U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2009–5051

National Water-Quality Assessment Program

Transport of Anthropogenic and Natural

Contaminants (TANC) to Public-Supply Wells

Aquifer Chemistry and Transport Processes in the

Zone of Contribution to a Public-Supply Well in

Woodbury, Connecticut, 2002–06

Not to scale

Glacial

Generalized

groundwater flow

sand and gravel

Glacial

Recharge

till

Fault

Urban area

Water

table

Discharge
This page has been left blank intentionally.
National Water Quality Assessment Program 

Aquifer Chemistry and Transport Processes 

in the Zone of Contribution to a Public-Supply 

Well in Woodbury, Connecticut, 2002–06

By Craig J. Brown, J. Jeffrey Starn, Kenneth G. Stollenwerk, Remo A. Mondazzi, 

and Thomas J. Trombley

Scientific Investigations Report 2009–5051

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: 2009

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Suggested citation:

Brown, C.J., Starn, J.J., Stollenwerk, K.G., Mondazzi, R.A., and Trombley, T.J., 2009, Aquifer chemistry and transport 

processes in the zone of contribution to a public-supply well in Woodbury, Connecticut, 2002–06: U.S. Geological 

Survey Scientific Investigations Report 2009–5051, 158 p. Also available at http://pubs.usgs.gov/sir/2009-5051/.
iii

Foreword

The U.S. Geological Survey (USGS) is committed to providing the Nation with credible scientific 

information that helps to enhance and protect the overall quality of life and that facilitates 

effective management of water, biological, energy, and mineral resources (http://www.usgs.

gov/). Information on the Nation’s water resources is critical to ensuring long-term availability 

of water that is safe for drinking and recreation and is suitable for industry, irrigation, and fish 

and wildlife. Population growth and increasing demands for water make the availability of that 

water, now measured in terms of quantity and quality, even more essential to the long-term 

sustainability of our communities and ecosystems.

The USGS implemented the National Water-Quality Assessment (NAWQA) Program in 1991 

to support national, regional, State, and local information needs and decisions related to 

water-quality management and policy (http://water.usgs.gov/nawqa). The NAWQA Program is 

designed to answer: What is the condition of our Nation’s streams and groundwater? How are 

conditions changing over time? How do natural features and human activities affect the quality 

of streams and groundwater, and where are those effects most pronounced? By combining 

information on water chemistry, physical characteristics, stream habitat, and aquatic life, the 

NAWQA Program aims to provide science-based insights for current and emerging water issues 

and priorities. From 1991-2001, the NAWQA Program completed interdisciplinary assessments 

and established a baseline understanding of water-quality conditions in 51 of the Nation’s river 

basins and aquifers, referred to as Study Units (http://water.usgs.gov/nawqa/studyu.html).

In the second decade of the Program (2001–2012), a major focus is on regional assessments 

of water-quality conditions and trends. These regional assessments are based on major river 

basins and principal aquifers, which encompass larger regions of the country than the Study 

Units. Regional assessments extend the findings in the Study Units by filling critical gaps in 

characterizing the quality of surface water and groundwater, and by determining status and 

trends at sites that have been consistently monitored for more than a decade. In addition, the 

regional assessments continue to build an understanding of how natural features and human 

activities affect water quality. Many of the regional assessments employ modeling and other 

scientific tools, developed on the basis of data collected at individual sites, to help extend 

knowledge of water quality to unmonitored, yet comparable areas within the regions. The 

models thereby enhance the value of our existing data and our understanding of the hydrologic 

system. In addition, the models are useful in evaluating various resource-management scenarios 

and in predicting how our actions, such as reducing or managing nonpoint and point sources of 

contamination, land conversion, and altering flow and (or) pumping regimes, are likely to affect 

water conditions within a region. 

Other activities planned during the second decade include continuing national syntheses 

of information on pesticides, volatile organic compounds (VOCs), nutrients, selected trace 

elements, and aquatic ecology; and continuing national topical studies on the fate of agricultural 

chemicals, effects of urbanization on stream ecosystems, bioaccumulation of mercury in 

stream ecosystems, effects of nutrient enrichment on stream ecosystems, and transport of 

contaminants to public-supply wells. 
iv

The USGS aims to disseminate credible, timely, and relevant science information to address 

practical and effective water-resource management and strategies that protect and restore 

water quality. We hope this NAWQA publication will provide you with insights and information 

to meet your needs, and will foster increased citizen awareness and involvement in the 

protection and restoration of our Nation’s waters.

The USGS recognizes that a national assessment by a single program cannot address all 

water-resource issues of interest. External coordination at all levels is critical for cost-effective 

management, regulation, and conservation of our Nation’s water resources. The NAWQA 

Program, therefore, depends on advice and information from other agencies—Federal, 

State, regional, interstate, Tribal, and local—as well as nongovernmental organizations, 

industry, academia, and other stakeholder groups. Your assistance and suggestions are 

greatly appreciated

Matthew C. Larsen

Associate Director for Water
v

Contents

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

Introduction ....................................................................................................................................................2

Purpose and Scope ..............................................................................................................................3

Description of Study Area ...................................................................................................................3

Previous Investigations........................................................................................................................8

Methods of Data Collection and Analysis .................................................................................................9

Design of Well Network.......................................................................................................................9

Drilling, Coring, and Well Installation ................................................................................................9

Analysis of Glacial Deposits and Bedrock .....................................................................................14

Geophysical Methods ........................................................................................................................15

Collection and Analysis of Water Samples ....................................................................................16

Statistical Analysis .............................................................................................................................19

Quality Assurance...............................................................................................................................19

Hydrogeologic Setting.................................................................................................................................20

Bedrock Geology.................................................................................................................................20

Surficial Deposits................................................................................................................................22

Hydrology .............................................................................................................................................22

Aquifer Chemistry ........................................................................................................................................24

Solid-Phase Geochemistry................................................................................................................24

Mineralogy..................................................................................................................................25

Sediment Extractions ................................................................................................................25

Fission-Track Radiography.......................................................................................................30

Carbon Content ..........................................................................................................................30

Adsorption Reactions................................................................................................................31

Groundwater Chemistry.....................................................................................................................31

Major Elements and Nutrients.................................................................................................34

Temporal Variations in Water Chemistry ...............................................................................76

Redox Conditions and DOC .....................................................................................................76

Naturally Occurring Constituents of Concern.......................................................................81

Stable Isotopes ..........................................................................................................................85

Organic Constituents.................................................................................................................91

Volatile Organic Compounds...........................................................................................92

Pesticides.........................................................................................................................110

Groundwater Age..............................................................................................................................110

Water Sources and Pathways........................................................................................................117

Factors Affecting the Water Chemistry at the Public-Supply Well .........................................121

Summary and Conclusions.......................................................................................................................122

Acknowledgments.....................................................................................................................................125

References Cited........................................................................................................................................125

Appendix 1. Depths of sediment and rock samples and description of texture and lithology, 

color, and sorting, from monitoring-well boreholes in the study area, Woodbury, 

Connecticut................................................................................................................................132
vi

Figures

1. Map showing locations of the regional- and local-scale areas for the study of 

the transport of anthropogenic and natural contaminants (TANC) to public-supply 

wells, monitoring and supply wells used for this study in Connecticut, and the 

glacial stratified deposits in the Connecticut, Housatonic, and Thames River 

Basins (CONN) study unit and surrounding area....................................................................4

2. Map showing modeled area showing wells, geologic materials, altitude of top of 

bedrock, lines of hydrogeologic section, and the contributing recharge area to the 

public-supply well (PSW-1) in the study area, Woodbury, Connecticut .............................5

3. Diagrams showing hydrogeologic sections showing locations and identifiers of 

wells installed in thestudy area, Woodbury, Connecticut .....................................................6

4. Map showing (A) land use/land cover for 2002 with Significant Potential 

Contaminant Sources, simulated paths of flow to monitoring wells, and the 

modeled contributing recharge area to well PSW-1 based on particle tracking 

with MODPATH, and (B) methyl-tert-butyl ether (MTBE) concentrations, in parts per 

billion (ppb), in samples collected September 8, 2004, from wells of shallow (less 

than 6 meters) and intermediate (about 9 meters) depths, Woodbury, Connecticut ........7

5. Diagram showing construction and lithology at public-supply well PSW-1, and 

screened intervals for PSW-1 and adjacent monitoring wells WY100, 101, 102, 103, 

and 106, Woodbury, Connecticut .............................................................................................12

6. Diagram showing construction and lithology at monitoring wells WY91 and 92, 

and multilevel samplers WY92c and WY92e, Woodbury, Connecticut..............................13

7. Map showing bedrock geology of the Pomperaug and Connecticut structural 

basins and the study area, and simulated paths of flow to monitoring wells and 

the modeled contributing recharge area to PSW-1 based on particle tracking with 

MODPATH, Woodbury, Connecticut ........................................................................................21

8. Diagram showing selected groundwater characteristics measured in well 

WY103, May 2005, with a water-quality monitor, and October 2004, with borehole 

geophysical tools, in relation to altitude, Woodbury, Connecticut.....................................24

9. Photographs showing optical microscope images of a sample of glacial deposits 

from 17 meters depth from land surface at borehole WY75, showing (A) an 

iron-oxide grain, and (B) fission tracks recorded after irradiation with uranium-235 

on the same sample, Woodbury, Connecticut.......................................................................30

10. Graph showing concentrations of (A) arsenic (V) in water as a function of arsenic 

sorbed, and (B) uranium (VI) in water as a function of uranium sorbed, based on 

column experiments of core sediments from WY83 (7.3 meters depth below land 

surface), WY90 (6.7 meters depth below land surface), WY92 (3.7 meters depth 

below land surface), WY94 (4.3 meters depth below land surface), and WY100 

(4.8 meters depth below land surface), and simulated sorption for these samples 

using PHREEQC...........................................................................................................................33

Appendix 2. Gamma, fluid temperature, fluid conductivity, and caliper logs, and acoustic 

travel time, acoustic televiewer amplitude, and optical televiewer images for 

bedrock monitoring wells WY86 (2–1), WY87 (2–2), WY97 (2–3), and WY106 (2–4) 

in relation to depth in the study area, Woodbury, Connecticut ........................................148

Appendix 3. Quality-control summary for constituents detected in field blanks and percent 

recovery for surrogates in the study area, Woodbury, Connecticut, 2003–05 ...............152

Appendix 4. Oxidation-reduction (redox) classification scheme developed for the 

transport of anthropogenic and natural contaminants to public-supply wells..............154
vii

11. Graph showing specific conductance as a function of depth of well screen 

below land surface for groundwater samples from wells in the Woodbury study 

area, and from selected wells elsewhere in the Pomperaug and Hartford 

Basins, Connecticut ...................................................................................................................50

12. Diagram showing distribution of (A) pH, and (B) bicarbonate concentrations in 

groundwater samples from well screens in the (1) shallow parts of the glacial 

aquifer, greater than 3 meters above bedrock, (2) deep glacial aquifer, less than 

3 meters above bedrock, (3) shallow bedrock, less than 30 meters below bedrock 

surface, and (4) deep bedrock, greater than 30 meters below bedrock surface in 

the study area, Woodbury, Connecticut .................................................................................62

13. Piper diagram showing the percentage of total equivalents of major cations and 

anions in groundwater samples from wells in the Woodbury study area, and from 

selected wells elsewhere in the Pomperaug and Hartford Basins, Connecticut............63

14. Diagram showing concentrations of (A) magnesium as a function of calcium, and 

(B) chloride as a function of sodium, in groundwater samples from wells in the 

Woodbury study area, and from selected wells elsewhere in the Pomperaug and 

Hartford Basins, Connecticut ...................................................................................................64

15. Graph showing concentrations of (A) magnesium as a function of calcium, and 

(B) chloride as a function of sodium, in groundwater samples from wells in the 

Woodbury study area, and from selected wells elsewhere in the Pomperaug and 

Hartford Basins, Connecticut ...................................................................................................67

16. Graph showing concentrations of chloride as a function of chloride:bromide 

mass concentration ratios in samples collected in the Woodbury study area, 

Connecticut, and in other studies, together with mixing lines between designated 

end points, dilute groundwater, halite, sewage, and seawater..........................................69

17. Graph showing concentrations of nitrate plus nitrite as a function of 

chloride/bromide mass concentration ratios in groundwater samples in the 

Woodbury study area, and from selected wells elsewhere in the Pomperaug and 

Hartford Basins, Connecticut. Symbols are color coded for the estimated relative 

dissolved organic carbon (DOC) source and strength.........................................................74

18. Graph showing concentration of nitrate plus nitrite as a function of (A) well depth, 

and (B) concentration of dissolved organic carbon, in groundwater samples from 

wells in the Woodbury study area, and from selected wells elsewhere in the 

Pomperaug and Hartford Basins, Connecticut. Symbols are color coded for the 

estimated relative dissolved organic carbon (DOC) source and strength........................75

19. Diagram showing hydrogeologic sections showing medians, and selected ranges, 

of dissolved oxygen concentrations in groundwater samples from wells in the 

study area, Woodbury, Connecticut........................................................................................78

20. Graph showing concentrations of dissolved organic carbon (DOC) as a function 

of the concentration of electron acceptor indicators, including dissolved 

(A) oxygen, (B) nitrate plus nitrite, (C) manganese, (D) iron, (E) sulfate, and 

(F) hydrogen sulfide, in groundwater samples from wells in the study area, 

Woodbury, Connecticut .............................................................................................................79

21. Diagram showing distributions of concentrations of (A) dissolved organic carbon 

(DOC) and nitrate plus nitrite, and (B) dissolved boron (B) and manganese (Mn), in 

groundwater samples from wells in relation to the group of wells (1) not apparently 

affected by abundant natural organic matter or septic-system leachate 

(background), (2) affected primarily by abundant natural organic matter, and 

(3) affected primarily by septic-system leachate in the Woodbury study area ...............80
viii

22. Graph showing concentrations of dissolved (A) arsenic, (B) uranium, 

(C) radium-226, (D) radium-228, and (E) radon-222 in groundwater samples from 

wells as a function of distance from the well screen to the bedrock interface in 

the Woodbury study area, and from selected wells elsewhere in the Pomperaug 

and Hartford Basins, Connecticut............................................................................................82

23. Graph showing concentrations of dissolved arsenic as a function of (A) dissolved 

oxygen (DO), and (B) dissolved organic carbon (DOC), and concentrations of 

dissolved uranium as a function of (C) pH, and (D) bicarbonate in groundwater 

samples from wells in the Woodbury study area, and from selected wells 

elsewhere in the Pomperaug and Hartford Basins, Connecticut.......................................83

24. Graph showing dissolved concentrations of (A) strontium as a function of 

vanadium, and (B) boron as a function of cobalt, in groundwater samples from 

wells in the Woodbury study area, and from selected wells elsewhere in the 

Pomperaug and Hartford Basins, Connecticut......................................................................85

25. Graph showing (A) isotope values of delta oxygen-18 as a function of delta hydrogen-2 

for samples of groundwater and surface water, and (B) concentrations 

of dissolved sulfate as a function of delta sulfur-34 of sulfate for samples of 

groundwater, collected in the Woodbury study area, and from selected wells 

elsewhere in the Pomperaug and Hartford Basins, Connecticut.......................................87

26. Graph showing (A) delta nitrogen-15 as a function of delta oxygen-18 values, and 

(B) initial nitrate in recharge as a function of initial delta nitrogen-15 values in 

recharge, corrected for denitrification ...................................................................................89

27. Diagram showing concentrations of (A) the 20 most frequently detected volatile 

organic compounds, and (B) the seven most frequently detected pesticides, in

groundwater samples from each well site in the Woodbury study area, and from

selected wells elsewhere in the Pomperaug Basin, Connecticut....................................108

28. Graph showing (A) apparent groundwater age as a function of estimated 

groundwater recharge temperature, (B) apparent groundwater age as a function 

of terrigenic helium-4 (4He) percentage, and (C) the tritium/initial tritium (3H/3H(0)) 

concentration ratio plotted as a function of concentrations of helium-3 (3H), with 

modeled curves for various groundwater age distributions for groundwater 

samples from wells in the study area, Woodbury, Connecticut .......................................111

29. Graph showing (A) the tritium/initial tritium (3H/3H(0)) concentrations as a 

function of sulfur hexafluoride (SF6) concentrations, with modeled curves for 

various groundwater age distributions, and (B) sulfur hexafluoride (SF6) 

concentrations as a function of terrigenic helium-4 (4He) concentrations, in 

groundwater samples from wells in the study area, Woodbury, Connecticut...............116

30. Graph showing average simulated mean traveltimes of groundwater to wells 

based on particles in MODPATH as a function of the number of volatile organic 

compounds (VOCs) detected in groundwater samples from wells in the study 

area, Woodbury, Connecticut.................................................................................................117

31. Graph showing apparent groundwater age as a function of the (A) silica 

saturation index and (B) calcite saturation index, in groundwater samples from 

wells in the study area, Woodbury, Connecticut.................................................................118
ix

Tables

1. Data on the construction of wells in the Woodbury study area, and in selected

wells elsewhere in the Pomperaug and Hartford Basins, Connecticut ............................10

2. Classes of water-quality chemical characteristics and constituents measured in

water samples from the Woodbury, Connecticut, study area for the flow-path,

source-well, and stream-sampling analyte schedules, October 2002 to July 2006.........17

3. Relative mineralogical abundances, based on x-ray diffraction (XRD), of core

samples from boreholes in the Woodbury, Connecticut, study area, 2003–04.................26

4. Mineralogy of slightly magnetic and nonmagnetic heavy-mineral separates based

on analysis by petrography and spectra of aquifer material from boreholes in the

study area, Woodbury, Connecticut, 2003–04........................................................................27

5. Selected constituents in acid extractions and organic carbon, and analysis of

bulk density and pore-water constituents of aquifer material from boreholes in

the study area, Woodbury, Connecticut, 2003–04 .................................................................28

6. Results of adsorption experiments on aquifer material sampled in the study area,

including (A) the pH, bicarbonate, and surface sorption site concentrations for

arsenic (V) and uranium (VI), and (B) equilibrium constants for PHREEQC model of

adsorption using experimental data........................................................................................32

7. General chemical characteristics and concentrations of major elements,

nutrients, dissolved organic carbon, and ultraviolet absorbance in groundwater

samples from wells in the Woodbury study area (2002–06), and from selected

wells elsewhere in the Pomperaug and Hartford Basins, Connecticut ............................36

8. Dissolved concentrations of trace elements, stable isotope ratios, and

radionuclides in groundwater samples from wells in the Woodbury, Connecticut

(2002–06), study area, and from selected wells elsewhere in the Pomperaug and

Hartford Basins ...........................................................................................................................50

9. Traveltime in years and percentage of particles in each land-use type for

flow-tracking particles backtracked from monitoring-well screens to the water

table, simulated with MODPATH (Starn and Brown, 2007)..................................................65

10. Summary of chloride:bromide mass ratios and concentrations of selected

constituents related to road salt (halite) and septic-system leachate in samples

from previous studies, and for groundwater samples from selected wells in the

Woodbury study area and elsewhere in the Pomperaug Basin, Connecticut ................70

11. Summary of recharge temperatures determined from dissolved gas

concentrations in groundwater samples from wells in the study area, Woodbury,

Connecticut, 2003–05 .................................................................................................................90

12. Concentrations of volatile organic compounds and pesticides detected in

groundwater samples from wells in the Woodbury study area, and from selected

wells elsewhere in the Pomperaug Basin, Connecticut, 2002–05......................................93

13. Statistical summary of volatile organic compounds and pesticides detected in

groundwater samples from wells in the study area, Woodbury, Connecticut,

2002–05 .......................................................................................................................................106
x

14. Summary of tritium/helium-3 (3H/3He), sulfur hexachloride (SF6), and

chlorofluorocarbons (CFC) groundwater age tracer data and apparent ages

using a piston flow model for water samples in the study area, Woodbury,

Connecticut, 2003–2005 ...........................................................................................................113

15. Summary of major geochemical sources and the indicative chemical

characteristics in the aquifer system of the study area, Woodbury, Connecticut........119

16. Results of inverse geochemical modeling with PHREEQC to determine the relative

contribution of high-sulfate groundwater from underlying fractured bedrock,

represented by a sample from WY106, to the glacial aquifer, represented by a

sample from WY100, in the study area, Woodbury, Connecticut......................................120

17. Results of inverse geochemical modeling with PHREEQC using delta sulfur-34 to

determine the relative contribution of groundwater to PSW-1 from various depths 

represented by adjacent monitoring wells WY102, 100, 101, and 106, in the study 

area, Woodbury, Connecticut.................................................................................................122
xi

Conversion Factors, Abbreviations, and Datums

Multiply By To obtain

Length

centimeter (cm) 0.3937 inch (in.)

millimeter (mm) 0.03937 inch (in.)

meter (m) 3.281 foot (ft) 

kilometer (km) 0.6214 mile (mi)

Area

square kilometer (km2) 247.1 acre

square kilometer (km2) 0.3861 square mile (mi2)

hectare (ha) 2.471 acre

Volume

liter (L) 0.2642 gallon (gal)

cubic meter (m3) 264.2 gallon (gal) 

cubic centimeter 0.06102 cubic inch (in3) 

Flow rate

liter per second (L/s) 15.85 gallon per minute (gal/min) 

cubic meter per day (m3/d) 264.2 gallon per day (gal/d) 

millimeter per year (mm/yr) 0.03937 inch per year (in/yr) 

Mass

gram (g) 0.03527 ounce, avoirdupois (oz)

kilogram (kg) 2.205 pound avoirdupois (lb)

metric ton per year 1.102 ton per year (ton/yr) 

picomoles per kilogram (pmol/kg) 1 x 10-9 moles per kilogram

femtomoles per kilogram (femtomol/kg) 1 x 10-12 moles per kilogram

Density

pound per cubic foot (lb/ft3) 0.01602 gram per cubic centimeter (g/cm3)

Radioactivity

becquerel per liter (Bq/L) 27.027 picocurie per liter (pCi/L) 

tritium units (TU) 3.19 picocurie per liter (pCi/L)

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

°F=(1.8×°C)+32

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

°C=(°F-32)/1.8

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.
xii

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

(mg/L), micrograms per liter (μg/L) or parts per billion (ppb), picograms per liter (pg/L), molality 

or moles per liter (M), milligrams per kilogram (mg/kg), picomoles per kilogram (pmol/kg), or 

femtomoles per kilogram (femtomol/kg), or cubic centimeters per liter at standard temperature 

and pressure (cm3STP/L).

List of Abbreviations

AMCL Alternative maximum contaminant level

CONN Connecticut, Housatonic, and Thames River Basins

E Estimated concentration

EM Electromagnetic 

HPFM Heat-Pulse Flowmeter 

MAS Major Aquifer Study

MCL Maximum contaminant level

MRL Minimum reporting level

MWL Meteoric water line

NAWQA National Water Quality Assessment Program

NWQL National Water Quality Laboratory

pCi/L picocuries per liter 

RPM Revolutions per minute

SWQA Source Water Quality Assessment

TANC Transport of Anthropogenic and Natural Contaminants to public-supply wells

TEAP Terminal electron acceptor processes

USEPA U.S. Environmental Protection Agency

USGS U.S. Geological Survey

VOC Volatile organic compound

VCDT Vienna Canyon Diablo Troilite

VPDB Vienna Pee Dee Belemnite

VSMOW Vienna Standard Mean Ocean Water

ETBE ethyl-tert-butyl ether

BTEX benzene, toluene, ethylbenzene, and xylene

MTBE methyl-tert-butyl ether

TAME tert-amyl methyl ether

1,1-DCE 1,1-dichloroethene

1,2-DCE cis-1,2-dichloroethene

DCA 1,1-dichloroethane

TCE trichloroethene

TCA 1,1,1-trichloroethane

PCE perchloroethene or tetrachloroethene

CFC-11 trichlorofluoromethane

CFC-12 dichlorodifluoromethane

CFC-113 1,1,2-trichlorotrifluoroethane

p-DCB 1,4-dichlorobenzene

Ag silver

Al aluminum

Ar argon
xiii

As arsenic B boron

Ba barium

Be beryllium

Br bromine

Br

- bromide

C carbon

Ca calcium

CaCO

3 calcium carbonate 

Cd cadmium

CH

4 methane

Co cobalt

CO

2 carbon dioxide

Cr chromium

Cu copper

DO or O

2 dissolved oxygen

DIC dissolved inorganic carbon

DOC dissolved organic carbon F- fluoride

Fe iron

FeS

2 iron disulfide

H hydrogen 2H deuterium, or hydrogen-2 3H tritium H2

S hydrogen sulfide

H

2

S, HS

- hydrogen sulfide species

He helium 3

He helium-3 or tritium

4

He helium-4

HCl hydrochloric acid

HCO

3

- bicarbonate

HNO

3 nitric acid

H

3

PO

4 phosphoric acid

K potassium

Li lithium

Mo molybdenum

Mg magnesium

Mn manganese N nitrogen

Na sodium

Ne neon

Ni nickel

NH

4

+ ammonium

NO

2

- nitrite

NO

3

- nitrate
xiv

O oxygen P phosphorus

Pb lead

PO

4

3

- phosphate

Ra radium

Rn radon S sulfur

SF

6 sulfur hexafluoride

Se selenium

SnCl

2

 tin (II) chloride

SO

4

2- sulfate

SiO

2 silica

Sr strontium

Tl thallium

TU tritium unit U uranium V vanadium

Zn zinc
Aquifer Chemistry and Transport Processes in the Zone 

of Contribution to a Public-Supply Well in Woodbury, 

Connecticut, 2002–06

By Craig J. Brown, J. Jeffrey Starn, Kenneth G. Stollenwerk, Remo A. Mondazzi, and Thomas J. Trombley

Abstract 

A glacial aquifer system in Woodbury, Connecticut, was 

studied to identify factors that affect the groundwater quality 

in the zone of contribution to a community public-supply 

well. Water samples were collected during 2002–06 from the 

public-supply well and from 35 monitoring wells in glacial 

stratified deposits, glacial till, and fractured bedrock. The 

glacial aquifer is vulnerable to contamination from a variety 

of sources due to the short groundwater residence times and 

the urban land use in the contributing recharge area to the 

public-supply well. The distribution and concentrations of 

pH, major and trace elements, stable isotope ratios, recharge 

temperatures, dissolved organic carbon (DOC), and volatile 

organic compounds (VOCs), and the oxidation-reduction 

(redox) conditions, were used to identify recharge source 

areas, aquifer source material, anthropogenic sources, 

chemical processes, and groundwater-flow paths from 

recharge areas to the public-supply well, PSW-1. 

The major chemical sources to groundwater and 

the tracers or conditions used to identify them and their 

processes throughout the aquifer system include (1) bedrock 

and glacial stratified deposits and till, characterized by 

high pH and concentrations of sulfate (SO4

2−), bicarbonate, 

uranium (U), radon-222, and arsenic (As) relative to those 

of other wells, reducing redox conditions, enriched delta 

sulfur-34 (d34S) and delta carbon-13 (d13C) values, depleted 

delta oxygen-18 (d18O) and delta deuterium (dD) values, 

calcite near saturation, low recharge temperatures, and 

groundwater ages of more than about 9 years; (2) natural 

organic matter, either in sediments or in an upgradient 

riparian zone, characterized by high concentrations of DOC 

or manganese (Mn), low concentrations of dissolved oxygen 

(DO) and nitrate (NO3

−

), enriched d34S values, and depleted 

d18O and dD values; (3) road salt (halite), characterized 

by high concentrations of sodium (Na), chloride (Cl−), 

and calcium (Ca), and indicative chloride/bromide (Cl:Br) 

mass concentration ratios; (4) septic-system leachate, 

characterized by high concentrations of NO3

−

, DOC, Na, 

Cl−, Ca, and boron (B), delta nitrogen-15 (d 15N) and d18O 

values, and indicative Cl:Br ratios; (5) organic solvent 

spills, characterized by detections of perchloroethene (PCE), 

trichloroethene (TCE), and 1,1-dichloroethene (1,1-DCE); 

(6) gasoline station spills, characterized by detections of 

fuel oxygenates and occasionally benzene; and (7) surfacewater leakage, characterized by enriched d18O and dD values 

and sometimes high DOC and Mn-reducing conditions. 

Evaluation of Cl− concentrations and Cl:Br ratios indicates 

that most samples were composed of mixtures of groundwater 

and some component of road salt or septic-system leachate. 

Leachate from septic-tank drainfields can cause locally 

anoxic conditions with NO3

−

 concentrations of as much as 

19 milligrams per liter (mg/L as N) and may provide up to 

15 percent of the nitrogen in water from well PSW-1, based on 

mixing calculations with d15N of NO3

−

.

Most of the water that contributes to PSW-1 is young 

(less than 7 years) and derived from the glacial stratified 

deposits. Typically, groundwater is oxic, but localized 

reducing zones that result from abundances of organic 

matter can affect the mobilization of trace elements and the 

degradation of VOCs. Groundwater from fractured bedrock 

beneath the valley bottom, which is old (more than 50 years), 

and reflects a Mn-reducing to methanic redox environment, 

constitutes as much as 6 percent of water samples collected 

from monitoring wells screened at the bottom of the glacial 

aquifer. Dissolved As and U concentrations generally are 

near the minimum reporting level (MRL) (0.2 micrograms 

per liter or μg/L and 0.04 μg/L, respectively), but water 

from a few wells screened in glacial deposits, likely derived 

from underlying organic-rich Mesozoic rocks, contain As 

concentrations up to 7 μg/L. At one location, concentrations 

of As and U were high in sediment sample extractions, and 

the concentration of dissolved As also was above background 

levels in the water sample from the well. The relatively low 

concentrations of U in water samples from this well are 

consistent with the low mobility of U under iron- (Fe) or 

Mn-reducing conditions. Experimental data for adsorption 

batch reactor experiments were modeled using PHREEQC 

with the generalized two-layer surface complexation model 
2 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

to determine adsorption reactions. A substantial amount of 

As and U was adsorbed onto four different glacial stratified 

deposit samples, whereas much less was adsorbed onto the 

sample of glacial till. In fact, there was a net release of U(VI) 

to solution by the glacial till, which may result from uranylcarbonate complexes that inhibit U adsorption, although it 

is possible that there was some U(VI) co-precipitated with 

carbonate minerals in the sediment that was released during 

the adsorption experiment. The net release of U(VI) from 

glacial till sediments experiments is consistent with higher 

concentrations of U in water samples from wells screened in 

deep glacial deposits and in bedrock than those screened in 

shallow, carbonate-poor glacial deposits. Radon-222 (222Rn) 

activities in groundwater samples from the Woodbury study 

area ranged from 490 to 13,000 picocuries per liter (pCi/L), 

and all exceeded the proposed maximum contaminant level 

(MCL) of 300 pCi/L. The median 222Rn activity of 1,100 pCi/L 

for glacial wells was greater than the median of 440 pCi/L for 

glacial aquifers of the northeastern United States, and appears 

to result from an abundant but relatively immobile mass of U 

and radium-226 (226Ra) on aquifer sediment surfaces.

Groundwater age plotted as a function of the number 

of VOC detections indicates that VOC occurrences are 

related to short groundwater traveltimes, and therefore, 

young groundwater is more vulnerable to contamination 

than older groundwater. VOCs were detected at 32 of the 36 

wells sampled for this study. Locally high concentrations of 

gasoline oxygenates (methyl-tert-butyl ether, or MTBE) and 

chlorinated solvents (PCE, TCE, and 1,1,1-trichloroethane or 

TCA), and low concentrations of disinfection byproducts were 

detected in groundwater samples from several wells. Eleven 

VOCs were detected in untreated water from PSW-1—PCE, 

TCA, TCE, 1,1-dichloroethane (DCA), cis-1,2-dichloroethene 

(cis-1,2-DCE), 1,1-dichloroethene (1,1-DCE), MTBE, 

tert-amyl methyl ether (TAME), ethyl-tert-butyl ether (ETBE), 

1,1,2-trichlorotrifluoroethane (CFC-113), and chloroform. 

Concentrations of TCE in untreated groundwater sampled 

from PSW-1 frequently exceeded the maximum contaminant 

level of 5 μg/L. Most VOCs were detected in water sampled 

from shallow or intermediate depths of the glacial aquifer 

and were associated with commercial- and light-industrial 

development. MTBE was detected in 50 percent of the wells 

and was the most frequently detected compound. Chloroform 

was found in 49 percent of wells and was the second most 

frequently detected compound, but concentrations in samples 

from all but two of the wells sites were less than the MRL. The 

sources of chloroform were attributed to the use of chlorinated 

drinking water and the associated recharge from septictank drainfields or lawn irrigation, or for well disinfection. 

Chlorinated solvents were the third most frequently detected 

group of compounds; two of them—TCE and PCE—exceeded 

health-based screening concentrations. PCE was detected in 

42 percent of wells, and concentrations were highest (up to 

11 μg/L) in samples from several wells downgradient from 

the commercial development. TCE was found in 33 percent 

of wells, at concentrations as high as 25 μg/L. Pesticides were 

detected at low concentrations in few wells and this reflects 

the small amount of agricultural land use in the study area. 

Atrazine, prometon, simazine, and fipronil were detected at 

concentrations near or less than the MRL in monitoring wells 

downgradient from urban areas.

Introduction 

The presence of contaminants and other constituents of 

concern in aquifers throughout the United States has prompted 

recent interest in the study of public-supply well vulnerability 

(Reilly and Pollock, 1993; Kauffman and others, 2001). 

Anthropogenic contaminants, such as solvents and other 

VOCs (Zogorski and others, 2006), pesticides (Gilliom and 

others, 2006), and NO3

−

 (Nolan and others, 1998) have been 

detected at low concentrations in water from public-supply 

wells across the United States. In addition, recent studies 

have found that elevated concentrations (above background) 

of naturally occurring contaminants, such as U and As, also 

are present in wells that supply drinking water (Focazio and 

others, 1999; Welch and others, 2000; Brown and others, 

2007; Ayotte and others, 2007). 

The glacial aquifer system is the largest principal aquifer 

in the United States, by areal extent and withdrawals for 

public supply (Warner and Arnold, 2006). The vulnerability 

of public-supply wells generally is high in these areas because 

of the typically young age of water and the high permeability 

of the glacial deposits. Urban areas that overlie valley-fill 

glacial aquifers in the northeast encompass anthropogenic 

sources or activities that may contribute potential sources 

of contaminants, such as underground storage tanks, septictank drainfields, chemical spills, application of road salt, 

stormwater-retention ponds, and fertilizers applied to lawns 

and golf courses. Furthermore, geochemical conditions 

may facilitate the mobilization and transport of natural 

contaminants or constituents of concern in the subsurface that 

can affect water supplies in some aquifer settings. Protection 

of groundwater used for public supply requires monitoring and 

an understanding of the chemical and hydraulic mechanisms 

that affect groundwater quality.

In 2001, the U.S. Geological Survey (USGS) National 

Water Quality Assessment (NAWQA) Program began a 

second cycle of water-quality investigations with in-depth 

analyses of processes, which are needed to improve the 

understanding of the mechanisms for distribution and 

mobilization of contaminants and their transport to publicsupply wells in representative aquifers and geographic areas. 

To better understand the factors that control the vulnerability 

of public-supply wells to anthropogenic and natural 

contaminants, a study of the Transport of Anthropogenic and 

Natural Contaminants (TANC) to public-supply wells was 

begun in 2001 (Eberts and others, 2005), using consistent 

and systematic data collected in a variety of principal aquifer 

settings in the United States. Seven regional studies were 
Introduction 3

conducted in a range of settings using regional groundwaterflow models and water-quality data from public-supply wells 

(Paschke and others, 2007). More detailed, local-scale (less 

than 100 km2) studies then were conducted in four of these 

areas, including the Pomperaug glacial aquifer in Woodbury, 

Connecticut, (the focus of this report) in the Connecticut, 

Housatonic, and Thames River Basins (CONN). Other 

studies were conducted in the Upper Floridan aquifer in 

Tampa, Florida, the High Plains aquifer in York, Nebraska, 

and the Central Valley aquifer in the eastern San Joaquin 

Valley near Modesto, California. Contributing-area flow 

paths were selected to cross a gradient of land uses and 

terminate at a public-supply well. The flow paths typify the 

hydrogeology, water chemistry, and sources of contaminants 

for the respective water-supply aquifer. Flow paths vary in 

length from about 5 to 8 km. A companion report describes 

the calibrated groundwater-flow model used to simulate the 

flow of water to the public-supply well in the delineated 

groundwater contributing area (Starn and Brown, 2007). 

Together, the reports serve as a foundation for comparing 

results among the Woodbury study area and other NAWQA 

TANC local-scale study areas.

Purpose and Scope

The purpose of this report is to describe the factors 

that affect the vulnerability of a public-supply well 

(PSW-1) to contamination in a glacial aquifer system in 

Woodbury, Connecticut. The report presents information 

on the hydrogeologic setting, aquifer geochemistry, and 

the occurrence and distribution of chemical constituents 

and characteristics and groundwater ages in the zone of 

contribution to the public-supply well (PSW-1). A description 

of the design of the local monitoring well network and 

methods of data collection and analysis are included. This 

report describes general water-chemistry characteristics, such 

as oxidation-reduction (redox) conditions, pH, and water 

types, in 35 monitoring wells and PSW-1. The interpretative 

steps for estimating groundwater ages using atmospheric 

tracers are described, along with the distribution of the 

interpreted groundwater ages. The occurrence and distribution 

of selected inorganic and organic chemical constituents 

are described to help assess groundwater recharge and 

discharge patterns and pathways, and the occurrence and 

distribution of contaminant point sources. The transport 

of anthropogenic contaminants and naturally occurring 

constituents of concern to supply wells in the TANC study 

are assessed. Concentrations of natural and anthropogenic 

and natural constituents are compared to U.S. Environmental 

Protection Agency (USEPA) Maximum Contaminant Levels 

(MCLs) to evaluate the potential relevance of the findings to 

human health.

Description of Study Area

The TANC study area in Connecticut is within the CONN 

Study Unit of NAWQA (fig. 1) and on the eastern side of the 

NAWQA Glacial Aquifers Principal Aquifer area (Warner and 

Arnold, 2006). The Pomperaug aquifer system underlies the 

145-km2 watershed drained by the Pomperaug River, its major 

tributaries—the Nonewaug and Weekeepeemee Rivers—and 

several smaller streams (Starn and Brown, 2007). Landsurface altitudes range from about 70 m at the flood plain of 

the Pomperaug River to about 215 m in the eastern uplands 

(in this report, altitudes are referenced to the North American 

Vertical Datum of 1988). The local-scale study area (herein 

described as “study area”) is a modeled part of the Pomperaug 

aquifer system that includes the zone of contribution to one 

public-supply well, PSW-1 (figs. 2 and 3). Advective particle 

tracking was used by Starn and Brown (2007) to estimate 

the contributing recharge area to PSW-1 (fig. 2), although 

uncertainty analysis showed that some recharge outside the 

designated source area could contribute to PSW-1.

The population of Woodbury increased 2.5-fold from 

1950 to 2000; the population in 2000 was 9,198, or about one 

person per hectare (U.S. Census Bureau, 2000). From 1985 

to 2002, 8 percent of the contributing recharge area to PSW-1 

changed from agricultural and undeveloped land to developed 

land (fig. 4A; Starn and Brown, 2007). Agricultural lands, 

which generally are represented by “agriculture and grasses” 

in figure 4A, make up only a small percentage of the study 

area and are located mostly in the uplands. Outside of the 

study area, agricultural products in the valley bottom include 

some silage corn, hay, and ornamental plants. Industrial land 

is limited in extent and includes small, high-tech industries. 

Upland areas are largely forested with scattered residences 

on 0.4 hectare or larger lots. Residential and commercial 

development has been, and still is, greater in the valleys than 

the uplands and tends to overlie the glacial aquifer; however, 

the percentage of residential development in the uplands 

continues to increase. 

Most water used for public supply is pumped from wells 

completed in valley-fill glacial deposits, including PSW-1, 

although four condominium complexes obtain water from 

wells completed in bedrock. Numerous residents, mostly in 

the uplands, obtain water from private wells for domestic use, 

including lawn irrigation. All residences and businesses are 

unsewered and generally rely on septic-tank drainfields to 

dispose of human waste. The term “septic-tank drainfields” 

is used in this report to describe a septic tank that collects 

the solids, with a pipe overflow that leads to a series of drain 

pipes called a leachfield. The septic-tank drainfield density for 

the 59.9 hectare (ha) contributing recharge area, as estimated 

from the approximately 42 septic systems in 2005 (Starn 

and Brown, 2007), was 0.7 sites per ha (70 sites per km2). 

The population in the contributing recharge area to PSW-1 

remained low until about 1950, when the rate of growth 

increased. Based on land records in the Town of Woodbury, 

and assuming that each house has a septic-tank drainfield, the 
4 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

SB120

WY65

F344

A318

P117

S401

S400

B403

S0110 BA104

NBR118

Pomperaug

River 

Watershed

GLACIAL STRATIFIED DEPOSITS

Boundary of the National Water-Quality

Assessment Connecticut, Housatonic, and 

Thames River Basins Study Unit

VERMONT

MASSACHUSETTS

RHODE

ISLAND

CONNECTICUT

NEW

HAMPSHIRE

Regionalscale

study

area

Local-scale

study area

73°20' 73°15' 73°10' 73°05'

41°40'

41°35'

41°30'

41°25'

Southbury

Woodbury

Litchfield

PomperaugR vi e r

South Broo k

Weekeepeemee River

Nonewaug

River

SB118

66

67

PSW-1

11

68

SB119

SB121

SB120

WY65

SB112

EXPLANATION

Local-scale TANC study area

Regional-scale TANC study area

Forested land-use well and identifier

Major aquifer-study well and identifier

Local-scale TANC public-supply well and identifier

11 Regional-scale TANC public-supply well and identifier

PSW-1

40 KILOMETERS

20 MILES

0 20

0 10

74° 72° 70°

42°

44°

Base from U. S. Geological Survey, 1:24,000, 1969 to 1984,

Projection: Connecticut State Plane Feet

Glacial Stratified Deposits from Soller and Packard (1998), 1:1,000,000

0 1 2 3 4 KILOMETERS

0 1 2 3 4 MILES

Figure 1. Locations of the regional- and local-scale areas for the study of the Transport of Anthropogenic and 

Natural Contaminants (TANC) to public-supply wells, monitoring and supply wells used for this study in Connecticut, 

and the glacial stratified deposits in the Connecticut, Housatonic, and Thames River Basins (CONN) study unit and 

surrounding area.
Introduction 5

250

550

500

450 400

350

200

300

600

650

700

190

180

170

160

150

100

750

800

850 750

350

400

750

800

450

750

250

500

450

400

550

550

350

700

750

350

350

500

350

300

500

750

450

400

350

500

150

750

700

South Brook

Pomperaug River

WY96

WY97

WY94

WY93

WY90

WY89

WY81

WY95 WY82

WY99

WY98

WY92

WY91

WY86

WY65

WY83

WY53

WY80

WY87

WY79

WY78

WY77

WY76

WY75

WY85

WY84

WY35

WY88

WY102

WY100

WY101

WY103

WY106

WY71

WY70

WY69

WY104

WY74

WY73

WY72

WY105

B'

A'

A

B

D'

C'

PSW-1 C D

EXPLANATION

Deltaic deposits

Deltaic over fluvial deposits

Fluvial deposits

Compact till

Altitude, top of bedrock 

10

50

Lines of geologic section

Model contributing recharge area boundary

Model boundary

Monitoring well and identifier

Public-supply well and identifier

Well sampled as part of a previous study and

well identifier

WY86

WY65

WY53

Geohydrologic units

Lake-bottom deposits

Fluvial deposits over compact till

Noncompact till

Major aquifer-study well and identifier (cycle II)

A A'

PSW-1

41°32'

73°13'

0 0.5 1 MILES

0 0.5 1 KILOMETERS

41°31'

73°12' 73°11'

Base from Connecticut Department of Environmental Protection, 1994, 1:24,000

Projection: State Plane Feet, Zone 3526

Geology modified from Stone and others (2005),

Pessl (1970), and Rodgers (1985)

10-foot contour interval, in feet above the

North American Vertical Datum of 1988 

50-foot contour interval, in feet above the

North American Vertical Datum of 1988

Figure 2. Modeled area showing wells, geologic materials, altitude of top of bedrock, lines of hydrogeologic section, and 

the contributing recharge area to the public-supply well (PSW-1) in the study area, Woodbury, Connecticut. 
6 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

Figure 3. Hydrogeologic sections showing locations and identifiers of wells installed in the study area, Woodbury, Connecticut.

Glacial stratified

deposits

Glacial till

deposits

Paleozoic

(crystalline)

bedrock

Triassic and Jurassic

bedrock

TRIASSIC AND JURASSIC

BEDROCK

A A'

WY102

WY100

WY101

WY103

WY106

WY74

WY73

WY72

WY105

WY96

WY97

FAULT

WY71

WY70

WY69

WY104 WY87WY86

WY35

WY88

60

100

80

120

140

160

METERS

METERS

METERS

METERS

40

20

B B'

C C' D' Pomperaug RiverD

Glacial stratified

deposits

Glacial stratified

deposits

Glacial till

deposits

Glacial till

deposits

Glacial till

deposits

40

60

80

20

100

120

50

60

70

80

90

Triassic and Jurassic

bedrock

Triassic and Jurassic

bedrock Triassic and

Jurassic

bedrock

ALTITUDE ABOVE NAVD 88, IN METERS

EXPLANATION

Monitoring well, screen, and identifier

Continuously screened well

Production well and identifier

Water table

WY85

WY84

WY78

WY99

WY98

WY77

WY80

South Brook

Glacial stratified

deposits

WY85

WY84

WY90

WY89

WY94

WY93

South Brook

South Brook

WY78

WY77

WY99

WY98

WY80

WY81

WY82

WY90

WY89

WY92

WY91

WY78

WY77

WY95

WY83

Multilevel

samplers:

WY92f

WY92e

WY92c South Brook

Unnamed Tributary

WY71

WY70

WY69

WY104

Glacial stratified

deposits

WY102

WY100

WY101

WY103

WY106

WY74

WY73

WY72

WY105

WY76

WY75

WY83

WY79

WY92

WY91

revi Rguarep moP

Unnamed Tributary

Multilevel

samplers:

WY92f

WY92e

WY92c

WY35

WY88

WY81

WY82

0 0.25 MILES

0 250 METERS 

0 0.25 MILES

0 250 METERS 

VERTICAL SCALE GREATLY EXAGGERATED 

0 0.25 MILES

0 250 METERS 

0 0.25 MILES

0 250 METERS 50

60

70

80

90

Glacial till

deposits

Glacial stratified

deposits

PSW-1

PSW-1

PSW-1

WY78
Introduction 7

Figure 4. (A) Land use/land cover for 2002 (Center for Land Use Education And Research, 2003), with Significant Potential Contaminant 

Sources (SPCSs; Connecticut Department of Public Health, 2007), simulated paths of flow to monitoring wells, and the modeled 

contributing recharge area to well PSW-1 based on particle tracking with MODPATH (Pollack, 1994), and (B) methyl-tert-butyl ether 

(MTBE) concentrations, in parts per billion (ppb), in samples collected September 8, 2004, from wells of shallow (less than 6 meters) and 

intermediate (about 9 meters) depths (Sovereign Consulting, Inc., 2004a), Woodbury, Connecticut.

WY74

WY73

WY72

WY105

WY71

WY70

WY69

WY104

WY85

WY84

WY78

WY77

WY99

WY98

WY80

WY94

WY93

WY102

WY100

WY101

WY103

WY106

WY95

WY95

WY53

WY53

WY76

WY75

WY92

WY91

73°13' 73°12' 73°11'

41°32'

41°31'

2002 Land cover

Developed

Turf and grass

Other grasses and agriculture

Deciduous forest

Coniferous forest

Water

Forested wetland

Nonforested wetland

Barren

Production well and identifier

PSW-1 Production well and identifier

USGS monitoring well (this study) and identifier

Non-USGS recovery well and well identifier

USGS monitoring well (previous study) and identifier

Land cover from Center for Land Use Education and Research,

The University of Connecticut, December, 2003 

Modeled area

Significant Potential Contaminant

Sources Facilities

Methyl-tert-butylether (MTBE) concentration contour,

depth less than 6 meters

MTBE concentration contour, depth equal to 9 meters

Boundary of contributing recharge area to PSW-1

NW19D

PSW-1

PSW-1

PSW-1 Monitoring well and simulated

path lines

Contributing recharge 

area to PSW-1

EXPLANATION

0 250 500 750 FEET

0 125 250 METERS

A

B EXPLANATION

Well sampled as part of a

previous study

100 ppb 1,000 ppb

10,000 ppb

100 ppb

1,000 ppb

10,000 ppb

Major aquifer-study well

and identifier (cycle II)

WY65

NW19D

0

0 0.5 1 KILOMETERS

0.75 MILES
8 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

number of drainfields in the contributing recharge area follows 

the general population trend. Water withdrawal records for 

PSW-1 show a slight increase in summer water use between 

1997 and 2001 (Starn and Brown, 2007) and likely is due to a 

small increase in population.

Several anthropogenic contaminant sources have been 

identified in the study area, including chlorinated solvent 

spills or leaks, an MTBE plume emanating from a gasoline 

station, leakage from septic-tank drainfields, chemical 

applications to lawns, and deicing salt from road runoff. 

The MTBE concentrations associated with the gasoline spill 

were mapped using data from both USGS and non-USGS 

monitoring wells (fig. 4B; Sovereign Consulting, Inc., 

2004a). Chlorinated solvents first observed in samples from 

PSW-1 in 1978 (Mazzaferro, 1986b) were associated with 

several light industrial or commercial properties in an area of 

businesses that is referred to herein as “the commercial area.” 

Facilities that have been identified as Significant Potential 

Contaminant Sources or SPCSs have been inventoried for the 

Connecticut Source Water Assessment Program (Connecticut 

Department of Public Health, 2007) and are abundant in 

the commercial area (fig. 4A). The SPCSs include sources 

associated with potentially regulated activities, such as usage 

and storage of hazardous materials, pesticides, and petroleum 

products by businesses. These businesses include some 

manufacturing plants, chemical wholesale storage, gasoline 

stations, dry cleaners, and furniture strippers. Groundwater 

from PSW-1 was treated by granular activated carbon (GAC) 

filtration since the late 1970s, after chlorinated solvents were 

found in groundwater, then by air stripping beginning in 2003.

Previous Investigations

The origin, petrology, and stratigraphy of Mesozoic 

sedimentary rocks and surrounding Paleozoic rocks within 

the study area are summarized by Burton and others (2005). 

Krynine (1950) provides detailed analysis of mineralogy 

and petrology in a study of the sedimentary rocks of the 

Hartford and Pomperaug Basins. Hubert and others (1978) 

and Weddle and Hubert (1983) developed a depositional 

model, based on petrologic and structural data, that shows 

the stratigraphic relationships between the Hartford and 

Pomperaug Basins. The glacial aquifer and overlying 

Holocene deposits are described in surficial materials 

maps (Pessl, 1970; Stone and others, 2005). Groundwater 

conditions in the Pomperaug River watershed have been 

described in several papers, as summarized in Starn and 

Brown (2007). Several recent NAWQA studies include 

wells in the Pomperaug River watershed (CONN-NAWQA 

website, http://ct.water.usgs.gov/nawqa/index.htm, July 

2006). The Groundwater Source Water-Quality Assessment 

(SWQA) study of 15 public-supply wells in the stratified 

glacial deposits of Connecticut was conducted to assess the 

quality of water from community water supplies, including 

nine wells in the Pomperaug River watershed area (Trombley 

and others, 2007). A groundwater-flow model was used to 

delineate the contributing area for these public-supply wells 

over a large area (128 km2) in the Pomperaug River watershed 

as part of the regional-scale TANC study (Lyford and others, 

2007). As part of the regional study, land use and contaminant 

point sources were delineated in the contributing areas of 

each supply well and compared to water-quality data from 

the public-supply well samples and from other previously 

obtained samples from other wells in the study area. As part 

of a NAWQA regional aquifer assessment study (referred to 

herein as major aquifer study or MAS; Lapham and others, 

2005) of the glacial aquifer in the Connecticut, Housatonic, 

and Thames River Basins study unit, two domestic wells 

were sampled in the Pomperaug Basin, including a well in 

Woodbury, in the northern part of the study area, and a well in 

Southbury, southwest of the study area. 

A study of the effects of land use on shallow groundwater 

quality in the Pomperaug and Pootatuck (located to the south) 

Basins (Grady and Weaver, 1989) showed that commercial/

industrial areas contained the most degraded groundwater 

quality. Residential areas had the highest concentrations of 

most major inorganic constituents and nutrients compared to 

other land use areas, and some shallow-groundwater samples 

contained several VOCs, including trichloroethene (TCE), 

1,1,1-trichloroethane (TCA), and perchloroethene (PCE), and 

pesticides, including 2,4-D, 2,4,5-T, and silvex. In agricultural 

areas, TCE and TCA were detected in groundwater samples, 

but no pesticides were found. Chloroform was detected widely 

in source waters from public-supply wells in western and 

west-central Connecticut and was attributed to a byproduct 

of disinfection during chlorination (Trombley and others, 

2007). Delineation and remediation of a gasoline spill to 

groundwater beneath the commercial area were conducted in 

2004 in response to the presence of several gasoline-related 

compounds in samples from PSW-1 (Sovereign Consulting, 

Inc., 2004a and b).

The groundwater chemistry in glacial and alluvial 

deposits in the New England, New York, and Pennsylvania 

areas is associated with the chemistry of the underlying 

bedrock (Rogers, 1989; Grady and Mullaney, 1998; Robinson 

and Ayotte, 2006). Grady and Mullaney (1998) found 

substantial differences in the groundwater chemistry of 

samples from shallow glacial wells in forested, undeveloped 

areas that overlie four different lithogeochemical types of 

bedrock in western New England. SO4

2− concentrations, 

for example, were greater in glacial deposits overlying 

Mesozoic rocks in the Hartford Basin defined as “arkosic” 

than in those overlying crystalline, calcareous, or carbonate 

bedrock. A study of 222Rn in bedrock wells in Connecticut 

indicated that concentrations are high (from 3,000 to more 

than 10,000 pCi/L) in some of the crystalline rocks in the 

uplands part of the Pomperaug River watershed (Thomas and 

others, 1988; Thomas and McHone, 1997). U concentrations 

can be high in groundwater from bedrock wells in some areas 

of Connecticut and have been associated with nephrotoxicity 

in a young child (Magdo and others, 2007). Concentrations 
Methods of Data Collection and Analysis 9

of As can be high in certain types of fractured bedrock in 

Connecticut (Brown and Chute, 2002) and may migrate to 

public-supply wells in adjacent glacial aquifers.

Methods of Data Collection 

and Analysis

This section describes the design of the monitoring-well 

network; the methods of drilling, coring, and installation of 

monitoring wells; the collection of aquifer material samples 

for characterizing lithology and mineralogy; the elemental and 

mineralogic analyses of sediment and rock data; geophysical 

methods; water-quality sampling and analyses; age dating 

of groundwater; methods of quality assurance; and data 

interpretation.

Design of Well Network

A single public-supply well, PSW-1, was selected for 

study of the sources and transport of contaminants based on 

the regional-scale TANC study for the Pomperaug aquifer 

system (figs. 2 and 3). PSW-1, which supplies water to 

Woodbury, was constructed in 1967 to a depth of 18.3 m with 

10-in.-diameter steel casing and a 4.6-m-long stainless-steel 

screen with 0.007-in. slots (table 1; fig. 5) (C.W. Lauman & 

Co., written commun., 1967).

The contributing recharge area to PSW-1, estimated 

using the regional model (Lyford and others, 2007), was used 

to determine locations for monitoring wells in the local-scale 

study. Monitoring-well clusters were installed along the most 

likely flow paths (figs. 2 and 3) determined by a preliminary 

simulation model. Subsequent uncertainty analysis showed 

that there was a high probability that the source area to PSW-1 

includes an area off the chosen flow path, as discussed in 

Starn and Brown (2007). Additional wells were drilled to 

include areas off the flow path, including areas associated with 

a selected land use or constituent source, to study processes 

integral to the transport of contaminants that are of (1) local 

importance to water quality in a typical New England glacialaquifer setting, and (2) regional or national importance. In 

areas of residential/commercial land use, for example, shallow 

wells were located near septic-tank drainfields, a losing 

stream, dry wells, and areas where road deicing is prevalent; 

these sources or activities are likely to affect groundwater 

quality locally. Bedrock wells were sampled to determine the 

contribution of flow and naturally occurring contaminants 

from upland areas and underlying bedrock. 

The monitoring-well network consists of 35 monitoring 

wells, including 24 screened in glacial stratified deposits, 

7 in underlying or adjacent glacial-till deposits, and 4 in 

underlying or adjacent bedrock (figs. 2 and 3). In most 

locations, a nest of two to three wells was installed so that 

different levels within the aquifer could be monitored and 

sampled. At some locations, wells were drilled into bedrock 

to characterize the contribution of flow from bedrock to well 

PSW-1. One previously installed USGS monitoring well, 

WY35, and PSW-1 were included in the monitoring network 

(table 1). Other wells in similar hydrogeochemical settings 

within the study area or in different areas of land use were 

used in data analysis, including (1) domestic wells in the 

Pomperaug Basin (WY65 and SB120) and the Hartford Basin 

(F344 and S401) that were sampled as part of the NAWQA 

MAS study; (2) a USGS monitoring well, WY53, previously 

installed in the study area; (3) community supply wells in 

the Pomperaug Basin (WY11, 66, 67, 68, and SB112, 118, 

119, and 121) that were sampled for the regional-scale TANC 

study; and (4) NAWQA undeveloped (forested) land-use 

wells completed in glacial aquifers overlying Mesozoic rocks 

in the Hartford Basin (SO110, NBR118, P117, and B403; 

table 1; figs. 1 and 2). Multilevel samplers were installed 

near a shallow well (WY92) to assess the variation in redox 

conditions near the water table.

Drilling, Coring, and Well Installation

Drilling and well installation were completed in three 

phases. The first set of monitoring wells was installed in the 

spring, summer, and fall of 2003, the second set was installed 

in the spring and summer of 2004, and two additional bedrock 

wells were installed in the winter of 2004. Boreholes were 

drilled to help define the lithology (and in the case of bedrock 

wells, geologic structure), to facilitate the collection of solid 

samples, for the purpose of borehole-geophysical logging at 

selected sites, and for the installation of monitoring wells. 

For boreholes in the glacial aquifer, two different methods 

of drilling were used, including (1) the hollow-stem auger 

method with split-spoon sampling, and (2) the drive and wash 

method. Thirty monitoring wells were installed in glacial 

deposits for this study. Most of the boreholes drilled in the 

glacial aquifer were installed using the hollow-stem auger 

method; core samples were obtained from glacial deposits 

by driving 5.1-cm internal-diameter split spoons at 1.5-m 

intervals at each well site. The drive and wash method was 

used at three sites to install continuously screened geophysical 

monitoring wells that spanned the vertical extent of the glacial 

aquifer; core samples were not collected during this drilling. 

Four bedrock wells were drilled, including two cored, open 

borehole wells (WY86 and WY87) and two boreholes drilled 

using the air-hammer rotary method and installed with PVC 

casing and screens (WY97 and WY106). The first two wells 

were sampled using a wire-line system (NQ) for bedrock 

coring with a 5.1-cm (2-in.) internal diameter by 1.5-m (5-ft) 

length split-tube sampler. The second two wells were not 

cored, but cuttings were collected during the air-hammer 

rotary drilling.

Core samples of glacial deposits were collected during 

drilling for visual inspection and later for determination of 

mineralogy; analysis for trace elements in grain coatings, 
10 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

Table 1. Data on the construction of wells in the Woodbury study area, and selected wells elsewhere in the Pomperaug and Hartford Basins, Connecticut.—Continued[NAVD88, North American Vertical Datum of 1988, in meters; NAWQA, National Water Quality Assessment Study; ID, identifier; NA, information not available; bls, below land surface; GSD, glacial stratified deposits; TILL, glacial till; BR, bedrock (shaded gray); TANC, study of Transport of Anthropogenic and Natural Contaminants to public-supply wells; SAS, small-area study, LAS, large-area study; MAS, major aquifer study, LUSfo, land-use study (forested, undeveloped)]

Well ID Study

Altitude, 

land surface 

(meters)

Well depth 

bls (meters)

Depth to 

bedrock 

bls (meters)

Top screen 

depth 

bls (meters)

Bottom screen 

depth 

bls (meters)

Groundwater 

depth 

bls (meters)

Lithology

PSW-1 This study 66.9 18.3 23.2 13.7 18.3 2.9 GSDWY35 Mazzaferro, 1986a 65.2 6.9 16.9 5.4 6.9 2.2 GSDWY531 Grady&Weaver, 1988 70.1 6.3 12.2 5.6 6.3 2.4 GSDWY69 This study 71.1 20.6 20.4 19.1 20.4 4.4 GSDWY70 This study 71.2 13.5 20.4 12.7 13.3 3.0 GSDWY71 This study 71.1 5.4 20.4 4.6 5.2 2.9 GSDWY72 This study 66.2 18.2 18.9 16.7 18.0 1.5 GSDWY73 This study 66.2 10.7 18.9 9.9 10.5 1.6 GSDWY74 This study 66.2 4.4 18.9 3.6 4.2 1.6 GSDWY75 This study 66.6 16.8 17.4 15.2 16.5 1.0 GSDWY76 This study 66.5 4.3 17.4 3.5 4.1 1.2 GSDWY77 This study 72.6 18.3 19.2 16.7 18.1 5.5 GSDWY78 This study 72.6 4.9 19.2 4.1 4.8 3.1 GSDWY79 This study 72.3 4.3 18.6 3.5 4.1 1.6 GSDWY80 This study 77.7 4.1 4.6 3.3 3.9 2.4 GSDWY81 This study 81.4 6.5 20.4 5.7 6.3 3.9 GSDWY82 This study 81.3 16.9 20.4 15.4 16.7 6.0 GSDWY83 This study 74.8 8.5 18.3 7.7 8.3 6.1 GSDWY84 This study 74.0 22.3 22.4 20.8 22.1 5.4 GSDWY85 This study 74.0 6.6 22.4 5.8 6.4 3.7 GSDWY862 This study 93.1 31.4 5.1 16.2 16.5 -0.2 BRWY872 This study 81.6 23.2 6.1 12.2 12.5 3.1 BRWY88 This study 63.7 13.7 15.5 12.2 13.5 0.9 TILLWY89 This study 80.2 11.2 11.3 9.6 11.0 5.4 TILLWY90 This study 80.3 8.4 11.3 7.6 8.2 5.1 TILLWY91 This study 70.0 17.4 18.6 9.7 11.0 1.6 GSDWY92 This study 70.0 4.3 18.6 3.5 4.1 1.5 GSDWY93 This study 76.7 7.7 9.8 6.9 7.5 2.1 TILLWY94 This study 76.7 4.7 9.8 3.9 4.5 2.8 GSDWY95 This study 69.8 4.0 20.4 3.2 3.9 1.2 GSDWY96 This study 149.4 6.7 9.1 5.1 6.5 3.2 TILLWY972,3 This study 149.4 20.3 9.1 18.7 20.1 14.9 BR
Methods of Data Collection and Analysis 11

Table 1. Data on the construction of wells in the Woodbury study area, and selected wells elsewhere in the Pomperaug and Hartford Basins, Connecticut.—Continued[NAVD88, North American Vertical Datum of 1988, in meters; NAWQA, National Water Quality Assessment Study; ID, identifier; NA, information not available; bls, below land surface; GSD, glacial stratified deposits; TILL, glacial till; BR, bedrock (shaded gray); TANC, study of Transport of Anthropogenic and Natural Contaminants to public-supply wells; SAS, small-area study, LAS, large-area study; MAS, major aquifer study, LUSfo, land-use study (forested, undeveloped)]

Well ID Study

Altitude, 

land surface 

(meters)

Well depth 

bls (meters)

Depth to 

bedrock 

bls (meters)

Top screen 

depth 

bls (meters)

Bottom screen 

depth 

bls (meters)

Groundwater 

depth 

bls (meters)

Lithology

WY98 This study 76.9 6.4 6.5 5.6 6.2 3.4 TILLWY99 This study 77.0 4.3 6.5 3.5 4.1 2.8 TILLWY100 This study 67.0 13.4 21.6 12.6 13.2 2.9 GSDWY101 This study 67.0 15.9 21.6 15.1 15.7 2.9 GSDWY102 This study 67.0 4.3 21.6 3.5 4.1 2.9 GSDWY103 This study 66.9 20.9 21.6 2.5 20.7 2.8 GSDWY104 This study 71.1 18.8 20.6 3.3 18.6 0.0 GSDWY105 This study 66.2 18.6 18.9 1.6 18.4 1.8 GSDWY1062,4 This study 67.0 42.6 21.6 41.1 42.4 2.6 BRWY111,5 NAWQA TANC-regional scale 80.8 38.4 38.1 35.1 38.4 10.7 GSDWY661,5 NAWQA TANC-regional scale 87.8 11.6 15.6 8.2 11.6 NA GSDWY671,5 NAWQA TANC-regional scale 61.9 12.2 12.2 9.2 12.2 NA GSDWY681,5 NAWQA TANC-regional scale 137.2 11.9 NA 10.4 11.9 NA GSDSB1121,5 NAWQA TANC-regional scale 49.7 23.2 21.3 23.2 23.2 NA GSDSB1181,5 NAWQA TANC-regional scale 56.1 18.6 19.8 18.6 18.6 NA GSDSB1191,5 NAWQA TANC-regional scale 54.3 25.0 NA 18.3 24.4 NA GSDSB1211,5 NAWQA TANC-regional scale 47.3 21.3 21.3 15.2 18.3 NA GSDWY651,6 NAWQA MAS-Pomperaug Basin 74.1 22.9 NA 22.0 22.9 3.2 GSDSB1201,6 NAWQA MAS-Pomperaug Basin 60.4 16.2 NA NA 16.2 3.0 GSDF3441,7 NAWQA MAS-Hartford Basin 56.4 75.3 NA 74.9 75.3 3.6 GSDS4011,7 NAWQA MAS-Hartford Basin 51.8 33.5 NA 22.8 33.5 3.4 GSDSO1101,8 NAWQA LUSfo 77.7 4.0 NA NA 4.0 1.7 GSDNBR1181,8 NAWQA LUSfo 63.4 5.7 NA NA 5.7 2.6 GSDB4031,8 NAWQA LUSfo 60.4 2.8 NA NA 2.8 0.5 GSDP1171,8 NAWQA LUSfo 27.4 5.2 NA NA 5.2 1.8 GSD

1Not sampled as part of this study.2Bedrock wells were sampled at water-bearing fractures.3Sand pack extends from 21.5 - 17.9 meters bls; steel surface casing extends to 17.68 m bls.4Sand pack extends from 41.1 - 42.4 meters bls; steel surface casing extends to 24.0 meters bls.5Glacial, community-supply well for regional-scale TANC study, Pomperaug Basin.6Glacial, domestic-supply well (major aquifer study) in Pomperaug Basin.7Glacial, domestic-supply well (major aquifer study) in Hartford Basin.8Glacial well in forested, undeveloped land use, Hartford Basin.
12 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

inorganic and organic C forms, N, stable isotopes, and 

sulfides; and determination of bulk density and grain size. 

Clear, plastic core liners were used in split spoons, and 

subsamples were cut, then processed (capped and taped) in 

a glove bag that was continually purged with ultrapure N2. 

Some subsamples were sealed in Mason jars within the glove 

bag, then kept on ice. Detailed sediment lithology of these 

boreholes and the coring procedure for the collection of core 

samples are described in Appendix 1.

Monitoring wells in the glacial deposits were installed 

in accordance with NAWQA protocols (Lapham and others, 

1995). Five-cm (2-in.) diameter polyvinyl chloride (PVC) 

casings with 10-slot (0.25-mm slotted) screens were used 

to construct wells in the glacial deposits (fig. 6). Shallow 

and intermediate wells generally were constructed with 

0.6-m length screens, and deep wells were constructed 

with 1.3-m length screens. Exceptions include shallow 

wells in till (WY80, WY89, WY90, WY93, WY96, WY98, 

and WY99) for which 1.2-m length screens were used. 

Multilevel samplers, which were installed in the annulus of 

WY92, consisted of varying lengths of 0.32-cm (1/8-in.) 

polyethylene tubing with a 2.5- to 5-cm ceramic screen 

at the bottom that was strapped to the well casing (fig. 6). 

Figure 5. Construction and lithology at public-supply well PSW-1 (C.W. Lauman & Co., written commun., 1967), and screened 

intervals for PSW-1 and adjacent monitoring wells WY100, 101, 102, 103, and 106, Woodbury, Connecticut. (Well locations are 

shown in figure 2). DEPTH BELOW LAND SURFACE, IN METERS

Concrete grout

Gravel filter pack

20-inch-diameter drilled hole

10-inch threaded joint

10-inch-diameter steel casing

10-inch-diameter screen,

 stainless steel, 0.070 inch slot

EXPLANATION

Screened interval

Water table

Sand and gravel

Till

Gravel filter pack

Concrete grout

Brown silty sand,

few large gravels 

Fill

Bedrock

Bedrock well (screened 41.1 - 42.4 meters below land surface)

PSW-1

WY106

WY103

WY100

WY101

WY102

PUBLIC-SUPPLY WELL MONITORING-WELL CLUSTER 

Brown fine sand,

mica, few large 

gravels 

Brown fine silty

sand, mica 

Brown very fine

silty sand, mica

20

24

16

12

8

4

Dark brown silty

sand, gravels

Brown coarse

sand and gravel

Brown very fine silty

sand, mica, clay,

cobbles, boulders

Cobbles, boulders,

brown clay
Methods of Data Collection and Analysis 13

Samples were collected from the multilevel samplers using a 

peristaltic pump.

All four bedrock wells were drilled using mud-rotary 

and air-rotary percussion drilling with a 0.2-m-diameter 

tricone roller drilling bit to penetrate the unconsolidated 

overburden material and approximately 0.6 m of competent 

bedrock. A biodegradable drilling fluid, which is designed 

to break down after about 48 hours, was used while drilling 

through the overburden in order to hold the borehole open. 

For the first and second bedrock wells installed, WY86 and 

WY87, 10-cm-diameter PVC casing was set into the predrilled boreholes, and a layer of bentonite chips, followed 

by a mixture of cement and bentonite, was poured into the 

annular space to seal the casing and isolate the water in 

the unconsolidated glacial materials from the water in the 

bedrock. A diamond-impregnated carbide bit was used the 

following day with a rotary-coring tool to cut into the rock. 

An NQ wire-line system was used to recover 1.5-m sections 

of bedrock cores during the drilling process. Bedrock core 

subsamples were placed in a glove bag that was continually 

purged with ultrapure N2, then sealed in Mason jars in the 

glove box and kept on ice. 

