Prepared in cooperation with the U.S. Army Corps of Engineers

U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2012–5263

Hydrogeologic Framework, Hydrology, and Water 

Quality in the Pearce Creek Dredge Material 

Containment Area and Vicinity, Cecil County, 

Maryland, 2010–11
Cover photograph: Pearce Creek Dredge Material Containment Area. Photograph taken by Cheryl A. Dieter, 2/13/2009.
Hydrogeologic Framework, Hydrology, and 

Water Quality in the Pearce Creek Dredge 

Material Containment Area and Vicinity, 

Cecil County, Maryland, 2010–11

By Cheryl A. Dieter, Michael T. Koterba, Otto S. Zapecza, Charles W. Walker, and 

Donald E. Rice

Prepared in cooperation with the U.S. Army Corps of Engineers

Scientific Investigations Report 2012–5263

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2013

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Suggested citation:

Dieter, C.A., Koterba, M.T., Zapecza, O.S., Walker, C.W., and Rice, D.E., 2013, Hydrogeologic framework, hydrology, 

and water quality in the Pearce Creek Dredge Material Containment Area and vicinity, Cecil County, Maryland, 

2010–11: U.S. Geological Survey Scientific Investigations Report 2012–5263, 219 p. with Appendixes

ISBN 978 1 4113 3526 4
iii

Contents

Abstract...........................................................................................................................................................1

Introduction.....................................................................................................................................................1

Purpose and Scope ..............................................................................................................................2

Previous Studies ...................................................................................................................................4

Description of Study Area ...................................................................................................................5

Well Numbering System......................................................................................................................5

History and Use.....................................................................................................................................5

Methods of Water-Quality Data Collection and Data Quality.................................................................5

Data-Collection Methods ....................................................................................................................6

Data Quality..........................................................................................................................................12

Contamination Bias: Field Blanks............................................................................................13

Measurement Uncertainty: Duplicate Samples ...................................................................13

Matrix Bias: Spiked Groundwater Samples ..........................................................................15

Measurement Accuracy: Standard Reference Samples and Ionic Mass Balances .....19

Hydrogeologic Framework.........................................................................................................................20

Well Network Design .........................................................................................................................20

Geologic Setting..................................................................................................................................21

Aquifers and Confining Units ............................................................................................................21

Potomac Group Aquifers ..........................................................................................................21

Upper Patapsco Aquifer...........................................................................................................22

Upper Patapsco Aquifer Deep Water-Bearing Zone...........................................................23

Confining Unit Between the Upper Patapsco Aquifer Shallow and Deep WaterBearing Zones...............................................................................................................23

Upper Patapsco Aquifer Shallow Water-Bearing Zone......................................................32

Upper Patapsco Confining Unit ...............................................................................................32

Magothy Aquifer........................................................................................................................32

Matawan Confining Unit and Fill .............................................................................................32

Chemical Composition of Sediments...............................................................................................33

Northern Chesapeake Bay Sediments...................................................................................33

Dredge Material Containment Area and Vicinity Sediments..............................................33

Sediment Chemistry Comparisons..........................................................................................34

Hydrology ......................................................................................................................................................38

Water-Level Synoptic Assessments and Continuous Data Collection ......................................38

Water Use ............................................................................................................................................40

Long-Term Water Levels....................................................................................................................40

Short-Term Water Levels...................................................................................................................40

Groundwater-Level Synoptic Assessments ...................................................................................42

Magothy Aquifer: May 19–20, 2010, Synoptic Assessment ................................................44

Magothy Aquifer: August 17–18, 2010, Synoptic Assessment ...........................................47

Magothy Aquifer: March 18, 2011, Synoptic Assessment. .................................................47

Upper Patapsco Aquifer Shallow Water-Bearing Zone: May 19–20, 2010, 

Synoptic Assessment ..................................................................................................47

Upper Patapsco Aquifer Shallow Water-Bearing Zone: August 17–18, 2010, 

Synoptic Assessment ..................................................................................................49
iv

Upper Patapsco Aquifer Shallow Water-Bearing Zone: March 18, 2011, 

Synoptic Assessment ..................................................................................................49

Upper Patapsco Aquifer Deep Water-Bearing Zone: May 19–20, 2010, 

Synoptic Assessment ..................................................................................................49

Upper Patapsco Aquifer Deep Water-Bearing Zone: August 17–18, 2010, 

Synoptic Assessment ..................................................................................................49

Perched Groundwater Zone: August 17–18, 2010, Synoptic Assessment........................49

Cross-Sectional Flow .........................................................................................................................57

Historical Perspective........................................................................................................................57

Water Quality................................................................................................................................................58

General Water-Quality Characteristics...........................................................................................60

Total Dissolved Solids and Major Ions ...................................................................................61

Bromide-Chloride Ratios ..........................................................................................................65

Total Dissolved Solids and General Patterns in Groundwater Flow..................................69

Electromagnetic-Induction Logging .......................................................................................76

Reduction-Oxidation Processes.......................................................................................................77

Historical Influences on Reduction-Oxidation Processes..................................................77

Terminal Electron Acceptor Process Analysis .....................................................................81

Dissolved Organic Carbon........................................................................................................82

Reduction-Oxidation Conditions and Processes..................................................................82

Mixed Reduction-Oxidation Processes and pH..................................................................108

Extended Implications of Reduction-Oxidation Processes on Groundwater Quality...113

Additional Water-Quality Indicators Illustrate Effect of Dredge Material Containment 

Area on Local Groundwater Quality.................................................................................114

Pesticides and Wastewater Compounds.............................................................................114

Low Level of Detection Pesticide Survey ............................................................................119

Wastewater Compound Survey.............................................................................................120

Quality of Water for Drinking-Water Supplies .............................................................................133

Maximum Contaminant Levels ..............................................................................................133

Health Advisory Levels............................................................................................................134

Secondary Drinking-Water Regulations ..............................................................................134

Acidity of Groundwater....................................................................................................................134

Influence on the Elk River.......................................................................................................134

Net Acidity.................................................................................................................................139

Integration of Findings ..............................................................................................................................140

Conclusions.................................................................................................................................................149

Acknowledgments.....................................................................................................................................149

References Cited........................................................................................................................................150

Appendixes A–C:........................................................................................................................................155

Appendix A.........................................................................................................................................156

Appendix B.........................................................................................................................................164

Appendix C.........................................................................................................................................172
v

Figures

1. Map showing location of the Pearce Creek Dredge Material Containment Area, 

Cecil County, Maryland................................................................................................................2

2. Map showing Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, 

Cecil County, Maryland, 2009......................................................................................................3

3. Map showing general topography and drainage characteristics of the study area 

before installation of the Pearce Creek Dredge Material Containment Area, 

Cecil County, Maryland, circa 1890............................................................................................6

4. Map showing general topography and drainage characteristics of the study area 

during the installation of the Pearce Creek Dredge Material Containment Area, Cecil 

County, Maryland, circa 1944......................................................................................................7

5. Map showing general topography and drainage characteristics of the study area 

after closure of the Pearce Creek Dredge Material Containment Area, Cecil County, 

Maryland, circa 1990s..................................................................................................................8

6. Map showing selected wells and surface-water sites used by the U.S. Geological 

Survey for water-quality data collection in the Pearce Creek Dredge Material 

Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11 ........................9

7. Map showing the monitoring well network, Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11 ....................................22

8. Maps showing A, Structure contours of the top of the upper Patapsco aquifer 

deep water-bearing zone, B, thickness of the confining unit between the upper 

Patapsco aquifer shallow and deep water-bearing zones, C, structure contours 

on the top of the upper Patapsco aquifer shallow water-bearing zone, and 

D, thickness of the upper Patapsco aquifer shallow water-bearing zone, in 

the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, 

Cecil County, Maryland, 2010–11..............................................................................................24

9. Maps showing A, Thickness of the upper Patapsco confining unit, B, structure 

contours on the top of the Magothy aquifer, C, thickness of the Magothy aquifer, 

and D, thickness of the Matawan confining unit in the Pearce Creek Dredge 

Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11 ......25

10. Map showing well locations and lines of hydrogeologic sections, Pearce Creek 

Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland ........26

11. Hydrogeologic section A–B, correlation based on gamma logs at boreholes (wells) 

indicated, Pearce Creek Dredge Material Containment Area and vicinity, 

Cecil County, Maryland..............................................................................................................27

12. Hydrogeologic section B–C, correlation based on gamma logs at boreholes (wells) 

indicated, Pearce Creek Dredge Material Containment Area and vicinity, 

Cecil County, Maryland..............................................................................................................28

13. Hydrogeologic section A–E, correlation based on gamma logs at boreholes (wells) 

indicated, Pearce Creek Dredge Material Containment Area and vicinity, 

Cecil County, Maryland..............................................................................................................29

14. Hydrogeologic section D–E, correlation based on gamma logs at boreholes (wells) 

indicated, Pearce Creek Dredge Material Containment Area and vicinity, 

Cecil County, Maryland..............................................................................................................30

15. Hydrogeologic section F–G, correlation based on gamma logs at boreholes (wells) 

indicated, Pearce Creek Dredge Material Containment Area and vicinity, Cecil 

County, Maryland........................................................................................................................31
vi

16. Map showing selected wells used by the U.S. Geological Survey for water-level 

data collection and the location of lines of section for groundwater flow A–A’ and 

B–B’ in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, 

Cecil County, Maryland..............................................................................................................39

17. Map showing observation wells and lake gage with installed water-level transducer, 

Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, 

Maryland ......................................................................................................................................43

18. Graph showing altitude of water levels in well CE Dd 81 near Pearce Creek 

Dredge Material Containment Area (DMCA), Cecil County, Maryland, 

March 1983–June 2011 ..............................................................................................................44

19. Graph showing average daily altitude of water levels in observation wells in the 

Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil 

County, Maryland, January 2010–February 2011...................................................................45

20. Graph showing altitude of water levels in observation wells and Pearce Creek 

Lake from September 26–October 6, 2010, in the Pearce Creek Dredge Material 

Containment Area (DMCA) and vicinity, Cecil County, Maryland.......................................46

21. Map showing potentiometric surface of the Magothy aquifer, May 19–20, 2010, in 

the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil 

County, Maryland........................................................................................................................48

22. Map showing potentiometric surface of the Magothy aquifer, August 17–18, 2010, 

in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, 

Cecil County, Maryland..............................................................................................................50

23. Map showing potentiometric surface of the Magothy aquifer, March 18, 2011, in 

the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil 

County, Maryland........................................................................................................................51

24. Map showing potentiometric surface of the upper Patapsco aquifer shallow water-

bearing zone, May 19–20, 2010, in the Pearce Creek Dredge Material Containment 

Area (DMCA) and vicinity, Cecil County, Maryland ..............................................................52

25. Map showing potentiometric surface of the upper Patapsco aquifer shallow water-

bearing zone, August 17–18, 2010, in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland ....................................................53

26. Map showing potentiometric surface of the upper Patapsco aquifer shallow water-

bearing zone, March 18, 2011, in the Pearce Creek Dredge Material Containment 

Area (DMCA) and vicinity, Cecil County, Maryland ..............................................................54

27. Map showing potentiometric surface of the upper Patapsco aquifer deep water-

bearing zone, May 19–20, 2010, in the Pearce Creek Dredge Material Containment 

Area (DMCA) and vicinity, Cecil County, Maryland ..............................................................55

28. Map showing potentiometric surface of the upper Patapsco aquifer deep 

water-bearing zone, August 17–18, 2010, in the Pearce Creek Dredge Material 

Containment Area (DMCA) and vicinity, Cecil County, Maryland.......................................56

29. Map showing potentiometric surface of a perched groundwater zone, August 17–18, 

2010, in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, 

Cecil County, Maryland..............................................................................................................58

30. Hydrogeologic section showing groundwater altitudes and flow directions along 

line A–A', May 2010, in the Pearce Creek Dredge Material Containment Area and 

vicinity, Cecil County, Maryland ...............................................................................................59

31. Hydrogeologic section showing groundwater altitudes and flow directions along 

line B–B', May 2010, in the Pearce Creek Dredge Material Containment Area and 

vicinity, Cecil County, Maryland ...............................................................................................60
vii

32. Map showing wells completed in the Magothy and upper Patapsco aquifers with 

available groundwater data which appear to be not overly affected by human 

activities or land use near the Pearce Creek Dredge Material Containment Area 

and vicinity, Cecil County, Maryland .......................................................................................62

33. Trilinear diagram for samples with A, total dissolved solids less than 300 milligrams 

per liter (mg/L) and B, total dissolved solids greater than 300 mg/L collected in 

the Pearce Creek Dredge Material Containment Area and vicinity, Cecil County, 

Maryland ......................................................................................................................................64

34. Map showing concentrations of total dissolved solids in water-quality samples 

collected from selected surface waters and selected wells completed in the 

perched water-bearing zone or Magothy aquifer in the Pearce Creek Dredge 

Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11 ......66

35. Map showing concentrations of total dissolved solids in water-quality samples 

collected from selected surface waters and selected wells completed in the upper 

Patapsco aquifer shallow water-bearing zone in the Pearce Creek Dredge Material 

Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11 ......................67

36. Map showing concentrations of total dissolved solids in water-quality samples collected from selected surface waters and selected wells completed in the upper 

Patapsco aquifer deep water-bearing zone in the Pearce Creek Dredge Material 

Containment Area and vicinity, Cecil County, Maryland, 2010–11......................................68

37. Graph showing ratios of the concentration of bromide to the concentration of 

chloride as a function of the concentration of chloride for selected surface- and 

groundwater samples collected in the Pearce Creek Dredge Material Containment 

Area (DMCA) and vicinity, Cecil County, Maryland, 1995–96 ..............................................69

38. Graph showing ratios of the concentration of bromide to the concentration of 

chloride as a function of the concentration of chloride for selected surface- and 

groundwater samples collected in the Pearce Creek Dredge Material Containment 

Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11 ..............................................70

39. Map showing selected wells used by the U.S. Geological Survey for water-quality 

descriptions along sections A–A’, B–B’, and C–C’ in the Pearce Creek Dredge 

Material Containment Area (DMCA) and vicinity, Cecil County, Maryland ......................71

40. Hydrogeologic section showing ratios of the concentration of bromide to the 

concentration of chloride in water-quality samples along line A–A'and collected 

from selected surface waters, and from selected wells completed in the perched 

water-bearing zone Magothy aquifer, or upper Patapsco aquifer shallow or deep 

water-bearing zone in the Pearce Creek Dredge Material Containment Area 

(DMCA) and vicinity, Cecil County, Maryland, 2010–11........................................................72

41. Hydrogeologic section showing concentrations of total dissolved solids in waterquality samples along line A–A’ and collected from selected surface waters, and 

from selected wells completed in the perched water-bearing zone Magothy aquifer, 

or upper Patapsco aquifer shallow or deep water-bearing zone in the Pearce 

Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, 

Maryland, 2010–11......................................................................................................................73

42. Hydrogeologic section showing concentrations of total dissolved solids in waterquality samples along line B–B’ and collected from selected wells completed in 

the Magothy aquifer or upper Patapsco aquifer shallow or deep water-bearing 

zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, 

Cecil County, Maryland, 2010–11..............................................................................................74

43. Hydrogeologic section showing concentrations of total dissolved solids in waterquality samples along line C–C’ and collected from selected surface waters and 

from selected wells completed in the Magothy aquifer or upper Patapsco aquifer 

shallow or deep water-bearing zone in the Pearce Creek Dredge Material 

Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11 ......................78
viii

44. Hydrogeologic section showing electromagnetic-induction logs, total dissolved 

solids concentrations (in milligrams per liter), and hydrogeology along line A–B..........79

45. Hydrogeologic section showing electromagnetic-induction logs, total dissolved 

solids concentrations (in milligrams per liter), and hydrogeology along line B–C..........80

46. Map showing concentrations of dissolved organic carbon in water-quality samples 

collected from selected surface waters and from selected wells completed in the 

perched water-bearing zone or Magothy aquifer in the Pearce Creek Dredge 

Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11 ......85

47. Map showing concentrations of dissolved organic carbon in water-quality samples 

collected from selected surface waters and from selected wells completed in the 

upper Patapsco aquifer shallow water-bearing zone in the Pearce Creek Dredge 

Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11 ......86

48. Hydrogeologic section showing concentrations of dissolved organic carbon 

in water-quality samples along line A–A’ and collected from selected surface 

waters and from selected wells completed in the perched water-bearing zone, 

Magothy aquifer, or upper Patapsco aquifer shallow or deep water-bearing zone 

in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, 

Cecil County, Maryland, 2010–11..............................................................................................87

49. Map showing predominant reduction-oxidation conditions and processes associated 

with selected surface waters and with selected wells completed in the perched 

water-bearing zone or Magothy aquifer in the Pearce Creek Dredge Material 

Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11 ......................88

50. Hydrogeologic section showing concentrations of dissolved oxygen in water-

quality samples along line A–A’ and collected from selected surface waters and 

from selected wells completed in the perched water-bearing zone, Magothy 

aquifer, or upper Patapsco aquifer shallow or deep water-bearing zone in the 

Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil 

County, Maryland, 2010–11........................................................................................................90

51. Hydrogeologic section showing concentrations of dissolved nitrate plus nitrite 

nitrogen in water-quality samples along line A–A’ and collected from selected 

surface waters and selected wells completed in the perched water-bearing zone, 

Magothy aquifer, or upper Patapsco aquifer shallow or deep water-bearing zone 

in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, 

Cecil County, Maryland, 2010–11..............................................................................................91

52. Map showing concentrations of dissolved ammonia nitrogen in water-quality 

samples collected from selected surface waters and from selected wells 

completed in the perched water-bearing zone or Magothy aquifer in the Pearce 

Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, 

Maryland, 2010–11......................................................................................................................92

53. Map showing concentrations of dissolved ammonia nitrogen in water-quality 

samples collected from selected surface waters and from selected wells 

completed in the upper Patapsco aquifer shallow water-bearing zone in the Pearce 

Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, 

Maryland, 2010–11......................................................................................................................93

54. Hydrogeologic section showing concentrations of dissolved ammonia nitrogen in 

water-quality samples along line A–A’ and collected from selected surface waters 

and from selected wells completed in the perched water-bearing zone, Magothy 

aquifer, or upper Patapsco aquifer shallow or deep water-bearing zone in the 

Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil 

County, Maryland, 2010–11........................................................................................................94
ix

55. Hydrogeologic section showing concentrations of dissolved manganese in water-

quality samples along line A–A’ and collected from selected surface waters and 

from selected wells completed in the perched water-bearing zone Magothy aquifer, 

or upper Patapsco aquifer shallow or deep water-bearing zone in the Pearce Creek 

Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 

2010–11 .........................................................................................................................................95

56. Map showing concentrations of dissolved manganese in water-quality samples 

collected from selected surface waters and from selected wells completed in the 

perched water-bearing zone or Magothy aquifer in the Pearce Creek Dredge 

Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11 ......96

57. Hydrogeologic section showing concentrations of dissolved iron in water-quality 

samples along line A–A’ and collected from selected surface waters and from 

selected wells completed in the perched water-bearing zone Magothy aquifer, or 

upper Patapsco aquifer shallow or deep water-bearing zone in the Pearce Creek 

Dredge Material Containment Area and vicinity, Cecil County, Maryland, 2010–11 .......97

58. Map showing concentrations of dissolved iron in water-quality samples collected 

from selected surface waters and from selected wells completed in the perched 

water-bearing zone or Magothy aquifer in the Pearce Creek Dredge Material 

Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11 ......................98

 59. Map showing concentrations of dissolved iron in water-quality samples collected 

from selected surface waters and from selected wells completed in the upper 

Patapsco aquifer shallow water-bearing zone in the Pearce Creek Dredge 

Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11 ......99

60. Map showing concentrations of dissolved sulfate in water-quality samples collected 

from selected surface waters and from selected wells completed in the perched 

water-bearing zone or Magothy aquifer in the Pearce Creek Dredge Material 

Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11 ....................100

61. Map showing concentrations of dissolved sulfate in water-quality samples collected 

from selected surface waters and from selected wells completed in the upper 

Patapsco aquifer shallow water-bearing zone in the Pearce Creek Dredge 

Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11 ....101

62. Map showing predominant reduction-oxidation conditions and processes 

associated with selected surface waters and with selected wells completed 

in the upper Patapsco aquifer shallow water-bearing zone in the Pearce Creek 

Dredge Material Containment Area (DMCA) and vicinity, Cecil County, 

Maryland, 2010–11....................................................................................................................103

63. Map showing concentrations of dissolved manganese in water-quality samples 

collected from selected surface waters and from selected wells completed in 

the upper Patapsco aquifer shallow water-bearing zone in the Pearce Creek 

Dredge Material Containment Area (DMCA) and vicinity, Cecil County, 

Maryland, 2010–11....................................................................................................................104

64. Map showing predominant reduction-oxidation conditions and processes 

associated with selected surface waters and with selected wells completed 

in the upper Patapsco aquifer deep water-bearing zone in the Pearce Creek 

Dredge Material Containment Area (DMCA) and vicinity, Cecil County, 

Maryland, 2010–11....................................................................................................................105

65. Hydrogeologic section showing concentrations of dissolved sulfate in water-

quality samples along line A–A’ and collected from selected surface waters and 

from selected wells completed in the perched water-bearing zone, Magothy 

aquifer, or upper Patapsco aquifer shallow or deep water-bearing zone in the 

Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil 

County, Maryland, 2010–11......................................................................................................106
x

66. Hydrogeologic section showing the predominant reduction-oxidation conditions 

and processes along line A–A’ associated with selected surface waters and with 

selected wells completed in the perched water-bearing zone, Magothy aquifer, or 

upper Patapsco aquifer shallow or deep water-bearing zone in the Pearce Creek 

Dredge Material Containment Area (DMCA) and vicinity, Cecil County, 

Maryland, 2010–11....................................................................................................................107

67. Hydrogeologic section showing the predominant reduction-oxidation conditions 

and processes along line C–C’ and collected from selected surface waters and 

selected wells completed in the perched water-bearing zone, Magothy aquifer, or 

upper Patapsco aquifer shallow or deep water-bearing zone in the Pearce Creek 

Dredge Material Containment Area (DMCA) and vicinity, Cecil County, 

Maryland, 2010–11....................................................................................................................109

68. Hydrogeologic section showing the predominant reduction-oxidation conditions 

and processes along line B–B’ associated with selected wells completed in the 

Magothy aquifer or in the upper Patapsco aquifer shallow or deep water-bearing 

zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, 

Cecil County, Maryland, 2010–11............................................................................................110

69. Hydrogeologic section showing the pH in water-quality samples along line A–A’

and collected from selected surface waters and from selected wells completed 

in the perched water-bearing zone, Magothy aquifer, or upper Patapsco aquifer 

shallow or deep water-bearing zone in the Pearce Creek Dredge Material 

Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11 ....................111

70. Hydrogeologic section showing the pH in water-quality samples along line C–C’ and 

collected from selected surface waters and from selected wells completed in the 

Magothy aquifer or upper Patapsco aquifer shallow or deep water-bearing zone 

in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil 

County, Maryland, 2010–11......................................................................................................112

71. Hydrogeologic section showing concentrations of dissolved aluminum in water-

quality samples along line A–A’ and collected from selected surface waters and 

from selected wells completed in the perched water-bearing zone, Magothy 

aquifer, or upper Patapsco aquifer shallow or deep water-bearing zone in the 

Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil 

County, Maryland, 2010–11......................................................................................................115

72. Map showing concentrations of dissolved beryllium in water-quality samples 

collected from selected surface waters and from selected wells completed in 

the upper Patapsco aquifer shallow water-bearing zone in the Pearce Creek 

Dredge Material Containment Area (DMCA) and vicinity, Cecil County, 

Maryland, 2010–11....................................................................................................................116

73. Hydrogeologic section showing concentrations of dissolved beryllium in water-

quality samples along line A–A’ and collected from selected surface waters and 

from selected wells completed in the Magothy aquifer or upper Patapsco aquifer 

shallow or deep water-bearing zone in the Pearce Creek Dredge Material 

Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11 ....................117

74. Map showing concentrations of dissolved arsenic in water-quality samples 

collected from selected surface waters and from selected wells completed in the 

upper Patapsco aquifer shallow water-bearing zone in the Pearce Creek Dredge 

Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11 ....118

75. Map showing the number of pesticides detected with low-level analytical methods 

in water-quality samples collected from selected surface waters and from survey 

wells completed in the perched water-bearing zone or Magothy aquifer in the 

Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil 

County, Maryland, 2010–11......................................................................................................126
xi

76. Hydrogeologic section showing the number of pesticides detected with low-level 

analytical methods in water-quality samples along line A–A’ and collected from 

survey wells completed in the Magothy aquifer or upper Patapsco aquifer shallow 

or deep water-bearing zone in the Pearce Creek Dredge Material Containment 

Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11 ............................................127

77. Hydrogeologic section showing the number of pesticides detected with low-level 

methods in water-quality samples along line B–B’ and collected from survey 

wells completed in the Magothy aquifer in the Pearce Creek Dredge Material 

Containment Area (DMCA) and vicnity, Cecil County, Maryland, 2010–11 .....................128

78. Map showing the number of pesticides detected with low-level analytical methods 

in water-quality samples collected from selected surface waters and from survey 

wells completed in the upper Patapsco aquifer shallow water-bearing zone in 

the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil 

County, Maryland, 2010–11......................................................................................................129

79. Map showing the number of wastewater compounds detected in water-quality 

samples collected from selected surface waters and from survey wells completed 

in the perched groundwater zone or Magothy aquifer in the Pearce Creek Dredge 

Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11 ....130

80. Map showing the number of wastewater compounds detected in water-quality 

samples collected from selected surface waters and from survey wells 

completed in the upper Patapsco aquifer shallow water-bearing zone in the 

Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil 

County, Maryland, 2010–11......................................................................................................131

81. Hydrogeologic section showing the number of wastewater compounds detected in 

water-quality samples along line A–A’ and collected from selected surface waters 

and from selected wells completed in the perched water-bearing zone, Magothy 

aquifer, or upper Patpsco aquifer shallow or deep water-bearing zone in the Pearce 

Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, 

Maryland, 2010–11....................................................................................................................132

82. Map showing net acidity in water-quality samples from selected surface waters 

and from selected wells completed in the perched water-bearing zone or Magothy 

aquifer in the Pearce Creek Dredge Material Containment Area (DMCA) and 

vicinity, Cecil County, Maryland, 2010–11.............................................................................141

83. Map showing net acidity in water-quality samples from selected surface waters 

and from selected wells completed in the upper Patapsco aquifer shallow waterbearing zone in the Pearce Creek Dredge Material Containment Area (DMCA) and 

vicinity, Cecil County, Maryland, 2010–11.............................................................................142

84. Hydrogeologic section showing net acidity in water-quality samples along line 

A–A’ from selected surface waters and from selected wells completed in the 

perched water-bearing zone, Magothy aquifer, or upper Patapsco aquifer shallow 

or deep watering-bearing zone in the Pearce Creek Dredge Material Containment 

Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11 ............................................143

85. Hydrogeologic section showing the net acidity in water-quality samples along line 

C–C’ from selected surface waters and from selected wells completed in the 

perched water-bearing zone, Magothy aquifer, or upper Patapsco aquifer shallow 

or deep watering-bearing zone in the Pearce Creek Dredge Material Containment 

Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11 ............................................144

86. Hydrogeologic section showing the net acidity in water-quality samples along 

line B–B’ and from selected wells completed in the Magothy aquifer or upper 

Patapsco aquifer shallow or deep watering-bearing zone in the Pearce Creek 

Dredge Material Containment Area (DMCA) and vicinity, Cecil County, 

Maryland, 2010–11....................................................................................................................145
xii

Tables

1. Stability criteria used for water-quality parameters during water-quality sampling 

in the Pearce Creek Dredge Material Containment Area and vicinity, 2010–11 ..............10

2. Contamination bias: Summary of evaluation of field-blank quality-control data for 

water-quality samples collected in the Pearce Creek Dredge Material Containment 

Area and vicinity, 2010–11 .........................................................................................................14

3. Measurement precision: Summary statistics for the relative differences in measurements between duplicate samples, by constituent types, obtained from the analyses 

of sequential groundwater samples collected in the Pearce Creek Dredge Material 

Containment Area and vicinity, 2010........................................................................................15

4. Matrix bias: Summary statistics for the recovery of pesticides on the basis of 

U.S. Geological Survey Organic Chemistry Research Laboratory low-level analytical 

methods and laboratory spikes for groundwater samples collected in the Pearce 

Creek Dredge Material Containment Area and vicinity, 2010..............................................16

5. Summary statistics for spike and surrogate recoveries for selected pesticides and 

other wastewater compounds in groundwater samples collected in the Pearce 

Creek Dredge Material Containment Area and vicinity, 2010–11 .......................................19

6. Measurement accuracy: Equivalence mass balance errors for groundwater samples 

collected in the Pearce Creek Dredge Material Containment Area and vicinity, 

2010–11 .........................................................................................................................................20

7. Stratigraphic correlation chart of geologic and hydrogeologic units in the Pearce 

Creek Dredge Material Containment Area and vicinity .......................................................23

8. Summary data on the chemical composition of shallow Chesapeake Bay sediments 

and pore water from fresh sediment-core samples, 2005–06.............................................35

9. Summary data on chemical composition of sediments in and underlying the Pearce 

Creek Dredge Material Containment Area from sediment-core samples obtained 

from selected boreholes, 1995–96 ...........................................................................................36

10. Summary data on chemical composition of sediments in the vicinity of the Pearce 

Creek Dredge Material Containment Area from sediment-core samples obtained 

from selected boreholes, 1995–96 ...........................................................................................37

11. Wells in the Pearce Creek Dredge Material Containment Area and vicinity in which 

water levels were measured during the May 2010, August 2010, and March 2011 

synoptic assessments to delineate the potentiometric surface in three aquifers ..........41

12. Chemical characteristics of natural water and water affected by residential 

activities in the surficial aquifer of the Delmarva Peninsula...............................................61

13. Available groundwater-quality data that do not appear to be overly affected by 

any land use in the Magothy and upper Patapsco aquifers in the Pearce Creek 

Dredge Material Containment Area and vicinity...................................................................63

14. Terminal electron acceptor classification criteria for redox categories and 

processes, and related reduction reactions, assigned on the basis of water-quality 

data obtained from groundwater samples collected in the Pearce Creek Dredge 

Material Containment Area and vicinity, 2010–11.................................................................83

15. Classification of redox categories and processes assigned on the basis of waterquality data obtained from groundwater and surface-water samples collected in 

the Pearce Creek Dredge Material Containment Area and vicinity, 2010–11 ..................84

16. Summary of pesticides detected with low-level analytical methods in groundwater 

and surface-water samples collected in the Pearce Creek Dredge Material 

Containment Area and vicinity, 2010–11 ...............................................................................119
xiii

17. Characteristics and summary of detections of organic wastewater compounds 

associated with groundwater samples collected from selected wells in the Pearce 

Creek Dredge Material Containment Area (DMCA) and vicinity, 2010 ............................121

18. Summary of water-quality constituents with concentrations exceeding 2009 U.S. 

Environmental Protection Agency Safe Drinking Water Act standards for at least 

one groundwater or surface-water site in the Pearce Creek Dredge Material 

Containment Area and vicinity, Maryland, 2010–11............................................................135

19. Reduction-oxidation conditions and processes and Federal Safe Drinking Water 

Act exceedances for domestic groundwater supplies in the Pearce Creek Dredge 

Material Containment Area and vicinity, 2010–11...............................................................138

Conversion Factors and Datums 

Inch/Pound to SI

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

acre 4,047 square meter (m2

)

Volume

gallon (gal) 3.785 liter (L) 

cubic yard (yd3

) 0.7646 cubic meter (m3) 

Flow rate

gallon per minute (gal/min) 0.06309 liter per second (L/s)

million gallons per day (Mgal/d) 0.04381 cubic meter per second (m3

/s)

inch per year (in/yr) 25.4 millimeter per year (mm/yr)

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows: 

°F=(1.8×°C)+32

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD 88).

Horizontal coordinate information is referenced to the North American Datum of 1983 

(NAD 83).

Altitude, as used in this report, refers to distance above the vertical datum.

Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius 

(μS/cm at 25 °C).

Concentrations of chemical constituents in water are given either in milligrams per liter 

(mg/L) or micrograms per liter (μg/L).
xiii

Abbreviations and Acronyms

BQS Branch of Quality Systems of the U.S. Geological Survey

BVE Bay View Estates residential community

C&D Canal Chesapeake and Delaware Canal

DMCA Dredge Material Containment Area

DOC dissolved organic carbon

HAL health advisory level

LRL laboratory reporting level

MB mass balance

MCL maximum contaminant level

MES Maryland Environmental Service

MPMV most probable median value

NAVD 88 North American Vertical Datum of 1988

NFM National Field Manual of the U.S. Geological Survey

NGVD 29 National Geodetic Vertical Datum of 1929

NTRU nephelometric turbidity ratio units

NWIS National Water Information System

NWQL National Water Quality Laboratory of the U.S. Geological Survey

OGRL Organic Geochemistry Research Laboratory of the U.S. Geological Survey

PAH polyaromatic hydrocarbon

QC quality control

RSD relative sample difference

SC specific conductance

SDWA Federal Safe Drinking Water Act

SDWR Secondary Drinking Water Regulations

SRS standard reference sample

SSSPD submersible, stainless-steel, positive-displacement pump

TDS total dissolved solids

TEAP terminal electron acceptor process

UPA upper Patapsco aquifer

USACE U.S. Army Corps of Engineers

USEPA U.S. Environmental Protection Agency

USGS U.S. Geological Survey

WSC Water Science Center of the U.S. Geological Survey

WVS West View Shores residential community
Abstract

In 2009, to support an evaluation of the feasibility of 

reopening the Pearce Creek Dredge Material Containment 

Area (DMCA) in Cecil County, Maryland, for dredge-spoil 

disposal, the U.S. Geological Survey (USGS) began to implement a comprehensive study designed to improve the understanding of the hydrogeologic framework, hydrology, and 

water quality of shallow aquifers underlying the DMCA and 

adjacent communities, to determine whether or not the DMCA 

affected groundwater quality, and to assess whether or not 

groundwater samples contained chemical constituents at levels 

greater than maximum allowable or recommended levels 

established by the U.S. Environmental Protection Agency Safe 

Drinking Water Act. 

The study, conducted in 2010–11 by USGS in cooperation with the U.S. Army Corps of Engineers, included 

installation of observation wells in areas where data gaps led 

earlier studies to be inconclusive. The data from new wells 

and existing monitoring locations were interpreted and show 

the DMCA influences the groundwater flow and quality. 

Groundwater flow in the two primary aquifers used for local 

supplies—the Magothy aquifer and upper Patapsco aquifer 

(shallow water-bearing zone)—is radially outward from the 

DMCA toward discharge areas, including West View Shores, 

the Elk River, and Pearce Creek Lake. In addition to horizontal flow outward from the DMCA, vertical gradients primarily 

are downward in most of the study area, and upward near the 

Elk River on the north side of the DMCA property, and the 

western part of West View Shores. Integrating groundwater 

geochemistry data in the analysis, the influence of the DMCA 

is not only a source of elevated concentrations of dissolved 

solids but also a geochemical driver of redox processes that 

enhances the mobilization and transport of redox-sensitive 

metals and nutrients. Groundwater affected by the DMCA is 

in the Magothy aquifer and upper Patapsco aquifer (shallow 

water-bearing zone). Based on minimal data, the water quality 

in the upper Patapsco aquifer deep water-bearing zone does 

not seem to have been impacted by the DMCA.

Introduction

The U.S. Army Corps of Engineers (USACE), Philadelphia District’s mission includes managing the water resources 

of the Delaware River basin. The agency is responsible for 

maintaining a navigable channel for large ocean-going and 

smaller vessels along the Chesapeake and Delaware Canal 

(C&D Canal) (fig. 1). The C&D Canal allows shipping vessels to go from the Delaware River to the Chesapeake Bay, 

and ultimately to the Port of Baltimore, thereby reducing the 

300-mi (mile) trip south along the Atlantic Coast of Delaware, 

Maryland, and Virginia to the mouth of the Chesapeake Bay, 

and from there north in the bay to the Port of Baltimore. The 

C&D Canal became navigable in 1829, albeit the canal was 

much narrower than it is today.

To maintain navigability, the C&D Canal periodically 

(generally annually or biennially) needs to be dredged, and 

the dredged material disposed. Dredging and disposal of this 

dredged material is the responsibility of the USACE. The 

USACE acquired a total of 996 acres of land, which is referred 

to in this report as the Pearce Creek Dredge Material Containment Area (DMCA) property, in 1937 as part of new (then) 

dredging work to deepen the C&D Canal (T. Kelly, USACE, 

written commun., 2012). In 1937, perimeter dikes were built 

around an area of approximately 260 acres, which is referred 

to in this report as the DMCA (bermed area), and a sluice 

was constructed that would allow water to leave the bermed 

area and flow into Pearce Creek. Subsequently, an additional 

sluice was constructed near the mouth of Pearce Creek, which 

limited the discharge from Pearce Creek to the Elk River and 

created what is referred to in this report as Pearce Creek Lake. 

Dredge materials were placed in the DMCA bermed area at 

the site in 1937 and 1938, and then again from the 1960s until 

the last placement of materials in 1993 (T. Kelly, USACE, 

written commun., 2012). In 1989, the dikes at the DMCA were 

raised to their current (2010–11) elevation, approximately 35 

to 40 ft (feet) relative to the North American Vertical Datum of 

1988 (NAVD 88), by bulldozing sediment within the DMCA 

bermed area to build the higher dikes (T. Kelly, USACE, 

written commun., 2012). It is estimated that 4.0 million cubic 

Hydrogeologic Framework, Hydrology, and Water Quality 

in the Pearce Creek Dredge Material Containment Area 

and Vicinity, Cecil County, Maryland, 2010–11

By Cheryl A. Dieter, Michael T. Koterba, Otto S. Zapecza, Charles W. Walker, and Donald E. Rice
2 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

yards of material was placed at the DMCA during this time 

(T. Kelly, USACE, written commun., 2012). 

Since 1993, the USACE has placed dredge materials at 

open-water sites, such as Pooles Island, located 18 mi to the 

southwest of the DMCA, in the Chesapeake Bay. In preparation for the closure of all open-water disposal sites in the 

Chesapeake Bay by the State of Maryland on December 31, 

2010, the USACE began looking for alternative disposal 

locations. Pearce Creek DMCA is the preferred option for the 

USACE because of its available capacity and proximity to the 

C&D Canal, which will result in lower dredging, transport, 

and placement costs than alternatives such as Court House 

Point or Poplar Island, 7 mi to the northeast and 50 mi to the 

south of the DMCA, respectively (D. Sirkis, USACE, written 

commun., 2009).

The USACE asked the U.S. Geological Survey (USGS) 

to conduct a study of the Pearce Creek DMCA and vicinity 

(fig. 2), to define the hydrogeologic framework, and to determine groundwater flow directions both laterally and vertically 

in the shallow groundwater flow system. The USACE also 

asked the USGS to determine whether or not chemical constituents in groundwater were greater than maximum allowable 

and (or) recommended U.S. Environmental Protection Agency 

(USEPA) Safe Drinking Water Act (SDWA) standards in 

(1) shallow private domestic wells adjacent to the DMCA, 

(2) shallow groundwater between the DMCA and Elk River, 

and (3) shallow groundwater upgradient of the DMCA. The 

final task was to determine whether or not the DMCA has 

affected groundwater quality adjacent to the site. In 2010, the 

USGS began an investigation of the Pearce Creek DMCA and 

vicinity. The results of the investigation are presented in this 

report.

Purpose and Scope

The purpose of this report is twofold: first, to present 

the results of the USGS study to describe the hydrogeologic 

framework, hydrology, and quality of groundwater in the 

USACE Pearce Creek DMCA and vicinity; and second, to 

assess whether or not the DMCA has affected the quality of 

groundwater for domestic drinking-water supplies in the vicinity of the DMCA. Understanding the interrelations among the 

hydrogeologic setting, groundwater flow, and groundwater 

quality are critical to understanding and illustrating the effect 

of the DMCA on drinking-water supplies in the study area. 

Thus, this report includes a description of the hydrogeology, 

Figure 1. Location of the Pearce Creek Dredge Material Containment Area, Cecil County, Maryland. 

Chester

River

Unicorn Br.

Elk

River

Little Elk Cr.

Big Elk Cr.

Sassafras River

Patapsco River

Bush

R.

Gunpowder R.

Middle R.

Loch Raven

 Reservoir

Deer

Creek

Prettyboy

Reservoir

Western

Gunpowder

Falls

Run

Gunpowder

Little

Falls

Pearce Creek Delaware River

H A R F O R D

K E N T

 Aberdeen

 Proving

Ground

Poole's

Island

Q U E E N

A N N E' S

Elkton

Chesapeake and

Delaware Canal

Chestertown

Earleville

PENNSYLVANIA

MARYLAND

MARYLAND

DELAWARE

C E C I L

B A L T I M O R E

 A N N E

A R U N D E L

BALTIMORE

 CITY

NEW

JERSEY

Bel Air

Towson

Ellicott 

City

Susquehanna River

Dover CHESAPEAKE BAY

Pearce Creek 

Dredge Material

Containment Area

695

695

83

70

95

95

PENNSYLVANIA

WEST 

VIRGINIA

VIRGINIA

DE

NJ

WASHINGTON,

D.C.

MAP 

AREA

MARYLAND

 ATLANTIC 

 OCEAN

DELAWARE

 BAY

Potomac

River

Pearce Creek Dredge Material

Containment Area

CHESAPEAKE BAY

Base from U.S. Geological Survey digital data, 2008, 1:1,000,000

from GCS WGS 1984 to NAD 1983 UTM ZONE 18N

Transverse Mercator projection

0

0 10 KILOMETERS

10 MILES

39°

39°

39°

30'

45'

15'

76°30' 76°00' 75°30'

Study

area
Introduction 

3

Elk River Pearce Creek Lake Property boundary of Pearce Creek Dredge Material Containment Area 

Perimeter dike

West View Shores

Crystal Beach

Bay View Estates

Pond Neck Road

39°26’

76° 75°59’ 75°58’

39°25’

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

Elevation in feet

EXPLANATION

High: 90Low: 0

Figure 2. Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2009.
4 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

which serves as the framework to describe the groundwater 

hydrology in the study area. The description of the groundwater hydrology includes a discussion of factors affecting temporal and spatial variations in groundwater levels and patterns 

in flow in the major water-bearing zones used for groundwater 

supplies in the study area. In turn, the described patterns in 

both horizontal and vertical groundwater flow form the basis 

for a discussion of the general chemistry of groundwater in the 

study area. The general chemistry of groundwater is developed 

and described based on surface-water samples and groundwater samples collected from observation and water-supply wells 

in the study area. The data obtained from these wells documenting groundwater quality also are evaluated to determine if 

concentrations of chemical constituents are greater than maximum allowable or recommended levels established by the U.S. 

Environmental Protection Agency Safe Drinking Water Act. 

The hydrogeologic framework, hydrology, and groundwater 

quality are then integrated to present the overall interpretation, 

or understanding, of groundwater sources, flow, and quality in 

the study area. An “integration of findings” section provides 

the synopsis of major findings. A set of appendixes provides 

details of the data-collection methods and the data resulting 

from the study.

Previous Studies

Various studies were conducted at the Pearce Creek 

DMCA in the 1990s after the last dredge materials were placed 

in 1993. There were concerns by local residents and Maryland State regulators that the DMCA had contributed to poor 

groundwater quality in the communities surrounding the site.

Maryland Environmental Service (MES) conducted a 

Phase I study of the local groundwater chiefly on the basis of 

available data and information for the Maryland Port Administration and the USACE (Maryland Environmental Service, 

1995). They compared groundwater-quality data from the 

local community to groundwater-quality data available for the 

DMCA, Crystal Beach, and the relevant surficial and confined 

aquifers in Cecil County, Md. They also compared selected 

water-quality parameters for groundwater and surface water 

(for example, Elk River, Pearce Creek Lake outlet, and DMCA 

effluent). MES (1995) concluded that groundwater in some 

domestic-supply wells in the West View Shores (WVS) community yielded elevated concentrations of metals (manganese, 

iron, calcium, sodium, and potassium), sulfate, and chloride. 

Wells with elevated concentrations of metals, sulfate, and 

chloride chiefly were completed at elevations of approximately 

–50 to –100 ft NAVD 88. (NAVD 88 is the vertical datum to 

which altitudes are referenced in this report. Sea level is similar, but not exactly 0 ft NAVD 88.) The concentrations in the 

wells located in WVS differed from typical existing groundwater concentrations in relation to Crystal Beach and to the 

relevant aquifers in Cecil County, Md. The MES (1995) also 

presented evidence that the elevated concentrations appeared 

related to the oxidation of sulfide-rich sediments. Identification 

of the source(s) of the elevated concentrations in groundwater 

and the sulfide-rich sediments were inconclusive. MES (1995) 

was not able to determine whether elevated concentrations of 

metals, sulfate, and chloride in groundwater reflected brackish water that intruded from Elk River or Chesapeake Bay, 

groundwater that flowed from the DMCA, or acidic groundwater from either of the above or other sources that reacted 

with in-situ sediments. Insufficient data on the hydrogeology, 

sediment, and groundwater chemistry, as well as groundwater 

flow in and near the WVS community resulted in the inability 

to identify the source(s) of the elevated concentrations of metals, sulfate, and chloride in their domestic-supply wells.

As a followup to the MES (1995) report, Black & Veatch 

Special Projects Corporation was contracted by the USACE 

to prepare a work plan and conduct a second Phase I study to 

determine the groundwater flow system in the Pearce Creek 

DMCA and collect geochemical data below the Pearce Creek 

DMCA. The findings were published in Black & Veatch 

Special Projects Corp., 1996. The results of Black &Veatch 

Special Projects Corp. (1996) were incorporated into a 

Phase II report by the U.S. Army Corps of Engineers (1996).

The U.S. Army Corps of Engineers, (1996) Phase II study 

included an analysis of the geology, hydrogeology, soil chemistry, and groundwater quality of the Pearce Creek DMCA and 

WVS community. The USACE concluded that (a) the Pearce 

Creek DMCA was not the source of elevated concentrations 

of metals, sulfate, and chloride because the area beneath the 

DMCA was underlain by a continuous confining unit, and 

(b) that the groundwater with elevated concentrations of metals, sulfate, and chloride originated from another source, possibly upgradient of the DMCA, or from intrusion of brackish 

water from Elk River and Chesapeake Bay (U.S. Army Corps 

of Engineers, 1996). Thus, the USACE concluded that further 

use of the Pearce Creek DMCA would not result in future 

problems for local community water supplies.

An additional review of existing data was conducted 

by Roy F. Weston, Inc., for the USACE, and the results were 

published in a final report (R.F. Weston, Inc., 1998). The 

purpose of that report was to determine the local hydrogeologic framework, potential groundwater flow paths from 

the Pearce Creek DMCA to domestic-supply wells in WVS, 

and to use geochemical and statistical methods to identify 

sources of groundwater recharge in WVS. R.F. Weston, Inc., 

determined that groundwater flow paths had the potential to 

allow groundwater to flow from the Pearce Creek DMCA into 

domestic-supply wells in WVS, but there were insufficient 

data to determine a definitive pathway. R.F. Weston, Inc., also 

noted that the geochemistry is complex, and that the source 

of geochemical signatures in the WVS could be from saltwater intrusion or could reflect regional groundwater flow and 

quality patterns. R.F. Weston, Inc., concluded that most of 

their analysis indicates that the Pearce Creek DMCA was not 

responsible for the degraded groundwater quality in the WVS, 

that there were insufficient data to determine the source of the 

poor quality of groundwater, and that possibly a local landfill area or residential plumbing could be contributing to the 

degraded groundwater quality in this community.
Methods of Water-Quality Data Collection and Data Quality 5

Description of Study Area

The Pearce Creek DMCA is located in Cecil County, Md. 

(fig. 1), on the eastern bank of the Chesapeake Bay near the 

confluence of the Elk River and the Chesapeake Bay. The site 

is located on Pond Neck approximately 7 mi west of Cecilton, Md. Several small communities border the Pearce Creek 

DMCA, including WVS, Bay View Estates, and Crystal Beach 

(fig. 2).

The climate in the study area is humid with well-defined 

seasons. The average annual precipitation in the area is 

approximately 45 inches per year and is relatively evenly distributed throughout the year. The mean tidal range on the Elk 

River, 8 mi north of the Pearce Creek DMCA, is 2.2 ft.

Review of Maryland State well permits indicates development of the WVS community mainly occurred after WWII 

in the 1940s and 1950s. Initially, numerous wells were 

installed typically at depths greater than 100 ft below land 

surface. However, many wells installed as replacement wells 

in the 1990s and 2000s were installed at shallower depths of 

less than 70 ft. The development of Bay View Estates, which 

borders the study area to the southwest of WVS, historically 

was controlled by a single landowner. Consequently, development occurred later and at a slower pace in this community 

than in WVS.

Well Numbering System

In this report, wells are identified by their USGS “local 

site name,” such as CE Dd 81, or CE Dd 124. The first two 

letters, “CE,” indicate the county in which the well is located, 

Cecil County, Md., in this example. The third and fourth 

letters, “Dd,” indicate the 5-minute quadrangle in which 

the well is located (LaMotte, 2010). The last two or three 

numbers indicate the order (sequentially) that the well was 

inventoried in the USGS National Water Information System 

(NWIS) database. The 5-minute quadrangles are designated 

by uppercase letters from north to south, and lowercase letters 

from west to east. Most of the wells in this report are in Cecil 

County, Md., and they are in the 5-minute quadrangle “Dd.” 

Therefore, for brevity, the wells are sometimes only identified 

by the last two or three digits, which is the case in this report. 

Appendix A lists the USGS local site names and other information, such as well depths and screened intervals, for each 

well discussed in this report. Appendix A also lists the well 

names used in some of the previous site investigations, in the 

column titled “USACE well name.”

History and Use

At the time the USACE acquired the property for the 

DMCA, the site was a groundwater discharge zone with a 

natural wetland that drained directly into the Elk River, or 

into Pearce Creek, which in turn naturally flowed into the Elk 

River (fig. 3). After the USACE acquired the property, the 

agency created drainage canals and other structures, such as 

berms and dikes, on the property (fig. 4). The berms and dikes 

were formed from cut and fill operations, by the agency likely 

using naturally deposited sediments within the DMCA property boundary (D. Sirkis, USACE, oral commun., 2011). Since 

the initial purchase of the site for dredge material disposal, the 

site has undergone many changes. The site is no longer freely 

draining. Pearce Creek is now a freshwater lake, after a land 

bridge was created at the mouth of the lake. The level in the 

lake can be raised or lowered through controlled releases at 

the lake outlet. Berms have been created at the site, and dredge 

material has been placed at the site. In addition to the sediment 

routinely dredged from the canal, a considerable amount of 

water from the Elk River routinely was mixed with dredged 

sediment to create slurry that was pumped into the DMCA. 

The containment area (within the berms) is currently (2012) 

260 acres (fig. 5).

Methods of Water-Quality Data 

Collection and Data Quality

Water-quality measurements and samples, which provide 

extensive data on the physical and chemical characteristics 

of groundwater and major surface waters in the study area 

(appendix B, table B1), were collected at 36 observation wells 

distributed throughout the study area, 15 domestic water-supply wells mainly located in WVS and along Pond Neck Road, 

and two surface-water sites—Elk River and Pearce Creek 

Lake (fig. 6). The selected wells provide coverage of the three 

major water-bearing zones—one in the Magothy aquifer and 

two (one shallow and one deep) in the upper Patapsco aquifer—beneath the DMCA and vicinity; the domestic wells provide an indication of the quality of groundwater obtained by 

residents mainly from the Magothy Formation and the upper 

Patapsco Formation outside of the DMCA property boundary 

(appendix A, table A1).

In relation to the wells chosen for data collection, historical records indicate there initially were many intermediate to 

deep supply wells in the WVS area, but residents abandoned 

many of these wells for shallow wells from about 1990 to 

about 2005. Although residents initially indicated their deep 

wells still existed and could be used for this study, onsite 

inspections of a number of these wells found none suitable for 

use. Logistical reasons (availability of open space and homeowner permission) limited installation of wells in the elevated 

central part of WVS, which further limited the ability to gather 

water-quality data from intermediate or greater depths in the 

area.

Water-quality data and samples also were collected from 

the two major surface waters in the area (fig. 6). In addition to 

providing an indication of their current (2010–11) water quality, data from Elk River provides an indication of the quality 

of water used to dispose of dredged sediments in the DMCA. 

In addition, water from the DMCA drained into Pearce Creek 
6 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

Lake; thus, data collection also included obtaining waterquality data and samples at the outlet of Pearce Creek Lake.

Except for wastewater and pesticide compounds, similar water-quality measurements and samples were obtained 

from all wells and surface-water sites (appendix A, table A1). 

Data collection for wastewater and pesticide compounds was 

conducted mainly at selected shallow observation wells in 

the study area, at all domestic water-supply wells, and at both 

surface-water sites. 

Water-quality data from most observation wells (30 of 

35) and all supply wells were obtained during April through 

mid-June, 2010 (appendix B, table B1). Data from five additional monitoring wells (three of which were installed late in 

2010), two existing wells, and the two nearby surface-water 

sites—Elk River and Pearce Creek Lake—were collected 

from late January through February in 2011. Data collection 

during both of these periods included quality-control samples 

and measurements at selected wells and surface-water sites 

(appendix B, table B2) to help determine the accuracy and 

comparability of the water-quality data. The collected waterquality and quality-control data have been summarized in a 

manner consistent with their use to address the objectives of 

this report (appendix B, tables B3 and B4, respectively).

Data-Collection Methods

Water-quality data collection at each well or surfacewater site was conducted by two local USGS Water Science 

Center (WSC) sampling teams—one in Baltimore, Md., and 

one in Dover, Del. Groundwater data-collection activities performed by either team included (a) purging to remove water 

that had been standing in a well, (b) flushing wetted equipment during the final stages of purging with groundwater to 

condition this equipment before final in-field measurements of 

0 500 1,000 1,500 2,000 FEET

0 200 400 METERS

Base map from U.S.Geological Survey, Maryland-Delaware

Cecilton quadrangle, June 1900

National Geodetic Vertical Datum of 1929 (NGVD 29)

Land surface contour—In feet above mean sea 

level. Contour interval 20 feet

Approximate current location of the DMCA 

perimeter dike

20

EXPLANATION

Elk River

Pearce Creek

N

Figure 3. General topography and drainage characteristics of the study area before installation of the Pearce Creek Dredge Material 

Containment Area (DMCA), Cecil County, Maryland, circa 1890.
Methods of Water-Quality Data Collection and Data Quality 7

selected water-quality parameters were obtained, and 

(c) collecting, processing, and, as necessary, preserving, 

samples until their analyses by the WSC team, or their shipment, by chain of custody, to selected USGS laboratories for 

analyses. 

Data collection at each surface-water site involved the 

use of equipment and procedures similar to those used to 

obtain groundwater samples; equipment was conditioned with 

surface water before final in-field measurements or samples 

were obtained. In the case of Elk River, the surface-water 

sample was collected soon after high tide at mid-channel, 

as a composite of approximately 1.5-liter samples collected 

at thirteen 3-ft intervals beginning 3 ft below the river surface. Equipment was conditioned with river water at each 

depth interval before the sample was collected. At the Pearce 

Creek Lake outlet, samples were sequentially collected and 

processed in a manner identical to that used for groundwater 

samples. 

Equipment and methods used for data collection were 

chosen in accordance with the USGS National Field Manual 

(NFM; U.S. Geological Survey, variously dated). (Parts of the 

USGS NFM have been written and revised by many authors 

over many years as procedures and protocols are refined, and 

as such the USGS NFM is not referenced by specific authors 

or publication years.) The methods for data collection were 

also based on the expected well and groundwater-quality 

conditions in the study area. Equipment and method selection 

also was guided by historical studies of groundwater quality conducted in the Pearce Creek study area in the 1990s 

(Maryland Environmental Service, 1995; U.S. Army Corps of 

0 500 1,000 1,500 2,000 FEET

0 200 400 METERS

Base map from U.S. Army Corps of Engineers 

Earleville quadrangle, Cecil County Maryland, 1944

National Geodetic Vertical Datum of 1929 (NGVD 29)

Land-surface contour—In feet above mean sea 

level. Contour interval 20 feet

Approximate current location of the DMCA 

perimeter dike

20

EXPLANATION

Elk River

Pearce Creek Lake

N

Figure 4. General topography and drainage characteristics of the study area during the installation of the Pearce Creek Dredge 

Material Containment Area (DMCA), Cecil County, Maryland, circa 1944. 
8 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

Engineers, 1996; and R.F. Weston, Inc., 1998), combined with 

recent (2009–10) site visits by the USGS to obtain geophysical 

and video logs, and by USACE contractors during the development or redevelopment of selected newly installed or existing monitoring wells. Collectively, these historical studies and 

site visits indicated that groundwater in the study area could 

be suboxic [a zone of water, between the oxic and anoxic 

zones, in which the concentration of oxygen (and sulfur) is 

very low] to anoxic with elevated concentrations of dissolved 

solids, including major ions, metals, dissolved organic carbon 

(DOC), and possibly hydrogen sulfide. Video logs of standing water in wells before and after their development revealed 

suspended sediments in most wells, which likely consisted 

of metal hydroxide or oxide precipitates and (or) fine silts or 

clays. Thus, data-collection equipment and procedures were 

chosen and employed to (a) ensure wells were adequately 

purged to remove standing water and suspended sediments, 

(b) properly condition sampling equipment, (c) obtain accurate 

in-field water-quality measurements and suitable groundwater 

samples, and (d) adequately clean reusable equipment onsite, 

or at the designated cleaning area in the study area, before 

proceeding to reuse that equipment at the next site.

To adequately prepare each observation well for data 

collection, purging was conducted in stages with a submersible, stainless-steel, and positive-displacement (SSSPD) pump. 

During the first stage, purging was conducted with a relatively 

high pumping rate, approximately 1–3 gal/min (gallons per 

minute), given there was no obvious continued decline in the 

water level in the well. The purpose of this stage of purging 

was to remove standing water and suspended solids. Purging 

at this pumping rate was conducted until the equivalent of 

at least two times the initial volume of water standing in the 

well casing had been removed, and the turbidity of discharged 

water declined to 5 NTRU (nephelometric turbidity ratio units) 

or less. During the next stage, generally high purging rates 

were decreased to reduce the potential for mixing between 

groundwater entering and already standing in the well, and to 

help ensure lateral groundwater flow to the well. Purging was 

Figure 5. General topography and drainage characteristics of the study area after closure of the Pearce Creek Dredge Material 

Containment Area, Cecil County, Maryland, circa 1990s. 

76° 75°59'

39°26'

39°25'30"

Elk River

Pearce Creek Lake

Crystal Beach

Pond Neck Road

EXPLANATION

0 500 1,000 1,500 2,000 FEET

0 200 400 600 METERS

West View Shores

Bay View Estates

Property boundary of Pearce Creek 

Dredge Material Containment Area

Perimeter dike

High-density residential (West View Shores, 

Bay View Estates, and Crystal Beach)

Low-density residential (Along Pond Neck 

Road)

Agriculture (row crop, pasture, or nursery, mainly 

southeast and east of Pond Neck Road)

Forested

Wetland

Base map from U.S. Geological Survey, Earleville, MD, 1975 and 

 Spesutie, MD, 1984, 7.5 minute Quadrangles
Methods of Water-Quality Data Collection and Data Quality 9

Elk River

Pearce Creek Lake

140

160

127

177

166

178

141

163

172 168

128

176 161

164

174

171

143

165

142 152

170

155

147

141 177

176

169

161

166

178

164

174

81

191

160

127

128

129

126

122 158

156

154

149

150

146

142

138

165

163

172 168

179

135

125

192

193

133

157

153

151

145

143

140

139

137

136

124

144

75°59' 76°

39°26'

39°25'30"

157

168122

169

155

170

Elk River

144

Elk River Pearce Creek Lake

Crystal Beach

Pond Neck Road

West View Shores

Bay View Estates

EXPLANATION

Locally perched groundwater observation well 

and identifier

Magothy aquifer observation well and identifierMagothy aquifer domestic well and identifierUpper Patapsco aquifer (shallow water-bearing 

zone) observation well and identifier

Upper Patapsco aquifer (shallow water-bearing 

zone) domestic well and identifier 

Upper Patapsco aquifer (deep water-bearing 

zone) observation well and identifier

Upper Patapsco aquifer (deep water-bearing 

zone) domestic well and identifier

Surface-water site and identifier

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

Figure 6. Selected wells and surface-water sites used by the U.S. Geological Survey for water-quality data collection in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11. (The area with yellow highlighting is the community of West View Shores.)
10 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

then continued until at least a third volume of standing water 

was removed from the well, turbidity measurements declined 

to less than 1 NTRU, water levels were relatively stable, and 

other selected water-quality purging parameters were stable 

(table 1).

Equipment used to purge the well and to obtain groundwater for water-quality measurements and samples was 

selected in accordance with USGS NFM procedures (Lane and 

others, 2003) with modifications to account for differences 

in well depth, type, and construction. For shallow monitoring wells with less than 10–15 ft of water standing above the 

well screen, pumping to purge the well and obtain in-field 

measurements and samples of groundwater was conducted 

with a single SSSPD pump fitted with dedicated and cleaned 

polychlorofluorocarbon-lined polyethylene sample tubing. 

The pump head was installed within 2 to 3 ft of the top of the 

well screen, and the pump system was used to purge the well, 

condition equipment, obtain in-field measurements, and collect 

groundwater samples. Generally the pumping rate was initially 

set at 1 to 2 gal/min or less, but ultimately reset to a low rate 

of flow (generally a few tenths of a gallon per minute) during 

the final stage of purging. 

Although the above approach was successful at most 

shallow wells, repeated attempts to use this approach, or 

other low-flow purging procedures, were unsuccessful at two 

shallow observation wells (appendix A, table A1, well CE Dd 

148 and well CE Dd 159). Despite several attempts by the 

USACE contractor to develop these wells, recovery rates for 

these two shallow wells were very low, and recovery water in 

these wells always was highly turbid and contained high levels 

of finely sized suspended solids. Recoveries were too low to 

adequately purge the wells and collect samples representative 

of groundwater.

For moderate to deep monitoring wells with more than 

10 to 15 ft of standing water above the top of the well screen, 

purging and groundwater data and sample collection were 

conducted with two SSSPD pumps. A small SSSPD pump 

similar to that used for shallow monitoring wells was installed 

to a depth of 2 to 3 ft from the top of the well screen. A large 

SSSPD then was installed generally 10 to 12 ft above the 

small pump. The large shallow pump mainly was used to 

purge and ultimately maintain the upward flow of groundwater 

into the well. This pump generally was operated at an initially 

high rate of flow (up to a few gallons per minute) during the 

initial stage of purging. The pumping rate was then reduced, 

as needed, to achieve purging requirements during the final 

stage of purging. The small deep SSSPD pump was started and 

operated at a low rate of flow (similar to that used for shallow 

monitoring wells) at the onset of the final stage of purging. 

Ultimately, the small deep SSSPD pump was used to obtain 

water-quality measurements and samples.

For domestic water-supply wells, purging, conditioning, 

and the collection of water-quality measurements and samples 

were conducted with the existing submersible supply pump in 

the well. Except for the rate of pumping, the domestic watersupply wells were sampled with the same methodology that 

was used for the monitoring wells. Groundwater from each 

supply well was obtained from a standard water spigot. This 

spigot generally was located on the water-supply distribution 

line either before or just after the pressurized supply tank, and 

before any type of water-treatment system. If the spigot was 

located before the supply tank, a second spigot after the supply 

tank but before the water-treatment system was used to create 

continuous and sufficient discharge from the supply tank to 

keep the well pump running and reduce any backflow from the 

tank or the water-distribution system beyond the tank. If the 

spigot was located just after the supply tank, spigot flow generally was split into a dedicated and cleaned polychlorofluorocarbon-lined polyethylene sample line and a waste line. Flows 

at the spigot and through the waste line then were regulated 

to continuously drop the pressure in the supply tank to keep 

the well pump running. In addition, and regardless of where 

the spigot used for data and sample collection was located, all 

through and shutoff values associated with the water treatment 

Table 1. Stability criteria used for water-quality parameters during water-quality sampling in the Pearce Creek Dredge Material 

Containment Area and vicinity, 2010–11.

[±, plus or minus; oC, degrees Celsius; %, percent; μS/cm, microsiemens per centimeter at 25 oC; >, greater than; <, less than; mg/L, milligrams per liter; mV, 

millivolts; NTRU, nephelometric turbidity ratio units]

Field measurement Stability criteria between successive measurements taken at 3- to 

5-minute intervals for at least three intervals

Multiparameter sonde, continuous measurements

Temperature (thermistor) ± 0.2 oC

pH ± 0.1 standard unit

Specific electrical conductance (SC) ± 3% for SC >100 μS/cm

Dissolved-oxygen concentration (polarographic or optical) ± 0.2 mg/L, if 0.5 mg/L or greater

Reduction-oxidation potential ± 20 mV (as data are reported to nearest 10 mV)

Spectrophotometer, point-in-time measurements

Turbidity (nephelometric) ± 5% for Turbidity < 100 NTRU
Methods of Water-Quality Data Collection and Data Quality 11

system were closed to prevent backflow through the system to 

the spigot. 

At each monitoring or supply well, in-field measurements 

of well discharge were obtained at the end of the purging 

(beginning of sampling) to help characterize the quality of 

groundwater. Except for turbidity, all measurements were 

obtained in accordance with the USGS NFM (Gibs and others, 

2007), at 5- to 10-minute increments, on well discharge, in an 

enclosed chamber equipped with a multiparameter sonde fitted 

with probes for pH, temperature, specific conductance, 

redox potential, and the concentration of dissolved oxygen 

(appendix B, table B5). Spectrophotometric measurements of 

turbidity were obtained in accordance with the USGS NFM 

(Anderson, 2005), with a turbidity sensor (nephelometric turbidity ratio units), at similar time increments, on grab samples 

of well discharge (appendix B, tables B2 and B5).

At each monitoring or supply well, samples of groundwater were collected, processed, and preserved in portable 

chambers with dedicated liners, and in accordance with the 

USGS NFM (U.S. Geological Survey, 2006), with several 

modifications to help ensure samples reflected groundwater 

unaltered by the manner of collection. Regarding samplecollection order, raw-water samples for hydrogen sulfide, net 

acidity, and acid neutralization capacity were collected first. 

Filtered samples for dissolved inorganic constituents (trace 

elements, major ions, and nutrients) and DOC were collected 

immediately after the raw-water samples, in the order listed, to 

reduce potential bias in trace-element and major-ion concentrations from potential sediment loading of the filter (Radtke 

and others, 2002). Samples for dissolved pesticide and then 

wastewater compounds were collected and filtered after the 

collection of the DOC sample, using a second filter, and only 

at selected (mainly shallow) monitoring wells and all domestic 

water-supply wells.

Filter selection and use followed USGS NFM guidance 

(Radtke and others, 2002) with some minor modifications in 

the preconditioning of filters and filtering procedure given 

groundwater characteristics in the study area. Samples for dissolved inorganic constituents and organic carbon were filtered 

through a polypropylene encapsulated 0.2- μm (micrometer) 

effective pore size pleated polysulfonyl filter. Before use, this 

filter was pre-rinsed with USGS WSC laboratory de-ionized 

[0.055 μS/cm (microsiemens per centimeter)] activated-carbon 

filtered water, hereafter referred to as simply USGS WSC 

laboratory-grade water, and, on the day of use, purged with 

high-purity, dried nitrogen gas to remove air (oxygen) and 

excess water from the filter. Samples for dissolved pesticides 

and wastewater compounds were filtered through a stainlesssteel plate filter containing a 0.70-μm effective-pore-size, 

142-millimeter-diameter baked, glass fiber, which also was 

pre-rinsed with USGS National Water Quality Laboratory 

(NWQL) Pesticide-Volatile Organic Compound grade water.

Additional steps taken to ensure that filtered samples 

for dissolved constituents reflected groundwater included the 

following: 

(a) Sample bottles that required pre-rinsing were each 

rinsed with USGS WSC laboratory-grade water rather than 

with groundwater—to avoid the oxidation of the latter and the 

possible formation of chemical precipitates in the groundwater rinse that could contaminate the sample bottle before the 

actual sample was collected; 

(b) To remove residual rinsate, and to reduce oxidation of 

the groundwater sample by air before it was entirely collected, 

all sample bottles were filled with groundwater from the bottom up with a dedicated extension tube and were allowed to 

overflow before they were capped with little to no head space; 

(c) For samples collected with a capsule filter, which 

contains considerable head space above and below the pleated 

filter, the capsule was attached to the sample tubing, inverted, 

and filled from the bottom up to displace the nitrogen gas and 

fill the entire filter housing. The dedicated extension tube was 

connected to the outflow stem of the filter, and sample flow 

discharged through the filter system to condition it before dissolved samples were collected.

For those samples that required chemical preservation—

dissolved samples for trace elements, major ions, and selected 

nutrients—the samples were acidified with the appropriate 

reagent-grade acid to a pH of 2 or less immediately after filtration. Dissolved samples for nutrients, organic carbon, and pesticides and wastewater compounds, which required physical 

preservation (chilling to at least 4 °C (degrees Celsius)), were 

placed on ice immediately after collection, and maintained and 

shipped in this state.

Upon completion of sampling at a well site, all nondedicated sample-wetted equipment to be reused at a subsequent well site was initially rinsed and flushed with WSC 

deionized tap water to remove groundwater. Depending on site 

conditions, reused equipment was then fully cleaned on site, 

or at a designated cleaning facility established in the study 

area. Except for the use of methanol, cleaning was performed 

in accordance with USGS NFM procedures for groundwater 

sampling (Wilde, 2004).

At selected monitoring and observation wells, qualitycontrol (QC) samples, including field blanks to assess potential sample contamination, and duplicate sequential groundwater samples to assess measurement precision, were collected 

for raw and dissolved constituents (appendix B, table B2). 

Additional duplicate sequential groundwater samples were 

collected for selected laboratory-analyzed samples, including 

pesticides or wastewater compounds, for laboratory spikes. 

Laboratory spikes were performed to assess whether any 

chemical precipitation [or other degradation] from sample 

oxidation during shipping or handling of samples in the laboratory reduced the recovery of these compounds. In addition, 

standard reference samples (SRSs), obtained from the USGS 

Branch of Quality Systems, Denver, Colorado, were submitted 

from the field to the NWQL to assess the accuracy of analysis 

for selected trace elements.

Chemical analysis of raw groundwater and qualitycontrol samples was conducted in the field or local USGS 

WSC laboratory depending upon the type of sample collected 
12 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

(appendix B, table B5). Analyses of samples for hydrogen 

sulfide were conducted on raw or whole-water samples in 

accordance with standard methods (appendix B, table B5), 

by the sampling team immediately, and no more than 5 to 

10 minutes after the samples were collected. Analyses of 

duplicate samples for acid neutralization capacity also were 

conducted on whole-water samples in the field or the USGS 

WSC laboratory in Baltimore, Md., on the day of collection 

and in accordance with the USGS NFM (Rounds, 2006). 

Except for one modification, the analyses of samples for net 

acidity also were conducted on whole-water samples acidified 

to a pH of 4 (H2SO4, titrant) within 24 hours of collection and 

then determined in the field or Baltimore USGS WSC laboratory in accordance with standard methods (appendix B, table 

B5). The modification was to increase the volume of hydrogen 

peroxide added to each sample from one-half to several milliliters to help ensure the oxidation of any hydrolyzed metals 

and DOC.

Samples analyzed by USGS laboratories other than 

the Baltimore USGS WSC were maintained until shipment, 

shipped, and then maintained by those laboratories under a 

formal chain of custody. With few exceptions, the analyses of 

groundwater and quality-control samples for total dissolved 

solids, dissolved inorganic constituents, dissolved carbon 

and 69 wastewater compounds were conducted with standard 

methods by the USGS NWQL in Denver, Colo. (appendix B, 

table B5). The exceptions are described below. 

Although all samples submitted to USGS laboratories 

were initially filtered in the field, most samples were treated 

by these laboratories as whole-water samples. Thus, except 

for selected anions—ammonia-, nitrate-plus-nitrite-, and 

nitrite-nitrogen, sulfate, and halides (bromide, chloride, and 

fluoride)—chemical analyses were performed by the NWQL 

or USGS Minerals Program Laboratory (arsenic) as if the samples were raw or whole-water rather than dissolved (filtered) 

samples. As such, raw or whole-water samples were analyzed 

using standard reference methods that involved the appropriate 

digestion of the sample, including any suspended solids that 

formed as a result of sample oxidation (appendix B, table B5). 

Water-quality samples analyzed by the NWQL for ammonia-, 

nitrate-plus-nitrite-, and nitrite-nitrogen, sulfate, and halides 

(bromide, chloride, and fluoride), and for low-level pesticides 

by the USGS Organic Geochemistry Research Laboratory 

(OGRL), Lawrence, Kansas, were refiltered in each laboratory 

to remove any suspended solids in accordance with standard 

reference methods for the analysis of these compounds. In 

addition, duplicate sequential groundwater samples were 

collected at selected wells whose discharge during sample collection had a high specific conductance. These samples were 

then spiked by the receiving USGS laboratory for low-level 

pesticides or wastewater compounds immediately after the 

sample bottles were opened to determine if recoveries of these 

compounds were reduced by the formation of suspended solids 

following exposure of the sample to air.

