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v

CONTENTS

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

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

Site history.....................................................................................................................................................................4

Previous investigations ..................................................................................................................................................4

Purpose and scope .........................................................................................................................................................5

Description of study area...............................................................................................................................................5

Geologic setting ....................................................................................................................................................5

Hydrologic setting.................................................................................................................................................7

Acknowledgments .........................................................................................................................................................7

Design of the ground-water tracer test ...................................................................................................................................7

Selection of the tracer-test site.......................................................................................................................................8

Design and installation of the tracer-test array ..............................................................................................................8

Selection, preparation, and injection of tracers .............................................................................................................9

Fluorescein dye .....................................................................................................................................................9

Bromide and sulfur hexafluoride ........................................................................................................................15

Sampling and analytical methods ................................................................................................................................16

Fluorescein-dye analysis.....................................................................................................................................17

Bromide analysis.................................................................................................................................................17

Sulfur hexafluoride analysis ...............................................................................................................................18

Volatile organic compound and methane analysis ..............................................................................................18

Results and evaluation of the chemical analyses .................................................................................................................19

Fluorescein-dye, bromide, and sulfur hexafluoride data .............................................................................................19

Volatile organic compound and methane data .............................................................................................................19

Quality assurance of the data.......................................................................................................................................21

Blanks .................................................................................................................................................................21

Replicate samples................................................................................................................................................24

Split samples and spiked split sample.................................................................................................................27

Analysis of the tracer movement..........................................................................................................................................28

Breakthrough curves....................................................................................................................................................28

Bromide breakthrough curves.............................................................................................................................29

Sulfur hexafluoride breakthrough curves............................................................................................................38

Isoconcentration contour plots.....................................................................................................................................47

Bromide concentrations ......................................................................................................................................51

Sulfur hexafluoride concentrations .....................................................................................................................56

Comparison of tracers..................................................................................................................................................61

Summary and conclusions....................................................................................................................................................64

References cited ...................................................................................................................................................................65

Appendixes...........................................................................................................................................................................67
vi

Figures

 1–3. Maps showing:

1. Location of the Canal Creek area and the wetland study area along West Branch Canal Creek,

Aberdeen Proving Ground, Maryland ............................................................................................................3

2. Location of the wetland study area along West Branch Canal Creek, Aberdeen Proving

Ground, Maryland, and the distribution of total organic halogen in the Canal Creek aquifer

upgradient from the wetland...........................................................................................................................6

3. Location of the ground-water tracer-test site and the C–C′ transect within the wetland study

area along West Branch Canal Creek, Aberdeen Proving Ground, Maryland.............................................10

4. Section C–C′ showing head distributions and ground-water-flow directions at high tide,

May 2, 1996, and the location of the ground-water tracer-test site, West Branch Canal Creek,

Aberdeen Proving Ground, Maryland ..................................................................................................................11

5. Photographs and schematic showing design features of the 1⁄4-inch inverted-screen piezometers ..........................12

6. Photographs showing the ground-water tracer array, on the C–C′ transect within the wetland

study area, West Branch Canal Creek, Aberdeen Proving Ground, Maryland:

(A) side view, and (B) top view............................................................................................................................13

7a–b. Schematic showing:

7a. Plan view of relative locations of the tracer-test piezometers in radial and rectilinear

coordinates, and depths below land surface .................................................................................................14

7b. Section view of relative depths below land surface of the tracer-test piezometers ........................................15

 8. Graphs showing sampling dates and water volumes removed for the ground-water tracer test...............................20

 9. Graph showing cumulative water removed during sampling of the ground-water tracer test..................................21

10. Graphs showing depth-averaged concentrations of volatile organic compounds in ground-water samples 

collected from the tracer array, August 1998 to September 1999.......................................................................22

11. Graph showing concentrations of methane in ground-water samples collected from the tracer array in 

August 1998 and September 1999 ....................................................................................................................23

12. Graph showing comparison of the empirical cumulative distribution function for bromide concentrations

in seven blanks analyzed by colorimetric method to the calculated lognormal cumulative

distribution function for a mean of 0.10 milligram per liter and a standard deviation

of 0.11 milligrams per liter ...............................................................................................................................23

13. Graphs showing variabilities calculated between replicate analyses (expressed as relative percent

differences) for each of the tracers used in the ground-water tracer test ..........................................................26

14. Graph showing relative percent differences between replicate analyses of individual volatile

organic compounds ...........................................................................................................................................27

15. Graph showing correlation of bromide concentrations from split analyses analyzed by colorimetric

method at the USGS National Water Quality Laboratory and ion-selective electrode at the

on-site laboratory ..............................................................................................................................................27

16–23: Charts showing bromide concentration with time for sampling points in:

16. Level H, 48 inches below land surface at radii of (a) 0 inches, (b) 7 inches, and (c) 14 inches

from the center of the array .....................................................................................................................30

17. Level G, 42 inches below land surface at radii of (a) 2 inches, (b) 7 inches, and (c) 14 inches

from the center of the array .....................................................................................................................31

18. Level F, 36 inches below land surface at radii of (a) 2 inches, (b) 7 inches, and (c) 14 inches

from the center of the array .....................................................................................................................32
vii

Figures—Continued

16–23: Charts showing bromide concentration with time for sampling points in:—Continued

19. Level E, 30 inches below land surface at radii of (a) 2 inches, (b) 7 inches, and (c) 14 inches

from the center of the array .....................................................................................................................33

20. Level D, 24 inches below land surface at radii of (a) 2 inches, (b) 7 inches, and (c) 14 inches

from the center of the array .....................................................................................................................34

21. Level C, 18 inches below land surface at radii of (a) 0 inches, (b) 7 inches, and (c) 14 inches

from the center of the array .....................................................................................................................35

22. Level B, 12 inches below land surface at radii of (a) 2 inches, (b) 7 inches, and (c) 14 inches

from the center of the array .....................................................................................................................36

23. Level A, 6 inches below land surface at radii of (a) 0 inches, (b) 6 or 7 inches, and (c) 13 or 

14 inches from the center of the array .....................................................................................................37

24–31: Charts showing sulfur hexafluoride concentration with time for sampling points in:

24. Level H, 48 inches below land surface at radii of (a) 0 inches, (b) 7 inches, and (c) 14 inches

 from the center of the array ....................................................................................................................39

25. Level G, 42 inches below land surface at radii of (a) 2 inches, (b) 7 inches, and (c) 14 inches

from the center of the array .....................................................................................................................40

26. Level F, 36 inches below land surface at radii of (a) 2 inches, (b) 7 inches, and (c) 14 inches

from the center of the array .....................................................................................................................41

27. Level E, 30 inches below land surface at radii of (a) 2 inches, (b) 7 inches, and (c) 14 inches

from the center of the array .....................................................................................................................42

28. Level D, 24 inches below land surface at radii of (a) 2 inches, (b) 7 inches, and (c) 14 inches

from the center of the array .....................................................................................................................43

29. Level C, 18 inches below land surface at radii of (a) 0 inches, (b) 7 inches, and (c) 14 inches

from the center of the array .....................................................................................................................44

30. Level B, 12 inches below land surface at radii of (a) 2 inches, (b) 7 inches, and (c) 14 inches

from the center of the array .....................................................................................................................45

31. Level A, 6 inches below land surface at radii of (a) 0 inches, (b) 6 or 7 inches, and (c) 13 or 

14 inches from the center of the array .....................................................................................................46

32–34: Isoconcentration contour plots:

32. Contour plots of fluorescein concentration by layer and along a north-south cross section of the

tracer array at time steps of:

a. 152–153 days after tracer injection.....................................................................................................48

b. 292–299 days after tracer injection ....................................................................................................49

c. 412–424 days after tracer injection.....................................................................................................50

33. Contour plots of bromide concentration by layer and along a north-south cross section of the

tracer array at time steps of:

a. 103–104 days after tracer injection.....................................................................................................52

b. 167–174 days after tracer injection ....................................................................................................53

c. 243–250 days after tracer injection.....................................................................................................54

d. 363–375 days after tracer injection ....................................................................................................55

34. Contour plots of sulfur hexafluoride concentration by layer and along a north-south cross section

of the tracer array at time steps of:

a. 103–104 days after tracer injection.....................................................................................................57

b. 167–174 days after tracer injection ....................................................................................................58

c. 243–250 days after tracer injection.....................................................................................................59

d. 363– 375 days after tracer injection ...................................................................................................60
viii

Figures—Continued

 35. Graphs showing comparison of tracers for the 0- to 2-in. radii by use of the dimensionless concentration

 (C/C0 ), which is derived by dividing tracer concentration (C ) by the injected concentration (C0),

 for (a) bromide and (b) sulfur hexafluoride .............................................................................................................63

Appendixes

A. Daily rainfall totals and fifteen-minute tidal water-level data from October 1997 through

September 1999 for West Branch Canal Creek, Aberdeen Proving Ground, Maryland ....................................68

B. Tracer-test data .......................................................................................................................................................72

B1. Site names and relative positions of tracer-test piezometers at West Branch Canal Creek,

Aberdeen Proving Ground, Maryland .....................................................................................................72

B2. Concentrations of fluorescein, bromide, and sulfur hexafluoride in ground-water samples

collected from the tracer array at West Branch Canal Creek, Aberdeen Proving Ground,

Maryland, July 14, 1998 through September 14, 1999 ...........................................................................75

B3. Concentrations of volatile organic compounds in ground-water samples collected from the

tracer array at West Branch Canal Creek, Aberdeen Proving Ground, Maryland,

August 4, 1998 through September 13, 1999 ........................................................................................104

B4. Concentrations of methane in ground-water samples collected from the tracer array at

West Branch Canal Creek, Aberdeen Proving Ground, Maryland,August 1998

and September 1999 ..............................................................................................................................110

B5. Concentrations of fluorescein, bromide, and sulfur hexafluoride in quality-assurance blanks

 collected during the tracer test at West Branch Canal Creek, Aberdeen Proving 

 Ground, Maryland, July 15, 1998 through October 7, 1999 ................................................................111

C. Sample calculation of sulfur hexafluoride concentrations in ground-water samples...........................................113

Conversion Factors and Vertical Datum

_____________________________________________________________________________________________________________________________________

Multiply By To obtain

_____________________________________________________________________________________________________________________________________

inch (in) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

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

foot per year (ft/yr) 0.3048 meter per year (m/yr) 

foot per day (ft/d) 0.3048 meter per day (m/d)

cubic foot (ft3) 0.0929 cubic meter (m3 )

_____________________________________________________________________________________________________________________________________

Vertical datum: In this report, “sea level” refers to the National Geodetic Vertical Datum of 1929—a geodetic datum 

derived from a general adjustment of the first-order level nets of the United States and Canada, formerly called 

Sea Level Datum of 1929.

Concentrations of chemical constituents in water are given in milligrams per liter (mg/L), micrograms per liter (μg/L), 

or nanograms per liter (ng/L).

Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (μS/cm at 25 °C).
Abstract 1

Design and Analysis of a Natural-Gradient Ground-Water 

Tracer Test in a Freshwater Tidal Wetland, West Branch

Canal Creek, Aberdeen Proving Ground, Maryland

By Lisa D. Olsen and Frederick J. Tenbus

Abstract

A natural-gradient ground-water tracer test 

was designed and conducted in a tidal freshwater 

wetland at West Branch Canal Creek, Aberdeen 

Proving Ground, Maryland. The objectives of the 

test were to characterize solute transport at the 

site, obtain data to more accurately determine the 

ground-water velocity in the upper wetland sediments, and to compare a conservative, ionic tracer 

(bromide) to a volatile tracer (sulfur hexafluoride) 

to ascertain whether volatilization could be an 

important process in attenuating volatile organic 

compounds in the ground water. The tracer test 

was conducted within the upper peat unit of a 

layer of wetland sediments that also includes a 

lower clayey unit; the combined layer overlies an 

aquifer. The area selected for the test was thought 

to have an above-average rate of ground-water discharge based on ground-water head distributions 

and near-surface detections of volatile organic 

compounds measured in previous studies. 

Because ground-water velocities in the wetland 

sediments were expected to be slow compared to 

the underlying aquifer, the test was designed to be 

conducted on a small scale.

Ninety-seven 1⁄4-inch-diameter inverted-screen 

stainless-steel piezometers were installed in a 

cylindrical array within approximately 25 cubic 

feet (2.3 cubic meters) of wetland sediments, in an 

area with a vertically upward hydraulic gradient. 

Fluorescein dye was used to qualitatively evaluate 

the hydrologic integrity of the tracer array before 

the start of the tracer test, including verifying the 

absence of hydraulic short-circuiting due to nonnatural vertical conduits potentially created during 

piezometer installation. Bromide and sulfur 

hexafluoride tracers (0.139 liter of solution containing 100,000 milligrams per liter of bromide 

ion and 23.3 milligrams per liter of sulfur hexafluoride) were co-injected and monitored to generate 

a dataset that could be used to evaluate solute 

transport in three dimensions. Piezometers were 

sampled 2 to 15 times each, from July 1998 

through September 1999, to assess background 

conditions and monitor tracer movement. During 

the test, 644 samples were analyzed for fluorescein, 617 samples were analyzed for bromide with 

an ion-selective electrode, 213 samples were analyzed for bromide with colorimetric methods, and 

603 samples were analyzed for sulfur hexafluoride, including samples collected prior to tracer 

injection to determine background concentrations. Additional samples were analyzed for volatile organic compounds (96 samples) and methane 

(37 samples) to determine the distribution of these 

contaminants and the extent of methanogenic conditions within the tracer array; however, these data 

were not used for the analysis of the test.

During the tracer test, the fluorescein dye, bromide, and sulfur hexafluoride were transported 

predominantly in the upward direction, although 

all three tracers also moved outward in all directions from the injection point, and it is likely that 

some tracer mass moved beyond the lateral edges 

of the array. An analysis of the tracer-test data was 

performed through the use of breakthrough curves 

and isoconcentration contour plots. Results show 

that movement of the fluorescein dye, a non-conservative tracer, was retarded compared to the 

other two tracers, likely as a result of sorption onto 

the wetland sediments. Suspected loss of tracer 

mass along the lateral edges of the array prevented 

a straightforward quantitative analysis of tracer 

transport and ground-water velocity from the bromide and sulfur-hexafluoride data. In addition, the 

initial density of the bromide/sulfur hexafluoride 

solution (calculated to be 1.097 grams per milli-
2 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD

liter) could have caused the solution to sink below 

the injection point before undergoing dilution and 

moving back up into the array. For these reasons, 

the data analysis in this report was performed 

largely through qualitative methods.

The mass of bromide and sulfur hexafluoride 

tracers within the array was estimated from the 

mean concentrations during each of four major 

sampling episodes that took place between 103 

and 375 days after tracer injection. Assuming an 

effective porosity of 0.40, the estimated mass of 

bromide ranged from about 68 percent (during the 

first major sampling episode) to as little as 4 percent of the mass that was initially injected, 

whereas the estimated mass of sulfur hexafluoride 

ranged from about 51 percent to 3 percent of the 

initial mass. These masses would be larger, however, if a higher porosity was assumed; for example, the mass of bromide estimated for the first 

major sampling episode would be 94 percent if an 

effective porosity of 0.55 was assumed. A comparison of bromide and sulfur hexafluoride concentrations relative to their respective injected 

concentrations indicates that a smaller proportion 

of the injected sulfur hexafluoride moved up into 

the tracer array compared to bromide. Breakthrough curves of bromide and sulfur hexafluoride 

concentrations with time showed differences 

between the two tracers in most parts of the array. 

In several instances, large concentrations of one 

tracer were not matched by large concentrations of 

the other. Breakthrough curves and isoconcentration contour plots indicate that the bromide tracer 

generally moved away from the injection point 

more efficiently than sulfur hexafluoride. The 

movement of the tracers coupled with the loss of 

tracer mass throughout the test shows qualitatively 

that there is a slight northward horizontal component to the ground-water flow in the area of the 

tracer array in addition to vertical flow.

Diffusion and advection are thought to be the 

major processes responsible for the tracer movement, based on the predominantly upward movement of the conservative tracers, coupled with the 

outward movement in all directions from the injection point. Decreases in concentration as the tracers moved upwards through the array were likely 

caused by dilution. Sorption was evaluated and 

eliminated as a potential source of mass loss or 

retardation for sulfur hexafluoride. Because the 

wetland sediments were saturated to land surface 

throughout the tracer test, potential losses of sulfur 

hexafluoride due to volatilization from the surface 

of the water table into an unsaturated zone could 

not be evaluated. Part of the sulfur hexafluoride 

could have volatilized into ambient bubbles of 

marsh gases at depth; this process could explain 

the early presence of sulfur hexafluoride in a few 

upper-level sampling points (because of gas-bubble rise) and the retardation of some of the sulfur 

hexafluoride (because of gas-bubble trapping) in 

the lower levels of the tracer array.

The tracer movement observed during this test 

can provide insights into the transport of volatile 

organic compounds in the wetland sediments at 

West Branch Canal Creek. Because the volatile 

organic compounds that are the contaminants of 

interest are nonconservative, sorption would be 

expected to retard their movement, though to a 

lesser degree than was observed for fluorescein, 

which has a higher octanol-water partitioning 

coefficient than the contaminants of interest. Dilution, which is thought to be a factor in reducing the 

tracer concentrations, could also affect volatile 

organic compounds in the wetland sediments; 

however, the higher proportion of daughter compounds detected in the shallow levels of the array 

(6 to 24 inches below land surface) compared to 

the deeper levels indicates that biodegradation is 

also acting to transform these compounds and 

reduce their mass. Finally, if volatile organic compounds are able to volatilize into bubbles of biogenic marsh gases at depth, their transport could 

be affected by potential acceleration or retardation 

due to gas-bubble rise or trapping, as was hypothesized with the sulfur hexafluoride.

Introduction

In cooperation with the U.S. Army, the U.S. Geological 

Survey (USGS) has been investigating the West Branch 

Canal Creek area of Aberdeen Proving Ground (APG), 

Maryland, (fig. 1) to assess the effectiveness of natural 

attenuation as a remediation option for ground-water contaminant plumes consisting of chlorinated volatile organic 

compounds (VOCs). Evaluating natural attenuation requires 

an understanding of the physical, chemical, and biological 

processes that control contaminant fate and transport, 
Introduction 3
4 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD

including abiotic degradation, biodegradation, sorption, dispersion, diffusion, volatilization, and ground-water flow. 

From May 1996 through January 1997, abiotic degradation, 

biodegradation, and sorption were quantified through laboratory microcosm experiments and batch sorption tests (Lorah 

and others, 1997). Dispersion and diffusion were not measured or estimated during this phase of the study and are difficult to quantify in tidal environments. Gas-flux chamber 

experiments designed to assess volatilization showed no 

detectable concentrations of VOCs in the air above the 

marsh surface; however, concentrations of VOCs in nearsurface ground water collected from the experimental sites 

were typically near or below the detection limit (Olsen and 

others, 1997; Lorah and others, 1997). Therefore, these 

experiments could not be used to determine whether volatilization could be a significant attenuation process if higher 

concentrations of VOCs were to reach the marsh surface. 

Ground-water velocities were not measured directly during 

these early investigations, but had been estimated based on 

data and assumptions provided in Lorah and others (1997) to 

be about 2.3 ft (feet) per year in an upward direction in the 

wetland sediments. However, it was believed that preferential flow could cause actual ground-water velocities to be 

more than an order of magnitude higher than this estimate.

From 1998 through 1999, the USGS, in cooperation with 

the U.S. Army Environmental Conservation and Restoration 

Division at APG, conducted a natural-gradient ground-water 

tracer test in a selected area of wetlands along West Branch 

Canal Creek. The objectives of this tracer test were to characterize solute transport and more accurately determine the 

ground-water velocity in the upper wetland sediments, and 

to compare a conservative ionic tracer (bromide) to a volatile 

tracer (sulfur hexafluoride) to determine whether volatilization could be a significant process in attenuating groundwater contaminants.

New methods were developed to overcome the difficulties associated with measuring tracer movement in wetland 

sediments with a low estimated ground-water velocity and 

upward ground-water flow, including the design of a smallscale three-dimensional array of 1⁄4-in.(inch)-diameter 

inverted-screen piezometers and low-volume sampling 

methods. Analytical methods were selected to minimize the 

sample volumes required and therefore minimize the water 

volume withdrawn for analysis, preserving the natural 

hydraulic gradient. The tracer-test data were analyzed by the 

use of breakthrough curves and isoconcentration contour 

plots. The results and analysis of the tracer test could be 

used to improve the understanding of natural attenuation and 

contaminant fate and transport processes at West Branch 

Canal Creek.

Site History

The U.S. Army has used APG as a center for chemical 

warfare research since 1917. Until the late 1970s, West 

Branch Canal Creek and the surrounding wetlands were used 

for disposal of chlorinated solvents and other wastes, including carbon tetrachloride, chloroform, trichloroethylene, and 

1,1,2,2-tetrachloroethane (Lorah and Clark, 1996). VOCs 

from these disposal activities are the source of the long-term 

contamination that persists in the Canal Creek aquifer, most 

likely through the slow dissolution of residual dense nonaqueous-phase liquids (Lorah and others, 1997). Fill material, including construction materials and debris from manufacturing facilities that were demolished in the late 1960s, 

was pushed out into areas of the wetland, displacing the natural wetland sediments. No known facilities that could have 

contributed contaminants to the ground water by way of the 

creek or the surrounding marshes have been active during 

the last two decades. A more detailed history of waste-disposal and landfilling activities in the Canal Creek area is 

available in Lorah and Clark (1996) and Nemeth (1989).

Previous Investigations

The first survey of soil, sediment, ground water, and surface water in the Edgewood Area (fig. 1) of APG was conducted by the U.S. Army Toxic and Hazardous Materials 

Agency, and is described in Nemeth and others (1983). In 

response to the U.S. Army’s concerns about contaminants in 

the Canal Creek area and data gaps in the initial survey, the 

USGS conducted a comprehensive investigation of contamination in the Canal Creek area. This investigation was conducted from 1985 through 1992, and is summarized in Lorah 

and Clark (1996).

In 1990, the Comprehensive Environmental Response 

and Compensation Liability Act (CERCLA) was passed, and 

Aberdeen Proving Ground was placed on the National Priorities List. This action led to an Interagency Agreement 

between the U.S. Army and Region III of the U.S. Environmental Protection Agency that required investigation and 

remediation of the Canal Creek area. From 1992 to 1996, 

the USGS began an investigation to determine the distribution, fate, and movement of chlorinated VOCs in the ground 

water along the West Branch Canal Creek. The objectives 

of the 1992–1996 investigation were to define the major 

ground-water flowpaths and hydrologic interactions between 

the aquifer, wetland, and surface water; to determine the distribution of contaminants along ground-water flowpaths; to 

determine the major geochemical and microbial processes 

affecting the VOCs; and to evaluate the effect and significance of natural-attenuation processes, including biodegradation, sorption, and volatilization, on the fate and mobility 

of VOCs in the wetland (Lorah and others, 1997). As part of 

the 1992–1996 investigation, ground-water flow velocities 

in the upward direction were calculated based on estimated 

porosities and data collected from piezometers that were 

screened in the aquifer sediments, which have relatively high 

hydraulic conductivities, and in the overlying fine-grained, 

organic-rich wetland sediments, which have lower hydraulic 

conductivities. These ground-water velocity estimates were 

representative of selected flowpaths extending through the 

aquifer and the wetland sediments, and were not necessarily 

representative of the wetland sediments as a hydrogeologic 

unit.

From 1996 through 1998, the USGS performed additional studies to further characterize natural-attenuation processes in the wetland sediments and their influence on the 
Introduction 5

fate of VOCs. Because these studies demonstrated that the 

layer of wetland sediments along West Branch Canal Creek 

was effective in attenuating contaminants, the USGS 

designed, conducted, and analyzed a natural-gradient 

ground-water tracer test in the upper wetland sediments, 

from 1998 through 2003, to further investigate this hydrologic unit. The objectives of this tracer test were to better 

characterize solute transport, procure a dataset that could be 

used in subsequent studies to verify previous estimates of 

ground-water velocity, and compare a nonvolatile conservative tracer to a volatile conservative tracer to determine 

whether volatilization could affect ground-water contaminants in the wetland sediments.

Purpose and Scope

This report describes the design and analysis of a smallscale natural-gradient tracer test that was conducted in an 

area of wetland sediments at West Branch Canal Creek. The 

tracer test was designed to monitor tracer movement in three 

dimensions within the upper peat unit of the wetland sediments over a period of approximately 1 year. Design and 

construction details for the 1⁄4-in. inverted-screen piezometers used for the tracer test, methods used for piezometer 

installation, and the arrangement of these piezometers within 

the “tracer array” are described. The techniques used to prepare and inject the tracers are discussed, and the methods 

used to collect and analyze samples from the tracer array are 

also presented.

Because one objective of the tracer test was to produce a 

dataset that could be used to verify previous estimates of 

ground-water velocity, the data that were collected throughout the test are provided, including the concentrations of 

fluorescein, bromide, and sulfur hexafluoride and the water 

volumes removed during sampling. Daily rainfall totals and 

tidal water-level data also are presented to provide a hydrologic context for the tracer data. Additional data are provided from ground-water samples that were periodically 

collected and analyzed for VOCs and methane to characterize the distributions of these solutes within the tracer array 

and determine whether their occurrence was consistent with 

observations in the upper wetland sediments. All of the 

chemical and hydrologic data included in this report were 

verified, and an evaluation of the data quality is presented 

for all of the compounds that were analyzed.

This report provides an analysis of the tracer movement 

based on the use of breakthrough curves and isoconcentration contour plots. Breakthrough curves are presented for 

bromide and sulfur hexafluoride only, whereas isoconcentration plots are presented for all three tracers. Mass losses 

from the tracer array are estimated for each tracer. A comparison of the movement of the three tracers (fluorescein, 

bromide, and sulfur hexafluoride) is provided, along with a 

discussion of the characteristics of the tracers and other solutes, such as the contaminants of interest, and the influence 

that solute characteristics can have on transport. A comparison of bromide, a nonvolatile conservative tracer, with sulfur 

hexafluoride, a volatile conservative tracer, is presented, 

with discussion of the possibility of volatilization.

Description of Study Area

West Branch Canal Creek is located in the Canal Creek 

area of APG, near the head of the Chesapeake Bay, in the 

Coastal Plain Physiographic Province of Maryland (fig. 1). 

From the confluence of its East and West Branches, Canal 

Creek flows southward into the Gunpowder River, an estuary located at the southwestern edge of the study area (fig. 

1). Freshwater wetlands characterize much of the West 

Branch Canal Creek area, though landfilling activities have 

decreased the area of some of these wetlands (fig. 2). Vegetation in the wetland study area consists mostly of common 

reed (Phragmites australis), with smaller zones of cattail, 

pickerelweed, and southern wild rice (Lorah and others, 

1997). 

During the 1992–96 investigation of the fate and transport of ground-water contaminants near West Branch Canal 

Creek, part of the creek and surrounding estuaries were designated as the “wetland study area” (fig. 2). An extensive 

network of drive-point piezometers was installed in this area 

from 1994 through 1995 to characterize the distribution and 

fate of contaminants in the ground water. The wetland study 

area and the piezometer network were subsequently used for 

the investigation of natural-attenuation processes in the wetland sediments, and the site selected for the tracer test is 

within this area.

Geologic Setting The geology of the Canal Creek area is 

characterized by thick, wedge-shaped deposits of unconsolidated Coastal Plain sediments that dip southeastward (Lorah 

and Clark, 1996). The Canal Creek aquifer, which is the 

contaminated aquifer of interest, is in the Patapsco Formation of Lower Cretaceous age, and ranges from 30 to 70 ft 

thick in the Canal Creek area (Lorah and Clark, 1996). The 

Canal Creek aquifer is confined in the East Branch Canal 

Creek area, and is semiconfined or unconfined near the 

West Branch Canal Creek area. The lower confined aquifer, 

which underlies the approximately 60-ft-thick lower confining unit, is not known to be contaminated (Lorah and 

Vroblesky, 1989; Lorah and Clark, 1996).