For the third and fourth bedrock wells, a steel 0.5-m 

(6-in.) diameter casing was set through the glacial deposits and 

into the rock. The steel casing, which had a drive shoe affixed 

to the lower end, was set into the predrilled borehole at wells 

WY97 and WY106. The casing was hammered into the rock, 

then grouted with a mixture of cement and bentonite to seal 

the casing and isolate the water in the unconsolidated glacial 

materials from the water in the bedrock. A 0.15 m (6-in.) 

Figure 6. Construction diagram and lithology at monitoring wells WY91 and 92, and multilevel samplers WY92c and WY92e, 

Woodbury, Connecticut. (Well locations are shown in figure 2). DEPTH BELOW LAND SURFACE, IN METERS

Concrete grout

Formation collapse

Bentonite seal

2-inch-diameter PVC casing

3/8-inch

polyethylene

tubing

1.5-inch-length 

ceramic filter

2-inch-diameter PVC screen,

 0.010 inch slot

EXPLANATION

WY92

<, less than

ND, not detected

Screened interval

Water table

Sand and gravel

Till

Formation collapse

Concrete grout

Stratified glacial deposits

WY 91

WY 92

Bentonite seal

Concrete grout

WY 92c

WY 92e

Bentonite seal

Dissolved constituent

concentrations,

in milligrams per liter

5.6

1.4

<0.04

ND

2.3

0.18

0.1

0.10

3.8

<0.06

0.1

0.015

3/15/05

5/2/05

3/15/05

5.2

1.6

<0.04

ND

8/19/04

5

0

10

Dissolved oxygen

NO3

-

NH4

+

H2S
14 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

tricone bit then was lowered inside the steel casing, and 

drilling continued to the predetermined depth. For the third 

and fourth bedrock wells, the air-rotary method and airhammer rotary method of drilling did not allow for collection 

of cores, but drill cuttings brought to the surface were 

collected for visual inspection.

Analysis of Glacial Deposits and Bedrock

The mineralogy of samples was determined by powder 

x-ray diffraction (XRD) for both bulk mineralogy and 

clay separates. Heavy-mineral and magnetic-susceptibility 

separations were done on sediment samples to identify 

minerals that could contain sulfides, oxides, and other heavy 

minerals that might be relevant to aquifer chemistry. The 

sediment-core subsamples were small (10 g) and, therefore, 

may not adequately represent the lithology, but they provided 

some information that was useful for the assessment of 

geochemistry and provenance. Once the heavy minerals were 

sieved to less than 60 mesh, separated using heavy liquids 

(density greater than 2.7 g/cm3) and magnetic susceptibility, 

one-half of the sample was ground for emission spectroscopy 

to provide semiquantitative analysis for 35 elements, and the 

other half was examined with light microscopy and powder 

XRD to help identify the minerals. The nonmagnetic fraction, 

which includes most sulfides, oxides, siderite, and silicates, 

and the slightly magnetic fraction were analyzed to target the 

more reactive minerals of interest (Arbogast, 1990). 

Fission-track radiography was used on sediment epoxy 

mounts to determine U concentrations in aquifer solids. 

The procedure involves the irradiation of samples with 

neutrons, which cause fission in 235U, for 8 hours with a 

flux of 2.5x1012 neutrons per centimeters per second. Some 

fission fragments recoil from the sample, enter the detector 

material (muscovite) cover, and create paths of damage that 

are enlarged by etching with hydrofluoric acid. A higher 

concentration of U will yield a greater density of tracks and a 

darker optical image.

Total C was measured by combustion with an automatic 

C analyzer, inorganic C was determined by coulometric 

titration of acid-evolved CO2, and organic C was computed by 

difference (Arbogast, 1996).

C and N in samples of aquifer solids that were collected 

for isotopic analysis were first converted to CO2 and N2 with 

an elemental analyzer; these two gases were separated using a 

gas chromatograph and then analyzed with a continuous-flow 

isotope-ratio mass spectrometer (Brenna and others, 1997; 

Révész and Qi, 2006). Carbonate was reacted with 100 percent 

H3PO4 at 25°C to liberate CO2, which was collected, purified 

by vacuum sublimation, and analyzed on an isotope-ratio 

mass spectrometer (McCrea, 1950). C isotopic ratios are 

reported in parts per thousand (per mil) relative to the VPDB 

(Vienna Peedee belemnite) standard by assigning a value 

of +1.95 per mil to National Bureau of Standard 19 CaCO3

(Coplen, 1994). N isotope ratios are reported relative to N2

in air. Internationally distributed isotope reference materials 

were interspersed with samples for calibration. The 2-sigma 

uncertainty of organic C isotopic results is 0.5 per mil, and 

that for inorganic C isotopic ratio results is 0.2 per mil. 

The 2-sigma uncertainty of N isotopic ratios is 0.5 per mil. 

Physical analyses were made of selected core materials 

including bulk density, percent organic matter (loss on 

ignition), and volumetric moisture content (R.W. Healy, 

USGS, written commun., 2005).

The abundances of elements in sediment grain coatings 

or other mineral phases in samples of aquifer material were 

evaluated by selective extractions using different acids 

and reagents, including (1) 10-percent nitric acid (HNO3), 

(2) 6 moles/L (M) hydrochloric acid (HCl) extraction, 

(3) 0.5-M HCl−hydroxylamine (HA)-extractable Fe, and 

(4) acid-volatile and Cr-reducible sulfides. All extractions 

were performed on wet sediments, but the moisture content 

was determined for a separate subsample and used to 

correct the analytical concentrations to dry weight. The 

first two extractions listed were performed in the laboratory 

environment. For the latter two extractions, core samples were 

subsampled in a glove bag, and the bottles and flasks were 

flushed with N2.

The coatings extraction (HCl and HNO3 extractions) 

methods were primarily intended to target ferric 

oxyhydroxides and their associated trace elements, but they 

also can extract other oxides and clay, carbonate, and sulfide 

phases to varying degrees. The sample/solution ratio for the 

6-M HCl−HA and 10-percent HNO3 extractions were 5 g ± 1 g 

wet weight to 15 mL (milliliters) of acid solution, whereas that 

for 0.5-M HCl−HA extraction was 4 to 10 g wet sediment to 

75 mL of reagent. The sediment and acid suspensions were 

set on a shaker table for 6 hours, then centrifuged, filtered 

with 0.45-mm-pore filters, and analyzed for several elements 

including As and U. Leachate derived from the 10 percent 

HNO3 extractions was analyzed for Al, Cr, Cu, Fe, Mn, 

Ni, and V by inductively coupled plasma optical emission 

spectroscopy (ICP-OES). Further dilution to 5 percent was 

required for analysis of As, Cd, Pb, and U with inductively 

coupled plasma mass spectrometry (ICP-MS), which yielded 

lower detection limits. Analysis of the 6-M HCl extractants 

required further dilution to 1.6-M HCl prior to analysis by 

ICP-MS. Leachate derived from the 6-M HCl extractions was 

diluted to 10 percent and analyzed by ICP-MS for elements 

that included Fe, Mn, Al, Ca, Cd, Cr, Cu, K, Mg, Na, Ni, Pb, 

V, Zn, and U. The 0.5-M HCl−HA and 6-M HCl extractions 

were performed according to Lovley and Phillips (1987) and 

analyzed using ICP-MS. The 0.5-M HCl−HA extracts were 

analyzed using the ferrozine method with a spectrometer 

(HACH Company, 2002).

Sulfide phases in sediments or rock were extracted 

using a method described by Allen and others (1991; 1993) 

and summarized in USEPA method 9030B (USEPA, 2006c). 

However, the method was modified to prevent the oxidization 

of hydrogen sulfide (H2S) by soluble ferric Fe by the addition 

of SnCl2 (M.L. Tuttle, U.S. Geological Survey, oral commun., 
Methods of Data Collection and Analysis 15

2003) and further modified by the addition of CrCl2 (Canfield 

and others, 1986; Bowles and others, 2003) to also extract 

pyrite-bound sulfide (K.M. Conko, U.S. Geological Survey, 

written commun., 2003). Sulfide phases that are extracted 

using this method include pyrite, elemental S, and acid volatile 

monosulfides. Samples of 5 to 20 g of undried sediment were 

transferred to a 250-mL round-bottomed flask (under N2) 

with 10 g SnCl2. The flask was attached to an N2 stream on a 

heating mantle, and 75 mL of deaerated 6-M HCl and 50 mL 

of CrCl2 solution were added. The samples were heated and 

kept at a subboiling temperature for 1 hr. H2S was collected 

in two sequential aliquots of 100 mL of 0.5-M NaOH. 

Sulfide was analyzed colorimetrically using the methylene 

blue method (HACH Company, 2002). N concentrations 

and d15N values were calibrated against reference materials 

USGS40 and USGS41 (d15N = -4.5 per mil and +47.6 per mil, 

respectively). The estimated reproducibility of normalized 

d15N values is about ±0.5 per mil (2 sigma). Batch reactor 

experiments were used to quantify adsorption of As(V) and 

U(VI) using five sediment samples from the study area. 

Core samples from WY83, WY92, WY94, and WY100 were 

collected from glacial stratified deposits, and a core sample 

from WY90 was collected from glacial till. Experiments were 

conducted by combining 35 mL of deionized water with 2 g of 

sediment in 40-mL polypropylene centrifuge tubes. Adsorption 

isotherms for As(V) were determined by diluting As(V) 

stock solutions, prepared from Na2HAsO4×7H2O, to obtain 

initial concentrations ranging from 0 to 500 μg/L. Adsorption 

isotherms for U(VI) were determined by diluting U(VI) stock 

solutions, prepared from UO3, to obtain initial concentrations 

ranging from 0 to 600 μg/L. Sodium bicarbonate was added to 

each set of samples to approximate the HCO3

-

 concentrations 

in groundwater associated with each core sample (table 6A). 

Initial pH values were adjusted with 0.1-Normal (N) H2SO4 to 

the approximate pH of groundwater.

The suspensions were mixed continuously on an endrotating mixer at two revolutions per minute (rpm) for five 

days. It was determined in preliminary experiments that As(V) 

and U(VI) adsorption was rapid, with 90 percent occurring 

within a few hours and reaching equilibrium within 2 days. 

Solutions were separated from the sediment by centrifuging at 

15,000 rpm for 15 min and filtering with 0.2-μm pore filters. 

The pH then was measured, and the HCO3

-

 concentration was 

determined by titration with 0.2-N H2SO4 to an end point at 

pH 4.5. Both As(V) and U(VI) were determined by ICP-MS.

The concentration of surface sites (surf_OH) available 

for adsorption was estimated for each sediment sample by 

titration with hydrogen ions. Ten grams of sediment were 

added to 100 mL deionized water in a 125-mL Erlenmeyer 

flask, and the suspension was stirred continuously during 

the experiments. The initial pH was increased to 10.12 with 

0.1-N NaOH in order to convert most surface sites to surf_O-. 

The suspensions then were titrated with 0.1-N HCl to pH 3.50 

at which all surface sites were surf_OH2+. Because each site 

consumed two hydrogen ions, the concentration of surface 

sites was calculated by dividing the moles of acid consumed 

by two. A deionized-water blank also was titrated to determine 

the quantity of hydrogen ions that were required to decrease 

the pH from 10.12 to 3.50.

The titration was reversed, from 3.50 to 10.12, with 

0.1-N NaOH as a check. The number of moles of OH- required 

to increase pH from 3.50 to 10.12 was within 95 percent of 

the moles of H+ required to titrate suspensions to pH 3.50 

for all samples except those from WY90, which contained 

a carbonate precipitate that also consumed hydrogen ions. 

Titration to pH 3.50 dissolved all carbonates, and N-degassing 

of the solution removed aqueous-carbonate complexes. The 

pH 10.12 to 3.50 titration was repeated on the carbonate-free 

sediment to estimate surface-site concentration.

Geophysical Methods

Both conventional and advanced borehole-geophysical 

methods were used to provide information on lithology and 

groundwater flow at three continuous-screen well locations in 

the glacial aquifer (WY103, WY104, and WY105) and at four 

borehole locations in the underlying (WY106) and adjacent 

fractured bedrock (WY86, WY87, and WY97) (Appendix 2; 

figs. 2–1 to 2–4). Conventional geophysical-logging methods 

were used to determine lithologic properties, infer locations 

where water enters or exits boreholes, and identify variations 

in dissolved solids in the fluids within a borehole and in the 

subsurface material adjacent to the borehole. Gamma logging 

measures the natural-gamma radioactivity of the formation 

surrounding the borehole; sources include K-40 and daughter 

products of U and thorium decay series. Gamma emissions 

can be correlated with lithology or rock type (clay or micarich material) or with fracture infilling and altered zones in 

bedrock. Fluid-resistivity logging measures the electrical 

resistivity of the fluid in the borehole. Changes in the electrical 

resistivity indicate differences in the concentration of the 

dissolved solids in the fluid in the borehole. These differences 

typically indicate sources of water that have contrasting 

chemistry and have come from different transmissive zones. 

Caliper logging is used to generate a continuous profile of the 

borehole diameter with depth and is useful to locate fractures 

and changes in the lithology or borehole construction.

Advanced borehole geophysical logs were used to 

identify the lithology of the boreholes and the location, 

orientation of foliation and laminations in the bedrock, 

and orientation of fractures intersected by the boreholes. 

Optical-televiewer (OTV) logging records a continuous, 

magnetically oriented, digitized 360-degree color image of 

the bedrock borehole wall (Williams and Johnson, 2000), 

that can permit the direct inspection of the borehole for 

fractures, changes in lithology, water level, bottom of casing, 

and borehole enlargements. The acoustic televiewer (ATV) 

produces a high-resolution, magnetically oriented, digital 

image that is used to determine the location and orientation 

of fractures that intersect the bedrock boreholes (Williams 

and Johnson, 2000). ATV logging records the amplitude and 
16 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

traveltime of the reflected signal, which can be displayed 

as a flattened 360-degree view of the borehole wall. Planar 

features such as fractures, foliation, and lithologic contacts 

can be identified directly on the images as sinusoidal curves 

that represent planar surfaces. On the acoustic traveltime log, 

a fracture is indicated by an increase in the one-way traveltime 

of the wave due to an increase in borehole diameter. 

Flowmeter logging was used to measure the direction 

and rate of vertical flow in boreholes and well screens. A 

Heat-Pulse Flowmeter (HPFM) was used in the four bedrock 

boreholes, whereas an electromagnetic (EM) flowmeter was 

used in the continuous well screens in the glacial aquifer. 

Fractures (in bedrock) or conductive zones (in sand and 

gravel) where water enters or exits the borehole or screen can 

be identified by evaluating the flowmeter results in conjunction 

with other geophysical logs. Under nonpumping conditions, 

differences in hydraulic head between two transmissive zones 

produce vertical flow in the borehole. Flowmeter logging was 

conducted under nonpumping conditions and under low-rate 

(1 to 3.8 L/min) pumping conditions to identify transmissive 

zones with similar heads that could not be identified without 

stressing the aquifer. For the bedrock wells, measurements 

were collected at discrete locations, usually above and below 

fractures, to determine any changes in the vertical flow rate 

that can be attributed to inflow or outflow at fractures between 

the measurement sites and to determine locations for screen 

zones and (or) the acquisition of water samples for waterquality analysis.

Collection and Analysis of Water Samples

Each well in the sampling network was sampled one 

to four times during the study, depending on the well depth 

and the date of installation. Wells along the estimated 

primary flow path were sampled once for an extensive list 

of constituents, including major ions and trace elements, 

222Rn and radionuclides, dissolved gases, age tracers, stable 

isotopes, VOCs, and pesticides (table 2). Wells off the primary 

flow path and shallow source wells, which were installed 

to characterize contaminant sources, were sampled for a 

more limited list of constituents (table 2) and were sampled 

more frequently to assess temporal variability. The shallow 

monitoring wells and PSW-1, along with the adjacent deep 

wells, were sampled two or three additional times for a limited 

list of analytes in order to assess temporal variability. The 

exception is well WY90, which could not be sampled initially 

because of the seasonally low position of the water table and 

the poor yield. A total of 85 samples were analyzed for this 

study, although some samples were collected from pooryielding wells on more than one occasion because a complete 

sample set could not be obtained on a given day.

Groundwater was sampled according to protocols 

by Koterba and others (1995). Wells were purged, and 

field measurements of temperature, specific conductance, 

pH, turbidity, and dissolved O2 (DO) concentrations were 

monitored until stable. Concentrations of total dissolved 

sulfides (H2S plus HS-, herein referred to as “H2S”) and low 

concentrations of DO (less than 1 mg/L) were measured 

onsite using colorimetric procedures (HACH Company, 

2002). All groundwater samples were analyzed for alkalinity 

by incremental titration within a few hours after sample 

collection. Water samples collected for analyses of major ions, 

trace elements, nutrients, and stable isotopes were filtered 

with a 0.45-μm inline filter; water samples for analysis of 

pesticides were filtered with a 0.7-mm glass-fiber filter. SO4

2−

in groundwater was collected on an anion-exchange resin 

column for sulfur-isotope analysis or water was collected in a 

bottle if SO4

2− concentrations were sufficiently high (Carmody 

and others, 1998). Groundwater ages were estimated from 

concentrations of tritium (3H), tritium-helium (3H-3He) ratios, 

chlorofluorocarbons (CFCs), and sulfur hexafluoride (SF6) 

tracers. Concentrations of 3H and 3H-3He ratios were measured 

in samples from selected wells and converted to residence 

times for comparison with simulated groundwater residence 

times (Starn and Brown, 2007). Water samples for d13C 

analysis of dissolved inorganic carbon (DIC) were collected 

in 1-L glass bottles, which were filled from the bottom up and 

sealed with a Teflon/silicon septa cap after a minimum of 3 to 

5 L were allowed to overflow the bottle to eliminate O2.

Groundwater samples to be analyzed for dissolved 

gases were collected in 160-mL septum bottles (sealed in a 

large beaker under flow of evacuated well water) and (or) in 

Cu tubes with pinchoff valves. In several cases, the samples 

in the septum bottles also were measured for d15N of N2. 

Dissolved gases (N2, Ar, CO2, CH4, O2, Ne, and He) were 

analyzed in groundwater samples by gas chromatography 

after extraction in headspaces of glass sample bottles 

(Busenberg and others, 1998). The resulting data were used 

to define recharge temperatures (1) for age dating because 

the solubility of atmospheric tracers varies as a function of 

temperature, (2) for determining concentrations of excess air 

and excess N2 to reconstruct initial NO3

−

 concentrations on 

the basis of the amount of denitrification that has occurred 

(Plummer and others, 2003), and (3) for tracing sources of 

groundwater recharge. Excess air consists of air trapped 

in pores that dissolves in groundwater, typically after a 

rapid rise in the water table. The amount of excess N2

reflects the amount of denitrification that has taken place. 

Recharge temperatures were calculated from Ne and Ar gas 

concentrations where these gases were both analyzed, and 

from N2 and Ar gas concentrations in samples where Ne 

concentration data were not available. N2 concentrations can 

be affected by denitrification under denitrifying conditions 

(where concentrations of O2 are less than 3 mg/L, those of Fe 

are greater than 0.3 mg/L, and those of Mn are greater than 

0.1 mg/L, and (or) HS- or CH4 are present) and, therefore, are 

not as reliable as Ne concentrations, particularly in samples 

where excess N2 is present. In one sample where gas samples 

were exsolving (probably due to methanogenesis and (or) 

generation of H2S), the He concentration also was used to 

constrain the recharge temperature. Ne and Ar are the more 
Methods of Data Collection and Analysis 17

Table 2. Classes of water-quality chemical characteristics and constituents measured in water samples from the Woodbury, 

Connecticut, study area for the flow-path, source-well, and stream-sampling analyte schedules, October 2002 to July 2006.

[Water-quality field parameters: temperature, pH, specific conductance, dissolved oxygen, dissolved sulfides, alkalinity; DOC, dissolved organic carbon; 

Ra, radium; Rn, radon; He, helium; O, oxygen; H, hydrogen; N, nitrogen; C, carbon; δ, delta; As, arsenic; SO4

2−, sulfate; CFCs, chlorofluorocarbons CFC11, 

CFC12, CFC113; analyses done by the U.S. Geological Survey National Water Quality Laboratory, unless otherwise indicated]

Flow-path schedule Source-well schedule Stream-sampling schedule

Water-quality field parameters Water-quality field parameters δ18O and δ2H (δD) isotopes1

Volatile organic compounds (VOCs) Volatile organic compounds (VOCs)

Gasoline oxygenates Major inorganic constituents and nutrients

Pesticides and herbicide metabolites DOC and ultraviolet absorbance

Major inorganic constituents and nutrients Stable isotopes (selected sites)

Trace elements Dissolved gases (selected sites)

As species, As[V] and As[III] 222Rn (selected sites)

DOC and ultra-violet (UV) absorbance 3H-3He ratios2 (δ3He) (selected sites)

δ15N isotopes1 in dissolved NH4

+ CFCs3

δ15N and 18O isotopes1 in dissolved NO3

− Sulfur hexafluoride3

 (SF6) (selected sites)

δ18O and δ2H (δD) isotopes1

δ34S isotope ratios1 (δ34S in SO4

2−)

δ13C isotope ratios4

Ra isotopes5 (226Ra & 228Ra)

Gross alpha / gross beta radiation5

222Rn

Dissolved gases6

3

H (tritium)7

3

H-3He ratios2 (δ3He)

4

He isotopes3

CFCs3

Sulfur hexafluoride3 (SF6)

1

Analyzed at the USGS Reston Isotope Laboratory, Virginia.

2

Analyzed at the Lamont Doherty Earth Observatory, Tritium-Helium Laboratory, New York.

3

Analyzed at the USGS CFC Laboratory, Virginia.

4

Analyzed at the University of Waterloo, Ontario.

5

Analyzed at Eberline Services, Richmond, California.

6

Analyzed at the USGS Dissolved Gas Laboratory, Virginia.

7

Analyzed at the University of Miami Laboratory, Florida.
18 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

conservative of the gases analyzed and were the first choice 

used to calculate recharge temperatures and excess air by 

using a back-solving routine to iterate between the solubility 

of each until they converged to a common value. In samples 

where Ne was not analyzed, N2 and Ar gases were used in 

the same way to calculate the recharge temperature. For 

samples in which excess N2 concentrations were estimated, 

an uncertainty analysis was done to estimate denitrification. 

To obtain the upper and lower limits of uncertainty, the excess 

N2 concentration was varied, first until the average excess air 

temperature was obtained, then until the average amount of 

excess air was reached. Dissolved gases were measured by 

gas chromatography after extraction from headspaces of glass 

samplers (Busenberg and others, 1998).

Multilevel samplers that were installed with their 

openings in the saturated zone above the screen at WY92 

were pumped with a peristaltic pump for 3 to 5 min before 

pH, specific conductance, DO, and H2S were measured; H2S 

was measured colorimetrically with a spectrometer. Samples 

were collected for analysis of nutrients at these sites. Because 

air bubbles were abundant in the water evacuated during 

sampling, however, concentrations of DO were likely to be 

artificially high and those of H2S, artificially low.

Water samples were analyzed for major and trace 

constituents, nutrients, DOC, 222Rn, pesticides, and VOCs 

by the USGS National Water-Quality Laboratory (NWQL) 

in Denver, Colorado. Major ions and trace elements were 

analyzed by ICP-MS, atomic-absorption spectrometry, or ion 

chromatography (Fishman and Friedman, 1989; Fishman, 

1993; and Faires, 1993). Samples were analyzed for ultraviolet absorbance at 254 nanometers and 280 nanometers. 

Nutrient concentrations were determined by colorimetry 

(Fishman, 1993; Patton and Kryskalla, 2003). VOCs samples 

were unfiltered and determined by gas chromatography 

and mass spectrometry using methods described in Connor 

and others (1998). Pesticides samples were filtered and 

analyzed by solid-phase extraction and capillary column gas 

chromatography/mass spectrometry (Kish and others, 2000; 

Zaugg and others, 1995). DOC was analyzed by ultravioletpromoted persulfate oxidation and infrared spectrometry 

(Brenton and Arnett, 1993). 222Rn was analyzed by liquid 

scintillation (American Society for Testing and Materials, 

1996). Activity of 226Ra was measured by 222Rn emanation, and 

activity of 228Ra was measured by beta counting, following 

standard USEPA methods (EPA 903.1; EPA 904.0–modified; 

Krieger and Whittaker, 1980). Water-quality samples were 

collected for 72-hour and 30-day gross alpha and gross beta 

activities and determined at Eberline Services of Richmond, 

California, by evaporating an aliquot of sample and counting 

alpha and beta emissions from the residue (EPA 900.0 – 

modified; USEPA, 1980).

Stable isotopes were analyzed using several different 

methods. Analyses of the stable isotopes of water, deuterium 

(dD or d2H) and d18O were done at the USGS Stable Isotope 

Laboratory in Reston, Virginia; a hydrogen equilibration 

method was used for dD analysis (Coplen and others, 

1991), and the CO2 equilibration technique (Epstein and 

Mayeda, 1953) was used for analysis of d18O. Analytical 

uncertainties for dD and d18O values are 2 and 0.2 per mil, 

respectively. Isotopes of N and O of NO3

−

 were analyzed 

using bacterial conversion of NO3

−

 to nitrous oxide, and 

values were reported relative to N2 in air, and the Vienna 

Standard Mean Ocean Water (VSMOW), respectively (Sigman 

and others, 2001; Casciotti and others, 2002; Révész and 

Casciotti, 2007). SO4

2− in groundwater and d34S in SO42− were 

analyzed for BaSO4 precipitates using procedures described 

in Carmody and others (1998). Results are reported in per 

mil relative to the Vienna Canyon Diablo Troilite (VCDT) 

standard. The uncertainty associated with d34S values is 

± 0.2 per mil. Water samples were analyzed for d13C using 

mass-spectrometry techniques at the University of Waterloo 

Environmental Isotope Laboratory in Waterloo, Canada, and 

are reported relative to the Vienna Pee Dee Belemnite (VPDB) 

standard. The uncertainty associated with the d13C values is 

± 0.2 per mil.

The age tracers 3H, 3H-3He, CFCs (CFC-11, CFC-12, 

and CFC-113), and SF6 were collected and measured to 

estimate the apparent groundwater age. Anthropogenic 

activities, such as industrial processes and atmospheric 

testing of thermonuclear devices, released 3H, SF6, and CFCs 

into the atmosphere in small but measurable concentrations. 

Precipitation that incorporates these gases from the 

atmosphere infiltrates into the ground and carries the particular 

chemical or isotopic signature of the atmospheric conditions 

at the time of recharge. These dating methods assume that gas 

exchange between the unsaturated zone and the atmosphere 

is fast, but that shallow groundwater remains closed to gas 

exchange after recharge (Schlosser and others, 1989; Plummer 

and Busenberg, 1999; Busenberg and Plummer, 2000). Where 

possible, two age-dating indicators were used for several wells 

that are thought to lie along the primary flow path within the 

modeled contributing area to the supply well. Certain tracer 

methods were avoided for wells that are known or suspected 

to have contamination from natural or anthropogenic sources 

not carried naturally by recharge. Unless otherwise noted, 

apparent ages were estimated by assuming that piston flow 

prevails in the aquifer system. 

The 3H-3He samples were collected in (1) special Cu 

tubes for 4He and Ne analyses and determination of d3He in 

dissolved He, and (2) 500-cm3 bottles for 3H determination 

by He ingrowth (Plummer and others, 1993). The samples for 

the determination of 4He, Ne, and d3He in dissolved He were 

collected in pinched-off copper tubes while back pressure was 

applied to prevent formation of gas bubbles. These samples 

were analyzed at the Noble Gas Laboratory of LamontDoherty Earth Observatory in Palisades, New York, by using 

quantitative gas extraction followed by mass spectrometric 

techniques (Schlosser and others, 1989). 

The 3H in water was measured at the Tritium Laboratory 

at the University of Miami, by internal gas proportional 

counting of H2- gas made from the water samples. 3H that 

was released into the atmosphere from nuclear weapons 
Methods of Data Collection and Analysis 19

tests between 1952 and 1963 provides a tracer for rainwater 

that allows dates of recharge to be estimated. Although 3H 

concentrations are now (2007) approaching that of natural 

atmospheric production (15 to 25 3H units), they remain 

high enough to use in this analysis. Bomb-related 3H can be 

used to infer some aspects of groundwater age; at the very 

least, water can be recognized as being recharged before 

or after 1953. Determination of both 3H and tritiogenic 3He 

in groundwater can define the initial 3H content and allow 

calculation of the apparent 3H-3He age. Details of 3H-3He 

dating procedures are presented in Schlosser and others 

(1988) and Solomon and Cook (1999). Analytic uncertainty 

is approximately ± 0.5 years. Larger uncertainties in age 

can result from (1) corrections in defining the tritiogenic 

3

He, (2) the assumption that the parcel of water remains 

confined following infiltration, and (3) mixing effects caused 

by hydrodynamic dispersion. Limitations to 3H-3He dating 

of groundwater in the study area include the addition of 

terrigenic He from crystalline rock sources and loss of 3H by 

degassing during sampling. For example, samples from wells 

drilled in the Taine Mountain Formation and a pegmatite 

(both discussed in section “Hydrogeologic Setting”) in the 

uplands of the study area contain excessive terrigenic He 

derived from the crystalline rock sources, which precluded 

the determination of ages. He excess in samples, in which an 

old fraction contains mixed mantle and crustal He sources 

that are as much as 50 percent greater than that of air-water 

equilibrium (4.6 x 10-8 cm3 STP/g), can invalidate or create 

large uncertainties in 3H-3He dating (Plummer and others, 

2003). Wells screened in the glacial deposits also had elevated 

terrigenic He, but values were corrected; those interpretations 

are discussed in the section on groundwater age.

The CFC samples were collected by inserting the end of 

the discharge tubing into the bottom of the bottle, allowing 

at least 2 L to overflow into a 2-L beaker, then capping the 

125-mL glass bottles with special foil-lined caps under water 

within the beaker. Groundwater samples for SF6 were collected 

by placing the sampling discharge line in the bottom of the 

bottle and displacing the air in the bottle with groundwater. 

After approximately 2 L of overflow, the sampling line was 

removed. The bottles were capped with polyseal conical screw 

caps without headspace and wrapped with electrical tape to 

prevent the caps from coming loose during shipping.

Concentrations of trichlorofluoromethane (CFC-11), 

dichlorodifluoromethane (CFC-12), and CFC-113 in water 

were determined at the USGS CFC laboratory in Reston, 

Virginia, with a detection limit of about 0.3 pg/L using purge 

and trap, gas-chromatographic techniques with electroncapture detector (GC-ECD) (Bullister, 1984; Bullister and 

Weiss, 1988; Busenberg and Plummer, 1992). Age dating with 

CFCs was done for samples from only two of the bedrock 

wells because of contamination by CFC point sources in 

groundwater underlying, or downgradient from, commercially 

developed land. The CFC-dating technique is described in 

Busenberg and Plummer (1992). Samples were analyzed for 

SF6 at the USGS CFC laboratory using procedures described 

by Busenberg and Plummer (2000). Terrigenic sources that are 

known to occur naturally, produce SF6 at low concentrations in 

some crystalline rocks (Busenberg and Plummer, 2000), which 

can result in apparent ages that are too young. Source rocks for 

naturally occurring SF6 in the study area may include upland 

igneous and metamorphic rocks, Mesozoic sedimentary rocks 

(derived from metamorphic rocks) that contain quartz grains 

with fluid inclusions (Krynine, 1950), and glacial deposits that 

contain both source rocks.

Statistical Analysis

Statistical procedures were used to describe distributions 

of data grouped by the lithologic composition of the aquifer, 

or to test for differences in the concentration or frequency 

of detection of water-quality variables for each group. 

Boxplots (Helsel and Hirsch, 1995) were constructed to 

show differences between groups of data that are uncensored 

or slightly censored (75 percent or more of the data greater 

than detection or reporting limits). Boxplots of selected data 

presented in this report illustrate the 10th, 25th (1st quartile), 

50th (median), 75th (3rd quartile), and 90th percentiles of the 

data distributions, plus values outside of the 10th and 90th 

percentiles (outliers).

Hypothesis tests were used to test for significant 

differences in water-quality variables among populations 

groupings. A one-factor analysis of variance (ANOVA) 

compares the mean values of each group with the overall 

mean for the entire data set and was used to test the null 

hypothesis that the group means, which include those for 

pH and HCO3

-

, are identical to the overall mean (Helsel and 

Hirsch, 1995). Rejection of the null hypothesis at the a = 0.05 

level of significance was considered evidence supporting the 

alternative hypothesis that the group means differ from the 

overall mean. The Kruskal-Wallis rank sum test, which is a 

nonparametric alternative to the one-way ANOVA (Helsel 

and Hirsch, 1995), was performed on data with a nonnormal 

distribution, including those for DOC and NO3

−

.

Quality Assurance

Quality-assurance samples were collected to assess 

laboratory performance and to help identify contamination 

problems associated with field-collection methods. Qualityassurance information for this study included the collection 

of 5 replicate samples, 16 blank samples, 3 equipment blanks, 

and 5 laboratory-surrogate spike samples of most constituents. 

Multiple replicate samples were collected and analyzed for 

VOCs, pesticides, major and trace constituents, and nutrients, 

which were the most frequently sampled constituents. 

Field blanks were collected at about 10 percent of wells to 

determine whether contamination occurred during sample 

collection, transport, or analysis. All blanks were processed 

using N2-purged universal water that was certified for use 

in the collection of blank samples for VOCs, pesticides, 
20 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

nutrients, DOC, major ions, and trace elements. Field blanks 

were processed using the same procedures and equipment as 

the environmental samples.

The only organic compounds detected in blank samples 

were carbon disulfide (CS2), benzene, and toluene, which 

were detected at estimated concentrations (E values, less 

than the MRL) of 0.07 μg/L, 0.01 μg/L, and 0.088 μg/L, 

respectively, in a field-equipment blank (Appendix 3). Two 

of those organic compounds also were detected in the blank 

water, which indicates that either the blank water itself was 

the source or the blanks were contaminated in the laboratory 

where the blanks were processed. No other VOCs or pesticides 

were detected in blank samples. Four inorganic constituents 

were detected in blanks at concentrations that were greater 

than the MRLs, including Cu, Pb, Zn, and Al. Two additional 

inorganic constituents, Ba and Be, were detected at 

estimated concentrations.

Values from replicate analyses for organic compounds 

were within analytical uncertainty, with the exception of 

organic C. Values from replicate analyses for inorganic 

compounds were within analytical uncertainty for all 

constituents. Bromide analyzed in several water samples 

collected from June 2005 to the end of the data collection 

had a positive bias, on average, compared to historic median 

values. The bias was likely a result of matrix interferences 

found in environmental samples; these values were removed 

from the data set used for this study.

Four surrogate compounds were added at the NWQL to 

all groundwater, surface-water, and quality-control samples 

that were analyzed for pesticides, VOCs, and gasoline 

oxygenates. These included diazinon-d-10, isobutyl alcohol, 

1,2-dichloroethane-d-4, and 1-bromo-4-fluorobenzene. 

Recoveries that range from 70 to 130 percent generally are 

considered to be within acceptable limits, although this range 

can vary considerably for specific compounds. Recoveries for 

the diazinon-d-10 surrogate ranged from 78 to 106 percent. 

Median percent recoveries for the three other surrogates were 

as follows: isobutyl alcohol, 91; 1,2-dichloroethane-d-4, 120; 

and 1-bromo-4-fluorobenzene, 88.

Hydrogeologic Setting

The Pomperaug aquifer system is made up of glacial 

deposits and fractured bedrock. Glacial stratified deposits 

are generally the most productive sources of groundwater in 

the New England area and occur in primary and secondary 

valleys. Glacial deposits overlie bedrock in all but a very few 

localized areas. Fractured-bedrock aquifers are located in the 

uplands, where they are used mostly for domestic supply and 

are mostly overlain by glacial till, and beneath the glacial 

stratified deposits in the valleys. In the Pomperaug aquifer 

system, as in much of New England, these two aquifers 

are hydraulically connected along valley bedrock contacts, 

although the flow rate is generally much less in fractured 

bedrock. The term “glacial aquifer system” herein refers to 

glacial deposits, including stratified deposits and till, and the 

underlying or adjacent fractured bedrock.

Bedrock Geology

Most of the study area is underlain by bedrock of at least 

two distinct ages and origins: (1) Paleozoic metamorphic 

rocks, which underlie the uplands east of the Pomperaug River 

Valley, and (2) Mesozoic basalt and sedimentary rocks, which 

underlie the valley (fig. 7). The Mesozoic and Paleozoic rocks 

are separated by the eastern border fault, which runs along 

a north-flowing segment of South Brook near wells WY86 

and WY87. The Pomperaug River watershed lies along the 

western edge of the Pomperaug Basin, which is similar in 

character to that of the Hartford Basin in central Connecticut; 

both of these basins include Mesozoic-age rocks of arkosic 

sandstone, conglomerate, shale, siltstone, and basalt (Burton, 

2006). Sediment grains in the coarse-grained glacial deposits 

of the Pomperaug Basin indicate a local provenance, including 

weathered basalt and other Mesozoic rocks and garnet-mica 

schist and gneiss from surrounding Paleozoic rocks (Burton 

and others, 2005).

The Mesozoic-age sequence of rocks, formally known 

as the Pomperaug Group is about 500 m thick and consists of 

as many as three basalt layers interbedded with shale, arkosic 

sandstone, and conglomerate, which dip eastward at various 

angles but average about 40o (Burton and others, 2005; Huber 

and Letourneau, 2006; fig. 7). In general, the rocks within 

the Pomperaug Group are faulted and fractured and consist 

of immature feldspathic alluvial and lacustrine closed-basin 

deposits. The lowermost unit is the South Britain Formation 

of Late Triassic age that consists of siltstone, sandstone, 

and conglomerate. Three basalt units have been described, 

including the East Hill Basalt, the Orenaug Basalt, and the 

South Brook Basalt. The upper two basalts, the Orenaug and 

the South Brook Basalts, are geochemically similar to their 

equivalents in the Hartford Basin to the east (Burton and 

others, 2005). The Orenaug Basalt is comagmatic with the 

Holyoke and Preakness Basalts of the Hartford and Newark 

Basins, respectively (Hurtubise and Puffer, 1983; Philpotts and 

others, 1996; Burton and others, 2005). 

The Cass Formation, which is 35 to 40 m thick, overlies 

the East Hill Basalt and consists of buff to black micrite 

(limestone) and calcareous shale; gray and red siltstone; redbrown and buff, fine- to coarse-grained litharenitic, quartzose, 

pebble-cobble conglomerate. The limestone unit is organic 

rich and known for its bitumen-coated fractures (Burton and 

others, 2005). The Orenaug Basalt is a quartz tholeiite at least 

80 m thick that forms most ridges in the Pomperaug Basin 

(Burton and others, 2005). Burton and others (2005) report 

possibly three basalt flow units within the Orenaug Basalt; 

the middle unit is softer than the others, more susceptible 

to erosion, and may be related to the bedrock topographic 

lows between ridges. The middle unit of the Orenaug Basalt 
Hydrogeologic Setting 21

Figure 7. Bedrock geology of the Pomperaug and Connecticut structural basins and the study area, and simulated paths of 

flow to monitoring wells and the modeled contributing recharge area to PSW-1 based on particle tracking with MODPATH 

(Starn and Brown, 2007), Woodbury, Connecticut.

Modeled area

Outcrop

Monitoring well, identifier,

and simulated path lines

Major aquifer-study well and

identifier (cycle II)

EXPLANATION

Pegmatite

Cass formation

East Hill basalt

Orenaug basalt

South Brook basalt

PALEOZOIC

AGE

MESOZOIC AGE

POMPERUAG GROUP

White Oaks formation

Taine Mountain formation

Taine Mountain formation, 

basal member 

South Britain formation

Contact

Fault, dashed where interpreted

Quarry

Js

Jw

Jo

Jc

Je

Trs

Dp

Ot

Otb

}

}

U.S. Geological Survey monitoring

well and identifier (previous study)

Pomperaug Basin 

(Burton, 2006)

Geologic map of the Pomperaug

Structural Basin (Burton, 2006)

Connecticut State geologic map

compiled by Rodgers (1985)

Pomperaug

Structural

Basin

Hartford

Structural

Basin

Eastern

Border

Fault

73°13' 73°12' 73°11'

41°32'

41°31'

0 0.5 1.0 KILOMETERS

0 0.25 0.5 0.75 MILES

Quarry

WY83

WY65

Contributing recharge 

area to PSW-1

WY53

WY86

WY87

WY91,92

WY69,70,71

WY72,73,74

WY83

WY65

WY79

WY81,82

WY98,99 WY80

WY77,78 WY84,85

WY93,94

Ot

WY95 WY53

Je

Otb

Beyond 

extent of 

geologic

mapping by

Burton (2006)

Je

Je

Trs

Jc

Jc

Jc

Jc

Jo

Js

Dp

Dp Jw

WY88 WY89, 90

WY35

WY96,97 WY100,101,102 WY75,76

Jw

Trs

PSW-1
22 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

underlies much of the study area and contains abundant 

plagioclase and amygdules filled with carbonate, prehnite, 

and chalcedony, as observed in WY87. The White Oaks 

Formation, which overlies the Orenaug Basalt, consists of a 

black lacustrine shale, conglomerate, and pebbly arkose and 

correlates to the East Berlin Formation of the Hartford Basin, 

the Turners Falls Formation of the Deerfield Basin, and the 

Towaco Formation of the Newark Basin (Burton and others, 

2005). The third basalt, the South Brook Basalt, overlies 

the White Oaks Formation and consists of a highly altered, 

vesicular basalt; exposures along South Brook are strongly 

altered by secondary growth of calcite, dolomite, and other 

minerals, and contain at least two Cu prospects.

Sedimentary rocks in the Hartford and Pomperaug 

Basins consist of a mixture of three mineralogic end 

members—(1) an arkosic (granitic) detritus made of about 

58 percent quartz, 40 percent feldspar (31 percent microcline, 

9 percent Na-plagioclase) and 2 percent mica; (2) a mixture 

of white and hematitic clay consisting of about 60 percent 

kaolinite, 6 percent gibbsite, 12 percent sericite-illite, and 

20 percent hematite; and (3) a calcite cement (Krynine, 

1950). Ferroan dolomite and dolomite cements also were 

found almost exclusively in the lacustrine, playa, and minor 

fluvial sandstones of the Hartford Basin (Hubert and others, 

1992). Rocks in the Hartford Basin generally are illitic, with 

subordinate amounts of chlorite (April, 1981); smectites 

and mixed-layer clays are the predominant clays in the East 

Berlin Formation (Gottfried and Kotra, 1988). Most samples 

of carbonaceous shales from the Newark Supergroup in the 

eastern Mesozoic Basins are not metal rich, aside from Cu; 

trace metals in these rocks mostly are associated with the 

inorganic clay fraction and not with organic matter (Dean, 

1988). Whole-rock geochemical analysis of shale from several 

members of the Passaic Formation in New Jersey yielded 

maximum concentrations of As that ranged from 13 mg/g 

in red shale to 50 mg/g in gray shale and 130 mg/g in black 

shale, with pyrite being the major source in black shales 

(Serfes, 2004).

Nonmarine sediments that were deposited in the 

Pomperaug Basin during the mainly arid Late Triassic and 

Early Jurassic Periods consist of evaporates and caliche, 

in addition to arkoses and shales (LeTourneau and Huber, 

2006). Downward circulating diagenetic fluids associated 

with the emplacement of diabase dikes and sills, and basalt 

flows (Gray, 1988; Huber and MacDonald, 1992) resulted 

in concentration of salts and metals and provided a Na-rich 

brine responsible for the formation of analcime and albite 

(van de Kamp and Leake, 1996), as well as chert, quartz, 

and albite overgrowths; hematite, illite and chlorite cement; 

carbonates; and metaliferous minerals in Mesozoic rocks 

of the Hartford Basin (Gray, 1988; Merino and others, 

1997). Trace metals weathered from mafic minerals were 

concentrated in the brine and ultimately deposited in the 

Na-rich shales of the Hartford (and presumably Pomperaug), 

Newark, and Deerfield Basins (van de Kamp and Leake, 

1996). Although no substantial evaporite deposits have been 

found in the shales of the Hartford Basin, probably as a result 

of dissolution by groundwater, some gypsum (CaSO4×2H2O) 

was found in the East Berlin Formation of the Hartford Basin 

(Hubert and others, 1978), and molds of anhydrite (CaSO4) 

crystals are common in basalts of the Pomperaug Basin 

(Garabedian and others, 1996). Small, stratabound deposits 

and fault/replacement deposits of Cu and Zn are widespread in 

sandstones beneath or adjacent to basalts in the vicinity of the 

Hartford Basin (Robinson and Sears, 1988).

Surficial Deposits

Surficial deposits in the study area consist of glacial 

till, glacial stratified deposits, and postglacial flood-plain 

deposits (alluvium and swamp). Most of the weathered rock 

and saprolite that mantled the bedrock surface probably was 

removed by the Illinois and Wisconsin Episodes ice sheets 

that covered Connecticut (Stone and others, 2005). Glacial 

stratified deposits composed of gravel, sand, silt, and clay 

were sorted and deposited by flowing glacial meltwater (Stone 

and others, 2005). Glacial stratified deposits are as much 

as 23 m thick beneath the study area but can be as much as 

46 m thick in other parts of the Pomperaug aquifer system 

(Mazzaferro, 1986b) typically associated with ice-contact 

positions and morphosequences (Koteff and Pessl, 1981; 

Randall, 2001; and Stone and others, 2005). A companion 

report (Starn and Brown, 2007) describes the glacial 

stratigraphy in more detail.

The source rocks for glacial deposits, on the basis of the 

color of the sediments and the rock fragments and gravels 

within (Appendix 1), appear to consist of a mixture of gray 

and greenish gray basalt (Orenaug, East Hill, or South 

Brook), light to medium gray gneiss and schist (probably 

Taine Mountain Formation or Rowe Schist), granite, reddish 

brown arkose (probably South Britain or White Oaks 

Formations), and black and reddish silty sand (probably from 

the Cass Formation), according to Burton and others (2005). 

The sediments at WY83 are generally coarse but include a 

0.15-m-thick, blackish-red layer that is high in silt and clay. 

The Cass Formation includes organic-rich (bitumen) lacustrine 

shales and siltstones that may be the source rock. The graincoating extractions indicated relatively high concentrations of 

U and As, which can be common in Newark Supergroup rocks 

(Vine and Tourtelot, 1970; Coveney and Martin, 1983).

Hydrology

Precipitation in the Pomperaug River Watershed averages 

about 117 cm/yr (centimeters per year; Randall, 1996). 

About 53 cm/yr of that is lost to evaporation or transpiration; 

therefore, about 64 cm/yr of water potentially could flow 

through the groundwater system (Starn and Brown, 2007). 

Generally, there is more recharge in spring and fall than in 

summer and winter. Sources of groundwater recharge in the 

study area include precipitation that infiltrates the ground 
Hydrogeologic Setting 23

and flows to the water table, streamflow where water flows 

from the stream to the water table, and subsurface flow from 

adjacent areas. Infiltrating precipitation recharges groundwater 

in the study area at different rates depending on geologic, 

topographic, and climatic factors (D.M. Bjerklie, U.S. 

Geological Survey, written commun., 2007). Geologic and 

topographic factors, such as surface permeability and slope, 

determine the rate of recharge in different areas. Climatic 

factors, such as rainfall and temperature, affect seasonal 

differences in the rate of recharge.

Water use in the Pomperaug River watershed, as in much 

of New England, varies by topography and demographics. 

Residents in the primary and secondary valleys of Connecticut 

generally rely on groundwater from public-supply wells. The 

exception to this is major cities, such as Hartford, New Haven, 

and Bridgeport (populations greater than 100,000), which 

generally rely on surface water from reservoirs or rivers. 

Residents in upland areas mostly rely on groundwater derived 

from fractured bedrock, either from domestic wells or small 

community public-supply wells. Most people in Woodbury 

live in the valley bottom and are supplied by groundwater 

from two community public-supply wells, including PSW-1 

that is the focus of the contributing area studied here. 

Community public-supply wells are present in the uplands 

(see Lyford and others, 2007), but much of the remaining 

withdrawals are from domestic wells in fractured bedrock.

Most of the groundwater withdrawn in the study area 

is returned to the subsurface as flow through septic-tank 

drainfields, although a small portion is applied to lawns, and 

a portion may recharge the groundwater system. In upland 

areas, the net effect of pumping from domestic wells is to 

redistribute water from bedrock fractures to shallow soils 

developed in glacial till. More of the water in the shallow 

subsurface evaporates or flows to local streams than would 

be the case if the water was not withdrawn from the bedrock 

aquifer (Starn and Brown, 2007). 

Groundwater flows laterally through till in upland areas 

to upland streams and wetlands, downward into bedrock 

fractures, and (or) laterally into glacial stratified deposits in 

the valley floor and to the Pomperaug River (figs. 2 and 3). 

Groundwater in glacial stratified deposits discharges to the 

Pomperaug River, to adjacent ponds formed in abandoned 

gravel quarries along the river, and to PSW-1 (fig. 2). A 

gradual increase in withdrawals from in PSW-1 during the 

past 5 years is apparent (Starn and Brown, 2007) and probably 

reflects increased residential demand. Particle simulations 

generated with MODPATH (Pollack, 1994) were used to 

estimate the contributing areas on the basis of 10 particles that 

were backtracked from each monitoring well (figs. 4 and 7, 

and table 9; Starn and Brown, 2007).

EM flowmeter measurements in a 20.7-m deep borehole 

located near PSW-1 showed upward flow during nonpumping 

conditions in two discrete zones near the top and bottom of 

the PSW-1 screen. These zones coincide with coarse sand and 

gravel, as indicated by the gamma log and by geologic log 

descriptions. There was no flow in the silty sand and very fine 

sand deposits between these two zones of preferential flow. 

The flow diminished almost completely during pumping at 

PSW-1, altering the natural upward gradient, but preferential 

flow during nonpumping conditions can affect the source 

of water to the well. Lithologic facies, as well as sediment 

color, were used to explain much of the heterogeneity in 

permeability and extractable Fe and Mn in a glacial fluvial 

aquifer (Sturgeon and others, 2006). The texture and 

structure of the glacial deposits was defined in detail through 

sediment-sample descriptions, results of interpretation of 

the geophysical log and EM flowmeter log, and chemical 

profiles in the continuously screened well WY103 (fig. 8). The 

flowmeter log shows increased flow in the zones between the 

18.1-m and 15.1-m depths in both zones and between the 12-m 

and 9-m depths. It appears that the stratified deposits contain 

some zones of layers, probably only tens of centimeters thick, 

that are more permeable than adjacent zones and function 

as the primary pathways for groundwater flow. The water 

chemistry is different in the 18.1-m-to-15.1-m zone that is 

associated with higher flow than in adjacent zones; the locally 

high specific conductance could be caused by anthropogenic 

contaminant sources such as recharge from a septic-tank 

drainfield. The DO concentrations in this zone also are lower 

than those in adjacent zones and may result from reduction by 

organic C.

The four monitoring wells that were drilled in bedrock 

(figs. 2 and 3) provided information on bedrock fractures 

and fracture flow. Vertical fractures in both the Mesozoic 

rocks in the Pomperaug Basin and the Paleozoic rocks in the 

adjacent uplands trend north-northeast (Burton and others, 

2005) and likely affect groundwater flow at a local scale. 

Stress-relief fractures are nearly horizontal and generally 

decrease with depth, but probably are important on the 

scale of a zone of contribution (Starn and Stone, 2005). 

Groundwater from fractures can discharge directly to surface 

water where bedrock is exposed, but more often, it discharges 

either laterally or vertically into glacial deposits in the valley. 

Some (about 4 percent) flow in upland areas discharges to 

public- and domestic-supply wells (Starn and Brown, 2007). 

Paleozoic rocks to the east of the eastern border fault are 

highly fractured (Burton and others, 2005), although most of 

the fractures observed in well WY86 are filled with secondary 

minerals. Fractures in the Orenaug Basalt tend to be filled 

with calcite and other minerals, and usually are not permeable. 

An eolian sandstone unit within the upper Cass Formation, 

directly beneath the Orenaug Basalt, has a relatively high 

porosity and permeability and may be a substantial pathway 

for preferential flow (Burton and others, 2005). Interbedded 

siltstone and fine sandstone units of the White Oaks Formation 

also contain water-bearing fractures, as observed using an EM 

flowmeter in a deep borehole in Southbury (W.C. Burton, U.S. 

Geological Survey, written commun., 2006). The South Brook 

Basalt is highly vesicular and may be permeable (Burton and 

others, 2005).
24 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

Aquifer Chemistry

The chemical composition of groundwater results from 

reactions with aquifer materials, anthropogenic-constituent 

sources, rates of recharge, and directions and rates of 

groundwater flow. The sections below describe (1) solidphase geochemistry to characterize aquifer material and its 

potential for weathering and other geochemical reactions in 

the aquifer system; (2) groundwater chemistry and age, and 

their spatial distribution to identify the sources and pathways 

of groundwater; and (3) groundwater chemistry in relation 

to groundwater-flow data to evaluate pathways to PSW-1. 

This characterization allows for improved understanding of 

groundwater chemistry in different parts of the aquifer system 

and chemical transport to a public-supply well.

Solid-Phase Geochemistry

The mineralogy, C content, acid-extractable fraction, 

and sorption behavior of subsurface materials were analyzed 

to help assess their effects on groundwater chemistry through 

aquifer weathering and other geochemical reactions, such as 

adsorption. Analyses were done on core samples from the 

glacial aquifer and from the underlying and adjacent bedrock, 

which typically is the “source rock” for the surficial deposits. 

Figure 8. Selected groundwater characteristics measured in well WY103, May 2005, with a water-quality monitor, and 

October 2004, with borehole geophysical tools, in relation to altitude, Woodbury, Connecticut. 

0.0 0.2

Change in upward flow

(gallons per minute per

0.3 meters of borehole 

length) 

9.5 11.0

Temperature

(degrees Celsius)

Dissolved oxygen

 (milligrams per liter)

3 5 6.2 6.4

pH

Screened interval in

adjacent pumping well

200 300 100 130

Natural gamma

(counts per second)

200 275

Specific conductance

(microsiemens per

centimeter at

25 degrees 

celsius)

Specific conductance

(microsiemens per

centimeter at

25 degrees 

celsius)

23.0 23.3

Temperature

(degrees Celsius)

46 46

48

50

52

54

56

58

60

62

64

ALTITUDE, IN METERS ABOVE NAVD 88

48

50

52

54

56

58

60

62

64

ALTITUDE, IN METERS ABOVE NAVD 88

WATER-QUALITY MONITOR, MAY 2005 BOREHOLE GEOPHYSICAL TOOLS, OCTOBER 2004
Aquifer Chemistry 25

Mineralogy

The mineralogy of the unconsolidated deposits is largely 

reflective of the mineral composition of the bedrock sources. 

Natural constituents, including alkalinity, Fe, Mn, As, U, 

Ca, HCO3

-

, and DOC, can be preferentially derived from 

certain source rocks. The type and distribution of the bedrock, 

therefore, can have a substantial effect on groundwater 

chemistry in the glacial aquifer. The mineralogy of surficial 

deposits is highly variable across Connecticut but generally is 

similar to adjacent bedrock (Stone and others, 2005), except 

that surficial deposits have a higher percentage of quartz and 

other minerals that are resistant to weathering. Fragments of 

distinctive sedimentary and igneous rocks of the Pomperaug 

Basin were deposited in an “indicator fan” of glacial deposits 

that extend generally to about 13 km to the southeast of the 

basin (Pessl, 1970). 

The x-ray diffractometry of whole-sample mounts from 

glacial deposits indicates the presence of mostly quartz, 

plagioclase (generally albite), and K feldspar for the bulk 

mineralogy (table 3). The dominance of Na-rich plagioclase 

(albite and oligoclase) over K feldspar is in accordance 

with studies of late Triassic sandstones of the Hartford and 

Pomperaug Basins (Krynine, 1950; Weddle and Hubert, 

1983; Hubert and others, 1992) and in rocks of the Newark 

Basin (Tabakh and Schreiber, 1998), where similar albite-rich 

sandstones were attributed to circulation of Na-rich fluids in 

the distant past. Muscovite and some biotite were abundant 

locally, particularly in sediments derived from bedrock such 

as the Taine Mountain Formation, pegmatite, and possibly 

the Cass and White Oaks Formations. Calcite and calcic 

plagioclase was observed in mineral-filled fractures of the 

Orenaug Basalt. Calcite also is present in calcite-bearing 

units of the South Britain, Cass, and White Oaks Formations 

of the Pomperaug Basin (Burton and others, 2005). Calcite 

was detected in trace amounts (table 3) in the deeper glacial 

deposits (WY75), possibly from mineral-filled fractures of 

underlying Orenaug Basalt or from the Cass Formation. 

Hornblende was detected in trace amounts at four sites, 

WY77, WY92, WY94, and WY100. Results of XRD analysis 

of the clay fractions, which include particles less than 1 mm 

in diameter, indicated the presence of mainly illite, smectite, 

and kaolinite, with lesser amounts of vermiculite, chlorite, 

intergrade smectite, and trace amounts of hornblende. 

Vermiculite is one of the major clay components in gneiss 

from WY92 and WY94, with smaller amounts present in 

WY100 (table 3). Goethite was not detected in either bulk 

or clay-size fraction of the 14 XRD samples, although 

samples from WY81 and WY77 yielded minor amounts of 

ultrafine material, less than 0.03 mm fraction, that consisted 

mainly of poorly crystalline goethite and total clay, with a 

trace of hornblende. Secondary Fe oxides were observed in 

thin sections as oxidized portions of primary Fe oxides, as 

hematite coatings and stains on other minerals, as hematiterich matrix of rock fragments, and as fracture-fill material. 

Hematite was observed in several heavy-mineral separates, 

and poorly crystalline ferric oxyhydroxides were determined 

in acid extractions, as discussed in the next section. Fe-sulfide 

minerals (FeS and (or) FeS2) were observed in one heavymineral separate and some sulfide extractions, and generally 

were associated with localized reducing zones beneath 

wetlands (WY100) or near the water table (WY94; tables 4 

and 5).

Results of heavy-mineral analysis were used to help 

determine the presence of more reactive mineral phases 

that might affect groundwater chemistry (table 4). The 

small number of samples precludes a detailed analysis of 

provenance. The heavy-mineral content of sample fractions 

from glacial deposits is estimated to range from 2 to 

10 percent of total sample weight. Heavy minerals in the 

slightly magnetic to nonmagnetic fractions include quartz (that 

contains inclusions or is part of rock fragments), amphibole/

pyroxene, zircon, sphene, epidote, biotite, muscovite, garnet, 

kyanite, rutile, tourmaline, and apatite (table 4). 

Sediment Extractions

Acid extractions were performed on sediments and 

rock samples to determine concentrations of Fe, Mn, and 

other trace elements, including As, U, Cu, and Pb, within 

solid phases (table 5). Concentrations and oxidation states 

of Fe and Mn can be used to assess the redox environment 

in the part of the aquifer from which the sample was 

taken. Concentrations of 0.5-M HCl-HA-extractable Fe 

(total) coatings (780 to 1,500 mg/g of sample) and 6-M 

HCl-extractable Fe (total) coatings (490 to 11,000 mg/g 

of sample) indicate that sediments can be rich in Fe and 

generally are consistent with predominantly oxic conditions 

(table 5). The 6-M HCl-extractable Fe (total) fraction, 

which indicates the amounts of both crystalline and poorly 

crystalline Fe coating, generally is 5 to 10 times greater 

than the 0.5-M HCl-HA-extractable Fe, which indicates 

the amount of poorly crystalline Fe(III) in the sample and 

also, presumably, the most microbially reactive Fe fraction 

(table 5). Concentrations of 6-M HCl-extractable Mn (total) 

coatings (less than 0.1 to 360 mg/g of sediment) generally are 

20 to 120 times smaller than those of 6-M HCl-extractable 

Fe (total) coatings (table 5), and the coatings generally are 

consistent with relative concentrations of dissolved Fe and Mn 

in oxic and Fe- or Mn-reducing conditions in groundwater. 

In the water samples that indicated reducing conditions, the 

dissolved Mn concentrations were 2 to 90 times higher than 

were the dissolved Fe concentrations.

Concentrations in the 6-M HCl extractions of sediments 

in samples from WY100 at the 16-m depth were high 

relative to those in sediments from other sites for almost 

all constituents analyzed, including Al, Ca, Mg, K, Na, Cr, 

Cu, U, Ni, and V (table 5). The 6-M HCl extractions for 

sediments from WY90 at the 6.7-m depth also yielded high 

concentrations of Ca, as well as Mg, Na, K, Cu, and Al, 

which may reflect the composition of the till, the proximity 

to bedrock, and (or) the relatively high concentrations of 
26 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

Table 3. Relative mineralogical abundances, based on x-ray diffraction (XRD), of core samples from boreholes in the Woodbury, 

Connecticut, study area, 2003–04.

[Lower integers indicate higher relative abundance. Zero indicates absence; ID, identifier; tr, or trace, indicates less than 1 percent; tr?, indicates a possible 

trace; bls, below land surface; bedrock wells shaded gray]

Well ID Depth bls 

(meters)

Relative abundance of bulk minerals

Quartz Plagioclase K-feldspar Total clay Calcite Mica Hornblende

WY72 18.3 1 2 0 3 0 0 0

WY72 18.3 2 1 0 3 0 0 0

WY75 16.8 1 2 3 6 tr 4 0

WY77 12.2 2 1 3 4 0 0 tr

WY81 5.9 1 2 3 4 0 0 0

WY86 7.0 1 3 tr 4 0 2 0

WY86 15.8 1 2 3 tr 0 4 0

WY87 12.2 2 1 0 3 0 0 0

WY90 7.0 1 2 3 4 0 0 0

WY92 4.0 1 2 3 4 0 0 0

WY92 16.5 1 2 3 4 0 0 tr

WY94 4.6 2 1 3 4 0 0 tr

WY100 3.0 1 3 2 4 0 0 tr

WY100 7.9 1 2 3 4 0 0 0

WY100 16.2 1 2 3 4 0 0 0

Well ID Depth bls 

(meters)

Relative abundance of clays less than 1 micron in size

Smectite Intergrade 

smectite Illite Kaolinite Chlorite Vermiculite Hornblende

WY72 18.3 1 0 tr 0 tr 0 0

WY75 16.8 2 0 1 3 4 0 tr

WY77 12.2 2 0 1 3 4 0 0

WY81 5.9 2 0 1 3 4 0 tr

WY86 7.0 1 0 3 4 2 0 0

WY86 15.8 0 0 1 tr tr? 0 0

WY87 12.2 1 0 3 2 4 0 tr

WY90 7.0 2 0 1 3 4 0 tr

WY92 4.0 2 0 1 3 4 0 tr

WY92 16.5 3 6 1 4 5 2 tr

WY94 4.6 4 6 1 3 5 2 tr

WY100 3.0 ? 4 1 2 5 3 tr

WY100 7.9 3 5 1 2 6 4 tr

WY100 16.2 3 0 1 2 4 0 tr

Well ID Depth bls 

(meters)

Relative abundance of clays less than 0.03 micron in size

Smectite Goethite Illite Kaolinite Chlorite Hornblende

WY77 12.2 2 1 tr? tr? 0 0

WY81 5.9 2 1 tr? tr? 0 tr
Aquifer Chemistry 27

dissolved solids derived from septic-tank drainfields. The 

6-M HCl extractions for sediments from WY83 had relatively 

high concentrations of U (0.5 mg/g), As (1.6 mg/g), and Cd 

(0.07 mg/g), but the 10-percent HNO3 extractions had even 

higher concentrations of U (11 mg/g) and Cd (9.6 mg/g). The 

discrepancy between the two types of extractions probably 

reflects the effect of the acid type and strength on the leaching 

of mineral coatings, which can vary considerably (Heron and 

others, 1994). Cd concentrations were high in the Cass 

Formation relative to that in other rocks in the Pomperaug 

Basin, based on whole-rock analysis (W.C. Burton, U.S. 

Geological Survey, written commun., 2006). Arsenic 

concentrations in 10-percent HNO3 extractions of sediments 

from WY83 also were much higher than in other sediments, 

indicating that the sediments were derived from the Cass 

Formation, which has mapped units less than 200 m to the 

northwest (fig. 7). Units in the Newark Supergroup can be 

organic rich and have high concentrations of As, U, and 

other trace elements (Vine and Tourtelot, 1970; Coveney and 

Martin, 1983), although trace elements in most samples of 

carbonaceous (organic-rich) shales of the Newark Supergroup 

are associated with the inorganic clay fraction and not directly 

with organic matter (Dean, 1988). For example, Szabo 

and Zapecza (1991) observed U enrichment in comparable 

calcareous black mudstone units within the Newark 

Supergroup of central New Jersey. Turner-Peterson (1977) 

hypothesized that uranyl ions were carried into the Newark 

Basin by groundwater, then the U was reduced by humic 

matter and dissolved sulfides (H2S and HS-) from U(VI) to 

U(IV), thereby decreasing the solubility and immobilizing U 

in the organic-rich sediments. A similar enrichment may have 

occurred in the Pomperaug Basin, since U-rich crystalline 

rocks and organic-rich sediments were both present in the 

source and the sink for U. Dilute waters migrated into the 

depositional basin where evaporative concentration during 

semiarid to arid climate conditions yielded brines; Hubert and 

others (1978) found ghost clasts of halite and gypsum that had 

been replaced by calcite or silica, indicating the past existence 

of brine. 

A rock sample from a fractured pegmatite at WY86 near 

the eastern border fault had high concentrations of constituents 

extracted with 10-percent HNO3, including As (0.29 mg/g) and 

U (0.45 mg/g), that were high compared with concentrations 

extracted from the Taine Mountain Formation host rock of 

0.098 mg/g for As and 0.44 mg/g for U (table 5). The pegmatite 

extends from depths of 13 m to 30 m below land surface in the 

host rock schist/gneiss (Taine Mountain Formation) (figs. 2, 3, 

and fig. 2–1). The Taine Mountain Formation had the highest 

concentration of Pb (8.3 mg/g) and a high concentration of 

Fe (4,200 mg/g) in extracts leached with 6-M HCl (table 5). 

Crystalline rocks, particularly biotite-muscovite (two-mica) 

granite and other high-grade metamorphic rocks, typically 

have high concentrations of U and 222Rn (Hollocher and 

Yuskaitis, 1993). Intrusive bodies of two-mica granite or 

pegmatite are common north and west of the basin (Burton 

and others, 2005); an intrusive rock north of the study area, 

mapped as the Nonewaug Granite (Gates, 1954), contains 

high concentrations of 222Rn and U (Dupuy and others, 1991). 

Concentrations of 222Rn and U in the northeastern glacial 

aquifers and New England crystalline aquifers are among the 

highest for principal aquifers of the United States (Ayotte and 

others, 2007). 

A rock sample from well WY87 was chemically 

correlated to the Orenaug Basalt by Burton and others (2005). 

Table 4. Mineralogy of slightly magnetic and nonmagnetic heavy-mineral separates based on analysis by petrography and spectra of 

aquifer material from boreholes in the study area, Woodbury, Connecticut, 2003–04.

[ID, indicates identifier; bls, below land surface. Separated fractions: magnetic, C1; slightly magnetic, C2; nonmagnetic, C3; %, percent.]

Well ID Depth bls 

(meters) Heavy-mineral separates

WY75 16.8 C-3: 40% sphene, 30% amphibole/pyroxene, 10% quartz, trace tourmaline, epidote, muscovite 

C-2: 50% garnet, 50% amphibole/pyroxene, trace epidote

WY77 12.2 C-3: 90% quartz, 10% amphibole/pyroxene C-2: 90% amphibole/pyroxene 10% (garnet, 

epidote, sphene)

WY81 5.9 C-3: 50% sphene, 30% zircon, some amphiboles, quartz, rutile, and kyanite

WY94 4.6 C-3: 80% quartz, 20% amphibole/pyroxene, trace sphene, zircon, muscovite, and pyrite

WY100 7.9 C-3: 30% amphibole/pyroxene, 30% sphene, 20% quartz, 10% (zircon, muscovite, hematite, 

garnet) C-2: 80% garnet, 10% amphibole/pyroxene, and 10% hematite

WY100 16.2 C-3: 80% amphibole/pyroxene, 10% zircon, 10% (quartz, sphene, apatite), and trace epidote 

and tourmaline
28 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

Table 5. Selected constituents in acid extractions and organic carbon, and analysis of bulk density and pore-water constituents of aquifer 

material from boreholes in the study area, Woodbury, Connecticut, 2003–04.

[Concentrations in micrograms per gram of sediment unless otherwise indicated; ID, indicates identifier; bls, below land surface; M, moles per liter; g/cc, 

grams per cubic centimeter; %, percent; Fe, iron; Mn, manganese; As, arsenic; U, uranium; Al, aluminum; Ca, calcium; Cr, chromium; Cu, copper; K, potassium; 

Mg, magnesium; Na, sodium; Ni, nickel; Pb, lead; V, vanadium; Zn, zinc; Cd, cadmium; HNO3, nitric acid; HCl, hydrochloric acid; HA, hydroxylamine; δ13C, 

delta carbon-13; C, carbon; δ15N, delta nitrogen-15; --, not measured; bedrock wells shaded gray; <, less than]

Well 

ID

Depth 

bls 

(meters)

Chemical extractions

Fe(II) 

(0.5-M 

HCl)1

Fe (total) 

(0.5-M 

HCl HA)2

Fe(III)3

Sulfides 

(AVS+ 

CRS)4

Fe 

(10% 

HNO3)

5

Mn 

(10% 

HNO3)

As 

(10% 

HNO3)

U 

(10% 

HNO3)

Cd 

(10% 

HNO3)

Pb 

(6-M 

HCl)6

Fe 

(6-M 

HCl)

Mn 

(6-M 

HCl)

U 

(6-M 

HCl)

Al 

(6-M 

HCl)

Ca 

(6-M 

HCl)

Cr 

(6-M 

HCl)

Cu 

(6-M 

HCl)

WY72 0.3 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

WY72 0.9 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

WY72 1.5 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

WY72 2.1 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

WY72 18.3 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

WY75 0.3 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

WY75 0.9 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

WY75 1.5 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

WY75 2.1 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

WY75 17.1 780 670 -110 0.76 2,100 110 0.071 0.093 6.4 0.96 5,400 51 0.20 2,000 740 3.8 4.4

WY77 12.5 840 790 -50 0.84 2,300 170 0.12 0.380 10 1.30 5,100 80 0.41 2,700 800 4.7 3.9

WY 81 0.3 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

WY 81 2.1 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

WY 81 3.4 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

WY 81 4.0 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

WY 81 5.9 1,500 1,500 0 1.5 2,200 180 0.10 0.210 11 1.60 5,500 109 0.41 2,736 981 5.0 3.5

WY83 6.4 -- -- -- -- -- -- 1.60 11 10 4.79 -- -- 0.07 -- -- -- --

WY83 7.9 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

WY83 8.1 -- -- -- -- -- -- -- -- -- -- 22,000 150 0.53 4,700 1,300 8.2 10

WY86 6.9 -- -- -- -- -- -- 0.098 0.44 18 8.45 4,200 62 0.39 2,600 1,200 3.0 4.6

WY86 15.8 -- -- -- -- -- -- 0.29 0.45 17 1.89 490 < 0.5 0.36 250 900 < 0.5 5.1

WY87 0.9 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

WY87 1.5 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

WY87 12.2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

WY90 7.0 1,300 1,500 200 1.7 -- -- 0.13 0.2 6 1.12 8,200 210 0.23 3,700 5,200 6.0 10

WY92 4.0 1,000 940 -60 1.3 -- -- 0.16 0.24 7.3 1.31 8,000 170 0.37 4,200 780 5.8 14

WY92 16.5 920 680 -240 1.20 -- -- 0.18 0.18 8.9 0.78 4,800 83 0.25 2,100 1,300 3.8 5.3

WY 94 4.3 1,100 1,100 0 1.0 -- -- 0.16 0.3 10 1.02 4,900 110 0.37 2,400 1,100 3.4 6.7

WY100 3.0 800 1,000 200 710 -- -- 0.35 0.84 70 0.84 4,100 33 0.50 3,300 480 4.3 4.3

WY100 7.9 890 920 30 1.1 -- -- 0.220 0.24 21 1.42 6,800 360 0.33 2,400 610 5.4 8.7

WY100 16.2 1,200 1,300 100 0.86 -- -- 0.063 0.16 18 1.15 11,000 310 0.56 5,800 4,300 6.2 9.2

1

Measured after extraction with 0.5-M HCl.