 The analysis of selected constituents required recently 

developed or modified standard reference methods, as follows: 

1. The analysis of nitrate-nitrogen, which was conducted 

by the NWQL, employed a recently developed reductase 

method to circumvent low bias results for nitrate-nitrogen 

concentrations in groundwater samples with elevated iron 

concentrations associated with the standard cadmiumreduction method (Patton and Kryskalla, 2011; and appendix B); 

2. The analysis of beryllium, which also was conducted 

by the NWQL, required the use of a modified standard 

whole-water recoverable method to reduce sample-matrix 

interferences (appendix B); 

3. The analyses for arsenic were conducted by the USGS 

Minerals Program Laboratory, Denver, Colo. This 

analysis also utilized a modified standard whole-water 

recoverable method to reduce sample-matrix interferences 

(appendix B); and 

4. The analysis of sulfate was conducted through a joint 

collaborative effort between the NWQL, which employed 

one standard reference method for most groundwater 

samples, and the Baltimore USGS WSC, which employed 

a second standard method, and regression analysis, to estimate sulfate concentrations for selected samples, which 

could not be analyzed by the NWQL method because of 

sample-matrix interferences (appendix B).

Analyses for approximately 50 low-level pesticide compounds in groundwater and surface-water samples obtained 

from selected wells and surface-water sites (appendix B, 

table B3) were conducted by the USGS OGRL in Lawrence, 

Kans. All samples were analyzed by the OGRL in accordance 

with standard recoverable methods for 22 triazine compounds 

or their metabolites and 32 acetanilide and acetanimide compounds or their metabolites at low levels (generally less 

than 0.020 or 0.025 μg/L (microgram per liter); appendix B, 

table B5).

Analyses of wastewater compounds only were conducted 

on samples obtained from selected wells and surface-water 

sites (appendix B, table B3), and by the NWQL in accordance 

with standard recoverable methods (appendix B, table B5). 

These analyses also included selected pesticides with 

relatively high laboratory reporting levels (approximately 

0.2 μg/L or greater) compared to the OGRL laboratory reporting levels for similar compounds. Hereafter, this analysis or 

data from this analysis will be referred to as the NWQL highlevel pesticide method or data, respectively.

Data Quality

The quality of the surface and groundwater data collected 

in 2010–11 was determined on the basis of quality-control data 

obtained from field blanks and duplicate sequential groundwater samples, from laboratory recoveries of water-quality 

samples spiked with pesticides, wastewater, or surrogate 

compounds (appendix B). Laboratories were also sent SRSs 
Methods of Water-Quality Data Collection and Data Quality 13

marked as site environmental samples, as an additional quality 

control measure (appendix B). Additional laboratory qualitycontrol data also were obtained, analyzed, and summarized 

for those constituents whose concentrations were determined 

with modified analytical methods—nitrate-nitrogen, sulfate, 

beryllium, and arsenic (appendix B). The purpose of all these 

evaluations was to assess the quality of the groundwater data 

collected, and to ensure the data were of sufficient quality to 

address the purposes of the project and of this report. These 

data-quality evaluations are described in detail later in this 

report (appendix B), and are summarized below in relation to 

contamination bias, measurement precision, sample-matrix 

bias, and measurement accuracy.

Contamination Bias: Field Blanks

Inadvertent and routine contamination of water-quality 

samples during or after their collection can be identified with 

field blanks (Koterba and others, 1995). A review of fieldblank data collected during 2010–11 (appendix B) has been 

summarized (table 2). For most of the water-quality data 

collected in this study, including dissolved solids, major ions, 

and pesticides, there was no evidence of routine contamination 

of field blanks, and thus potentially of water-quality samples, 

during or after their collection. For both years of data collection, and except for occasional trace (detectable) amounts 

of selected major and minor ions, the concentrations of all 

groundwater constituents in field-blank samples generally 

were below the laboratory reporting levels (LRLs). In addition, no pesticide was detected in any field blank. Thus, no 

appreciable bias due to inadvertent contamination during the 

collection, processing, preservation, shipping, or analysis of 

groundwater samples in either year of data collection is evident that would warrant limiting the interpretation of the major 

ion, nutrient, or pesticide water-quality data.

For five wastewater compounds (1,4-dichlorobenzene, 

bis(2-ethylhexyl) phthalate, bisphenol A, diethyl phthalate, 

and phenol), the frequency, magnitude (generally less than 

1 μg/L), and timing of field-blank contamination does appear 

to correspond to the magnitude and timing of their occurrence 

in groundwater samples. In addition, triphenyl phosphate was 

detected in every field blank at concentrations below its LRL, 

but it was not detected in any water-quality sample. Determination of the source (or sources) of contamination was (were) 

beyond the scope of this report, but all these compounds are 

relatively ubiquitous in the environment due to their natural 

occurrence and (or) many anthropogenic uses. Given the consistency in low-level occurrence of these compounds in most 

if not all field blanks, with the co-occurrence of these same 

compounds in groundwater samples collected at similar times 

as the contaminated blanks, detections of these compounds in 

the groundwater samples are considered the result of contamination bias. These compounds were excluded from other 

interpretive analyses in this report, including evaluation of the 

USEPA SDWA standards. 

 Measurement Uncertainty: Duplicate Samples

The absolute relative difference between duplicate 

sample measurements for a given constituent, expressed in 

percent, and hereafter referred to as the relative sample difference (RSD) in this report, provides an indication of the general 

precision in measurement for that constituent. Given no bias in 

the sample values appeared in relation to their order of collection, the RSD for each constituent and duplicate sample was 

computed as follows:

RSDi = ABS[(X2–X1)/(Mean (X1+X2))]*100 (1)

Where

RSD is the relative sample difference for a given 

constituent X and the ith duplicate pair 

(i = 1,2,3, or 4), expressed in percent;

ABS is the absolute value of the entire subsequent 

calculation;

X2–X1 is the difference in measurements between 

first sample collected (X1) and the second 

sample (X2) collected sequentially after X1; 

and

Mean (X2+X1) is used to normalize their difference for 

comparative purposes.

RSD values were computed in the above manner for four pairs 

of duplicate sequential groundwater samples, and they were 

reviewed for each constituent and collectively summarized to 

reflect groups of constituents (appendix B). 

The summary of RSD values obtained from sequential 

duplicate groundwater samples revealed that precision in measurement differed by constituent group (table 3). There were 

no differences in measurement precision for pesticide data 

obtained with either the low-level OGRL or high-level NWQL 

methods. This result reflects that only a few pesticides were 

detected in groundwater samples, and all detections reflect 

low-level concentrations above the LRLs for these pesticides. 

Precision results for total dissolved solids, major ions, and 

nutrients indicate little to modest variability between measurements from duplicate samples for most constituents. For 

these constituents, mean or median RSD values were less 

than 3 percent, and RSD values were generally less than 

10 percent (table 3). Values in excess of approximately 

10 percent corresponded to estimated sample concentrations 

below the LRLs, which generally have higher than normal 

uncertainty in their measurement. For trace elements, the 

uncertainty in measurement increases, with mean and median 

RSD values ranging from 4 to 10 percent, and individual 

constituent values as high as approximately 35 percent. RSD 

values derived from estimated (below LRL) concentrations 

for trace elements covered a similar range in values. Wastewater compounds had the greatest uncertainty in measurement (table 3). The mean RSD value for these compounds 

was approximately 20 percent, with individual RSD values as 

high as 45 percent—excluding two extreme outliers. The high 

degree of uncertainty in wastewater compound measurement 
14 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area Table 2. Contamination bias: Summary of evaluation of field-blank quality-control data for water-quality samples collected in the Pearce Creek Dredge Material Containment Area and vicinity, 2010–11. [USGS; U.S. Geological Survey; mg/L; milligrams per liter; μg/L; micrograms per liter; E, estimated value with higher than normal uncertainty; <, less than; --, not analyzed; value in red indicates concentra- tion detected in field blank; LRL, laboratory reporting level] Constituent groups and constituents Summary Dissolved solids, major ions, and nutrients (mg/L) Spurious low-level (estimated 0.01 mg/L or less) detections in a few constituents in single but various blanks; one detection at measureable levels (1.4 mg/L) for dissolved recoverable carbon in blank associated with groundwater samples with consider- ably high carbon concentrations. Trace elements (μg/L) Possible bias in arsenic (As) for groundwater samples with low-level As (less than 0.5 μg/L) collected between 4/28/2010 and 5/19/2010; possible bias in zinc (Zn) for samples with low- level Zn (1.0 μg/L or less) collected 5/26/2010 (for example, wells CE Dd 146 and 158). Pesticides triazines and metabolites, acetanilides and acetanimides, and metabolites low-level methods (0.020– 0.025 μg/L) No detections for any constituent in this group. Wastewater compounds and high-level pesticide method (0.2 μg/L or greater) No detections for any constituent in this group. Wastewater compounds, other, dissolved, recoverable (μg/L) Systematic contamination of field blanks and likely all associated groundwater samples that contain the follwing at detetectable (estimated) concentrations: 1,4-Dichlorobenzene, Bis(2-ethyl- hexyl) phthalate, Bisphenol A, Diethyl phthalate, and phenol. Constituent Local USGS well identifer and date of collection for field blanks CE Dd 137 05/05/2010 CE Dd 157 05/19/2010 CE Dd 159 05/26/2010 CE Dd 163 06/07/2010 CE Dd 168 06/02/2010 CE Dd 193 01/31/2011 1,4-Dichlorobenzene < 0.2 < 0.2 < 0.2 E 0.031 E 0.006 -- Detections in 2 blanks below LRL, similar in magnitude and time of occurrence as detections in samples from domestic supply wells. Bis(2-ethylhexyl) phthalate < 2 E 1.90 < 2 E 1.25 E 0.292 -- Detections in 3 blanks below LRL; their magnitude and time of occurrence are similar to detections in groundwater samples (mainly domestic supply wells). Bisphenol A < 0.4 E 0.092 E .111 E .083 E 0.087 -- Detections in 4 blanks below LRL; their magnitude and time of occurrence are similar to detections in most groundwater samples. Diethyl phthalate E 0.06 0.24 < 0.2 0.39 E 0.06 -- Detections in 4 blanks below LRL; their magnitude and time of occurrence are similar to detections in most groundwater samples. Phenol E 0.139 E 0.115 E 0.100 E 0.110 E 0.133 -- Detections in all blanks below LRL, magnitude and duration of occurrence indicates groundwater-quality samples likely positively biased. Triphenyl phosphate, 

water, unfiltered, recoverable, micrograms per liter

< 0.2 E 0.04 E 0.01 E 0.02 E 0.010 -- Detections in 4 consecutive blanks below LRL, but no detections 

in any groundwater samples.
Methods of Water-Quality Data Collection and Data Quality 15

reflects concentrations that generally were below all the LRLs 

for these constituents. 

The differences in measurement precision among constituent groups combined with differences in the frequency with 

which compounds were detected among constituent groups 

influenced how the data were interpreted for this report. For 

those constituents commonly detected and measurable above 

their LRLs with reasonably good precision—total dissolved 

solids, major ions, nutrients, and trace elements—the concentration data are used to describe patterns in the occurrence and 

distribution of these constituents in groundwater. For those 

constituents infrequently detected and (or) measured with a 

high degree of uncertainty—namely pesticides and wastewater 

compounds—simply their detections, either as individual compounds, or relative to grouping detected compounds by their 

chemical type or use, rather than their concentration, is used to 

describe simple patterns in the occurrence and distribution of 

either type of compound in groundwater.

Matrix Bias: Spiked Groundwater Samples

Given anticipated changes to the sample matrix that 

could result when suboxic (low dissolved oxygen) or anoxic 

(no measurable dissolved oxygen) samples were fully exposed 

to air (oxygen) in the USGS laboratories, it was necessary to 

determine whether such changes could influence the quality of 

the data collected. The potential for changes from dissolved to 

solid forms for redox-sensitive inorganic constituents, including major ions and trace elements, were for the most part 

addressed through the acidification of samples to a low pH 

(2 or less). Sample acidification to a pH of less than 2 proved 

sufficient to prevent solids from forming in samples for these 

constituents. In addition, the use of recoverable, rather than 

dissolved, laboratory analytical methods helped ensure any 

solids that did form were digested. However, potential changes 

in the sample matrix could affect the ability to accurately 

estimate concentrations of selected organic constituents, which 

were obtained from the analysis of dissolved samples that 

were not acidified—such as major anions, wastewater compounds, and pesticides. Also, although wastewater compounds 

and pesticides also were analyzed with recoverable methods, 

an additional assessment for possible matrix bias was conducted with the duplicate sequential groundwater samples 

whose collection was described earlier in this report. For 

pesticide and wastewater compounds, one of the duplicate 

samples was spiked by the OGRL or NWQL immediately 

upon opening in the laboratory. Both duplicate samples were 

then allowed time to oxidize; then they were analyzed with 

recoverable analytical methods, and the recovery of the spiked 

constituent was determined in accordance with standard laboratory procedures for spiked samples.

Data on the recoveries of low-level pesticides and 

wastewater compounds were reviewed with the OGRL and 

NWQL, respectively, and the results compiled for this report 

(appendix B). A summary of the recovery data for the OGRL 

low-level method for pesticides indicates that recoveries 

were within the normal ranges for most (46 of 53) compounds (table 4). Five compounds—cyanazine acid, deethyl 

cyanazine, linuron, flufenacet oxanilic acid, and propachlor oxanilic acid—had higher than normal recoveries; two 

compounds—2-chloro-N-(2,6-diethylphenyl) acetamide and 

propachlor(ethane)sulfonic acid—had lower than normal 

recoveries. All pesticide compounds actually detected in 

Table 3. Measurement precision: Summary statistics for the relative differences in measurements between duplicate samples, by 

constituent types, obtained from the analyses of sequential groundwater samples collected in the Pearce Creek Dredge Material 

Containment Area and vicinity, 2010.

[RSD, relative sample difference; E, estimated relative difference, in percent, determined from duplicate sequential samples, which each had a measureable 

concentrations below the laboratory reporting level for the constituent; ---, not quantified]

Summary statistic

Constituent group

Dissolved solids, major 

ions, and nutrients1

(percent)

Trace elements2

(percent)

Wastewater compounds3

(percent)

Pesticides4

(percent)

Median RSD 1.07 4.17 --- ---

Mean RSD 2.89 7.56 E 20.367 0.000

Minimum RSD 0.000 0.184 E 1.29 0.000

Maximum RSD 25.2 35.8 E 45.6 0.000

Number of RSD values 57 45 20 8

1

 Five of the 57 RSD values are estimated values and range range from E 7.02 to E 25.2 percent.

2

 Four of the 45 RSD values are estimated values and range from E 0.319 to E 33.1 percent. Two extreme RSD values are not included: a value of 

107 percent for arsenic, and a value of 214 percent for lithium. Each reflects marked differences between duplicate sample concentrations near their 

respective laboratory reporting levels.

3

 All 20 RSD values are estimated values. 

4

 All RSD values are zero as there was no difference between the duplicate sample concentrations for the eight instances in which both duplicate samples 

had measureable concentrations.
16 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

Table 4. Matrix bias: Summary statistics for the recovery of pesticides on the basis of U.S. Geological Survey Organic Chemistry 

Research Laboratory low-level analytical methods and laboratory spikes for groundwater samples collected in the Pearce Creek 

Dredge Material Containment Area and vicinity, 2010.

[Rose-shaded background indicates compound recovery is greater (or less) than normal with normal (mean) recovery being generally between approximately 

75 to 125 percent; Gray-shaded background indicates compounds that were detected in at least one groundwater sample; --, not applicable; <, less than]

Pesticide

Recovery statistics

Median

(percent)

Mean

(percent)

Minimum

(percent)

Maximum

(percent)

Number of 

spiked samples

Triazines and metabolites

Atrazine, water, dissolved, recoverable 96.0 93.4 80.0 104 5

Bromacil, water, dissolved, recoverable 108 106 76.0 131 5

Cyanazine, water, dissolved, recoverable 110 111 83.0 136 5

Cyanazine acid (CAC), water, dissolved, 

recoverable

501 484 71.0 813 5

Cyanazine amide (CAM), water, dissolved, 

recoverable

108 115 80.0 155 5

2-Chloro-4-isopropylamino-6-amino-s-triazine 

(DEA), water, dissolved, recoverable

104 104 84.0 133 5

Deethyl cyanazine (DEC), water, dissolved, 

recoverable

101 107 78.0 136 5

Deethyl cyanazine acid (DCAC), water, 

dissolved, recoverable

562 544 75.0 1,200 5

Deethyl cyanazine amide (DCAM), water, 

dissolved, recoverable

108 114 80.0 155 5

Chlorodiamino-s-triazine (DDA), water, 

dissolved, recoverable

105 103 81.0 131 5

2-Hydroxy-4-isopropylamino-6-amino-s-triazine (DEHA), water, dissolved, recoverable

89.0 78.8 36.0 107 5

2-Hydroxy-4-isopropylamino-6-ethylamino-striazine (DIHA), dissolved, water, recoverable

126 116 65.0 168 5

 2-Chloro-6-ethylamino-4-amino-s-triazine 

(DIA), water, dissolved, recoverable

102 103 81.0 120 5

Diuron, water, dissolved, recoverable 104 102 63.0 135 5

Demethyl fluometuron (DMFM), water, dissolved, recoverable89.0 93.6 68.0 146 5

Fluometuron, water, dissolved, recoverable 121 124 101 150 5

Linuron, water, dissolved, recoverable 173 160 92.0 191 5

Prometon, water, dissolved, recoverable 110 114 91.0 134 5

Propazine, water, dissolved, recoverable 93.0 94.0 77.0 108 5

Simazine, water, dissolved, recoverable 79.0 80.0 72.0 86.0 5

Hydroxy-simazine, water, dissolved, 

recoverable

103 103 67.0 149 5
Methods of Water-Quality Data Collection and Data Quality 17

Table 4. Matrix bias: Summary statistics for the recovery of pesticides on the basis of U.S. Geological Survey Organic Chemistry 

Research Laboratory low-level analytical methods and laboratory spikes for groundwater samples collected in the Pearce Creek 

Dredge Material Containment Area and vicinity, 2010.—Continued

[Rose-shaded background indicates compound recovery is greater (or less) than normal with normal (mean) recovery being generally between approximately 

75 to 125 percent; Gray-shaded background indicates compounds that were detected in at least one groundwater sample; --, not applicable; <, less than]

Pesticide

Recovery statistics

Median

(percent)

Mean

(percent)

Minimum

(percent)

Maximum

(percent)

Number of 

spiked samples

Acetanilides, acetanimides, and metabolites

Acetochlor, water, dissolved, recoverable 94.5 92.0 38.0 145 6

Dechloroacetochlor, water, dissolved, recoverable74.5 72.5 56.0 83.0 6

Acetochlor (ethane)sulfonic acid (ESA), water, 

dissolved, recoverable

80 80.7 74.0 92.0 6

Hydroxyacetochlor, water, dissolved, recoverable83 83.3 66.0 109 6

Acetochlor oxanilic acid (OXA), water, 

dissolved, recoverable

91 90.2 76.0 100 6

Acetochlor sulfynil-acetic acid (SSA), water, 

dissolved, recoverable

76.5 83.7 67.0 106 6

2-Chloro-N-(2-ethyl-6-methylphenyl) acetamide, water, dissolved, recoverable74 70.7 44.0 89.0 6

2-[(2-Ethyl-6-methylphenyl)amino]-2-oxoethane-sulfonic acid, water, dissolved, 

recoverable

108 109 60.0 140 6

Alachlor, water, dissolved, recoverable 90.5 88.3 42.0 139 6

2-Chloro-N-(2,6-diethylphenyl) acetamide, 

water, dissolved, recoverable

77.5 73.0 50.0 93.0 6

2-[2,6 diethylphenyl amino]-2-oxoethane-sulfonic acid water, dissolved, recoverable111.5 104.0 62.0 125 6

Dechloroalachlor, water, dissolved, recoverable, 78 74.7 54.0 84.0 6

Alachlor (ethane) sulfonic acid (ESA), water, 

dissolved, recoverable

91.5 92.8 90.0 100 6

Alachlor oxanilic acid (OXA), water, 

dissolved, recoverable

90.5 90.5 77.0 104 6

Alachlor sulfynilacetic acid (SAA), water, 

dissolved, recoverable

90.5 79.8 64.0 101 6

Hydroxyalachlor, water, dissolved, recoverable 83 83.5 64.0 111 6

Dimethenamid, water, dissolved, recoverable 89.5 92.3 60.0 142 6

Dechlorodimethen-amid, water, dissolved, 

recoverable

88 85.8 72.0 100 6

Dimethenamid (ethane)sulfonic acid (ESA), 

water, dissolved, recoverable

89.5 89.7 85.0 94.0 6

Dimethenamid oxanilic acid (OXA), water, 

dissolved, recoverable

94 91.0 70.0 108 6

Hydroxydimethenamid, water, dissolved, 

recoverable

87 87.8 64.0 112 5

Flufenacet, water, dissolved, recoverable, 84 89.2 46.0 160 6

Flufenacet (ethane) sulfonic acid (ESA), water, 

dissolved, recoverable

74.5 76.0 46.0 95.0 6
18 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

groundwater samples in the study area (table 4) had recoveries 

within the normal expected range. Therefore, the only limitation in relation to the interpretation of the pesticide data on 

the basis of detected compounds is that the lower than normal 

recoveries for 2-chloro-N-(2,6-diethylphenyl) acetamide and 

propachlor(ethane)sulfonic acid could have limited their detection in groundwater.

The NWQL determined recoveries on wastewater compounds and surrogate wastewater compounds from laboratoryspiked groundwater compounds. Whereas data on spiked 

groundwater samples for all constituents are limited, surrogate 

spikes, which involved four surrogate compounds, were used 

on all groundwater and surface-water samples. A compilation 

of these data (appendix B, table B8) is summarized (table 5), 

and, on the basis of a collaborative review with the NWQL, 

indicates that the pattern in recoveries in groundwater and 

surface-water samples essentially mimicked the pattern the 

NWQL observed in recent laboratory spiked reagent and 

other quality-control blanks. Namely, although recoveries 

of wastewater compounds generally are low compared to 

other analyses for trace organic constituents, the recoveries 

for most wastewater compounds in the spiked groundwater 

sample were similar to levels the NWQL has observed in other 

groundwater samples. In addition, wastewater compound 

surrogate recoveries (mean and range in recovery) from all 

the groundwater samples analyzed from the study area were 

similar to, or better than, the recoveries (mean and range in 

recovery) observed in a similar number of 2010 spiked reagent 

blanks (D. Damrau, USGS, written commun., 2011). 

In relation to recoveries from laboratory spiked groundwater samples, and except for five wastewater compounds, 

recoveries for all other wastewater compounds from groundwater spiked samples were within acceptable ranges (generally 

70 to 130 percent). However, the recovery for 3-beta-coprostanol was quite low (22 percent), and it was not detected in 

any groundwater sample. In addition, recoveries for four 

other compounds—beta-sitosterol, beta-stigmastanol, cholesterol, and cotinine—which ranged between 40 to 60 percent, 

although sufficient to detect each of these compounds in at 

least some groundwater samples, were considered too low to 

provide a reliable description of the occurrence of these compounds in groundwater samples in the study area. Thus, even 

detection data for these five compounds were excluded from 

interpretive analyses.

Recoveries from laboratory-spiked samples also were 

used to assess possible matrix bias effects on the analysis of 

nitrate-plus-nitrite nitrogen, arsenic, and beryllium, each of 

which was analyzed with modified standard methods. For 

these modified methods, laboratory-spiked samples included 

laboratory quality-control and (or) reagent blanks as well as 

groundwater and surface-water samples. For each method, 

recoveries from laboratory-spiked samples fell within the 

normal expected ranges (within approximately 75 to 125 percent of the expected theoretical spiked sample concentration) 

whether the spiked sample was a water-quality sample, or 

Table 4. Matrix bias: Summary statistics for the recovery of pesticides on the basis of U.S. Geological Survey Organic Chemistry 

Research Laboratory low-level analytical methods and laboratory spikes for groundwater samples collected in the Pearce Creek 

Dredge Material Containment Area and vicinity, 2010.—Continued

[Rose-shaded background indicates compound recovery is greater (or less) than normal with normal (mean) recovery being generally between approximately 

75 to 125 percent; Gray-shaded background indicates compounds that were detected in at least one groundwater sample; --, not applicable; <, less than]

Pesticide

Recovery statistics

Median

(percent)

Mean

(percent)

Minimum

(percent)

Maximum

(percent)

Number of 

spiked samples

Flufenacet oxanilic acid (OXA) water, dissolved, recoverable181 165.8 66.0 205 6

Metolachlor, water, dissolved, recoverable 97 86.8 40.0 105 6

Dechlorometolachlor, water, dissolved, recoverable91.5 87.5 54.0 104 6

Metolachlor (ethane) sulfonic acid (ESA), 

water, dissolved, recoverable

93.5 93.3 88.0 100 6

Metolachlor oxanilic acid (OXA), water, dissolved, recoverable88 84.2 59.0 99.0 6

Hydroxymetolachlor, water, dissolved, recoverable90 89.8 76.0 111 6

Propachlor, water, dissolved, recoverable 73.5 83.0 52.0 148 6

Propachlor (ethane) sulfonic acid (ESA), dissolved, water, recoverable-- < 0.050 < 0.050 < 0.050 6

Propachlor oxanilic acid (OXA), water, dissolved, recoverable327.5 266 70.0 358 6
Methods of Water-Quality Data Collection and Data Quality 19

reagent or other laboratory blank (appendix B). Thus, all data 

for nitrate-plus-nitrite nitrogen, arsenic, and beryllium were 

considered unbiased by sample-matrix effects and suitable for 

interpretation.

Measurement Accuracy: Standard Reference 

Samples and Ionic Mass Balances

Standard references samples (SRS), and the calculation 

of the mass balance (MB), as the sum of major cationic constituents minus sum of major anionic constituents, expressed 

in percent, for each groundwater and surface-water sample, 

provide independent checks on the quality of data for selected 

inorganic constituents (Koterba and others, 1995). Both SRSs 

and MBs were employed to assess the accuracy of measurements for the inorganic data collected.

The USGS Branch of Quality Service (BQS), Denver, 

Colo. provided SRSs that were submitted as blind waterquality samples from the field for trace elements (appendix B, table B4). Additional SRS samples also were employed 

by each of the USGS laboratories for the modified analytical 

methods for sulfate, arsenic, and beryllium.

Analytical results for the blind BQS SRS samples 

(appendix B) indicated that except for five trace elements, 

the concentrations of all other trace elements were within 

one (pseudo) standard deviation, and often within ± (plus or 

minus) 20 percent or less of their most probable (median) 

value (MPMV) in either of two SRSs. Exceptions included 

copper, selenium, and uranium in one BQS SRS sample 

(sample TE-197), and thallium, boron, and selenium in another 

BQS SRS (sample TE-199). However, the concentrations for 

these trace elements generally also were acceptable, being 

within ± 30 percent and (or) within two times the (pseudo) 

standard deviation from their MPMVs. For the modified 

analytical methods, all laboratories provided analytical results 

for all their internal SRSs (appendix B). The results indicate 

repeated measurements for all internal SRSs generally fell 

within standard laboratory acceptance criteria, namely within 

80 to 120 percent of the most probable value for a variety of 

SRSs (appendix B). Thus, on the basis of all SRSs analyses, 

concentration data for sulfate and trace elements were considered sufficiently accurate for interpretive analyses. 

Calculated results for MBs (appendix B, table B11) 

were reviewed and summarized (table 6). The MB values 

for groundwater samples indicate a negative bias from the 

theoretical value of zero and an excess of anions for most 

groundwater samples. For observation wells, the mean MB 

is –5.41 meq/L (milliequivalents per liter) ± 35 percent 

(variance), or in relative terms, approximately –15 percent 

± 30 percent. For domestic water-supply wells the bias is 

slightly less than that above for supply wells—the mean 

MB being –1.26 meq/L ± 2.70 percent, or approximately 

–12 percent ± 24 percent. The MB values for surface waters 

are similar in magnitude to MB values for domestic wells 

(appendix B, table B11). 

The causes of the negative bias in the MB values are 

unknown, but they likely are multiple in nature. The laboratory analyses for most major anions, as well as most cations 

and trace elements, such as iron, manganese, and aluminum, 

Table 5. Summary statistics for spike and surrogate recoveries for selected pesticides and other wastewater compounds in 

groundwater samples collected in the Pearce Creek Dredge Material Containment Area and vicinity, 2010–11.

[Recovery, in percent, determined from duplicate sequential samples, one of which was spiked with the actual wastewater compound (or surrogate) by the 

laboratory before analysis, and one of which was used to correct spiked-sample concentration for concentation of wastewater in sample before it was spiked; 

E, estimated, recovery with likely higher than normal uncertainty because of low concentrations—below laboratory reporting levels—in both duplicate 

samples]

Recoveries for groundwater samples spiked with 

actual wastewater compounds: summarized for all 

recoveries for all compounds within the group

Recoveries for each of four laboratory surrogate wastewater compounds: summarized 

for all groundwater samples spiked with all four compounds

Summary

statistics

Wastewater group

Summary 

statistics

Wastewater surrogate compound

Pesticide 

compounds1

(percent)

Other wastewater 

compounds2

(percent)

Bisphenol 

A-d3, surrogate recovery

(percent)

Caffeine-13C, 

surrogate 

recovery

(percent)

Decafluorobiphenyl, surrogate recovery

(percent)

Fluoranthened10, surrogate 

recovery

(percent)

Median E 105 90.3 Median 101 79.7 55.7 80.7

Mean 106 90.69 Mean 100 74.8 56.6 79.7

Minimum E 84.6 E 48.00 Minimum 40.4 24.1 24.9 36.5

Maximum E 126 E 117.0 Maximum 147 105 79.5 106

Number of recovery values 11 56 Number of recovery values 29 29 29 29

1

 Three of the eleven recovery values range from E 84.6 to E 126 percent.

2

 Excludes extremely low estimated recovery of E 22.6 percent for 3-tert-Butyl-4-hydroxyanisole; other recovery values (33 of 56) were estimated values, 

ranging from E 48.0 to E 117 percent. 
20 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

required a range of sample dilution rates be used to reduce 

sample matrix interferences in the analysis of samples for 

each constituent. Dilution rates for a given constituent often 

differed among samples—from as little as 2-fold to as high 

as 50- or 60-fold. Collectively, this could lead to one or more 

systematic biases—such as overestimating the concentrations 

of one or more major anions, or underestimating the concentrations of one or more cations. However, the MB bias also 

simply could be a function of the assumptions regarding the 

charge assigned to each cationic and anionic constituent. For 

example, in the case of iron, as with most other metals, only 

its concentration was determined. The mean MB error can 

be reduced assuming iron is present as Fe3+ rather than Fe2+ 

(table 6), but then variance also increases because the sole 

use of Fe3+ creates high outlier MB values. In actuality, both 

ionic forms of iron could be present and their ratios differ in 

groundwater associated with different well locations. However, determining the individual concentrations of multiple 

ionic species for major constituents such as iron, aluminum, 

and manganese, for each groundwater sample was beyond the 

scope of this report. In addition, the negative bias in MB could 

be the result of not including other possible cationic constituents in the MB calculation—such as organic acid or silica 

species associated with the high concentrations of dissolved 

recoverable organic carbon and dissolved silica (as SiO2

) 

found in groundwater in the DMCA and vicinity (appendix B, 

table B3). Thus, although the MB results do indicate an imbalance in the electroneutrality of samples, it could be erroneous 

to assume and assign this imbalance solely to errors in laboratory measurements. 

Hydrogeologic Framework

A hydrogeologic framework was developed to delineate the shallow groundwater system underlying the Pearce 

Creek DMCA and adjacent residential areas for the purpose of 

defining and understanding the groundwater flow system and 

water quality of the area. The main focus of the framework 

was the definition of the lateral and vertical distribution of the 

aquifers and confining units that ultimately contain and control 

the local groundwater supply. 

Well Network Design

Previous geologic and hydrogeologic investigations were 

used to establish a preliminary hydrogeologic framework for 

the study area. These investigations included hydrogeologic 

data provided in Phase I and II groundwater investigations 

(Maryland Environmental Service, 1995; U.S. Army Corps of 

Engineers, 1996), and data from the following reports: Drummond (2007); Edwards and Hansen (1979); and Mack and 

Achmad (1986). Additionally, new borehole geophysics data 

were collected from existing monitoring wells in the study 

area, and were incorporated with well construction records for 

nearby domestic wells to refine the preliminary hydrogeologic 

framework. This framework was then used to delineate three 

water-bearing units within the top 250 ft of sediments underlying the study area that are being tapped by local water-supply 

wells. 

Findings of the Phase I and II groundwater investigations and subsequent review documents (Maryland Environmental Service, 1995; U.S. Army Corps of Engineers, 1996; 

R.F. Weston, Inc., 1998) stated the need for an expansion of 

the existing (prior to this study) 15-well monitoring network 

for further definition of groundwater flow directions, water 

chemistry, and the sources of degraded water in area wells. 

As part of the 2010–11 USGS study, 28 new monitoring wells 

were installed in the study area. Site selection was based on 

the need for (1) improved spatial and vertical distribution of 

geologic framework, water-level and water-quality data, and 

(2) replacement of 5 of the 15 existing monitoring wells determined to have structural or yield-related problems following 

video logging and redevelopment. 

Table 6. Measurement accuracy: Equivalence mass balance errors for groundwater samples collected in the Pearce Creek Dredge 

Material Containment Area and vicinity, 2010–11.

[meq/L, milliequivalents per liter]

Well type

Mass balance error statistics (assuming iron is present as ferrous iron)

Mean difference 

(meq/L) Variance Mean difference (percent) Variance Number of samples

Observation -5.41 35.4 -15.08 33.1 36

Domestic -1.26 2.70 -12.48 23.6 15

Well type

Mass balance error statistics (assuming iron is present as ferric iron)

Mean difference 

(meq/L)

Variance Mean difference 

(percent)

Variance Number of samples

Observation -2.26 10.5 -3.78 61.5 36

Domestic -0.83 2.17 -6.77 70.6 15
Hydrogeologic Framework 21

The new monitoring wells mainly were installed to create nested well pairs or triplets to determine vertical as well 

as horizontal changes in the direction of groundwater flow 

and quality with depth in the targeted water-bearing units 

(fig. 7). Screen intervals for each well nest were determined 

by initially drilling and gamma-ray logging a deep borehole 

at each site. Screen intervals for the deep well and shallow 

well(s) at each nest were selected on the basis of the interpretation of gamma-ray logs and the lithological nature of core 

material retrieved for the same interval. Well construction data 

for existing and newly installed wells has been summarized 

(appendix A, table A1).

Geologic Setting

The study area is located in the upper Chesapeake Bay 

region approximately 12 mi southeast of the Fall Line, which 

marks the western extent of the Atlantic Coastal Plain physiographic province. Coastal Plain sediments generally are 

classified as a southeast-dipping wedge of unconsolidated 

gravel, sand, silt, and clay that range in age from Cretaceous 

to Holocene. These sediments were deposited in non-marine, 

deltaic, and marine environments on a bedrock surface composed primarily of crystalline metamorphic and igneous rock 

of Cambrian and Precambrian age. Coastal Plain sediments in 

Cecil County range in thickness from a feather edge at the Fall 

Line, which approximately follows Interstate 95 in Maryland, 

to more than 1,500 ft in the southeastern part of the county 

at the Maryland-Delaware border. The depth to crystalline 

bedrock underlying the Pearce Creek study area has been 

estimated at 900 ft (Otton and others, 1988). 

This study focused on the geologic units or parts of units 

that relate directly to the aquifers and confining units that 

comprise the shallow groundwater flow system underlying the 

DMCA and its vicinity. From oldest to youngest these units 

include sediments of the Patapsco Formation (the uppermost 

part of the Potomac Group), the Magothy Formation, and 

the Merchantville Formation of the Matawan Group, all of 

Cretaceous age. Overlying these are the Tertiary Pensauken 

Formation of Pliocene (?) to Miocene (?) age and the surficial 

deposits of Quaternary age. The stratigraphic relation of geologic and hydrogeologic units on the basis of the interpretation 

of the hydrogeologic framework and aquifer nomenclature 

used in this report is shown in table 7. 

Aquifers and Confining Units

Aquifers, water-bearing zones within aquifers, and 

intervening confining units in the study area are described and 

delineated on the basis of stratigraphic correlations derived 

from existing geophysical data combined with collected geophysical data obtained from boreholes during the early stages 

of this study. The recent geophysical data were obtained from 

geophysical logs of existing and newly installed wells within 

the study area (appendix C).

The aquifers and confining units that form the basis for 

the determination of the groundwater flow system underlying 

the DMCA and its vicinity are illustrated in a series of structure contour and isopach maps (figs. 8 and 9). These 

maps along with five related hydrogeologic cross sections 

(figs. 10–15) show the vertical and horizontal relations among 

the hydrogeologic units. Structure contours and hydrogeologic-unit delineation were derived from the interpretation of 

natural gamma-ray logs. Distinctive signatures and patterns on 

gamma-ray logs provided an objective method to mark aquifer 

and confining unit boundaries and facilitate stratigraphic correlation of these units. 

Gamma-ray logs are graphical plots of the rate of emission of gamma rays emitted by the formations penetrated by 

the borehole. In general, silt- and clay-bearing sediments show 

much higher natural gamma activity than do clean quartz 

sands and carbonates. This is because of the ability of clays 

to concentrate radioactive elements through ion exchange 

and adsorption. Feldspars and micas, which readily decompose into clay, also contain small proportions of the gammaemitting radioisotope potassium-40 (Keys and McCary, 1971). 

Gamma radiation increases to the right on the gamma-ray log. 

Therefore, relatively higher radioactive sediments, such as 

silts and clays, cause log deflections toward the right, whereas 

permeable sediments, such as sand and gravel, generally have 

low radioactivity and cause log deflections toward the left. 

The aquifers described herein include the confined upper 

Patapsco aquifer where two distinct water-bearing zones, 

referred to hereafter as the shallow and deep water-bearing 

zones, are defined, and the shallower Magothy aquifer which 

functions in conjunction with overlying surficial deposits as 

either unconfined or confined depending on location. The 

confining units that are mapped include two within the Patapsco Formation: one that lies between the shallow and deep 

water-bearing zones of the upper Patapsco aquifer and another 

that lies between the upper Patapsco aquifer and the overlying Magothy aquifer. Confinement overlying the Magothy 

aquifer, which can include sediments of the Matawan Group 

and (or) fill material in the DMCA, forms the uppermost layer 

described in this framework.

Potomac Group Aquifers

The Potomac Group, which consists largely of a thick, 

complexly interbedded sequence of non-marine unconsolidated sand, silt, and clay, is the basal Coastal Plain unit in the 

study area. As is often characteristic of fluvial sediments, the 

Potomac Group exhibits great lateral variation, which makes 

lithostratigraphic correlation beyond a single outcrop or cluster of closely spaced boreholes difficult. In the upper Chesapeake Bay area south of Cecil County, the Potomac Group 

has been subdivided into three formations (Patuxent, Arundel, 

and Patapsco) (Higgins and Conant, 1990). The Patuxent and 

Patapsco are generally mapped as aquifers whereas the Arundel functions as a confining unit. Farther south in Maryland 

and the middle Eastern Shore, the Patapsco Formation has 
22 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

been subdivided into the lower Patapsco and upper Patapsco 

aquifers (Mack and Achmad, 1986; Drummond, 2007).

In Cecil County, the individual formations of the Potomac 

Group have been difficult to distinguish, particularly in 

outcrop, and are not differentiated on the geologic map of the 

county (Higgins and Conant, 1990). Otton and others (1988) 

in their study of the water resources of Cecil County, use 

borehole geophysics to broadly divide the Potomac Group into 

upper and lower Potomac aquifers using natural gamma-ray 

logs. The water-bearing zones of the upper Patapsco aquifer 

delineated in this report roughly correspond to permeable units 

within the upper Potomac aquifer shown in geologic cross 

sections by Otton and others (1988). Edwards and Hansen 

(1979) used borehole geophysics and pollen data to differentiate the formations of the Potomac Group in borehole CE Dc 

2 near Turkey Point on Elk Neck and borehole CE Ec 17 at 

Grove Point, which are located approximately 2 mi west and 

southwest, respectively, of the Pearce Creek DMCA. The units 

they show as the “Elk Neck beds of the Patapsco Formation” 

(microfloral zone III) correlate well with the hydrogeologic 

units of the Patapsco Formation as subdivided for this study 

(J. Wilson, Maryland Geological Survey, written commun., 

2010). Therefore, this report uses the terminology of the upper 

Patapsco aquifer in the description of hydrogeologic units 

delineated within the uppermost Potomac Group sediments 

underlying the study area.

Upper Patapsco Aquifer

In the study area, the upper Patapsco aquifer is mapped as 

a multi-layer aquifer system. Two distinct water-bearing zones 

(shallow and deep) separated by a clay/silt confining unit 

have been delineated (table 7; figs. 11–15). This multi-layer 

division is supported by natural gamma-ray log stratigraphy, 

water-level data, domestic well completion records and waterquality conditions. The high density of data made it possible to 

correlate these individual units in the study area. The waterbearing zones and confining units exhibit the fluvial nature of 

0

0

0.5 1.0 MILE

0.5 1.0 KILOMETER

Property boundary of 

Pearce Creek Dredge 

Material Containment 

Area 

West View Shores

Pond Neck Road

N

Elk River

Pearce Creek Lake

Crystal Beach

Bay View 

Estates

126 136

191

192

193

153

154

155

122

123, 139 

124

81 151 ,

152

127

141

133 135

132

134

125

130

128

129 150

145

146

147 131

157

158

148

149

144

144

137

138

156

159

140

160

142

143

Location of well or well nest

Existing well and identifier 

New well and identifier

Color of well identifier denotes aquifer 

monitored

Local perched zone

Magothy aquifer

Upper Patapsco aquifer, shallow 

 water-bearing zone

Upper Patapsco aquifer, deep 

 water-bearing zone 

EXPLANATION

129

146

136

126

141

Figure 7. Monitoring well network, Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, 

Maryland, 2010–11. 
Hydrogeologic Framework 23

the deposition, which locally includes substantial changes of 

unit thickness and lithology over short distances, and fewer 

data points may have prevented the correlation of these units. 

These changes are characteristic of the riverine deposition of 

the Patapsco Formation in comparison to the broad sheet-like 

deposits characteristic of marine and marginal marine deposition of the overlying Magothy and Matawan units. Although 

the hydrogeologic units of the upper Patapsco Formation can 

be separated locally, at a regional scale these water-bearing 

zones could be connected to form a more extensive aquifer 

system.

Upper Patapsco Aquifer Deep Water-Bearing 

Zone

The upper Patapsco aquifer deep water-bearing zone is 

the deepest hydrogeologic unit penetrated in the study area 

and provides water for only a small number of homes in residential areas near the DMCA. Of the available well completion reports for the area it is estimated that the upper Patapsco 

aquifer deep water-bearing zone provides water for less than 

8 percent of area wells. 

Structure contours on the top of the upper Patapsco 

aquifer deep water-bearing zone reflect data obtained from 

seven boreholes (at six locations) that penetrate the top of this 

unit (fig. 8A). The altitude of the top of the unit ranges from a 

maximum of approximately –150 ft just north of the southern 

boundary of the perimeter dike to –180 ft NAVD 88 at the 

edges of the area. The upper Patapsco aquifer deep waterbearing zone ranges in thickness from 40 to 55 ft at three 

sites where the entire unit was penetrated in the borehole. The 

predominant lithology based on continuous sediment core is 

medium to coarse-grained sand, well-sorted, and ranging in 

color from light tan to brown and gray.

Confining Unit Between the Upper Patapsco 

Aquifer Shallow and Deep Water-Bearing Zones

The thickness of this confining unit generally ranges 

from 40 to 50 ft within the DMCA, increases to more than 

80 ft near the Elk River in WVS (West View Shores residential 

community), and decreases to approximately 25 ft between 

the aquifers along the southeastern property boundary of the 

DMCA (fig. 8B). Dominant lithologies of the confining unit 

are gray to dark gray clay and silty clay, often with reddish 

mottling, with lignite and thin fine-grained sand lenses present. 

Table 7. Stratigraphic correlation chart of geologic and hydrogeologic units in the Pearce Creek Dredge Material Containment Area 

and vicinity.

[Geology from Higgins and Conant, 1990, and Edwards and Hansen, 1979; hydrogeology modified from Otton and others, 1988]

System Series Group Geologic

formation Hydrogeologic unit

Quaternary Holocene undifferentiated

Surficial deposits locally part of Magothy 

aquifer where Matawan confining unit is thin 

or missing—anthropogenic fill material is 

considered part of Matawan confining unit

Tertiary Miocene Pensauken

Surficial deposits locally part of Magothy 

aquifer where Matawan confining unit is thin 

or missing

Cretaceous

Upper

Cretaceous

Matawan Merchantville Matawan confining unit

Magothy Magothy aquifer

Lower

Cretaceous Potomac

Patapsco

upper Patapsco confining unit

upper Patapsco aquifer

shallow water-bearing zone

confining unit

upper Patapsco aquifer

deep water-bearing zone

undifferentiated

undifferentiated aquifers and confining units

Lower Paleozoic to Precambrian consolidated basement rocks
24 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

Figure 8.

A, Structure contours of the top of the upper Patapsco aquifer deep water-bearing zone, 

B, thickness of the confining unit between the upper Patapsco 

aquifer shallow and deep water-bearing zones, 

C, structure contours on the top of the upper Patapsco aquifer shallow water-bearing zone, and 

D, thickness of the 

upper Patapsco aquifer shallow water-bearing zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11.

0 1,000 2,000 FEET

0 200 400 600 METERS Base map from Cecil County, Maryland government

Maryland State Plane coordinate system North American Datum of 1983

75°58'30" 75°59' 75°59'30"

39°26'

39°25'30"

75°58'30" 75°59' 75°59'30"

39°26'

39°25'30"

75°58'30" 75°59' 75°59'30"

39°26'

39°25'30"

75°58'30" 75°59' 75°59'30"

39°26'

39°25'30"

-65

-54

-37

-53

-44

-69

-40

-32

-67

-33

-76

-32

-55

-57

-28 -28

-54

-70

-102

-80

-60

-100

-40

66

68

56

52

51

68

26

58

55

60

50

40

30

60

-159

-152

-143

-179

-167

-192

-170

-160

-180

-150

40

83

60

43

52

51

28

25

60

D

C

B

A

-180

Elk River

Pearce Creek Lake

Elk River

Pearce Creek Lake

Elk River

Pearce Creek Lake

Elk River

Pearce Creek Lake

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

Structure contour —Shows altitude of the top of the upper Patapsco aquifer, 

shallow water-bearing zone. Contour interval 20 feet. Datum is North American Vertical Datum of 1988

Well location—Number is altitude, in feet, of the top of the upper Patapsco 

aquifer, shallow water-bearing zone

-60

-55

EXPLANATION

Line of equal thickness of the upper Patapsco aquifer, shallow water-bearing 

zone—Contour interval 10 feet

Well location—Number is the thickness, in feet, of the upper Patapsco aquifer, 

shallow water-bearing zone

60

51

EXPLANATION

Structure contour—Shows altitude of the top of the upper Patapsco aquifer, 

deep water-bearing zone. Contour interval 10 feet. Datum is North American Vertical Datum of 1988

Well location—Number is altitude, in feet, of the top of the upper Patapsco 

aquifer, deep water-bearing zone

-152

-150

EXPLANATION

Line of equal thickness of the confining unit between the upper Patapsco 

aquifer shallow and deep water-bearing zones—Contour interval 20 feet

Well location—Number is the thickness, in feet, of the confining unit between 

the upper Patapsco aquifer, shallow and deep water-bearing zones

25

40

Altitude of the top of the upper Patapsco aquifer, deep water-bearing zone

EXPLANATION

Thickness of the confining unit between the upper Patapsco

aquifer shallow and deep water-bearing zones

Altitude of the top of the upper Patapsco aquifer, shallow water-bearing zone Thickness of the upper Patapsco aquifer, shallow water-bearing zone
Hydrogeologic Framework 25

65

44

75°58'30" 75°59' 75°59'30"

39°26'

39°25'30"

75°58'30" 75°59' 75°59'30"

39°26'

39°25'30"

75°58'30" 75°59' 75°59'30"

39°26'

39°25'30"

75°58'30" 75°59' 75°59'30"

39°26'

39°25'30"

8

17

48

28

15

52

31

36 36

41

37

24

40

8

8

2

7 0 -5

25

13

21

-5

-1

28

27

22

-8

21

24

11

-3

4

0

20

-20

0

20

40

60

20

48

51

18

50

15

40

32

39

40

42

10

50

54

44

32

34

21

44

40

20

50

40

50

D

C

B

A

0 0 0

8

21

44

12

51

45

20

27

50

33

11

62

44

44

23

30

40

20

10

50

60

0

30

20

Pearce Creek Lake Pearce Creek Lake

Pearce Creek Lake Pearce Creek Lake

0 1,000 2,000 FEET

0 200 400 600 METERS

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

Elk River

Elk River

Elk River

Elk River

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

40

52

EXPLANATION

Structure contour—Shows altitude of the top of the Magothy aquifer. Contour interval 20 feet. 

Datum is North American Vertical Datum of 1988

Well location —Number is altitude, in feet, of the top of the Magothy aquifer

20

25

EXPLANATION

Line of equal thickness of the Matawan confining unit—Contour interval 

20 feet

Well location—Number is the thickness, in feet, of the Matawan 

confining unit 

40

40

EXPLANATION

Line of equal thickness of the Magothy aquifer—Contour interval 10 and 20 feetWell location—Number is the thickness, in feet, of the Magothy aquifer

44

40

EXPLANATION

Line of equal thickness of the upper Patapsco confining unit—Dashed where 

approximate. Contour interval 10 feet

Well location—Number is the thickness, in feet, of the upper Patapsco 

confining unit

Thickness of the upper Patapsco confining unit 

Thickness of the Magothy aquifer Thickness of the Matawan confining unit

Altitude of the top of the Magothy aquifer

Figure 9.

A, Thickness of the upper Patapsco confining unit, 

B, structure contours on the top of the Magothy aquifer, 

C, thickness of the Magothy aquifer, and 

D, thickness of the Matawan confining unit in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11. 
26 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area 75°59’ 75°59’30” 75°58’30” 39°26' 39°25' 39°25'30" Pearce Creek Lake

Elk River

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

A

B

C

D

E

F

G

EXPLANATION

127

141

160

128

152

122

129

156

147

126

158

138

149

125

155

193

191

150

130

142

142

A

B

Location of well and identifierTrace of hydrogeologic cross section

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

Figure 10.

Well locations and lines of hydrogeologic sections, Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, 

Maryland. (Individual lines of section are described further in figures 11

–15.) 
Hydrogeologic Framework 27

CE Dd 141 CE Dd 160 CE Dd 128 CE Dd 152

Magothy aquiferUpper Patapsco aquifershallow water-bearing zone

Upper Patapsco aquifer

deep water-bearing zone

Wellidentifier

Gamma ray log

Well location

EXPLANATION

Sections dashed where approximately 

located

5025

-25-50-75

-100-125-150-175-200-225-250

0

0 500 1,000 1,500 2,000 2,500 3,000

Distance, in feet

A

B

Altitude, in feet above or below North American Vertical Datum of 1988 Confining unit

confining unit Upper Patapsco

VERTICAL EXAGGERATION x 6.5

BEND IN

SECTION

BEND IN

SECTION

Figure 11. Hydrogeologic section A–B, correlation based on gamma logs at boreholes (wells) indicated, Pearce Creek Dredge Material Containment Area and 

vicinity, Cecil County, Maryland. (Location of section is shown in figure 10.)
28 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area Gamma ray log Well location Magothy aquifer Matawan confining unit Magothy aquifer Upper Patapsco confining unit Upper Patapsco aquifer shallow water-bearing zone Upper Patapsco aquifer deep water-bearing zone 5025 -25 -50 -75 -100 -125 -150 -175 -200 -225 -250

0

0 1,000 2,000 3,000 4,000 5,000 6,000

Distance, in feet

B

C

Altitude, in feet above or below North American Vertical Datum of 1988 Confining unit

Confining unit

VERTICAL EXAGGERATION x 13

EXPLANATION

Sections dashed where approximately 

located

CE Dd 152

CE Dd 130

CE Dd 122 CE Dd 138 CE Dd 155 Well

identifier

Figure 12. Hydrogeologic section B–C, correlation base on gamma logs at boreholes (wells) indicated, Pearce Creek Dredge Material Containment Area 

and vicinity, Cecil County, Maryland. (Location of section is shown in figure 10.)
Hydrogeologic Framework 29

Magothy aquifer

Upper Patapsco aquifershallow water-bearing zone

Upper Patapsco aquifer

deep water-bearing zone

Wellidentifier

5025

-25-50-75

-100-125-150-175-200-225-250

0

0 1,000 2,000 3,000 4,000 5,000 6,000

Distance, in feet

A

E

Altitude, in feet above or below North American Vertical Datum of 1988 Confining unit

VERTICAL EXAGGERATION x 13

CE Dd 141 CE Dd 156 CE Dd 147

Upper Patapsco

confining unit

Gamma ray log

Well location

EXPLANATION

Sections dashed where approximately 

located

Figure 13. Hydrogeologic section A–E, correlation based on gamma logs at boreholes (wells) indicated, Pearce Creek Dredge Material Containment Area and 

vicinity, Cecil County, Maryland. (Location of section is shown in figure 10.)
30 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area Magothy aquifer Upper Patapsco aquifer shallow water-bearing zone Well identifier 5025 -25 -50 -75 -100 -125 -150 -175 -200 -225 -250

0

0 1,000 2,000 3,000 4,000 5,000 6,000

Distance, in feet

D

E

Altitude, in feet above or below North American Vertical Datum of 1988

CE Dd 138 CE Dd 158 CE Dd 126 CE Dd 147

Upper Patapsco

confining unit

Confining unit

VERTICAL EXAGGERATION x 13

CE Dd 149

Gamma ray log

Well location

EXPLANATION

Sections dashed where approximately 

located

Matawan confining unit

Figure 14. Hydrogeologic section D–E, correlation based on gamma logs at boreholes (wells) indicated, Pearce Creek Dredge Material Containment Area and 

vicinity, Cecil County, Maryland. (Location of section is shown in figure 10.)
Hydrogeologic Framework 31 Figure 15. Hydrogeologic section F–G, correlation based on gamma logs at boreholes (wells) indicated, Pearce Creek Dredge Material Containment Area and vicinity, Cecil County, Maryland. (Location of section is shown in figure 10.)

Magothy aquifer

Upper Patapsco aquifer shallow water-bearing zone

Upper Patapsco aquifer

deep water-bearing zone

Wellidentifier 50

25

-25-50-75

-100-125-150-175-200-225-250

0

0 1,000 2,000 3,000 4,000 5,000 6,000

Distance, in feet

F

G

Altitude, in feet above or below North American Vertical Datum of 1988

CE Dd 155 CE Dd 191 CE Dd 150

Upper Patapsco

CE Dd 125

confining unitConfining unit

Confining unit

VERTICAL EXAGGERATION x 13

Gamma ray log

Well location

EXPLANATION

Sections dashed where 

approximately located

Matawan confining unit
32 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

Upper Patapsco Aquifer Shallow Water-Bearing 

Zone

The upper Patapsco aquifer shallow water-bearing zone 

provides water for the majority of domestic wells along Pond 

Neck Road and the lower half of WVS nearer the Elk River. 

Of the available well-completion reports for the area, it is estimated that the upper Patapsco aquifer shallow water-bearing 

zone provides water for approximately 71 percent of area 

wells. 

Structure contours of the top of the upper Patapsco aquifer shallow water-bearing zone indicate the altitude of the top 

of the unit ranges from approximately -40 ft NAVD 88 in the 

WVS area to -102 ft NAVD 88 at monitoring well CE Dd 150 

located east of the DMCA perimeter dike (fig. 8C). The thickness of the upper Patapsco aquifer shallow water-bearing zone 

ranges between 50 and 60 ft for much of the DMCA and WVS 

(fig. 8D). The unit thins to less than 30 ft in thickness near 

the eastern property boundary of the DMCA. Characteristic 

lithologies include fine to medium-grained gray, brown, tan, 

and locally orange sands with occasional thin beds of gravel. 

Clay and silt stringers within the unit are common, with some 

clay lenses as much as 5 to 10 ft thick.

Upper Patapsco Confining Unit

The confining unit overlying the upper Patapsco aquifer 

shallow water-bearing zone increases in thickness from 30 to 

more than 60 ft from the center of the DMCA north toward 

Elk River and Pearce Creek Lake (fig. 9A; section D–E, 

fig. 14; section F–G, fig. 15). The unit thins to the south and 

is missing in the southwestern corner of the DMCA near wells 

CE Dd 81, 130, 122, 123, and 124. The unit is also missing in the southeastern most part of WVS (fig. 9A; section 

A–B, fgure 11; and section B–C, fig. 12), which places the 

upper Patapsco aquifer shallow water-bearing zone in direct 

hydraulic connection with the overlying Magothy aquifer. This 

hydraulic connection between the two aquifers in this area has 

direct implications on the groundwater flow system and water 

quality. The contact at the bottom of the Magothy aquifer and 

the top of the upper Patapsco aquifer shallow water-bearing 

zone on hydrogeologic sections where the upper Patapsco 

confining unit is missing is inferred and not meant to imply an 

exact boundary between geologic formations.

There is a substantial increase in the thickness of the 

upper Patapsco confining unit, and separation between the 

Magothy aquifer and upper Patapsco aquifer shallow waterbearing zone, from southeast to northwest through WVS and 

parallel to Elk River (section A–B, fig. 11; and section A–E, 

fig. 13, respectively). Continuous core retrieved during drilling 

for this study shows that the clays and silty clays of the upper 

Patapsco confining unit can be quite variable in color but are 

typically dark gray or red with lignite throughout.

Magothy Aquifer

The Magothy aquifer consists of sediments of the Cretaceous Magothy Formation. As defined herein, the aquifer 

can contain the overlying Tertiary Pensauken Formation and 

younger surficial Quaternary sands and gravels where unconfined. In the study area, the aquifer is composed predominantly of light colored white, yellow, tan, and gray medium to 

coarse-grained quartz sand and fine gravel. Beds of red brown 

iron stained sand and gravel are also present particularly near 

the top of the aquifer.

The Magothy aquifer is the uppermost aquifer encountered in the study area. Of the available well-completion 

reports for the area, it is estimated that the aquifer provides 

water for approximately 21 percent of area wells, most of 

which are located in the upper part of WVS near the DMCA 

property boundary.

The Magothy aquifer is unconfined from the Elk River 

eastward to near the western berm of the DMCA (figs. 9B and 

9D; section A–B, fig. 11). Therefore, the altitude of the top of 

the unit is land surface where the unit is exposed west of the 

berm. Across the DMCA, the top of the unit is encountered at 

approximately 0 ft NAVD 88. The aquifer generally ranges in 

thickness from 40 to 50 ft throughout most of the study area 

except near the Elk River where the aquifer thins to less than 

20 ft and is likely composed predominantly of younger Tertiary and (or) Quaternary deposits (fig. 9C; section A–B, fig. 

11; section A–E, fig. 13).

Matawan Confining Unit and Fill

Matawan Group sediments that overly the Magothy 

aquifer form a regional confining unit in the Maryland Coastal 

Plain (Otton and others, 1988). Higgins and Conant (1990) 

noted that the Merchantville Formation is the predominant 

component of Matawan Group sediments in the study area. 

Higgins and Conant also mapped a large area they refer to 

as spoil material indicated to be mixtures of soil, sand, clay, 

gravel, and debris from dredging operations. This fill material 

in part directly overlies the Magothy aquifer in the western 

part of the DMCA and overlies the Merchantville Formation 

in the eastern part of the DMCA. It is also likely that the fill 

material overlies the original wetland sediment, thus creating 

a buried layer of organic rich material. The Matawan confining unit is predominantly a dark gray to green clay and silty 

clay with lignite and organic detritus present. Because the fill 

imparts a degree of confinement, is locally as much as 25 ft 

thick, and is difficult to distinguish hydrologically from the 

underlying Merchantville Formation sediments, both fill and 

Merchantville Formation sediments are included in the total 

thickness of the confining unit. Confinement overlying the 

Magothy aquifer increases from 0 to more than 40 ft eastwardly across the DMCA as 20 to 30 ft of fill is encountered 

and as the overlying Matawan Group sediments increase 

in thickness in the easterly down-dip direction (fig. 9D; 

section B–C, fig. 12).
Hydrogeologic Framework 33

Chemical Composition of Sediments

For the purposes of this study, no data are available (or 

obtainable) on the chemical composition of the canal or Elk 

River sediments deposited in the DMCA during its use. Nor 

are there data on the chemical composition of native sediments in the area of the DMCA or vicinity that predate the 

creation and use of this facility. However, studies have been 

conducted on the composition of Chesapeake Bay sediments, 

which include the northern part of the Chesapeake Bay and 

Elk River Estuary. Limited data collected by the USACE after 

the closure of the DMCA also are available on the chemical 

composition of the surficial (fill-Matawan) sediments, and on 

sediments in the underlying aquifers and confining beds in the 

DMCA, as well as in the vicinity of the DMCA.

Northern Chesapeake Bay Sediments

The chemical composition of sediments in the Chesapeake Bay, hereafter referred to as bay sediments in this 

report, has been the subject of several studies. Early studies by 

Sinex and Helz (1981) describe the concentration and regional 

geochemistry of trace elements in bay sediments about the 

time the DMCA was in its final decade of use. Except for 

chromium, the authors found that bay sediments north of 

Baltimore, Md., are enriched 3 to 8 times relative to sediments 

in the remainder of the bay in the concentrations of most trace 

elements, including cobalt, copper, iron, manganese, nickel, 

and lead. Concentrations of metals in digested1 upper bay 

sediments were on the order of hundreds of milligrams per 

kilogram for cobalt, copper, nickel, and lead; thousands of 

milligrams per kilogram for manganese; and tens of thousands of milligrams per kilogram for iron. They also identified 

that the chief sources of the enriched metals are fine-grained 

(less than 63-μm fraction) sediments, which are prevalent 

throughout the northern part of the bay. In a subsequent study, 

Marvin-DiPasquale and Capone (1998) found that greater than 

50 percent of the sulfur, as labile sulfate (35SO4

2–), annually 

introduced in in-situ surficial (0- to 12-cm depth) sediments in 

the upper bay was reduced to (ferrous) iron sulfide (FeS). 

In a recent and broad comprehensive study of bay sediment contaminants, Hartwell and Hameedi (2007) examined 

the magnitude and extent of contaminants in recently deposited shallow (upper 2- to 3-cm or upper 10-cm) bay sediments. 

For three sites on Elk River Estuary, sediments found at two 

of three sites—the mouth of the estuary near WVS and farther 

up river just above the C&D Canal (Chesapeake and Delaware Canal)—were considered to be in the top 10th percentile 

of all contaminated sites. As for most sites in this percentile 

category, sediment samples from these two sites consisted of 

a relatively high percentage of fine-grained silts and clays, 

which as noted above, appear prone to the absorption and 

retention of inorganic and organic contaminants. In particular, 

1

 Four-hour digestion with 90 percent nitric acid and 10 percent 

hydrochloric acid.

Hartwell and Hameedi (2007) provide data on the two Elk 

River estuary sites, which when compared to other middle and 

lower bay estuaries were:

1. High in most of the 15 extractable2 trace elements on the 

basis of their mean normalized total metal concentration, 

which was approximately 32 percent; 

2. moderately high in selected insecticides, such as dichlorodiphenyltrichloroethane (DDT) and (or) DDT metabolites 

(approximately 4 μg/kg (micrograms per kilogram)), 

chlorpyrifos (approximately 0.4 μg/kg), and chlordanes 

and related cyclodienes (approximately 2 μg/kg), as well 

as total chlorinated benzenes (approximately 2–3 μg/kg);

3. moderate in levels of low-weight polyaromatic hydrocarbons (PAHs) (approximately 250–500 μg/kg), and 

polychlorinated biphenyls (about 10–20 μg/kg); and

4. moderately low to low in high-weight PAHs (500–

1,000 μg/kg) insecticides such as hexachlorcyclohexane 

(HCH) (approximately 0.1 μg/kg), butylins (approximately 5 μg/kg), and total PAHs normalized for total 

organic carbon (approximately 1,000 or less μg/kg).

Hollweg and others (2009) also recently characterized the 

general chemical composition of bay sediments to assess rates 

of mercury methylation, which included sediment results 

from northern bay sites most applicable to Elk River Estuary 

(table 8). Because of the nature of their study, all sediment 

samples were collected, maintained, processed, and analyzed 

under anerobic (oxygen-free) conditions. Thus, their data 

reflect the in-situ chemical composition of bay sediments and 

sediment pore water. In comparison with middle and lower 

bay sediments, they concluded that upper bay sediments were 

low in bulk density, and high in total and organic carbon, 

sulfur, nitrogen, and iron (II). Extractable bulk-phase metallic 

monosulfides and polysulfides (table 8, acid-volatile sulfide 

and chromium reduced sulfide, respectively) also were high 

and include, for example, ferrous sulfide (FeS) and pyrite 

(FeS2

). In addition, pore waters from these sediments as well 

as other bay sediments were highly alkaline in pH (a mean 

pH of 8.4, with a standard deviation of 0.2). Compared to 

middle and lower bay sediments, however, the authors noted 

that northern bay sediments contained little nitrate-plus-nitrite 

nitrogen, moderately low concentrations of sulfate, moderate 

concentrations of sulfide, and relatively high concentrations of 

total iron and total manganese (table 8).

Dredge Material Containment Area and Vicinity 

Sediments

Limited data are available on the chemical composition 

of surficial and underlying sediments in the DMCA. The 

readily available data reflect sediment samples taken and 

analyzed by the USACE after the closure of the facility in 

2

 Extraction methods could not be documented. 
34 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

1992 (U.S. Army Corps of Engineers, 1996). The individual 

sediment-sample data from that report were categorized and 

grouped on the basis of their original location and depth of 

sampling to provide statistical summaries of the chemical data 

in relation to the hydrogeologic framework of the study area 

as described above in this report (tables 9 and 10).

As of 1995–96, when the sediment samples were collected, all sediments in and beneath the DMCA contained 

relatively high concentrations of iron, with the highest concentrations being associated with fill-Matawan sediments, which 

were of many types (table 9). The fill-Matawan sediments also 

contained relatively elevated concentrations of manganese, 

zinc, and copper. Slurry or pore waters3 associated with all 

sediments generally were acidic. Concentrations of sulfate 

were highest associated with the fill-Matawan sediments, but 

also occurred at elevated concentrations in water associated 

with the underlying Magothy aquifer sands, and the confininglayer silt, peat, and (or) clay. Sulfide also occurred at measurable concentrations in slurry or pore waters associated with 

at least some sediment samples from the fill-Matawan and 

underlying aquifer and confining unit sediments.

In the vicinity of the DMCA, all sediments except those 

associated with the Magothy aquifer contained relatively high 

concentrations of iron (table 10). Most other metals were at 

moderate to low concentrations, with metal concentrations 

associated with confining-unit sediments being higher than 

metal concentrations associated with sediments in either the 

Magothy aquifer or upper Patapsco aquifer shallow waterbearing zone. Slurry or pore waters associated with all 

sediments also generally were acidic. Sulfate concentrations 

appeared to be highest in sediments associated with the upper 

Patapsco aquifer shallow water-bearing zone. Sulfide concentrations also were measurable in sediments associated with 

both confining units and both aquifers; consistently high concentrations occurred in the confining unit sediments between 

the Magothy and upper Patapsco aquifers. 

Sediment Chemistry Comparisons 

Other than broad comparisons and contrasts, further 

interpretive analyses of the chemical composition of the bay 

and DMCA sediments are limited, in part by the fact that the 

sediment samples reflect two very different aquatic environments, and, in part, because the methodologies used to collect, 

preserve, and analyze samples associated with each of these 

environments differed appreciably. For example, it already 

was noted that the collection, preservation, and analysis of bay 

sediment samples were conducted excluding sample exposure 

to oxygen. It is unlikely that this condition could have been 

maintained during the collection, preservation, and analysis of 

sediment samples from the DMCA or its vicinity. Thus, results 

for redox-sensitive species, such as iron, manganese, nitrate 

and nitrite nitrogen, sulfide, and sulfate, could be biased if 

3

 Unable to confirm whether analyses reflected pore waters or sediment 

slurries.

sediment samples were even partially oxidized during these 

procedures. 

Despite the obvious differences, the bay sediment data 

indicate that these sediments contain appreciable amounts of 

carbon, nitrogen, and sulfur, as well as several trace elements 

such as iron and manganese. These sediments appear also to 

be quite alkaline (pH approximately 8) and contain appreciable mono and poly sulfides and sulfate but little nitrateplus-nitrite nitrogen. Collectively, the above results indicate 

an environment that appears to be in a fairly reduced state. 

By comparison, sediments in the DMCA and its vicinity also 

exhibit many of the same chemical sediment characteristics as 

bay sediments, including elevated concentrations of iron and 

manganese, as well as sulfate and measurable sulfide, which 

could also reflect an environment that is possibly in a similar 

reduced state. There also is clearly one marked difference 

between bay and DMCA sediments: whereas the pH of the 

former appears distinctly alkaline (table 8, pH 8.4 (mean) 

± 0.2 (standard deviation)), the pH of the latter appears distinctly acidic (table 9, pH 3.0 to 6.2).

Because similar methods were used to collect, preserve, 

and analyze sediment samples in the DMCA and vicinity, one 

can compare and contrast their sediment chemical composition. For example, iron is highly abundant, and manganese 

moderately abundant, in sediments in and within the vicinity of the DMCA (tables 9 and 10, respectively). All other 

metals occur at relatively low concentrations in sediments in 

and within the vicinity of the DMCA. Slurry or pore water is 

acidic and contains measurable concentrations of sulfide in 

sediments in the DMCA and its vicinity. 

There are differences in the concentrations of selected 

constituents in sediments in the DMCA and its vicinity. Concentrations of iron outside the DMCA generally are similar 

to iron concentrations in sediments in the DMCA, regardless 

of whether one is comparing these sediment concentrations 

between the surficial sediments, or the underlying Magothy 

aquifer, confining unit, or upper Patapsco aquifer shallow 

water-bearing zone. However, manganese and zinc concentrations occur at higher concentrations in the surficial fillMatawan sediments in the DMCA compared to the surficial 

Matawan sediments outside of the DMCA. The same pattern 

also occurs for the confining unit between the Magothy aquifer 

and upper Patapsco aquifer shallow water-bearing zone; but 

the order is reversed for sediments in the upper Patapsco 

aquifer shallow water-bearing zone. Sediments in this zone in 

the DMCA appear to contain more manganese and zinc than 

sediments in this zone outside of the DMCA.

The above information cannot be interpreted fully without knowing the patterns in groundwater flow in the study 

area and the geochemical processes that could occur within 

the groundwater flow system. For example, whether or not 

the chemical composition of sediments in the vicinity of the 

DMCA reflect native sediments, and thus a potential independent source area for recharge that influences the chemistry of 

groundwater in the area, depends on the answers to several 
Hydrogeologic Framework 35

Table 8. Summary data on the chemical composition of shallow Chesapeake Bay sediments and pore water from fresh sediment-core samples, 2005–06 (modified from Hollweg and others, 2009).[g, wet wt/cm3, grams wet weight per cubic centimeter; wt, weight; g, wet wt/g dry wt, grams wet weight per grams dry weight; mL/cm3, milliliters per cubic centimeter; mg/kg, milligrams per kilogram; 

mg/L, milligrams per liter; μg/L, micrograms per liter; N, north; W, west; Fe, iron; Mn, manganese]

Areal location Sample type Statistical measure1

Bulk 

density

(g, wet 

wt/cm3)

Wet-dry ratio

(g, wet wt/g, 

dry wt)

Porosity

(mL/cm3)

Loss on ignition

(percent)

Carbon, 

total

(mg/kg, 

dry wt)

Sulfur, 

total

(mg/kg, 

dry wt)

Nitrogen, 

total

(mg/kg, 

dry wt)

Acidvolatile 

sulfide2, as 

sulfur

(mg/kg, dry 

wt)

Chromuimreduced 

sulfide2, as 

sulfur

(mg/kg, dry 

wt)

Fe(II), extractable

(mg/kg, dry 

wt)

Upper Chesapeake Bay main channel (latitude 392056.4 N, longitude 761049.8 W)

Sediment:

Mean 1.34 2.28 0.746 6.38 21,810 8,270 2,380 718 4,425 505

Standard 

deviation 0.11 0.18 0.034 0.92 1,322 545 370 253 962 205

pH

(standard 

units)

Nitrate-nitrite 

as nitrogen3

(mg/L)

Sulfate

(mg/L)

Sulfide, as 

sulfur3

(mg/L)

Fe, total

(μg/L)

Mn, total

(μg/L)

Pore 

water:

Mean 8.36 0.0444 219 0.0702 3,300 4,290

Standard 

deviation 0.17 0.0080 74 0.0491 2,030 2,690

1 Grand mean and standard deviation of means and standard deviations for analyses conducted on a dozen or more subsamples of sediment and pore-water analyses collected and analyzed on four different 

cruises from May 2005 through April 2006.

2 Acid volatile sulfide (AVS) is sulfide which is distilled as hydrogen sulfide from sediments exposed to 6 Normal (oxygen-free) hydrochloric acid; chromium reduced sulfide (CRS) is sulfide which is 

distilled as hydrogen sulfide from sediments exposed to hot, freshly prepared chromium (II) 0.5 Normal hydrochloric acid. In the context of this report. AVS is presumed to measure labile soluable sulfides, 

including polysulfides and metal (M) monosulfides (MS), with M for example, being iron, manganese, and (or) zinc; and CRS is presumed to measure relatively nonlabile and insoluable sulfide minerals such as pyrite (FeS2).