Sediments in the Canal Creek aquifer consist of mediumto coarse-grained sand and gravel, interfingered with thin 

layers or lenses of clay and silt. Upgradient from the wetland, the aquifer is overlain by fill material and the sediments of the upper confining unit. Within the wetland, the 

Canal Creek aquifer is overlain by wetland sediments, which 

are about 6 to 12 ft thick in the wetland study area. These 

wetland sediments consist of organic-rich peat, clay, silt, 

sandy clay, and clayey sand. Natural attenuation of VOCs 

occurs primarily in the upper peat unit of the wetland sediments, where the average total organic content was 18 percent (average of 15 sediment samples), and to a lesser extent 

in the lower clayey unit (Lorah and others, 1997). The effective porosity for the combined upper peat unit and lower 

clayey unit was assumed to be 0.40 (based on assumptions 

used in Lorah and others, 1997), but could range as high as 

0.55 within the upper peat unit, based on National Soil 

Survey data for the area (Soil Survey Staff, 2004).
6 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Design of the Ground-Water Tracer Test 7

Hydrologic Setting Shallow ground water on both sides 

of West Branch Canal Creek generally flows laterally and 

upward toward the creek channel. Ground water discharges 

from the Canal Creek aquifer through the wetland sediments 

into the creek and marsh areas. Deep flow in the aquifer 

may enter the regional flow system, which flows toward the 

southeast (Lorah and Clark, 1996). Recharge, in the form of 

rainfall infiltration, occurs upgradient from the creek. The 

average annual rainfall from 1997 through 1999 was 39.8 in. 

(Charles Clough, Meteorology Team, Aberdeen Test Center, 

U.S. Army, written commun., 2000). Daily rainfall totals 

from October 1997 through September 1999 were calculated 

from data provided by the U.S. Army Aberdeen Test Center 

Meteorology Team (Charles Clough, written commun., 

2000) and are presented in Appendix A.

North of Magnolia Road (fig. 2), the West Branch Canal 

Creek is typically nontidal. South of Magnolia Road, the 

West Branch Canal Creek is influenced by tides that range 

from approximately –0.5 to 4.0 ft relative to sea level, with 

an average change in tidal amplitude of approximately 1 ft 

per tidal cycle. Surface water in the tidal area generally 

ranges from fresh—less than 1,000 μS/cm (microsiemens 

per centimeter)—to slightly brackish (1,000 to 4,000 μS/cm) 

in the late fall, winter, spring, and early summer, and from 

slightly brackish to more strongly brackish (4,000 to

10,000 μS/cm) in the late summer and early fall (Olsen and 

others, 1997; Phelan and others, 2001). Tidal water levels 

were measured by a gage that has been operating on the West 

Branch Canal Creek at Hanlon Road since 1987 (fig. 2). 

Graphs of 15-minute tidal water-level data for October 1997 

through September 1999 are presented in Appendix A. 

Extremes in tidal amplitude are typically associated with 

storm events or strong winds pushing surface water northward up the Chesapeake Bay and the Gunpowder River or 

southward out of the Gunpowder River and the Chesapeake 

Bay. Under these conditions, water levels in West Branch 

Canal Creek do not necessarily coincide with predicted lunar 

tide levels. An example of wind effects on tidal water levels 

can be seen in data collected during two Nor’easters that 

affected the Chesapeake Bay area during January 27–29 and 

February 3–6, 1998 (Appendix A). Localized winds and 

freezing conditions can also cause deviations from the predicted lunar tide levels. Tidal fluctuations in the wetland can 

influence local ground-water heads, resulting in small, cyclical fluctuations in the water levels measured in some of the 

piezometers in the wetland study area (Lorah and others, 

1997; p. 30, 36). The long-term effects of tidal fluctuations 

on the net ground-water velocity are thought to be negligible; however, these fluctuations would likely increase the 

effects of dispersion on dissolved substances in the wetland 

sediments. Due to the overall upward ground-water flux and 

periodic tidal inundation, the surficial sediments in the wetland study area generally remain saturated all of the time.

Acknowledgments

The authors thank the following people for their contributions to the ground-water tracer test at West Branch Canal 

Creek. John Wrobel of the U.S. Army Environmental Conservation and Restoration Division, APG, and Allison 

O’Brien, contractor for the U.S. Army Environmental Conservation and Restoration Division, provided project guidance and logistical support. Peter Pritchard and his crew 

from the U.S. Army Aberdeen Test Center are thanked for 

their ongoing efforts in maintaining the floating walkways 

and bridge within the wetland study area. Alan Rosencrance, Henry Gardner, and Thomas Shedd of the U.S. Army 

Center for Environmental Research, Fort Detrick, Maryland, 

are thanked for providing the on-site laboratory trailer and 

technical support associated with its operation.

The authors are also grateful to colleagues within the 

USGS who provided support and assistance that made this 

study possible. The authors thank William Coon and the 

New York District of the USGS Water Resources Discipline 

for providing the fluorometer used for the fluorescein analyses, and Glenda Brown of the USGS National Water Quality 

Laboratory for performing bromide analyses that she customized for our low sample volumes. The authors are grateful to Eurybiades Busenberg of the USGS National Research 

Program, and his assistant, Wandee Kirkland, for providing 

analytical instrumentation and operational support at the 

USGS Reston Chlorofluorocarbon Laboratory for the sulfur 

hexafluoride analyses. We also thank Eurybiades Busenberg 

for his help and recommendations in adapting the headspace 

calculations to the context of this experiment.

The authors are grateful to Michelle Lorah and Daniel 

Phelan of the Maryland-Delaware-DC District of the USGS, 

and to Jonathan Johnson, formerly of the New Jersey District, for their ideas and advice concerning the design and 

implementation of the tracer test. We thank Elizabeth Marchand, Edward Miller, Linda Jo Dyer, and Daniel Phelan of 

the Maryland-Delaware-DC District for their help with analyzing sulfur hexafluoride samples. We thank Mastin Mount 

of the Maryland-Delaware-DC District for performing the 

bromide analyses by ion-selective electrode, and we thank 

Mastin Mount and Daniel Phelan for their contributions to 

the fluorescein analysis. We also thank Tracey Spencer for 

performing some of the VOC analyses. The authors are 

especially grateful to Mastin Mount, Daniel Phelan, Elizabeth Marchand, Linda Jo Dyer, and Jonathan Johnson for 

collecting ground-water samples during various segments of 

the tracer test. Finally, the authors thank the Publications 

staff of the Maryland-Delaware-DC District for their work in 

the preparation of this report.

Design of the Ground-Water Tracer Test

Measuring ground-water velocity in a vertical flow environment is difficult, and the particularly low velocity 

expected in the wetland sediments in the study area at West 

Branch Canal Creek necessitated that the tracer test be conducted on a very small scale, requiring the development of 

several new methods. Factors considered in the design of 

the ground-water tracer test included selection of an appro-
8 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD

priate tracer-test site; design and installation of the tracer-test 

array; selection, preparation, and injection of tracers; and 

sampling and analytical methods.

Selection of the Tracer-Test Site

The tracer test was conducted in the organic-rich peat 

sediments between piezometer sites WB35 and WB36 on the 

C–C′ transect in the wetland study area at West Branch 

Canal Creek (fig. 3). This site was selected based on 

ground-water flow patterns and head distributions, and the 

location of the contaminant plume.

The site that was selected for the tracer test had been 

determined from the previous investigation (Lorah and 

others, 1997) to be an area of converging ground-water flow 

(fig. 4), and therefore would likely have above-average 

ground-water discharge and relatively high ground-water 

velocity compared to other locations along the sampling 

transects. Based on head distributions, the average groundwater velocity in the wetland sediments near this site had 

been previously estimated to be 2.3 ft/yr (feet per year), calculated along a vertical flow line sited near piezometer cluster WB-35, assuming an effective porosity of 0.40 and an 

average vertical hydraulic conductivity in the wetland sediments of 0.007 ft/d (feet per day) (Lorah and others, 1997). 

In addition, the contaminant plume was close to the land surface in this area—VOCs had been detected in a shallow piezometer (WB35A, screened 1.5 to 2.0 ft below land surface) 

and in porous-membrane sampling devices (at depths of 

approximately 0.5 to 2.0 ft below land surface) installed in 

this area (Olsen and others, 1997; Spencer and others, 2000).

Selecting a site with a relatively high upward groundwater velocity was necessary to allow the test to be completed within the shortest possible timeframe, and to allow 

the velocity to be measured in an area in which contaminants 

are likely to be transported most quickly through the wetland 

sediments to the surface. In addition, the five shallowest piezometers in cluster WB35 (with screen depths ranging from 

1.5 to 18.5 ft. below land surface) were known to be affected 

by tidal fluctuations (Lorah and others, 1997); therefore, the 

ground-water system in this location was expected to be 

influenced by tidally enhanced dispersion processes, which 

could further accelerate contaminant transport and spreading.

Design and Installation of the Tracer-Test Array

Ground-water tracer tests commonly involve injecting a 

single tracer or multiple tracers into an injection well, and 

monitoring the movement of the tracer(s) by collecting 

ground-water samples from nearby wells. Multi-level sampling devices or piezometers can be used instead of wells. 

Ideally, any apparatus used to monitor tracer movement 

should not itself significantly influence the natural hydraulic 

gradients or the formation properties that determine the 

tracer movement. For the small-scale tracer test conducted 

at West Branch Canal Creek, small-scale injection and monitoring apparatus were needed. Based on lessons learned 

from a prior unsuccessful tracer test that relied on multi-level 

sampling devices made of bundled strands of flexible tubing, 

the injection and monitoring apparatus used for this study 

featured single strands of rigid stainless-steel tubing. An 

injection piezometer and 96 monitoring piezometers were 

constructed of 1⁄4-in.-diameter stainless-steel tubing fitted 

with internal piezometer screens designed to protect the piezometer openings from clogging with sediment (fig. 5).

The stainless-steel tubing was cut into lengths equal to 

the desired depth below land surface plus an additional 4.0–

4.5 ft to extend above land surface to prevent tidal flooding 

of the piezometers, and to accommodate water levels above 

land surface that are possible under flowing artesian conditions. Prior to installation, the tubing was decontaminated 

by flushing the inside and outside several times with a mixture of warm water and Alquinox detergent, scrubbing the 

outside with methanol-soaked sterile cotton gauze, rinsing 

inside and out with methanol, and then rinsing inside and out 

three times with deionized water. The piezometer screens 

were decontaminated using the same sequence of solutions.

The 3-in.-long piezometer screens were constructed of 

100-mesh (150-micron) stainless-steel wire mesh formed 

into a cylinder held open at one end by a 1⁄4-in.-diameter 

brass collar and tapering to a flattened point at the other end 

(fig. 5). The piezometer screens were attached to the stainless-steel tubes by inserting the pointed end of the screen 

upward into the end of the tube until the entire wire screen 

was inside the tube. The brass collar of the screen was fitted 

flush with the end of the stainless-steel tube. If insertion of 

the screen was difficult, the end of the tubing was either 

reamed with a 1⁄4-in. drill bit to slightly widen the opening, or 

the wire mesh of the screen was twisted slightly to compress 

it to fit inside the opening of the tube.

A two-tiered 3-ft by 3-ft plywood template drilled with 

1⁄4-in. holes was used to guide the spatial placement of the 

piezometers and to provide lateral support to the sections of 

the piezometers sticking above land surface. Prior to piezometer installation, the plywood template was painted with 

water-based latex paint to resist weathering, and was labeled 

with permanent marker with the radial coordinates for which 

the piezometers were named to facilitate in piezometer identification during sampling (fig. 6). The piezometers were 

then installed manually through the holes in the plywood 

template by pushing the screen end of the tube into the marsh 

sediments to the desired depth, while injecting a few milliliters of deionized organic-free water into the top of the 

piezometers to prevent the screen from clogging. This 

installation method had been tested elsewhere in the wetland 

and was found to be more effective at preventing screen 

clogging than inserting the piezometers with no water injection. Immediately following insertion, each piezometer was 

promptly purged of a few milliliters of water to remove the 

deionized water and to verify that the screen was sufficiently 

free of clogs. After installation, the piezometers were 

capped with vented 1⁄4-in.-diameter slip caps (figs. 5 and 6).

The network of 1⁄4-in.-diameter inverted-screen piezometers was installed in a spatial array that featured two concentric rings, with diameters of approximately 14 and 28 in., 

with discrete sampling points located at depths ranging from 
Design of the Ground-Water Tracer Test 9

0.5–5.0 ft below land surface. The injection piezometer was 

installed at the center of the array, at a depth of 4.0 ft below 

land surface, and 96 additional piezometers were installed 

above and around the injection piezometer to allow monitoring of the tracer movement (fig. 7). The concentric circle 

pattern was used so that multiple piezometers at each depth 

would be the same distance from the injection point, allowing comparisons of tracer concentrations and movement over 

time to be made among piezometers that were at equal distances from the injection point, but in different directions. A 

few piezometers were installed at 0.25 and 2.0 in. from the 

center axis because the ground-water flow direction in the 

wetland was thought to be mainly upward. The piezometers 

generally were installed about a month before water samples 

were collected to allow the wetland sediments to re-stabilize 

around the tubing. One piezometer (G18-180) was later 

installed 18 in. from the center of the circle because initial 

fluorescein data indicated that the tracer could be moving 

faster towards this location. Additional piezometers, including one that was later installed 24 in. from the center of the 

circle (D24-045) and four that were later installed below 

the injection point at 54 in. and 60 in. below land surface 

(I06-285, I07-112, J06-000, and J07-187), were not sampled 

until 250 days or more after tracer injection. 

Tracer-test piezometer sites were named on the basis of 

their relative positions, using radial coordinates. The first 

character of each piezometer site name is a letter that corresponds to the depth of the piezometer below land surface, in 

6-in. increments, so that “A” designates piezometers with 

intakes that are 6 in. below land surface, “B” designates piezometers with intakes that are 12 in. below land surface, and 

so on. The second two characters of each name are numbers 

that indicate the radius of the circle on which each piezometer is located, in inches from the center axis—for example, 

D07-000 is a piezometer with an intake positioned 24 in. 

below land surface, 7 in. from the center of the tracer array. 

The last three characters of the name designate the position 

of the piezometer on the circle, in degrees (° ), measured 

from a reference of 0° , which was designated as a northwesterly direction pointing directly towards the creek, 52° counterclockwise from magnetic north. For example, D07-180 is 

24 in. below land surface, 7 in. from the center of the tracer 

array, at the point on the circle that is farthest away (180° ) 

from the creek, 138° clockwise from magnetic north. Radial 

coordinates, rectilinear coordinates, and distances from the 

tracer injection point were determined for each piezometer 

site and are presented in Appendix B1. 

Selection, Preparation, and Injection of Tracers

The three tracers used in this study were fluorescein 

dye, bromide ion, and sulfur hexafluoride. Fluorescein 

dye, a reactive tracer, was injected on July 17, 1998, to test 

the hydrologic integrity of the tracer array prior to the 

injection of the conservative tracers (bromide ion and 

sulfur hexafluoride). A solution of bromide ion saturated 

with sulfur hexafluoride was injected 49 days later, on

September 4, 1998, and was monitored through

September 14, 1999.

Fluorescein Dye Sodium fluorescein is a reactive dye 

tracer commonly used to trace surface-water and groundwater movement (Kasnavia and others, 1999; Mull and 

others, 1988; Smart and Laidlaw, 1977). Fluorescein dye is 

essentially nontoxic (acute oral LD50,rat = 6.72 grams per 

kilogram; Smart, 1984) and may be easily and inexpensively 

detected at concentrations in the microgram per liter (μg/L) 

range using a fluorometer (Sabatini and Austin, 1991). 

Although fluorescein dye is sometimes considered a conservative tracer for tracing surface-water movement, it undergoes significant sorption on mineral surfaces (Kasnavia and 

others, 1999), and would be expected to demonstrate considerable sorption in sediments that are rich in organic matter 

(Sabatini and Austin, 1991), such as the wetland sediments 

at West Branch Canal Creek. Fluorescein dye also demonstrates decreased fluorescence in waters with pH values less 

than 5 (Sabatini and Austin, 1991; Mull and others, 1988; 

Wilson, 1968), which may be pertinent to ground water at 

West Branch Canal Creek, since pH values less than 5 have 

been observed in shallow piezometers near the tracer-test 

site (Olsen and others, 1997; Spencer and others, 2000).

In a column experiment to test the feasibility of using 

fluorescein dye as a ground-water tracer at West Branch 

Canal Creek, 25 mL (milliliters) of fluorescein dye, as a

1-percent solution (weight/weight), were placed at the top of 

a 12-in.-long column of wetland sediments contained in a

2.5-in.-diameter plastic sleeve. The column apparatus was 

covered with aluminum foil to prevent exposure to light, 

which can cause chemical degradation of the dye to nonfluorescing products. The dye was forced through the sediments in the column by additions of 50 to 150 mL of deionized water every 2 to 3 days for 8 weeks. The eluent from 

the column was collected and measured every few days for 

volume and concentration of fluorescein dye. The pH of the 

column eluent was measured at the beginning and end of the 

experiment and increased from 4.8 to 6.7, likely because 

much of the ambient ground water in the sediment column 

had been replaced by deionized water. The peak concentration of fluorescein dye occurred approximately 4 weeks 

after the start of the experiment. Concentrations gradually 

dropped to near the reporting limit by 6 weeks. After 8 

weeks, a cumulative total of less than 5 percent of the initial 

mass of fluorescein dye had been recovered in the column 

eluent.

The low recovery observed in the column experiment 

confirmed that fluorescein would not be an appropriate 

tracer to quantitatively measure ground-water velocity. 

Fluorescein, however, was selected as a qualitative tracer, to 

evaluate the hydrologic integrity of the tracer array, and to 

verify that the vertically oriented piezometers would not 

cause artificial short-circuiting of the ground-water flow. If 

fluorescein was detected in the shallow depth of the tracer 

array shortly after injection, the tracer test could be aborted 

prior to injecting the conservative tracers.

On July 17, 1998, 25 mL of a 5-percent solution of fluorescein dye in deionized water (50,000,000 μg of sodium 

fluorescein per liter of solution) were injected into the tracer 
10 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Design of the Ground-Water Tracer Test 11
12 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Design of the Ground-Water Tracer Test 13
14 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Design of the Ground-Water Tracer Test 15

array at piezometer H00-000. The concentration and volume 

of the fluorescein dye solution were selected based on the 

need to have a sufficient mass of fluorescein dye to overcome the effects of sorption and potential low pH in the 

ground water, and to minimize the volume so that injection 

of the dye would not cause a large displacement of ground 

water and thereby disrupt the natural hydraulic gradients in 

the ground-water-flow system. The resulting fluorescein dye 

solution had a density of 1.035 g/mL (grams per milliliter) 

and was dark, blood red, and nearly opaque.

Prior to the fluorescein dye injection, 45 mL of ground 

water were removed from the injection piezometer by using 

a 60-mL-capacity plastic syringe assembled with a 3-way 

polycarbonate valve attached to 1/8-in.-diameter Teflon tubing that was lowered to the top of the screen. Teflon tape 

had been wound tightly around the outside end of the Teflon 

tubing to form a seal against the inside of the piezometer 

near the top of the piezometer screen. The 3-way valve was 

used to maintain vacuum on the Teflon injection tubing 

while the plastic syringe containing the 45 mL of ground 

water was disconnected from the valve assembly. Ten mL of 

the ground water were used to analyze for background fluorescence, and 18 mL were used to analyze for background 

bromide. Next, a 25-mL-capacity graduated glass syringe 

was attached to the 3-way valve and used to inject the fluorescein dye into the marsh sediments via the Teflon injection 

tubing. The 3-way valve was then closed to maintain pressure on the Teflon injection tubing, while 1 mL of the previously removed ground water was used to rinse the dye 

residue from the 25-mL glass injection syringe. The 1 mL of 

rinsate, which was bright yellow, was then injected to ensure 

that the entire volume of dye was used. An additional 7 mL 

of previously removed ground water were subsequently 

injected in order to completely clear the dye from the Teflon 

injection tubing and push it into the surrounding formation. 

(This volume was approximately equal to the interior volume of the Teflon injection tubing and piezometer screen.) 

The 3-way valve was then closed and left attached to the 

Teflon injection tubing inside the injection piezometer to 

maintain neutral pressure (neither pushing nor pulling) on 

the water column until additional tracers could be added. 

Confirmation that the dye had completely cleared the injection tubing and piezometer screen and had not mixed with 

the 7 mL of ground water that had been left in the injection 

tubing was made 49 days later during the injection of the 

bromide ion and sulfur hexafluoride, when the standing 

water in the injection tubing was observed to have no yellow 

color.

Bromide and Sulfur Hexafluoride Bromide ion, typically 

from sodium or potassium bromide salts, is an inorganic conservative tracer that is not harmful to the environment and is 

widely used in ground-water studies (Prych, 1999; Springer, 

1998; Wilson and Mackay, 1993). Sulfur hexafluoride (SF6 ) 

is an inert gas that is detectable over a wide range of concentrations (Busenberg and Plummer, 2000), and it has recently 

gained acceptance as a conservative tracer in ground water 

(Busenberg and Plummer, 1997; Wilson and Mackay, 1993; 

Wilson and Mackay, 1996; Smart and Biggin, 1989). The 

movement of bromide in ground water would be expected to 

be controlled by advection and dispersion processes, 

whereas the movement of sulfur hexafluoride could also be 

affected by volatilization.

On September 4, 1998, 139 mL of 100,000-mg/L bromide solution saturated with sulfur hexafluoride gas (resulting in a concentration of 23.3 mg/L sulfur hexafluoride) 

were injected into the tracer array at piezometer H00-000. 

The bromide/SF6 solution was injected 49 days after the 

fluorescein dye to allow sufficient time to determine whether 

the tracer array or its installation had created any artificial 

vertical conduits in the wetland sediments, based on the 

fluorescein movement.

The bromide/SF6 solution was made by preparing 

sodium bromide solution and then saturating it with sulfur 

hexafluoride gas. A 250-mL quantity of 100,000-mg/L
16 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD

bromide-ion solution was made by dissolving 32.1930 g 

(grams) of sodium bromide into deionized organic-free 

water in a volumetric flask. The density of this solution was 

calculated to be 1.096 g/mL. Next, a 150-mL aliquot of the 

bromide solution was transferred to a pre-weighed Tedlar 

bag with a valve opening, which was then reweighed to confirm the volume of bromide solution added. Approximately 

100 mL of sulfur-hexafluoride gas were introduced to the 

bromide solution through the valve of the Tedlar bag, mixed 

by shaking the bag gently for several minutes, allowed to 

equilibrate for 10 to 15 minutes, and then expelled through 

the valve. This process was repeated three times using fresh 

sulfur hexafluoride gas to ensure complete saturation of the 

bromide solution. Approximately 50 mL of gas-phase sulfur 

hexafluoride were retained in the Tedlar bag in contact with 

the bromide/SF6 solution, to maintain the concentration of 

sulfur hexafluoride in the solution at saturation levels during 

tracer injection.

Prior to the injection of the bromide/SF6 solution, the

1/8-in.-diameter Teflon tubing used for the fluorescein injection was removed from the injection piezometer (H00-000) 

and quickly replaced with 1⁄4-in. diameter Teflon tubing 

attached directly to the top of the piezometer tube and 

secured with a 3-way valve. Attaching the tubing directly 

to the top of the injection piezometer (instead of placing it 

inside the piezometer) allowed for a more secure seal, which 

was needed to prevent the potential escape of sulfur hexafluoride gas from the piezometer after the injection of the bromide/SF6 solution. Seventy-five mL of ground water 

(slightly more than the 72.4 mL calculated volume of standing water in the piezometer) were then removed from H00-

000 through the Teflon tubing using the 3-way valve and two 

60-mL-capacity syringes. This water was inspected for 

color associated with the fluorescein dye and was observed 

to be clear except for the last 2 mL, which were pale yellow 

and were therefore returned to the injection piezometer. This 

inspection confirmed that the procedure used for injecting 

the fluorescein dye was successful and that none of the concentrated dye had traveled back upwards into the injection 

piezometer during the first 49 days after injection.

The Tedlar bag filled with bromide/SF6 solution was 

carefully suspended above the piezometer to minimize external pressure on the bag. A pinch clamp was placed on the 

Teflon injection tubing to keep it closed while the tubing was 

disconnected from the 3-way valve and was then connected 

to the valve of the Tedlar bag. The valve of the Tedlar bag 

was then opened and the clamp removed so that the bromide/

SF6 solution could flow freely into the piezometer. The vacuum that had been created by the earlier removal of ground 

water from the injection piezometer caused the wetland sediments to suck in the first two-thirds of the tracer solution, 

and it was necessary to adjust the valve on the bag to regulate the initial flow of tracer solution. The remaining onethird of the solution was introduced by gravity feed from the 

suspended bag. The Tedlar bag was then detached and 

replaced by the 3-way valve (with interim use of the pinch 

clamp), and the 73 mL of previously removed ground water 

were injected to push the tracer solution from the injection 

piezometer and screen into the surrounding sediments. 

Finally, the 3-way valve was closed to maintain neutral pressure on the water column during the tracer test.

 After the injection of the bromide/SF6 solution, the 

Tedlar bag was weighed, and the volume of tracer solution 

injected was determined to be 139 mL. The temperature of 

the solution during the 4-hour injection period was assumed 

to be the same as the temperature immediately outside the 

bag, which had been periodically measured and averaged 

25 °C (degrees Celsius), as shown below: 

 

The concentration of hexafluoride in the tracer solution 

was calculated to be 23.3 mg/L (23,300,000 nanograms per 

liter), based on a sulfur hexafluoride solubility of 35.5 mg/L 

in pure water at 25 °C (Wilhelm and others, 1977), and a salting-out coefficient of 0.189 for sulfur hexafluoride in sodium 

bromide solutions, which was determined by assuming proportionality with salting-out coefficients for sulfur hexafluoride in sodium chloride, potassium chloride, and potassium 

bromide solutions presented in Morrison and Johnstone 

(1955).

Sampling and Analytical Methods

Ground-water samples were periodically collected from 

the tracer array and analyzed for fluorescein, bromide, and 

sulfur hexafluoride to monitor the movement of the tracers. 

Four major sampling episodes, in which all or nearly all of 

the piezometers were sampled, were conducted at 103–104, 

167–174, 243–250, and 363–375 days after injection of the 

bromide/SF6 solution. Prior to sampling, the piezometers in 

the tracer array were purged and allowed to recover. Recovery times were typically 5 to 30 minutes. Purging was limited to one piezometer volume (usually less than 20 mL, 

depending on the depth of the water column) to minimize the 

volume of ground water removed from the piezometers, 

thereby reducing the potential to create artificial hydraulic 

gradients that could influence the natural movement of the 

tracers. The piezometers were purged and sampled using 

1/8-in.-diameter Teflon tubing inserted to a depth just above 

the screen. The Teflon tubing was attached to a 3-way valve 

Bromide/sulfur hexafluoride solution temperatures 

during tracer injection on September 4, 1998

Solution temperature

Time (degrees Celsius)

 9:00 AM 21.9

10:00 AM 24.0

11:00 AM 26.2

 12:00 noon 27.9

 Average 25.0
Design of the Ground-Water Tracer Test 17

connected to a graduated 10-mL glass syringe that allowed 

ground water to be withdrawn, measured, and expelled, 

without aerating the sample water or the water left in the piezometer. All volumes of water withdrawn during purging 

and sampling were carefully recorded. Following sample 

collection, the tubing, syringe, and 3-way valve were decontaminated by washing three times with a mixture of deionized water and phosphate-free, biodegradable detergent, and 

rinsing three times with deionized water before use in the 

next piezometer.

Ground-water samples (4–5 mL) collected for analysis of 

fluorescein and bromide by selective-ion electrode were put 

in test tubes that doubled as cuvettes for the fluorometer, and 

were capped and stored in the dark until analysis. Additional 

samples (16 mL) collected for bromide analysis by colorimetric method were collected in 30-mL brown polyethylene 

bottles and promptly shipped to the USGS National Water 

Quality Laboratory (NWQL) in Lakewood, Colorado, for 

analysis. Samples for the analysis of sulfur hexafluoride 

were collected by injecting 2 mL of the ground water from 

the glass syringe through a stainless-steel needle into sealed 

25-mL serum vials that had been purged with ultra-high 

purity nitrogen gas and evacuated of 2 mL of gas prior to 

sample collection. During the tracer test, samples were periodically collected from a subset of the piezometers for analysis for VOCs and methane, to evaluate their distribution over 

the depth range of the tracer test. VOC samples were collected with no headspace in 8-mL glass vials with Teflon 

septa and refrigerated until analysis. Methane samples 

(2 mL) were collected in sealed 25-mL serum vials in the 

same manner as that of sulfur hexafluoride, except that mercuric chloride was added to the vials prior to sample collection to prevent microbial activity from affecting the methane 

concentrations prior to analysis.

Analytical techniques were modified to minimize the 

volume of sample required. Each fluorescein analysis 

required only 4 to 5 mL of sample water. The sample from 

the fluorescein analysis was often reused for analysis of 

bromide by ion-selective electrode. Bromide analysis by 

colorimetric method required 16 mL of sample, which were 

diluted 1:2 with deionized water to provide sufficient volume for the analysis. Headspace analysis for sulfur hexafluoride required only 2 mL of sample. Analyses for VOCs and 

methane required only 8 mL and 2 mL for each sample, 

respectively.

Fluorescein-Dye Analysis Fluorescein dye analyses 

were performed at an on-site laboratory by using a Turner 

Model 10 filter fluorometer configured for fluorescein analyses. The methods of analysis are described in detail in Wilson (1968) and in manuals provided by the manufacturer. 