2

Measured after extraction with 6-M hydroxylamine (HA) in 0.5-M HCl.

3

Calculated as Fe(total) minus Fe(II).

4

Measured acid-volatile and chromium-reducible sulfides after extraction by method modified from Allen and others (1991; 1993).

5

Measured after extraction with 10% HNO3.

6

Measured after extraction with 6-M HCl.
Aquifer Chemistry 29

Table 5. Selected constituents in acid extractions and organic carbon, and analysis of bulk density and pore-water constituents of 

aquifer material from boreholes in the study area, Woodbury, Connecticut, 2003–04.—Continued

[Concentrations in micrograms per gram of sediment unless otherwise indicated; ID, indicates identifier; bls, below land surface; M, moles per liter; g/cc, 

grams per cubic centimeter; %, percent; Fe, iron; Mn, manganese; As, arsenic; U, uranium; Al, aluminum; Ca, calcium; Cr, chromium; Cu, copper; K, potassium; 

Mg, magnesium; Na, sodium; Ni, nickel; Pb, lead; V, vanadium; Zn, zinc; Cd, cadmium; HNO3, nitric acid; HCl, hydrochloric acid; HA, hydroxylamine; δ1C, delta 

carbon-13; C, carbon; δ15N, delta nitrogen-15; --, not measured; bedrock wells shaded gray; <, less than]

Chemical extractions Reston stable isotope laboratory Physical analyses

K 

(6-M 

HCl)

Mg 

(6-M 

HCl)

Na 

(6-M 

HCl)

Ni 

(6-M 

HCl)

Pb 

(6-M 

HCl)

V 

(6-M 

HCl)

Zn 

(6-M 

HCl)

Cd 

(6-M 

HCl)

d13C of 

total C 

(per mil)

Total C 

(weight 

%)

d13C of 

calcite 

C

 (per 

mil)

Organic 

C 

(weight 

%)

d13C of 

Organic 

C (per 

mil)

d15N of 

total 

N (per 

mil)

Total N 

(weight 

%)

Loss on 

ignition 

(weight 

%)

Bulkdensity 

solids 

(g/cc)

Moisture 

content 

(volumetric 

%)

-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 4.4 1.3 0.45

-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 0.4 1.6 0.31

-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 3.0 1.6 0.29

-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 0.8 2.0 0.58

-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 6.4 0.9 0.33

-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 1.4 1.6 0.30

-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 1 1.4 0.33

-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 1.2 1.7 0.25

550 1,100 38 4.8 3.0 6.2 7.4 -- -- -- -- -- -- -- -- -- -- --

720 1,100 36 5.2 3.2 5.5 7.3 -- -- -- -- -- -- -- -- -- -- --

-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 1.8 1.6 0.03

-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 0.6 1.3 0.14

-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 0.8 1.7 0.14

-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 3.0 1.6 0.28

630 1,200 61 5.4 3.4 8.5 7.7 -- -- -- -- -- -- -- -- -- -- --

-- -- -- -- 1.10 -- -- 0.070 -- -- -- -- -- -- -- 0.8 -- --

-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

880 1,800 -- 11 2.5 -- 16 0.110 -- -- -- -- -- -- -- -- -- --

800 1,900 85 7.9 8.30 7.4 < 0.5 0.020 -- -- -- -- -- -- -- -- -- --

130 61 40 4.5 2.40 2.1 < 0.5 0.024 -- -- -- -- -- -- -- -- -- --

-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 3 1.9 0.16

-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 1.8 1.6 0.16

-- -- -- -- -- -- -- -- -12.7 0.4 -8.52 0.08 -26.9 -- 0.01 -- -- --

850 2,400 95 6.8 1.40 16 13 0.026 -11.1 0.17 -7.34 0.06 -24.8 -- 0.01 -- -- --

1,200 1,700 45 8.4 1.20 11 17 0.017 -27.9 2.05 -- 2.7 -27.9 2.83 0.11 -- -- --

660 1,000 26 6.4 0.98 7.9 < 0.5 0.014 -25.6 0.15 -- 0.15 -26.3 -- 0.01 -- -- --

590 920 27 7.1 1.20 10.1 8.4 17 -23.5 0.06 -- 0.06 -- -- 0.01 -- -- --

160 1,200 94 7.5 1.10 14 18 0.07 -18.9 0.05 -- 0.04 -22.8 -- 0.01 -- -- --

490 940 32 8.6 1.60 9.3 9.0 0.027 -23.3 0.06 -- 0.07 -24 -- 0.01 -- -- --

1,700 4,000 130 11 1.50 31 32 0.028 -22.8 0.06 -- 0.05 -23.9 -- 0.01 -- -- --
30 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

1.0 mm

A

B

The upper part of the borehole below the thin glacial till 

is a highly weathered, gray-green unconsolidated material 

(saprolite) that grades to a massive fine-grained basalt 

containing abundant amygdule vesicles filled with secondary 

minerals, similar to those described by Garabedian and others 

(1996) that contained calcite, quartz, prehnite, pumpellyite, 

apophyllite, and other minerals. Most of the these vesicles are 

filled and did not yield water, but one or two fractures at the 

12.2- to 12.5-m depth that are tilted eastward about 15 degrees 

yielded about 0.8 L/min. The fractures are consistent with 

the strata. Below this zone is massive basalt with no fractures 

evident; it may represent the lower member of the Orenaug 

Basalt. To the southeast, the basalt is brecciated and highly 

altered as a result of its close proximity to the eastern border 

fault, which parallels and probably underlies South Brook 

(Burton and others, 2005). The basalt contains 

abundant secondary silica, chlorite, and calcite. 

Two former Cu prospects are located to the west 

of WY86 and across South Brook. Whole-rock 

analysis of a sample from 23-m depth showed 

relatively low concentrations of As at 1.7 mg/g, U 

at less than the detection limit, and Cu at 50 mg/g. 

A sample collected from the lower member of the 

Orenaug Basalt by Burton and others (2005) had an 

As concentration of 5.1 mg/g.

Fission-Track Radiography

Most sediment grains in core samples 

consisted of quartz and feldspar and did not show 

much evidence of U; however, some reddish 

Fe-oxide grains appeared to have much higher 

U concentrations, which were estimated using 

fission-track radiography. Fission-track maps 

were produced from epoxy-mount thin sections of 

core samples to determine the distribution of U. 

A fission-track map of sediments from the 17-m 

depth at WY75 (fig. 9), for example, shows the 

U distribution in ferric hydroxide coatings on 

sediment grains. These sediments may be derived 

from Mesozoic rocks, such as the Cass Formation, 

and are similar to sediments near WY83. Estimated 

U content is on the order of 10 to 100 mg/g, based 

on fission-track density (Brown and Zielinski, 

2004). The overall abundance of such oxides is 

low, and their fractional contribution of U to the 

total U inventory in the rock is probably less than 

a few percent, but emanation of 222Rn from such 

sites could account for a large fraction of total 

222Rn emanation. The distribution of U in the 

aquifer material implies the co-occurrence of U 

progeny such as Ra. 222Rn, which is derived from 

the decay of 226Ra, was present at high activities in the 

glacial aquifer and crystalline rock in upland areas, as 

discussed later in the “Naturally Occurring Constituents 

of Concern” section.

Carbon Content

The organic-C content of core samples from the 

Pomperaug aquifer system generally was low, although 

sediments at some sites had concentrations greater than 

3 percent by weight (table 5). Higher organic-C content 

generally is consistent with groundwater samples that contain 

relatively high, natural DOC concentrations (Brown and 

others, 2006). Organic-matter content also was measured in 

shallow, unsaturated-zone deposits by loss-on-ignition; these 

values range from about 0.4 percent to 4.4 percent by weight 

and reflect the high organic content typical of the soil zone 

(table 5). Several exceptions to this vertical distribution of 

organic C include the WY92 well site, where organic-rich 

Figure 9. Optical microscope images of a sample of glacial deposits 

from 17 meters depth from land surface at borehole WY75, showing (A) 

an iron-oxide grain, and (B) fission tracks recorded after irradiation with 

uranium-235 on the same sample, Woodbury, Connecticut.
Aquifer Chemistry 31

sediment was observed at the water table from 3.6 to 4.3 m 

and reflects buried wetland deposits. Similarly, a core sample 

from a depth of 2.7 to 3.4 m below land surface at WY100 

had a high observed organic-matter content, but that is not 

reflected in the subsample analyzed (table 5). At WY83, 

sediments in a blackish red, 6-cm layer in the core from the 

6.1 to 6.7 m depth, appeared to be dark and organic rich, and 

a subsample from this depth interval had a weight loss-onignition result of 0.8 percent (table 5). Groundwater samples 

from the WY83 well screen adjacent to this depth were high 

in DOC, and redox conditions typically were anoxic; these 

results reflect the presence of source material from the Cass 

Formation, as discussed in the section “Surficial Geology.” 

A mineralized fault exposed at a quarry about 1.9 km to the 

north of WY83 contains bitumen, as well as quartz, calcite, 

stilbite, and other secondary minerals (Burton and others, 

2005). The Shuttle Meadow Formation, the equivalent unit to 

the Cass Formation in the Hartford Basin, contains a normal 

distribution of saturated hydrocarbons (Kotra and others, 

1988; Dickneider and others, 1996), and similar units of the 

Newark Supergroup in eastern North American rift basins 

have some hydrocarbon potential (Ziegler, 1983).

The d13C values for total C in core samples ranged from 

-28 to -11 per mil. d13C values of organic C ranged from 

-28 to -23 per mil; these values are similar to those in the 

Newark and Culpeper Basins (-27 to 20.7) and may indicate 

lacustrine-algal deposits (Spiker, 1985). In the Hartford 

Basin, caliche calcites in fluvial mudstones have d13C isotopic 

compositions ranging from -7.3 to -3.8 per mil, indicating that 

paleosol processes occurred during warm and dry climatic 

conditions in Late Triassic time (Suchecki and others, 1988). 

Only two of the eight samples that were submitted contained 

enough calcite for analysis of d13C: a till from WY90 and a 

mineralized basalt fracture at WY87 had values of -7.34 and 

-8.52, respectively. 

Adsorption Reactions

Experimental data for adsorption batch-reactor 

experiments were modeled using PHREEQC (Parkhurst 

and Appelo, 1999) with the generalized two-layer surface 

complexation model of Dzombak and Morel (1990) to 

determine adsorption reactions. Solution composition and 

adsorption site density were included as known quantities. 

Equilibrium constants for the surface-complexation reactions 

used to simulate As(V) and U(VI) adsorption were adjusted to 

give the best fit to experimental results for WY100 (table 6). 

These equilibrium constants then were used to simulate the 

experimental results for the remaining sediment samples.

The results of column experiments indicate that 

substantial adsorption occurred for the four samples of the 

glacial stratified deposits (WY83, 92, 94, and 100), and 

much less adsorption occurred for the glacial till (WY90). 

Isotherms for As(V) adsorption by sediments are plotted 

in figure 10A. Surface-complexation equilibrium constants 

were adjusted to give the best fit to data from the experiment 

with WY100 sediments (table 6B). These constants then 

were used to model As(V) adsorption by the other sediment 

samples. It was assumed that all adsorption occurred at weak 

surface sites, characteristic of anion adsorption (Dzombak 

and Morel, 1990). The model accurately simulated adsorption 

by aquifer sediments from WY83, WY92, and WY94; 

however, the model predicted more adsorption by sediments 

from WY90 than was observed. Two possible explanations 

for the overpredicted adsorption are that core sediment from 

WY90 (1) represents glacial till and may have a different 

assemblage of sorption sites with respect to As(V) than 

the four samples collected from glacial stratified deposits, 

and (2) was downgradient from a septic-tank drainfield 

and the sediment may have been exposed to groundwater 

with solutes that strongly sorbed to the sediment, thereby 

blocking As(V) adsorption. The concentration of As(V) 

on surface sites measured by H+ titration for WY90 was 

160 micromoles per liter (mM/L), although the surfacesite As(V) concentration that gave the best match to the 

experimental data was only 26 mM/L (fig. 10A). This indicates 

the presence of a solute that blocked As(V) adsorption but 

not H+ or an assemblage of adsorption sites that differed 

in response to As(V) and H+ than those on the four glacial 

stratified sediment samples. Carbonate minerals were apparent 

in the WY90 sediment, and although the H+ titration was 

adjusted to take this into account, it is possible there was still 

some carbonate associated with surface sites that blocked 

As(V) adsorption.

U(VI) also was strongly adsorbed by the four samples 

of glacial stratified deposits (fig. 10B). The same modeling 

technique used for As(V) was applied to U(VI) adsorption 

with similar results. Because uncomplexed U(VI) occurs as 

the UO2

+2 cation, strong sorption sites were included (table 6). 

The concentration of strong sorption sites was estimated to 

be 2.5 percent of the weak-site concentration (Dzombak and 

Morel, 1990). In the presence of carbonate ions, the dominant 

U(VI) species in solution are UO2(CO3)3

4- and UO2

(CO3)2

2-, 

and these species are adsorbed by the weak sites.

Surface-complexation equilibrium constants (table 6B) 

fit to the WY100 isotherm also simulated U(VI) adsorption 

by the other glacial-stratified deposit samples reasonably 

well, but overpredicted adsorption by sediments from WY90. 

Even the lower site concentration of 26 mM/L used for As(V) 

resulted in overpredicted U(VI) adsorption. In fact, there was a 

net release of U(VI) to solution in the experiment with WY90 

sediments. It is possible some U(VI) coprecipitated with the 

carbonate minerals in the sediment and was released during 

the adsorption experiment.

Groundwater Chemistry

Water-chemistry constituents measured in the glacial 

aquifer system include major and trace constituents, 

radionuclides, stable isotopes, and dissolved gases, VOCs 

and pesticides, and age tracers. The groundwater chemistry 
32 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

Table 6. Results of adsorption experiments on aquifer material sampled in the study area, including (A) the pH, bicarbonate, and 

surface sorption site concentrations for arsenic (V) and uranium (VI), and (B) equilibrium constants for PHREEQC model of adsorption 

using experimental data.

[ID, indicates identifier; bls, below land surface; mmol/L, millimoles per liter; mg/L, milligrams per liter; As, arsenic; U, uranium; K, equilibrium constant; 

Site_wOH, weak sorption sites; Site_sOH, strong sorption sites]

A B

Well 

ID

Depth 

bls 

(meters)

Description Species 

analyzed

Average 

pH1

HCO3

-

(mg/L)1

Concentration 

(mmol/L) Adsorption Reaction Log K

 Site_wOH2 Site_sOH3

WY83 7.3 Medium sand, 

some silt

As(V) 7.09 100 160 0 Site_wOH + H+ = Site_wOH2+ 17.29

WY83 U(VI) 6.95 100 156 4 Site_wOH = Site_wO- + H+ 1-8.93

WY90 6.7 Glacial till As(V) 8.38 186 164 0 Site_sOH +H+ = Site_sOH2+ 17.29

U(VI) 8.29 189 160 4 Site_sOH = Site_sO- + H+ 1-8.93

As(V) 8.38 186 26.04 0 As(V) (arsenate)

U(VI) 8.29 189 25.44 0.6 Site_wOH + AsO4

-3 + 3H+

 = 

Site_wH2AsO4 + H2O

2

29.31

WY92 3.7 Sand As(V) 7.06 97.6 78 0 Site_wOH + AsO4

-3 + 2H+

 = 

Site_wHAsO4

-

 + H2O 

2

23.81

U(VI) 6.97 100 76 2 Site_wOH + AsO4

-3 + H+

 = 

Site_wAsO4

-2 + H2

O 

2

16.65

WY94 4.3 Fine sand As(V) 7.00 128 47 0 Site_wOH + AsO4

-3 = 

Site_wOHAsO4

-3 

2

8.53

U(VI) 6.92 87 45.2 1.8 U(VI)

 WY100 15.8 Fine sand As(V) 7.22 104 61 0 Site_sOH + UO2

+2 = 

Site_sOUO2

+

 + H+ 

2

5.90

U(VI) 6.99 110 59.5 1.5 Site_wOH + UO2

+2 = 

Site_wOUO2

+

 + H+ 

2

3.54

1

Values were measured after 5-day equilibration period.

2

Total surface site concentrations determined by H+ titration. Site_wOH represents weak surface 

sites and Site_sOH represents strong surface sites (used only for U(VI) sorption).

3

Assumes that strong sites are 2.5 percent of total site concentration (Dzombak and Morel, 1990).

4

Surface site concentration that gave best fit to experimental data.

Site_wOH + UO2

+2 + CO3-2 = 

Site_wOUO2HCO3 

2

-14.08

Site_wOH + UO2

+2 + CO3-2 = 

Site_wOUO2CO3

-

 + H+ 

2

-16.35

HCO3-

Site_wOH + CO3

-2 + 2H+

 = 

Site_wHCO3 + H2O 

2

10.56

Site_wOH + CO3

-2 + H+

 = 

Site_wCO3

-

 + H2O

2

15.62

1

Equilibrium constants from Dzombak and 

Morel (1990).

2

Equilibrium constants fit to experimental data for 

sediment sample WY100.
Aquifer Chemistry 33

0 50 100 150 200 250 300 350

A

B

0

WY83

WY83, simulated

WY90

WY90, simulated

WY92

WY92, simulated

WY94

WY94 simulated

WY100

WY100, simulated

WY90, simulated, best fit

ARSENIC (V) CONCENTRATION, IN MICROGRAMS PER LITER

CONCENTRATION OF SORBED ARSENIC,

 IN MICROGRAMS PER GRAM

1

3

5

7

9

0 100 200 300 400 500 600 700

-2

0

2

4

6

8

10

12

WY83

WY83, simulated

WY90

WY90, simulated

WY92

WY92, simulated

WY94

WY94, simulated

WY100

WY100, simulated

WY90, simulated, best fit

Glacial till

Glacial till

URANIUM (VI) CONCENTRATION, IN MICROGRAMS PER LITER

CONCENTRATION OF SORBED URANIUM,

 IN MICROGRAMS PER GRAM

EXPLANATION

EXPLANATION

Figure 10. Concentrations of (A) arsenic (V) in water as a function of arsenic sorbed, and (B) uranium (VI) in water as a function of 

uranium sorbed, based on column experiments of core sediments from WY83 (7.3 meters depth below land surface), WY90 (6.7 meters

depth below land surface), WY92 (3.7 meters depth below land surface), WY94 (4.3 meters depth below land surface), and WY100 

(4.8 meters depth below land surface), and simulated sorption for these samples using PHREEQC (Parkhurst and Appelo, 1993). 
34 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

of this glacial aquifer system is primarily affected by 

weathering of aquifer material and associated naturally 

occurring constituents of concern, and by anthropogenic 

sources, including road salt, leachate from septic-tank 

drainfields (or septic-system leachate), leaking underground 

storage tanks, chemical spills, and stormwater runoff from 

roads and parking lots to dry wells or losing streams. Several 

tools were used to help distinguish anthropogenic sources or 

pathways from natural ones, including Piper diagrams, scatter 

plots, Cl:Br ratio plots, stable isotopes, dissolved gases, and 

groundwater age tracers. Differences in chemical signatures 

among the parts of the aquifer system are used to improve the 

understanding of groundwater-flow patterns and pathways, 

and to test hypotheses for processes that affect water quality in 

well PSW-1.

Major Elements and Nutrients

Groundwater in the glacial aquifer within the study 

area is generally a Ca, Na, Mg-(HCO3)0-2 water and reflects 

the weathering from natural sources and constituents 

derived from anthropogenic sources or activities (table 7). 

Groundwater samples had a median specific conductance of 

278 mS/cm but ranged from 104 mS/cm near a losing stream 

to 1,530 mS/cm near a septic-tank drainfield. Glacial stratified 

deposits contribute most of the groundwater to PSW-1; the 

water was mostly oxic, had a low-to-neutral pH range (5.6 to 

6.9), and was undersaturated with respect to calcite (table 7). 

However, the chemistry of groundwater in the glacial aquifer 

is affected by groundwater in underlying and adjacent till 

and bedrock that can impart higher pH and dissolved CO2, 

reducing conditions, and higher specific conductance (table 7; 

fig. 11). Concentrations of SO4

2− and some trace constituents 

(table 8) can be high in groundwater from fractured bedrock 

that underlies the valley bottom and can affect groundwater 

chemistry in the glacial aquifer. 

Shallow groundwater (greater than 3 m above bedrock) 

has a distinctly different chemistry than deep groundwater 

(within 3 m of bedrock or deeper) in glacial stratified deposits, 

glacial till, and bedrock. Shallow groundwater has higher 

specific conductance (and, therefore, dissolved solids) than 

deep water and appears to be affected by septic-system 

leachate, application of road salt, and other anthropogenic 

sources (fig. 11). On the basis of a one-factor ANOVA, the pH 

was significantly higher in water samples from wells finished 

in bedrock and glacial deposits adjacent to bedrock than it was 

in shallow and intermediate (herein referred to as “shallow”) 

parts of the glacial aquifer (fig. 12A). Also, the HCO3

-

concentration was significantly higher in samples from wells 

finished in bedrock and glacial deposits adjacent to bedrock, 

with the exception of well WY106. The locally calcareous 

composition of mineral-filled basalt fractures and gneiss, 

schist, and pegmatite (tables 3 and 5) likely caused the higher 

pH of groundwater in bedrock and adjacent deep glacial 

deposits. The pH is an important factor in the occurrence and 

movement of natural contaminants, such as As, U, and other 

trace elements. The aquifer system can be categorized by 

depth and (or) aquifer material into zones of distinct ranges 

of pH (table 7). The pH differences probably can be attributed 

to anthropogenic sources, groundwater age, and water-rock 

interaction, particularly in areas where the aquifer matrix 

contains calcite or dolomite, such as in basalt fractures. The 

pH zones are (1A) shallow depths, where the pH of water 

typically is 5.3 to 6.4, and (1B) deep glacial depths within 

3 meters of bedrock, where the pH of water typically is in 

the range of 6.4 to 7.5 (table 7). Groundwater samples from 

wells screened in compact till typically have higher pH of the 

deep glacial zone 1B, including shallow wells such as WY89. 

Groundwater in fractured bedrock can be divided into (2A) the 

upper 100 ft of bedrock, where pH ranges from 6.9 to 8.3, and 

(2B) deep bedrock, where the pH is about 9.

Major-ion concentrations in groundwater samples 

from wells screened in the lower part of the glacial stratified 

deposits, or in glacial till, generally reflect those of underlying 

bedrock, as observed on a Piper diagram (fig. 13). The Piper 

diagram (Hem, 1992) is used to show the clustering of 

samples by water type, and the effects of aquifer weathering 

and anthropogenic activities on major ion concentrations; 

samples are represented by the percentages of total cations and 

total anions, plotted on separate trilinear plots, then projected 

onto a central diamond (Hem, 1992). The ion percentages 

for most deep glacial aquifer wells plotted close together, 

whereas those for the shallow depth wells of the same cluster 

are relatively scattered on the diagram. Groundwater samples 

from wells in deep glacial deposits, till, and bedrock show 

greater percentages of Ca and HCO3

-

 (fig. 13) and reflect 

weathering of calcite in bedrock. The deep glacial well 

WY82 is an exception to this grouping and may reflect a large 

downward gradient at this site, coupled with the location at 

an intersection of roads and, therefore, vulnerability to roadsalt runoff. Concentrations of HCO3

-

 and SiO2, which also is 

a product of weathering, were plotted to help determine the 

relative extent of aquifer weathering (fig. 14A). 

The extent of aquifer weathering also can be 

approximated by the groundwater residence time. The 

particle-tracking program MODPATH was used to simulate 

groundwater residence time, which in turn was used to relate 

natural and anthropogenic factors to water quality (table 9; 

Starn and Brown, 2007). Groundwater from WY83 appears to 

be young and has a short simulated flow path (< 1 year), but 

the flow path probably moves through a greater percentage 

of silt and clay minerals and carbonate minerals derived from 

the Cass Formation that are more easily weathered than other 

well flow paths, as indicated by the relatively high dissolved 

silica and saturation indices for calcite and dolomite (table 7). 

Glacial till also contains a greater proportion of clay, calcite, 

and other reactive minerals and, therefore, contains higher 

concentrations of dissolved silica and HCO3

-

 (table 7). 

Bedrock well WY87, in the Mesozoic basalt, had ion 

percentages similar to those of both wells (WY86 and WY97) 

in the Paleozoic rock (fig. 13) and may reflect similar rock 

chemistry, or the close proximity of WY87 to the contact 
Aquifer Chemistry 35

Table 7. General chemical characteristics and concentrations of major elements, nutrients, dissolved organic carbon, and ultraviolet absorbance in groundwater samples from wells in the Woodbury study area (2002–06), and from selected wells elsewhere in the Pomperaug and Hartford Basins, Connecticut. —Continued[ID, identifier; --, not measured; NA, not applicable; <, less than; E, estimated value below minimum reporting level; mS/cm, microsiemens per centimeter at 25 degrees Celsius; C, Celsius; HCO3−, bicarbonate; DO, dissolved oxygen; H2S plus HS-, sulfides; CH4, methane; Ca, calcium; Mg, magnesium; K, potassium; Na, sodium; Br−, bromide; Cl−, chloride; F-, fluoride; SO42-, sulfate; SiO2, silica; NH4+, ammonia; NO2−, nitrite; NO3−, nitrate; PO43−, orthophosphate; DOC, dissolved organic carbon; UV, ultraviolet; nm, nanometers; SI, saturation index; cm, centimeters; redox, oxidation–reduction; O2, oxygen reducing; NO3, nitrate reducing; Mn, manganese reducing; Fe, iron reducing; SO4, sulfate reducing; FeSO4, iron- to sulfate-reducing; CH4, methanogenic; X - Y/Z, mixture (X) of waters with different redox ranging from most oxidized (Y) to most reduced (Z); concentrations in milligrams per liter, unless otherwise noted; bedrock wells shaded gray]

Well ID Date Redox class1 DOC category2 Geo- chemical zone3 Temperature, water (degrees C)

Specific 

conductance 

(μS/cm at 

25 degrees 

Celsius)

pH, 

field HCO3−

Dissolved 

oxygen 

(DO)

H S 2

plus 

HS−

(as S)

CH4 Ca Mg K Na Br −

PSW-14 8/14/79 O2 DOC1 1B 12.5 230 6.4 44 -- -- -- 22 6 1.1 11 --PSW-1 10/23/02 O2 DOC1 1B 12 184 6.1 71 2.4 -- -- 23 6.4 1.3 18 0.034PSW-1 12/30/03 O2 DOC1 1B 12 283 6.2 82 54.8 <0.002 0.001 25 7.0 1.6 20 0.036PSW-1 8/11/04 O2 DOC1 1B 12.5 292 6.3 76 5.2 -- 0.001 26 6.7 1.4 20 0.031PSW-1 11/30/04 O2 DOC1 1B 11.5 283 6.4 83 5.1 -- 0.001 25 6.9 1.6 20 0.042PSW-1 8/5/05 O2 DOC1 1B 13 301 6.1 76 4.2 -- -- 27 6.7 1.5 19 --PSW-1 7/11/06 O2 DOC1 1B 14.5 310 5.8 -- 4.8 -- <0.001 -- -- -- -- --WY35 12/1/03 X - O2/Fe DOC2 1A 12.5 141 6 33 50.81 0.019 0.001 9.9 2.6 1.7 7.0 0.069WY35 9/16/04 X - O2/Fe DOC2 1A 15 119 6.15 31 1.4 -- -- 8.6 2.1 1.6 6.5 0.067WY35 2/18/05 X - O2/Fe DOC2 1A 8 128 6.1 34 1.2 -- -- 9.6 2.3 1.6 6.6 0.123WY 35 11/29/05 X - O2/Fe DOC2 1A 13 140 5.8 33 3.1 -- -- 11 2.6 2 7.6 --WY534 4/12/85 O2 DOC3 1A 13 215 6.3 -- 4.7 -- -- 18 5.9 -- 14 --WY69 12/10/03 X - O2/SO4 DOC1 1B 11.5 276 6.5 82 56.3 0.014 0.001 31 7.4 1.8 10 0.035WY69 2/23/05 O2 DOC1 1B 11.2 308 6.4 -- 6.6 -- -- -- -- -- -- --WY70 12/29/03 O2 DOC1 1A 11 218 6.1 59 5.1 0.004 <0.001 17 5.6 1.8 15 0.033WY70 2/23/05 O2 DOC1 1A 12.2 222 6.1 59 4.3 -- -- -- -- -- -- --WY71 12/22/03 -- DOC3 1A 11 400 6.1 102 -- -- <0.001 22 6.0 2.3 50 0.096WY71 7/27/04 X - O2/SO4 DOC3 1A 13.5 511 6.2 160 0.81 0.003 -- 36 9.3 2.5 52 0.078WY71 1/7/05 O2 DOC3 1A 11.7 461 6.2 168 1.5 -- -- 31 8.7 2.4 51 0.101
36 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06 Table 7. General chemical characteristics and concentrations of major elements, nutrients, dissolved organic carbon, and ultraviolet absorbance in groundwater samples from wells in the Woodbury study area (2002–06), and from selected wells elsewhere in the Pomperaug and Hartford Basins, Connecticut. .—Continued [ID, identifier; --, not measured; NA, not applicable; <, less than; E, estimated value below minimum reporting level; mS/cm, microsiemens per centimeter at 25 degrees Celsius; C, Celsius; HCO3−, bicarbonate; DO, dissolved oxygen; H2S plus HS-, sulfides; CH4, methane; Ca, calcium; Mg, magnesium; K, potassium; Na, sodium; Br−, bromide; Cl−, chloride; F-, fluoride; SO42−, sulfate; SiO2, silica; NH4

+, ammonia; NO2

−, nitrite; 

NO3

−, nitrate; PO43−, orthophosphate; DOC, dissolved organic carbon; UV, ultraviolet; nm, nanometers; SI, saturation index; cm, centimeters; redox, oxidation–reduction; O2, oxygen reducing; NO3, nitrate reducing; 

Mn, manganese reducing; Fe, iron reducing; SO4, sulfate reducing; FeSO4, iron- to sulfate-reducing; CH4, methanogenic; X - Y/Z, mixture (X) of waters with different redox ranging from most oxidized (Y) to most reduced (Z); concentrations in milligrams per liter, unless otherwise noted; bedrock wells shaded gray]

Well ID Cl−

Cl:Br 

mass 

ratio

F- SO4

2− SiO2 NH4

+

(as N)

NO2

−

(as N)

NO3

− plus 

NO2

−

(as N)

PO4

3−

(as P) DOC

UV 

absorbance, 

254 nm 

(units 

per cm)

UV 

absorbance, 

280 nm 

(units per cm)

SI 

(calcite)

SI 

(quartz) Water type

PSW-14 26 -- -- 21 15 -- -- 1.3 -- -- -- -- -2.01 0.453 Ca-Mg-Na-HCO3-Cl−SO4PSW-1 30 908 <0.17 17 15 E0.037 <0.008 1.8 E0.01 0.43 -- -- -2.27 0.591 Ca-Na-Mg-HCO3-ClPSW-1 33 911 <0.17 17 16 <0.04 <0.008 1.8 E0.003 -- -- -- -2.07 0.612 Ca-Na-Mg-HCO3-ClPSW-1 33 1,072 <0.17 18 16 <0.04 <0.008 1.9 0.014 0.41 0.0052 0.0042 -1.99 0.598 Ca-Na-Mg-HCO3-ClPSW-1 33 789 E0.054 18 16 <0.04 <0.008 1.9 E0.004 0.36 0.0047 0.0038 -1.85 0.614 Ca-Na-Mg-HCO3-ClPSW-1 34 -- E0.051 19 15 -- <0.008 2.0 E0.004 0.34 0.0049 0.0037 -2.17 0.562 Ca-Na-Mg-HCO3-ClPSW-1 -- -- -- -- -- -- -- -- -- -- -- -- -- --WY35 15 218 <0.17 13 13 E0.026 <0.008 0.26 E0.009 0.50 -- -- -3.02 0.508 Ca-Na-HCO3-Cl−SO4WY35 8.8 132 <0.17 12 13 0.053 <0.008 0.13 0.016 0.52 0.014 0.0120 -2.91 0.468 Ca-Na-HCO3-Cl−SO4WY35 13 105 <0.1 11 13 <0.04 <0.008 0.31 0.008 0.75 0.023 0.0210 -2.98 0.581 Ca-Na-HCO3-Cl−SO4WY 35 13 -- E0.07 11 13 0.04 <0.008 0.38 0.009 0.40 0.022 0.020 -3.15 0.500 Ca-Na-HCO3-ClWY534 26 -- 18 15 0.15 -- 2.9 <0.01 0.90 -- -- -2.37 0.562 Ca-Na-Mg-Cl−HCO3WY69 20 565 <0.17 33 17 <0.04 <0.008 1.5 0.006 0.37 -- -- -1.75 0.646 Ca-Mg-HCO3-SO4-ClWY69 -- -- -- -- -- -- -- -- -- -- -- -- -- --WY70 22 666 <0.17 11 16 <0.04 <0.008 3.2 E0.005 0.43 -- -- -2.47 0.609 Ca-Na-Mg-HCO3-ClWY70 -- -- -- -- -- -- -- -- -- -- -- -2.47 0.609 --WY71 55 866 <0.17 16 13 <0.04 <0.008 1.1 E0.004 1.30 -- -- -2.16 0.516 Na-Ca-HCO3-ClWY71 68 521 <0.17 13 12 <0.04 <0.008 0.88 0.017 0.99 0.022 0.0160 -1.54 0.353 Na-Ca-HCO3-ClWY71 52 -- E0.073 13 14 <0.04 E0.004 0.72 E0.005 1.15 0.020 0.0140 -1.71 0.554 Na-Ca-HCO3-Cl
Aquifer Chemistry 37

Table 7. General chemical characteristics and concentrations of major elements, nutrients, dissolved organic carbon, and ultraviolet absorbance in groundwater samples from wells in the Woodbury study area (2002–06), and from selected wells elsewhere in the Pomperaug and Hartford Basins, Connecticut. —Continued[ID, identifier; --, not measured; NA, not applicable; <, less than; E, estimated value below minimum reporting level; mS/cm, microsiemens per centimeter at 25 degrees Celsius; C, Celsius; HCO3−, bicarbonate; DO, dissolved oxygen; H2S plus HS-, sulfides; CH4, methane; Ca, calcium; Mg, magnesium; K, potassium; Na, sodium; Br−, bromide; Cl−, chloride; F-, fluoride; SO42-, sulfate; SiO2, silica; NH4+, ammonia; NO2−, nitrite; NO3−, nitrate; PO43−, orthophosphate; DOC, dissolved organic carbon; UV, ultraviolet; nm, nanometers; SI, saturation index; cm, centimeters; redox, oxidation–reduction; O2, oxygen reducing; NO3, nitrate reducing; Mn, manganese reducing; Fe, iron reducing; SO4, sulfate reducing; FeSO4, iron- to sulfate-reducing; CH4, methanogenic; X - Y/Z, mixture (X) of waters with different redox ranging from most oxidized (Y) to most reduced (Z); concentrations in milligrams per liter, unless otherwise noted; bedrock wells shaded gray]

Well ID Date Redox class1 DOC category2 Geo- chemical zone3 Temperature, water (degrees C)

Specific 

conductance 

(μS/cm at 

25 degrees 

Celsius)

pH, 

field HCO3−

Dissolved 

oxygen 

(DO)

H S 2

plus 

HS−

(as S)

CH4 Ca Mg K Na Br −

WY71 5/18/05 O2 DOC3 1A 12.5 645 6 126 3.2 -- -- 46 15 2.6 56 --WY72 12/16/03 X - O2/SO4 DOC1 1B 10.5 291 6.9 84 -- 0.068 <0.001 35 8.5 1.6 11 0.028WY72 2/23/05 -- DOC1 1B 11.2 318 6.8 -- 5.5 -- -- -- -- -- -- --WY73 12/17/03 O2 DOC3 1A 11 297 6.1 102 54.2 <0.002 0.001 23 6.6 1.5 27 0.032WY74 11/6/03 O2 DOC3 1A 12 344 6.2 160 55.8 <0.002 <0.001 27 7.8 1.9 32 0.037WY74 7/28/04 O2 DOC3 1A 13 385 6.2 168 5.9 -- -- 31 8.0 1.8 30 0.055WY74 1/10/05 O2 DOC3 1A 10.8 388 6.3 126 5.1 -- -- 33 10 2.0 30 0.059WY74 6/15/05 O2 DOC3 1A 14.5 344 6.3 84 6.2 -- -- 30 8.5 1.7 25 --WY75 11/13/03 X - O2/SO4 DOC1 1B 11.5 345 6.4 73 55.7 0.027 0.001 36 6.4 1.6 20 0.029WY76 11/12/03 O2 DOC3 1A 13 265 6.2 61 54.8 0.001 <0.001 20 5.8 2.2 22 0.034WY76 7/26/04 O2 DOC3 1A 12 274 6.1 61 2.0 -- -- 23 6.2 1.8 21 0.042WY76 1/4/05 O2 DOC3 1A 11.4 272 6.1 49 3.1 -- -- 18 5.8 1.9 25 0.051WY76 6/14/05 X - O2/SO4 DOC3 1A 12 240 5.9 59 4.2 0.001 -- 17 5.7 1.5 18 --WY77 12/9/03 X - O2/SO4 DOC1 1B 8.5 172 6.5 54 53.6 0.19 0.001 19 4.8 1.4 10 0.026WY78 11/20/03 O2 DOC2 1A 10.5 104 6.2 22 3.2 0.007 <0.001 6.6 2.2 1.1 9.0 E0.0085WY78 7/28/04 SO4 DOC2 1A 18 128 6.3 30 0.36 0.014 -- 7.3 2.4 1.4 11 <0.016WY78 1/11/05 X - O2/NO3 DOC2 1A 4.5 764 6.1 14 6.1 -- -- 51 17 2.9 59 --WY78 5/24/05 X - O2/NO3 DOC2 1A 11 111 6.1 26 5.5 -- -- 5.7 2.0 1.1 12 --WY79 11/4/03 SO4 DOC3 1A 14 347 6.2 87 50.08 0.097 <0.001 25 5.5 1.9 33 0.049WY79 7/29/04 O2 DOC3 1A 14.5 366 6.1 89 1.8 -- -- 28 5.5 1.7 35 0.057
38 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06 Table 7. General chemical characteristics and concentrations of major elements, nutrients, dissolved organic carbon, and ultraviolet absorbance in groundwater samples from wells in the Woodbury study area (2002–06), and from selected wells elsewhere in the Pomperaug and Hartford Basins, Connecticut. .—Continued [ID, identifier; --, not measured; NA, not applicable; <, less than; E, estimated value below minimum reporting level; mS/cm, microsiemens per centimeter at 25 degrees Celsius; C, Celsius; HCO3−, bicarbonate; DO, dissolved oxygen; H2S plus HS-, sulfides; CH4, methane; Ca, calcium; Mg, magnesium; K, potassium; Na, sodium; Br−, bromide; Cl−, chloride; F-, fluoride; SO42−, sulfate; SiO2, silica; NH4

+, ammonia; NO2

−, nitrite; 

NO3

−, nitrate; PO43−, orthophosphate; DOC, dissolved organic carbon; UV, ultraviolet; nm, nanometers; SI, saturation index; cm, centimeters; redox, oxidation–reduction; O2, oxygen reducing; NO3, nitrate reducing; 

Mn, manganese reducing; Fe, iron reducing; SO4, sulfate reducing; FeSO4, iron- to sulfate-reducing; CH4, methanogenic; X - Y/Z, mixture (X) of waters with different redox ranging from most oxidized (Y) to most reduced (Z); concentrations in milligrams per liter, unless otherwise noted; bedrock wells shaded gray]

Well ID Cl−

Cl:Br 

mass 

ratio

F- SO4

2− SiO2 NH4

+

(as N)

NO2

−

(as N)

NO3

− plus 

NO2

−

(as N)

PO4

3−

(as P) DOC

UV 

absorbance, 

254 nm 

(units 

per cm)

UV 

absorbance, 

280 nm 

(units per cm)

SI 

(calcite)

SI 

(quartz) Water type

WY71 124 -- <0.1 10 13 <0.04 <0.008 2.2 <0.006 0.81 0.014 0.0100 -1.86 0.506 Na-Ca-Mg-Cl−HCO3WY72 29 1,027 <0.17 26 19 <0.04 <0.008 1.2 <0.006 E0.32 -- -- -1.25 0.712 Ca-Mg-HCO3-ClWY72 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY73 37 1,158 <0.17 12 14 <0.04 <0.008 2.1 E0.005 0.61 -- -- -2.24 0.555 Na-Ca-HCO3-ClWY74 42 1,145 <0.17 13 12 <0.04 <0.008 1.9 0.007 0.67 -- -- -1.93 0.496 Na-Ca-HCO3-ClWY74 50 921 <0.17 11 11 <0.04 <0.008 1.6 0.026 0.67 0.0094 0.0068 -1.73 0.334 Ca-Na-HCO3-ClWY74 47 794 E0.051 11 13 <0.04 <0.008 1.1 0.009 0.76 0.011 0.0084 -1.70 0.536 Ca-Na-Mg-HCO3-ClWY74 37 -- <0.1 11 11 <0.04 <0.008 1.7 0.007 0.60 0.0059 0.0042 -1.69 0.522 Ca-Na-Mg-HCO3-ClWY75 43 1,509 <0.17 29 19 <0.04 <0.008 1.5 <0.006 0.34 -- -- -1.80 0.680 Ca-Na-Cl−HCO3WY76 32 957 <0.17 11 17 <0.04 <0.008 3.8 0.007 0.51 -- -- -2.28 0.604 Ca-Na-HCO3-ClWY76 34 813 <0.17 13 16 <0.04 <0.008 2.5 0.022 0.57 0.0092 0.0065 -2.22 0.489 Ca-Na-Mg-HCO3-ClWY76 33 644 <0.1 14 17 <0.04 <0.008 3.4 0.008 0.66 0.0099 0.0074 -2.54 0.629 Na-Ca-Cl−HCO3WY76 29 -- <0.1 10 15 <0.04 <0.008 2.5 0.006 0.46 0.0082 0.0060 -2.66 0.578 Ca-Na-Mg-HCO3-ClWY77 19 742 <0.17 12 16 <0.04 <0.008 0.34 E0.003 0.54 -- -- -2.11 0.666 Ca-Na-Mg-HCO3-ClWY78 13 -- <0.17 8.1 11 <0.04 <0.008 0.10 E0.005 4.7 -- -- -3.18 0.464 Na-Ca-HCO3-ClWY78 17 -- <0.17 7.5 12 <0.04 <0.008 <0.06 0.025 1.8 0.069 0.0520 -2.80 0.387 Na-Ca-HCO3-ClWY78 214 -- <0.1 8.1 11 <0.04 <0.008 0.26 <0.006 1.1 0.022 0.0160 -2.82 0.568 Ca-Na-Mg-ClWY78 15 -- E0.067 8.6 12 <0.04 <0.008 <0.06 E0.004 1.5 0.055 0.0420 -3.24 0.497 Na-Ca-HCO3-ClWY79 44 898 <0.17 16 16 <0.04 <0.008 3.7 E0.003 0.87 -- -- -2.02 0.580 Na-Ca-HCO3-ClWY79 45 805 <0.17 19 15 <0.04 <0.008 3.0 0.018 0.54 0.0076 0.0053 -1.99 0.462 Na-Ca-HCO3-Cl
Aquifer Chemistry 39

Table 7. General chemical characteristics and concentrations of major elements, nutrients, dissolved organic carbon, and ultraviolet absorbance in groundwater samples from wells in the Woodbury study area (2002–06), and from selected wells elsewhere in the Pomperaug and Hartford Basins, Connecticut. —Continued[ID, identifier; --, not measured; NA, not applicable; <, less than; E, estimated value below minimum reporting level; mS/cm, microsiemens per centimeter at 25 degrees Celsius; C, Celsius; HCO3−, bicarbonate; DO, dissolved oxygen; H2S plus HS-, sulfides; CH4, methane; Ca, calcium; Mg, magnesium; K, potassium; Na, sodium; Br−, bromide; Cl−, chloride; F-, fluoride; SO42-, sulfate; SiO2, silica; NH4+, ammonia; NO2−, nitrite; NO3−, nitrate; PO43−, orthophosphate; DOC, dissolved organic carbon; UV, ultraviolet; nm, nanometers; SI, saturation index; cm, centimeters; redox, oxidation–reduction; O2, oxygen reducing; NO3, nitrate reducing; Mn, manganese reducing; Fe, iron reducing; SO4, sulfate reducing; FeSO4, iron- to sulfate-reducing; CH4, methanogenic; X - Y/Z, mixture (X) of waters with different redox ranging from most oxidized (Y) to most reduced (Z); concentrations in milligrams per liter, unless otherwise noted; bedrock wells shaded gray]

Well ID Date Redox class1 DOC category2 Geo- chemical zone3 Temperature, water (degrees C)

Specific 

conductance 

(μS/cm at 

25 degrees 

Celsius)

pH, 

field HCO3−

Dissolved 

oxygen 

(DO)

H S 2

plus 

HS−

(as S)

CH4 Ca Mg K Na Br −

WY79 1/31/05 O2 DOC3 1A 11.2 369 6.2 95 1.3 0.001 -- 28 5.8 1.7 36 0.049WY79 8/5/05 O2 DOC3 1A 13.5 370 5.9 97 1.2 -- -- 27 5.3 1.7 37 --WY80 11/5/03 X - O2/SO4 DOC2 1A 13 150 5.9 54 2 0.29 0.003 13 4.7 1.1 8.7 0.025WY80 8/30/04 X - O2/Mn DOC2 1A 17 141 6.1 41 1.3 -- -- 12 3.9 1.1 8.3 <0.016WY80 1/11/05 X - O2/NO3 DOC2 1A 8.6 129 -- 43 2.9 <0.002 -- 12 3.9 0.9 7.6 E0.014WY80 5/17/05 X - O2/NO3 DOC2 1A 10.5 115 5.9 31 3.0 -- -- 9.1 3.5 0.8 6.9 --WY81 12/2/03 X - O2/SO4 DOC1 1A 9 334 6.2 49 58.8 0.032 0.001 22 3.4 1.3 33 0.040WY81 7/29/04 O2 DOC1 1A 20 362 6.1 35 8 -- -- 25 3.5 1.3 31 0.033WY81 1/13/05 O2 DOC1 1A 10.5 286 6.3 50 10 -- -- 22 3.2 1.3 33 0.036WY81 5/4/05 O2 DOC1 1A 9.81 316 5.9 39 9.8 -- -- 24 3.7 1.2 30 --WY82 12/8/03 X - O2/CH4 DOC1 1A 9 309 6.2 44 58.5 0.003 0.001 24 3.7 1.6 26 0.027WY83 11/4/03 X - Mn/CH4 DOC2 1A 12.5 329 6.5 162 0.5 0.08 0.026 30 8.3 1.4 8.7 0.047WY83 8/31/04 X - O2/CH4 DOC2 1A 13.5 328 6.5 145 0.79 -- 0.039 28 7.4 1.3 8.2 0.048WY83 1/4/05 X - Fe/SO4 DOC2 1A 11.5 325 6.5 118 0.4 0.001 -- 29 8.1 1.4 8.8 0.37WY83 4/29/05 X - O2/Fe DOC2 1A 15.1 322 6.3 134 2.5 -- -- 29 7.9 1.3 8.4 0.89WY83 7/11/06 -- DOC2 1A 12.3 311 4.4 109 0.2 -- -- -- -- -- -- --WY84 11/18/03 X - NO3/CH4 DOC1 1B 13 220 6.6 82 0.16 0.024 0.014 24 5.8 1.3 9.5 0.033WY84 2/28/05 X - O2/SO4 DOC1 1B 11 206 6.6 -- 0.3 0.008 -- -- -- -- -- --WY85 11/19/03 X - O2/CH4 DOC3 1A 16 1450 5.3 89 50.6 0.007 0.55 128 35.3 9.6 65 0.17WY85 8/10/04 X - O2/SO4 DOC3 1A 17 906 6 65 0.66 0.26 -- 68 15.3 17 45 0.069
40 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06 Table 7. General chemical characteristics and concentrations of major elements, nutrients, dissolved organic carbon, and ultraviolet absorbance in groundwater samples from wells in the Woodbury study area (2002–06), and from selected wells elsewhere in the Pomperaug and Hartford Basins, Connecticut. .—Continued [ID, identifier; --, not measured; NA, not applicable; <, less than; E, estimated value below minimum reporting level; mS/cm, microsiemens per centimeter at 25 degrees Celsius; C, Celsius; HCO3−, bicarbonate; DO, dissolved oxygen; H2S plus HS-, sulfides; CH4, methane; Ca, calcium; Mg, magnesium; K, potassium; Na, sodium; Br−, bromide; Cl−, chloride; F-, fluoride; SO42−, sulfate; SiO2, silica; NH4

+, ammonia; NO2

−, nitrite; 

NO3

−, nitrate; PO43−, orthophosphate; DOC, dissolved organic carbon; UV, ultraviolet; nm, nanometers; SI, saturation index; cm, centimeters; redox, oxidation–reduction; O2, oxygen reducing; NO3, nitrate reducing; 

Mn, manganese reducing; Fe, iron reducing; SO4, sulfate reducing; FeSO4, iron- to sulfate-reducing; CH4, methanogenic; X - Y/Z, mixture (X) of waters with different redox ranging from most oxidized (Y) to most reduced (Z); concentrations in milligrams per liter, unless otherwise noted; bedrock wells shaded gray]

Well ID Cl−

Cl:Br 

mass 

ratio

F- SO4

2− SiO2 NH4

+

(as N)

NO2

−

(as N)

NO3

− plus 

NO2

−

(as N)

PO4

3−

(as P) DOC

UV 

absorbance, 

254 nm 

(units 

per cm)

UV 

absorbance, 

280 nm 

(units per cm)

SI 

(calcite)

SI 

(quartz) Water type

WY79 43 873 <0.1 21 16 <0.04 <0.008 2.7 <0.006 0.93 0.0053 <0.0035 -1.99 0.620 Na-Ca-HCO3-ClWY79 43 -- <0.1 24 15 <0.04 <0.008 2.9 E0.003 0.46 0.0080 0.0055 -2.22 0.555 Na-Ca-HCO3-ClWY80 11 426 <0.17 9.6 20 <0.04 <0.008 <0.06 0.007 1.0 -- -- -2.79 0.683 Ca-Mg-Na-HCO3-ClWY80 15 -- <0.17 8.0 19 <0.04 <0.008 <0.06 0.01 0.89 0.019 0.0150 -2.61 0.553 Ca-Na-Mg-HCO3-ClWY80 11 -- E0.05 9.0 18 <0.04 <0.008 <0.06 <0.006 1.0 0.019 0.0150 -1.88 0.712 Ca-Na-Mg-HCO3-ClWY80 11 -- <0.1 8.6 16 <0.04 <0.008 <0.06 <0.006 0.71 0.019 0.0150 -3.25 0.634 Ca-Na-Mg-HCO3-ClWY81 55 1,390 <0.17 24 14 <0.04 <0.008 1.4 <0.006 0.70 -- -- -2.40 0.591 Na-Ca-Cl−HCO3WY81 72 2,182 <0.17 15 13 <0.04 <0.008 1.3 0.013 0.60 0.0088 0.0066 -2.42 0.388 Na-Ca-ClWY81 47 1,308 E0.065 24 14 <0.04 <0.008 0.88 <0.006 0.61 0.0050 <0.0035 -2.27 0.573 Na-Ca-Cl−HCO3WY81 61 -- E0.052 19 13 <0.04 <0.008 1.3 <0.006 0.42 0.0044 <0.0035 -2.71 0.552 Na-Ca-Cl−HCO3WY82 52 1,914 <0.17 22 15 <0.04 <0.008 1.1 <0.006 0.62 -- -- -2.41 0.621 Ca-Na-Cl−HCO3WY83 25 536 <0.17 9.2 32 0.197 E0.006 <0.06 0.006 1.6 -- -- -1.42 0.901 Ca-Mg-HCO3-ClWY83 24 503 <0.17 8.3 32 0.21 <0.008 <0.06 0.16 2.1 0.047 0.039 -1.48 0.884 Ca-Mg-HCO3-ClWY83 23 62 E0.077 8.6 32 0.216 <0.008 <0.06 <0.006 2.0 0.065 0.057 -1.56 0.922 Ca-Mg-HCO3-ClWY83 23 26 E0.063 9.0 31 0.187 <0.008 <0.06 <0.006 1.3 0.057 0.050 -0.956 0.844 Ca-Mg-HCO3-ClWY83 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY84 25 770 <0.17 11 20 <0.04 <0.008 0.12 <0.006 0.50 -- -- -1.66 0.696 Ca-Mg-HCO3-ClWY84 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY85 400 2400 <0.17 8.7 17 <0.04 <0.008 <0.06 E0.003 7.8 -- -- -2.25 0.502 Ca-Mg-Na-ClWY85 200 2,916 <0.17 8.6 12 1.144 <0.008 14 0.013 89 0.12 0.095 -1.94 0.392 Ca-Na-Cl
Aquifer Chemistry 41

Table 7. General chemical characteristics and concentrations of major elements, nutrients, dissolved organic carbon, and ultraviolet absorbance in groundwater samples from wells in the Woodbury study area (2002–06), and from selected wells elsewhere in the Pomperaug and Hartford Basins, Connecticut. —Continued[ID, identifier; --, not measured; NA, not applicable; <, less than; E, estimated value below minimum reporting level; mS/cm, microsiemens per centimeter at 25 degrees Celsius; C, Celsius; HCO3−, bicarbonate; DO, dissolved oxygen; H2S plus HS-, sulfides; CH4, methane; Ca, calcium; Mg, magnesium; K, potassium; Na, sodium; Br−, bromide; Cl−, chloride; F-, fluoride; SO42-, sulfate; SiO2, silica; NH4+, ammonia; NO2−, nitrite; NO3−, nitrate; PO43−, orthophosphate; DOC, dissolved organic carbon; UV, ultraviolet; nm, nanometers; SI, saturation index; cm, centimeters; redox, oxidation–reduction; O2, oxygen reducing; NO3, nitrate reducing; Mn, manganese reducing; Fe, iron reducing; SO4, sulfate reducing; FeSO4, iron- to sulfate-reducing; CH4, methanogenic; X - Y/Z, mixture (X) of waters with different redox ranging from most oxidized (Y) to most reduced (Z); concentrations in milligrams per liter, unless otherwise noted; bedrock wells shaded gray]

Well ID Date Redox class1 DOC category2 Geo- chemical zone3 Temperature, water (degrees C)

Specific 

conductance 

(μS/cm at 

25 degrees 

Celsius)

pH, 

field HCO3−

Dissolved 

oxygen 

(DO)

H S 2

plus 

HS−

(as S)

CH4 Ca Mg K Na Br −

WY85 2/1/05 X - NO3/SO4 DOC3 1A 11.9 1020 5.8 76 0.5 0.001 -- 90 20 22 47 0.088WY85 6/16/05 X - O2/SO4 DOC3 1A 14.5 1530 5.8 66 2.6 0.004 -- 125 30 33 65 --WY86 12/4/03 X - O2/SO4 DOC1 2A 8.5 224 7.5 94 51.7 0.003 0.001 35 0.8 0.4 9.8 0.029WY86 3/7/05 X - O2/SO4 DOC1 2 9.6 219 7.3 -- 0.56 0.009 0.001 -- -- -- -- --WY87 12/18/03 -- DOC1 2 8.5 212 8 88 0.76 <0.002 -- -- -- -- -- --WY87 12/29/03 X - NO3/Mn DOC1 2 10 209 8.3 -- 0.38 -- -- 26 4.2 1.0 10 0.019WY87 3/7/05 SO4 DOC1 2 9.3 224 7.3 -- 0.4 0.003 -- -- -- -- -- --WY88 11/24/03 X - O2/CH4 DOC2 1B 10.5 279 7.2 100 53 0.46 0.018 33 7.0 2.2 8.7 0.021WY88 9/14/04 O2 DOC2 1B 12 259 7.0 -- 4.6 -- -- -- -- -- -- --WY89 8/18/04 O2 DOC3 1B 19 572 7.3 143 7.9 -- -- 62 15 3.7 16 0.050WY89 11/2/04 X - O2/SO4 DOC3 1B 13.5 570 -- -- 8.2 0.002 0.002 -- -- -- -- --WY90 11/9/04 X - O2/CH4 DOC3 1B 12 751 7 168 1.6 0.001 0.001 103 18 3.2 25 0.069WY90 5/26/05 -- DOC3 1B 14.5 646 6.7 221 8.8 -- -- 85 16 3.7 26 0.100WY91 8/19/04 O2 DOC1 1B 11.5 222 6.6 66 5.2 <0.002 0.001 27 4.9 1.6 7.3 0.021WY91 12/14/04 O2 DOC1 1B 10 233 6.9 -- 5.6 -- <0.001 -- -- -- -- --WY92 8/23/04 O2 DOC1 1A 13 271 6.3 51 3.3 -- -- 25 4.8 2.1 16 0.026WY92 12/9/04 O2 DOC1 1A 12.4 255 6.4 74 3.4 -- <0.001 24 5.0 1.9 16 0.037WY92 5/2/05 O2 DOC1 1A 9.58 259 6.1 56 5.6 -- -- 26 5.4 1.6 15 0.064WY93 8/24/04 X - O2/Mn DOC1 1B 18.5 258 7.5 113 2.5 0.003 -- 34 7.8 1.6 8.3 0.028WY94 10/14/04 O2 DOC3 1A 14.5 196 6.2 45 8.6 -- -- 20 5.6 1.0 6.5 0.035
42 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06 Table 7. General chemical characteristics and concentrations of major elements, nutrients, dissolved organic carbon, and ultraviolet absorbance in groundwater samples from wells in the Woodbury study area (2002–06), and from selected wells elsewhere in the Pomperaug and Hartford Basins, Connecticut. .—Continued [ID, identifier; --, not measured; NA, not applicable; <, less than; E, estimated value below minimum reporting level; mS/cm, microsiemens per centimeter at 25 degrees Celsius; C, Celsius; HCO3−, bicarbonate; DO, dissolved oxygen; H2S plus HS-, sulfides; CH4, methane; Ca, calcium; Mg, magnesium; K, potassium; Na, sodium; Br−, bromide; Cl−, chloride; F-, fluoride; SO42−, sulfate; SiO2, silica; NH4

+, ammonia; NO2

−, nitrite; 

NO3

−, nitrate; PO43−, orthophosphate; DOC, dissolved organic carbon; UV, ultraviolet; nm, nanometers; SI, saturation index; cm, centimeters; redox, oxidation–reduction; O2, oxygen reducing; NO3, nitrate reducing; 

Mn, manganese reducing; Fe, iron reducing; SO4, sulfate reducing; FeSO4, iron- to sulfate-reducing; CH4, methanogenic; X - Y/Z, mixture (X) of waters with different redox ranging from most oxidized (Y) to most reduced (Z); concentrations in milligrams per liter, unless otherwise noted; bedrock wells shaded gray]

Well ID Cl−

Cl:Br 

mass 

ratio

F- SO4

2− SiO2 NH4

+

(as N)

NO2

−

(as N)

NO3

− plus 

NO2

−

(as N)

PO4

3−

(as P) DOC

UV 

absorbance, 

254 nm 

(units 

per cm)

UV 

absorbance, 

280 nm 

(units per cm)

SI 

(calcite)

SI 

(quartz) Water type

WY85 230 2,638 <0.1 11 15 1.958 E0.005 12 <0.006 3.0 0.13 0.10 -2.05 0.581 Ca-Na-ClWY85 380 -- <0.1 9.7 14 4.212 <0.008 19 <0.006 2.0 0.092 0.070 -1.98 0.511 Ca-Na-ClWY86 5.4 185 0.35 25 21 <0.04 <0.008 0.2 E0.004 0.43 -- -- -0.622 0.783 Ca-HCO3-SO4WY86 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY87 -- -- -- -- -- -- -- -- -- 0.54 -- -- 0.0328 0.754 Ca-Na-HCO3WY87 15 776 <0.17 13 21 <0.04 <0.008 E0.034 0.02 -- -- -- -- -- --WY87 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY88 25 1,215 <0.17 13 15 <0.04 <0.008 1.3 0.006 0.62 -- -- -0.897 0.605 Ca-Mg-HCO3-ClWY88 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY89 77 1,525 <0.17 9.7 20 0.058 0.009 6.7 0.016 -- -- -- -0.291 0.584 Ca-Mg-HCO3-ClWY89 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY90 54 776 <0.1 7.7 32 0.05 <0.008 17 0.012 1.2 0.021 0.0160 -0.428 0.905 Ca-Mg-HCO3-ClWY90 63 630 <0.1 11 30 0.25 E0.006 9.4 E0.004 0.60 0.015 0.0120 -- -- --WY91 19 905 <0.17 15 19 <0.04 <0.008 1.6 0.011 0.45 0.0043 <0.0035 -1.73 0.680 Ca-HCO3-ClWY91 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY92 39 1,500 <0.17 18 16 <0.04 <0.008 1.2 0.017 0.36 0.0040 <0.0035 -2.15 0.585 Ca-Na-Cl−HCO3WY92 37 1,000 E0.057 16 16 -- -- -- -- 0.36 0.0048 0.0038 -1.92 0.600 Ca-Na-HCO3-ClWY92 37 580 E0.058 17 14 <0.04 <0.008 1.4 E0.004 0.52 0.0056 0.0040 -2.36 0.588 Ca-Na-Cl−HCO3WY93 13 450 <0.17 13 15 E0.039 0.01 0.25 0.022 <0.33 <0.0035 <0.0035 -0.418 0.474 Ca-Mg-HCO3WY94 15 430 <0.1 12 19 <0.04 <0.008 2.6 0.017 0.39 <0.0035 <0.0035 -2.37 0.648 Ca-Mg-HCO3-ClWY94 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
Aquifer Chemistry 43

Table 7. General chemical characteristics and concentrations of major elements, nutrients, dissolved organic carbon, and ultraviolet absorbance in groundwater samples from wells in the Woodbury study area (2002–06), and from selected wells elsewhere in the Pomperaug and Hartford Basins, Connecticut. —Continued[ID, identifier; --, not measured; NA, not applicable; <, less than; E, estimated value below minimum reporting level; mS/cm, microsiemens per centimeter at 25 degrees Celsius; C, Celsius; HCO3−, bicarbonate; DO, dissolved oxygen; H2S plus HS-, sulfides; CH4, methane; Ca, calcium; Mg, magnesium; K, potassium; Na, sodium; Br−, bromide; Cl−, chloride; F-, fluoride; SO42-, sulfate; SiO2, silica; NH4+, ammonia; NO2−, nitrite; NO3−, nitrate; PO43−, orthophosphate; DOC, dissolved organic carbon; UV, ultraviolet; nm, nanometers; SI, saturation index; cm, centimeters; redox, oxidation–reduction; O2, oxygen reducing; NO3, nitrate reducing; Mn, manganese reducing; Fe, iron reducing; SO4, sulfate reducing; FeSO4, iron- to sulfate-reducing; CH4, methanogenic; X - Y/Z, mixture (X) of waters with different redox ranging from most oxidized (Y) to most reduced (Z); concentrations in milligrams per liter, unless otherwise noted; bedrock wells shaded gray]

Well ID Date Redox class1 DOC category2 Geo- chemical zone3 Temperature, water (degrees C)

Specific 

conductance 

(μS/cm at 

25 degrees 

Celsius)

pH, 

field HCO3−

Dissolved 

oxygen 

(DO)

H S 2

plus 

HS−

(as S)

CH4 Ca Mg K Na Br −

WY94 10/27/04 O2 DOC3 1A -- -- -- -- 55.2 -- 0.003 -- -- -- -- --WY94 2/8/05 O2 DOC3 1A 9.5 181 5.7 46 9.5 -- -- 19 5.3 1.1 6.4 0.041WY94 5/3/05 O2 DOC3 1A 10.01 170 5.6 39 11 -- -- 18 5.2 0.8 6.2 0.066WY95 8/2/04 X - O2/SO4 DOC3 1A 16 417 6 93 0.57 0.011 -- 27 7.1 2.7 40 0.082WY95 2/1/05 X - Mn/SO4 DOC3 1A 9.6 349 6.1 83 0.14 0.001 -- 25 6.5 1.9 33 0.063WY95 6/16/05 X - O2/Mn DOC3 1A 11 400 6.0 81 1.2 -- -- 27 7.4 2.1 35 0.1WY96 11/4/04 X - O2/CH4 DOC3 1A 9 550 6.3 129 8.2 -- 0.001 60 13 1.6 27 0.042WY96 2/9/05 O2 DOC3 1A 11.5 581 6.1 99 5.6 -- -- 56 15 1.4 28 0.056WY96 6/15/05 X - O2/SO4 DOC3 1A 15.5 400 6.1 94 7.2 0.028 -- 39 11 1.0 23 --WY97 2/15/05 X - O2/CH4 DOC1 2 10.9 311 6.9 114 8.8 -- 0.001 27 6.3 1.9 27 0.034WY98 8/25/04 X - O2/CH4 DOC2 1B 16 242 6.5 100 2.9 -- 0.014 23 7.1 1.6 14 E0.011WY99 10/19/04 -- DOC2 1A 8.6 163 6.4 60 10 -- -- -- -- -- -- --WY99 10/20/04 X - O2/Mn DOC2 1A 10 160 6.6 -- 8.6 -- 0.003 12 4.5 1.6 13 E0.018WY99 2/3/05 X - O2/Mn DOC2 1A 5.6 134 6.2 27 6.4 -- -- 8.8 3.0 1.2 9.9 <0.1WY99 5/23/05 O2 DOC2 1A 15.5 123 5.5 32 10 -- -- 8.5 3.2 1.3 11 --WY100 8/3/04 O2 DOC1 1A 15 249 6.2 61 4 -- -- 21 5.8 1.6 16 0.046WY100 8/6/04 -- DOC1 1A 11 -- -- -- 53.6 -- 0.001 -- -- -- -- --WY100 12/7/04 -- DOC1 1A -- -- -- -- 4 -- -- -- -- -- -- --WY101 8/4/04 O2 DOC1 1B 14 300 6.5 91 4.0 -- 0.001 25 6.2 2.4 21 0.038
44 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06 Table 7. General chemical characteristics and concentrations of major elements, nutrients, dissolved organic carbon, and ultraviolet absorbance in groundwater samples from wells in the Woodbury study area (2002–06), and from selected wells elsewhere in the Pomperaug and Hartford Basins, Connecticut. .—Continued [ID, identifier; --, not measured; NA, not applicable; <, less than; E, estimated value below minimum reporting level; mS/cm, microsiemens per centimeter at 25 degrees Celsius; C, Celsius; HCO3−, bicarbonate; DO, dissolved oxygen; H2S plus HS-, sulfides; CH4, methane; Ca, calcium; Mg, magnesium; K, potassium; Na, sodium; Br−, bromide; Cl−, chloride; F-, fluoride; SO42−, sulfate; SiO2, silica; NH4

+, ammonia; NO2

−, nitrite; 

NO3

−, nitrate; PO43−, orthophosphate; DOC, dissolved organic carbon; UV, ultraviolet; nm, nanometers; SI, saturation index; cm, centimeters; redox, oxidation–reduction; O2, oxygen reducing; NO3, nitrate reducing; 

Mn, manganese reducing; Fe, iron reducing; SO4, sulfate reducing; FeSO4, iron- to sulfate-reducing; CH4, methanogenic; X - Y/Z, mixture (X) of waters with different redox ranging from most oxidized (Y) to most reduced (Z); concentrations in milligrams per liter, unless otherwise noted; bedrock wells shaded gray]

Well ID Cl−

Cl:Br 

mass 

ratio

F- SO4

2− SiO2 NH4

+

(as N)

NO2

−

(as N)

NO3

− plus 

NO2

−

(as N)

PO4

3−

(as P) DOC

UV 

absorbance, 

254 nm 

(units 

per cm)

UV 

absorbance, 

280 nm 

(units per cm)

SI 

(calcite)

SI 

(quartz) Water type

WY94 15 360 <0.1 9.0 15 <0.04 <0.008 4.2 <0.006 0.60 0.0048 <0.0035 -2.97 0.617 Ca-Mg-HCO3-ClWY94 18 270 <0.1 11 13 <0.04 <0.008 2.7 <0.006 0.48 0.0080 0.0060 -3.14 0.549 Ca-Mg-HCO3-ClWY95 71 870 <0.17 14 16 E0.028 <0.008 0.26 0.018 1.8 0.016 0.010593 -2.15 0.540 Na-Ca-Cl−HCO3WY95 54 860 <0.1 11 14 <0.04 E0.004 1.4 E0.005 1.1 0.022 0.0181 -2.21 0.588 Na-Ca-Cl−HCO3WY95 67 480 <0.1 12 14 <0.04 <0.008 1.6 0.008 0.72 0.0079 0.0053906 -2.26 0.565 Na-Ca-Cl−HCO3WY96 89 2,100 0.14 20 37 E0.033 <0.008 1.2 0.022 0.66 0.0090 0.0059 -1.50 1.02 Ca-Mg-Na-Cl−HCO3WY96 110 1,900 0.13 18 36 <0.04 <0.008 1.2 0.011 0.83 0.0086 0.0058 -1.79 0.964 Ca-Mg-Na-Cl−HCO3WY96 60 -- 0.16 20 33 <0.04 <0.008 1.2 0.014 0.62 <0.0035 <0.0035 -1.90 0.865 Ca-Na-Mg-Cl−HCO3WY97 22 640 0.17 28 17 <0.04 <0.008 0.85 E0.004 -- 0.025 0.0170 -0.882 0.660 Ca-Na-HCO3WY98 17 -- <0.17 7.0 17 E0.038 <0.008 <0.06 0.014 2.2 0.050 0.035 -1.66 0.579 Ca-Na-Mg-HCO3-ClWY99 -- -- -- -- -- -- -- -- -- 1.4 0.11 0.089 -- -- --WY99 16 -- E0.079 7.0 19 <0.04 <0.008 <0.06 E0.003 -- -- -- -2.33 0.736 Ca-Na-Mg-HCO3-ClWY99 17 -- <0.1 12 14 <0.04 <0.008 0.07 <0.006 1.2 0.058 0.047 -0.882 0.660 Ca-Na-HCO3WY99 16 -- <0.1 10 15 <0.04 <0.008 E0.048 <0.006 1.3 0.13 0.110 -1.66 0.579 Ca-Na-Mg-HCO3-ClWY100 28 610 <0.17 16 16 <0.04 <0.008 2.3 0.015 0.39 0.0043 <0.0035 -2.22 0.561 Ca-Na-Mg-HCO3-ClWY100 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY100 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY101 32 830 <0.17 16 16 <0.04 <0.008 1.6 -- 0.50 0.0059 0.004 -1.69 0.569 Ca-Na-HCO3-ClWY101 -- -- -- -- -- -- -- -- -- -- -- -- -1.69 0.574 Ca-Na-HCO3-Cl
Aquifer Chemistry 45