3 Standard deviation provided by Dr. Terrill Hollweg (written commun., 2011), which was inadvertently excluded during final publication. 
36 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area Table 9. Summary data on chemical composition of sediments in and underlying the Pearce Creek Dredge Material Containment Area from sediment-core samples obtained from selected boreholes, 1995–96 (modified from U.S. Army Corps of Engineers, 1996). [USACE, U.S. Army Corps of Engineers; USGS, U.S. Geological Survey; X or XXX, a numerical value associated with site identifier; ft, feet; bls, below land surface; mg/L, milligrams per liter; mg/kg, milligrams per kilogram; DMCA, Dredge Material Containment Area; WVS, West View Shores; UPA shallow, upper Patapsco aquifer shallow water-bearing zone; MA, Magothy aquifer; <, undetected at concentration indicated; E, estimated; ---, not determined; mean provided when constituent had measureable values for all samples, and median could not be determined due to even number of samples; N, spiked sample recovery not within control limits] Areal location and water- bearing zone or confining unit USACE local identifier (CSW X) USGS local identifier (CE Dd XXX) Depth interval of sample (ft bls) Sample sediment type(s) Statistical measure Pore water Sediment Sulfide (mg/L) Sulfate (mg/L) pH (standard units) Arsenic, extract- able (mg/kg) Copper, extract- able (mg/kg) Iron, extract- able (mg/kg) Lead, extract- able (mg/kg) Man- ganese, extract- able (mg/kg) Zinc, extract- able (mg/kg) DMCA, fill- Matawana 1, 2, 3b, 14 and 15 122, 126, 134, and 135 Within 0–34 Sands and silty sands, silts, clayey and sandy silts, clays Mean --- 1,118 5.05 7.7 18.6 19,093 21.6 797 95.6 ± SD --- 842 0.67 3.9 11.4 9,602 13.6 723 67.3 Median 13.0 1,000 5.15 8.10 16.1 21,500 20.5 668 87.3 Minimum < 4.99 259 3.83 0.43 2.80 751 2.8 37.1 2.0 Maximum 210 3,500 6.20 18.4 E 48.8 36,100 48 3,270 252 Number of samples 21 21 21 21 21 21 21 21 21 DMCA, MA 2, 3b, 14, and 15 126, 134, and 135 Within 34–92 Sands Mean --- 299 4.26 2.2 2.2 2,860 3.1 81 5.8 ± SD --- 471 0.84 0.7 0.4 2,243 1.7 71 4.9 Median < 0.2 26.0 4.57 2.4 E 2.4 2,090 2.6 66.8 3.4 Minimum < 0.2 4.17 3.03 1.1 1.6 1,420 1.1 7.0 1.4 Maximum 78 1,100 5.20 3.1 2.6 6,840 5.4 189 12 Number of samples 5 5 5 5 5 5 5 5 5 DMCA, Confining unit between MA and UPA, shallow 2 and 3b 126 Within 84–104 Silt, peat, and clay Mean 66 454 5.42 --- 14.5 12,550 11 121 55 ± SD 74 23 0.30 --- 10.0 10,710 6.1 24.5 45 Median 37 441 5.52 N 10.5 E 17.2 18,400 14 121 71 Minimum 11.38 440 5.08 N < 0.3 3.4 187 3.5 96 4.4 Maximum 150 480 5.65 15.4 22.8 19,050 14.4 E 145 90 Number of samples 3 3 3 3 3 3 3 3 3 DMCA, UPA, shallow 1, 2, and 14 122, 126, and 134 Within 78–130 Sands Mean --- --- 4.49 7.3 11.3 9,670 8.2 77.8 43 ± SD --- --- 0.99 6.9 8.7 9,340 5.6 61.5 39 Median 26.5 436.2 4.77 1.5 4.7 1,580 1.9 30.5 6.4 Minimum < 0.2 23.0 4.24 0.3 3.0 3 3.0 3.0 3.0 Maximum 103 630 5.68 15.4 22.8 19,150 14.4 145 90 Number of samples 4 4 4 4 4 4 4 4 4

a Surficial sediments within approximately 34 feet of land surface were considered to reflect fill (dredged and deposited material) and possibly pre-existing shallow native sediments disturbed during the 

initial or later reconstruction under continued operation of the DMCA.

b Well has no corresponding USGS well identifier given it was never located during this study.
Hydrogeologic Framework 37

Table 10. Summary data on chemical composition of sediments in the vicinity of the Pearce Creek Dredge Material Containment Area from sediment-core samples obtained from selected boreholes, 1995–96 (modified from U.S. Army Corps of Engineers, 1996).[USACE, U.S. Army Corps of Engineers; USGS, U.S. Geological Survey; X or XXX, a numerical value associated with site identifier; ft, feet; bls, below land surface; mg/kg, milligram per kilogram; DMCA, Dredge Material Containment Area; PNR, Pond Neck Road; WVS, West View Shores; ERA, Area between DMCA and Elk River; UPA shallow, upper Patapsco aquifer; shallow water-bearing zone; MA, Magothy aquifer; <, undetected at concentration indicated; E, estimated; ---, not able to determine; mean provided when constituent had measureable values for all samples, and median could not be determined due to even number of samples]

Areal location 

and waterbearing zone 

or confining 

unit

USACE 

local 

identifier

(CSW X)

USGS 

local 

identifier

(CE Dd 

XXX)

Depth 

interval 

of sample

(ft bls)

Sample 

sediment 

type(s)

Statistical 

measure

Pore water Sediment

Sulfide

(mg/L)

Sulfate

(mg/L)

pH

(standard 

units)

Arsenic, 

extractable

(mg/kg)

Copper, 

extractable 

(mg/kg)

Iron, 

extractable

(mg/kg)

Lead, 

extractable

(mg/kg)

Manganese, 

extractable

(mg/kg)

Zinc, 

extractable

(mg/kg)

WVS and ERA, MA

7, 8, and 11

127, 128, and 131

Within 

0–50

Sands, silts, and silty sands

Mean 64.6 --- 5.51 2.3 5.4 5,010 6.5 45.4 10.8

±SD 47.1 --- 0.47 1.8 4.4 3,320 4.4 46.8 10.4

Median 45.8 --- 5.5 2.0 4.2 4,240 4.5 32.9 7.5

Minimum 20.1 --- 4.63 < 0.27 1.6 236 1.40 1.30 2.2

Maximum 149.8 < 172 6.20 7.0 17.8 12,000 16.7 186 40.0

Number of samples 14 14 14 14 14 14 14 14 14

WVS, Confining unit between MA and UPA shallow

7 127 Within 

24–60

Clays and silts

Mean 201 --- 5.72 2.0 14.1 18,620 12.2 148 62.7

±SD 66.9 --- 0.88 0.1 7.0 15,170 5.0 125 25.4

Median 233 --- 5.40 2.0 11.8 10,800 12.3 82.3 51.2

Minimum 124 --- 5.05 2.0 8.6 8,960 7.2 68.8 45.0

Maximum 246 < 89.8 6.71 2.1 22.0 36,100 17.1 292 91.8

Number of samples 3 3 3 3 3 3 3 3 3

WVS, UPA shallow

7 and 8 127 and 

128

Within 

70–102

Peats and silty sands

Mean 124 868.55 4.68 --- 6.4 12,280 5.7 21.6 18.4

±SD 79.3 1,412.49 0.32 --- 6.5 18,640 6.8 30.0 33.9

Median 144.3 198.4 4.6 --- 4.3 4,400 3.4 8.7 1.7

Minimum 10.8 91.7 4.45 < 0.25 1.5 326 0.78 2.7 0.87

Maximum 196 2,986 5.16 6.8 15.6 40,000 15.5 66.2 69.3

Number of samples 4 4 4 4 4 4 4 4 4

PNR, Mattawan surficial confining unit 

5 125 Within 

0–56

Peat, sands sandy silts, and silty sands and clays

Mean 19.1 --- 4.62 17.4 8.3 16,500 10.0 60.7 33.5

±SD 11.9 --- 0.85 20.5 3.6 9,690 5.4 47.7 18.5

Median 16.5 < 84.3 4.60 11.8 8.4 15,900 8.9 54.7 < 29.6

Minimum 7.60 --- 3.41 3.0 2.8 3,530 3.8 4.2 ---

Maximum 43.9 429 4.36 69.6 8.5 34,500 23.0 70.7 57.6

Number of samples 9 9 9 9 9 9 9 9 9

a Sediments cannot necessarily be considered native as they could have been exposed to groundwater from the DMCA by either groundwater flow or by the use of untreated groundwater by residents. 
38 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

questions. Are these sediments in fact located in a recharge 

rather than a discharge zone? What is the redox state of the 

zone? What is the origin and chemical nature of the water 

entering the zone, and is it likely changing as water passes 

through the zone? Answers to these questions can be found by 

integrating hydrogeologic framework, hydrology, and waterquality information, and are described in later sections of this 

report.

Hydrology

Patterns in horizontal and vertical directions of groundwater flow within the Magothy and upper Patapsco aquifers 

were determined from synoptic water-level measurements 

made in May and August 2010 and March 2011. Continuous water-level data recorded during the period January 2010 

through March 2011 from selected well nests provide information on daily and seasonal fluctuations and provide further 

information regarding vertical trends between aquifers. The 

derived patterns in groundwater flow associated with the May 

2010 synoptic assessment are used as the basis for the interpretations of groundwater quality in the DMCA and vicinity 

given that most water-quality samples were collected within 

this general time frame. The changes in water levels between 

the three synoptics as well as the continuous water-level data 

provide additional information on how groundwater flow 

within and between aquifers changes through time in response 

to water use, recharge, precipitation, and tidal effects.

Water-Level Synoptic Assessments and 

Continuous Data Collection

Three synoptic assessments of groundwater levels were 

conducted in the study area. The first synoptic assessment was 

conducted during May 19–20, 2010; water-level data were 

obtained from 58 wells and calculated for 3 wells for a 

total of 61 data points from within the DMCA and vicinity (fig. 16; table 11). The second synoptic assessment was 

conducted from August 17–18, 2010; water-level data were 

obtained from 62 wells and calculated for 3 wells for a total 

of 65 data points from within the DMCA and vicinity (fig. 16; 

table 11). The May and August 2010 synoptic assessments 

included a combination of existing and newly installed project 

observation wells, neighboring domestic wells in WVS and 

along Pond Neck Road and a local irrigation well. Following the installation of three additional wells for the project in 

December 2010 (wells CE Dd 191, 192, and 193), a third more 

limited synoptic assessment using observation wells only (39 

wells total) was conducted in March 2011 (table 11). The synoptic data were used to delineate the potentiometric surfaces 

of each aquifer in May and August 2010 and March 2011. 

The May and March synoptic assessments reflect a time in the 

spring when many of the seasonal residents of WVS generally 

are absent, and groundwater withdrawals for supplies are 

reduced leading to higher groundwater level altitudes. The 

August assessment reflects summer withdrawals and generally 

lower groundwater levels with most seasonal residents being 

present, and groundwater withdrawals for supplies presumably are greater than in the spring. Elevated evapotranspiration 

within the DMCA and vicinity also occurs during the summer. 

The USACE (Atlantic City, New Jersey) surveyed the 

altitudes of land surface and measuring points at all observation wells and the altitude of land surface for domestic wells 

used for this study. From these surveyed altitudes, the altitude 

of a measuring point was determined for each well by the 

USGS. 

For each water-level synoptic assessment, the depth to 

water in each well below the measuring point was measured 

by the USGS with a steel tape graduated to 0.01 ft. Water levels were adjusted to the altitude of the measuring point at each 

well to obtain the altitude of water level at each well. Accuracy of the altitude of groundwater levels is considered to be 

0.01 ft for the observation wells and 0.1 ft for domestic wells.

Continuous water-level data, collected from 15 study area 

observation wells (fig. 17; appendix A, table A1) with installed 

transducers, provided additional information on how groundwater flow within and between aquifers changes through time, 

including long- and short-term responses to recharge, tidal 

effects and other stresses such as drought, and groundwater 

withdrawals. Transducer water-level data were collected from 

some wells starting January 26, 2010, and the last transducers were removed March 31, 2011. The period of record for 

water-level measurements ranged from about 3 to 14 months 

depending upon when the transducer was installed in the well. 

The transducers used were rated at either 15 or 30 psi (pounds 

per square inch), with an accuracy of altitude of water level 

of ± 0.2 percent or less. The altitude of the water level was 

stored every 15 minutes on a data logger, and check measurements were made approximately every 30 days. Transducer 

water-level data were entered into the USGS National Water 

Information System (NWIS) database, where drift corrections based on check measurements, and (or) measuring point 

datum corrections were applied to the data when necessary. 

Pearce Creek Lake, which is dammed at the northeastern 

limit of the DMCA property (fig. 17), receives streamflow 

from Pearce Creek and is a potential groundwater recharge 

source and (or) discharge area. The lake level was monitored with a staff gage and continuous gage; the transducer 

in the continuous gage recorded the lake level at 15-minute 

intervals. The transducer level was referenced to a surveyed 

reference point on the gage. To better understand groundwater and surface-water interaction within Pearce Creek Lake, 

12 piezometers were driven into the lakebed during the May 

2010 groundwater synoptic assessment. Each piezometer was 

connected to a manometer, and the difference between the lake 

and piezometer level was recorded. The piezometer difference 

then was converted to the altitude of water level using the 

altitude of lake level determined from the staff gage reading.
Hydrology 39 Figure 16. Selected wells used by the U.S. Geological Survey for water-level data collection and the location of lines of section for groundwater flow A–A’ and B–B’ in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland. (Individual section lines are described further in relation to figs. 30 and 31.)

Elk River

Pearce Creek Lake

140

160

127

177

166

178

141

163

172 168

179 128

176

161

164

174

171

143

165

142 152

188

170

155

152

147

141 177

167 183 182

181

180

185

184

A

A’

B’

B

176

169

161

190

166

187

178

164 162

174

81

191

160

127

128

129

126

122 130 158

156

154

149

150

146

142

138

165

163

172 18672 168

179

135

125

192

193

133

157

153

151

145

143

159

140

139

137

148

136

124

144

189

75°59' 76°

39°26'

39°25'30"

123

157

168

122

169

155

170

Elk River

144189

A A'

Elk River Pearce Creek Lake

Crystal Beach

Pond Neck Road

West View Shores

Bay View Estates

EXPLANATION

Line of sectionLocally perched groundwater observation well 

and identifier

Locally perched groundwater domestic well and 

identifier

Magothy aquifer observation well and identifierMagothy aquifer domestic well and identifier

Upper Patapsco aquifer (shallow water-bearing 

zone) observation well and identifier

Upper Patapsco aquifer (shallow water-bearing 

zone) domestic well and identifier

Upper Patapsco aquifer (deep water-bearing 

zone) observation well and identifier

Upper Patapsco aquifer (deep water-bearing 

zone) domestic well and identifier

Surface-water site and identifier

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 
40 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

Water Use

Except for selected residences in the community of 

Crystal Beach, which is just north of Pearce Creek Lake 

(fig. 17), groundwater use in the study area is predominantly 

self-supplied by privately owned residential wells. Within 

Crystal Beach, a private water company, with a withdrawal 

permit from the Maryland Department of the Environment, 

pumps groundwater for public supplies. State-maintained 

records indicate the water company pumped an average 

of 0.295 Mgal/d (million gallons per day) in 2008 and 

0.315 Mgal/d in 2009 from two wells completed in the upper 

Patapsco deep water-bearing zone. There also are permitted 

irrigation withdrawals from a farm to the east of the DMCA 

(fig. 17). Multiple irrigation wells on this property pumped an 

average of 0.672 Mgal/d in 2009 and 1.074 Mgal/d in 2008 

from the Magothy aquifer. All other withdrawals in the area 

were from private non-permitted domestic wells. Maryland 

well completion reports were obtained for 107 wells in the 

area of WVS and Pond Neck Road. Of these, 23 wells were 

screened in the Magothy aquifer, 76 wells were screened in 

the upper Patapsco aquifer shallow water-bearing zone, and 

8 wells were screened in the upper Patapsco aquifer deep 

water-bearing zone. Based on well completion reports, most 

withdrawals for supplies outside the DMCA property are from 

the upper Patapsco aquifer shallow water-bearing zone.

Long-Term Water Levels

Although there is a paucity of data on historical water 

levels in the study area, periodic measurements at one well, 

CE Dd 81, in the vicinity of the DMCA, are available beginning in 1983. This well is completed in the upper Patapsco 

aquifer shallow water-bearing zone, and is located near the 

entrance of the DMCA (fig. 17). Historical measurements at 

this well from March 1983 through March 2011, converted to 

water-level altitudes, ranged from 8.48 ft NAVD 88 in July, 

1983 to 1.26 ft NAVD 88 in November 2002 (fig. 18). Waterlevel altitudes in this well also vary through time in response 

to changes in groundwater recharge. There does not appear 

to be a long-term decline in the altitude of water level in this 

well in response to groundwater withdrawals for the period of 

record.

Short-Term Water Levels

Average-daily water levels for the period of January 26, 

2010, to March 31, 2011, were calculated from the 15-minute 

transducer water-level data. Average daily levels were calculated as altitudes for Pearce Creek Lake and selected wells, 

with the latter being grouped by water-bearing zone and similar approximate locations (fig. 19). The altitude of the surface 

of the lake is regulated at the outlet, with a rapid rise in lake 

level presumably the result of direct precipitation and runoff 

generated by precipitation. Among the monitored wells, the 

transducer data indicate the highest water-level altitude during 

the period of measurement occurred at well CE Dd 123, and 

the lowest occurred at well CE Dd 136. Both these wells are 

completed in the Magothy aquifer and are located within the 

bermed area of the DMCA. 

Trends in water-level altitudes generally reflect seasonal 

patterns in evapotranspiration and water use (fig. 19). Waterlevel altitudes in the transducer wells generally increased 

during the winter to their highest recorded levels in early 

spring (January through May 2010). Both evapotranspiration 

and local water use (groundwater pumping) generally are low 

during this period. Water-level altitudes then around the end of 

May generally decreased through the summer to at least early 

fall in most wells, which generally corresponds to the time of 

reduced recharge, increased evapotranspiration, and increased 

local groundwater withdrawals. By early winter (January 

2011), water-level altitudes generally increased until the time 

all transducers were removed from the observation wells 

(March 2011). 

The altitudes of water levels collected at 15-minute 

intervals were examined in relation to Tropical Storm 

Nicole (fig. 20). This storm locally brought as much as 

5 to 7 inches (in.) of rain to the study area during September 

30–October 1, 2010. The water-level response to this tropical 

storm was greatest in Pearce Creek Lake; the transducer at 

the lake gage showed a 3-ft increase in the altitude of the lake 

surface during this storm. The altitude of water level increased 

at most wells during the storm (fig. 20). 

Increases in groundwater-level altitudes could reflect the 

net effects of (a) an increase in hydraulic head caused by the 

weight of the increased volume of river water on the underlying sediments from a storm surge on the Elk River, (b) a 

decrease in barometric pressure associated with the presence 

of the atmospheric low (depression) reflecting the remnants 

of Tropical Storm Nicole, and (c) an increase in the volume 

of water in the lake, coupled with ponding of water within the 

DMCA. Several wells that are relatively near the Elk River 

(e.g., CE Dd 81, 126, 127, 136, and 141) display semi-diurnal 

variations in water levels. The greatest tidal fluctuations average about 0.5 ft per tidal cycle and occur in the upper Patapsco 

shallow water-bearing zone in observation well CE Dd 127 at 

the base of WVS near the Elk River. Tidal fluctuations are also 

noted in water levels in wells in and near the western most 

part of the DMCA where fluctuations are generally 0.2 ft per 

tidal cycle or less. From September 30 into October 1, those 

wells show a heightened semi-diurnal response to greater 

than normal tides associated with storm surge in the upper 

Chesapeake Bay. Tidal fluctuations vary the load on confined 

aquifers near and beneath coastal water bodies. The relationship is direct, with water levels in wells increasing with tidal 

water levels. For barometric pressure fluctuations, the relationship is inverse; a decrease in barometric pressure would lead 

to an increase in water levels in wells in confined aquifers. 

Finally, an increase in the volume of water in the lake and 

infiltration of water ponded within the DMCA could provide 

a mechanism for recharging the groundwater. In relation to 
Hydrology 41

Table 11. Wells in the Pearce Creek Dredge Material Containment Area and vicinity in which water levels were measured during the 

May 2010, August 2010, and March 2011 synoptic assessments to delineate the potentiometric surface in three aquifers.

[ft, feet (referenced to North American Vertical Datum of 1988); UPA, upper Patapsco aquifer; shallow, shallow water-bearing zone; deep, deep water-bearing 

zone; ---, well not measured]

Station name Well use Aquifer

Altitude of water 

level,

May 19 or 20, 2010

(ft)

Altitude of water 

level,

August 17 or 18, 2010

(ft)

Altitude of water 

level,

March 18, 2011

(ft)

CE Dd 81 Observation UPA, shallow 6.76 5.11 4.73

CE Dd 116 Irrigation Magothy 8.89 1.45 ---

CE Dd 122 Observation UPA, shallow 7.14 5.54 5.49

CE Dd 124 Observation Perched 18.74 17.58 19.29

CE Dd 125 Observation Magothy 8.59 6.37 7.53

CE Dd 126 Observation UPA, shallow 3.94 3.37 3.37

CE Dd 127 Observation UPA, shallow 4.28 3.24 3.19

CE Dd 128 Observation UPA, shallow 5.38 4.21 3.94

CE Dd 129 Observation UPA, shallow 6.92 5.44 5.28

CE Dd 130 Observation UPA, shallow 6.92 5.45 5.3

CE Dd 133 Observation Magothy 9.96 7.41 9.58

CE Dd 135 Observation Magothy 9.62 8.26 8.9

CE Dd 136 Observation Magothy 1.19 1.28 1.63

CE Dd 137 Observation Magothy 9.48 7.54 8.55

CE Dd 138 Observation UPA, shallow 8.02 6.31 2.67

CE Dd 139 Observation Magothy 8.95 7.1 7.13

CE Dd 140 Observation Magothy 4.59 5.03 5.83

CE Dd 141 Observation UPA, deep 1.6 1.31 1.24

CE Dd 142 Observation UPA, shallow 5.23 4.12 3.81

CE Dd 143 Observation Magothy 4.84 3.69 3.4

CE Dd 144 Observation Perched 18.21 15.91 20.41

CE Dd 145 Observation Magothy 1.59 1.62 2.03

CE Dd 146 Observation UPA, shallow 2.7 2.13 2.42

CE Dd 147 Observation UPA, deep 3.57 2.77 2.95

CE Dd 148 Observation Magothy 9.02 6.98 7.76

CE Dd 149 Observation UPA, shallow 7.73 5.96 6.5

CE Dd 150 Observation UPA, shallow 5.41 4.14 4.31

CE Dd 151 Observation Magothy --- 6.51 6.21

CE Dd 152 Observation UPA, deep 4.69 3.69 3.46

CE Dd 153 Observation Magothy 9.71 7.17 8.45

CE Dd 154 Observation UPA, shallow 9.29 6.91 7.55

CE Dd 155 Observation UPA, deep 6.38 4.48 5.15

CE Dd 156 Observation UPA, shallow 6.39 5.08 4.89

CE Dd 157 Observation Magothy 10.46 8.33 9.76

CE Dd 158 Observation UPA, shallow 8.09 6.35 6.66

CE Dd 159 Observation Magothy 3.64 2.85 3.03

CE Dd 160 Observation UPA, shallow 4.64 3.22 3.06

CE Dd 161 Domestic UPA, shallow 6.99 5.56 ---

CE Dd 162 Domestic UPA, shallow 6.49 5.19 ---
42 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

the pre-storm water-level altitudes, post-storm water-level 

altitudes in several wells completed in the Magothy aquifer 

appear elevated and continued to rise thereafter (fig. 20).

Daily fluctuations in groundwater levels in the upper 

Patapsco aquifer shallow water-bearing zone are evident in 

well CE Dd 154 owing to nearby groundwater withdrawals. 

Well CE Dd 154 is part of a three-well nest where well 

CE Dd 153 is screened in the Magothy aquifer and CE Dd 155 

is screened in the upper Patapsco aquifer deep water-bearing 

zone. The isolation of the three units from one another in this 

area is noted by the lack of any appreciable effect of nearby 

pumping as recorded in adjacent well CE Dd 154, screened in 

the upper Patapsco aquifer shallow water-bearing zone.

Groundwater-Level Synoptic Assessments

Groundwater flow directions in the Magothy and upper 

Patapsco aquifer shallow and deep water-bearing zones 

are based on potentiometric surface maps delineated using 

groundwater-level data collected during synoptic water-level 

assessments in May and August 2010 and March 2011 

(table 11). May and August 2010 maps include estimated 

water levels for well 192 and well 193 screened in the 

Magothy aquifer and well 191 screened in the upper Patapsco aquifer shallow water-bearing zone. These wells were 

installed following the May and August synoptic assessments. 

The synoptic altitudes of water levels for wells 192 and 193 

Table 11. Wells in the Pearce Creek Dredge Material Containment Area and vicinity in which water levels were measured during the 

May 2010, August 2010, and March 2011 synoptic assessments to delineate the potentiometric surface in three aquifers.—Continued

[ft, feet (referenced to North American Vertical Datum of 1988); UPA, upper Patapsco aquifer; shallow, shallow water-bearing zone; deep, deep water-bearing 

zone; ---, well not measured]

Station name Well use Aquifer

Altitude of water 

level,

May 19 or 20, 2010

(ft)

Altitude of water 

level,

August 17 or 18, 2010

(ft)

Altitude of water 

level,

March 18, 2011

(ft)

CE Dd 163 Domestic Magothy 7.96 6.2 ---

CE Dd 164 Domestic UPA, shallow 7.41 5.75 ---

CE Dd 165 Domestic Magothy 8.13 6.34 ---

CE Dd 167 Domestic UPA, shallow 3.67 2.85 ---

CE Dd 168 Domestic Magothy 7.61 5.72 ---

CE Dd 169 Domestic UPA, shallow 6.19 4.78 ---

CE Dd 170 Domestic UPA, deep 6.79 5.01 ---

CE Dd 171 Domestic UPA, deep 4.17 3.37 ---

CE Dd 174 Domestic UPA, shallow --- 5.48 ---

CE Dd 176 Domestic UPA, shallow --- 6.11 ---

CE Dd 177 Domestic UPA, shallow 3.97 --- ---

CE Dd 178 Domestic UPA, shallow --- 3.65 --

CE Dd 179 Domestic Magothy 8.24 6.43 ---

CE Dd 180 Domestic UPA, shallow 3.18 2.19 ---

CE Dd 181 Domestic UPA, shallow 3.12 2.15 ---

CE Dd 182 Domestic UPA, shallow 3.83 2.63 ---

CE Dd 183 Domestic UPA, shallow 3.98 2.58 ---

CE Dd 184 Domestic UPA, shallow 3.55 2.03 ---

CE Dd 185 Domestic UPA, shallow 4.33 2.84 ---

CE Dd 186 Domestic Magothy 5.84 4.3 ---

CE Dd 187 Domestic UPA, shallow 6.26 4.86 ---

CE Dd 188 Domestic UPA, deep 3.26 2.88 ---

CE Dd 189 Domestic Perched --- 16.87 ---

CE Dd 190 Domestic UPA, shallow 2.21 1.99 ---

CE Dd 191 Observation UPA, shallow 6.11a 4.18a 5.21

CE Dd 192 Observation Magothy 10.23a 7.78a 9.21

CE Dd 193 Observation Magothy 9.85a 7.59a 8.92

a

 Value was calculated.
Hydrology 43

00

0.5 1.0 MILE

0.5 1.0 KILOMETER

West View Shores

Pond Neck Road

N

Elk River

Pearce Creek Lake

Crystal Beach

Bay View Estates

126

Lake Gage

136

192

191

193

153154155

122123

81 151 ,

152

127

141

Location of well or well nest

Well and identifier 

Color of well identifier denotes aquifer 

monitoredMagothy aquiferUpper Patapsco aquifer, shallow  water-bearing zoneUpper Patapsco aquifer, deep  water-bearing zone 

EXPLANATION

129

136126141

Property boundary of Pearce Creek Dredge Material Containment Area 

Figure 17. Observation wells and lake gage with installed water-level transducer, Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland.
44 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

were determined by estimating what the water levels would 

have been based on a simple linear regression of water levels 

in wells 192 and 193 with water-levels in well 153. (The 

coefficients of determination for the trend lines for wells 153 

and 192, and for wells 153 and 193, were 0.983 and 0.991, 

respectively.)

The comparable well for well 191 was well 154. 

Well 154, an upper Patapsco aquifer shallow water-bearing 

zone well, and well 153 are located on private property with 

a homeowner well that is also screened in the upper Patapsco 

aquifer shallow water-bearing zone. Withdrawals from the 

homeowner well cause declines in the altitude of water level 

in well 154—usually several times daily, with the altitude of 

water level recovering between withdrawal periods; this is 

clearly seen in fgure 20. Because of the daily fluctuations in 

water level in well 154, the maximum daily altitudes of water 

levels for wells 154 and 191 were used for the linear regression. (The coefficient of determination value for this trend line 

was 0.9812.) The maximum daily water-level altitude could 

differ from a synoptic level taken at a specific time during the 

day, but the difference is expected to be small; for example, 

the greatest daily difference recorded by the transducer in 

well 191 was 0.28 ft.

Magothy Aquifer: May 19–20, 2010, Synoptic 

Assessment

The altitude of groundwater levels was determined for 

the 16 observation wells, 5 domestic wells, and 1 irrigation 

well open to the Magothy aquifer from the groundwater-level 

measurements taken during May 19–20, 2010. The altitude 

of water levels in all Magothy aquifer wells and lake-bed 

piezometers measured during the May 19–20 synoptic assessment were used to develop the potentiometric-surface contours 

for the Magothy aquifer (fig. 21). Groundwater flow within the 

aquifer is interpreted as being perpendicular to the contours 

with flow in the direction of high groundwater altitude to low 

groundwater altitude. Areas of highest groundwater altitude 

generally occur in the southeastern part of the DMCA property. Groundwater flow is generally outward from this area, 

northward to Pearce Creek Lake, south toward Pond Neck 

Road, and northwest and westward toward WVS and the 

Elk River. A groundwater flow divide running in an easterly 

direction through the DMCA separates northerly and southerly 

flow components. The horizontal gradients are low to the east 

of the DMCA property, indicating little flow from the DMCA 

property toward the east, or from the east towards the DMCA 

property.

198319841985198619871988198919901991199219931994199519961997199819992000200120022003200420052006200720082009201020112012

0

1

2

3

Year

4

5

6

7

8

9

10

Altitude of water level, in feet relative to North American Vertical Datum of 1988

No data

collected

No data

collected

Figure 18. Altitude of water levels in well CE Dd 81 near Pearce Creek Dredge Material Containment Area 

(DMCA), Cecil County, Maryland, March 1983–June 2011.
Hydrology 45 Figure 19.

Average daily altitude of water levels in observation wells in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, 

Maryland, January 2010–March 2011.

Period of intense rainfall from remnants of Tropical Storm Nicole 

Well identififier

VERTICAL EXAGGERATION x 20

98765

43

210

10

01/22/2010 03/13/2010 05/02/2010 06/21/2010 08/10/2010 09/29/2010 11/18/2010 01/07/2011 02/26/2011

Average daily altitude of water level, in feet above North American Vertical Datum of 1988

Date, month/day/year

August synoptic

May synoptic

141

192193

153

154

Lakelevel

151

122

191

81

152

127

126

155

136

123

EXPLANATION

Like colored lines are wells in the same nestDashed lines are Magothy aquifer wellsThick lines are upper Patapsco aquifer 

shallow water-bearing zone wells

Thin lines are upper Patapsco aquifer deep 

water-bearing zone wells
46 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area 9/26/2010 9/27/2010 9/28/2010 9/29/2010 9/30/2010 10/01/2010 10/02/2010 10/03/2010 10/04/2010 10/05/2010 10/06/2010 Period of intense rainfall from remnants of Tropical Storm Nicole Lake level Chesapeake City, Maryland tide gage 122 81127 136 123 Well identififier 153 154 151 152 155 126 141 1

0

-1

-2

98765

43

2

10

Altitude of water level, in feet above North American Vertical Datum of 1988

Date, month/day/year

EXPLANATION

Like colored lines are wells in the same nestDashed lines are Magothy aquifer wellsThick lines are upper Patapsco aquifer 

shallow water-bearing zone wells

Thin lines are upper Patapsco aquifer deep 

water-bearing zone wells

Figure 20. Altitude of water levels in observation wells and Pearce Creek Lake from September 26–October 6, 2010, in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland.
Hydrology 47

The potentiometric-surface contours in the area of Pearce 

Creek Lake during the May 2010 synoptic assessment were 

in part derived on the basis of the altitude of water levels 

obtained from the lake-bed piezometers (fig. 21). Except for 

areas of isolated clay or cemented sediments, most piezometer 

installations indicated that the lake-bed muck is hydraulically 

connected to underlying sands, implying that the Magothy 

aquifer subcrops beneath Pearce Creek Lake. Just to the east 

of the 6-ft potentiometric-surface contour, the altitude of the 

water level in the lake bed was the same as the lake level 

(fig. 21, P-11). When this piezometer was driven into the 

lake bed, solid clay was encountered immediately below 

the lake-bed deposits, and the piezometer was set into the 

lake-bed deposits. Thus, the altitude of the water level in this 

piezometer is that of the lake and not of the groundwater. Clay 

and iron-cemented sediments were encountered in the area 

between P-8 and P-9 (fig. 21); no water-level measurement 

could be made from a piezometer that was to be installed in 

this location. Cemented sediments also were encountered during initial attempts to install a third piezometer (fig. 21, P-4); 

however, this piezometer was eventually set in sand below the 

lake bottom.

 During the May 2010 synoptic assessment, the altitude 

of the lake was calculated at 6.79 ft on the basis of the lake 

staff gage reading on May 19, 2010. The continuous-gage 

lake-level data associated with this staff gage indicate that the 

lake level varied between 6.78 and 6.81 ft during the 2-day 

synoptic assessment; thus variations between –0.01 and 

0.02 ft in the lake-bed piezometer measurements could be due 

to variations in the lake level. However, the lake-bed piezometers at the downstream end of the lake had an altitude of 

groundwater level in the Magothy aquifer that was 1.3 ft less 

than the altitude of the lake (fig. 21, P-1 and P-7). This difference in water-level altitudes indicates that in the down-lake 

area in the vicinity of these two piezometers there is flow from 

the lake downward to the Magothy aquifer. Up-lake from these 

two piezometers, the vertical flow measurements indicate that 

during this synoptic assessment groundwater from the Magothy aquifer is discharging to the lake (fig. 21).

Magothy Aquifer: August 17–18, 2010, Synoptic 

Assessment

The altitude of groundwater levels was determined for 

the 16 observation wells, 5 domestic wells, and 1 irrigation 

well open to the Magothy aquifer from the groundwater-level 

measurements taken during August 17–18, 2010. The lake-bed 

piezometer at the downstream end of Pearce Creek Lake was 

reinstalled and an altitude of water level also was obtained at 

this piezometer. In general, the altitude of water levels in the 

remeasured wells and piezometer were lower than the altitude 

of water levels during the May 2012 synoptic assessment. 

Continuous altitude of water-level measurements confirm that 

between May and August 2010 there was a generally decreasing trend in the altitudes of water levels for the transducer 

wells open to the Magothy aquifer (fig. 19). The two exceptions were well 140 and well 145, which both are located near 

Elk River (fig. 17). Tidal influences could have caused the 

higher August level in well 145, but the consistently erratic 

levels in well 140 are indicative of a problem in well construction. The mean difference of the altitude of water level 

between the May and August levels, for all Magothy aquifer 

wells, was 1.82 ft. This includes one relatively large difference 

of 7.44 ft for well 116, an active irrigation well to the east of 

the DMCA property; this difference is likely the result of local 

withdrawals from this and nearby irrigation wells.

The potentiometric-surface contours derived from the 

altitudes of water levels in the August 2010 synoptic assessment (fig. 22) generally resemble contours derived from the 

May 2010 synoptic assessment. Thus the pattern in groundwater flow within the Magothy aquifer during the late summer 

and spring synoptic assessments is similar despite the general 

decline in the altitude of water levels.

Magothy Aquifer: March 18, 2011, Synoptic 

Assessment

The altitude of groundwater levels was determined for 

the 16 observation wells open to the Magothy aquifer from the 

groundwater-level measurements taken on March 18, 2011. 

These late winter-early spring water levels are overall higher 

than those of August 2010 but generally not as high as those 

taken during May 2010 (table 11). 

The potentiometric surface of the Magothy aquifer on 

March 18, 2010, is shown in figure 23. The pattern of horizontal flow in the Magothy aquifer within the study area is 

relatively consistent with previous synoptic results. Areas of 

highest groundwater altitude generally occur in the southeastern part of the DMCA. Groundwater flow is generally outward 

from this area, northward to Pearce Creek Lake, south toward 

Pond Neck Road and northwest and westward toward WVS 

and the Elk River. Horizontal gradients are low to the east of 

the DMCA property, indicating little flow from the DMCA 

property toward the east, or from the east toward the DMCA 

property. 

Upper Patapsco Aquifer Shallow Water-Bearing 

Zone: May 19–20, 2010, Synoptic Assessment

The altitudes of groundwater levels were determined for 

17 observation wells and 14 domestic wells open to the upper 

Patapsco aquifer shallow water-bearing zone from the groundwater-level measurements taken during the May 19–20, 2010, 

synoptic assessment. The altitudes of water levels in these 

wells from the May 19–20 synoptic assessment were used to 

derive the potentiometric-surface contours for this zone 

(fig. 24). The pattern of horizontal groundwater flow within 

this water-bearing zone during the May 2010 synoptic assessment was similar to the pattern of groundwater flow observed 

in the Magothy aquifer during this period. The potentiometric 
48 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area 75°57' 75°58' 75°59' 39°26'30" 39°26' 39°25'30" 39°25' 0 500 1,000 1,500 2,000 FEET 0 200 400 METERS Base map from Cecil County, Maryland government Maryland State Plane coordinate system North American Datum of 1983 Pearce Creek Lake

Elk River

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

Crystal Beach

West View Shores

Pond Neck Road

4

2

6

6

8

8

10

10

4.61 3.64

4.84 7.96

8.37

8.25

8.25

8.96 10.46

9.48

9.02

8.59

8.59

9.72

9.85

8.89 9.96

10.23

9.62

1.19

1.59

8.13

4.61 3.64

4.84

5.84

7.61

8.13

P-75.49

P-15.49

P-116.79

P-86.77 P-9 6.8

Altitude of lake was6.79 feet, 5/18/2010 P-3

6.83

P-36.83

P-66.81

P-56.81

P-46.99

P-126.89 P-2 7.55

EXPLANATION

Potentiometric surface contour in the Magothy aquifer—Shows altitude at 

which water would have stood in tightly cased wells, May 19–20, 2010. Dashed where approximately located. Contour interval 2 feet. Datum is North American Vertical Datum of 1988

Direction of groundwater flow

Lake bed piezometer—Top number is identifier. Bottom number is altitude of 

water level, in feet. Datum is North American Vertical Datum of 1988

Magothy aquifer observation well—Number is altitude of water level, in feet. 

Datum is North American Vertical Datum of 1988

Magothy aquifer domestic or irrigation well—Number is altitude of water 

level, in feet. Datum is North American Vertical Datum of 1988

6

Figure 21. Potentiometric surface of the Magothy aquifer, May 19–20, 2010, in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland.
Hydrology 49

surface of the upper Patapsco aquifer shallow water-bearing 

zone has its highest altitudes in approximately the same location as the Magothy aquifer, but May 2010 upper Patapsco 

aquifer shallow heads are approximately 1 to 2 ft lower than 

the highest altitudes of the Magothy potentiometric surface 

during the same time period. Similar to groundwater flow 

within the Magothy aquifer, groundwater flow within the 

upper Patapsco shallow water-bearing zone within the DMCA 

is interpreted to be northward and westward toward the Elk 

River and WVS. However, the horizontal gradients are low 

in the southeastern corner of the DMCA property and south 

along Pond Neck Road indicating little horizontal flow in this 

southern part of the study area.

Upper Patapsco Aquifer Shallow Water-Bearing 

Zone: August 17–18, 2010, Synoptic Assessment

The altitudes of groundwater levels were determined for 

17 observation wells and 16 domestic wells open to the upper 

Patapsco aquifer shallow water-bearing zone from the groundwater-level measurements taken during the August 17–18, 

2010, synoptic assessment. The altitudes of water levels in 

all wells completed in upper Patapsco aquifer shallow waterbearing zone from the August 17–18, 2010, synoptic assessment were used to derive potentiometric-surface contours for 

this time period (fig. 25). Synoptic results indicate the altitudes 

of water levels were lower during the August synoptic assessment compared to the May synoptic assessment (figs. 24 and 

25). The decline in water-level altitudes between May and 

August 2010 is confirmed by the generally decreasing trend 

in continuous water-level altitudes for the wells open to the 

upper Patapsco aquifer shallow-water-bearing zone (fig. 19). 

The mean difference in altitude of water levels for this waterbearing zone between the May and August synoptic assessments was 1.34 ft. 

The pattern of groundwater flow within the upper Patapsco aquifer shallow water-bearing zone, interpreted from 

the August synoptic levels, is similar to the pattern of flow 

observed on the basis of the May synoptic levels (figs. 24 and 

25). 

Upper Patapsco Aquifer Shallow Water-Bearing 

Zone: March 18, 2011, Synoptic Assessment

The altitudes of groundwater levels determined for 

17 observation wells open to the upper Patapsco aquifer shallow water-bearing zone from the groundwater-level measurements taken during March 18, 2011, are contoured on the 

potentiometric map in fgure 26. Groundwater flow directions 

during this period are essentially the same as described for the 

previous two synoptic measurements for this aquifer. 

Upper Patapsco Aquifer Deep Water-Bearing 

Zone: May 19–20, 2010, Synoptic Assessment

The altitudes of groundwater levels were determined 

for four observation wells and three domestic wells open to 

the upper Patapsco aquifer deep water-bearing zone from the 

groundwater-level measurements taken during May 19–20, 

2010. Although the paucity of data limits the accuracy of 

interpretation, potentiometric-surface contours for this waterbearing zone were derived from the water-level altitudes 

obtained from these 7 wells (fig. 27). The resultant contours 

indicate that groundwater in this zone generally follows the 

axis of the Pond Neck peninsula, and travels northwestward to 

the Elk River. 

Upper Patapsco Aquifer Deep Water-Bearing 

Zone: August 17–18, 2010, Synoptic Assessment

All wells used for water-level measurements during the 

May 2010 synoptic assessment were reused during the August 

2010 synoptic assessment. The altitudes of water levels in 

these wells were used to determine the potentiometric-surface 

contours for the upper Patapsco aquifer deep water-bearing 

zone (fig. 28). Similar to the synoptic results for the Magothy 

and upper Patapsco aquifer shallow water-bearing zone, the 

water-level altitudes in the upper Patapsco aquifer deep waterbearing zone were lower during the August synoptic assessment compared to their altitudes the May synoptic assessment. 

The mean decline in the altitudes of water levels between the 

two synoptic assessments was 1.07 ft. The general direction of 

groundwater flow in August remained northwestward toward 

the Elk River.

Perched Groundwater Zone: August 17–18, 2010, 

Synoptic Assessment

The altitude of groundwater determined for three shallow 

wells (22 to 27 ft below land surface) located along the western property boundary of the DMCA and extending into WVS 

indicates a local zone of perched groundwater (fig. 29). These 

include wells 144 and 189, which are considered screened in 

part of the Magothy aquifer, and well 124, which is screened 

at the base of the dredge material (R.F. Weston, Inc., 1998). 

Water levels in these wells are approximately 10 ft higher than 

surrounding wells screened deeper in the Magothy aquifer. 

R.F. Weston, Inc., (1998) also noted the perched water zone 

in well 124 based on water-level measurements taken in 1996 

and 1997. The altitudes of water levels and associated potentiometric contours in fgure 29 are approximate and generalized, given only three water-level altitudes form the basis of 

interpretation. The small unnamed stream along the western 

property boundary of the DMCA (fig. 29) is at approximately 

the same elevation as the potentiometric contours, and it is 

likely that the perched groundwater may be associated with, 

and discharges to, this unnamed stream. Water-quality data for 
50 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area 75°57' 75°58' 75°59' 39°26'30" 39°26' 39°25'30" 39°25' 0 500 1,000 1,500 2,000 FEET 0 200 400 METERS Base map from Cecil County, Maryland government Maryland State Plane coordinate system North American Datum of 1983 Pearce Creek Lake

Elk River

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

Crystal Beach

West View Shores

Pond Neck Road

2

6

6

4

8

8 2.85

3.69

5.03

4.3 5.7

6.3

6.2

2.85

3.69

5.03

4.3 5.7

6.3

6.2

6.4

7.1

7.54

8.33

1.18

1.62

4.58

8.26

7.41 1.4

7.59

7.03

6.37

7.78

6.98

6.39

4.58

EXPLANATION

Potentiometric surface contour in the Magothy aquifer—Shows altitude 

at which water would have stood in tightly cased wells, August 17–19, 2010. Dashed where approximately located. Contour interval 2 feet. Datum is North American Vertical Datum of 1988

Direction of groundwater flow

Lake bed piezometer—Number is altitude of water level, in feet. Datum is 

North American Vertical Datum of 1988

Magothy aquifer observation well—Number is altitude of water level, in feet. 

Datum is North American Vertical Datum of 1988

Magothy aquifer domestic or irrigation well—Number is altitude of water 

level, in feet. Datum is North American Vertical Datum of 1988

6

6.4

6.37

Altitude of lake was6.88 feet, 8/18/2010

Figure 22. Potentiometric surface of the Magothy aquifer, August 17–18, 2010, in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland.
Hydrology 51 Figure 23. Potentiometric surface of the Magothy aquifer, March 18, 2011, in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland.

75°57' 75°58' 75°59'

39°26'30"

39°26'

39°25'30"

39°25'

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

Pearce CreekLake

Elk River

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

Crystal Beach

West View Shores

Pond Neck Road

4

6

2

8

8

5.83

3.03

3.40

6.18

7.13 9.78

9.589.21

8.92

8.44

7.53

8.55

7.76

8.90

1.63

2.03

Altitude of lake was7.18 feet, 3/18/2011

EXPLANATION

Potentiometric surface contour in the Magothy aquifer—Shows altitude 

at which water would have stood in tightly cased wells, March 18, 2011. Dashed where approximately located. Contour interval 2 feet. Datum is North American Vertical Datum of 1988

Direction of groundwater flow

Magothy aquifer observation well—Number is altitude of water level, in feet. 

Datum is North American Vertical Datum of 1988

6 7.76
52 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area 75°57' 75°58' 75°59' 39°26'30" 39°26' 39°25'30" 39°25' 0 500 1,000 1,500 2,000 FEET 0 200 400 METERS Base map from Cecil County, Maryland government Maryland State Plane coordinate system North American Datum of 1983 Pearce Creek Lake

Elk River

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

Crystal Beach

West View Shores

Pond Neck Road

2

4

6

6

8

4

8

3.55

3.18

3.12

4.33

4.28

3.97

3.98 3.67

5.23

4.64

538

6.26

3.18

3.12

3.97

3.98 3.67

3.83

5.23

4.64

5.38

6.26

6.2

2.21

6.99

6.53

2.71

3.94

8.1

7.73

9.29

6.11

5.41

8.02

6.93

6.7

6.93

7.14

7.41

6.49

EXPLANATION

Potentiometric surface contour in the upper Patapsco aquifer, shallow 

water-bearing zone—Shows altitude at which water would have stood in tightly cased wells, May 19–20, 2010. Dashed where approximately located. Contour interval 2 feet. Datum is North American Vertical Datum of 1988

Direction of groundwater flow

Upper Patapsco shallow aquifer observation well—Number is altitude of water 

level, in feet. Datum is North American Vertical Datum of 1988

Upper Patapsco shallow aquifer domestic or irrigation well—Number is altitude 

of water level, in feet. Datum is North American Vertical Datum of 1988

6 9.29

6.49

Figure 24. Potentiometric surface of the upper Patapsco aquifer shallow water-bearing zone, May 19–20, 2010, in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland.
Hydrology 53

75°57' 75°58' 75°59'

39°26'30"

39°26'

39°25'30"

39°25'

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

Pearce CreekLake

Elk River

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

Crystal Beach

West View Shores

Pond Neck Road

2

4

6

2.03

2.84 3.24

2.85 2.58

2.63 3.22

2.15

2.19

2.03

2.84

2.85 2.58

2.63 3.223.65

4.86 4.12

5.75

4.21

4.86 5.75

5.7519

5.05

5.46 5.54 6.33

6.83

4.18

4.14

6.31 

5.96

5.44

5.22

1.99

5.56 4.79

5.48 6.12

3.23

2.13

2.15

2.19

EXPLANATION

Potentiometric surface contour in the upper Patapsco aquifer, shallow 

water-bearing zone—Shows altitude at which water would have stood in tightly cased wells, August 17–18, 2010. Dashed where approximately located. Contour interval 2 feet. Datum is North American Vertical Datum of 1988

Direction of groundwater flow

Upper Patapsco shallow aquifer observation well—Number is altitude of 

water level, in feet. Datum is North American Vertical Datum of 1988

Upper Patapsco shallow aquifer domestic or irrigation well—Number is 

altitude of water level, in feet. Datum is North American Vertical Datum of 1988

6 6.83

5.19

Figure 25. Potentiometric surface of the upper Patapsco aquifer shallow water-bearing zone, August 17–18, 2010, in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland.
54 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area 75°57' 75°58' 75°59' 39°26'30" 39°26' 39°25'30" 39°25' 0 500 1,000 1,500 2,000 FEET 0 200 400 METERS Base map from Cecil County, Maryland government Maryland State Plane coordinate system North American Datum of 1983 Pearce Creek Lake

Elk River

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

Crystal Beach

West View Shores

Pond Neck Road

4

6

3.19

4.73

5.3081

5.49

6.67

6.64

5.28

4.89

2.42

3.37

4.31

5.21

7.81

6.50

3.06

3.81

3.934

EXPLANATION

Potentiometric contour in the upper Patapsco aquifer, shallow waterbearing zone—Shows altitude at which water would have stood in tightly 

cased wells, March 18, 2011. Dashed where approximately located. Contour interval 2 feet. Datum is North American Vertical Datum of 1988

Direction of groundwater flow

Upper Patapsco shallow aquifer observation well—Number is altitude 

of water level, in feet. Datum is North American Vertical Datum of 1988

6 7.81

Figure 26. Potentiometric surface of the upper Patapsco aquifer shallow water-bearing zone, March 18, 2011, in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland.
Hydrology 55

75°57' 75°58' 75°59'

39°26'30"

39°26'

39°25'30"

39°25'

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

Pearce CreekLake

Elk River

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

Crystal Beach

West View Shores

Pond Neck Road

2

4

6

3.26

1.61

4.17

3.59

6.8

6.8

6.36

4.17

4.7

EXPLANATION

Potentiometric surface contour in the upper Patapsco aquifer, deep waterbearing zone— Shows altitude at which water would have stood in tightly 

cased wells, May 19–20, 2010. Dashed where approximately located. Contour interval 2 feet. Datum is North American Vertical Datum of 1988

Direction of groundwater flow

Upper Patapsco deep aquifer observation well—Number is altitude of 

water level, in feet. Datum is North American Vertical Datum of 1988

Upper Patapsco deep aquifer domestic or irrigation well—Number is 

altitude of water level, in feet. Datum is North American Vertical Datum 

of 1988

6 6.36

Figure 27. Potentiometric surface of the upper Patapsco aquifer deep water-bearing zone, May 19–20, 2010, in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland.
56 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

75°57' 75°58' 75°59'

39°26'30"

39°26'

39°25'30"

39°25'

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

Pearce CreekLake

Elk River

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

Crystal Beach

West View Shores

Pond Neck Road

2

4

2.88

1.16

3.37

3.49

5.02 4.3

2.78

EXPLANATION

Potentiometric surface contour in the upper Patapsco aquifer, deep waterbearing zone— Shows altitude at which water would have stood in tightly 

cased wells, August 17–18, 2010. Dashed where approximately located. Contour interval 2 feet. Datum is North American Vertical Datum of 1988

Direction of groundwater flow

Upper Patapsco deep aquifer observation well—Number is altitude of 

water level, in feet. Datum is North American Vertical Datum of 1988

Upper Patapsco deep aquifer domestic or irrigation well—Number is 

altitude of water level, in feet. Datum is North American Vertical Datum 

of 1988

6 4.3

5.02

Figure 28. Potentiometric surface of the upper Patapsco aquifer deep water-bearing zone, August 17–18, 2010, in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland.
Hydrology 57

these shallow water table wells are included on maps of the 

Magothy aquifer.

Cross-Sectional Flow

In addition to potentiometric surfaces presented in map 

view, two-dimensional representations of groundwater flow 

along selected cross sections provide a perspective of vertical 

as well as horizontal groundwater flow within and between 

the three major water-bearing zones within the study area 

(fig. 30, section A–A′ and fig. 31, section B–B′). Section A–A′

(fig. 30) extends eastward from Elk River through WVS and 

the DMCA. Section B–B′ (fig. 31) runs perpendicular to A–A′

and in a north-south direction from Elk River to just beyond 

the southern property boundary of the DMCA. These sections have been generalized to show a vertical profile of well 

locations, screen intervals, contoured water-level data and 

flow directions in relation to the hydrogeologic framework. 

The sections extend vertically from land surface down to or 

through the upper Patapsco aquifer deep water-bearing zone. 

The potentiometric-surface contours from the May 19–20, 

2010, synoptic assessment were projected onto each section 

and contours of equal value were connected across the confining units between the three water-bearing units.

Section A–A′ (fig. 30) illustrates the direction of lateral 

and vertical components of flow as driven by the water-level 

altitudes among the hydrologic units. Downward flow at land 

surface implies recharge, which in the DMCA occurs mainly 

in response to precipitation since the DMCA’s closure in the 

mid-1990s. Downward flow outside of the DMCA occurs in 

response to recharge from the lake, irrigation, and (or) septic 

effluent, as well as precipitation, depending on the local land 

use and human activities near the DMCA property.

Flow between aquifers is vertically downward over most 

of the area, and flow is generally impeded locally by the presence of confining units or zones of lower permeable material. 

However, groundwater flow along the line of section A–A′

from the western part of the DMCA toward Elk River is relatively unimpeded and markedly downward where the Magothy 

aquifer is unconfined and hydraulically connected to the upper 

Patapsco aquifer shallow water-bearing zone. Ultimately, 

groundwater flow is vertically upward at the western end of 

section A–A′ and discharges to the Elk River. Horizontal gradients are much lower in the eastern part of the DMCA property, 

indicating little flow from the DMCA property toward the east 

along section A–A′.

Section B–B′ (fig. 31) illustrates lateral flow of groundwater extending outward from the groundwater vertical 

divide, which is located approximately between well 138 and 

well 158. Along this line of section, and except in the vicinity of well 126 and well 147, vertical flow is predominantly 

downward through the hydrogeologic units. In the vicinity 

of well 126 and well 147, groundwater flow is upward as 

flow discharges to the Elk River. The cross-sectional patterns in groundwater flow described here form the basis for 

the discussion of water-quality conditions, and these patterns 

have direct bearing on the transport and quality of groundwater beneath the DMCA and vicinity as well as the quality 

of groundwater used for domestic water supplies (see Water 

Quality, this report).

Historical Perspective

There are no available groundwater-level data and, 

therefore, no interpreted directions of groundwater flow before 

or during the period of active disposal of dredge material at 

the DMCA. There are very few data for the period since the 

active disposal ceased at the DMCA until the 2010–11 study. 

This is a historical limitation in hydrologic data for this study. 

However, in general terms, and on the basis of topographic 

maps before, during, and after the DMCA was built, and 

hydrogeologic data collected during the 2010–11 study, the 

site was likely a low-elevation tidal wetland, which reflected 

regional groundwater discharge from the Magothy aquifer 

before the DMCA was constructed in the late 1930s. As is 

common in other coastal estuaries along the Chesapeake Bay, 

and on the basis of early (pre-1930s) topography of the study 

area, groundwater mainly would have discharged into the 

wetland. From this wetland, it (the former groundwater discharge) either flowed directly into the Elk River, or into Pearce 

Creek, and subsequently flowed into the Elk River. During 

the 1930s to 1990s, the construction of a land bridge limited 

the discharge of Pearce Creek into the Elk River and led to 

the creation of Pearce Creek Lake. This lake likely resulted in 

elevated water levels in local groundwater, particularly during 

the late fall through winter months. In addition, the initial 

construction and raising of berms used to create the DMCA, 

combined with an eventual rise in the land surface elevation 

within the DMCA of 20 to 30 ft as a result the deposition of 

dredged sediments, combined with the large volumes of Elk 

River water that were used to transfer these sediments into 

the DMCA, likely contributed to a rise in water levels in 

local groundwater. Ultimately, the combined effects of all the 

above transitioned the site into an elevated local groundwater 

recharge area, which affected local groundwater flow patterns. Although much of the Elk River water pumped into the 

DMCA during sediment disposal was drained through a sluice 

and into Pearce Creek Lake after allowing sediments to settle 

over a several day period, net recharge within the DMCA as 

a result of sediment disposal exceeded that generally associated with the preexisting wetland under normal precipitation 

conditions.

Although there are no historical data that show the effects 

of depositing large volumes of recharge into the DMCA on 

groundwater levels during its use, the effects on groundwater levels could be similar to that observed from continuous 

water-level data in September and October 2010 from Tropical Storm Nicole, which deposited 5 to 7 in. of precipitation 

within a 48-hour period at the site.
58 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

Finally, despite no DMCA use during the past 20–

25 years, the maximum local water levels associated with 

the Magothy aquifer are centered over part of the DMCA. 

The water-level pattern is not entirely what would be expected 

solely from regional groundwater recharge and flow; the pattern indicates that recharge from precipitation is relatively 

high in the vicinity of the containment area. 

Water Quality

The chemistry of regional and local surficial groundwater, both natural (or background) and that affected by human 

activities, of the Delmarva Peninsula has been described by 

Shedlock and others (1999). Natural surficial groundwater is 

moderately acidic, and low in total dissolved solids, specific 

conductance, alkalinity, nitrate as nitrogen, chloride, major 

cations (calcium, magnesium, sodium, and potassium), and, 

except in poorly draining sandy sediments with silt and 

organic matter, most trace elements (table 12). Under residential land use, groundwater in the surficial aquifer generally 

is slightly more acidic and moderately elevated in relation to 

most of the above properties or constituents. In the northern 

and inner coastal section of the Delmarva Peninsula, which 

includes the general area near the DMCA, Shedlock and others 

(1999) note that sediments typically are fine grained and low 

in permeability. However, their study did not specifically characterize water quality along coastal areas in the northernmost 

part of the Delmarva Peninsula, probably because of a paucity 

of historical data.

Historical data to describe the quality of local groundwater without the effects from human development in the vicinity 

0

0

0.25 0.5 MILE

0.25 0.5 KILOMETER

West View Shores

Pond Neck Road

N

Elk River

Pearce 

Creek 

Lake

Local stream

Crystal Beach

Bay View 

Estates

,

Observation well in the perched 

groundwater zone—Number is altitude 

of water level, in feet. Datum is North 

American Veritcal Datum of 1988

Water-level contour—Shows altitude of 

water level in the perched groundwater 

zone (August 2010), in feet. Contour 

interval 2 feet. Datum is North 

American Veritcal Datum of 1988 

EXPLANATION

17.58

16.87

15.91

18

16

18

16

16.87

15.91

15.91

16

Property boundary of 

Pearce Creek Dredge 

Material Containment 

Area 

Figure 29. Potentiometric surface of a perched groundwater zone, August 17–18, 2010, in the Pearce Creek 

Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland.
Water Quality 59 Figure 30. Hydrogeologic section showing groundwater altitudes and flow directions along line A–A’, May 2010, in the Pearce Creek Dredge Material Containment Area and vicinity, Cecil County, Maryland. (Location of line of section A–A’ is shown in figure 16.)

Magothy aquifer

Fill - Matawan Formation

Upper Patapsco aquifershallow water-bearing zone

Upper Patapsco aquiferdeep water-bearing zone

2

4

6

6

6

8

8

10

10

9.85 10.23

6.11

10.46

8.1

7.14

8.96

4.7

4.17

6.7

8.37

7.4

8.13

7.61

5.38

5.23

4.64 6.93

4.84 3.64

Groundwater divide

Well

identifier

7.96

18.74

5025

-25-50-75

-100-125-150-175-200-225-250

0

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000

Distance, in feet

4,500 5,000 5,500 6,000 6,500 7,000 8,000 8,500 9,000 7,500

A

WEST

A'

EAST

193

192 191

157 158 124 139122 130

151

152

81

163

168

165

164 171 142

143

128 160 159

Confining Unit

Confining unit

Elk

River

Confining unit

Altitude, in feet above or below North American Vertical Datum of 1988

VERTICAL EXAGGERATION x 20

Water-level altitude, in feet, May 2010Water-level contour, interval 2 feet— Dashed where approximately locatedDirection of groundwater flowPrecipitation/recharge

EXPLANATION

6.11

6
60 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

of the DMCA are limited: however, there are some groundwater-quality conditions from nearby sites (outside of the 

DMCA) that are available from various other studies (1983–

2003) (table 13, fig. 32). Whereas the data are insufficient to 

warrant a definitive discussion of “natural or background” 

water-quality conditions for the study area, they are used for 

comparative purposes in subsequent discussions in this report 

as the best representation available of those conditions. 

The quality of groundwater beneath the study area differed spatially within the Magothy aquifer, and within the 

upper Patapsco aquifer deep and shallow water-bearing zones. 

In part, the differences in the general chemical composition of 

groundwater can be linked to the previously described patterns 

in groundwater flow. In part, the differences also reflect differences in geochemical conditions associated with groundwater—including redox conditions and acidity—that also appear 

to relate to the DMCA and its influence on groundwater quality beneath and in the vicinity of the DMCA. 

General Water-Quality Characteristics

The general quality of groundwater in the study area can 

be described in relation to the occurrence, distribution, and 

chemistry of total dissolved solids (TDS). Both the quantity 

and quality, which is presented on trilinear diagrams, of TDS 

are discussed in relation to the probable patterns in recharge 

6

8

8

6

10

4

2

9.48

8.02

1.19

2.71

8.10

9.02 1.59

3.94

10.46

7.73

Groundwater divide

Altitude, in feet above or below North American Vertical Datum of 1988

B

NORTH

B'

SOUTH

Well

identifier

Elk River

VERTICAL EXAGGERATION x 20

126136 138 137

147

145

146 148 149

157 158

-250

-225

-200

-175

-150

-125

-100

-75

-50

-25

0

25

50

Distance, in feet

Magothy aquifer

Fill - Matawan Formation

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 5,000 5,500

3.59

Water-level altitude, in feet, May 2010

Water-level contour, interval 2 feet—

 Dashed where approximately located

Direction of groundwater flow

Precipitation/recharge

EXPLANATION

7.73

6

Confining unit

Upper Patapsco aquifer

shallow water-bearing zone

Confining unit

Upper Patapsco aquifer

deep water-bearing zone

Confining unit

Figure 31. Hydrogeologic section showing groundwater altitudes and flow directions along line B–B’, May 2010, in the 

Pearce Creek Dredge Material Containment Area and vicinity, Cecil County, Maryland. (Location of line of section B–B’ is 

shown in figure 16.)
Water Quality 61

and groundwater flow from the DMCA in each of the major 

aquifers in the study area. Collectively, these descriptions provide the basis for subsequent discussions of the redox states 

and acidity of groundwater and help illustrate the influence of 

the DMCA on the quality of groundwater in the study area, 

including that used for domestic drinking-water supplies.

Trilinear (Piper) diagrams provide a useful tool for the 

visualization of geochemical data. By plotting percentages 

of major ions, similarities and differences in the chemical 

composition of the samples can be easily illustrated. Figure 33 

shows the anionic and cationic composition of groundwater 

and surface waters in the study area. The waters are grouped 

into two different categories: low TDS (less than 300 mg/L), 

and high TDS (greater than 300 mg/L) (fig. 33A and 33B, 

respectively).

Total Dissolved Solids and Major Ions

The concentrations of TDS in the two predominant 

surface waters in the vicinity of the DMCA were markedly different (fig. 34). The concentration of TDS was relatively low 

(89 mg/L) at the controlled discharge outlet for the landlocked 

Pearce Creek Lake in comparison to the concentration of 

TDS at the main channel of the nearby Elk River tidal estuary 

(1,960 mg/L). Differences between the two waters were also 

observed in their major ion chemistries. Sodium and chloride 

were the predominant ions measured in the Elk River tidal 

estuary, whereas mixtures of calcium and sodium cations and 

sulfate and chloride anions were observed in the Pearce Creek 

Lake water (fig. 33).

The concentration and chemistry of TDS in groundwater 

is heterogeneous, both spatially and vertically, amongst and 

within different aquifers in the study area. In the Magothy 

aquifer (fig. 34), concentrations of TDS ranged from 45 to 

5,700 mg/L. Within the DMCA property boundary, all but two 

of the wells sampled (135 and 145) had TDS concentrations 

greater than 500 mg/L, the Federal Secondary Drinking Water 

Regulation (SDWR) for public drinking-water supplies. 

The two wells with the highest concentrations (greater than 

5,500 mg/L) of TDS are located just south of the DMCA 

property boundary along Pond Neck Road. Low TDS 

concentrations (less than 200 mg/L) in the Magothy aquifer 

mainly occurred in the WVS community, and specifically 

in the topographically elevated residential area that lies just 

northwest of the DMCA property boundary. The lowest concentration of TDS (45 mg/L) in the Magothy aquifer occurred 

southeast of the DMCA and its property boundary and just 

north of Pond Neck Road in well CE Dd 193, which had a 

TDS concentration similar to natural water (tables 12 and 13).

The chemistry of the Magothy aquifer also varied greatly 

within the study area. Wells with TDS concentrations under 

300 mg/L, slightly greater than level found in natural water, 

showed different chemistries than those with TDS concentrations greater than 300 mg/L. The main difference in chemistry 

was the proportion of sulfate in the samples. Sulfate was the 

most prevalent anion (typically greater than 50 percent 

of the total anion composition) in waters that had concentrations of TDS greater than 300 mg/L (fig. 33B; appendix B, 

table B3). This pattern was observed primarily in wells within 

the DMCA boundary. Wells within the WVS community with 

TDS under 300 mg/L had very low proportions of ferrous iron 

and manganese and a mixture of chloride and sulfate anions 

(fig. 33A). The higher percentages of chloride found in the 

wells under WVS may show some impact from Elk River 

water, in which chloride made up greater than 80 percent of 

the total anions (fig. 33).

In the upper Patapsco aquifer shallow water-bearing 

zone, as in the case of the Magothy aquifer, the concentrations 

of TDS also varied greatly, ranging from 75 to 6,080 mg/L 

(fig. 35). Elevated TDS concentrations occur along the southern and western parts of the DMCA (either within the DMCA 

or at its property boundary), just beyond the southeastern 

property boundary of the DMCA near Pond Neck Road, and 

west of the DMCA into WVS. Within WVS, elevated concentrations of TDS occurred peripheral to low concentrations of 

TDS (above and below but near 500 mg/L) in wells located 

in the central part of this residential area northwest of the 

DMCA. The lowest concentrations of TDS occurred in this 

water-bearing zone throughout most of the southeastern 

half of the DMCA. The lowest concentration in TDS 

(75 mg/L) occurred in the upper Patapsco aquifer shallow 

water-bearing zone at the easternmost edge of the DMCA 

property boundary (well CE Dd 191), and may indicate 

Table 12. Chemical characteristics of natural water and water affected by residential activities in the surficial aquifer of the 

Delmarva Peninsula (modified from Shedlock and others, 1993, 1999).

[mg/L; milligrams per liter; μS/cm at 25 °C; microsiemens per centimeter at 25 degrees Celsius; CaCO3, calcium carbonate; μg/L, micrograms per liter; 

<, less than; ---, not available]

Predominant 

land use

Properties Dissolved constituents

Total 

dissolved 

solids 

(mg/L)

Specific 

conductance

(μS/cm)

pH

(standard 

units)

Alkalinity

(mg/L 

as 

CaCO3

)

Calcium

(mg/L)

Magnesium

(mg/L)

Sodium

(mg/L)

Potassium

(mg/L)

Chloride

(mg/L)

Sulfate

(mg/L)

Nitrate 

as 

nitrogen

(mg/L)

Silica

(mg/L)

Iron

(μg/L)

Undeveloped < 200 115 5.8 26 4.8 1.7 9.4 1.1 9.1 6.6 < 0.4 24 1,800

Residential --- 163 5.4 6.0 7.8 4.1 9.3 2.6 16 7.5 7.1 18 2.0
62 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

0 1 2 MILES

0 1 2 KILOMETERS

Veazey Neck

Pearce Neck

Pond Neck

Elk River

Grove Neck

CE Dd 84

CE Dd 85

CE Dd 51

CE Ed 27

CE Ec 21 CE Ec 23

CE Dd 103

CE Dd 82

CE Dd 102

39°27'39°24'

75°57' 79°

Base map from U.S. Geological Survey, Earleville, MD, 1975 and  Spesutie, MD, 1984, 7.5 minute Quadrangles

EXPLANATION

Location of well and identifier

CE Ec 21

Pearce Creek

Lake

Property boundary of Pearce Creek Dredge Material Creek Dredge Material Containment Area 

Figure 32.

Wells completed in the Magothy and upper Patapsco aquifers with available groundwater data which appear to be not overly 

affected by human activities or land use near the Pearce Creek Dredge Material Containment Area and vicinity, Cecil County, Maryland.
Water Quality 63

Table 13. Available groundwater-quality data that do not appear to be overly affected by any land use in the Magothy and Upper Patapsco aquifers in the Pearce Creek Dredge Material Containment Area and vicinity.[USGS, U.S. Geological Survey; ft, feet; NAVD 88, North American Vertical Datum of 1988; bls, below land surface; mg/L, milligrams per liter; μS/cm, microsiemens per centimeter at 25 degrees Celsius; μg/L, micrograms per liter, <, less than; ---, data unavailable; UPA, upper Patapsco aquifer; shallow, shallow water-bearing zone; deep, deep water-bearing zone]

USGS local 

identifier

Land 

surface 

altitude 

(ft, 

NAVD 88)

Depth 

to top of 

screened 

interval 

(ft, bls) 

Depth to 

bottom of screened 

interval 

(ft, bls) 

Aquifer

Year 

of data 

collection

Total 

dissolved 

solids 

(mg/L)

Specific 

conductance, 

raw water 

(μS/cm)

Dissolved 

oxygen, 

raw 

water 

(mg/L)

pH 

(standard 

units)

Chloride, 

dissolved, 

(mg/L)

Sodium, 

dissolved, 

(mg/L)

Sulfate, 

dissolved, 

(mg/L)

Manganese, 

dissolved 

(μg/L)

Aluminum, 

dissolved 

(μg/L)

Iron, 

dissolved 

(μg/L)

CE Ec 23 60 118 123 Magothy 1998 --- 63 0.3 5.5 --- --- --- --- --- ---

CE Ec 21 62 --- 87 Magothy 1983 70 110 --- 5.4 12 12 8 20 <100 80CE Dd 82 61 105 125 Magothy 1983 56 60 4.3 4.5 8.3 4.7 --- --- <100 30

CE Dd 102 65 107 112 Magothy 2003 --- 52 4.3 5.2 6 4.4 6 30 20 1,030

CE Dd 84 15 90 120 UPA, 

shallow

1983 43 44 --- 4.8 4.4 3.1 2.2 --- <100 30

CE Dd 103 75.48 190 215 UPA, 

shallow 

1998 --- 53 5.3 5.3 --- --- --- --- --- ---

CE Dd 85 10 120 140 UPA, 

deep

1998 --- 152 0.2 4.6 --- --- --- --- --- ---
64 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

background concentrations (natural water) for this aquifer (see 

tables 12 and 13). 

The upper Patapsco aquifer shallow water-bearing zone 

displayed similar major ion chemistry to the Magothy aquifer 

for wells with TDS concentrations greater than 300 mg/L. 

Regardless of geographic position, sulfate was the most prevalent anion (greater than 50 percent) in samples with high TDS 

(greater than 300 mg/L). For wells with less than 300 mg/L 

of TDS, which were only located within the DMCA property 

boundary, bicarbonate was the predominant (greater than 

75 percent) anion in the water; in contrast, proportions of chloride and sulfate were very low. Although the low TDS wells 

were located in the DMCA, they were located in areas where 

the confining unit between the Magothy and upper Patapsco 

aquifer shallow water-bearing zone is present.

In the upper Patapsco aquifer deep water-bearing zone, 

the concentrations of TDS were relatively low, ranging from 

60 to 137 mg/L (fig. 36). The TDS concentrations in this 

aquifer were slightly higher along the Elk River shoreline 

(74 and 137 mg/L) than inland and southeast of the DMCA in 

this aquifer (60 and 101 mg/L). Locations with TDS concentrations less than 100 mg/L are similar to concentrations found 

in natural groundwater in this aquifer (tables 12 and 13). Well 

CE Dd 152 had a concentration of 2,100 mg/L TDS, however, 

the integrity of the sample/well may have been compromised 

during installation and was not used for groundwater flow 

20

20

40

40

60

60

80

80

100

100

100

100

100

100 100

80 80

60 60

40 40

20 20

0 0

0

0

0

0

20

40

60

80

100

0

0

20

20

20

40

40

Sulfate

Iron + manganese 

Calcium + magnesium + iron + manganese 

Chloride + sulfate

40

60

60

60

80

80

80

Calcium + magnesium

PERCENTAGE OF TOTAL MILLIEQUIVALENTS PER LITER

Sodium + potassium

Bicarbonate

Chloride

TOTAL DISSOLVED SOLIDS LESS THAN 300 MILLIGRAMS PER LITER

Pearce Creek Lake

Magothy aquifer, West View Shores

Magothy aquifer, Dredge Material Containment Area 

(DMCA) and south and east of the DMCA

Upper Patapsco aquifer, shallow water-bearing zone, 

DMCA and south and east of the DMCA

Upper Patapsco aquifer, deep water-bearing zone

EXPLANATION

A

Figure 33. Trilinear diagram for samples with A, total dissolved solids less than 300 milligrams per liter (mg/L) and B, total 

dissolved solids greater than 300 mg/L collected in the Pearce Creek Dredge Material Containment Area and vicinity, Cecil 

County, Maryland.
Water Quality 65

interpretations in this report. The complete set of data for well 

CE Dd 152 is available in appendix B, table B3 and is presented on water-quality figures in the main part of the report. 