The fluorometer was zeroed with deionized organic-free 

blank water and calibrated with standards in concentrations 

of 5.0, 25, 100, 200, 500, and 1,000 μg/L of sodium fluorescein. The calibration curve was linear from 5.0 to 500 μg/L, 

but began to curve downwards at 1,000 μg/L due to concentration quenching, which is common at high concentrations 

(Wilson, 1968). The average relative response factor used 

to quantify the fluorescein concentrations in the environmental samples was therefore calculated using only the five lowest standards. A least-squares regression that included the 

1,000 μg/L standard was used, however, as an estimation 

tool for samples with concentrations exceeding 500 μg/L to 

aid in determining the amount of dilution needed to reduce 

the concentrations in those samples to fall within the linear 

calibration range. Background fluorescence of the ambient 

ground water was determined by analyzing samples collected prior to fluorescein injection, and was generally below 

5.0 μg/L.

Bromide Analysis Bromide samples were either analyzed by ion-selective electrode at the on-site laboratory or 

sent to the NWQL for analysis by colorimetric method. Two 

different methods were used for the bromide analyses 

because each method was thought to have advantages and 

disadvantages that precluded complete reliance on either 

method. Ion-selective electrodes have been considered to be 

unreliable; however, the colorimetric method required much 

more water for analysis (16 mL compared to 4 mL for the 

ion-selective electrode) and had higher costs and a longer 

turn-around time to get the data compared to the ion-selective electrode. Therefore, some of the samples were collected for analysis by ion-selective electrode to conserve 

water and minimize analytical costs, some of the samples 

were collected for analysis by colorimetric method (to the 

extent that sufficient water was thought to be available), and 

some of the samples were collected as split samples to evaluate whether the ion-selective electrode data were comparable 

in quality to the colorimetric data.

The bromide analyses by ion-selective electrode were 

typically performed on the same 4–5 mL of sample water 

that were used for the fluorescein analysis, following the 

general method described in EPA Method 9211 (USEPA, 

1996). Each day of use, the bromide electrode was calibrated using a 2-point calibration with 50 and 100 mg/L 

standards. This calibration was then verified using additional standards in concentrations of 1.0, 5.0, 200, and sometimes 500 mg/L, depending on the concentrations measured 

in the environmental samples. A tiny amount of ionicstrength-adjustor solution was added to each sample prior to 

analysis as a buffer to maintain constant ionic strength; the 

amount added depended on the sample volume, and the 

slight dilution effect of the added solution was accounted for 

in the reported concentrations by application of a multiplier. 

Samples with high (greater than 500 mg/L) bromide concentrations generally were diluted with deionized water to a 

concentration between 50–100 mg/L, and reanalyzed so that 

the results would fall within the linear calibration range; 

results were then multiplied by the dilution factor before 

reporting.

The bromide analyses by colorimetric method were performed following methods described in Fishman and others 

(1994). The minimum sample volume required for the analysis was approximately 30 mL. To minimize the volume of 

water withdrawn from the tracer array, only 16–18 mL of 

sample were typically collected, which were then diluted 
18 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD

at the NWQL using volumetric glassware to make up the 

necessary volume (usually 1:1 with deionized water). Additional sample dilution was sometimes necessary to reduce 

the bromide concentrations to below 20 mg/L, which is 

the upper reporting limit (RL) for the colorimetric method

(Fishman and others, 1994). Because the colorimetric 

method was markedly more sensitive than the ion-selective 

electrode (lower RL of 0.01 mg/L compared to 1.0 mg/L for 

the electrode), the dilution of samples for colorimetric analysis did not affect the comparability of the two methods.

Sulfur Hexafluoride Analysis Sulfur hexafluoride samples were analyzed at the USGS Reston Chlorofluorocarbon 

Laboratory by the West Branch Canal Creek project staff, 

under the guidance of Eurybiades Busenberg, using a gas 

chromatograph (GC) with an electron-capture detector. The 

method of analysis is described in Busenberg and Plummer 

(2000). To accommodate the small-volume requirements of 

the tracer test, only 2 mL of water were collected for each 

sample and injected into prepared 25-mL serum vials. For 

each analysis, a 1-mL aliquot of headspace was withdrawn 

from the serum vial and diluted by injection into a 292.8-mL 

glass mixing vessel containing ultra-high purity nitrogen 

gas. Thirty to 60 mL of the sample/nitrogen mixture were 

then withdrawn from the mixing vessel and injected into a 

fixed-volume sample loop that was maintained at atmospheric pressure. If a very low concentration was expected, 

the mixing vessel was not used, and the 1-mL aliquot of 

headspace was introduced directly into a gas-tight syringe 

containing a measured volume (30–60 mL) of nitrogen gas, 

and the resulting mixture injected into the sample loop. For 

each analysis, one of two sample loops was generally used, 

with loop volumes of either 0.1130 mL or 0.3015 mL. The 

30–60 mL of sample/nitrogen mixture used for each sample 

was of sufficient volume to flush the selected sample loop of 

any residual gases from the previous analysis and fill it for 

the next analysis. Once filled, the contents of the sample 

loop were introduced to the GC column, and the instrument’s 

response was measured as peak area using an integrator. The 

mixing vessel and syringe were then thoroughly flushed with 

nitrogen gas before preparing the next sample.

The concentrations of sulfur hexafluoride in the aliquots 

of headspace were determined using an average relative 

response factor obtained by averaging the responses of several analyses of 0.100 μg/L sulfur hexafluoride standard 

measured using the 0.1130- and 0.3015-mL sample loops. 

The concentrations of sulfur hexafluoride in the groundwater samples were then calculated from the headspace data 

using the Ideal Gas Law and Henry’s Law. Henry’s Law 

constants used in the calculations were derived as described 

in Wilhelm and others (1977). The formulas and calculations used for the determination of sulfur hexafluoride concentrations in ground-water samples are very complicated; 

an example calculation for a single analysis is presented in 

Appendix C. Reporting limits for sulfur hexafluoride ranged 

from 0.01–0.34 ng/L (nanograms per liter), depending on the 

dilution factor used, the sample temperature, and the ratio of 

sample to headspace volume.

Volatile Organic Compound and Methane Analysis

VOCs and methane were analyzed at the on-site laboratory 

at West Branch Canal Creek. Sample volumes for VOCs and 

methane were 8 mL and 2 mL, respectively. VOCs were 

analyzed using a purge-and-trap capillary gas chromatograph with a mass-selective detector. Laboratory qualityassurance practices included analyzing at least one calibration standard and one laboratory blank daily (or with each 

batch of samples) and verifying that each sample met internal quality-control limits, including internal standard and 

surrogate response criteria. The analytical method is equivalent to EPA Method 524.2, and includes modifications presented in Rose and Schroeder (1995). Additional 

modifications to the method include the following:

• Dibromofluoromethane was substituted for 1,2-

dichloroethane-d4 as the earliest eluting surrogate 

standard. This compound has a shorter retention time 

than 1,2-dichloroethane-d4, and thus provides better 

coverage of early eluting compounds (such as vinyl 

chloride, cis-1,2-dichloroethene, and trans-1,2-

dichloroethene) that are of central interest to the 

research supported by these analyses. The use of 

dibromofluoromethane as an acceptable surrogate for 

VOCs analyzed by purge and trap gas chromatography/

mass spectrometry is documented in EPA Method 8260.

• Sample volumes were 5 mL instead of 25 mL. The 

volumes of sparge tubes, gas-tight syringes, luer-lock 

syringes, volumetric flasks, and other glassware were 

adjusted accordingly. Potential reduction of analyte 

response due to the smaller volume was offset by the 

improved purge efficiency associated with purging a 

smaller volume of sample.

• A lower RL of 0.5–2.0 μg/L was used for all VOCs of 

interest, based on the lowest calibration standard that 

was consistently observed during each period of 

calibration. Non-detections and detections that were 

less than the RL are reported as less than (<) the RL 

value, with no additional qualifiers. Because groundwater samples from the West Branch Canal Creek area 

can have high concentrations (greater than 1,000 μg/L 

for some analytes), results should be used for screening 

purposes only and not for determining regulatory 

compliance by State or Federal agencies. The lower RL 

of 0.5 μg/L corresponds to a signal-to-noise ratio of 10 

or higher for analytes of interest, and is sufficiently 

larger (typically by a factor of 10 or more) than the 

method detection limits that are generally attainable 

using the same instrument configuration, such as those 

reported in Connor and others (1998).

• Calibration was performed using 12 to 14 calibration 

standards with concentrations ranging from 0.1–

250.0 μg/L. Calibration curves were constructed for 

each analyte of interest, using the set of standards 

that provided the widest concentration range while 

achieving a relative standard deviation (RSD) of less 
Results and Evaluation of the Chemical Analy ses 19

than or equal to 20 percent. The highest calibration level 

accepted for each analyte was used as the upper RL for 

that analyte. Data exceeding the upper RL were 

reported as greater than (>) the RL value.

Methane was analyzed using a gas chromatograph 

with a flame-ionization detector, using techniques described 

in Baedecker and Cozzarelli (1992). Concentrations of 

methane in the ground-water samples were calculated using 

Henry’s Law, based on the concentrations detected in 

aliquots of the headspace withdrawn from the sample vials. 

The instrument calibration was checked daily using standard 

compressed gas ranging in concentration from 10–10,000 

parts per million. The lower RL for aqueous methane concentrations depended upon the volume of the sample, the 

volume of the sample vial, and the temperature of the sample 

at the time of analysis, and ranged from 49.7–79.4 μg/L for 

the samples collected from the tracer array.

Results and Evaluation of the Chemical 

Analyses

Ground-water samples were collected from the tracertest piezometers on 50 dates from July 14, 1998 through 

September 14, 1999, and analyzed for fluorescein dye

(644 samples), bromide ion (830 samples), and sulfur 

hexafluoride (603 samples), including samples collected 

prior to tracer injection for determining background concentrations. Most of the piezometers were sampled 9 to 12 

times throughout the experiment; however, four major sampling episodes in which all (or nearly all) of the piezometers were sampled were conducted at 103–104, 167–174, 

243–250, and 363–375 days after injection of the bromide/

SF6 solution. The sequence of sampling dates and water volumes removed each day are shown in figure 8. The cumulative volume of water removed during sampling (after 

injection of the bromide/SF6 solution) was 17,448 mL 

(17.448 L) (fig. 9), which is equivalent to about 9 percent of 

the volume of water within the tracer array (assuming an 

effective porosity of 0.40). Results of the fluorescein, bromide, and sulfur hexafluoride analyses, along with water 

volumes removed, were tabulated for each piezometer, and 

are presented in Appendix B2. The results are grouped 

alphabetically by site name and are listed in chronological 

order for each site. 

Fluorescein-Dye, Bromide, and Sulfur Hexafluoride Data

Fluorescein dye was analyzed for 644 ground-water 

samples (Appendix B2), including 42 replicate samples 

(6.5 percent). Of these samples, 191 had detections, with 

concentrations ranging from 5.1–35,800 μg/L, and 453 were 

below the RL of 5.0 μg/L. Background concentrations measured in fluorescein samples collected from a variety of 

depths prior to injection of the dye (July 17, 1998) were

generally below 5.0 μg/L. Ground-water sampling for 

fluorescein dye was temporarily suspended between 154–

291 days after the injection of the fluorescein dye (from 

December 18, 1998 through May 4, 1999), because the fluorometer was unavailable during this period; therefore, no 

fluorescein data were collected during the second major 

sampling episode.

Bromide was analyzed by ion-selective electrode in the 

on-site laboratory for 617 ground-water samples (Appendix 

B2), including 43 replicate samples (7.0 percent). Of these 

samples, 545 had detections, with concentrations ranging 

from 1.0–991 mg/L, and 72 were below the RL of 1.0 mg/L. 

Background concentrations from samples collected from a 

variety of depths prior to injection of the bromide/SF6

solution (September 4, 1998) and analyzed by ion-selective 

electrode, were generally below 2.0 mg/L, with a few exceptions. The highest concentration of bromide in a background 

sample analyzed by ion-selective electrode was 3.2 mg/L, in 

a sample collected from A06-300 on August 4, 1998.

Bromide was also analyzed by colorimetric methods 

at NWQL for 213 ground-water samples (Appendix B2), 

including 20 replicate samples (9.4 percent). Of these 

samples, 212 had detections, with concentrations ranging 

from 0.03–1,090 mg/L, and one sample was below the RL of 

0.02 mg/L. The highest concentration of bromide in background samples analyzed by colorimetric methods was

0.34 mg/L, in a sample collected from A14-127 on 

August 4, 1998.

Sulfur hexafluoride was analyzed for 603 ground-water 

samples (Appendix B2), including 35 replicate samples 

(5.8 percent). Of these samples, 556 had detections, with 

concentrations ranging from 0.03–356,000 ng/L, and 47 

were below the RL, which ranged from 0.01–0.34 ng/L. Of 

the three tracers used, sulfur hexafluoride was detected over 

the widest range of concentrations, with detections spanning 

eight orders of magnitude. Background concentrations 

measured in three sulfur hexafluoride samples collected 

prior to the injection of the bromide/SF6 solution

(September 4, 1998) were 0.03, 0.16, and 1.27 ng/L.

Volatile Organic Compound and Methane Data

VOCs were analyzed for 96 ground-water samples 

(Appendix B3), including 5 replicate samples, to determine 

the spatial and temporal distribution of VOCs within the 

tracer array during the test. Of the 59 VOCs analyzed, only 

18 compounds were detected in samples. VOC samples 

were collected in August and October 1998, and February, 

May, and September 1999. Fewer VOC samples were collected than the number of samples collected for the tracer 

compounds because of the need to minimize water withdrawal from the tracer array. The most frequently detected 

VOCs were cis-1,2-dichloroethene, trans-1,2-dichloroethene, and vinyl chloride. VOC data were not used for the 

calculations of ground-water velocity because the initial concentration distribution was unknown, and VOCs are known 

to participate in degradation and sorption reactions and 

therefore are not considered to be conservative solutes. The 

vertical distributions of VOCs in the tracer array were determined by pooling the data for each depth and finding the 

average concentration of each compound, and are presented 
20 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Results and Evaluation of the Chemical Analy ses 21

for each VOC-sampling event to illustrate the temporal variability in the concentrations of these compounds (fig. 10). 

The concentrations and proportions of individual compounds 

varied systematically with depth, with parent compounds 

such as 1,1,2,2-tetrachloroethane and trichloroethene predominating at the deeper depths, and daughter compounds 

such as cis- and trans-1,2-dichloroethene and vinyl chloride 

predominating at the shallower depths. In addition, the lowest total concentrations of VOCs were observed in the upper 

levels of the tracer array. This pattern is consistent with 

VOC data collected in previous studies from nearby piezometers and porous-membrane sampling devices (Lorah and 

others, 1997, p 66, fig. 32). 

Methane was analyzed for 37 ground-water samples, 

with all samples collected and analyzed in duplicate (Appendix B4). Thirteen samples were collected in August 1998, 

and 24 samples were collected in September 1999. Methane 

samples were collected to determine the vertical extent of 

methanogenesis within the tracer array during the test. The 

vertical distribution of methane concentrations is presented 

in figure 11. Methanogenic conditions were previously 

shown (Lorah and others, 1997) to support biodegradation of 

the VOCs detected in the wetland sediments in the West 

Branch Canal Creek area, and appear to be associated with 

the transformation to daughter products and reductions in 

concentrations of the VOCs observed in the upper levels of 

the tracer array.

Quality Assurance of the Data

Quality-assurance samples were collected to evaluate 

bias and variability in the data collected for the three tracers 

and to compare the ion-selective electrode and colorimetric 

methods used to analyze for bromide. Bias is defined as 

systematic error that may result from contaminants being 

introduced into a sample or analytes being lost from a sample during collection, processing, or analysis. Variability is 

defined as random error in independent measurements of the 

same quantity, and may result from variations in sampling 

and analytical procedures. The quality-assurance samples 

evaluated for the tracer test included blanks, replicates, split 

samples, and a spiked split sample.

Blanks Laboratory blanks and field blanks were analyzed to evaluate the potential for systematic bias in the data 

due to contamination from equipment used for sampling and 

analysis or from the ambient environment. Laboratory 

blanks were typically analyzed at the start and end of each 

batch of analyses, with additional laboratory blanks sometimes analyzed in the middle of a batch if the batch had a 

large number of samples. Concentrations of tracer compounds in laboratory blanks were consistently below detection limits or substantially below the RL; therefore, the 

laboratory processes, analytical equipment, and deionized 

organic-free water used for the blanks were eliminated from 

consideration as sources of measurable bias in the tracer 

data.

Field blanks collected throughout the tracer test included 

wash blanks, ambient blanks, and air blanks. Wash blanks 

were collected by passing deionized organic-free water 

through the same equipment that was used to collect samples 

(after the usual equipment-washing procedures had been performed) and were used to evaluate the potential for contaminants to be transferred from one sample to the next by way of 

the sampling equipment. Ambient blanks were collected by 

pouring deionized organic-free water directly into the sample vials at the field site and were used to evaluate the potential for contaminants to be transferred to samples from the 

ambient environment during collection. Air blanks were 

collected by syringing ambient air near the tracer array into 

the sample vials and, like the ambient blanks, were used to 

evaluate the potential for contaminants to be transferred 

from the ambient environment during sample collection.

Wash Blanks—Thirty-two wash blanks were collected 

and analyzed for fluorescein dye (Appendix B5). All of 

these wash blanks had concentrations below the RL of

5.0 μg/L; therefore, sampling procedures were eliminated 

from consideration as a source of measurable bias in the 

fluorescein data. Thirty-three wash blanks were collected 

and analyzed for bromide by ion-selective electrode at the 

on-site laboratory (Appendix B5). All of these wash blanks 

had concentrations below the RL of 1.0 mg/L; therefore, 

sampling procedures were eliminated from consideration as 

a source of measurable bias for the bromide data obtained by 

ion-selective electrode.

Seven wash blanks were collected and analyzed for 

bromide by colorimetric methods at the NWQL (Appendix 

B5). Bromide was detected in all seven wash blanks, at levels ranging from 0.01 (the RL) to 0.33 mg/L, with a mean of 

0.10 mg/L and a standard deviation of 0.11 mg/L. These 
22 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Results and Evaluation of the Chemical Analy ses 23

concentrations were lower than the highest detection in 

background samples analyzed by colorimetric methods 

(0.34 mg/L in A14-127 on August 4, 1998) and could be due 

to transfer of low-level bromide residues from sampling or 

analytical equipment. The empirical cumulative distribution 

function of bromide concentrations in these wash blanks was 

compared to a cumulative distribution function plotted for a 

lognormal distribution with a mean of 0.10 mg/L and a standard deviation of 0.11 mg/L (fig. 12). If the true population 

of bromide concentrations in wash blanks analyzed by colorimetric methods is lognormally distributed, the probability 

that any hypothetical blank collected from the true population would exceed background levels is small—3.4 percent. 

For interpretation purposes, the bromide data obtained using 

colorimetric methods were pooled with the ion-selective 

electrode data and assigned a combined RL of 1.0 mg/L (the 

higher RL of the two methods). Assuming the stated lognormal distribution, the probability that any hypothetical blank 

collected from the true population of bromide analyses by 

colorimetric methods would exceed the combined RL of 

1.0 mg/L is very low—0.13 percent. Therefore, although the 

bromide data obtained using colorimetric methods would be 

expected to have a slight positive bias, this bias is small and 

assumed to be inconsequential in the interpretation of the 

tracer-test results.

Eight wash blanks were collected and analyzed for sulfur 

hexafluoride (Appendix B5). Sulfur hexafluoride concentrations in five of the wash blanks were below their RLs, which 

ranged from 0.01–0.96 ng/L, depending on the sample temperature at the time of analysis and the ratio of sample volume to headspace. Concentrations in three of the wash 

blanks exceeded their respective RLs, with concentrations of 

0.72 ng/L (RL = 0.21 ng/L), 0.74 ng/L (RL = 0.22 ng/L), and 

0.92 (RL = 0.21 ng/L). These concentrations are all lower 

than the highest concentration of sulfur hexafluoride 

detected in background samples (1.27 ng/L in F02-195 on 

August 3, 1998); therefore, the possibility of a slight positive 

bias in sulfur hexafluoride concentrations is assumed to be 

inconsequential in the interpretation of the tracer-test results.

Eight wash blanks were collected and analyzed for VOCs 

(Appendix B3). All VOC results for these wash blanks were 

below the RLs, with the exception of a single detection of 

trichlorofluoromethane (1.3 μg/L), a common refrigerant, in 

one wash blank that was collected on September 2, 1999. 

Three wash blanks were collected and analyzed for methane 

(Appendix B4), and the results for these blanks were below 

their RLs.

Ambient Blanks—Eleven ambient blanks were collected 

and analyzed for fluorescein dye and for bromide measured 

by ion-selective electrode (Appendix B3). All 11 ambient 

blanks had fluorescein concentrations below the RL of

5.0 μg/L and bromide concentrations below the RL of

1.0 mg/L; therefore, contamination from the ambient environment should not be considered a significant source of 

positive bias in the fluorescein and bromide data. Ambient 

blanks were not analyzed for bromide using the colorimetric 

method, which has a greater sensitivity and a lower RL than 
24 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD

the ion-selective electrode method. It is possible that bromide could have been present in the ambient blanks at concentrations less than 1.0 mg/L; however, because bromide is 

not volatile, the likelihood of bromide transfer to blanks and 

samples from the ambient air is substantially lower than that 

of transfer via the surfaces of equipment used for sampling 

and analysis. Therefore, the slight positive bias observed in 

wash blanks analyzed by colorimetric methods should not be 

attributed to contamination from the ambient air.

Air Blanks—Because sulfur hexafluoride readily volatilizes from solution and partitions almost entirely into the gas 

phase, and is analyzed more practically in the gas phase 

(whereas fluorescein and bromide are more practically analyzed in the aqueous phase), air blanks were collected 

instead of conventional (aqueous) ambient blanks to evaluate 

the potential for bias in the sulfur hexafluoride data. For the 

two air blanks collected, sulfur hexafluoride concentrations 

were below detection limits in one sample (less than 

1.20 ng/L on November 19, 1998) and 1.52 ng/L in the other 

(on November 18, 1998). These data indicate that sulfur 

hexafluoride could have been present at times in the air near 

the tracer array during sampling and could have come in 

contact with the sample water and the sampling equipment. 

Sulfur hexafluoride in the air near the tracer array could have 

come from volatilization from the purge water that was collected at the site. Sulfur hexafluoride concentrations as high 

as 79,400 ng/L were detected in the ground-water samples 

collected on November 18, 1998. The purge water collected 

that day would have been a composite of water from all of 

the piezometers sampled and is a possible source of the 

1.52-ng/L detection in the air blank. The low concentrations 

of sulfur hexafluoride in three of the eight wash blanks 

could have been caused by sulfur hexafluoride transfer from 

residues on the sampling equipment or from the ambient air 

at the site. This potential bias could also have affected the 

environmental sample data; however, the magnitude of the 

potential bias is comparable to the sulfur hexafluoride concentrations in background samples and should not affect the 

overall interpretation of the tracer-test results.

Replicate Samples Replicate samples (138 pairs) were 

collected sequentially at selected sites and times to assess the 

overall variability of the tracer data. If a replicate sample 

was collected for one or more of the tracers from a particular 

piezometer on a specific date, the first sample is designated 

with a “1” in the “Replicate” column, and the second sample 

is designated with a “2” in the “Replicate” column in Appendix B2. “NR” designates samples for which no replicate was 

collected. Variability, a measure of the degree of difference 

between replicate measurements of the same quantity, was 

determined by calculating the relative percent difference 

(RPD) between the two sample concentrations (prior to 

rounding the data to the appropriate number of significant 

digits) using the formula:

 , (1)

where C1 and C2 are the concentrations of a tracer compound in the replicate samples.

If the tracer concentrations in one or both of the replicate 

samples were below the RL, the RPD could not be calculated. The numbers of cases in which the concentrations 

were (1) below the RL in both samples, (2) below the RL 

in one sample, but at or above the RL in the other, and

(3) above the RL in both samples (RPDs were calculated in 

this case), are as follows: 

 

RPD 

C1 C2 –

C1 C2 ( ) + ⁄ 2 = ------------------------------ x 100 percent 

Type of replicate sample pair

Fluorescein

dye

Bromide, 

ion-selective 

electrode

Bromide,

colorimetric

Sulfur 

hexafluoride

Total,

all tracers

1. Below the reporting limit for both samples 28 8 0 0 36

2. Below the reporting limit for one sample, 

 but at or above the reporting limit for the

 other

2 1 0 14

3. Above the reporting limit for both samples

 (relative percent differences were

 calculated)

10 34 20 34 98

Total number of replicate sample pairs 40 43 20 35 138
Results and Evaluation of the Chemical Analy ses 25

Variability (expressed as RPD) was generally low for all 

of the tracers—less than 25 percent for most samples (fig. 

13). No strong correlations were observed between sample 

variability and any of the following factors: sample date, 

sample depth, distance of the sampling point from the tracer 

injection point, sample concentration, and the volume of 

water removed during sampling—correlation coefficients 

were less than 0.21 for each of these factors. The distribution of RPDs was noticeably different, however, among the 

three tracers and between the two sets of bromide data (ionselective electrode and colorimetric methods), indicating 

that the degree of sample variability is related to the characteristics of the individual tracer compounds and the analytical methods used to measure them. Histograms comparing 

the distributions of RPDs for each tracer are presented in 

figure 13, with separate histograms for bromide analyzed by 

selective-ion electrode and colorimetric methods. 

Of the three tracers used, sulfur hexafluoride showed the 

greatest variability. Of the 34 replicate pairs evaluated for 

sulfur hexafluoride, 9 pairs (over 26 percent) had RPDs 

greater than 25 percent, and 1 pair had an RPD greater than 

150 percent (fig. 13). Fluorescein and bromide (both methods) demonstrated lower variability than sulfur hexafluoride—over 75 percent of the replicate pairs for fluorescein 

and bromide had RPDs below 25 percent, and none had 

RPDs greater than 100 percent. The higher RPDs for sulfur 

hexafluoride are likely due to differences in its physical 

characteristics compared to those of the other tracers.

Because sulfur hexafluoride is a gas and volatilizes 

readily from water, it can partition into any gas phase present 

in the water, which would reduce its aqueous concentration. 

Gas-phase equilibrium processes represent a source of variability that could only have affected the sulfur hexafluoride 

and not the fluorescein or bromide. Gas bubbles could have 

been introduced to samples when the ground water was 

syringed from a piezometer, if care was not taken to expel all 

gases from the syringe and 3-way valve before collecting the 

sample, or if the piezometer did not contain enough water for 

continuous withdrawal of sample water without aeration. It 

is more likely, however, that gas bubbles in the samples were 

due to effervescence, which was observed in many of the 

ground-water samples. Ground-water pressure below the 

surface of the water table exceeds atmospheric pressure 

because of the weight of the overlying water, resulting in the 

water having a higher capacity for dissolved gases than 

would be possible at atmospheric pressure. Artesian conditions (evidenced by water levels in the piezometers in the 

study area being higher than the water table), due to the 

higher elevation of the surrounding recharge areas and the 

confining nature of the wetland sediments, is an additional 

source of pressure that would further increase the capacity 

for dissolved gases in the shallow ground water. Concentrations of dissolved biogenic marsh gases (such as methane, 

carbon dioxide, hydrogen sulfide, and carbon disulfide) in 

excess of their solubility limits for water at atmospheric 

pressure would be expected to effervesce as bubbles when 

the ground water was brought to the surface during sampling. For the effervescent samples, a portion of the dissolved sulfur hexafluoride that was added to the ground 

water as a tracer could have effervesced with the marsh 

gases or subsequently partitioned into bubbles that formed in 

the sample vials. The headspace analysis method used for 

the sulfur hexafluoride would have greatly minimized the 

variability associated with potential effervescence in the 

water after sample collection; however, intrinsic heterogeneities in the concentrations of dissolved gases within the 

ambient ground water itself could have contributed to the 

variability observed in the sulfur hexafluoride replicates.

Differences in variabilities also were observed between 

bromide measured by ion-selective electrode and by colorimetric methods (fig. 13). Over 90 percent of the replicate 

pairs (31 of 34) analyzed for bromide by ion-selective electrode had RPDs of less than 25 percent. Only 75 percent of 

the replicate pairs (15 of 20) analyzed for bromide by the 

colorimetric method had RPDs less than 25 percent. Sampling procedures for bromide analyzed by both methods 

were nearly identical; therefore, the differences in variabilities are more likely due to differences in laboratory procedures. Samples analyzed by the colorimetric methods 

typically were diluted at a 1:2 ratio with deionized water 

prior to analysis to provide adequate sample volume. For 

both analytical methods, samples with concentrations that 

exceeded the calibration range were diluted to reduce the 

concentrations to within the calibration range and re-analyzed. The upper RL for the ion-selective electrode was 

500 mg/L, and the upper RL for the colorimetric method was 

20 mg/L; therefore, a higher proportion of samples analyzed 

by colorimetric method were diluted, and for this method, 

the dilution step was performed in addition to the initial 

1:2 dilution done for sample-volume purposes. These dilution steps could explain the higher variabilities in the replicate samples analyzed by the colorimetric method compared 

to the replicates analyzed by ion-selective electrode.