Table 7. General chemical characteristics and concentrations of major elements, nutrients, dissolved organic carbon, and ultraviolet absorbance in groundwater samples from wells in the Woodbury study area (2002–06), and from selected wells elsewhere in the Pomperaug and Hartford Basins, Connecticut. —Continued[ID, identifier; --, not measured; NA, not applicable; <, less than; E, estimated value below minimum reporting level; mS/cm, microsiemens per centimeter at 25 degrees Celsius; C, Celsius; HCO3−, bicarbonate; DO, dissolved oxygen; H2S plus HS-, sulfides; CH4, methane; Ca, calcium; Mg, magnesium; K, potassium; Na, sodium; Br−, bromide; Cl−, chloride; F-, fluoride; SO42-, sulfate; SiO2, silica; NH4+, ammonia; NO2−, nitrite; NO3−, nitrate; PO43−, orthophosphate; DOC, dissolved organic carbon; UV, ultraviolet; nm, nanometers; SI, saturation index; cm, centimeters; redox, oxidation–reduction; O2, oxygen reducing; NO3, nitrate reducing; Mn, manganese reducing; Fe, iron reducing; SO4, sulfate reducing; FeSO4, iron- to sulfate-reducing; CH4, methanogenic; X - Y/Z, mixture (X) of waters with different redox ranging from most oxidized (Y) to most reduced (Z); concentrations in milligrams per liter, unless otherwise noted; bedrock wells shaded gray]

Well ID Date Redox class1 DOC category2 Geo- chemical zone3 Temperature, water (degrees C)

Specific 

conductance 

(μS/cm at 

25 degrees 

Celsius)

pH, 

field HCO3−

Dissolved 

oxygen 

(DO)

H S 2

plus 

HS−

(as S)

CH4 Ca Mg K Na Br −

WY101 12/7/04 -- DOC1 1B -- -- 6.4 -- 6.5 <0.002 -- -- -- -- -- --WY102 8/5/04 X - O2/CH4 DOC2 1A 13.5 252 6.2 63 2.3 -- 0.003 17 4.5 1.1 24 0.030WY102 11/30/04 X - O2/CH4 DOC2 1A 12.4 257 6.3 73 1.7 -- 0.002 14 4.2 1.0 30 <0.02WY102 5/24/05 X - O2/Fe DOC2 1A 9 251 5.9 89 3.0 -- -- 10 3.3 0.7 38 --WY106 12/27/04 X - NO3/CH4 DOC1 2B 11.1 711 9 13 0.15 0.013 0.002 58 0.32 0.5 94 E0.017WY114,6 10/23/02 O2 NA NA 10.5 147 6.2 64 2.7 <0.002 -- 23 4.9 1.7 9.7 0.030WY664,6 11/7/02 X - O2/Fe NA NA 15 358 6.4 70 1.1 <0.002 -- 22 3.6 2.9 26 0.040WY674,6 4/17/03 O2 NA NA 10.5 236 6.6 82 9 <0.002 -- 23 7.0 1.3 15 0.020WY684,6 4/16/03 O2 NA NA 13 153 6.3 24 5.9 <0.002 -- 11 3.4 1.7 12 0.010SB1124,6 10/28/02 Mn DOC1 NA 13 265 6.3 35 0.3 <0.002 -- 21 5.0 2.5 31 0.030SB1184,6 10/22/02 X - NO3/Fe DOC1 NA 12.6 348 6.2 94 0.3 <0.002 -- 31 7.3 1.6 20 0.040SB1194,6 11/5/02 X - O2/NO3 DOC1 NA 9.5 64 5.9 15 8.3 <0.002 -- 7 1.7 0.7 3 0.020SB1214,6 11/20/02 O2 DOC1 NA 11.5 278 6.5 75 1.6 <0.002 -- 32 6.4 1.8 13 0.020WY654,7 6/6/02 O2 DOC1 1A 11 126 6.2 34 7.1 <0.002 <0.001 14 3.5 1.5 10 <0.03WY654,7 12/13/04 O2 DOC1 1A 10.5 179 6.2 36 7.4 <0.002 -- 15 3.8 1.6 11 --WY654,7 4/11/05 O2 DOC1 1A 10.0 178 6.0 33 8.2 <0.002 -- 15 3.8 1.4 11 --WY654,7 6/21/05 O2 DOC1 1A 12.5 187 5.9 37 8.1 <0.002 -- 16 3.8 1.6 11 --WY654,7 11/9/05 O2 DOC1 1A 11.6 184 5.9 33 8.2 <0.002 -- 16 3.7 1.4 11 --SB1204,7 11/15/02 O2 DOC3 NA 15 663 6.6 121 1.3 <0.002 <0.001 37 12 2.1 38 0.041F3444,8 5/30/02 X - NO3/Fe NA NA 8 684 8 79 <0.1 -- <0.001 111 17 2.4 13 0.030S4014,8 5/23/02 O2 NA NA 7.3 414 7.3 180 6.6 -- -- 68 7.3 0.7 9.6 0.030
46 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06 Table 7. General chemical characteristics and concentrations of major elements, nutrients, dissolved organic carbon, and ultraviolet absorbance in groundwater samples from wells in the Woodbury study area (2002–06), and from selected wells elsewhere in the Pomperaug and Hartford Basins, Connecticut. .—Continued [ID, identifier; --, not measured; NA, not applicable; <, less than; E, estimated value below minimum reporting level; mS/cm, microsiemens per centimeter at 25 degrees Celsius; C, Celsius; HCO3−, bicarbonate; DO, dissolved oxygen; H2S plus HS-, sulfides; CH4, methane; Ca, calcium; Mg, magnesium; K, potassium; Na, sodium; Br−, bromide; Cl−, chloride; F-, fluoride; SO42−, sulfate; SiO2, silica; NH4

+, ammonia; NO2

−, nitrite; 

NO3

−, nitrate; PO43−, orthophosphate; DOC, dissolved organic carbon; UV, ultraviolet; nm, nanometers; SI, saturation index; cm, centimeters; redox, oxidation–reduction; O2, oxygen reducing; NO3, nitrate reducing; 

Mn, manganese reducing; Fe, iron reducing; SO4, sulfate reducing; FeSO4, iron- to sulfate-reducing; CH4, methanogenic; X - Y/Z, mixture (X) of waters with different redox ranging from most oxidized (Y) to most reduced (Z); concentrations in milligrams per liter, unless otherwise noted; bedrock wells shaded gray]

Well ID Cl−

Cl:Br 

mass 

ratio

F- SO4

2− SiO2 NH4

+

(as N)

NO2

−

(as N)

NO3

− plus 

NO2

−

(as N)

PO4

3−

(as P) DOC

UV 

absorbance, 

254 nm 

(units 

per cm)

UV 

absorbance, 

280 nm 

(units per cm)

SI 

(calcite)

SI 

(quartz) Water type

WY102 27 900 <0.17 16 14 0.052 <0.008 1.8 0.014 1.0 0.055 0.043 -2.33 0.521 Na-Ca-HCO3-ClWY102 27 -- E0.085 19 14 0.073 <0.008 1.2 E0.005 1.5 0.063 0.049 -2.21 0.533 Na-Ca-HCO3-ClWY102 17 -- E0.086 18 13 0.101 <0.008 0.83 <0.006 2.3 0.15 0.12 -2.75 0.568 Na-Ca-HCO3-ClWY106 5.4 320 0.33 300 21 <0.04 <0.008 <0.06 <0.006 <0.33 0.0063 0.0060 -0.0738 0.699 Na-Ca-SO4WY114,6 20 650 <0.17 13 18 0.04 <0.008 1.7 E0.01 0.4 -- -- -2.22 0.672 Ca-Na-Mg-HCO3-ClWY664,6 52 1,300 <0.17 14 13 0.35 <0.008 1.6 0.08 0.7 -- -- -1.96 0.475 Na-Ca-Cl−HCO3WY674,6 28 1,400 0.03 9.8 20 0.04 <0.008 E2 E0.02 0.3 -- -- -1.72 0.716 Ca-Na-Mg-HCO3-ClWY684,6 24 2,400 0.05 9 8.2 0.03 <0.008 0.6 0.03 0.6 -- -- -2.82 0.3 Ca-Na-Mg-Cl−HCO3SB1124,6 67 2,200 <0.2 14 11 <0.04 <0.008 1.7 0.02 0.4 -- -- -2.39 0.420 Na-Ca-Cl−HCO3SB1184,6 41 1,000 <0.17 15 17 <0.04 <0 .008 1.9 E0.01 0.7 -- -- -1.92 0.622 Ca-Na-HCO3-ClSB1194,6 4 200 <0.2 11 12 E0.02 <0.008 0.07 E0.01 0.4 -- -- -3.64 0.514 Ca-Mg-HCO3-SO4SB1214,6 32 1,600 <0.2 16 19 <0.04 <0.008 2.3 <0.02 E.2 -- -- -1.72 0.684 Ca-Na-Mg-HCO3-ClWY654,7 18 -- <0.1 13 14 E0.03 -- 2.1 <0.02 -- -- -- -2.69 0.567 Ca-Na-HCO3-ClWY654,7 22 -- <0.1 12 15 <.04 <0.008 2.09 <0.006 -- -- -- -2.60 0.562 Ca-Na-Cl−HCO3WY654,7 22 -- <0.1 11 15 <.04 <0.008 2.38 <0.006 -- -- -- -2.89 0.607 Ca-Na-Mg-ClWY654,7 23 -- <0.1 12 15 <.04 <0.008 2.40 <0.006 -- -- -- -2.88 0.570 Ca-Na-Cl−HCO3WY654,7 21 -- <0.1 12 14 <.04 <0.008 2.4 <0.006 0.41 -- -- -2.69 0.564 Ca-Na-HCO3-ClSB1204,7 56 1,400 <2 14 20 <0.04 -- 10.8 <0.02 0.75 -- -- -1.32 0.656 Ca-Na-Mg-HCO3-ClF3444,8 4.3 140 E0.1 300 16 0.05 <0.008 <0.05 0.05 <0.3 -- -- 0.121 0.669 Ca-SO4S4014,8 22 750 <0.1 16 20 <0.04 <0.008 3.9 E0.01 E0.3 -- -- -0.304 0.780 Ca-HCO3
Aquifer Chemistry 47

Table 7. General chemical characteristics and concentrations of major elements, nutrients, dissolved organic carbon, and ultraviolet absorbance in groundwater samples from wells in the Woodbury study area (2002–06), and from selected wells elsewhere in the Pomperaug and Hartford Basins, Connecticut. —Continued[ID, identifier; --, not measured; NA, not applicable; <, less than; E, estimated value below minimum reporting level; mS/cm, microsiemens per centimeter at 25 degrees Celsius; C, Celsius; HCO3−, bicarbonate; DO, dissolved oxygen; H2S plus HS-, sulfides; CH4, methane; Ca, calcium; Mg, magnesium; K, potassium; Na, sodium; Br−, bromide; Cl−, chloride; F-, fluoride; SO42-, sulfate; SiO2, silica; NH4+, ammonia; NO2−, nitrite; NO3−, nitrate; PO43−, orthophosphate; DOC, dissolved organic carbon; UV, ultraviolet; nm, nanometers; SI, saturation index; cm, centimeters; redox, oxidation–reduction; O2, oxygen reducing; NO3, nitrate reducing; Mn, manganese reducing; Fe, iron reducing; SO4, sulfate reducing; FeSO4, iron- to sulfate-reducing; CH4, methanogenic; X - Y/Z, mixture (X) of waters with different redox ranging from most oxidized (Y) to most reduced (Z); concentrations in milligrams per liter, unless otherwise noted; bedrock wells shaded gray]

Well ID Date Redox class1 DOC category2 Geo- chemical zone3 Temperature, water (degrees C)

Specific 

conductance 

(μS/cm at 

25 degrees 

Celsius)

pH, 

field HCO3−

Dissolved 

oxygen 

(DO)

H S 2

plus 

HS−

(as S)

CH4 Ca Mg K Na Br −

SO1104,9 9/3/92 O2 DOC1 NA 11.5 103 7.2 40 9.3 -- -- 12 2.5 1.2 4.0 <0.1NBR1184,9 8/27/93 O2 DOC2 NA 19 314 7.5 126 4.3 -- -- 30 11 2.1 17 0.030BA1044,9 8/5/93 O2 DOC2 NA 11 83 6.1 23 3 -- -- 6.9 1.9 2.4 5.1 0.010P1174,9 07/29/94 O2 DOC1 NA 10 102 6.6 33 12 -- -- 8.4 2.4 0.6 5.1 0.020B4034,9 8/19/93 X - O2/Mn DOC2 NA 19 500 8 272 8.9 -- -- 54 19 2 21 0.090
48 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06 Table 7. General chemical characteristics and concentrations of major elements, nutrients, dissolved organic carbon, and ultraviolet absorbance in groundwater samples from wells in the Woodbury study area (2002–06), and from selected wells elsewhere in the Pomperaug and Hartford Basins, Connecticut. .—Continued [ID, identifier; --, not measured; NA, not applicable; <, less than; E, estimated value below minimum reporting level; mS/cm, microsiemens per centimeter at 25 degrees Celsius; C, Celsius; HCO3−, bicarbonate; DO, dissolved oxygen; H2S plus HS-, sulfides; CH4, methane; Ca, calcium; Mg, magnesium; K, potassium; Na, sodium; Br−, bromide; Cl−, chloride; F-, fluoride; SO42−, sulfate; SiO2, silica; NH4

+, ammonia; NO2

−, nitrite; 

NO3

−, nitrate; PO43−, orthophosphate; DOC, dissolved organic carbon; UV, ultraviolet; nm, nanometers; SI, saturation index; cm, centimeters; redox, oxidation–reduction; O2, oxygen reducing; NO3, nitrate reducing; 

Mn, manganese reducing; Fe, iron reducing; SO4, sulfate reducing; FeSO4, iron- to sulfate-reducing; CH4, methanogenic; X - Y/Z, mixture (X) of waters with different redox ranging from most oxidized (Y) to most reduced (Z); concentrations in milligrams per liter, unless otherwise noted; bedrock wells shaded gray]

Well ID Cl−

Cl:Br 

mass 

ratio

F- SO4

2− SiO2 NH4

+

(as N)

NO2

−

(as N)

NO3

− plus 

NO2

−

(as N)

PO4

3−

(as P) DOC

UV 

absorbance, 

254 nm 

(units 

per cm)

UV 

absorbance, 

280 nm 

(units per cm)

SI 

(calcite)

SI 

(quartz) Water type

SO1104,9 4.8 -- 0.1 12 16 0.01 <1 0.13 0.03 0.30 -- -- -1.66 0.614 Ca-HCO3-SO4NBR1184,9 28 930 <0.1 24 16 0.03 -- 0.74 0.02 0.7 -- -- -0.427 0.495 Ca-Mg-Na-HCO3-ClBA1044,9 8.7 870 <1 6.6 9 <.01 <1 0.11 <1 0.7 -- -- -3.230 0.372 Ca-Na-Mg-HCO3-ClP1174,9 4 200 <0.1 13 13 0.02 <1 0.098 0.02 0.4 -- -- -2.51 0.388 Ca-Na-Mg-HCO3B4034,9 18 200 0.2 7 16 0.06 <1 <0.06 0.02 8.3 -- -- 0.610 0.491 Ca-Mg-HCO3

1Details on redox classification scheme shown in Appendix 4.2DOC category: DOC1 DOC2 DOC3

DOC source Background DOC Naturally high DOC (buried wetland, riparian 

zone/losing stream, or organic-rich source rocks)

Septic leachate DOC

Redox potential class O2/NO3/Mn O2/NO3/Mn O2/NO3/Mn

3Geochemical zones: 1A 1B 2A 2B

Aquifer description Glacial aquifer, 

shallow/ intermediate

Glacial aquifer, deep (within 3 meters 

of bedrock)

BR, (upper 30 meters of 

bedrock)

BR, lower (more than 30 

meters below top of bedrock

Redox potential class O2 O2/NO3/Mn O2/NO3/Mn Mn/Fe/SO4pH range 5.3–6.4 106.41–7.5 106.9–8.3 > 8.3

4Not sampled as part of this study.5Analyzed in laboratory from dissolved gas sample.6Glacial, public-supply well (regional-scale TANC Study).7Glacial, domestic-supply well (major aquifer study) in Pomperaug Basin.8Glacial, domestic-supply well (major aquifer study) in Hartford Basin.9Glacial well in forested, undeveloped land, Hartford Basin.10The exceptions to these zones include wells WY82 and WY65, which have pH values below the deep glacial aquifer range, and WY83, which has a pH value above the shallow glacial aquifer range.
Aquifer Chemistry 49

with the Taine Mountain Formation (fig. 2). Bedrock well 

WY106, however, is screened deeper in the Orenaug Basalt 

and had much different groundwater chemistry than other 

bedrock wells sampled—most notably high concentrations 

of SO4

2−

 (table 7; fig. 14B), as well as Na and Ca and other 

constituents (B, F, Li, Mo, Se, Sr, and Zn; table 8). The SO4

2−

concentration of 300 mg/L in groundwater from WY106 

exceeded the National Secondary Drinking Water Regulations 

of 250 mg/L (USEPA, 2006b). WY106 has some similarities 

in chemistry to that of some glacial aquifer wells that overlie 

Mesozoic rocks in the Hartford and Newark Basins. The water 

sample from well F344, for example, had similar major-ion 

chemistry to the sample from well WY106 (low Cl−, high 

SO4

2−

), although the F344 sample had lower concentrations 

of Na and higher concentrations of Ca, Mg, and HCO3

-

 than 

did WY106, which probably reflect interbasinal variations in 

chemistry of lithologic units (fig. 13; tables 7 and 8). Rock 

samples from Mesozoic shales of the Hartford Basin are 

enriched in B (van de Kamp and Leake, 1996; p. 107) and 

Ba (Hubert and others, 1992) relative to other Mesozoic rocks. 

The concentration of Ba in the water sample from WY106 was 

relatively low, however.

Several domestic bedrock wells in the valley bottom 

have been reported to contain high concentrations of SO4

2−

, 

including a sample with 1,300 mg/L SO4

2−

 from a well that is 

located about 2 km north of WY106 (J.L. Pond, Pomperaug 

River Watershed Coalition, oral commun., 2003) and another 

from a well 0.4 km to the north. Several residents in the 

study area with domestic bedrock wells deeper than about 

45 m below land surface reported poor water quality with 

high concentrations of SO4

2−

 and Na. High concentrations of 

dissolved Na in the deep bedrock of the Pomperaug Basin 

are consistent with the abundance of albite overgrowths 

observed in Newark Supergroup rocks by other studies 

(Gray, 1988; Merino and others, 1997). Groundwater 

samples from sedimentary-bedrock aquifers in the Newark 

Supergroup of the Passaic River Basin in New Jersey had high 

concentrations of Ba, Ca, Mg, Sr, and SO4

2−

 relative to those 

from other aquifers in that area, and SO4

2− concentrations 

were directly related to well depths (Czarnik and Kozinski, 

1994). The dissolved molar ratio of SO4

2− to Ca (fig. 14B) is 

1:1, consistent with gypsum dissolution, for several samples 

from wells screened in deep glacial deposits. Well WY106, 

screened in the underlying basalt, had the highest SO4

2−

concentration, which might reflect prior dissolution of gypsum 

and, locally, subsequent dedolomitization along the flow path. 

Dedolomitization is a process, whereby, as a result of gypsum 

or anhydrite dissolution, dolomite dissolves and calcite 

precipitates (Plummer and others, 1990). Dolomite is present 

in Mesozoic rocks in the Pomperaug Basin but is mainly 

0

0

500 1,000 1,500

50

40

30

20

10

SPECIFIC CONDUCTANCE AT 25 DEGREES CELSIUS,

 IN MICROSIEMENS PER CENTIMETER

DEPTH OF WELL SCREEN, IN METERS 

BELOW LAND SURFACE

68 67

66

11

SB119

SB112

SB121

SB118

70

73

81

86

87

97 106

78

83

79 403 85

89

90

95

71

71

95 74

96

120

Septic-system

leachate effects

100

EXPLANATION

Glacial deposits, shallow, and identifier

Glacial deposits, deep

Bedrock, shallow

Bedrock, deep

PSW-1

Glacial deposits, shallow

 (Hartford Basin)

Glacial deposits, domestic well

 (Pomperaug Basin)

Glacial deposits, public-supply well

 (Pomperaug Basin)

90

Figure 11. Specific conductance as a function of depth of well screen below land surface for groundwater samples from wells 

in the Woodbury study area, and from selected wells elsewhere in the Pomperaug and Hartford Basins, Connecticut.
50 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

Table 8. Dissolved concentrations of trace elements, stable isotope ratios, and radionuclides in groundwater samples from wells in the Woodbury, Connecticut (2002–06), study area, and from selected wells elsewhere in the Pomperaug and Hartford Basins.—Continued[Concentrations in micrograms per liter, unless otherwise noted; Al, aluminum; Sb, antimony; As, arsenic; Ba, barium; Be, beryllium; B, boron; Cd, cadmium; Cr, chromium; Co, cobalt; Cu, copper; Fe, iron; Pb, lead; Li, lithium; Mn, manganese; Mo, molybdenum; Ni, nickel; N, nitrogen; Se, selenium; Ag, silver; Sr, strontium; Tl, thallium; U, uranium; V, vanadium; Zn, zinc; H-1, protium; H-2, deuterium; O, oxygen; C, carbon; DIC, dissolved inorganic carbon; per mil, parts per thousand; scu, sigma combined uncertainty; bedrock wells shaded gray; <, less than; E, estimated value below minimum reporting level; --, no data; pCi/L, picocuries per liter]

Well 

ID Date Al Sb As 

As

(III) 

(arsenite)

As

(V) 

(arsenate)

Ba Be B Cd Cr Co Cu Fe Pb Li Mn Mo Ni Se Ag Sr 

PSW-1 10/23/02 <1.6 <0.3 <0.26 -- -- 14 <0.06 66 <0.037 <0.8 0.19 0.66 <10 E0.04 1.4 0.31 E0.27 0.89 <0.5 <0.2 102PSW-1 12/30/03 <1.6 <0.2 E0.11 <1 <1.2 13 <0.06 65 <0.04 <0.8 0.27 28 <6.4 0.44 1.3 0.31 <0.4 0.90 E0.24 <0.2 107PSW-1 8/11/04 <1.6 <0.2 <0.2 <0.26 <0.26 14 <0.06 72 <0.04 <0.8 0.31 28 <6.4 0.5 1.5 0.30 <0.4 1.1 <0.4 <0.2 110PSW-1 11/30/04 -- -- -- -- -- -- -- -- -- -- -- -- <6.4 -- -- <0.6 -- -- -- -- --PSW-1 7/11/06 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY35 12/1/03 E1.1 <0.2 2.2 -- 41 <0.06 19 E0.039 0.61 2.4 E0.23 5,100 <0.08 1.5 540 0.42 1.4 <0.4 <0.2 50WY35 9/16/04 -- -- -- -- -- -- -- -- -- -- -- -- 3,500 -- -- 540 -- -- -- -- --WY35 11/29/05 -- -- -- -- -- -- -- -- -- -- -- -- 4,400 -- -- 400 -- -- -- -- --WY531 4/12/85 -- -- 1 -- -- 29 <0.5 40 <1 <1 <3 <10 -- <10 <4 49 <10

M -- <1 90

WY69 12/10/03 <1.6 <0.2 <0.2 <1 <1.2 15 <0.06 15 <0.04 <0.8 0.11 <0.33 <6.4 <0.08 0.76 1.2 0.45 0.69 <0.4 <0.2 117WY70 12/29/03 <1.6 <0.2 <0.2 <1 <1.2 18 <0.06 34 <0.04 <0.8 0.19 0.61 E3.6 <0.08 0.64 1.1 E0.23 0.77 E0.23 <0.2 93WY71 12/22/03 <1.6 <0.2 <0.2 <1 <1.2 47 <0.06 32 <0.04 <0.8 0.26 0.74 E6.0 <0.08 <0.6 1.6 <0.4 0.94 <0.4 <0.2 137WY71 7/27/04 -- -- -- -- -- -- -- -- -- -- -- -- 6.8 -- -- 1.8 -- -- -- -- --WY71 1/7/05 -- -- -- -- -- -- -- -- -- -- -- -- E5.7 -- -- 1.8 -- -- -- -- --WY71 5/18/05 -- -- -- -- -- -- -- -- -- -- -- -- E3.3 -- -- 1.2 -- -- -- -- --WY72 12/16/03 <1.6 <0.2 <0.2 <1 <1.2 7 <0.06 23 <0.04 <0.8 0.12 E0.23 <6.4 <0.08 2.4 2.7 <0.4 0.53 <0.4 <0.2 91WY73 12/17/03 <1.6 <0.2 <0.2 <1 <1.2 23 <0.06 102 <0.04 <0.8 0.39 0.51 E3.7 <0.08 1.3 1.8 <0.4 1.1 <0.4 <0.2 130WY74 11/6/03 <1.6 <0.2 E0.1 -- -- 40 <0.06 124 <0.04 <0.8 0.40 0.58 E4 <0.08 0.74 3.4 <0.4 1.3 <0.4 <0.2 140WY74 7/28/04 -- -- -- -- -- -- -- -- -- -- -- -- 10.9 -- -- E0.57 -- -- -- -- --WY74 1/10/05 -- -- -- -- -- -- -- -- -- -- -- -- <6.4 -- -- E0.34 -- -- -- -- --WY74 6/15/05 -- -- -- -- -- -- -- -- -- -- -- -- 7.3 -- -- 0.66 -- -- -- -- --WY75 11/13/03 <1.6 <0.2 E0.1 -- -- 11 <0.06 21 <0.04 E0.41 0.093 E0.29 <6.4 <0.08 2.4 0.57 E0.32 0.67 E0.30 <0.2 136WY76 11/12/03 <1.6 <0.2 <0.2 -- -- 24 <0.06 76 E0.025 E0.65 0.45 0.55 E5.7 0.19 1.1 17 0.55 1.4 <0.4 <0.2 96WY76 7/26/04 -- -- -- -- -- -- -- -- -- -- -- -- E3.7 -- -- 2.8 -- -- -- -- --WY76 1/4/05 -- -- -- -- -- -- -- -- -- -- -- -- E5.0 -- -- 2.3 -- -- -- -- --
Aquifer Chemistry 51

Table 8. Dissolved concentrations of trace elements, stable isotope ratios, and radionuclides in groundwater samples from wells in the Woodbury, Connecticut (2002–06), study area, and from selected wells elsewhere in the Pomperaug and Hartford Basins.—Continued[Concentrations in micrograms per liter, unless otherwise noted; Al, aluminum; Sb, antimony; As, arsenic; Ba, barium; Be, beryllium; B, boron; Cd, cadmium; Cr, chromium; Co, cobalt; Cu, copper; Fe, iron; Pb, lead; Li, lithium; Mn, manganese; Mo, molybdenum; Ni, nickel; N, nitrogen; Se, selenium; Ag, silver; Sr, strontium; Tl, thallium; U, uranium; V, vanadium; Zn, zinc; H-1, protium; H-2, deuterium; O, oxygen; C, carbon; DIC, dissolved inorganic carbon; per mil, parts per thousand; scu, sigma combined uncertainty; bedrock wells shaded gray; <, less than; E, estimated value below minimum reporting level; --, no data; pCi/L, picocuries per liter]

Well 

ID Tl U V Zn 

Delta 

H-2/ H-1 

ratio 

(per mil)

Delta 

O-18/ O-16 

ratio 

(per mil)

Delta 

O-18/O-16 

ratio in 

NO3−

(per mil)

Delta 

N-15/N-14 

ratio in 

NO3−

(per mil)

Delta 

S-34/S-32 

ratio in 

SO42− (per 

mil)

Delta 

C-13/C-12 

ratio in 

DIC 

(per mil)

Alpha 

activity, as 

Thorium-230 

(pCi per L)

Gross 

beta, 

as Cs-137 

(pCi per L)

Radon-222 

(pCi per L)

Radon-222 

2scu (pCi/L)

Radium-226 

(pCi per L)

Radium-228 

(pCi per L)

PSW-1 <0.041 0.069 0.56 E0.59 -- -- -- -- -- -- -- -- -- -- -- --PSW-1 <0.04 0.053 0.38 4.0 -47.5 -7.9 3.8 8.5 7.9 -- <1.8 1.6 1,100 34 0.075 <0.48PSW-1 <0.04 0.066 0.58 4.1 -47.0 -7.7 8.3 -19 <1.2 <2.4 1,247 37 0.13 0.50PSW-1 -- -- -- -- -- -- 4.0 8.0 -- -- -- -- -- -- -- --PSW-1 -- -- -- -- -47.8 -7.7 -- -- -- -- -- -- -- -- -- --WY35 <0.04 <0.04 <0.14 1.4 -46.2 -7.6 2.5 7.5 -- -- -- -- -- -- -- --WY35 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY35 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY531 -- -- <6 10 -- -- -- -- -- -- -- -- -- -- -- --WY69 <0.04 0.12 1.0 <0.6 -45.4 -7.6 2.9 5.5 10.2 -- <1.4 1.7 970 33 0.031 <0.62WY70 <0.04 E0.025 E0.11 <0.6 -45.2 -7.6 3.7 7.3 5.8 -- 0.12 1.63 680 29 0.058 <0.47WY71 <0.04 0.056 0.22 E0.44 -45.1 -7.4 9.4 18.2 5.1 -- <2.4 3.5 950 37 -- --WY71 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY71 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY71 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY72 <0.04 0.12 1.1 E0.30 -49.2 -7.9 2.5 6.5 9.8 -- <1.8 <1.4 490 26 0.045 <0.47WY73 <0.04 <0.04 E0.075 <0.6 -48.2 -7.8 4.9 9.8 5.9 -- <1.6 1.9 1,300 36 0.08 <0.45WY74 <0.04 0.057 0.46 0.76 -49.8 -8 3.8 6.6 4.3 -- <3 1.8 1,700 40 0.15 <0.68WY74 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY74 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY74 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY75 <0.04 0.12 1.3 <0.6 -47.3 -7.8 1.3 6.5 10.0 -- 0.28 2.6 880 31 0.036 E0.13WY76 <0.04 <0.04 0.44 E0.50 -49.7 -8.0 3.9 6.9 6.3 -- <1.4 2 1,500 38 0.048 E0.55WY76 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY76 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
52 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06 Table 8. Dissolved concentrations of trace elements, stable isotope ratios, and radionuclides in groundwater samples from wells in the Woodbury, Connecticut (2002–06), study area, and from selected wells elsewhere in the Pomperaug and Hartford Basins.—Continued [Concentrations in micrograms per liter, unless otherwise noted; Al, aluminum; Sb, antimony; As, arsenic; Ba, barium; Be, beryllium; B, boron; Cd, cadmium; Cr, chromium; Co, cobalt; Cu, copper; Fe, iron; Pb, lead; Li, lithium; Mn, manganese; Mo, molybdenum; Ni, nickel; N, nitrogen; Se, selenium; Ag, silver; Sr, strontium; Tl, thallium; U, uranium; V, vanadium; Zn, zinc; H-1, protium; H-2, deuterium; O, oxygen; C, carbon; DIC, dissolved inorganic carbon; per mil, parts per thousand; scu, sigma combined uncertainty; bedrock wells shaded gray; <, less than; E, estimated value below minimum reporting level; --, no data; pCi/L, picocuries per liter] Well ID Date Al Sb As As (III) (arsenite) As (V) (arsenate) Ba Be B Cd Cr Co Cu Fe Pb Li Mn Mo Ni Se Ag Sr WY76 6/14/05 -- -- -- -- -- -- -- -- -- -- -- -- 8.0 -- -- 0.79 -- -- -- -- -- WY77 12/9/03 40 <0.2 <0.2 <1 <1.2 10 <0.06 18 <0.04 <0.8 0.19 E0.27 53 <0.08 1.2 160 E0.29 0.77 <0.4 <0.2 70 WY78 11/20/03 10 <0.2 <0.2 <1 <1.2 10 <0.06 13 <0.04 1.1 0.089 3.1 14 0.22 <0.6 6.5 E0.3 1.2 <0.4 <0.2 37 WY78 7/28/04 -- -- -- -- -- -- -- -- -- -- -- -- 17 -- -- 8.0 -- -- -- -- -- WY78 1/11/05 -- -- -- -- -- -- -- -- -- -- -- -- E3.1 -- -- 0.78 -- -- -- -- -- WY78 5/24/05 -- -- -- -- -- -- -- -- -- -- -- -- 12 -- -- 3.4 -- -- -- -- -- WY79 11/4/03 <1.6 <0.2 <0.2 -- -- 34 <0.06 22 E0.024 <0.8 0.83 0.43 E5.0 0.13 1.9 3.9 <0.4 1.1 <0.4 <0.2 148 WY79 7/29/04 -- -- -- -- -- -- -- -- -- -- -- -- 8.7 -- -- 1.6 -- -- -- -- -- WY79 1/31/05 -- -- -- -- -- -- -- -- -- -- -- -- E5.9 -- -- 1.1 -- -- -- -- -- WY79 8/5/05 -- -- -- -- -- -- -- -- -- -- -- -- E5.3 -- -- 0.71 -- -- -- -- -- WY80 11/5/03 1.7 <0.2 <0.2 -- -- 16 <0.06 11 E0.02 E0.63 0.31 0.43 9.4 <0.08 0.98 170 E0.30 1.2 <0.4 <0.2 32 WY80 8/30/04 -- -- -- -- -- -- -- -- -- -- -- -- <6.4 -- -- 140 -- -- -- -- -- WY80 1/11/05 -- -- -- -- -- -- -- -- -- -- -- -- 7.3 -- -- 41 -- -- -- -- -- WY80 5/17/05 -- -- -- -- -- -- -- -- -- -- -- -- E5.6 -- -- 2.0 -- -- -- -- -- WY81 12/2/03 E0.82 <0.2 <0.2 <1 <1.2 28 <0.06 25 <0.04 E0.62 0.14 2.4 11.7 <0.08 2.0 7.2 0.40 2.4 <0.4 <0.2 145 WY81 7/29/04 -- -- -- -- -- -- -- -- -- -- -- -- 7.3 -- -- 5.5 -- -- -- -- -- WY81 1/13/05 -- -- -- -- -- -- -- -- -- -- -- -- <6.4 -- -- 1.7 -- -- -- -- -- WY81 5/4/05 -- -- -- -- -- -- -- -- -- -- -- -- <6.4 -- -- 1.6 -- -- -- -- -- WY82 12/8/03 <1.6 <0.2 <0.2 <1 <1.2 23 <0.06 18 E0.02 <0.8 0.18 0.81 <6.4 <0.08 2.7 43 <0.4 0.97 <0.4 <0.2 140 WY83 11/4/03 <1.6 <0.2 5.8 -- -- 53 <0.06 26 E0.022 E0.46 3.3 E0.36 2,700 <0.08 6.9 2,100 E0.36 1.7 <0.4 <0.2 57
Aquifer Chemistry 53

Table 8. Dissolved concentrations of trace elements, stable isotope ratios, and radionuclides in groundwater samples from wells in the Woodbury, Connecticut (2002–06), study area, and from selected wells elsewhere in the Pomperaug and Hartford Basins.—Continued[Concentrations in micrograms per liter, unless otherwise noted; Al, aluminum; Sb, antimony; As, arsenic; Ba, barium; Be, beryllium; B, boron; Cd, cadmium; Cr, chromium; Co, cobalt; Cu, copper; Fe, iron; Pb, lead; Li, lithium; Mn, manganese; Mo, molybdenum; Ni, nickel; N, nitrogen; Se, selenium; Ag, silver; Sr, strontium; Tl, thallium; U, uranium; V, vanadium; Zn, zinc; H-1, protium; H-2, deuterium; O, oxygen; C, carbon; DIC, dissolved inorganic carbon; per mil, parts per thousand; scu, sigma combined uncertainty; bedrock wells shaded gray; <, less than; E, estimated value below minimum reporting level; --, no data; pCi/L, picocuries per liter]

Well 

ID Tl U V Zn 

Delta 

H-2/ H-1 

ratio 

(per mil)

Delta 

O-18/ O-16 

ratio 

(per mil)

Delta 

O-18/O-16 

ratio in 

NO3−

(per mil)

Delta 

N-15/N-14 

ratio in 

NO3−

(per mil)

Delta 

S-34/S-32 

ratio in 

SO42− (per 

mil)

Delta 

C-13/C-12 

ratio in 

DIC 

(per mil)

Alpha 

activity, as 

Thorium-230 

(pCi per L)

Gross 

beta, 

as Cs-137 

(pCi per L)

Radon-222 

(pCi per L)

Radon-222 

2scu (pCi/L)

Radium-226 

(pCi per L)

Radium-228 

(pCi per L)

WY76 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY77 <0.04 0.041 1 <0.6 -50.1 -7.9 2.0 4.2 5.9 -- <3 2.05 720 33 0.044 <0.56WY78 <0.04 E0.028 <0.14 0.69 -44.6 -7.3 3.0 8.6 6.7 -- <3 2.24 1,100 33 0.031 <0.54WY78 -- -- -- -- -40.6 -6.55 -- -- -- -- -- -- -- -- -- --WY78 -- -- -- -- -48.0 -7.8 -- -- -- -- -- -- -- -- -- --WY78 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY79 <0.04 0.042 0.39 E0.49 -- -- 2.21 11.2 -- -- -- -- -- -- -- --WY79 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY79 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY79 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY80 <0.04 <0.04 0.65 1.05 -44.9 -7.2 -- -- 5.9 -- <0.74 <1.1 1,100 36 0.027 <0.74WY80 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY80 -- -- -- -- -43.0 -6.9 -- -- -- -- -- -- -- -- -- --WY80 -- -- -- -- -- -- -0.61 6.5 -- -- -- -- -- -- -- --WY81 <0.04 0.054 0.38 <0.6 -48.9 -8.0 0.69 7.3 9.7 -- <1.7 1.8 1,000 34 0.097 <0.56WY81 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY81 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY81 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY82 <0.04 0.11 0.36 E0.31 -52.5 -8.3 0.65 7.4 9.3 -- <1.7 2.3 1,800 42 0.051 <0.56WY83 <0.04 E0.024 0.23 0.86 -- -- -- -- -- -- -- -- -- -- -- --
54 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

Table 8. Dissolved concentrations of trace elements, stable isotope ratios, and radionuclides in groundwater samples from wells in the Woodbury, Connecticut (2002–06), study area, and from selected wells elsewhere in the Pomperaug and Hartford Basins.—Continued[Concentrations in micrograms per liter, unless otherwise noted; Al, aluminum; Sb, antimony; As, arsenic; Ba, barium; Be, beryllium; B, boron; Cd, cadmium; Cr, chromium; Co, cobalt; Cu, copper; Fe, iron; Pb, lead; Li, lithium; Mn, manganese; Mo, molybdenum; Ni, nickel; N, nitrogen; Se, selenium; Ag, silver; Sr, strontium; Tl, thallium; U, uranium; V, vanadium; Zn, zinc; H-1, protium; H-2, deuterium; O, oxygen; C, carbon; DIC, dissolved inorganic carbon; per mil, parts per thousand; scu, sigma combined uncertainty; bedrock wells shaded gray; <, less than; E, estimated value below minimum reporting level; --, no data; pCi/L, picocuries per liter]

Well 

ID Date Al Sb As 

As

(III) 

(arsenite)

As

(V) 

(arsenate)

Ba Be B Cd Cr Co Cu Fe Pb Li Mn Mo Ni Se Ag Sr 

WY83 8/31/04 -- -- -- 4.7 2.3 -- -- -- -- -- -- -- 23,000 -- -- 1,800 -- -- -- -- --WY83 1/4/05 -- -- -- -- -- -- -- -- -- -- -- -- 14,000 -- -- 1,800 -- -- -- -- --WY83 4/29/05 -- -- -- -- -- -- -- -- -- -- -- -- 23,000 -- -- 1,700 -- -- -- -- --WY83 7/11/06 -- -- -- 2.2 4.4 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY84 11/18/03 <1.6 <0.2 <0.2 -- -- 11 <0.06 8 0.048 <0.8 0.56 2.0 48 <0.08 1.0 320 0.78 1.5 <0.4 <0.2 65WY84 11/19/03 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY85 11/19/03 11 <0.2 <0.2 -- -- 345 E0.056 34 2.034 1.8 30.4 20.4 3,100 1.6 1.8 11,000 0.46 50 E0.25 <0.2 720WY85 8/10/04 -- -- -- -- -- -- -- -- -- -- -- -- 602 -- -- 7,300 -- -- -- -- --WY85 2/1/05 -- -- -- -- -- -- -- -- -- -- -- -- 670 -- -- 10,000 -- -- -- -- --WY85 6/16/05 -- -- -- -- -- -- -- -- -- -- -- -- 380 -- -- 16,000 -- -- -- -- --WY86 12/4/03 4.8 <0.2 1.8 <1 1.5 38 <0.06 27 E0.026 <0.8 0.15 7.5 E5.0 E0.065 14 16 2.0 1.4 <0.4 <0.2 227WY87 12/18/03 -- -- -- <1 E0.62 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY87 12/29/03 6 <0.2 0.67 -- -- 36 <0.06 11 <0.04 <0.8 0.09 0.85 E5.5 <0.08 6.2 120 2.4 0.34 <0.4 <0.2 173WY87 3/7/05 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY88 11/24/03 4.6 <0.2 0.36 <1 <1.2 10 <0.06 27 E0.022 <0.8 0.44 E0.27 8.3 <0.08 4.1 730 7.9 1.9 <0.4 <0.2 76WY89 8/18/04 5.2 E0.12 <0.2 <0.26 0.61 17 <0.06 51 0.119 E0.68 0.67 1.9 29 0.084 9.5 16 15 3.9 <0.4 <0.2 141WY90 11/9/04 E0.84 <0.2 E0.16 <0.26 0.28 30 <0.06 155 E0.026 E0.75 0.83 1.6 11 <0.08 10 11 0.52 1.4 E0.40 <0.2 212WY90 5/26/05 -- -- -- -- -- -- -- -- -- -- -- -- 16 -- -- 45 -- -- -- -- --WY91 8/19/04 <1.6 <0.2 <0.2 <0.26 <0.26 11 <0.06 33 <0.04 <0.8 0.078 E0.31 <6.4 <0.08 4.0 17 E0.3 0.45 <0.4 <0.2 97WY91 12/14/04 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY92 8/23/04 <1.6 <0.2 <0.2 <0.26 0.80 25 <0.06 23 <0.04 <0.8 0.11 0.5 <6.4 E0.044 3.1 0.7 <0.4 0.43 <0.4 <0.2 105WY92 12/9/04 -- -- -- -- -- -- -- -- -- -- -- -- E3.5 -- -- E0.40 -- -- -- -- --WY92 5/2/05 -- -- -- -- -- -- -- -- -- -- -- -- <6.4 -- -- <0.6 -- -- -- -- --WY93 8/24/04 4.6 <0.2 E0.14 <0.26 0.72 10 <0.06 13 0.177 E0.43 0.18 1.6 <6.4 E0.044 1.4 52 53 1.3 <0.4 <0.2 69WY93 8/25/04 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
Aquifer Chemistry 55

Table 8. Dissolved concentrations of trace elements, stable isotope ratios, and radionuclides in groundwater samples from wells in the Woodbury, Connecticut (2002–06), study area, and from selected wells elsewhere in the Pomperaug and Hartford Basins.—Continued[Concentrations in micrograms per liter, unless otherwise noted; Al, aluminum; Sb, antimony; As, arsenic; Ba, barium; Be, beryllium; B, boron; Cd, cadmium; Cr, chromium; Co, cobalt; Cu, copper; Fe, iron; Pb, lead; Li, lithium; Mn, manganese; Mo, molybdenum; Ni, nickel; N, nitrogen; Se, selenium; Ag, silver; Sr, strontium; Tl, thallium; U, uranium; V, vanadium; Zn, zinc; H-1, protium; H-2, deuterium; O, oxygen; C, carbon; DIC, dissolved inorganic carbon; per mil, parts per thousand; scu, sigma combined uncertainty; bedrock wells shaded gray; <, less than; E, estimated value below minimum reporting level; --, no data; pCi/L, picocuries per liter]

Well 

ID Tl U V Zn 

Delta 

H-2/ H-1 

ratio 

(per mil)

Delta 

O-18/ O-16 

ratio 

(per mil)

Delta 

O-18/O-16 

ratio in 

NO3−

(per mil)

Delta 

N-15/N-14 

ratio in 

NO3−

(per mil)

Delta 

S-34/S-32 

ratio in 

SO42− (per 

mil)

Delta 

C-13/C-12 

ratio in 

DIC 

(per mil)

Alpha 

activity, as 

Thorium-230 

(pCi per L)

Gross 

beta, 

as Cs-137 

(pCi per L)

Radon-222 

(pCi per L)

Radon-222 

2scu (pCi/L)

Radium-226 

(pCi per L)

Radium-228 

(pCi per L)

WY83 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY83 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY83 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY83 -- -- -- -- -46.3 -7.6 -- -- 16.4 -17.71 -- -- -- -- -- --WY84 <0.04 0.073 1.4 E0.44 -45.4 -7.3 -- -- 5.9 -- <1.6 <1.5 -- -- 0.047 <0.5WY84 -- -- -- -- -- -- -- -- -- -- -- -- 740 30 -- --WY85 0.077 0.076 0.44 2.6 -45.1 -7.4 -- -- 5.9 -- <7.8 8.6 1,800 28 0.42 0.80WY85 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY85 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY85 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY86 <0.04 1.3 E0.12 0.95 -49.9 -8.0 4.2 8.2 11.8 -- 3.5 3.5 8,600 84 0.95 <0.62WY87 -- -- -- -- -- -- -- -- 6.9 -- -- -- 1,600 28WY87 <0.04 0.50 6.3 <0.6 -- -- -- -- -- -- <1.3 1.9 0.071 <0.51WY87 -- -- -- -- -44.7 -7.3 -- -- -- -- -- -- -- -- -- --WY88 <0.04 0.95 0.70 <0.6 -46.8 -7.6 3.5 7.9 7.1 -- <1.9 3.7 2,200 45 <0.018 <0.57WY89 <0.04 0.35 0.99 3.0 -- -- -- -- 4.3 -- -- -- -- -- -- --WY90 <0.04 0.34 1.2 1.1 -- -- -0.88 9.5 5.2 -- -- -- -- -- -- --WY90 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY91 E0.04 0.13 0.8 <0.6 -- -- -- -- 5.0 -17.18 1.2 3.4 1,300 31 0.096 <0.52WY91 -- -- -- -- -- -- 2.4 6.5 -- -- -- -- -- -- -- --WY92 <0.04 E0.028 0.18 <0.6 -- -- -- -- 6.7 -17.6 1.1 <2.4 970 34 0.12 <0.8WY92 -- -- -- -- -- -- 3.2 9.1 -- -- -- -- -- -- -- --WY92 -- -- -- -- -- -- 2.1 9.3 -- -- -- -- -- -- -- --WY93 <0.04 1.8 1.8 E0.48 -- -- -- -- 5.8 -18.0 <0.9 1.8 -- 0.074 <0.69WY93 -- -- -- -- -- -- -- -- -- -- -- -- 770 33 -- --
56 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

Table 8. Dissolved concentrations of trace elements, stable isotope ratios, and radionuclides in groundwater samples from wells in the Woodbury, Connecticut (2002–06), study area, and from selected wells elsewhere in the Pomperaug and Hartford Basins.—Continued[Concentrations in micrograms per liter, unless otherwise noted; Al, aluminum; Sb, antimony; As, arsenic; Ba, barium; Be, beryllium; B, boron; Cd, cadmium; Cr, chromium; Co, cobalt; Cu, copper; Fe, iron; Pb, lead; Li, lithium; Mn, manganese; Mo, molybdenum; Ni, nickel; N, nitrogen; Se, selenium; Ag, silver; Sr, strontium; Tl, thallium; U, uranium; V, vanadium; Zn, zinc; H-1, protium; H-2, deuterium; O, oxygen; C, carbon; DIC, dissolved inorganic carbon; per mil, parts per thousand; scu, sigma combined uncertainty; bedrock wells shaded gray; <, less than; E, estimated value below minimum reporting level; --, no data; pCi/L, picocuries per liter]

Well 

ID Date Al Sb As 

As

(III) 

(arsenite)

As

(V) 

(arsenate)

Ba Be B Cd Cr Co Cu Fe Pb Li Mn Mo Ni Se Ag Sr 

WY94 10/14/04 <1.6 <0.2 <0.2 <0.26 0.77 20 <0.06 12 <0.04 1.3 0.115 1.4 14 <0.08 E0.43 6.6 0.50 3.0 <0.4 <0.2 81WY94 2/8/05 -- -- -- -- -- -- -- -- -- -- -- -- 12 -- -- 5.1 -- -- -- -- --WY94 5/3/05 -- -- -- -- -- -- -- -- -- -- -- -- E5.1 -- -- 2.7 -- -- -- -- --WY95 8/2/04 -- -- -- <0.26 <0.26 -- -- -- -- -- -- -- 8.7 -- -- 490 -- -- -- -- --WY95 2/1/05 -- -- -- -- -- -- -- -- -- -- -- -- 8.6 -- -- 120 -- -- -- -- --WY95 6/16/05 -- -- -- -- -- -- -- -- -- -- -- -- <6.4 -- -- 94 -- -- -- -- --WY96 11/4/04 E1.066 <0.2 E0.12 <0.26 0.66 26 <0.06 35 E0.029 2.0 0.20 2.4 15 E0.043 34 18 E0.38 4.6 E0.22 <0.2 100WY96 11/9/04 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY96 2/9/05 -- -- -- -- -- -- -- -- -- -- -- -- 9.8 -- -- 3.6 -- -- -- -- --WY96 6/15/05 -- -- -- -- -- -- -- -- -- -- -- -- 13 -- -- 2.3 -- -- -- -- --WY97 2/15/05 E1.016 E0.1 0.2 <1 <1.2 32 <0.06 9.9 E0.039 E0.8 0.20 2.4 <6.4 <0.08 8.4 75 4.4 2.8 0.56 <0.2 130WY98 8/25/04 1.951 E0.11 E0.19 E0.18 0.8 11 <0.06 26 0.093 <0.8 0.34 2.4 3.2 0.201 E0.53 870 12 1.4 <0.4 <0.2 57WY98 8/26/04 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY99 10/20/04 E1.3 <0.2 E0.16 <0.26 0.62 11 <0.06 14 E0.028 <0.8 0.33 0.51 <18 <0.08 E0.42 530 1.2 1.4 E0.27 <0.2 55WY99 10/21/04 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY99 2/3/05 -- -- -- -- -- -- -- -- -- -- -- -- 19 -- -- 66 -- -- -- -- --WY99 5/23/05 -- -- -- -- -- -- -- -- -- -- -- -- 6.5 -- -- 35 -- -- -- -- --WY100 8/3/04 <1.6 <0.2 <0.2 <0.26 <0.26 15 <0.06 37 <0.04 E0.50 0.28 E0.36 <6.4 <0.08 1.1 1.2 <0.4 0.85 <0.4 <0.2 90WY101 8/4/04 <1.6 <0.2 <0.2 <0.26 0.86 16 <0.06 120 <0.04 <0.8 0.40 2.5 <6.4 0.10 3.0 1.7 E0.28 1.6 E0.28 <0.2 99WY102 8/5/04 5.16 <0.2 E0.14 -- -- 12 <0.06 25 <0.04 <0.8 0.61 1.3 44 <0.08 E0.37 240 0.45 0.61 <0.4 <0.2 67WY102 11/30/04 -- -- -- -- -- -- -- -- -- -- -- -- 140 -- -- 180 -- -- -- -- --WY102 5/24/05 -- -- -- -- -- -- -- -- -- -- -- -- 840 -- -- 210 -- -- -- -- --WY106 12/27/04 3.179 <0.2 0.28 <1 <1.2 9 <0.06 212 <0.04 <0.8 0.17 3.9 <6.4 <0.08 47 0.32 2.2 0.42 0.67 <0.2 590WY111,2 10/23/02 <2 <0.05 0.3 -- -- 50 <0.06 27 <0.04 <0.8 0.099 9.2 <10 1.1 5.5 1.5 0.2 1.8 <0.3 <1 74WY661,2 11/7/02 <2 <0.05 1.6 -- -- 120 <0.06 37 0.04 <0.8 1 0.3 4,700 0.18 3.9 1,800 1.4 0.67 <0.3 <1 140
Aquifer Chemistry 57

Table 8. Dissolved concentrations of trace elements, stable isotope ratios, and radionuclides in groundwater samples from wells in the Woodbury, Connecticut (2002–06), study area, and from selected wells elsewhere in the Pomperaug and Hartford Basins.—Continued[Concentrations in micrograms per liter, unless otherwise noted; Al, aluminum; Sb, antimony; As, arsenic; Ba, barium; Be, beryllium; B, boron; Cd, cadmium; Cr, chromium; Co, cobalt; Cu, copper; Fe, iron; Pb, lead; Li, lithium; Mn, manganese; Mo, molybdenum; Ni, nickel; N, nitrogen; Se, selenium; Ag, silver; Sr, strontium; Tl, thallium; U, uranium; V, vanadium; Zn, zinc; H-1, protium; H-2, deuterium; O, oxygen; C, carbon; DIC, dissolved inorganic carbon; per mil, parts per thousand; scu, sigma combined uncertainty; bedrock wells shaded gray; <, less than; E, estimated value below minimum reporting level; --, no data; pCi/L, picocuries per liter]

Well 

ID Tl U V Zn 

Delta 

H-2/ H-1 

ratio 

(per mil)

Delta 

O-18/ O-16 

ratio 

(per mil)

Delta 

O-18/O-16 

ratio in 

NO3−

(per mil)

Delta 

N-15/N-14 

ratio in 

NO3−

(per mil)

Delta 

S-34/S-32 

ratio in 

SO42− (per 

mil)

Delta 

C-13/C-12 

ratio in 

DIC 

(per mil)

Alpha 

activity, as 

Thorium-230 

(pCi per L)

Gross 

beta, 

as Cs-137 

(pCi per L)

Radon-222 

(pCi per L)

Radon-222 

2scu (pCi/L)

Radium-226 

(pCi per L)

Radium-228 

(pCi per L)

WY94 <0.04 0.057 0.61 E0.38 -- -- -- -- 6.6 -20.6 <0.44 0.74 590 30 0.080 <0.69WY94 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY94 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY95 -- -- -- -- -- -- -- -- -- -- -- -- 1,200 35 -- --WY95 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY95 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY96 <0.04 0.096 1.9 0.78 -- -- -- -- 4.6 -20.7 -- -- 1,200 36 -- --WY96 -- -- -- -- -- -- -- -- -- -- <1.8 2.77 -- -- 0.068 <0.44WY96 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY96 -- -- -- -- -- -- 1.1 7.6 -- -- -- -- -- -- -- --WY97 <0.04 1.4 E0.14 0.86 -48.1 -7.8 -- -- 0.39 -17.6 0.049 4.4 13,000 99 0.14 0.14WY98 <0.04 0.47 1.1 9.2 -44.1 -7.2 -- -- 6.7 -12.1 -- -- -- -- -- --WY98 -- -- -- -- -- -- -- -- <0.9 1.7 740 30 0.057 0.16WY99 <0.04 E0.035 0.74 0.65 -- -- -- -- 8.5 -- -- -- -- -- 0.17 <1.1WY99 -- -- -- -- -- -- -- -- -- -- -- -- 800 30 -- --WY99 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY99 -- -- -- -- -43.3 -7.1 1.2 5.9 -- -- -- -- -- -- -- --WY100 <0.04 E0.024 E0.10 E0.48 -46.6 -7.7 -- -- 7.1 -19.2 <1.9 2.5 -- -- 0.093 0.12WY101 <0.04 0.088 0.65 <0.6 -49.0 -7.9 -- -- 8.1 -18.7 0.37 1.9 860 32 0.072 <1WY102 <0.04 0.066 1.3 <0.6 -46.6 -7.7 -- -- 7.1 -20.3 <2 <2 2,400 47 0.062 <0.51WY102 -- -- -- -- -- -- 4.4 9.6 -- -- -- -- -- -- -- --WY102 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY106 <0.04 0.15 0.74 1.5 -57.0 -8.9 -- -- 13.6 -13.6 <3 1.0 5,500 71 0.051 <0.56WY111,2 <.04 1.4 0.7 54 -- -- -- -- -- -- -- -- 580 26 -- --WY661,2 <.04 0.38 <0.1 21.4 -- -- -- -- -- -- -- -- NA NA -- --
58 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06 Table 8. Dissolved concentrations of trace elements, stable isotope ratios, and radionuclides in groundwater samples from wells in the Woodbury, Connecticut (2002–06), study area, and from selected wells elsewhere in the Pomperaug and Hartford Basins.—Continued [Concentrations in micrograms per liter, unless otherwise noted; Al, aluminum; Sb, antimony; As, arsenic; Ba, barium; Be, beryllium; B, boron; Cd, cadmium; Cr, chromium; Co, cobalt; Cu, copper; Fe, iron; Pb, lead; Li, lithium; Mn, manganese; Mo, molybdenum; Ni, nickel; N, nitrogen; Se, selenium; Ag, silver; Sr, strontium; Tl, thallium; U, uranium; V, vanadium; Zn, zinc; H-1, protium; H-2, deuterium; O, oxygen; C, carbon; DIC, dissolved inorganic carbon; per mil, parts per thousand; scu, sigma combined uncertainty; bedrock wells shaded gray; <, less than; E, estimated value below minimum reporting level; --, no data; pCi/L, picocuries per liter] Well ID Date Al Sb As As (III) (arsenite) As (V) (arsenate) Ba Be B Cd Cr Co Cu Fe Pb Li Mn Mo Ni Se Ag Sr WY671,2 4/17/03 <2 <0.05 <0.3 -- -- 20 <0.06 23 <0.04 <0.8 0.056 1.9 <10 0.09 4.2 0.3 0.5 0.92 <0.3 <1 60 WY681,2 4/16/03 <2 <0.05 <0.3 -- -- 24 <0.06 12 <0.04 <0.8 0.031 7.6 <10 0.76 E0.5 0.4 0.3 0.45 <0.3 <1 62 SB1121,2 10/28/02 <2 <0.3 <0.3 -- -- 20 <0.06 27 <0.04 <0.8 11 0.5 <10 0.38 7.1 130 <0.3 18.5 <0.5 0.4 96 SB1181,2 10/22/02 <2 <0.3 0.3 -- -- 58 <0.06 41 <0.04 <0.8 0.16 1 58 1.7 4 44 <0.3 1.1 <0.5 <0.2 260 SB1191,2 11/5/02 <2 <0.3 <0.3 -- -- 3 <0.06 11 <0.04 <0.8 0.019 12 <10 2.8 E0.3 0.8 0.4 0.76 <0.5 <0.2 23 SB1211,2 11/20/02 <2 <0.3 0.3 -- -- 25 <0.06 23 <0.04 <0.8 0.075 3.8 19 0.37 2.9 1 0.2 1.6 <0.5 <0.2 69 WY651,3 6/6/02 <1 E0.04 <0.2 -- -- 13 <0.06 16 E0.02 <0.8 0.03 1.9 29 0.13 2.2 0.7 <0.2 0.13 E0.3 <1 76 WY651,3 12/13/04 -- -- -- -- -- -- -- -- -- -- -- -- 45 -- -- 2.3 -- -- -- -- -- WY651,3 4/11/05 -- -- -- -- -- -- -- -- -- -- -- -- 61 -- -- 2.8 -- -- -- -- -- WY651,3 6/21/05 10 <0.2 <0.2 -- -- 15 <0.06 17 E.04 <.8 .051 5.1 79 .65 2.2 4.4 <.4 1.15 E.3 <.2 87 WY651,3 11/9/05 -- -- -- -- -- -- -- -- -- -- -- -- 65 -- -- 5.8 -- -- -- -- -- SB1201,3 11/15/02 <2 <0.3 E0.1 -- -- 55 <0.06 49 0.07 <0.8 1.3 43 41 0.68 5.7 0.8 <0.3 3.2 <1.5 <0.2 93 F3441,4 05/30/02 <1 <0.05 1.9 -- -- 28 <0.06 521 .04 <0.8 0.22 1.5 120 <0.08 4.4 200 4.4 <0.06 <0.3 <1 1,900 S4011,4 05/23/02 <1 <0.3 0.9 -- -- 53 <0.06 58 .04 E0.6 0.15 2.7 <10 1.5 4.6 0.5 E0.2 0.72 <0.3 <1 390 SO1101,5 09/03/92 -- -- -- -- -- -- -- -- -- -- -- -- 21 -- -- 17 -- -- -- -- -- NBR1181,5 08/27/93 -- -- -- -- -- -- -- -- -- -- -- -- 8 -- -- 42 -- -- -- -- -- BA1041,5 8/5/93 -- -- -- -- -- -- -- -- -- -- -- -- 8 -- -- 37 -- -- -- -- -- P1171,5 07/29/94 -- -- -- -- -- -- -- -- -- -- -- -- 6 -- -- 5 -- -- -- -- -- B4031,5 08/19/93 -- -- -- -- -- -- -- -- -- -- -- -- 46 -- -- 2,300 -- -- -- -- --
Aquifer Chemistry 59

Table 8. Dissolved concentrations of trace elements, stable isotope ratios, and radionuclides in groundwater samples from wells in the Woodbury, Connecticut (2002–06), study area, and from selected wells elsewhere in the Pomperaug and Hartford Basins.—Continued[Concentrations in micrograms per liter, unless otherwise noted; Al, aluminum; Sb, antimony; As, arsenic; Ba, barium; Be, beryllium; B, boron; Cd, cadmium; Cr, chromium; Co, cobalt; Cu, copper; Fe, iron; Pb, lead; Li, lithium; Mn, manganese; Mo, molybdenum; Ni, nickel; N, nitrogen; Se, selenium; Ag, silver; Sr, strontium; Tl, thallium; U, uranium; V, vanadium; Zn, zinc; H-1, protium; H-2, deuterium; O, oxygen; C, carbon; DIC, dissolved inorganic carbon; per mil, parts per thousand; scu, sigma combined uncertainty; bedrock wells shaded gray; <, less than; E, estimated value below minimum reporting level; --, no data; pCi/L, picocuries per liter]

Well 

ID Tl U V Zn 

Delta 

H-2/ H-1 

ratio 

(per mil)

Delta 

O-18/ O-16 

ratio 

(per mil)

Delta 

O-18/O-16 

ratio in 

NO3−

(per mil)

Delta 

N-15/N-14 

ratio in 

NO3−

(per mil)

Delta 

S-34/S-32 

ratio in 

SO42− (per 

mil)

Delta 

C-13/C-12 

ratio in 

DIC 

(per mil)

Alpha 

activity, as 

Thorium-230 

(pCi per L)

Gross 

beta, 

as Cs-137 

(pCi per L)

Radon-222 

(pCi per L)

Radon-222 

2scu (pCi/L)

Radium-226 

(pCi per L)

Radium-228 

(pCi per L)

WY671,2 <.04 0.17 1.1 E1 -- -- -- -- -- -- -- -- 1,210 33 -- --WY681,2 <.04 0.07 0.1 1.3 -- -- -- -- -- -- -- -- 1,290 36 -- --SB1121,2 E0.02 0.03 0.8 120 -- -- -- -- -- -- -- -- -- -- -- --SB1181,2 0.04 0.32 1.2 6.5 -- -- -- -- -- -- -- -- 760 29 -- --SB1191,2 0.04 E0.01 E0.1 4.8 -- -- -- -- -- -- -- -- -- -- -- --SB1211,2 E0.02 0.37 0.3 1.6 -- -- -- -- -- -- -- -- -- -- -- --WY651,3 <0.04 0.22 0.4 104 -45.5 -7.6 -- -- -- -- <0.91 1.9 2,200 44 0.06 <0.56WY651,3 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY651,3 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --WY651,3 <.04 -- <.1 129 -- -- -- -- -- -- -- -- -- -- -- --WY651,3 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --SB1201,3 E0.04 0.09 1.4 11 -42.4 -7.1 -- -- -- -- 1.03 3.6 280 22 0.17 0.84F3441,4 <.04 1.6 1.5 2 -52.0 -8.5 -- -- -- -- 4.8 5 900 31 0.24 <0.62S4011,4 <.04 0.4 9.7 1 -- -- -- -- -- -- <3 1.1 -- -- 0.035 0.44SO1101,5 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --NBR1181,5 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --BA1041,5 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --P1171,5 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --B4031,5 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06 Table 8. Dissolved concentrations of trace elements, stable isotope ratios, and radionuclides in groundwater samples from wells in the Woodbury, Connecticut (2002–06), study area, and from selected wells elsewhere in the Pomperaug and Hartford Basins.—Continued [Concentrations in micrograms per liter, unless otherwise noted; Al, aluminum; Sb, antimony; As, arsenic; Ba, barium; Be, beryllium; B, boron; Cd, cadmium; Cr, chromium; Co, cobalt; Cu, copper; Fe, iron; Pb, lead; Li, lithium; Mn, manganese; Mo, molybdenum; Ni, nickel; N, nitrogen; Se, selenium; Ag, silver; Sr, strontium; Tl, thallium; U, uranium; V, vanadium; Zn, zinc; H-1, protium; H-2, deuterium; O, oxygen; C, carbon; DIC, dissolved inorganic carbon; per mil, parts per thousand; scu, sigma combined uncertainty; bedrock wells shaded gray; <, less than; E, estimated value below minimum reporting level; --, no data; pCi/L, picocuries per liter] Well ID Date Al Sb As As (III) (arsenite) As (V) (arsenate) Ba Be B Cd Cr Co Cu Fe Pb Li Mn Mo Ni Se Ag Sr Pomperaug River above South Brook 12/30/03 0855 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Pomperaug River above South Brook 12/27/04 1200 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- South Brook at South Pomperaug Ave at Pomperaug 1/11/05 1320 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- South Brook at South Pomperaug Ave at Pomperaug 12/27/04 1730 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- South Brook at Middle Quarter Rd at Pomperaug 1/11/05 1230 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
Aquifer Chemistry 61

Table 8. Dissolved concentrations of trace elements, stable isotope ratios, and radionuclides in groundwater samples from wells in the Woodbury, Connecticut (2002–06), study area, and from selected wells elsewhere in the Pomperaug and Hartford Basins.—Continued[Concentrations in micrograms per liter, unless otherwise noted; Al, aluminum; Sb, antimony; As, arsenic; Ba, barium; Be, beryllium; B, boron; Cd, cadmium; Cr, chromium; Co, cobalt; Cu, copper; Fe, iron; Pb, lead; Li, lithium; Mn, manganese; Mo, molybdenum; Ni, nickel; N, nitrogen; Se, selenium; Ag, silver; Sr, strontium; Tl, thallium; U, uranium; V, vanadium; Zn, zinc; H-1, protium; H-2, deuterium; O, oxygen; C, carbon; DIC, dissolved inorganic carbon; per mil, parts per thousand; scu, sigma combined uncertainty; bedrock wells shaded gray; <, less than; E, estimated value below minimum reporting level; --, no data; pCi/L, picocuries per liter]

Well 

ID Tl U V Zn 

Delta 

H-2/ H-1 

ratio 

(per mil)

Delta 

O-18/ O-16 

ratio 

(per mil)

Delta 

O-18/O-16 

ratio in 

NO3−

(per mil)

Delta 

N-15/N-14 

ratio in 

NO3−

(per mil)

Delta 

S-34/S-32 

ratio in 

SO42− (per 

mil)

Delta 

C-13/C-12 

ratio in 

DIC 

(per mil)

Alpha 

activity, as 

Thorium-230 

(pCi per L)

Gross 

beta, 

as Cs-137 

(pCi per L)

Radon-222 

(pCi per L)

Radon-222 

2scu (pCi/L)

Radium-226 

(pCi per L)

Radium-228 

(pCi per L)

Pomperaug 

River above South Brook

-- -- -- -- -45.0 -7.5 -- -- -- -- -- -- -- -- -- --

Pomperaug 

River above South Brook

-- -- -- -- -47.0 -7.7 -- -- -- -- -- -- -- -- -- --

South Brook 

at South Pomperaug Ave at Pomperaug

-- -- -- -- -47.7 -7.7 -- -- -- -- -- -- -- -- -- --

South Brook 

at South Pomperaug Ave at Pomperaug

-- -- -- -- -43.3 -7.3 -- -- -- -- -- -- -- -- -- --

South Brook 

at Middle Quarter Rd at Pomperaug

-- -- -- -- -47.3 -7.7 -- -- -- -- -- -- -- -- -- --

1Not sampled as part of this study.2Glacial, community-supply well for regional-scale TANC study, Pomperaug Basin.3Glacial, domestic-supply well (major aquifer study) in Pomperaug Basin.4Glacial, domestic-supply well (major aquifer study) in Hartford Basin.5Glacial well in forested, undeveloped land use, Hartford Basin.
62 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

A

B

6

5

7

8

9

10

23 18 3 1

pH

10

20

30

40

50

100

200

300

400

22 18 3 1

BEDROCK, SHALLOW

(LESS THAN 30 METERS 

BELOW BEDROCK SURFACE)

GLACIAL AQUIFER, DEEP

(LESS THAN 3 METERS

ABOVE BEDROCK)

GLACIAL AQUIFER, SHALLOW

(MORE THAN 3 METERS 

ABOVE BEDROCK )

BEDROCK, DEEP

(MORE THAN 30 METERS 

BELOW BEDROCK SURFACE)

BICARBONATE CONCENTRATION, 

IN MILLIGRAMS PER LITER

23 Number of values

EXPLANATION 

75th percentile

Median

25th percentile

Data value less than or equal to

1.5 times the interquartile range

outside the quartile

Data value less than or equal to

1.5 times the interquartile range

outside the quartile

Outlier data more than 1.5 times

the interquartile range

Outlier data more than

1.5 times the 

interquartile range

} Interquartile

range

Figure 12. Distribution of (A) pH, and (B) bicarbonate concentrations in groundwater samples from well screens in the (1) shallow 

parts of the glacial aquifer, greater than 3 meters above bedrock, (2) deep glacial aquifer, less than 3 meters above bedrock, 

(3) shallow bedrock, less than 30 meters below bedrock surface, and (4) deep bedrock, greater than 30 meters below bedrock 

surface in the study area, Woodbury, Connecticut.
Aquifer Chemistry 63

1979

Upland

bedrock

Deep Mesozoic

basin influence

Mesozoic

shale

1979

1979

EXPLANATION

Glacial aquifer, shallow, and identifier

Glacial aquifer, deep, and identifier

Glacial aquifer, deep (Hartford Basin), and identifier

Bedrock, shallow, and identifier

Bedrock, deep, and identifier

PSW-1 (1979 refers to date of sample taken prior to this study)

Glacial aquifer, shallow (Hartford Basin), and identifier

Glacial aquifer, domestic well (Pomperaug Basin), and identifier

Percent

Ca

100

80

60

20

0

0

20

40

60

80

100

Mg

0

20

40

60

80

100

Na + K

Cl

0

20

40

60

80

100

100

80

60

40

20

CO3

 + HCO3

100

80

60

20

0

SO4

0

SO4

 + Cl

0

20

40

60

80

100

Ca + Mg

100

80

60

40

20

0

100

80

20

Percent

Percent

Deep glacial 

aquifer

87

106

87

86

87

86

106

106

97

97

97

40

20

40

60

80

100

60

40

85

81

82

78

78

78

NBR118

0

40

0

F344

F344

S401

S401

WY65

B403

106

86

82

83

S401

S401

B403

B403

B403

F344

NBR118 NBR118

83

83

83

Figure 13. Piper diagram showing the percentage of total equivalents of major cations and anions in groundwater samples from 

wells in the Woodbury study area, and from selected wells elsewhere in the Pomperaug and Hartford Basins, Connecticut. 
64 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

SULFATE CONCENTRATION, IN MILLIMOLES PER LITER

CALCIUM CONCENTRATION,

IN MILLIMOLES PER LITER

Gypsum

dissolution

0 1 2 3 0

1

2

3

35

10 15 20 25 30 35 40

0

50

100

150

200

300

250

BICARBONATE, CONCENTRTAION,

 IN MILLIGRAMS PER LITER

Glacial till

Glacial

deposits

likely derived

from Cass

Formation

Shallow 

bedrock wells

Glacial aquifer, 

deep

SILICA CONCENTRATION, IN MILLIGRAMS PER LITER

A B

83

85

85

90

90

89 96

106

F344

96

EXPLANATION

Glacial aquifer, shallow

Glacial aquifer, deep

Glacial aquifer, deep (Hartford Basin)

Bedrock, shallow

Bedrock, deep

PSW-1

Glacial aquifer, shallow (Hartford Basin)

Glacial aquifer, shallow

(Pomperaug Basin, out of study area)

Figure 14. Concentrations of (A) silica as a function of bicarbonate and (B) calcium as a function of sulfate in groundwater 

samples from wells in the Woodbury study area, and from selected wells elsewhere in the Pomperaug and Hartford Basins, 

Connecticut.

restricted to cements in some lacustrine deposits (Hubert and 

others, 1992; Krynine, 1950). Furthermore, concentrations of 

Mg in the representative deep bedrock well (WY106) were 

very low and do not support dissolution of dolomite after the 

dissolution of gypsum and precipitation of calcite.