The major ion chemistry of the upper Patapsco aquifer 

deep water-bearing zone was very similar to the chemistry of 

the upper Patapsco aquifer shallow water-bearing zone with 

similar TDS concentrations. Bicarbonate was the predominant 

anion; in contrast, proportions of chloride and sulfate were 

very low. The proportions of cations were relatively mixed and 

similar to those for water from other aquifers.

Bromide-Chloride Ratios

Mass ratios of bromide to chloride (Br:Cl, mg/L to mg/L) 

have been used to identify seawater intrusion into groundwater (Richter and Kreitler, 1993). They also have been used to 

differentiate groundwater affected by road salt and from other 

land uses (Snow and others, 1990), and brackish water from 

urban land uses (Andreasen and Fleck, 1997). In addition, R.F. 

Weston, Inc., (1998) used these ratios in an attempt to identify 

potential sources of recharge to WVS community groundwater 

supplies.

In particular, R.F. Weston, Inc., (1998) utilized statistical 

and graphical analyses of water quality data, including Br:Cl 

ratios (fig. 37), to argue that the groundwater used for supplies 

Figure 33. Trilinear diagram for samples with A, total dissolved solids less than 300 milligrams per liter (mg/L) and B, total 

dissolved solids greater than 300 mg/L collected in the Pearce Creek Dredge Material Containment Area and vicinity, Cecil 

County, Maryland.—Continued

20

20

40

40

60

60

80

80

100

100

100

100

0

0

0

20

40

60

80

100

0

0

20

20

40

Sulfate

Iron + manganese 

Calcium + magnesium + iron + manganese 

Chloride + sulfate

40

60

60

80

80

Calcium + magnesium

PERCENTAGE OF TOTAL MILLIEQUIVALENTS PER LITER

Sodium + potassium

Bicarbonate

Chloride

TOTAL DISSOLVED SOLIDS GREATER THAN 300 MILLIGRAMS PER LITER

Elk River

Fill

Magothy aquifer, West View Shores

Magothy aquifer, Dredge Material Containment Area 

(DMCA) and south and east of the DMCA

Upper Patapsco aquifer, shallow water-bearing zone, 

West View Shores

Upper Patapsco aquifer, shallow water-bearing zone, 

DMCA and south and east of the DMCA

Upper Patapsco aquifer, deep water-bearing zone

EXPLANATION

100

100 100

80 80

60 60

40 40

20 20

0 0

0

20

40

60

80

PERCENT

B
66 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area 1,960 127141 128 69 120 80 1,530 198 5,700 5,180 45 508 1,790 5,580 1,430 89 446 762 161 934 1,030 2,540 2,100 3,140 75°59' 76° 39°26' 39°25'30" 198 934 2,540 1,96089

Elk River Pearce Creek Lake

Crystal Beach

Pond Neck Road

West View Shores

Bay View Estates

EXPLANATION

Potentiometric surface contour in the Magothy aquifer—Shows altitude at which water 

would have stood in tightly cased wells, May 19–20, 2010. Dashed where approximately located. Contour interval 2 feet. Datum is North American Vertical Datum of 1988

Direction of groundwater flowLocally perched aquifer well—Number shows total dissolved solids concentration, in 

milligrams per liter (mg/L). Exceeds Federal Secondary Drinking Water Regulation (500 mg/L)

Magothy aquifer well—Number shows total dissolved solids concentration, in mg/L. 

Exceeds Federal Secondary Drinking Water Regulation (500 mg/L)

Magothy aquifer well—Number shows total dissolved solids concentration, in mg/L. 

Does not exceed Federal Secondary Drinking Water Regulation (500 mg/L)

Surface-water site—Number shows total dissolved solids concentration, in mg/L. 

Exceeds Federal Secondary Drinking Water Regulation (500 mg/L)

Surface-water site—Number shows total dissolved solids concentration, in mg/L. 

Does not exceed Federal Secondary Drinking Water Regulation (500 mg/L)

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

6

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

2

4

6

6

8

8

10

10

Figure 34. Concentrations of total dissolved solids in water-quality samples collected from selected surface waters and selected wells completed in the perched water-bearing zone or Magothy aquifer in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11.
Water Quality 67

1,960

127

641

388

4,550

725

505

402

728

2,270

3,400

75

124

362

1,090

4,640

89

101

4,000

365 8

1,430

3,830

6,080

1,320

167

4,660

241

75°59' 76°

39°26'

39°25'30"

1,320

865

1,960

89

Elk River Pearce Creek Lake

Crystal Beach

Pond Neck Road

West View Shores

Bay View Estates

EXPLANATION

Potentiometric surface contour in the upper Patapsco aquifer, shallow water-bearing 

zone—Shows altitude at which water would have stood in tightly cased wells, May 19–20, 2010..Dashed where approximately located. Contour interval 2 feet. Datum is North American Vertical Datum of 1988

Direction of groundwater flowUpper Patapsco aquifer well, shallow water-bearing zone—Number shows total dissolved 

solids concentration, in milligrams per liter (mg/L). Exceeds Federal Secondary Drinking Water Regulation (500 mg/L)

Upper Patapsco aquifer well, shallow water-bearing zone—Number shows total 

dissolved solids concentration, in mg/L. Does not exceed Federal Secondary Drinking Water Regulation (500 mg/L)

Surface-water site—Number shows total dissolved solids concentration, in mg/L. 

Exceeds Federal Secondary Drinking Water Regulation (500 mg/L)

Surface-water site—Number shows total dissolved solids concentration, in mg/L. 

Does not exceed Federal Secondary Drinking Water Regulation (500 mg/L)

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

6

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

2

4

4

6

6

8

8

Figure 35. Concentrations of total dissolved solids in water-quality samples collected from selected surface waters and selected wells completed in the upper Patapsco aquifer shallow water-bearing zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11.
68 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area 1,960 127 74 137 101 75 60 2,100 89 98 75°59' 76° 39°26' 39°25'30" 2,100 101 1,96089

Elk River Pearce Creek Lake

Crystal Beach

Pond Neck Road

West View Shores

Bay View Estates

EXPLANATION

Potentiometric surface contour in the upper Patapsco aquifer, deep water-bearing 

zone—Shows altitude at which water would have stood in tightly cased wells, May 19–20, 2010. Dashed where approximately located. Contour interval 2 feet. Datum is North American Vertical Datum of 1988

Direction of groundwater flowUpper Patapsco aquifer well, deep water-bearing zone—Number shows total 

dissolved solids concentration, in milligrams per liter (mg/L). Exceeds Federal Secondary Drinking Water Regulation (500 mg/L)

Upper Patapsco aquifer well, deep water-bearing zone—Number shows total 

dissolved solids concentration, in mg/L. Does not exceed Federal Secondary Drinking Water Regulation (500 mg/L)

Surface-water site—Number shows total dissolved solids concentration, in mg/L. 

Exceeds Federal Secondary Drinking Water Regulation (500 mg/L)

Surface-water site—Number shows total dissolved solids concentration, in mg/L. 

Does not exceed Federal Secondary Drinking Water Regulation (500 mg/L)

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

6

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

2

4

6

Figure 36. Concentrations of total dissolved solids in water-quality samples collected from selected surface waters and selected wells completed in the upper Patapsco aquifer deep water-bearing zone in the Pearce Creek Dredge Material Containment Area and vicinity, Cecil County, Maryland, 2010–11.
Water Quality 69

by WVS residents likely reflected multiple different sources—

intruded Elk River water, local recharge, including possibly 

that from an local unknown dump area, and (or) groundwater 

flow from the DMCA. However, absent sufficient information on the hydrogeologic framework and actual patterns in 

groundwater flow, R.F. Weston, Inc., indicated it was not possible to determine the actual sources of groundwater supplies 

beneath the community.

Revisiting these ratios on the basis of the 2010–11 data 

(appendix B, table B3), the ratio values for selected surface 

waters and groundwater in the study area are diverse (fig. 38). 

There does still appear to be an elevated ratio (greater than 

surface-water ratios) in groundwater associated with most supply and observation wells. However, groundwater associated 

with selected wells has ratios that are either similar in value to 

the ratio for Pearce Creek Lake, or to the ratio for Elk River 

water. 

Vertical cross sections (locations shown in figure 39) 

illustrate the relations between Br:Cl values and groundwater flow patterns. For example, anoxic groundwater in the 

western part of the DMCA in the perched water-bearing zone, 

and in the Magothy aquifer just beyond the DMCA property 

boundary near WVS, is highly enriched in bromide relative 

to chloride (fig. 40). The opposite is true for groundwater 

in the shallow oxygen-bearing zone in the Magothy aquifer beneath WVS, which have the lowest Br:Cl values for 

groundwater in the area. At depth beneath WVS, the Br:Cl 

values for groundwater in the upper Patapsco aquifer shallow water-bearing zone are intermediate in value in relation 

to their shallow water and DMCA (likely) sources, which is 

to be expected if water in this zone reflects a mixture of water 

from both sources. Furthermore, these ratios also are generally greater than the Br:Cl value for Elk River water, or for the 

oxygen-bearing groundwater much farther east in the Magothy 

aquifer, which reflect two different sources of groundwater. 

Hence, without knowledge of the hydrogeologic framework 

and patterns and chemistry of groundwater flow, it would be 

a challenge to interpret the influence of the DMCA on the 

quality of groundwater supplies in WVS solely on the basis of 

Br:Cl ratios.

Total Dissolved Solids and General Patterns in 

Groundwater Flow

Differences in the concentrations of TDS can be related 

to the general patterns in groundwater flow within and 

between the Magothy and upper Patapsco aquifers. This relation is best illustrated through visual (aerial and sectional), 

rather than statistical, comparisons of the concentrations of 

TDS at selected wells along the general and probable directions of groundwater flow. The latter are inferred from the 

potentiometric surface maps and sectional flow diagrams 

1

0.1

0.01

0.001

10 100 1,000 10,000

Upstream of Pearce 

Creek Lake

Downstream of 

Pearce Creek Lake

Dredge Material 

Containment Area 

surface-water effluent Sassafras River

Bohemia River

Elk River at West View 

Shores shoreline

Well CE Dd 81

Chloride concentration, in milligrams per liter

Ratio of bromide concentration, in milligrams per liter, to

chloride concentration, in milligrams per liter

Well located in West View Shores

Well located along Pond Neck Road

Surface-water site

EXPLANATION

Ratio of bromide concentration, in milligrams per liter to chloride 

concentration, in milligrams per liter, of the Chesapeake Bay 

(approximately 0.003, from Hem,1985, Morris and Riley, 1996, and 

Andreasen and Fleck, 1997)

Figure 37. Ratios of the concentration of bromide to the concentration of chloride as a function of the concentration of 

chloride for selected surface- and groundwater samples collected in the Pearce Creek Dredge Material Containment Area 

(DMCA) and vicinity, Cecil County, Maryland, 1995–96 (modified from R.F. Weston, Inc.,1998).
70 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

described earlier in this report (see Hydrology, this report). 

Because most of the groundwater-quality samples were collected close in time to the May 2010 synoptic assessment, the 

potentiometric surface and flow lines presented on the waterquality figures are interpreted from the May synoptic assessment presented in figures 21, 24, and 27.

For the sectional comparisons, only those wells in the 

vicinity of each line of section are used to illustrate vertical patterns in groundwater flow (fig. 39). In addition, in the 

resulting composite TDS-groundwater-flow sections, only 

the general directions of groundwater flow are shown within 

and between aquifers, without the accompanying water-level 

potentiometric contours, to facilitate visualization of the TDS 

concentrations along the probable paths of groundwater flow.

From both the aerial (fig. 34) and the vertical section A–A′ (fig. 41) perspectives, groundwater in the shallow 

perched zone, shown by well CE Dd 124 and (or) CE Dd 

144, on the west side of the DMCA, is elevated in TDS (CE 

Dd 124, 934 mg/L; CE Dd 144, 3,140 mg/L). The occurrence 

of elevated concentrations of TDS in this shallow perched 

groundwater demonstrates that the surficial sediments in the 

DMCA remain a source for elevated TDS in groundwater 

more than 20 years after the cessation in use of the DMCA 

in the early 1990s. As to the fate of these TDS, groundwater 

in this perched zone likely discharges to the local stream that 

lies between the DMCA berm and property boundary farther 

west (see Hydrology, this report). Although water-quality 

data associated with this perched groundwater are provided 

throughout later discussions of specific water-quality constituents in this report, the fate of each dissolved constituent likely 

is determined when this groundwater discharges into the local 

stream, and (or) in the stream during its flow to Elk River, 

which are beyond the scope of this report.

To the north of the perched groundwater, the DMCA is 

fairly close to Elk River. Groundwater beneath this northern 

section of the DMCA in both the Magothy aquifer (fig. 34) and 

the upper Patapsco aquifer shallow water-bearing zone 

(fig. 35) reflect the northerly flow of groundwater from the 

central interior of the DMCA. The TDS concentrations associated with this northerly flow are best illustrated in section B–B′

(fig. 42). Beneath the DMCA and just west of the groundwater 

divide, groundwater that flows north in the Magothy aquifer 

contains elevated concentrations of TDS 

(fig. 42, well 157, 1,790 mg/L). This TDS concentration is 

over 30 times greater than the TDS concentration for natural 

water found nearby in this aquifer (table 13, Magothy aquifer, 

TDS, 43, 56, and 70 mg/L). The high concentration of TDS 

in this part of the Magothy aquifer likely reflects vertical 

0

5

10

15

20

25

0 100 200 300 400 500 600 700 800 900 1,000 1,100 1,200

Chloride concentration, in milligrams per liter

Pearce Creek Lake

Elk River

EXPLANATION

Ratio (x 103) of bromide concentration, in milligrams per liter, to

chloride concentration, in milligrams per liter

Magothy aquifer

Upper Patapsco aquifer, shallow water-bearing zone

Upper Patapsco aquifer, deep water-bearing zone

Surface water near West View Shores, MD

Ratio (x 103

) of bromide concentration, in milligrams per liter, to 

chloride concentration, in milligrams per liter, of the 

Chesapeake Bay (3.3 to 3.4, from Hem, 1985, Morris and Riley, 

1996, and Andreasen and Fleck, 1997)

Figure 38. Ratios of the concentration of bromide to the concentration of chloride as a function of the 

concentration of chloride for selected surface- and groundwater samples collected in the Pearce Creek Dredge 

Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11. 
Water Quality 71

Elk River

Pearce Creek Lake

75°59' 76°

39°26'

39°25'30"

157

168122

169

155

170

Elk River

144

Elk River Pearce Creek Lake

Crystal Beach

Pond Neck Road

West View Shores

Bay View Estates

EXPLANATION

Line of sectionLocally perched groundwater observation well 

and identifier

Magothy aquifer observation well and identifierMagothy aquifer domestic well and identifierUpper Patapsco aquifer (shallow water-bearing 

zone) observation well and identifier

Upper Patapsco aquifer (shallow water-bearing 

zone) domestic well and identifier 

Upper Patapsco aquifer (deep water-bearing 

zone) observation well and identifier

Upper Patapsco aquifer (deep water-bearing 

zone) domestic well and identifier

Surface-water site and identifier

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

171

147

152

176

169

178

164

174

81

191

160

128

126

122 158

149

146

142

138

165

163

172 168

176

169

164

174

163

172 168

192

193

157 151

145

143

178

160

142128

139

137

136

124

A

B'

C'

C

B

A'

A A'

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

Figure 39. Selected wells used by the U.S. Geological Survey for water-quality descriptions along sections A–A′, B–B’, and C–C’ in the Pearce Creek 

Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland.
72 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area Magothy aquifer Fill - Matawan Formation Upper Patapsco aquifer shallow water-bearing zone Upper Patapsco aquifer deep water-bearing zone Groundwater divide Well identifier 4.19 5.41 5.75 6.93 3.07 4.48 19.2 11.6 3.82 1.08 E1.01 23.7 1.07 6.25 4.27 3.87 3.85 2.941.232.61 3.23 172 5025 -25 -50 -75 -100 -125 -150 -175 -200 -225 -250

0

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000

Distance, in feet

4,500 5,000 5,500 6,000 6,500 7,000 8,000 8,500 9,000 7,500

A

WEST

A'

EAST

193

192 191

157158 124 139122

151 81

163

168

165

164 171 142

128

178 160

Confining unit

Confining unit

Elk

River

Confining unit

Altitude, in feet above or below North American Vertical Datum of 1988

VERTICAL EXAGGERATION x 20

Ratio (x103) of bromide concen-

 tration, in milligrams per liter  (mg/L), to chloride concentration  in mg/LDirection of groundwater flowPrecipitation/recharge

EXPLANATION

5.41

Figure 40. Hydrogeologic section showing ratios of the concentration of bromide to the concentration of chloride in water-quality samples along line A–A’ and 

collected from selected surface waters, and from selected wells completed in the perched water-bearing zone, Magothy aquifer, or upper Patapsco aquifer shallow or deep water-bearing zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11. (Location of line of section A–A’ is shown in figure 39.)
Water Quality 73

Magothy aquifer

Fill - Matawan Formation

Upper Patapsco aquifer

shallow water-bearing zone

Upper Patapsco aquifer

deep water-bearing zone

172

Groundwater divide

Well

identifier

45 5,180

75

1,790

362

6,080

1,030

934

2,100 74

4,640

1,430

641

69

128

80

120

365

4,000

1,430

4,550

5025

-25-50-75

-100-125-150-175-200-225-250

0

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000

Distance, in feet

4,500 5,000 5,500 6,000 6,500 7,000 8,000 8,500 9,000 7,500

A

WEST

A'

EAST

193

192 191

157 158 124139122

151

152

81

163

168

165

164 171 142

128

178

160

Confining unit

Confining unit

Elk

River

Confining unit

Altitude, in feet above or below North American Vertical Datum of 1988

VERTICAL EXAGGERATION x 20

Total dissolved solids concentration, in  milligrams per liter (mg/L)

—Red number 

 indicates that the Federal Secondary Drinking Water Regulation (500 mg/L) was exceededDirection of groundwater flowPrecipitation/recharge

EXPLANATION

75

Figure 41. Hydrogeologic section showing concentrations of total dissolved solids in water-quality samples along line A–A’ and collected from selected surface 

waters, and from selected wells completed in the perched water-bearing zone, Magothy aquifer, or upper Patapsco aquifer shallow or deep water-bearing zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11. (Location of line of section A–A’ is shown in figure 39.)
74 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

recharge through overlying DMCA sediments. Flow at this 

location also continues vertically downward to the upper 

Patapsco aquifer shallow water-bearing zone through the 

confining layer, which is relatively thin, and consists of sandy 

and silty clay sediments (see Hydrogeologic Framework, this 

report). Leakage through this confining layer of groundwater 

elevated in TDS likely accounts for the occurrence of the moderately elevated concentration of TDS in this water-bearing 

zone (fig. 42, CE Dd 158, 362 mg/L). This TDS concentration 

is about 5 times greater than the TDS concentration in natural 

water in this aquifer (table 13, upper Patapsco aquifer, shallow 

water-bearing zone, TDS, 53 mg/L). The chemistry of CE Dd 

158 (fig. 33), despite its moderate TDS concentrations, was 

very similar to the chemistry of those wells with much higher 

concentrations of TDS. The similarities in major ion content, 

specifically a high percentage of sulfate, also indicated a vertical influence from the Magothy aquifer. 

Groundwater in both the Magothy aquifer and upper 

Patapsco aquifer shallow water-bearing zone at the groundwater divide and beneath the DMCA flows laterally to the 

north (figs. 34 and 42). In the northern part of the DMCA, the 

concentration of TDS in the Magothy aquifer is elevated 

(figs. 42 and, CE Dd 136, 2,100 mg/L). However, this concentration is not much greater than the concentration of TDS 

observed in this aquifer upgradient and in the interior of the 

DMCA. 

3,400

2,540

1,320

101

98

362

1,790

446

2,100

167

Groundwater divide

Altitude, in feet above or below North American Vertical Datum of 1988 

B

NORTH

B'

SOUTH

Well

identifier

Elk River

VERTICAL EXAGGERATION x 20

126 136 137 138

147

145

146 149

157 158

-250

-225

-200

-175

-150

-125

-100

-75

-50

-25

0

25

50

Distance, in feet

Magothy aquifer

Fill - Matawan Formation

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 5,000 5,500

Confining unit

Upper Patapsco aquifer

shallow water-bearing zone

Confining unit

Upper Patapsco aquifer

deep water-bearing zone

Confining unit

Total dissolved solids concentration, in 

 milligrams per liter (mg/L)—Red number 

 indicates that the Federal Secondary

 Drinking Water Regulation (500 mg/L)

 was exceeded

Direction of groundwater flow

Precipitation/recharge

EXPLANATION

362

Figure 42. Hydrogeologic section showing concentrations of total dissolved solids in water-quality samples along line 

B–B’ and collected from selected wells completed in the Magothy aquifer or upper Patapsco aquifer shallow or deep 

water-bearing zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 

2010–11. (Location of line of section B–B’ is shown in figure 39.)
Water Quality 75

By way of contrast, the concentration of TDS is relatively 

low in the underlying upper Patapsco aquifer shallow waterbearing zone in this northern section of the DMCA (fig. 42, 

CE Dd 126, 167 mg/L). It is only about half the concentration 

of TDS observed in this water-bearing zone generally upgradient and in the interior of the DMCA (fig. 42, CE Dd 158, 

362 mg/L). This decline in TDS implies the leakage observed 

through the confining layer into this zone in the DMCA 

interior is not extensive, and is consistent with the increasing thickness of the overlying upper Patapsco confining layer 

along B–B′ to the north (see Hydrogeologic Framework, this 

report). 

The quality of the TDS also indicates that leakage 

through the confining zone in the northern section of the 

DMCA area is not extensive. As mentioned previously, despite 

only moderate TDS concentrations, water from CE Dd 158 

is chemically similar to water from wells with much higher 

concentrations of TDS, particularly those with a high percentage of sulfate (fig. 33). In contrast, water from CE Dd 126 is 

chemically very different; this water was dominated by bicarbonate but had very low percentages of sulfate (fig. 33).

Farther north beyond the DMCA berm, but within the 

DMCA property boundary, along B–B′, the Magothy aquifer 

crops out beneath the shoreline and Elk River (fig. 42). Here 

groundwater flow from this shallow aquifer and upgradient 

flow from the underlying upper Patapsco aquifer shallow 

water-bearing zone converge and discharge either into Pearce 

Creek (downstream of the lake outlet), or along the shoreline or beneath the Elk River (fig. 42, CE Dd 145, 146, and 

147). The concentration of TDS in the Magothy aquifer at this 

northerly location is notably lower (fig. 42, CE Dd 145, 

446 mg/L) compared to the elevated TDS concentration 

observed in the Magothy aquifer upgradient and interior to 

the DMCA (fig. 42, CE Dd 136, 2,100 mg/L). The chemistry 

of water from CE Dd 145 is typical of water from wells with 

TDS greater than 300 mg/L, specifically the high percentage 

of sulfate (fig. 33). The reduced TDS concentration in the 

Magothy aquifer at this location could reflect groundwater 

recharge from Pearce Creek Lake, which has a similar chemistry, although a lower percentage of sulfate (fig. 34, TDS equals 

89 mg/L). Recharge likely occurs seasonally when lake levels 

are high along the lower part of the lake (see Hydrology, this 

report). 

Well CE Dd 145 can be used as a TDS point of reference 

to evaluate the possible effect of DMCA discharge on the Elk 

River. The TDS concentration in the Magothy aquifer near 

the northern DMCA property boundary (fig. 42, CE Dd 145, 

446 mg/L) is about 7 to 8 times greater than the concentration 

of TDS in natural water for this aquifer (table 13, Magothy 

aquifer). Whether or not this concentration of TDS in the 

Magothy aquifer at this location is of concern depends in part 

upon the nature of the TDS, which is predominantly sulfate. 

However, the transport and fate of the individual dissolved 

constituents as this groundwater discharges along the shoreline, or directly through bed sediments into the Elk River, are 

beyond the scope of this report. In addition, consideration 

needs to be given to the water quality of the receiving body, 

the Elk River, which has a TDS concentration of 1,960 mg/L 

(fig. 34) and chemistry that is predominantly made up of 

sodium and chloride ions.

In the eastern and southern parts of the DMCA and 

vicinity, from an aerial perspective (figs. 34 and 35), elevated 

concentrations of TDS (greater than 500 mg/L) occur downgradient of the groundwater divides in the Magothy aquifer 

and in the upper Patapsco aquifer shallow water-bearing zone 

at all but the most easterly sites. From a vertical perspective 

to the east along A–A′ (fig. 41), in the Magothy aquifer in the 

interior of the DMCA, elevated TDS concentrations, composed mainly of sulfate, occurred near the groundwater divide 

(CE Dd 157, 1,790 mg/L) and likely reflect vertical recharge 

through overlying DMCA sediments. Farther to the east near 

the DMCA property boundary, and just south of the groundwater divide, the concentrations of TDS were quite high (CE Dd 

192, 5,180 mg/L). Absent additional information, it is unlikely 

that the elevated TDS at depth in the Magothy aquifer at this 

location reflect groundwater flow into the DMCA area from 

farther to the east, or through the confining unit from above. 

Either source of water is extremely low in TDS (fig. 41, CE 

Dd 193, 45 mg/L; CE Dd 191, 75 mg/L). 

The extremely high concentration of TDS in the Magothy 

aquifer at CE Dd 192 could reflect groundwater flow from the 

southeastern part of the DMCA. Similar elevated concentrations of TDS with high proportions of sulfate occur in the 

Magothy aquifer south and downgradient of the groundwater 

divide within the DMCA property boundary and along Pond 

Neck Road (fig. 34, CE Dd 125 and 153; 5,700 and 5,580 

mg/L, respectively). In addition, elevated concentrations of 

TDS also occur in the upper Patapsco aquifer shallow waterbearing zone south and downgradient of its groundwater 

divide—within the DMCA, within the DMCA property boundary, and outside the DMCA property boundary (fig. 35, CE 

Dd 138, 149, and 154; 1,320, 3,400, and 1,090 mg/L, respectively). These elevated TDS concentrations also reflect leakage 

through the relatively thin and permeable confining layer 

described earlier, but reflect southerly rather than northerly 

groundwater flow (fig. 42).

The elevated concentrations of TDS in both of these 

aquifers, which are attributed to groundwater flow from the 

DMCA, are considerable. The TDS concentrations in excess 

of 5,000 mg/L in the Magothy aquifer in the eastern and southern locations described above are 90–100 times greater than 

the concentration of TDS in natural water in this aquifer 

(table 13, Magothy aquifer). The TDS concentrations in the 

upper Patapsco aquifer shallow water-bearing zone in the 

southern locations described above are approximately 14 to 

48 times greater than the concentration of TDS in natural 

water for this aquifer (table 13, upper Patapsco aquifer shallow 

water-bearing zone). 

Along the western part of the DMCA, elevated TDS 

concentrations occur within the DMCA, at its property 

boundary, and beyond into WVS in both the Magothy aquifer 

(fig. 34) and the upper Patapsco aquifer shallow water-bearing 
76 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

zone (fig. 35). In the Magothy aquifer (fig. 34), westward 

groundwater flow begins in the interior southern half of the 

DMCA, and from there moves through the lower western part 

of the DMCA to its property boundary with WVS. Elevated 

concentrations of TDS associated with westward flow within 

the DMCA property boundary are between 1,000 and 2,000 

mg/L in the Magothy aquifer (fig. 34). Concentrations of TDS 

in the underlying upper Patapsco aquifer shallow water-bearing zone were lower than or similar to those in the Magothy 

aquifer at two wells near the central interior of the DMCA but 

are markedly elevated (4,000 to 6,000 mg/L) near the westernmost point in the DMCA (fig. 35). Toward the west (toward 

WVS) along A–A′ (fig. 41), groundwater flow with elevated 

TDS in the Magothy aquifer beneath the DMCA likely travels 

beyond the berm, and at least to well CE Dd 152. However, 

along this part of the groundwater flow system, and farther 

west into WVS, the following patterns in groundwater flow 

and TDS concentrations were observed (fig. 41): 

(1) Elevated concentrations of TDS occurred in the 

deeper Magothy aquifer groundwater just beyond the DMCA 

dike in WVS (CE Dd 151, 1,430 mg/L), concomitant with 

a vertically downward gradient where local recharge occurs 

through this elevated part of WVS; and

(2) Highly elevated concentrations of TDS (4,000–

6,000 mg/L) occurred beneath the WVS community in the 

upper Patapsco aquifer shallow water-bearing zone, where 

the confining unit between the Magothy and upper Patapsco 

aquifers is absent and flow is vertically downward. 

In the Magothy aquifer in the WVS area (fig. 41), shallow 

groundwater flow is determined by vertical recharge—both 

from precipitation and residential land use. The latter includes 

outdoor water uses such as irrigation and effluents from 

individual septic systems for every residence. Nevertheless, 

shallow groundwater in the Magothy aquifer in the elevated 

central part of WVS contained relatively low TDS (less than 

approximately 130 mg/L) and had a chloride dominated 

chemistry.

Groundwater flow with elevated TDS from the western 

end of the DMCA that travels vertically downward into the 

upper Patapsco aquifer shallow water-bearing zone can travel 

farther north in this zone and beneath the confining layer 

before possibly discharging vertically upwards and eventually 

into Elk River (fig. 43). As observed in section A–A′, shallow 

groundwater in the Magothy aquifer in section C–C′ contains 

low concentrations of TDS (CE Dd 163, 69 mg/L), which 

likely reflect local recharge from precipitation and residential 

use.

The patterns in groundwater flow and the low TDS 

concentrations beneath the WVS community indicate that it 

is unlikely that the community is responsible for the elevated 

TDS concentrations found at depth beneath their community. 

The chemistry of the water from Magothy wells under WVS 

was different from that at other wells with TDS concentrations 

less than 300 mg/L (fig. 33). Chloride and sulfate accounted 

for the majority of the anions in water from the WVS Magothy 

wells, whereas, other waters with TDS concentrations less 

than 300 mg/L had a higher proportion of bicarbonate.

The patterns in the TDS concentrations and groundwater 

flow beneath and in the vicinity of the DMCA indicate that the 

DMCA is the most likely source of elevated concentrations of 

TDS in groundwater in the Magothy aquifer and upper Patapsco aquifer shallow water-bearing zone. There was also a clear 

distinction in the chemistry of water based on the concentration of TDS. For those waters with greater than 300 mg/L of 

TDS, sulfate was the most prevalent ion, regardless of aquifer 

or well location. For those wells with TDS concentrations less 

than 300 mg/L, closer to levels found in natural groundwater 

for the aquifer, the chemistry was not dominated by sulfate 

and varied between location.

Electromagnetic-Induction Logging

Electromagnetic-induction logs support the use of waterquality sampling from wells screened at discrete intervals 

to describe groundwater quality in each aquifer. These logs 

are obtained by running an induction probe inside a well and 

simultaneously recording the conductivity of the water outside 

the borehole as the probe is lowered and then raised through 

the entire length of the well. The major hydrogeologic factors 

that affect induction logs in sand and gravel aquifers are the 

TDS concentration in the groundwater and the silt and clay 

content of the aquifer (Williams and others, 1993). Lithologic 

information from sediment-core descriptions and natural 

gamma-ray logs were used in combination to determine 

whether the increased conductivity of a given zone is related 

to the TDS concentration or to the silt and clay content. 

A vertical profile of the concentrations of TDS and the 

induction logs for selected wells within the Magothy aquifer 

and upper Patapsco aquifer shallow and deep water-bearing 

zones was constructed along the line of section A–B (fig. 44). 

Conductivity increases toward the right on the induction logs 

with a scale ranging from 0 to 100 millisiemens per meter. The 

induction logs clearly mark the extent of the poorest quality 

water in relation to TDS content of groundwater. The largest 

deflections to the right are noted on the section and generally 

correspond to 100 millisiemens per meter on the log scale. 

Also shown on section A–B are the location of the sampled 

intervals of wells within each nested site and the concentration of TDS in mg/L obtained from those intervals. Zones of 

highest conductivity marked by signatures on the induction 

logs are consistent with high concentrations of TDS recorded 

in sampled wells. Thus, section A–B shows that the extent 

of poor quality water containing high TDS concentrations is 

greatest in vertical thickness in the upper Patapsco aquifer 

shallow water-bearing zone in the most upgradient well of the 

section (CE Dd 152), namely near the DMCA beginning at an 

elevation of approximately –30 ft NAVD 88. Induction-log 

signatures show zones of highest conductivity downgradient 

toward the Elk River and mainly are situated in the bottom 

30 ft of this zone beginning at elevations of –70 to –80 ft 
Water Quality 77

NAVD 88. Similar TDS-conductivity log relations constructed 

for wells along the western side of the DMCA (line of section B–C, fgure 45, which includes wells CE Dd 130, 122, 

and 152) show signatures which also confirm relatively thick 

zones of high conductivity water occur at shallow depths, and 

at the base of the Magothy aquifer where confined, inside the 

DMCA. 

The downward and downgradient movement of highconductivity water representative of high TDS concentration 

is consistent with groundwater flow conditions that indicate 

recharge to the unconfined system, strong downward gradients of flow, and movement of water downgradient to the Elk 

River. 

As shown in the above examples, TDS concentrations in 

sand and gravel aquifers can differ by more than an order of 

magnitude within a vertical distance of a 5 to 10 ft. At a single 

location, the water quality sampled from monitoring wells 

can markedly change, depending on the vertical placement 

of screened intervals. However, in the case of this study, the 

occurrence of highly elevated concentrations of TDS and high 

log-conductance do frequently co-occur and reflect high TDS 

and thick water-bearing zones. The induction logs also indicate that the vertical extent of the aquifer with high TDS water 

likely is greater in and near the western side of the DMCA 

than indicated solely by groundwater sampling (figs. 44 and 

45; circled high-conductance areas in log sections without 

well locations). In addition, as the downgradient distance from 

the DMCA through WVS increases, both the concentrations of 

TDS and log-conductance patterns indicate the poorest quality 

groundwater occurs at depth within the upper Patapsco aquifer 

shallow water-bearing zone, which is consistent with the flow 

of groundwater from the DMCA to beneath WVS.

Reduction-Oxidation Processes

Historical Influences on Reduction-Oxidation 

Processes

The topographic map from 1900 indicates that the area 

upon which the DMCA was built was a natural, inner-coastal, 

tidal wetland, which drained into the Elk River directly, or 

Pearce Creek, which, in turn, drained into the Elk River 

(fig. 3; see Hydrology, this report). Prior to construction of 

the DMCA, the 1900 topography combined with the hydrogeologic framework for this area indicate that this wetland 

likely was a discharge area for shallow groundwater, flowing 

from topographic highs on the peninsula uplands towards the 

topographically low wetlands, as well as discharge from parts 

of the Magothy aquifer. Given the descriptions of groundwater 

quality for wetlands overlying similar stratigraphy, groundwater flow to this wetland likely would have been slow, and 

the chemistry of groundwater would have been governed by 

reducing conditions (Shedlock and others, 1993, 1999; Speiran, 1996). Under such reducing conditions, and given natural 

groundwater conditions in the area, groundwater associated 

with the original wetland likely would have contained little to 

no dissolved oxygen or nitrate-nitrogen and possibly elevated 

concentrations of metals such as iron. However, as groundwater discharged into and from this wetland, redox-sensitive 

metals, such as iron and manganese, and minerals, such as iron 

sulfide, likely would have oxidized, precipitated, and accumulated in wetland sediments.

Construction of the DMCA likely changed this wetland 

area over time from a groundwater discharge area to a local 

groundwater recharge area. Construction of the DMCA berms, 

placement of dredge materials, and resulting increases in land 

surface, Pearce Creek Lake levels, and groundwater levels 

reversed the natural flow directions. The construction of the 

DMCA would have also caused the native wetland sediments, 

typically high in organic material, to be buried under the 

dredge materials.

During the use of the DMCA, Elk River water was mixed 

with sediments, and the slurry was pumped into the bermed 

area of the DMCA. This process likely resulted in an appreciable increase in recharge compared to recharge from normal 

amounts of precipitation. Up to several feet of standing water 

were drained from the DMCA , primarily through a sluice, 

over the course of several days after each batch of sediment 

slurry was deposited (D. Sirkis, USACE, written commun., 

2010). The effects on hydraulic head from adding Elk River 

water are illustrated by the rise in water levels associated 

with the recharge from Tropical Storm Nicole, which reflects 

less than 0.5 ft of water being deposited over the DMCA (see 

Hydrology, this report). The mixing of anoxic bay sediments 

with oxic Elk River water also likely would result in the temporary oxidation of shallow dredged sediments, which contain 

minerals such as ferrous sulfide and pyrite. The oxidation of 

these minerals could lead to acidic conditions and the mobilization of metals during and initially following sediment deposition concomitant with recharge. Similar oxidizing, acidic, 

and mobilizing conditions could arise in surficial deposited 

sediments during annual drying (summer) and wetting (winter) 

cycles within the DMCA, which also could promote the mobilization of metals; whereas deep sediments likely remained 

under reduced conditions. 

Repetition of the above dredged-sediment disposal 

process over time has raised the level of deposited sediments 

(fill) in the DMCA by 30 ft or more (see Hydrogeologic

Framework, this report). This is a substantial increase in 

material enriched in carbon, nitrogen, sulfur, and metals (see 

Northern Chesapeake Bay Sediments, this report). Also 

because deposited dredged material contained an abundance of 

fine-grained organic and silty sediments, drainage conditions 

in the DMCA have remained poor. 

Current (2010–11) groundwater levels in the DMCA and 

vicinity and a seasonal dense Phragmites (species unknown) 

cover indicate the containment area has become an elevated 

recharging artificial wetland (fig. 5, see Hydrology, this 

report). As such, the DMCA’s historical influence on groundwater could not only be as a source of elevated concentrations 

of TDS, but also as a geochemical driver of redox processes 
78 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

0

50

25

74

169

174 176 171 164 163

81 151

1,960

402

505 728

641

69 1,430

4,640

Altitude, in feet above or below North American Vertical Datum of 1988 

C

NORTH

C'

SOUTH

Well

identifier

Elk River

-100-125-150-175-200-225-250

-25-50-75

0 200 400 600 800 1,000 1,200 1,400 1,600 1,800 2,000 2,200 2,400

Distance, in feet

VERTICAL EXAGGERATION x 6

Magothy aquifer

Confining unit

Upper Patapsco aquifer

shallow water-bearing zone

Confining unit

Upper Patapsco aquifer

deep water-bearing zone

Confining unit

Total dissolved solids concentration, in milligrams  per liter (mg/L)

—Red number indicates that the 

 Federal Secondary Drinking Water Regulation  (500 mg/L) was exceededDirection of groundwater flowPrecipitation/recharge

EXPLANATION

362

Figure 43. Hydrogeologic section showing concentrations of total dissolved solids in water-quality samples along line C–C’ and collected from selected 

surface waters and from selected wells completed in the Magothy aquifer or upper Patapsco aquifer shallow or deep water-bearing zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11. (Location of line of section C–C’ is shown in figure 39.)
Water Quality 79

Magothy aquiferUpper Patapsco aquifershallow water-bearing zone

Upper Patapsco aquifer

deep water-bearing zone

Wellidentifier

5025

-25-50-75

-100-125-150-175-200-225-250

0

0 500 1,000 1,500 2,000 2,500 3,000

Distance, in feet

A

B

Altitude, in feet above or below North American Vertical Datum of 1988 Confining unit Confining unit Upper Patapsco

VERTICAL EXAGGERATION x 7

EXPLANATION

CE Dd 141 CE Dd 160 CE Dd 128 CE Dd 152

4,640 4,000

4,000

3,830

161

762

1,430

1,430

2,100

137

4,550

Electromagneticinduction log

Well location

Zone of high conductivity waterIndicates position of open interval in 

well or adjacent nested well and measured total dissolved solids concentration, in milligrams per liter

Sections dashed where approximately 

located

Figure 44. Hydrogeologic section showing electromagnetic-induction logs, total dissolved solids concentrations (in milligrams per liter), and hydrogeology along line A–B. (Location of line A–B is shown in figure 10.)
80 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area 1,090 60 2,540 1,320 934 1,030 6,080 1,430 4,640 2,100 5,580 Magothy aquifer Matawan confining unit Magothy aquifer Upper Patapsco aquifer shallow water-bearing zone Upper Patapsco aquifer deep water-bearing zone 5025 -25 -50 -75 -100 -125 -150 -175 -200 -225 -250

0

0 1,000 2,000 3,000 4,000 5,000 6,000

Distance, in feet

B

C

Altitude, in feet above or below North American Vertical Datum of 1988 Confining unit Confining unit

VERTICAL EXAGGERATION x 14

CE Dd 152

CE Dd 130

CE Dd 122 CE Dd 138 CE Dd 155 Well identifier

EXPLANATION

2,540

Zone of high conductivity waterIndicates position of open interval in 

well or adjacent nested well and measured total dissolved solids concentration, in milligrams per liter

Sections dashed where approximately 

located

Electromagneticinduction log

Well location

 Figure 45. Hydrogeologic section showing electromagnetic-induction logs, total dissolved solids concentrations (in milligrams per liter), and hydrogeology along line B–C. (Location of line B–C is shown in figure 10.)
Water Quality 81

that enhance the mobilization and transport of redox-sensitive 

metals and nutrients in the DMCA fill-Matawan sediments as 

well as in the underlying aquifers. 

Terminal Electron Acceptor Process Analysis

Redox processes can markedly affect the quality of 

groundwater in an aquifer. These processes have been shown 

to immobilize or mobilize potentially toxic metals in natural 

aquifers (Lovely and others, 1991; Smedley and Kinniburgh, 

2002; McMahon and Chapelle, 2008); and generate undesirable byproducts, including ferrous iron, hydrogen sulfide, and 

methane (Back and Barnes, 1965; Baedecker and Back, 1979; 

Chapelle and Lovley, 1992). 

McMahon and Chapelle (2008) developed a terminal 

electron acceptor process (TEAP) methodology to help identify the dominant redox conditions and predominant redox 

processes in groundwater for 15 principal aquifers in the 

United States. This analytical and systematic framework was 

developed on the basis of frequently observed ecological patterns in the sequential reduction of dissolved oxygen, nitrate, 

and sulfate in groundwater, and the threshold concentrations 

of these substrates to support microbial populations, combined 

with the utilization of manganese and iron as solid-phase electron acceptors to indicate the production of dissolved manganese and iron.

The method of Jurgens and others (2009), which automated the TEAP analytical approach and framework developed by McMahon and Chapelle (2008), was used in this 

report to help identify the dominant redox conditions and 

processes for the study area. For the purposes of this report, 

their automated method was used to compare the dominant 

redox conditions and processes with the probable patterns in 

groundwater flow, TDS, and other indicators of water quality to help determine the probable influence of the DMCA on 

groundwater in the study area.

In the Jurgens and others (2009) method, it is assumed 

that pH is moderate (6.8–8.6), that there is sufficient total dissolved carbon to meet microbial demands, and that the total 

(recoverable) dissolved concentrations of iron and manganese 

accurately reflect the concentrations of the bivalent metals 

Fe2+ and Mn2+, respectively (McMahon and Chapelle, 2008; 

Chapelle and others, 2008). However, if the system contains 

an abundance of total dissolved carbon, it is possible have 

multiple, simultaneous reduction processes occurring. If the 

proper microorganisms are present, iron, manganese and sulfate reduction, as well as methanogenesis can occur simultaneously when there is no competition for an organic donor. 

Measurement of the concentrations of dissolved oxygen, 

nitrate, sulfate, sulfide, and dissolved methane gas are recommended by Jurgens and others (2009) for the TEAP analyses. 

All these constituents were directly measured for groundwater in the DMCA and vicinity, except nitrate and methane. Because concentrations of nitrite occurred at no more 

than trace levels in groundwater (appendix B, table B3), the 

concentration of nitrate plus nitrite was used to estimate nitrate 

nitrogen.

The TEAP analysis reflects redox conditions generally 

facilitated by microorganisms that obtain energy by transferring electrons from donors (usually organic carbon) to 

acceptors (usually inorganic species). Because some electron 

acceptors provide more energy than others, electron acceptors 

are utilized by these microorganisms in the order of energy 

provided by the acceptors, from most to least in energy gain. 

With sufficient, but not excess, carbon sources, the order of 

progression in the reduction of inorganic species usually is 

as follows: dissolved oxygen (O2

), nitrate (NO3

–

), manganese 

(Mn(IV)), iron (Fe(III)), sulfate (SO4

2–), and carbon dioxide 

(CO2(g)). Hence, the concentrations of the soluble electron 

acceptors—(O2), nitrate (NO3

–

), and sulfate (SO4

2–)—and 

of the TEAP end products—manganese (Mn2+), iron (Fe2+), 

ammonia, sulfide [H2STotal the sum of dihydrogen sulfide 

(H2S), hydrogen sulfide (HS–), and sulfide (S2–)], and methane 

(CH4(g))—can be used to identify the dominant redox conditions and processes in groundwater within, beneath, and in the 

vicinity of the DMCA. 

Dissolved CH4(g) was not measured, as it was not 

sampled in past studies, nor were there any indications of its 

occurrence base on interpretation in past studies (U.S. Army 

Corps of Engineers, 1996; R.F. Weston, Inc., 1998). Because 

groundwater in the DMCA and vicinity generally is more 

acidic (appendix B, table B3, pH 4.0—6.6) than groundwater 

considered by McMahon and Chapelle (2008, pH 6.5–8.5), the 

use of the dissolved recoverable concentrations of iron for the 

concentrations of Fe2+ warrants explanation. At the low end 

of the pH range for groundwater in the DMCA and its vicinity, the concentration of dissolved recoverable metals such as 

iron likely reflects ferric (Fe3+) as well as ferrous (Fe2+) iron. 

Except for groundwater with measurable dissolved oxygen, 

the concentrations of dissolved recoverable metals in groundwater are highly elevated, and in most cases, orders of magnitude above the TEAP threshold concentration necessary to 

support microbial-reducing conditions for these metals. Thus, 

it was assumed that the actual concentrations of Fe2+, even if 

not equal to the dissolved recoverable concentration of iron, 

would still be in excess of that needed to support microbial 

reduction requirements (table 14, Individual half-reaction, 

concentration of Fe2+ ≥ 0.1 mg/L).

Chapelle and others (2008) note that anoxic groundwater 

systems also can be dominated by sulfate-reducing conditions. 

To distinguish between iron- and sulfate-reducing conditions, 

they observed that concentrations of ferrous iron and hydrogen 

sulfide in groundwater systems tend to be inversely (hyperbolically) related. The authors determined that measurements 

of dissolved (ferrous) iron, sulfate, and hydrogen sulfide could 

be used to distinguish which, if either, of these two reduction 

processes likely is dominant. For iron reduction to be 

the dominant process, the iron-to-hydrogen sulfide mass 

ratio must exceed 10 (table 14, iron (Fe2+) ≥ 0.1 mg/L; sulfate 

≥ 0.5 mg/L; and iron-to-hydrogen sulfide mass ratio [(mg/L)/

(mg/L) ≥ 10]. For sulfate reduction to be the dominant 
82 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

process, the iron-to-hydrogen sulfide ratio cannot exceed 3. 

For ratios between 3 and 10, both processes could be occurring simultaneously, and (or) in close proximity with reduced 

waters mixing in the well borehole. 

Dissolved Organic Carbon

DOC concentrations appeared more than adequate for 

microbial reduction. Concentrations of dissolved (recoverable) 

carbon generally were one to two orders of magnitude greater 

than the dissolved carbon concentrations found in surficial 

or confined natural groundwater on the Delmarva Peninsula 

(Shedlock and others, 1993, 1999). Higher dissolved carbon 

concentrations also occurred in conjunction with high TDS 

concentrations. 

Bay sediments contain abundant amounts of organic 

carbon (table 8, carbon, 21,810 mg/kg). The DMCA fill also 

likely contains abundant organic carbon from deposited bay 

sediments. In addition, the original wetland sediment, buried 

by DMCA fill, may have been a significant source of organic 

carbon. Seasonal Phragmites vegetation within the DMCA 

continues to provide an additional source of organic carbon to 

the containment area.

Groundwater in both the perched water-bearing zone and 

the Magothy aquifer within the DMCA property boundary 

contained elevated concentrations of DOC (fig. 46). Concentrations of DOC range from approximately 3 to 13 mg/L. By 

way of contrast, concentrations in shallow groundwater in 

Magothy aquifer beneath WVS are no more than 2 mg/L and 

are generally less than 1 mg/L. To the east beyond the DMCA 

property boundary, the concentration of DOC in groundwater 

not overly affected by anthropogenic activities is less than 

0.3 mg/L (fig. 46; appendix B, table B3).

Groundwater in the upper Patapsco aquifer shallow 

water-bearing zone and along the southwestern part of the 

DMCA and property boundary contains elevated concentrations of DOC—approximately 4–11 mg/L (fig. 47). Beneath 

WVS, concentrations of carbon also are elevated and are 

approximately 1–7 mg/L. The lowest concentrations of DOC 

occur along the eastern property boundary of the DMCA and 

are less than 0.6 mg/L. Similar low concentrations are found 

in the upper Patapsco aquifer deep water-bearing zone (appendix B, table B3).

Elevated concentrations of DOC may have been a 

major cause of the reducing conditions found in groundwater associated with groundwater flow from the DMCA (for 

example, fgure 48). The occurrence of DOC at elevated 

levels in groundwater flow from the DMCA into the Magothy 

aquifer and ultimately into the upper Patapsco aquifer shallow water-bearing zone beneath WVS is significant. Elevated 

concentrations of DOC from the DMCA provide an abundance 

of carbon to support microbial reduction and mobilization of 

metals in the upper Patapsco aquifer shallow water-bearing 

zone beneath WVS.

Reduction-Oxidation Conditions and Processes

Summary results for the TEAP analysis identified five 

general redox categories and corresponding reduction processes characterizing groundwater in the DMCA and its 

vicinity (table 14). Also included in this summary are the corresponding individual half-cell reactions and threshold conditions for each individual reduction process. The TEAP results 

can be characterized on the basis of the dominant condition 

and predominant reduction process identified for each well 

(table 15).

The five major redox categories and corresponding reduction reaction processes indicate groundwater in the DMCA 

and vicinity include oxic (O2 reducing condition), mixed oxicanoxic (O2

–Mn(IV) or O2–Fe(III) reducing condition), mixed 

anoxic (NO3–Fe(III) reducing conditions), anoxic ((Fe(III) 

reducing), and CH4(g) generating conditions (table 15). The 

oxic or anoxic categories reflect a single species predominant 

in the redox condition, whereas the mixed reducing conditions 

(O2

–Fe(III), O2–Mn(IV), or NO3–Fe(III)) warrant explanation. 

Mixed categories reflect groundwater associated with different 

reducing processes. Mixed conditions could reflect: (a) two 

reduction processes occurring simultaneously in the sediment, 

with neither process fully dominating, (b) borehole mixing 

of groundwater undergoing different reduction processes at 

different depths along, or different distances from, the well 

screen (Jurgens and others, 2009; McMahon and Chapelle, 

2008), or (c) simultaneous reactions occurring due to the abundance of DOC found in the majority of the waters. 

With the potential causes in mind, the TEAP analysis can 

be used to describe redox conditions and processes in different 

parts of the surface-water and groundwater system in the study 

area. Redox conditions differed for surface waters. At the 

Pearce Creek Lake outlet, lake discharge reflected a slightly 

reduced, mixed oxic-anoxic condition (fig. 49, O2–Mn); 

whereas Elk River water was found to be oxic (fig. 49, O2). 

Groundwater in the perched zone and the Magothy aquifer 

within the DMCA property boundary, and along Pond Neck 

Road, are anoxic, and, except for well CE Dd 135, reflect 

groundwater where ferric (Fe3+) iron likely is being reduced 

(fig. 49, Fe(III)). Groundwater associated with well CE Dd 

135 is classified as under anoxic conditions and potentially 

generating methane (fig. 49, CH4(g), NC). 

By way of contrast, except for groundwater associated 

with well CE Dd 143, shallow groundwater in the Magothy 

aquifer and surface waters in the vicinity, but beyond the property boundary of the DMCA, exhibit a variety of different but 

generally less severe reducing conditions—either oxic (O2) or 

mixed oxic-anoxic conditions (fig. 49, O2–Mn(IV) or Fe(III)), 

indicating that oxygen and either Mn(IV) or Fe(III) are being 

reduced. The chemistry of the groundwater from well CE Dd 

143 reflects a mixed anoxic condition associated with nitrate 

(NO3

–

) and ferric iron reduction (fig. 49, NO3

–

-Fe). The variety 

of redox conditions and reducing processes associated with 

groundwater in the Magothy aquifer beneath WVS could 

reflect pumping-induced mixing of groundwater with different 
Water Quality 83

Table 14. Terminal electron acceptor classification criteria for redox categories and processes, and related reduction reactions, assigned on the basis of water-quality data obtained from groundwater samples collected in the Pearce Creek Dredge Material Containment Area and vicinity, 2010–11 (modified from Jurgens and others, 2009).[Chemical species: O2, dissolved oxygen; NO3-, dissolved nitrate; MnO2(s), manganese oxide with manganese in 4+ oxidation state; Fe(OH)3(s), iron hydroxide with iron in 3+ oxidation state; FeOOH(s), iron 

oxyhydroxide with iron in 3+ oxidation state; SO42–, dissolved sulfate; CO2(g), carbon dioxide gas; CH4(g), methane gas; Redox category: O2 ≥ 0.5 mg/L, dissolved oxygen greater than or equal to 0.5 mg/L; O2

< 0.5 mg/L, dissolved oxygen less than 0.5 mg/L; Redox process: O2, oxygen reduction; NO3, nitrate reduction; Mn(IV), manganese reduction; Fe(III), iron reduction; SO4, sulfate reduction; CH4gen, methanogenesis; Abbreviations: mg/L, milligrams per liter; ≥, greater than or equal to; >, greater than; Y, yes; N, no; ---, criteria do not apply because the species concentration is not affected by the redox process; 

x, not applicable]

Redox category1 Redox process1 Dissolved oxygen (≥ 0.5 mg/L) Nitrate, as nitrogen (≥ 0.5 mg/L) Manganese (≥ 0.05 mg/L) Iron (≥ 0.1 mg/L) Sulfate (≥ 0.5 mg/L) Iron/hydrogen sulfide mass ratio (> 0.3) Iron/hydrogen sulfide mass ratio (> 10)

Oxic O2 Y --- N N --- x x

Mixed (oxic and anoxic) O2 and Mn(IV) Y --- Y N --- x x

Mixed (oxic and anoxic) O2 and Fe(III) Y N --- Y Y Y Y

Mixed (anoxic) NO3 and Fe(III) N Y --- Y Y Y Y

Anoxic Fe(III) N N --- Y Y Y Y

Anoxic CH4gen N N --- Y N x x

Individual electron acceptor (reduction) half-reaction

Oxic O2 O2 + 4H+ + 4e- → 2H O2

Anoxic NO3 2NO3- + 12H+ + 10e- → N2(g) + 6 H O; NO 2 3- + 10H+ + 8e- → NH4+ + 3H O2

Anoxic Mn(IV) MnO2(s) + 4H+ + 2e- → Mn2+ + 2H O2

Anoxic Fe(III) Fe(OH)3(s) + H+ + e- → Fe2+ + H O; FeOOH 2 (s) + 3H+ + e- → Fe2+ + 2H O 2

Anoxic SO4 SO42- + 9H+ + 8e- → HS- + 4H O2

Anoxic CH4gen CO2(g) + 8H+ + 8e- → CH4(g) + 2H O2

1 For brevity, only those classifications relevant to this report are provided here; the full range in redox conditions and processes and their relevant water-quality classification criteria is available from 

Jurgens and others (2009).
84 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

redox conditions and (or) simultaneous but different redox 

conditions occurring in groundwater in close proximity to the 

well screens. 

Redox conditions and processes influence the occurrence and distribution of individual redox-sensitive species in 

groundwater in the DMCA and vicinity. The affected redoxsensitive species include dissolved oxygen, dissolved inorganic nitrogen compounds (nitrate-plus-nitrite and ammonianitrogen), total recoverable manganese and iron, and dissolved 

sulfur compounds (sulfide or sulfate). 

On the basis of concentrations of dissolved oxygen 

above the TEAP threshold (table 14, O2

 ≥ 0.50 mg/L), only 

shallow groundwater in the Magothy aquifer beneath WVS 

(fig. 50), and in the Magothy aquifer east of the DMCA property boundary (fig. 50, well CE Dd 193) are considered to be 

in an oxygen-bearing zone.

Table 15. Classification of redox categories and processes 

assigned on the basis of water-quality data obtained from 

groundwater and surface-water samples collected in the 

Pearce Creek Dredge Material Containment Area and vicinity, 

2010–11.—Continued

[USGS, U.S. Geological Survey; Redox process: O2, oxygen reduction; NO3, 

nitrate reduction; Mn(IV), manganese reduction; Fe(III), iron reduction; 

SO4, sulfate reduction; CH4gen, methanogenesis]

USGS local 

identifier

General redox 

category Redox process

Domestic wells

CE Dd 161 Anoxic Fe(III)

CE Dd 163 Mixed (oxic-anoxic) O2

-Mn(IV)

CE Dd 164 Mixed (oxic-anoxic) O2

-Mn(IV)

CE Dd 165 Mixed (oxic-anoxic) O2

-Fe(III)

CE Dd 166 Mixed (anoxic) NO3

-Fe(III)

CE Dd 168 Oxic O2

CE Dd 169 Anoxic Fe(III)

CE Dd 170 Anoxic Fe(III)

CE Dd 171 Mixed (oxic-anoxic) O2

-Fe(III)

CE Dd 172 Mixed (oxic-anoxic) O2

-Mn(IV)

CE Dd 174 Anoxic Fe(III)

CE Dd 176 Anoxic Fe(III)

CE Dd 177 Anoxic Fe(III)

CE Dd 178 Mixed (oxic-anoxic) O2

-Mn(IV)

CE Dd 179 Anoxic Fe(III)

Surface waters

Elk River at mouth 

near Crystal Beach, 

Md.

Oxic O2

Pearce Creek at 

Crystal Beach, Md.

Mixed (oxic-anoxic) O2-Mn(IV)

Table 15. Classification of redox categories and processes 

assigned on the basis of water-quality data obtained from 

groundwater and surface-water samples collected in the Pearce 

Creek Dredge Material Containment Area and vicinity, 2010–11.

[USGS, U.S. Geological Survey; Redox process: O2, oxygen reduction; NO3, 

nitrate reduction; Mn(IV), manganese reduction; Fe(III), iron reduction; 

SO4, sulfate reduction; CH4gen, methanogenesis]

USGS local 

identifier

General redox 

category Redox process

Observation wells

CE Dd 81 Anoxic Fe(III)

CE Dd 122 Anoxic Fe(III)

CE Dd 124 Anoxic Fe(III)

CE Dd 125 Anoxic Fe(III)

CE Dd 126 Anoxic Fe(III)

CE Dd 127 Anoxic Fe(III)

CE Dd 128 Anoxic Fe(III)

CE Dd 129 Anoxic Fe(III)

CE Dd 133 Anoxic Fe(III)

CE Dd 135 Anoxic CH4gen

CE Dd 136 Anoxic Fe(III)

CE Dd 137 Anoxic Fe(III)

CE Dd 138 Anoxic Fe(III)

CE Dd 139 Anoxic Fe(III)

CE Dd 140 Mixed (oxic-anoxic) O2

-Fe(III)

CE Dd 141 Anoxic Fe(III)

CE Dd 142 Anoxic Fe(III)

CE Dd 143 Mixed (anoxic) NO3

-Fe(III)

CE Dd 144 Anoxic Fe(III)

CE Dd 145 Anoxic Fe(III)

CE Dd 146 Anoxic Fe(III)

CE Dd 147 Anoxic Fe(III)

CE Dd 149 Anoxic Fe(III)

CE Dd 150 Anoxic Fe(III)

CE Dd 151 Anoxic Fe(III)

CE Dd 153 Anoxic Fe(III)

CE Dd 154 Anoxic Fe(III)

CE Dd 155 Mixed (oxic-anoxic) O2

-Fe(III)

CE Dd 156 Anoxic CH4gen

CE Dd 157 Anoxic Fe(III)

CE Dd 158 Anoxic Fe(III)

CE Dd 160 Anoxic Fe(III)

CE Dd 191 Anoxic Fe(III)

CE Dd 192 Anoxic Fe(III)

CE Dd 193 Mixed (oxic-anoxic) O2

-Fe(III)
Water Quality 85

75°59' 76°

39°26'

39°25'30"

8.8

13

4.3

Elk River Pearce Creek Lake

Crystal Beach

Pond Neck Road

West View Shores

Bay View Estates

EXPLANATION

Potentiometric surface contour in the Magothy aquifer—Shows altitude at which 

water would have stood in tightly cased wells, May 19–20, 2010. Dashed where approximately located. Contour interval 2 feet. Datum is North American Vertical Datum of 1988

Direction of groundwater flowLocally perched aquifer well—Number shows dissolved organic carbon 

concentration, in milligrams per liter (mg/L)

Magothy aquifer well—Number shows dissolved organic carbon 

concentration, in mg/L. <, less than; E, estimated

Surface-water site—Number shows dissolved organic carbon concentration, 

in mg/L

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

6

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

2

4

4

6

6

8

10

10

10

4.3

2.2

3.2

6.7

3.1

19

8.8

7.8

10 6.2

13

3.1

2.0

E 0.5

E 0.4

0.9 E 0.4

<0.6

2.0

E 0.5

3.2

7.9

6.16

11

<0.3

Figure 46. Concentrations of dissolved organic carbon in water-quality samples collected from selected surface waters and from selected wells completed in the perched water-bearing zone or Magothy aquifer in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11.
86 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area <0.3 2.0 11 4.5 <0.6 6.4 4.3 75°59' 76° 39°26' 39°25'30" 11 4.3

Elk River Pearce Creek Lake

Crystal Beach

Pond Neck Road

West View Shores

Bay View Estates

EXPLANATION

Potentiometric surface contour in the upper Patapsco aquifer, shallow 

water-bearing zone—Shows altitude at which water would have stood in tightly cased wells, May 19–20, 2010. Dashed where approximately located. Contour interval 2 feet. Datum is North American Vertical Datum of 1988

Direction of groundwater flow

Upper Patapsco aquifer well, shallow water-bearing zone—Number shows dissolved 

organic carbon concentration, in milligrams per liter (mg/L). <, less than; E, estimated

Surface-water site—Number shows dissolved organic carbon concentration, in mg/L

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

6

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

2

4

4

6

6

8

8

5.1

1.5

1.1

1.0

1.3

2.6

3.6

7.0

0.6

1.1

E 0.4

13

1.1

1.0

0.7

1.2

7.3

7.3 07

2.0 6.8

2.2

Figure 47. Concentrations of dissolved organic carbon in water-quality samples collected from selected surface waters and from selected wells completed in the upper Patapsco aquifer shallow water-bearing zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11.
Water Quality 87

Magothy aquifer

Fill - Matawan Formation

Upper Patapsco aquifer

shallow water-bearing zone

Upper Patapsco aquifer

deep water-bearing zone

Groundwater divide

Well

identifier

7.9

<0.3

<0.3

19

1.1

7.8

13

6.2

10

6.4

1.0

E 0.4

6.8

7.3

2.0

0.7

E 0.5

<0.6

E 0.4

2.2

<0.6

172

5025

-25-50-75

-100-125-150-175-200-225-250

0

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000

Distance, in feet

4,500 5,000 5,500 6,000 6,500 7,000 8,000 8,500 9,000 7,500

A

WEST

A'

EAST

193

192 191

157 158 124 139 122

151 81

163

168

165

164 171 142

128

178

160

Confining unit

Confining unit

Elk

River

Confining unit

Altitude, in feet above or below North American Vertical Datum of 1988 

VERTICAL EXAGGERATION x 20

Dissolved organic carbon concentration,  in milligrams per liter

—<, less than; 

 E, estimatedDirection of groundwater flowPrecipitation/recharge

EXPLANATION

1.1

Figure 48. Hydrogeologic section showing concentration of dissolved organic carbon in water-quality samples along line A–A’ and collected from selected surface 

waters and from selected wells completed in the perched water-bearing zone, Magothy aquifer, or upper Patapsco aquifer shallow or deep water-bearing zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11. (Location of line of section A–A’ is shown in figure 39.)
88 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

Figure 49. Predominant reduction-oxidation conditions and processes associated with selected surface waters and with selected wells completed in the perched water-bearing zone or Magothy aquifer in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11.

O2

127

75°59' 76°

39°26'

39°25'30"

Elk River Pearce Creek Lake

Crystal Beach

Pond Neck Road

West View Shores

Bay View Estates

EXPLANATION

Potentiometric surface contour in the Magothy aquifer—Shows altitude at which 

water would have stood in tightly cased wells, May 19–20, 2010. Dashed where approximately located. Contour interval 2 feet. Datum is North American Vertical Datum of 1988

Direction of groundwater flowPerched aquifer wellSurface-water siteMagothy aquifer well

Reduction-oxidation conditions and processes

Oxic, O2, oxygen present and being reduced 

Oxic and anoxic, O2-Mn, oxygen and manganese present and being reduced. 

O2-Fe, oxygen and iron present and being reduced

Anoxic, NO3-Fe, nitrate and iron present and being reduced. Fe, iron present 

and being reduced. CH4, NC methane generation (not confirmed ), and 

sulfate reduced 

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

6

2

6

4

8

10

10

10

8

6

4

2

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

O2-Fe

O2 O2-Mn

O2-Mn

O2-Fe

O2-Fe O2-Fe

Fe

Fe

Fe

Fe

Fe

Fe

Fe

Fe

CH4, NC Fe

Fe

Fe

Fe

Fe

O2 O2-Mn

O2-Mn NO3-Fe 3-Fe

O2-Fe

O2-Mn
Water Quality 89

Concentrations of nitrate-plus-nitrite nitrogen above the 

TEAP threshold (table 14, NO3

–

 ≥ 0.5 mg/L) only occur in 

shallow groundwater in the Magothy aquifer beneath part of 

WVS and east of the DMCA property boundary (fig. 51). Elsewhere nitrate-plus-nitrite nitrogen only occurs at low concentrations (approximately 0.15 mg/L or less). The pattern in the 

occurrence of nitrate plus nitrite nitrogen at elevated concentrations is consistent with elevated concentrations of dissolved 

oxygen described above. The occurrence of nitrate plus nitrite 

nitrogen is also similar to other groundwater samples from 

residential areas elsewhere on the Delmarva Peninsula, where 

oxic shallow groundwater has higher concentrations of nitrate 

plus nitrite nitrogen than anoxic groundwater (table 12). 

The major dissolved inorganic form of nitrogen in 

groundwater under reduced conditions is ammonia nitrogen 

(fig. 52). The highest concentrations in ammonia nitrogen 

in groundwater under reduced conditions occur beneath the 

DMCA, or within or near the DMCA property boundary, in the 

perched groundwater zone and Magothy aquifer (figs. 52 and 

53). On the basis of patterns in groundwater flow, groundwater 

in the Magothy aquifer with elevated concentrations of ammonia nitrogen travels south at least to Pond Neck Road and west 

from the DMCA (fig. 52) before flowing laterally and vertically downward into the upper Patapsco shallow water-bearing 

zone beneath WVS (fig. 54).

Concentrations of dissolved manganese are less than the 

TEAP threshold (table 14, Mn2+, 0.05 mg/L, or 50 μg/L) in 

groundwater at one well in the Magothy aquifer beneath WVS 

(fig. 55). The occurrence of moderately elevated manganese 

concentrations just below the oxygen-bearing zone in WVS 

could reflect solid-phase Mn(IV) reduction and mobilization 

in conjunction with groundwater moving vertically downward 

from this oxygen-bearing zone. Manganese was abundant and 

well above the TEAP threshold throughout the remainder of 

the Magothy aquifer (fig. 55). High manganese concentrations in this aquifer occurred beneath the southern and western 

parts of the DMCA. To the south, the highest concentrations 

occurred along Pond Neck Road and reflected groundwater 

flow from the DMCA to this aquifer. Given this flow path 

occurs in entirely anoxic iron-reducing conditions, the high 

manganese concentrations along Pond Neck Road could 

reflect solid-phase Mn(IV) reduction and mobilization not 

only in the DMCA, but throughout the anoxic aquifer (fig. 56).

Chapelle and others (2008) note that anoxic groundwater 

systems can be dominated by iron- or sulfate-reducing conditions, or both. Groundwater throughout most of the DMCA 

and vicinity is under redox conditions where iron likely is 

being reduced. Concentrations of iron below < 0.01 mg/L only 

are approached in oxygen-bearing shallow groundwater in the 

Magothy aquifer beneath WVS (fig. 57). Iron concentrations 

are considerably above the TEAP threshold in the perched 

water-bearing zone and the Magothy aquifer, as well as the 

upper Patapsco aquifer shallow water-bearing zone (figs. 58 

and 59). As in the case of manganese, high concentrations 

of iron generally correspond to groundwater flow within and 

from the DMCA. Concentrations of iron also tend to increase 

with depth and distance along the groundwater flow paths 

from the DMCA (for example, figure 57), in what are mainly 

anoxic iron-reducing conditions. The highest concentrations 

of iron correspond to areas where groundwater flow from the 

DMCA potentially could be in contact with oxygen-bearing 

or mixed oxic-anoxic groundwater from other source areas—

for example, to the west of the DMCA in the upper Patapsco 

aquifer beneath WVS or to the east of the DMCA property 

boundary (fig. 59). The high concentrations of iron also 

correspond to elevated levels of DOC found in the samples. 

These elevated concentrations of iron are also considerably 

greater than concentrations of iron in groundwater elsewhere 

in the vicinity of the study area that are considered not overly 

affected by human activities (table 13).

Groundwater unaffected by flow from the DMCA has 

concentrations of iron higher than the TEAP threshold of 

0.01 mg/L. Native sediments throughout most of the area have 

high iron concentrations, which likely reflect iron’s abundance 

in native aquifer sediments as well as in the DMCA fill (see 

Chemical Composition of Sediments, this report). Iron is 

more abundant than manganese in DMCA fill-Matawan sediments and other sediments in the study area (table 9). The 

relative abundance of iron and manganese in the sediments, 

iron being greater than manganese, is likely related to the 

relative abundance of those elements in the Earth’s outer crust: 

this could explain why iron concentrations generally exceed 

manganese concentrations in groundwater in the study area 

and vicinity that are not overly affected by human activities 

(table 13).

As noted in the previous section (see Total Dissolved 

Solids and Major Ions, this report) the proportion of sulfate 

within a particular sample was an important factor for distinguishing groundwater flow patterns. Dredge material and 

buried wetland sediments were likely the largest source of 

sulfur within the study area. The addition of oxic Elk River 

water may have oxidized the ferrous sulfide minerals to form 

sulfate, which is mobile. The sulfate can then be reduced, 

under the proper conditions, to hydrogen sulfide. However, 

sulfate generally is not undergoing appreciable reduction in 

this groundwater flow system. The iron-to-hydrogen sulfide 

mass ratios all exceeded 10, indicating the flow system was 

predominately iron-reducing. Except for groundwater associated with two wells within the DMCA property boundary, 

concentrations of sulfate occurred at measurable (exceeding 

approximately 0.2 mg/L) to extremely elevated (thousands of 

milligrams per liter) concentrations throughout the Magothy 

aquifer (fig. 60) and the upper Patapsco aquifer shallow waterbearing zone (fig. 61).