Variabilities also were evaluated for the VOCs, using the 

data in Appendix B3. Fifty-nine VOCs were analyzed for 

5 replicate pairs, generating 295 possible comparisons 

between replicate analyses. Of these 295 possible comparisons, 272 were below the RL in both samples, 1 was below 

the RL in one sample but above the RL in the other, and 22 

were above the RL for both samples. RPDs calculated for 

the 22 replicate analyses with detections in both samples 

were generally less than 40 percent, with the exception of the 

RPDs for a replicate pair collected from D07-022 (fig. 14). 

Because of the slow recovery rate for this piezometer, the 

second sample of this replicate pair was collected 1 day after 

the first sample. Because VOCs are volatile, they are susceptible to losses if the water is exposed to air during sampling and analysis; therefore, sampling and analytical 

methods were selected to minimize the potential for sample 

aeration. VOCs would also be susceptible to losses in gas 

bubbles from natural effervescence in the samples for which 

this occurred. Another possible source of variability in the 

VOC data is small-scale heterogeneities in the distribution of 

VOCs in the immediate vicinity of the piezometer screens 
26 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Results and Evaluation of the Chemical Analy ses 27

because of localized zones of increased degradation or sorption. 

Split Samples and Spiked Split Sample Fifty-four splitsample pairs, including 1 spiked split-sample pair, were collected and analyzed for bromide by ion-selective electrode 

and colorimetric methods to evaluate the comparability of 

the two analytical techniques. The split samples were collected sequentially by filling a vial for analysis at the on-site 

laboratory by ion-selective electrode and then filling a vial 

for analysis at the NWQL by the colorimetric method, or 

vice versa. If replicate analyses were performed for either or 

both analytical methods for a split sample, the replicate values were averaged before comparing the split samples. The 

spiked split-sample pair was collected by adding a known 

quantity of concentrated bromide solution to a known volume of sample water that was collected from C14-270 on 

November 5, 1998, to produce an expected spike concentration of 199.95 mg/L. The spiked sample water was then 

divided into separate vials for analysis by the two methods.

Of the 54 bromide split-sample pairs analyzed, 48 pairs 

(including the spiked pair) had concentrations above the RL 

in both samples, and could be compared quantitatively. For 

these 48 pairs, concentrations in the samples analyzed using 

the ion-selective electrode correlated favorably (correlation 

coefficient, r = 0.967) with concentrations in the samples 

analyzed using colorimetric methods (fig. 15). Eliminating 

the spiked split-sample pair from the data set did not change 

the degree of correlation (r = 0.967). The remaining 6 splitsample pairs had concentrations below the RL of 1.0 mg/L 

for the samples analyzed by ion-selective electrode, and concentrations above the RL of 0.02 mg/L (but below 1.0 mg/L) 

for the samples analyzed by the colorimetric method.

The 2 bromide split-sample pairs that showed the most 

difference between the analytical methods were collected 

from H07-030 on September 17, 1998 (104 mg/L by ionselective electrode, 392 mg/L by colorimetric method), and 

from H07-090 on November 18, 1998 (185 mg/L by ionselective electrode, 87.7 mg/L by colorimetric method) (fig. 

15). These samples were collected from sites that were very 

close (7 in.) to the injection piezometer and were collected 

13 and 75 days, respectively, after the introduction of the 

bromide/SF6 solution. The differences in the results for 

these split-sample pairs could be due to small-scale heterogeneities in the ground water, which could cause differences 

in tracer concentrations between the first and second aliquots 

of water withdrawn from these piezometers. Although the 

small water volumes withdrawn during sampling were 

expected to overcome most of the heterogeneity in tracer 

concentrations associated with small-scale changes in the 

composition of the ground water in the vicinity of the piezometer intakes, samples collected from piezometers closest 

to the injection piezometer and from the earliest dates after 

tracer injection would be the most susceptible to small-scale 

variations in tracer concentration.

Analyte recoveries for the spiked split sample were very 

good. Based on an expected bromide concentration of 

199.95 mg/L, the recovery of bromide analyzed by the ion-
28 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD

selective electrode was 99.7 percent (199.28 mg/L), and the 

recovery of bromide analyzed using the colorimetric method 

was 105 percent (209.85 mg/L). Based on the results of the 

split-sample pairs and the spiked split-sample pair, bromide 

data obtained using the ion-selective electrode and the colorimetric methods were considered comparable, and were 

pooled for the purpose of data analysis and interpretation.

Analysis of the Tracer Movement

Analysis of tracer movement in a natural-gradient tracer 

test can be a complex process. The complexity of the analysis of tracer movement in this study was increased due to 

several aspects of the test environment and tracer array configuration. First, the test was conducted in a ground-water 

discharge zone, with the injection point near the bottom of 

the tracer array. This differs from most other field tracer 

tests, which are conducted with one or more injection points 

located at one end of an essentially horizontal flow field. 

Second, the area was affected by tides that inundated the 

land surface approximately twice a day. This resulted in 

uncontrolled diurnal variations in hydraulic gradient within 

the array, and may have resulted in surface water diluting the 

ground-water tracer concentrations within the shallowest 

depths of the array. Third, the size of the tracer array was 

necessarily small, because tracer movement was expected to 

be slow in this environment. The small array size meant that 

small variations in hydraulic properties (such as direction 

and magnitude of hydraulic gradient, and spatial heterogeneity in hydraulic conductivity caused by roots or other preferred flowpaths) could cause large differences in the actual 

results compared to what was expected, which was simple 

upward movement.

Tracer movement was expected to be affected by a number of hydrologic and chemical processes, including advection (transport of solutes by ground-water flow), mechanical 

dispersion (spreading of a solute plume because of differing 

ground-water velocities within a porous medium), and 

chemical diffusion (spreading of a solute plume from areas 

of high chemical concentration to areas of low chemical concentration). Advection moves solutes in the direction of 

ground-water flow, which in this area was expected to be 

generally upward. Mechanical dispersion will not occur 

without advection. It spreads the plume in all directions 

away from the center of mass, with most of the spreading in 

the longitudinal direction (parallel to flow) and lesser 

spreading in transverse directions. Chemical diffusion 

works in all directions and unlike mechanical dispersion, is 

not caused by ground-water flow. Chemical diffusion would 

be the dominant spreading factor in cases where groundwater flow is very slow or negligible. Where ground-water 

flow is faster, advection and mechanical dispersion usually 

dominate, with chemical diffusion often lumped into the dispersion term. Tracer movement was not expected to be 

affected by volatilization, except for sulfur hexafluoride in 

the uppermost level of the tracer array, because fluorescein 

dye and bromide are not volatile, and dissolved sulfur 

hexafluoride generally does not volatilize from solution 

unless a gas phase is present.

In addition to these processes, the density of the 

bromide/SF6 solution required for the tracer test could have 

caused some initial downward movement of the tracer mass. 

Although the injected volume was only 139 mL and dilution 

would have acted rapidly to mitigate the density effects, it is 

possible that the center of tracer mass dropped below the 

injection point during the early days of the test. If one were 

to assume that the initial tracer mass had been a sphere that 

became diluted homogeneously as it expanded in all directions, a ten-fold dilution of the tracer solution would have 

increased of the radius of the plume from 1.7 in to 3.7 in. 

(assuming an effective porosity of 0.40), and decreased the 

solution density from 1.096 g/mL to 1.0096 g/mL, which 

would be closer to the density of the ground water in the 

tracer array. It is unlikely that such dilution would have 

occurred homogeneously throughout the plume however, 

therefore, the center of mass and concentration distribution 

in the early days of the test proved too difficult to quantify. 

In order not to artificially force the tracer to lower depths, 

samples were not collected from below the injection point 

(levels I and J) until late in the test (starting 250 days after 

bromide/SF6 injection), so it is impossible to tell whether 

part of the tracer mass could have moved downwards below 

the array and been lost. This potential initial sinking of the 

tracer mass prohibits a straightforward mathematical analysis of the tracer test. It is possible that analytical methods or 

numerical models developed for variable-density fluid flow, 

such as SUTRA (Voss and Provost, 2002), could be used to 

characterize the tracer movement and differentiate between 

density effects and other hydrologic processes; however, this 

exercise was beyond the scope of this report. The following 

analysis of the tracer test is based on breakthrough curves 

and isoconcentration contour plots.

Breakthrough Curves

Breakthrough curves of bromide and sulfur hexafluoride 

concentrations with time were plotted for each sampling 

point to compare different spatial characteristics of tracer 

movement. In the following sections, the breakthrough 

curves and associated discussions are presented by 

depth, starting from the bottom of the tracer array (level H, 

48 in. below land surface) and moving upward (to level A, 

6 in. below land surface), because the tracer was injected 

at 48 in. below land surface and the hydraulic gradient 

generally was upward.

The tracer test was designed to minimize disturbance

to the natural flow field—therefore, a small volume

(0.139 liter) of highly concentrated tracer solution was 

injected. The initial concentration of bromide tracer was 

100,000 mg/L, and the initial concentration of sulfur 

hexafluoride was 23.3 mg/L, or 23,300,000 ng/L. Minimal 

water was removed from the system during sampling. The 

first samples were collected 13 days after injection of the 

bromide/SF6 solution, and relatively few samples were col-
Analy sis of the Tracer Movement 29

lected until 60–104 days after injection. This time lag 

between injection and the first major sampling round may be 

one reason that the peak tracer concentrations from samples 

were two or more orders of magnitude smaller than the initial concentrations.

Bromide Breakthrough Curves

Level H—The bromide breakthrough curves for level H 

(where the tracer was injected) are shown in figures 16a–c. 

At the injection point (the 0-in. radius), no samples were collected until 104 days after injection to reduce the possibility 

of removing a large fraction of the tracer mass. The small 

concentrations shown in this curve indicate that the bromide 

tracer had indeed moved away from the injection point 

before samples were collected. The largest concentrations in 

level H (about 250–300 mg/L) were at the 7-in. radius, at 

30-, 90-, and 210-degree orientations to the creek (fig. 16b). 

The largest concentrations for all sampling locations on the 

7-in. radius in level H were detected within 45 days after 

tracer injection. Peak concentrations detected on the 

14-in. radius were smaller (less than 50 mg/L) than those on 

the 7-in. radius, and they occurred between 45–103 days 

after tracer injection (fig. 16c).

Level G—The peak bromide concentration in level G 

(6 in. above the injection level) was detected on the 

2-in. radius, 47 days after tracer injection (fig. 17a). This 

concentration of 1,040 mg/L (average of replicate samples 

with concentrations of 991 and 1,090 mg/L) was the largest 

bromide concentration detected during the tracer experiment. Peak concentrations of bromide detected at points on 

the 7-in. radius of level G (fig. 17b) ranged as high as 

340 mg/L, which is comparable to the peak concentrations in 

level H below. On the 14-in. radius, the highest concentration (104 mg/L) was detected 75 days after tracer injection, 

at a sampling point oriented 105 degrees from the creek 

(G14-105, fig. 17c). The next largest peak (49 mg/L) was 

detected 50 days later at a sampling point oriented 

22 degrees from the creek (fig. 17c).

Level F—Breakthrough curves for bromide concentrations 

in level F (12 in. above the injection level) are shown

in figures 18a–c. Peak concentrations of bromide of 

about 300–400 mg/L were detected in samples from the 

2-in. radius in level F (fig. 18a). Peak concentrations for 

bromide at several locations on the 7-in. radius in level F 

(fig. 18b) were about half as large as the concentrations on 

the 2-in. radius for this level (fig. 18a), with peak concentrations ranging from 35 mg/L (at F07-315) to 185 mg/L (at 

F07-075) (fig. 18b). On the 14-in. radius in level F (fig. 

18c), the largest peak concentration was 60 mg/L, at 

sampling location F14-045.

Level E—Breakthrough curves for bromide concentrations for level E (figs. 19a–c), which is 18 in. above the 

injection level, exhibit some features that were not apparent 

in curves from the lower levels. Unlike levels F, G, and H, 

the largest peak concentration (214 mg/L) was detected 

on the 14-in. radius (fig. 19c) rather than on the 2-in. (fig. 

19a) or the 7-in. (fig. 19b) radius. Additionally, the peak 

concentration from the sampling point on the 2-in. radius 

(106 mg/L) was very similar to the largest peak concentration in sampling points on the 7-in. radius (E07-045, 

112 mg/L), whereas in the F level, concentrations on the

2-in. radius (fig. 18a) were at least 100 mg/L larger than the 

peak concentrations on the 7-in. radius (fig. 18b). The drop 

in concentration for points on the 2-in. radius from level F to 

level E (371 mg/L in level F to 106 mg/L in level E) is consistent with the drop in concentration on the 2-in. radius 

from level G (1,040 mg/L) to level F (371 mg/L).

The large peak bromide concentration at E14-277 on the 

14-in. radius (214 mg/L, 174 days after tracer injection) (fig. 

19c) is difficult to explain with the available data. Not only 

is this peak the largest concentration in level E, it also is 

larger than any concentration on the 14-in. radii in levels H, 

G, or F below (figs. 16c, 17c, and 18c respectively). It is 

possible that (a) a slug of tracer moved towards E14-277 

through a preferential pathway between the sampling points 

in the lower layers; (b) a slug of tracer moved past the various sampling points between sampling events (that is, the 

peak was missed); (c) a slug of tracer moved outside of the 

array boundary in the lower layers before moving back into 

the tracer array at level E; or (d) the concentration at E14-

277 is incorrect because of an error in sample handling or 

analysis.

Level D—Breakthrough curves for bromide concentrations in level D (24 in. above the injection level) on the 

2-, 7-, and 14-in. radii are shown in figures 20a–c. For the 

sampling location on the 2-in. radius, it appears that the peak 

concentration could have occurred between two sampling 

events and therefore was missed. Nearly identical concentrations in samples collected 46 and 89 days after tracer 

injection (fig. 20a) indicate that a peak could have occurred 

between those two sampling dates. Peak concentrations of 

bromide at three sampling points on the 7-in. radius (fig. 

20b) and one point on the 14-in. radius (fig. 20c) exceeded 

the largest concentration detected at the location on the 

2-in. radius for level D (fig. 20a). No concentration on any 

radius of the D level was as large as the 214-mg/L concentration on the 14-in. radius of level E (E14-277). The largest 

concentration on the 14-in. radius of level D (D14-052, 

59 mg/L at 104 days after tracer injection) occurred earlier 

and on the opposite side of the tracer array from the anomalous peak in the level below, at E14-277 (figs. 19c and 20c).

Level C—Breakthrough curves for bromide in level C 

(figs. 21a–c), which is 30 in. above the injection level, are 

somewhat different from the lower levels, indicating a possible transition in tracer movement. The point on level C in 

the center of the array did not exhibit any clear peak (fig. 

21a), and concentrations fluctuated below 10 mg/L for the 

duration of the tracer test. Many of the points on the 

7-in. radius (fig. 21b) and 14-in. radius (fig. 21c) were similar. In addition, each breakthrough curve had a low point 

during the sampling event at 244 days (figs. 21a–c) and 

ended with a larger concentration at 374 days after tracer 

injection. The largest peak concentration of bromide in level 

C (48 mg/L at 76 days after injection) was detected at 

C07-067 on the 7-in radius (fig. 21b). 
30 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Analy sis of the Tracer Movement 31
32 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Analy sis of the Tracer Movement 33
34 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Analy sis of the Tracer Movement 35
36 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Analy sis of the Tracer Movement 37
38 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD

Levels B and A—Bromide breakthrough curves in levels B 

and A (figs. 22a–c and 23a–c), 36 and 42 in. above the injection level, were similar to curves from many of the sampling 

points in level C. As was the case with concentrations in 

level C, concentrations in levels B and A generally fluctuated between about 1 and 10 mg/L (the only detection larger 

than 10 mg/L was at A14-015). A small concentration (less 

than or equal to 1 mg/L) was detected in each location during 

the sampling episode at 243 days, and concentrations 

increased again between 243–375 days after tracer injection 

(figs. 22a–c and 23a–c). For many of the sampling locations 

in levels B and A, the largest bromide concentrations 

detected were at the end of the test (figs. 22a–c and 23a–c). 

It is unclear why the concentrations fluctuated as they did in 

these upper two levels; however, the magnitude of these concentrations is very small compared to the bromide concentrations that were observed in the deeper levels of the array.

Sulfur Hexafluoride Breakthrough Curves Because 

sulfur hexafluoride and bromide are considered to be conservative tracers that do not adsorb onto sediment (Harden and 

others, 2003; Wilson and Mackay, 1993), it was expected 

that both tracers would behave in a similar fashion. Analysis 

of breakthrough data from the West Branch Canal Creek 

tracer test, however, showed differences between the two 

tracers in almost every sampling level of the tracer array. In 

several instances, for example, anomalously large concentrations of one tracer were not matched by large concentrations 

of the other. Differences in behavior between the tracers are 

described below.

Level H—Breakthrough curves of sulfur hexafluoride in 

level H (where the tracer was injected) are shown in figures 

24a–c. As with bromide, no samples were collected from 

the injection point until 104 days after injection to reduce the 

possibility of removing a large fraction of the tracer mass. In 

contrast with bromide, the sulfur hexafluoride concentration 

in the sample from the injection point (fig. 24a) was large 

(355,584 ng/L) relative to the concentrations at other sampling locations. It was the largest concentration of sulfur 

hexafluoride detected during any of the four major sampling 

episodes, and it is an indication that the sulfur hexafluoride 

tracer did not move away from the injection point as efficiently as the bromide tracer.

Peak concentrations of sulfur hexafluoride from samples 

on the 7-in. (fig. 24b) and 14-in. (fig. 24c) radii in the injection level (level H) were much smaller than the largest concentration measured at the injection point. The breakthrough 

curves on the 7-in. radius (fig. 24b) showed concentration 

fluctuations over time, which indicates a high likelihood that 

peaks occurred between sampling events.

Level G—Sulfur hexafluoride breakthrough curves for 

level G (6 in. above the injection level) are shown in figures 

25a–c. The largest peak concentration detected in this level 

was 87,427 ng/L at G02-000 on the 2-in. radius (fig. 25a). 

On the 7-in. radius (fig. 25b), the sulfur hexafluoride breakthrough curves in level G (6 in. above the injection level) 

fluctuated similarly to those from the 7-in. radius in the 

injection level (level H, fig. 24b). This concentration pattern was not as apparent on the 14-in. radius of level G (fig. 

25c), but it is possible that the highest concentrations for 

these sampling points coincided with days that were between 

sampling events, and peak concentrations might have been 

missed.

Level F—Breakthrough curves for sulfur hexafluoride in 

level F (12 in. above the injection level) are shown in figures 

26a–c. The largest peak concentration of sulfur hexafluoride 

(over 11,000 ng/L) in level F was detected on the 2-in. radius 

at F02-195 (fig. 26a). Concentrations of sulfur hexafluoride 

on the breakthrough curves for each of the level F sampling 

points on the 2-in. radius fluctuated throughout the tracer 

experiment. On the 7-in. radius in level F, sulfur-hexafluoride concentrations (fig. 26b) fluctuated in a similar manner 

to those on the 2-in. radius. On the 14-in. radius of level F, 

the peak concentrations for sulfur hexafluoride (fig. 26c) 

were very similar for two of the sampling points (943 ng/L at 

site F14-045 and 915 ng/L at site F14-210).

Level E—Sulfur hexafluoride breakthrough curves for 

level E (18 in. above the injection level) are shown in figures 

27a–c. The largest concentration of sulfur hexafluoride

in level E (5,611 ng/L) was detected at E07-045 on the

7-in. radius (fig. 27b). The magnitude of this peak was similar to some of the highest peak concentrations in level F, 

located 6 in. below level E. One data anomaly on the

14-in. radius of level E is that the large bromide concentration detected 174 days after injection at site E14-277 (fig. 

20c) was not matched by a similarly large sulfur-hexafluoride concentration on any of the sampling days (fig. 27c).

Level D—Breakthrough curves of sulfur hexafluoride 

concentrations for level D (24 in. above the injection level) 

are shown in figures 28a–c. For the sampling point on the 

2-in. radius (fig. 28a), concentrations of sulfur hexafluoride 

detected on the first and last sampling dates were virtually 

identical (474 and 476 ng/L, respectively) and were the largest concentrations detected at that point.

As with the bromide breakthrough curves for level D, 

concentrations of sulfur hexafluoride at three points on the

7-in. radius (fig. 28b) and one point on the 14-in. radius (fig. 

28c) exceeded the peak concentrations detected in the sampling point on the 2-in. radius (fig. 28a). On the 7-in. radius, 

D02-022 showed the largest peak concentrations of the sulfur hexafluoride (fig. 28b) and bromide (fig. 20b) tracers. 

The sampling points that had the third largest peak concentrations on the 7-in. radius were different for each tracer 

(D07-337 for bromide, and D07-165 for sulfur hexafluoride; 

figs. 20b and 28b respectively).

Level C—Sulfur hexafluoride breakthrough curves in 

level C, which is 30 in. above the injection level and 

18 in. below land surface, are shown in figures 29a–c. As 

was the case with the curves for bromide, no clear single 

peak sulfur hexafluoride concentration is apparent for the 

sampling point in the center of the tracer array (C00-000, fig. 

29a); instead, peaks of similar concentration can be seen 

near the beginning and the end of the tracer test. On the 

7-in. radius of level C, the largest sulfur hexafluoride peak 

was at C07-067 (760 ng/L; fig. 29b). This is more than 
Analy sis of the Tracer Movement 39
40 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Analy sis of the Tracer Movement 41

 
42 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Analy sis of the Tracer Movement 43
44 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Analy sis of the Tracer Movement 45
46 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Analy sis of the Tracer Movement 47

10 times the peak concentration at the sampling point in the 

center of the array (72.3 ng/L at C00-000), and slightly less 

than 10 times the peak concentration on the 14-in. radius 

(82.8 ng/L at C14-030).

Level B—Breakthrough curves for sulfur hexafluoride 

concentrations in level B, which was 36 in. above the injection level and 12 in. below land surface, are shown in figures 

30a–c. Breakthrough curves of concentrations of sulfur 

hexafluoride for sampling points on the 2-in. radius did not 

appear to have definitive peaks (fig. 30a). The largest peak 

concentration on the 2-in. radius in level B was the last sample collected from B02-307 (fig. 30a). It should be noted 

that the sulfur hexafluoride concentration was larger in the 

last sample (375 days) at each location than at the sample 

before, collected 243 days after tracer injection (fig. 30b). 

For the sampling points in level B on the 14-in. radius (fig. 

30c), peak concentrations for the sulfur hexafluoride probably occurred between sampling dates.

Level A—Sulfur hexafluoride breakthrough curves for 

level A, located 6 in. below land surface and 42 in. above the 

injection level, are shown in figures 31a–c. The peak concentration of sulfur hexafluoride in the center of level A 

(A00-300, fig. 31a) was about 11 ng/L, which is very small. 

A much larger concentration of 186 ng/L was detected in the 

first sample collected from A07-142, on the 7-in. radius of 

the tracer array (fig. 31b). Peak concentrations detected in 

samples from the 14-in. radius at this level were similar in 

magnitude to those at the sampling point in the center of the 

array.

Isoconcentration Contour Plots

To facilitate interpretation of the tracer-test data and 

communication of the results, two-dimensional representations of the tracer concentration distributions were constructed for the four major sampling episodes (three for 

fluorescein). These two-dimensional representations include 

planar “depth slices” for the eight depths that were sampled 

throughout the experiment, and for the data points that were 

nearest to a single vertical planar section oriented along a 

north-south axis (figs. 32a–c, 33a–d, and 34a–d). Concentration values were plotted and isoconcentration contour 

lines were drawn for each horizontal depth slice and vertical 

planar section. Isoconcentration contour lines were generated using S-Plus 2000 Professional Release 3 (Copyright 

1988-2000, Mathsoft, Inc.), using bivariate interpolation to 

perform smooth-surface fitting for the data, following methods described in Akima (1978). The resulting isoconcentration contours were then manually adjusted, using professional judgment, to eliminate or correct spurious results in 

data-poor areas of the plots and to accommodate knowledge 

of the system that could not be captured using pure bivariate 

interpolation. 

Isoconcentration contour plots were generated for each 

of the three tracer compounds (fluorescein dye, bromide, and 

sulfur hexafluoride). Although fluorescein dye is considered 

to be a non-conservative tracer and would be expected to 

adsorb to sediments, its movement (or relative lack thereof) 

is useful as an indicator of the hydrologic integrity of the 

tracer array (figs. 32a–c). Hydrologic short-circuiting due to 

potential preferential flow along the sides of the injection 

piezometer or sampling piezometers, if it occurred, was 

expected to be noticeable as rapid upward movement of the 

dye within the first month of the tracer test. Such movement 

was not evident throughout the period of the tracer test (figs. 

32a–c). Indeed, the fluorescein dye exhibited relatively little 

movement, even at 412–424 days after injection (fig. 32c). 

The behavior of the fluorescein dye, as illustrated by the isoconcentration contours, could provide insight into the likely 

behavior of other non-conservative solutes with similar 

properties.

As discussed earlier, the analysis of spatial moments is 

an effective way to track tracer mass over time and to fully 

characterize the results of a three-dimensional tracer test. 

This analysis ordinarily is accomplished by numerically 

solving one or more triple integrals of tracer concentration in 

the three-dimensional space of the test domain. The numerical integration would require that the tracer concentrations 

be interpolated onto a pre-determined grid. For the tracer 

experiment at West Branch Canal Creek, however, this 

would be difficult to do accurately because the concentration 

data (Appendix B2, and figs. 33–34) indicate that for the 

conservative tracers, much of the tracer mass was transported beyond the lateral boundaries of the tracer array, 

possibly because of density differences between the tracer 

solution and the ambient ground water in the early part of 

the test, or because of dispersive processes. Tracer concentrations in samples collected from piezometers in the 

14-in. radius of the tracer array often were above the RLs. It 

is likely that tracer mass lost beyond the lateral boundaries of 

the array remained in close proximity to the array; however, 

the concentrations outside of the tracer array were not routinely measured. This means that the total mass cannot be 

accounted for by interpolation within the volume contained 

within the array of the sampling points, and that extrapolation would also be required. Unfortunately, there is no clear 

way to ensure that the method of extrapolation would produce the correct results, as different extrapolation assumptions would result in different interpreted configurations of 

tracer mass within and outside of the array.

In the analysis that follows, the tracer array was assumed 

to represent a cylinder of material that extended slightly 

beyond the volume delineated by the sampling points themselves. The height of this cylinder was assumed to be 48 in., 

extending from 3 in. above level A (6 in. below land surface) 

to 3 in. below level H (the injection level, 48 in. below land 

surface). This dimension was selected so that the volume of 

material from beyond the top and bottom levels of sampling 

points was equivalent to one-half of the volume contained 

between sampling levels. The radius of this cylinder was 

assumed to be 16.4 in., which was selected so that the volume of material between radii of 14 and 16.4 in. was equivalent to one-half of the volume contained between the 7- and 

14-in. radii of sampling points. On the basis of the volume 

for a porous cylinder of the above specifications and an 

effective porosity of 0.40 (porosity from Lorah and others, 
48 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Analy sis of the Tracer Movement 49
50 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Analy sis of the Tracer Movement 51

1997), the volume of water represented by the tracer array 

was determined to be 266 liters (L). If a higher porosity 

value of 0.55 were assumed, which would be consistent with 

National Soil Survey Center data for the area (Soil Survey 

Staff, 2004), the volume of water represented by the tracer 

array would be 366 L.

Estimates of the total tracer mass measured in the array 

were obtained for bromide and sulfur hexafluoride for each 

of the four major sampling episodes by multiplying the mean 

concentration for each sampling episode by the volume of 

water represented by the array. The tracer mass values for 

each major sampling episode were then divided by the 

injected tracer mass to determine the percentage of the original tracer mass that was recovered, and to evaluate possible 

mass loss outside of the sampled volume. [The mass of bromide initially injected into the array was 13,900 milligrams 

(100,000 mg/L * 0.139 L), and the mass of sulfur hexafluoride injected into the array was 3.2 x 106 nanograms

(23.3 mg/L * 0.139 L).] Tracer mass values calculated in 

this manner can be uncertain because (1) the porosity is not 

known with certainty, (2) all of the sampling points were 

weighted equally even though they were not uniformly 

spaced throughout the array, and (3) tracer concentrations 

between sampling points and immediately outside of the 

array were assumed to be represented by the points that were 

sampled.