Other wells screened in glacial deposits appear to be 

affected by underlying Mesozoic shales. Data representing the 

major-ion distributions of samples from WY83, as depicted in 

figure 13, plotted near the ion distributions for bedrock wells 

and also near those for wells S403, S401, and NBR118 that tap 

groundwater from glacial deposits that overlie Mesozoic rocks 

in the Hartford Basin. Major-ion ratios in samples from these 

wells appear to reflect interaction with the Cass Formation 

and the Shuttle Meadow Formation, respectively, and do not 

appear to be affected by basinal fluids or older (> 50 years), 

deep groundwater with higher ionic strength. The low 

concentration of SO4

2− in samples from WY83, for example, 

likely reflects SO4

2− reduction. Ca correlates well with Mg for 

most samples (fig. 15A) and likely is related to the distribution 

of calcite or other carbonate minerals in bedrock and glacial 

till deposits and to various anthropogenic activities and 

sources, including liming of lawns, road salting, and septicsystem leachate, and associated cation exchange. Cations 

such as Na and Ca, and anions such as Cl− are associated with 

road salting (Panno and others, 2006). Road-salt runoff is 

indicated by the high concentrations of Na+ and Cl−; Na+ and 

Cl− concentrations in some samples plot along a 1:1 line (for 

example, halite in road salt), but some samples show relatively 

high concentrations of Cl− (fig. 15B), which may indicate 

other sources and preferential sorption of Na+ over Cl−. 

Water samples from well WY85, which is near a septic-tank 

drainfield, have particularly high concentrations of Cl− and 

appear to be affected by septic-system leachate, as discussed 

later in this section.

Plots of the relation between Cl− concentrations and Cl:Br 

mass-concentration ratios were used to help determine the 
Aquifer Chemistry 65

Table 9. Traveltime in years and percentage of particles in each land-use type for flow-tracking particles backtracked from monitoring-well screens to the water table, simulated with MODPATH (Starn and Brown, 2007).—Continued[CRA, contibuting recharge area; ID, identifier; ag, agricultural; bedrock wells shaded gray; --, no particles generated because the model was dry at the screen interval]

Well ID

Age 

tracers 

measured

Number 

of 

particles

Travel time, in years CRA 

land 

use

Particles in general land use Percentage of particles in general land use Average travel time in each general land use, in years

Minimum Average Maximum Urban Ag Forested/ wetland Urban Ag Forested/ wetland Urban Ag Forested/ wetland Total average 

age

WY 69 1 10 5.6 6.3 8.3 Mixed 9 0 1 0.9 0 0.1 5.6 0 0.63 6.3WY 70 1 10 1.3 1.4 1.5 Urban 10 0 0 1 0 0 1.4 0 0 1.4WY 71 1 10 -- -- -- -- -- -- -- -- -- -- -- -- -- --WY72 1 10 7.4 8.5 8.9 Mixed 2 0 8 0.2 0 0.8 1.7 0 6.8 8.5WY73 1 10 2.6 2.8 2.9 Urban 10 0 0 1 0 0 2.8 0 0 2.8WY74 1 10 -- -- -- -- -- -- -- -- -- -- -- -- -- --WY75 1 10 5.9 6.2 6.6 Urban 10 0 0 1 0 0 6.2 0 0 6.2WY76 1 10 -- -- -- -- -- -- -- -- -- -- -- -- -- --WY77 0 10 0.6 0.7 0.8 Urban 10 0 0 1 0 0 0.70 0 0 0.7WY78 0 10 -- -- -- -- -- -- -- -- -- -- -- -- -- --WY79 0 10 1.2 1.3 1.5 Urban 10 0 0 1 0 0 1.3 0 0 1.3WY80 0 10 0.5 0.5 0.5 Mixed 1 0 9 0.1 0 0.9 0.05 0 0.46 0.5WY81 0 10 0.3 0.4 0.4 Urban 10 0 0 1 0 0 0.37 0 0 0.4WY82 0 10 2.3 4.3 6.7 Mixed 6 3 1 0.6 0.30 0.1 2.6 1.3 0.43 4.3WY83 0 10 0.2 0.4 0.5 Urban 10 0 0 1 0 0 0.37 0 0 0.4WY84 1 10 3.3 4.6 6.2 Mixed 9 0 1 0.9 0 0.1 4.1 0 0.46 4.6WY85 1 10 0.8 0.8 0.8 Urban 10 0 0 1 0 0 0.82 0 0 0.8WY86 1 10 3.1 3.2 3.3 Urban 10 0 0 1 0 0 3.2 0 0 3.2WY87 1 10 2.6 2.6 2.6 For/wet 0 0 10 0 1 0 0 2.6 2.6WY88 0 4 0.1 0.3 0.5 For/wet 0 0 4 0 0 1 0 0 0.32 0.3WY89 0 10 0.6 0.7 0.8 For/wet 0 0 10 0 0 1 0 0 0.72 0.7WY90 0 10 0.3 0.4 0.4 For/wet 0 0 10 0 0 1 0 0 0.39 0.4WY91 0 10 7.7 8.4 9.1 Mixed 8 0 2 0.8 0 0.2 6.7 0 1.7 8.4WY92 0 10 1.6 2.0 2.4 Urban 10 0 0 1 0 0 2.0 0 0 2.0WY93 0 10 5.5 5.5 5.6 For/wet 0 0 10 0 0 1 0 0 5.5 5.5WY94 0 10 0.3 1.2 2.5 For/wet 0 0 10 0 0 1 0 0 1.2 1.2WY95 0 10 0.5 0.5 0.6 Urban 10 0 0 1 0 0 0.54 0 0 0.5
66 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06 Table 9. Traveltime in years and percentage of particles in each land-use type for flow-tracking particles backtracked from monitoring-well screens to the water table, simulated with MODPATH (Starn and Brown, 2007).—Continued [CRA, contibuting recharge area; ID, identifier; ag, agricultural; bedrock wells shaded gray; --, no particles generated because the model was dry at the screen interval] Well ID Age tracers measured Number of particles Travel time, in years CRA land use Particles in general land use Percentage of particles in general land use Average travel time in each general land use, in years Minimum Average Maximum Urban Ag Forested/ wetland Urban Ag Forested/ wetland Urban Ag Forested/ wetland Total average age WY96 0 10 -- -- -- -- -- -- -- -- -- -- -- -- -- -- WY97 1 10 2.8 3.0 3.3 Urban 10 0 0 1 0 0 3.0 0 0 3.0 WY98 0 10 0.3 0.4 0.4 Mixed 8 0 2 0.8 0 0.2 0.28 0 0.07 0.4 WY99 0 10 0.0 0.1 0.1 Urban 10 0 0 1 0 0 0.07 0 0 0.07 WY100 1 10 10 10.4 10.7 Urban 10 0 0 1 0 10 0 0 10 WY101 1 10 6.7 7.5 9.4 Mixed 8 0 2 0.8 0 0.2 6.0 0 1.5 7.5 WY102 1 10 0.4 0.6 0.9 Mixed 0 3 7 0 0.30 0.7 0 0.19 0.45 0.6 WY103 0 10 0.8 6.0 11.5 Mixed 8 1 1 0.8 0.10 0.1 4.8 0.60 0.60 6.0 WY104 0 10 0.4 3.3 6.2 Mixed 8 0 2 0.8 0 0.2 2.6 0 0.66 3.3 WY105 0 10 1.0 4.5 6.8 Mixed 8 0 2 0.8 0 0.2 3.6 0 0.90 4.5 WY106 1 10 5.9 5.9 5.9 For/wet 0 0 10 0 0 1 0 0 5.9 5.9

1The water table simulated in the model was above the well screen, so particles could not be back tracked.
Aquifer Chemistry 67

spline curve

98

0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

0

1

2

3

0 2 4 6 8 10 12

CHLORIDE CONCENTRATION, IN MILLIMOLES PER LITER

MAGNESIUM CONCENTRATION, IN MILLIMOLES PER LITER

0

1

2

3

4

1:1

y = 2.303 + 0.065

r2

 = 0.8285

78

85

71

102

95

96

89

106

A

B

CALCIUM CONCENTRATION,

IN MILLIMOLES PER LITER

SODIUM CONCENTRATION,

IN MILLIMOLES PER LITER

EXPLANATION

Glacial aquifer, shallow, and identifier

Glacial aquifer, deep

Glacial aquifer, deep (Hartford Basin)

Bedrock, shallow

Bedrock, deep

Glacial aquifer, shallow (Hartford Basin)

PSW-1

85

90

89

96

78

71

74

Glacial aquifer, domestic well

 (Pomperaug Basin)

90

106

Figure 15. Concentrations of (A) magnesium as a function of calcium, and (B) chloride as a function of sodium, in 

groundwater samples from wells in the Woodbury study area, and from selected wells elsewhere in the Pomperaug and 

Hartford Basins, Connecticut.
68 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

effects of anthropogenic sources or activities on groundwater 

chemistry (table 7, fig. 16). Concentrations of Cl− and Br−

are useful in distinguishing several sources because of their 

conservative nature in water, because they have different 

abundances in natural fluids and most solids (Davis and others, 

1998), and because natural halite deposits are nonexistent in 

the Pomperaug aquifer system. Plots of Cl− concentrations 

and Cl:Br ratios have been used to determine the effects of 

road salt, sewage, and seawater or brines on groundwater 

quality (Davis and others, 1998; Vengosh and Pankratov, 

1998; Thomas, 2000; Panno and others, 2006). Although 

both Cl− and Br− have similar sources and behave similarly 

geochemically (Fuge, 1969), Cl− is generally 40 to 8,000 times 

as abundant as Br−, and Cl− has a slightly lower solubility than 

does Br− (Davis and others, 1998). Atmospheric deposition 

is the primary source of Cl− and Br− in pristine groundwater 

in the study area. Cl:Br ratios in precipitation typically range 

from 50 to 100; near the coast, ratios generally are about 290, 

similar to seawater, and decrease with distance from the ocean 

to a low of 20 to 56 in the midwestern United States (Panno 

and others, 2006). Seawater has an average Cl− concentration 

of about 19,500 mg/L and an average Br− concentration of 

about 290 (Davis and others, 1998). Cl− and Br− concentrations 

and their ratios for several sources relevant to the Woodbury 

study area, including previously published values, and those 

for well samples in other areas are shown in table 10. A graph 

of Cl− concentrations and Cl:Br mass ratios shows the values 

for well samples relative to previously published source 

values or ranges for road salt (halite), domestic septic-system 

leachate (sewage), and seawater (fig. 16). Mixing lines were 

calculated between assumed end points for dilute groundwater 

and road salt (halite), domestic septic-system leachate 

(sewage), and seawater.

Cl− concentrations and Cl:Br ratios in the Pomperaug 

glacial aquifer were affected to some extent by three endmember sources—dilute groundwater, road salt (halite), and 

sewage (septic-system leachate) (fig. 16). Seawater does not 

appear to be a direct source of Cl− or Br−, given the distance 

from the well to the coast, but it is shown as an additional 

endpoint in figure 16 for illustrative purposes. The dilute 

groundwater end point is represented by a monitoring well 

(well SO110), which is completed in glacial stratified deposits 

overlying Mesozoic rocks in a forested, undeveloped area in 

north-central Connecticut. Groundwater samples from other 

wells in undeveloped parts of Connecticut (P117) and of the 

study area (for example, WY86 and WY106) generally had 

Cl− concentrations less than 10 mg/L and Cl:Br ratios less 

than 400, which is the ratio that Thomas (2000) considered to 

be the threshold for anthropogenic sources in the midwestern 

United States. Cl− and Br− concentrations in shallow 

groundwater should be similar to those in local atmospheric 

deposition but slightly more concentrated as a result of 

evapotranspiration and some interaction with shallow glacial 

or alluvial deposits. Because Cl− and Br− concentrations in 

atmospheric deposition are small, small amounts of Cl− and 

Br− from other sources will generally dominate the Cl:Br ratio. 

The medians for Cl− concentrations (10,000 mg/L) and 

Cl:Br ratios (6,770) that were representative of halite road 

salt in Massachusetts (Granato, 1996) were used for the end 

point of halite. Halite is applied to roads for the treatment 

of snow and ice in the study area during the winter season 

and is the major source of Cl−. Groundwater samples that 

appeared to be affected by road-salt applications and by 

septic-tank drainfields had the largest deviation from dilute 

groundwater in the Cl:Br plots. Similarly, in a glacial aquifer 

in the Detroit, Michigan, metropolitan area, Thomas (2000) 

found that anthropogenic contaminants were closely related to 

elevated Cl:Br ratios and surmised that the greatest effect on 

groundwater quality was from septic-system leachate and from 

road-salt runoff. Cl− concentrations and Cl:Br ratios for most 

samples in the study area fall along the mixing curve between 

typical values for dilute groundwater and road salt (fig. 16). 

The Br− ion in halite is depleted relative to Cl− by a factor of 

20 to 30 because the Br− ion is larger (Schoonen and others, 

1995). The influx of Na from halite road salt acts to increase 

exchangeable cations and results in increased concentrations 

of Ca, Mg, and K in groundwater samples, particularly during 

the winter months (table 7). The town of Woodbury applied 

about 730 to 820 metric tons of halite per year to about 

145 km of town roadways, which translates to about 5 to 

6 metric tons per km of town roadway, during the 2004–2005 

and 2005–2006 winter seasons. Road salt is probably applied 

to state roads at similar rates, although these roads can be 

wider, and the application rates may be higher.

Domestic and community sewage for the entire 

Woodbury, Connecticut, population is disposed of through 

on-site septic-tank drainfields, which can affect concentrations 

of Cl− and Br−, as well as NO3

−

 and NH4

+

, PO4

3-, B, and DOC 

(tables 7, 8, and 10). A median Cl− concentration of 91 mg/L 

and a Cl:Br ratio of 769, as determined for effluent from 

29 private septic systems in the midwestern United States 

by Panno and others (2006), were used to represent the end 

point for septic-system leachate (fig. 16) because of the large 

number of septic-system samples from which it was derived. 

This end point is lower than the median Cl:Br ratio of 1,197 

and higher than the median Cl− concentration of 72 mg/L 

that were calculated for groundwater samples collected from 

wells downgradient from septic-tank drainfields in this study 

area; the median values were derived from samples from 

WY85, WY89, WY90, and WY95 (table 10). All these sites, 

particularly WY85 and WY95, are near roads or parking 

lots and probably are affected by halite road-salt runoff as 

well; the Cl− concentration of 400 mg/L in groundwater from 

WY85 exceeded the National Secondary Drinking Water 

Regulations of 250 mg/L (USEPA, 2006b). Septic-system 

leachate also can be affected by water-softener salt, which 

is generally NaCl (Panno and others, 2006), although water 

from glacial stratified deposits typically is soft (a sample of 

untreated water at PSW-1 had a total hardness of about 5 mg/L 

as CaCO3) and, therefore, is not likely to require softening. 

Domestic well SB120, which is 7 km to the south of the study 

area, also is downgradient from a previously failed septic-tank 
Aquifer Chemistry 69

86

P117

SB120

87

87

77 70

84

95

81

71

74

75

74

72

73

83

102

101

76

79

82

92

92

89

100

69

99 91

94

SO110

SO110

98

98

88

78

Anthropogenic

effects

Sewage

(Peavy, 1978)

Sewage

(Davis and others, 1998)

Sewage

Jagucki and Darner (2001)

Septic-system leachate

(Panno and others, 2006)

Pomperaug septic-system

leachate (median value for wells

near septic-tank drainfields)

Septic-system leachate

and road-salt effects

Dilute

groundwater

CHLORIDE/BROMIDE MASS CONCENTRATION RATIO

CHLORIDE CONCENTRATION, IN MILLIGRAMS PER LITER

Halite

Seawater

Sewage

EXPLANATION

Glacial aquifer, shallow, and identifier

Glacial aquifer, deep

Bedrock, shallow

Bedrock, deep

PSW-1

Glacial aquifer, shallow (Hartford Basin)

Mixing lines and end points

Glacial aquifer, domestic well (Pomperaug Basin)

Glacial aquifer, production well (Pomperaug Basin)

85

85

96

90

40

100

1,000

10,000

1 10 100 1,000 10,000

106

106

35

80 93

Figure 16. Concentrations of chloride as a function of chloride:bromide mass concentration ratios in 

samples collected in the Woodbury study area, Connecticut, and in other studies, together with mixing lines 

between designated end points, dilute groundwater, halite, sewage, and seawater.
70 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

Table 10. Summary of chloride:bromide mass ratios and concentrations of selected constituents related to road salt (halite) and 

septic-system leachate in samples from previous studies, and groundwater samples from selected wells in the Woodbury 

study area and elsewhere in the Pomperaug Basin, Connecticut. —Continued

[Concentrations in milligrams per liter; Na+, sodium; Ca2

+

, calcium; SO4

2−, sulfate; Cl−

, chloride; Br−, bromide; NO3

−

+NO2

−

, nitrate plus nitrite; NH4

+

, ammonia; 

PO4

3-, orthophosphate; B, boron; specific conductance in microsiemens per centimeter at 25 degrees Celsius; DOC, dissolved organic carbon; DO, dissolved oxygen; 

HCO3

-

, bicarbonate; --, indicates data not available; E, estimated value below minimum reporting level; NA, not applicable; ~, approximately; <, less than; samples 

within shaded area used to calculate median for wells with septic-system leachate influence.]

References Na+ Ca2

+ SO4

2− Cl− Br−

 Dilute groundwater

1

SO110; 10/6/05 -- -- -- 5 0.03

 Sewage

Davis and others, 1998 (assembled for U.S., England) -- -- -- NA NA

Vengosh and Pankrotov, 1998 (Israel) -- -- -- 260–396 0.4–0.9

Thomas, 2000; Jagucki and Darner, 2001 -- -- -- 69 NA

Panno and others, 2006 (midwestern U.S.) 45–2,720 -- -- 91 0.1183

Average of median values for wells affected by Pomperaug septic-system leachate, 

(WY85,89,90,95)

-- -- -- 113 0.060

Median values for wells affected by Pomperaug septic-system leachate 

(WY85,89,90,95)

-- -- -- 62.7 0.053

Endpoint value for wells affected by Pomperaug septic-system leachate -- -- -- 81.5 NA

Behl and others, 1987 -- -- -- NA NA

Peavy, 1978 -- -- -- 37–101 NA

 Road salt/halite

Granato, 1996; analysis of road salt -- -- -- 10,000 1.5

Granato, 1996; highway runoff -- -- -- 80,000 --

Granato, 1996; first flush winter storm -- -- -- 17,000 --

Davis and others, 1998 -- -- -- -- --

Schoonen and others, 1995; analysis of Suffolk County, New York, road salt -- -- -- ~10,000 ~1.76

 Seawater

Davis and others, 1998 -- -- -- 19,000–20,000 --

Hem, 1992 -- -- -- 19,000 65

Krauskopf, 1979 10,770 -- -- 18,800 67

 Atmospheric deposition

Davis and others, 1998; lower -- -- -- -- --

Davis and others, 1998; upper -- -- -- -- --

 Pomperaug Basin wells with probable effects of septic-system leachate

WY71; 12/22/2003 50 22 16 55 0.096

WY71; 7/27/2004 52 36 13 68 0.078

WY71; 1/7/2005 51 31 13 52 0.10

WY71; 5/18/2005 56 46 9.7 120 0.17

WY73; 2/17/2003 27 23 12 37 0.032

WY74; 11/6/2003 32 27 13 42 0.037

WY74; 7/28/2004 30 31 11 50 0.055
Aquifer Chemistry 71

Table 10. Summary of chloride:bromide mass ratios and concentrations of selected constituents related to road salt (halite) and 

septic-system leachate in samples from previous studies, and groundwater samples from selected wells in the Woodbury study area 

and elsewhere in the Pomperaug Basin, Connecticut.—Continued

[Concentrations in milligrams per liter; Na+, sodium; Ca2

+

, calcium; SO4

2−, sulfate; Cl−

, chloride; Br−, bromide; NO3

−

+NO2

−

, nitrate plus nitrite; NH4

+

, 

ammonia; PO4

3-, orthophosphate; B, boron; specific conductance in microsiemens per centimeter at 25 degrees Celsius; DOC, dissolved organic carbon; 

DO, dissolved oxygen; HCO3

-

, bicarbonate; --, indicates data not available; E, estimated value below minimum reporting level; NA, not applicable; 

~, approximately; <, less than;samples within shaded area used to calculate median for wells with septic-system leachate influence.]

Cl:Br 

mass 

ratio

NO3

−

+NO2

−

, 

as N

NH4

+

, 

as N PO4

3−, as P B Specific 

conductance DOC DO HCO3

−

Probable 

organic 

carbon 

source

 Dilute groundwater

167.0 -- -- -- -- -- -- -- -- --

Sewage

300–600 -- -- -- -- -- -- -- -- --

410–873 -- -- -- -- -- -- -- -- --

450 -- -- -- -- -- -- -- -- --

769 -- -- -- -- -- -- -- -- --

997 -- -- -- -- -- -- -- -- --

1,200 -- -- -- -- -- -- -- -- --

873 -- -- -- -- -- -- -- -- --

275–531 -- -- -- -- -- -- -- -- --

NA -- -- -- -- -- -- -- -- --

Road salt/halite

6,667 -- -- -- -- -- -- -- -- --

3,300 -- -- -- -- -- -- -- -- --

58,621 -- -- -- -- -- -- -- -- --

1,000–10,000 -- -- -- -- -- -- -- -- --

5,690 -- -- -- -- -- -- -- -- --

Seawater

288–292 -- -- -- -- -- -- -- -- --

292 -- -- -- -- -- -- -- -- --

281 -- -- -- -- -- -- -- -- --

Atmospheric deposition

50–120 (inland) -- -- -- -- -- -- -- -- --

130–180 (near coast) -- -- -- -- -- -- -- -- --

Pomperaug Basin wells with probable effects of septic-system leachate

866 1.1 <.04 E0.004 32 400 1.3 -- 160 Mesozoic rocks

521 0.9 <.04 0.017 -- 511 0.99 0.81 170 Partly septic

746 0.7 <.04 E0.005 -- 461 1.20 1.5 130 Partly septic

1,145 2.2 <.04 <0.006 -- 645 0.81 3.2 110 Partly septic

1,158 2.1 <.04 E0.005 100 297 0.61 4.2 79 Partly septic

1,145 1.9 <.04 0.007 120 344 0.67 5.8 110 Partly septic

921 1.6 <.04 0.026 -- 385 0.67 5.9 120 Partly septic
72 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

Table 10. Summary of chloride:bromide mass ratios and concentrations of selected constituents related to road salt (halite) and 

septic-system leachate in samples from previous studies, and groundwater samples from selected wells in the Woodbury 

study area and elsewhere in the Pomperaug Basin, Connecticut. —Continued

[Concentrations in milligrams per liter; Na+, sodium; Ca2

+

, calcium; SO4

2−, sulfate; Cl−

, chloride; Br−, bromide; NO3

−

+NO2

−

, nitrate plus nitrite; NH4

+

, ammonia; 

PO4

3-, orthophosphate; B, boron; specific conductance in microsiemens per centimeter at 25 degrees Celsius; DOC, dissolved organic carbon; DO, dissolved oxygen; 

HCO3

-

, bicarbonate; --, indicates data not available; E, estimated value below minimum reporting level; NA, not applicable; ~, approximately; <, less than; samples 

within shaded area used to calculate median for wells with septic-system leachate influence.]

References Na+ Ca2

+ SO4

2− Cl− Br−

WY74; 1/10/2005 30 33 11 47 0.059

WY74; 6/15/2005 25 30 11 37 --

WY76; 11/12/2003 22 20 11 32 0.034

WY76; 7/26/2004 21 23 13 34 0.042

WY76; 1/4/2005 25 18 14 33 0.051

WY76; 6/14/2005 18 17 10 29 0.076

SB1202; 11/15/2002 38 37 14 56 0.041

WY85; 11/19/2003 65 128 8.7 400 0.167

WY85; 8/10/2004 45 68 8.6 200 0.069

WY85; 2/1/2005 47 90 11 230 0.088

WY85; 6/16/2005 65 125 9.7 380 --

WY89; 11/2/2004 16 62 9.7 77 0.050

WY90; 11/9/2004 0.081 103 7.7 54 0.069

WY90; 5/26/2005 0.095 85 11 63 --

WY95; 8/2/2004 40 27 14 71 0.082

WY95; 2/1/2005 33 25 11 54 0.063

WY95; 6/16/2005 35 27 12 67 --

Pomperaug Basin Median -- -- -- 72 0.069

Range-high -- -- -- 377 0.55

Range-low -- -- -- 43 0.049

1

Glacial well in forested, undeveloped land, Hartford Basin.

2

Glacial, domestic well (major aquifer study) in Pomperaug Basin.
Aquifer Chemistry 73

Table 10. Summary of chloride:bromide mass ratios and concentrations of selected constituents related to road salt (halite) and 

septic-system leachate in samples from previous studies, and groundwater samples from selected wells in the Woodbury study area 

and elsewhere in the Pomperaug Basin, Connecticut.—Continued

[Concentrations in milligrams per liter; Na+, sodium; Ca2

+

, calcium; SO4

2−, sulfate; Cl−

, chloride; Br−, bromide; NO3

−

+NO2

−

, nitrate plus nitrite; NH4

+

, 

ammonia; PO4

3-, orthophosphate; B, boron; specific conductance in microsiemens per centimeter at 25 degrees Celsius; DOC, dissolved organic carbon; 

DO, dissolved oxygen; HCO3

-

, bicarbonate; --, indicates data not available; E, estimated value below minimum reporting level; NA, not applicable; 

~, approximately; <, less than;samples within shaded area used to calculate median for wells with septic-system leachate influence.]

Cl:Br 

mass 

ratio

NO3

−

+NO2

−

, 

as N

NH4

+

, 

as N PO4

3−, as P B Specific 

conductance DOC DO HCO3

−

Probable 

organic 

carbon 

source

794 1.1 <.04 0.009 -- 388 0.76 5.1 130 Partly septic

-- 1.7 <.04 0.007 -- 344 0.60 6.2 120 Partly septic

957 3.8 <.04 0.007 76 265 0.51 4.8 61 Partly septic

813 2.5 <.04 0.022 -- 274 0.57 2 61 Partly septic

644 3.4 <.04 0.008 -- 272 0.66 3.1 49 Partly septic

382 2.5 <.04 0.006 -- 240 0.46 4.2 59 Partly septic

1,366 11 <0.04 <.02 49 660 0.8 1.3 120 Septic

2,395 <.06 <.04 E0.003 34 1452 7.8 0.6 89 Septic

2,920 14 1.1 0.013 -- 906 89 0.66 65 Septic

2,614 12 2 <0.006 -- 1025 3.0 0.5 76 Septic

-- 19 4.2 <0.006 -- 1529 2.0 2.59 66 Septic

1,525 6.7 0.058 0.016 51 570 -- 8.0 140 Septic

776 17.4 0.05 0.012 -- 751 1.2 1.6 170 Septic

-- 9.4 0.25 E0.004 160 646 0.60 8.8 220 Septic

872 0.26 E0.028 0.018 -- 417 1.8 0.57 93 Partly septic

865 1.4 <0.04 E0.005 -- 349 1.1 0.14 83 Partly septic

-- 1.6 <0.04 0.008 -- 400 0.72 1.22 81 Partly septic

1,197 10 0.008 -- 634 1.1 2.9 112 --

1,525 -- -- -- -- -- -- -- -- --

363 -- -- -- -- -- -- -- -- --
74 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

drainfield for a retirement home; a groundwater sample had 

a Cl:Br ratio of 1,400 and Cl− concentration of 56 mg/L, 

similar to those in samples from the Woodbury study area. The 

Cl− concentrations and Cl:Br ratios for samples taken from 

these wells, in addition to samples from wells that are near 

septic-tank drainfields (WY71, WY74, WY76, and WY96), 

were used to define the areas on the graph likely affected by 

septic-system leachate (fig. 16). Values for several samples 

from other wells in the study area also plot within the area of 

the graph showing wells affected by septic-system leachate, 

including WY81, WY83, WY94, WY100, and PSW-1. 

The Cl:Br ratios associated with domestic sewage reported 

elsewhere were 275 to 531 (Behl and others, 1987) and 300 

to 600 (Davis and others, 1998) (table 10). Cl− concentrations 

in septic systems and adjacent soils in Montana ranged from 

37 mg/L to 101 mg/L (Peavy, 1978). Values for community 

supply wells in the Pomperaug River watershed, including 

PSW-1, generally plot along the dilute groundwater-halite line 

(fig. 16).

Concentrations of NO3

−

+NO2

−

 in groundwater can be 

derived from several sources, including microbial decay of 

organic matter in soils, animal waste, septic-system leachate, 

synthetic fertilizers, and rainfall. NO3

−

 +NO2

−

 concentrations 

ranged from less than the MRLs in water samples with 

reducing redox characteristics to 19 mg/L as N for a well 

that is immediately downgradient from a septic-tank 

drainfield (table 10). Concentrations of NO2

−

 were less than 

the MRL of 0.008 mg/L in all but two samples; therefore, 

NO3

−

+NO2

−

 will hereafter be referred to as simply “NO3

−

”. 

The median concentration of NO3

−

 for wells in the study 

area was 1.3 mg/L as N, but values varied considerably 

depending on the presence of anthropogenic N sources and 

redox conditions. Urban septic-system leachate and lawn 

fertilizer are the major sources of NO3

−

 in the study area and 

significantly affect shallow groundwater quality (figs. 17 and 

18). A graph of Cl:Br ratios and NO3

−

 concentrations shows 

that samples from wells adjacent to septic-tank drainfields 

and (or) the commercial area have high Cl:Br concentration 

ratios, and NO3

−

 concentrations generally are high but include 

concentrations less than the MRL (fig. 17).

The presence of DOC concentrations that are greater 

than background appears to result in reduction of NO3

−

 to 

N2 (denitrification), as well as reduction of other electron 

acceptors O2, Mn4+, Fe3+, and SO4

2−. The classification of wells 

based on water chemistry indicators and proximal natural 

or anthropogenic sources of DOC, which is described in a 

following section, “Redox Conditions and DOC,” is illustrated 

in figures 17 and 18 by varying colors of symbol outlines 

Denitrification

Anthropogenic effects

NITRATE +NITRITE CONCENTRATION, IN MILLIGRAMS PER LITER AS NITROGEN

EXPLANATION

Glacial aquifer, shallow, and identifier

Glacial aquifer, deep

Bedrock, shallow

Bedrock, deep

PSW-1

Glacial aquifer, shallow (Hartford Basin)

Glacial aquifer, deep (Hartford Basin)

CHLORIDE/BROMIDE, MASS CONCENTRATION RATIO

40

100

1,000

10,000

0.03 0.1 1 10 20

85

85

120

95

95

77

71

35

76

74 76 S401

71

96

73

74

79

88

82

76 70

100

102

101

91 79

106

94

84

89

90

83

83

87

80

B403

Glacial aquifer, production well

(Pomperaug Basin)

Glacial deposits, domestic well

(Pomperaug Basin)

Symbol outline color:

Low DOC, natural organic matter source

High DOC, natural organic matter source

High DOC, septic-system leachate source

Figure 17. Concentrations of nitrate plus nitrite as a function of chloride/bromide mass concentration ratios in groundwater 

samples in the Woodbury study area, and from selected wells elsewhere in the Pomperaug and Hartford Basins, Connecticut. 

Symbols are color coded for the estimated relative dissolved organic carbon (DOC) source and strength.
Aquifer Chemistry 75

WELL DEPTH, IN METERS BELOW LAND SURFACE

NITRATE PLUS NITRITE CONCENTRATION,

IN MILLIGRAMS PER LITER AS NITROGEN

A

B

81

CONCENTRATION OF DISSOLVED ORGANIC CARBON, 

IN MILLIGRAMS PER LITER

0.1

1

10

100

NITRATE PLUS NITRITE CONCENTRATION,

IN MILLIGRAMS PER LITER AS NITROGEN

0.03 0.1 1 10 20

Symbol outline color:

Low DOC, natural organic-matter source

High DOC, natural organic-matter source

High DOC, septic-system leachate source

35

53

65

70

71

71

72

73

74

75

69

76

77

78

78

78

79

79

80

81

82

83

84

85

85

86

88

90

91 92

93

94

95

95 96

98

99

100

101

102

SB120

86

EXPLANATION

Glacial aquifer, shallow, and identifier

Glacial aquifer, deep

Glacial aquifer, deep

(Hartford Basin)

Bedrock, shallow

Bedrock, deep

PSW-1

Glacial aquifer, shallow

 (Hartford Basin)

Glacial aquifer, production well

 (Pomperaug Basin)

Glacial aquifer, domestic well

 (Pomperaug Basin) 0 5 10 15 20

0

70

73

96

79

85

35

85

89

90

90

76

94

94

53

40

30

20

10

106

88

83

69

72

75

77

82

84

86

87

91

97

100

101

65

78

102

71

74

95 B403 95

S401

SB120

Figure 18. Concentration of nitrate plus nitrite as a function of (A) well depth, and (B) concentration of dissolved organic carbon, 

in groundwater samples from wells in the Woodbury study area, and from selected wells elsewhere in the Pomperaug and Hartford 

Basins, Connecticut. Symbols are color coded for the estimated relative dissolved organic carbon (DOC) source and strength.
76 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

for sample data points. For wells that are near septic-tank 

drainfields, concentrations of NO3

−

 (median 10 mg/L as N) 

and DOC (median of 1 mg/L) generally were higher than 

those of background wells and are defined herein as “High 

DOC, septic-system leachate source.” Samples from most 

wells had low concentrations of NO3

−

 and DOC; these wells 

are defined herein as “Low DOC, natural organic matter 

source.” Groundwater that appeared to be naturally reducing 

as a result of high DOC from riparian zones, buried wetland 

deposits, or sediments, likely derived from the organic-rich 

Cass Formation had lower NO3

−

 concentrations than the 

median, apparently because of denitrification; these wells are 

defined herein as “High DOC, natural organic matter source” 

(fig. 18B). 

NO3

−

 concentrations in the four wells downgradient 

from septic-tank drainfields ranged from less than the MRL 

to 19 mg/L as N, with a median concentration of 10 mg/L 

as N. Well WY85, which is downgradient from a drainfield, 

generally had high NO3

−

 concentrations (as much as 19 mg/L 

as N), although the NO3

−

 concentration was less than the MRL 

of 0.06 mg/L in the first sample collected, despite high DOC 

concentrations (figs. 17 and 18B); the high NO3

−

 concentration 

indicates the likely presence of a denitrifying zone near the 

screen. The DOC in septic-system leachate is attenuated, and 

NH4

+

 is oxidized to NO3

−

, in the unsaturated zone (Robertson 

and others, 1991; Harmon and others, 1996). The presence 

of high concentrations of DOC (2 mg/L on June 16, 2005, to 

89 mg/L on August 10, 2004), together with widely varying 

NO3

−

 concentrations, in samples from WY85 collected on 

November 19, 2003 and August 10, 2004 indicate that DOC, 

likely from septic-tank drainfields, was not oxidized before 

entering the water table and, therefore, apparently provided an 

electron donor for denitrification in the November 19, 2003 

sample. The unsaturated zone sediments below the septictank drainfield may have been overloaded with septic-system 

leachate from a system overload or failure, resulting in high 

concentrations of nitrate in subsequent samples.

Concentrations of NH4

+

 were less than the MRL at most 

sites, but were as high as 4.2 mg/L as N at wells affected 

by septic-system leachate; the concentrations also were 

measurable in parts of the aquifer that contain naturally 

occurring organic matter in sediment or riparian zones and that 

have reducing characteristics (table 7). PO4

3− concentrations 

were low, with a median of 0.006 mg/L, but those wells with 

septic-system leachate effects had a median of 0.008 mg/L as 

P (table 7).

Temporal Variations in Water Chemistry

Temperature, DOC concentrations, redox conditions, and 

concentrations of contaminants from road salt and septictank drainfields changed temporally in shallow groundwater. 

These changes reflect the seasonal variability in groundwater 

recharge and decomposition of leaves and other organic debris 

in riparian zones, as well as variability in anthropogenic 

sources, such as road salt and septic-system leachate. During 

the study period, median groundwater temperatures were 

about 12.3°C in shallow wells, 11.6°C in intermediate and 

deep wells, and 9.6°C in bedrock wells and upland till wells. 

Deep wells that were sampled periodically had temperature 

ranges of only a few degrees Celsius. 

Variations in groundwater temperature were greatest in 

shallow wells that have more rapid recharge, particularly near 

losing streams. For shallow wells that were sampled several 

times during different seasons, groundwater temperatures 

differed most near South Brook, including variations of 

8.4°C in WY80, 13.5°C in WY78, and 9.9°C in WY99 

(table 7). The water chemistry in samples from WY78 also 

varied seasonally; specific conductance ranged from 104 to 

764 mS/cm, probably resulting from road salt (halite) runoff 

during winter months, and redox conditions varied from 

oxic to SO4

2− reducing, probably resulting from the decay of 

natural organic matter in nearby stream sediments during the 

summer and fall and the subsequently high concentrations 

of DOC (1.1 to 5.7 mg/L) in water samples. Groundwater 

temperatures varied by about 7°C in WY35, adjacent to 

the Pomperaug River; stable-isotope ratios indicate that the 

effects on the water chemistry in samples from WY35 may be 

caused by leakage from the river and adjacent quarry ponds. 

Groundwater temperatures varied by 11°C at well WY81, 

which is situated on a slope, and the variation probably results 

from rapid recharge, as supported by the quick response of 

water levels to rainfall events. The large temporal variations 

in redox chemistry and concentrations of DOC and nitrate in 

groundwater samples from WY85 could have resulted from an 

exceedance of capacity of a nearby septic-tank drainfield, as 

discussed in the previous section.

Long-term variation in water chemistry was difficult to 

identify because of the lack of chemical data, although some 

long-term data are available for PSW-1. A sample collected 

from PSW-1 in 1979 had major ion chemistry similar to that 

of deep glacial wells, but samples obtained from 2002 to 2005 

show a shift in ion ratios and appear to reflect several shallow 

sources of contamination, particularly road salt and septicsystem leachate (table 7). The increase in concentrations of 

Cl-, Na+, HCO3

-

, and other constituents could result from 

an increase in population and a concomitant increase in 

contaminant sources, particularly septic-tank drainfields 

(table 7; figs. 11 and 18). 

Redox Conditions and DOC 

Redox reactions affect many chemical processes in 

aquifers, including the speciation and mobility of naturally 

occurring elements, such as Fe, Mn, S, As, and U, and the 

transformation of anthropogenic compounds, such as NO3

−

, 

chloroform, and PCE. Redox conditions proceed along a 

well-documented sequence of Terminal Electron Acceptor 

Processes (TEAP), in which a single TEAP typically 

dominates at a particular time and aquifer location (Chapelle 

and others, 1995). The predominant TEAPs, from more 

oxidizing to reducing are O2- reducing (also referred to as 
Aquifer Chemistry 77

oxic in this report), NO3

−

reducing, Mn-reducing, Fe-reducing, 

SO4

2− reducing, and methanic (containing CH4

). A redox 

classification scheme developed for the regional-scale TANC 

studies, as described by Paschke and others (2007) and 

presented in Appendix 4, uses various chemical indicator 

species to classify redox conditions in each groundwater 

sample; however, the present study has modified this 

scheme based on data that are available for hydrogen sulfide 

and methane (table 7). In several instances, conflicting or 

overlapping indicators of redox conditions occur and are 

related to mixtures of water with different redox indicators 

but also may indicate disequilibrium between redox indicators 

(table 7).

Groundwater in the glacial aquifer generally is oxic, 

but commonly contains indicators of NO3

-

, Mn-, Fe-, or 

SO4

2- reducing, or significantly increased groundwater 

concentrations of Cl− and other major ions (table 7), as well 

as trace elements such as B and Mn (fig. 21B). B is present 

in domestic sewage as a residue of laundry detergents and, 

therefore, can be an indicator of septic-system leachate in the 

Woodbury study area. 

Naturally Occurring Constituents of Concern

Naturally occurring constituents of concern in this study 

area include trace elements, such as As, U, 222Rn, and Mn, 

as well as some major ions, including Cl− and SO4

2−. These 

constituents can be mobilized from sediments and rocks 

by different geochemical processes, or derived from deep 

Mesozoic basin water that has high concentrations of total 

dissolved solids.

Concentrations of dissolved As generally were low in 

the study area, which is typical of glacial aquifers in much 

of the eastern United States (Thomas, 2007). Dissolved As 

in groundwater is largely affected by adsorption processes, 

which can vary with redox conditions, pH, competing ions, 

and the sorption properties of mineral surfaces. Dissolved As 

concentrations in the groundwater samples ranged from less 

than the MRL of 0.2 μg/L to 5.8 μg/L, but only eight samples 

from the study area had concentrations at or greater than the 

MRL (fig. 22A). Much of the glacial deposits in the study area 

likely are derived from underlying basalt (fig. 7); groundwater 

in unaltered basalt commonly contains low As concentrations 

(Welch and others, 2000). Several groundwater samples that 

contained some of the highest dissolved As concentrations 

had DO concentrations less than 2 mg/L (fig. 23A), and the 

two samples with the highest As concentrations (WY35 and 

WY83) contained dissolved Fe concentrations greater than 

2,500 μg/L (table 8), indicating greater As mobility under 

anoxic conditions. As discussed in the previous section, 

“Redox Conditions and DOC,” the anoxic conditions were 

associated with concentrations of DOC, and some of the 

highest As (fig. 23B), Mn, and Fe concentrations (fig. 20C and 

D) in groundwater samples were from aquifer sediments that 

appear to be derived from the organic-rich rock of the Cass 

Formation, which underlies glacial deposits about 0.6 km to 

the north (fig. 7; table 8; Burton, 2006). It also is possible that 

additional subsurface faults, not shown on the geologic map, 

exist that have exposed the Cass Formation to the underlying 

glacial deposits nearer WY83 (W.C. Burton, U.S. Geological 

Survey, written commun., 2005). As can be mobilized by 

reduction of As(V), or by the reductive dissolution of ferric 

oxyhydroxides coupled to the oxidation of organic C, which 

typically results in the subsequent mobilization of sorbed As 

(Stollenwerk, 2003). Other monitoring wells downgradient 

from WY83, including WY35, WY88, and WY53, also 

had As concentrations that were greater than background 

concentrations and may have been affected by sediments 

derived from the Cass Formation (fig. 22A); the locations of 

these wells, and their geochemical similarity, are consistent 

with the southward, down-valley direction by which rocks 

from the Cass Formation would have been transported by 

glacial ice. Wells S401 and F344 that appear to be screened in 

glacial deposits derived from the Newark Supergroup rocks 

in the Hartford Basin also had As concentrations greater than 

the MRL. Concentrations of As also were somewhat greater 

in bedrock wells WY86 and WY87, which are close to the 

eastern border fault. The concentrations of As in samples 

from PSW-1 were less than the MRL, although communitysupply well WY66 that is 2 km to the west had detectable 

As concentrations (1.6 mg/L); well WY66 also had high 

concentrations of Mn and Fe of 1,800 mg/L and 4,700 mg/L, 

respectively, indicating reducing conditions (table 8) that 

might be caused by organic-rich sediments.

Dissolved U concentrations in groundwater samples 

were low, ranging from less than the MRL of 0.2 μg/L to 

1.8 μg/L (table 8). Other glacial aquifers throughout the 

Northeast also had low U concentrations compared to glacial 

aquifer systems throughout the United States (Ayotte and 

others, 2007). U concentrations were highest in wells with 

low DO (<0.8 mg/L) despite the fact that U is more soluble 

under oxic conditions; this indicates that other factors 

likely affected U concentrations, such as proximity to the 

bedrock interface (fig. 22B), or groundwater pH and HCO3

-

concentrations (figs. 23C and D). Under oxic conditions, 

U exists in the 6+ oxidation state [U(VI)] and will form the 

oxycation, uranyl (UO2

2+) in normal pH ranges of 6 to 9. 

Under anoxic conditions, U(VI) generally is reduced to U(IV) 

and is much less mobile. The U concentration was below 

the MRL in a groundwater sample from WY83, despite the 

high concentration (11 μg/g) in a sediment extraction with 

10 percent HNO3 from aquifer material adjacent to the well 

screen (table 5), because U typically is reduced in organic-rich 

horizons. The abundance of U on selected ferric hydroxide 

grains of sediments from several sites, as determined by 

fission track radiography (fig. 9), is consistent with the large 

abundance of U in the extraction of sediment from WY83, 

probably from the Cass Formation, relative to other aquifer 

core samples. Concentrations of U were highest in wells 

in crystalline (Paleozoic-age) bedrock and glacial till and 

generally were highest in the deepest well of each cluster, 

indicating that the proximity to bedrock affects the dissolved 
78 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

Glacial stratified

deposits

Glacial till

deposits

Paleozoic

(crystalline)

bedrock

Triassic and Jurassic

bedrock

TRIASSIC AND JURASSIC

BEDROCK

A A'

Till

WY102

WY100

WY101

WY103

WY106

WY74

WY73

WY72

WY105

WY96

WY97

FAULT

WY71

WY70

WY69

WY104 WY87WY86

WY35

WY88

60

100

80

120

140

160

40

20

PSW-1

B B'

C C' D'

TILL

Pomperaug River

D

Glacial stratified

deposits

Glacial till

deposits

Glacial till

deposits

PSW-1

50

60

70

80

90

40

60

80

20

100

120

60

70

80

90

Triassic and Jurassic

bedrock

Triassic and Jurassic

bedrock Triassic and

Jurassic

bedrock

0.2

1.3 0.66

5.4

3.4 3.6

5.7

9.3

8.5

3

4.2

5.9

5.5

2.3

1.4

4

4

4.7

1.5

6.4

4.4 

(0.2 - 6.1)

3.6

0.57 0.66

5.4

3.4

8

1.6

4.4 

(0.2 - 6.1)

3.6

0.63

2.5 9.1

2.1

9.3

8.5

0.3

8

1.6 1.6

8

ALTITUDE ABOVE NAVD 88, IN METERS

WY85

WY84

WY78

WY99

WY98

WY77

WY80

South Brook

0 0.25 MILES

0 250 METERS 

0 0.25 MILES

0 250 METERS 

0 0.25 MILES

0 250 METERS 

0 0.25 MILES

0 250 METERS 

Median and range of 

dissolved oxygen concentrations,

in milligrams per liter

4.4 (0.2 - 6.1)

EXPLANATION

Monitoring well, screen, and identifier

Continuously screened well

Production well and identifier

Water table

PSW-1

50

VERTICAL SCALE GREATLY EXAGGERATED 

WY78

Glacial stratified

deposits

WY85

WY84

WY90

WY89

WY94

WY93

South Brook

South Brook

WY78

WY77

WY99

WY98

WY80

WY81

WY82

WY90

WY89

WY92

WY91

WY78

WY77

WY95

WY83

Multilevel

samplers:

WY92f

WY92e

WY92c South Brook

Unnamed Tributary

WY71

WY70

WY69

WY104

Glacial stratified

deposits

WY102

WY100

WY101

WY103

WY106

WY74

WY73

WY72

WY105

WY76

WY75

WY83

WY79

WY92

WY91

Pomperaug River

Unnamed Tributary

Multilevel

samplers:

WY92f

WY92e

WY92c

WY35

WY88

WY81

WY82

3

4.2

5.9 4.4 (0.2 - 6.1)

5.5

2.3 0.5

8.6

2.9

1.4

4.8 4

4

8.8

3.6

0.63

0.2

0.3

2.3 0.6

4.7

1.5

6.4

Figure 19. Hydrogeologic sections showing medians, and selected ranges, of dissolved oxygen concentrations in groundwater 

samples from wells in the study area, Woodbury, Connecticut.
Aquifer Chemistry 79

0

0.1

0.2

0.3

0.4

0.5

10

5

100

400

0

5

10

15

20

0

5

10

15

5

0

10

15

20

25

78

98

85

35

83

102

106

F344

E

77

78

79

80

83

F 88

98

0

2

4

6

8

10

DISSOLVED ORGANIC CARBON, IN MILLIGRAMS PER LITER

0.2 1 10 100

DISSOLVED OXYGEN

CONCENTRATION, IN

MILLIGRAMS PER LITER

NITRATE PLUS NITRITE

CONCENTRATION, IN

MILLIGRAMS PER LITER

AS NITROGEN

DISSOLVED MANGANESE

CONCENTRATION, IN

MILLIGRAMS PER LITER

DISSOLVED IRON

CONCENTRATION, IN

MILLIGRAMS PER LITER

DISSOLVED SULFATE

CONCENTRATION, IN

MILLIGRAMS PER LITER

HYDROGEN SULFIDE

CONCENTRATION, IN

MILLIGRAMS PER LITER

12

78

78

83

83

85

85

98

99

102

101

100

B403

79

85

85

83

85

90

87

SB120

72

A

B

C

D

98

S401

B403

SB120

85

EXPLANATION

Glacial aquifer, shallow, and identifier

Glacial aquifer, deep

Glacial aquifer, deep (Hartford Basin)

Bedrock, shallow

Bedrock, deep

PSW-1

Glacial aquifer, shallow (Hartford Basin)

Glacial aquifer, domestic well

(Pomperaug Basin)

Figure 20. Concentrations of dissolved 

organic carbon (DOC) as a function of 

the concentration of electron acceptor 

indicators, including dissolved (A) oxygen, 

(B) nitrate plus nitrite, (C) manganese, (D) 

iron, (E) sulfate, and (F) hydrogen sulfide, 

in groundwater samples from wells in the 

study area, Woodbury, Connecticut.
80 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06 DISSOLVED BORON CONCENTRATION, IN MILLIGRAMS PER LITER

20

26

23

8 11

33

30 Number of values

EXPLANATION 

75th percentile

Median

25th percentile

Data value less than or equal to

1.5 times the interquartile range

outside the quartile

Data value less than or equal to

1.5 times the interquartile range

outside the quartile

Outlier data more than 1.5 times the 

interquartile range

Outlier data more than1.5 times the 

interquartile range

B

B

B

BACKGROUND WELLS

WELLS AFFECTED BY

SEPTIC-SYSTEM LEACHATE

WELLS AFFECTED BY

NATURAL ORGANIC MATTER

1 2 3

}Interquartile

range

A

B

DISSOLVED MANGANESE CONCENTRATION,

 IN MILLIGRAMS PER LITER

0.1

1

10

100

1,000

Mn

Mn

Mn

Mn REPORTING LEVEL = 0.3

0.01

0.1

1.0

10

20

CONCENTRATION NITRATE PLUS NITRITE,

IN MILLIGRAMS PER LITER AS NITROGEN

27 24

34

NO3- REPORTING

LEVEL = 0.06

NO3

-

+

NO2

-

NO3

-

+

NO2

-

NO3

-

+

NO2

-

0.1

1

10

10

5

100

100

300

26 24

33

DOC

DOC

DOC

DOC REPORTING LEVEL = 0.3

DISSOLVED ORGANIC CARBON (DOC)

 CONCENTRATION, IN MILLIGRAMS PER LITER

Figure 21. Distributions of concentrations of (A) dissolved organic carbon (DOC) and nitrate plus nitrite (NO3

−

+NO2

−

, and 

(B) dissolved boron (B) and manganese (Mn), in groundwater samples from wells in relation to the group of wells (1) not 

apparently affected by abundant natural organic matter or septic-system leachate (background), (2) affected primarily by 

abundant natural organic matter, and (3) affected primarily by septic-system leachate in the Woodbury study area.
Aquifer Chemistry 81

U concentration (fig. 22B). This is consistent with the lower 

sorption capacity for U and the net release of U(VI) by till 

samples in batch-reactor experiments, as discussed previously 

in “Adsorption Reactions.” Probable sources of U include 

minerals in the underlying Mesozoic rocks (arkose, shale and 

siltstone, and mineral-filled veins in basalt) and in upland 

metamorphic rocks and pegmatites, as well as on ferric 

hydroxide grain coatings on glacial sediments derived from 

these source rocks. Geochemical speciation of water samples 

collected from wells in or near bedrock, which have relatively 

high HCO3

-

 concentrations, shows that uranyl-carbonate 

complexes (UO2(CO3)2

-2 and UO2

(CO3)3

-4) predominate. 

These uranyl-carbonate complexes can inhibit U adsorption 

and contribute to greater U mobility, as observed in other 

aquifer systems with high HCO3

-

 concentrations (Brown and 

others, 2007). The mobility of the uranyl complex is limited 

by sorption and higher pH, but with higher concentrations 

of competing ions, uranyl will tend to desorb from ferric 

oxyhydroxides, clays, and other mineral surfaces (Davis and 

others, 2004).

Activities of 226Ra and 228Ra were relatively low (from 

less than 0.018 to 0.95 pCi/L and from 0.12 to 0.8 pCi/L, 

respectively) in the study area (figs. 22C and D) and are 

consistent with the low concentrations of U measured in 

groundwater samples. The activities of 226Ra and 228Ra did 

not increase with depth, as did U; in fact, the activity of 226Ra 

was greater in shallow parts of the glacial aquifer and could 

be related to its greater mobility at lower pH (Szabo and 

Zapecza, 1991). 222Rn activities in groundwater samples from the study 

area ranged from 490 to 13,000 pCi/L, and all samples were 

greater than the USEPA proposed MCL of 300 pCi/L (USEPA, 

2006a) (fig. 22E). The median 222Rn activity in samples 

from wells screened in the glacial aquifer of the study area 

was 1,100 pCi/L, greater than the median of 440 pCi/L for 

shallow wells in the glacial aquifer of the CONN (Grady and 

Mullaney, 1998) and greater than the median of 340 pCi/L for 

glacial aquifers in the eastern United States (Ayotte and others, 

2007). Three samples, all from bedrock wells, exceeded the 

alternate MCL (AMCL) of 4,000 pCi/L (USEPA, 2006a). 

The water samples from two wells in upland Paleozoic rocks 

had 222Rn activities of 8,600 and 13,000 pCi/L, whereas the 

samples from wells in fractured basalt had 222Rn activities of 

1,600 and 5,500 pCi/L. 222Rn activities are high (from 3,000 

to 650,000 pCi/L) in some of the crystalline rocks in the 

uplands of Connecticut (Dupuy and others, 1991) and in New 

England crystalline rocks (median of 2,100 pCi/L) (Ayotte and 

others, 2007). High activities of 222Rn were associated with 

the Nonewaug Granite and the Taine Mountain Formation 

(Thomas and others, 1988). Although 222Rn activity was not 

correlated with depth in the glacial deposits, the activities 

in water samples from the bedrock wells generally were 

higher than those in the glacial deposits (fig. 22E). The short 

half-life of 222Rn (3.8 days) precludes the possibility that the 

high activities seen in the glacial aquifer of the study area 

are derived from the upland bedrock aquifers (Brown and 

Zielinski, 2004). The high 222Rn concentrations in groundwater 

may indicate an abundant but relatively immobile mass of U 

and 226Ra on aquifer sediment surfaces, as observed in fission 

track radiographs (fig. 9).

Other naturally occurring contaminants observed in the 

study area were present in concentrations that were below 

USEPA primary drinking-water standards, or that exceeded 

secondary drinking-water standards. High concentrations 

of dissolved Mn and (or) Fe reflect anoxic conditions, and 

one or both exceeded USEPA secondary drinking-water 

standards of 50 mg/L and 300 mg/L, respectively, at wells 

WY35, WY77, WY80, WY83, WY84, WY85, WY87, WY88, 

WY95, WY98, WY99, and WY102 (table 8). The communitysupply well, WY66, to the west of the study area (fig. 1), 

had sufficiently high concentrations of Mn and Fe to require 

Mn- and Fe-removal treatment by the water utility (table 8). 

High concentrations of SO4

2− (300 mg/L) and total dissolved 

solids are associated with groundwater from underlying 

Mesozoic rocks, as discussed at the beginning of this section, 

and exceeded the USEPA secondary drinking-water standards 

of 300 mg/L and 500 mg/L, respectively, in the water sample 

from WY106. Trace element concentrations generally were 

higher in samples from wells in bedrock and near-bedrock 

glacial deposits, as well as from wells affected by septicsystem leachate and (or) road salt, than in samples from 

shallow wells in glacial stratified drift that were relatively 

unaffected by anthropogenic sources (table 8). Dissolved 

concentrations of Cu were high in bedrock well WY86, which 

is near the eastern border fault in the South Brook area that is 

host to some small Cu prospect mines, compared to most other 

wells. Mesozoic basin rocks can have high concentrations of 

Cu and Ba; water samples from wells F344 and S401 from the 

Hartford Basin have high Cu and Ba concentrations relative 

to most other wells, but WY106 had only high concentrations 

of Cu, and WY83 had only high concentrations of Ba. The 

elevated concentrations of dissolved Cu in PSW-1, WY65, and 

SB120 are typical of supply wells because of the steel screen, 

casing, and other pipes and fittings that are in contact with the 

sample water prior to collection. Dissolved concentrations of 

Sr and V were among the highest in samples from wells that 

generally had constituents reflective of deep groundwater from 

the Mesozoic basins, including WY106 in the study area and 

F344 and S401 in the Hartford Basin (fig. 24A). Dissolved 

concentrations of B were higher in samples from bedrock 

well WY106 and other wells that reflect Mesozoic basin 

chemistry (F344 and S401), whereas those of cobalt (Co) were 

higher in wells screened in sediments likely derived from 

the Cass Formation (fig. 24B). Although As, U, Cd, and Pb 

concentrations were high in the 10-percent HNO3 extractions 

of sediment samples collected adjacent to the well screen at 

WY83, only As concentrations were high in groundwater 

samples, indicating that the other constituents were not readily 

desorbed or weathered from the sediments under the anoxic 

conditions. Water samples from wells WY35 and WY88 had 

concentrations of As, Fe, Mn, and DOC that were greater 

than those concentrations in samples from most other glacial 
82 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

35

88

86

87

97

106

83

53

AFFECTED BY SEDIMENTS

DERIVED FROM CASS FORMATION

86

87

97

106

85

100

102

101

80

85 74 76

SB120

65

0.2 0.4 0.6 0.8 1.0

A B

C D

E

97

DISSOLVED ARSENIC CONCENTRATION,

IN MICROGRAMS PER LITER

RADIUM-226 (226Ra) ACTIVITY,

IN PICOCURIES PER LITER

RADIUM-228 (228Ra) ACTIVITY,

IN PICOCURIES PER LITER

RADON-222 (222Rn) ACTIVITY,

IN PICOCURIES PER LITER

DISTANCE FROM WELL SCREEN

TO BEDROCK, IN METERS

DISTANCE FROM WELL SCREEN

TO BEDROCK, IN METERS

DISTANCE FROM WELL SCREEN

TO BEDROCK, IN METERS

DISTANCE FROM WELL SCREEN

TO BEDROCK, IN METERS

DISTANCE FROM WELL SCREEN

TO BEDROCK, IN METERS

0 2,000 4,000 6,000 8,000 10,000 12,000 14,000

88

82

85

86

87

97

106

EXPLANATION

Glacial aquifer, shallow, and identifier

Glacial aquifer, deep, and identifier

Glacial aquifer, deep (Hartford Basin), and identifier

Bedrock, shallow, and identifier

Bedrock, deep, and identifier

PSW-1

Glacial aquifer, domestic well

 (Pomperaug Basin), and identifier

98

S401

SB120

85

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

106

87

DISSOLVED URANIUM CONCENTRATION,

IN MICROGRAMS PER LITER

88

87

93

97

65

98

89

90

S401 F344

86

-30

-20

-10

0

10

20

-30

-20

-10

0

10

20

-30

-20

-10

0

10

20

0

2 4 6

-30

-20

-10

0

10

20

S401 F344

0 0 0.5 1.0 1.5 2.0

-30

-20

-10

0

10

20

Figure 22. Concentrations of dissolved (A) arsenic, (B) uranium, (C) radium-226, (D) radium-228, and (E) radon-222 in groundwater 

samples from wells as a function of distance from the well screen to the bedrock interface in the Woodbury study area, and from 

selected wells elsewhere in the Pomperaug and Hartford Basins, Connecticut.
Aquifer Chemistry 83

Affected by sediments

derived from Cass Formation

120

35

8182

106

106

65

78

80

83

79

85

71

74

94

96

120

DISSOLVED URANIUM CONCENTRATION,

IN MICROGRAMS PER LITER

0 0.5 1.0 2.0 2.0 1.5 5

6

7

8

9

10

pH

88

72

86

87

93

97

101

65

98

F344

S401 89

90

DISSOLVED URANIUM CONCENTRATION,

IN MICROGRAMS PER LITER

0 0.5 1.0 1.5

0

50

100

150

200

BICARBONATE CONCENTRATION,

IN MILLIGRAMS PER LITER

88

69

72

75

86

86

91

93

97

101

98

F344

S401

89

90

106

53

35

DISSOLVED ARSENIC CONCENTRATION,

IN MICROGRAMS PER LITER

0 1 2 3 4 5 6

0

2

4

6

8

10

12

DISSOLVED OXYGEN,

IN MILLIGRAMS PER LITER

88

86

87

83

F344

S401

65

A B

C D

78

83

85

53

EXPLANATION

Glacial aquifer, shallow, and identifier

Glacial aquifer, deep, and identifier

Glacial aquifer, deep (Hartford Basin), and identifier

Bedrock, shallow, and identifier

Bedrock, deep, and identifier

PSW-1

Glacial aquifer, domestic well

 (Pomperaug Basin), and identifier

98

S401

65

85

0 1 2 3 4 5 6

0

2

4

6

8

10

DISSOLVED ORGANIC CARBON

CONCENTRATION,

IN MILLIGRAMS PER LITER 

86 35

87

98

F344

S401

88106

DISSOLVED ARSENIC CONCENTRATION,

IN MICROGRAMS PER LITER

Figure 23. Concentrations of dissolved arsenic as a function of (A) dissolved oxygen (DO), and (B) dissolved organic carbon 

(DOC), and concentrations of dissolved uranium as a function of (C) pH, and (D) bicarbonate in groundwater samples from wells 

in the Woodbury study area, and from selected wells elsewhere in the Pomperaug and Hartford Basins, Connecticut.
84 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

wells; as with WY83, the locations of WY35 and WY88 

are consistent with the southward direction to which glacial 

deposits would have been transported (fig. 7). Glacial wells 

S401 and F344 that overlie rocks of the Newark Supergroup in 

the Hartford Basin, were found to have high concentrations of 

constituents such as As, Ba, B, Cu, Li, Sr, U, and V, relative to 

most other glacial wells in the study area (table 8).

Concentrations of Ba, Cd, Cr, Cu, Pb, Ni, Sr, Tl, and 

Zn were high in groundwater samples from WY85 relative 

to those from most other wells and appear to be related to 

septic-system leachate, either in the effluent itself or mobilized 

from aquifer sediments. Trace elements, including Cr, Cu, 

Pb, Ni, and Zn, can be present in septic cleaners and can be 

used for source identification (Noss and others, 1987). Wells 

that are affected by septic leachate, as indicated by the data 

points labeled “high DOC, septic-system leachate source” 

(fig. 24B) generally had high concentrations of both B and Co. 

Although concentrations of B (fig. 24B) were relatively high 

(12 to 155 μg/L) in some samples from wells that appear to be 

affected by upgradient septic-tank drainfields, concentrations 

in samples from WY85 and WY74 were not, probably because 

the septic-system leachate that affects these sites is primarily 

from commercial sites that do not use laundry detergents. The 

groundwater sample from well WY85 had by far the highest 

Sr concentration (0.72 mg/L) of any sample from wells in 

the study area and may be affected by seawater, which has an 

average Sr concentration of 8 mg/L (Drever, 2005) (fig. 24A); 

this supports its placement near seawater on the graph of 

Cl−Cl:Br ratio (fig. 16). Although saltwater intrusion is not a 

factor at this site, the amount of seawater residue from seafood 

waste and lobster tanks at a nearby restaurant discharged to 

the upgradient septic-tank drainfield may have been enough 

to affect constituents such as Cl, Br, and Sr in groundwater 

samples from WY85. High concentrations of ions in road 

salt and septic-system leachate can mobilize trace elements 

through competitive ion exchange, desorption of inner-sphere 

surface complexes (Hingston and others, 1972), or formation 

of aqueous complexes (Doner, 1978). Competitive ion 

exchange takes place whether or not the ions in the incoming 

solution have a lower affinity for the exchanger than sorbed 

ions (Appelo and Postma, 1993).

Stable Isotopes

Stable isotopes were used to determine different chemical 

sources that affect groundwater quality and the amount of 

mixing of the waters. The sources may have different isotopic 

signatures due to the source itself or to chemical fractionation 

related to evaporative or chemical processes. Stable isotopes 

measured from constituents in water samples include d18O, 

dD, d18O of NO3

−

, d15N of NO3

−

, d15N of NH4

+

, d34S, and d13C 

of DIC. Stable isotopes also were analyzed in organic and 

inorganic C in sediments and rocks, and in sulfide minerals, as 

mentioned in the methods section.

The stable isotopes d18O and dD were used to help 

determine surface-water leakage to groundwater and the 

resulting effect on groundwater chemistry. The global meteoric 

water line (MWL), which represents a global average of d18O 

and dD in precipitation (and an average of many local or 

regional meteoric water lines that differ from the global line 

as a result of varying climatic and geographic parameters), 

has a slope of about 8 (Craig, 1961; Clark and Fritz, 1997). 

Temperature correlates strongly with d18O and dD because 

the process of rainout distills the heavy isotopes from the 

vapor (Clark and Fritz, 1997). Precipitation that runs off to 

streams or that is quickly recharged to groundwater reflects 

the d18O and dD of the local rainfall. Evaporation of surface 

water, which is affected by the humidity, causes enrichment 

of d18O and dD through Rayleigh distillation (Craig, 1961). 

Transpiration does not involve fractionation (Zimmerman and 

others, 1967; Förstel, 1982), although some vegetation such 

as permanent grasses can increase evaporative loss seasonally 

(Darling and Bath, 1988). Comparison of these ratios in 

groundwater samples to the MWL can provide information 

on whether samples primarily follow a distribution reflecting 

variations in the isotopic composition of precipitation or 

whether secondary processes such as evaporation have shifted 

values of d18O and dD off of the MWL (Coplen, 1994). The 

varying slopes of regional MWLs (not shown) probably reflect 

the humidity of the local air mass, which imparts a distinctive 

evaporative isotopic signature to rainfall and hence to stream 

samples (Kendall and Coplen, 2000).

The d18O and dD data for the study area were compared 

to a local meteoric water line (LMWLct) that was generated 

by analysis of stream samples collected from sites in 

Connecticut; the LMWLct serves as a proxy for the isotopic 

signature of local precipitation (Kendall and Coplen, 2000) 

(fig. 25A). Most groundwater samples and surface-water 

samples from South Brook and the Pomperaug River plotted 

along a line with a slope of about 9, labeled as LMWLpomp 

(fig. 25A). The LMWLpomp line is more representative 

of the study area than the stream data used to produce 

LMWLct because the d18O and dD values in rainfall vary 

locally (Coplen and Kendall, 2000). Samples from wells that 

reflect a greater contribution from older, deep groundwater, 

including WY106, F344 (deep glacial well in the Hartford 

Basin), WY82, WY86, and WY77, were depleted in the heavy 

isotopes d18O and dD; these isotopes were depleted during the 

glacial period (Rozanski and others, 1993). The deep glacial 

well WY82 is located within 0.1 km of the eastern border 

fault, (fig. 7) and chemistry of the water also may have been 

affected by older basin water, as supported by d18O and dD 

data values. Aquifer weathering at low temperatures generally 

has little effect on dD, but d18O is enriched by dissolution of 

calcite (Clayton and others, 1966).