Groundwater associated with two wells within the DMCA 

property boundary (fig. 6, wells CE Dd 156 and CE Dd 135) 

and screened in the Magothy aquifer had low levels of dissolved oxygen (less than 0.5 mg/L), low to moderate levels 

of levels of ammonia-nitrogen (less than 4 mg/L), moderately 

elevated levels of dissolved iron (up to hundreds of milligrams 

per liter), low levels of sulfide (0.015 μg/L), and sulfate concentrations reported as less than the LRL (19 mg/L). On the 
90 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area Magothy aquifer Fill - Matawan Formation Upper Patapsco aquifer shallow water-bearing zone Upper Patapsco aquifer deep water-bearing zone 172 Groundwater divide Well identifier 0.29 0.33 0.40 0.42 0.32 0.33 <0.25 0.31 4.02 8.03 0.53 <0.25 0.29 0.30 0.797.22 3.10 0.39 14.22 4.43 3.39 5025 -25 -50 -75 -100 -125 -150 -175 -200 -225 -250

0

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000

Distance, in feet

4,500 5,000 5,500 6,000 6,500 7,000 8,000 8,500 9,000 7,500

A

WEST

A'

EAST

193

192 191

157 158 124 139 122

151 81

163

168

165

164 171 142

128

178 160

Confining unit

Confining unit

Elk

River

Confining unit

Altitude, in feet above or below North American Vertical Datum of 1988

VERTICAL EXAGGERATION x 20

Dissolved oxygen concentration, in  milligrams per liter

—<, less than

Direction of groundwater flowPrecipitation/recharge

EXPLANATION

4.43

Figure 50. Hydrogeologic section showing concentrations of dissolved oxygen in water-quality samples along line A–A’ and collected from selected surface waters 

and from selected wells completed in the perched water-bearing zone, Magothy aquifer, or upper Patapsco aquifer shallow or deep water-bearing zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11. (Location of line of section A–A’ is shown in figure 39.)
Water Quality 91

Magothy aquifer

Fill - Matawan Formation

Upper Patapsco aquifer

shallow water-bearing zone

Upper Patapsco aquifer

deep water-bearing zone

172

Groundwater divide

Well

identifier

0.12

0.02

2.04

0.11

0.09

0.15

E 0.03

<0.04

0.15

2.36

3.44

<0.04

0.14

0.15

E 0.03

5.61

1.88

0.05

1.44

2.37

1.32

5025

-25-50-75

-100-125-150-175-200-225-250

0

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000

Distance, in feet

4,500 5,000 5,500 6,000 6,500 7,000 8,000 8,500 9,000 7,500

A

WEST

A'

EAST

193

192 191

157 158 124 139 122

151 81

163

168

165

164 171 142

128

178 160

Confining unit

Confining unit

Elk

River

Confining unit

Altitude, in feet above or below North American Vertical Datum of 1988

VERTICAL EXAGGERATION x 20

EXPLANATION

0.02 Dissolved nitrate plus nitrite nitrogen concen-

 tration, in milligrams per liter (mg/L)—<, less  than; E, estimated. Federal Maximum  Contaminant Level for drinking water is  10 mg/LDirection of groundwater flowPrecipitation/recharge

Figure 51. Hydrogeologic section showing the concentrations of dissolved nitrate plus nitrite nitrogen in water-quality samples along line A–A’ and collected from 

selected surface waters and selected wells completed in the perched water-bearing zone, Magothy aquifer, or upper Patapsco aquifer shallow or deep waterbearing zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11. (Location of line of section A–A’ is shown in figure 39.) 
92 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area 127 75°59' 76° 39°26' 39°25'30"

Elk River Pearce Creek Lake

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

Crystal Beach

Pond Neck Road

West View Shores

Bay View Estates

EXPLANATION

Potentiometric surface contour in the Magothy aquifer—Shows 

altitude at which water would have stood in tightly cased wells, May 19–20, 2010. Dashed where approximately located. Contour interval 2 feet. Datum is North American Vertical Datum of 1988

Direction of groundwater flowLocally perched aquifer well—Number shows dissolved ammonia 

nitrogen concentration, in milligrams per liter (mg/L). Federal Health Advisory Level for drinking water is 24.7 mg/L

Magothy aquifer well—Number shows dissolved ammonia nitrogen 

concentration, in mg/L. Federal Health Advisory Level for drinking water is 24.7 mg/L. <, less than

Surface-water site —Number shows dissolved ammonia nitrogen 

concentration, in mg/L. Federal Health Advisory Level for drinking water is 24.7 mg/L. <, less than

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

6

2 4

6

8

10

10

8

6

0.25

<0.02 <0.02

<0.02

<0.01

21.10

3.50

7.98

3.87

3.87

9.13

7.27

5.76

5.76

1.83

0.49

2.64

0.03

3.19

4.22

9.36

0.52

0.10

0.10

<0.02

0.08

1.20

Figure 52. Concentrations of dissolved ammonia nitrogen in water-quality samples collected from selected surface waters and from selected wells completed in the perched water-bearing zone or Magothy aquifer in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11.
Water Quality 93 Figure 53. Concentrations of dissolved ammonia nitrogen in water-quality samples collected from selected surface waters and from selected wells completed in the upper Patapsco aquifer shallow water-bearing zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11.

127

75°59' 76°

39°26'

39°25'30"

Elk River Pearce Creek Lake

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

Crystal Beach

Pond Neck Road

West View Shores

Bay View Estates

EXPLANATION

Potentiometric surface contour in the upper Patapsco aquifer, shallow 

water-bearing zone—Shows altitude at which water would have stood in tightly cased wells, May 19–20, 2010. Dashed where approximately located. Contour interval 2 feet. Datum is North American Vertical Datum of 1988

Direction of groundwater flow

Upper Patapsco aquifer well, shallow water-bearing zone–—Number shows dissolved 

ammonia nitrogen concentration, in milligrams per liter (mg/L). Federal Health Advisory Level for drinking water is 24.7 mg/L. <, less than

Surface-water site–—Number shows dissolved ammonia nitrogen concentration, in 

mg/L. Federal Health Advisory Level for drinking water is 24.7 mg/L. <, less than

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

6

0.10

2

4

6

8 8

6

4

1.01 0.06

0.17

1.25

2.13 1.11

0.30

1.01 0.06

0.17

1.25

3.43

1.29

0.14

0.10

6.90 0.14

0.06

0.04

0.15

0.08

0.08

2.13 1.11

0.30

3.75

<0.01
94 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment AreaFigure 54. Hydrogeologic section showing concentrations of dissolved ammonia nitrogen in water-quality samples along line A–A’ and collected from selected 

surface waters and from selected wells completed in the perched water-bearing zone, Magothy aquifer, or upper Patapsco aquifer shallow or deep water-bearing zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11. (Location of line of section A–A’ is shown in figure 39.)

Magothy aquifer

Fill - Matawan Formation

Upper Patapsco aquifer

shallow water-bearing zone

Upper Patapsco aquifer

deep water-bearing zone

Groundwater divide

Well

identifier

2.64

0.04

5.76

0.14

6.90

9.13 7.98

3.75

0.07

<0.020.30

3.16

5.69

3.33

0.17

<0.02

<0.02

3.87

<0.01

0.03

0.08

5025

-25-50-75

-100-125-150-175-200-225-250

0

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000

Distance, in feet

4,500 5,000 5,500 6,000 6,500 7,000 8,000 8,500 9,000 7,500

A

WEST

A'

EAST

193

192 191

157 158 124139122

151 81

163

168

165

164 171 142

128

178 160

Confining unit

Confining unit

Elk

River

Confining unit

Altitude, in feet above or below North American Vertical Datum of 1988

VERTICAL EXAGGERATION x 20

172

Dissolved ammonia nitrogen concentration,  in milligrams per liter (mg/L)

—<, less than. 

 Federal Health Advisory Level for drinking  water is 24.7 mg/LDirection of groundwater flowPrecipitation/recharge

EXPLANATION

0.04
Water Quality 95 Figure 55. Hydrogeologic section showing concentrations of dissolved manganese in water-quality samples along line A–A’ and collected from selected surface waters and from selected wells completed in the perched water-bearing zone, Magothy aquifer, or upper Patapsco aquifer shallow or deep water-bearing zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11. (Location of line of section A–A’ is shown in figure 39.) 

Magothy aquifer

Fill - Matawan Formation

Upper Patapsco aquifer

shallow water-bearing zone

Upper Patapsco aquifer

deep water-bearing zone

Groundwater divide

Well

identifier

185

0.22

28.8

0.60

200

36.4

43.4

110

0.22

12.2

0.95

78.7

140

27.9

3.30

0.15

0.47

31.9

0.01

0.81

1.71

172

5025

-25-50-75

-100-125-150-175-200-225-250

0

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000

Distance, in feet

4,500 5,000 5,500 6,000 6,500 7,000 8,000 8,500 9,000 7,500

A

WEST

A'

EAST

193

192 191

157 158 124139122

151 81

163

168

165

164 171 142

128

172

160

Confining unit

Confining unit

Elk

River

Confining unit

Altitude, in feet above or below North American Vertical Datum of 1988

VERTICAL EXAGGERATION x 20

Dissolved manganese concentration, in  milligrams per liter (mg/L)

—Red number 

 indicates that the Federal Health Advisory  Level for drinking water (0.30 mg/L) was  exceeded. Federal Secondary Drinking  Water Regulation is 0.05 mg/LDirection of groundwater flowPrecipitation/recharge

EXPLANATION

0.22
96 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

Figure 56. Concentrations of dissolved manganese in water-quality samples collected from selected surface waters and from selected wells completed in the perched water-bearing zone or Magothy aquifer in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11.

127

141

75°59' 76°

39°26'

39°25'30"

0.22

31.985.0

0.820.01

Elk River Pearce Creek Lake

Crystal Beach

Pond Neck Road

West View Shores

Bay View Estates

EXPLANATION

Potentiometric surface contour in the Magothy aquifer—Shows altitude at which water would 

have stood in tightly cased wells, May 19–20, 2010. Dashed where approximately located. Contour interval 2 feet. Datum is North American Vertical Datum of 1988

Direction of groundwater flowLocally perched aquifer well—Number shows dissolved manganese concentration, in 

milligrams per liter (mg/L). Exceeds Federal Health Advisory Level for public drinking water supply (0.30 mg/L)

Magothy aquifer well—Number shows dissolved manganese concentration, in mg/L. Exceeds 

Federal Health Advisory Level for public drinking water supply (0.30 mg/L)

Magothy aquifer well—Number shows dissolved manganese concentration, in mg/L. 

Does not exceed Federal Health Advisory Level for public drinking water supply (0.30 mg/L)

Surface-water site—Number shows dissolved manganese concentration, in mg/L. 

Exceeds Federal Health Advisory Level for public drinking water supply (0.30 mg/L)

Surface-water site—Number shows total dissolved manganese concentration, in 

mg/L. Does not exceed Federal Health Advisory Level for public drinking water supply (0.30 mg/L)

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

6

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

2

4

6

6

8

8

10

10

0.01

0.16

0.15

0.05

0.22

45.6

38.5

31.9

43.4 36.4

85.0

28.8

0.47

3.09

185

0.81

152

177

66.7

9.80

0.82

0.22

13.8

1.71
Water Quality 97 Figure 57. Hydrogeologic section showing concentrations of dissolved iron in water-quality samples along line A–A’ and collected from selected surface waters and from selected wells completed in the perched water-bearing zone, Magothy aquifer, or upper Patapsco aquifer shallow or deep water-bearing zone in the Pearce Creek Dredge Material Containment Area and vicinity, Cecil County, Maryland, 2010–11. (Location of line of section A–A’ is shown in figure 39.) 

Magothy aquifer

Fill - Matawan Formation

Upper Patapsco aquifer

shallow water-bearing zone

Upper Patapsco aquifer

deep water-bearing zone

172

Groundwater divide

Well

identifier

326

12.7

186

82.3

537

116 41.2

537

E0.02

<0.03

13.0

353

429

36.8

0.02

<0.03

95.4

0.03

1.77

8.48

<0.03

5025

-25-50-75

-100-125-150-175-200-225-250

0

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000

Distance, in feet

4,500 5,000 5,500 6,000 6,500 7,000 8,000 8,500 9,000 7,500

A

WEST

A'

EAST

193

192 191

157 158 124 139122

151 81

163

168

165

164 171 142 178

128160

Confining unit

Confining unit

Elk

River

Confining unit

Altitude, in feet above or below North American Vertical Datum of 1988 

VERTICAL EXAGGERATION x 20

Concentration of dissolved iron, in milligrams  per liter (mg/L)—<, less than; E, estimated. 

 Red number indicates value exceeds Federal  Secondary Drinking Water Regulation  (0.30 mg/L)Direction of groundwater flowPrecipitation/recharge

EXPLANATION

0.02
98 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment AreaFigure 58. Concentrations of dissolved iron in water-quality samples collected from selected surface waters and from selected wells completed 

in the perched water-bearing zone or Magothy aquifer in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11.

127

141

75°59' 76°

39°26'

39°25'30"

<0.03

95.4

190

0.06

Elk River Pearce Creek Lake

Crystal Beach

Pond Neck Road

West View Shores

Bay View Estates

EXPLANATION

Potentiometric surface contour in the Magothy aquifer—Shows altitude at which water would 

have stood in tightly cased wells, May 19–20, 2010. Dashed where approximately located. Contour interval 2 feet. Datum is North American Vertical Datum of 1988

Direction of groundwater flowLocally perched aquifer well—Number shows dissolved iron concentration, in milligrams 

per liter (mg/L). Exceeds Federal Health Advisory Level for public drinking water supply (0.30 mg/L)

Magothy aquifer well—Number shows dissolved iron concentration, in mg/L. Exceeds 

Federal Health Advisory Level for public drinking water supply (0.30 mg/L)

Magothy aquifer well—Number shows dissolved iron concentration, in mg/L. 

Does not exceed Federal Health Advisory Level for public drinking water supply (0.30 mg/L). <, less than

Surface-water site—Number shows dissolved iron concentration, in mg/L. Does not 

exceed Federal Health Advisory Level for public drinking water supply (0.30 mg/L)

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

6

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

2

2

4

4

6

6

8

8

10

10

0.03

1.47

6.29

<0.03

<0.03

<0.03

<0.03

<0.03

<0.03

41.2

34.3

118

25.5

0.06

51.4 68.2

326

1.77

468

656

186

190

130

116

95.4

8.48

6.29
Water Quality 99 Figure 59. Concentrations of dissolved iron in water-quality samples collected from selected surface waters and from selected wells completed in the upper Patapsco aquifer shallow water-bearing zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11.

127

141

75°59' 76°

39°26'

39°25'30"

0.02

381

0.06

Elk River Pearce Creek Lake

Crystal Beach

Pond Neck Road

West View Shores

Bay View Estates

EXPLANATION

Potentiometric surface contour in the upper Patapsco aquifer, shallow water-bearing 

zone— Shows altitude at which water would have stood in tightly cased wells, May 19–20, 2010. Dashed where approximately located. Contour interval 2 feet. Datum is North American Vertical Datum of 1988

Direction of groundwater flowUpper Patapsco aquifer well, shallow water-bearing zone—Number shows dissolved 

iron concentration, in milligrams per liter (mg/L). Exceeds Federal Health Advisory Level for public drinking water supply (0.30 mg/L)

Upper Patapsco aquifer well, shallow water-bearing zone—Number shows 

dissolved iron concentration, in mg/L. Does not exceed Federal Health Advisory Level for public drinking water supply (0.30 mg/L). E, estimated

Surface-water site—Number shows dissolved iron concentration, in mg/L. Does 

not exceed Federal Health Advisory Level for public drinking water supply (0.30 mg/L)

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

6

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

276

0.03

26.4

18.5

0.06

20.2

82.3

196

381 80.7

12.7

8.59 624

537

20.6

429

19.3

67.2

56.4

E 0.02

537

0.02

20.6

429

19.3

67.256.4

756.6

71.8

56.6

E 0.02

0.02

36.8 353

2

4

4

6

6

8

8
100 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area Figure 60. Concentrations of dissolved sulfate in water-quality samples collected from selected surface waters and from selected wells completed in the perched water-bearing zone or Magothy aquifer in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, 

Maryland, 2010-11.

127

141

75°59' 76°

39°26'

39°25'30"

17

510 27

Elk River Pearce Creek Lake

Crystal Beach

Pond Neck Road

West View Shores

Bay View Estates

EXPLANATION

Potentiometric surface contour in the Magothy aquifer— Shows altitude at which water 

would have stood in tightly cased wells, May 19–20, 2010. Dashed where approximately located. Contour interval 2 feet. Datum is North American Vertical Datum of 1988

Direction of groundwater flowLocally perched aquifer well—Number shows dissolved sulfate concentration, in milligrams 

per liter (mg/L). Exceeds Federal Secondary Drinking Water Regulation (250 mg/L)

Magothy aquifer well—Number shows dissolved sulfate concentration, in mg/L. Exceeds 

Federal Secondary Drinking Water Regulation (250 mg/L). E, estimated

Magothy aquifer well—Number shows dissolved sulfate concentration, in mg/L. Does not 

exceed Federal Secondary Drinking Water Regulation (250 mg/L). <, less than

Surface-water site—Number shows dissolved sulfate concentration, in mg/L. Does not 

exceed Federal Secondary Drinking Water Regulation (250 mg/L)

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

6

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

2

4

6

6

8

8

10

10

170

27

10

240

20

14

17 45

E 1,380

980

600 790

600

260

2,930

3,430

3,230

<0.09

2.5

E 1,190

E 370

E 1,530

510 E 900

45
Water Quality 101 Figure 61. Concentrations of dissolved sulfate in water-quality samples collected from selected surface waters and from selected wells completed in the upper Patapsco aquifer shallow water-bearing zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11.

127

141

75°59' 76°

39°26'

39°25'30"

82.3

E 800

27

Elk River Pearce Creek Lake

Crystal Beach

Pond Neck Road

West View Shores

Bay View Estates

EXPLANATION

Potentiometric surface contour in the upper Patapsco aquifer, shallow water-bearing 

zone— Shows altitude at which water would have stood in tightly cased wells, May 19–20, 2010. Dashed where approximately located. Contour interval 2 feet. Datum is North American Vertical Datum of 1988

Direction of groundwater flowUpper Patapsco aquifer well, shallow water-bearing zone—Number shows dissolved 

sulfate concentration, in milligrams per liter (mg/L). Exceeds Federal Secondary Drinking Water Regulation (250 mg/L). E, estimated

Upper Patapsco aquifer well, shallow water-bearing zone—Number shows 

dissolved sulfate concentration, in mg/L. Does not exceed Federal Secondary Drinking Water Regulation (250 mg/L). E, estimated

Surface-water site—Number shows dissolved sulfate concentration, in mg/L. 

Does not exceed Federal Secondary Drinking Water Regulation (250 mg/L)

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

6

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

2

4

4

6

6

8

8

170

2,150

340

2,680

0.02

19.3 67.2

56.4

2,430

E 710

E 1,270

E 340

2,150

340

2,680

0.02

19.3 67.2

26.4

82.3

8.59

12.7

700

E 800

20.2

18.5

27

56.4 E 340

E 2,640 E 3,730

E 1,920

E 2,790 E 1,270
102 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

basis of the TEAP threshold criteria (table 14), groundwater at 

both wells was classified as anoxic and the predominant reduction process as methane generation (table 15). Since dissolved 

methane (gas) was not determined, this classification could not 

be confirmed. But both wells contain unusually low levels of 

TDS—less than 250 mg/L (appendix B, table B3). Groundwater from both wells exhibit water-quality conditions that would 

indicate conditions are anoxic and have reducing conditions 

that indicate at least sulfate is being reduced.

Redox conditions in the upper Patapsco aquifer shallow water-bearing zone beneath the DMCA and within or 

just beyond the DMCA property boundary are similar to the 

conditions in the overlying Magothy aquifer. Except for well 

CE Dd 156, groundwater conditions generally are anoxic, with 

Fe(III) reduction being the dominant process (fig. 62, Fe(III)). 

Groundwater associated with well CE Dd 156 also is anoxic, 

but it is in a severely reduced state and possibly generating 

methane (fig. 62, CH4(g), not confirmed). Beneath WVS, 

water in the upper Patapsco shallow water-bearing zone exhibits reducing conditions, which generally are almost as severe 

as conditions associated with this water-bearing zone within 

and near the DMCA (fig. 62, Fe(III) dominates), and more 

severe than the redox conditions in the overlying Magothy 

aquifer (fig. 49), with anoxic (Fe(III)) or mixed anoxic 

(NO3–Fe) conditions dominating (fig. 62).

In the upper Patapsco aquifer shallow water-bearing zone, 

elevated manganese concentrations occurred above the TEAP 

threshold in the southern and western parts of the DMCA and 

its vicinity (fig. 63). In the south, elevated manganese concentrations occurred beneath the DMCA, and beyond along Pond 

Neck Road. The elevated concentrations of manganese along 

Pond Neck Road correspond to flow initially from the 

DMCA and into the Magothy aquifer, which eventually 

leaked through the confining layer into the upper Patapsco 

aquifer shallow water-bearing zone (fig. 42). In the west, 

the pattern and process is similar, but rather than leakage, 

the confining layer between the aquifers is absent (fig. 42). 

Groundwater in the Magothy aquifer beneath the DMCA 

contained elevated manganese concentrations above the TEAP 

threshold and the concentration of manganese increased along 

the western flow path from the DMCA groundwater divide to 

the base of the upper Patapsco aquifer shallow water-bearing 

zone. This increase in manganese could reflect solid-phase 

Mn(IV) reduction and mobilization not only in the DMCA, 

but also along the groundwater flow path, and particularly at 

the base of the upper Patapsco aquifer shallow water-bearing 

zone. 

In the upper Patapsco aquifer deep water-bearing zone, 

groundwater reflects mixed oxic-anoxic conditions (fig. 64, 

O2

–Fe(III), wells CE Dd 155 and CE Dd 171) and anoxic 

conditions (fig. 64, Fe(III)). In this zone, however, the mixed 

oxic-anoxic conditions reflect low concentrations of dissolved 

oxygen, 0.55 and 0.53 mg/L at wells CE Dd 155 and CE Dd 

171, respectively, which are just above the 0.50 mg/L TEAP 

threshold that identifies oxic waters (table 14). 

In the upper Patapsco aquifer deep water-bearing zone, 

and except for one well (CE Dd 170, Mn2+, 1.17 mg/L), concentrations of manganese range from approximately 0.07 to 

0.13 mg/L (appendix B, table B3). There likely is little solidphase reduction and mobilization of Mn(IV) in this aquifer 

despite the anoxic conditions. The low manganese concentrations could reflect the lack of availability of solid-phase 

Mn(IV) in this aquifer (see below).

The upper Patapsco aquifer deep water-bearing zone 

had low sulfate concentrations (appendix B, table B3, range 

from 8 to 22 mg/L), when compared to other parts of the 

study area. Elevated concentrations of sulfate, at levels of 

hundreds to thousands of milligrams per liter, mainly occurred 

in anoxic groundwater in the DMCA, or were associated with 

groundwater flow from the DMCA (fig. 65). The elevated 

concentrations of sulfate associated with groundwater flow 

within and from the DMCA appreciably exceeded concentrations of sulfate in groundwater associated with either aquifer 

within (figs. 60, 61, and 65) or near the study area where that 

groundwater does not appear to be overly affected by human 

activities (table 13).

The different patterns observed in t he dominant redox 

categories and predominant reduction processes can be related 

to the quality of groundwater and, in particular, concentrations 

of TDS in groundwater in the study area, as well as land use, 

through patterns in groundwater flow. To illustrate, groundwater flow and the redox conditions associated with that flow 

from DMCA recharge into the Magothy aquifer to either the 

east or west of the groundwater divide along A–A' are anoxic; 

Fe(III) reduction is the dominant process (fig. 66). This anoxic 

groundwater also contains highly elevated concentrations of 

TDS (fig. 41). However, to the east and beyond the DMCA 

property boundary, less-severe mixed oxic-anoxic conditions occur (fig. 66, O2

–Fe(III), well CE Dd 193). Although 

the sources of the water sampled in this area are not entirely 

known, they are unlikely to include recharge from the DMCA, 

as the concentration of TDS associated with this well more 

aptly reflects groundwater that has not been overly affected by 

any human activities or land use (fig. 41; table 12).

Along the western end of the DMCA property boundary 

and A–A′ (fig. 66), the pattern in redox conditions and processes also appears related to the source of the groundwater 

and previously described patterns in groundwater flow and 

TDS (fig. 41). The most severe reducing condition—that of 

Fe(III) reduction—corresponds to groundwater from DMCA 

recharge to the Magothy aquifer that flows beneath the western half of the DMCA. The reducing conditions then occur 

farther westward and vertically downward to the base of the 

upper Patapsco aquifer shallow water-bearing zone. Finally, 

the reducing conditions are found farther along the flow path, 

to the west, or along the flow path that goes upwards or discharges along the western end of WVS or the Elk River 

(fig. 66). This flow also contains the highest concentrations of 

TDS in either aquifer in this area (fig. 41). However, groundwater at shallow depths beneath the WVS community is under 

less severe and often mixed oxic-anoxic conditions (fig. 66, 
Water Quality 103 Figure 62. Predominant reduction-oxidation conditions and processes associated with selected surface waters and with selected wells completed in the upper Patapsco aquifer shallow water-bearing zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11.

127

141

75°59' 76°

39°26'

39°25'30"

Elk River Pearce Creek Lake

Crystal Beach

Pond Neck Road

West View Shores

Bay View Estates

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

2

4

4

6

6

8

8

O2

Fe

Fe

Fe

Fe Fe

FeFe Fe

Fe

NO3-Fe

O2-Mn

O2-Mn

Fe

Fe

Fe

FeFe Fe

Fe Fe

Fe

Fe

Fe

Fe

Fe

Fe

Fe

Fe

Fe

NO3-Fe

CH4, NC

O2-Mn

O2-Mn

O2-Mn

Potentiometric surface contour in the upper Patapsco aquifer, shallow water-bearing 

zone— Shows altitude at which water would have stood in tightly cased wells, May 19–20, 2010. Dashed where approximately located. Contour interval 2 feet. Datum is North American Vertical Datum of 1988

Direction of groundwater flowUpper Patapsco aquifer well, shallow water-bearing zoneSurface-water site

Reduction-oxidation conditions and processes

Oxic, O2, oxygen present and being reduced 

Oxic and anoxic, O2-Mn, oxygen and manganese present and being reduced. 

O2-Fe, oxygen and iron present and being reduced

Anoxic, NO3-Fe, nitrate and iron present and being reduced. Fe, iron present 

and being reduced. CH4, NC methane generation (not confirmed ), and 

sulfate reduced 

6

EXPLANATION
104 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment AreaFigure 63. Concentrations of dissolved manganese in water-quality samples collected from selected surface waters and from selected wells completed 

in the upper Patapsco aquifer shallow water-bearing zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11.

127

141

75°59' 76°

39°26'

39°25'30"

Elk River Pearce Creek Lake

Crystal Beach

Pond Neck Road

West View Shores

Bay View Estates

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

2

4

4

6 6

8

8

0.01

0.01

19.4 136

0.94

140

3.30

27.9 78.7

1.07

2.73

12.2

12.3

81.2

19.4

0.94

140

3.30

2.73

12.2

12.3

81.2

0.18

0.18

222

200

200

0.35

0.60

0.12

0.22

10.4

70.4

17.5

0.12

0.82

0.82

110

EXPLANATION

Potentiometric surface contour in the upper Patapsco aquifer, shallow water-bearing 

zone— Shows altitude at which water would have stood in tightly cased wells, May 19–20, 2010. Dashed where approximately located. Contour interval 2 feet. Datum is North American Vertical Datum of 1988

Direction of groundwater flowUpper Patapsco aquifer well, shallow water-bearing zone—Number shows dissolved 

manganese concentration, in milligrams per liter (mg/L). Exceeds Federal Health Advisory Level for public drinking water supply (0.30 mg/L)

Upper Patapsco aquifer well, shallow water-bearing zone—Number shows dissolved 

manganese concentration, in mg/L. Does not exceed Federal Health Advisory Level for public drinking water supply (0.30 mg/L)

Surface-water site—Number shows dissolved manganese concentration, in mg/L. 

Exceed Federal Health Advisory Level for public drinking water supply (0.30 mg/L)

Surface-water site—Number shows dissolved manganese concentration, in mg/L. 

Does not exceed Federal Health Advisory Level for public drinking water supply (0.30 mg/L)

6
Water Quality 105 Figure 64. Predominant reduction-oxidation conditions and processes associated with selected surface waters and with selected wells completed in the upper Patapsco aquifer deep water-bearing zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11.

127

75°59' 76°

39°26'

39°25'30"

O2-Mn

O2-Fe

O2-Fe

Fe Fe

Fe

Fe

Fe

Elk River Pearce Creek Lake

Crystal Beach

Pond Neck Road

West View Shores

Bay View Estates

EXPLANATION

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

6

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

2

4

6

O2

Potentiometric surface contour in the upper Patapsco aquifer, deep water-bearing 

zone— Shows altitude at which water would have stood in tightly cased wells, May 19–20, 2010. Dashed where approximately located. Contour interval 2 feet. Datum is North American Vertical Datum of 1988

Direction of groundwater flowUpper Patapsco aquifer well, deep water-bearing zoneSurface-water site

Reduction-oxidation conditions and processes

Oxic, O2, oxygen present and being reduced 

Oxic and anoxic, O2-Fe, oxygen and iron present and being reduced, 

O2-Mn, oxygen and manganese present and being reduced

Anoxic, Fe, iron present and being reduced
106 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment AreaFigure 65. Hydrogeologic section showing concentrations of dissolved sulfate in water-quality samples along line A–A’ and collected from selected surface waters and from selected wells completed in the perched water-bearing zone, Magothy aquifer, or upper Patapsco aquifer shallow or deep water-bearing zone in the Pearce 

Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11. (Location of line of section A–A’ is shown in figure 39.)

Magothy aquifer

Fill - Matawan Formation

Upper Patapsco aquifer

shallow water-bearing zone

Upper Patapsco aquifer

deep water-bearing zone

172

2,930

14

790

220

E 3,730

600

2.5

E 900

E 2,640

250

17

18

2,430

2,680

E 710

150

20

14

170

45

510

Groundwater divide

Well

identifier

5025

-25-50-75

-100-125-150-175-200-225-250

0

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000

Distance, in feet

4,500 5,000 5,500 6,000 6,500 7,000 8,000 8,500 9,000 7,500

A

WEST

A'

EAST

193

192 191

157 158 124 139 122

151 81

163

168

165

164 171 142

128

178 160

Confining unit

Confining unit

Elk

River

Confining unit

Altitude, in feet above or below North American Vertical Datum of 1988 

VERTICAL EXAGGERATION x 20

Dissolved sulfate concentration, in milligrams  per liter (mg/L)

—E, estimated. Red number 

 indicates value exceeds Federal Secondary  Drinking Water Regulation (250 mg/L)Direction of groundwater flowPrecipitation/recharge

EXPLANATION

14
Water Quality 107 Figure 66. Hydrogeologic section showing the predominant reduction-oxidation conditions and processes along line A–A’ associated with selected surface waters and with selected wells completed in the perched water-bearing zone, Magothy aquifer, or upper Patapsco aquifer shallow or deep water-bearing zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11. (Location of line of section A–A’ is shown in figure 39.)

Magothy aquifer

Fill - Matawan Formation

Upper Patapsco aquifershallow water-bearing zone

Upper Patapsco aquifer

deep water-bearing zone

Altitude, in feet above or below North American Vertical Datum of 1988 Groundwater divide

Well

identifier

An-Fe

An-Fe

An-FeAn-Fe

An-Fe

An-Fe

An-Fe

An-Fe

An-Fe

An-Fe

An-Fe

An-Fe

Mx-O2-Fe

Mx-O2-Fe

Mx-O2-Mn

Mx-O2-Mn

Mx-O2-Mn

Mx-O2-Mn

O2

O2 Mx-O2-Mn

172

5025

-25-50-75

-100-125-150-175-200-225-250

0

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000

Distance, in feet

4,500 5,000 5,500 6,000 6,500 7,000 8,000 8,500 9,000 7,500

A

WEST

A'

EAST

193

192 191

157 158 124 139 122

151 81

163

168

165

164 171 142 178

128 160

Confining unit

Confining unit

Elk

River

Confining unit

VERTICAL EXAGGERATION x 20

Reduction-oxidation conditions and processes

 Oxygen present and being reduced

 Mixed oxic and anoxic, oxygen, and manganese present and being reduced Mixed oxic and anoxic, oxygen, and iron present and being reduced Anoxic, iron present and being reducedDirection of groundwater flowPrecipitation/recharge

EXPLANATION

O2

An-Fe

Mx-O2-Fe

Mx-O2-Mn
108 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

O2–Fe(III) or O2–Mn). In part, these redox conditions and 

processes likely reflect local recharge—precipitation and residential use (irrigation and septic effluents), where human uses 

reflect groundwater that generally has been treated to remove 

TDS before use. Thus, local recharge and shallow groundwater likely is a mixture of oxic (precipitation or surface 

irrigation) and mixed oxic-anoxic (for example, septic system 

effluent) (figs. 43, 49, and 66), with relatively low concentrations of TDS (fig. 41).

A pattern similar to that described among redox conditions and processes, TDS, and groundwater described above 

for A–A′, also occurs along C–C′ through the WVS community 

(fig. 67). Groundwater in the Magothy aquifer beneath the 

DMCA is under anoxic and Fe(III)-reducing conditions and 

associated with high concentrations of TDS (fig. 43). Both 

these attributes persist as this water flows north into WVS 

and then downward into the upper Patapsco aquifer shallow 

water-bearing zone beneath the community. However, as in 

the case of A–A′, groundwater at shallow depths beneath the 

community along C–C′ also is under mixed oxic-anoxic conditions (fig. 67, O2

–Mn) and likely reflects the relatively oxic to 

mixed oxic-anoxic nature of local recharge that contains low 

to intermediate concentrations of TDS (fig. 43).

It should be noted that anoxic iron-reducing groundwater conditions are not solely the result of the DMCA. For 

example, along B–B′, anoxic iron-reducing conditions occur 

throughout the groundwater flow system, including the upper 

Patapsco aquifer deep water-bearing zone. Despite the anoxic 

iron-reducing conditions, concentrations of TDS and major 

ion distributions indicated that the groundwater in the upper 

Patapsco aquifer deep water-bearing zone has not been 

impacted by the DMCA (fig. 68). 

Given the dominant redox conditions and predominant 

redox processes and their relation to patterns in groundwater flow and TDS, the effect of the DMCA appears to be the 

recharging of groundwater under reduced conditions that is 

elevated in TDS, which could be expected to contain elevated 

concentrations of reduced forms of redox-sensitive species. 

The primary areas affected by this DMCA recharge are the 

perched water-bearing zone and the Magothy aquifer within 

and at least along to the DMCA property boundary, and where 

leakage occurs into the upper Patapsco aquifer shallow waterbearing zone—along Pond Neck Road, and into WVS. This 

conclusion is consistent with the concept that the DMCA is 

an elevated and artificial groundwater-recharging wetland 

that was created on a natural discharging wetland. However, 

whether or not groundwater flow from the DMCA is the sole 

source of poor quality water farther along groundwater flow 

paths from the DMCA cannot be fully determined on the basis 

of this analysis of groundwater flow, redox conditions, and 

TDS.

Mixed Reduction-Oxidation Processes and pH

Groundwater in the DMCA and vicinity with the highest levels of TDS (fig. 41), and high or the highest levels of 

sulfate (fig. 65), and reduced metals—manganese (fig. 63), 

and ferrous iron (fig. 57)—generally corresponds to parts 

of the groundwater flow system where anoxic iron-reducing 

groundwater from the DMCA potentially come into contact 

with oxygen-bearing groundwater from other source areas. 

Two such areas are the local Magothy aquifer-upper Patapsco 

aquifer shallow water-bearing zone beneath WVS and the 

local Magothy aquifer just east of the DMCA. 

Whether groundwater in these two areas simply represents a downgradient plume of older contaminated groundwater from the DMCA—for example, the migration of 

groundwater recharge from the DMCA when it was in use—or 

reflects another unique redox condition outside of the DMCA 

is critical to understanding what factors influence the quality 

of water in these areas. However, no information is available 

on the ages of groundwater in the study area since its time of 

recharge, or from hydrogeochemical modeling, which could 

help determine the above. In the case of the local WVS flow 

system, there are sufficient data and knowledge about the area 

to indicate that the quality of the groundwater in this area 

could reflect a localized interaction between oxygen-bearing 

and anoxic groundwater that leads to a unique redox environment, which further affects the quality of groundwater beneath 

the community.

Redox conditions in the groundwater beneath WVS 

indicate groundwater at shallow depth is oxygen bearing, at 

intermediate depths reflects mixed oxic-anoxic conditions, and 

at even deeper depths is anoxic (figs. 66 and 67). Absent any 

influence from the DMCA, this description could be considered a natural groundwater phenomenon; it generally could be 

expected to result in groundwater whose quality with depth 

would be expected to reflect that found in local aquifers in 

the study area that are not overly affected by human activities 

(tables 12 and 13).

Hamilton and others (1993) describe typical changes in 

the pH associated with redox conditions for groundwater in 

the surficial aquifer and updip confined aquifers of the Delmarva Peninsula. Rainfall on the Peninsula typically is oxic 

and acidic (pH 4–5 standard units), but low in TDS, and not 

highly buffered. However, upon infiltration and with increasing depth, the pH in most shallow groundwater increases 

(pH 5–6) and is weakly buffered as a result of reactions with 

silicate minerals. In updip aquifers such as the Magothy aquifer, or possibly in areas such as in WVS, where there no longer 

is a confining layer, groundwater flow is not impeded and can 

continue downward. Hamilton and others (1993) indicate the 

pH could again increase (6–8) with depth of flow as a result of 

iron and possibly sulfate reduction. The results of this process 

absent considerable anthropogenic influence are reflected in 

the pH of groundwater in the upper Patapsco aquifer shallow 

water-bearing zone in the study area (table 13; wells CE Dd 

146 and CE Dd 191). Overall, the general pattern of declines 

in pH with depth and from shallow to deep aquifers also 

appears in groundwater in the vicinity of the study area not 

overly affected by human activities (table 13).

Differences in the pH of groundwater with depth beneath 

WVS are not similar to the pattern with depth described above 

for groundwater relatively unaffected by human activities 
Water Quality 109 Figure 67. Hydrogeologic section showing the predominant reduction-oxidation conditions and processes along line C–C’ and collected from selected surface waters and selected wells completed in the perched water-bearing zone, Magothy aquifer, or upper Patapsco aquifer shallow or deep water- bearing zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11. (Location of line of section C–C’ is shown in figure 39.) 

0

50

25 169

174 176 171 164 163

81 151

Altitude, in feet above or below North American Vertical Datum of 1988

C

NORTH

C'

SOUTH

Well

identifier

Elk River

-100-125-150-175-200-225-250

-25-50-75

0 200 400 600 800 1,000 1,200 1,400 1,600 1,800 2,000 2,200 2,400

Distance, in feet

VERTICAL EXAGGERATION x 6

Magothy aquifer

Confining unit

Upper Patapsco aquifer

shallow water-bearing zone

Confining unit

Upper Patapsco aquifer

deep water-bearing zone

Confining unit

O2

An-Fe

An-Fe

An-Fe An-Fe

An-Fe

Mx-O2-Fe

Mx-O2-Mn

Mx-O2-Mn

Reduction-oxidation conditions and processes

 Oxygen present and being reduced

 Mixed oxic and anoxic, oxygen, and manganese present and being reduced Mixed oxic and anoxic, oxygen, and iron present and being reduced Anoxic, iron present and being reducedDirection of groundwater flowPrecipitation/recharge

EXPLANATION

O2

An-Fe

Mx-O2-Fe

Mx-O2-Mn
110 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

(figs. 69 and 70). Shallow oxygen-bearing groundwater 

beneath WVS is acidic (fig. 69; approximately pH 4.5 to 

5.0 standard units). In part, this acidity likely reflects recharge 

from precipitation. In part, it also reflects recharge from residential use. 

The pH of residential recharge in WVS could differ 

considerably. Historical surveys (Maryland Environmental 

Service, 1995) indicate that most WVS residents treat their 

water to remove most but not all metals. However, these 

historical surveys, as well as recent surveys conducted by 

the USGS during the canvassing of this area to select wells 

and by the Cecil County Health Department (A. Scramlin, 

Cecil County Health Department, written commun., 2010), 

suggested at least some but not all residents also treat their 

water to increase the pH to approximately 6 standard units. 

Thus, depending on the depth water is withdrawn (fig. 69), and 

the subsequent level of treatment, the pH of residential supply water, and, thus, initial recharge water associated with its 

use, could range from approximately 4.2 to 6 standard units. 

This range in pH is considerably broader than the range in pH 

in groundwater recharge typically associated with precipitation. Ultimately, despite the possible range in the initial pH 

of residential recharge, it likely is weakly buffered, as the pH 

in oxygen-bearing shallow groundwater beneath WVS ranges 

from of approximately 4.5 to 5 standard units and is typically 

less than pH associated with groundwater in the Magothy 

Figure 68. Hydrogeologic section showing the predominant reduction-oxidation conditions and processes along line B–B’ 

associated with selected wells completed in the Magothy aquifer or in the upper Patapsco aquifer shallow or deep waterbearing zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11. 

(Location of line of section B–B’ is shown in figure 39.)

An-Fe

An-Fe

An-Fe

An-Fe An-Fe

An-Fe

An-Fe

An-Fe

An-Fe

An-Fe

Groundwater divide

Altitude, in feet above or below North American Vertical Datum of 1988

B

NORTH

B'

SOUTH

Well

identifier

Elk River

VERTICAL EXAGGERATION x 20

126

136 138 137

147

145

146 149

157 158

-250

-225

-200

-175

-150

-125

-100

-75

-50

-25

0

25

50

Distance, in feet

Magothy aquifer

Fill - Matawan Formation

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 5,000 5,500

Confining unit

Upper Patapsco aquifer

shallow water-bearing zone

Confining unit

Upper Patapsco aquifer

deep water-bearing zone

Confining unit

Reduction-oxidation conditions and processes

 Anoxic, iron present and being reduced

Direction of groundwater flow

Precipitation/recharge

EXPLANATION

An-Fe
Water Quality 111 Figure 69. Hydrogeologic section showing the pH in water-quality samples along line A–A’ and collected from selected surface waters and from selected wells completed in the perched water-bearing zone, Magothy aquifer, or upper Patapsco aquifer shallow or deep water-bearing zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11. (Location of line of section A–A’ is shown in figure 39.)

Magothy aquifer

Fill - Matawan Formation

Upper Patapsco aquifer

shallow water-bearing zone

Upper Patapsco aquifer

deep water-bearing zone

172

Groundwater divide

Well

identifier

3.9

6.2

5.6

6.0

4.3

6.2

5.8

4.9

4.2

4.4

6.1

4.5

4.4

4.6

5.4

4.9

6.3

8.2

5.6

4.5

4.9

5025

-25-50-75

-100-125-150-175-200-225-250

0

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000

Distance, in feet

4,500 5,000 5,500 6,000 6,500 7,000 8,000 8,500 9,000 7,500

A

WEST

A'

EAST

193

192 191

157 158 124 139 122

151 81

163

168

165

164 171 142 178

128 160

Confining unit

Confining unit

Elk

River

Confining unit

Altitude, in feet above or below North American Vertical Datum of 1988

VERTICAL EXAGGERATION x 20

pH —Red number indicates pH less than  acceptible range in Federal Secondary  Drinking Water Regulation. Federal  Secondary Drinking Water Regulation, greater than 6.5 and less than 8.5Direction of groundwater flowPrecipitation/recharge

EXPLANATION

8.2
112 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area Figure 70. Hydrogeologic section showing the pH in water-quality samples along line C–C’ and collected from selected surface waters and from selected wells completed in the Magothy aquifer or upper Patapsco aquifer shallow or deep water-bearing zone in the Pearce Creek Dredge Material Containment 

Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11. (Location of line of section C–C’ is shown in figure 39.)

0

50

25

6.3

6.1 5.8

6.1

4.2

4.4 5.8

4.9

169

174 176 171 164 163

81 151

8.2

Altitude, in feet above or below North American Vertical Datum of 1988

C

NORTH

C'

SOUTH

Well

identifier

Elk River

-100-125-150-175-200-225-250

-25-50-75

0 200 400 600 800 1,000 1,200 1,400 1,600 1,800 2,000 2,200 2,400

Distance, in feet

VERTICAL EXAGGERATION x 6

Magothy aquifer

Confining unit

Upper Patapsco aquifer

shallow water-bearing zone

Confining unit

Upper Patapsco aquifer

deep water-bearing zone

Confining unit

pH —Red number indicates pH less than  acceptible range in Federal Secondary  Drinking Water Regulation (>6.5 and <8.5)Direction of groundwater flowPrecipitation/recharge

EXPLANATION

8.2
Water Quality 113

aquifer in the vicinity of the study area which appear not 

overly affected by human activities (table 13).

Beneath the oxygen-bearing zone in WVS, and under 

natural conditions, as described above, it would be expected 

that there would be an increase in pH downgradient. However, 

the pH of groundwater beneath the oxygen-bearing zone in the 

Magothy–upper Patapsco aquifers slightly decreases, ranging 

from 4.2 to 4.9 standard units (fig. 69). In addition, the low pH 

at depth in the upper Patapsco aquifer shallow water-bearing 

zone appears to be local in character, and is not evident either 

upgradient or downgradient in this zone (fig. 70). Below the 

shallow oxygen-bearing zone, groundwater at intermediate 

depths also reflects mixed oxic and anoxic conditions, and, at 

the base of the upper Patapsco aquifer shallow water-bearing 

zone, anoxic (iron-reducing) conditions (figs. 66 and 67). 

The overall trend in pH of progressively acidic conditions 

with depth could be directly related to the progression from 

oxygen-bearing to mixed oxic and anoxic and ultimately 

anoxic conditions. Both progressive conditions could reflect 

the effects of residential supply-well withdrawals, which 

draw anoxic groundwater coming from the DMCA into what 

initially is relatively oxygen-bearing groundwater associated 

with local recharge. If anoxic groundwater is drawn into predominately oxygen-bearing groundwater, then the former will 

undergo oxidation. One notable outcome of oxidation would 

be the production of acidity (H+

), and corresponding decline 

in pH, through the oxidation of reduced iron, and the local 

formation of ferric hydroxide precipitates, as follows:

Fe2+ + 0.25O2 + H+ = Fe3+ + 0.5 H2O (2) 

Fe3+ + 3H2O = Fe(OH)3(s)+3H+ (3)

The oxidation of iron sulfide minerals would also lead to the 

production of acidity. The oxidation reaction of iron sulfide is 

as follows:

2FeS + 4.5O2 + 2H2O = Fe2O3 + 4H+ + 2SO4

2– (4)

The initial low pH of shallow groundwater in the Magothy aquifer beneath WVS, and the resulting increase in pH 

with depth in groundwater in the Magothy—upper Patapsco 

aquifers beneath WVS, would provide acidic conditions 

well suited for hydrolysis and mobilization of metals from 

native sediments. The groundwater flow from the DMCA also 

contains abundant levels of organic carbon (see Dissolved 

Organic Carbon, this report), which are necessary to support 

microbial reducing conditions (table 14, reduction reactions). 

The return to relatively severe (iron-reducing) anoxic conditions at depth in the upper Patapsco aquifer shallow waterbearing zone beneath WVS, combined with the low pH and 

elevated concentrations of organic carbon, imply groundwater 

conditions at depth in the upper Patapsco aquifer beneath the 

WVS community are ideally suited for the increased microbial 

reduction and mobilization of metals. The overall expected 

result would be a localized increase in the concentration of 

TDS, which in combination with the major inflow of anoxic 

groundwater of similar quality from the DMCA would account 

for the local and highly elevated concentrations of TDS and 

reduced metals at depth in the upper Patapsco aquifer shallow water-bearing zone directly beneath the WVS community 

and described in earlier sections of this report. Similar redox 

reactions could occur elsewhere in the vicinity of the DMCA 

where local groundwater withdrawals for supplies draw highly 

reduced anoxic groundwater from the DMCA into areas where 

local groundwater generally is oxygen-bearing. 

Extended Implications of Reduction-Oxidation 

Processes on Groundwater Quality

Groundwater in the DMCA and vicinity that is not 

affected by the DMCA include: (a) in the Magothy aquifer, 

the shallow oxygen-bearing groundwater beneath WVS to 

the west of the DMCA and to the east of the DMCA, (b) in 

the anoxic upper Patapsco aquifer shallow water-bearing 

zone, except where leakage has occurred through the confining layer from the Magothy aquifer beneath the DMCA, or 

where the confining layer is absent to the west of the DMCA 

beneath WVS, and (c) in the anoxic upper Patapsco aquifer 

deep water-bearing zone. Despite differences in redox conditions, groundwater in these areas has been shown to contain 

relatively low concentrations of TDS and the forms of redoxsensitive constituents reflecting the redox condition.

Groundwater affected by the DMCA is predominately 

anoxic and mainly reflects iron-reducing conditions. These 

redox conditions correspond to the virtual absence of dissolved oxygen but an abundance of the reduced forms of 

nitrogen (ammonia) and metals (manganese and iron). Given 

iron is reduced instead of sulfate, sulfate occurs at elevated 

concentrations. The resultant anoxic groundwater occurs in 

the Magothy aquifer beneath the DMCA, and bordering the 

DMCA property boundary, as well as beyond its boundary. 

The anoxic groundwater also occurs in the upper Patapsco 

aquifer shallow water-bearing zone to the west of the DMCA 

beneath WVS where the confining layer between the Magothy 

aquifer and the upper Patapsco aquifer shallow water-bearing 

zone is absent, and beneath the DMCA where leakage occurs 

through the confining layer between these two aquifers. 

The implications of the potential effects of the DMCA 

on groundwater quality beyond its boundaries extend to other 

trace elements and not just iron and manganese. McMahon 

and Chapelle (2008) recently examined high concentrations of naturally occurring arsenic in the principal aquifers 

of the United States. They found that regardless of aquifer 

sediment type, elevated concentrations of arsenic concentrations were found in groundwater under reduced (Mn(IV)- or 

Fe(III)—SO4

2–) compared to oxic conditions. In particular, 

the occurrence and distribution of three additional trace elements—aluminum, beryllium, and arsenic—appear similarly 

governed for groundwater in the DMCA and vicinity. Elevated 
114 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

concentrations of these trace elements mainly occur at high 

concentrations in groundwater where reducing conditions 

could be enhanced by the mixing of anoxic water from the 

DMCA and oxygen-bearing water from another source. The 

three areas where these conditions possibly occur are in the 

Magothy aquifer just east of the DMCA property boundary, 

in the Magothy aquifer west of the DMCA property boundary and beneath WVS, and in the Magothy aquifer to the 

north where it potentially co-discharges with groundwater 

from the upper Patapsco aquifer shallow water-bearing zone 

and possibly groundwater recharge from Pearce Creek Lake. 

For brevity, the following discussion focuses on groundwater 

flow along C–C′ with an emphasis on groundwater flow in the 

Magothy aquifer to WVS. 

After iron and manganese, the next most abundant trace 

element in groundwater is aluminum (appendix B, table B3). 

Concentrations of aluminum in groundwater in the DMCA and 

vicinity range from less than 0.01 to 58 mg/L. Along section 

line A–A′ (fig. 71), the highest concentrations of aluminum 

occur at depth in the upper Patapsco aquifer shallow waterbearing zone west of the DMCA and beneath WVS, and in 

the Magothy aquifer east of the DMCA property boundary. In 

each case, anoxic groundwater from the DMCA is in proximity to oxic waters from another source. In WVS, the concentrations of aluminum begin increasing with depth, acidity, and 

severity in redox conditions below the oxygen-bearing zone, 

and they are highest at the base of the upper Patapsco aquifer 

shallow water-bearing zone. The solubility of aluminum can 

increase with elevated concentrations of sulfate and DOC, 

which were also observed at the base of the upper Patapsco 

aquifer shallow water-bearing zone. Elsewhere, in the study 

area (fig. 71), or near the study area (table 13), groundwater 

has relatively low concentrations of dissolved aluminum. 

Concentrations of dissolved beryllium in groundwater in 

the DMCA and vicinity range from less than 0.4 to 18 μg/L 

(appendix B, table B3). Elevated concentrations of beryllium 

mainly are associated with groundwater at depth in the upper 

Patapsco aquifer shallow water-bearing zone beneath the 

western end of the DMCA and into WVS (fig. 72). As in the 

case of aluminum, concentrations of beryllium increase with 

depth below the oxygen-bearing zone beneath the community 

and are highest under the extreme reducing conditions at the 

base of the upper Patapsco aquifer shallow water-bearing zone 

(fig. 73).

Concentrations of arsenic in groundwater in the 

DMCA and vicinity range from less than 0.10 to 58.7 μg/L 

(appendix B, table B3). The highest concentrations of arsenic 

occurred in samples taken in 2010 and 2011 at well CE Dd 

122, which is completed in the upper Patapsco aquifer shallow 

water-bearing zone beneath perched water-bearing zone and 

Magothy aquifer at the western end of the DMCA (fig. 74). 

Lower but still elevated concentrations of arsenic occur in 

water-supply wells completed in this same water-bearing zone 

directly downgradient and west-northwest of well CE Dd 122. 

All of these wells are completed at depth in this water-bearing 

zone and under highly reducing conditions.

Additional Water-Quality Indicators Illustrate 

Effect of Dredge Material Containment Area on 

Local Groundwater Quality

The influence of the DMCA on the quality of groundwater is apparent in relation to water-quality conditions not 

directly related to redox conditions and redox-sensitive waterquality constituents. The DMCA’s influence also is apparent 

in the occurrence and distribution of detectable pesticides and 

wastewater compounds in groundwater in the DMCA and 

vicinity.

Pesticides and Wastewater Compounds

Occurrence and distribution surveys for pesticides in 

groundwater in the Mid-Atlantic Coastal Plain generally have 

been conducted to determine their fate and transport following their use in agricultural, residential, and (or) urban settings 

(Koterba and others, 2010). Fewer surveys have been conducted for wastewater compounds in groundwater in this setting, but they too generally have been conducted to determine 

the fate and transport of these compounds in groundwater.

Only within the last decade have surveys been done to 

determine the fate and transport of these and other organic 

compounds in bay sediments (see Chemical Composition of 

Sediments, this report). Bay sediments contain pesticides and 

wastewater compounds that generally are resistant to complete 

degradation. The source of most of these compounds typically 

is related to their use in terrestrial settings, but the occurrence 

of these compounds in bay sediments implies they generally 

have been exposed to both oxic and anoxic environments, and 

still persist, albeit often in a metabolite, rather than parent, 

compound form.

For the purposes of this report, occurrence and distribution surveys for these compounds mainly were conducted 

to (a) determine if groundwater in WVS used for water 

supplies, and relatively shallow groundwater elsewhere in 

the study area, contained residues of these compounds, and 

(b) determine the source of local recharge or groundwater 

flow such as agricultural areas, residential areas, and (or) the 

DMCA. Because most pesticides and wastewater compounds 

of anthropogenic origin are of relatively recent origin, the 

surveys are limited in aerial and vertical extent in relation to 

the shallow groundwater flow system in the DMCA and its 

vicinity. Thus deeper groundwater in the study area (such as 

from the upper Patapsco aquifer deep water-bearing zone and 

some groundwater from the upper Patapsco aquifer shallow 

water-bearing zone) was not analyzed for pesticides or wastewater compounds. In this report, the term pesticide includes 

both pesticides and their metabolites for which samples were 

analyzed. 
Water Quality 115 Figure 71. Hydrogeologic section showing concentrations of dissolved aluminum in water-quality samples along line A–A’ and collected from selected surface waters and from selected wells completed in the perched water-bearing zone, Magothy aquifer, or upper Patapsco aquifer shallow or deep water-bearing zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11. (Location of line of section A–A’ is shown in figure 39.)

Magothy aquifer

Fill - Matawan Formation

Upper Patapsco aquifer

shallow water-bearing zone

Upper Patapsco aquifer

deep water-bearing zone

172

Groundwater divide

Well

identifier

58.0

<0.01

<0.06

<0.01

26.5

<0.02 0.03

3.29

1.24

0.19

<0.01

4.86

18.7

0.83

0.11

0.09

0.03

0.01

0.01

0.01

0.11

5025

-25-50-75

-100-125-150-175-200-225-250

0

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000

Distance, in feet

4,500 5,000 5,500 6,000 6,500 7,000 8,000 8,500 9,000 7,500

A

WEST

A'

EAST

193

192 191

157 158 124 139 122

151 81

163

168

165

164 171 142

128

178

160

Confining unit

Confining unit

Elk

River

Confining unit

Altitude, in feet above or below North American Vertical Datum of 1988 

VERTICAL EXAGGERATION x 20

Dissolved aluminum concentration, in milligrams per liter (mg/L) —Red number indicates value  exceeds Federal Secondary Drinking Water Regulation (0.20 mg/L). <, less thanDirection of groundwater flowPrecipitation/recharge

EXPLANATION

<0.01
116 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area Figure 72. Concentrations of dissolved beryllium in water-quality samples collected from selected surface waters and from selected wells completed 

in the upper Patapsco aquifer shallow water-bearing zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11.

127

141

75°59' 76°

39°26'

39°25'30"

Elk River Pearce Creek Lake

Crystal Beach

Pond Neck Road

West View Shores

Bay View Estates

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

2

4

4

6 6

8

8

<0.08

<0.04

5.6

0.14

1.8

0.58

3.5

5.8

0.41

6.0 <0.04

<0.04

0.16

0.1

5.6

17.0

0.14

0.58

3.5

5.8 4.0

18.0 0.6

0.064

0.53

0.34

0.29

<0.04

0.41

6.0

1.0 1.6

E 0.033

E 0.038

17.0

27

EXPLANATION

Potentiometric surface contour in the upper Patapsco aquifer, shallow water-bearing 

zone— Shows altitude at which water would have stood in tightly cased wells, May 19–20, 2010. Dashed where approximately located. Contour interval 2 feet. Datum is North American Vertical Datum of 1988

Direction of groundwater flowUpper Patapsco aquifer well, shallow water-bearing zone—Number shows dissolved 

beryllium concentration, in micrograms per liter (μg/L). Exceeds Federal Maximum Contaminant Level for public drinking water supply (4.0 μg/L). E, estimated

Upper Patapsco aquifer well, shallow water-bearing zone—Number shows 

dissolved beryllium concentration, in μg/L. Does not exceed Federal Maximum Contaminant Level for public drinking water supply (4.0 μg/L). <, less than. E, estimated

Surface-water site—Number shows dissolved beryllium concentration, in μg/L. 

Does not exceed Federal Maximum Contaminant Level for public drinking water supply (4.0 μg/L). <, less than

6 82.3
Water Quality 117 Figure 73. Hydrogeologic section showing concentrations of dissolved beryllium in water-quality samples along line A–A’ and collected from selected surface waters and from selected wells completed in the Magothy aquifer or upper Patapsco aquifer shallow or deep water-bearing zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11. (Location of line of section A–A’ is shown in figure 39.)

Magothy aquifer

Fill - Matawan Formation

Upper Patapsco aquifershallow water-bearing zone

Upper Patapsco aquifer

deep water-bearing zone

Groundwater divide

Well

identifier

6.7

0.29

<0.40 <0.04

18

0.083

0.60

17

5.6

0.76

E 0.039

1.6

6.0

1.0

0.41

0.39

0.12

0.28

<0.08

E0.010

0.68

5025

-25-50-75

-100-125-150-175-200-225-250

0

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000

Distance, in feet

4,500 5,000 5,500 6,000 6,500 7,000 8,000 8,500 9,000 7,500

A

WEST

A'

EAST

193

192 191

157 158 124 139 122

151 81

163

168

165

164 171 142

128

178 160

Confining unit

Confining unit

Elk

River

Confining unit

Altitude, in feet above or below North American Vertical Datum of 1988

VERTICAL EXAGGERATION x 20

172

Dissolved beryllium concentration, in micrograms per liter (μg/L) —Red number indicates value 

 exceeds Federal Maximum Contaminant Level (4 μg/L). <, less than; E, estimatedDirection of groundwater flowPrecipitation/recharge

EXPLANATION

<0.01
118 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area Figure 74. Concentrations of dissolved arsenic in water-quality samples collected from selected surface waters and from selected wells completed 

in the upper Patapsco aquifer shallow water-bearing zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11.

127

141

75°59' 76°

39°26'

39°25'30"

Elk River Pearce Creek Lake

Crystal Beach

Pond Neck Road

West View Shores

Bay View Estates

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

2

4

4

6 6

8

8

0.25

6.34

3.92

1.594.75

0.111.05

0.89

0.12

0.35

0.32

58.7

8.71

3.94

0.84

0.30 1.041

<0.10

<0.10

6.34

4.750.11

8.71

3.94

0.84

<0.10

<0.10

<0.10

0.34

<0.10

<0.10

0.31

0.39

<0.10

58.7

0.25

EXPLANATION

Potentiometric surface contour in the upper Patapsco aquifer, shallow water-bearing 

zone— Shows altitude at which water would have stood in tightly cased wells, May 19–20, 2010. Dashed where approximately located. Contour interval 2 feet. Datum is North American Vertical Datum of 1988

Direction of groundwater flowUpper Patapsco aquifer well, shallow water-bearing zone—Number shows dissolved 

arsenic concentration, in micrograms per liter (μg/L). Exceeds Federal Maximum Contaminant Level for public drinking water supply (10.0 μg/L). E, estimated

Upper Patapsco aquifer well, shallow water-bearing zone— Number shows 

dissolved arsenic concentration, in μg/L. Does not exceed Federal Maximum Contaminant Level for public drinking water supply (10.0 μg/L). <, less than. E, estimated

Surface-water site—Number shows dissolved arsenic concentration, in μg/L. Does 

not exceed Federal Maximum Contaminant Level for public drinking water supply (10.0 μg/L)

6 0.31
Water Quality 119

Low Level of Detection Pesticide Survey

An occurrence and distribution survey to detect pesticides at low levels was conducted with 20 observation and 

15 domestic-supply wells (appendix A, table A1; appendix B, 

table B1) in the DMCA and its vicinity to provide information on the distribution of 54 pesticides or their metabolites 

in the shallow groundwater in the study area (primarily the 

Magothy aquifer and upper Patapsco aquifer shallow waterbearing zone). These pesticides and metabolites commonly are 

detected in shallow groundwater in Mid-Atlantic Coastal Plain 

settings and associated with agricultural, residential, and (or) 

urban land use (Koterba and others, 2010).

The purpose of this pesticide survey was to help determine the potential sources of groundwater used for domestic 

water supplies in the vicinity of the DMCA. Most (44 of 

54) pesticide or metabolite compounds were not detected 

(concentrations reported as less than their respective LRLs) 

in any groundwater samples from observation or domestic 

wells (appendix B, table B3, LCEA and LCPD pesticides and 

metabolites). 

Ten of the 54 different pesticides were detected in observation and (or) domestic water-supply wells at generally low 

(less than 0.50 μg/L) concentrations (table 16). Compounds 

detected with the highest frequency were the metabolites of 

metolachlor and alachlor, and included metolachlor ethane 

sulfonic acid (ESA) (15 of 35 wells), metolachlor oxanilic 

acid (OXA) (13 of 35 wells), alachlor oxanilic acid (OXA) 

(12 of 35 wells), and alachlor ethane sulfonic acid (ESA) 

(11 of 35 wells). Other than these four compounds, only six 

other compounds were each detected once—dechloroalachlor, 

dechlorometolachlor, metolachlor, the triazine metabolites 

2-chloro-4-isopropyl-amino-6-amino-s-triazine (DEA) and 

2-hydroxy-4-isopropyl-amino-6-ethylamino-s-triazine (HA), 

and dimethenamid, with the latter only being detected at the 

Pearce Creek Lake outlet (table 16).

The occurrence of mainly the ESA and OXA metabolites 

of alachlor and metolachlor, compared to other pesticide residues in groundwater in the study area, is consistent with patterns of pesticide occurrence observed in other nearby Coastal 

Plain settings (Koterba and others, 2010) and likely relates 

to their resistance to further degradation once in the soil and 

no longer exposed to photochemical degradation (J. Barbash, 

USGS, written commun., 2011). 

Multiple pesticide detections occurred in groundwater 

at two wells screened in the local perched water table 

Table 16. Summary of pesticides detected with low-level analytical methods in groundwater and surface-water samples collected in 

the Pearce Creek Dredge Material Containment Area and vicinity, 2010–11.

[μg/L, micrograms per liter; <, less than; X, number of wells with detectable concentrations]

Analyte

Laboratory 

reporting 

level (μg/L)

Number of detections and range in detected concentrations (μg/L)

Observation wells Comments

(X/20)

Domestic wells 

(X/15) All wells (X/35)

Triazines and metabolites

2-chloro-4-isopropyl-amino6-amino-s-triazine (DEA)< 0.025 1/20, 0.050 0/15 1/35, 0.50

2-hydroxy-4-isopropylamino-6-ethylamino-striazine (HA)< 0.025 1/20, 0.050 0/15 1/35, 0.050 Also detected 

(0.070 μg/L) in 

Pearce Creek Lake

Acetanilides, acetanimides, and metabolites

Alachlor ethane sulfonic 

acid (ESA)

< 0.020 9/20, 0.020 to 0.160 2/15, 0.020 to 0.030 11/35, 0.020 to 0.160

Alachlor oxanilic acid 

(OXA)

< 0.020 9/20, 0.040 to 0.250 3/15, 0.030 to 0.100 12/35, 0.030 to 0.250

Dechloroalachlor < 0.020 1/20, 0.020 0/15 1/35, 0.020

Metolachlor ethane sulfonic 

acid (ESA)

9/20, 0.020 to 0.110 6/15, 0.020 to 0.080 15/35, 0.020 to 0.110 Also detected 

(0.140 μg/L) in 

Elk River 

Metolachlor < 0.020 1/20, 0.030 0/15 1/35, 0.030

Dechlorometolachlor < 0.020 0/20 1/15, 0.020 1/35, 0.020

Metolachlor oxanilic acid 

(OXA)

< 0.020 10/20, 0.030 to 0.100 3/15, 0.030 to 0.090 13/35, 0.030 to 0.100 Also detected 

(0.090 μg/L) in 

Pearce Creek Lake 

Dimethenamid < 0.020 0/20 0/15 0/35 Detected (0.040 μg/L) 

only in Pearce Creek 

Lake 
120 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

(wells CE Dd 124, 2 pesticide detections; and CE Dd 144, 4 

pesticide detections) and in 11 wells screened in the Magothy 

aquifer primarily located along the southern part of the study 

area along Pond Neck Road (fig. 75) in the central part of the 

DMCA (wells CE Dd 137 and 144, 3 pesticides detected at 

each well; well CE Dd 157, 2 detections), and in WVS just 

beyond the DMCA property boundary (domestic well CE Dd 

179, 5 pesticides detected). Only one pesticide, metolachlor 

ethane sulfonic acid, was detected in one of the six other 

wells (used in this survey) located in WVS and completed in 

shallow oxic water in the Magothy aquifer (well CE Dd 172). 

Thus, most pesticide detections occur in wells completed 

beneath the DMCA, beneath its property boundary, or just 

beyond its property boundary, and are associated with anoxic 

groundwater flow within or from the DMCA (figs. 76 and 77). 

Notably, five detections occurred in well CE Dd 193, which is 

completed in the oxic water east of the DMCA. Despite having 5 detections, other water quality parameters in CE Dd 193 

did not appear to be overly affected by any land use. 

The co-occurrence of similar pesticides (mainly ESA and 

OXA metabolites of metolachlor and alachlor) in the wells 

sampled along Pond Neck Road could indicate that shallow 

oxic groundwater east of the DMCA is mixing with anoxic 

groundwater flowing south from the DMCA along the southern and southeastern border of the DMCA property boundary. 

It also could be that the co-occurrence of similar pesticides 

in both anoxic groundwater from the DMCA and oxic water 

to the east of the DMCA simply reflect the ubiquitous and 

long-term use of these compounds and their resistance to 

degradation. During DMCA use, these compounds could have 

been introduced into the DMCA in either dredged sediment 

or Elk River water, and they simply have remained detectable 

in older groundwater flowing from the DMCA; whereas their 

occurrence in oxic groundwater from the east of the DMCA 

simply reflects their long-term use in agricultural areas to the 

east and (or) south of the DMCA. That the latter is most likely 

supported by the fact that pesticide detections in the Magothy 

aquifer beneath the DMCA or along its property boundary to 

the north and northwest (figs. 75 and 76) also had detections of 

these same compounds, and this groundwater is mainly associated with recharge and groundwater flow from the DMCA.

In only one sample, domestic-supply well CE Dd 172, 

which involves a single pesticide detection, does the source 

of Magothy groundwater possibly reflect solely local recharge 

in WVS (figs. 75 and 76), as supported by other water-quality 

data. The remainder of the pesticides detected in groundwater 

beneath the WVS community reflect groundwater flowing 

from the DMCA or mixed DMCA-anoxic and WVS-oxic 

groundwater at depth (figs. 76 and 77).

The majority of wells screened in the upper Patapsco 

aquifer shallow water-bearing zone from which samples were 

analyzed for low-level pesticide detections were located in 

WVS; two other wells were located in the southeastern part 

of the study area. Most of the low-level pesticide detections 

in the upper Patapsco aquifer shallow water-bearing zone are 

associated with groundwater flow from the DMCA, or mixed 

DMCA anoxic and WVS oxic groundwater. With one exception, multiple metabolite detections in the upper Patapsco 

aquifer shallow water-bearing zone are most prevalent beneath 

the northwestern part of WVS, where wells are completed 

in the deep part of this water-bearing zone (fig. 78). The one 

exception is domestic well CE Dd 161, which is located on the 

eastern edge of WVS and just west of the DMCA. Four pesticides were detected in this well (metolachlor and alachlor ESA 

and OXA metabolites). Absent the confining layer between the 

Magothy and upper Patapsco aquifers, the most likely source 

of water for this well is groundwater flow from the DMCA.

Of the two wells in this pesticide survey that were 

completed in the upper Patapsco aquifer outside of the WVS 

community (fig. 78) only one pesticide (metolachlor-ESA) 

was detected in one of these wells (CE Dd 192). The source of 

this groundwater is flow from the DMCA. 

Wastewater Compound Survey

An occurrence and distribution survey for wastewater 

compounds was conducted for 14 selected observation wells, 

mainly in the western half of the DMCA, and 15 domestic 

water-supply wells in the vicinity of the DMCA (appendix A, 

table A1; appendix B, table B1). Approximately 69 wastewater 

compounds (table 17), classified according to common sources 

or uses, were included and reflect selected fossil fuel and combustion byproducts (11), biogenic sterols (4), detergent components and their metabolites (8), solvents (4), pesticides (15), 

fragrances and flavorants (9), pharmaceuticals (5), plasticizers 

(7), flame retardants (3), anti-oxidants (2), and chlorination 

byproducts (1). Data for five wastewater compounds appeared 

unsuitable for source-water or spatial interpretation because 

of issues related to the quality of data (table 17, DQI; and 

appendix B, table B9), and included the pesticide 1,4-dichlorobenzene, the plasticizers bisphenol A, and bis(2-ethylhexyl) 

and diethyl phthalates, and the ubiquitous use and source compound phenol. Of the remaining 64 wastewater compounds, 35 

were not detected (reported as less than their respective LRLs) 

in groundwater samples from observation or domestic wells 

(appendix B, table B9). 

Twenty-nine of the 64 wastewater compounds were 

detected at low concentrations (less than 1 μg/L), which generally were below the LRLs, but above the long-term method 

detection limit (table 17; appendix B, table B3). Therefore, 

most concentrations are estimated values with higher than 

normal uncertainty, and hereafter they are referred to as simply 

detections in this report. Individual compounds detected with 

the highest frequency were the biogenic sterols cholesterol 

(11 of 29 wells) and β-sitosterol (9 of 29 wells), the detergent 

isomers of 4-nonylphenol (8 of 29 wells), and the solvent 

isophorone (10 of 29 wells). 

The most frequently detected wastewater compounds 

grouped according to potential source and (or) use and the 

number of different compounds detected within each group 

were fossil fuel components and combustion byproducts 

(10 of 11 compounds), biogenic sterols (4 of 4 compounds), 
Water Quality 121

Table 17. Characteristics and summary of detections of organic wastewater compounds associated with groundwater samples 

collected from selected wells in the Pearce Creek Dredge Material Containment Area and vicinity, 2010.