Bromide Concentrations The isoconcentration contour 

plots for bromide concentrations within the tracer array during the four major sampling episodes are shown in figures 

33a–d. Isoconcentration contour plots representing sampling results from 103–104 days (fig. 33a), 167–174 days 

(fig. 33b), 243–250 days (fig. 33c), and 363–375 days (fig. 

33d) after injection illustrate the movement of the bromide 

tracer over time. 

The results of the first major sampling episode for 

bromide (103–104 days after tracer injection) are shown in 

figure 33a. The highest bromide concentration during this 

sampling episode (296 mg/L) was in level G (42 in. below 

land surface, and 6 in. above the injection layer), near the 

center of the array (fig. 33a). This concentration is almost 

three orders of magnitude smaller than the injected concentration of 100,000 mg/L, indicating that considerable dilution of the tracer slug had occurred. In addition, bromide 

concentrations greater than the background level of 0.5 mg/L 

(Spencer and others, 2000) were detected at all of the sampling points during this time step, which indicates that bromide was transported upwards and outwards into the array, 

and possibly beyond the boundaries of the array. Concentrations as high as 59 mg/L were detected in samples from 

the outermost radius of 14 in. (at level D, 24 in. above the 

injection layer), which indicates the loss of bromide out of 

the side of the array. The concentration distribution (fig. 33) 

also indicates that the tracer movement was mostly upwards, 

with a slight bias to the north. The mean bromide concentration for all samples from the first major sampling episode 

was 35.6 mg/L. Multiplying by the water volume in the 

array (266 L, assuming an effective porosity of 0.40) gives 

an estimated mass of 9,500 mg (milligrams) of bromide, or 

about 68 percent of the injected tracer mass. If an effective 

porosity of 0.55 were assumed, the tracer mass for bromide 

measured during the first major sampling episode would be 

about 13,000 mg, or approximately 94 percent of the injected 

tracer mass.

The second major sampling episode for bromide took 

place 167–174 days after injection. The results (fig. 33b) 

show little evidence of upward tracer transport compared to 

the previous sampling episode (fig. 33a). There was evidence, however, of horizontal movement to the north, indicated in levels D, F, and G, 24 to 42 in. below land surface 

(6 to 24 in. above the injection level). As with the first sampling episode, bromide concentrations above background 

(0.5 mg/L) were present in samples collected from the outer 

radius of the tracer array at all depths (fig. 33b), which indicates horizontal loss of bromide from the array. One unexpectedly large bromide concentration (214 mg/L at E14-277) 

was seen in the horizontal depth slice for level E (30 in. 

below land surface, 18 in. above the injection level), on the 

outside edge of the tracer array (fig. 33b). This concentration is about two orders of magnitude greater than the 

concentration at the same sampling point at 103–104 days 

after injection (fig. 33a). A transport pathway for this high 

bromide concentration is not evident from examination of 

the breakthrough curves (figs. 16–23) and the data table 

(Appendix B2); however, several potential causes of this 

anomalous concentration were noted in the earlier discussion 

of break-though curves for bromide on level E (p. 48, fig. 

19c.), including the possibility that a slug of tracer moved 

towards E14-277 through a preferential pathway between 

the sampling points in the lower layers. The mean bromide 

concentration for the second major sampling episode was 

13.4 mg/L, which indicates that an estimated mass of 

about 3,600 mg (26 percent of the initial mass) of bromide 

remained within the array, if an effective porosity of 0.40 

were assumed. If an effective porosity of 0.55 were 

assumed, the bromide mass accounted for in the second 

major sampling episode would be about 4,900 mg, or 

35 percent of the initial mass.

The third complete sampling episode (243–250 days 

after injection, fig. 33c) also did not indicate much upward 

movement, other than the reduced concentrations apparent in 

levels G and H (42 and 48 in. below land surface, respectively). Concentrations in all levels, however, appeared to be 

reduced, as only three sampling points had bromide concentrations greater than 10 mg/L (fig. 33c). Bromide concentrations at some points in levels F, G, and H (36, 42, and 48 in. 

below land surface) were at background levels (0.5 mg/L or 

less), and many points had bromide concentrations between 

0.5 and 1 mg/L (fig. 33c). As with the earlier sampling periods (figs. 33a–b), mass loss out of the sides of the array is 

apparent (fig. 33c). The estimated mass of bromide tracer, 

calculated based on a mean concentration of 2.0 mg/L for the 

third time step, was 540 mg (almost 4 percent of the initial 

mass) for an effective porosity of 0.40, or 740 mg (over 5 

percent of the initial mass) for an effective porosity of 0.55.
52 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Analy sis of the Tracer Movement 53
54 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Analy sis of the Tracer Movement 55
56 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD

The fourth and final sampling episode took place 

363–375 days after injection of the tracers (fig. 33d). Continuing the trend observed in the previous sampling episodes 

(figs. 33a–c), concentrations in levels G and H (42 and 48 in. 

below ground surface, fig. 33d) for the fourth sampling episode dropped below the reporting limit (1.0 mg/L), which is 

near the background concentration of 0.5 mg/L or less 

(Spencer and others, 2000). Bromide concentrations in the 

upper sampling points in the tracer array 6–12 in. below land 

surface, (fig. 33d) unexpectedly increased, however, after 

having decreased during the previous two sampling episodes 

(figs. 33b–c). These concentrations are an order of magnitude above background levels, so it is likely that they 

resulted from injected bromide tracer rather than background 

concentrations of bromide in the ambient ground water; 

however, the cause of the late increase in concentrations is 

not known. The mean concentration of bromide during the 

fourth sampling episode (3 mg/L) was slightly larger than 

the mean from the third sampling episode (2 mg/L). The 

mass of bromide in the fourth sampling episode was estimated to be 880 mg (about 6 percent of the initial mass) 

based on an effective porosity of 0.40, or 1,200 mg (almost 9 

percent of the initial mass) based on an effective porosity of 

0.55.

The inferred movement of bromide tracer (figs. 33a–d), 

coupled with the apparent loss of tracer mass throughout the 

test, shows qualitatively that in addition to vertical flow, 

there is a northward horizontal component to ground-water 

flow in the area of the tracer array. As it is possible that the 

tracer solution sank below the injection point at the beginning of the test and then did not move as a discrete pulse, 

calculations of the magnitude or direction of the velocity 

vector from these data would have some degree of uncertainty.

Sulfur Hexafluoride Concentrations Isoconcentration 

contour plots were constructed for sulfur hexafluoride concentrations to show the movement of this tracer over time 

(figs. 34a–d). The four major sampling episodes for sulfur 

hexafluoride were the same as for the bromide: 103–104 

days (fig. 34a), 167–174 days (fig. 34b), 243–250 days (fig. 

34c), and 363–375 days (fig. 34d) after tracer injection.

The results of the first complete sampling episode for 

sulfur hexafluoride (103–104 days after tracer injection) are 

shown in figure 34a. In contrast with the results from the 

bromide tracer (fig. 34a), the largest concentration of sulfur 

hexafluoride tracer (355,584 ng/L) was detected at the injection point rather than at a sampling point in the next highest 

level. This concentration is less than 2 percent of the initial 

sulfur hexafluoride tracer concentration (23,300,000 ng/L), 

which represents dilution that is similar to the dilution of the 

largest concentration of bromide (relative to the initial concentration) during the first sampling episode.

As with bromide, the movement of sulfur hexafluoride 

between the time of injection and the first major sampling 

episode (fig. 34a) appeared to be upward, with a slight bias 

to the north, primarily in levels H and G (48 and 42 in. below 

land surface, respectively). A concentration of 1,376 ng/L of 

sulfur hexafluoride at one sampling point and many other 

detections greater than 100 ng/L on the outermost (14-in.) 

radius indicate the loss of tracer mass beyond the lateral 

boundaries of the array (fig. 34a). In addition, the mean 

concentration of sulfur hexafluoride for the first major sampling episode was 6,150 ng/L, which, when multiplied by 

the water volume in the array, gives an estimated mass of 

1.64 x 106 ng, or about 51 percent of the initial mass of sulfur hexafluoride injected at the beginning of the tracer test, if 

a porosity of 0.40 is assumed. If a porosity of 0.55 were 

assumed, the estimated mass of sulfur hexafluoride in the 

array would be 2.26 x 106 ng, or about 70 percent of the initial mass that was injected. 

The second major sulfur hexafluoride sampling round 

took place 167–174 days after tracer injection. No sample 

was collected at the injection point during this sampling episode. The highest tracer concentration (25,536 ng/L) was in 

level G, 6 in. above the injection level (fig. 34b). Concentrations larger than 1,000 ng/L were detected at two or more 

points in each of the bottom five sampling levels (48 to 

24 in. below land surface), which was generally about 12 in. 

farther upward from the injection point than the locations in 

which similar concentrations had been measured during the 

first sampling episode. Lateral spreading had continued, 

with many sampling points on the 14-in. radius having concentrations larger than 1,000 ng/L (fig. 34b). A comparison 

of concentration distributions indicated that the tracer 

motion was upward and somewhat to the north between the 

first two sampling episodes. In the upper layers of the array 

(24 to 6 in. below land surface), concentrations at many 

points had decreased to less than 1 ng/L from higher values 

measured during the previous sampling episode, possibly 

indicating an influx of ambient ground water into those layers. The mean concentration of sulfur hexafluoride during 

the second major sampling episode was 1,500 ng/L. Multiplying this concentration by the water volume in the tracer 

array results in an estimated mass of about 12 percent of the 

amount that was initially injected if an effective porosity of 

0.40 were assumed, or about 17 percent of the injected mass 

if an effective porosity of 0.55 were assumed.

The third major sampling round for sulfur hexafluoride 

occurred 243–250 days after tracer injection. Tracer concentrations from this sampling event (fig. 34c) appear to be 

distributed similarly to the previous sampling event, but 

more dilute. The largest concentration of sulfur hexafluoride 

detected for the third time step was 8,263 ng/L (in level 

F, 12 in. above the injection level), but no sample was collected from the injection point. Concentrations larger 

than 1,000 ng/L were detected at only seven other sampling 

points (fig. 34c) during this time step. Samples from nearly 

all locations in levels B and A (12 and 6 in. below land 

surface) had concentrations less than 1 ng/L. The mean concentration for the array during the third major sampling episode was 450 ng/L, which results in an estimated mass of 

118,000 ng of sulfur hexafluoride (assuming an effective 

porosity of 0.40), or less than 4 percent of the initial injected 

mass. If an effective porosity of 0.55 were assumed, the esti-
Analy sis of the Tracer Movement 57
58 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Analy sis of the Tracer Movement 59
60 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Analy sis of the Tracer Movement 61

mated mass would be 162,000 ng, which is about 5 percent 

of the initial injected mass.

For the fourth major sampling episode, sulfur hexafluoride samples were collected from 363–375 days after tracer 

injection (fig. 34d). The largest concentration detected during this time step was 8,195 ng/L, which is similar to the 

largest concentration that was detected during the third sampling episode. This concentration was detected at the injection point, which had not been sampled during the previous 

two sampling episodes. In contrast with the previous two 

episodes, concentrations of sulfur hexafluoride in all of the 

sampling locations during the fourth sampling episode were 

larger than 1 ng/L. A similar result was found for the bromide (figs. 33a–d), for which the concentrations in the upper 

layers of the array had increased between the third and fourth 

time steps. It is not clear why this occurred; however, it is 

possible that seasonal differences in temperature, rainfall, 

and evapotranspiration could have diluted the tracer concentrations in the near-surface layers of the array during the 

third sampling episode (May 1999), and subsequently 

increased concentrations during the fourth sampling episode 

(September 1999). The mean concentration of sulfur 

hexafluoride for the entire array during the fourth sampling 

round was 300 ng/L, which was smaller than the mean for 

the third sampling round. The tracer mass estimated from 

this mean was about 3 or 4 percent of the initial injected 

mass of sulfur hexafluoride, assuming an effective porosity 

of 0.40 or 0.55 (respectively) for the calculations of water 

volume in the array.

As was the case with the bromide tracer, qualitative interpretation of isoconcentration curves for sulfur hexafluoride 

(figs. 34a–d) indicates that a northward horizontal component of ground-water flow was present along with the vertical component. In addition, because the sulfur hexafluoride 

tracer did not move as a discrete pulse, it is difficult to accurately calculate the magnitude and direction of the velocity 

vector from these data.

Comparison of Tracers

After injection, the fluorescein showed much less 

spreading than the bromide and sulfur hexafluoride, 

and its center of mass remained near the injection point 

(figs. 32a–c). Even during the fourth major sampling 

episode (412–424 days after fluorescein-dye injection), 

the fluorescein-dye pulse had retained nearly the same 

position and shape as it had during the first major sampling 

episode. Because fluorescein dye is known to participate in 

sorption reactions with mineral surfaces and organic matter 

(Kasnavia and others, 1999; Sabatini and Austin, 1991), the 

transport of the dye should be similar to that of other solutes 

that participate in sorption reactions. The VOCs that are the 

major contaminants in the wetland study area are also known 

to sorb to organic matter in the sediments (Lorah and others, 

1997, p. 83). The octanol-water partitioning coefficient, 

KOW, is a measure of partitioning of a solute from aqueous 

solution into an organic phase (octanol) and can be used to 

evaluate the tendency of a solute in a ground-water system to 

adsorb to organic matter (Piwoni and Keeley, 1990). KOW

values typically vary over several orders of magnitude and 

therefore are expressed as logarithms. The log KOW values 

for the VOCs of interest are slightly lower than the log KOW 

for fluorescein; therefore, the transport of these VOCs 

would be expected to be retarded because of sorption, but to 

a lesser extent than would be seen for fluorescein. Of the 

VOCs listed below, vinyl chloride would be expected to 

exhibit the least amount of retardation because of sorption.

Breakthrough curves of bromide and sulfur hexafluoride 

concentrations with time were plotted for each sampling 

point to compare different spatial characteristics of tracer 

movement. Analysis of breakthrough data showed differences between the two tracers in almost every sampling level 

of the tracer array. In several instances, for example, anomalously large concentrations of one tracer were not matched 

by large concentrations of the other. One place this occurred

 

Substance Log KOW value(s) Reference

Fluorescein dye 3.35 Calculated using methods described by Meylan 

and Howard (1995)

1,1,2,2-Tetrachloroethane 2.56, 2.39 Reported by Montgomery and Welkom (1990)

1,1,2-Trichloroethane 2.18 Reported by Montgomery and Welkom (1990)

Trichloroethene 2.53, 2.29, 2.42, 2.60, 

3.24, 3.30, 2.37, 3.03

Reported by Montgomery and Welkom (1990)

cis-1,2-Dichloroethene 1.41 Reported by Montgomery and Welkom (1990)

trans-1,2-Dichloroethene 2.09 Reported by Montgomery and Welkom (1990)

Vinyl chloride 0.60 Reported by Montgomery and Welkom (1990)
62 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD

was at the injection point (H00-000), where the highest 

detection of sulfur hexafluoride was observed at the same 

time as a relatively low detection of bromide. This observation, made 104 days after tracer injection, indicates that the 

bromide tracer moved away from the injection point more 

efficiently than sulfur hexafluoride.

Isoconcentration contour plots for bromide (figs. 33a–c) 

and sulfur hexafluoride (figs. 34a–c) also showed that the 

bromide pulse generally moved away from the injection 

point more rapidly than the sulfur hexafluoride pulse; however, there were a few specific sampling points in the middle 

and upper levels of the tracer array in which a portion of the 

sulfur hexafluoride appeared to have outpaced the bromide. 

On October 1, 1998 (27 days after injection), site D07-165 

had replicate samples with concentrations of 432 ng/L and 

378 ng/L of sulfur hexafluoride, compared to concentrations 

of 1.7 mg/L and 1.4 mg/L of bromide.

 To verify that these trends were not an artifact of the 

different initial concentrations and reporting limits for the 

bromide and sulfur hexafluoride, the comparison of tracer 

movement was considered in reference to the original 

injected concentrations by calculating dimensionless concentrations (C/C0 ) by dividing the tracer concentration (C) 

for each measurement by the injected concentration (C0). 

For site D07-165, at which sulfur hexafluoride was thought 

to have outpaced bromide, the dimensionless concentrations 

for replicate samples collected on October 1, 1998, were 

0.000019 and 0.000016 for sulfur hexafluoride, compared to 

dimensionless concentrations of 0.000017 and 0.000014 for 

bromide. This indicates that although sulfur hexafluoride 

may have slightly outpaced bromide at this site, the relative 

concentrations are very similar, and any potential acceleration of sulfur hexafluoride compared to bromide is likely to 

have been localized and minor. Dimensionless concentrations were also used to verify the hypothesis that the bromide 

pulse as a whole had moved away from the injection point 

more rapidly than the sulfur hexafluoride pulse. A comparison of the relative movement of the bromide and sulfur 

hexafluoride using the dimensionless concentrations and the 

same vertical scales, for levels A through H of the array is 

shown in figure 35. The bromide peak is apparent in shallower depth intervals and earlier in the tracer test than the 

sulfur hexafluoride peak (fig. 35). In addition, a larger portion of the tracer mass is evident in the tracer array for the 

bromide compared to the sulfur hexafluoride, especially in 

the upper levels of the array. 

As the comparison of tracers indicates that the bulk of the 

sulfur hexafluoride was somewhat retarded compared to the 

bromide, a sorption test was performed to evaluate the 

potential for the sulfur hexafluoride to adsorb to the organicrich wetland sediments. The sorption test was conducted 

using replicate sets of serum vials containing a 1:6 ratio of 

deionized water to wetland sediment, which were spiked 

with a solution of sulfur hexafluoride to produce an expected 

concentration of approximately 400 ng/L, and then stored 

upside-down on a shaker table at approximately 22 °C. After 

32 days of contact with the sediments, no significant 

decreases in sulfur hexafluoride concentrations were 

observed, and sorption was eliminated as a potential cause of 

the retardation of sulfur hexafluoride.

The early presence of sulfur hexafluoride at a few sites in 

the middle and upper levels of the tracer array and its persistence in the 6-in. depth throughout the duration of the experiment neither supports nor contradicts a hypothesis of 

volatilization from the saturated sediments into the overlying 

atmosphere. The wetland sediments had remained saturated 

throughout the tracer experiment, so dissolved sulfur 

hexafluoride in the ground water at the 6-in. depth would not 

have had the opportunity to come in direct contact with the 

atmosphere. Had all other hydrologic processes been 

assumed to be identical for bromide and sulfur hexafluoride, 

the absence or a rapid disappearance of sulfur hexafluoride 

from the 6-in. depth might have been assumed to be due to 

volatilization if the sediments had been unsaturated to that 

depth at any time, but this condition was not observed.

Interaction of the sulfur hexafluoride with natural marsh 

gases at depth could explain this tracer’s fate and transport. 

The major difference between bromide and sulfur hexafluoride is that sulfur hexafluoride can volatilize into any gas 

phase that is present (Wilson and MacKay, 1993). If no gas 

phase were present at depth, the sulfur hexafluoride would 

be expected to move in the same manner as bromide (conservatively). The early presence of sulfur hexafluoride at a few 

sampling points in the upper levels of the array and the 

apparent retardation of the bulk of the sulfur hexafluoride in 

the lower and middle levels of the array compared to bromide could have been due to volatilization of dissolved sulfur hexafluoride gas into small bubbles of marsh gases that 

are produced in the wetland sediments when concentrations 

of the marsh gases exceed saturation levels. Ebullition (formation of bubbles) of methane and other biogenic gases has 

been well documented in wetland environments (FechnerLevy and Hemond, 1996), and in one study of gas exchange 

in a small lake in which sulfur hexafluoride was used as a 

tracer (Cole and Caraco, 1998), methane ebullition was evaluated as a potential source of tracer loss. Sulfur hexafluoride 

volatilization into naturally present gas bubbles within the 

tracer array could have provided two additional transport 

mechanisms that are not available to bromide: (1) upward 

movement associated with gas-bubble rise, and (2) retardation associated with gas-bubble trapping. These mechanisms could explain the early presence of sulfur hexafluoride 

at a few locations in the middle and upper levels of the array, 

and the lagging of the bulk of the sulfur hexafluoride near 

the injection point through the end of the tracer test. If small 

bubbles containing sulfur hexafluoride were formed shortly 

after tracer injection, these bubbles could have acted as a 

continuing source of sulfur hexafluoride near the tracer 

injection point, as the marsh gases could have re-dissolved at 

a later time, when concentrations decreased to below saturation levels. The occasional observation of effervescent 

ground-water samples during the tracer experiment supports 

this hypothesis. Like sulfur hexafluoride, the VOCs that are 

the major contaminants in the wetland study area could be 
Analy sis of the Tracer Movement 63
64 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD

susceptible to volatilization into gas bubbles within the wetland sediments. If the volatilization hypothesis is correct, 

this transport mechanism could be an additional source of 

variability in VOC movement.

Summary and Conclusions

The U.S. Geological Survey, in cooperation with the 

U.S. Army, conducted a small-scale natural-gradient groundwater tracer test during a period of approximately 1 year. 

This tracer test was conducted within saturated sediments in 

a freshwater tidal wetland near West Branch Canal Creek, at 

Aberdeen Proving Ground, Maryland, as a part of ongoing 

studies of natural attenuation. The objectives of the test 

were to better characterize solute transport at the site, procure a dataset that could be used to more accurately determine the ground-water velocity in the upper wetland 

sediments, and compare a conservative, ionic tracer (bromide) to a conservative, volatile tracer (sulfur hexafluoride) 

to determine whether volatilization could affect the fate of 

volatile compounds in the ground water. The test was conducted using a cylindrical array of ninety-seven 1⁄4-inchdiameter inverted-screen piezometers within approximately 

25 cubic feet (2.3 cubic meters) of organic-rich wetland sediments, in an area with a vertically upward hydraulic gradient. Fluorescein dye was injected on July 17, 1998, as

0.025 liter of solution containing 50,000 milligrams per liter 

of sodium fluorescein, to test the hydrologic integrity of the 

tracer array prior to the injection of the conservative tracers. 

A solution of bromide ion saturated with sulfur hexafluoride 

(0.139 liter of solution containing 100,000 milligrams 

per liter of bromide ion and 23.3 milligrams per liter of 

sulfur hexafluoride) was injected 49 days later, on 

September 4, 1998. Tracer movement was monitored 

through September 14, 1999, with the collection of groundwater samples, including 644 samples that were analyzed for 

fluorescein, 617 samples that were analyzed for bromide 

with an ion-selective electrode, 213 samples that were analyzed for bromide with colorimetric methods, and 603 samples that were analyzed for sulfur hexafluoride. Additional 

samples for volatile organic compounds (96 samples) and 

methane (37 samples) were collected to determine the distribution of these contaminants and the extent of methanogenic 

conditions within the array.

Differences in the chemical properties of the three tracers 

and their movement throughout the experiment provide 

insights into contaminant fate and transport in the wetland 

sediments. Fluorescein dye proved to be a good tracer for 

evaluating the hydrologic integrity of the array of piezometers that were used in the tracer test. Fluorescein dye was 

also useful as a non-conservative tracer to illustrate the 

effects of sorption on retarding the movement of solutes that 

have similar octanol-water partitioning coefficients, including some volatile organic compounds. Bromide worked well 

as a conservative tracer for the ground-water system. Sulfur 

hexafluoride also proved to be useful as a conservative tracer 

and was detectable over the widest range of concentrations, 

eight orders of magnitude. Sulfur hexafluoride moved differently than bromide. Apparent simultaneous acceleration 

of some of the sulfur hexafluoride to discrete locations in the 

upper levels of the array and retardation of a portion of the 

sulfur hexafluoride pulse in the lower levels of the array 

could have been due to volatilization of the dissolved gas 

into small bubbles of ambient marsh gases that can be produced in the wetland sediments when concentrations of the 

gases exceed saturation levels.

Isoconcentration contour plots and breakthrough curves 

were constructed to aid in the analysis of tracer movement. 

Although bromide and sulfur hexafluoride were transported 

predominantly upward, the tracers also moved outward in all 

directions from the injection point. Concentration data at the 

lateral edges of the tracer array indicated that tracer mass 

was lost out of the sides of the array throughout the duration 

of the test. During the four major sampling episodes (103–

104, 167–174, 243–250, and 363–375 days after tracer injection), the mass of each tracer was estimated by multiplying 

the mean concentration by the approximate volume of water 

in the array. Assuming an effective porosity of 0.40, the estimated mass of bromide ranged from about 68 percent (during the first sampling episode) to as low as 4 percent of the 

mass that was initially injected, whereas the estimated mass 

of sulfur hexafluoride ranged from about 51 percent to 

3 percent of the initial mass. If an effective porosity of 0.55 

was used, these tracer masses would be higher by a factor of 

1.375. The loss of tracer mass from the array prevented a 

straightforward quantitative analysis of tracer transport and 

ground-water velocity. For these reasons, data analysis was 

limited to qualitative methods.

The distribution of bromide over time shows qualitatively that in addition to vertical flow, there is a slight northward horizontal component to ground-water flow in the area 

of the tracer array. This assumes that the lateral movement 

of bromide beyond the tracer array was similar to the direction of movement inferred by the concentration distribution 

observed within the array. Because it was possible that the 

tracer solution sank below the injection point at the beginning of the test due to density differences (the initial density 

of the tracer solution was calculated to be 1.097 grams per 

milliliter) and then did not move as a discrete pulse, calculations of the magnitude or direction of the velocity vector 

from these data cannot be performed without uncertainty. A 

comparison of bromide and sulfur hexafluoride concentrations relative to their respective injected concentrations indicates that a smaller proportion of the injected mass of sulfur 

hexafluoride moved up into the tracer array than bromide. 

On the basis of the predominantly upward movement of 

the conservative tracers and the outward movement in all 

directions from the injection point, diffusion and advection 

are thought to be the major processes responsible for the 

tracer movement. Dilution, possibly enhanced by intermittent interaction with the overlying tidal surface water, likely 

decreased the concentrations of the tracers as they were 
Summary and References Cited 65

transported upwards through the tracer array. Sorption was 

evaluated and eliminated as a potential source of retardation 

or mass loss for sulfur hexafluoride. Potential losses of sulfur hexafluoride due to volatilization from the surface of the 

water table could not be measured in the tracer array because 

the wetland sediments had remained saturated to land surface throughout the tracer test. A portion of the sulfur 

hexafluoride could have volatilized into ambient bubbles of 

biogenic marsh gases at depth; this process could explain the 

early presence of sulfur hexafluoride in a few sampling 

points in the upper levels of the tracer array (because of gasbubble rise), and the retardation of the bulk of the sulfur 

hexafluoride (because of gas-bubble trapping) in the lower 

levels of the tracer array.

The tracer movement observed and the transport processes inferred from this movement are consistent with the 

concentration distribution of the volatile organic compounds 

detected in the array; however, the circumstances of the original introduction of the volatile organic compounds to the 

site are not known with certainty, so comparisons must be 

limited. Concentrations of volatile organic compounds were 

largest in the lowest depths of the array and decreased with 

decreasing depth. In addition to the transport processes that 

affect conservative solutes such as bromide, volatile organic 

compounds can also undergo sorption and degradation, both 

of which were observed in this experiment. The volatile 

organic compounds detected in low concentrations in the 

shallow levels of the tracer array (6–24 inches below land 

surface) were nearly exclusively daughter compounds, indicating that biodegradation was transforming these compounds and reducing their mass. Methane was detected at 

depths of 6–42 inches below land surface, with the largest 

concentrations in the shallowest levels, where biodegradation was most evident by the presence of daughter compounds. This is consistent with the pattern of methanogenic 

conditions that was documented previously for this site. 

Chemical and physical processes responsible for differences 

in the transport of fluorescein and sulfur hexafluoride compared to bromide, such as sorption (resulting in retardation 

of fluorescein) and volatilization into bubbles of marsh gases 

(resulting in bulk retardation of sulfur hexafluoride with isolated instances of accelerated upward movement) are likely 

to similarly affect the transport of volatile organic compounds in the upper wetland sediments in the area around 

West Branch Canal Creek.

References Cited

Akima, H., 1978, A method of bivariate interpolation and 

smooth surface fitting for irregularly distributed data 

points: ACM Transactions on Mathematical Software, 

v. 4, p. 148–164.

Baedecker, M.J., and Cozzarelli, I.M., 1992, The 

determination and fate of unstable constituents in 

contaminated groundwater, in Lesage, S., and Jackson, 

 R.E. (eds.), Groundwater Contamination and Analysis at 

 Hazardous Waste Sites: New York, Marcel Dekker, 

p. 425–461.