The dD and d18O values in surface waters are enriched by 

evaporation and were used here to assess the effects of stream 

leakage on shallow groundwater. Water that has evaporated 

from surface-water bodies, or that has mixed with evaporated 

water, plots below the MWL, typically along a divergent line 

(Drever, 2005) with a slope of about 6 (fig. 25A). Isotope 

ratios for samples from wells near streams or riparian zones, 
Aquifer Chemistry 85

in particular South Brook and to a lesser extent the Pomperaug 

River, plotted along an evaporation line that reflects surfacewater leakage from the Pomperaug River (WY35 and WY88, 

and one sample at PSW-1), or South Brook (WY78, WY80, 

WY87, WY98 and WY99) or septic-system leachate (WY71, 

WY84, and WY85; fig. 25A). The effects of streamflow losses 

on groundwater chemistry vary; in some cases, solutes in 

water samples from shallow wells are diluted by stream water. 

At other wells, such as WY78, the chemistry of groundwater 

samples was affected by road salt, and solute concentrations 

increase seasonally. Because surface-water samples and 

groundwater samples for analysis of dD and d18O values were 

not always collected at the same time, direct relationships 

could not be made, and mixing could not be quantified. 

Ideally, samples are collected within a period of a few days 

in summer when dD and d18O values for surface water and 

groundwater are most different. The plotting of sample data 

from wells that are affected by septic-system leachate along 

the evaporation line (fig. 25A) may result from evaporation 

of water near the points of use, such as dishwashers or 

showers. Denitrification at some well sites that are affected 

by septic-system leachate, such as WY85, also could result in 

dD and d18O values for groundwater samples that plot along 

the evaporation line; biologically formed NO3

−

 contains d18O 

depleted water, since one O atom comes from atmospheric O2, 

and the other two come from the water (Clark and Fritz, 1997).

The d13C values for DIC in groundwater samples range 

from -20.7 to -12.2 per mil with a median of -17.8 per mil 

DISSOLVED STRONTIUM CONCENTRATION, 

IN MICROGRAMS PER LITER

A

DISSOLVED BORON CONCENTRATION, 

IN MICROGRAMS PER LITER

DISSOLVED COBALT CONCENTRATION,

 IN MICROGRAMS PER LITER

DISSOLVED VANADIUM CONCENTRATION,

 IN MICROGRAMS PER LITER

B

0 100 200 300 400 500

0

1

2

3

4

35

88 73

106

83

102

401

79

89 90

74 76

120

EXPLANATION

Glacial aquifer, shallow, and identifier

Glacial aquifer, deep

Glacial aquifer, deep (Hartford Basin)

Bedrock, shallow

Bedrock, deep

PSW-1

Glacial aquifer, shallow (Hartford Basin)

Glacial aquifer, domestic well

 (Pomperaug Basin)

98

86

106

S401

B403

SB120

85

53

S401

F344

F344

100

10

1

0.1

0.05

20 1,000 2,000

Affected by sediments

derived from Cass Formation

Affected by septic-system

leachate

Affected by deep groundwater

from Mesozoic Basin

Affected by

deep groundwater

from Mesozoic Basin

90

Symbol outline color:

Low DOC, natural organic matter source

High DOC, natural organic matter source

High DOC, septic-system leachate source

87

85

106

Figure 24. Dissolved concentrations of (A) strontium as a function of vanadium, and (B) boron as a function of cobalt, in 

groundwater samples from wells in the Woodbury study area, and from selected wells elsewhere in the Pomperaug and 

Hartford Basins, Connecticut. (DOC, dissolved organic carbon)
86 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

(table 8). The heavier d13C values of calcite in some core 

samples, including a glacial till sample (-7.34 per mil) at 

WY90 and a basalt sample (-8.52 per mil) at WY87, are 

likely affected by heavier d13C values observed in calcite 

(table 5). The groundwater sample from fractured basalt at 

WY106 exhibits a heavy d13C value (-13.6 per mil) relative 

to other water samples; based on its near saturation with 

respect to calcite (table 7), this may indicate dissolution of 

calcite at some point along its flow path. The d13C values for 

DIC in some groundwater samples also may be affected by 

reaction with the lighter d13C values in organic C from glacial 

sediments (table 5); wells WY102 and WY100, which are 

screened below organic-rich sediments, had lighter d13C values 

of -20.3 and -19.2 per mil, respectively (table 8).

The d34S of SO4

2− in groundwater samples ranged from 

0.39 per mil to 16.4 per mil and appears to reflect several 

processes and mixtures of sources (table 8; fig. 25B). The 

source of the light d34S of SO4

2− value of 0.39 per mil in the 

groundwater sample from WY97 (the upland bedrock well) 

could reflect the oxidation of FeS2, which might be present 

in secondary fractures. The heaviest d34S value, 16.4 per mil, 

in water from WY83 supports the earlier hypothesis that 

sediments at this well were derived, in part, from the Cass 

Formation of the Newark Supergroup. The d34S values in the 

equivalent rock unit (Passaic Formation) of the Newark Basin 

range from 3.3 to 11 per mil (El-Tabakh and others, 1997), and 

the d34S values in sedimentary SO4

2− in rocks of Jurassic age 

and older typically range from 10 to 30 per mil, with a mean 

from 15 to 20 per mil (Holser and Kaplan, 1966). The d34S 

values for several deep glacial wells fall along a hyperbolashaped mixing line between that of WY100, which is of 

intermediate depth about 8.2 m above bedrock, and WY106, 

the deep bedrock well that is finished in fractured basalt 

(fig. 25B). Mixtures of two components that have different 

isotope ratios and different concentrations of a given element 

plot as hyperbolas on graphs (Faure, 1986), similar to figure 

25B. The curve may result from an exponential relation caused 

by the fractionation of 34S.

Bedrock well WY106 had high concentrations of 

SO4

2− (300 mg/L) and relatively heavy d34S (13.6 per mil) 

(fig. 25B; tables 7 and 8). The apparent groundwater age 

(more than 50 years) at WY106 is old relative to ages for 

other samples in the study area, as discussed in a later section, 

and the chemistry of the water may reflect contributions 

from ancient water in fractured Mesozoic basin rocks. On 

the basis of the high concentrations of SO4

2− and Ca and low 

concentrations of HCO3

-

 in this ancient water, together with 

the mostly arid depositional environment of the Mesozoic 

rocks in the Pomperaug Basin (LeTourneau and Huber, 2006) 

and subsequent alteration after rifting, the water composition 

could result from gypsum or anhydrite dissolution followed 

by the precipitation of calcite. The d34S of SO4

2− values for 

WY83 (16.4 per mil) and WY86 (11.8 per mil) also are heavy 

but do not plot along the mixing line with WY106 (fig. 25B). 

The heavy sulfur (S) in water samples from these wells could 

be caused (1) by SO4

2− reduction and subsequent formation 

of sulfide minerals such as FeS and FeS2, which effectively 

removes the lighter 32S from the pool, (2) by dissolution of 

gypsum, or (3) by degradation of organic matter that has heavy 

d34S. Groundwater samples from wells that had heavy d34S, 

including WY83, 86, 99, 98, and 78 (fig. 25B), also had high 

concentrations of DOC and (or) natural organic carbon and, 

consequently, reducing conditions; SO4

2− concentrations were 

low, as would be expected under SO4

2−reducing conditions. 

Similarly, groundwater samples at sites apparently affected 

by septic-tank drainfields also had low SO4

2− concentrations, 

but relatively depleted d34S values in SO4

2− (wells WY70, 

71, 73, 74, 85, 90, and 96). The difference is likely caused 

by the reactions subsequent to the reduction of SO4

2− to 

H2S: in organic-rich sediments, the removal of S by the 

formation of sulfide minerals results in enriched 34S ratios in 

the residual SO4

2−, whereas near septic-tank drainfields, the 

associated exsolution of H2S results in depleted 34S ratios in 

the residual SO4

2−.

The d15N and d18O of NO3

−

 values are used to distinguish 

among all sources of NO3

−

, except ammonium fertilizers and 

bacterially produced soil NO3

−

 (Clark and Fritz, 1997). The 

d15N values in NO3

−

 for groundwater samples from most wells 

were less than 9 per mil, and the d18O values in NO3

−

 generally 

were less than 5 per mil (fig. 26A). These isotope values, and 

the sparsity of ammonium fertilizers used in the study area, 

indicate that the NO3

−

 in most samples formed from decayed 

organic matter in the soil zone. The relatively high d15N of 

NO3

−

 in some of the samples, however, indicates effects from 

sewage and animal waste and (or) denitrification, which 

enriches the d15N in NO3

−

. Water samples from six wells had 

d15N values greater than 9 per mil, including wells WY71, 

73, 79, 90, 92, and 102. The small percentage of agricultural 

land use in the study area is consistent with the depleted d18O 

of NO3

−

 in samples, relative to those d18O of NO3

−

 in samples 

from agricultural areas that are affected by nitrate fertilizers 

(McMahon and others, 2007). It is not likely that atmospheric 

deposition could produce NO3

−

 concentrations larger than 

0.5 mg/L as N within the study area, based on average 

precipitation-weighted concentrations in wet deposition from 

National Atmospheric Deposition Program (NADP) stations 

in New England and southern New York (NADP, 2007). 

NO3

−

 concentrations in shallow groundwater beneath forested 

areas in Connecticut typically ranged from less than 0.1 to 

0.74 mg/L as N, with a median of 0.19 mg/L as N (Grady and 

Mullaney, 1998), so natural soil N is not a likely source of the 

high NO3

−

 concentrations in recharge. Groundwater NO3

−

 that 

originates from septic-tank drainfields is enriched with 15N as a 

result of biological fractionation; NH4

+

 is characterized by the 

enriched d15N of catabolic organisms (including humans) and 

microbially converted to NO3

−

 in shallow groundwater (Clark 

and Fritz, 1997). The presence of other electron donor point 

sources, including chemical spills or leaking underground 

storage tanks as in the case of WY95, or natural electron 

donors such as FeS2 in aquifer sediments, also can cause the 

conversion of NO3

−

 to N2 (denitrification). The denitrification 

of NO3

−

 to dissolved N2 and intermediate products results 
Aquifer Chemistry 87

-60

-55

-50

-45

-40

GMWL

LMWLct

Evaporation Line y = 6.08x + 0.776

LMWLpomp

DELTA HYDROGEN-2 (δD), IN PER MIL,

VIENNA STANDARD MEAN OCEAN WATER

DELTA OXYGEN-18 (δ18O), IN PER MIL

South Brook

GMWL, global meteoric 

water line

LMWLct, local meteoric

water line, Connecticut 

Pomperaug River

LMWLpomp, local meteoric

water line, Pomperaug River

watershed, inferred

Evaporation line, inferred

y = 9.077x + 23.78

0

88

86

97

106

83

Intermediate glacial (hypothetical end point)

Fractured basalt

Deep glacial (mixture) (hypothetical end point)

DISSOLVED SULFATE CONCENTRATION, IN MILLIGRAMS PER LITER

100 200 300

DELTA SULFUR-34 (δ34S) OF SULFATE, IN PER MIL,

VIENNA CANYON DIABLO TROILITE

Mixing with Mesozoic bedrock water

EXPLANATION

Glacial aquifer, shallow,

and identifier

Glacial aquifer, deep, and identifier

Glacial aquifer, deep, and identifier

(Hartford Basin), and identifier

Bedrock, shallow, and identifier

Bedrock, deep, and identifier

PSW-1

Glacial aquifer, domestic well

 (Pomperaug Basin), and identifier

89

86

58

Month/year and upstream/

downstream location 

EXPLANATION

Glacial aquifer, shallow,

and identifier

and identifier

and identifier

Glacial aquifer, deep,

Bedrock, shallow,

Bedrock, deep, and identifier

PSW-1

98

86

106

99

Affected by 

septic-system leachate

Natural

organic

carbon

effects

Symbol outline color

Low DOC, natural organic

matter source

High DOC, natural organic

matter source

High DOC, septic-system

leachate source

Symbol outline color

Low DOC, natural organicmatter source

High DOC, natural organicmatter source

High DOC, septic-system

leachate source

69

72

75

81

82

100

101

78

88

98

99

102

73

76

85

80

90

71

74

96

Mixing line

35

88

73

77

82

86

F344

84 F344

87

97

78

78

80

83

98

99

102

106

106

100 85

71

SB120

12/03

12/03

12/04

12/04 down

1/05 down

1/05 up

1/05 up

A

B

-57.5

-52.5

-47.5

-42.5

-37.5

-9.25 -9.0 -8.75 -8.5 -8.25 -8.0 -7.75 -7.5 -7.25 -7.0 -6.75 -6.5 -6.25

5

10

15

0

2.5

7.5

12.5

17.5

50 150 250 350

SB120

Figure 25. (A) Isotope values of delta oxygen-18 as a function of delta hydrogen-2 for samples of groundwater and surface water, and

(B) concentrations of dissolved sulfate as a function of delta sulfur-34 of sulfate for samples of groundwater, collected in the Woodbury 

study area, and from selected wells elsewhere in the Pomperaug and Hartford Basins, Connecticut. Symbols are color coded for the 

estimated relative dissolved organic carbon (DOC) source and strength.
88 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

in an increase of d15N and d18O of the residual NO3

−

 and is 

common in reduced groundwaters (Kendall, 1998; Böhlke, 

2002). Denitrification of NO3

−

 in locally reduced waters is 

possible in some samples, based on enriched values of d15N in 

NO3

−

 and (or) the presence of excess N2 concentrations up to 

7.8 cm3/L. This could be the case for WY79, 80, 83, 84, 85, 

89, 90, and PSW-1 (table 11). The ratio of dissolved gases in 

the water sample from WY84 appeared to be altered by gas 

stripping, possibly caused by the generation of CH4 and HSfrom organic-matter decomposition, and so this sample was 

not included in the analysis. Other samples were not analyzed 

because of the gas-stripping problem (WY85) or because of 

poor well yield (WY89 and other wells screened in till). The 

d15N and d18O in NO3

−

 from anoxic water can be positively 

correlated, and some samples show a slight 1:2 fractionation 

trend that has been reported for denitrification (fig. 26A), but 

insufficient data exist for a valid determination for this study 

(McMahon and others, 2008). 

The d15N of NO3

−

 and concentrations of NO3

−

 in samples 

with excess N2 were corrected for denitrification, where 

possible, to determine initial conditions and plotted with 

concentrations of NO3

−

 as N (fig. 26B) (McMahon and others, 

2008). Where necessary, initial concentrations were obtained 

by correcting measured concentrations for denitrification 

effects produced in the aquifer (McMahon and others, 

2008). Samples with d15N of NO3

−

 less than about 9 per mil 

likely were derived from soil NO3

−

 and ammonium fertilizer 

sources, whereas the sample from WY90 with relatively 

high concentrations of NO3

−

 had more enriched d15N of 

NO3

−

, which likely was derived from septic-tank drainfields 

(fig. 26B). The groundwater samples with the largest NO3

−

concentrations were obtained from wells downgradient from 

residential septic-tank drainfields; well WY90 had a d15N value 

(9.5 per mil) that is consistent with a septic-tank drainfield 

source. Adequate samples could not be obtained from WY84, 

WY85, and WY89, which also appear to have been affected 

by septic-system leachate, because of inadequate yield or 

gas stripping as described previously. The sample with the 

second highest NO3

−

 concentration (well WY79) had a d15N 

of NO3

−

 of 3.9 per mil, which is consistent with a fertilizer 

source of N. However, based on its location in the commercial 

area, and the presence of anthropogenic organic compounds 

discussed in a later section, “Organic Constituents,” well 

WY79 also appears to be affected by septic-system leachate. 

NO3

−

 concentrations in samples from WY83 typically were 

less than the MRL (0.06 mg/L as N), but the d15N of NH4

+

 of 

one sample was 2.6 per mil (not shown in table 8). Transport 

of NO3

−

 leached from septic-tank drainfields is limited by 

denitrification coupled to the oxidation of organic C (Hinkle 

and others, 2007). This effect of organic C from septic-system 

leachate on groundwater redox chemistry is spatially limited, 

based on the predominance of oxic conditions throughout most 

of the aquifer.

Organic Constituents

Volatile organic compounds and pesticides were detected 

in groundwater samples from many of the wells and generally 

were associated with residential, commercial, and industrial 

land use in the study area.

Volatile Organic Compounds

Volatile organic compounds were widely detected 

in water samples from monitoring wells throughout the 

glacial aquifer, and from PSW-1 (table 12). Thirty VOCs 

were detected in one or more water samples out of a total of 

85 VOCs analyzed (table 13). VOCs were detected at 32 of 

the 36 wells sampled for this study; one well in a forested 

area (WY86) was not sampled for VOCs. The concentrations 

of the 20 most frequently detected VOCs are shown in 

figure 27. Higher median concentrations and a larger number 

of detections of VOCs generally were present in samples 

from the shallow glacial deposits rather than samples from 

the deep glacial deposits or fractured bedrock (fig. 27) and 

were associated with commercial, light-industrial, and 

residential land-use areas (table 13). Point sources are present 

in the commercial area upgradient from PSW-1, including 

two or more chlorinated-solvent plumes present since 1978 

(Mazzaferro, 1986a; Scott Beals, Sovereign Consulting, 

Inc., written commun., 2006) and an MTBE plume (fig. 4B) 

discovered in 2003 that originated from a gasoline station. 

MTBE was the most frequently detected compound in 

47 samples from 19 wells (table 13). Samples with the 

highest MTBE concentrations (greater than 10 μg/L) were 

associated with the MTBE plume, together with other gasoline 

oxygenates, including TAME and ETBE that were detected 

in 10 wells and 8 wells, respectively. Chloroform was the 

second most frequently detected compound, found in 19 wells 

(47 percent of wells sampled), but concentrations in samples 

from all but 2 of the well sites were estimated values less than 

the MRL. 

Of the 30 VOCs detected in groundwater samples, 

concentrations of two compounds—PCE and TCE—exceeded 

USEPA MCLs, which are legally enforceable drinking-water 

standards and are the highest allowed concentrations of 

contaminants in drinking water (USEPA, 2006a) (table 13). 

Eleven VOC compounds were detected in groundwater from 

PSW-1: PCE; 1,1,1-TCA; 1,1,2-trichlorotrifluoroethane 

(CFC-113); TCE; 1,1-dichloroethane (1,1-DCA); cis-1,2-

dichloroethene (cis-1,2-DCE); 1,1-dichloroethene (1,1-DCE); 

MTBE; TAME; ETBE; and chloroform. TCE exceeded the 

MCL in an untreated water sample from PSW-1. A sample 

from well WY98 had low concentrations of benzene, 

toluene, ethylbenzene, and xylene (BTEX) compounds (less 

than 0.2 μg/L); plus 26 nontarget hydrocarbon compounds 

(greater than 0.1 μg/L to about 2 μg/L); and several 

smaller non-target hydrocarbons (less than 0.1 μg/L). The 

nontarget hydrocarbons (compounds that are not on the 

USEPA Priority Pollutant List) detected include aliphatic 
Aquifer Chemistry 89

92

80*

81 82

71

90*

99

96

79*

86*

73

102

74

76

70 78

-5

0

5

10

15

0 5 10 15 20

0

5

10

15

0 5 10MAXIMUM CONTAMINANT LEVEL

FORESTED

RECHARGE END MEMBER

SEWAGE AND 

ANIMAL WASTE

15 20

INIITIAL DELTA NITROGEN-15 (δ15N) OF NITRATE

IN RECHARGE, IN PER MIL, AIR

90*

79*

102

81 76

70

99

82

73

DELTA NITROGEN-15 (δ15N) OF NITRATE,

IN PER MIL, AIR

DELTA OXYGEN-18 (δ18O,) OF NITRATE,

IN PER MIL, VIENNA MEAN OCEAN WATER

EXPLANATION

Glacial aquifer, shallow, and identifier

Glacial aquifer, deep, and identifier

Bedrock, shallow, and identifier

PSW-1

82

86

99

EXPLANATION

Glacial aquifer, shallow, and identifier

Glacial aquifer, deep, and identifier

PSW-1

*Well sample contained excess nitrogen gas

82

99

1:1

1:2

A

B

86 Bedrock, shallow, and identifier

86*

Mixing line

1:1 fractionation trend

1:2 fractionation trend

Symbol outline color

Low DOC, natural organic-matter source

High DOC, natural organic-matter source

High DOC, septic-system leachate source

SEWAGE AND 

ANIMAL WASTE

INITIAL NITRATE CONCENTRATION IN RECHARGE,

IN MILLIGRAMS PER LITER AS NITROGEN

*Well sample contained excess nitrogen gas,

 and values have been corrected for denitrification

Symbol outline color

Low DOC, natural organic-matter source

High DOC, natural organic-matter source

High DOC, septic-system leachate source

Figure 26. (A) Delta nitrogen-15 as a function of delta oxygen-18 values, and (B) initial nitrate in recharge as a function of initial 

delta nitrogen-15 values in recharge, corrected for denitrification. The lines indicate the range of fractionation trends reported for 

nitrate reduction. Mixing lines show some possible source contributions to nitrate in PSW-1 samples. (Modified from McMahon 

and others, 2008.)
90 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

Table 11. Summary of recharge temperatures determined from dissolved gas concentrations in groundwater samples from wells in 

the study area, Woodbury, Connecticut, 2003–05.—Continued

[NA, not applicable; ID, identifier; °C, degrees Celsius; bedrock wells shaded gray; cm3STP/L, cubic centimeters per liter at standard temperature and pressure, 

which is 25 degrees celsius and 1 atmosphere; <, less than; mg/L, milligrams per liter; O2, dissolved oxygen; Ar, argon; Ne, neon; N2, nitrogen gas; integrity of 

recharge temperature: 0, no/unacceptable gas measurements, estimated based on average; 1, Ar-Ne gas used to calculate (greatest integrity); 2, Ar-N2, O2 less 

than 3 mg/L; 3, Ar-N2, O2 greater than 3 mg/L (least integrity)]

Well 

ID

Sample 

date

Recharge 

temperature 

(oC)

Excess 

air 

(cm3STP/L)

Dissolved gases 

used for calculations/ 

O2 concentration

Integrity of 

recharge 

temperature

Excess 

N2

(cm3STP/L) 

Excess 

N2 Range2

(cm3STP/L) 

PSW-1 12/30/2003 7.8 1.5 Ar-Ne1 1 NA NA

PSW-1 12/30/2003 10.6 4.3 Ar-N2, O2 > 3 mg/L 2 NA 0.85–2

PSW-1 8/11/2004 8.7 1.7 Ar-Ne 1 NA NA

PSW-1 8/11/2004 9.7 2.7 Ar-N2, O2 > 3 mg/L 2 NA NA

PSW-1 11/30/2004 10.4 3.1 Ar-N2, O2 > 3 mg/L 2 NA NA

PSW-1 Average: 9.0 2.1 NA NA NA NA

WY35 12/1/2003 11.0 3.0 Ar-N2, O2 < 3 mg/L 3 NA NA

WY69 12/10/2003 7.0 2.2 Ar-Ne 1 NA NA

WY70 12/29/2003 9.0 2.2 Ar-N2, O2 > 3 mg/L 0 NA NA

WY71 12/22/2003 9.0 2.2 Ar-N2, O2 > 3 mg/L 0 NA NA

WY72 12/16/2003 9.0 2.2 Ar-N2, O2 > 3 mg/L 0 NA NA

WY73 12/17/2003 11.8 0.7 Ar-Ne 1 NA NA

WY74 11/6/2003 11.7 1.3 Ar-Ne 1 NA NA

WY75 11/13/2003 7.5 2.2 Ar-Ne 1 NA NA

WY76 11/12/2003 11.2 1.2 Ar-Ne 1 NA NA

WY77 12/9/2003 6.5 3.2 Ar-N2, O2 > 3 mg/L 2 NA NA

WY78 11/20/2003 7.9 1.8 Ar-N2, O2 > 3 mg/L 2 NA NA

WY79 11/4/2003 11.7 1.0 Ar-N2, O2 < 3 mg/L 3 3 3–4.4

WY80 11/5/2003 11.5 1.6 Ar-N2, O2 < 3 mg/L 3 1 1 - 2.4

WY81 12/2/2003 10.3 4.2 Ar-N2, O2 > 3 mg/L 2 NA NA

WY82 12/8/2003 9.4 4.2 Ar-N2, O2 > 3 mg/L 2 NA NA

WY83 11/4/2003 10.4 1.5 Ar-N2, O2 < 3 mg/L 3 1.5 2.2–3.4

WY83 8/31/2004 8.3 1.5 Ar-N2, O2 < 3 mg/L 3 1.5 1.1–1.9

WY843 11/19/2003 7.4 4.0 Ar-N2, O2 < 3 mg/L 3 1.5 0–3.2

WY853 11/19/2003 22.3 1.2 Ar-N2, O2 < 3 mg/L 3 2 1.6–7.8

WY86 3/7/2005 6.6 2.3 Ar-N2, O2 < 3 mg/L 3 0.5 NA

WY86 12/4/2003 6.9 3.8 Ar-N2, O2 < 3 mg/L 3 NA NA

WY87 12/18/2003 9.0 2.2 Ar-N2, O2 < 3 mg/L 0 NA NA

WY88 11/24/2003 10.3 2.7 Ar-N2, O2 > 3 mg/L 2 NA NA

WY893 11/2/2004 11.4 2.3 Mixed redox5 3 NA 0.3–1.3

WY90 11/9/2004 8.2 0.25 Ar-N2, O2 < 3 mg/L 3 1.4 0.5–1.4

WY91 12/14/2004 8.3 2.5 Ar-N2, O2 > 3 mg/L 2 NA NA

WY92 12/9/2004 9.4 2.6 Ar-N2, O2 > 3 mg/L 2 NA NA
Aquifer Chemistry 91

Table 11. Summary of recharge temperatures determined from dissolved gas concentrations in groundwater samples from wells in 

the study area, Woodbury, Connecticut, 2003–05.—Continued

[NA, not applicable; ID, identifier; °C, degrees Celsius; bedrock wells shaded gray; cm3STP/L, cubic centimeters per liter at standard temperature and pressure, 

which is 25 degrees celsius and 1 atmosphere; <, less than; mg/L, milligrams per liter; O2, dissolved oxygen; Ar, argon; Ne, neon; N2, nitrogen gas; integrity of 

recharge temperature: 0, no/unacceptable gas measurements, estimated based on average; 1, Ar-Ne gas used to calculate (greatest integrity); 2, Ar-N2, O2 less 

than 3 mg/L; 3, Ar-N2, O2 greater than 3 mg/L (least integrity)]

Well 

ID

Sample 

date

Recharge 

temperature 

(oC)

Excess 

air 

(cm3STP/L)

Dissolved gases 

used for calculations/ 

O2 concentration

Integrity of 

recharge 

temperature

Excess 

N2

(cm3STP/L) 

Excess 

N2 Range2

(cm3STP/L) 

WY93 10/27/2004 9.0 2.2 Ar-N2, O2 > 3 mg/L 0 NA NA

WY94 10/27/2004 9.0 2.2 Ar-N2, O2 > 3 mg/L 0 NA NA

WY96 10/9/2004 9.0 2.2 Ar-N2, O2 > 3 mg/L 0 NA NA

WY97 2/16/2005 4.3 1.8 Ar-N2, O2 > 3 mg/L 2 NA NA

WY98 10/20/2004 10.7 1.1 Ar-N2, O2 > 3 mg/L 2 NA NA

WY99 10/20/2004 9.0 2.2 Ar-N2, O2 > 3 mg/L 0 NA NA

WY100 8/3/2004 7.3 1.7 Ar-Ne 1 NA NA

WY101 8/4/2004 8.8 1.6 Ar-Ne 1 NA NA

WY102 8/5/2004 6.2 0.2 Ar-Ne 1 NA NA

WY102 11/30/2004 10.3 2.6 Ar-N2, O2 > 3 mg/L 2 NA NA

WY106 12/27/2004 7.2 7.8 Ar-N2, O2 < 3 mg/L 3 NA Assume none

Average4: 9.0 2.2

1

Assumes complete dissolution of excess air.

2

Based on uncertainty analysis, using average recharge temperature and excess air values.

3

Assumes complete dissolution of excess air.

3

Questionable measurement due to possible gas stripping.

4

Average is based on integrity of measurement (1 or 2).

5

The presence of dissolved oxygen is inconsistent with the presence of other redox indicators, as explained in Appendix 4.

hydrocarbons—alkanes, alkenes, and a few cycloalkanes. 

A chromatogram of these compounds has a profile of peaks 

similar to kerosene; a nearby home or septic-tank drainfield 

may be the source.

Several gasoline-related compounds were detected 

in samples from monitoring wells, including gasoline 

oxygenates and gasoline hydrocarbons. The MTBE plume was 

discovered in 2003 after an MTBE concentration of 300 mg/L 

was measured in a sample from WY76, for this study, and 

270 μg/L was measured in a backup community-supply 

well (Kevin Moran, United Water Connecticut, Inc., written 

commun., 2003). Concentrations of MTBE in a sample from 

PSW-1 increased by more than an order of magnitude from 

2002 to 2003, to 7.5 μg/L. During this time, reformulated 

gasoline in the Connecticut area typically accounted for 

about 6 percent MTBE by weight (600,000 mg/kg), but 

Connecticut banned its sale and use as a gasoline additive 

on or after January 1, 2004 (Connecticut Department of 

Environmental Protection, 2004). Concentrations of MTBE 

in monitoring wells at the gasoline station source were 

590,000 μg/L, and concentrations of benzene, toluene, 

ethylbenzene, and xylene were 9,200 μg/L, 36,000 μg/L, 

3,500 μg/L, 16,000 μg/L, respectively. Also, the concentration 

of isopropyl benzene was 168 μg/L, that of TAME was 

69,000 μg/L, ETBE was 2,000 μg/L, and tert-butyl alcohol 

[tert-butanol; 2-methyl-2-propanol] was 9,100 μg/L (Scott 

Beals, Sovereign Consulting, Inc., written commun., 2006). 

The duration of the gasoline spill is not known. In a sample 

collected on August 2, 2004, at well WY95, which is only 

about 180 m downgradient from the gasoline station source, 

the concentration of MTBE was 17,000 μg/L; benzene, 

0.94 μg/L; ethylbenzene, 0.12 μg/L; and toluene, below 

detection. The other gasoline oxygenates TAME, ETBE, 

and diisopropyl ether were present in WY95 samples at 

concentrations as great as 2,800 μg/L, 41 mg/L, and 0.41 μg/L, 

respectively (table 12). Concentrations of MTBE in samples 
92 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

from PSW-1 peaked at 29 μg/L on two occasions in 2005, then 

decreased to 2.1 μg/L or lower in the monthly sampling from 

December 2005 through June 2006 (Scott Beals, Sovereign 

Consulting, Inc., written commun., 2006). 

The BTEX compounds also were detected in water 

samples from the study area but at lower concentrations and 

much less frequently than other compounds in gasoline, such 

as MTBE. Benzene was detected at 9,200 μg/L at the source 

of the gasoline spill and decreased by about four orders of 

magnitude over the 180 m to WY95, the well with the highest 

concentration of gasoline oxygenates. MTBE generally did not 

occur with other gasoline compounds except when detected 

at high concentrations in this study. Likewise, MTBE was not 

detected with other gasoline-related compounds in a national 

study of VOCs, probably because of the higher solubility, 

lower capacity for sorption, and greater persistence of MTBE 

in groundwater relative to other gasoline hydrocarbons 

(Zogorski and others, 2006). Low concentrations of benzene 

and (or) toluene were detected at other wells that could 

be associated with spills of gasoline or fuel oil, including 

WY85, 88, 89, 90, 93, 94, 96, 98, and 99. The compound 

1,2,4-trimethylbenzene, which mainly is used as a gasoline 

additive, was detected in some of these same wells (WY90, 

94, 95, and 99). However, this compound also is used in 

solvents, dyes, and perfumes (Zogorski and others, 2006) and 

could be related to septic-system leachate.

Chloroform was detected in 10 of the shallow glacial 

wells and in 7 of the deep glacial wells, or 45 percent of the 

wells sampled. The high detection rate of chloroform in this 

study is consistent with other groundwater VOC studies in 

the CONN (Grady and Mullaney, 1998) and in the Nation’s 

drinking-water-supply wells (Zogorski and others, 2006). 

Potential sources of chloroform in groundwater include 

recharge of chlorinated water, direct releases such as spills 

and leaking underground storage tanks, dehalogenation 

of tetrachloromethane, bleach in septic-tank drainfields, 

and some natural sources (Ivahnenko and Barbash, 2004). 

Chloroform also is a disinfection byproduct that is produced 

during the chlorination of drinking water and wastewater 

that contains naturally occurring organic material. The 

trihalomethanes include chloroform (trichloromethane), 

bromodichloromethane, dibromochloromethane, and 

bromoform (tribromomethane), but only chloroform was 

detected in the study area. Chloroform generally was detected 

in residential and commercial areas and not in undeveloped 

areas, so its occurrence in the wells sampled is probably not 

natural. The wells in which chloroform was detected generally 

coincide with areas of water-supply distribution pipes, 

which carry chlorinated water, and septic-tank drainfields 

at commercial and residential properties with publicwater supply. In a national study of VOCs, chloroform in 

groundwater was statistically associated with the percentage 

of urban land, the number of Resource Conservation and 

Recovery Act (RCRA) hazardous-waste facilities, the 

number of gasoline storage sites, and septic drainfield density 

(Zogorski and others, 2006). Chloroform was detected at 

concentrations as great as 480 μg/L in groundwater samples 

from the source area of the gasoline spill and as great as 

350 μg/L near a grocery-store septic-tank drainfield; the 

source of chloroform at these wells may have been cleaning 

products (bleach) used for disinfection of a noncommunity 

supply well (Scott Beals, Sovereign Consulting, Inc., written 

commun., 2006). Detections of chloroform associated with 

benzene, toluene, PCE, TCE, 1,1-DCA, and CFC-13 in 

water samples from WY88 and WY35, which are completed 

in the glacial aquifer in a gravel-mined area to the west 

of PSW-1 and the Pomperaug River, indicate recharge of 

utility-supplied drinking water with wastewater under an 

area that, historically, may have been used for rinsing heavy 

equipment.Chlorinated solvents were the third most frequently 

detected class of organic (anthropogenic) compounds in this 

study area. In samples of groundwater nationwide, PCE, 

TCA, and TCE were among the top 10 most often detected 

compounds of 55 VOCs analyzed (Moran and others, 2007). 

Chlorinated solvents are used for vapor degreasing, cold 

cleaning, dry cleaning, in electronics manufacturing, and as 

septic-tank cleaners (Murphy and Morrison, 2004). Some 

of the detected solvents likely originated as spills in the 

commercial area and include PCE, TCA, CFC-113, TCE, 

and cis-1,2-DCE (Sovereign Consulting, Inc., 2004a). Most 

chlorinated solvents belong to a group of compounds that 

can form dense, nonaqueous-phase liquids (DNAPLs), which 

leave a free-phase residual that can persist in aquifers for 

many years. Concentrations of PCE and TCE, for example, 

have changed little in the water pumped from PSW-1 during 

the past 25 years. In this study, PCE was detected in 42 

percent of wells, and concentrations were highest in samples 

from several monitoring wells downgradient from the 

commercial area (table 13); concentrations of PCE in samples 

from well WY95 exceeded the USEPA MCL of 5 μg/L at 

concentrations up to 11 μg/L. TCE was detected in 33 percent 

of wells, at concentrations up to 25 μg/L; 4 wells (WY76, 

WY100, WY102, and PSW-1) exceeded the USEPA MCL 

of 5 μg/L at concentrations up to 25 μg/L. Concentrations of 

TCE exceeded the MCL in 4 of the 6 groundwater samples 

collected from PSW-1 before treatment, and ranged 4.3 to 

16 μg/L (table 12). The compound 1,4-dichlorobenzene 

(paradichlorobenzene, or p-DCB) has some use as a solvent 

but is primarily used as a fumigant pesticide and will be 

discussed in the section on pesticides. 

Although the strengths of chlorinated solvents at the 

source are not known, samples collected during an aquifer 

pumping test in March 2005 from a non-USGS well 

located 9 m northwest of WY95 for treatment of the MTBE 

contamination (Scott Beals, Sovereign Consulting, Inc., 

written commun., 2005) contained high concentrations of 

chlorinated solvents when the pumping rate was doubled. 

Concentrations in groundwater samples were 13.4 μg/L for 

PCE and 8.1 μg/L for TCE at a dry cleaner, 470 μg/L for TCA 

at the recovery well, and 410 μg/L for TCE and 180 μg/L for 

TCA at well NW19D. Groundwater at the source area was 

pumped into an air-stripping treatment system from June 21, 
Aquifer Chemistry 93

Table 12. Concentrations of volatile organic compounds and pesticides detected in groundwater samples from wells in the Woodbury study area, and from selected wells elsewhere in the Pomperaug Basin, Connecticut, 2002–05.—Continued[ID, identifier; concentrations in micrograms per liter; <, less than; E, estimated value below minimum reporting level; --, not measured; VOC, volatile organic compound; red values indicate detectable concentrations; bedrock wells shaded gray]

Compound 

group

Solvents

Well 

ID

Sample 

date

Perchloroethene 

(PCE)

1,1,1-

Trichloroethane 

(TCA)

Dichloro 

difluoromethane 

(CFC-12)

1,1,2-

Trichloro1,2,2-

trifluoroethane 

(CFC-113)

Trichloroethene 

(TCE)

1,1-

Dichloroethane 

(DCA)

cis-1,2-

Dichloroethene 

(1,2-DCE)

1,1-

Dichloroethene 

(1,1-DCE)

Chloroethane Chloro- methane Vinyl chlor- ide Carbon tetra- chlor- ide Methyl ethyl ketone (MEK) Ace- tone Tetra- hydro- furan (THF)

PSW-1 10/23/2002 0.67 17 <0.18 1.1 16 E0.05 0.17 0.42 <0.12 <0.17 <0.11 <0.06 <5 <7 <2.2PSW-1 12/30/2003 0.54 6.8 <0.18 0.43 7.9 E0.04 0.16 E0.09 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2PSW-1 7/23/2004 0.5 3.5 <0.18 0.39 4.3 E0.03 0.16 E0.06 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2PSW-1 8/11/2004 0.51 3.3 <0.18 0.41 4.5 <0.035 0.14 E0.08 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2PSW-1 11/30/2004 0.48 5.9 <0.18 0.59 7 E0.04 0.15 E0.07 <0.12 <0.17 <0.08 <0.06 <2 <6 <1PSW-1 8/5/2005 0.31 4.5 <0.18 0.47 5.2 E0.03 E0.07 E0.04 <0.12 <0.17 <0.08 <0.06 <2 <6 <1WY35 12/1/2003 E0.03 0.6 <0.18 E0.05 0.6 E0.06 <0.024 <0.024 <0.12 <0.17 <0.06 <0.06 <4 <6 E0.77WY35 9/16/2004 <0.06 0.13 <0.18 <0.038 0.14 <0.035 <0.024 <0.024 <0.12 <0.17 <0.06 <0.06 <4 <6 E1.2WY35 2/18/2005 <0.03 0.42 <0.18 <0.038 0.31 E0.02 <0.024 <0.024 <0.12 <0.17 <0.08 <0.06 <2 <6 <1WY35 11/29/2005 <0.03 0.44 <0.18 <0.038 0.3 E0.03 <0.024 <0.024 <0.12 <0.17 <0.08 <0.06 <2 <6 E0.75WY69 12/10/2003 <0.06 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2WY70 12/29/2003 0.1 E0.03 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2WY71 12/22/2003 E0.07 E0.03 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2WY71 7/27/2004 E0.03 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 E0.09 <0.17 <0.06 <0.06 <4 <6 <2.2WY71 1/7/2005 E0.04 E0.02 <0.18 <0.038 <0.038 <0.035 E0.01 <0.024 <0.12 <0.17 <0.08 <0.06 <2 <6 <1WY71 5/18/2005 E0.02 E0.01 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.08 <0.06 <2 <6 <1WY72 12/16/2003 E0.04 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2WY73 12/17/2003 0.14 E0.04 <0.18 <0.038 E0.03 E0.05 E0.06 <0.024 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2WY74 11/6/2003 0.13 E0.03 <0.18 <0.038 E0.04 E0.06 E0.10 <0.024 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2WY74 7/28/2004 E0.07 E0.02 <0.18 <0.038 E0.03 E0.09 E0.04 <0.024 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2WY74 1/10/2005 E0.07 E0.03 <0.18 <0.038 E0.03 E0.07 E0.04 <0.024 <0.12 <0.17 <0.08 <0.06 <2 <6 <1WY74 6/15/2005 E0.06 E0.02 <0.18 <0.038 E0.03 E0.03 E0.03 <0.024 <0.12 E0.03 <0.08 <0.06 <2 <6 <1
94 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06 Table 12. Concentrations of volatile organic compounds and pesticides detected in groundwater samples from wells in the Woodbury study area, and from selected wells elsewhere in the Pomperaug Basin, Connecticut, 2002–05.—Continued [ID, identifier; concentrations in micrograms per liter; <, less than; E, estimated value below minimum reporting level; --, not measured; VOC, volatile organic compound; red values indicate detectable concentrations; bedrock wells shaded gray] Compound group Solvents Well ID Sample date Per- chloro- ethene (PCE) 1,1,1- Tri- chloro- ethane (TCA) Di- chloro difluoro- methane (CFC-12) 1,1,2- Tri- chloro- 1,2,2- tri- fluoro- ethane (CFC-113) Tri- chloro- ethene (TCE) 1,1- Di- chloro- ethane (DCA) cis-1,2- Di- chloro- ethene (1,2-DCE) 1,1- Dichloro- ethene (1,1-DCE) Chloro- ethane Chloro- methane Vinyl chlor- ide Carbon tetra- chlor- ide Methyl ethyl ketone (MEK) Ace- tone Tetra- hydro- furan (THF) WY75 11/13/2003 <0.06 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2 WY76 11/12/2003 2.3 18 <0.18 0.87 21 E0.06 0.89 0.25 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2 WY76 7/26/2004 2.6 6.2 <0.18 0.66 7.9 E0.04 0.45 E0.07 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2 WY76 1/4/2005 1.7 16 <0.18 2 19 0.17 0.55 0.18 <0.12 <0.17 <0.08 <0.06 <2 <6 <1 WY76 6/14/2005 1.8 5.9 <0.18 0.72 7.8 E0.04 0.18 E0.05 <0.12 <0.17 <0.08 <0.06 <2 <6 <1 WY77 12/9/2003 <0.06 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2 WY78 11/20/2003 <0.06 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.06 <0.06 <2.2 WY78 7/28/2004 <0.06 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2 WY78 1/11/2005 <0.03 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.08 <0.06 <2 <6 <1 WY78 5/24/2005 <0.03 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.08 <0.06 <2 <6 <1 WY79 11/4/2003 <0.06 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2 WY79 7/29/2004 <0.06 <0.032 <0.18 <0.038 <0.038 E0.04 <0.024 <0.024 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2 WY79 1/31/2005 <0.03 <0.032 <0.18 <0.038 E0.01 E0.03 <0.024 <0.024 <0.12 <0.17 <0.08 <0.06 <2 <6 <1 WY79 8/5/2005 <0.03 <0.032 <0.18 <0.038 <0.038 E0.02 <0.024 <0.024 <0.12 <0.17 <0.08 <0.06 <2 <6 <1 WY80 11/5/2003 <0.06 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2 WY80 8/30/2004 <0.06 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2 WY80 1/11/2005 <0.03 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.08 <0.06 <2 <6 <1 WY80 5/17/2005 <0.03 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.08 <0.06 <2 <6 <1 WY81 12/2/2003 <0.06 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2 WY81 7/29/2004 <0.06 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2 WY81 1/13/2005 <0.03 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.08 <0.06 <2 <6 <1

WY81 5/4/2005 <0.03 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 E0.04 <0.08 <0.06 <2 <6 <1
Aquifer Chemistry 95

Table 12. Concentrations of volatile organic compounds and pesticides detected in groundwater samples from wells in the Woodbury study area, and from selected wells elsewhere in the Pomperaug Basin, Connecticut, 2002–05.—Continued[ID, identifier; concentrations in micrograms per liter; <, less than; E, estimated value below minimum reporting level; --, not measured; VOC, volatile organic compound; red values indicate detectable concentrations; bedrock wells shaded gray]

Compound 

group

Solvents

Well 

ID

Sample 

date

Perchloroethene 

(PCE)

1,1,1-

Trichloroethane 

(TCA)

Dichloro 

difluoromethane 

(CFC-12)

1,1,2-

Trichloro1,2,2-

trifluoroethane 

(CFC-113)

Trichloroethene 

(TCE)

1,1-

Dichloroethane 

(DCA)

cis-1,2-

Dichloroethene 

(1,2-DCE)

1,1-

Dichloroethene 

(1,1-DCE)

Chloroethane Chloro- methane Vinyl chlor- ide Carbon tetra- chlor- ide Methyl ethyl ketone (MEK) Ace- tone Tetra- hydro- furan (THF)

WY82 12/8/2003 <0.06 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2WY83 11/4/2003 <0.06 <0.032 <0.18 <0.038 <0.038 0.21 <0.024 <0.024 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2WY83 8/31/2004 <0.06 <0.032 <0.18 <0.038 <0.038 0.16 <0.024 <0.024 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2WY83 1/4/2005 <0.03 <0.032 <0.18 <0.038 <0.038 0.17 <0.024 <0.024 <0.12 <0.17 <0.08 <0.06 <2 <6 <1WY83 4/29/2005 <0.03 <0.032 <0.18 <0.038 <0.038 0.17 <0.024 <0.024 <0.12 <0.17 <0.08 <0.06 <2 <6 <1WY84 11/18/2003 <0.06 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2WY85 11/19/2003 <0.06 <0.032 <0.18 <0.038 0.11 0.12 0.14 <0.024 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2WY85 8/10/2004 <0.06 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2WY85 2/1/2005 <0.03 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.08 <0.06 <2 <6 E0.29WY85 6/16/2005 <0.03 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 E0.09 <0.08 <0.06 <2 <6 <1WY87 12/18/2003 <0.06 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2WY88 11/24/2003 E0.09 2.6 <0.18 0.22 2.8 E0.07 <0.024 E0.06 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2WY88 9/14/2004 E0.06 1.9 <0.18 E0.2 2.1 E0.04 <0.024 E0.03 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2WY89 10/26/2004 E0.05 <0.032 E0.12 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.08 <0.06 <2 <6 <1WY90 11/9/2004 0.37 <0.032 E0.05 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.08 <0.06 <2 <6 <1WY90 5/26/2005 0.11 <0.032 E0.06 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 E0.07 <0.08 <0.06 <2 <6 <1WY91 8/19/2004 <0.06 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2WY92 8/23/2004 <0.06 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2WY92 12/9/2004 <0.03 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.08 <0.06 <2 <6 <1WY92 5/2/2005 <0.03 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.08 <0.06 <2 <6 <1WY93 8/24/2004 <0.06 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2WY94 10/14/2004 <0.03 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.08 <0.06 <2 <6 <1
96 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06 Table 12. Concentrations of volatile organic compounds and pesticides detected in groundwater samples from wells in the Woodbury study area, and from selected wells elsewhere in the Pomperaug Basin, Connecticut, 2002–05.—Continued [ID, identifier; concentrations in micrograms per liter; <, less than; E, estimated value below minimum reporting level; --, not measured; VOC, volatile organic compound; red values indicate detectable concentrations; bedrock wells shaded gray] Compound group Solvents Well ID Sample date Per- chloro- ethene (PCE) 1,1,1- Tri- chloro- ethane (TCA) Di- chloro difluoro- methane (CFC-12) 1,1,2- Tri- chloro- 1,2,2- tri- fluoro- ethane (CFC-113) Tri- chloro- ethene (TCE) 1,1- Di- chloro- ethane (DCA) cis-1,2- Di- chloro- ethene (1,2-DCE) 1,1- Dichloro- ethene (1,1-DCE) Chloro- ethane Chloro- methane Vinyl chlor- ide Carbon tetra- chlor- ide Methyl ethyl ketone (MEK) Ace- tone Tetra- hydro- furan (THF) WY94 2/8/2005 <0.03 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.08 <0.06 <2 <6 <1 WY94 5/3/2005 <0.03 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.08 <0.06 <2 <6 <1 WY95 8/2/2004 11 E0.04 <0.18 <0.038 2.4 <0.035 2.2 <0.024 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2 WY95 2/1/2005 E6.5 <3.2 <18 <3.8 E2.6 <3.5 E1.8 <2.4 <12 <17 <8 <6 <200 <600 <100 WY95 6/16/2005 10 <0.32 <1.8 E1.8 2 <0.35 E0.8 <0.24 <1.2 <1.7 <0.8 <0.6 <20 <60 <10 WY96 11/4/2004 <0.03 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.08 <0.06 <2 <6 <1 WY96 2/9/2005 <0.03 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.08 <0.06 <2 <6 <1 WY96 6/15/2005 <0.03 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 E0.2 <0.08 <0.06 E0.5 E1.8 <1 WY97 2/15/2005 <0.03 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.08 <0.06 <2 <6 <1 WY98 8/25/2004 <0.06 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2 WY99 10/21/2004 <0.03 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.08 <0.06 <2 <6 <1 WY99 2/3/2005 <0.03 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.08 <0.06 <2 <6 <1 WY99 5/23/2005 <0.03 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 E0.06 <0.08 <0.06 <2 <6 <1 WY100 8/3/2004 1.8 19 <0.18 2.2 15 E0.08 0.57 0.25 <0.12 <0.17 <0.06 E0.03 <4 <6 <2.2 WY101 8/4/2004 0.75 E0.04 <0.18 <0.038 0.29 <0.035 0.13 <0.024 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2 WY102 8/5/2004 1.7 22 <0.18 2.7 25 0.16 0.53 0.35 <0.12 <0.17 <0.06 <0.06 <4 <6 <2.2 WY102 11/30/2004 1.4 21 <0.18 2.8 25 0.65 0.45 0.34 <0.12 <0.17 <0.08 E0.04 <2 <6 <1 WY102 5/24/2005 0.52 13 <0.18 1.4 16 0.23 0.23 0.15 <0.12 <0.17 E0.04 <0.06 <2 <6 <1 WY106 12/27/2004 <0.03 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.08 <0.06 <2 <6 <1 WY651 6/6/2002 E0.04 E0.04 <0.18 <0.06 <0.038 <0.035 <0.038 <0.04 <0.12 <0.17 <0.11 <0.06 <5 <7 <2.2 WY651 4/11/2005 E0.01 <0.032 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.08 <0.06 <2 <6 <1

WY651 11/9/2005 <0.03 E0.01 <0.18 <0.038 <0.038 <0.035 <0.024 <0.024 <0.12 <0.17 <0.08 <0.06 <2 <6 <1SB1201 11/6/2002 <0.027 <0.032 <0.18 <0.06 <0.038 <0.035 <0.038 <0.04 <0.12 <0.17 <0.11 <0.06 <5 <7 <2.2
Aquifer Chemistry 97

Table 12. Concentrations of volatile organic compounds and pesticides detected in groundwater samples from wells in the Woodbury study area, and from selected wells elsewhere in the Pomperaug Basin, Connecticut, 2002–05.—Continued[ID, identifier; concentrations in micrograms per liter; <, less than; E, estimated value below minimum reporting level; --, not measured; VOC, volatile organic compound; red values indicate detectable concentrations; bedrock wells shaded gray]

Compound 

group Gasoline compounds

Well 

ID

Sample 

date

Methyl-tertbutyl 

ether 

(MTBE)

tertAmyl 

methyl 

ether 

(TAME)

Ethyl 

-tertbutyl 

ether 

(ETBE)

Diisopropyl 

ether Benzene Toluene Ethyl benzene

1-Ethyl-2-

methyl 

benzene 

(o-ethyl 

toluene)

o-xylene m- & p- xylene Isopropyl benzene

1,2,4-

Trimethyl 

benzene

PSW-1 10/23/2002 0.6 <0.08 <0.05 <0.1 <0.035 <0.05 <0.03 <0.06 <0.07 <0.06 <0.06 <0.056

PSW-1 12/30/2003 7.5 0.12 E0.06 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056PSW-1 7/23/2004 7.8 0.94 0.24 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056PSW-1 8/11/2004 8.1 0.91 0.21 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056PSW-1 11/30/2004 16 2.3 0.26 <0.1 <0.021 <0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056PSW-1 8/5/2005 16 2.3 E0.22 <0.1 <0.021 <0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY35 12/1/2003 <0.17 <0.08 <0.05 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY35 9/16/2004 <0.17 <0.08 <0.05 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY35 2/18/2005 <0.1 <0.04 <0.03 <0.1 <0.021 <0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY35 11/29/2005 <0.1 <0.04 <0.03 <0.1 <0.021 <0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY69 12/10/2003 0.22 <0.08 <0.05 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY70 12/29/2003 0.68 E0.02 <0.05 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY71 12/22/2003 0.84 <0.08 <0.05 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY71 7/27/2004 0.4 <0.08 <0.05 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY71 1/7/2005 6.5 0.89 E0.02 <0.1 <0.021 <0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY71 5/18/2005 1.5 0.18 <0.03 <0.1 <0.021 <0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY72 12/16/2003 0.26 <0.08 <0.05 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY73 12/17/2003 0.37 <0.08 <0.05 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY74 11/6/2003 0.31 <0.08 <0.05 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY74 7/28/2004 1.2 <0.08 <0.05 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY74 1/10/2005 2.3 0.15 <0.03 <0.1 <0.021 <0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY74 6/15/2005 33 3.6 0.12 <0.1 <0.021 E0.009 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056
98 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06 Table 12. Concentrations of volatile organic compounds and pesticides detected in groundwater samples from wells in the Woodbury study area, and from selected wells elsewhere in the Pomperaug Basin, Connecticut, 2002–05.—Continued [ID, identifier; concentrations in micrograms per liter; <, less than; E, estimated value below minimum reporting level; --, not measured; VOC, volatile organic compound; red values indicate detectable concentrations; bedrock wells shaded gray] Compound group Gasoline compounds Well ID Sample date Methyl-tert- butyl ether (MTBE) tert- Amyl methyl ether (TAME) Ethyl 

-tertbutyl 

ether 

(ETBE)

Diisopropyl 

ether Benzene Toluene Ethyl benzene

1-Ethyl-2-

methyl 

benzene 

(o-ethyl 

toluene)

o-xylene m- & p- xylene Isopropyl benzene

1,2,4-

Trimethyl 

benzene

WY75 11/13/2003 <0.17 <0.08 <0.05 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056

WY76 11/12/2003 300 15 0.9 <0.1 E0.02 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY76 7/26/2004 53 E0.06 1.9 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY76 1/4/2005 0.93 <0.04 1 <0.1 E0.01 <0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY76 6/14/2005 60 0.13 3 <0.1 <0.021 <0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY77 12/9/2003 <0.17 <0.08 <0.05 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY78 11/20/2003 <0.17 <0.08 <0.05 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY78 7/28/2004 <0.17 <0.08 <0.05 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY78 1/11/2005 <0.1 <0.04 <0.03 <0.1 <0.021 <0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY78 5/24/2005 <0.1 <0.04 <0.03 <0.1 <0.021 <0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY79 11/4/2003 E0.1 <0.08 <0.05 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY79 7/29/2004 0.29 <0.08 <0.05 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY79 1/31/2005 0.24 <0.04 <0.03 <0.1 <0.021 <0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY79 8/5/2005 0.19 <0.04 <0.03 <0.1 <0.021 <0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY80 11/5/2003 <0.17 <0.08 <0.05 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY80 8/30/2004 <0.17 <0.08 <0.05 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY80 1/11/2005 <0.1 <0.04 <0.03 <0.1 <0.021 <0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY80 5/17/2005 <0.1 <0.04 <0.03 <0.1 <0.021 <0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY81 12/2/2003 <0.17 <0.08 <0.05 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY81 7/29/2004 <0.17 <0.08 <0.05 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY81 1/13/2005 <0.1 <0.04 <0.03 <0.1 <0.021 <0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056
Aquifer Chemistry 99

Table 12. Concentrations of volatile organic compounds and pesticides detected in groundwater samples from wells in the Woodbury study area, and from selected wells elsewhere in the Pomperaug Basin, Connecticut, 2002–05.—Continued[ID, identifier; concentrations in micrograms per liter; <, less than; E, estimated value below minimum reporting level; --, not measured; VOC, volatile organic compound; red values indicate detectable concentrations; bedrock wells shaded gray]

Compound 

group Gasoline compounds

Well 

ID

Sample 

date

Methyl-tertbutyl 

ether 

(MTBE)

tertAmyl 

methyl 

ether 

(TAME)

Ethyl 

-tertbutyl 

ether 

(ETBE)

Diisopropyl 

ether Benzene Toluene Ethyl benzene

1-Ethyl-2-

methyl 

benzene 

(o-ethyl 

toluene)

o-xylene m- & p- xylene Isopropyl benzene

1,2,4-

Trimethyl 

benzene

WY81 5/4/2005 0.22 <0.04 <0.03 <0.1 <0.021 <0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056

WY82 12/8/2003 <0.17 <0.08 <0.05 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY83 11/4/2003 <0.17 <0.08 <0.05 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY83 8/31/2004 <0.17 <0.08 <0.05 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY83 1/4/2005 <0.1 <0.04 <0.03 <0.1 <0.021 <0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY83 4/29/2005 <0.1 <0.04 <0.03 <0.1 <0.021 <0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY84 11/18/2003 E0.09 <0.08 <0.05 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY85 11/19/2003 8.4 0.24 <0.05 <0.1 E0.03 <0.05 E0.02 0.017 <0.038 <0.06 <0.038 <0.056WY85 8/10/2004 0.44 <0.08 <0.05 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY85 2/1/2005 0.97 E0.06 E0.02 <0.1 <0.021 <0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY85 6/16/2005 1.7 0.125 <0.03 <0.1 E0.01 E0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY87 12/18/2003 <0.17 <0.08 <0.05 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY88 11/24/2003 E0.09 <0.08 <0.05 <0.1 E0.02 E0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY88 9/14/2004 E0.2 <0.08 <0.05 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY89 10/26/2004 0.13 <0.04 <0.03 <0.1 <0.021 E0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY90 11/9/2004 0.5 <0.04 <0.03 <0.1 <0.021 <0.02 <0.03 <0.06 <0.038 <0.06 <0.038 0.11WY90 5/26/2005 0.25 <0.04 <0.03 <0.1 E0.02 E0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY91 8/19/2004 <0.17 <0.08 <0.05 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY92 8/23/2004 <0.17 <0.08 <0.05 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY92 12/9/2004 <0.1 <0.04 <0.03 <0.1 <0.021 <0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY92 5/2/2005 <0.1 <0.04 <0.03 <0.1 <0.021 <0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056
100 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06 Table 12. Concentrations of volatile organic compounds and pesticides detected in groundwater samples from wells in the Woodbury study area, and from selected wells elsewhere in the Pomperaug Basin, Connecticut, 2002–05.—Continued [ID, identifier; concentrations in micrograms per liter; <, less than; E, estimated value below minimum reporting level; --, not measured; VOC, volatile organic compound; red values indicate detectable concentrations; bedrock wells shaded gray] Compound group Gasoline compounds Well ID Sample date Methyl-tert- butyl ether (MTBE) tert- Amyl methyl ether (TAME) Ethyl 

-tertbutyl 

ether 

(ETBE)

Diisopropyl 

ether Benzene Toluene Ethyl benzene

1-Ethyl-2-

methyl 

benzene 

(o-ethyl 

toluene)

o-xylene m- & p- xylene Isopropyl benzene

1,2,4-

Trimethyl 

benzene

WY93 8/24/2004 <0.17 <0.08 <0.05 <0.1 E0.02 E0.04 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056

WY94 10/14/2004 <0.1 <0.04 <0.03 <0.1 <0.021 <0.02 <0.03 <0.06 <0.038 <0.06 <0.038 E0.02WY94 2/8/2005 <0.1 <0.04 <0.03 <0.1 E0.03 E0.05 <0.03 <0.06 <0.038 E0.02 <0.038 <0.056WY94 5/3/2005 <0.1 <0.04 <0.03 <0.1 <0.021 <0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY95 8/2/2004 17,000 2,800 41 0.41 0.94 <0.05 0.12 <0.06 <0.038 <0.06 E0.03 E0.04WY95 2/1/2005 2,100 310 E5.4 <10 <2.1 <2 <3 <6 <3.8 <6 <3.8 <5.6WY95 6/16/2005 1,300 220 3.3 <1 <0.21 <0.2 <0.3 <0.6 <0.38 <0.6 <0.38 <0.56WY96 11/4/2004 <0.1 <0.04 <0.03 <0.1 <0.021 <0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY96 2/9/2005 <0.1 <0.04 <0.03 <0.1 <0.021 E0.015 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY96 6/15/2005 <0.1 <0.04 <0.03 <0.1 E0.03 E0.039 <0.03 <0.06 E0.02 E0.02 <0.038 <0.056WY97 2/15/2005 <0.1 <0.04 <0.03 <0.1 <0.021 <0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY98 8/25/2004 <0.17 <0.08 <0.05 <0.1 0.16 0.12 E0.041 <0.06 E0.03 E0.06 <0.038 <0.056WY99 10/21/2004 <0.1 <0.04 <0.03 <0.1 E0.02 E0.018 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY99 2/3/2005 <0.1 <0.04 <0.03 <0.1 E0.06 E0.073 E0.01 <0.06 E0.03 E0.04 <0.038 E0.02WY99 5/23/2005 <0.1 <0.04 <0.03 <0.1 E0.01 E0.028 <0.03 <0.06 <0.038 E0.02 <0.038 <0.056WY100 8/3/2004 5 0.13 1.1 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY101 8/4/2004 8.8 0.31 <0.05 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY102 8/5/2004 0.39 <0.08 1 <0.1 <0.021 <0.05 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY102 11/30/2004 0.3 <0.04 0.62 <0.1 E0.02 <0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY102 5/24/2005 0.58 <0.04 0.51 <0.1 <0.021 <0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY106 12/27/2004 <0.1 <0.04 <0.03 <0.1 <0.021 E0.060 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056WY651 6/6/2002 0.19 <0.08 <0.05 <0.1 <0.035 <0.05 <0.03 <0.06 <0.07 <0.06 <0.06 <0.056
Aquifer Chemistry 101

Table 12. Concentrations of volatile organic compounds and pesticides detected in groundwater samples from wells in the Woodbury study area, and from selected wells elsewhere in the Pomperaug Basin, Connecticut, 2002–05.—Continued[ID, identifier; concentrations in micrograms per liter; <, less than; E, estimated value below minimum reporting level; --, not measured; VOC, volatile organic compound; red values indicate detectable concentrations; bedrock wells shaded gray]

Compound 

group Gasoline compounds

Well 

ID

Sample 

date

Methyl-tertbutyl 

ether 

(MTBE)

tertAmyl 

methyl 

ether 

(TAME)

Ethyl 

-tertbutyl 

ether 

(ETBE)

Diisopropyl 

ether Benzene Toluene Ethyl benzene

1-Ethyl-2-

methyl 

benzene 

(o-ethyl 

toluene)

o-xylene m- & p- xylene Isopropyl benzene

1,2,4-

Trimethyl 

benzene

WY651 4/11/2005 0.63 E0.04 <0.03 <0.1 <0.021 <0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056

WY651 11/9/2005 0.57 E0.06 <0.03 <0.1 <0.021 <0.02 <0.03 <0.06 <0.038 <0.06 <0.038 <0.056SB1201 11/6/2002 E0.08 <0.08 <0.05 <0.1 <0.035 <0.05 <0.03 <0.06 <0.07 <0.06 <0.06 0.11

1Glacial, domestic-supply well (major aquifer study) in the Pomperaug Basin.
102 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06 Table 12. Concentrations of volatile organic compounds and pesticides detected in groundwater samples from wells in the Woodbury study area, and from selected wells elsewhere in the Pomperaug Basin, Connecticut, 2002–05.—Continued [ID, identifier; concentrations in micrograms per liter; <, less than; E, estimated value below minimum reporting level; --, not measured; VOC, volatile organic compound; red values indicate detectable concentrations; bedrock wells shaded gray] Compound group Other VOC compounds Pesticides Well ID Sample date 1,4- Dichloro- benzene (p-DCB) Carbon disulfide (CS2

)

Chloroform

Total 

VOC 

detects

4-Chloro2-methyl 

phenol

Atrazine

Deethyl 

atrazine 

(CIAT)

Fipronil Fipronil sulfide Prometon Simazine Total pesticide detects

PSW-1 10/23/2002 <0.05 <0.07 E0.03 9 <0.0056 E0.002 E0.002 <0.007 <0.005 E0.005 0.008 4PSW-1 12/30/2003 <0.034 <0.038 E0.07 10 <0.0056 <0.007 <0.006 <0.016 <0.013 E0.005 0.0064 2PSW-1 7/23/2004 <0.034 <0.038 E0.09 11 <0.0057 <0.007 <0.006 E0.006 E0.007 <0.005 0.008 3PSW-1 8/11/2004 <0.034 <0.038 E0.08 10 <0.0057 <0.007 <0.006 <0.016 <0.013 0.006 0.008 2PSW-1 11/30/2004 <0.034 <0.038 E0.07 11 -- -- -- -- -- -- -- --PSW-1 8/5/2005 <0.034 <0.038 E0.03 11 -- -- -- -- -- -- -- --WY35 12/1/2003 <0.034 E0.04 E0.02 8 -- -- -- -- -- -- -- --WY35 9/16/2004 <0.034 <0.038 <0.024 4 -- -- -- -- -- -- -- --WY35 2/18/2005 <0.034 <0.038 E0.02 4 -- -- -- -- -- -- -- --WY35 11/29/2005 <0.034 E0.039 E0.02 6 -- -- -- -- -- -- -- --WY69 12/10/2003 <0.034 <0.038 E0.04 2 <0.0056 <0.007 <0.006 <0.016 <0.013 <0.005 E0.003 1WY70 12/29/2003 <0.034 <0.038 E0.02 5 <0.0056 <0.007 <0.006 <0.016 <0.013 <0.005 <0.005 0WY71 12/22/2003 <0.034 <0.038 E0.06 4 <0.0056 <0.007 <0.006 <0.016 <0.013 0.1 <0.005 1WY71 7/27/2004 <0.034 <0.038 0.13 4 -- -- -- -- -- -- -- --WY71 1/7/2005 <0.034 <0.038 E0.03 7 -- -- -- -- -- -- -- --WY71 5/18/2005 <0.034 <0.038 0.17 6 -- -- -- -- -- -- -- --WY72 12/16/2003 <0.034 <0.038 E0.02 3 <0.0056 <0.007 <0.006 <0.016 <0.013 <0.005 0.0085 0WY73 12/17/2003 <0.034 <0.038 0.48 7 <0.0056 <0.007 <0.006 <0.016 <0.013 <0.005 <0.005 0WY74 11/6/2003 <0.034 <0.038 0.45 7 <0.0056 <0.007 <0.006 E0.006 E0.003 <0.005 <0.005 2WY74 7/28/2004 <0.034 <0.038 0.39 7 -- -- -- -- -- -- -- --WY74 1/10/2005 <0.034 <0.038 0.22 8 -- -- -- -- -- -- -- --WY74 6/15/2005 <0.034 <0.038 E0.04 11 -- -- -- -- -- -- -- --WY75 11/13/2003 <0.034 <0.038 <0.024 0 <0.0056 <0.007 <0.006 <0.016 <0.013 <0.005 0.018 1
Aquifer Chemistry 103

Table 12. Concentrations of volatile organic compounds and pesticides detected in groundwater samples from wells in the Woodbury study area, and from selected wells elsewhere in the Pomperaug Basin, Connecticut, 2002–05.—Continued[ID, identifier; concentrations in micrograms per liter; <, less than; E, estimated value below minimum reporting level; --, not measured; VOC, volatile organic compound; red values indicate detectable concentrations; bedrock wells shaded gray]

Compound 

group Other VOC compounds Pesticides

Well 

ID

Sample 

date

1,4-

Dichlorobenzene 

(p-DCB)

Carbon 

disulfide 

(CS2)

Chloroform

Total 

VOC 

detects

4-Chloro2-methyl 

phenol

Atrazine

Deethyl 

atrazine 

(CIAT)

Fipronil Fipronil sulfide Prometon Simazine Total pesticide detects

WY76 11/12/2003 <0.034 <0.038 E0.04 11 <0.0056 <0.007 <0.006 <0.016 <0.013 0.013 E0.005 2WY76 7/26/2004 <0.034 <0.038 E0.04 9 -- -- -- -- -- -- -- --WY76 1/4/2005 <0.034 <0.038 E0.04 11 -- -- -- -- -- -- -- --WY76 6/14/2005 <0.034 <0.038 E0.07 9 -- -- -- -- -- -- -- --WY77 12/9/2003 <0.034 <0.038 E0.05 1 <0.0056 <0.007 <0.006 <0.016 <0.013 <0.005 <0.005 0WY78 11/20/2003 <0.034 <0.038 <0.024 0 <0.0056 <0.007 <0.006 <0.016 <0.013 <0.005 <0.005 0WY78 7/28/2004 <0.034 <0.038 <0.024 0 -- -- -- -- -- -- -- --WY78 1/11/2005 <0.034 0.51 <0.024 1 -- -- -- -- -- -- -- --WY78 5/24/2005 <0.034 <0.038 <0.024 0 -- -- -- -- -- -- -- --WY79 11/4/2003 <0.034 <0.038 <0.024 1 -- -- -- -- -- -- -- --WY79 7/29/2004 <0.034 <0.038 <0.024 2 -- -- -- -- -- -- -- --WY79 1/31/2005 E0.03 <0.038 E0.009 5 -- -- -- -- -- -- -- --WY79 8/5/2005 E0.02 <0.038 <0.024 3 -- -- -- -- -- -- -- --WY80 11/5/2003 <0.034 <0.038 <0.024 0 -- -- -- -- -- -- -- --WY80 8/30/2004 <0.034 <0.038 <0.024 0 -- -- -- -- -- -- -- --WY80 1/11/2005 <0.034 <0.038 <0.024 0 -- -- -- -- -- -- -- --WY80 5/17/2005 <0.034 <0.038 <0.024 0 -- -- -- -- -- -- -- --WY81 12/2/2003 <0.034 <0.038 E0.09 1 <0.0056 <0.007 <0.006 <0.016 <0.013 0.009 <0.005 1WY81 7/29/2004 <0.034 <0.038 E0.04 1 -- -- -- -- -- -- -- --WY81 1/13/2005 <0.034 <0.038 E0.05 1 -- -- -- -- -- -- -- --WY81 5/4/2005 <0.034 <0.038 0.23 2 -- -- -- -- -- -- -- --WY82 12/8/2003 <0.034 <0.038 E0.04 1 <0.0056 <0.007 <0.006 <0.016 <0.013 0.01 <0.005 1
104 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06 Table 12. Concentrations of volatile organic compounds and pesticides detected in groundwater samples from wells in the Woodbury study area, and from selected wells elsewhere in the Pomperaug Basin, Connecticut, 2002–05.—Continued [ID, identifier; concentrations in micrograms per liter; <, less than; E, estimated value below minimum reporting level; --, not measured; VOC, volatile organic compound; red values indicate detectable concentrations; bedrock wells shaded gray] Compound group Other VOC compounds Pesticides Well ID Sample date 1,4- Dichloro- benzene (p-DCB) Carbon disulfide (CS2