[NO, naturally occurring source; CMAR, commercial, manufacturing, agricultural, and (or) residential source(s); PAH, polycyclic aromatic hydrocarbon; μg/L, 

micrograms per liter; E, estimated concentration with greater than normal uncertainty; <, less than; DQI, data-quality issues preclude interpretation of data, see 

text for in-depth discussion; wastewater compound analytical method described in Zaugg and others (2002)]

Analyte Major use(s) and (or) source(s)1

Laboratory 

reporting level 

(μg/L)

Number of detections (X), and range in 

concentrations

Observation 

wells (X/14)

Domestic 

wells (X/15)

All wells 

(X/29)

Fossil fuel components and combustion byproducts (except for p-Creosal, all are PAH compounds)

Anthracene NO, plant compound, combustion; CMAR: wood 

preservative, insecticide

< 0.2 6/14, E 0.01 

to E 0.027

0/15 6/29, E 0.01 

to E 0.027

9,10-Anthraquinone NO, oxidative byproduct of anthracene; CMAR: 

Bird (geese) repellent, noncrop areas, also dye ingredient, digestive additive in paper-pulp processing, and additive in laxatives and antimalarials 

< 0.2 5/14, E 0.025 

to 0.063

0/15 5/29, E 0.025 

to 0.063

p-Cresol NO, combustion byproduct; CMAR: wood preservative, combustion byproduct < 0.2 5/14, E 0.020 

to E 0.102

0/15 5/29, E 0.020 

to E 0.102

Fluoranthene NO, combustion byproduct; CMAR: combustion 

byproduct in coal tar and asphalt

< 0.2 4/14, E 0.008 

to E 0.043

0/15 4/29, E 0.008 

to E 0.043

Naphthalene NO, combustion byproduct; CMAR: combustion 

byproduct wood or fossil fuel; also found in tar, 

asphalt, and gasoline, and used in toilet bowl 

deodorizers, or as fumigant for moth repellent 

< 0.2 2/14, E 0.008 

to E 0.016

3/15, E 0.009 

to E 0.017

5/29, E 0.008 

to E 0.017

1-Methylnaphthalene NO, combustion byproduct, crude oil; CMAR: 

gasoline or diesel fuel component, combustion 

byproduct of tar, asphalt, crude oil 

< 0.2 2/14, E 0.008 

to E 0.009

0/15 2/29, E 0.008 

to E 0.009

2-Methylnaphthalene NO, combustion byproduct, crude oil; CMAR: 

gasoline or diesel fuel component, combustion 

byproduct of tar, asphalt, crude oil 

< 0.2 1/14, E 0.011 0/15 1/29, E 0.011

2,6-Dimethylnaphthalene NO, combustion byproduct; CMAR: diesel or kerosene fuel component, combustion byproduct < 0.2 1/14, E 0.009 0/15 1/29, E 0.009

Phenanthrene NO, combustion byproduct; CMAR: combustion product of tar, diesel fuel, crude oil, used in 

manufacture of selected dyes and pharmaceuticals 

(opiates) 

< 0.2 5/14, E 0.013 

to E 0.083

0/15 5/29, E 0.013 

to E 0.083

Pyrene NO, combustion byproduct; CMAR: combustion 

byproduct of asphalt 

< 0.2 4/14, E 0.013 

to E 0.032

0/15 4/29, E 0.013 

to E 0.032

Benzo[a]pyrene NO, combustion byproduct coal tar; CMAR: combustion byproduct of coal tar, petroleum fuels, and 

barbacued meats, 

< 0.2 0/14 0/15 0/29

Biogenic sterols

Cholesterol NO, plant and animal (including human) sterol < 0.16 7/14, E 0.24 

to E 0.51

4/15, E 0.12 

to E 0.32

11/29, E 0.12 

to E 0.51

3-β-Coprostanol NO, carnivore, including human, fecal sterol < 0.16 4/14, E 0.305 

to E 0.422

3/15, E 0.181 

to E 0.266

7/29, E 0.181 

to 0.422

β-Sitosterol NO, phytosterol < 0.16 7/14, E 0.474 

to E 1.07

2/15, E 0.243 

and 

E 0.466

9/29, E 0.243 

to E 1.07

β-Stigmastanol NO, phytosterol < 0.17 4/14, E 0.170 

to E 0.327

0/15 4/29, E 0.170 

to E 0.327
122 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

Table 17. Characteristics and summary of detections of organic wastewater compounds associated with groundwater samples 

collected from selected wells in the Pearce Creek Dredge Material Containment Area and vicinity, 2010.—Continued

[NO, naturally occurring source; CMAR, commercial, manufacturing, agricultural, and (or) residential source(s); PAH, polycyclic aromatic hydrocarbon; μg/L, 

micrograms per liter; E, estimated concentration with greater than normal uncertainty; <, less than; DQI, data-quality issues preclude interpretation of data, see 

text for in-depth discussion; wastewater compound analytical method described in Zaugg and others (2002)]

Analyte Major use(s) and (or) source(s)1

Laboratory 

reporting level 

(μg/L)

Number of detections (X), and range in concentrations

Observation 

wells (X/14)

Domestic 

wells (X/15)

All wells 

(X/29)

Detergent additives and their metabolites

4-Cumylphenol 

(4-(2-Phenylisopropyl)

phenol)

CMAR: Detergent metabolite < 0.2 0/14 0/15 0/29

4-Nonylphenol (sum of 

all isomers), 4-(2,4-dimethylheptan-3-yl)

phenols

CMAR: Detergent metabolite < 1.6 7/14, E 0.20 

to E 0.34

1/15, E 0.09 8/29, E 0.09 

to E 0.34

4-Nonylphenol diethoxylates (NP2EO)CMAR: Detergent metabolite < 3.2 6/14, E 0.93to 

E 2.11

0/15 6/29, E 0.93 

to E 2.11

4-Nonylphenol monoethoxylates (NP1EO)CMAR: Detergent metabolite < 1.6 4/14, E 0.32 

to E 0.44

0/15 4/29, E 0.32 

to E 0.44

4-n-Octylphenol CMAR: Detergent metabolite < 0.2 0/14 0/15 0/29

4-tert-Octylphenol CMAR: Detergent metabolite < 0.4 0/14 0/15 0/29

4-tert-Octylphenol 

diethoxylates (OP2EO) 

CMAR: Detergent metabolite < 0.5 3/14, E 0.092 

to E 0.162

1/15, E 0.084 4/29, E 0.084 

to E 0.162

4-tert-Octylphenol 

monoethoxylates 

(OP1EO) 

CMAR: Detergent metabolite < 1.0 0/14 0/15 0/29

Solvents

Isophorone Solvent < 0.2 8/14, E 0.010 

to E 0.034

2/15, E 0.013 

and 

E 0.014

10/29, 

E 0.010 to 

E 0.034

Isopropylbenzene 

(cumene) 

NO, crude oil; CMAR: solvent found or used in 

manufacture of herbicides, asphalt primer, cement, petroleum-based fuels (aviation and automobile), sealants, varnish, paint thinner, acetone, 

and phenol

< 0.2 1/14, E 0.006 2/15, E 0.008 

and E 

0.010

3/29, E 0.006 

to E 0.010

Tetrachloroethene (PCE) Solvent, degreaser; also veterinary anthelmintic < 0.4 0/14 0/15 0/29

Tributyl phosphate CMAR: solvent and plasticizer for cellulose esters 

such as nitrocellulose and cellulose acetate, 

solvent solvent in inks, synthetic resins, gums, 

adhesives (namely for veneer plywood) and 

herbicide and fungicide; anti-foaming agent in 

detergent solutions, and in various emulsions, 

paints, and adhesives.

< 0.2 1/14, E 0.013 0/15 1/29, E 0.013

Pesticides

Atrazine CMAR: herbicide, crop and noncrop areas < 0.2 0/14 0/15 0/29

Bromacil CMAR: herbicide < 0.2 0/14 0/15 0/29

Carbaryl CMAR: insecticide < 0.2 0/14 0/15 0/29

Carbazole CMAR: insecticide, also dye manufacturing < 0.2 0/14 0/15 0/29
Water Quality 123

Table 17. Characteristics and summary of detections of organic wastewater compounds associated with groundwater samples 

collected from selected wells in the Pearce Creek Dredge Material Containment Area and vicinity, 2010.—Continued

[NO, naturally occurring source; CMAR, commercial, manufacturing, agricultural, and (or) residential source(s); PAH, polycyclic aromatic hydrocarbon; μg/L, 

micrograms per liter; E, estimated concentration with greater than normal uncertainty; <, less than; DQI, data-quality issues preclude interpretation of data, see 

text for in-depth discussion; wastewater compound analytical method described in Zaugg and others (2002)]

Analyte Major use(s) and (or) source(s)1

Laboratory 

reporting level 

(μg/L)

Number of detections (X), and range in 

concentrations

Observation 

wells (X/14)

Domestic 

wells (X/15)

All wells 

(X/29)

Chlorpyrifos CMAR: insecticide < 0.2 0/14 0/15 0/29

Diazinon CMAR: Insecticide, restricted use, noncrop areas 

as of 1998–2004

< 0.2 0/14 0/15 0/29

1,4-Dichlorobenzene CMAR: insecticide, fumigant, moth repellant, sanitation deodorizer, disinfectant < 0.2 DQI DQI DQI

3,4-Dichlorophenyl isocyanateMetabolite of diuron herbicide, in selected crop and 

noncrop areas

< 1.6 0/14 0/15 0/29

d-Dichlorvos CMAR: insecticide in crop (grain/seed storage) and 

noncrop (plant/pet) uses

< 0.2 0/14 0/15 0/29

d-Limonene NO, citrus fruit terpene; CMAR: fungicide, manufacturing 

< 0.2 0/14 0/15 0/29

Metalaxyl CMAR: fungicide < 0.2 0/14 0/15 0/29

Metolachlor CMAR: herbicide, crop and noncrop areas < 0.2 0/14 0/15 0/29

Pentachlorophenol CMAR: insecticide, fungicide, wood preservative < 0.8 3/14, E 0.051 

to E 0.064

0/15 3/29, E 0.051 

to E 0.064

Prometon CMAR: herbicide, crop and noncrop areas < 0.2 1/14, E 0.032 0/15 1/29, E 0.032

N,N-Diethyltoluamide 

(DEET)

CMAR: mosquito repellent, insecticide ingredient < 0.2 0/14 2/15, E 0.11 

and 0.51

2/29, E 0.11 

and 0.51

Fragrances and flavorants 

Acetophenone (1-Phenylethanone)Fragrance and or flavoring in detergent, tobacco, 

beverages, fruits, also a solvent 

< 0.4 0/14 0/15 0/29

Benzophenone (Diphenylmethanone)CMAR: Ultaviolet light damage inhibitor in film, 

perfume, and soap manufacturing 

< 0.2 0/14 0/15 0/29

1,3,4,6,7,8-Hexahydro-4,6,6,7,8,8- 

hexamethylcyclopentaγ-2-benzopyran 

(HHCB) 

CMAR: fragrance (musk), flavoring < 0.2 0/14 0/15 0/29

Indole NO, animal, coal tar byproduct; CMAR: fragrance < 0.2 1/14, E 0.013 1/15, E 0.014 2/29, 

E 0.013 

and 

E 0.014

3-Methyl-1H-indole 

(skatole) 

NO, fecal indole; CMAR: fragrance, essential oil < 0.2 1/14, E 0.006 0/15 1/29, E 0.006

Isoborneol NO, exoisomer of borneal (terpene) in plants and 

insects; CMAR: fragrance, flavoring 

< 0.2 0/14 0/15 0/29

Menthol NO, plant compound; CMAR: fragrance, flavoring, 

also pharmaceuticals—antipruritics, decongestants, and analgesics

< 0.2 0/14 1/15, E 0.022 1/129, 

E 0.022

Methyl salicylate NO, plant ester; CMAR: fragrance, liniment, 

flavoring, or as an odor-masking agent for some 

organophosphate pesticides

< 0.2 0/14 0/15 0/29
124 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

Table 17. Characteristics and summary of detections of organic wastewater compounds associated with groundwater samples 

collected from selected wells in the Pearce Creek Dredge Material Containment Area and vicinity, 2010.—Continued

[NO, naturally occurring source; CMAR, commercial, manufacturing, agricultural, and (or) residential source(s); PAH, polycyclic aromatic hydrocarbon; μg/L, 

micrograms per liter; E, estimated concentration with greater than normal uncertainty; <, less than; DQI, data-quality issues preclude interpretation of data, see 

text for in-depth discussion; wastewater compound analytical method described in Zaugg and others (2002)]

Analyte Major use(s) and (or) source(s)1

Laboratory 

reporting level 

(μg/L)

Number of detections (X), and range in 

concentrations

Observation 

wells (X/14)

Domestic 

wells (X/15)

All wells 

(X/29)

7-Acetyl-1,1,3,4,4,6-

hexamethyl-1,2,3,4-

tetrahydro-naphthalene 

(AHTN) 

CMAR: fragrance (musk) < 0.2 0/14 0/15 0/29

Plasticizers

Bis(2-ethylhexyl) phthalateCMAR: plasticizer, antioxidant < 0.2 DQI DQI DQI

Bisphenol A CMAR: plasticizer, antioxidant < 0.4 DQI DQI DQI

Diethyl phthalate CMAR: plasticizer for polymers and resins < 0.2 DQI DQI DQI

Triethyl citrate (ethyl 

citrate) 

Plasticizer, cosmetics, food additive, food contact 

material, medical, and pharmaceutical uses; 

cigarette filters, cosmetics, lacquers

< 0.2 0/14 0/15 0/29

Triphenyl phosphate Platicizer, also used as antioxidant flame retardant 

in resin, wax, and roofing paper

< 0.2 0/14 0/15 0/29

Tri(2-butoxyethyl) phosphate Plasticizer < 0.320 0/14 1/15, E 0.145 1/29, E 0.145

Pharmaceuticals 

Camphor NO, plant terpenoid; CMAR: Pharmaceutical 

(ointments), also flavoring, fragrance, and moth 

repellent

< 0.2 2/14, E 0.018 

and E 0.021

0/15 2/29, 

E 0.018 

and 

E 0.021

Caffeine NO: plant insecticide; CMAR: psychoactive 

stimulant 

< 0.8 0/14 0/15 0/29

Cotinine NO, Nicotine metabolite and biomarker < 0.2 0/9 0/15 0/24

Isoquinoline CMAR: used in manufacture of antifungals and 

insectidies, as well as in dyes, paints, and rubber 

products; also extraction solvent for resins and 

terpenes, and corrosion inhibitor

< 0.2 0/14 0/15 0/29

Triclosan CMAR: antimicrobial disinfectant used in deodorants, toothpastes, shaving creams, mouth washes, 

and cleaning supplies

< 0.2 0/14 0/15 0/29

Flame retardants

2,2 ́,4,4 ́-tetrabromodiphenyl ether (BDE 47)CMAR: flame retardent < 0.3 0/14 0/15 0/29

Tri(2-chloroethyl) phosphate (FYROL CEF) 

CMAR: flame retardant < 0.2 0/14 0/15 0/29

Tri(dichloroisopropyl)

phosphate (FYROL 

PCF) 

CMAR: flame retardant < 0.2 0/14 0/15 0/29
Water Quality 125

detergent additives and (or) their metabolites (4 of 8 compounds), and solvents (3 of 4 compounds). Few pesticides and 

fragrances or flavorants, plasticizers, or pharmaceuticals, and 

no flame retardants or antioxidants were detected.

Most of the detected wastewater compounds have natural 

as well as synthetic origins (table 17), and a number of these 

compounds have been shown to occur in organic-rich siltyclay sediments such as those found in the upper bay (Hartwell 

and Hameedi, 2007). As such, they also reflect compounds 

which generally are resistant to degradation, and thus, could 

still be emanating from the sediment and Elk River water initially deposited in the DMCA during the time of operation. 

Wastewater compounds were minimally detected in 5 of 

the 7 surveyed wells in the Magothy aquifer in WVS. Two of 

the 7 wells had zero compounds detected, 2 wells had 1 compound detected, 2 wells had 3 compounds detected, and 1 well 

had 4 compounds detected (fig. 79). Wastewater compounds 

were detected in 7 of 8 wells screened in the Magothy aquifer 

and surveyed within the property boundary of the DMCA. 

Three to five compounds were detected in three wells. The 

highest number of detections of wastewater compounds in the 

Magothy aquifer occurred in the western and central part of 

the DMCA at well 137 (7 compounds detected), well 139 

(13 compounds detected), well 157 (14 compounds detected), 

and well 144 (18 compounds detected) (fig. 79). Southeast of 

the DMCA property boundary, three compounds were detected 

in well CE Dd 153, which is screened in the Magothy aquifer.

In the upper Patapsco aquifer shallow water-bearing zone 

(fig. 80), all but one surveyed well (CE Dd 154) was located in 

WVS. Of the eleven surveyed wells, 5 had zero detections of 

wastewater compounds; 5 wells had between 1 and 3 detections, and 1 well (CE Dd 160) had 12 detections. Wastewater 

compounds detected in the Magothy aquifer in the western 

half of the DMCA may have been transported within the 

anoxic flow from the DMCA west beneath WVS and vertically downward to the upper Patapsco aquifer shallow waterbearing zone (fig. 81); this may account for the high number 

of wastewater compounds detected in groundwater analyzed 

from well CE Dd 160.

Groundwater contaminated by residential wastewater 

treatment, landfill, or septic effluents in other shallow aquifers, often includes measurable or detectable concentrations 

of wastewater compounds associated with human consumption and residential land-use activities—for example, pharmaceuticals or residential pesticide use (Barnes and others, 

2008; Focazio and others, 2008; Standley and others, 2008). 

However, with the exception of N,N-diethyltoluamide (DEET) 

and menthol found in the groundwater sample from domestic well CE Dd 165, and a relatively high concentration of 

DEET found in the groundwater sample from domestic well 

CE Dd 172, few of these types of wastewater compounds 

were detected in shallow domestic wells in WVS. The two 

human-use wastewater compounds detected in groundwater 

at well CE Dd 165 could reflect local use because the well 

Table 17. Characteristics and summary of detections of organic wastewater compounds associated with groundwater samples 

collected from selected wells in the Pearce Creek Dredge Material Containment Area and vicinity, 2010.—Continued

[NO, naturally occurring source; CMAR, commercial, manufacturing, agricultural, and (or) residential source(s); PAH, polycyclic aromatic hydrocarbon; μg/L, 

micrograms per liter; E, estimated concentration with greater than normal uncertainty; <, less than; DQI, data-quality issues preclude interpretation of data, see 

text for in-depth discussion; wastewater compound analytical method described in Zaugg and others (2002)]

Analyte Major use(s) and (or) source(s)1

Laboratory 

reporting level 

(μg/L)

Number of detections (X), and range in concentrations

Observation 

wells (X/14)

Domestic 

wells (X/15)

All wells 

(X/29)

Antioxidants

3-t-Butyl-4-hydroxyanisole (BHA) CMAR: antioxidant, food preservative < 0.2 0/14 0/15 0/29

5-Methyl-1H-benzotriazole CMAR: antioxidant in antifreeze, anticorrosive < 1.6 0/9 0/15 0/24

Chlorination byproducts

Bromoform (tribromomethane) CMAR: water-chlorination byproduct < 0.2 0/14 0/15 0/29

Ubiquitous (multiple) source and use

Phenol NO, plants and coal tar; CMAR: Used to create 

plastics, polycarbonates, resins, nylon, nonionic 

detergents, drugs, most notably aspirin, as well 

as many herbicides and pharmaceuticals, oral 

anesthetics and analgesics, and antiseptics.

< 0.2 DQI DQI DQI

1

 Modified from similar source and use categorizations from Buxton and Kolpin (2002), Kolpin and others (2002), Focazio and others (2008), Ferrell 

(2009), and Tertuliani and others (2008).
126 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area 127 75°59' 76° 39°26' 39°25'30"

Elk River Pearce Creek Lake

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

Crystal Beach

Pond Neck Road

West View Shores

Bay View Estates

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

2 4

6

8

10

10

8

6

1

0

1 0

0 0

0

01

1

0

0 0

0

0 2

3 

4

3

3

1

0 0

4

4

4

5

2

5

EXPLANATION

Potentiometric surface contour in the Magothy aquifer—Shows altitude 

at which water would have stood in tightly cased wells, May 19–20, 2010. Dashed where approximately located. Contour interval 2 feet. Datum is North American Vertical Datum of 1988

Direction of groundwater flow

Locally perched aquifer well—Number indicates number of pesticides detected Magothy aquifer well—Number indicates number of pesticides detected Surface-water site—Number indicates number of pesticides detected 

6 4

3

1

Figure 75. Number of pesticides detected with low-level analytical methods in water-quality samples collected from selected surface waters and from survey wells completed in the perched water-bearing zone or Magothy aquifer in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11.
Water Quality 127

Magothy aquifer

Fill - Matawan Formation

Upper Patapsco aquifer

shallow water-bearing zone

Upper Patapsco aquifer

deep water-bearing zone

172

Groundwater divide

Well

identifier

4

1

2

--

--

0 1

--

0

0

0

--

3

--

1

1

0

2

1

5

0

5025

-25-50-75

-100-125-150-175-200-225-250

0

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000

Distance, in feet

4,500 5,000 5,500 6,000 6,500 7,000 8,000 8,500 9,000 7,500

A

WEST

A'

EAST

193

192191

157 158 124 139122

151 81

163

168

165

164 171 142

128

178

160

Confining unit

Confining unit

Elk

River

Confining unit

Altitude, in feet above or below North American Vertical Datum of 1988

VERTICAL EXAGGERATION x 20

Number of pesticide compounds detected

—

--, No sample collected 

Direction of groundwater flowPrecipitation/recharge

EXPLANATION

1

Figure 76. Hydrogeologic section showing the number of pesticides detected with low-level analytical methods in water-quality samples along line A–A’ and 

collected from survey wells completed in the Magothy aquifer or upper Patapsco aquifer shallow or deep water-bearing zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11. (Location of line of section A–A’ is shown in figure 39.)
128 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

pit is located inside the house and was flooded by an internal 

water-supply line break in 2008. The high concentration of 

DEET found in domestic well CE Dd 172 also could reflect 

local residential use. DEET was the only wastewater compound detected in groundwater from this well. DEET was only 

detected in wells CE Dd 165 and CE Dd 172; DEET was not 

detected in any wells in the DMCA. 

Other than DEET and menthol, all other wastewater 

compounds detected in groundwater from domestic wells in 

the WVS also were detected in groundwater from DMCA 

observation wells. In addition, they were detected at a greater 

frequency and (or) often-higher concentration in samples from 

DMCA wells compared to samples from domestic-supply 

wells (table 17). 

In the upper Patapsco aquifer deep water-bearing zone 

only one well (CE Dd 170) was included in the survey. Two 

wastewater compounds were detected in well CE Dd 170. 

In summary, the wastewater compound results indicate the 

occurrence of a high number of similar compounds in and 

beneath the DMCA and in the upper Patapsco aquifer shallow water-bearing zone along the groundwater flow path from 

the DMCA to WVS, which is consistent with the patterns 

observed for many other water-quality constituents in this 

study. Thus, detections of wastewater compounds also support 

Figure 77. Hydrogeologic section showing the number of pesticides detected with low-level methods in water-quality 

samples along line B–B’ and collected from survey wells completed in the Magothy aquifer in the Pearce Creek Dredge 

Material Containment Area (DMCA) and vicnity, Cecil County, Maryland, 2010–11. (Location of line of section B–B’ is shown 

in figure 39.)

--

3

--

3

--

--

--

1

--

2

Groundwater divide

Altitude, in feet above or below North American Vertical Datum of 1988

B

NORTH

B'

SOUTH

Well

identifier

Elk River

VERTICAL EXAGGERATION x 20

126136 137 138

147

145

146 149

157 158

-250

-225

-200

-175

-150

-125

-100

-75

-50

-25

0

25

50

Distance, in feet

Magothy aquifer

Fill - Matawan Formation

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 5,000 5,500

Confining unit

Upper Patapsco aquifer

shallow water-bearing zone

Confining unit

Upper Patapsco aquifer

deep water-bearing zone

Confining unit

Number of pesticide compounds detected—

 --, No sample collected 

Direction of groundwater flow

Precipitation/recharge

EXPLANATION

1
Water Quality 129 Figure 78. Number of pesticides detected with low-level analytical methods in water-quality samples collected from selected surface waters and from survey wells completed in the upper Patapsco aquifer shallow water-bearing zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11.

127

141

Elk River Pearce Creek Lake

Crystal Beach

Pond Neck Road

West View Shores

Bay View Estates

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

75°59' 76°

39°26'

39°25'30"

2

4

4

6

6

8

8

2

4

4 1 1

0

0

0

1

3

2

4

0

1

1

1

0

0

1

3

EXPLANATION

Potentiometric surface contour in the upper Patapsco aquifer, shallow water-bearing 

zone— Shows altitude at which water would have stood in tightly cased wells, May 19–20, 2010. Dashed where approximately located. Contour interval 2 feet. Datum is North American Vertical Datum of 1988

Direction of groundwater flow

Upper Patapsco aquifer well, shallow water-bearing zone—Number 

indicates number of pesticides detected 

6 1
130 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area Figure 79. Number of wastewater compounds detected in water-quality samples collected from selected surface waters and from survey wells completed in the perched groundwater zone or Magothy aquifer in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11. 127 75°59' 76° 39°26' 39°25'30"

Elk River Pearce Creek Lake

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

Crystal Beach

Pond Neck Road

West View Shores

Bay View Estates

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

2 4

6

8

10

10

8

6

3

0

0 1

1

4

7

18

3

4

0

3

14 13 5

3

3

0 1

1

EXPLANATION

Potentiometric surface contour in the Magothy aquifer—Shows altitude 

at which water would have stood in tightly cased wells, May 19–20, 2010. Dashed where approximately located. Contour interval 2 feet. Datum is North American Vertical Datum of 1988

Direction of groundwater flow

Locally perched aquifer well—Number indicates number of wastewater 

compounds detected 

Magothy aquifer well—Number indicates number of wastewater 

compounds detected 

6 18

7
Water Quality 131 Figure 80. Number of wastewater compounds detected in water-quality samples collected from selected surface waters and from survey wells completed in the upper Patapsco aquifer shallow water-bearing zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11. 

127

141

Elk River Pearce Creek Lake

Crystal Beach

Pond Neck Road

West View Shores

Bay View Estates

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

75°59' 76°

39°26'

39°25'30"

2

4

4

6

6

8

8

2

0

0

0

1

0

12

2

2

3 0

0

0

0

12

2

2

0

3

EXPLANATION

Potentiometric surface contour in the upper Patapsco aquifer, shallow water-bearing 

zone— Shows altitude at which water would have stood in tightly cased wells, May 19–20, 2010. Dashed where approximately located. Contour interval 2 feet. Datum is North American Vertical Datum of 1988

Direction of groundwater flow

Upper Patapsco aquifer well, shallow water-bearing zone —Number 

indicates number of wastewater compounds detected 

6 1
132 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment AreaFigure 81. Hydrogeologic section showing the number of wastewater compounds detected in water-quality samples along line A–A’ and collected from selected surface waters and from selected wells completed in the perched water-bearing zone, Magothy aquifer, or upper Patpsco aquifer shallow or deep water-bearing 

zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11. (Location of line of section A–A’ is shown in figure 39.)

Magothy aquifer

Fill - Matawan Formation

Upper Patapsco aquifer

shallow water-bearing zone

Upper Patapsco aquifer

deep water-bearing zone

Groundwater divide

Well

identifier

--

--

14

--

13 5

--

2

1

0

--

12

--

0

1

3

--

--

--

1

172

5025

-25-50-75

-100-125-150-175-200-225-250

0

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000

Distance, in feet

4,500 5,000 5,500 6,000 6,500 7,000 8,000 8,500 9,000 7,500

A

WEST

A'

EAST

193

192 191

157 158 124 139 122

151 81

163

168

165

164 171 142

128

178 160

Confining unit

Confining unit

Elk

River

Confining unit

Altitude, in feet above or below North American Vertical Datum of 1988

VERTICAL EXAGGERATION x 20

Number of wastewater compounds detected

—

--, No sample collected 

Direction of groundwater flowPrecipitation/recharge

EXPLANATION

1
Water Quality 133

the conclusion that groundwater flow from the DMCA affects 

the quality of groundwater at depths used for domestic supplies beneath WVS.

Quality of Water for Drinking-Water Supplies

Single-residential domestic water supplies such as those 

in WVS are not regulated under the Federal Safe Drinking 

Water Act (SDWA).4 However, local groundwater is the major 

source of domestic-well water supplies in vicinity of the 

DMCA. Thus, although the USEPA SDWA standards have no 

regulatory bearing on the use of private residential wells for 

drinking or other household purposes, they can be used as a 

guide to indicate whether or not local groundwater supplies 

are impaired. 

The 2009 Edition of the U.S. Environmental Protection 

Agency Drinking Water Standards and Health Advisories 

(U.S. Environmental Protection Agency, 2009) was used to 

evaluate the quality of the groundwater in drinking-water 

supplies. All USEPA SDWA standards and advisories, including Maximum Contaminant Levels (MCLs), Health Advisory 

Levels (HALs), and Secondary Drinking Water Regulations 

(SDWRs), were considered, provided the data were collected. 

The MCL, HAL, or SDWR is included with the collected 

water-quality data for every constituent that has a Federal 

standard (appendix B, table B3). The term “standard” as used 

hereafter in the report will be a generic reference to refer to 

one or all three of the sets of standards above. For brevity, 

results are provided in general terms for those constituents 

that were less than the maximum allowable or recommended 

levels, and only those water-quality constituents with concentrations that were greater than maximum allowable or 

recommended levels (MCLs, HALs, or SDWR), are discussed 

below.

Fifty-eight water-quality constituents measured as 

part of this study have a 2009 SDWA standard (U.S. Environmental Protection Agency, 2009), which was used to 

evaluate the suitability of sampled water for potable use 

(appendix B, table B3). Concentrations of forty-two of these 

constituents were measured at concentrations below the 

maximum allowable or recommended levels in all samples 

collected for this study, thus they did not exceed the USEPA 

SDWA standards. The majority of these 42 constituents were 

either regulated pesticides or wastewater compounds, which 

generally were detected at concentrations below their individual LRLs. Included in this group are five wastewater compounds whose concentrations in groundwater samples possibly were positively biased by contamination during or after 

sample collection (see Data Quality, this report). However, 

as with the other 37 constituents in this group, their concentrations were less than the maximum allowable or recommended 

levels for their respective 2009 USEPA SDWA standards. 

4

 Serves fewer than 25 individuals and (or) has fewer than 15 service 

connections (Federal Register, 1998).

Sixteen constituents had concentrations in groundwater and (or) surface-water samples that were greater than 

the maximum allowable or recommended levels for a 2009 

USEPA SDWA standard (table 18). These constituents include 

the general physical or chemical characteristics common to 

groundwater–for example, TDS and pH–as well as selected 

inorganic constituents that generally are less than the maximum allowable or recommended levels for the standards in 

most groundwater–for example, the trace elements beryllium, 

thallium, nickel, and arsenic. Measured concentrations greater 

than the allowable or recommended levels established in standards, are hereafter termed exceedances, these include MCLs, 

HALs, and SDWR criteria, and form an initial basis for the 

following discussion. 

Maximum Contaminant Levels

Groundwater concentrations for four trace elements—

arsenic, beryllium, cadmium, and thallium—were greater than 

their respective MCLs at one or more observation or domestic 

wells (table 18). A brief summary for each of these trace elements follows. 

Arsenic (MCL 10 μg/L): Only one observation well, (CE 

Dd 122) located in the DMCA, yielded a sample with a concentration of arsenic greater than the MCL. The concentration 

of arsenic was 58.7 μg/L and was confirmed and replicated. 

Concentrations of arsenic, ranging from approximately 4 to 

9 μg/L, were measured in wells downgradient from this well 

in the upper Patapsco aquifer shallow water-bearing zone 

beyond the western side of the DMCA and in domestic-supply 

wells in WVS (fig. 74). These concentrations (ranging from 4 

to 9 μg/L) are below the MCL for arsenic, but they are greater 

than concentrations found in natural groundwater for the 

aquifer. 

Beryllium (MCL 4 μg/L): Six observation wells (CE Dd 

81, 122, 133, 145, 160 and 192) and two domestic-supply 

wells (CE Dd 161 and CE Dd 164) had concentrations of 

beryllium greater than the MCL. In addition, one observation 

well (CE Dd 129) and one domestic-supply well (CE Dd 176) 

had beryllium concentrations at or within 10 percent of the 

MCL (appendix B, table B3). Beryllium concentrations also 

appeared to be higher—than concentrations common in natural groundwater near the study area—in the upper Patapsco 

aquifer shallow water-bearing zone beneath the DMCA and 

downgradient in groundwater beneath WVS (fig. 72, beryllium 

concentrations of approximately 4–18 μg/L).

Cadmium (MCL 5 μg/L) and thallium (MCL 2 μg/L): 

One observation well (CE Dd 192) had concentrations of 

cadmium (5.12 μg/L) and thallium (2.56 μg/L) (as well as 

beryllium, 6.7 μg/L) above their respective MCLs. 

Exceedances of the MCLs for beryllium, cadmium, and 

thallium and elevated concentrations of arsenic (compared to 

natural groundwater) could reflect enhanced reduction and 

their release from sediments within the DMCA. The occurrence of concentrations of beryllium and arsenic greater than 

or near the MCLs in groundwater in the study area were 
134 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

shown to be highly localized (generally the western part of the 

DMCA and WVS), and related to Fe(III)-reducing conditions 

associated with the mixing of anoxic DMCA-source waters 

and oxic (other source) groundwater (see Extended Implications of Reduction-Oxidation Processes on Groundwater 

Quality, this report). Cadmium and thallium concentrations 

greater than the MCLs occurred simultaneously with beryllium concentration greater than the MCL in one observation 

well—CE Dd 122. This well is completed at the base of the 

upper Patapsco aquifer shallow water-bearing zone, where 

extreme reducing conditions occurred.

Health Advisory Levels

Six constituents, manganese, nickel, sodium, sulfate, 

strontium, and zinc, exceeded (were greater than recommended levels) USEPA SDWA HALs (table 18) in some wells. 

Strontium, zinc, and nickel exceeded their respective HALs in 

2, 4, and 22 percent of the 50 wells sampled, respectively. In 

contrast, sulfate, sodium, and manganese exceeded the HAL 

in 44, 66, and 72 percent of the 50 wells sampled (table 18; 

appendix B, table B3). 

Secondary Drinking-Water Regulations 

Eight constituents (or properties), aluminum, chloride, 

iron, manganese, pH, sulfate, TDS, and turbidity, exceeded 

SDWRs in some wells (table 18). Iron, manganese, and pH 

values exceeded the SDWR in 90, 90, and 92 percent 

of the sampled wells respectively (table 18; appendix B, 

table B3). Aluminum, chloride, TDS, and sulfate concentrations exceeded the SDWR in fewer wells (32, 32, 56, and 

52 percent, respectively) than iron, manganese, and pH. 

Samples from 10 percent of the sampled wells exceeded the 

SWDR for turbidity; which likely is an artifact of sampling 

rather than an in-situ condition of groundwater (table 18).

The evaluation of the quality of groundwater in the 

DMCA and vicinity based on USEPA SDWA standards indicates that the pH, metals (numerous, but notably iron and manganese), and TDS are of concern (table 18). To improve the 

understanding of the effect of reduced (chemically) groundwater on the quality of drinking water currently (2010–11) used 

for WVS supplies, the exceedance data for domestic wells 

(table 18) was combined with their TEAP classification 

(table 15). In combination, the data indicate the effects of 

reduced groundwater on domestic supplies depend upon the 

degree of reduction (table 19). As the degree of reduction in 

groundwater increased—from oxic to mixed to anoxic—the 

number and type of impairments and number of chemical constituents that exceeded the USEPA SDWA standards increased. 

The concentration of TDS in water used for domestic supplies 

was greater than the USEAP SDWA standard mainly when 

that water is anoxic because there is then sufficient dissolved 

manganese, iron, and (or) sulfate concentrations greater than 

maximum allowable or recommended levels. Other metals, 

such as aluminum, beryllium, and nickel (table 19), also were 

greater than their respective USEPA SDWA standards when 

groundwater is withdrawn for supplies from wells completed 

in a mixed anoxic-oxic zone (fig. 66, well CE Dd 164, 

Mn–O2

–Fe(III), or downgradient of an anoxic zone (fig. 67, 

well CE Dd 176, anoxic Fe(III)). Data were not collected from 

any supply well in the highest or most severe reduction zone 

(anoxic-Fe) because most deep supply wells in WVS appear to 

have been abandoned and no longer exist. However, groundwater from observation wells completed in or downgradient 

from the anoxic-Fe zone (fig. 66, wells CE Dd 81, and CE Dd 

128, 142, and 160) contained elevated concentrations of other 

metals, in addition to iron and manganese, at concentrations 

that exceed their USEPA SDWA standards (appendix B, 

table B3). 

Acidity of Groundwater

Whereas the effect of the DMCA on groundwater quality 

used for domestic supplies could be addressed, the effect of 

the DMCA on Elk River is only partially addressed. Information on the quality of groundwater that discharges into streams 

before they enter Elk River, or that eventually directly discharges through bed sediments into Elk River, is unavailable 

as groundwater samples were not collected in stream or riverbed. The quality of domestic supplies or Elk River water can 

be defined and compared through an accurate determination 

of the net acidity of groundwater, where the latter is derived 

on the basis of the pH, the concentrations of total dissolved 

redox-sensitive metals (iron—(Fe2+ and Fe3+), manganese—

Mn2+, aluminum—Al3+), and if the pH exceeds 4.3, alkalinity 

(bicarbonate, HCO3

–

, and carbonate CO3

2–) of groundwater and 

surface water.

Influence on the Elk River

On the basis of data collected in this study, groundwater likely to either be discharging through bed sediments to 

streams, which then discharge to Elk River, or that likely 

discharges into bed sediments into Elk River, is anoxic. The 

implications of the possible effects of DMCA groundwater 

discharge on either local streams or the Elk River will differ 

depending on the redox condition of the stream or river and 

bed-sediment redox conditions. If the stream or river becomes 

anoxic for an extended period of time, reduced metals that 

have accumulated in underlying sediments likely will be 

released into the river. However, if the stream or river maintains a generally oxic state throughout, then reduced metals 

being transported in groundwater will oxidize upon exposure 

to oxic sediments or river water, form insoluble precipitates, 

and accumulate in the river bed sediments. 

Whereas verifying either the oxic or anoxic scenario for 

groundwater discharge into the local stream or Elk River as 

described above was beyond the scope of this study, verifying 
Water Quality 135

Table 18. Summary of water-quality constituents with concentrations exceeding 2009 U.S. Environmental Protection Agency (USEPA) 

Safe Drinking Water Act (SDWA) standards for at least one groundwater or surface-water site in the Pearce Creek Dredge Material 

Containment Area and vicinity, 2010–11.

[NTRU, nephelometric turbidity ratio unit; mg/L, milligrams per liter; dissolved, sample filtered through an encapsulated and pleated 0.2-micron effective pore 

size, polysulfonyl filter; μg/L, micrograms per liter; SDWR, Secondary Drinking Water Standard (aesthetic—generally color, odor, and (or) taste); 

HAL, Health Advisory Level; MCL, Maximum Contaminant Level; LRL, laboratory reporting level; <, less than; E, estimated]

Water-quality 

constituent1

USEPA SDWA 

standard

Type of 

standard

Groundwater 

(by well type) or 

surface water

Number of 

sites with 

sample concentrations 

that exceeded 

the standard/

total number of 

sampling sites2

Range in 

concentrations 

for all sites

Samples whose 

concentrations exceeded 

standard 

Arsenic (μg/L) 10 MCL Observation 1/35 < 0.10 to 58.7 Well CE Dd 122, reanalysis 

confirmed, with replication but about half the 

value

Domestic supply 0/15 < 0.10 to 8.71

Surface waters 0/2 0.25 to 0.35

Beryllium (μg/L) 4 MCL Observation 6/35 0.010 or < 0.04 

to 18 

Wells CE Dd 81, 122, 133, 

145, 160, and 192 

Domestic supply 2/15 E 0.033 or 

< 0.04 to 5.8

Wells CE Dd 161 and 164

Surface waters 0/2 < 0.08 to 0.10

Cadmium (μg/L) 5 MCL Observation 1/35 < 0.04 to 5.12 Well CE Dd 192

Domestic supply 0/15 < 0.04 to 2.86

Surface waters 0/2 < 0.10 to 0.19

Thallium (μg/L) 2 MCL Observation 1/35 < 0.06 to 2.56 

or < 7.20

Well CE Dd 192, reanalysis 

confirmed exceedance of 

standard

Domestic supply 0/15 < 0.12 to 0.42 

or < 1.20

Surface waters 0/2 < 0.06 to 

< 0.12

Manganese (μg/L) 300 HAL, dietary Observation 26/35 69.3 to 222,000 Too numerous to list3

, also 

24 of 36 wells exceeded 

1,000 mg/L 1 day and 10 

day child HAL

Domestic supply 10/15 46.5 to 81,200 Except for wells CE Dd 

163, 168, 170, 171, and 

172, all wells exceeded 

standard, also 9 of 15 

wells also exceeded 

1,000 mg/L 1-day and 

10-day child HAL

Surface waters 1/2 5.0 to 823 Pearce Creek Lake

50 SDWR Observation 35/35 69.3 to 222,000 All wells exceeded standard

Domestic supply 14/15 46.5 to 81,200 Except for well CE Dd 

168, all wells exceeded 

standard

Surface waters 1/2 5.0 to 823 Pearce Creek Lake
136 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

Table 18. Summary of water-quality constituents with concentrations exceeding 2009 U.S. Environmental Protection Agency Safe 

Drinking Water Act standards for at least one groundwater or surface-water site in the Pearce Creek Dredge Material Containment 

Area and vicinity, 2010–11.—Continued

[NTRU, nephelometric turbidity ratio unit; mg/L, milligrams per liter; dissolved, sample filtered through an encapsulated and pleated 0.2-micron effective 

pore size, polysulfonyl filter; μg/L, micrograms per liter; SDWR, Secondary Drinking Water Standard (aesthetic—generally color, odor, and (or) taste); HAL, 

Health Advisory Level; MCL, Maximum Contaminant Level; LRL, laboratory reporting level; <, less than; E, estimated]

Water-quality 

constituent1

USEPA SDWA 

standard

Type of 

standard

Groundwater 

(by well type) or 

surface water

Number of 

sites with 

sample concentrations 

that exceeded 

the standard/

total number of 

sampling sites2

Range in 

concentrations 

for all sites

Samples whose 

concentrations exceeded 

standard 

Nickel (μg/L) 100 HAL Observation 9/35 E 0.2 or < 0.4 

to 780

Wells CE Dd 81, 122, 125, 

127, 128, 129, 153, 160, 

and 192

Domestic supply 2/15 < 0.4 to 400 Wells CE Dd 161 and 179

Surface waters 0/2 2.2 to 12

Sodium (mg/L) 20 HAL, dietary Observation 25/35 4.83 to 397 Too numerous to list3

, 

also 19/36 wells exceed 

SDWR (60 mg/L)

Domestic supply 8/15 4.48 to 169 Wells CE Dd 161, 164, 166, 

174, 176, 177, 178, and 

179. Also wells CE Dd 

161, 164, 177, and 179 

exceed SDWR (60 mg/L)

Surface waters 1/2 8.06 to 516 Elk River, also exceeded 

SDWR

Sulfate (mg/L) 500 HAL Observation 20/35 < 0.09 to 

E 3,730

Too numerous to list3

Domestic supply 2/15 11 to 1,270 Wells CE Dd 161 and 179

Surface waters 0/2 27 to 170

250 SDWR Observation 22/35 < 0.09 to 

E 3,730

Too numerous to list3

Domestic supply 4/15 11 to 1,270 Wells CE Dd 161, 176, 177, 

and 179

Surface waters 0/2 27 to 170

Strontium (μg/L) 4,000 HAL Observation 1/35 42 to 4,300 Well CE Dd 154

Domestic supply 0/15 37 to 730

Surface waters 0/2 45 to 550

Zinc (μg/L) 2,000 HAL Observation 2/35 E 1.1 or < 2 to 

2,400

Wells CE Dd 122 and 160

Domestic supply 0/15 E 2 to 880

Surface waters 0/2 < 5 to 48

pH (Standard 

units), raw 

water

6.5 to 8.5 SDWR Observation 31/35 3.9 to 6.8 Too numerous to list3

, 

below lower limit of 

standard

Domestic supply 15/15 4.2 to 6.4 Too numerous to list3

, 

below lower limit of 

standard

Surface waters 0/2 6.6 to 8.2
Water Quality 137

that the DMCA is a potential contributing element in either 

scenario is within the scope of this study

Groundwater flow to the local unnamed stream near the 

western DMCA property boundary from the perched waterbearing zone in the western end of the DMCA is anoxic 

(fig. 41), moderately elevated in TDS (fig. 34), moderately to 

highly elevated in dissolved ammonia-nitrogen and sulfate, 

and extremely elevated in the concentrations of dissolved 

metals (Mn(II), Fe(II/III)). This local unnamed stream, in turn, 

discharges to the Elk River (fig. 34). 

Pearce Creek Lake discharges to the tidal part of Pearce 

Creek (downstream of the lake outlet). However, during 

seasonally high levels, the lake also provides groundwater 

recharge along its lower third, which also could discharge to 

the stream, and possibly directly to Elk River (see Hydrology, this report). On the basis of data collected in February 

2011; whereas Elk River water is highly oxic, the quality of 

lake water was mixed oxic-anoxic and undergoing oxygen 

and manganese reduction (table 15). Thus, at a time when lake 

turnover in the region likely already had occurred, and the lake 

water should have been well oxygenated, it was discharging 

manganese downstream (appendix B, table B3, Pearce Creek 

Lake, dissolved manganese, 823 μg/L). 

Table 18. Summary of water-quality constituents with concentrations exceeding 2009 U.S. Environmental Protection Agency Safe 

Drinking Water Act standards for at least one groundwater or surface-water site in the Pearce Creek Dredge Material Containment 

Area and vicinity, 2010–11.—Continued

[NTRU, nephelometric turbidity ratio unit; mg/L, milligrams per liter; dissolved, sample filtered through an encapsulated and pleated 0.2-micron effective 

pore size, polysulfonyl filter; μg/L, micrograms per liter; SDWR, Secondary Drinking Water Standard (aesthetic—generally color, odor, and (or) taste); HAL, 

Health Advisory Level; MCL, Maximum Contaminant Level; LRL, laboratory reporting level; <, less than; E, estimated]

Water-quality 

constituent1

USEPA SDWA 

standard

Type of 

standard

Groundwater 

(by well type) or 

surface water

Number of 

sites with 

sample concentrations 

that exceeded 

the standard/

total number of 

sampling sites2

Range in 

concentrations 

for all sites

Samples whose 

concentrations exceeded 

standard 

Turbidity (NTRU), 

raw water

5 SDWR Observation 3/35 < 0.1 to 200 Wells CE Dd 81, 146, and 

150

Domestic supply 2/15 0.2 to 16 Wells CE Dd 161 and 166

Surface waters 2/2 8.6 to 20 Elk River and Pearce Creek 

Lake

Total dissolved 

solids (mg/L)

500 SDWR Observation 22/35 45 to 6,080 Too numerous to list3

Domestic supply 6/15 69 to 2,270 Wells CE Dd 161, 164, 174, 

176, 177, and 179

Surface waters 1/2 89 to 1,960 Elk River

Chloride (mg/L) 250 SDWR Observation 15/35 2.7 to 750 Too numerous to list3

Domestic supply 1/15 3.8 to 330 Well CE Dd 161

Surface waters 1/2 18 to 1,100 Elk River

Aluminum (μg/L) 50 to 200 SDWR Observation 13/35 < 3 to 58,000 Too numerous to list3

Domestic supply 3/15 < 6 to 1,990 Wells CE Dd 164, 176, 179

Surface waters 0/2 9 to 34

Iron (μg/L) 300 SDWR Observation 35/35 1,170 to 

656,000

All wells exceeded standard 

Domestic supply 10/15 19 or < 28 to 

71,800

Except for wells CE Dd 

163, 164, 168, 172, and 

178, all wells exceeded 

standard

Surface waters 0/2 27 to 63

1

 Except for pH and turbidity, all other constituents reflect dissolved concentrations.

2

 Well CE Dd 152 not included in analysis. Additional details are provided in the Total Dissolved Solids and Major Ions section of this report.

3

 Additional information on wells that exceeded standard is provided in appendix B, table B3.
138 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area Table 19. Reduction-oxidation conditions and processes and Federal Safe Drinking Water Act exceedances for domestic groundwater supplies in the Pearce Creek Dredge Material Containment Area and vicinity, 2010–11. [TEAP, Terminal electron acceptor process (Jurgens and others, 2009); HAL, health advisory level; SDWR, secondary drinking-water regulation, MCL, maximum contaminant level; μg/L, micrograms per liter; mg/L, milligram per liter; NTRU, nephelometric turbidity ratio unit; O2, oxygen reduction; NO3, nitrate reduction; Mn(IV), manganese reduction, Fe(III), iron reduction; X, standard was exceeded; (x), within 5 percent of standard] USGS local identifier TEAP reduction-oxidation results Federal Safe Drinking Water Act standard exceeded pH Manganese Iron Sodium Total dissolved solids Sulfate Alumi- num Turbid- ity Beryl- lium Nickel Chlo- ride Condition Process HAL 6.5-8.5 SDWR (50 μg/L) HAL (300 μg/L) SDWR (300 μg/L) HAL (20 mg/L) SDWR (60 mg/L) SDWR (500 mg/L SDWR (250 mg/L) HAL (500 mg/L) SDWR (200 μg/L) SDWR 5 NTRU MCL (4 μg/L) HAL (100 μg/L) SDWR (250 mg/L) CE Dd 161 Anoxic Fe(III)

X

X

X

X

X

X

X

X

X

X

X

X

X

CE Dd 179 Anoxic Fe(III)

X

X

X

X

X

X

X

X

X

X

X

CE Dd 176 Anoxic Fe(III)

X

X

X

X

X

X

X

X

CE Dd 177 Anoxic Fe(III)

X

X

X

X

X

X

X

X

CE Dd 174 Anoxic Fe(III)

X

X

X

X

X

X

CE Dd 169 Anoxic Fe(III)

X

X

X

X

CE Dd 170 Anoxic Fe(III)

X

X

X

CE Dd 166 Mixed (anoxic) NO3-Fe(III)

X

X

X

X

X

X

CE Dd 164 Mixed (oxicanoxic)

O2-Mn(IV)

X

X

X

X

X

X (x)

X

X

CE Dd 178 Mixed (oxicanoxic)

O2-Mn(IV)

X

X

X

X

CE Dd 165 Mixed (oxicanoxic)

O2-Fe(III)

X

X

X

X

CE Dd 172 Mixed (oxicanoxic)

O2-Mn(IV)

X

X

CE Dd 171 Mixed (oxicanoxic)

O2-Fe(III)

X

X

X

CE Dd 163 Mixed (oxicanoxic)

O2-Mn(IV)

X

X (x)

CE Dd 168 Oxic

O2 X

Number of exceedances of Federal Safe 

Drinking Water Act standards 15 14 10 10 8 4 6 4 2 3 2 2 2 1
Water Quality 139

Pearce Creek Lake also was recharging groundwater 

along the lower third of the lake in May 2010 (see Hydrology, 

this report). Groundwater downstream of Pearce Creek Lake 

also was discharging from the DMCA through the Magothy 

aquifer to Pearce Creek downstream of the lake discharge and 

likely farther along the shoreline and into the Elk River. This 

groundwater north of the DMCA is moderately elevated in 

TDS and, on the basis of the samples from the shallowest well 

in the Magothy aquifer (appendix B, table B3, well CE Dd 

145), is anoxic. However, the groundwater is low in ammonianitrogen and sulfate and is only moderately elevated in metals.

Farther south and along the western edge of the DMCA, 

groundwater from the DMCA flows west into WVS and travels vertically downward into the upper Patapsco aquifer shallow water-bearing zone into what is a highly-reducing zone. 

Then the groundwater moves upward and discharges along the 

western WVS shoreline or into bed sediments beneath the Elk 

River. In the area of upward flow, groundwater is anoxic 

(figs. 66 and 67), contains moderate to low levels of ammonianitrogen, and has high levels of manganese and iron.

At the time of this study, the Elk River was highly oxic 

(dissolved oxygen, 14.2 mg/L). The composite sample from 

the river (taken at 13 3-ft intervals) was collected soon after 

high tide, and in the winter. Field measurements indicated 

the concentration of dissolved oxygen was vertically uniform 

throughout the river profile (L. Myers, USGS, written commun., 2010). The USGS field crew also observed the river 

from the shore of WVS at an unusually low tide, and they 

noted an abrupt transition in river bed sediments, which went 

from light brown near shore to extremely dark black color 

offshore (J. Teunis, USGS, written commun., 2010). Both 

observations support the concept that metals are accumulating 

in the sediments offshore from WVS.

Furthermore, the effect of generally oxic river conditions 

on the fate of elevated metal concentrations in groundwater 

discharge in this area of Elk River could already be known. 

The recent study by Hartwell and Hameedi (2007; also see 

Chemical Composition of Sediments, this report) identified the lower Elk River Estuary as in the top tenth percentile 

among all bay estuary sites for toxics accumulation, largely 

on the basis of metals. DMCA use covers an extended period 

from the 1930s to the 1990s (six decades) in this part of the 

river.

Net Acidity

Groundwater and surface waters governed by redox conditions in the DMCA and its vicinity can be compared on the 

basis of acidity, provided the latter is not just the acidity associated with the pH (free hydrogen ion, H+

) of water. Accurate 

measurement of the acidity of groundwater governed by redox 

conditions requires including the additional acidity associated 

with hydrolyzed dissolved metal species such as iron, manganese, and aluminum, if they occur in groundwater that is 

governed by redox conditions (Kirby and Cravotta, 2005a,b). 

Acidity calculations can provide a single value that reflects the 

pH and all major redox-sensitive metal species to characterize 

and compare water quality. Acidity also can be used to assess 

potential changes in the quality of any surface water receiving 

direct discharge of anoxic water. 

Net acidity can be determined as follows (Kirby and 

Cravotta, 2005b): 

AcidityNet = AcidityCalculated – AlkalinityStdMthd (5)

where:

Each of the above terms is expressed in milligrams per liter as 

calcium carbonate (CaCO3),

AlkalinityStdMthd is determined by standard methods, 

AcidityCalculated is 50(1000 x (10–pH) +2(Fe2+)/56+3(Fe3+) 

/56 +2(Mn2+)/55 +3(Al3+)/27) (6)

and where the pH is measured and expressed in standard 

units, the total dissolved metal (Fe2+, 

Fe3+, Mn2+, and Al3+) concentrations are 

in milligrams per liter, each converted 

to milliequivalents per liter, using their 

valences and formula weights, and the 

entire expression then converted to 

milligrams per liter as CaCO3.

For groundwater in the DMCA and its vicinity, AcidityNet was determined from equations (5) and (6) with selected 

modifications (appendix B). In brief, AlkalinityStdMthd (ALK, 

hereafter) was estimated by Acid Neutralization Capacity 

(ANC, hereafter; see appendix B, table B3), as it was similar in value to ALK, on the basis of duplicate titrations of 

raw- and dissolved-groundwater samples. Concentrations of 

aluminum (Al3+), manganese (Mn2+), and iron (Fe2+) were estimated with the dissolved recoverable concentrations of these 

metals (appendix B, table B3, dissolved iron, manganese, and 

aluminum). The assumption that all iron was present as ferrous 

(Fe2+) iron could underestimate AcidityCalculated (equation 6), 

and thus AcidityNet (equation 5). Although this potential bias 

was investigated, and this bias was not apparent (appendix B), 

AcidityNet should be considered a conservative estimate. For 

interpretation of AcidityNet calculation, large negative values 

imply waters whose ALK exceeds AcidityCalculated, and thus 

generally reflect oxic conditions with AcidityNet mainly governed by bicarbonate and carbonate alkalinity. Large positive 

values generally imply anoxic waters with AcidityNet mainly 

governed by dissolved metals. For either case, the measured 

pH may be nearly identical, but AcidityNet values can differ 

markedly and range from positive to highly negative. Thus, 

the interpretive value in using AcidityNet to describe and compare the quality of groundwater governed by changes in redox 

conditions is apparent.

The most oxic and ALK-governed water in the study area 

is Elk River, whose AcidityNet equals –63 mg/L as CaCO3 

(fig. 82). In the Magothy aquifer beneath and in the vicinity 

of the DMCA (fig. 82), AcidityNet ranges from values of 
140 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

approximately –10 mg/L as CaCO3 to over 1,100 mg/L as 

CaCO3, reflecting natural groundwater and DMCA dischargeaffected groundwaters, respectively. The most oxic and weakly 

ALK-governed water in the Magothy aquifer occurs in the 

recharge area in WVS (AcidityNet equals approximately –6 to 

–3 mg/L as CaCO3) and in the Pearce Creek Lake discharge 

area (AcidityNet equals approximately –5 mg/L as CaCO3). 

AcidityNet values throughout the remainder of the DMCA and 

WVS in the Magothy aquifer and perched-water zone are governed by moderate pH and moderate to high concentrations of 

reduced metals.

In the upper Patapsco aquifer shallow water-bearing zone 

(fig. 83), the general trend in AcidityNet is for low negative values to occur in the very eastern part of the study area. Moving 

to the west, and south along the DMCA, AcidityNet values (227 

and 656 mg/L as CaCO3) reflect leakage from the Magothy 

aquifer through the confining layer. Farther west, the AcidityNet values (thousands of mg/L as CaCO3

) increase, reflecting 

downward flow from the Magothy aquifer of moderate-pH 

waters with very high reduced metals and no ALK, except for 

one deep well (AcidityNet of 1,130 as CaCO3), and, the AcidityNet values decrease in intermediate depth wells (AcidityNet

values of approximately 5 to 90 mg/L as CaCO3, respectively) 

a short distance farther west into WVS, where mixing occurs 

with recharging water from the Magothy aquifer. Toward the 

northern part of the DMCA, AcidityNet values are all negative, reflecting the thick confining layer between the Magothy 

aquifer and upper Patapsco aquifer, and again groundwater 

that is ALK-governed with moderate pH and relatively low 

redox-metals content.

The contrast between groundwater unaffected by human 

activity and groundwater affected by the DMCA and WVS 

is striking in cross-sectional views. Along line A–A′ (fig. 84), 

natural or relatively unaffected waters have AcidityNet values 

ranging from –10 to –30 mg/L as CaCO3. DMCA-affected 

groundwater AcidityNet values range from approximately 

89 to 1,250 mg/L as CaCO3 in the Magothy aquifer. Beneath 

WVS, AcidityNet values in the shallow oxic zone are –3 to 

3 mg/L as CaCO3, and it increases to approximately 30 mg/L 

as CaCO3

 at intermediate depths. However, in the low pH 

(highly acidic) and highly reducing upper Patapsco shallow 

water-bearing zone, AcidityNet values range from 800 to 1,480 

mg/L as CaCO3. Along line C–C′ (fig. 85), the pattern in 

AcidityNet values is similar to that observed in WVS along line 

A–A′. However, the replication indicates this pattern occurs 

beneath a major part of the community. 

The influence of the DMCA on AcidityNet concentrations 

in groundwater also is apparent along B–B′ (fig. 86). Concentrations in AcidityNet in the upper Patapsco aquifer shallow 

water-bearing zone are approximately –40 mg/L as CaCO3, 

where groundwater is relatively unaffected by human activities. In contrast, AcidityNet values range from approximately 90 

to 400 mg/L as CaCO3 beneath the DMCA, downgradient from 

the DMCA along its borders, or where leakage of DMCAaffected groundwater occurs between the Magothy aquifer and 

upper Patapsco aquifer shallow water-bearing zone.

Integration of Findings

The water-quality conditions currently (2010–11) present 

in the study area are directly related to a number of contributing factors. These factors include: historical changes in land 

use and landscape, the distribution and composition of permeable and relatively impermeable sediments, the groundwater 

flow system, and the chemical reactions that occur as water 

moves from areas of groundwater recharge to groundwater 

discharge. 

Development of the DMCA has significantly changed the 

hydrology of the site. Once an area of low-lying swamp and 

marsh deposits, with surface elevations only several feet above 

sea level (fig. 3), repetition of the disposal process over time 

has raised the level of deposited sediments (fill). The DMCA 

now stands at an average elevation of between 35 to 40 ft 

NAVD 88 (EA Engineering, Science, and Technology, Inc., 

2009). Berms and dikes surrounding the containment area are 

substantially higher in elevation. The developed site functions 

as a large retention basin, not only during former times of 

dredge-material emplacement, but also during substantial precipitation events once placement of dredge materials ceased. 

Formerly an area of groundwater discharge, the site is now an 

area of groundwater mounding and recharge, allowing for the 

slow percolation of water downward through the fill material.

Limited existing data are available on the chemical 

composition of the fill material within the DMCA. Sediment 

data collected in 1995–96 during the Phase II study (U.S. 

Army Corps of Engineers, 1996) indicate elevated concentrations of some metals—particularly manganese, zinc, lead, and 

copper—as compared to deeper naturally deposited formation 

sediments (table 9). Numerous studies of bay sediments from 

the upper Chesapeake Bay (a source of dredged material) have 

been made. These studies indicate that northern bay sediments—including sediments in the lower Elk River near the 

DMCA—are enriched in trace elements such as iron, manganese, zinc, and aluminum; have appreciable amounts of carbon, nitrogen, and sulfur; and include anthropogenic organic 

compounds such as pesticides and wastewater compounds.

Although groundwater of poor quality in the DMCA and 

vicinity has been documented in previous studies with samples 

collected in 1991–96 (Maryland Environmental Service, 1995; 

R.F. Weston, Inc., 1998), the results were inconclusive in identifying the source (or sources) of poor quality groundwater in 

nearby domestic wells. On the basis of the recommendations 

of these earlier studies, a more comprehensive monitoringwell network (fig. 6) was designed for this 2010–11 USGS 

study with the purpose of collecting the data necessary to 

define the underlying hydrogeologic framework, groundwaterflow system, the source(s) of water to supply wells, and the 

impact, if any, the DMCA has on water quality underlying the 

facility and in adjacent residential areas.

Synoptic groundwater-level measurements collected in 

May and August 2010 in the study area show that groundwater 
Water Quality 141 Figure 82. Net acidity in water-quality samples from selected surface waters and from selected wells completed in the perched water-bearing zone or Magothy aquifer in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11.

127

75°59' 76°

39°26'

39°25'30"

Elk River Pearce Creek Lake

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

Crystal Beach

Pond Neck Road

West View Shores

Bay View Estates

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

2

4

6

8

10

10

8

6

-63.1

-6.4

-2.0 -2.6

3.5 5.0 36.5

150

8.9

134

68.3

404

58.2

93

151

-16.3

-8.4

160

155

1,250

1,120

1,350

-4.9

3.5 5.0 36.5

EXPLANATION

Potentiometric surface contour in the Magothy aquifer—Shows altitude 

at which water would have stood in tightly cased wells, May 19–20, 2010. Dashed where approximately located. Contour interval 2 feet. Datum is North American Vertical Datum of 1988

Direction of groundwater flow

Locally perched aquifer well—Number shows net acidity, in milligrams 

per liter (mg/L) as calcium carbonate 

Magothy aquifer well—Number shows net acidity, in mg/L as calcium 

carbonate

Surface-water site—Number shows net acidity, in mg/L as calcium 

carbonate

6 134

404

-4.9
142 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area Figure 83. Net acidity in water-quality samples from selected surface waters and from selected wells completed in the upper Patapsco aquifer shallow water-bearing zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11. 127141 75°59' 76° 39°26' 39°25'30"

Elk River Pearce Creek Lake

Crystal Beach

Pond Neck Road

West View Shores

Bay View Estates

Base map from Cecil County, Maryland governmentMaryland State Plane coordinate system North American Datum of 1983

0 500 1,000 1,500 2,000 FEET0 200 400 METERS

Perimeter dike

Property boundary of Pearce Creek Dredge Material Containment Area 

2

4

4

6 6

8

8

-63.1

683

5.3

5.2

44

21.7

206

32.6 85.7

804

29.9

1,130

5.3

5.2 21.7

206

94.6 94.6

32.6

29.9

1,130

1,160 1,480

1,440

-133

-46.5 

-38.9

-4.9

-77.9

-28.2

88.7

666

274

70.3

-4.9

EXPLANATION

Potentiometric surface contour in the upper Patapsco aquifer, shallow waterbearing zone— Shows altitude at which water would have stood in tightly cased 

wells, May 19–20, 2010. Dashed where approximately located. Contour interval 2 feet. Datum is North American Vertical Datum of 1988

Direction of groundwater flow

6 666 Upper Patapsco aquifer well, shallow water-bearing zone—Number shows 

net acidity, in milligrams per liter (mg/L) as calcium carbonate

Surface-water site—Number shows net acidity, in mg/L as calcium 

carbonate
Water Quality 143 Figure 84. Hydrogeologic section showing net acidity in water-quality samples along line A–A’ from selected surface waters and from selected wells completed in the perched water-bearing zone, Magothy aquifer, or upper Patapsco aquifer shallow or deep watering-bearing zone in the Pearce Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11. (Location of line of section A–A’ is shown in figure 39.)

Magothy aquifer

Fill - Matawan Formation

Upper Patapsco aquifer

shallow water-bearing zone

Upper Patapsco aquifer

deep water-bearing zone

Groundwater divide

Well

identifier

1,250

-28.2

160

70.3

68.3

1,480

8.9

1,160

32.6

3.5

-25.9

804

1,130

5.3

85.7

-2.0

-2.6

134

-63.1

-8.4

5.0

5025

-25-50-75

-100-125-150-175-200-225-250

0

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000

Distance, in feet

4,500 5,000 5,500 6,000 6,500 7,000 8,000 8,500 9,000 7,500

A

WEST

A'

EAST

193

192191

157 158 124 139 122

151 81

163

168

165

164 171 142

128

178

160

Confining unit

Confining unit

Elk

River

Confining unit

Altitude, in feet above or below North American Vertical Datum of 1988

VERTICAL EXAGGERATION x 20

172

Net acidity, in milligrams per liter as calcium  carbonate

—Determined in accordance with 

 Kirby and Cravotta, 2005b Direction of groundwater flowPrecipitation/recharge

EXPLANATION

70.3
144 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area Figure 85. Hydrogeologic section showing the net acidity in water-quality samples along line C–C’ from selected surface waters and from selected wells completed in the perched water-bearing zone, Magothy aquifer, or upper Patapsco aquifer shallow or deep watering-bearing zone in the Pearce Creek 

Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11. (Location of line of section C–C’ is shown in figure 39.)

0

50

25

-63.1

44

21.7 94.6

-25.9

3.5 8.9

1,160

32.6

169

174 176 171 164 163

81 151

Altitude, in feet above or below North American Vertical Datum of 1988

C

NORTH

C'

SOUTH

Well

identifier

Elk River

-100-125-150-175-200-225-250

-25-50-75

0 200 400 600 800 1,000 1,200 1,400 1,600 1,800 2,000 2,200 2,400

Distance, in feet

VERTICAL EXAGGERATION x 6

Magothy aquifer

Confining unit

Upper Patapsco aquifer

shallow water-bearing zone

Confining unit

Upper Patapsco aquifer

deep water-bearing zone

Confining unit

Net acidity, in milligrams per liter as calcium  carbonate

—Determined in accordance with 

 Kirby and Cravotta, 2005b Direction of groundwater flowPrecipitation/recharge

EXPLANATION

44
Water Quality 145

flow in the two primary aquifers used for local supplies—the 

Magothy aquifer and upper Patapsco aquifer (shallow waterbearing zone)—is radially outward from the DMCA toward 

discharge areas, including WVS, Elk River and Pearce Creek 

Lake (figs. 21–25). In addition to horizontal flow outward 

from the DMCA, vertical gradients primarily are downward in 

most of the study area, and upward near the Elk River on the 

north side of the DMCA property, and the western part of West 

View Shores. Vertical mixing of waters occurs between the 

two aquifers particularly where the Magothy aquifer and upper 

Patapsco aquifer shallow water-bearing zone are in hydraulic 

connection in areas where confinement between the aquifers is 

thin or missing (figs. 9, 11, 12, and 30).

Given this understanding of the groundwater flow system, 

it is clear that water that falls on the DMCA as precipitation 

or is deposited along with dredge-fill material will eventually seep into the underlying Magothy aquifer and flow from 

that aquifer into parts of the upper Patapsco aquifer shallow 

water-bearing zone. Potentiometric-contour maps and vertical 

profiles of the groundwater flow system in cross section show 

that the DMCA is the major upgradient source area of water 

to wells completed in the Magothy aquifer and the upper Patapsco aquifer shallow water-bearing zone and located in WVS 

Figure 86. Hydrogeologic section showing the net acidity in water-quality samples along line B–B’ and from selected 

wells completed in the Magothy aquifer or upper Patapsco aquifer shallow or deep watering-bearing zone in the Pearce 

Creek Dredge Material Containment Area (DMCA) and vicinity, Cecil County, Maryland, 2010–11. (Location of line of 

section B–B’ is shown in figure 39.)

666

404

274

151

-46.5

-38.9

-39.7

93.0

70.3

160

Groundwater divide

Altitude, in feet above or below North American Vertical Datum of 1988

B

NORTH

B'

SOUTH

Well

identifier

Elk River

VERTICAL EXAGGERATION x 20

126136 138 137

147

145

146 149

157 158

-250

-225

-200

-175

-150

-125

-100

-75

-50

-25

0

25

50

Distance, in feet

Magothy aquifer

Fill - Matawan Formation

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 5,000 5,500

Confining Unit

Upper Patapsco aquifer

shallow water-bearing zone

Confining unit

Upper Patapsco aquifer

deep water-bearing zone

Confining unit

Net acidity, in milligrams per liter as calcium 

 carbonate—Determined in accordance with 

 Kirby and Cravotta, 2005b 

Direction of groundwater flow

Precipitation/recharge

EXPLANATION

666
146 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

and along part of Long Neck Road. Other important sources of 

groundwater recharge to the area and particularly to domestic 

wells located at higher elevations in WVS and completed at 

shallow depths in the Magothy aquifer are precipitation that 

falls directly on this area and local residential recharge from 

landscape irrigation and septic effluents (fig. 30).

Results of water-quality analyses and the occurrence and 

distribution of specific water-quality constituents are consistent with the hydrogeologic framework, directions of groundwater flow, and identification of the DMCA as a source area 

that has impacted local groundwater quality. The distribution 

of TDS in groundwater is used as a measure of the general 

quality of groundwater beneath the DMCA and its vicinity. 

TDS content is a measure of the combined content of all dissolved inorganic and organic substances contained in the water 

sample. It is not generally considered a primary pollutant associated with health effects; rather it is used as an indication of 

aesthetic characteristics of drinking water and as an aggregate 

indicator of the presence of a broad array of chemical constituents. The Federal SDWR for TDS is 500 mg/L or less in 

public drinking-water supplies. 

During the use of the DMCA, brackish Elk River water 

was mixed with sediments, and the slurry would have been 

pumped into the DMCA, adding an additional major source of 

TDS, including chloride and sodium. Concentrations measured 

in area wells in the Magothy and upper Patapsco aquifers not 

influenced by the DMCA, or located just outside the study 

area, have TDS concentrations of less than 100 mg/L, typical 

of natural groundwater for the aquifers. In contrast, TDS concentrations in the Magothy aquifer directly under the DMCA 

are an order of magnitude greater; several Magothy aquifer 

and upper Patapsco aquifer shallow water-bearing zone 

wells yielded groundwater samples with TDS in the 4,000 to 

6,000 mg/L range (appendix B; and figs. 32, 34, and 35). Individual constituents such as chloride, sodium, sulfate, manganese, iron, and aluminum are also orders of magnitude higher 

in aquifers underlying the DMCA and vicinity than in either 

aquifer within or near the study area where human activities 

have not overly influenced groundwater quality (table 13; 

appendix B). The latter also reflect conditions consistent with 

water-quality information and analysis provided by Otton 

and others (1988) and Willey and others (1987) for Potomac 

Group and Magothy aquifers throughout Cecil County, Md. In 

fact, Otton and others (1988) make a point of not using analytical results from a 1983 sample of groundwater from well 

CE Dd 81 located just outside the DMCA berm in the southwestern corner of the DMCA, owing to the fact that the water 

does not represent natural water in the aquifer. 

Given the groundwater flow system and groundwater 

geochemistry of the study area, the influence of the DMCA is 

not only as a source of TDS but also a geochemical driver of 

redox processes that enhance the mobilization and transport of 

redox-sensitive metals and nutrients. Groundwater affected by 

the DMCA is predominately anoxic and mainly reflects ironreducing conditions. These redox conditions are characterized 

by the absence of dissolved oxygen, and an abundance of the 

reduced forms of nitrogen (ammonia) and metals (manganese 

and iron). Compounding factors that elevate the concentrations of dissolved constituents include the presence of organic 

carbon, the mixing of anoxic and oxic waters, and the acidity 

of groundwater.

Creation of reduced groundwater conditions generally 

is facilitated by microorganisms that depend on the presence 

of organic carbon. Sources of organic carbon dissolved in 

groundwater include fill composed of bay sediments that are 

known to contain abundant amounts of carbon (table 8, carbon, 21.8 mg/kg). Other substantial sources of carbon to the 

groundwater flow system are the seasonal Phragmites vegetation within the DMCA; the abundance of lignite in naturally 

deposited sediments including the Matawan, Magothy, and 

Patapsco Formations; and wetland sediments that were buried 

during the construction of the DMCA. The elevated concentrations of dissolved organic carbon support microbial activity 

that leads to anoxic conditions in groundwater. 

Groundwater in the study area with the highest levels of TDS, manganese, ferrous iron, and sulfate generally 

correspond to parts of the groundwater flow system under 

highly anoxic iron-reducing conditions that possibly reflect 

the mixing of anoxic groundwater from the DMCA with oxic 

groundwater from other source areas. This occurs predominantly where the Magothy aquifer is unconfined, allowing 

hydraulic connection with the underlying upper Patapsco 

aquifer shallow water-bearing zone. Here, direct recharge from 

precipitation provides oxygenated water to the groundwater 

flow system, and groundwater pumping for water supplies aids 

mixing (figs. 30 and 66).

As anoxic groundwater is drawn into or flows into areas 

such as WVS, which contain predominately oxic water, 

the anoxic water undergoes oxidation. The outcome of this 

process is the production of acidity (H+

) through the oxidation 

of reduced iron, and the formation of ferric hydroxide precipitates. The low pH of groundwater throughout the Magothy 

aquifer and upper Patapsco aquifer shallow water-bearing 

zone beneath WVS provides an abundance of acidity for 

metal hydrolysis. This acidity is locally increased with depth 

beneath oxic zones in WVS. The result is a localized increase 

in the concentration of TDS (and likely reduced metals and 

sulfate) which, in combination with the major inflow of anoxic 

groundwater of similar quality from the DMCA, accounts for 

the local and highly elevated concentrations of TDS and other 

reduced species in the upper Patapsco aquifer shallow waterbearing zone. The most severe reducing condition—that of 

Fe(III) reduction—corresponds to groundwater from DMCA 

recharging the Magothy aquifer, flowing beneath the western 

half of the DMCA, then moving farther westward and vertically downward to the base of the upper Patapsco aquifer 

shallow water-bearing zone, and ultimately either continuing 

farther west in this zone, or moving vertically upward 

to discharge along the western end of WVS or Elk River 

(fig. 66). This flow also contains the highest concentrations of 
Water Quality 147

TDS in either aquifer in this area (fig. 41). However, groundwater at shallow depths beneath the community is under less 

severe mixed oxic-anoxic conditions (fig. 66, O2–Fe(III)).

Whereas groundwater at depth beneath WVS is poor in 

quality, shallow groundwater in elevated areas of this community is of relatively good quality. Shallow groundwater in the 

Magothy aquifer initially reflects local recharge, precipitation, 

and residential use, and contains relatively low concentrations of TDS (fig. 41). The improved water quality is due in 

part to recharge from precipitation (low in TDS) and in part to 

residential use of groundwater that has been treated to reduce 

TDS. Use of this limited zone of generally oxic water that is 

low in TDS is consistent with the large percentage of wells 

that have been installed within the shallow unconfined Magothy aquifer in WVS since 1985, as opposed to deeper depths 

where poor quality water is present. 

In addition to water-quality analyses of discrete intervals 

within aquifers, electromagnetic-induction logging provided 

a continuous profile of the vertical extent of high conductivity water representative of high TDS concentration (figs. 44

and 45). The downward and downgradient movement of water 

with high TDS concentrations emanating from the DMCA 

is consistent with groundwater flow patterns, recharge to the 

unconfined system, strong downward gradients of flow, and 

movement of water downgradient to Elk River as described 

above.