Busenberg, Eurybiades, and Plummer, L.N., 1997, Use of 

sulfur hexafluoride as a dating tool and as a tracer of 

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Appendixes 67

Appendixes--A through C follow
68 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendixes 69
70 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendixes 71
Appendix B1. Site names and relative positions of tracer-test piezometers at West Branch Canal Creek,

 Aberdeen Proving Ground, Maryland

[For radial coordinates, 0 degrees points toward the creek, angle theta increases in the clockwise direction, and magnetic north is at 52 degrees.

For rectilinear coordinates, the origin is the tracer-injection site, H00-000. The X-axis is oriented perpendicular to the creek, positive on the

side of the origin that is away from the creek, and negative on the side that is closest to the creek. The Y-axis is parallel to the creek, positive

on the upstream side of the origin, and negative on the downstream side. The Z-axis is elevation and is positive in the upward direction.]

Distance Radial Coordinates Rectilinear Coordinates 

from Depth Radius Angle Distance in X, Y, and Z

injection below from theta directions from the

point, land central from origin (injection point) Site

Site calculated surface axis creek X Y Z identification

name (inches) (inches) (inches) (degrees) (inches) (inches) (inches) number

A00-300 42.00 6 0 300 -0.09 -0.16 42 392347076183801

A06-300 42.43 6 6 300 -3.00 -5.20 42 392347076183802

A07-037 42.58 6 7 37 -5.59 4.21 42 392347076183803

A07-142 42.58 6 7 142 5.52 4.31 42 392347076183804

A07-247 42.58 6 7 247 2.74 -6.44 42 392347076183805

A13-300 43.97 6 13 300 -6.50 -11.26 42 392347076183806

A14-015 44.27 6 14 15 -13.52 3.62 42 392347076183807

A14-127 44.27 6 14 127 8.43 11.18 42 392347076183808

A14-255 44.27 6 14 255 3.62 -13.52 42 392347076183809

B02-030 36.06 12 2 30 -1.73 1.00 36 392347076183810

B02-307 36.06 12 2 307 -1.20 -1.60 36 392347076183811

B07-082 36.67 12 7 82 -0.97 6.93 36 392347076183812

B07-202 36.67 12 7 202 6.49 -2.62 36 392347076183813

B07-292 36.67 12 7 292 -2.62 -6.49 36 392347076183814

B07-352 36.67 12 7 352 -6.93 -0.97 36 392347076183815

B14-037 38.63 12 14 37 -11.18 8.43 36 392347076183816

B14-187 38.63 12 14 187 13.90 -1.71 36 392347076183817

B14-337 38.63 12 14 337 -12.89 -5.47 36 392347076183818

C00-000 30.00 18 0 0 -0.18 0.00 30 392347076183819

C07-007 30.81 18 7 7 -6.95 0.85 30 392347076183820

C07-067 30.81 18 7 67 -2.74 6.44 30 392347076183821

C07-127 30.81 18 7 127 4.21 5.59 30 392347076183822

C07-217 30.81 18 7 217 5.59 -4.21 30 392347076183823

C07-262 30.81 18 7 262 0.97 -6.93 30 392347076183824

C07-322 30.81 18 7 322 -5.52 -4.31 30 392347076183825

C14-030 33.11 18 14 30 -12.12 7.00 30 392347076183826

C14-172 33.11 18 14 172 13.86 1.95 30 392347076183827

C14-270 33.11 18 14 270 0.00 -14.00 30 392347076183828

C14-322 33.11 18 14 322 -11.03 -8.62 30 392347076183829

D02-105 24.08 24 2 105 0.52 1.93 24 392347076183830

D07-022 25.00 24 7 22 -6.49 2.62 24 392347076183831

D07-105 25.00 24 7 105 1.81 6.76 24 392347076183832

D07-165 25.00 24 7 165 6.76 1.81 24 392347076183833

D07-277 25.00 24 7 277 -0.85 -6.95 24 392347076183835

D07-337 25.00 24 7 337 -6.44 -2.74 24 392347076183834

 72 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B1. Site names and relative positions of tracer-test piezometers at West Branch Canal Creek,

 Aberdeen Proving Ground, Maryland--Continued

Distance Radial Coordinates Rectilinear Coordinates 

from Depth Radius Angle Distance in X, Y, and Z

injection below from theta directions from the

point, land central from origin (injection point) Site

Site calculated surface axis creek X Y Z identification

name (inches) (inches) (inches) (degrees) (inches) (inches) (inches) number

D14-052 27.78 24 14 52 -8.62 11.03 24 392347076183836

D14-247 27.78 24 14 247 5.47 -12.89 24 392347076183837

D14-307 27.78 24 14 307 -8.43 -11.18 24 392347076183838

D14-352 27.78 24 14 352 -13.86 -1.95 24 392347076183839

D24-045 33.94 24 24 45 -16.97 16.97 24 none assigned

E02-285 18.11 30 2 285 -0.52 -1.93 18 392347076183840

E07-000 19.31 30 7 0 -7.00 0.00 18 392347076183841

E07-045 19.31 30 7 45 -4.95 4.95 18 392347076183842

E07-120 19.31 30 7 120 3.50 6.06 18 392347076183843

E07-180 19.31 30 7 180 7.00 0.00 18 392347076183844

E07-240 19.31 30 7 240 3.50 -6.06 18 392347076183845

E07-307 19.31 30 7 307 -4.21 -5.59 18 392347076183846

E14-007 22.80 30 14 7 -13.90 1.71 18 392347076183847

E14-082 22.80 30 14 82 -1.95 13.86 18 392347076183848

E14-157 22.80 30 14 157 12.89 5.47 18 392347076183849

E14-217 22.80 30 14 217 11.18 -8.43 18 392347076183850

E14-277 22.80 30 14 277 -1.71 -13.90 18 392347076183851

E14-315 22.80 30 14 315 -9.90 -9.90 18 392347076183852

F02-195 12.17 36 2 195 1.93 -0.52 12 392347076183853

F02-330 12.17 36 2 330 -1.73 -1.00 12 392347076183854

F07-015 13.89 36 7 15 -6.76 1.81 12 392347076183855

F07-075 13.89 36 7 75 -1.81 6.76 12 392347076183856

F07-157 13.89 36 7 157 6.44 2.74 12 392347076183857

F07-225 13.89 36 7 225 4.95 -4.95 12 392347076183858

F07-285 13.89 36 7 285 -1.81 -6.76 12 392347076183859

F07-315 13.89 36 7 315 -4.95 -4.95 12 392347076183860

F14-045 18.44 36 14 45 -9.90 9.90 12 392347076183861

F14-135 18.44 36 14 135 9.90 9.90 12 392347076183862

F14-210 18.44 36 14 210 12.12 -7.00 12 392347076183863

F14-292 18.44 36 14 292 -5.24 -12.98 12 392347076183864

F14-345 18.44 36 14 345 -13.52 -3.62 12 392347076183865

G02-000 6.32 42 2 0 -2.00 0.00 6.0 392347076183866

G07-060 9.22 42 7 60 -3.50 6.06 6.0 392347076183867

G07-135 9.22 42 7 135 4.95 4.95 6.0 392347076183868

G07-195 9.22 42 7 195 6.76 -1.81 6.0 392347076183869

 73 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B1. Site names and relative positions of tracer-test piezometers at West Branch Canal Creek,

 Aberdeen Proving Ground, Maryland--Continued

Distance Radial Coordinates Rectilinear Coordinates 

from Depth Radius Angle Distance in X, Y, and Z

injection below from theta directions from the

point, land central from origin (injection point) Site

Site calculated surface axis creek X Y Z identification

name (inches) (inches) (inches) (degrees) (inches) (inches) (inches) number

G07-255 9.22 42 7 255 1.81 -6.76 6.0 392347076183870

G07-300 9.22 42 7 300 -3.50 -6.06 6.0 392347076183871

G07-345 9.22 42 7 345 -6.76 -1.81 6.0 392347076183872

G14-022 15.23 42 14 22 -12.98 5.24 6.0 392347076183873

G14-105 15.23 42 14 105 3.62 13.52 6.0 392347076183874

G14-165 15.23 42 14 165 13.52 3.62 6.0 392347076183875

G14-225 15.23 42 14 225 9.90 -9.90 6.0 392347076183876

G14-285 15.23 42 14 285 -3.62 -13.52 6.0 392347076183877

G14-330 15.23 42 14 330 -12.12 -7.00 6.0 392347076183878

G18-180 18.97 42 18 180 18.00 0.00 6.0 392347076183800

H00-000 0.00 48 0 0 0.00 0.00 0.0 392347076183879

H07-030 7.00 48 7 30 -6.06 3.50 0.0 392347076183880

H07-090 7.00 48 7 90 0.00 7.00 0.0 392347076183881

H07-150 7.00 48 7 150 6.06 3.50 0.0 392347076183882

H07-210 7.00 48 7 210 6.06 -3.50 0.0 392347076183883

H07-270 7.00 48 7 270 0.00 -7.00 0.0 392347076183884

H07-330 7.00 48 7 330 -6.06 -3.50 0.0 392347076183885

H14-000 14.00 48 14 0 -14.00 0.00 0.0 392347076183886

H14-060 14.00 48 14 60 -7.00 12.12 0.0 392347076183887

H14-120 14.00 48 14 120 7.00 12.12 0.0 392347076183888

H14-180 14.00 48 14 180 14.00 0.00 0.0 392347076183889

H14-240 14.00 48 14 240 7.00 -12.12 0.0 392347076183890

H14-300 14.00 48 14 300 -7.00 -12.12 0.0 392347076183891

I06-285 8.49 54 6 285 -1.55 -5.80 -6.0 392347076183893

I07-112 9.22 54 7 112 2.62 6.49 -6.0 392347076183894

J06-000 13.42 60 6 0 -6.00 0.00 -12.0 392347076183895

J07-187 13.89 60 7 187 6.95 -0.85 -12.0 392347076183896

 74 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B2. Concentrations of fluorescein, bromide, and sulfur hexafluoride in ground-water samples

 collected from the tracer array at West Branch Canal Creek, Aberdeen Proving Ground,

 Maryland, July 14, 1998 through September 14, 1999

[SF6, sulfur hexafluoride; μg/L, micrograms per liter; mg/L, milligrams per liter; ng/L, nanograms per liter; mL, milliliters; NR, no replicate was

collected for this sample; --, not analyzed; <, less than; purge, analysis was performed on purge water]

Days after Bromide, Bromide,

Days after bromide ion- colori- Sulfur Water

fluorescein and SF6 Fluore- selective metric hexa- volume

Site Date injection, injection, scein electrode method fluoride removed

name Replicate sampled 07/17/1998 09/04/1998 (μg/L) (mg/L) (mg/L) (ng/L) (mL)

07/17/1998 09/04/1998

A00-300 NR 07/14/1998 -3 -52 -- -- -- -- 45.0

A00-300 NR 09/18/1998 63 14 -- -- -- -- 19.0

A00-300 NR 10/20/1998 95 46 < 5.0 2.3 -- -- 10.4

A00-300 NR 10/21/1998 96 47 -- -- -- 0.40 3.8

A00-300 NR 12/03/1998 139 90 < 5.0 3.8 -- -- 14.2

A00-300 NR 12/17/1998 153 104 < 5.0 5.8 -- 3.52 12.8

A00-300 NR 02/19/1999 217 168 -- 5.9 -- < .16 17.6

A00-300 NR 05/05/1999 292 243 < 5.0 -- 1.02 < .02 53.0

A00-300 NR 06/23/1999 341 292 < 5.0 5.4 -- 11.2 12.8

A00-300 NR 09/14/1999 424 375 13.7 7.7 -- 1.63 25.6

A06-300 NR 07/14/1998 -3 -52 -- -- -- -- 38.0

A06-300 NR 08/04/1998 18 -31 5.5 3.2 -- < .01 13.2

A06-300 NR 08/05/1998 19 -30 -- -- 0.18 -- 26.4

A06-300 NR 08/31/1998 45 -4 15.7 -- -- -- 10.5

A06-300 NR 10/01/1998 76 27 < 5.0 1.4 -- -- 7.0

A06-300 NR 11/19/1998 125 76 < 5.0 2.3 -- 26.3 17.2

A06-300 NR 12/17/1998 153 104 < 5.0 6.6 -- 4.73 11.4

A06-300 NR 02/19/1999 217 168 -- 4.8 -- < .02 24.8

A06-300 NR 05/05/1999 292 243 < 5.0 -- 0.88 < .02 44.0

A06-300 NR 09/13/1999 423 374 < 5.0 8.3 -- 1.37 24.0

A07-037 NR 07/14/1998 -3 -52 -- -- -- -- 40.0

A07-037 NR 08/31/1998 45 -4 < 5.0 -- -- -- 9.2

A07-037 NR 10/21/1998 96 47 < 5.0 2.1 -- 0.91 10.6

A07-037 NR 12/03/1998 139 90 < 5.0 2.8 -- -- 8.5

A07-037 NR 12/17/1998 153 104 < 5.0 4.3 -- 4.54 12.4

A07-037 NR 02/19/1999 217 168 -- 5.6 -- 52.6 23.0

A07-037 NR 05/05/1999 292 243 < 5.0 -- 0.97 < .02 38.8

A07-037 NR 09/13/1999 423 374 13.4 5.8 -- 2.23 20.3

A07-142 NR 07/14/1998 -3 -52 -- -- -- -- 7.0

A07-142 NR 08/20/1998 34 -15 < 5.0 -- -- -- 5.5

A07-142 NR 10/21/1998 96 47 < 5.0 2.1 -- -- 7.2

A07-142 NR 11/19/1998 125 76 < 5.0 2.7 -- 186 14.8

A07-142 NR 12/17/1998 153 104 < 5.0 8.1 -- 9.13 11.4

75 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B2. Concentrations of fluorescein, bromide, and sulfur hexafluoride in ground-water samples

 collected from the tracer array at West Branch Canal Creek, Aberdeen Proving Ground,

 Maryland, July 14, 1998 through September 14, 1999--Continued

Days after Bromide, Bromide,

Days after bromide ion- colori- Sulfur Water

fluorescein and SF6 Fluore- selective metric hexa- volume

Site Date injection, injection, scein electrode method fluoride removed

name Replicate sampled 07/17/1998 09/04/1998 (μg/L) (mg/L) (mg/L) (ng/L) (mL)

07/17/1998 09/04/1998

A07-142 NR 01/07/1999 174 125 -- -- -- -- 3.4

A07-142 NR 01/19/1999 186 137 -- 9.4 -- 10.5 12.4

A07-142 NR 02/19/1999 217 168 -- 7.1 -- 12.0 14.1

A07-142 NR 05/05/1999 292 243 < 5.0 -- 0.83 < .02 50.0

A07-142 NR 09/13/1999 423 374 13.9 -- -- 2.06 10.2

A07-247 NR 07/14/1998 -3 -52 -- -- -- -- 6.0

A07-247 NR 08/20/1998 34 -15 5.4 -- -- -- 9.0

A07-247 NR 10/01/1998 76 27 5.2 < 1.0 0.37 -- 26.9

A07-247 NR 11/05/1998 111 62 < 5.0 2.3 -- -- 9.8

A07-247 NR 12/17/1998 153 104 < 5.0 7.0 -- 2.03 15.0

A07-247 NR 02/19/1999 217 168 -- 5.4 -- < .16 16.0

A07-247 NR 05/05/1999 292 243 -- -- 0.90 < .02 24.2

A07-247 NR 09/13/1999 423 374 7.2 9.3 -- 2.13 21.6

A13-300 NR 07/14/1998 -3 -52 -- -- -- -- 6.0

A13-300 NR 08/04/1998 18 -31 -- -- 0.20 -- 19.0

A13-300 NR 08/05/1998 19 -30 -- -- -- -- 4.2

A13-300 NR 08/20/1998 34 -15 < 5.0 -- -- -- 7.6

A13-300 NR 10/01/1998 76 27 -- -- -- -- 6.3

A13-300 NR 10/21/1998 96 47 < 5.0 1.5 -- -- 7.7

A13-300 NR 12/03/1998 139 90 -- -- -- -- 3.8

A13-300 NR 12/17/1998 153 104 < 5.0 2.7 -- -- 1.6

A13-300 NR 02/19/1999 217 168 -- 6.5 -- -- 7.4

A13-300 NR 05/05/1999 292 243 -- -- 0.90 < .02 22.0

A13-300 NR 09/13/1999 423 374 5.2 9.3 -- 1.63 13.2

A14-015 NR 07/14/1998 -3 -52 -- -- -- -- 22.0

A14-015 NR 08/20/1998 34 -15 < 5.0 -- -- -- 9.0

A14-015 NR 09/18/1998 63 14 < 5.0 1.9 -- 1.11 5.6

A14-015 NR 12/03/1998 139 90 < 5.0 2.0 -- -- 8.2

A14-015 NR 12/17/1998 153 104 < 5.0 4.1 -- 5.33 10.2

A14-015 NR 02/19/1999 217 168 -- 4.6 -- 13.0 15.6

A14-015 NR 05/05/1999 292 243 < 5.0 -- 0.95 < .02 40.6

A14-015 NR 09/13/1999 423 374 7.4 10.8 -- 5.44 14.4

A14-127 NR 07/15/1998 -2 -51 -- -- -- -- 7.0

A14-127 NR 08/04/1998 18 -31 -- -- 0.34 -- 38.9

A14-127 NR 10/01/1998 76 27 < 5.0 3.1 -- -- 8.0

76 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B2. Concentrations of fluorescein, bromide, and sulfur hexafluoride in ground-water samples

 collected from the tracer array at West Branch Canal Creek, Aberdeen Proving Ground,

 Maryland, July 14, 1998 through September 14, 1999--Continued

Days after Bromide, Bromide,

Days after bromide ion- colori- Sulfur Water

fluorescein and SF6 Fluore- selective metric hexa- volume

Site Date injection, injection, scein electrode method fluoride removed

name Replicate sampled 07/17/1998 09/04/1998 (μg/L) (mg/L) (mg/L) (ng/L) (mL)

07/17/1998 09/04/1998

A14-127 NR 10/21/1998 96 47 < 5.0 2.9 -- -- 17.9

A14-127 NR 12/17/1998 153 104 < 5.0 8.6 -- 12.5 13.4

A14-127 NR 02/19/1999 217 168 -- 5.7 -- 33.4 18.6

A14-127 NR 05/05/1999 292 243 < 5.0 -- 1.02 < .02 42.2

A14-127 NR 09/13/1999 423 374 6.2 9.7 -- 2.61 25.2

A14-255 NR 07/15/1998 -2 -51 17.7 -- -- -- 11.0

A14-255 NR 09/18/1998 63 14 < 5.0 < 1.0 -- -- 7.1

A14-255 NR 11/19/1998 125 76 7.6 3.3 -- -- 6.2

A14-255 NR 12/03/1998 139 90 -- -- -- -- 2.6

A14-255 NR 12/17/1998 153 104 < 5.0 8.3 -- -- 9.7

A14-255 NR 01/19/1999 186 137 -- 7.6 -- -- 7.4

A14-255 NR 02/19/1999 217 168 -- -- -- 33.7 5.9

A14-255 NR 05/05/1999 292 243 < 5.0 -- -- < .02 17.7

A14-255 NR 09/13/1999 423 374 -- -- -- -- 2.5

B02-030 NR 07/14/1998 -3 -52 -- -- -- -- 28.0

B02-030 NR 08/20/1998 34 -15 < 5.0 -- -- -- 8.2

B02-030 NR 08/31/1998 45 -4 < 5.0 -- -- -- 17.0

B02-030 NR 10/01/1998 76 27 < 5.0 1.2 -- 2.57 11.6

B02-030 NR 11/09/1998 115 66 -- -- 0.21 2.28 27.2

B02-030 NR 12/03/1998 139 90 < 5.0 2.3 -- 9.62 12.5

B02-030 NR 12/17/1998 153 104 < 5.0 3.9 -- 1.94 11.3

B02-030 NR 01/19/1999 186 137 -- -- -- 13.6 7.7

B02-030 NR 02/19/1999 217 168 -- 7.4 -- 34.5 14.7

B02-030 NR 05/05/1999 292 243 < 5.0 -- 0.89 < .02 37.9

B02-030 NR 06/23/1999 341 292 < 5.0 5.2 -- 55.7 14.5

B02-030 NR 09/13/1999 423 374 < 5.0 9.5 -- 5.22 26.6

B02-307 NR 07/14/1998 -3 -52 -- -- -- -- 45.0

B02-307 NR 08/03/1998 17 -32 < 5.0 1.9 -- < .01 19.8

B02-307 NR 10/01/1998 76 27 < 5.0 < 1.0 -- 2.13 13.2

B02-307 NR 10/20/1998 95 46 -- -- -- -- 6.0

B02-307 1 10/21/1998 96 47 < 5.0 2.4 -- 5.60 10.7

B02-307 2 10/21/1998 96 47 -- 1.3 -- -- --

B02-307 NR 11/09/1998 115 66 -- -- -- -- 6.0

B02-307 NR 12/03/1998 139 90 < 5.0 2.8 -- 0.39 14.1

B02-307 NR 12/17/1998 153 104 < 5.0 6.1 -- 15.0 17.1

77 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B2. Concentrations of fluorescein, bromide, and sulfur hexafluoride in ground-water samples

 collected from the tracer array at West Branch Canal Creek, Aberdeen Proving Ground,

 Maryland, July 14, 1998 through September 14, 1999--Continued

Days after Bromide, Bromide,

Days after bromide ion- colori- Sulfur Water

fluorescein and SF6 Fluore- selective metric hexa- volume

Site Date injection, injection, scein electrode method fluoride removed

name Replicate sampled 07/17/1998 09/04/1998 (μg/L) (mg/L) (mg/L) (ng/L) (mL)

07/17/1998 09/04/1998

B02-307 NR 02/19/1999 217 168 -- 6.8 -- 10.2 16.4

B02-307 NR 05/05/1999 292 243 < 5.0 -- 0.82 < .02 35.7

B02-307 NR 09/13/1999 423 374 7.2 6.8 -- 2.84 26.4

B07-082 NR 07/14/1998 -3 -52 -- -- -- -- 10.0

B07-082 NR 08/20/1998 34 -15 < 5.0 -- -- -- 8.4

B07-082 NR 10/01/1998 76 27 < 5.0 1.2 -- -- 9.5

B07-082 NR 10/21/1998 96 47 < 5.0 2.2 -- 0.78 11.8

B07-082 NR 11/19/1998 125 76 < 5.0 3.4 -- 3.53 15.6

B07-082 NR 12/17/1998 153 104 < 5.0 4.2 -- 12.9 11.8

B07-082 NR 02/19/1999 217 168 -- 6.7 -- < .02 14.0

B07-082 NR 05/05/1999 292 243 < 5.0 -- 0.91 < .02 34.5

B07-082 NR 09/13/1999 423 374 < 5.0 6.4 -- 11.2 25.0

B07-202 NR 07/14/1998 -3 -52 -- -- -- -- 9.0

B07-202 NR 08/04/1998 18 -31 -- -- 0.05 -- 24.8

B07-202 NR 08/05/1998 19 -30 < 5.0 1.5 -- -- 10.0

B07-202 1 09/18/1998 63 14 < 5.0 < 1.0 0.06 2.63 42.7

B07-202 2 09/18/1998 63 14 -- -- 0.05 1.01 --

B07-202 NR 11/09/1998 115 66 -- -- 0.35 4.86 27.0

B07-202 NR 12/17/1998 153 104 < 5.0 5.6 -- 7.29 14.0

B07-202 NR 02/19/1999 217 168 -- 7.8 -- 24.5 15.4

B07-202 NR 05/05/1999 292 243 < 5.0 -- 0.70 < .02 49.0

B07-202 NR 09/13/1999 423 374 6.3 7.6 -- 3.86 25.8

B07-292 NR 07/14/1998 -3 -52 -- -- -- -- 7.0

B07-292 NR 08/20/1998 34 -15 < 5.0 -- -- -- 2.0

B07-292 NR 10/01/1998 76 27 -- -- -- -- 0.6

B07-292 NR 10/21/1998 96 47 < 5.0 < 1.0 -- -- 3.2

B07-292 NR 11/19/1998 125 76 < 5.0 2.1 -- 0.87 13.4

B07-292 NR 12/03/1998 139 90 < 5.0 2.6 -- -- 8.4

B07-292 NR 12/17/1998 153 104 < 5.0 5.0 -- 1.89 9.8

B07-292 NR 01/19/1999 186 137 -- 8.6 -- 8.29 11.8

B07-292 NR 02/19/1999 217 168 -- 7.4 -- < .16 12.3

B07-292 NR 05/05/1999 292 243 < 5.0 -- 0.75 < .06 31.2

B07-292 NR 09/13/1999 423 374 < 5.0 8.9 -- 4.16 25.6

B07-352 NR 07/14/1998 -3 -52 -- -- -- -- 8.0

B07-352 1 09/18/1998 63 14 < 5.0 1.1 0.13 3.73 33.0

78 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B2. Concentrations of fluorescein, bromide, and sulfur hexafluoride in ground-water samples

 collected from the tracer array at West Branch Canal Creek, Aberdeen Proving Ground,

 Maryland, July 14, 1998 through September 14, 1999--Continued

Days after Bromide, Bromide,

Days after bromide ion- colori- Sulfur Water

fluorescein and SF6 Fluore- selective metric hexa- volume

Site Date injection, injection, scein electrode method fluoride removed

name Replicate sampled 07/17/1998 09/04/1998 (μg/L) (mg/L) (mg/L) (ng/L) (mL)

07/17/1998 09/04/1998

B07-352 2 09/18/1998 63 14 < 5.0 1.3 -- -- --

B07-352 NR 11/05/1998 111 62 < 5.0 1.5 -- -- 10.4

B07-352 NR 12/17/1998 153 104 < 5.0 2.2 -- 3.83 12.6

B07-352 NR 02/19/1999 217 168 -- 6.6 -- 10.1 14.4

B07-352 NR 05/05/1999 292 243 < 5.0 -- 0.88 < .02 44.5

B07-352 NR 09/13/1999 423 374 < 5.0 5.0 -- 4.92 17.0

B14-037 NR 07/14/1998 -3 -52 < 5.0 -- -- -- 25.0

B14-037 NR 08/04/1998 18 -31 -- -- 0.27 -- 26.1

B14-037 NR 08/05/1998 19 -30 -- -- -- -- 9.6

B14-037 NR 11/05/1998 111 62 < 5.0 2.0 -- -- 9.6

B14-037 NR 12/17/1998 153 104 < 5.0 4.7 -- 9.51 12.2

B14-037 NR 02/19/1999 217 168 -- 6.6 -- 24.6 15.8

B14-037 NR 05/05/1999 292 243 < 5.0 -- 0.64 24.7 37.1

B14-037 NR 09/13/1999 423 374 < 5.0 5.3 -- 9.44 24.6

B14-187 NR 07/15/1998 -2 -51 -- -- -- -- 6.0

B14-187 NR 08/20/1998 34 -15 < 5.0 -- -- -- 10.2

B14-187 NR 10/20/1998 95 46 < 5.0 1.2 -- -- 11.2

B14-187 NR 11/19/1998 125 76 < 5.0 2.2 -- 3.10 13.5

B14-187 NR 12/17/1998 153 104 < 5.0 4.6 -- 10.0 12.9

B14-187 NR 01/19/1999 186 137 -- 7.7 -- -- 8.8

B14-187 NR 02/19/1999 217 168 -- 8.0 -- < .16 22.8

B14-187 NR 05/06/1999 293 244 < 5.0 -- 1.80 < .03 34.8

B14-187 NR 09/13/1999 423 374 < 5.0 9.4 -- 4.80 14.6

B14-337 NR 07/15/1998 -2 -51 -- -- -- -- 22.0

B14-337 NR 10/01/1998 76 27 < 5.0 1.7 -- -- 10.9

B14-337 NR 10/21/1998 96 47 < 5.0 2.6 -- -- 44.1

B14-337 NR 12/03/1998 139 90 < 5.0 3.0 -- -- 13.6

B14-337 NR 12/17/1998 153 104 < 5.0 5.4 -- 2.09 18.4

B14-337 NR 02/19/1999 217 168 -- 5.1 -- 9.05 27.0

B14-337 NR 05/06/1999 293 244 < 5.0 -- 0.85 < .04 38.6

B14-337 NR 09/13/1999 423 374 < 5.0 8.4 -- 13.1 38.6

C00-000 NR 07/14/1998 -3 -52 -- -- -- -- 30.0

C00-000 NR 08/03/1998 17 -32 < 5.0 1.2 -- < .01 19.1

C00-000 NR 08/20/1998 34 -15 < 5.0 -- -- -- 17.1

C00-000 NR 09/18/1998 63 14 -- -- 0.12 -- 25.0

79 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B2. Concentrations of fluorescein, bromide, and sulfur hexafluoride in ground-water samples

 collected from the tracer array at West Branch Canal Creek, Aberdeen Proving Ground,