)

Chloroform

Total 

VOC 

detects

4-Chloro2-methyl 

phenol

Atrazine

Deethyl 

atrazine 

(CIAT)

Fipronil Fipronil sulfide Prometon Simazine Total pesticide detects

WY83 11/4/2003 <0.034 <0.038 <0.024 1 -- -- -- -- -- -- -- --WY83 8/31/2004 <0.034 <0.038 <0.024 1 -- -- -- -- -- -- -- --WY83 1/4/2005 <0.034 E0.015 <0.024 2 -- -- -- -- -- -- -- --WY83 4/29/2005 <0.034 <0.038 <0.024 1 -- -- -- -- -- -- -- --WY84 11/18/2003 <0.034 <0.038 <0.024 1 <0.0056 <0.007 <0.006 <0.016 <0.013 <0.005 <0.005 0WY85 11/19/2003 0.31 <0.038 <0.024 9 E0.009 <0.007 <0.006 <0.016 <0.013 0.014 <0.005 2WY85 8/10/2004 E0.06 <0.038 <0.024 2 -- -- -- -- -- -- -- --WY85 2/1/2005 E0.10 <0.038 <0.024 5 -- -- -- -- -- -- -- --WY85 6/16/2005 E0.06 <0.038 <0.024 5 -- -- -- -- -- -- -- --WY87 12/18/2003 <0.034 <0.038 <0.024 0 <0.0056 <0.007 <0.006 <0.016 <0.013 <0.005 <0.005 0WY88 11/24/2003 <0.034 E0.08 E0.06 11 <0.0056 E0.005 <0.006 <0.016 <0.013 <0.005 E0.002 2WY88 9/14/2004 <0.034 <0.038 E0.06 8 -- -- -- -- -- -- -- --WY89 10/26/2004 <0.034 <0.038 <0.024 4 -- -- -- -- -- -- -- --WY90 11/9/2004 E0.03 <0.038 <0.024 5 -- -- -- -- -- -- -- --WY90 5/26/2005 E0.01 <0.038 <0.024 7 -- -- -- -- -- -- -- --WY91 8/19/2004 <0.034 <0.038 E0.02 1 -- -- -- -- -- -- -- --WY92 8/23/2004 <0.034 <0.038 <0.024 0 -- -- -- -- -- -- -- --WY92 12/9/2004 <0.034 <0.038 E0.05 1 -- -- -- -- -- -- -- --WY92 5/2/2005 <0.034 <0.038 <0.024 0 -- -- -- -- -- -- -- --WY93 8/24/2004 <0.034 <0.038 <0.024 2 -- -- -- -- -- -- -- --WY94 10/14/2004 <0.034 <0.038 <0.024 1 -- -- -- -- -- -- -- --WY94 2/8/2005 <0.034 <0.038 <0.024 3 -- -- -- -- -- -- -- --WY94 5/3/2005 <0.034 <0.038 <0.024 0 -- -- -- -- -- -- -- --
Aquifer Chemistry 105

Table 12. Concentrations of volatile organic compounds and pesticides detected in groundwater samples from wells in the Woodbury study area, and from selected wells elsewhere in the Pomperaug Basin, Connecticut, 2002–05.—Continued[ID, identifier; concentrations in micrograms per liter; <, less than; E, estimated value below minimum reporting level; --, not measured; VOC, volatile organic compound; red values indicate detectable concentrations; bedrock wells shaded gray]

Compound 

group Other VOC compounds Pesticides

Well 

ID

Sample 

date

1,4-

Dichlorobenzene 

(p-DCB)

Carbon 

disulfide 

(CS2)

Chloroform

Total 

VOC 

detects

4-Chloro2-methyl 

phenol

Atrazine

Deethyl 

atrazine 

(CIAT)

Fipronil Fipronil sulfide Prometon Simazine Total pesticide detects

WY95 8/2/2004 <0.034 <0.038 <0.024 12 -- -- -- -- -- -- -- --WY95 2/1/2005 <3.4 <3.8 <2.4 5 -- -- -- -- -- -- -- --WY95 6/16/2005 <0.34 <0.38 <0.24 6 -- -- -- -- -- -- -- --WY96 11/4/2004 <0.034 <0.038 <0.024 0 -- -- -- -- -- -- -- --WY96 2/9/2005 <0.034 <0.038 <0.024 1 -- -- -- -- -- -- -- --WY96 6/15/2005 <0.034 <0.038 <0.024 7 -- -- -- -- -- -- -- --WY97 2/15/2005 <0.034 <0.038 <0.024 0 -- -- -- -- -- -- -- --WY98 8/25/2004 <0.034 <0.038 <0.024 5 -- -- -- -- -- -- -- --WY99 10/21/2004 <0.034 E0.08 <0.024 3 -- -- -- -- -- -- -- --WY99 2/3/2005 <0.034 <0.038 <0.024 6 -- -- -- -- -- -- -- --WY99 5/23/2005 <0.034 E0.02 <0.024 5 -- -- -- -- -- -- -- --WY100 8/3/2004 <0.034 <0.038 E0.04 12 <0.0057 <0.007 <0.006 <0.016 <0.013 <0.005 0.008 1WY101 8/4/2004 <0.034 <0.038 E0.02 7 <0.0057 <0.007 <0.006 E0.010 E0.007 <0.005 0.012 2WY102 8/5/2004 <0.034 <0.038 E0.04 10 <0.0057 <0.007 <0.006 <0.016 <0.013 0.0065 E0.005 1WY102 11/30/2004 <0.034 <0.038 E0.04 12 -- -- --WY102 5/24/2005 <0.034 <0.038 E0.03 11 -- -- --WY106 12/27/2004 <0.034 <0.038 <0.024 1 -- -- --WY651 6/6/2002 <0.05 <0.07 E0.01 4 -- 0.024 E0.008 <0.015 <0.005 2WY651 4/11/2005 <0.034 <0.038 E0.05 4 -- -- --WY651 11/9/2005 <0.034 <0.038 E0.05 3 <0.0056 0.022 E0.006 <0.016 <0.013 <0.01 0.008 3SB1201 11/6/2002 <0.05 <0.07 E0.02 3 -- <0.007 <0.006 <0.007 <0.005 <0.015 0.11 1

1Glacial, domestic-supply well (major aquifer study) in the Pomperaug Basin.
106 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06 Table 13. Statistical summary of volatile organic compounds and pesticides detected in groundwater samples from wells in the study area, Woodbury, Connecticut, 2002–05.—Continued [μg/L, micrograms per liter; USEPA, U.S. Environmental Protection Agency; MCL, Maximum Contamination Level; N, number of samples analyzed; E, estimated value; --, no data; LT, less than reporting level.] Constituent Chemical Abstracts Service Registry number Minimum Median Mean Maximum

N E values

Number 

of values 

greater 

than or 

equal to 

reporting 

level

Total 

number 

of 

detections

Sum 

of 

detections 

at each 

well

Well 

detection 

frequency 

(percent)

USEPA 

MCL 

concentration 

(μg/L)1

Volatile organic compounds

Perchloroethene (PCE) 127-18-4 0.014 0.06 0.58 11 84 14 21 35 15 42 51,1,1-Trichloroethane (TCA) 71-55-6 0.01 0.032 2.1 22 84 12 19 31 12 33 200Trichloroethene (TCE) 79-01-6 0.01 0.038 2.3 25 84 7 23 30 12 33 51,1-Dichloroethane (DCA) 75-34-3 0.019 0.035 0.1 3.5 84 21 9 30 11 31 --cis-1,2-Dichloroethene (cis-1,2-DCE) 156-59-2 0.011 0.024 0.14 2.2 84 9 16 25 10 28 701,1-Dichloroethene (1,1-DCE) 75-35-4 0.024 0.024 0.08 2.4 84 9 7 16 5 14 7Chloroethane 75-00-3 0.089 0.12 0.27 12 84 1 0 1 1 3 --Chloromethane 74-87-3 0.033 0.17 0.38 17 84 6 0 6 0 --Vinyl chloride 75-01-4 0.041 0.08 0.17 8 84 1 0 1 1 3 --1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113) 76-13-1 0.038 0.038 0.3 3.8 83 2 14 16 7 19 2,000Dichlorodifluoromethane (CFC-12) 75-71-8 0.054 0.18 0.41 18 83 3 0 3 2 6 --Methyl ethyl ketone (MEK) 78-93-3 0.5 4 5.6 200 83 1 0 1 1 3 --Acetone 67-64-1 1.8 6 14 600 83 1 0 1 1 3 --Carbon disulfide 75-15-0 0.015 0.038 0.094 3.8 84 5 1 6 5 14 700Chloroform 67-66-3 0.009 0.024 0.086 2.4 84 35 7 42 17 47 2 80Tetrahydrofuran (THF) 109-99-9 0.28 1.7 2.8 100 84 3 0 3 2 6 --Methyl-tert-butyl ether (MTBE) 1634-04-4 0.08 0.18 250 17,000 84 4 43 47 18 50 --tert-Amyl methyl ether (TAME) 994-05-8 0.04 0.08 40 2,800 84 4 18 22 9 25 --Ethyl-tert-butyl ether (ETBE) 637-92-3 0.017 0.05 0.76 41 84 5 14 19 7 19 --Diisopropyl ether 108-20-3 0.1 0.1 0.23 10 84 0 1 1 1 3 --Benzene 71-43-2 0.011 0.021 0.061 2.1 84 13 2 15 10 28 5Ethylbenzene 100-41-4 0.01 0.03 0.069 3 84 3 1 4 4 11 700Isopropylbenzene 98-82-8 0.026 0.038 0.088 3.8 84 1 0 1 1 3 --1,2,4-Trimethylbenzene 95-63-6 0.023 0.056 0.13 5.6 84 3 2 5 4 11 --
Aquifer Chemistry 107

Table 13. Statistical summary of volatile organic compounds and pesticides detected in groundwater samples from wells in the study area, Woodbury, Connecticut, 2002–05.—Continued[μg/L, micrograms per liter; USEPA, U.S. Environmental Protection Agency; MCL, Maximum Contamination Level; N, number of samples analyzed; E, estimated value; --, no data; LT, less than reporting level.]

Constituent

Chemical 

Abstracts

Service 

Registry 

number

Minimum Median Mean Maximum N E values

Number 

of values 

greater 

than or 

equal to 

reporting 

level

Total 

number 

of 

detections

Sum 

of 

detections 

at each 

well

Well 

detection 

frequency 

(percent)

USEPA 

MCL 

concentration 

(μg/L)1

Toluene 108-88-3 0.009 0.05 0.062 2 84 13 1 14 11 31 1,0002-Ethyltoluene 611-14-3 0.017 0.06 0.14 6 84 1 0 1 1 3 --1-Ethyl-2-methylbenzene (o-ethyl toluene) 95-47-6 0.016 0.038 0.088 3.8 84 3 0 3 4 11 --m- and p-xylene 106-42-3 and 

108-38-3

0.016 0.06 0.14 6 84 5 0 5 5 14 --

Carbon tetrachloride 56-23-5 0.027 0.06 0.14 6 84 2 0 2 2 6 --1,4-Dichlorobenzene (p-DCB) 106-46-7 0.013 0.034 0.082 3.4 84 7 1 8 3 8 --

Pesticides

4-Chloro-2-methylphenol 1570-64-5 0.006 0.006 0.006 0.009 24 1 0 1 1 3 --Atrazine 1912-24-9 0.002 0.007 0.009 0.024 26 2 4 6 2 6 3Deethyl atrazine (CIAT) 6190-65-4 0.002 0.006 0.0060 0.008 26 4 0 4 1 3 --Prometon 1610-18-0 0.004 0.005 0.011 0.1 26 2 7 9 6 17 100Simazine 122-34-9 0.002 0.005 0.011 0.11 26 5 10 15 8 22 4Fipronil sulfide 120067-83-6 0.003 0.013 0.012 0.013 25 3 0 3 1 3 --Fipronil 120068-37-3 0.006 0.016 0.014 0.016 25 3 0 3 3 8 --

1U.S. Environmental Protection Agency (2006b).2MCL is for total trihalomethanes.
108 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

0.01 0.1 1.0 10 100 1,000 10,000

CONCENTRATION, IN MICROGRAMS PER LITER

4-chloro-2-methyl phenol

Simazine

Prometon

Fipronil sulfide

Fipronil

Deethyl atrazine (CIAT)

Atrazine

PESTICIDES

0.001 50,000

o-xylene

m- & p-xylene

Trichloroethylene

Toluene

Tetrachloroethylene

TAME

Methylchloride

MTBE

Ethylbenzene

ETBE

cis-1,2 dichloroethene

Chloroform

Carbon disulfide (CS2

)

CFC113

Benzene

1,4-dichlorobenzene (p-DCB)

1,2,4-trimethyl benzene

1,1-dichloroethylene

1,1-dichloroethane

1,1,1-trichloroethane

EXPLANATION

Glacial aquifer, shallow

Glacial aquifer, deep

Bedrock

PSW-1

Glacial aquifer, domestic well

 (Pomperaug Basin)

A

B

VOLATILE ORGANIC COMPOUNDS

Figure 27. Concentrations of (A) the 20 most frequently detected volatile organic compounds, and (B) the seven most 

frequently detected pesticides, in groundwater samples from each well site in the Woodbury study area, and from 

selected wells elsewhere in the Pomperaug Basin, Connecticut.
Aquifer Chemistry 109

2004, to July14, 2006, when the concentration of MTBE in 

the influent was less than 100 μg/L. Concentrations of MTBE 

in groundwater from PSW-1 had decreased to less than 2 μg/L 

by July 2006 (Scott Beals, Sovereign Consulting, Inc., written 

commun., 2007).

Volatile organic compounds can result from industrial 

production for use in industrial, commercial, or domestic 

applications but also can originate from transformation in the 

environment of parent VOC compounds. These productionand domestic-use sources, as well as environmental 

transformations, likely are sources of the 30 VOCs detected 

in this study area. Possible transformation byproducts include 

(1) TCE and 1,2-DCE from PCE; (2) 1,1-DCA from TCA; (3) 

1,2-DCE, 1,1-DCE, and vinyl chloride from TCE (Gillham, 

1996). Benzene was detected at concentrations up to 9,200 

μg/L at the source of the gasoline spill (discussed previously in 

this section). The four-fold decrease in benzene concentrations 

over the 180 m distance to WY95 indicates a loss rate of 56 

μg/L per m, and that of MTBE yields a loss rate of about 0.19 

μg/L per m. Tetrahydrofuran was detected at concentrations 

near the MRL at WY35, located in an industrial setting, and at 

well WY85, located downgradient from a restaurant septictank drainfield in a commercial area. Tetrahydrofuran is a 

moderately polar solvent that is used in production of food 

storage and packaging materials, rubber, resins, and plastics. 

It commonly is used in industry to degrease metal parts, 

so its uses appear to be consistent with the different source 

areas where it occurs. Carbon disulfide (CS2) was detected in 

water samples from wells WY35, 88, 78, 83, and 99, where 

naturally occurring DOC was likely present under sometimes 

Fe- or Mn-reducing conditions in sediments adjacent to 

the well screen. Small amounts of CS2 can be released by 

the degradation of organic matter in wetlands, although 

the highest concentrations of CS2 occur near industrial or 

commercial sources. CS2 also is used in soil disinfectants, 

herbicides, and grain fumigants (Montgomery and Welkom, 

1990).

Pesticides

Pesticide concentrations were low and generally 

at or near the MRL. Eight pesticides were detected at 

low concentrations in groundwater samples: atrazine, 

deethylatrazine (CIAT, an atrazine breakdown product 

or degradate), prometon, simazine, 1,4-dichlorobenzene 

(p-DCB), 4-chloro-2-methylphenol, fipronil, and fipronil 

sulfide (table 12; fig. 27). Six of these compounds 

were detected in water samples from PSW-1 (table 12). 

Concentrations of atrazine in groundwater were much less 

than 3 μg/L, which is the MCL (USEPA, 2006a). Atrazine 

is an herbicide most commonly detected in agricultural 

areas but also is used on lawns and golf courses, and along 

roads and rights-of-way (Gilliom and others, 2006); it can 

persist in groundwater for long periods of time (Denver and 

Sandstrom, 1991; Barbash and others, 1999). Prometon and 

simazine are usually associated with urban herbicides and 

are applied to lawns, roadsides and other rights-of-way, and 

nurseries. Fipronil is used as a household insecticide in flea 

and tick sprays, ant and roach baits, and granular turf products 

(USEPA, 1996). The compound 4-chloro-2-methylphenol, 

which is a transformation product of the herbicide 

2-methyl-4-chlorophenoxyacetic acid (MCPA), was detected 

in well WY85. 

Atrazine was detected in only a few wells, probably 

because there is little agricultural land use in the study 

area. A measure of an organic compound’s hydrophobicity 

is expressed by reporting a coefficient K that indicates the 

compound’s octanol/water partition coefficient (Kow), which 

is the ratio of a chemical’s concentration in the octanol phase 

to its concentration in the aqueous phase of a two-phase 

octanol/water system. Atrazine is considered to be highly 

mobile and has a log Kow of 2.75 (MacKay and others, 1997). 

The atrazine transformation product, CIAT, has a log Kow

of 1.3 (Gilliom and others, 2006) and also was not widely 

detected. Prometon and simazine are highly soluble and 

mobile in water (Gilliom and others, 2006) and were detected 

at low concentrations in both shallow and deep glacial wells 

downgradient from the commercial area, whereas atrazine 

was detected above the MRL at only one site (WY65) near 

a horse paddock north of the study area. Fipronil adsorbs 

strongly to soil and has low-to-moderate solubility in water 

(Kow=4.01; Connelly, 2001) but was detected at estimated 

values less than the MRL in samples from PSW-1, an adjacent 

monitoring well, WY101 and a nearby shallow well WY74. 

Fipronil sulfide is a transformation product of fipronil that has 

a relatively low mobility. Shallow wells downgradient from 

commercial or community-residential septic-tank drainfields, 

including WY79, 85, and 90, had detections of p-DCB, which 

is used to control moths, molds, and mildew, and to deodorize 

restrooms and waste containers. Twenty-two percent of its 

production is for use as a deodorant in toilet blocks, and 

28 percent is for use as a moth repellent (Agency for Toxic 

Substances and Disease Registry, 2006). The leachate from 

septic-tank drainfields that are upgradient from the wells in 

which p-DCB was detected originates from buildings where 

professional cleaning services or supplies are used and likely 

contains this compound. p-DCB is a possible carcinogen, 

although there is no direct evidence that it can cause cancer in 

humans (Norris, 1997).

Groundwater Age

Samples were collected to estimate groundwater ages 

using several tracers, including (1) 3H, (2) 3H-3He, (3) SF6, 

and (4) chlorofluorocarbons (CFCs). Apparent groundwater 

age is defined as the time elapsed since recharge of a sampled 

parcel of water. 3H was measured for several wells, in addition 

to those sampled for 3H-3H, to determine whether the water 

was prenuclear detonation (or prebomb) in age and recharged 

before 1952, or postbomb in age. Dissolved gas concentrations 

were measured to estimate the temperature of groundwater 
110 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

at the time of recharge, because the solubility of atmospheric 

tracers varies as a function of temperature, and to calculate the 

amount of excess air and excess N (table 11). 

Recharge temperatures were estimated from Ne, Ar, and 

N2 dissolved gas concentrations and yielded an average of 

9.0°C; average excess air volume was 2.2 cm3/L at standard 

temperature and pressure (cm3STP/L) (table 11). The 

estimated recharge temperature varied in PSW-1 between 

the two sampling years, as indicated by the range in recharge 

temperatures (7.8 to 10.6°C) (table 11). Recharge temperatures 

in shallow wells averaged 10.2°C with 2 cm3STP/L of excess 

air, and those in the deep glacial, upland till, and bedrock 

wells averaged 8.1°C with 2.3 cm3STP/L excess air. In 

addition to this stratification in groundwater temperatures, 

there is an inverse relationship between apparent groundwater 

age and recharge temperature (fig. 28A). There are three 

possible reasons for the differences in recharge temperatures. 

(1) Groundwater recharge from stormwater runoff over 

pavement and other impervious surfaces and from septic-tank 

drainfields in the relatively urbanized valley bottom would 

generally be warmer than water recharged in upland areas. 

Water from shallow wells can be very young (0 to 2 years) 

and, because many of the dissolved gas samples were 

collected during the fall, may reflect warmer temperatures, 

especially in areas of overland flow (warm pavement) and 

septic-tank drainfields. Furthermore, recharge temperatures in 

shallow groundwater were affected locally in some wells by 

streamflow leakage to groundwater during warmer months. 

(2) A greater percentage of recharge may occur in the uplands 

during the winter and spring, compared to that in the valley 

bottom. The uplands are predominantly forested, and soils 

are generally more porous on the forest floor and could 

allow more infiltration compared to cleared and compacted 

developed land at the valley bottom, even during winter 

months (Satterlund and Adams, 1992). (3) Air temperatures 

have warmed over the past 150 years (Jones and others, 1999) 

and older groundwater was recharged at colder temperatures. 

This is consistent with the decrease in d18O and dD values 

observed with increasing groundwater age (fig. 25A and 

table 8).

The amount of excess air calculated from dissolved gases 

also varied among wells and was larger in bedrock wells, 

and in wells WY81 and 82, which have recent recharge. Well 

WY85 appeared to be stripped of some dissolved gases, based 

on the ratios of N2, Ar, and Ne. Gas stripping in groundwater 

at WY85, and possibly the deeper well WY84, could result 

from CH4, H2S, and N2 gas bubbles rising through sediments 

as a result of natural microbial processes associated with the 

decomposition of septic-system leachate. Two other wells, 

WY89 and WY90, are immediately downgradient from a 

septic-tank drainfield. Excess N2 amounts were estimated 

for these wells, as discussed in section “Collection and 

Analysis of Water Samples,” because it is very likely that the 

conversion of NO3

−

 to N2 occurred here, given the low DO 

concentrations, the high DOC concentrations, and the low 

concentrations of NO3

−

. Well WY79 had excess N2 amounts 

and is located in a town park where fertilizer N is a likely 

source. Organic-rich glacial sediments derived from the Cass 

Formation also could create the low DO concentrations near 

the well (table 7).

Dating groundwater with 3H is qualitative at best, but 

can be useful in recognizing postbomb water, and can be used 

together with other tracers to estimate mixing of groundwater 

from various sources. 3H concentrations in samples from wells 

screened in glacial deposits ranged from 6.0 tritium units (TU) 

in well WY102 to 7.5 TU in WY76 (table 14). These ranges in 

values reflect, in part, the high seasonal and annual variations 

observed in 3H in precipitation (Clark and Fritz, 1997). The 3

H concentration in a sample from a bedrock well WY106 

was 0.10 TU, indicating that the water likely was recharged 

before 1952.

The 3H/3He dates were estimated in 18 samples from 

17 wells (PSW-1 was sampled twice). Apparent age in 

groundwater is less than 6 years in most glacial aquifer 

deposits, but older in bedrock groundwater, which flows 

through fractures that require longer or slower flow paths 

(fig. 28A). Apparent groundwater ages in the glacial aquifer 

ranged from 0.7 years in a shallow well near PSW-1 to 

8.4 years in a deep well about midway along the flow path 

in overlying glacial deposits. Apparent ages in groundwater 

from shallow bedrock wells (less than 15 m below bedrock 

surface) ranged from 9.9 to over 20 years. Well WY87, which 

intersects a fracture in basalt, had an apparent age of 9.9 years, 

which is longer than the mean simulated age of 2.6 years 

(tables 9 and 14). The measured residence time can be long 

for at least two reasons: (1) the actual flow path can be longer 

than the simulated flow path because of tortuous paths through 

a fracture network (fracture networks are not explicitly 

included in the simulation), or (2) the sample is a mixture of 

water of a short residence time (through a permeable fracture) 

and water of a long residence time (from dead-end fractures 

or from fractures so small that Darcy’s Law does not apply) 

(Starn and Brown, 2007). The simulated residence times in 

bedrock tend to be short because of the low bulk-rock porosity 

that is used in the advective particle tracking. 

The 3H-3He apparent-age calculations are sensitive 

to the amount of terrigenic 4He (from decay of U-series 

radionuclides) and excess air. Terrigenic 4He is naturally 

derived from crystalline rock sources (Plummer and others, 

2003) and excesses of even 50 percent over that of air-water 

equilibrium can invalidate or create large uncertainties 

in 3H-3He dating, such as in areas where the old fraction 

contains mixed mantle and crustal helium sources (Plummer 

and others, 2000). Terrigenic 4He (relative to the total 4He) 

generally was high (greater than 15 percent) and water 

samples from bedrock wells WY86, WY97, and WY106 had 

exceedingly high percentages of terrigenic He that precluded 

determination of ages (table 14). The 4He concentrations also 

were high in samples from glacial sediments, possibly from 

decay of U-series radionuclides in sand grains (Fe oxides or 

feldspars) that originated from crystalline rock in the uplands. 

This explanation is supported by an increase of excess 4He 
Aquifer Chemistry 111

concentration with age (fig. 28B); 4He concentrations are 

lower in younger groundwater (less than 7 years in age), and 

He apparently accumulates from U-series decay in aquifer 

sediments. In addition, temperature correlates with excess 

4

He; samples with high excess 4He typically had cooler 

recharge temperatures, whereas young samples had warmer 

temperatures (for example, WY74 and WY76). Samples with 

a negative percent terrigenic 4He, including those collected 

from wells WY74, WY84, and WY85 (table 14), may indicate 

gas stripping, which could result in preferential loss of 3He and 

yield an older estimated age.

Lumped parameter models were used to estimate the 

mean residence time and age distribution of groundwater 

in the glacial aquifer and the underlying fractured bedrock. 

These models treat an aquifer system as a homogeneous 

compartment in which the input tracer concentrations are 

converted to output tracer concentrations according to the 

system-response function used and how the flow system is 

described (Zuber, 1986; Maloszewski and Zuber, 1982). Flowsystem characteristics are represented by assumed conceptual 

end members, including a piston-flow model (PFM), an 

exponential-mixing model (EMM), and a binary-mixing model 

(BMM) (Cook and Böhlke, 1999) (fig. 28C). For the PFM, it 

is assumed that after a tracer is isolated from the atmosphere 

(at the time of groundwater recharge), it becomes incorporated 

in a parcel of water that moves from the recharge area with 

the mean velocity of groundwater. All flow lines are assumed 

to have similar velocities, and hydrodynamic dispersion and 

Figure 28. (A) Apparent groundwater age as a function of estimated groundwater recharge temperature, (B) apparent groundwater 

age as a function of terrigenic helium-4 (4He) percentage, and (C) the tritium/initial tritium (3H/3H(0)) concentration ratio plotted as a 

function of concentrations of helium-3 (3H), with modeled curves for various groundwater age distributions for groundwater samples 

from wells in the study area, Woodbury, Connecticut.

35

69

73

75

84

86 (CFC age)

97 (CFC age)

87

100

101

106

106

102

74

76

APPARENT AGE, IN YEARS

A

B

APPARENT AGE, IN YEARS

4

5

6

8

9

7

10

11

12

13

ESTIMATED RECHARGE TEMPERATURE,

IN DEGREES CELSIUS

EXPLANATION

Glacial aquifer, shallow,

and identifier

Glacial aquifer, deep,

and identifier

Bedrock, shallow,

and identifier

Bedrock, deep, and

identifier

PSW-1

100

87

35

EXPLANATION

N

Glacial aquifer, shallow, and identifier

Glacial aquifer, deep, and identifier

Bedrock, shallow,

and identifier

PSW-1

69

87

71

Log base 10

 curve

0

20

10

30

50

70

40

60

TERRIGENIC HELIUM-4 (4He),

IN PERCENT

74

76 71 84

73 70

102 100

69

87

72

75

101

(Tritium age,

minimum)

70 87

73 75

71

0

10

20

30

40

0 0.2 0.4 0.6 0.8 1.0

TRITIUM/INITIAL TRITIUM (3H/3H(0)) CONCENTRATION

RATIO, IN TRITIUM UNITS

TRITIUM (3H) CONCENTRATION,

IN TRITIUM UNITS

Piston flow model

Exponential mixing model

Binary mixing model

Exponential piston model

100

102

PSW-1 101

C

85

72

EXPLANATION

Glacial aquifer, shallow,

and identifier

Glacial aquifer, deep,

and identifier

Bedrock, shallow, and identifier

PSW-1

100

87

71

69

76 84 74

0 5 10 15 20 25 30 35 40 45 50 55 0 1 2 3 4 5 6 7 8 9 10 11
112 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

molecular diffusion of the tracer are assumed to be negligible. 

The BMM assumes that one or both end members of the 

binary mixture is either young or old. The EMM represents 

an aquifer system in which the mean residence time of 

groundwater is exponentially distributed. Groundwater flow 

is composed of recharge from all past years, but contributions 

to well discharge decrease exponentially from the most recent 

recharge to that which took place in the very distant past. In 

the exponential-piston model (EPM), the sample consists of 

an infinite number of subparcels that have an exponential age 

distribution (EMM), but the whole assemblage is shifted in 

time (Cook and Böhlke, 1999).

A computer program (Böhlke, 2005) was used to 

calculate theoretical curves for the different lumped parameter 

models using atmospheric data as input for the various tracers. 

3

H(0) represents the initial 3H concentration at the time of 

recharge and is the sum of the measured concentrations of 3H 

and tritiogenic 3He. A graph of the relation between 3H/3H(0)

and 3H (fig. 28C) shows that most well samples generally plot 

along the PFM curve for very young water (less than 6 years 

in age), although samples from two deep wells (WY69 and 

WY75) and WY102, a shallow well near PSW-1, plot on or 

near the BMM curve dominated by young water (fig. 28C). 

The fit of samples to the BMM curve supports earlier evidence 

that a small proportion of the sample may be tracer-free water 

derived from the underlying bedrock. The 3H-3He apparent 

ages of deep glacial wells generally are older than those of 

shallow wells; Starn and Brown (2007) used simulated agetracer distributions to explain that about 34 percent of the 

flow in glacial deposits at the study area was derived from 

underlying bedrock.

A graph of 3H/3H(0) and SF6 concentrations (fig. 29A) 

shows the relatively high concentrations of the SF6 tracer 

relative to the 3H/3H(0) ratio. The disparity probably results 

from background SF6 concentrations in glacial deposits that 

were derived from high-temperature crystalline rocks; as 

with terrigenic 4He, terrigenic SF6 also occurs naturally in 

some crystalline rocks, mainly as fluid inclusions, and slowly 

diffuses into the water (Busenberg and Plummer, 2000). Well 

WY86, which is completed in the crystalline bedrock, had a 

measured SF6 concentration of more than 19 femtomoles per 

kilogram (femtomol/kg), whereas the SF6 concentrations in 

the rest of the samples were generally less than 3 femtomol/

kg (table 14). Although it seems likely that SF6 concentrations, 

like terrigenic 4He, are naturally high in the glacial deposits 

derived from crystalline rocks, the correlation is not good 

between these constituents (fig. 29B). However, the water 

samples from deep glacial wells that likely are affected 

by groundwater from bedrock are particularly high in 

concentrations of SF6 and terrigenic 4He (PSW-1, WY69, 

WY72, and WY75). Water samples from other wells that are 

not high in concentrations of terrigenic 4He, but do have high 

concentrations of SF6, may have additional sources (fluid 

inclusions) in the glacial deposits and, therefore, are not as 

attenuated as is 4He during transport away from the bedrock 

source. The SF6 tracer gives a current age of water in most 

wells and, therefore, was not used for analysis in this study.

Age dating with CFCs was done only in two of the 

bedrock wells (table 15); the presence of CFCs that originate 

from spills or tank leaks precluded their use at wells with 

flow paths underlying or downgradient from commercially 

developed land. Generally, the apparent ages determined by 

CFCs are older than those determined by 3H/3He because 

the 3H/3He ages are based on an isotope ratio that should not 

be affected by mixing with old (pre-1952) water. However, 

CFCs can be degraded under anaerobic conditions, and the 

resulting low concentrations indicate artificially old apparent 

groundwater ages. Based on concentrations of the CFC-12 

tracer and using a PFM, groundwater from WY86 has an 

apparent age of about 8 to 10 years. The CFC-11 and CFC-113 

tracers are more prone to degradation under Fe- and SO4

2−

reducing conditions and, on the basis of ratio comparisons 

to CFC-12, appear to be partially degraded; the low 

concentrations of DO and detectable amounts of H2S and CH4

measured in samples from this well support the hypothesis 

that some anaerobic degradation has taken place. CFC-12 is 

less prone to degradation, so the apparent age could be even 

younger than 8 to 10 years, especially given the fact that the 

well exhibits artesian conditions following spring recharge. 

WY97 was contaminated with CFC-11, probably from a 

septic-tank drainfield about 40 m west of the well, but CFC-12 

and CFC-113 indicate an apparent age range of 20 to 22 years. 

Groundwater residence times were simulated using 

MODPATH (table 9), as discussed in section “Major Elements 

and Nutrients,” to help relate natural and anthropogenic 

factors to water quality because groundwater tracers for which 

apparent ages can be estimated were not sampled at all wells. 

The mean simulated flow-weighted residence time of water 

withdrawn from PSW-1, determined with forward particle 

tracking, is 5.8 years (Starn and Brown, 2007) and agrees 

reasonably with the apparent 3H-3He age of 5.5 and 6.6 years. 

About 34 percent of the groundwater from PWS-1 corresponds 

to water recharged in the glacial aquifer and is younger than 

5 years, about 56 percent of the water is from 5 to 9 years old, 

and the remaining 10 percent of the water is older than 9 years 

and likely was derived from till or upland bedrock, based on 

model simulations (Starn and Brown, 2007). Vertical profiles 

of groundwater residence time for water recharged through 

the valley bottom seem to show superimposed exponential 

distributions, whereas in deeper parts of the aquifer, which 

are recharged primarily in the uplands, the vertical profiles 

show a piston-flow distribution (Starn and Brown, 2007). 

The wide range of ages in the aquifer is a result of a mixing 

of many different flow paths, such that age inversions (older 

water overlying younger water) can occur at several points in 

the profile.

Groundwater age plotted as a function of the number of 

VOC detections (fig. 30) indicates that VOC occurrences are 

related to short groundwater traveltimes, and therefore, young 

groundwater is more vulnerable to contamination than older 

groundwater. The exceptions include the samples from PSW-1 
Aquifer Chemistry 113

Table 14. Summary of tritium/helium-3 (3H/3He), sulfur hexachloride (SF6), and chlorofluorocarbons (CFC) groundwater age tracer 

data and apparent ages using a piston flow model for water samples in the study area, Woodbury, Connecticut, 2003–2005. 

[Ages in bold are deemed most reliable; ID, identifier; NP, not possible to calculate an age; --, not measured; cm3STP/gH2O, cubic centimeters per gram of 

water at standard temperature and pressure; TU, tritium units; femtoMol/kg, femtomoles per kilogram; pmol/kg, picomoles per kilogram; pptv, parts per 

trillion by volume; bedrock wells shaded gray]

Sample 

ID

Sample 

date

Tritium-helium (3H/3He) data

3

H 

(TU)

3

H 

error 

1 

sigma 

(TU)

[

4

He] 

measured 

(cm3STP/

gH2O)

[

3

He] 

measured 

(cm3STP/

gH2O)

3

H/3He Age, 

No 

terrigenic 

correction 

(years)

[

3

He]

(TU)

4

He, 

terrigenic 

percent

3

H/3He 

age, adjusted 

for terrigenic 

He (years)

PSW-1 12/30/03 6.8 0.14 8.33E-8 8.28E-14 NP 2.99 34.3 6.6

PSW-1 08/11/04 6.8 0.03 8.36E-8 8.28E-14 NP 2.46 33.5 5.5

WY69 12/10/03 6.1 0.12 1.08E-7 8.70E-14 NP 2.34 45.8 5.8

WY70 12/29/03 6.1 0.12 5.78E-8 8.11E-14 2.29 1.91 3.4 4.9

WY71 12/22/03 7.0 0.14 5.36E-8 7.34E-14 0.03 0.75 2.5 1.8

WY72 12/16/03 6.6 0.13 1.38E-7 9.39E-14 NP 3.96 56.3 8.4

WY73 12/17/03 6.7 0.13 5.09E-8 7.03E-14 0.81 1.68 4.9 4.0

WY74 11/06/03 7.1 0.14 5.27E-8 7.31E-14 0.82 0.30 0 0.75

WY75 11/13/03 6.2 0.12 1.54E-7 9.32E-14 NP 4.63 62.2 10

WY76 11/12/03 7.5 0.15 5.32E-8 7.22E-14 -0.81 0.37 2.4 0.86

WY84 11/18/03 7.0 0.14 6.18E-8 8.72E-14 2.30 1.47 1.5 3.4

WY85 11/19/03 6.8 0.14 8.51E-8 1.19E-13 2.32 2.01 2.3 1

4.6

WY87 12/18/03 7.0 0.14 5.86E-8 8.86E-14 6.96 5.18 5.8 9.9

WY100 08/03/04 6.5 0.13 7.05E-8 8.18E-14 -49.90 2.04 21.0 4.9

WY101 08/04/04 7.0 0.17 7.77E-8 8.16E-14 NP 2.44 29.5 5.4

WY102 08/05/04 6.0 0.31 6.28E-8 7.13E-14 NP 2.17 23.6 5.6

WY106 12/27/04 0.10 0.004 2.19E-7 6.17E-13 128 219 76.6 2

>50

WY86 03/07/05 -- -- -- -- -- -- --

WY97 02/16/05 -- -- -- -- -- -- --

1

Gases likely fractionated due to gas stripping; age not reliable.

2

Age based on tritium concentration only.

3

Highly contaminated with CFCs.
114 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

Table 14. Summary of tritium/helium-3 (3H/3He), sulfur hexachloride (SF6), and chlorofluorocarbons (CFC) groundwater age tracer 

data and apparent ages using a piston flow model for water samples in the study area, Woodbury, Connecticut, 2003–2005.—Continued 

 [Ages in bold are deemed most reliable; ID, identifier; NP, not possible to calculate an age; --, not measured; cm3STP/gH2O, cubic centimeters per gram of water at 

standard temperature and pressure; TU, tritium units; femtoMol/kg, femtomoles per kilogram; pmol/kg, picomoles per kilogram; pptv, parts per trillion by volume; 

bedrock wells shaded gray]

Sulfur hexafluoride (SF6) data Chlorofluorocarbons (CFC) data

SF6

in 

water 

(femtoMol/

kg)

Calculated 

SF6

partial 

pressure 

(pptv)

SF6 apparent 

recharge 

year, 

piston 

flow 

SF6 apparent 

age, piston 

flow

CFC-11 

corrected 

concentration 

(pmol/kg)

CFC-12 

corrected 

concentration 

(pmol/kg)

CFC-113 

corrected 

concentration 

(pmol/kg)

CFC-11 age 

piston flow 

(years)

CFC-12 age 

piston flow 

(years)

CFC-113 age 

piston flow 

(years)

2.72 5.51 2003.0 Current -- -- -- -- -- --

2.16 4.43 1999 5.7 -- -- -- -- -- --

3.03 5.63 2003.5 0.9 -- -- -- -- -- --

3.09 6.14 Current Current -- -- -- -- -- --

4.05 8.04 Current Current -- -- -- -- -- --

3.12 6.22 Current Current -- -- -- -- -- --

2.73 6.97 Current Current -- -- -- -- -- --

2.89 6.89 Current Current -- -- -- -- -- --

2.82 5.32 2002.5 1.4 -- -- -- -- -- --

2.66 6.30 Current Current -- -- -- -- -- --

3.23 4.53 1999.3 4.6 -- -- -- -- -- --

1.48 2.95 1992.8 111 -- -- -- -- -- --

3.35 6.67 Current Current -- -- -- -- -- --

2.13 4.16 1998 6.7 -- -- -- -- -- --

2.62 5.46 2000.5 4.2 -- -- -- -- -- --

2.63 5.64 2002.5 2.2 -- -- -- -- -- --

-- -- -- -- -- -- -- -- -- --

19.4 31.7 NP NP 2.01 3.35 0.148 33 9.5 27

-- -- -- -- 36.7 2.72 0.389 3

NP 22 20
Aquifer Chemistry 115

and adjacent monitoring-well screens, WY100 and WY101. 

Samples from each of these wells likely consist of a composite 

of waters with a wide range of ages, including about 4 percent 

of water that was older than 10 years. 

Concentrations of selected chemical constituents and 

redox conditions also were related to groundwater age. The 

concentration of dissolved solids generally increases with the 

length of time groundwater remains in contact with source 

material. Concentrations of constituents such as SiO2 and 

HCO3

-

 may be a function of residence time, but they also can 

be affected by the aquifer material. High SO4

2− concentrations, 

for example, were associated with groundwater from 

fractured basalt beneath the valley bottom (fig. 25B). Silica 

saturation with respect to quartz generally was higher in the 

wells screened in till and bedrock than those in the glacial 

stratified deposits. The weathering of silicates in glacial 

stratified deposits should be fairly uniform, and the SiO2

content generally should be reflective of groundwater age, 

temperature, and pH, except in parts of the aquifer system near 

bedrock and till that contain greater amounts of calcite and 

silicates other than quartz. Silica saturation showed a linear 

relationship with apparent groundwater age with the exception 

of water samples from bedrock wells WY97 and WY106 that 

were affected chemically by interactions with till and deep 

Mesozoic basin water, respectively (fig. 31A). The calcite 

saturation index generally was lower in shallow glacial wells 

compared to wells screened in deep glacial stratified deposits 

and till (fig. 31B) and probably reflects a lower calcite content; 

water samples from bedrock wells all had a calcite saturation 

index near saturation.

Water Sources and Pathways

Results for all useful tracers of major water sources 

discussed previously are integrated in this section to 

characterize the source, transport, and receptor processes that 

affect the movement of selected natural and anthropogenic 

constituents to PSW-1. Characterization of water in different 

parts of the aquifer system is based on concentrations of 

selected inorganic constituents, pH, ion ratios, stable isotope 

ratios, recharge temperature, and selected anthropogenic and 

natural contaminants. The major sources of water and the 

indicative chemical characteristics used to identify the sources 

are described in table 15. 

Water from wells completed in fractured bedrock and 

till generally contained high pH and high concentrations of 

HCO3

-

, U, and 222Rn, and calcite was near saturation relative 

to that in other wells. A water sample from the deep bedrock 

well, WY106, and several deep glacial aquifer wells had 

depleted d18O and dD values and high concentrations of SO4

2−

with enriched d34S relative to those from other wells (fig. 

25A and B). As discussed previously in the “Stable Isotopes” 

section, SO4

2− concentrations and their d34S values in samples 

from several deep glacial wells and a shallow glacial well, 

WY81, plot along a hyperbola-shaped mixing line between 

WY100 and WY106; the samples appear to contain a fraction 

of heavy S from underlying bedrock, as represented by 

WY106 (fig. 25B). Monitoring wells WY88, WY102, WY100, 

WY101, WY82, WY81, WY72, WY75, and WY69, and 

PSW-1 contained water that is mostly representative of the 

glacial aquifer, but results of inverse geochemical modeling 

with PHREEQC indicated that the water also contained 

amounts of an end member, represented by water from 

WY106, ranging from 0 to 6.2 percent (table 16). Although 

WY102 is a shallow well, upward flow from bedrock below 

could affect chemistry in the well. Furthermore, the location of 

values of SO4

2− and d34S of SO42− for WY102 near the binary 

mixing model line (fig. 28C) also indicates a contribution 

of flow from underlying bedrock. The geochemical models 

included pyrite and gypsum as mineral phases; some models 

could be run without using d34S as a constraint, but those 

models required precipitation of pyrite or dissolution of 

gypsum (table 16). Samples from several wells that are near 

septic-tank drainfields and appear to have been affected 

by septic-system leachate fall within a range of relatively 

depleted d34S of SO4

2− isotope values from 4.3 to 6.3 per mil 

(fig. 25B).

 As discussed previously, several groundwater samples 

in the study area appear to have been affected by water 

from Mesozoic basin rocks or associated minerals and 

sorbed complexes. Although most brine water generated 

during basalt emplacement is likely to be purged from the 

fractured bedrock aquifer, Shapiro (2002) concludes that high 

concentrations of constituents could persist for long periods 

of time in small bedrock fractures that transmit water very 

slowly. Furthermore, sorption modeling by Appelo and Postma 

(1993) shows that sorbed constituents can persist for long 

periods of time. Although water from Mesozoic basin rocks 

may contain associated constituents of concern, the older age 

shows that the water predates substantial development, and 

therefore, the water had a lower vulnerability to anthropogenic 

contamination (table 16).

Groundwater with locally reducing conditions and 

high concentrations of As was observed in samples from 

wells screened in glacial deposits that contain entrained 

Mesozoic sediments, particularly WY83, and to a lesser 

extent WY35, WY88, and WY53. Concentrations of As, Co, 

and Li were relatively high in groundwater samples from 

WY83. Concentrations of As, U, Cd, and Pb were high in 

the 10 percent HNO1 extractions of sediment samples that 

were collected at the depth interval of the screen at WY83. U 

concentrations were low in groundwater samples from WY83 

because U typically is chemically reduced and immobile in 

reduced, organic-rich horizons. Water samples from wells 

WY35, WY88, and WY53 had high concentrations of Fe and 

(or) Mn and detectable concentrations of As, and some other 

trace elements that indicate that Mesozoic source rocks may 

have affected groundwater chemistry at these sites. Samples 

from other glacial wells adjacent to or overlying Mesozoic 

rocks in the Hartford Basin, such as S401 and F344, were 

found to have high concentrations of trace constituents, 
116 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

Figure 29. (A) Tritium/initial tritium (3H/3H(0)) concentrations as a function of sulfur 

hexafluoride (SF6) concentrations, with modeled curves for various groundwater age 

distributions, and (B) sulfur hexafluoride (SF6) concentrations as a function of terrigenic 

helium-4 (4He) concentrations, in groundwater samples from wells in the study area, 

Woodbury, Connecticut.

87

76 74

73

84

75

69 70

 71

 72

0

2

4

6

8

0 0.2 0.4 0.6 0.8 1.0

SULFUR HEXAFLUORIDE CONCENTRATION,

IN PARTS PER TRILLION BY VOLUME

 100

 101

102

Piston flow model

Exponential mixing model

Binary mixing model

Exponential piston model

EXPLANATION

Glacial aquifer, shallow, and identifier

Glacial aquifer, deep, and identifier

Bedrock, shallow, and identifier

PSW-1

98

71

EXPLANATION

Glacial aquifer, shallow, and identifier

Glacial aquifer, deep, and identifier

Bedrock, shallow, and identifier

PSW-1

98

71

TRITIUM/INITIAL TRITIUM CONCENTRATION RATIO, 

IN TRITIUM UNITS

0.1 0.3 0.5 0.7 0.9 1.1

10

30

50

70

87

2 3 4 5 6 7 8

TERRIGENIC HELIUM-4, IN PERCENT

20

0

40

60

SULFUR HEXAFLUORIDE CONCENTRATION, 

IN PARTS PER TRILLION BY VOLUME

70 76

87

73

74

71 84

69

72

75

A

B

1

3

5

7

9
Aquifer Chemistry 117

including As, Ba, B, Li, Sr, and V (table 8). As discussed 

previously, groundwater at these sites could be affected by 

glacial sediments derived from similar underlying Mesozoic 

rocks and (or) deep, ancient basin water, and thus the wells 

at these sites are more vulnerable to natural contaminants. 

Domestic or public-supply wells in such areas could be subject 

to high concentrations of As if Fe- or Mn-reducing conditions 

prevail or U if oxic conditions prevail.

Most detections of VOCs were in samples of relatively 

young groundwater from shallow or intermediate depths of 

the glacial aquifer (fig. 30) and were related to commercial 

and light-industrial development (WY71, WY76, and WY95, 

although some detections appeared to be related to residential 

land use (WY94, WY89, WY90, and WY96). 

Factors Affecting the Water Chemistry at the 

Public-Supply Well 

Pumping of PSW-1 changes the distribution of 

groundwater flow paths and the rate of flow to PSW-1. 

PSW-1 has a relatively low pumping rate (4.53 x 10-3 m3/s, or 

71.9 gal/min) compared to some other wells in glacial aquifers 

(Warner and Arnold, 2006) but can still capture contaminants 

and speed up their movement in the zone of contribution. The 

water withdrawn from PSW-1 is derived from different landuse settings, but a major part of groundwater is young and 

derived from recharge in residential and commercial land-use 

areas (fig. 4). On the basis of simulations with MODPATH 

(Starn and Brown, 2007), about 16 percent of the water 

from PSW-1 originates in the zone of higher recharge rates 

in the commercial area; the residence time for PSW-1 water 

recharged in the commercial area ranges from 1.6 to 3.8 years, 

and median flow-weighted residence time is 2.5 years (Starn 

and Brown, 2007). Water derived from the parking-lot drains 

(dry wells) and septic-tank drainfields in the commercial area 

results in only a slightly higher percentage of younger water to 

the PSW-1, but a spill in that area would cause a much more 

rapid effect at PSW-1 because of the drains. 

The groundwater pathways to the PSW-1 screen are 

affected by the lithology of intervening glacial deposits. 

Samples from the monitoring well cluster installed adjacent 

to PSW-1 were collected to understand vertical differences in 

water chemistry near PSW-1. This cluster of wells includes 

three wells with 0.6- to 1.0-m long screens: one is completed 

near the water table about 4 m below land surface, one is 

completed just above the top of the PSW-1 screen, and one is 

completed near the center of the PSW-1 screen. Geophysical 

logging and water-quality profiling also were conducted for a 

borehole that was located adjacent to, and spanned the length 

of, the PSW-1 screened interval. Profiles of temperature, 

specific conductance, DO, and flows with an electromagnetic 

(EM) flowmeter were conducted under pumping and 

nonpumping conditions.

Figure 30. Average simulated mean traveltimes of groundwater to wells based on particles in MODPATH (Starn and Brown, 

2007) as a function of the number of volatile organic compounds (VOCs) detected in groundwater samples from wells in the 

study area, Woodbury, Connecticut.

69

70

72

73

75

77

79

80

82

83

84

87

88

89

90

92 91

93

94

95

97

98

99

100

101

102

EXPLANATION

Glacial aquifer, shallow,

and identifier

Glacial aquifer, deep,

and identifier

Bedrock, shallow,

and identifier

Bedrock, deep

PSW-1

98

86

71

0 2 4 6 8 10

0

2

4

6

8

10

12

13

AVERAGE SIMULATED TRAVELTIME, IN YEARS

NUMBER OF VOLATILE ORGANIC

COMPOUND DETECTIONS
118 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

Figure 31. Apparent groundwater age as a function of the (A) silica saturation index 

and (B) calcite saturation index, in groundwater samples from wells in the study area, 

Woodbury, Connecticut.

A

0 10 20 30 40 50

APPARENT GROUNDWATER AGE, IN YEARS

-4

-3

-2

-1

0

CALCITE SATURATION INDEX

B

35

69

70

72

73

75

84

86

87

97

100

101

85 102

71

74

76

0 10 20 30 40 50

APPARENT GROUNDWATER AGE, IN YEARS

0.4

0.5

0.6

0.7

0.8

0.9

35

69

70

72

73

75

84

86

87

97

100

101

102

85

71

74

76

SILICA SATURATION INDEX

EXPLANATION

Glacial aquifer, shallow,

and identifier

Glacial aquifer, deep

Bedrock, shallow

Bedrock, deep

PSW-1

98

86

71

EXPLANATION

Glacial aquifer, shallow,

and identifier

Glacial aquifer, deep

Bedrock, shallow

Bedrock, deep

PSW-1

98

86

71
Aquifer Chemistry 119

As described in the “Hydrology” section, the glacial 

aquifer deposits adjacent to PSW-1 were found to have two 

zones of preferential flow—one adjacent to the bottom and one 

just above the top of the PSW-1 screen; the aquifer adjacent to 

the center of the screen is generally composed of finer deposits 

and appears to be less conductive to flow. Measurements 

made with a water-quality monitor in the borehole showed 

an increase in temperature and specific conductance and a 

decrease in DO concentrations in a narrow interval coincident 

with the lowermost zone of high permeability identified 

with the borehole flowmeter. This interval is located near 

the bottom of the PSW-1 screen, and the data indicate that 

the stratified nature of the deposits results in zones that are 

substantially more permeable than adjacent zones and that 

are likely to be the primary pathways for groundwater flow. 

These zones of preferential flow can be very thin (less than 

0.1 m) and may not be adequately assessed with monitoring 

wells alone.

Water-quality data from monitoring wells and boreholes 

near PSW-1 also indicate that the chemistry of water in 

the aquifer varies over short vertical intervals near PSW-1. 

These vertical variations in aquifer chemistry are affected 

by heterogeneities in the aquifer deposits and the presence 

of upgradient point sources of contaminants. Constituents in 

samples collected from the well clusters located throughout 

the zone of contribution to PSW-1 were consistent with those 

constituents in samples collected near PSW-1, indicating that 

the water quality in this study area primarily was affected 

by the distribution of point sources, such as septic-tank 

drainfields and solvent or gasoline station leaks or spills 

(Brown and others, 2006), and by aquifer characteristics. VOC 

concentrations in samples collected from PSW-1 generally 

were within the range of high concentrations in samples from 

monitoring wells screened near the top of PSW-1 and low 

concentrations in samples from the well screened near the 

center of the PSW-1 screened interval (13.7 to 18.3 m depth).

NO3

−

 concentrations and d15N and d18O of NO3

−

 were 

used to model sources of N for PSW-1. NO3

−

 concentrations in 

recharge from forested land-use areas in Connecticut and other 

northeastern states typically are less than 1 mg/L as N, so soil 

N is not a likely source of the large NO3

−

 as N concentrations 

in recharge. Samples from PSW-1 plot along a mixing line 

with end points at forested land use, represented by WY87, 

and urban land use downgradient from a septic-tank drainfield, 

WY90 (fig. 26B); 10 to 15 percent of the NO3

−

 as N in those 

samples may have been contributed by a septic-tank drainfield 

(McMahon and others, 2008). 

Table 15. Summary of major geochemical sources and the indicative chemical characteristics in the aquifer system of the study area, 

Woodbury, Connecticut. 

[SO4

2−, sulfate; HCO3-

, bicarbonate, U, uranium; 222Rn, radon-222; As, arsenic; δ34S, delta sulfur-34; δ13C, delta carbon-13; δ18O, delta oxygen-18; δD, delta 

deuterium; DOC, dissolved organic carbon; Fe, iron; Mn, manganese; DO, dissolved oxygen; Na+, sodium; Cl−, chloride; Br−, bromide; Ca2+, calcium; B, 

boron; δ15N, delta nitrogen-15; NO3

−

, nitrate; PCE, perchloroethene; TCE, trichloroethylene; 1,1-DCE, 1,1-dichloroethylene]

Major sources Indicative chemical characteristics

1. Bedrock and till effects on the glacial aquifer High pH and concentrations of SO4

2−, HCO3-

, U, 222Rn, and As 

relative to other wells; reducing redox conditions; enriched δ34S 

of SO4

2− and δ13C ratios; depleted δ18O and δD ratios; calcite near 

saturation; low recharge temperatures; and older (greater than 

6 years) groundwater ages relative to shallow and intermediate 

wells in glacial stratified deposits.

2. Natural organic matter sources, either in sediments or in 

upgradient riparian zones.

High DOC, Fe, or Mn; low DO and NO3

−

 (reducing redox 

conditions); enriched δ34S.

3. Road salt (halite) High Na+, Cl−, Ca2+; high Cl/Br ratios.

4. Septic-system leachate High NO3

−

, DOC, Na+, Cl−, Ca2+, and B; enriched δ15N and δ18O of 

NO3; indicative Cl/Br ratios.

5. Organic solvent spills PCE, TCE, 1,1-DCE

6. Fuel station spill Fuel oxygenates, benzene near source.

7. Surface-water leakage Enriched δ18O and δD; seasonally high DOC and low DO or NO3

−

.
120 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

Table 16. Results of inverse geochemical modeling with PHREEQC to determine the relative contribution of high-sulfate groundwater from underlying fractured bedrock, represented by a sample from WY106, to the glacial aquifer, represented by a sample from WY100, in the study area, Woodbury, Connecticut. [%, percent; CaX2, calcium exchange site; NaX, sodium exchange site; MgX2, magnesium site; Fe(OH)3(a), amorphous iron oxide]

Percent 

end 

member 

WY100

Percent 

end 

member 

WY106

Final 

well

Models 

found

Model 

run

Phases

Phase 

mole 

transfers

Uncertainty

Notes Sum 

of 

residuals

Sum of 

delta/ 

uncertainty 

limit 

Maximum 

fractional 

error in 

element 

concentration 

99.2% (98–99.6%) 0.8% (0.4–2%) PSW-1 3 Model 1 No phases No phases 7.4 10 0.2 Runs without δ34S mineral reaction or requires 

dissolution of gypsum and 100% of WY100, or pyrite precipitation and 100% of WY100

100% 0 Model 2 Gypsum 1.61E-5 7 7 0.2100% 0 Model 3 Pyrite -3.85E-6 7.1 8 0.18

Fe(OH)3(a) 3.85E-6

99% 0.74 (0.57–1.1) WY101 3 Model 1 Calcite 2.20E-4 9.1 13 0.1 Runs without δ34S mineral reaction or requires 

100% of WY100 and dissolution of gypsum or precipitation of pyrite

100% 0 Model 2 Gypsum 1.20E-5 4.5 4.5 0.84

Calcite 2.46E-4CaX2 -9.14E-5NaX 1.83E-4

100% 0 Model 3 Pyrite -2.69E-6 4.28 5.3 1.83E-4

Fe(OH)3(a) 2.69E-6Calcite 2.41E-4CaX2 -9.14E-5NaX 1.83E-4

93.8% 6.2 WY72 1 Model 1 Calcite 4.39E-4 14 21 0.24 Runs without δ34S mineral reaction

CaX2 1.90E-4NaX -3.80E-4

100% 0 Model 2 Calcite 4.39E-4 12 18 0.24

MgX2 1.25E-4NaX -2.50E-4

96

% (95–98

%) 4.1 (2.4–4.6) WY75 2 Model 1 Calcite 1.85E-4 6.4 7.8 0.2 Runs without δ34S mineral reaction or requires 

dissolution of gypsum and 100% of WY100

100 0 Model 2 Gypsum 5.50E-5 8.4 8.4 0.2 Requires gypsum dissolution

Calcite 1.52E-5

96 (94.3–97.6) 4% (2.4–5.7%) WY69 1 Model 1 Pyrite -3.42E-6 9.4 12 0.2 Requires pyrite precipitation and Fe(OH)3

dissolution Fe(OH)3(a) 3.42E-6

Calcite 1.85E-4CaX2 2.03E-4NaX -4.06E-5
Summary and Conclusions 121

Inverse geochemical modeling with PHREEQC was done 

to help determine the contribution of water from different 

depths to PSW-1. Mixing of water represented by samples 

with complete major-ion data for wells adjacent to PSW-1 

was simulated without mass transfer. Two hypothetical 

models were generated (table 17). Results from the first model 

indicate that 99.2 percent of the contribution of groundwater 

to PSW-1 is composed of water represented by adjacent 

monitoring well WY100 (near the top of the PSW-1 screen) 

and that about 1 percent is composed of water from underlying 

fractured bedrock, as represented by WY106 (table 17). 

Results from the second model indicate, again, that most of 

the water (98.5 percent) is derived from flow near the top of 

the screen represented by WY100, but the other 1.5 percent 

is derived from flow at the middle of the screen represented 

by WY101. Both of these models indicate that groundwater 

chemistry is not uniform throughout the vertical extent of 

the aquifer, but is affected by the most permeable pathways. 

Furthermore, there may be no contribution from the shallow 

part of the aquifer represented by WY102 (table 17). The 

result from either model is feasible, but the two hypothetical 

mixing cases proposed may not be the only options, and water 

pumped at PSW-1 could be derived from depths and pathways 

other than those represented by samples from adjacent 

monitoring well screens. For example, the d18O and dD 

values for a water sample collected from PSW-1 plot near the 

evaporation line (fig. 25A) and indicate that the Pomperaug 

River may contribute water to well PSW-1.

The contribution of water from fractured bedrock to deep 

wells in the glacial aquifer, based on geochemical modeling 

of d34S of SO4

2− (table 16), is consistent with results of the 

groundwater-flow budget in the flow model (Starn and Brown, 

2007). Predevelopment groundwater flowing upward from 

bedrock is likely to have low or undetectable concentrations of 

anthropogenic contaminants and, given the low concentrations 

of naturally occurring contaminants in samples from PSW-1, 

lowers the vulnerability of PSW-1 to contamination.

Summary and Conclusions

A study was conducted to investigate the vulnerability of 

a public-supply well to anthropogenic and naturally occurring 

contaminants in a glacial aquifer system in Woodbury, 

Connecticut, as part of the U.S. Geological Survey National 

Water Quality Assessment (NAWQA) Program. The publicsupply well, PSW-1, is screened in the glacial aquifer and 

supplies a large portion of the locally used water. Wells in the 

glacial aquifer system are vulnerable to contamination from a 

variety of sources because of the short groundwater residence 

times and the urban land use in the contributing recharge area 

to PSW-1. Study of the vulnerability included an assessment 

of the chemical constituents in the unconsolidated glacial 

and surficial deposits, as well as the underlying and adjacent 

fractured bedrock, because these deposits and rocks can be 

sources of naturally occurring contaminants to PSW-1 as a 

result of aquifer weathering and other processes. 

Water samples were collected during 2002–06 from 

the public-supply well and from 35 monitoring wells, which 

include 25 that are screened in glacial stratified deposits, 6 that 

are screened in glacial till, and 4 in fractured bedrock. The 

chemistry of groundwater in the glacial deposits is affected 

by anthropogenic sources, including road salt, septic-tank 

drainfields, leaking underground storage tanks or chemical 

spills, stormwater runoff from roads and parking lots to dry 

wells or losing streams, and weathering of aquifer material and 

associated naturally occurring contaminants.

Abundances of organic matter can cause locally reducing 

conditions in this generally oxic aquifer system but are 

spatially limited in these glacial aquifers. Organic carbon (C) 

sources consisting of (1) natural organic matter in surface 

water in the summer and fall months; (2) natural sedimentary 

organic matter, in greater abundance in some sediments; 

and (3) point sources of contaminants, including septic-tank 

drainfields and leaking underground storage tanks can result 

in local reducing zones that affect the movement of many 

contaminants. Denitrification takes place downgradient from 

septic-tank drainfields in at least one location. Localized 

reducing zones also can affect the mobilization of trace 

elements, including arsenic (As) and uranium (U), and affect 

the degradation of volatile organic compounds (VOCs).

Bedrock composed of Paleozoic metamorphic rocks 

underlies the uplands in the eastern part of the study area, and 

Mesozoic basalt and sedimentary rocks directly underlie the 

valley. The Mesozoic-rock sequence is at least 300 meters 

thick and includes as many as three basalt layers interbedded 

with shale, arkosic sandstone, and conglomerate that dip 

eastward. Concentrations of arsenic (As) and uranium (U) in 

aquifer sediment or rock sample extractions generally were 

low and corresponded to low concentrations in groundwater. 

Glacial deposits that appear to be derived from the Mesozoic 

Cass Formation, however, contain locally abundant 

concentrations of organic C and extractable As, U, and other 

trace elements that can be mobilized in groundwater.

Concentrations of As and U in groundwater generally 

were low in the study area, which is typical of glacial aquifers 

in much of the eastern United States. Concentrations of As 

in groundwater samples ranged from less than the minimum 

reporting level (MRL) of 0.2 micrograms per liter (μg/L) 

to 5.8 μg/L. In samples from most wells, including PSW-1, 

concentrations of As were less than the MRL. The mobility of 

As appeared to be greater under relatively reducing conditions; 

samples that contained the highest dissolved As concentrations 

had low (less than 2 milligrams per liter or mg/L) dissolved 

oxygen (DO) concentrations, and (or) high dissolved iron (Fe) 

or manganese (Mn) concentrations (greater than 100 μg/L and 

greater than 50 μg/L, respectively). Some of the highest As 

concentrations in groundwater samples were contributed by 

aquifer sediments that appear to be derived from the organicrich units of the Cass Formation, probably through desorption 

of As(V) or reductive dissolution of ferric oxyhydroxides 
122 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

coupled with the oxidation of organic C and the subsequent 

mobilization of As. Water samples from several glacial-aquifer 

wells to the north and west of PSW-1 also were geochemically 

similar to the Cass Formation, and their locations are 

consistent with the southward, down-valley direction by which 

glacial deposits would have been transported by glacial ice.

Dissolved U concentrations in groundwater samples 

ranged from less than the MRL (0.2 μg/L) to 1.8 μg/L, and 

concentrations in samples from PSW-1 were about 0.06 μg/L. 

U in water generally was highest in wells in crystalline 

(Paleozoic-age) bedrock, glacial till, and in the deep glacial 

stratified deposits. Factors such as the proximity of the well 

screen to bedrock and the associated higher bicarbonate 

(HCO3

-

) concentrations and predominance of uranyl-carbonate 

complexes had a greater effect on U mobility in the aquifer 

than did redox chemistry. U concentrations in groundwater 

samples from a monitoring well (WY83) were low despite the 

high concentrations in extractions from sediments sampled 

adjacent to the screen because U typically is reduced and 

immobilized in organic-rich zones or layers. 

Radon-222 (222Rn) activities in groundwater samples 

from the Woodbury study area ranged from 490 to 

13,000 picocuries per liter (pCi/L), and all exceeded the 

proposed maximum contaminant level (MCL) of 300 pCi/L. 

The 222Rn activities in water samples from the bedrock wells 

generally were higher than other wells. The two wells in 

upland Paleozoic fractured bedrock had 222Rn activities of 

8,600 and 13,000 pCi/L, whereas wells in fractured basalt had 

lower 222Rn activities of 1,600 and 5,500 pCi/L. The median 

activity in wells screened in the glacial aquifer of the study 

area was 1,100 pCi/L, greater than the median of 440 pCi/L 

for shallow wells in other glacial aquifers of the northeastern 

United States. The high 222Rn concentrations in the glacial 

aquifer may indicate an abundant but relatively immobile mass 

of U and radium-226 on aquifer sediment surfaces but not 

dissolved in groundwater.

Experimental data for adsorption batch reactor 

experiments were modeled using PHREEQC with a 

generalized two-layer surface complexation model to 

determine adsorption reactions. Significant adsorption of 

both As and U was observed in the four glacial stratified sand 

and gravel samples, and much less sorption by the sample 

of glacial till. There was a net release of U(VI) to solution in 

the experiment with aquifer material from WY90, and it is 

possible that there was some U(VI) coprecipitated with the 

carbonate minerals in the sediment that was released. The 

net release of U(VI) from glacial till sediments experiments 

is consistent with higher concentrations of U in water 

samples from wells screened in deep glacial deposits and in 

bedrock than in those screened in shallow, carbonate-poor 

glacial deposits.

VOCs were widely detected in water samples from 

monitoring wells throughout the glacial aquifer and from 

PSW-1. VOCs were detected in samples from 89 percent 

of wells. Most VOCs were detected in water samples from 

shallow or intermediate depths of the glacial aquifer and 

were related to commercial- and light-industrial landuse areas. Eleven VOCs were detected in water from 

PSW-1: perchloroethene (PCE), 1,1,1-trichloroethane 

(TCA), trichloroethene (TCE), 1,1-dichloroethane (DCA), 

cis-1,2-dichloroethene (cis-1,2-DCE),1-dichloroethene 

(1,1-DCE), methyl-tert-butyl ether (MTBE), tert-amyl 

methyl ether (TAME), ethyl-tert-butyl ether (ETBE), 

1,1,2-trichlorotrifluoroethane (CFC-113), and chloroform. 

Several point sources are present in the commercial area 

upgradient from PSW-1, including two or more chlorinated 

solvent spills evidenced since 1978, and an MTBE plume 

discovered in 2003 that had leaked from a gasoline station. 

MTBE was the most frequently detected compound, found 

in 50 percent of wells sampled. The compounds benzene, 

toluene, ethylbenzene, xylene also were detected but at lower 

concentrations and much less frequently. Chloroform was the 

Table 17. Results of inverse geochemical modeling with PHREEQC using delta sulfur-34 to determine the 

relative contribution of groundwater to PSW-1 from various depths represented by adjacent monitoring wells 

WY102, 100, 101, and 106, in the study area, Woodbury, Connecticut.

[ID, identifier. Values in parentheses are ranges that account for uncertainty in analytical data.]

Well ID Model 1 Model 2

WY102 0 percent 0 percent

WY100 99.2 percent 

(98.4–99.9 percent)

98.5 percent 

(98.4–98.5 percent)

WY101 0 percent 1.5 percent 

(1.5–1.6 percent)

WY106 0.8 percent 

(0.1–1.6 percent)

0 percent

Sum of residuals 11 15

Sum of delta/uncertainty limit 16 23

Maximum fractional error in element concentration 0.15 0.15
Summary and Conclusions 123

second most frequently detected VOC, found in 47 percent 

of wells sampled, but concentrations in samples from all 

but two of the wells were estimated at less than the MRL. 

The presence of chloroform was attributed to the use of 

chlorinated drinking water and the associated recharge from 

septic-tank drainfields or lawn irrigation, or well disinfection. 

Chlorinated solvents were the third most frequently detected 

group of VOCs in this study and likely were used for 

degreasing, dry cleaning, and electronics manufacturing, and 

as ingredients in septic-tank cleaning products in upgradient 

residential, commercial, and light-industrial areas. Of the 

30 VOCs detected in groundwater samples, two compounds 

exceeded drinking-water standards (PCE and TCE). PCE was 

detected in 42 percent of wells sampled, and concentrations 

were highest in samples from several monitoring wells 

downgradient from the commercial area. PCE in one well 

exceeded the U.S. Environmental Protection Agency (USEPA) 

MCL of 5 μg/L at concentrations up to 11 μg/L. TCE was 

detected in samples from 33 percent of wells, with four 

of these detections exceeding the USEPA MCL of 5 μg/L 

at concentrations up to 25 μg/L. Concentrations of TCE 

exceeded the MCL in four of the six groundwater samples 

collected from PSW-1 before treatment and ranged from 

4.3 to 16 μg/L.