The influence of the DMCA on the quality of groundwater is apparent in relation to more than just TDS and redoxsensitive species. This influence has also been demonstrated in 

relation to the low-level detections of pesticides and in particular wastewater compounds. Multiple detections of pesticides 

and wastewater compounds occur within the Magothy aquifer, 

primarily within the DMCA, and are attributed to dredged 

sediment and Elk River water pumped into the DMCA during 

the active time period of the DMCA. 

Other hydrogeologic and groundwater flow conditions 

within the DMCA that have an impact on local water quality 

are the integrity of confining units associated with the aquifers 

and upward or horizontal flow to streams. The lack of confinement and hydraulic connection of the Magothy aquifer and 

upper Patapsco aquifer shallow water-bearing zone and its 

implication to flow and quality of groundwater has already 

been discussed. Also important is the structure of the upper 

Patapsco confining unit as it spans the DMCA. This confining 

unit thickens substantially in the northern half of the DMCA, 

north of well 158. The confining unit thins to the south of 

well 158, with local sandy zones interfingering with the clays 

that decrease the effectiveness of the confining unit in restricting downward flow from the Magothy aquifer to the upper 

Patapsco aquifer shallow water-bearing zone (figs. 9A and 14). 

This is consistent with the elevated TDS concentrations found 

in both aquifers south of well 158 (fig. 42). Upward flow of 

groundwater at well nests near wells 126 and 145 effectively 

keep water with high concentrations of TDS contained in the 

Magothy aquifer in the northwestern part of the DMCA.

Water-quality sampling and analysis of wells completed 

in the upper Patapsco aquifer deep water-bearing zone indicate 

that groundwater throughout this zone is under anoxic conditions but is relatively low in TDS content. Based on minimal 

data, the water quality in the upper Patapsco aquifer deep 

water-bearing zone does not seem to have been impacted by 

the DMCA. 

The groundwater flow (as determined by this study) 

combined with multiple aspects of the groundwater quality 

data and analysis indicate that the high TDS and sulfate waters 

beneath and beyond the DMCA, both vertically and laterally, 

are the result of past use and recharge as a result of past operation of the DMCA. The groundwater-quality data and analysis 

that support this conclusion include the redox distribution, 

concentration distributions of TDS, sulfate, iron, chloride, 

dissolved oxygen, pH, nitrogen, groundwater types (as shown 

on trilinear diagrams), and the correlation of TDS to multiple 

anions and cations. Specifically,

1. TDS concentrations in the Magothy aquifer under 

the DMCA and vicinity range from 45 to more than 

5,000 mg/L.

2. TDS concentrations toward the high end of this range 

generally correspond to the westerly thinning of the 

Matawan confining unit and eventual outcrop of the sediments of the Magothy aquifer in the western part of the 

DMCA and in WVS. The high TDS values in the southeastern part of the study area likely reflect historical flows 

outward from the DMCA during the site’s operation. Substantial overlying confinement and slow horizontal flow 

in this area of the Magothy aquifer hinder the dilution of 

high TDS water.

3. Concentrations of TDS in the Magothy aquifer beneath 

the northern or northeastern part of the study area are 

generally 500 mg/L or less and reflect the occurrence and 

increased thickness of the Matawan confining unit above 

the Magothy aquifer, which likely reduced recharge from 

the DMCA. In addition, there is upward flow of low TDS 

water from the upper Patapsco aquifer shallow waterbearing zone, and (or) recharge from Pearce Creek Lake 

(also low TDS water) into the Magothy aquifer. 

4. Waters with concentrations of TDS less than 170 mg/L 

occur in the shallow Magothy aquifer beneath WVS. 

These moderately low concentrations of TDS reflect 

recharge through the residential area from precipitation 

combined with septic system recharge and (or) local residential irrigation.

5. In the upper Patapsco shallow water-bearing zone in the 

northeastern part of the study area, TDS concentrations 

are less than 170 mg/L and reflect concentrations found 

in natural waters. In contrast, TDS concentrations exceed 

6,000 mg/L under the southwestern part of the DMCA. 

The latter likely reflects older groundwater recharge from 
148 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

the DMCA under past hydrologic conditions (that may not 

be represented by current 2010–11 hydrogeologic data).

6. Under WVS, TDS concentrations in the deep part of the 

upper Patapsco shallow water-bearing zone are 4,000 to 

5,000 mg/L. These concentrations in part reflect groundwater with high TDS concentrations that flowed from the 

Magothy aquifer from the east and then downward into 

this zone.

7. The distribution of major ions was very similar for wells 

with TDS concentrations greater than 300 mg/L. Sulfate 

accounted for the majority of the anions present in the 

water. The ion distribution was similar regardless of geographic position or aquifer. 

8. The distribution of major ions was heterogeneous for 

wells with TDS concentrations less than 300 mg/L. 

However, patterns in ion distribution varied depending on 

aquifer or geographic position.

• In general, where water-bearing zones are well confined, groundwater beneath the study area is anoxic 

regardless of the aquifer or water-bearing zone. Anoxic 

waters were also found in several wells that were not 

affected by the DMCA.

• Conditions in the Magothy aquifer and upper Patapsco 

shallow water-bearing zone beneath WVS are oxic at 

the shallowest depths, oxic to anoxic or anoxic mixtures at intermediate depths, and anoxic in the deepest 

part of the upper Patapsco shallow water-bearing 

zone. The only other area where oxic groundwater conditions occur is east of the DMCA property boundary 

(well 193).

• Within the DMCA, the reduced sediments and oxic Elk 

River water deposition could have led to the initial oxidation of sulfur, the formation of sulfate, a decrease in 

pH, and hydrolyzation of trace elements such as iron, 

manganese, and aluminum from the deposited and (or) 

native sediments exposed to the recharged water from 

the DMCA. As this water returns to reduced conditions, elevated nitrogen (organic and (or) ammonia) 

and carbon, as well as elevated calcium, magnesium, 

sodium, and chloride would all have generally been 

present in groundwater beneath the DMCA, in areas 

where the confining layer is absent or thin (i.e., southcentral, southwest, and southeast of the boundary of 

the DMCA). 

There are very little data to support alternative hypotheses for a different or additional source of high TDS, sulfate, 

iron, and chloride and low pH groundwater. The overwhelming evidence is that the DMCA has affected the groundwater. 

Human activities potentially upgradient of the DMCA to the 

east, and (or) including extensive agriculture, or potential local 

point sources such as ponds or landfills are unlikely sources of 

the high TDS groundwater observed beneath and in the southeast part of the study area for several reasons.

First, TDS concentrations in the Magothy aquifer (which 

one could hypothesize are possibly associated with regional 

groundwater flow towards the DMCA) are low (less than 

170 mg/L) and are similar to natural waters unaffected by 

anthropogenic activities in the aquifer. The concentrations of 

TDS in wells nearby, but outside the study area of this report, 

are also less than 100 mg/L. These low concentrations of TDS 

are consistent with this aquifer being overlain by the Matawan 

confining unit (50 to 60 ft thick). Groundwater has distinctly 

different major ion chemistry in areas with low TDS than in 

areas with higher TDS (greater than 300 mg/L). 

Second, one could hypothesize that human activities near 

the land surface (agriculture, landfills) could be the source 

of the high TDS and sulfate water. There are three problems 

with this hypothesis: (a) concentrations of TDS, sulfate, and 

iron beneath other agricultural areas of the Eastern Shore 

of Maryland are orders of magnitude lower than measured 

in samples beneath the DMCA and vicinity; (b) the source 

necessary to generate the mass of TDS, sulfate, and iron as 

measured in samples beneath the DMCA and vicinity would 

need to be extremely large; and (c) the Magothy aquifer to 

the east and south, where human activities predominate (for 

example, agriculture, nurseries, local surface landfill), is 

overlain by 50 to 60 ft of the Matawan confining unit, which 

would retard the flow of high TDS and sulfate water from the 

land surface to the Magothy aquifer. Potential loading from 

point sources likely would not be able to generate the mass of 

source necessary.

Third, there is no evidence that Elk River water intrusion 

is directly responsible for the occurrence of high TDS and 

sulfate waters. In contrast, several lines of evidence suggest 

that it is not a direct source. General patterns in groundwater flow in both the Magothy aquifer and upper Patapsco 

shallow water-bearing zone all are east to west, not west to 

east; groundwater from both aquifers discharges into the Elk 

River bed sediments. Trilinear (Piper) diagrams indicate that 

Elk River water is a chemically unique type (predominately 

sodium chloride and low sulfate). Previous (R.F. Weston, 

Inc.,1998) and current (2010–11) analyses of the bromide 

to chloride ratios collectively show that the ratios for Elk 

River water appear similar to ratios in groundwater, but they 

are not indicative of the Elk River being the source of the 

groundwater. 

There are selected limitations in the available data for 

groundwater flow and quality at several locations throughout 

the extent and thickness of the Magothy aquifer and upper 

Patapsco shallow water-bearing zone within the perimeter dike 

of the DMCA. Borehole geophysical logs indicate that high 

conductance water occurs in several locations where wells 

have not been screened and indicate that the low conductance 

water occurs at other locations. Water level and geochemical 
Acknowledgments 149

data at the following locations would address gaps in the current data set regarding both groundwater flow and quality as 

water flows through the DMCA sediments, and through the 

Magothy aquifer beneath the DMCA: midway between 

wells CE Dd 139 and CE Dd 157 at the base of the Magothy 

aquifer, near well CE Dd 157 at the base of the Magothy aquifer, near well CE Dd 139 screened at a depth midway between 

the screened intervals of wells CE Dd 122 and 139, near 

well CE Dd 193 in the top of the Magothy aquifer, near 

well CE Dd 193 in the upper Patapsco shallow water-bearing 

zone. 

Data gaps also exist outside the DMCA perimeter dike. 

Water level and geochemical data south and east of wells CE 

Dd 125, 153, and 193 would be useful in further delineation 

of the groundwater flow system and geochemistry of groundwater south and east of the DMCA. These additional data 

may provide information that further corroborate the conclusions presented in this report—namely that the DMCA is the 

major source of the high TDS type groundwater found beneath 

and in the vicinity of the DMCA, or they could indicate that 

groundwater east and (or) south of the DMCA contributes to 

the high TDS type groundwater beneath and along the southern and eastern parts of the DMCA and study area. However, 

without the additional data, the latter is largely speculative; 

whereas there are sufficient data and multiple lines of evidence 

on the basis of the analyses of current (2010–11) and historical 

data to suggest that the DMCA use led to the occurrence of the 

high TDS type groundwater in the study area.

Conclusions

The integration of the hydrogeologic, hydrologic, and 

water-quality information developed as part of this study 

provides an improved understanding of the impact of the 

U.S. Army Corps of Engineers Pearce Creek Dredge Material 

Containment Area (DMCA) in Cecil County, Maryland on 

the groundwater flow system in the DMCA and the immediate vicinity. Before the DMCA was constructed, the site was a 

low-lying, natural wetland that freely drained to the tidal Elk 

River, or freely drained to the adjacent Pearce Creek, which in 

turn drained into the tidal Elk River. The bermed area of the 

DMCA now rises more than 30 ft above pre-DMCA low-lying 

topographic position on the Chesapeake Bay coast, making it 

a recharge area for the underlying aquifers, as demonstrated 

by potentiometric maps of the Magothy aquifer and upper 

Patapsco shallow and deep water-bearing zones. Vertical gradients have resulted in downward groundwater flow from the 

DMCA sediments into the underlying Magothy aquifer, and 

then downward into the upper Patapsco shallow water-bearing 

zone where the intervening confining unit is thin or missing. 

The chemical composition of the dredged bay sediments that 

were mixed with oxic, brackish Elk River water and emplaced 

within the berms of the DMCA has influenced the quality 

of groundwater recharging the underlying aquifers, creating a complex chemical matrix discernible in groundwater 

throughout the local groundwater flow system. Water-quality 

data of numerous types are consistent with the hydrogeologic 

and hydrologic interpretation that the DMCA has degraded 

local groundwater quality. The water is considered degraded 

in part as a result of concentrations of some chemical constituents at levels greater than maximum allowable or recommended levels established in the U.S. Environmental Protection Agency Safe Drinking Water Act Secondary Drinking 

Water Regulations, Health Advisory Levels, and Maximum 

Contaminant Levels. Data for TDS concentrations, major ion 

content, redox-sensitive species (dissolved oxygen, nitrogen, 

manganese, iron, and sulfate), DOC, pesticides, wastewater 

compounds, and acidity support the finding that the DMCA is 

the primary source of the poor quality of water found in the 

aquifers underlying it. The migration of groundwater impacted 

by the DMCA into the upper Patapsco shallow water-bearing 

zone where the overlying confining unit is absent is a source 

of the poor quality groundwater that supplies some domestic 

wells in the West View Shores residential community.

Acknowledgments

The authors would like to thank the U.S. Army Corps of 

Engineers for support of this study, and providing technical 

background on the site and previous studies, especially Timothy Kelly, Daniel Sirkis, and J. Mark Chamberlain. 

The authors thank the following USGS colleagues for 

thorough reviews that helped to improve this report: Matthew 

Pajerowski, Douglas Chambers, Jeff Raffensperger, J. Stephen 

Schindler, David Pollock, and Michelle Lorah. The authors 

thank Charles Cravotta for his assistance in the determination 

and review of acidity titrations and calculations. The authors 

would like to thank the following USGS colleagues who 

were instrumental in the completion of this study: Michael 

Brayton, Deborah Bringman, Michael Brownley, Roberto 

Cruz, William Davies, Megan Dustin, Andrew LaMotte, Peter 

Lapa-Lilly, Brenda Majedi, Luke Myers, Andrew Reid, Jessica 

Teunis, Jason Sorenson, Andrew Massey, Pierre Lacombe, 

and Robert Rosman. Finally, the authors appreciate the help of 

Larry Slack, Valerie Gaine, Michael Kemppainen and Timothy 

Auer for editorial review, illustration preparation, and publication of this report.
150 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

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Appendixes A–C
156 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area Table A1. Characteristics of observation and domestic wells used for hydrogeologic framework, hydrologic, and water-quality data collection in the Dredge Material Containment Area and vicinity, Cecil County, Maryland, 2010–11. [USGS, U.S. Geological Survey; USACE, U.S. Army Corps of Engineers; ddmmss.s, degrees, minutes, seconds (to nearest tenth – or .ss, hundredth); NAD83, North American Datum, 1983; NAVD88, North American Vertical Datum, 1988; ft, feet; bls, below land surface; in., inches; PVC, polyvinylchloride; Type of open interval: P-perforated, R-wire-wound screen, S-screen, X-open hole; UPA, upper Patapsco aquifer; shallow, shallow water-bearing zone; deep, deep water-bearing zone; MA, Magothy aquifer; X (G, C, and or R), implies gamma, conductance, and or resistivity geophysical logs were taken); X (M, T) implies manual intermittent water levels were recorded, and or time-series continuous monitoring data were collected; ---, missing data; np, not published] USGS well identifier USGS local identifier USACE local identifier State well permit number Year of well instal- lation Location of well Elevation of land surface near well (NAVD88) (ft) Depth of well (ft, bls) Depth of bore- hole (ft, bls) Mate- rial com- posi- tion of well Diam- eter of well (in.) Mate- rial com- posi- tion of open inter- val Di- am- eter of open in- ter- val (in.) Type of open interval Latitude (NAD83) ddmmss.s Longitude (NAD83) ddmmss.s Observation wells 392536075593201 CE Dd 81 --- CE-81-0469 1983 392536.8 755929.9 21.70 115 503 PVC 4 PVC 2 R 392536075591901 CE Dd 122 CSW 1 CE-94-1016 1995 392535.88 755919.34 34.88 129.33 140 PVC 4 PVC 4 P 392536075592001 CE Dd 123 CSW 4 CE-94-1019 1996 392535.73 755920.01 35.86 59 60 PVC 4 PVC 4 P 392536075592002 CE Dd 124 CSW 6 CE-94-1020 1996 392536 755920.1 35.82 22 22 PVC 2 PVC 2 P 392514075584301 CE Dd 125 CSW 5 CE-94-1080 1995 392514.2 755842.9 46.96 90.33 92 PVC 4 PVC 4 P 392556075590001 CE Dd 126 CSW 2 CE-94-1017 1995 392556 755900.5 39.03 127.5 210 PVC 4 PVC 4 P 392550075593901 CE Dd 127 CSW 7 CE-94-1021 1995 392550.05 755938.78 8.00 91.3 107 PVC 4 PVC 4 P 392540075594401 CE Dd 128 CSW 8 CE-94-1081 1995 392540.1 755943.8 25.23 128.25 133.5 PVC 4 PVC 4 P 392547075591701 CE Dd 129 CSW 9 CE-94-1134 1996 392547.2 755917.3 28.07 125 139 PVC 4 PVC 4 P 392539075592201 CE Dd 130 CSW 10 CE-94-1447 1996 392539.1 755921.9 29.46 115 115 PVC 2 PVC 2 P 392603075585601 CE Dd 131 CSW 11 CE-94-1448 1996 392603.4 755856.2 21.47 58 62 PVC 4 PVC 4 P 392520075590301 CE Dd 132 CSW 12 CE-94-1449 1996 392520.4 755903.5 35.30 38 46 PVC 2 PVC 2 P 392546075581901 CE Dd 133 CSW 13 CE-94-1450 1996 392546 755819 16.00 53 55 PVC 4 PVC 4 P 392520075590302 CE Dd 134 CSW 14 CE-94-1451 1996 392520.3 755903.4 34.58 119 119 PVC 2 PVC 2 P 392546075584801 CE Dd 135 CSW 15 CE-94-1452 1996 392546 755848.2 42.75 99 102 PVC 2 PVC 2 P 392556075590002 CE Dd 136 2A CE-95-3089 2010 392555.7 755900.2 38.45 55 59 PVC 4 PVC 4 R 392527075590802 CE Dd 137 3A CE-95-3098 2010 392527.2 755908.1 36.82 63 70 PVC 4 PVC 4 R 392527075590801 CE Dd 138 3R CE-95-3097 2010 392527.2 755908.1 36.85 120 148 PVC 4 PVC 4 R 392536075592003 CE Dd 139 4R CE-95-3090 2010 392535.7 755919.8 34.86 58 59 PVC 4 PVC 4 R 392548075593801 CE Dd 140 7A CE-95-3096 2010 392548.4 755939.1 11.47 16 28 PVC 4 PVC 4 R 392548075593802 CE Dd 141 7B CE-95-3095 2010 392548.4 755938.1 11.21 222 228 PVC 4 PVC 4 R 392540075594501 CE Dd 142 8A CE-95-3088 2010 392540.4 755945 23.55 89 98 PVC 4 PVC 4 R

392540075594502 CE Dd 143 8B CE-95-3087 2010 392540.4 755945 23.72 44 48 PVC 4 PVC 4 R

392547075591702 CE Dd 144 9A CE-95-3107 2010 392547.1 755917.2 28.12 27 34 PVC 4 PVC 4 R

392603075585602 CE Dd 145 11C CE-95-3106 2010 392603.4 755856.3 21.00 30 30 PVC 4 PVC 4 R
Appendix 

A    ﻿﻿   157

Table A1. Characteristics of observation and domestic wells used for hydrogeologic framework, hydrologic, and water-quality data collection in the Dredge Material Containment Area and vicinity, Cecil County, Maryland, 2010–11.—Continued[USGS, U.S. Geological Survey; USACE, U.S. Army Corps of Engineers; ddmmss.s, degrees, minutes, seconds (to nearest tenth – or .ss, hundredth); NAD83, North American Datum, 1983; NAVD88, North American Vertical Datum, 1988; ft, feet; bls, below land surface; in., inches; PVC, polyvinylchloride; Type of open interval: P-perforated, R-wire-wound screen, S-screen, X-open hole; UPA, upper Patapsco aquifer; shallow, shallow water-bearing zone; deep, deep water-bearing zone; MA, Magothy aquifer; X (G, C, and or R), implies gamma, conductance, and or resistivity geophysical logs were taken); X (M, T) implies manual intermittent water levels were recorded, and or time-series continuous monitoring data were collected; ---, missing data; np, not published]

USGS well 

identifier

USGS local 

identifier

USACE 

local 

identifier

State well 

permit 

number

Year of 

well 

installation

Location of well

Elevation of 

land surface 

near well 

(NAVD88) 

(ft)

Depth 

of well

(ft, bls)

Depth of 

borehole

(ft, bls)

Material 

composition of 

well

Diameter of 

well

(in.)

Material 

composition of 

open 

interval

Diameter 

of 

open 

interval

(in.)

Type of 

open 

interval

Latitude 

(NAD83)

ddmmss.s

Longitude 

(NAD83)

ddmmss.s

392603075585604 CE Dd 146 11R CE-95-3105 2010 392603.5 755856.4 21.00 128.5 130 PVC 4 PVC 4 R

392603075585603 CE Dd 147 11A CE-95-3104 2010 392603.5 755856.4 21.10 198 198 PVC 4 PVC 4 R

392520075590401 CE Dd 148 12R CE-95-3103 2010 392520.3 755904.3 37.06 40 48 PVC 4 PVC 4 R

392520075590402 CE Dd 149 14R CE-95-3102 2010 392520.3 755904.4 36.98 118 118 PVC 4 PVC 4 R

392546075581902 CE Dd 150 13A CE-95-3101 2010 392546.6 755818.7 16.45 145 248 PVC 4 PVC 4 R

392537075593001 CE Dd 151 16A CE-95-3100 1905 392536.8 755929.9 21.83 40 40 PVC 4 PVC 4 R392537075593002 CE Dd 152 16B CE-95-3099 2010 392536.8 755929.9 21.99 177 217 PVC 4 PVC 4 R

392521075583301 CE Dd 153 17A CE-95-3094 2010 392520.7 755833.2 48.34 88 88 PVC 4 PVC 4 R392521075583302 CE Dd 154 17B CE-95-3086 2010 392520.7 755833.2 47.61 162 167 PVC 4 PVC 4 R

392521075583303 CE Dd 155 17C CE-95-3085 2010 392520.7 755833.2 46.99 223 287 PVC 4 PVC 4 R

392552075591601 CE Dd 156 18B CE-95-3084 2010 392552.2 755916.4 27.19 87 127 PVC 4 PVC 4 R

392537075590101 CE Dd 157 19A CE-95-3091 2010 392536.8 755900.9 38.22 56 58 PVC 4 PVC 4 R392537075590102 CE Dd 158 19B CE-95-3092 2010 392536.8 755900.9 38.36 112 148 PVC 4 PVC 4 R

392545075594601 CE Dd 159 20A CE-95-3093 2010 392544.7 755946 28.20 35 121 PVC 4 PVC 4 R

392545075594602 CE Dd 160 20B CE-95-3083 2010 392544.7 755946 27.64 116 120 PVC 4 PVC 4 R

392530075582001 CE Dd 191 21-deep CE-95-3343 2010 392530.3 755820.5 21.49 150 197 PVC 4 PVC 4 R

392530075582002 CE Dd 192 21-shallow CE-95-3342 2010 392530.3 755820.5 21.60 67 67 PVC 4 PVC 4 R

392525075581401 CE Dd 193 22 CE-95-3350 2010 392524.6 755814.5 43.28 88 197 PVC 4 PVC 4 R

392418076013003 CE Ec 17 --- CE 73-1720 --- 392418 760129 83 --- 1,107 --- --- --- --- ---

392403075521801 CE Ee 29 --- CE-73-2266 1978 392405.3 755217.5 703 547 1,458 Steel 4 Stainless 4 R

392716076003001 CE Dc 2 --- CE-73-1722 1977 392716 760029 603 --- 936 --- --- --- --- ---

392641075550101 CE Dd 72 --- CE-71-0135 1971 392641 755500 903 320 460 PVC 2 PVC 2 P

392625075582701 CE Dd 103 --- CE-94-1759 1997 392624.5 755827.7 75.48 215 215 PVC 4 PVC 4 S

392537075575701 CE Dd 116 --- --- 1993 392546.6 755744.3 81.46 130 130 PVC 4 PVC 4 S
158 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area Table A1. Characteristics of observation and domestic wells used for hydrogeologic framework, hydrologic, and water-quality data collection in the Dredge Material Containment Area and vicinity, Cecil County, Maryland, 2010–11.—Continued [USGS, U.S. Geological Survey; USACE, U.S. Army Corps of Engineers; ddmmss.s, degrees, minutes, seconds (to nearest tenth – or .ss, hundredth); NAD83, North American Datum, 1983; NAVD88, North American Vertical Datum, 1988; ft, feet; bls, below land surface; in., inches; PVC, polyvinylchloride; Type of open interval: P-perforated, R-wire-wound screen, S-screen, X-open hole; UPA, upper Patapsco aquifer; shallow, shallow water-bearing zone; deep, deep water-bearing zone; MA, Magothy aquifer; X (G, C, and or R), implies gamma, conductance, and or resistivity geophysical logs were taken); X (M, T) implies manual intermittent water levels were recorded, and or time-series continuous monitoring data were collected; ---, missing data; np, not published] USGS well identifier USGS local identifier USACE local identifier State well permit number Year of well instal- lation Location of well Elevation of land surface near well (NAVD88) (ft) Depth of well (ft, bls) Depth of bore- hole (ft, bls) Mate- rial com- posi- tion of well Diam- eter of well (in.) Mate- rial com- posi- tion of open inter- val Di- am- eter of open in- ter- val (in.) Type of open interval Latitude (NAD83) ddmmss.s Longitude (NAD83) ddmmss.s Domestic wells 392547075592501 CE Dd 161 --- np 1989 np np 26.30 80 --- PVC 4 PVC 4 P 392540075593401 CE Dd 162 --- np 1979 np np 30.65 105 --- Steel 4 Steel 3 P 392540075593402 CE Dd 163 --- np 1985 np np 30.56 50 --- PVC 4 PVC 4 P 392541075593301 CE Dd 164 --- np 2007 np np 33.59 85 --- PVC 4 PVC 4 P 392539075593601 CE Dd 165 --- np 1988 np np 31.08 57 --- PVC 4 PVC 4 P 392546075594001 CE Dd 166 --- np 1980 np np 15.19 67 --- Steel 4 Steel 3 P 392548075594401 CE Dd 167 --- np 1991 np np 28.87 107 --- PVC 4 PVC 4 P 392543075593501 CE Dd 168 --- np 1992 np np 34.80 57 --- PVC 4 PVC 4 P 392548075593201 CE Dd 169 --- np 1986 np np 22.12 84 --- PVC 4 PVC 4 P 392516075585101 CE Dd 170 --- np 1993 np np 80.80 258 260 PVC 4 PVC 4 P 392542075593401 CE Dd 171 --- np 1996 np np 35.41 196 --- PVC 4 PVC 4 P 392542075593801 CE Dd 172 --- np 1982 np np 34.87 51 --- PVC 4 PVC 4 P 392545075593201 CE Dd 174 --- np 1997 np np 33.62 70 --- PVC 4 PVC 4 P 392545075592901 CE Dd 176 --- np --- np np 34.38 74 --- PVC 4 PVC 4 P 392548075594402 CE Dd 177 --- np 2007 np np 28.67 85 --- PVC 4 PVC 4 P 392543075594402 CE Dd 178 --- np 1994 np np 20.50 65 --- PVC 4 PVC 4 P 392542075592401 CE Dd 179 --- np 2008 np np 31.84 60 --- PVC 4 PVC 4 P 392541075595301 CE Dd 180 --- np 2000 np np 26.58 75 75 PVC 4 PVC 4 P 392542075595301 CE Dd 181 --- np 1996 np np 27.91 97 97 PVC 4 PVC 4 P 392546075594801 CE Dd 182 --- np 1993 np np 34.66 92 92 PVC 4 PVC 4 P

392546075594802 CE Dd 183 --- np 1985 np np 35.18 68 68 PVC 4 PVC 4 P

392552075594401 CE Dd 184 --- np 1998 np np 8.56 52 52 PVC 4 PVC 4 P
Appendix A 159

Table A1. Characteristics of observation and domestic wells used for hydrogeologic framework, hydrologic, and water-quality data collection in the Dredge Material Containment Area and vicinity, Cecil County, Maryland, 2010–11.—Continued[USGS, U.S. Geological Survey; USACE, U.S. Army Corps of Engineers; ddmmss.s, degrees, minutes, seconds (to nearest tenth – or .ss, hundredth); NAD83, North American Datum, 1983; NAVD88, North American Vertical Datum, 1988; ft, feet; bls, below land surface; in., inches; PVC, polyvinylchloride; Type of open interval: P-perforated, R-wire-wound screen, S-screen, X-open hole; UPA, upper Patapsco aquifer; shallow, shallow water-bearing zone; deep, deep water-bearing zone; MA, Magothy aquifer; X (G, C, and or R), implies gamma, conductance, and or resistivity geophysical logs were taken); X (M, T) implies manual intermittent water levels were recorded, and or time-series continuous monitoring data were collected; ---, missing data; np, not published]

USGS well 

identifier

USGS local 

identifier

USACE 

local 

identifier

State well 

permit 

number

Year of 

well 

installation

Location of well

Elevation of 

land surface 

near well 

(NAVD88) 

(ft)

Depth 

of well

(ft, bls)

Depth of 

borehole

(ft, bls)

Material 

composition of 

well

Diameter of 

well

(in.)

Material 

composition of 

open 

interval

Diameter 

of 

open 

interval

(in.)

Type of 

open 

interval

Latitude 

(NAD83)

ddmmss.s

Longitude 

(NAD83)

ddmmss.s

392551075594301 CE Dd 185 --- np 1994 np np 6.58 57 57 PVC 4 PVC 4 P

392544075594101 CE Dd 186 --- np 1999 np np 18.37 40 40 PVC 4 PVC 4 P

392542075594101 CE Dd 187 --- np 1987 np np 36.41 82 82 PVC 4 PVC 4 P

392552075592601 CE Dd 188 --- np 1997 np np 13.02 180 180 PVC 4 PVC 4 P

392546075592401 CE Dd 189 --- np 1977 np np 26.36 24 24 Concrete 36 --- 36 X392554075592401 CE Dd 190 --- np 2008 np np 11.90 60 60 PVC 4 PVC 4 P
160 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area Table A1. Characteristics of observation and domestic wells used for hydrogeologic framework, hydrologic, and water-quality data collection in the Dredge Material Containment Facility and vicinity, Cecil County, Maryland, 2010–11.—Continued [USGS, U.S. Geological Survey; USACE, U.S. Army Corps of Engineers; ddmmss.s, degrees, minutes, seconds (to nearest tenth – or .ss, hundredth); NAD83, North American Datum, 1983; NAVD88, North American Vertical Datum, 1988; ft, feet; bls, below land surface; in., inches; PVC, polyvinylchloride; Type of open interval: P-perforated, R-wire-wound screen, S-screen, X-open hole; UPA, upper Patapsco aquifer; shallow, shallow water-bearing zone; deep, deep water-bearing zone; MA, Magothy aquifer; X (G, C, and or R), implies gamma, conductance, and or resistivity geophysical logs were taken); X (M, T) implies manual intermittent water levels were recorded, and or time-series continuous monitoring data were collected; ---, missing data; np, not published] USGS well identifier USGS local identifier USACE local identifier State well permit number Depth to top of open interval (ft, bls) Depth to bot- tom of open inter- val (ft, bls) Altitude of top of screened interval (NAVD88) (ft) Altitude of bottom of screened interval (NAVD88) (ft) Aquifer and local water- bearing zone in which well was com- pleted Current measur- ing point, height above land surface (ft) Current measur- ing point altitude (NAVD88) (ft) Indicator (X) of type(s) of data collected from well1 Hydro- geologic Hydro- logic Water quality Observation wells 392536075593201 CE Dd 81 --- CE-81-0469 110 115 -88.30 -93.30 UPA, shallow 2.96 24.66 X (G, R) X (M, T)

X

392536075591901 CE Dd 122 CSW 1 CE-94-1016 119 129.33 -84.12 -94.45 UPA, shallow 2.91 37.79 X (G, C) X (M, T)

X

392536075592001 CE Dd 123 CSW 4 CE-94-1019 48.67 59 -12.81 -23.14 MA 3.04 38.90 --- X (M, T) ---

392536075592002 CE Dd 124 CSW 6 CE-94-1020 21 22 14.82 13.82 Fill material 3.04 38.86 --- X (M)

X

392514075584301 CE Dd 125 CSW 5 CE-94-1080 80.33 90.33 -33.37 -43.37 MA -0.07 46.89 X (G, C) X (M)

X

392556075590001 CE Dd 126 CSW 2 CE-94-1017 117.5 127.5 -78.47 -88.47 UPA, shallow 2.28 41.31 X (G, C) X (M, T)

X

392550075593901 CE Dd 127 CSW 7 CE-94-1021 80.97 91.3 -72.97 -83.30 UPA, shallow -0.29 7.71 X (G, C) X (M, T)

X

392540075594401 CE Dd 128 CSW 8 CE-94-1081 117.92 128.25 -92.69 -103.02 UPA, shallow -0.35 24.88 X (G, C) X (M)

X

392547075591701 CE Dd 129 CSW 9 CE-94-1134 114.67 125 -86.60 -96.93 UPA, shallow 2.52 30.59 X (G, C) X (M)

X

392539075592201 CE Dd 130 CSW 10 CE-94-1447 100 115 -70.54 -85.54 UPA, shallow 2.70 32.16 X (G, C) X (M) ---

392603075585601 CE Dd 131 CSW 11 CE-94-1448 53 58 -31.53 -36.53 MA 2.77 24.24 --- X (M) ---

392520075590301 CE Dd 132 CSW 12 CE-94-1449 28 38 7.30 -2.70 MA 2.84 38.14 --- X (M) ---

392546075581901 CE Dd 133 CSW 13 CE-94-1450 48 53 -32.00 -37.00 MA 1.40 17.40 X (G, C) X (M)

X

392520075590302 CE Dd 134 CSW 14 CE-94-1451 109 119 -74.42 -84.42 UPA, shallow 2.92 37.50 --- X (M) ---

392546075584801 CE Dd 135 CSW 15 CE-94-1452 89 99 -46.25 -56.25 MA 2.90 45.65 X (G) X (M)

X

392556075590002 CE Dd 136 2A CE-95-3089 50 55 -11.55 -16.55 MA 3.16 41.61 --- X (M, T)

X

392527075590802 CE Dd 137 3A CE-95-3098 53 63 -16.18 -26.18 MA 2.38 39.20 --- X (M)

X

392527075590801 CE Dd 138 3R CE-95-3097 110 120 -73.15 -83.15 UPA, shallow 2.34 39.19 X (G, C) X (M)

X

392536075592003 CE Dd 139 4R CE-95-3090 48 58 -13.14 -23.14 MA 2.79 37.65 --- X (M)

X

392548075593801 CE Dd 140 7A CE-95-3096 11 16 0.47 -4.53 MA 1.84 13.31 --- X (M)

X

392548075593802 CE Dd 141 7B CE-95-3095 217 222 -205.79 -210.79 UPA, deep 1.45 12.66 X (G, C) X (M, T)

X

392540075594501 CE Dd 142 8A CE-95-3088 79 89 -55.45 -65.45 UPA, shallow 1.67 25.22 X (G, C) X (M)

X

392540075594502 CE Dd 143 8B CE-95-3087 39 44 -15.28 -20.28 MA 1.66 25.38 --- X (M)

X

392547075591702 CE Dd 144 9A CE-95-3107 22 27 6.12 1.12 perched 2.88 31.00 --- X (M)

X

392603075585602 CE Dd 145 11C CE-95-3106 20 30 1.00 -9.00 MA 2.42 23.42 --- X (M)

X

392603075585604 CE Dd 146 11R CE-95-3105 118.5 128.5 -97.50 -107.50 UPA, shallow 2.41 23.41 --- X (M)

X
Appendix A 161

Table A1. Characteristics of observation and domestic wells used for hydrogeologic framework, hydrologic, and water-quality data collection in the Dredge Material Containment Facility and vicinity, Cecil County, Maryland, 2010–11.—Continued[USGS, U.S. Geological Survey; USACE, U.S. Army Corps of Engineers; ddmmss.s, degrees, minutes, seconds (to nearest tenth – or .ss, hundredth); NAD83, North American Datum, 1983; NAVD88, North American Vertical Datum, 1988; ft, feet; bls, below land surface; in., inches; PVC, polyvinylchloride; Type of open interval: P-perforated, R-wire-wound screen, S-screen, X-open hole; UPA, upper Patapsco aquifer; shallow, shallow water-bearing zone; deep, deep water-bearing zone; MA, Magothy aquifer; X (G, C, and or R), implies gamma, conductance, and or resistivity geophysical logs were taken); X (M, T) implies manual intermittent water levels were recorded, and or time-series continuous monitoring data were collected; ---, missing data; np, not published]

USGS 

well 

identifier

USGS 

local 

identifier

USACE 

local 

identifier

State well 

permit 

number

Depth 

to top 

of open 

interval

(ft, bls)

Depth 

to bottom of 

open 

interval

(ft, bls)

Altitude 

of top of 

screened 

interval 

(NAVD88) 

(ft)

Altitude of 

bottom of 

screened 

interval 

(NAVD88) 

(ft)

Aquifer and 

local waterbearing zone 

in which well 

was completed

Current 

measuring point, 

height 

above 

land 

surface

(ft)

Current 

measuring point 

altitude 

(NAVD88)

(ft)

Indicator (X) of type(s) of data 

collected from well1

Hydrogeologic Hydro- logic Water quality

392603075585603 CE Dd 147 11A CE-95-3104 188 198 -166.90 -176.90 UPA, deep 2.42 23.52 X (G, C) X (M) X392520075590401 CE Dd 148 12R CE-95-3103 35 40 2.06 -2.94 MA 2.56 39.62 -- X (M) ---2

392520075590402 CE Dd 149 14R CE-95-3102 108 118 -71.02 -81.02 UPA, shallow 2.54 39.52 X (G, C) X (M) X

392546075581902 CE Dd 150 13A CE-95-3101 135 145 -118.55 -128.55 UPA, shallow 3.04 19.49 X (G, C) X (M) X

392537075593001 CE Dd 151 16A CE-95-3100 30 40 -8.17 -18.17 Magothy 2.38 24.21 --- X (M, T) X

392537075593002 CE Dd 152 16B CE-95-3099 167 177 -145.01 -155.01 UPA, deep 2.12 24.11 X (G, C) X (M, T) X

392521075583301 CE Dd 153 17A CE-95-3094 78 88 -29.66 -39.66 MA 1.65 49.99 --- X (M, T) X

392521075583302 CE Dd 154 17B CE-95-3086 152 162 -104.39 -114.39 UPA, shallow 1.70 49.31 --- X (M, T) X

392521075583303 CE Dd 155 17C CE-95-3085 213 223 -166.01 -176.01 UPA, deep 1.71 48.70 X (G, C) X (M, T) X

392552075591601 CE Dd 156 18B CE-95-3084 77 87 -49.81 -59.81 UPA, shallow 3.00 30.19 X (G, C) X (M) X

392537075590101 CE Dd 157 19A CE-95-3091 51 56 -12.78 -17.78 MA 2.32 40.54 --- X (M) X

392537075590102 CE Dd 158 19B CE-95-3092 107 112 -68.64 -73.64 UPA, shallow 2.33 40.69 X (G, C) X (M) X

392545075594601 CE Dd 159 20A CE-95-3093 25 35 3.20 -6.80 MA -0.25 27.95 X (G) X (M) ---2

392545075594602 CE Dd 160 20B CE-95-3083 106 116 -78.36 -88.36 UPA, shallow -0.40 27.24 X (G, C) X (M) X

392530075582001 CE Dd 191 21-deep CE-95-3343 145 150 -123.51 -128.51 UPA, shallow 2.03 23.52 X (G, C) X (M, T) X

392530075582002 CE Dd 192 21-shallow CE-95-3342 57 67 -35.40 -45.40 MA 2.34 23.94 --- X (M, T) X

392525075581401 CE Dd 193 22 CE-95-3350 78 88 -34.72 -44.72 MA 2.20 45.48 X (G, C) X (M, T) X

392418076013003 CE Ec 17 --- CE 73-1720 --- --- --- --- Wissahickon 

Schist

--- ---- X (G) --- ---

392403075521801 CE Ee 29 --- CE-73-2266 515 525 -440 -450 UPA 2.35 77.35 X (G) --- ---

392716076003001 CE Dc 2 --- CE-73-1722 --- --- --- --- Wissahickon 

Schist

--- --- X (G) --- ---

392641075550101 CE Dd 72 --- CE-71-0135 300 320 -210 -230 Potomac 

Group

--- --- X (G) --- ---

392625075582701 CE Dd 103 --- CE-94-1759 190 215 -114.52 -139.52 Potomac 

Group

0.31 75.79 --- X (M) ---

392537075575701 CE Dd 116 --- --- 120 130 -38.54 -48.54 MA 1.33 82.79 --- X (M) ---
162 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area Table A1. Characteristics of observation and domestic wells used for hydrogeologic framework, hydrologic, and water-quality data collection in the Dredge Material Containment Facility and vicinity, Cecil County, Maryland, 2010–11.—Continued [USGS, U.S. Geological Survey; USACE, U.S. Army Corps of Engineers; ddmmss.s, degrees, minutes, seconds (to nearest tenth – or .ss, hundredth); NAD83, North American Datum, 1983; NAVD88, North American Vertical Datum, 1988; ft, feet; bls, below land surface; in., inches; PVC, polyvinylchloride; Type of open interval: P-perforated, R-wire-wound screen, S-screen, X-open hole; UPA, upper Patapsco aquifer; shallow, shallow water-bearing zone; deep, deep water-bearing zone; MA, Magothy aquifer; X (G, C, and or R), implies gamma, conductance, and or resistivity geophysical logs were taken); X (M, T) implies manual intermittent water levels were recorded, and or time-series continuous monitoring data were collected; ---, missing data; np, not published] USGS well identifier USGS local identifier USACE local identifier State well permit number Depth to top of open interval (ft, bls) Depth to bot- tom of open inter- val (ft, bls) Altitude of top of screened interval (NAVD88) (ft) Altitude of bottom of screened interval (NAVD88) (ft) Aquifer and local water- bearing zone in which well was com- pleted Current measur- ing point, height above land surface (ft) Current measur- ing point altitude (NAVD88) (ft) Indicator (X) of type(s) of data collected from well1 Hydro- geologic Hydro- logic Water quality Domestic wells 392547075592501 CE Dd 161 --- np 65 80 -38.7 -53.7 UPA, shallow 0.79 27.09 --- X (M)

X

392540075593401 CE Dd 162 --- np 97 105 -66.35 -74.35 UPA, shallow 1.40 32.05 --- X (M) ---

392540075593402 CE Dd 163 --- np 44 50 -13.44 -19.44 MA 0.50 31.06 --- X (M)

X

392541075593301 CE Dd 164 --- np 75 85 -41.41 -51.41 UPA, shallow 0.55 34.14 --- X (M)

X

392539075593601 CE Dd 165 --- np 50 57 -18.92 -25.92 MA 0.96 32.04 --- X (M)

X

392546075594001 CE Dd 166 --- np 59 67 -43.81 -51.81 UPA, shallow 0.72 15.91 --- X (M)

X

392548075594401 CE Dd 167 --- np 97 107 -68.13 -78.13 UPA, shallow 0.85 29.72 --- X (M) ---

392543075593501 CE Dd 168 --- np 50 57 -15.2 -22.2 MA 0.89 35.69 --- X (M)

X

392548075593201 CE Dd 169 --- np 74 84 -51.88 -61.88 UPA, shallow 0.41 22.53 --- X (M)

X

392516075585101 CE Dd 170 --- np 248 258 -167.2 -177.2 UPA, deep 0.70 81.50 --- X (M)

X

392542075593401 CE Dd 171 --- np 191 196 -155.59 -160.59 UPA, deep 0.50 35.91 --- X (M)

X

392542075593801 CE Dd 172 --- np 47 51 -12.13 -16.13 MA 1.10 35.97 --- X (M)

X

392545075593201 CE Dd 174 --- np 60 70 -26.38 -36.38 UPA, shallow 0.65 34.27 --- X (M)

X

392545075592901 CE Dd 176 --- np 64 74 -29.62 -39.62 UPA, shallow 0.75 35.13 --- X (M)

X

392548075594402 CE Dd 177 --- np 75 85 -46.33 -56.33 UPA, shallow 0.79 29.46 --- X (M)

X

392543075594402 CE Dd 178 --- np 55 65 -34.5 -44.5 UPA, shallow 1.40 21.90 --- X (M)

X

392542075592401 CE Dd 179 --- np 50 60 -18.16 -28.16 MA 1.75 33.59 --- X (M)

X

392541075595301 CE Dd 180 --- np 70 75 -43.42 -48.42 UPA, shallow 1.30 27.88 --- X (M) ---

392542075595301 CE Dd 181 --- np 87 97 -59.09 -69.09 UPA, shallow 1.12 29.03 --- X (M) ---

392546075594801 CE Dd 182 --- np 87 92 -52.34 -57.34 UPA, shallow 0.53 35.19 --- X (M) ---

392546075594802 CE Dd 183 --- np 60 68 -24.82 -32.82 UPA, shallow 0.80 35.98 --- X (M) ---

392552075594401 CE Dd 184 --- np 42 52 -33.44 -43.44 UPA, shallow 0.37 8.93 --- X (M) ---

392551075594301 CE Dd 185 --- np 50 57 -43.42 -50.42 UPA, shallow 1.10 7.68 --- X (M) ---
Appendix A 163

Table A1. Characteristics of observation and domestic wells used for hydrogeologic framework, hydrologic, and water-quality data collection in the Dredge Material Containment Facility and vicinity, Cecil County, Maryland, 2010–11.—Continued[USGS, U.S. Geological Survey; USACE, U.S. Army Corps of Engineers; ddmmss.s, degrees, minutes, seconds (to nearest tenth – or .ss, hundredth); NAD83, North American Datum, 1983; NAVD88, North American Vertical Datum, 1988; ft, feet; bls, below land surface; in., inches; PVC, polyvinylchloride; Type of open interval: P-perforated, R-wire-wound screen, S-screen, X-open hole; UPA, upper Patapsco aquifer; shallow, shallow water-bearing zone; deep, deep water-bearing zone; MA, Magothy aquifer; X (G, C, and or R), implies gamma, conductance, and or resistivity geophysical logs were taken); X (M, T) implies manual intermittent water levels were recorded, and or time-series continuous monitoring data were collected; ---, missing data; np, not published]

USGS 

well 

identifier

USGS 

local 

identifier

USACE 

local 

identifier

State well 

permit 

number

Depth 

to top 

of open 

interval

(ft, bls)

Depth 

to bottom of 

open 

interval

(ft, bls)

Altitude 

of top of 

screened 

interval 

(NAVD88) 

(ft)

Altitude of 

bottom of 

screened 

interval 

(NAVD88) 

(ft)

Aquifer and 

local waterbearing zone 

in which well 

was completed

Current 

measuring point, 

height 

above 

land 

surface

(ft)

Current 

measuring point 

altitude 

(NAVD88)

(ft)

Indicator (X) of type(s) of data 

collected from well1

Hydrogeologic Hydro- logic Water quality

392544075594101 CE Dd 186 --- np 30 40 -11.63 -21.63 MA 1.65 20.02 --- X (M) ---

392542075594101 CE Dd 187 --- np 72 82 -35.59 -45.59 UPA, shallow 0.31 36.72 --- X (M) ---

392552075592601 CE Dd 188 --- np 160 180 -146.98 -166.98 UPA, deep 1.19 14.21 --- X (M) ---

392546075592401 CE Dd 189 --- np 23 24 3.36 2.36 perched 0.20 26.56 --- X (M) ---

392554075592401 CE Dd 190 --- np 50 60 -38.10 -48.10 UPA, shallow 1.30 13.20 --- X (M) ---

1 Detailed description of each type of data collected from each well is further described in main report.2 Attempted to obtain water quality samples and data on two separate occasions; well yield insufficient to obtain sample.3 Land surface altitude is estimated, not surveyed in.
164 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

Introduction

Water-quality field measurements and laboratory analyses were conducted in 2010–11 to provide data on the physical and chemical characteristics of groundwater and surface 

water in the Pearce Creek Dredge Material Containment Area 

(DMCA) and vicinity, Cecil County, Maryland. The data 

collected included quality-control (QC) samples and measurements at selected groundwater and surface-water sites to help 

determine the accuracy and comparability of the water-quality 

data. Modified laboratory methods also were used to obtain 

data for selected water-quality constituents because of samplematrix interferences likely associated with the high dissolvedsolids concentrations of groundwater in the study area. All 

tables referenced in this appendix are linked to an Excel file.

Extent and Types of Data Collected

 Water-quality measurements and samples were collected 

at 36 observation wells, 15 domestic water-supply wells, 

and two surface-water sites during 2010–11. A broad variety 

of data were collected at each site on general water-quality 

characteristics, major ions, trace elements, pesticides, and 

wastewater compounds. However, survey (occurrence and 

distribution) data for pesticides and wastewater compounds 

in groundwater and surface waters were obtained from only 

shallow observation wells, in addition to all domestic supply 

wells, and both surface-water sites. The types of water-quality 

data collected have been summarized by category or type for 

each groundwater or surface-water site (table B1, link to Excel 

file).

Quality-control samples and measurements were obtained 

at selected groundwater and surface-water sites to help determine the accuracy and comparability of the water-quality data. 

At selected monitoring and observation wells, field blanks 

were collected on site to assess potential sample contamination, and duplicate sequential groundwater samples were 

obtained to assess measurement precision. At selected sites, 

additional replicate sequential groundwater samples were 

collected for selected laboratory-analyzed samples, including 

pesticide or wastewater compounds, for laboratory spikes. 

Laboratory spikes were performed to assess whether any 

chemical precipitation from sample oxidation during shipping 

or handling of samples in the laboratory reduced the recovery 

of these compounds. In addition, standard reference samples, 

obtained from the U.S. Geological Survey (USGS) Branch 

of Quality Systems (BQS), Denver, Colorado, were submitted from the field to the National Water Quality Laboratory 

(NWQL) to assess the accuracy of analysis for selected trace 

elements. Table B2 (link to Excel file) summarizes the different types of field QC samples collected, their site of collection, and the types and categories of water-quality constituents 

assessed in relation to that QC sample.

Water-Quality and Quality-Control Data

Water-quality data from most observation wells (30 of 

36) and all domestic supply wells (15) were obtained during April through mid-June, 2010. Data for five additional 

monitoring wells installed late in 2010, and from two nearby 

surface-water sites—the Elk River and Pearce Creek Lake—

were obtained February 9–10, 2011. The data for both periods 

of data collection are summarized by general water-quality 

category or type (table B3, link to Excel file). The associated 

QC data have been summarized in a manner consistent with 

their use to address the objectives of this report (table B4, link 

to Excel file).

In relation to both the water-quality and QC data, the 

nomenclature regarding the types of data warrants discussion. 

References to constituent results for raw water, for example, 

“pH, raw water,” imply a measurement [analysis] made on 

unaltered groundwater discharge from the well. References 

to results for constituents dissolved in water, for example, 

“Chloride, dissolved water,” a measurement made on a sample 

of groundwater being discharged from the well, was filtered 

in the field when collected, and may have been filtered again 

in the laboratory before analysis. Major anions fall into this 

category, including bromide, chloride, and fluoride, as well as 

sulfate, and ammonia-, nitrite, and nitrate-plus-nitrite nitrogen.

The majority of the inorganic water-quality data are 

expressed as “dissolved recoverable,” which implies a 

measurement obtained from a sample of groundwater being 

discharged from the well that was filtered in the field when 

collected, then if inorganic in nature, also preserved with 

acid in the field, but ultimately analyzed by a USGS laboratory after an initial in-bottle digestion with nitric acid—as 

if it were a whole-water recoverable sample. The digestion 

procedure was essential to ensure any colloidal precipitates, 

which formed after collection and because of oxidation of the 

sample, were dissolved and incorporated into the original dissolved sample. In the case of other dissolved recoverable constituents, including organic carbon, and ammonia-plus-organic 

Appendix B: Water-Quality and Quality-Control Data and 

Custom Methods Used in the Investigation of the Pearce 

Creek Dredge Material Containment Area and Vicinity, 

Cecil County, Maryland, 2010–11
Appendix B 165

nitrogen, which also initially were chemically preserved with 

acids, other and more rigorous digestion procedures were used 

to ensure results reflected the original dissolved samples. In 

the case of pesticides and wastewater compounds, which were 

preserved by chilling, rather than acidification, representative 

samples of water and any suspended material were extracted 

rather than digested to ensure the results reflected the original 

dissolved samples. Details of the specific digestion or extraction procedure used, which were conducted in accordance 

with standard reference methods, are provided in the laboratory reference for each inorganic constituent (table B5, link to 

Excel file).

Overall, whole-water recoverable methods reflect the 

constituents in solution after a representative water-suspendedsediment sample is digested or extracted. In the case of this 

study, complete dissolution of any colloidal material likely 

was achieved, as field-acidified samples did not appear to 

form visible colloidal precipitates after samples were oxidized 

and the digested samples for inorganics, organic carbon, and 

ammonia-plus-organic nitrogen, have remained clear for 

months following their initial oxidation (D. Damrau, USGS, 

written commun., 2011). Suspensions did form in selected 

pesticide and wastewater samples after their oxidation in the 

laboratory. However, the efficiency of the extractions for pesticide and wastewater compounds was assessed to determine if 

the suspensions biased the recovery of these compounds (see 

below).

For selected constituents—nitrate-plus-nitrite nitrogen, 

beryllium, arsenic, and sulfate—data reference the use of a 

“modified method.” Historical or preliminary QC data for each 

of these constituents indicated that the standard method for 

these constituents was inadequate to obtain accurate measurements, mainly because of sample-matrix interferences that 

could not be addressed without some modification to the standard method. These water-quality constituents were analyzed 

with modified standard methods, which are described later in 

this appendix.

Quality-Control Data Tables for 

Interpretation

Tables used to create summary QC data and determine 

the quality of groundwater and surface-water data as described 

in the main body of this report are as follows:

To assess the potential contamination of water-quality 

samples during or after their collection from field blanks 

(table B6, link to Excel file); a summary table of these data 

are discussed in the main report (table 2);

To assess the precision of measurement of commonly 

measureable water-quality constituents from sequential replicate groundwater samples (table B7, link to Excel file); a summary table of these data are discussed in main report (table 3);

To assess the potential influence of sample matrix bias 

on the recovery of pesticide compounds from low-level (0.2 

to 0.8 μg/L, micrograms per liter) analytical methods used by 

the USGS Organic Geochemistry Research Laboratory, from 

spiked groundwater samples and surrogate constituents in all 

samples (table B8, link to Excel file); a summary table of these 

data is discussed in the main report (table 4);

To assess the potential influence of sample matrix bias 

on the recovery of wastewater compounds from analytical 

methods used by the USGS NWQL from spiked groundwater 

samples and surrogate constituents in all samples (table B9,

link to Excel file); a summary table of these data is discussed 

in the main report (table 5); and

To assess measurement accuracy, standard reference 

samples, from USGS BQS, for trace elements were sent as 

blind water-quality samples from the field (table B10, link to 

Excel file); these data are discussed in the main report. 

In addition, mass equivalent balances were computed 

for major ionic constituents in milliequivalents per liter 

(table B11, link to Excel file); a summary table of these data is 

discussed in the main report (table 6).

In addition, all pesticides detected in groundwater 

samples with low-level detection methods are summarized 

(table B12, link to Excel file) to facilitate their interpretation and discussion in the main report. Within the context of 

each of the above tables, QC as well as water-quality data for 

selected constituents were obtained with modified standard 

methods for four water-quality constituents—nitrate-plusnitrite nitrogen, arsenic, beryllium, and sulfate. The modified 

standard method for each of these constituents is described 

below.

Modified Standard Laboratory Methods 

for the Analysis of Selected WaterQuality Constituents

Modified laboratory methods were employed by the 

USGS laboratories to obtain accurate measurements of four 

water-quality constituents—nitrate-plus-nitrite nitrogen, 

arsenic, beryllium, and sulfate. A description of the modified 

method and the associated field and laboratory control data to 

support the validation of the resultant water-quality data for 

interpretive use in this report are provided below.

Nitrate-plus-Nitrite Nitrogen

Historical data indicated there was little to no measureable nitrate and nitrite but highly elevated concentrations of 

dissolved iron in groundwater in the DMCA and vicinity (U.S. 

Army Corps of Engineers, 1996; Weston, Inc., 1998). Given 

elevated concentrations of dissolved iron in the form of ferrous 

iron, the latter can be preferentially reduced instead of nitrate 

using the standard cadmium-reduction method for nitrate 

analysis, and lead to low-biased or immeasurable concentrations of nitrate-plus-nitrite nitrogen (Patton and Kryskalla, 
166 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

2011). To avoid this potential bias, the USGS NWQL recently 

developed a nitrate reductase method, which reduces nitrate 

to nitrite (Patton and Kryskalla, 2011). The nitrite concentration is then determined using the standard spectrophotometric 

(colorimetric) phosphomolybdenum-blue complex analytical 

method.

With few exceptions, all laboratory QC data were within 

acceptable limits (table B13, link to Excel file). Laboratory 

blanks contained trace (0.01–0.05 mg/L) to undetectable 

(or less than the laboratory reporting level of < 0.04 mg/L) 

concentrations of nitrate-plus-nitrite nitrogen. Except for three 

water-quality samples, recoveries on spiked samples of all 

types—laboratory blanks, field blanks, duplicate sequential 

samples, and water-quality samples—were similar, and generally within the acceptable control range for standard NWQL 

methods—85–115 percent. High recoveries (124, 147, and 

162 percent) occurred on the water-quality sample for wells 

CE Dd 163, CE Dd 168 duplicate sequential sample, and CE 

Dd 172, respectively. CE Dd 172, which required dilution, 

and thus concentrations of nitrate-plus-nitrite nitrogen would 

be expected to have a higher or lower than normal variability 

in recovery.

Beryllium

Concentrations of beryllium were determined by the 

USGS NWQL using a modified standard inductively coupled 

plasma-mass spectrometry (ICP-MS) method. Whole-water 

recoverable beryllium is routinely determined along with other 

trace elements simultaneously on a single sample by using 

ICP-MS (Garbarino and Struzeski, 1998)1. An aerosol of the 

sample solution is produced by using a high-dissolved-solids 

tolerant nebulizer. The aerosol is introduced into the argon 

plasma where it undergoes desolvation, atomization, and 

ionization. Ions are sampled through multiple orifices into the 

quadrupole mass spectrometer where they are separated on 

the basis of their mass-to-charge ratios. An electron multiplier detects the ions by generating a current that is directly 

proportional to the concentration of the element present in the 

sample. The effects of sample transport, instrumental drift, 

and matrix-induced fluctuations in plasma characteristics are 

reduced by using the ratio of elemental ion intensity to the 

internal standard element ion intensity for calibration. The 

described method is for the determination of multiple elements 

in a sample. The standard optimization procedure consists of 

maximizing the signal for three elements spanning the entire 

mass spectrum (7

Li, 89Y, and 205Tl) while maintaining ion 

doubly-charged and oxide levels below pre-determined values. 

Optimization is achieved through the adjustment of argon gas 

flows, electrical lenses, quadrupole electrical settings, and 

electron multiplier settings.

Preliminary QC information for beryllium determinations conducted with the standard method described above 

indicated that concentrations of beryllium could be biased 

1

See table B5.

and underestimated (Mark R. Hill, USGS, written commun., 

2011). Minimal modifications were made to the standard 

method optimization procedures to enhance the ICP-MS determinations of beryllium. Also, an alternate internal standard 

was used for beryllium, which is permissible under the NWQL 

ICP-MS methodology. In routine analyses at the NWQL, 

concentrations of beryllium generally are determined by ratios 

to germanium-72, 72Ge. However, for water-quality samples 

analyzed in this study, the most accurate determination of 

beryllium was obtained with beryllium ratios to rhodium-103, 

103Rh. The latter was determined on the basis of recoveries 

of beryllium from laboratory spikes of reagent blanks, field 

blanks, and groundwater samples, as well as internal beryllium standard-reference samples, whose spiked or reference 

concentrations were similar to the range in beryllium concentrations found in groundwater samples from the study area.

All laboratory control data indicated that the beryllium 

water-quality data are suitable for interpretation. Laboratory 

QC data for beryllium were within acceptable limits (table 

B14, link to Excel file). All laboratory (and field) blanks contained immeasurable (< 0.04 μg/L) concentrations of beryllium. The beryllium concentrations in the spiked and reference 

samples were similar to the range of arsenic values found in 

groundwater and surface-water samples from the study area. 

Despite considerable differences in the range of dilution rates 

among samples, recoveries (beryllium) on spiked samples of 

all types—laboratory blanks, field blanks, duplicate sequential samples, and water-quality samples—were similar, and 

all within the generally acceptable control range for standard 

NWQL ICP-MS methods for trace elements—80–120 percent. 

A high recovery (146 percent) occurred on the water-quality 

sample for well CE Dd 146, which was the only sample that 

required dilution, and thus concentrations of beryllium would 

be expected to have a higher or lower than normal variability in recovery. Concentrations for three standard reference 

samples, each analyzed multiple times, all fell within plus or 

minus (±) 30 percent, and, in most cases were within ± 2 SD 

(standard deviations) of the most probable value (MPV), and 

within the acceptable QC range.

Arsenic

Preliminary QC information indicated that the analysis 

of arsenic with standard ICP-MS methods used by the NWQL 

failed to pass laboratory quality controls due to sample-matrix 

interferences. An alternative standard method for the analysis 

of arsenic is through conversion of arsenic to arsenic hydride 

(arsine) and analysis of arsenic hydride by atomic fluorescence 

spectrometry (Hageman and others, 2002).

The determination of total arsenic requires that all the 

arsenic be in the inorganic As(III) state. Organic and inorganic 

forms of arsenic are first oxidized to As(V) by digestion with 

a mixture of saturated potassium persulfate and concentrated 

hydrochloric acid in open polychlorofluorocarbon vessels. The 

As(V) is then quantitatively reduced to As(III) by adding a 
Appendix B 167

potassium iodide/ascorbic acid reagent. Sodium borohydride 

is added to the solution, which results in rapid formation of the 

arsenic hydride as illustrated by:

3 NaBH4 + 4H3AsO3 → 4 AsH3(g) + 3 H3BO3 + 3 NaOH (B1)

The gaseous arsine is phase separated from the analytical 

solution stream and transported with argon gas to the atomizer 

(a hydrogen flame) of the atomic fluorescence spectrometer. 

The sodium borohydride reducing agent, by rapid generation 

of the elemental hydride in the reaction cell, minimizes dilution of the arsine by the carrier gas and provides rapid, sensitive determinations of arsenic.

Concentrations of arsenic in the samples are quantified 

using calibration standards in solutions of a similar matrix. QC 

information for arsenic determinations was obtained by digesting, and subsequently analyzing, water reference samples purchased from the National Research Council, Canada (NASS-5 

seawater and SLEW-3 estuarine water) that have certified 

values for their arsenic concentrations in highly saline media. 

QC data were also obtained by digesting and determining the 

total arsenic content of four different aqueous standard reference samples (“T” standards) produced by the USGS’s BQS, 

and on the basis of recoveries obtained from laboratory spikes 

of reagent blanks, field blanks, and groundwater samples.

All laboratory control data indicated that the arsenic 

water-quality data are suitable for interpretation. Laboratory 

QC data for arsenic were within acceptable limits (table B15,

link to Excel file). All laboratory (and field) blanks contained 

trace (0.10–0.15 μg/L), or immeasurable (< 0.10 μg/L), concentrations of arsenic. Thus, trace levels of arsenic in groundwater and surface-water samples could reflect a very low level 

contamination bias. Despite considerable differences in the 

range of dilution rates among samples, recoveries on spiked 

samples of all types—laboratory blanks, field blanks, duplicate 

sequential samples, and water-quality samples—were similar, 

and all were within the generally acceptable control range 

for standard NWQL ICP-MS methods for trace elements 

(80–120 percent). In addition, all standard reference sample 

concentrations fell within the acceptable range of being within 

± 3 SD of the MPV, and in most cases were within ± 2 SD of 

the MPV. The arsenic concentrations in the spiked and reference samples were similar to the range of arsenic values found 

in groundwater and surface-water samples from the study area.

Sulfate

The analysis of sulfate in water is routinely conducted 

by the USGS NWQL with a standard ICP method (Garbarino 

and Struzeski, 1998). Preliminary QC information for selected 

samples repeatedly failed to pass laboratory quality controls 

due to sample-matrix interferences—generally related to 

samples with elevated concentrations of dissolved recoverable solids. An alternative standard method for the analysis 

of sulfate is to convert sulfate (ion) to barium sulfate (solid) 

and measure a colloidal dispersion of the barium sulfate with 

a nephelometric turbidimeter (U.S. Environmental Protection 

Agency, 2005, Method 375.4). The concentration of sulfate in 

the sample is determined as a ratio against similarly prepared 

and analyzed barium-sulfate standards. General comparisons 

between these two methods have shown that they provide 

similar results given low dilution rates are maintained for the 

barium-sulfate analyses (Reisman and others, 2007).

For the purposes of this report—and the analysis and 

interpretation of sulfate data—we employed a nephelometric turbidity ratio unit spectrophotometer and the Hach, Inc. 

(2008a,b) methods for barium-sulfate analyses. Limitations 

in this method are twofold. First, the method reporting level 

for the barium-sulfate method (40 mg/L) is higher than the 

method reporting level for the ICP method (10 mg/L). Second, the dilution rate for the barium-sulfate method had to be 

generally less than 5:1 to avoid bias in measurements related 

to the use of high dilution rates (Reisman and others, 2007).

Because of limitations in dilution rates and a high method 

reporting level, data from the barium-sulfate method were 

correlated to data from the ICP method on the basis of samples Inductively coupled plasma sulfate concentration, in milligrams per liter 

Barium-sulfate turbidimetric method sulfate concentration,

in milligrams per liter 

Sample analyzed by both methods

Estimated ICP concentration using

 barrium-sulfate concentration and

 linear regression equation:

 Sulfate (mg/L)ICP = 1.14 × Sulfate (mg/L)BaSO4

− 56.0

 R-squared = 0.995; p < 0.00001

EXPLANATION

1:1 Correspondence Line

0 

500 

1,000 

1,500 

2,000 

2,500 

3,000 

3,500 

0 500 1,000 1,500 2,000 2,500 3,000 3,500 

Figure B1. Relation between sulfate concentration in 

milligrams per liter (mg/L) determined with the barium-sulfate 

method and the inductively coupled plasma (ICP) method 

for samples collected in the Pearce Creek Dredge Material 

Containment Area and vicinity, Cecil County, Maryland, 

2010–11.
168 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

analyzed with both methods. The established linear relation 

between sulfate concentrations then was used to estimate the 

concentration of sulfate relative to the ICP method on the basis 

of the concentration of sulfate determined with the bariumsulfate method for those groundwater samples with sulfate 

concentrations that could not be determined with the ICP 

method.

The relation between sulfate concentrations on the basis 

of samples analyzed with both methods was linear, positive, and highly significant (fig. B1, correlation coefficient 

(R-squared) equal to 0.995, and power of test, p, less than 

0.00001). In addition, results were consistent between the 

two methods in relation to field blanks – the barium-sulfate 

method reporting as < 40 mg/L and the ICP method reporting 

as < 0.18 mg/L (table B16, link to Excel file).

Validation of Net Acidity with Hot 

Acidity Titrations

Kirby and Cravotta (2005b) recommended that net acidity be determined as follows:

AcidityNet = AcidityCalculated – AlkalinityStdMthd (B2)

Where each of the above terms is expressed in milligrams 

per liter as calcium carbonate (CaCO3), AlkalinityStdMthd is 

determined by standard methods, and AcidityCalculated is given 

by:

AcidityCalculated=50{1,000(10-pH) + [2(Fe2+) + 3(Fe3+)]/56 + 

2(Mn2+)/55 +3(Al3+)/27} (B3)

Where the pH is measured and expressed in standard 

units, the total dissolved metal (Fe2+, Fe3+, Mn2+ and Al3+) concentrations are in milligrams per liter, each converted to milliequivalents per liter, using their valences and formula weights, 

and the entire expression then converted to mg/L as CaCO3

.

Kirby and Cravotta (2005b) also recommend validation 

of AcidityNet be conducted by direct measurements obtained 

through hot acidity titrations. These titrations were performed 

in accordance with Kirby and Cravotta (2005b), and equivalent on selected groundwater samples reflecting the range 

in AcidityNet as determined above. In brief, titrations were 

performed on groundwater samples after initially reducing 

their pH to 4 within 24 hours to preserve samples (Kirby and 

Cravotta, 2005b). Preserved samples were digested with 

30 percent hydrogen peroxide with heating to drive off carbon 

dioxide, and then titrated to a pH of approximately 8.2. The 

acidity of the sample in milligrams per liter as CaCO3 was 

determined in accordance with procedures described by Kirby 

and Cravotta (2005b), which hereafter, is referred to as Acidityhot in this appendix.

On the basis of theoretical considerations and empirical 

studies, Kirby and Cravotta (2005b) have shown that AcidityNet is equal to Acidtyhot. Therefore, the two measurements 

should be linearly and positively correlated. Comparisons 

of AcidityNet with Acidityhot—a direct measure of Acidity Calculated - AlkalinityStdMthd, were conducted using standard 

methods (Kirby and Cravotta, 2005b). The two measures were 

highly, positively, and linearly related (fig. B2, correlation 

coefficient (R-squared) equal to 0.997, and power of test, p, 

less than 0.00001). Acidityhot values were biased low at high 

acidity concentrations. The values for CE Dd 127 and 160 

are considered outliers, with potential low bias in Acidityhot. 

The cause of this bias was investigated but remains unknown 

(C. Cravotta, III, USGS, written commun., 2010). It possibly could be related to the slow hydrolization of manganese, 

which has been found to occur in acid-mine drainage waters 

with elevated concentrations of manganese and dissolved 

organic carbon (Tewalt, 2004). Most groundwater samples in 

the DMCA and vicinity with elevated dissolved solids also 

contain elevated concentrations of dissolved recoverable 

organic carbon (see Dissolved Recoverable Organic Carbon, 

main report). Thus, AcidityNet values as determined by equations (B2) and (B3) likely are accurate with Acidityhot likely 

being underestimated.

1:1 Trendine

0 

200 

400 

600 

800 

-200 

-400 

1,200 

1,000 

1,400 

Hot and net acidity with trendline

EXPLANATION

1:1 Trendline

Outliers

-500 0 500 1,000 1,500 

CE Dd 160

CE Dd 127

Aciditynet= 1.1246 Acidityhot -2.2537

R-squared = 0.997, p < 0.00001

Aciditynet, in milligrams per liter as CaCO3

Acidityhot, in milligrams per liter as CaCO3

Figure B2. Relation between AcidityNet and Acidityhot (both in 

milligrams per liter (mg/L) as CaCO3

) for selected groundwater 

samples collected in the Pearce Creek Dredge Material 

Containment Area and vicinity, 2010.
Appendix B 169

Acknowledgments

The authors would like to thank the following chemists 

for their collaborative efforts to develop modified standard 

methods that were used to analyze the water samples for 

arsenic and beryllium, their thorough summaries of method 

modifications, and their reviews of the resultant data: Donna 

Damrau, Supervisory Chemist, and Mark Hill, Research 

Chemist, USGS NWQL, Denver, Colorado, Paul Lamothe, 

Research Chemist, USGS Geologic Discipline Mineral 

Resources Program Laboratory, Denver, Colorado; and 

Anthony Bednar, Research Chemist, USACE Environmental 

Laboratory, Engineer Research and Development Center, 

Vicksburg, Mississippi.

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Kirby, C.S., and Cravotta, C.A., III, 2005b. Net alkalinity and net acidity 2: Practical considerations: Applied 

Geochemistry, v. 20, no. 10, p. 1,941–1,964. (Also available at http://www.sciencedirect.com/science/article/pii/

S0883292705001381.)

Lee, E.A., Kish, J.L., Zimmerman, L.R., and Thurman, E.M., 

2001, Methods of analysis by the U.S. Geological Survey 

Organic Geochemistry Research Group—Update and additions to the determination of chloroacetanilide herbicide 

degradation compounds in water using high-performance 

liquid chromatography/mass spectrometry: U.S. Geological 

Survey Open-File Report 01–10, 17 p.

Lee, E.A., Strahan, A.P., and Thurman, E.M., 2002, Methods 

of analysis by the U.S. Geological Survey Organic Geochemistry Research Group—Determination of triazine and 

phenylurea herbicides and their degradation products in 

water using solid-phase extraction and liquid chromatography/mass spectrometry: U.S. Geological Survey Open-File 

Report 02–436, 26 p. (Also available at http://ks.water.usgs.

gov/pubs/reports/of.02-436.pdf.)

Lewis, M.E., 2006, Dissolved-oxygen concentration (ver. 2.1): 

U.S. Geological Survey Techniques of Water-Resources 

Investigations, book 9, chap. A6, sec. 6.2, June, accessed 

September 28, 2010, at http://pubs.water.usgs.gov/twri9A6/.

Nordstrom, D.K., and Wilde, F.D., 2005, Reduction-oxidation 

potential (ver. 1.2): U.S. Geological Survey Techniques of 

Water-Resources Investigations, book 9, chap. A6, sec. 6.5, 

September, accessed September 28, 2010, at http://pubs.

water.usgs.gov/twri9A6/.

Patton, C.J., and Kryskalla, J.R., 2011, Colorimetric determination of nitrate plus nitrite in water by enzymatic reduction, automated discrete analyzer methods: U.S. Geological 

Survey Techniques and Methods, book 5, chap. B8, 34 p.

Patton, C.J., and Truitt, E.P., 1992, Methods of analysis by 

the U.S. Geological Survey National Water Quality Laboratory–Determination of total phosphorus by a Kjeldahl 

digestion method and an automated colorimetric finish that 

includes dialysis: U.S. Geological Survey Open-File Report 

92–146, 39 p.