 Maryland, July 14, 1998 through September 14, 1999--Continued

Days after Bromide, Bromide,

Days after bromide ion- colori- Sulfur Water

fluorescein and SF6 Fluore- selective metric hexa- volume

Site Date injection, injection, scein electrode method fluoride removed

name Replicate sampled 07/17/1998 09/04/1998 (μg/L) (mg/L) (mg/L) (ng/L) (mL)

07/17/1998 09/04/1998

C00-000 NR 10/01/1998 76 27 -- -- -- 13.8 11.2

C00-000 NR 11/05/1998 111 62 -- -- 6.01 73.2 30.2

C00-000 NR 12/03/1998 139 90 -- -- 2.13 49.7 22.4

C00-000 NR 12/17/1998 153 104 < 5.0 4.1 -- 38.8 16.4

C00-000 NR 02/19/1999 217 168 -- 6.2 -- < .33 20.0

C00-000 NR 05/06/1999 293 244 < 5.0 -- 1.80 < .05 39.6

C00-000 NR 06/23/1999 341 292 < 5.0 4.2 -- 62.8 17.6

C00-000 1 09/13/1999 423 374 < 5.0 5.3 -- 39.5 17.1

C00-000 2 09/13/1999 423 374 < 5.0 3.9 -- -- --

C07-007 NR 07/14/1998 -3 -52 -- -- -- -- 108.0

C07-007 NR 09/18/1998 63 14 -- -- -- -- 16.6

C07-007 NR 11/05/1998 111 62 < 5.0 17.1 -- -- 17.2

C07-007 1 12/03/1998 139 90 < 5.0 14.8 12.12 167 37.0

C07-007 2 12/03/1998 139 90 -- 14.9 -- -- --

C07-007 NR 12/17/1998 153 104 < 5.0 12.4 -- 10.5 19.8

C07-007 NR 02/19/1999 217 168 -- 6.6 -- 201 29.8

C07-007 NR 05/06/1999 293 244 < 5.0 -- 1.13 135 77.4

C07-007 NR 09/13/1999 423 374 < 5.0 4.4 -- 124 36.6

C07-067 NR 07/14/1998 -3 -52 -- -- -- -- 87.0

C07-067 NR 08/20/1998 34 -15 < 5.0 -- -- -- 21.8

C07-067 NR 10/21/1998 96 47 < 5.0 13.2 -- 28.6 17.6

C07-067 NR 11/19/1998 125 76 < 5.0 47.7 -- 51.9 19.0

C07-067 NR 12/17/1998 153 104 < 5.0 18.0 -- 150 18.6

C07-067 NR 02/19/1999 217 168 -- 7.4 -- 613 18.6

C07-067 NR 05/06/1999 293 244 < 5.0 -- 1.57 760 48.4

C07-067 NR 09/13/1999 423 374 7.4 4.1 -- 573 38.7

C07-127 NR 07/14/1998 -3 -52 -- -- -- -- 11.0

C07-127 NR 08/31/1998 45 -4 6.7 -- -- -- 14.4

C07-127 NR 10/01/1998 76 27 -- -- -- -- 3.6

C07-127 NR 11/05/1998 111 62 < 5.0 3.9 -- -- 13.3

C07-127 NR 12/03/1998 139 90 < 5.0 3.0 2.28 5.07 27.8

C07-127 NR 12/17/1998 153 104 < 5.0 2.8 -- 58.6 17.2

C07-127 1 01/19/1999 186 137 -- 5.5 -- 40.5 23.2

C07-127 2 01/19/1999 186 137 -- 5.3 -- 34.2 --

C07-127 NR 02/19/1999 217 168 -- 6.4 -- 96.2 26.9

80 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B2. Concentrations of fluorescein, bromide, and sulfur hexafluoride in ground-water samples

 collected from the tracer array at West Branch Canal Creek, Aberdeen Proving Ground,

 Maryland, July 14, 1998 through September 14, 1999--Continued

Days after Bromide, Bromide,

Days after bromide ion- colori- Sulfur Water

fluorescein and SF6 Fluore- selective metric hexa- volume

Site Date injection, injection, scein electrode method fluoride removed

name Replicate sampled 07/17/1998 09/04/1998 (μg/L) (mg/L) (mg/L) (ng/L) (mL)

07/17/1998 09/04/1998

C07-127 NR 05/06/1999 293 244 < 5.0 -- 1.08 101 56.2

C07-127 NR 09/13/1999 423 374 < 5.0 4.4 -- 95.7 24.8

C07-217 NR 07/14/1998 -3 -52 -- -- -- -- 15.0

C07-217 NR 10/01/1998 76 27 < 5.0 < 1.0 -- 26.0 17.6

C07-217 NR 10/20/1998 95 46 < 5.0 1.3 -- 8.56 13.8

C07-217 NR 11/19/1998 125 76 -- -- 0.50 45.6 22.3

C07-217 NR 12/17/1998 153 104 < 5.0 4.3 -- 9.50 17.3

C07-217 purge 01/19/1999 186 137 -- 4.2 -- -- 6.0

C07-217 NR 01/19/1999 186 137 -- 7.5 -- 11.1 8.6

C07-217 NR 02/19/1999 217 168 -- 6.1 -- < .02 19.2

C07-217 1 05/06/1999 293 244 < 5.0 -- 0.62 < .02 42.8

C07-217 2 05/06/1999 293 244 < 5.0 -- -- -- --

C07-217 NR 09/13/1999 423 374 < 5.0 5.3 -- 6.67 31.6

C07-262 NR 07/14/1998 -3 -52 -- -- -- -- 67.0

C07-262 NR 08/20/1998 34 -15 < 5.0 -- -- -- 15.5

C07-262 NR 11/05/1998 111 62 < 5.0 < 2.0 -- -- 13.4

C07-262 NR 12/02/1998 138 89 -- -- 0.76 4.14 21.5

C07-262 NR 12/17/1998 153 104 < 5.0 3.6 -- 66.5 16.7

C07-262 NR 02/19/1999 217 168 -- 5.1 -- < .32 18.7

C07-262 NR 05/06/1999 293 244 < 5.0 -- 0.61 21.0 40.6

C07-262 1 09/13/1999 423 374 < 5.0 4.6 -- 2.10 23.8

C07-262 2 09/13/1999 423 374 < 5.0 4.0 -- -- --

C07-322 NR 07/14/1998 -3 -52 -- -- -- -- 9.0

C07-322 NR 10/01/1998 76 27 < 5.0 1.1 0.24 -- 28.4

C07-322 NR 10/20/1998 95 46 < 5.0 1.3 -- -- 8.2

C07-322 1 11/19/1998 125 76 -- -- 1.27 14.1 32.8

C07-322 2 11/19/1998 125 76 -- -- 1.65 -- --

C07-322 NR 12/02/1998 138 89 < 5.0 3.3 1.29 -- 21.6

C07-322 NR 12/17/1998 153 104 < 5.0 4.1 -- 5.43 12.0

C07-322 NR 02/19/1999 217 168 -- 6.2 -- < .34 13.7

C07-322 1 05/06/1999 293 244 < 5.0 -- 0.73 < .02 36.5

C07-322 2 05/06/1999 293 244 -- -- -- 5.63 --

C07-322 NR 09/13/1999 423 374 < 5.0 7.0 -- 7.37 27.9

C14-030 NR 07/14/1998 -3 -52 -- -- -- -- 19.0

C14-030 NR 10/01/1998 76 27 < 5.0 1.4 -- -- 10.6

81 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B2. Concentrations of fluorescein, bromide, and sulfur hexafluoride in ground-water samples

 collected from the tracer array at West Branch Canal Creek, Aberdeen Proving Ground,

 Maryland, July 14, 1998 through September 14, 1999--Continued

Days after Bromide, Bromide,

Days after bromide ion- colori- Sulfur Water

fluorescein and SF6 Fluore- selective metric hexa- volume

Site Date injection, injection, scein electrode method fluoride removed

name Replicate sampled 07/17/1998 09/04/1998 (μg/L) (mg/L) (mg/L) (ng/L) (mL)

07/17/1998 09/04/1998

C14-030 NR 11/19/1998 125 76 < 5.0 9.9 -- -- 13.9

C14-030 NR 12/17/1998 153 104 < 5.0 8.0 -- 27.3 16.6

C14-030 NR 01/19/1999 186 137 -- 9.1 6.38 82.8 25.9

C14-030 NR 02/19/1999 217 168 -- 6.8 -- 22.4 13.0

C14-030 NR 05/06/1999 293 244 < 5.0 -- 1.11 19.0 37.7

C14-030 NR 09/13/1999 423 374 < 5.0 5.4 -- 18.2 39.9

C14-172 NR 07/15/1998 -2 -51 -- -- -- -- 9.0

C14-172 NR 08/05/1998 19 -30 -- -- 0.03 -- 23.2

C14-172 NR 08/20/1998 34 -15 < 5.0 -- -- -- 13.8

C14-172 NR 09/18/1998 63 14 < 5.0 < 1.0 -- 2.31 13.2

C14-172 NR 10/21/1998 96 47 -- 1.3 -- -- 26.6

C14-172 NR 11/05/1998 111 62 < 5.0 1.0 -- -- 7.8

C14-172 NR 12/17/1998 153 104 < 5.0 3.3 -- 30.0 11.8

C14-172 NR 02/19/1999 217 168 -- 5.8 -- -- 6.0

C14-172 NR 05/06/1999 293 244 -- -- 0.72 < .02 23.1

C14-172 NR 09/13/1999 423 374 < 5.0 3.5 -- 4.10 10.4

C14-270 NR 07/15/1998 -2 -51 -- -- -- -- 10.0

C14-270 NR 09/18/1998 63 14 < 5.0 < 1.0 -- 7.83 16.8

C14-270 NR 11/05/1998 111 62 < 5.0 < 1.0 0.08 -- 60.7

C14-270 NR 12/02/1998 138 89 < 5.0 1.1 -- -- 8.4

C14-270 NR 12/17/1998 153 104 < 5.0 2.7 -- 21.9 18.9

C14-270 NR 02/19/1999 217 168 -- 4.6 -- < .02 17.8

C14-270 NR 05/06/1999 293 244 < 5.0 -- 0.69 < .02 42.5

C14-270 1 09/13/1999 423 374 < 5.0 4.5 -- 4.75 38.3

C14-270 2 09/13/1999 423 374 < 5.0 4.9 -- -- --

C14-322 NR 07/14/1998 -3 -52 10.6 -- -- -- 20.0

C14-322 NR 08/04/1998 18 -31 -- -- 0.06 -- 33.0

C14-322 NR 08/05/1998 19 -30 -- -- -- -- 12.8

C14-322 NR 08/20/1998 34 -15 < 5.0 -- -- -- 16.8

C14-322 NR 10/01/1998 76 27 < 5.0 < 1.0 -- -- 12.0

C14-322 NR 10/20/1998 95 46 < 5.0 1.1 -- -- 26.8

C14-322 NR 11/02/1998 108 59 -- -- -- -- 33.6

C14-322 NR 12/17/1998 153 104 < 5.0 3.9 -- 2.10 14.9

C14-322 NR 02/19/1999 217 168 -- 5.1 -- 9.91 14.6

C14-322 NR 05/06/1999 293 244 < 5.0 -- 0.89 < .02 35.5

82 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B2. Concentrations of fluorescein, bromide, and sulfur hexafluoride in ground-water samples

 collected from the tracer array at West Branch Canal Creek, Aberdeen Proving Ground,

 Maryland, July 14, 1998 through September 14, 1999--Continued

Days after Bromide, Bromide,

Days after bromide ion- colori- Sulfur Water

fluorescein and SF6 Fluore- selective metric hexa- volume

Site Date injection, injection, scein electrode method fluoride removed

name Replicate sampled 07/17/1998 09/04/1998 (μg/L) (mg/L) (mg/L) (ng/L) (mL)

07/17/1998 09/04/1998

C14-322 1 09/13/1999 423 374 < 5.0 5.2 -- 7.67 31.4

C14-322 2 09/13/1999 423 374 < 5.0 4.9 -- 7.48 --

D02-105 NR 07/14/1998 -3 -52 -- -- -- -- 45.0

D02-105 NR 08/05/1998 19 -30 14.2 1.4 -- -- 6.4

D02-105 NR 08/20/1998 34 -15 < 5.0 -- -- -- 17.4

D02-105 NR 10/01/1998 76 27 < 5.0 4.9 -- 474 15.1

D02-105 NR 10/20/1998 95 46 -- -- 23.3 54.4 28.6

D02-105 NR 12/02/1998 138 89 -- -- 24.1 136 24.8

D02-105 NR 12/17/1998 153 104 < 5.0 19.5 -- -- 18.1

D02-105 NR 02/19/1999 217 168 -- 10.3 -- 409 15.2

D02-105 NR 05/06/1999 293 244 < 5.0 -- 1.82 175 35.5

D02-105 NR 09/10/1999 420 371 < 5.0 3.2 -- 476 33.7

D07-022 NR 07/14/1998 -3 -52 -- -- -- -- 9.0

D07-022 NR 08/04/1998 18 -31 -- -- -- -- 15.8

D07-022 NR 08/05/1998 19 -30 -- -- 0.04 -- 31.1

D07-022 NR 08/20/1998 34 -15 < 5.0 -- -- -- 20.7

D07-022 1 10/20/1998 95 46 -- -- 38.3 67.5 40.9

D07-022 2 10/20/1998 95 46 -- -- -- 53.0 --

D07-022 NR 11/19/1998 125 76 -- -- 92.7 60.3 22.3

D07-022 NR 12/17/1998 153 104 < 5.0 119 -- 364 17.0

D07-022 NR 02/19/1999 217 168 -- 28.9 -- 2,970 14.4

D07-022 1 05/06/1999 293 244 7.5 -- 4.18 1,430 58.8

D07-022 2 05/06/1999 293 244 -- -- 3.83 1,387 --

D07-022 1 06/23/1999 341 292 < 5.0 4.2 -- 458 15.9

D07-022 2 06/23/1999 341 292 -- -- -- 424 --

D07-022 NR 09/10/1999 420 371 8.4 3.0 -- 246 26.8

D07-105 NR 07/14/1998 -3 -52 6.4 -- -- -- 18.0

D07-105 NR 09/18/1998 63 14 < 5.0 < 1.0 1.19 8.52 31.8

D07-105 NR 10/01/1998 76 27 < 5.0 3.3 -- 6.72 18.0

D07-105 NR 11/05/1998 111 62 -- -- 46.9 31.1 22.0

D07-105 NR 12/02/1998 138 89 < 5.0 55.5 -- 876 16.6

D07-105 NR 12/17/1998 153 104 < 5.0 33.2 -- 660 15.3

D07-105 NR 02/19/1999 217 168 -- 13.3 -- 1,350 26.6

D07-105 NR 05/06/1999 293 244 10.5 -- 3.69 794 32.8

D07-105 NR 09/10/1999 420 371 12.3 3.6 -- 487 23.2

83 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B2. Concentrations of fluorescein, bromide, and sulfur hexafluoride in ground-water samples

 collected from the tracer array at West Branch Canal Creek, Aberdeen Proving Ground,

 Maryland, July 14, 1998 through September 14, 1999--Continued

Days after Bromide, Bromide,

Days after bromide ion- colori- Sulfur Water

fluorescein and SF6 Fluore- selective metric hexa- volume

Site Date injection, injection, scein electrode method fluoride removed

name Replicate sampled 07/17/1998 09/04/1998 (μg/L) (mg/L) (mg/L) (ng/L) (mL)

07/17/1998 09/04/1998

D07-165 NR 07/14/1998 -3 -52 -- -- -- -- 19.0

D07-165 NR 08/20/1998 34 -15 < 5.0 -- -- -- 18.2

D07-165 1 10/01/1998 76 27 < 5.0 1.3 2.18 432 44.1

D07-165 2 10/01/1998 76 27 < 5.0 1.4 -- 378 --

D07-165 1 10/20/1998 95 46 < 5.0 5.2 -- -- 20.0

D07-165 2 10/20/1998 95 46 < 5.0 5.4 -- -- --

D07-165 NR 11/19/1998 125 76 < 5.0 3.4 -- -- 15.6

D07-165 NR 12/17/1998 153 104 < 5.0 6.6 -- 606 16.4

D07-165 NR 02/19/1999 217 168 -- 6.1 -- 151 23.8

D07-165 1 05/06/1999 293 244 < 5.0 -- 0.63 82.1 81.8

D07-165 2 05/06/1999 293 244 -- -- 0.65 -- --

D07-165 NR 09/09/1999 419 370 -- -- -- -- 11.6

D07-277 NR 07/14/1998 -3 -52 -- -- -- -- 9.0

D07-277 NR 08/04/1998 18 -31 -- -- <0.02 -- 39.0

D07-277 1 08/20/1998 34 -15 < 5.0 -- -- -- 26.0

D07-277 2 08/20/1998 34 -15 < 5.0 -- -- -- --

D07-277 NR 10/20/1998 95 46 -- -- 5.09 16.3 25.9

D07-277 NR 12/02/1998 138 89 -- -- 10.8 9.60 20.3

D07-277 NR 12/17/1998 153 104 < 5.0 8.1 -- -- 15.1

D07-277 NR 02/19/1999 217 168 -- 7.2 -- -- 15.6

D07-277 NR 02/25/1999 223 174 -- -- -- 100 2.6

D07-277 NR 05/06/1999 293 244 -- -- 1.21 10.4 28.0

D07-277 NR 09/10/1999 420 371 9.8 -- -- 26.1 18.0

D07-337 NR 07/14/1998 -3 -52 -- -- -- -- 12.0

D07-337 NR 08/31/1998 45 -4 5.3 -- -- -- 16.2

D07-337 NR 10/01/1998 76 27 < 5.0 14.3 -- -- 8.9

D07-337 NR 11/05/1998 111 62 -- -- 49.1 -- 15.4

D07-337 NR 11/19/1998 125 76 < 5.0 50.5 -- -- 8.8

D07-337 NR 12/17/1998 153 104 < 5.0 27.7 -- 303 11.4

D07-337 NR 01/19/1999 186 137 -- 17.0 12.7 145 29.1

D07-337 NR 02/19/1999 217 168 -- 9.9 -- 225 10.2

D07-337 NR 05/07/1999 294 245 < 5.0 -- 1.16 65.5 36.8

D07-337 NR 06/23/1999 341 292 < 5.0 4.8 -- 2.75 10.2

D07-337 NR 09/10/1999 420 371 < 5.0 2.9 -- 32.0 26.6

D14-052 NR 07/14/1998 -3 -52 -- -- -- -- 11.0

84 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B2. Concentrations of fluorescein, bromide, and sulfur hexafluoride in ground-water samples

 collected from the tracer array at West Branch Canal Creek, Aberdeen Proving Ground,

 Maryland, July 14, 1998 through September 14, 1999--Continued

Days after Bromide, Bromide,

Days after bromide ion- colori- Sulfur Water

fluorescein and SF6 Fluore- selective metric hexa- volume

Site Date injection, injection, scein electrode method fluoride removed

name Replicate sampled 07/17/1998 09/04/1998 (μg/L) (mg/L) (mg/L) (ng/L) (mL)

07/17/1998 09/04/1998

D14-052 NR 08/20/1998 34 -15 < 5.0 -- -- -- 12.1

D14-052 NR 10/01/1998 76 27 < 5.0 < 1.0 -- -- 12.9

D14-052 NR 10/21/1998 96 47 < 5.0 2.6 -- -- 20.0

D14-052 NR 11/19/1998 125 76 < 5.0 25.2 -- 69.0 11.8

D14-052 NR 12/17/1998 153 104 < 5.0 58.8 -- 80.5 12.8

D14-052 NR 01/19/1999 186 137 -- 37.9 -- 2,080 11.6

D14-052 NR 02/19/1999 217 168 -- 22.0 -- 632 13.5

D14-052 NR 05/07/1999 294 245 < 5.0 8.3 7.11 966 33.6

D14-052 1 06/23/1999 341 292 < 5.0 11.1 -- 29.8 20.7

D14-052 2 06/23/1999 341 292 < 5.0 8.9 -- -- --

D14-052 NR 09/10/1999 420 371 < 5.0 4.1 -- 255 22.6

D14-247 NR 07/15/1998 -2 -51 -- -- -- -- 12.0

D14-247 NR 08/20/1998 34 -15 -- -- -- -- 3.8

D14-247 NR 08/31/1998 45 -4 -- -- -- -- 3.0

D14-247 NR 09/18/1998 63 14 < 5.0 < 1.0 0.15 1.28 26.8

D14-247 NR 10/20/1998 95 46 < 5.0 1.3 -- 1.69 16.7

D14-247 NR 12/02/1998 138 89 -- -- -- 9.03 8.6

D14-247 NR 12/17/1998 153 104 < 5.0 1.1 -- -- 13.2

D14-247 NR 02/19/1999 217 168 -- 4.1 -- < .02 11.4

D14-247 NR 05/07/1999 294 245 < 5.0 -- 0.80 < .02 30.7

D14-247 NR 09/10/1999 420 371 < 5.0 3.0 -- 21.5 20.6

D14-307 NR 07/15/1998 -2 -51 -- -- -- -- 10.0

D14-307 NR 10/01/1998 76 27 < 5.0 < 1.0 -- -- 9.7

D14-307 NR 10/21/1998 96 47 < 5.0 1.1 -- -- 31.4

D14-307 NR 11/19/1998 125 76 < 5.0 1.6 -- 3.67 12.3

D14-307 NR 12/17/1998 153 104 < 5.0 1.7 -- 1.82 16.4

D14-307 NR 01/19/1999 186 137 -- 4.7 -- 20.0 14.8

D14-307 NR 02/19/1999 217 168 -- 4.9 -- 58.5 17.4

D14-307 1 05/07/1999 294 245 < 5.0 -- 1.03 10.7 51.6

D14-307 2 05/07/1999 294 245 -- -- 1.01 -- --

D14-307 NR 06/23/1999 341 292 < 5.0 5.5 -- 16.3 15.6

D14-307 NR 09/10/1999 420 371 < 5.0 2.2 -- 66.4 34.4

D14-352 NR 07/15/1998 -2 -51 -- -- -- -- 19.0

D14-352 NR 09/18/1998 63 14 < 5.0 1.4 -- 8.14 16.5

D14-352 NR 11/05/1998 111 62 < 5.0 1.4 -- -- 19.4

85 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B2. Concentrations of fluorescein, bromide, and sulfur hexafluoride in ground-water samples

 collected from the tracer array at West Branch Canal Creek, Aberdeen Proving Ground,

 Maryland, July 14, 1998 through September 14, 1999--Continued

Days after Bromide, Bromide,

Days after bromide ion- colori- Sulfur Water

fluorescein and SF6 Fluore- selective metric hexa- volume

Site Date injection, injection, scein electrode method fluoride removed

name Replicate sampled 07/17/1998 09/04/1998 (μg/L) (mg/L) (mg/L) (ng/L) (mL)

07/17/1998 09/04/1998

D14-352 NR 12/02/1998 138 89 -- -- 1.04 1.00 23.6

D14-352 NR 12/17/1998 153 104 < 5.0 3.3 -- 13.8 15.6

D14-352 NR 02/19/1999 217 168 -- 5.5 -- 9.83 19.0

D14-352 1 05/07/1999 294 245 < 5.0 -- 1.14 19.3 67.2

D14-352 2 05/07/1999 294 245 -- -- 1.16 -- --

D14-352 1 06/23/1999 341 292 < 5.0 6.9 -- 23.2 25.6

D14-352 2 06/23/1999 341 292 < 5.0 7.4 -- 22.7 --

D14-352 NR 09/10/1999 420 371 < 5.0 11.9 -- 36.8 56.9

D24-045 NR 09/02/1999 412 363 -- -- -- -- 17.0

D24-045 NR 09/03/1999 413 364 < 5.0 < 1.0 -- 9.25 19.2

D24-045 1 09/10/1999 420 371 < 5.0 2.3 -- 64.5 41.2

D24-045 2 09/10/1999 420 371 < 5.0 2.5 -- -- --

E02-285 NR 07/14/1998 -3 -52 -- -- -- -- 21.0

E02-285 NR 08/03/1998 17 -32 < 5.0 1.4 -- 0.03 22.7

E02-285 1 08/11/1998 25 -24 < 5.0 1.6 -- -- 24.7

E02-285 2 08/11/1998 25 -24 < 5.0 1.3 -- -- --

E02-285 NR 08/31/1998 45 -4 < 5.0 -- -- -- 24.7

E02-285 NR 09/18/1998 63 14 -- -- 7.62 -- 21.0

E02-285 NR 10/01/1998 76 27 -- -- -- 828 9.0

E02-285 NR 10/20/1998 95 46 < 5.0 38.6 -- 72.4 14.7

E02-285 1 11/19/1998 125 76 < 5.0 106 -- 1,490 13.0

E02-285 2 11/19/1998 125 76 -- -- -- 1,140 --

E02-285 NR 12/17/1998 153 104 < 5.0 88.9 -- 2,960 19.3

E02-285 NR 02/24/1999 222 173 -- 26.2 -- 1,900 19.3

E02-285 NR 05/07/1999 294 245 < 5.0 -- 1.65 426 36.1

E02-285 NR 09/09/1999 419 370 < 5.0 1.3 -- 467 27.9

E07-000 NR 07/14/1998 -3 -52 -- -- -- -- 15.0

E07-000 NR 09/18/1998 63 14 < 5.0 < 1.0 -- 4.26 24.0

E07-000 NR 11/05/1998 111 62 < 5.0 13.2 -- -- 17.7

E07-000 NR 12/02/1998 138 89 -- -- 23.9 46.3 17.9

E07-000 NR 12/17/1998 153 104 < 5.0 35.0 -- 57.7 12.3

E07-000 NR 02/24/1999 222 173 -- 10.8 -- 411 12.4

E07-000 NR 05/07/1999 294 245 < 5.0 2.4 1.61 116 31.8

E07-000 NR 06/23/1999 341 292 < 5.0 -- -- 165 14.6

E07-000 1 09/10/1999 420 371 < 5.0 1.7 -- 79.4 33.2

86 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B2. Concentrations of fluorescein, bromide, and sulfur hexafluoride in ground-water samples

 collected from the tracer array at West Branch Canal Creek, Aberdeen Proving Ground,

 Maryland, July 14, 1998 through September 14, 1999--Continued

Days after Bromide, Bromide,

Days after bromide ion- colori- Sulfur Water

fluorescein and SF6 Fluore- selective metric hexa- volume

Site Date injection, injection, scein electrode method fluoride removed

name Replicate sampled 07/17/1998 09/04/1998 (μg/L) (mg/L) (mg/L) (ng/L) (mL)

07/17/1998 09/04/1998

E07-000 2 09/10/1999 420 371 < 5.0 1.6 -- -- --

E07-045 NR 07/14/1998 -3 -52 -- -- -- -- 15.0

E07-045 NR 07/15/1998 -2 -51 < 5.0 -- -- -- 10.0

E07-045 NR 10/01/1998 76 27 < 5.0 1.1 -- -- 13.0

E07-045 NR 11/05/1998 111 62 -- -- 56.5 12.9 17.6

E07-045 NR 12/17/1998 153 104 < 5.0 112 -- 625 11.6

E07-045 1 01/07/1999 174 125 -- 97.1 -- 3,400 21.2

E07-045 2 01/07/1999 174 125 -- 96.3 -- 2,480 --

E07-045 NR 02/25/1999 223 174 -- 51.8 -- 5,610 20.0

E07-045 NR 05/10/1999 297 248 < 5.0 9.9 10.5 22.4 44.0

E07-045 NR 06/23/1999 341 292 < 5.0 8.9 -- -- 6.8

E07-045 NR 09/09/1999 419 370 14.3 3.3 -- 681 16.0

E07-120 NR 07/14/1998 -3 -52 -- -- -- -- 23.0

E07-120 NR 08/20/1998 34 -15 < 5.0 -- -- -- 23.1

E07-120 NR 09/18/1998 63 14 < 5.0 < 1.0 -- 16.6 14.9

E07-120 NR 10/20/1998 95 46 -- -- 22.4 63.6 30.4

E07-120 NR 11/19/1998 125 76 < 5.0 53.9 -- 255 19.2

E07-120 NR 12/17/1998 153 104 < 5.0 68.1 -- 647 20.2

E07-120 NR 02/24/1999 222 173 -- 21.3 -- 115 15.8

E07-120 1 05/10/1999 297 248 < 5.0 6.4 6.64 1,230 71.0

E07-120 2 05/10/1999 297 248 -- -- 5.70 1,060 --

E07-120 NR 09/09/1999 419 370 < 5.0 1.7 -- 2,250 34.0

E07-180 NR 07/14/1998 -3 -52 -- -- -- -- 16.0

E07-180 NR 08/31/1998 45 -4 5.2 -- -- -- 24.5

E07-180 NR 10/01/1998 76 27 < 5.0 1.0 0.87 16.5 33.4

E07-180 NR 10/21/1998 96 47 < 5.0 1.4 -- 79.5 15.2

E07-180 NR 12/02/1998 138 89 < 5.0 7.4 7.86 7.05 29.5

E07-180 NR 12/17/1998 153 104 < 5.0 8.8 -- 364 14.4

E07-180 NR 02/24/1999 222 173 -- 4.1 -- 293 21.8

E07-180 1 05/10/1999 297 248 < 5.0 -- 0.96 43.9 36.5

E07-180 2 05/10/1999 297 248 -- -- -- 43.6 --

E07-180 NR 09/09/1999 419 370 < 5.0 1.2 -- 59.3 37.2

E07-240 NR 07/14/1998 -3 -52 -- -- -- -- 14.0

E07-240 NR 09/18/1998 63 14 < 5.0 1.4 -- 13.2 13.6

E07-240 1 11/19/1998 125 76 -- -- 26.2 799 38.0

87 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B2. Concentrations of fluorescein, bromide, and sulfur hexafluoride in ground-water samples

 collected from the tracer array at West Branch Canal Creek, Aberdeen Proving Ground,