Pesticides were detected at relatively low concentrations 

in only a few wells in the study area. Atrazine was rarely 

detected, probably because there is little agricultural land use 

in the study area. Prometon and simazine, which are more 

soluble and mobile in water and more widely used in areas 

of mixed land use and urban land use, were detected at low 

concentrations in shallow and deep glacial wells downgradient 

from the commercial area. The insecticide fipronil was 

detected only at estimated concentrations less than the MRL 

in PSW-1 and an adjacent monitoring well. The presence of 

some compounds including fipronil and paradichlorobenzene 

(p-DCB) in samples from wells downgradient from the 

commercial area indicates a possible association with the 

upgradient commercial and industrial land-use area, and with 

associated septic-system leachate.

Tritium-helium (3H-3He) age tracers were used to 

estimate apparent groundwater ages in most wells in the 

glacial aquifer. Chlorofluorocarbons (CFCs) were used to 

date samples from two bedrock wells where excess helium-4 

(4He) precluded a 3H-3He date. Apparent groundwater ages 

are less than 9 years for water samples from glacial aquifer 

deposits but greater than 9 years in samples from bedrock 

fractures through which water moves along longer or slower 

flow paths. Apparent ages of groundwater from shallow 

bedrock wells (less than 15 m below bedrock surface) ranged 

from about 9 to 20 years and from deep bedrock wells, more 

than 50 years. The water produced at PSW-1 is derived from 

various land-use settings, but a major portion of groundwater 

is young (less than 7 years) and is derived from recharge in 

residential, commercial, and forested land-use areas.

An inverse relationship exists between estimated 

groundwater age and estimated recharge temperature in 

wells in the study area. The difference in estimated recharge 

temperatures may result from (1) warm groundwater recharge 

in the urbanized valley bottom that results from stormwater 

runoff over impervious surfaces during warm months and 

leachate from septic-tank drainfields; (2) a greater percentage 

of cool recharge that could originate in the predominantly 

forested uplands during the winter and spring rather than 

in the cleared and compacted soils of developed land at the 

valley bottom; and (3) a warming of the climate over the past 

150 years, which in turn caused higher temperatures of the 

recharge, as opposed to older groundwater that was recharged 

at colder temperatures in a cooler climate. The colder recharge 

in the past is consistent with the decrease in delta oxygen-18 

(d18O) and delta hydrogen-2 (d2H or dD) values observed with 

increasing groundwater age.

Several isotopic and other chemical tracers were 

analyzed in samples from wells in and near the modeled 

zone of contribution to help characterize the processes 

related to the source, transport, and pumping of PSW-1 that 

affect the movement of selected natural and anthropogenic 

constituents to PSW-1. The major sources and the indicative 

chemical characteristics or conditions used to identify them 

are (1) bedrock, and deep glacial stratified deposits and till, 

which affect water quality in the glacial aquifer—high pH 

and concentrations of sulfate (SO4

2−), bicarbonate (HCO3−

), 

U, 222Rn, and As relative to the concentrations in other 

wells; reducing redox conditions, enriched delta sulfur-34 

(d34S) values, depleted d18O and dD values, calcite near 

saturation, low recharge temperatures, high concentrations 

of excess 4He, and older (greater than 9 years) groundwater 

relative to the groundwater in wells screened in shallow 

and intermediate glacial stratified deposits; (2) natural 

organic matter, either in sediments or in upgradient riparian 

zones—high concentrations of DOC, Fe, and (or) Mn, and 

low concentrations of DO and (or) nitrate (NO3

−

) (reducing 

redox conditions), and enriched d34S values; (3) road salt 

(halite)—high concentrations of Na+, Cl−, and Ca2+, and 

indicative chloride/bromide (Cl:Br) mass concentration ratios; 

(4) septic-system leachate—high concentrations of NO3

−

, 

DOC, sodium (Na+), chloride (Cl−), calcium (Ca2+), and boron 

(B), delta nitrogen-15 (d 15N), and d 18O values, and indicative 

Cl:Br ratios; (5) organic solvent spills—detections of PCE, 

TCE, and 1,1-DCE; (6) gasoline station spills—detections of 

fuel oxygenates and benzene; and (7) surface-water leakage—

enriched 18O and D values, seasonally high concentrations of 

DOC, and reducing conditions.

Water in fractured bedrock in the Pomperaug Basin 

typically contains high concentrations of sulfate (SO4

2−) and 

Na, which likely results from gypsum or anhydrite dissolution 

and cation exchange. Geochemical modeling was used to 

determine the contribution of water from underlying bedrock, 

primarily using SO4

2− and d18S of SO42− as end members; 

results of the model showed a substantial (up to 6 percent) 

contribution from underlying bedrock to the glacial aquifer. 

Mixing calculations based on geochemical modeling indicate 

that the water in PSW-1 is mainly composed of water similar 
124 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

in chemistry to the water in samples from monitoring well 

WY100, screened near the top of the PSW-1 screened interval; 

minor contributions to PSW-1 were from the center of the 

screened interval and from underlying bedrock, represented 

by the chemistry of water samples from WY101. The stratified 

nature of the glacial deposits results in thin sediment layers 

that are more permeable than adjacent zones and represent 

localized pathways for groundwater flow.

The urban land use in the contributing recharge area 

to PSW-1 coupled with the young groundwater (less than 

7 years) result in a setting that is vulnerable to anthropogenic 

contamination. PSW-1 water contained low concentrations 

of the selected naturally occurring contaminants measured 

because of the overall scarcity of sources; the relatively small 

component of old water (greater than 50 years) with high 

concentrations of dissolved solids, which originated from 

underlying bedrock at this well, provides no health concern. 

There are, however, rock units outside the zone of contribution 

to PSW-1 in the Pomperaug Basin and elsewhere that contain 

high concentrations of As, U, 222Rn, Ra, Fe, Mn, and dissolved 

solids that could result in the locally high vulnerability of 

nearby supply wells completed in adjacent contributing areas 

and other glacial aquifers in the northeast. Glacial deposits 

derived from the Cass Formation in the Pomperaug Basin 

and other Newark Supergroup units in other Mesozoic basin 

settings, for example, could be sources of high As and U 

concentrations that affect drinking-water supply and may be a 

concern for human health.

Acknowledgments

The authors thank Larry Pond, Marc Taylor, Laurie 

Gianatti, Hunter Brawley, Dick Leavenworth, and several 

other members of the Pomperaug River Water Coalition who 

provided invaluable assistance with identifying historical 

land-use practices, assembling data from well-drilling records, 

and facilitating permissions or contacts for the drilling of 

monitoring wells or domestic-well sampling. They also 

coordinated meetings with the town, the State, and with local 

water companies. The authors also thank Kevin Moran and 

Gary Lord of United Water of Connecticut who generously 

provided access and historical information on public-supply 

fields, pumping, and water-quality data. Thanks go to Dave 

Monckton, director of public works for Woodbury who 

provided assistance with drilling locations and granted access 

to the old Trolley bed trail along South Brook. The authors 

appreciate USGS personnel who greatly contributed to the 

study, including, from the Connecticut Water Science Center, 

Timothy Frick, Karen Beaulieu, Jason Lewis, Justin Hudon, 

and David Bjerklie, and from the Geologic Discipline, 

Robert Zielinski, William Burton, and Janet Stone. Leon 

Kauffman provided invaluable assistance with intersecting 

particle-tracking results with GIS coverages. Finally, the 

authors thank the landowners who graciously provided access 

to their property for drilling, installation, and sampling of 

monitoring wells, or provided detailed information on their 

domestic wells. 

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134 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

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Appendix 135

Appendix

1. Depths of sediment and rock samples and description of texture and 

lithology, color, and sorting, from monitoring-well boreholes in the study 

area, Woodbury, Connecticut.................................................................................................132

2. Gamma, fluid temperature, fluid conductivity, and caliper logs, and acoustic 

traveltime, acoustic televiewer amplitude, and optical televiewer images for 

bedrock monitoring wells WY86, WY87, WY97, and WY106 in relation to depth in 

the study area, Woodbury, Connecticut ...............................................................................148

3. Quality-control summary for constituents detected in field blanks and percent 

recovery for surrogates in the study area, Woodbury, Connecticut, 2003–05 ...............152

4. Oxidation-reduction (redox) classification scheme developed for the transport of 

anthropogenic and natural contaminants to public-supply wells....................................154
136 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06 Appendix 1. Depths of sediment and rock samples and description of texture and lithology, color, and sorting, from monitoring-well boreholes in the study area, Woodbury, Connecticut.—Continued [%, percent; --, data not available; textural classification: trace, 0 to 2%; few, 2 to 5%; some, 5 to 15%; with, 15 to 30%; modifier (for example, silty), 30 to 45%; root, greater than 45%; bedrock wells shaded gray; cm, centimeters; m, meters; mm, millimeters] Well name Sampling depth below land surface (meters) Unsaturated zone (UZ) or saturated zone (SZ) Description from geologist’s log From To Texture and lithology Color1 WY69 0.0 0.6 UZ Gravelly silty sand from 0.2–0.6 m Moderate brown (5YR3/4) WY69 1.2 1.8 UZ Fine-medium sand with zone of medium-coarse sand (1.4–1.5 m), 0.3 m recovery Moderate yellowish brown (10YR5/4) WY69 1.8 2.4 UZ Fine sand (upper 3 cm of core is gravelly sand, some silt) Moderate yellowish brown (10YR5/4) WY69 2.4 3.0 UZ Fine to medium sand Moderate yellowish brown (10YR5/4) WY69 3.0 3.7 SZ Silty medium sand, few-some gravels to coarse and very coarse sand, some gravels Moderate brown (5YR4/4) to moderate yellowish brown (10YR5/4) WY69 4.6 5.2 SZ Medium sand Moderate yellowish brown (10YR5/4) WY69 6.1 6.7 SZ Gravels upper 8 cm; over medium sand (poorly sorted), some silt, few gravels, trace cobbles Dark yellowish brown(10YR4/2 to moderate yellowish brown (10YR5/4) WY69 7.6 8.2 SZ Medium sand grading to 8 cm of poorly sorted coarse and very fine sand to medium sand with granules and coarse and very coarse sand Moderate yellowish brown (10YR5/4) WY70 9.1 9.8 SZ Fine sand, some silt; grades to medium sand, trace muscovite, black mineral, some faint banding (oxide zones?); fine-medium sand at bottom Moderate brown (5YR4/4) WY69 10.7 11.3 SZ Medium sand, some coarse, very coarse, and fine sand Dark yellowish brown (10YR4/2) WY69 12.2 12.8 SZ Coarse sand with medium and very coarse sand, few pebbles ~ 5mm Moderately yellowish brown (10YR5/4) to dark yellowish brown (10YR4/2) WY69 13.7 14.3 SZ Coarse sand with medium and very coarse sand, grades to very fine sand, few-some silt, few fine sand, red-orange mottling, grades to well-sorted fine sand, some gravels (0.5–3mm) Moderately yellowish brown (10YR5/4), with red-orange mottling WY69 15.2 15.9 SZ 0–9 cm medium-coarse sand; 9–12 cm coarse sand; 12–43 cm fine-medium sand, few silt (product blebs); 43–46 cm fine- medium sand with silt Moderately yellowish brown (10YR5/4), becomes moderate brown (5YR4/4)-moderate red at 43 cm WY69 16.8 17.4 SZ Fine-medium sand, pockets of medium sand and fine sand Moderate yellowish brown (10YR5/4) WY69 18.3 18.9 SZ Fine sand and fine-medium sand Moderate yellowish brown (10YR5/4), moderate brown arkose fragments
Appendix 137

Appendix 1. Depths of sediment and rock samples and description of texture and lithology, color, and sorting, from monitoring-well boreholes in the study area, Woodbury, Connecticut.—Continued[%, percent; --, data not available; textural classification: trace, 0 to 2%; few, 2 to 5%; some, 5 to 15%; with, 15 to 30%; modifier (for example, silty), 30 to 45%; root, greater than 45%; bedrock wells shaded gray; cm, centimeters; m, meters; mm, millimeters]

Well 

name

Sampling depth 

below land 

surface 

(meters)

Unsaturated 

zone

 (UZ) 

or saturated 

zone 

(SZ)

Description from geologist’s log

From To Texture and lithology Color1

WY69 19.8 20.4 SZ Medium sand with pockets of crumbly rock (arkose/sandstone) 

and pockets of gray clay; bedrock at 20.4 m

Moderate yellowish brown (10YR5/4)

WY72 0.0 0.6 UZ Organic-rich upper 13 mm clayey medium sand, some silt; grades 

to same as above, few gravels up to 3 cm

Moderate brown (5YR3/4) grades to moderate yellowish brown 

(10YR5/4)

WY72 0.6 1.2 UZ Fine-medium sand with gravels up to 38 mm (quartz, etc.) Moderate yellowish brown (10YR5/4)WY72 1.2 1.5 UZ Medium sand, some gravels (up to 51 mm, incl. gneiss cobble), 

trace to some silt

Moderate brown (10YR) grades to moderate yellowish brown 

(10YR5/4)

WY72 1.2 1.8 UZ Medium sand, trace to some silt, some gravel Moderate brown (5YR3/4) grades to moderate yellowish brown 

(10YR5/4)

WY72 1.5 2.1 UZ Upper 0.076 m rock chunks overlies 0.06 m of medium sand 

overlies .076 m of pea-sized gravel, overlies silty sand (same as above interval, with granules in lower .076 m)

Moderate reddish brown rock chunks in upper .076 m, overlies 

moderate yellowish brown

WY72 2.1 2.4 SZ Fine-medium sand Moderate brown (5YR3/4) grades to moderate yellowish brown 

(10YR5/4)

WY72 3.0 3.7 SZ Upper 10 cm medium sand, few gravels, grades to 12 cm medium 

sand, well sorted, to medium-coarse sand with very coarse sand, overlies 10 cm gravelly coarse and very coarse sand

Moderate brown (5YR3/4)

WY72 4.6 5.2 SZ Medium sand upper 23 cm, coarse and very coarse sand, some 

pebbles lower 23 cm

Moderate yellowish brown in upper 46 cm, lower 3 cm, moderate 

brown sandstone

WY72 6.1 6.7 SZ Pea-sized gravels of quartz, feldspar, sandstone, metamorphic 

over poorly sorted medium sand, some gravels up to 25 mm; lower 76 mm, fine-medium sand

Moderate brown (5YR4/4) to moderate yellowish brown 

(10YR4/2)

WY72 7.6 8.2 SZ Gravelly medium-coarse sand, poorly sorted, some silt in pockets, 

gravels up to 51 mm diameter

Moderate brown (5YR4/4) 

WY72 9.1 9.8 SZ Coarse sand in upper 76 cm, overlies medium sand Moderate brown (5YR4/4)WY72 10.7 11.3 SZ Coarse sand, some gravels upper 76 cm, overlies fine sand 10 cm, 

overlies fine sand some silt and coarse sand in lower 10 cm

Moderate brown (5YR3/4) grades to moderate yellowish brown 

(10YR5/4)

WY72 12.2 12.8 SZ Fine-very coarse sand, few gravels upper 12 cm; grades to 

medium sand, some silt, gravels up to 25 mm, laminae evident, some orange mottling (appears of granitic origin)

Dark yellowish brown (10YR4/2); orange mottling near bottom
138 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06 Appendix 1. Depths of sediment and rock samples and description of texture and lithology, color, and sorting, from monitoring-well boreholes in the study area, Woodbury, Connecticut.—Continued [%, percent; --, data not available; textural classification: trace, 0 to 2%; few, 2 to 5%; some, 5 to 15%; with, 15 to 30%; modifier (for example, silty), 30 to 45%; root, greater than 45%; bedrock wells shaded gray; cm, centimeters; m, meters; mm, millimeters] Well name Sampling depth below land surface (meters) Unsaturated zone (UZ) or saturated zone (SZ) Description from geologist’s log From To Texture and lithology Color1 WY72 13.7 14.3 SZ Very coarse sand with gravel (<6 mm) Moderate brown WY72 15.2 15.9 SZ Coarse-very coarse sand in upper 12 cm; overlies fine sand, very well sorted Moderate yellowish brown (10YR5/4)overlies dark yellowish brown (10YR4/2) WY72 16.8 17.4 SZ Coarse-very coarse sand with gravels (mainly pea size); overlies 23 cm fine-medium sand, well sorted Dark yellowish brown(10YR4/2 WY72 18.3 18.9 SZ Medium sand (muscovite abundant) grades to weathered arkose, becomes competent in lower 9 cm Pale yellowish brown grades to dark gray (N3) WY72 18.6 18.9 SZ Bedrock Dark gray (N3) WY75 0.0 0.6 UZ Fine sandy silt, organic matter and roots in upper 15 cm Dark brown (10YR4/2) WY75 0.6 1.2 UZ Medium sand, with to some gravel, trace clay and silt Moderate yellowish brown (10YR5/4) with 6 mm layers of grayish brown (10YR7/7) at 88 cm and 94 cm. WY75 1.2 1.8 UZ Gravelly medium-coarse sand, trace silt, trace to few clay in spots Dark yellowish brown (10YR4/2) WY75 1.8 2.4 SZ Gravelly medium-coarse sand, trace-some silt, trace to few clay in spots Moderate brown (5YR3/4) WY75 3.0 3.7 SZ Fine-medium sand in upper 10 cm; silty medium sand, trace clay, gravels of shale(?) and weathered rock Moderate yellowish brown, grades to moderate brown WY75 4.6 5.2 SZ Gravels (well rounded feldspar gneiss, schist, large quartzite) poor recovery (cobble blocked) Dark yellowish brown(10YR4/2) WY75 6.1 6.7 SZ Medium sand upper 8 cm, over fine sand Moderate brown (5YR4/4) (reddish clay entrained in water) WY75 7.6 8.2 SZ Medium sand, few gravels up to 2 cm (quartzite, etc.); over fine well sorted sand, some dark minerals Dark yellowish brown; moderate brown (5YR4/4) band at 23 –26 cm WY75 9.1 9.8 SZ Coarsening upward sequence of coarse and very coarse sand up to gravel (quartz, feldspar, gneiss) Pale-moderate yellowish brown WY75 10.7 11.3 SZ Coarsening upward sequence up to coarse sand, some very coarse sand Pale-moderate yellowish brown WY75 12.2 12.8 SZ Coarsening upward sequence from fine-medium sand to medium- coarse sand, trace-few gravels up to 15 mm up to coarse sand, some very coarse sand Moderate yellowish brown to dark yellowish brown; orange band at 12.4 m WY75 13.7 14.3 SZ Medium sand, trace gravels Moderate dark yellowish brown; faint orange mottling

WY75 15.2 15.9 SZ Coarse and very coarse sand 0.1 m, grades down to fine sand Moderate brown (red looking) grades to dark brown (looks more 

reduced)
Appendix 139

Appendix 1. Depths of sediment and rock samples and description of texture and lithology, color, and sorting, from monitoring-well boreholes in the study area, Woodbury, Connecticut.—Continued[%, percent; --, data not available; textural classification: trace, 0 to 2%; few, 2 to 5%; some, 5 to 15%; with, 15 to 30%; modifier (for example, silty), 30 to 45%; root, greater than 45%; bedrock wells shaded gray; cm, centimeters; m, meters; mm, millimeters]

Well 

name

Sampling depth 

below land 

surface 

(meters)

Unsaturated 

zone

 (UZ) 

or saturated 

zone 

(SZ)

Description from geologist’s log

From To Texture and lithology Color1

WY75 16.8 17.2 SZ Medium sand Moderate yellowish brown (10YR5/4) to dark yellowish brown 

(10YR4/2) 

WY75 17.2 17.4 SZ Till; gravelly silt and sand, trace-few clay, very compact, hard Grayish brown (5YR3/4)WY77 0.0 0.6 UZ Medium sandy loam (upper 15 cm) grades to gravelly medium 

sand, trace silt

Dark yellowish brown (10YR4/2)

WY77 0.6 1.2 UZ Silty medium sand to medium sand some silt, few clay; grades to 

gravelly medium sand

Grayish brown (5YR3/4) grades to moderate yellowish brown

WY77 1.2 1.8 UZ Gravelly sand (fill) Moderate yellowish brown (10YR5/4) to very pale orange 

(10YR6/2) (crushed concrete??)

WY77 1.8 2.4 UZ Gravelly medium sand (fill) Moderate yellowish brown (10YR5/4)WY77 3.0 3.7 SZ Gravelly medium-coarse sand Moderate yellowish brown (10YR5/4)WY77 4.6 5.2 SZ Medium-coarse sandy gravel, some-few silt, trace-few clay; large 

cobble in lower 75 mm

Moderate yellowish brown to dark yellowish brown

WY77 6.1 6.7 SZ Medium sand becomes gravelly Medium sand at 6.6 m (25-mm 

thick red arkose layers at 10 cm and 15 cm; at 6.4 m, weathered grayish green shale); granite cobble in shoe

Moderate yellowish brown (10YR5/4), with layers of light red 

(5y6/6) and grayish green (5G5/2)

WY77 7.6 8.2 SZ Fine-medium sand upper 10 cm; gravel of arkose at 12 cm, blow 

that, medium-coarse sand with gravel

Dark yellowish brown (10YR4/2) grades to moderate yellowish 

brown (10YR5/4); arkose gravel moderate (5R4/6) to dusky red (5R3/4)

WY77 9.1 9.8 SZ Fine-medium sand; lower 8 cm grades from very fine sand, few 

silt and silty very fine-fine sand back to fine-medium sand in end of shoe

Dark yellowish brown (10YR4/2) grades to moderate yellowish 

brown (10YR5/4) in lower 27 cm

WY77 10.7 11.3 SZ Gravelly very coarse sand in upper 8 cm, then medium-coarse 

sand grading to fine-medium sand

Moderate yellowish brown (10YR5/4)

WY77 12.2 12.8 SZ Medium sand, with zone of medium sand, some gravel (up to 

8-mm diameter)

Moderate yellowish brown (10YR5/4) to dark yellowish brown 

(10YR4/2)

WY77 13.7 14.3 SZ Fine-medium sand upper 10 cm; changes to gravelly medium 

sand, grades to fine-medium sand in end of shoe

Moderate yellowish brown (10YR5/4) to dark yellowish brown 

(10YR4/2)

WY77 15.2 15.9 SZ Very coarse sand, few gravels upper 10 cm, fine sand below that Moderate yellowish brown (10YR5/4)
140 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06 Appendix 1. Depths of sediment and rock samples and description of texture and lithology, color, and sorting, from monitoring-well boreholes in the study area, Woodbury, Connecticut.—Continued [%, percent; --, data not available; textural classification: trace, 0 to 2%; few, 2 to 5%; some, 5 to 15%; with, 15 to 30%; modifier (for example, silty), 30 to 45%; root, greater than 45%; bedrock wells shaded gray; cm, centimeters; m, meters; mm, millimeters] Well name Sampling depth below land surface (meters) Unsaturated zone (UZ) or saturated zone (SZ) Description from geologist’s log From To Texture and lithology Color1 WY77 16.8 17.4 SZ Very fine sand, few silt and fine sand, trace gravels (5–10 mm) Moderate yellowish brown (10YR5/4) WY77 18.3 18.9 SZ Medium sand, pockets of silt/clay and broken rotten rock including fragments of grayish green 5G5/2 basalt, some resembles shale Moderate yellowish brown (10YR5/4), rock fragments of grayish green (5G5/2) WY77 0.0 19.2 SZ No core sample--rock -- WY79 0.0 0.6 UZ Loam grades to medium sand, few gravels Grayish brown grades to light brown WY79 0.6 1.2 UZ Gravelly medium sand Pale (10YR6/2)-moderate yellowish brown (10YR5/4) WY79 1.2 1.8 UZ Gravelly medium sand Pale yellowish brown (10YR6/2) to moderate yellowish brown (10YR5/4) WY79 1.8 2.4 SZ Gravelly medium sand with very coarse sand Moderate brown(5YR3/4 to grayish brown (5YR3/2) WY79 3.0 3.7 SZ Very fine sand, some silt, few clay Pale yellowish brown (5YR5/6) WY80 0.0 0.6 UZ Gravelly medium sand, few silt Dark yellowish brown (10YR4/2) WY80 0.6 1.2 UZ Medium sand with gravels, some silt, boulders (difficult drilling 0.9–1.5 m) Dark yellowish brown (10YR4/2) WY80 1.2 1.8 UZ Gravelly medium sand, trace-some silt, few or no clay (gravel blocked recovery) Moderate brown (5YR4/4) WY80 1.8 2.4 UZ Gravelly medium sand, pockets of same with few silt Moderate yellowish brown (10YR5/4) to dark yellowish brown (10YR4/2) WY80 2.4 3.0 UZ Boulders--difficult drilling WY80 3.0 3.7 UZ Medium sand, some gravels, few-some silt Dark yellowish brown (10YR4/2) WY80 3.7 4.3 UZ/SZ Gravelly medium-coarse sand, some silt, trace clay in pockets Dark yellowish brown (10YR4/2) WY81 0.0 0.6 UZ Medium-coarse sand, few-trace silt Moderate brown(5YR3/4 to dark yellowish brown (10YR4/2) WY81 0.6 1.2 UZ Medium sand with gravels Dark yellowish brown (10YR4/2) WY81 1.2 1.8 UZ Fine-medium sand with poorly sorted gravels up to 51 mm; grades to gravelly coarse sand in shoe Moderate yellowish brown (10YR5/4) WY81 1.8 2.4 UZ Medium-coarse sand with gravels Dark yellowish brown(10YR4/2) grades to moderate yellowish brown (10YR5/4) WY81 2.4 3.0 UZ Medium sand, well sorted, grades at 46 cm to medium-coarse 

sand with gravel

Moderate yellowish brown (10YR5/4) 
Appendix 141

Appendix 1. Depths of sediment and rock samples and description of texture and lithology, color, and sorting, from monitoring-well boreholes in the study area, Woodbury, Connecticut.—Continued[%, percent; --, data not available; textural classification: trace, 0 to 2%; few, 2 to 5%; some, 5 to 15%; with, 15 to 30%; modifier (for example, silty), 30 to 45%; root, greater than 45%; bedrock wells shaded gray; cm, centimeters; m, meters; mm, millimeters]

Well 

name

Sampling depth 

below land 

surface 

(meters)

Unsaturated 

zone

 (UZ) 

or saturated 

zone 

(SZ)

Description from geologist’s log

From To Texture and lithology Color1

WY81 3.0 3.7 UZ Gravelly medium sand, grades to medium sand with gravels Moderate brown (5YR3/4) grades to moderate yellowish brown 

(10YR5/4), grades to light brown (5YR5/6)

WY81 3.7 4.3 UZ Gravelly medium-coarse sand Moderate yellowish brown (10YR5/4) to moderate brown 

(5YR4/4)

WY81 5.5 6.1 SZ Medium sand, few-some very coarse and coarse sand, few-some 

gravel up to 51 mm (metamorphic)

Moderate yellowish brown (10YR5/4)

WY81 7.3 7.9 SZ Fine-medium sand grades to very fine sand at bottom of shoe Moderate brown (5YR4/4)WY81 8.8 9.5 SZ Coarse-very coarse sand, some small gravels~2mm in upper 

30mm; next 12 cm fine-medium sand; next 0.10 m coarse sand, some very coarse sand and small gravels; grades to very finefine sand in bottom of shoe

Moderate yellowish brown (10YR5/4)

WY81 10.4 11.0 SZ Medium sand, few gravels in upper 26 cm; overlies 5 cm of 

gravels; then 15 cm of medium sandy gravel/gravelly sand

Pale-moderate yellowish brown

WY82 12.2 12.8 SZ Medium-coarse sand, few-some silt (pockets), gravels of gneiss 

(quartz rich)

Dark yellowish brown(10YR4/2) 

WY82 13.7 14.3 SZ Medium sand grades to gravel and sand (moderately sorted 

granules) to gravelly medium sand, some silt (in pockets); quartzite cobble

Moderate yellowish brown (10YR5/4)

WY82 15.2 15.9 SZ Gravelly sand, some silt/sandy gravel, few silt; some gravels (up 

to 25 mm) rounded

Dark yellowish brown(10YR4/2) 

WY82 16.8 17.4 SZ Medium-very coarse sandy gravel (all granules sized) to 16.8 m; 

fine-medium sand with silt and clay to 16.9 m; gneiss gravel in shoe

Dark yellowish brown(10YR4/2) to moderate yellowish brown 

(5YR5/4)

WY82 18.3 18.9 SZ Hard gravel, sand, silt, and clay and fragments of rock (basalt?) Moderate yellowish brown (10YR5/4) with reddish dark brown 

rock

WY82 19.8 20.4 SZ Weathered rock --WY83 0.0 0.6 UZ Gravelly medium-coarse sand, some silt, trace-few clay Moderate brown (5YR4/4)WY83 1.5 2.1 UZ Gravelly medium sand, trace-few silt Dark yellowish brown (10YR4/2)WY83 3.0 3.7 UZ Gravelly medium sand, trace-few silt Dark yellowish brown (10YR4/2)WY83 4.6 5.2 UZ Gravel-blocked--no recovery --
142 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06 Appendix 1. Depths of sediment and rock samples and description of texture and lithology, color, and sorting, from monitoring-well boreholes in the study area, Woodbury, Connecticut.—Continued [%, percent; --, data not available; textural classification: trace, 0 to 2%; few, 2 to 5%; some, 5 to 15%; with, 15 to 30%; modifier (for example, silty), 30 to 45%; root, greater than 45%; bedrock wells shaded gray; cm, centimeters; m, meters; mm, millimeters] Well name Sampling depth below land surface (meters) Unsaturated zone (UZ) or saturated zone (SZ) Description from geologist’s log From To Texture and lithology Color1 WY83 5.2 5.8 UZ Fine sand Pale yellowish brown (10YR6/2) to moderate yellowish brown (10YR5/4) WY83 6.1 6.7 SZ Medium sand (moderate brown) few-some silt Moderate olive brown (5YR4/4) to dark yellowish brown 10YR4/2 WY83 7.6 8.2 SZ 7.8–8.1 silty medium sand, moderate brown 5YR4/4; layer at 7.8 m of blackish red 5Y2/2 medium sand and granules; 8.08–8.14 very fine sandy silt, few clay, light olive gray 5Y5/2 Dark yellowish orange (10YR6/6) to moderate yellowish brown (10YR5/4) silty sand with layer of fine clayey silt with sand (10YR4/2); layer at 7.8 m of blackish red 5Y2/2 medium sand and granules WY84 0.0 0.6 UZ Fine to medium sand, some granules, few-some silt Dusky yellowish brown (10YR2/2) WY84 1.2 1.8 UZ Medium sand with granules and gravel (arkose); some silt Dark yellowish brown (10YR4/2) WY84 2.7 3.4 UZ Gravelly fine-medium sand, few-some silt Moderate yellowish brown (10YR5/4) WY84 3.4 4.0 UZ Gravelly fine-medium sand, some-with silt, gravels up to 51 mm diameter Moderate brown(5YR4/4 to dark reddish brown (10YR3/4) WY84 4.6 5.2 SZ Fine-very coarse sand and gravel with silt, few-trace clay (likely fill); bottom 0.03-m silt content decreased to “trace-few” Dark yellowish brown (10YR4/2) to pale yellowish brown to moderate yellowish brown and 3 cm layer of moderate reddish brown (arkose) WY84 6.1 6.7 SZ Gravelly medium-coarse and, band of light brown fine-medium sand @.046 m down Moderate yellowish brown (10YR5/4) WY84 7.6 8.2 SZ Medium sandy gravel and layer of medium-coarse sand at 12 cm down; gravels of striated quartzite in lower 61 cm Moderate yellowish brown (10YR5/4) to dark yellowish brown (10YR4/2) WY84 9.1 9.8 SZ Medium sand with gravel/gravelly Medium sand, trace to some silt, trace clay with reddish brown pocket Moderate yellowish brown (10YR5/4) to dark yellowish brown (10YR4/2) WY84 10.7 11.3 SZ Medium sand grades to gravelly medium sand Dark yellowish brown (10YR4/2) WY84 12.2 12.8 SZ Fine-medium sand Dark yellowish brown (10YR4/2) WY84 13.7 14.3 SZ Medium sand 9 cm; 9–21 cm fine-Medium sand, grades to medium-coarse sand with granules and small gravels (shaley fragment has pyrite appearance) Moderate yellowish brown (10YR5/4) WY84 15.2 15.9 SZ Gravelly medium sand with gravels, some silt, grades to medium sand Moderate yellowish brown (10YR5/4) grades to dark yellowish brown (10YR4/2)

WY84 16.8 17.4 SZ Fine-medium sand, lower 6 cm is fine sand, well sorted Moderate yellowish brown (10YR5/4) 
Appendix 143

Appendix 1. Depths of sediment and rock samples and description of texture and lithology, color, and sorting, from monitoring-well boreholes in the study area, Woodbury, Connecticut.—Continued[%, percent; --, data not available; textural classification: trace, 0 to 2%; few, 2 to 5%; some, 5 to 15%; with, 15 to 30%; modifier (for example, silty), 30 to 45%; root, greater than 45%; bedrock wells shaded gray; cm, centimeters; m, meters; mm, millimeters]

Well 

name

Sampling depth 

below land 

surface 

(meters)

Unsaturated 

zone

 (UZ) 

or saturated 

zone 

(SZ)

Description from geologist’s log

From To Texture and lithology Color1

WY84 18.3 18.9 SZ Cobble over very fine sand Moderate yellowish brown (10YR5/4) WY84 19.8 20.4 SZ Fine sand, very well sorted, and 1–3 mm blobs of product?WY84 21.3 22.0 SZ Fine-medium sand with cobbles (basalt) in spoon; layers of 

granules, very coarse and coarse sand at 3 cm and 30 cm

Moderate yellowish brown (10YR5/4) 

WY84 22.4 22.5 SZ Weathered basalt and some silty sand Greenish black (5G2/1)WY86 5.1 5.5 SZ Gneiss with yellowish gray quartzite bands; specks of pyrite (?) 

observed on outside of core

Dark gray with yellowish gray quartzite bands

WY86 5.5 7.1 SZ Gneiss with phyllite, tremolite/glauconite? And soft grayish 

yellow green (5GY7/2) near bottom (faulted/fractured zone) and dark gray schist

Dark gray and zone of grayish yellow green (5GY7/2) near 

bottom

WY86 6.9 7.0 SZ Gneiss and schist with phyllite/tremolite/glauconite Dark gray (N3) with zones of grayish yellowish green (5GY7/2) WY86 7.1 8.4 SZ Biotite-rich sand at top, becoming schistose/gneiss with zone of 

green (glauconite?), greenish clay silt on fracture surfaces

Dark gray (N3), greenish clay silt on fracture surfaces

WY86 8.4 9.6 SZ Gneiss with steep fractures (~70 deg dip and foliations 

(“bedding”)

Dark gray (N3) 

WY86 9.6 11.6 SZ Schist/gneiss Dark gray (N3) WY86 11.6 13.2 SZ Biotite/chlorite schist in upper 0.52 m; 2 soft/crumbly micaceous 

zones; .52 –1.5 m pegmatitic (chlorite layer at contact), large crystals of calcite and sodic feldspar, quartz, clumps and layers of mafic mineral

Dark gray (N3) 

WY86 13.2 14.7 SZ Pegmatite with iron oxide coatings on fracture surfaces (grains 

of quartz, K and Na feldspar, biotite, and mafic mineral [amphibole?], crystals about 1-cm diameter on average

Dark gray (N3) 

WY86 14.7 16.2 SZ Pegmatite with couple zones of fractures with Fe oxide coatings Dark gray (N3) WY86 15.8 15.8 SZ Pegmatite with iron oxide coatings on fracture surfaces (grains 

of quartz, K and Na feldspar, biotite, and mafic mineral [amphibole?], crystals about 1-cm diameter on average

Medium-dark gray (N4) but coarse grains vary

WY86 16.2 17.1 SZ Pegmatite, somewhat fractured (probably mostly from drilling 

process, but we are losing some water and some oxidation evident in one or two places

Medium-dark gray (N4) but coarse grains vary

WY86 17.1 17.7 SZ Pegmatite, somewhat fractured, we are losing more water Medium-dark gray (N4) but coarse grains vary
144 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06 Appendix 1. Depths of sediment and rock samples and description of texture and lithology, color, and sorting, from monitoring-well boreholes in the study area, Woodbury, Connecticut.—Continued [%, percent; --, data not available; textural classification: trace, 0 to 2%; few, 2 to 5%; some, 5 to 15%; with, 15 to 30%; modifier (for example, silty), 30 to 45%; root, greater than 45%; bedrock wells shaded gray; cm, centimeters; m, meters; mm, millimeters] Well name Sampling depth below land surface (meters) Unsaturated zone (UZ) or saturated zone (SZ) Description from geologist’s log From To Texture and lithology Color1 WY86 17.7 19.3 SZ Pegmatite, coarser near bottom, micaceous surfaces at fractures (chlorite); Fe coatings Medium-dark gray (N4) but coarse grains vary WY86 19.3 20.8 SZ Pegmatite, with finer grained and gray 10 cm band near bottom Medium-dark gray (N4) but coarse grains vary WY86 20.8 22.3 SZ Pegmatite Medium-dark gray (N4) but coarse grains vary WY86 22.3 23.8 SZ Pegmatite, high-angle fractures (propagated by drilling but break only along micaceous layers (chlorite? slippery) Medium-dark gray (N4) but coarse grains vary WY86 23.8 25.4 SZ Pegmatite, only 7 large chunks with 12 cm band (dipping 70 degrees) of medium-dark gray finer grains; pyrite crystals Medium-dark gray (N4) but coarse grains vary WY86 25.4 26.9 SZ Pegmatite, with similar finer-grained band at top of core Medium-dark gray (N4) but coarse grains vary WY86 26.9 28.4 SZ Pegmatite Medium-dark gray (N4) but coarse grains vary WY86 28.4 29.9 SZ Pegmatite with medium-dark gray fine-grain bands (25–51 mm) near top, and TRANSITION to biotite schist in lower 61 cm Medium-dark gray (N4) but coarse grains vary WY86 29.9 31.5 SZ Biotite schist becomes light colored (brecciated) 51 mm larger grained, then back to biotite schist with 11 cm thick band of light gray (N7)--calcic?, with horizontal contacts Medium-dark gray (N4) but coarse grains vary WY87 9.1 9.3 SZ -- WY87 11.3 11.9 SZ Basalt, shaley, overlain by crushed basalt granules Medium bluish gray (SB5/1) WY87 11.8 12.2 SZ Basalt with 1–30 mm veins (horizontal and steeply dipping) of light gray quartz or calcite and grayish green mineral (prehnite or glauconite) Dark gray (N3) to grayish black (N2), veins of light gray or grayish green (5G5/2) WY87 12.2 12.4 SZ Same as above, with vuggy porosity Same as above WY87 12.7 14.7 SZ Same as above, but less porosity and more fractures (probably during removal from barrel) Same as above WY87 14.7 16.2 SZ Basalt with fractures filled with calcite and green/black mineral; recovered from barrel essentially unbroken -- WY87 16.2 17.1 SZ Basalt with large vugs filled with white and light green phenocrysts; only 0.9 m of 1.5 m core retrieved Dark gray (N3) to grayish black (N2), veins of light gray or grayish green (5G5/2) WY87 17.1 17.7 SZ Large vug fillings/phenocrysts of white and light green minerals Save as above WY87 17.7 20.1 SZ Reddish zone has coarse grains up to 3 mm diameter Reddish colored zone from 57–57.3
Appendix 145

Appendix 1. Depths of sediment and rock samples and description of texture and lithology, color, and sorting, from monitoring-well boreholes in the study area, Woodbury, Connecticut.—Continued[%, percent; --, data not available; textural classification: trace, 0 to 2%; few, 2 to 5%; some, 5 to 15%; with, 15 to 30%; modifier (for example, silty), 30 to 45%; root, greater than 45%; bedrock wells shaded gray; cm, centimeters; m, meters; mm, millimeters]

Well 

name

Sampling depth 

below land 

surface 

(meters)

Unsaturated 

zone

 (UZ) 

or saturated 

zone 

(SZ)

Description from geologist’s log

From To Texture and lithology Color1

WY87 20.1 21.6 SZ Grayish red with coarse grains, changes to olive black with small 

phenocrysts

Grayish red (10R4/2) changes to olive black with small 

phenocrysts

WY87 21.6 23.1 SZ Coarse phenocrysts with fine ground mass and filled vugs 

(calcite?)

Grayish red (10R4/2)

WY88 0.6 1.5 UZ Drill cuttings: gravels --WY88 1.5 -- UZ Drill cuttings: fine-medium sand, few-some silt, trace clay, some 

gravels

--

WY88 3.0 -- SZ Drill cuttings: gravelly sand, few-some silt Light olive gray (5Y5/2)WY88 4.6 -- SZ Drill cuttings: gravelly sand, few-some silt Moderate olive brown (5Y4/4)WY88 6.1 -- SZ Drill cuttings: gravelly fine-coarse sand, gravels up to 8 cm Moderate olive brown (5Y4/4)WY88 7.6 -- SZ Gravelly fine-coarse sand, gravels up to 8 cm Moderate olive brown (5Y4/4)WY88 9.1 -- SZ Medium-coarse sand and granules, small gravels --WY88 10.7 11.3 SZ Medium sand grades to fine sand, some silt, trace-few clay, and 

weathered gravels of biotite schist

Light olive gray (5Y5/2)

WY88 11.6 12.2 SZ Very coarse sand (could be wash) overlies gravelly fine sand and 

chunks of weathered rock (red rock and schist) and zones of silty sand, trade clay

Moderate yellowish brown (10YR5/4) 

WY88 14.6 15.2 SZ Fine-medium sand, moderately well sorted overlies fine-coarse 

sand with gravels, few-some silt

Grayish brown (5Y3/2)-medium brown (5YR3/4)

WY88 15.5 15.6 SZ Fine-medium sand overlies schist/gneiss Moderate yellowish brown (10YR5/4) sand over rockWY35 0.0 0.9 UZ Soil (sandy loam) --WY35 0.9 2.1 UZ Gravel; pebbles to cobbles, and fine-coarse sand --WY35 2.1 3.0 SZ Sand, fine-coarse, and gravel; some very coarse sand, some v fine 

sand, and silt

--

WY35 3.0 6.4 SZ Sand, f-med; some v fine sand, some coarse-very coarse sand and 

gravel, little silt

--

WY35 6.4 15.5 SZ Sand, f-coarse, and gravel; some v fine sand, some silt --WY35 15.5 15.9 SZ Till --
146 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06 Appendix 1. Depths of sediment and rock samples and description of texture and lithology, color, and sorting, from monitoring-well boreholes in the study area, Woodbury, Connecticut.—Continued [%, percent; --, data not available; textural classification: trace, 0 to 2%; few, 2 to 5%; some, 5 to 15%; with, 15 to 30%; modifier (for example, silty), 30 to 45%; root, greater than 45%; bedrock wells shaded gray; cm, centimeters; m, meters; mm, millimeters] Well name Sampling depth below land surface (meters) Unsaturated zone (UZ) or saturated zone (SZ) Description from geologist’s log From To Texture and lithology Color1 WY89 1.2 1.8 UZ 0–12 cm fine-medium sand, some gravels up to 1.5cm; 12–23 cm cobbles, weathered (metamorphic with large muscovite-- schistose) Dark yellowish brown (10YR5/4) WY89 3.0 3.7 UZ Gravelly very fine-very coarse sand, few silt, gravels up to 2.5 cm (quartzite gravel) Dark yellowish brown (10YR5/4) WY89 5.2 5.8 UZ Fine-very coarse sandy gravel, some silt Moderate brown 5YR3/4 WY89 6.1 6.7 SZ Medium sand, well sorted, grades to medium sand, some gravel and very coarse sand Moderate yellowish brown to dark yellowish 10YR5/4 to dark yellowish brown 10Y4/2 near bottom WY89 7.3 7.9 SZ Fine to very coarse sandy gravel, gravelly sand; lower 6 cm greenish basalt in lower 5 cm (part of boulder) Dark yellowish brown over olive gray to grayish olive green (basalt) WY89 9.1 9.8 SZ 0–61 cm gravels of granite; over 12 cm silty fine sand, few clay (till) Moderate brown (5YR4/4) WY89 10.7 11.3 SZ Silt and very fine-fine sand with gravels of granite, arkose, weathered basalt (with white clay alteration mineral, possibly sericite) Moderate brown (5YR4/4) WY90 6.7 7.3 SZ Very compact fine-medium sand, some clay, few silt, some gravels (up to 4 cm) grades to silty fine-medium sand, some gravels, trace clay; gravels are freshly broken basalt (olive gray) [top 61 cm were gravelly medium-coarse sand--may be slough] Moderate brown (5YR3/4) grades to moderate yellowish brown (10YR5/4) WY91 1.2 1.8 SZ Fine-medium sand, some coarse and few very coarse sand, few silt Moderate yellowish brown 10YR5/4 WY91 2.7 3.4 SZ Silty fine sand; near bottom is a 2-mm horizon of muscovite-rich very coarse-coarse sand and small gravels (quartz); at bottom 30 cm becomes medium-very coarse sandy gravel Dark yellowish brown 10YR4/2 grades to moderate brown 5YR3/4 WY91 4.3 4.9 SZ Fine sand and fine-medium sand, some silt Moderate brown 5YR3/4 until 4.4 m, then moderate brown 10YR4/4 WY91 5.8 6.4 SZ Fine-medium sand; 76 cm becomes coarse-very coarse sandy gravel (gravels of metamorphic, green basalt) some laminae evident, some dark colored blebs (organic matter or organics); shoe--lower 6 cm very coarse sandy gravel, pockets of reddish silt Moderate brown 10YR4/4; silt is dark reddish brown 10R3/4 to light brown 5YR4/4 (gravel)
Appendix 147

Appendix 1. Depths of sediment and rock samples and description of texture and lithology, color, and sorting, from monitoring-well boreholes in the study area, Woodbury, Connecticut.—Continued[%, percent; --, data not available; textural classification: trace, 0 to 2%; few, 2 to 5%; some, 5 to 15%; with, 15 to 30%; modifier (for example, silty), 30 to 45%; root, greater than 45%; bedrock wells shaded gray; cm, centimeters; m, meters; mm, millimeters]

Well 

name

Sampling depth 

below land 

surface 

(meters)

Unsaturated 

zone

 (UZ) 

or saturated 

zone 

(SZ)

Description from geologist’s log

From To Texture and lithology Color1

WY91 7.3 7.9 SZ Fine-very fine sand, few silt; 0–1.1 m becomes fine-medium sand, 

some dark colored blebs (organic matter or product?) in sand

Moderate reddish brown (10YR6; becomes moderate yellowish 

brown 10YR5/4 at 1.1 m

WY91 8.8 9.5 SZ Fine-medium sand, some coarse sand, few gravels up to 1cm with 

2 zones of gravelly fine-medium sand; 23 cm, becomes medium sand, some coarse sand; lower 3 cm fine sand

Moderate yellowish brown (10YR5/4), becomes moderate-dark 

yellowish brown in lower 0.03 m

WY91 10.4 11.0 SZ Fine-medium sand [9–12 cm zone of gravel with layer of silty 

very fine sand below it]; 21 cm coarse -very coarse sand some granules; lower 6.1 cm medium-coarse sandy gravels (up to 2.5cm, few-some silt in one small zone

Moderate yellowish brown (10YR5/4)

WY91 11.9 12.5 SZ 0–9 cm fine-medium sand, becomes coarse-very coarse sand with 

gravels up to 1.5 cm; lower 3 cm becomes medium sand

Dark yellowish brown (10YR6/6)

WY91 13.4 14.0 SZ 0–26 cm medium sand with 2 zones of sandy gravel (granules); 

changes to fine-medium sand (with layer of dark reddish brown 10R3/4); grades to fine-very fine sand at bottom

Moderate-yellowish brown (10YR5/4)

WY91 14.9 15.5 SZ 0–6 cm gravel, some medium-very coarse sand; 6–12 cm finemedium sand; 12–18 cm fine sand Moderate brown (5YR3/4) becomes moderate-yellowish brown (10YR5/4)WY91 16.5 17.1 SZ 0–9 cm coarse sandy gravel; 9–33 cm fine sand, trace silt; 14–33 

cm medium-very coarse sand (some granules of quartz, muscovite) well sorted with small pocket of orange color

Pale yellowish brown to dark yellowish brown (10YR6/2 

-10YR4/2)

WY91 18.0 18.6 SZ 0–6 cm fine-medium sand; 6–18 cm fine-medium sand and fine 

sand with gravels (some weathered schist, basalt, and some rounded basalt), few-some silt and very fine-fine sand; 18–21 cm silt with gravels

Dark yellowish brown (10YR4/2); silt is moderate brown 5YR4/4

WY91 18.9 19.1 SZ Gravel, fine-medium sand, some silt (till) Moderate brown 10YR4/4WY92 3.7 4.3 SZ Medium sand --WY92 16.2 16.8 SZ Sand, well sorted, few gravels of arkose, basalt, metamorphic rock Moderate-yellowish brown (10YR5/4)and moderate brown 

10YR4/4

WY93 1.2 1.8 UZ Gravels (gneiss/schist) 0–6 cm ; 6–53 cm fine-coarse sandy 

gravel, some silt

Grades from moderate brown 5YR3/4 to moderate brown 5YR4/4
148 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06 Appendix 1. Depths of sediment and rock samples and description of texture and lithology, color, and sorting, from monitoring-well boreholes in the study area, Woodbury, Connecticut.—Continued [%, percent; --, data not available; textural classification: trace, 0 to 2%; few, 2 to 5%; some, 5 to 15%; with, 15 to 30%; modifier (for example, silty), 30 to 45%; root, greater than 45%; bedrock wells shaded gray; cm, centimeters; m, meters; mm, millimeters] Well name Sampling depth below land surface (meters) Unsaturated zone (UZ) or saturated zone (SZ) Description from geologist’s log From To Texture and lithology Color1 WY93 2.7 3.4 UZ Fine-coarse sandy gravel (up to 3 cm, basalt), some muscovite flakes up to 2mm Pale-dark yellowish orange (10YR8/6 -10YR6/6) WY93 4.3 4.9 SZ Fine-medium sand, grading in lower 12 cm to fine sand, well sorted; muscovite common Pale-moderate yellowish brown (10YR6/2 –10YR5/4)) WY93 5.8 6.4 SZ 0–9 cm medium sand becomes a coarse sand; 9–49 cm gravelly fine-medium sand, some coarse sand, trace-some silt, few dark areas (organics or dark minerals?), gravels of basalt, foliated schist with garnet, abundant Na plagioclase or some pink mineral) Moderate yellowish brown 10YR5/4 WY93 7.3 7.9 SZ 0–9 cm fine-medium sand becomes @ 9 cm silty and fine sandy gravel (fresh and weathered basalt), few-some clay Moderate yellowish brown 10YR5/4 WY93 8.8 9.5 SZ Fine-medium sand grades to fine-very coarse sand with gravels (mostly granules, few up to 2 cm), some silt, few clay in pockets -- WY93 9.5 9.8 SZ 0–34 cm coarse sand, some fine-medium, with granules and gravels up to 2–4 mm; 34–41 cm weathered basalt (dark gray N3), pocket of silty sand Dusky brown (10YR2/2) to dark yellowish brown (10YR4/2); basalt is dark gray (N3) WY94 4.3 4.9 SZ Fine sand, well sorted Moderate yellowish brown 10YR5/4 WY95 1.2 1.8 SZ 0–6 cm fine-medium sand; some gravels; 6–30 cm gravelly fine- coarse sand, some silt and very fine-fine sand, trace-few clay 0–6 cm Moderate yellowish brown 10YR3/4; 6–30 cm grades from light brown 5YR5/6 to Moderate brown 5YR4/4 WY95 2.7 3.4 SZ Fine-medium sand, some coarse, few very coarse, few gravel (most small, couple up to 2 mm Moderate yellowish brown 10YR5/4 to moderate brown (5YR4/4) WY95 4.3 4.9 SZ Gravelly coarse-very coarse sand (gravels mostly 1–2 mm) Moderate yellowish brown 10YR5/4 to moderate brown (5YR4/4) WY96 1.2 1.8 UZ Clayey medium sand [to medium sand, some clay], few-some silt, few-some gravels (most granules, one 5-cm arkose gravel) Moderate brown (5YR3/4) WY96 2.7 3.4 UZ 0–30 cm fine-medium sand, some clay, some silt, few-some granules, few gravels up to 2.5 cm or so; bottom 6 cm is fine- medium sand with silt Moderate brown (5YR4/4) WY96 4.3 4.9 UZ Fine-medium sand some-with silt, few-some gravels, trace clay Moderate brown (5YR4/4); medium gray (N4) gravel (basalt?) at bottom
Appendix 149

Appendix 1. Depths of sediment and rock samples and description of texture and lithology, color, and sorting, from monitoring-well boreholes in the study area, Woodbury, Connecticut.—Continued[%, percent; --, data not available; textural classification: trace, 0 to 2%; few, 2 to 5%; some, 5 to 15%; with, 15 to 30%; modifier (for example, silty), 30 to 45%; root, greater than 45%; bedrock wells shaded gray; cm, centimeters; m, meters; mm, millimeters]

Well 

name

Sampling depth 

below land 

surface 

(meters)

Unsaturated 

zone

 (UZ) 

or saturated 

zone 

(SZ)

Description from geologist’s log

From To Texture and lithology Color1

WY96 4.6 5.5 -- Hard drilling--gravels/boulders --WY96 5.8 6.4 SZ Clay, sand, silt, and broken rock (medium gray) metamorphic rock 

or basalt

Moderate brown (5YR4/4); medium gray (N4) gravel fragments

WY97 0.0 9.1 UZ Soil and till --WY97 8.5 13.4 UZ Soft gray rock @ 8.5–9.2 m, then alternating soft and hard zones Medium gray/medium dark gray (N5–N4)WY97 10.7 0.0 -- Initially considered this bedrock interface, but drilling below was 

intermittently hard and soft, salt and pepper coarse sand at 11 m

Medium gray/medium dark gray (N5–N4)

WY97 12.7 13.1 SZ Fractured gneissic/biotite schist with mud lined fracture surfaces, 

(underneath clay is orange--Fe oxides--and in some places greenish yellow mineral)

Rock: very dark gray (7.5YRN3) to pinkish gray (5YR6/2)

WY97 13.1 14.7 SZ Gneiss/biotite schist with high angle foliation and fractures and 

veins of quartz (or calcite) and yellowish mineral (feldspar?).

Dark gray (ground mass)

WY97 14.7 15.3 SZ Gneiss/biotite schist with high angle foliation and fractures and 

veins of quartz (or calcite) and yellowish mineral (feldspar?).

Dark gray (ground mass)

WY97 15.3 15.5 SZ Metamorphic rock, high angle fractures and foliation Gray (2.5YN5) fresh surface; oxidized iron surface:moderate 

reddish brown (10R4/6–10R6/6)

WY97 15.5 0.0 Drillers consider this “competent bedrock” BedrockWY97 13.4 36.0 SZ Gneiss/schist; drillers called it a “sandstone”; no water produced Dark yellowish orange (10YR6/6) to moderate yellowish brown 

(10YR5/4)

WY97 39.0 42.1 SZ Gneiss/schist Rock color changed to olive gray (5Y4/1)WY98 0.6 1.2 UZ 0–12 cm medium sand, with-some gravels (trolley bed fill?); 

12–21 cm medium sandy loam, some gravels, some clay

0–12 cm dark yellowish brown (10YR4/4); 12–21 cm dark brown 

(10YR3/3)

WY98 0.9 6.4 UZ Large boulders, difficult drilling --WY98 2.9 3.5 SZ Gravelly medium-coarse sand, some or with silt, 0-few clay, 

mostly basalt gravel; pocket of gray silty zone; not real compact till, but appears to be till

Dark gray (10YR4/1) to dark grayish brown (10YR4/2)

WY98 3.7 4.3 SZ 0–3 cm basalt, weathered and kaolinite (feldspar) pockets; 3–6 

cm shoe fine-medium sandy gravel with coarse and very coarse sand, few-some silt

Light gray (10YR7/2)

WY98 4.4 5.0 SZ Gravelly sand (similar to above) basalt fragments Brown/dark brown (10YR4/3)
150 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06 Appendix 1. Depths of sediment and rock samples and description of texture and lithology, color, and sorting, from monitoring-well boreholes in the study area, Woodbury, Connecticut.—Continued [%, percent; --, data not available; textural classification: trace, 0 to 2%; few, 2 to 5%; some, 5 to 15%; with, 15 to 30%; modifier (for example, silty), 30 to 45%; root, greater than 45%; bedrock wells shaded gray; cm, centimeters; m, meters; mm, millimeters] Well name Sampling depth below land surface (meters) Unsaturated zone (UZ) or saturated zone (SZ) Description from geologist’s log From To Texture and lithology Color1 WY98 6.4 6.5 SZ Basalt pieces (blue-green, weathered flakey), silt, few-some clay Greenish gray (5BG511) WY100 1.2 1.8 UZ Fine-medium sand, some gravels and granules and very coarse sand Yellowish brown (10YR5/4) WY100 2.7 3.4 SZ 0–7.5 cm gravelly fine-medium sand, few gravels; 7.5–23 cm gravelly fine-medium sand, few-some silt; 23–30 cm weathered gravels (10YR7/1), basalt (black) in shoe 0–7.5 cm brown (10YR5/3); 7.5–23 cm greenish gray (5G5/1); 23–30 cm light gray (10YR7/1) weathered gravels, black basalt in shoe WY100 4.3 4.9 SZ Fine-medium sand, some gravels and coarse sand, gravels up to and >5 cm; pocket of very dark gray (10YR3/1) sand some silt, few clay; 9–18 cm brown gravels of basalt blocked. Brown (10YR5/3) WY100 5.8 6.4 SZ 0–6 cm medium sand, some fine, coarse, and very coarse sand; 6–12 cm gravelly fine-coarse sand, few silt, and pockets of fine sand, some medium and coarse; 12–21 cm gravels, some sand Moderate brown (10YR4/4) WY100 7.6 8.2 SZ Gravels and medium-very coarse sand; gravels of feldspar, metamorphic, quartz, medium-very coarse sand Brown (10YR4/3) to moderate brown (10YR4/4) WY100 8.2 8.8 SZ Fine-medium sand, some gravels, grades up to medium sand with gravels, some coarse sand Brown (10YR4/3) WY100 10.4 11.0 SZ Fine-medium sand, some gravels (basalt; gneiss gravel in shoe) 10YR4/3; reddish in shoe 5YR5/2 WY100 12.2 12.8 SZ Medium-coarse sand, some-with gravels Brown (10YR5/3) WY100 14.6 15.2 SZ Reddish brown medium sand (0–6 cm) over thin horizon (1.5 cm) of 5YR5/6 yellowish red, over thin horizon silty very fine sand, over gray brown 10YR5/1–5/2 fine sand, few-trace silt Reddish brown over 5YR5/6 yellowish red, over gray brown (10YR5/1–5/2) WY100 15.9 16.5 SZ Fine-medium sand, well sorted, grades downward to fine sand with very fine sand, well sorted Brown 10YR5/3 WY100 16.8 17.4 SZ 0–3 cm fine sand, some-few silt; 3–18 cm medium sandy gravel; 17 cm fine-very fine sand grayish brown; 18–21 cm medium sand few-some clay and silt, some gravels 0–3 cm dark yellowish brown (10YR4/4); 3–18 cm medium sandy gravel; 17–18 cm grayish brown (10YR5/2) WY100 18.3 18.9 SZ 0–9 cm medium then fine-medium sand some coarse and very coarse; 9–14 cm coarse-very coarse sand, some-medium sand and gravels (fine upwards to top); 14–27 cm very fine sand, grades downward to silty very fine sand/ very fine sandy silt 0– 9 cm brown10YR5/3; 9–14 cm (10YR5/2) more reddish than above; 14–27 cm grayish brown 10YR5/2 mottled gray and slightly reddish gray
Appendix 151

Appendix 1. Depths of sediment and rock samples and description of texture and lithology, color, and sorting, from monitoring-well boreholes in the study area, Woodbury, Connecticut.—Continued[%, percent; --, data not available; textural classification: trace, 0 to 2%; few, 2 to 5%; some, 5 to 15%; with, 15 to 30%; modifier (for example, silty), 30 to 45%; root, greater than 45%; bedrock wells shaded gray; cm, centimeters; m, meters; mm, millimeters]

Well 

name

Sampling depth 

below land 

surface 

(meters)

Unsaturated 

zone

 (UZ) 

or saturated 

zone 

(SZ)

Description from geologist’s log

From To Texture and lithology Color1

WY100 19.8 20.4 SZ 0–9 cm fine-medium, some coarse and very coarse; 9–14 cm 

coarse-very coarse sand, some medium sand and gravels, fining upwards to top; 14–27 cm grayish brown very fine sand grading down to silty very fine sand/very fine sandy silt

0–9 cm brown (10YR5/2); 9–14 cm (10YR5/2--slightly more 

reddish than above); 14–27 cm grayish brown 10YR5/2

WY100 21.3 22.0 SZ Broken rock and silty fine sand, few-some clay, very compact Brown (10YR4/3)WY100 21.6 21.7 SZ Arkose gravels and medium-coarse sandy clay with silt Dark yellowish brown (10YR4/2)WY101 2.7 3.4 SZ Fine-very coarse sand with /some gravels (mostly granules and 

some gravels (up to 2.5 cm), some silt, trace clay, organic matter (roots, wood chunks in upper parts; color indicate organic rich; lower 6 cm shoe very coarse sandy gravel, silty weathered basalt

Dark gray (10YR3/1); lower 6 cm: gray-dark gray (10YR4/1–5/1) 

with weathered basalt of dark greenish gray (5GY4/1)

WY106 21.6 60.6 SZ Basalt; hard drilling (no saprolite at top of bedrock) Dark gray (N2) to near black

1Based on Geological Society of America rock-color chart (Goddard and others, 1951).
152 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

Figure 2–1. Gamma, fluid temperature, fluid conductivity, and caliper logs, and acoustic traveltime, 

acoustic televiewer amplitude, and optical televiewer images for bedrock monitoring well WY86 in 

relation to depth in the study area, Woodbury, Connecticut.

Caliper

(inches)

Fluid conductivity

(microsiemens per

centimeter)

Temperature

(degrees Celsius)

Gamma

(counts per second) Acoustic traveltime

0° 90° 180° 270° 0°

Acoustic televiewer

amplitude Optical televiewer

0 200 400 13 14 15 16 150 160 170 180 3 3.5 4 0° 90° 180° 270° 0° 0° 90° 180° 270° 0°

DEPTH, IN METERS

WY86

 3

 6

 9

12

15

18

21

24

27

30

33

 0

 3
Appendix 153

0 150 14 15 100 200 3 4.5 0° 90° 180° 270° 0° 0° 90° 180° 270° 0° 0° 90° 180° 270° 0°

DEPTH, IN METERS

WY87

Caliper

(inches)

Temperature

(degrees Celsius)

Gamma

(counts per second) Acoustic traveltime Acoustic televieweramplitude Optical televiewer

Fluid conductivity

(microsiemens per

centimeter)

15

18

21

9

12

24

Figure 2–2. Gamma, fluid temperature, fluid conductivity, and caliper logs, and acoustic traveltime, 

acoustic televiewer amplitude, and optical televiewer images for bedrock monitoring well WY87 in 

relation to depth in the study area, Woodbury, Connecticut.
154 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06

Figure 2–3. Gamma, fluid temperature, fluid conductivity, and caliper logs, and acoustic 

traveltime, acoustic televiewer amplitude, and optical televiewer images for bedrock monitoring 

well WY97 in relation to depth in the study area, Woodbury, Connecticut.

50 275 14 15 100 130 5.5 8.5 0° 90° 180° 270° 0° 0° 90° 180° 270° 0° 0° 90° 180° 270° 0°

18

DEPTH, IN METERS

WY97

Caliper

(inches)

Temperature

(degrees Celsius)

Gamma

(counts per second) Acoustic traveltime

Acoustic televiewer

amplitude Optical televiewer

Fluid conductivity

(microsiemens per

centimeter)

21

24

27

30

33

36

39

42

45
Appendix 155

Figure 2–4. Gamma, fluid temperature, fluid conductivity, and caliper logs, and acoustic traveltime, 

acoustic televiewer amplitude, and optical televiewer images for bedrock monitoring well WY106 in 

relation to depth in the study area, Woodbury, Connecticut. 

10 60 15 16 500 2,500 5.5 7 0° 90° 180° 270° 0° 0° 90° 180° 270° 0° 0° 90° 180° 270° 0°

WY106

DEPTH, IN METERS

caliper

(inches)

temperature

(degrees Celsius)

gamma

(counts per second) acoustic traveltime

acoustic televiewer

amplitude optical televiewer

fluid conductivity

(microsiemens per

centimeter)

24

27

30

33

36

39

42

45

54

48

51

57

60

21

63
156 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06 Appendix 3. Quality-control summary for constituents detected in field blanks and percent recovery for surrogates in the study area, Woodbury, Connecticut, 2003–05. —Continued [VOC, volatile organic compound; Pest, pesticide; %, percent; textural classification: trace, 0 to 2%; few, 2 to 5%; some, 5 to 15%; with, 15 to 30%; modifier (for example, silty), 30 to 45%; root, greater than 45%.] Constituent name Class Mean Minimum Lower 25th percentile Median Upper 75th percentile Maximum Number of analyses Number of values above the reporting level Number of detections estimated below the reporting level Number of values above the reporting level Concentration, in micrograms per liter Isobutyl alcohold-6, surrogate, % recovery VOC 92 78 79 95 102 106 5 0 0 5 2-Chloro-4-isopropylamino-6- amino-s-triazine Pest 0.006 0.006 0.006 0.006 0.006 0.006 2 2 0 0 4-Chloro-2-methylphenol Pest 0.0056 0.0056 0.0056 0.0056 0.0056 0.0056 2 2 0 0 Atrazine Pest 0.007 0.007 0.007 0.007 0.007 0.007 2 2 0 0 Fipronil sulfide Pest 0.013 0.013 0.013 0.013 0.013 0.013 2 2 0 0 Fipronil Pest 0.016 0.016 0.016 0.016 0.016 0.016 2 2 0 0 Prometon Pest 0.0075 0.005 0.0062 0.0075 0.0088 0.01 2 2 0 0 Simazine Pest 0.005 0.005 0.005 0.005 0.005 0.005 2 2 0 0 1,1,1-Trichloroethane (TCA) VOC 0.032 0.032 0.032 0.032 0.032 0.032 16 16 0 0 1,1,2-Trichloro-1,2,2- trifluoroethane (CFC113) VOC 0.038 0.038 0.038 0.038 0.038 0.038 16 16 0 0 1,1-Dichloroethane (DCA) VOC 0.035 0.035 0.035 0.035 0.035 0.035 16 16 0 0 1,1-Dichloroethene (1,1-DCE) VOC 0.024 0.024 0.024 0.024 0.024 0.024 16 16 0 0 1,2,4-Trimethylbenzene VOC 0.056 0.056 0.056 0.056 0.056 0.056 16 16 0 0 1,4-Dichlorobenzene (p-DCB) VOC 0.034 0.034 0.034 0.034 0.034 0.034 16 16 0 0 2-Ethyltoluene VOC 0.06 0.06 0.06 0.06 0.06 0.06 16 16 0 0 Acetone VOC 6 6 6 6 6 6 16 16 0 0 Benzene VOC 0.021 0.021 0.021 0.021 0.021 0.021 16 16 0 0 Carbon disulfide VOC 0.04 0.038 0.038 0.038 0.038 0.07 16 15 1 0 Chloroethane VOC 0.12 0.12 0.12 0.12 0.12 0.12 16 16 0 0 Chloromethane VOC 0.17 0.17 0.17 0.17 0.17 0.17 16 16 0 0
Appendix 157

Appendix 3. Quality-control summary for constituents detected in field blanks and percent recovery for surrogates in the study area, Woodbury, Connecticut, 2003–05.—Continued[VOC, volatile organic compound; Pest, pesticide; %, percent; textural classification: trace, 0 to 2%; few, 2 to 5%; some, 5 to 15%; with, 15 to 30%; modifier (for example, silty), 30 to 45%; root, greater than 45%.]

Constituent name

Class Mean Minimum

Lower 

25th 

percentile

Median

Upper 

75th 

percentile

Maximum Number 

of 

analyses

Number 

of values 

above the 

reporting 

level

Number of 

detections 

estimated 

below the 

reporting 

level

Number 

of values 

above the 

reporting 

level

Concentration, in micrograms per liter

cis-1,2-Dichloroethene 

(cis-1,2-DCE)

VOC 0.024 0.024 0.024 0.024 0.024 0.024 16 16 0 0

Dichlorodifluoromethane 

(CFC-12)

VOC 0.18 0.18 0.18 0.18 0.18 0.18 16 16 0 0

Diisopropyl ether VOC 0.1 0.1 0.1 0.1 0.1 0.1 16 16 0 0Methyl ethyl ketone (MEK) VOC 2.8 2 2 2 4 4 16 16 0 0Ethylbenzene VOC 0.03 0.03 0.03 0.03 0.03 0.03 16 16 0 0Isopropylbenzene VOC 0.038 0.038 0.038 0.038 0.038 0.038 16 16 0 0tert-Amyl methyl ether 

(TAME)

VOC 0.055 0.04 0.04 0.04 0.08 0.08 16 16 0 0

m- and p-Xylene VOC 0.06 0.06 0.06 0.06 0.06 0.06 16 16 0 0o-Xylene, water VOC 0.038 0.038 0.038 0.038 0.038 0.038 16 16 0 0Ethyl-tert-butyl ether (ETBE) VOC 0.038 0.03 0.03 0.03 0.05 0.05 16 16 0 0Methyl-tert-butyl ether 

(MTBE)

VOC 0.13 0.1 0.1 0.1 0.17 0.17 16 16 0 0

Perchloroethene (PCE) VOC 0.041 0.03 0.03 0.03 0.06 0.06 16 16 0 0Tetrachloromethane VOC 0.06 0.06 0.06 0.06 0.06 0.06 16 16 0 0Tetrahydrofuran VOC 1.45 1 1 1 2.2 2.2 16 16 0 0Toluene VOC 0.029 0.0088 0.02 0.02 0.05 0.05 16 15 1 0Trichloroethene (TCE) VOC 0.038 0.038 0.038 0.038 0.038 0.038 16 16 0 0Trichloromethane VOC 0.024 0.024 0.024 0.024 0.024 0.024 16 16 0 0Vinyl chloride VOC 0.072 0.06 0.06 0.08 0.08 0.08 16 16 0 0
158 Aquifer Chemistry & Transport Processes in the Zone of Contribution to a Public-Supply Well in Woodbury, CT, 2002–06
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Publishing Service Centers.

For more information concerning this report, contact:

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dc_ct@usgs.gov

or visit our Web site at:

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Connecticut, Housatonic, and

Thames River Basins 

Study Unit

Brown and others—Aquifer Chemistry and Transport Processes in the Zone of Contribution to a Well in Woodbury, Connecticut, 2002–06—Scientific Investigations Report 2009–5051