Patton, C.J., and Truitt, E.P., 2000, Methods of analysis by the 

U.S. Geological Survey National Water Quality Laboratory–Determination of ammonium plus organic nitrogen by 

a Kjeldahl digestion method and an automated photometric 

finish that includes digest cleanup by gas diffusion: U.S. 

Geological Survey Open-File Report 00–170, 31 p.

Radtke, D.B., Davis, J.V., and Wilde, F.D., 2005, Specific 

electrical conductance (ver. 1.2): U.S. Geological Survey 

Techniques of Water-Resources Investigations, book 9, 

chap. A6, sec. 6.3, August, accessed September 28, 2010, at 

http://pubs.water.usgs.gov/twri9A6/.

Reisman, D.J., Sundaram, V., Al-Abed, S.R., and Allen, D., 

2007, Statistical validation of sulfate quantification methods 

used for analysis of acid mine drainage: Talanta, v. 71, 

p. 303–311.

Ritz, G.F., and Collins, J.A., 2008, pH (ver. 2.0): U.S. Geological Survey Techniques of Water-Resources Investigations, 

book 9, chap. A6, sec. 6.4, October, accessed September 28, 

2010, at http://pubs.water.usgs.gov/twri9A6/.

Tewalt, S.J., 2004, The use of ozone to remediate dissolved 

manganese from coal mine drainage, abs., in Northeastern Section (39th Annual) and Southeastern Section (53rd 

Annual) Joint Meeting March 25–27, 2004, McLean, Va., 

Geological Society of America, Abstracts, v. 36. no. 2, 

p. 82. 

U.S. Army Corps of Engineers, 1996, Pearce Creek Disposal 

Area Groundwater Investigation, Pearce Creek, Maryland, 

Phase II Report: U.S. Army Corp of Engineers, Philadelphia 

District, Philadelphia, Penn., 240 p. including 5 apps.

U.S. Environmental Protection Agency, 2005, B.3.11 EPA 

Methods 375.3 and 375.4 (Sulfate), p. B9, in U.S. Environmental Protection Agency Aquiculture Guide, Appendix B: 

508 Analytical methods and nominal quantification limits, 

15 p., accessed May 5, 2010, at http://water.epa.gov/scitech/

wastetech/guide/aquaculture/upload/2005_09_01_guide_

aquaculture_add_appendixb_508.pdf.

Weston, R.F., Inc., 1998, Review of groundwater investigations for the Pearce Creek Dredge Disposal Containment 

Area, Final report to the U.S. Army Corps of EngineersPhiladelphia District, Weston, R.F., Inc. Westchester, Penn., 

73 p. with 2 additional apps.
Appendix B 171

Wilde, F.D., 2006, Temperature (ver. 2.0): U.S. Geological 

Survey Techniques of Water-Resources Investigations, book 

9, chap. A6, sec. 6.1, March, accessed September 28, 2010, 

at http://pubs.water.usgs.gov/twri9A6/.

Zaugg, S.D., Smith, S.G., and Schroeder, M.P., 2006, Methods 

of analysis by the U.S. Geological Survey National Water 

Quality Laboratory–Determination of wastewater com-

pounds in whole water by continuous liquid-liquid extrac-

tion and capillary-column gas chromatography/mass spec-

trometry: U.S. Geological Survey Techniques and Methods, 

book 5, chap. B4, 30 p.
172 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

Appendix C: Descriptive Logs of Boreholes in the Pearce 

Creek Dredge Material Containment Area and Vicinity, 

Cecil County, Maryland, 2010–11

List of boreholes

CE Dd 136 CE Dd 150

CE Dd 137 CE Dd 151

CE Dd 138 CE Dd 152

CE Dd 139 CE Dd 153

CE Dd 140 CE Dd 154

CE Dd 141 CE Dd 155

CE Dd 142 CE Dd 156

CE Dd 143 CE Dd 157

CE Dd 144 CE Dd 158

CE Dd 145 CE Dd 159

CE Dd 146 CE Dd 160

CE Dd 147 CE Dd 191

CE Dd 148 CE Dd 192

CE Dd 149 CE Dd 193

Conversion factors

Inch/Pound to SI

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD 88).

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Altitude, as used in this report, refers to distance above the vertical datum.

Apparent conductivity (AP-COND) is given in millimhos per meter, which is equivalent to 

milliSiemens per meter.

Gamma logs are given in units of American Petroleum Institute gamma ray units (API-GR).
Appendix C 173

Abbreviations and acronyms

AP-COND apparent conductivity (from borehole geophysical log)

API-GR American Petroleum Institute gamma ray units

DMCA dredge material containment area

GAMMA natural gamma radiation (from borehole geophysical log)

NAVD 88 North American Vertical Datum of 1988

NGVD29 National Geodetic Vertical Datum of 1929

UPA, deep upper Patapsco aquifer, deep water-bearing zone

UPA, shallow upper Patapsco aquifer, shallow water-bearing zone

USACE U.S. Army Corps of Engineers

USGS U.S. Geological Survey

WSC Water Science Center of the U.S. Geological Survey

WVS West View Shores residential community
174 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

EXPLANATION

Lithology Lithology

Silty clay

Silt

Clayey silt

Sand

Silty sand

Clay

Silty sandy clay

Sandy clay

Clayey sand

Sandt gravel

Sandy silt

EXPLANATION

Lithology

Silty clay

Silt

Clayey silt

Sand

Silty sand

Clay

Silty sandy clay

Sandy clay

Clayey sand

Sandy gravel

Sandy silt

Lithology

Magothy

UPA, shallow

UPA, deep

Matawan confining unit

Confining unit

Cement with grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

EXPLANATION

Well construction
Appendix C 175

60

55

50

45

40

35

30

25

20

15

10

5

0

No observations. Aquifer designation based on adjacent wells.

Silty Clay; Dark Gray, yellow and reddish brown mottling, organics detritus present, soft.

Sandy Silt; Tan, soft.

Silty Clay; Dark Gray, tan and light gray layers present.

Silty Clay; Dark Gray, very hard, organic detritus present.

Sand; Light Gray to White, medium to coarse-grained, organic detritus and gravel present.

Sand; Light Gray and White, angular, gravel present.

Silty Clay; Dark Gray, very hard, lignite present.

Silty Sand; Gray, medium-grained.

Matawan Confining Unit

Magothy

Lithologic Description Aquifer Well

392556075590002 CE Dd 136

Boart Longyear

3/31/2010

3/31/2010

J. Sorenson

59

55

0.02

Sonic

39°25'55.7"N

75°59'00.2"W

38.45

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Scale

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 1 1P
176 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

70

65

60

55

50

45

40

35

30

25

20

15

10

5

0

No observations. Aquifer designation based on adjacent wells.

Clayey Silt; Gray, gravel present.

Sand; Light Tan to Black, medium-grained.

Sand; Gray, coarse-grained, poorly-sorted, silt lenses present.

Sand; Tan to Gray, fine to coarse-grained, poorly-sorted, gravel present.

Sand; Light Gray to Tan, very fine-grained, well-sorted.

Matawan Confining Unit

Magothy

Lithologic Description Aquifer Well

392527075590802 CE Dd 137

Boart Longyear

4/6/2010

4/7/2010

A. Massey

70

63

0.015

Sonic

39°25'27.2"N

75°59'08.1"W

36.82

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Scale

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 1 1P
Appendix C 177

150

140

130

120

110

100

90

80

70

60

50

40

30

20

10

0 Silt; Tan to Brown, mottling and sand present.

Clay; Gray, fine-grained, hard.

Clay; Dark Gray, lignite and organic detritus present, soft.

Clay; Dark Gray, lignite and organic detritus present, soft.

Clay; Dark Gray to Black, organic detritus present.

Silty Sand; Tan, fine to medium-grained.

Sand; Light Tan, medium to coarse-grained, trace angular gravel present.

Silty Sand; Tan to Brown, fine-grained, mottling present.

Sand; Yellow to Tan, gravel and organics present.

Sand; Yellow to Tan, medium to coarse-grained, gravel present.

Sandy Silt;

Sand; White to Light Gray, fine-grained, yellow mottling present,

Sand; Light Tan, fine to medium-grained, well-sorted, reddish brown mottling

present.

Clay; Reddish Brown, light gray mottling, hard.

Clay; Reddish Brown, light gray mottling present, hard.

Silty Clay; Gray, mottling present.

Sand; Tan, medium to coarse-grained.

Clay; Gray, hard.

Clay; Red to Reddish Brown, silt, sand, and gravel present.

Sand; Light Gray, mottling present.

Sand; Tan, medium to coarse-grained, silt lenses present.

Clay; Red, hard.

Silty Clay; Reddish-Brown, light gray mottling.

Silty Sand; Gray.

Silty Sand; Light Gray, reddish brown mottling present.

Silty Sand; Gray, clay lenses present.

Silty Sand; Gray.

Sand; Light Gray.

Matawan Confining Unit

Magothy Confining Unit UPA, shallow

GAMMA

0

50

100150

AP-COND200 100

0

Lithologic Description Aquifer Well

392527075590801 CE Dd 138

Boart Longyear

4/1/2010

4/1/2010

J. Sorenson

148

120

0.02

Sonic

39°25'27.2"N

75°59'08.1"W

36.85

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 1 1P
178 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

60

55

50

45

40

35

30

25

20

15

10

5

0

No observations. Aquifer designation based on adjacent wells.

Sand; Dark to Light Gray, fine-grained.

Sand; White and Black.

Sand; Tan, interbedded thin clayey zones.

Clayey Sand; Light Tan, coarse-grained, angular gravel present.

Sand; Light Tan, fine to coarse-grained, poorly-sorted, well-rounded gravel present.

Silty Sand; Gray, very fine-grained.

Sand; Light Tan, fine to coarse-grained, poorly-sorted, well-rounded gravel present.

Sand; White, coarse-grained.

Clay; White and Gray.

Matawan Confining Unit

Magothy

Lithologic Description Aquifer Well

392536075592003 CE Dd 139

Boart Longyear

3/30/2010

3/30/2010

A. Massey

59

58

0.02

Sonic

39°25'35.7"N

75°59'19.8"W

34.86

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 1 1P
Appendix C 179

25

20

15

10

5

0

No observations. Aquifer designation based on adjacent wells.

Sand; Red and Brown, poorly-sorted, gravel and cobbles present.

Sand; Brown, fine to medium-grained, gravel present.

Sand; Brown, fine-grained.

Sand; Brown, medium to coarse-grained, gravel present.

Sand; Brown, medium to coarse-grained, gravel and organics present.

Sand; Gray, fine-grained.

Silt; Gray, very fine-grained sand lenses present.

Clayey Silt; Dark Gray.

Sand; Gray, fine-grained.

Silt; Dark Gray, angular coarse-grained sand and gravel present.

Magothy Confining Unit

Lithologic Description Aquifer Well

392548075593801 CE Dd 140

Boart Longyear

4/10/2010

4/10/2010

A. Massey

28

16

0.02

Sonic

39°25'48.4"N

75°59'39.1"W

11.47

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 1 1P
180 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

100

80

60

40

20

0 No Observations.

Sand; Red-Brown, poorly-sorted, contains gravel.

Sand; Red and Brown, fine to medium-grained, poorly-sorted, angular, contains

gravel. Transition to well-sorted at 14'.

Sand; Medium to coarse-grained, poorly-sorted, contains gravel.

Sand; Medium to coarse-grained, poorly-sorted, contains gravel and organics.

Silty Sand; Red with red, oxidizing residue, trace gravel present.

Silty Sand; Gray, fine-grained, well-sorted.

Silty Clay; Gray to Dark Gray, micaceous, contains rounded gravel, contains banded

zones of silt and clay.

Sand; Gray, medium to coarse-grained.

Silty Clay; Dark Brown and Gray, contains lignite and fine-organics.

Clay; Dark Brown, contains fine-organics and rounded gravel.

Clay; Dark Gray to Black, contains fine organics and gravel.

Clay; Dark Gray to Black, contains trace amounts of fine organics and gravel.

Clay; Dark Gray to Black, contains black and white organics and trace amounts of

gravel.

Clay; Dark Gray and Brown, contains brown and white organics and trace amounts

of gravel.

Sand; Light Tan grading to Dark Gray, fine-grained, well-sorted.

Silty Sand; Dark Gray, medium-grained, poorly-sorted, contains gravel.

Clay; Gray, contains lignite and rounded-gravel.

Clay; Gray, contains sand and rounded-gravel.

Silty Sand; Gray, intermittent zones of Gray Clay and Gray Silty Sand.

Sand; Tan and red transition zone containing Red Clay irregular inclusions, medium

to coarse-grained, rounded gravel present.

Sand; Gray, medium-grained, contains gravel.

Sand; Gray, fine to medium-grained, contains gravel.

Sand; Gray to Brown, fine to medium-grained, contains gravel.

Sand; Brown to Red, fine to medium-grained, contains gravel.

Sand; Red to Light Orange, fine to medium-grained, well-sorted.

Sand; Orange grading to Dark Orange at bottom, fine to medium-grained,

well-sorted.

Sand; Brown and Red, fine to medium-grained, well-sorted.

Clay; Gray, red mottling present.

Sand; Orange, fine to medium-grained, well-sorted.

Sand; Orange, medium-grained, well-sorted, well-rounded.

Magothy Confining Unit UPA, shallow

GAMMA

0

50

100

AP-COND 100

0

50

Lithologic Description Aquifer Well

392548075593802 CE Dd 141

Boart Longyear

4/8/2010

4/9/2010

A. Massey

228

222

0.02

Sonic

39°25'48.4"N

75°59'38.1"W

11.21

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 3 1P
Appendix C 181

200

180

160

140

120

100 Sand; Orange, medium-grained, well-sorted, well-rounded. Sand; Brown, clay and silt lenses present, fine to coarse-grained, poorly-sorted.

Silty Clay; Gray, firm.

Sand; Gray, very fine-grained.

Silty Clay; Gray and Dark Gray.

Clay; Dark Gray, contains lignite.

Clay; Dark Gray to Brown, contains lignite.

Silty Clay; Gray and Brown, hard, contains lignite.

Silt; Gray to Dark Gray and Brown, very hard.

Clayey Silt; Dark Gray, dense, contains lignite.

Silt; Light Gray, hard, dense, contains trace amounts of lignite and clays.

Silty Sand; Gray to Dark Gray, very fine-grained.

Silt; Light Gray, hard, dense, contains trace amounts of lignite and clays.

Sand; Dark Gray, intermittent silt and clay layers present, iron nodule present.

Clay; Dark Gray, bands of very fine-grained Sand present.

Clay; Dark Gray to Black, lenses of very fine-grained sand and silt.

Sand; Dark Gray, intermittent silt and clay layers present.

Sand; Gray, very fine-grained, well-sorted.

Silty Clay; Light Gray, dark gray, red, and brown mottling present.

Clay; Light Gray, dark gray, red, and brown mottling present.

Clay; Light Gray, dark gray, red, and brown mottling present, medium-grained sand

present.

Clay; Light Gray, dark gray, red, and brown mottling present, lignite present.

Silty Clay; Gray, Brown, and Yellow, hard, red mottling present.

Silty Clay; Brown and Gray, reddish brown mottling present.

Silty Clay; Brown and Gray, reddish brown mottling present, medium-grained sand

present.

Clayey Silt; Brown and Gray, reddish brown mottling present, medium-grained sand

present.

Clay; Dark Brown.

Clay; Dark Brown, contains gray silt mottling.

Silty Clay; Brown and Gray, reddish brown mottling present.

Sand; Gray, very fine-grained.

Clay; Dark Brown.

Confining Unit

GAMMA

0

50

100

AP-COND 100

0

50

Lithologic Description Aquifer Well

392548075593802 CE Dd 141

Boart Longyear

4/8/2010

4/9/2010

A. Massey

228

222

0.02

Sonic

39°25'48.4"N

75°59'38.1"W

11.21

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 3 2P
182 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

240

220

200

Clay; Dark Brown, lenses of gray silty clay.

Silty Sand; Gray, very fine-grained, contains lignite.

Clayey Silt; Dark Gray, hard.

Clay; Dark Brown.

Silty Sand; Gray to Light Gray and Brown, very fine-grained, contains lignite.

Sand; Gray, very fine-grained, well-sorted.

Silty Sand; Gray, very fine-grained, contains lignite and clay inclusions.

Sand; Tan to Light Brown, medium-grained, well-sorted, contains sand concretions.

Sand; Orange Brown and Gray, contains rounded gravel, lignite, and sand

concretions.

Silty Clay; Gray and Brown, contains poorly-sorted sand, rounded gravel, sand

concretions, and lignite.

Clay; Red and Gray, hard, light purple mottling present.

UPA, deep

GAMMA

0

50

100

AP-COND 100

0

50

Lithologic Description Aquifer Well

392548075593802 CE Dd 141

Boart Longyear

4/8/2010

4/9/2010

A. Massey

228

222

0.02

Sonic

39°25'48.4"N

75°59'38.1"W

11.21

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 3 3P
Appendix C 183

100

95

90

85

80

75

70

65

60

55

50

45

40

35

30

25

20

15

10

5

0

No observations. Aquifer designation based on adjacent wells.

Sand; Brown to Gray, medium to coarse-grained.

Silt; Gray, poorly-sorted, trace gravel present.

Sand; Gray, poorly-sorted, trace gravel present. Intermittent lenses of silt, clay, and

gravel.

Silty Clay; Gray, mottling present.

Clay; Light Tan.

Sandy Silt; Reddish Brown, very fine-grained.

Silty Sand; Light Tan, very fine-grained. Intermittent Silty Clay lenses.

Silty Sand; Gray and orange, fine to very fine-grained.

Sand; Gray and Orange, medium-grained.

Sand; Tan. Intermittent Silty Clay lenses.

Sand; Brown, medium-grained.

Sand; Orange to Brown, fine-grained.

Sand; Reddish Brown to Dark Reddish Brown, fine-grained. Irregularly shaped gray

clay inclusions present.

Magothy Confining Unit UPA, shallow

GAMMA

-1040

90140

AP-COND -2

5

30

55

0

Lithologic Description Aquifer Well

392540075594501 CE Dd 142

Boart Longyear

4/11/2010

4/11/2010

A. Massey

98

89

0.02

Sonic

39°25'40.4"N

75°59'45.0'W

23.55

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 1 1P
184 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

45

40

35

30

25

20

15

10

5

0

No observations. Aquifer designation based on adjacent wells.

Silty Sand; Orange, fine to coarse-grained, poorly-sorted, with gravel.

Sand; Orange, very fine-grained to fine-grained.

Silty Sand; Orange to Reddish Orange, very fine to medium-grained, containing intermittent lenses of

gray clay.

Sand; Light Orange, fine-grained, very well-sorted.

Silt; Gray, reddish orange mottling, contains clay.

Sand; Tan, fine to medium-grained, clay nodules present.

Magothy Confining Unit

Lithologic Description Aquifer Well

392540075594502 CE Dd 143

Boart Longyear

4/12/2010

4/12/2010

A. Massey

48

44

0.02

Sonic

39°25'40.4"N

75°59'45.0'W

23.72

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 1 1P
Appendix C 185

30

25

20

15

10

5

0 Fill Material; Clay with sand lenses, organic detritus present.

Clay; Gray, Yellow, and Orange-Brown, mottling present.

Clayey Sand; Fine to coarse-grained, poorly-sorted, angular, red clay clasts present.

Sand; Medium Gray, fine to coarse-grained, poorly-sorted, trace gravel present. Clayey lenses up to

1-inch present.

Sand; Gray with multi-colored fines, fine to coarse-grained, poorly-sorted, sub-angular. Quartz cobbles

present at 7 feet.

Clay; Medium to Dark Gray, soft. 6-inch zone of organic detritus present.

Clayey Sand; Gray-Brown, fine to medium-grained, poorly-sorted, angular.

Clayey Sand; Gray-Brown, fine to fine-grained, angular.

Sand; Gray with multi-colored fines, fine to medium-grained, poorly-sorted.

Silty Sand; Medium Blue-Gray, very fine-grained, gravel present.

Silty Sand; Medium Gray, very fine-grained, well-sorted, wet.

Matawan Confining Unit

Magothy Confining Unit

Lithologic Description Aquifer Well

392547075591702 CE Dd 144

Boart Longyear

3/29/2010

3/29/2010

C. Dieter

34

27

0.02

Sonic

39°25'47.1"N

75°59'17.2"W

28.12

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 1 1P
186 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

35

30

25

20

15

10

5

0

No observations. Aquifer designation based on adjacent wells.

Sand; Tan, medium to coarse-grained, poorly-sorted, rounded gravel present.

Sand; Gray, fine-grained, clay inclusions present.

Sand; Tan, medium to coarse-grained, poorly-sorted, rounded gravel present.

Sand; Black, fine to medium-grained, contains organics, detritus, and gravel.

Sand; Light Gray, medium to coarse-grained, poorly-sorted, fine gravel present.

Sand; Gray, fine-grained, well-sorted.

Sand; Medium Gray, medium to coarse-grained, poorly-sorted, fine gravel present.

Sand; Gray, medium-grained, well-sorted.

Sand; Medium Gray, medium to coarse-grained, poorly-sorted, gravel present.

Clay; Red, gray mottling present.

Magothy

Confining Unit

Lithologic Description Aquifer Well

392603075585602 CE Dd 145

Boart Longyear

3/28/2010

3/28/2010

A. Massey

30

30

0.02

Sonic

39°26'03.4"N

75°58'56.3"W

21.00

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 1 1P
Appendix C 187

80

70

60

50

40

30

20

10

0

No observations. Aquifer designation based on adjacent wells.

Magothy Confining Unit

Lithologic Description Aquifer Well

392603075585604 CE Dd 146

Boart Longyear

3/28/2010

3/28/2010

A. Massey

129.5

128.5

0.02

Sonic

39°26'03.5"N

75°58'56.4"W

21.00

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 2 1P
188 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

140

130

120

110

100

90

80

Sand; Tan to Orange Tan, very fine-grained.

Sand; Tan ,very fine-grained.

Sand; Gray, very fine-grained, clay nodules present.

Sand; Gray, fine-grained, sand cementations present.

Sand; Tan, fine to very fine-grained. 6-inch zone of Sand cementations and coarse-grain sizes present

at 121 and 123 feet.

Sand; Gray, fine to medium-grained, angular.

Sand; Tan, fine to medium-grained.

Sandy Clay; Grayish Red.

Sand; Light Tan, fine to medium-grained, angular.

UPA, shallow

Lithologic Description Aquifer Well

392603075585604 CE Dd 146

Boart Longyear

3/28/2010

3/28/2010

A. Massey

129.5

128.5

0.02

Sonic

39°26'03.5"N

75°58'56.4"W

21.00

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 2 2P
Appendix C 189

100

90

80

70

60

50

40

30

20

10

0 Silty Sand; Light Brown, trace gravel present.

Silty Clay; Brown, gravel present.

Sand; Brown, fine to medium-grained, well-sorted with trace poorly-sorted gravel.

Sand; Brown, poorly-sorted, gravel present.

Sand; Orange-Brown, fine to very fine-grained, poorly-sorted.

Sand; Brown, fine to medium-grained, poorly-sorted, organic matter present.

Sand; Light Tan, fine to coarse-grained, angular, organic matter present,

cobble-sized clay and sand concretions present.

Sand; Light Tan, fine to coarse-grained, angular, organic matter present,

cobble-sized clay concretions present.

Sand; Dark Gray, fine to medium-grained, organic matter and black clay nodules

present

Sand; Dark Gray, poorly-sorted, gravel present.

Sand; Gray, poorly-sorted.

Sand; Gray, fine to very fine-grained.

Sand; Gray, fine to medium-grained, poorly-sorted. Gravel present at 35'.

Clay; Light Blue-Gray, mottling present.

Sand; Orange-Brown, medium to coarse-grained, poorly-sorted, gray nodules, clay,

and gravel present.

Clay; Very Light Gray, red mottling present, fine silts and sand present.

Sand; Very Light Gray to White, transition zone towards sand, very fine-grained,

well sorted.

Sand; Brown, dark red cobble-sized sand concretions present.

Clay; Gray, high plasticity, mottling present.

Clay; Dark Red, high plasticity, mottling present.

Clay; Gray, dark red mottling present.

Clay; Gray, gray and brown mottling present.

Clay; Gray and Dark Gray, mottling and organics/lignite present

Sandy Clay; Very fine-grained, black nodules present.

Sand; Light Gray, fine-grained.

Sand; Gray and Tan to Brown, very fine-grained, well-sorted.

Sandy Clay; Dark Gray, very fine-grained, lignite present.

Clay; Dark Gray, stiff to very stiff, silt present, sand concretions present, 3-inch zone

of gray sand at 93 feet. Transition to sandy clay to 99 feet.

Sand; Dark Gray to Dark Red, very fine-grained, well-sorted, cobble-sized gravel

present.

Magothy Confining Unit

GAMMA

-1040

90140

AP-COND -8123252

Lithologic Description Aquifer Well

392603075585603 CE Dd 147

Boart Longyear

3/27/2010

3/27/2010

A. Massey

198

198

0.02

Sonic

39°26'03.5"N

75°58'56.4"W

21.10

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 2 1P
190 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

200

190

180

170

160

150

140

130

120

110

100

Sand; Light Tan, fine-grained, well-sorted, angular.

Clay; Gray, silt and sand present, very fine-grained.

Sand; Light Brown.

Silty Sand; Light Gray, very fine-grained.

Silty Sand; Gray transition zone with sand, silts, and clay. Dark Red mottling present.

Sand; Gray, very fine-grained, well-sorted, clay nodules present. One-foot

coarser-grained sand at 117 feet.

Sand; Brown and Light Tan, well-sorted. Clay nodules present at 122 feet.

Sand; Tan, well-sorted, angular sand concretions present.

Sand; Light Brown, fine-grained, trace gravel present.

Sand; Gray, coarse-grained, poorly-sorted.

Sand; Gray to Tan, medium-grained, poorly-sorted, angular to subangular.

Clay; Gray to Dark Red, brown clay nodules present.

Clay; Gray, very firm, mottling present.

Silty Clay; Gray, dark red mottling present.

Silty Clay; Dark Gray and Gray, very hard.

Silty Clay; Gray, dark red mottling present, very stiff.

Silty Clay; Gray, dark gray mottling present.

Sandy Clay; Gray.

Silty Clay; Gray.

Silty Sand; Gray, very fine-grained.

Silty Clay; Light Brown.

Silty Sand; Gray, very fine-grained.

Sand; Gray, very fine-grained.

Silty Sand; Gray, very fine-grained.

Silty Sand; Gray, very fine-grained, well-sorted.

Silty Clay; Dark Gray.

Sand; Gray, very fine-grained. Clay inclusions present at 183 feet and silt content

increases at 197 feet.

UPA, shallow Confining Unit

UPA, deep

GAMMA

-1040

90140

AP-COND -8123252

Lithologic Description Aquifer Well

392603075585603 CE Dd 147

Boart Longyear

3/27/2010

3/27/2010

A. Massey

198

198

0.02

Sonic

39°26'03.5"N

75°58'56.4"W

21.10

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 2 2P
Appendix C 191

45

40

35

30

25

20

15

10

5

0

No observations. Aquifer designation based on adjacent wells.

Clay; Dark Gray, lignite present, soft.

Silty Clay; Tan, gray and dark gray mottling present, very hard.

Silty Sand; Tan, medium to coarse-grained. Black, yellow, and light gray mottling present.

Sandy Silt; Tan, yellow and light gray mottling present, hard, becomes soft and saturated at 30 feet. 4

inch clayey sand lens present at 31 feet.

Silty Sand; Tan, fine-grained.

Sand; Light Tan, fine to medium-grained, black and yellow mottling present.

Sand; Light Tan to White, fine to medium-grained.

Silty Clay; Tan, very hard, lignite present from 41 to 42 feet.

Sandy Silt; Brown, yellow and light gray mottling present.

Sand; Tan grading to White, fine to coarse-grained, gray, yellow, and black mottling present.

Matawan Confining Unit

Magothy

Lithologic Description Aquifer Well

392520075590401 CE Dd 148

Boart Longyear

3/31/2010

3/31/2010

J. Sorenson

48

40

0.02

Sonic

39°25'20.3"N

75°59'04.3"W

37.06

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 1 1P
192 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

80

70

60

50

40

30

20

10

0 Sandy Silt; Gray Brown, rounded to angular, bands of poorly-sorted sands and

gravel.

Silty Sand; Yellow Brown, poorly-sorted, sand and gravel present.

Clay; Dark Gray, reddish brown mottling present, black organics present. Bands of

yellow medium-grained sands present from 3.5 to 4.5 feet.

Clay; Dark Gray, dark organics present in bands throughout observed interval.

Clay; Dark Gray, sand and gravels present at 18 feet.

Silty Sand; Yellow to Gray. Angular gravel and fine-grained sand present.

Silty Clay; Brownish Gray, yellow mottling present, very hard.

Sandy Silt; Brownish Gray, red and yellow mottling present.

Sandy Silt; Bluish Gray to Tan, fine to medium-grained, well-graded.

Silty Sand; Tan to White, medium to coarse-grained, gray and yellow mottling

present.

Sand; Light Tan to White, medium and coarse-grained, yellow mottling present,

organics present. 6-inch Silty Sand lens present at 44 feet.

Sandy Silt; Yellow.

Silty Clay; Brownish Tan, vertical linear organic deposits present.

Sand; Light Tan, medium to coarse-grained.

silty Clay; Dark Tan, yellow and light tan mottling present, organics present, soft.

Sand; Light Tan to White, coarse-grained, brown and black mottling present.

Sandy Silt; Tan, yellow and light gray mottling present.

Sand; Light Tan to Tan, coarse-grained. 3-inch Dark Tan Clay lens present at 60

feet.

Silty Sand; Yellow, Tan, and White banded coloring, fine to coarse-grained. Angular

gravel present.

Sand; Yellow, coarse-grained, angular to sub-rounded gravel present

Sand; White, coarse-grained, well-sorted, clayey nodules present.

Sand; Tan to Yellow, gravel present, angular to sub-rounded.

Sand; White, coarse-grained, yellow and black mottling present.

Sand; White to Yellow, coarse-grained, angular gravel present.

Confining Unit

Magothy

GAMMA

050100150

AP-COND150 100

050

Lithologic Description Aquifer Well

392520075590402 CE Dd 149

Boart Longyear

3/29/2010

3/30/2010

J. Sorenson

118

118

0.02

Sonic

39°25'20.3"N

75°59'04.4"W

36.98

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 2 1P
Appendix C 193

120

110

100

90

80 Sand; White to Yellow, coarse-grained, angular gravel present.

Silty Clay; Tan, very hard, friable.

Silty Clay; Dark Gray, lignite present, hard, friable.

Silty Clay; Tan, very hard, friable.

Silty Sand; Gray, well-graded from coarse-grained sand to fine-grained silty sand,

very hard.

Sand; Light Gray, fine to medium-grained, well-sorted.

Sand; Light Gray, fine to medium-grained, well-sorted. 6-inch silty sand layer at 99

feet.

Sand; Light Gray, coarse-grained, well-sorted.

Confining Unit UPA, shallow

GAMMA

050100150

AP-COND150 100

050

Lithologic Description Aquifer Well

392520075590402 CE Dd 149

Boart Longyear

3/29/2010

3/30/2010

J. Sorenson

118

118

0.02

Sonic

39°25'20.3"N

75°59'04.4"W

36.98

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 2 2P
194 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

100

90

80

70

60

50

40

30

20

10

0 Clay; Tan, hard, organic detritus present.

Clay; Dark Blue, high organic content, detritus present.

Sandy Clay; Light Blue, organics and red brown oxidization present in sands.

Clay; Light Blue.

Sandy Clay; Light Blue, organics and red brown oxidization present in sands.

Clay; Medium Brown, trace sand and organics present, soft.

Silty Clay; Medium to Reddish Brown.

Sandy Silt; Light Blue, contains fine-grained, oxidized sand lenses.

Silty Sand; Gray to Brownish Gray, very fine-grained sand, oxidized striations in

sand, grading coarser to 24 feet.

Silty Sand; Gray to Brown, fine to medium-grained sand.

Silty Clay; Light Blue.

No Recovery. Saturated.

Sandy Silt; Light Bluish Gray, brown oxidation present.

Silty Sand; Dark Gray.

Silty Sand; Light Gray to Gray.

Sandy Silt; Dark Gray, high organic content increasing to 47 feet.

Sand; Light Gray, medium to coarse-grained, intermittent white sand lenses present.

Sandy Gravel; Light Yellow, poorly-sorted, grain size ranging from sand to cobbles.

Sand; White, medium to fine-grained, purple and yellow mottling present, sandy silt

lenses present.

Silty Clay; Red to Purple Red, very hard.

Silty Clay; Light Gray, yellow mottling present.

Silty Clay; Red to Gray.

Clay; Light Gray, reddish brown and yellow mottling present.

Silty Clay; Light Gray, reddish brown and yellow mottling present.

Silty Clay; Light Gray, reddish brown and yellow mottling increased from above

observation.

Silty Clay; Brownish Red.

Silty Clay; Reddish Brown, white silt lenses present, black and yellow mottling

present, very hard.

Silty Clay; Brownish Red, silt lenses present, black and yellow mottling present, very

hard.

Silty Clay; Light Purple, red and yellow mottling present, friable, very hard.

Clay; Red Brown, lignite and white and yellow mottling present and increasing to 98

feet, very hard.

Matawan Confining Unit

Magothy

Confining Unit

GAMMA

050100

150

200

AP-COND -14090

0

Lithologic Description Aquifer Well

392546075581902 CE Dd 150

Boart Longyear

3/25/2010

3/27/2010

J. Sorenson

248

145

0.015

Sonic

39°25'46.6"N

75°58'18.7"W

16.45

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 3 1P
Appendix C 195

200

190

180

170

160

150

140

130

120

110

100

Silty Clay; Red color increasing to 108 feet, light gray mottling present, very hard,

brittle.

Clay; Red, light gray mottling present, very hard, brittle.

Silty Clay; Light Gray, red and yellow mottling present.

Silty Clay; Light Gray, red mottling present, very hard and brittle.

Sandy Silt; Light Gray, yellow mottling present.

Silty Clay; Light Gray, red and yellow mottling present, very hard, brittle.

Silty Sand; Light Gray, fine to medium-grained sand, yellow mottling and lignite

present.

Sandy Silt; Light Gray, hard with black, yellow, and red mottling present.

Silty Sand; Light Gray, fine to medium-grained, mottling present, gravel present.

Sand; Gray, medium to coarse-grained, red and yellow mottling present.

Silty Clay; Light Gray with yellow and red mottling, very hard, brittle.

Clay; Reddish Brown, light gray and bluish black mottling present, very hard, brittle.

Clay; Reddish Brown, sand lenses present, lignite and yellow and gray mottling

present, very hard.

Sandy Silt; Dark Brownish Gray, lignite and yellow mottling present, hard, brittle.

Silty Clay; Reddish Gray, nodes of very fine-grained sand and silt present, mottling

present.

Silty Clay; Reddish Gray, nodes of very fine-grained sand and silt present, mottling

present, angular cobbles present.

Sandy Silt; Gray, coarse sand to gravel-sized grains present and increasing to 171

feet.

Silty Sand; Gray, contains black organic and white fine-grained lenses.

Silty Clay; Gray to Dark Gray, lignite banding and fine-grained lenses present.

Silty Clay; Light and Dark Gray varved layering.

Sand; Light Gray to Tan, medium to coarse-grained, well-sorted.

Silty Clay; Light and Dark Gray varved layering.

Sand; Light Gray to Tan, medium to coarse-grained, well-sorted.

Silty Clay; Light and Dark Gray varved layering.

Sand; Light Tan, medium to coarse-grained, well-sorted.

Silty Clay; Light and Dark Gray varved layering.

Sand; Light Tan, medium to coarse-grained, well-sorted, dark black organic banding

present.

UPA, shallow Confining Unit

GAMMA

050100

150

200

AP-COND -14090

0

Lithologic Description Aquifer Well

392546075581902 CE Dd 150

Boart Longyear

3/25/2010

3/27/2010

J. Sorenson

248

145

0.015

Sonic

39°25'46.6"N

75°58'18.7"W

16.45

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 3 2P
196 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

250

240

230

220

210

200

p

Silty Clay; Light and Dark Gray varved layering.

Sand; Light Tan, medium to coarse-grained, well-sorted, dark black organic banding

and detritus present.

Sand; Gray to Tan, coarse-grained, yellow mottling present.

Sand; Light Gray, coarse-grained, medium to coarse-grained, nodes of gray clay

and lignitic debris present.

Sand; Light Tan, medium to coarse-grained, well-sorted, trace gravel present.

Sand; Light Tan, medium to coarse-grained, well-sorted.

Sand; Gray, medium to coarse-grained, well-sorted, lignitic debris present.

Clay; Dark Gray, reddish brown mottling and lignite present.

Clay; Dark Gray, very hard.

Clay; Brown to Reddish Brown, light gray and yellow mottling present.

Clay; Dark Gray, reddish brown mottling present.

Sand; Gray, medium to coarse-grained, lignite present.

Sand; Tan, medium to coarse-grained, black and red mottling present.

Sand; Brown, red clay lenses present.

Sand; Light Gray and Tan, coarse-grained.

Clay; Dark Gray, white silt lenses and gray mottling present, very hard.

UPA, deep

GAMMA

050100

150

200

AP-COND -14090

0

Lithologic Description Aquifer Well

392546075581902 CE Dd 150

Boart Longyear

3/25/2010

3/27/2010

J. Sorenson

248

145

0.015

Sonic

39°25'46.6"N

75°58'18.7"W

16.45

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 3 3P
Appendix C 197

40

35

30

25

20

15

10

5

0 Fill.

Sand; Tan, fine-grained sand, well-sorted.

Sand; Gray, fine to very fine-grained. 3-inch layer of dark Gray Clay at 3 feet.

Sand; Brown, medium-grained, trace gravel present.

Sandy Clay; Dark Gray to Black, fine-grained. Red Sand and Gravel at 6 feet. 6-inches of Brown Silty

Clay at 7.5 feet.

Silty Sand; Brown, poorly-sorted.

Sand; Brown, very fine-grained, gray mottling present.

Sand; Gray, very fine-grained, well-sorted.

Sand; Reddish Brown, very fine-grained, well-sorted. Grades finer to 17 feet.

Sand; Tan, very fine-grained, well-sorted, Clay nodules present, grades coarser to 20 feet.

Sand; Tan, very fine-grained, well-sorted, Gray Clay present.

Silty Sand; White, fine-grained.

Sand; Tan, medium to coarse-grained, gravel present.

Silty Sand; Gray, trace gravel present, 6-inch band of coarser sands and 3-inches of Gray Silty Clay at

26 and 26.5 feet respectively.

Sand; Reddish Brown, fine to coarsely-grained, 2-inch band of Gray Clayey Sand at 28 feet, trace

gravel from 28-29 feet.

Sand; Reddish Brown, fine to coarsely-grained, trace gravel present.

Sand; Reddish Brown, fine to medium-grained, angular, 2-inch micaceous Gray Silty Sand present at 33

feet.

Sand; Dark Reddish Brown, fine to medium-grained, angular, grades coarser to 36 feet.

Sand; Dark Reddish Brown, fine to medium-grained, angular, trace gravel present.

Sand; Dark Reddish Brown, fine-grained, angular, increasing gravel content.

Magothy

Lithologic Description Aquifer Well

392537075593001 CE Dd 151

Boart Longyear

3/30/2010

4/1/2010

A. Massey

40

40

0.02

Sonic

39°25'36.8"N

75°59'29.9"W

21.83

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 1 1P
198 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

80

70

60

50

40

30

20

10

0 Fill.

Sand; Tan, fine-grained sand, well-sorted.

Sand; Gray, fine to very fine-grained. 3-inch layer of dark Gray Clay at 3 feet.

Sand; Brown, medium-grained, trace gravel present.

Sandy Clay; Dark Gray to Black, fine-grained. Red Sand and Gravel at 6 feet.

6-inches of Brown Silty Clay at 7.5 feet.

Silty Sand; Brown, poorly-sorted.

Sand; Brown, very fine-grained, gray mottling present.

Sand; Gray, very fine-grained, well-sorted.

Sand; Reddish Brown, very fine-grained, well-sorted. Grades finer to 17 feet.

Sand; Tan, very fine-grained, well-sorted. Clay nodules present, grades coarser to

20 feet.

Sand; Tan, very fine-grained, well-sorted, Gray Clay present.

Silty Sand; White, fine-grained.

Sand; Tan, medium to coarse-grained, gravel present.

Silty Sand; Gray, trace gravel present, 6-inch band of coarser sands and 3-inches of

Gray Silty Clay at 26 and 26.5 feet respectively.

Sand; Reddish Brown, fine to coarsely-grained. 2-inch band of Gray Clayey Sand

at 28 feet, trace gravel from 28-29 feet.

Sand; Reddish Brown, fine to coarsely-grained, trace gravel present.

Sand; Reddish Brown, fine to medium-grained, angular, 2-inch micaceous Gray Silty

Sand present at 33 feet.

Sand; Dark Reddish Brown, fine to medium-grained, angular, grades coarser to 36

feet.

Sand; Dark Reddish Brown, fine to medium-grained, angular, trace gravel present.

Sand; Dark Reddish Brown, fine-grained, angular, increasing gravel content.

Sand; Reddish Brown, medium-grained, well-graded to coarser Sand and angular

gravel up to one-inch in size.

Sand; Light Gray to White, very fine-grained, well-sorted.

Clayey Silt; Light Gray.

Sand; Light Gray to White, very fine-grained, well-sorted.

Sand; Light Gray to White, very fine to fine-grained, tan mottling present.

Sand; Light Gray to White, very fine to fine-grained, tan mottling present, silt present

in matrix. 6-inch Brown, medium-grained Sand at 53.5 feet.

Sand; Gray, very fine-grained, well-sorted,.

Clay; Gray, reddish brown mottling present.

Sand; Light Gray, fine-grained, intermittent reddish brown color increasing to 62 feet.

Sand; Tan, irregularly-shaped gray silty clay nodes present.

Sand; Light Tan to White, fine to medium-grained, well-sorted.

Sand; Gray, fine to medium-grained, well-sorted.

Sand; Gray, fine to medium-grained, well-sorted, well-graded finer.

Silty Clay; Gray.

Sand; Gray, fine to medium-grained, well-sorted, well-graded finer.

Sand; Fine to very-fine-grained.

Magothy

GAMMA

-10

40

90

AP-COND

0

255075

Lithologic Description Aquifer Well

392537075593002 CE Dd 152

Boart Longyear

3/30/2010

3/31/2010

A. Massey

217

177

0.02

Sonic

39°25'36.8"N

75°59'29.9"W

21.99

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 3 1P
Appendix C 199

160

150

140

130

120

110

100

90

80

Sa d; e o e y e g a ed

Silty Sand; Gray, very-fine-grained, reddish brown mottling present.

Sand; Brown, medium-grained, well-sorted, rounded.

Sand; Tan, medium-grained, well-sorted, rounded, clay nodules present, trace clay

in matrix increasing to 85 feet.

Sand; Tan, medium-grained, well-sorted, rounded..

Sand; Brown to Reddish Brown, fine to medium-grained, well-sorted, rounded.

Sand; Reddish Brown, medium to coarse-grained, poorly-sorted, rounded,

Sand; Tan to Light Reddish Brown, medium-grained,

Silty Sand; Gray, coarse-grained, angular.

Silty Clay; Gray, dark red mottling present at 93.5 feet, hard.

Clay; Gray, hard.

Silty Clay; Dark Gray, hard, light gray silty inclusions.

Clay; Dark Gray, hard.

Clay; Dark Gray, with light gray mottling.

Silt; Dark Gray, hard.

Clayey Silt; Gray and Dark Red.

Clayey Silt; Dark Red and Gray, mottling present.

Sand; Tan, medium-grained.

Silt; Gray, dark red sand present.

Sand Clay; Gray, very fine=grained.

Silt; Gray, hard.

Sand; Gray, very fine-grained. 4-inch hard, gray silt present at 114 feet.

Sand; Light Tan, medium-grained, well-rounded.

Sand; Light Tan, medium-grained.

Sand; Light Tan, medium-grained, angular sandstone cobbles present.

Sand; Brown, medium to coarse-grained, angular gravel present.

Clay; Gray and Dark Red, hard, mottling present.

Silty Clay; Gray, dark red mottling present, hard.

Silty Clay; Gray, dark red mottling present, medium to coarse-grained sand present,

hard.

Clayey Silt; Gray, brown and red mottling present, hard.

Clay; Dark Red, gray mottling present.

Clay; Dark Brown, hard.

Clayey Silt; Light Gray.

Silty Sand; Gray, very fine-grained.

Silt; Gray, dense.

Clayey Silt; Dark Brown.

Silt; Very Dark Gray, trace lignite present.

Sand; Gray, very fine-grained.

Clayey Silt; Dark Gray.

Silty Sand; Dark Gray, very fine-grained sand.

Silt; Gray and Tan banded coloring.

Sand; Gray and Black banded coloring, very fine-grained.

Sandy Silt; Gray and Black banded coloring, very fine-grained.

Silt; Gray, lignite present.

Sand; Light Gray, very fine-grained, 4-inch zone containing black streaking present

UPA, shallow Confining Unit

GAMMA

-10

40

90

AP-COND

0

255075

Lithologic Description Aquifer Well

392537075593002 CE Dd 152

Boart Longyear

3/30/2010

3/31/2010

A. Massey

217

177

0.02

Sonic

39°25'36.8"N

75°59'29.9"W

21.99

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 3 2P
200 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

220

210

200

190

180

170

160 at 161 feet.

Sand; Light Gray, very fine-grained, organics present at 164-feet.

Silty Clay; Light Gray, high organic content.

Sand; Gray, fine-grained, increased lignite content to 169 feet.

Sand; Light to Dark Gray, very fine-grained.

Sand; Dark Gray, organic detritus present at 177.5 feet, bands of Dark Gray sand,

silt and organics.

Silt; Dark Gray, organic detritus present.

Sand; Light Gray, very fine to medium-grained.

Silty Clay; Light to Dark Gray banded coloring present, fine-grained sand present in

veins.

Silt; Gray to Dark Gray banded coloring, Gray Clay and Light Gray fine-grained

Sand lenses present.

Silt; Gray to Dark Gray, gray very fine-grained sand lenses present, lignite present.

Sand; Gray and Black, fine -grained.

Silty Sand; Gray, very fine-grained.

Silty Sand; Fine-grained, well-graded to coarse-grained, very hard.

Silty Sand; Gray, very fine-grained.

Sand; Gray, very fine-grained, Dark Gray Silty Clay lenses present from 201 to 204

feet.

Sand; Light Gray, very fine-grained.

Silty Sand; Gray, medium to coarse-grained, poorly sorted, organic detritus present.

Silty Sand; Gray, organics and lignite present, gray Silty Clay lenses up to 2 inches

present.

Silty Clay; Gray, light gray mottling present, lignite present.

Silty Sand; Gray, organics and lignite present, gray Silty Clay lenses up to 2 inches

present.

Sand; Gray, fine to medium-grained, well-sorted.

UPA, deep

GAMMA

-10

40

90

AP-COND

0

255075

Lithologic Description Aquifer Well

392537075593002 CE Dd 152

Boart Longyear

3/30/2010

3/31/2010

A. Massey

217

177

0.02

Sonic

39°25'36.8"N

75°59'29.9"W

21.99

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 3 3P
Appendix C 201

90

85

80

75

70

65

60

55

50

45

40

35

30

25

20

15

10

5

0

No observations. Aquifer designation based on adjacent wells.

Silty Clay; Green, mottling and sand present.

Sandy Silt; Aqua Blue, organics present.

Clayey Silt; Dark Gray, organics present, very micaceous, <1 inch-thick gravel lenses present at 49 feet.

Silt; Very fine-grained, lignite and organics present, micaceous.

Sand; Gray, very fine-grained, light and silver mica present.

Sand; White to Light Gray, fine-grained.

Sandy Silt; Light to Medium Gray, lignite and organics present.

Sand; Light to Medium Gray, lignite and organics present.

Silt; Dark Gray, micaceous, lignite present.

Sand; Medium Gray, fine-grained.

Silty Clay; Dark Gray, organics present.

Silty Sand; Dark Gray, fine to coarse-grained, organics present.

Sandy Clay; Organics present.

Sand; Light Orange to Tan, medium to coarse-grained, poorly-sorted.

Sand; Poorly-sorted, angular gravel present, organics and clay nodules present.

Sand; White to Light Tan, fine to coarse-grained, poorly-sorted, well-rounded.

Matawan Confining Unit Magothy

Lithologic Description Aquifer Well

392521075583301 CE Dd 153

Boart Longyear

4/13/2010

4/14/2010

C. Dieter

88

88

0.015

Sonic

39°25'20.7"N

75°58'33.2"W

48.34

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 1 1P
202 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

170

160

150

140

130

120

110

100

90

80

70

60

50

40

30

20

10

0

No observations. Aquifer designation based on adjacent wells.

Sand; Gray, fine-grained, lenses of gray silty clay and lignite present.

Silt; Gray, clay present in matrix.

Sand; Gray, fine-grained, clay nodules and lignite present.

Sand; Tan and Gray, lignite present. Lenses of silt and clay present from 150 to 152 feet.

Sand; Gray to Tan, fine-grained.

Sand; Light to Dark Gray, dark gray clay lens present at 158 feet.

Clay; Gray, brown and red mottling present, hard.

Matawan Confining Unit

Magothy Confining Unit UPA, shallow

Lithologic Description Aquifer Well

392521075583302 CE Dd 154

Boart Longyear

4/11/2010

4/12/2010

A. Massey

167

162

0.015

Sonic

39°25'20.7"N

75°58'33.2"W

47.61

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 1 1P
Appendix C 203

120

110

100

90

80

70

60

50

40

30

20

10

0 Sandy Silt; Brown, soft, gravel present.

Sandy Clay; Tan, interbedded Reddish-Brown and Gray coloring, hard.

Sandy Clay; Dark Green, tan mottling present, iron nodules present,

medium-hardness.

Sandy Clay; Dark Green to Blue, dark gray mottling present, medium-hardness

grading to hard.

Sandy Silt; Dark Gray, soft. Pyrite nodules present at 17, 22, and 40 feet.

Sandy Silt; Light Gray, gray mottling present.

Sandy Silt; Dark Gray to Black, coarse-grained, gravel present.

Silty Sand; Dark Gray to Black, lignite and organic detritus present.

Silty Sand; Light Gray, gray and tan mottling present. Thin lenses of high-organic

content and detritus present at 60, 64, and 66 feet.

Sand; Light Gray to White, medium to coarse-grained. 3-inch clay lens at 67.75 feet.

Silty Sand; Dark Gray, light gray mottling present, organic detritus present.

Sand; Yellowish Tan, medium to coarse-grained. Gravel lens at 77.5 feet.

Silty Sand; Tan, yellowish-tan mottling present, gravel present.

Sand; Yellowish-Tan to White, coarse-grained, angular gravel present. 4-inch clay

lens at 86 feet.

Silty Sand; Yellow to Tan, fine-grained sand, gravel present.

Silty Clay; Light Brown, dark-brown and yellow mottling present, hard, white nodes

of silt present from 100 to 102 feet.

Matawan Confining Unit

Magothy Confining Unit

GAMMA

050100150

200

AP-COND180 -280

0

Lithologic Description Aquifer Well

392521075583303 CE Dd 155

Boart Longyear

4/8/2010

4/10/2010

J. Sorenson

287

223

0.02

Sonic

39°25'20.7"N

75°58'33.2"W

46.99

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 3 1P
204 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

240

230

220

210

200

190

180

170

160

150

140

130

120

Sandy Silt; Gray, brown mottling present at 125 feet.

Sand; Light Gray to Gray, organic detritus present.

Silty Clay; Dark Gray, organic detritus present.

Sandy Silt; Gray, black mottling present.

Sand; Gray, fine to medium-grained, organic detritus present.

Interval of an approximate sample recovery of 40%. Tan Sand in upper 3 feet and

Gray Sandy Silt in lower foot.

Silty Clay; Light Gray and Gray interbedded coloring. Thin lens of organic detritus at

147.2 feet.

Silty Sand; Gray, black mottling present.

Sand; Yellowish Tan to Tan, fine to medium-grained.

Silty Clay; Gray, dark green and dark red mottling present.

Silty Sand; Gray, tan mottling present.

Silty Clay; Gray, dark green and dark red mottling present.

Silty Clay; Dark Gray, lignite and organic detritus present, very hard.

Silty Sand; Gray, coarse-grained, gravel present, lignite present.

Sandy Silt; Gray, gray clay and tan mottling present.

Clayey Silt; Dark Gray and interbedded light gray lenses, medium-grained sand

present in matrix, hard.

Sand; Yellowish Tan, medium to coarse-grained.

Sand; Tan, medium-grained, well-sorted.

Sand; Brown to Light Tan, medium to coarse-grained, dark gray mottling.

Sandy Silt; Tan, brown and yellow mottling present, medium-hardness.

Silty Sand; Dark Gray, black mottling, organic detritus, and lignite present.

Silty Clay; Dark Gray interbedded with Light Gray, lignite present.

Silty Sand; Dark to Light Gray lignite present

UPA, shallow Confining Unit

UPA, deep

GAMMA

050100150

200

AP-COND180 -280

0

Lithologic Description Aquifer Well

392521075583303 CE Dd 155

Boart Longyear

4/8/2010

4/10/2010

J. Sorenson

287

223

0.02

Sonic

39°25'20.7"N

75°58'33.2"W

46.99

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 3 2P
Appendix C 205

300

290

280

270

260

250

240 Silty Sand; Dark to Light Gray, lignite present.

Silty Clay; Dark Gray, lignite present, very hard.

Clay; Dark Gray, light tan silt lenses and lignite present.

Clayey Silt; Light Gray, green and red mottling present.

Clayey Silt; Olive Green, light gray and red mottling, very hard.

Clayey Silt; Light Gray, mottling present, friable.

Silt; Gray, hard, silt concretions and sand present, saturated.

Clayey Silt; Reddish Brown, gray mottling, hard.

Clayey Silt; Dark Gray, light gray and black mottling, very hard.

Sandy Silt; Light Gray.

Clayey Silt; Dark Gray, light gray and black mottling, very hard.

Confining Unit

GAMMA

050100150

200

AP-COND180 -280

0

Lithologic Description Aquifer Well

392521075583303 CE Dd 155

Boart Longyear

4/8/2010

4/10/2010

J. Sorenson

287

223

0.02

Sonic

39°25'20.7"N

75°58'33.2"W

46.99

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 3 3P
206 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

100

90

80

70

60

50

40

30

20

10

0 Sand; Reddish Brown, gravel present.

Clay; Red and Gray.

Silty Clay; Sand, poorly-sorted, gravel present.

Sand; Brown, medium-grained, well-sorted, angular.

Clay; Dark Gray. Organics present, very-fine sandy silt lenses present.

Clay; Gray, stiff.

Clay; Gray and Tan, very soft, silt present.

Silty Clay; Gray, dark oxidized bands present, angular gravel present.

Sandy Clay; Red to Dark Gray, mottled.

Sand; Brown, very fine-grained.

Silty Sand; Gray and Brown.

Silty Clay; Gray, medium-stiff.

Silty Clay; Gray, organics present, medium-stiff, trace gravel present.

Silty Sand; Gray, very fine-grained, organic detritus present.

Silty Clay; Gray, organics present, medium-stiff, trace gravel present.

Sand; Medium-grained, poorly-sorted, gravel and cobbles present.

Sand; Gray, fine-grained, well-sorted.

Sand; Light Gray, coarse-grained, poorly-sorted.

Sand; Gray, fine-grained.

Sand; Light Tan, very fine-grained, very well-sorted.

Silty Sand; Gray, very fine-grained, brown and gray mottling, trace gray clay lenses.

Magothy Confining Unit UPA, shallow

GAMMA 4090

AP-COND -4163656

Lithologic Description Aquifer Well

392552075591601 CE Dd 156

Boart Longyear

3/29/2010

3/29/2010

A. Massey

127

87

0.02

Sonic

39°25'52.2"N

75°59'16.4"W

27.19

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 2 1P
Appendix C 207

130

120

110

100

Silty Clay; Dark Gray.

Sand; Gray, very fine-grained, gray clay lenses present.

Silt; Gray, hard.

Sand; Gray, very fine-grained.

Clay; Gray, reddish-brown mottling present, hard.

Clay; Reddish-Brown. Mottling present, hard

Silty Sand; Light Gray, very fine-grained.

Clayey Silt; Light Gray, dark reddish brown mottling present.

Confining Unit

GAMMA 4090

AP-COND -4163656

Lithologic Description Aquifer Well

392552075591601 CE Dd 156

Boart Longyear

3/29/2010

3/29/2010

A. Massey

127

87

0.02

Sonic

39°25'52.2"N

75°59'16.4"W

27.19

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 2 2P
208 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

60

55

50

45

40

35

30

25

20

15

10

5

0

No observations. Aquifer designation based on adjacent wells.

Silt; Gray, yellow-tan mottling present.

Silty Sand; Gray to Tan, fine-grained.

Sand; Light Tan, fine to coarse-grained, well-graded to coarse-grained, trace gravel present.

Gravelly Sand; Dark Brown sand, grain sizes up to cobbles present.

Sand; Light Tan to White, medium to coarse-grained. 2-inch sandy silt lenses present at 55 and 56 feet.

Silty Sand; Light Gray, fine to medium-grained, nodes of silty clay present.

Confining Unit

Magothy

Lithologic Description Aquifer Well

392537075590101 CE Dd 157

Boart Longyear

4/7/2010

4/7/2010

J. Sorenson

58

56

0.02

Sonic

39°25'36.8"N

75°59'00.9"W

38.22

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 1 1P
Appendix C 209

100

90

80

70

60

50

40

30

20

10

0 Silty Clay; Brown, gravel present.

Silty Sand; Dark Brown.

Clay; Dark Gray to Black, contains brown silty sand, organics present, soft.

Clay; Dark Gray to Black, organic detritus present, soft. Fine to medium-grained

Silty Sand lens present at 12.5 feet.

Clay; Gray, light gray mottling present.

Clay; Dark Gray to Black, organic detritus present, soft.

Clay; Dark Gray to Black, soft.

Sandy Silt; Gray to Tan, light gray mottling present, trace gravel present, grades

from soft to hard in observed interval.

Clay; Light Gray, tan and yellow mottling present, moderately hard.

Sand; Tan to Light Tan, fine to medium-grained, mottling present.

Silty Sand; Light Tan, fine-grained.

Sand; Tan to Dark Brown, medium to coarse-grained, silty lenses and nodes

present, angular gravel present.

Silty Sand; Light Gray to Blue-Gray, fine-grained, yellow and tan mottling present.

Sand; Light Gray, fine to medium-grained, well-sorted, yellow mottling present from

77 to 81 feet.

Clay; Light Gray, yellow mottling present, hard.

Silty Sand; Yellow-Tan, medium-grained, yellow-red mottling present, well-graded

to sandy silt. 6-inch Light Gray Sandy Silt lens at 85.5 feet.

Sand; Yellow-Tan, medium to coarse-grained, black and light tan mottling present.

Silty Clay; Light Gray to Blue-Gray, very hard.

Confining Unit

Magothy Confining Unit

GAMMA

0

50

100150

AP-COND200 100

0

Lithologic Description Aquifer Well

392537075590102 CE Dd 158

Boart Longyear

4/6/2010

4/7/2010

A. Massey

148

112

0.02

Sonic

39°25'36.8"N

75°59'00.9"W

38.36

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 2 1P
210 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

150

140

130

120

110

100 Silty Sand; Light Gray, reddish brown mottling present.

Clay; Dark Gray with bands of Light Gray, very hard.

Sand; Yellow, medium to coarse-grained, dark gray mottled lens at 109 to 110 feet.

Silty Sand; Light Gray, medium to coarse-grained, reddish gray mottling present.

Silty Sand; Red, coarse-grained, nodes and streaks of silty clay.

UPA, shallow

GAMMA

0

50

100150

AP-COND200 100

0

Lithologic Description Aquifer Well

392537075590102 CE Dd 158

Boart Longyear

4/6/2010

4/7/2010

A. Massey

148

112

0.02

Sonic

39°25'36.8"N

75°59'00.9"W

38.36

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 2 2P
Appendix C 211

80

70

60

50

40

30

20

10

0 Fill; Dark Brown, contains gravel.

Silty Sand; Brown.

Silty Sand; Orange Brown, contains rounded gravel.

Sand; Tan, trace gravel present.

Clay; Gray, high plasticity.

Silty Sand; Iron oxide staining present.

Silty Sand; Tan, trace gravel present.

Silty Sand; Tan to Gray, trace gravel present.

Clayey Sand; Gray, cobble-sized gravel present.

Silty Sand; Orange Brown, with poorly-sorted gravel.

Sandy Gravel; Gray and Tan, medium to coarse-grained sand, poorly-sorted gravel.

Sandy Gravel; Gray to White, poorly-sorted, orange staining.

Clay; White, gravel present.

Silty Sand; Tan.

Sand; Coarse-grained.

Sand; Orange to Tan, gravel present.

Silty Clay; Orange, contains gray clay lenses.

Sandy Clay; Fine to medium-grained.

Silty Sand; Tan, fine-grained sand.

Clay; White, high plasticity, trace amounts of silt present.

Silty Sand; Tan to Dark Gray.

Clay; Yellow to Tan, red and white mottling present.

Clay; Dark Red, yellow mottling present.

Clay; Dark Gray, lignite present.

Clay; Dark Gray to Black, high plasticity, lignite present.

Clay; Gray, high plasticity, tan and red clay inclusions present.

Clay; Dark Red, high plasticity, tan clay inclusions present.

Silty Sand; Brown, Gray, and White, well-graded, clay present.

Clay; Dark Red, high plasticity.

Sand; Tan and Orange, fine to medium-grained, poorly-sorted.

Sand; Tan and Orange, fine to medium-grained, poorly-sorted, trace iron concretions present.

Magothy Confining Unit

GAMMA

150100

0

50

Lithologic Description Aquifer Well

392545075594601 CE Dd 159

Boart Longyear

4/6/2010

4/6/2010

M. Leipert (USACE)

121

35

0.02

Sonic

39°25'44.7"N

75°59'46.0"W

28.20

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 2 1P
212 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

130

120

110

100

90

80 Sand; Tan, very fine-grained, well-sorted.

Sand; Gray, medium to coarse-grained.

Sand; Tan, very fine to medium-grained, well-sorted.

Sand; Tan to Orange, medium to coarse-grained, well sorted, trace iron concretions present.

Sandy Clay; White and Red, high plasticity.

Sand; Orange Brown, fine to medium-grained, iron concretions present.

Sand; Orange Brown, white and gray clay lenses present.

Clay; Tan, high plasticity, red clay inclusions present.

Silty Clay; Gray.

Silty Clay; Gray, white and red clay inclusions present.

Silty Clay; Dark Red.

Sand; Tan, fine to medium-grained, well-sorted, concretions present.

Clay; Tan and Gray, mottling present.

UPA, shallow Confining Unit

GAMMA

150100

0

50

Lithologic Description Aquifer Well

392545075594601 CE Dd 159

Boart Longyear

4/6/2010

4/6/2010

M. Leipert (USACE)

121

35

0.02

Sonic

39°25'44.7"N

75°59'46.0"W

28.20

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 2 2P
Appendix C 213

120

110

100

90

80

70

60

50

40

30

20

10

0

No observations. Aquifer designation based on adjacent wells.

Sand; Medium to coarse-grained.

Clay.

Sand; Medium to coarse-grained.

Clay.

Magothy Confining Unit UPA, shallow Confining Unit

GAMMA

0

50

100150

AP-COND 204570

Lithologic Description Aquifer Well

392545075594602 CE Dd 160

Boart Longyear

4/9/2010

4/9/2010

J. Sorenson

120

116

0.02

Sonic

39°25'44.7"N

75°59'46.0"W

27.64

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 1 1P
214 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

100

90

80

70

60

50

40

30

20

10

0 Silty Clay; Brown.

Silt; Light Brown, dry, friable.

Clayey Silt; Medium gray-brown, with trace gravel and nodules.

Sand; Brown, very fine-grained, micaceous.

Silty Sand; Medium orange-brown very fine-grained, iron nodules present.

Sand; Light orange-gray, very fine-grained, micaceous, trace amounts of organics

present.

Sand; Light gray, very fine-grained.

Sand; Light gray, very fine-grained, micaceous, trace amounts of organics present.

Sand; Light Gray, fine-grained, iron nodules present, red pore-water present.

Sand; Light gray, fine to medium-grained, iron staining present.

Sand; Light brown-gray, fine-grained, micaceous, heavier, darker minerals present.

Sand; Light gray, fine-grained, orange staining present.

Sand; White, coarse-grained, poorly-sorted, coarse, angular gravel present.

Sand; Medium to coarse-grained, poorly-sorted, trace gravel.

Sand; Medium-grained, poorly-sorted, trace gravel.

Sand; Coarse-grained, poorly-sorted, trace gravel.

Sand; Medium-grained, poorly-sorted, trace gravel.

Sand; Coarse-grained, poorly-sorted, trace gravel.

Clayey Silt; Light gray, light orange iron banding present.

Silty Sand; Light gray, very fine-grained.

Silty Sand; Light gray, very fine-grained, very firm.

Sand; Light gray, very fine-grained, well-sorted, light orange iron bands present,

friable.

Sand; Gray, fine-grained.

Sand; Gray, fine to very fine-grained, orange bands present.

Sand; Gray, fine-grained, orange bands present.

Confining Unit Magothy Confining Unit

GAMMA

-104090140

AP-COND -8123252

Lithologic Description Aquifer Well

392530075582001 CE Dd 191

Boart Longyear

11/30/2010

12/3/2010

C. Dieter

197

150

0.015

Sonic

39°25'30.3"N

75°58'20.5"W

21.49

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Scale

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 2 1P
Appendix C 215

200

190

180

170

160

150

140

130

120

110

100 Sand; Gray and orange, fine to very fine-grained.

Sand; Orange, fine to very fine-grained.

Clay; Dark gray, firm.

Sand; Medium gray, very fine-grained, contains clayey silt.

Silty Clay; Dark gray, contains very fine-grained sand and trace lignite.

Silty Clay; Gray, contains gravel and lignite.

Silty Clay; 4" of solid rock present.

Clay; Dark gray, contains very fine-grained sand and lignite.

Clay; Medium gray, lenses of tan silt present.

Clay; Dark gray, contains lignite.

Silty Sand; Gray

Silt; Gray, contains silty sand.

Clay; Dark gray.

Silty Sand; Grayish white.

Clay; Gray, with white silty sand.

Silty Sand; White, clay lenses present.

Sand; White, medium-grained.

Sand; White and Gray, fine-grained.

Silty Clay; Gray.

Clay; Light Gray, very firm.

Clay; Red and Gray.

Clay; Gray.

Clay; Red, saturated.

Silty Clay; Gray.

Silty Sandy Clay; Gray.

Clay; Red to brown, intermediate very fine-grained, gray silty sand present.

Silty Clay; Gray.

Clay; Gray, hard.

Silty Clay; Light gray, transition to gray sandy clay.

Sandy Clay; Gray.

Sand; Gray, alternating very fine to medium-grained.

Silty Sand; Dark gray to black, very fine to fine-grained.

Sand; Coarse sand zone, large lignite inclusion.

Silty Clay; Contains sand.

UPA, shallow Confining Unit

UPA, deep

GAMMA

-104090140

AP-COND -8123252

Lithologic Description Aquifer Well

392530075582001 CE Dd 191

Boart Longyear

11/30/2010

12/3/2010

C. Dieter

197

150

0.015

Sonic

39°25'30.3"N

75°58'20.5"W

21.49

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Scale

(Feet)

U.S. Department of the Interior

U.S. Geological Survey

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 2 2P
216 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

65

60

55

50

45

40

35

30

25

20

15

10

5

0

No observations. Aquifer designation based on adjacent wells.

Sand; Light orange, medium-grained.

Sand; Medium to coarse-grained.

Sand; Light orange, coarse-grained, trace gravel present.

Silty Sand; Light orange, medium-grained.

Sand; Coarse-grained, poorly-sorted, contains gravel.

Sand; Light orange, coarse-grained, very fine-grained sand lenses present..

Sand; Light orange, coarse-grained, poorly-sorted, gravel present.

Sand; Orange, coarse-grained, poorly-sorted, gravel present.

Sand; Light gray and orange, coarse-grained, poorly-sorted, gravel present.

Matawan Confining Unit

Magothy

Lithologic Description Aquifer Well

392530075582002 CE Dd 192

Boart Longyear

12/4/2010

12/4/2010

P. Lapa-Lilly

67

67

0.015

Sonic

39°25'30.3"N

75°58'20.5"W

21.60

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 1 1P
Appendix C 217

80

70

60

50

40

30

20

10

0

Topsoils, roots and gravel present.

Sandy Silt; Light Grayish Brown, friable.

Clayey Silt; Brown, organic detritus present.

Clayey Silt; Light Grayish Brown, dry, iron staining present.

Sandy Silt; Light Gray, gravels and organics present.

Sand; Medium to coarse-grained, medium to coarse gravel and cobbles present.

Clayey Silt; Dark Gray, soft, micaceous. Contains Silt clasts at 17 and 37 feet.

Silt; Light Gray, trace fine-grained sand, micaceous.

Sand; Light Gray, very fine-grained, micaceous.

Silt; Light Gray, micaceous.

Silt; Dark Gray, lenses of very-fine-grained sand present, micaceous.

Sand; Medium Gray, very fine-grained, micaceous.

Sandy Silt; Dark gray, micaceous.

Sand; Gray, fine-grained.

Sand; Gray, fine to medium-grained, iron staining and nodules present.

Sand; Orange Gray, transition from Sand to Silts.

Sand; Orange, medium-grained.

Sand; Medium to coarse-grained, iron staining present.

Clayey Silt; Tan.

Sand; Fine-grained.

Silty Sand; Fine-grained.

Sand; Very fine-grained, silty sand lenses present.

Sandy Clay; Tan, lignite present.

Silty Sand; Fine-grained, micaceous.

Confining Unit

Magothy

GAMMA

0

50

100150

AP-COND -4163656

Lithologic Description Aquifer Well

392525075581401 CE Dd 193

Boart Longyear

12/6/2010

12/7/2010

C. Dieter

197

88

0.015

Sonic

39°25'24.6"N

75°58'14.5"W

43.28

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 3 1P
218 Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area

160

150

140

130

120

110

100

90

80

Sand; Fine to medium-grained, micaceous.

Sand; Coarse-grained, poorly-sorted, sub-angular, gravel present.

Silt; Light Gray, zones of very fine-grained sand present, orange staining present.

Clay; Light Gray, zones of increased silt content present.

Clay; Light Gray, very firm, hard, red mottling present, oxidized zones of iron

present.

Silty Clay; Light Gray, Light red and yellow brown mottling present.

Silty Clay; Light Pink and Gray, yellow brown mottling present.

Silty Clay; Light Gray.

Sandy Silt; Light Gray, very fine-grained.

Silt; Light Pink and Gray, yellow brown mottling present.

Clay; Light Pink and Gray, purple mottling present.

Silty Clay; Light Gray, zones of maroon and yellow mottling present from 119 to 122

feet.

Clay; Medium Gray, gray, brown, and pink mottling present.

Clay; Light Gray, mottling present.

Silty Clay; Yellow Brown and Light Gray, mottling present.

Silty Clay; Medium Gray, gray and brown mottling present.

Clayey Silt; Medium Gray, lignite and zones of light tan sand present.

Silty Clay; Medium Gray, lignite and zones of light tan sand present.

Silty Clay; Medium Gray, lignite present.

Confining Unit

GAMMA

0

50

100150

AP-COND -4163656

Lithologic Description Aquifer Well

392525075581401 CE Dd 193

Boart Longyear

12/6/2010

12/7/2010

C. Dieter

197

88

0.015

Sonic

39°25'24.6"N

75°58'14.5"W

43.28

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 3 2P
Appendix C 219

200

190

180

170

160

Silty Clay; Medium Gray, thinly interbedded clays, silts, and tan sands.

Clay; Medium Gray.

Sand; Medium Gray, very fine-grained, well sorted.

Silty Clay; Medium Gray, thinly interbedded clays, silts, and tan sands.

Sand; Light to Medium Gray, Fine-grained, zones of clay at 178 and 182 feet.

Clayey Sand; Medium to Dark Gray, fine to medium-grained, lignite present.

Clayey Sand; Medium Gray, fine to medium-grained.

UPA, shallow

GAMMA

0

50

100150

AP-COND -4163656

Lithologic Description Aquifer Well

392525075581401 CE Dd 193

Boart Longyear

12/6/2010

12/7/2010

C. Dieter

197

88

0.015

Sonic

39°25'24.6"N

75°58'14.5"W

43.28

Station ID:

Date Began:

Date Completed:

Logged By:

Boring Depth (Feet):

Well Depth (Feet):

Drilling Method:

Screen Size (Inches):

Driller:

Latitude

(NAD 83):

Longitude

(NAD 83):

Land Surface Elevation

(NAVD 88):

Pearce Creek

Dredge Material Containment Area

Cecil County, Maryland

Lithologic

Log

Depth

(Feet)

U.S. Department of the Interior

U.S. Geological Survey 

Well Construction

Cement with Grout

Bentonite

Sand #00

Sand #01

Casing

Screen

Aquifer

Magothy

UPA, shallow

UPA, deep

Matawan Confining Unit

Confining Unit

age of 3 3P
Prepared by West Trenton and Rolla Publishing Service Centers

For additional information, contact:

Director, MD-DE-DC Water Science Center

U.S. Geological Survey

5522 Research Park Drive

Baltimore, MD 21228

or visit our Web site at:

http://md.water.usgs.gov

Dieter and others—Hydrogeologic Framework, Hydrology, and Water Quality in the Pearce Creek Dredge Material Containment Area—Scientific Investigations Report 2012–5263

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