 Maryland, July 14, 1998 through September 14, 1999--Continued

Days after Bromide, Bromide,

Days after bromide ion- colori- Sulfur Water

fluorescein and SF6 Fluore- selective metric hexa- volume

Site Date injection, injection, scein electrode method fluoride removed

name Replicate sampled 07/17/1998 09/04/1998 (μg/L) (mg/L) (mg/L) (ng/L) (mL)

07/17/1998 09/04/1998

E07-240 2 11/19/1998 125 76 -- -- -- 704 --

E07-240 NR 12/17/1998 153 104 < 5.0 22.9 -- 771 11.0

E07-240 NR 01/07/1999 174 125 -- 14.8 18.5 1,030 27.1

E07-240 NR 02/24/1999 222 173 -- 6.6 -- 209 12.2

E07-240 NR 05/10/1999 297 248 < 5.0 -- 1.02 < .02 29.4

E07-240 NR 09/09/1999 419 370 < 5.0 1.3 -- 68.8 23.4

E07-307 NR 07/14/1998 -3 -52 -- -- -- -- 18.0

E07-307 NR 08/20/1998 34 -15 < 5.0 -- -- -- 19.4

E07-307 NR 10/01/1998 76 27 < 5.0 3.5 -- 3.89 18.7

E07-307 NR 11/05/1998 111 62 -- -- 24.2 38.9 29.9

E07-307 1 12/02/1998 138 89 -- -- 30.2 92.9 24.2

E07-307 2 12/02/1998 138 89 -- -- -- 115 --

E07-307 NR 12/17/1998 153 104 < 5.0 25.4 -- 176 13.0

E07-307 NR 02/24/1999 222 173 -- 5.7 -- 288 16.2

E07-307 NR 05/10/1999 297 248 < 5.0 -- 0.80 13.6 43.2

E07-307 1 06/23/1999 341 292 < 5.0 4.7 -- 28.9 26.2

E07-307 2 06/23/1999 341 292 < 5.0 4.6 -- 25.8 --

E07-307 NR 09/09/1999 419 370 < 5.0 < 1.0 -- 74.0 33.8

E14-007 NR 07/14/1998 -3 -52 -- -- -- -- 16.0

E14-007 NR 08/20/1998 34 -15 < 5.0 < 1.0 -- -- 12.0

E14-007 NR 10/20/1998 95 46 < 5.0 < 1.0 -- -- 15.7

E14-007 NR 12/17/1998 153 104 5.3 8.4 -- -- 10.5

E14-007 NR 01/07/1999 174 125 -- 17.9 -- 113 13.8

E14-007 NR 02/24/1999 222 173 -- 13.9 -- 393 24.2

E14-007 NR 05/10/1999 297 248 -- -- 4.13 38.3 38.4

E14-007 NR 06/23/1999 341 292 5.5 7.8 -- -- 7.8

E14-007 NR 09/09/1999 419 370 < 5.0 2.1 -- 39.2 9.4

E14-082 NR 07/14/1998 -3 -52 -- -- -- -- 11.0

E14-082 NR 09/30/1998 75 26 < 5.0 < 1.0 0.32 -- 28.6

E14-082 NR 11/19/1998 125 76 < 5.0 14.6 -- -- 14.3

E14-082 NR 12/17/1998 153 104 < 5.0 33.0 -- 123 17.4

E14-082 NR 02/24/1999 222 173 -- 23.9 -- 1,280 19.0

E14-082 NR 05/10/1999 297 248 < 5.0 -- 15.7 408 31.8

E14-082 NR 06/23/1999 341 292 < 5.0 14.3 -- 752 13.4

E14-082 NR 09/09/1999 419 370 < 5.0 6.5 -- 601 29.6

88 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B2. Concentrations of fluorescein, bromide, and sulfur hexafluoride in ground-water samples

 collected from the tracer array at West Branch Canal Creek, Aberdeen Proving Ground,

 Maryland, July 14, 1998 through September 14, 1999--Continued

Days after Bromide, Bromide,

Days after bromide ion- colori- Sulfur Water

fluorescein and SF6 Fluore- selective metric hexa- volume

Site Date injection, injection, scein electrode method fluoride removed

name Replicate sampled 07/17/1998 09/04/1998 (μg/L) (mg/L) (mg/L) (ng/L) (mL)

07/17/1998 09/04/1998

E14-157 NR 07/15/1998 -2 -51 -- -- -- -- 11.0

E14-157 NR 08/04/1998 18 -31 -- -- -- -- 5.4

E14-157 NR 08/05/1998 19 -30 -- -- 0.06 -- 32.2

E14-157 NR 08/20/1998 34 -15 < 5.0 -- -- -- 17.6

E14-157 NR 11/05/1998 111 62 < 5.0 < 1.0 -- -- 10.4

E14-157 NR 12/17/1998 153 104 < 5.0 5.0 -- 117 12.3

E14-157 NR 05/10/1999 297 248 < 5.0 -- 0.60 6.08 39.6

E14-217 NR 07/15/1998 -2 -51 -- -- -- -- 13.0

E14-217 NR 10/01/1998 76 27 < 5.0 < 1.0 -- 1.91 22.7

E14-217 NR 10/20/1998 95 46 < 5.0 1.2 -- -- 26.8

E14-217 NR 12/02/1998 138 89 < 5.0 2.6 -- 16.4 21.6

E14-217 NR 12/17/1998 153 104 < 5.0 2.4 -- 21.7 17.4

E14-217 NR 02/24/1999 222 173 -- 2.1 -- 25.2 26.2

E14-217 NR 05/10/1999 297 248 < 5.0 -- 0.73 < .02 34.9

E14-217 NR 09/09/1999 419 370 < 5.0 1.9 -- -- 13.0

E14-277 NR 07/15/1998 -2 -51 -- -- -- -- 14.0

E14-277 NR 08/20/1998 34 -15 < 5.0 -- -- -- 9.0

E14-277 NR 11/05/1998 111 62 < 5.0 2.2 -- -- 14.0

E14-277 NR 12/02/1998 138 89 < 5.0 4.4 5.15 171 23.5

E14-277 NR 12/17/1998 153 104 < 5.0 3.9 -- 41.3 14.4

E14-277 NR 01/07/1999 174 125 -- 3.0 -- 103 17.2

E14-277 NR 02/25/1999 223 174 -- 214 -- 185 31.1

E14-277 NR 05/10/1999 297 248 < 5.0 2.6 1.27 44.3 35.9

E14-277 1 09/08/1999 418 369 5.7 1.7 -- 127 31.0

E14-277 2 09/08/1999 418 369 < 5.0 1.7 -- -- --

E14-315 NR 07/15/1998 -2 -51 -- -- -- -- 13.0

E14-315 NR 08/05/1998 19 -30 -- -- 0.08 -- 27.8

E14-315 NR 10/20/1998 95 46 < 5.0 < 1.0 -- -- 13.4

E14-315 1 11/19/1998 125 76 < 5.0 3.4 -- -- 14.2

E14-315 2 11/19/1998 125 76 < 5.0 3.3 -- -- --

E14-315 NR 12/17/1998 153 104 < 5.0 6.4 -- 8.62 17.9

E14-315 NR 02/24/1999 222 173 -- 3.4 -- 46.2 13.0

E14-315 NR 05/10/1999 297 248 < 5.0 -- 0.87 4.94 36.6

E14-315 NR 06/23/1999 341 292 < 5.0 3.7 -- 25.8 19.6

E14-315 NR 09/08/1999 418 369 < 5.0 1.1 -- 166 30.0

89 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B2. Concentrations of fluorescein, bromide, and sulfur hexafluoride in ground-water samples

 collected from the tracer array at West Branch Canal Creek, Aberdeen Proving Ground,

 Maryland, July 14, 1998 through September 14, 1999--Continued

Days after Bromide, Bromide,

Days after bromide ion- colori- Sulfur Water

fluorescein and SF6 Fluore- selective metric hexa- volume

Site Date injection, injection, scein electrode method fluoride removed

name Replicate sampled 07/17/1998 09/04/1998 (μg/L) (mg/L) (mg/L) (ng/L) (mL)

07/17/1998 09/04/1998

F02-195 NR 07/14/1998 -3 -52 -- -- -- -- 51.0

F02-195 NR 08/03/1998 17 -32 895 1.3 -- 1.27 22.3

F02-195 1 08/11/1998 25 -24 800 < 1.0 -- -- 27.4

F02-195 2 08/11/1998 25 -24 907 < 4.0 -- -- --

F02-195 NR 09/17/1998 62 13 257 87.6 161 8,870 35.2

F02-195 NR 10/19/1998 94 45 250 279 -- 8,540 21.7

F02-195 NR 11/19/1998 125 76 148 315 -- 11,300 20.2

F02-195 NR 12/17/1998 153 104 134 176 -- 5,460 13.2

F02-195 NR 02/24/1999 222 173 -- 18.4 -- 10,000 26.2

F02-195 NR 05/10/1999 297 248 65.9 -- 1.67 309 41.4

F02-195 NR 09/08/1999 418 369 80.5 < 1.0 -- 1,010 34.1

F02-330 NR 07/14/1998 -3 -52 -- -- -- -- 23.5

F02-330 NR 08/03/1998 17 -32 6.6 1.3 -- 0.16 17.4

F02-330 purge 08/11/1998 25 -24 27.7 1.1 -- -- 21.0

F02-330 NR 08/11/1998 25 -24 75.6 1.4 -- -- 6.0

F02-330 NR 09/30/1998 75 26 37.3 251 -- 4,740 32.3

F02-330 NR 10/19/1998 94 45 45.7 354 389 -- 24.3

F02-330 NR 11/18/1998 124 75 -- -- 303 -- 28.4

F02-330 1 12/02/1998 138 89 52.2 317 -- 8,810 30.1

F02-330 2 12/02/1998 138 89 -- -- -- 7,460 --

F02-330 NR 12/17/1998 153 104 58.9 200 -- 7,990 23.0

F02-330 NR 02/24/1999 222 173 -- 24.7 -- 5,810 25.2

F02-330 NR 05/10/1999 297 248 65.0 1.9 1.63 8,260 39.0

F02-330 NR 06/23/1999 341 292 43.0 3.1 -- 362 22.2

F02-330 1 09/08/1999 418 369 113 1.0 -- 3,010 36.4

F02-330 2 09/08/1999 418 369 -- -- -- 199 --

F07-015 NR 07/14/1998 -3 -52 -- -- -- -- 21.0

F07-015 NR 08/03/1998 17 -32 14.3 1.5 0.04 < .01 39.5

F07-015 NR 09/17/1998 62 13 < 5.0 1.0 7.98 34.9 42.9

F07-015 NR 11/05/1998 111 62 -- -- 103 396 37.3

F07-015 1 12/02/1998 138 89 19.7 137 -- 216 21.2

F07-015 2 12/02/1998 138 89 19.2 155 -- -- --

F07-015 NR 12/17/1998 153 104 179 140 -- 1,610 22.9

F07-015 NR 02/24/1999 222 173 -- 40.1 -- 1,930 24.0

F07-015 NR 05/10/1999 297 248 11.4 3.8 4.57 6,550 52.4

90 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B2. Concentrations of fluorescein, bromide, and sulfur hexafluoride in ground-water samples

 collected from the tracer array at West Branch Canal Creek, Aberdeen Proving Ground,

 Maryland, July 14, 1998 through September 14, 1999--Continued

Days after Bromide, Bromide,

Days after bromide ion- colori- Sulfur Water

fluorescein and SF6 Fluore- selective metric hexa- volume

Site Date injection, injection, scein electrode method fluoride removed

name Replicate sampled 07/17/1998 09/04/1998 (μg/L) (mg/L) (mg/L) (ng/L) (mL)

07/17/1998 09/04/1998

F07-015 NR 06/22/1999 340 291 -- -- -- 3,750 18.6

F07-015 NR 06/23/1999 341 292 16.4 4.5 -- -- 18.6

F07-015 1 09/08/1999 418 369 29.1 1.5 -- 308 36.8

F07-015 2 09/08/1999 418 369 -- -- -- 280 --

F07-075 NR 07/14/1998 -3 -52 -- -- -- -- 40.0

F07-075 NR 08/20/1998 34 -15 111 -- -- -- 23.9

F07-075 NR 10/19/1998 94 45 68.2 36.6 -- 7.13 24.6

F07-075 NR 11/18/1998 124 75 33.0 137 -- 64.6 25.4

F07-075 NR 12/17/1998 153 104 19.2 185 -- 704 26.0

F07-075 NR 02/25/1999 223 174 -- -- -- 5,440 21.2

F07-075 NR 05/10/1999 297 248 -- -- 15.1 383 41.8

F07-075 NR 06/22/1999 340 291 19.5 7.9 -- 2,910 15.0

F07-075 NR 09/08/1999 418 369 67.6 -- -- 688 34.6

F07-157 NR 07/14/1998 -3 -52 -- -- -- -- 22.0

F07-157 purge 08/11/1998 25 -24 < 5.0 1.2 -- -- 19.5

F07-157 NR 08/11/1998 25 -24 < 5.0 1.2 -- -- 7.2

F07-157 NR 09/30/1998 75 26 < 5.0 7.6 10.4 -- 39.0

F07-157 NR 11/05/1998 111 62 -- -- 73.9 185 34.6

F07-157 NR 12/01/1998 137 88 < 5.0 92.8 -- -- 16.4

F07-157 NR 12/16/1998 152 103 < 5.0 72.8 -- 1,270 20.4

F07-157 NR 02/24/1999 222 173 -- 11.3 -- 1,500 27.1

F07-157 NR 05/10/1999 297 248 < 5.0 -- 1.74 329 45.6

F07-157 NR 09/08/1999 418 369 < 5.0 1.1 -- 123 24.7

F07-225 NR 07/14/1998 -3 -52 -- -- -- -- 16.0

F07-225 NR 08/20/1998 34 -15 < 5.0 -- -- -- 22.7

F07-225 NR 09/30/1998 75 26 < 5.0 65.7 -- -- 12.4

F07-225 NR 11/18/1998 124 75 -- -- 165 3,410 17.3

F07-225 NR 12/16/1998 152 103 < 5.0 129 -- 949 18.3

F07-225 NR 01/19/1999 186 137 -- 52.3 36.7 3,440 34.8

F07-225 NR 02/24/1999 222 173 -- 8.6 -- 2,150 13.4

F07-225 NR 05/10/1999 297 248 < 5.0 -- 1.02 357 38.1

F07-225 NR 09/08/1999 418 369 < 5.0 < 1.0 -- 91.2 32.4

F07-285 NR 07/14/1998 -3 -52 -- -- -- -- 23.0

F07-285 NR 08/31/1998 45 -4 < 5.0 -- -- -- 35.6

F07-285 NR 09/30/1998 75 26 < 5.0 31.6 -- 27.3 24.4

91 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B2. Concentrations of fluorescein, bromide, and sulfur hexafluoride in ground-water samples

 collected from the tracer array at West Branch Canal Creek, Aberdeen Proving Ground,

 Maryland, July 14, 1998 through September 14, 1999--Continued

Days after Bromide, Bromide,

Days after bromide ion- colori- Sulfur Water

fluorescein and SF6 Fluore- selective metric hexa- volume

Site Date injection, injection, scein electrode method fluoride removed

name Replicate sampled 07/17/1998 09/04/1998 (μg/L) (mg/L) (mg/L) (ng/L) (mL)

07/17/1998 09/04/1998

F07-285 NR 10/19/1998 94 45 < 5.0 36.7 -- -- 16.0

F07-285 NR 10/21/1998 96 47 -- -- -- 4.16 4.0

F07-285 NR 11/05/1998 111 62 -- -- 47.9 138 32.0

F07-285 NR 12/01/1998 137 88 < 5.0 46.5 -- 77.1 18.8

F07-285 NR 12/17/1998 153 104 < 5.0 23.5 -- 270 24.2

F07-285 NR 02/24/1999 222 173 -- 9.0 -- 31.2 18.8

F07-285 1 05/11/1999 298 249 < 5.0 -- 0.82 28.9 59.4

F07-285 2 05/12/1999 299 250 -- -- 0.59 -- --

F07-285 NR 09/08/1999 418 369 < 5.0 1.0 -- 32.9 37.6

F07-315 NR 07/14/1998 -3 -52 -- -- -- -- 37.0

F07-315 NR 08/20/1998 34 -15 < 5.0 -- -- -- 30.4

F07-315 NR 10/19/1998 94 45 -- -- 17.3 -- 17.5

F07-315 NR 11/18/1998 124 75 < 5.0 35.2 -- 59.3 27.4

F07-315 NR 12/17/1998 153 104 < 5.0 15.2 -- 190 22.6

F07-315 NR 02/24/1999 222 173 -- 3.4 -- 232 18.0

F07-315 NR 05/11/1999 298 249 7.4 -- 0.65 68.4 41.6

F07-315 NR 06/22/1999 340 291 < 5.0 2.2 -- 108 20.6

F07-315 NR 09/08/1999 418 369 < 5.0 1.0 -- 16.3 35.6

F14-045 NR 07/14/1998 -3 -52 -- -- -- -- 17.0

F14-045 NR 08/04/1998 18 -31 -- -- 0.09 -- 25.4

F14-045 NR 08/05/1998 19 -30 -- -- -- -- 11.6

F14-045 purge 08/11/1998 25 -24 < 5.0 -- -- -- 20.4

F14-045 NR 08/11/1998 25 -24 < 5.0 1.9 -- -- 6.0

F14-045 1 09/30/1998 75 26 < 5.0 1.3 -- -- 24.9

F14-045 2 09/30/1998 75 26 < 5.0 1.0 -- -- --

F14-045 NR 11/18/1998 124 75 < 5.0 8.2 -- -- 19.0

F14-045 NR 12/16/1998 152 103 < 5.0 43.3 -- 168 14.2

F14-045 NR 02/24/1999 222 173 -- 59.8 -- 943 15.9

F14-045 NR 05/11/1999 298 249 < 5.0 -- 9.68 244 31.3

F14-045 NR 06/22/1999 340 291 < 5.0 6.0 -- 316 15.8

F14-045 NR 09/08/1999 418 369 < 5.0 1.5 -- 14.3 26.4

F14-135 NR 07/15/1998 -2 -51 -- -- -- -- 15.0

F14-135 NR 08/20/1998 34 -15 < 5.0 -- -- -- 19.2

F14-135 1 10/19/1998 94 45 < 5.0 20.3 -- -- 36.0

F14-135 2 10/19/1998 94 45 -- 19.3 -- -- --

92 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B2. Concentrations of fluorescein, bromide, and sulfur hexafluoride in ground-water samples

 collected from the tracer array at West Branch Canal Creek, Aberdeen Proving Ground,

 Maryland, July 14, 1998 through September 14, 1999--Continued

Days after Bromide, Bromide,

Days after bromide ion- colori- Sulfur Water

fluorescein and SF6 Fluore- selective metric hexa- volume

Site Date injection, injection, scein electrode method fluoride removed

name Replicate sampled 07/17/1998 09/04/1998 (μg/L) (mg/L) (mg/L) (ng/L) (mL)

07/17/1998 09/04/1998

F14-135 1 11/05/1998 111 62 < 5.0 30.4 -- -- 24.1

F14-135 2 11/05/1998 111 62 < 5.0 26.6 -- -- --

F14-135 NR 12/16/1998 152 103 < 5.0 20.8 -- 140 19.3

F14-135 NR 01/19/1999 186 137 -- 9.8 10.3 205 34.1

F14-135 NR 02/25/1999 223 174 -- -- -- 12.4 14.0

F14-135 NR 05/11/1999 298 249 -- -- 1.62 202 39.4

F14-135 NR 09/07/1999 417 368 < 5.0 <1.0 -- 74.8 35.0

F14-210 NR 07/15/1998 -2 -51 -- -- -- -- 21.0

F14-210 NR 09/17/1998 62 13 -- -- -- -- 12.4

F14-210 NR 10/21/1998 96 47 5.2 1.2 -- -- 24.9

F14-210 1 12/01/1998 137 88 5.3 < 1.0 -- 394 31.3

F14-210 2 12/01/1998 137 88 5.3 < 1.0 -- 363 --

F14-210 NR 12/16/1998 152 103 < 5.0 1.0 -- 518 27.3

F14-210 NR 02/24/1999 222 173 -- 1.0 -- 915 30.1

F14-210 NR 05/11/1999 298 249 < 5.0 -- 0.17 9.94 43.6

F14-210 NR 09/07/1999 417 368 < 5.0 < 1.0 -- 21.9 50.6

F14-292 NR 07/14/1998 -3 -52 < 5.0 -- -- -- 26.0

F14-292 NR 08/04/1998 18 -31 -- -- 0.08 -- 36.8

F14-292 NR 09/30/1998 75 26 < 5.0 2.6 -- -- 22.8

F14-292 1 11/18/1998 124 75 < 5.0 11.8 -- -- 27.4

F14-292 2 11/18/1998 124 75 < 5.0 11.9 -- -- --

F14-292 NR 12/16/1998 152 103 < 5.0 10.4 -- 284 25.2

F14-292 NR 02/24/1999 222 173 -- 3.8 -- 25.7 16.1

F14-292 NR 05/11/1999 298 249 < 5.0 -- 0.65 7.40 46.4

F14-292 1 09/07/1999 417 368 < 5.0 1.2 -- 44.0 59.6

F14-292 2 09/07/1999 417 368 < 5.0 < 1.0 -- 42.9 --

F14-345 NR 07/15/1998 -2 -51 -- -- -- -- 19.0

F14-345 NR 08/20/1998 34 -15 < 5.0 -- -- -- 13.4

F14-345 NR 11/05/1998 111 62 < 5.0 1.1 -- -- 10.3

F14-345 NR 12/01/1998 137 88 < 5.0 5.2 5.21 -- 23.8

F14-345 NR 12/17/1998 153 104 < 5.0 7.6 -- 18.0 24.8

F14-345 NR 01/07/1999 174 125 -- 12.1 -- 44.0 15.8

F14-345 NR 02/24/1999 222 173 -- 8.6 -- 4.91 12.8

F14-345 NR 05/11/1999 298 249 < 5.0 -- 1.97 19.4 29.6

F14-345 NR 06/22/1999 340 291 5.8 5.7 -- 84.8 27.4

93 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B2. Concentrations of fluorescein, bromide, and sulfur hexafluoride in ground-water samples

 collected from the tracer array at West Branch Canal Creek, Aberdeen Proving Ground,

 Maryland, July 14, 1998 through September 14, 1999--Continued

Days after Bromide, Bromide,

Days after bromide ion- colori- Sulfur Water

fluorescein and SF6 Fluore- selective metric hexa- volume

Site Date injection, injection, scein electrode method fluoride removed

name Replicate sampled 07/17/1998 09/04/1998 (μg/L) (mg/L) (mg/L) (ng/L) (mL)

07/17/1998 09/04/1998

F14-345 NR 09/07/1999 417 368 < 5.0 1.5 -- 42.5 25.4

G02-000 NR 07/14/1998 -3 -52 -- -- -- -- 26.0

G02-000 NR 08/03/1998 17 -32 3,460 1.2 -- < .01 14.3

G02-000 NR 08/19/1998 33 -16 5,120 < 1.0 -- -- 22.6

G02-000 NR 09/17/1998 62 13 -- -- 151 -- 16.6

G02-000 NR 10/21/1998 96 47 5,770 991 1,090 14,000 16.5

G02-000 NR 11/18/1998 124 75 2,370 548 -- 79,400 29.0

G02-000 NR 12/16/1998 152 103 2,030 296 -- 87,400 23.1

G02-000 NR 02/25/1999 223 174 -- 48.1 -- 25,500 24.3

G02-000 NR 05/11/1999 298 249 523 4.4 2.55 2,470 37.5

G02-000 NR 06/22/1999 340 291 448 2.5 -- 2,880 24.6

G02-000 1 09/07/1999 417 368 1,020 < 1.0 -- 1,140 27.6

G02-000 2 09/07/1999 417 368 -- -- -- 1,240 --

G07-060 NR 07/14/1998 -3 -52 -- -- -- -- 45.0

G07-060 NR 08/05/1998 19 -30 3,790 2.2 -- -- 8.0

G07-060 NR 08/19/1998 33 -16 1,500 < 1.0 -- -- 29.2

G07-060 NR 11/05/1998 111 62 -- -- 180 15,900 30.9

G07-060 1 12/01/1998 137 88 2,280 189 -- 11,600 35.6

G07-060 2 12/01/1998 137 88 1,870 186 -- 4,770 --

G07-060 purge 12/16/1998 152 103 1,160 151 -- -- 11.0

G07-060 NR 12/16/1998 152 103 1,660 107 -- 23,600 20.1

G07-060 NR 02/25/1999 223 174 -- 28.0 -- 9,020 28.0

G07-060 NR 05/11/1999 298 249 391 4.0 3.55 885 47.3

G07-060 NR 06/22/1999 340 291 252 2.1 -- 135 27.6

G07-060 1 09/07/1999 417 368 377 <1.0 -- 1,050 51.0

G07-060 2 09/07/1999 417 368 296 <1.0 -- -- --

G07-135 NR 07/14/1998 -3 -52 -- -- -- -- 26.0

G07-135 purge 08/11/1998 25 -24 < 5.0 1.3 -- -- 17.5

G07-135 NR 08/11/1998 25 -24 < 5.0 1.6 -- -- 8.0

G07-135 NR 08/31/1998 45 -4 < 5.0 -- -- -- 29.8

G07-135 NR 09/30/1998 75 26 < 5.0 46.2 49.1 -- 33.7

G07-135 NR 10/19/1998 94 45 < 5.0 84.5 -- -- 19.4

G07-135 NR 11/18/1998 124 75 -- -- 127 -- 23.6

G07-135 NR 12/16/1998 152 103 < 5.0 88.3 -- 2,570 16.3

G07-135 1 01/07/1999 174 125 -- 59.5 -- 6,260 19.4

94 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B2. Concentrations of fluorescein, bromide, and sulfur hexafluoride in ground-water samples

 collected from the tracer array at West Branch Canal Creek, Aberdeen Proving Ground,

 Maryland, July 14, 1998 through September 14, 1999--Continued

Days after Bromide, Bromide,

Days after bromide ion- colori- Sulfur Water

fluorescein and SF6 Fluore- selective metric hexa- volume

Site Date injection, injection, scein electrode method fluoride removed

name Replicate sampled 07/17/1998 09/04/1998 (μg/L) (mg/L) (mg/L) (ng/L) (mL)

07/17/1998 09/04/1998

G07-135 2 01/07/1999 174 125 -- -- -- 5,900 --

G07-135 NR 02/25/1999 223 174 -- 9.8 -- 2,680 18.6

G07-135 NR 05/11/1999 298 249 < 5.0 -- 2.32 819 37.0

G07-135 1 09/07/1999 417 368 < 5.0 <1.0 -- 45.1 21.6

G07-135 2 09/07/1999 417 368 < 5.0 <1.0 -- -- --

G07-195 NR 07/14/1998 -3 -52 5.9 -- -- -- 21.0

G07-195 NR 08/03/1998 17 -32 < 5.0 1.3 -- < .01 20.3

G07-195 NR 08/19/1998 33 -16 29.8 -- -- -- 20.0

G07-195 NR 09/17/1998 62 13 12.8 76.5 121 2,910 26.7

G07-195 NR 11/05/1998 111 62 -- -- 287 8,350 27.2

G07-195 NR 12/01/1998 137 88 16.0 211 -- -- 18.6

G07-195 NR 12/16/1998 152 103 18.4 119 -- 6,220 18.8

G07-195 NR 02/25/1999 223 174 -- 11.3 -- 5,610 27.0

G07-195 NR 05/11/1999 298 249 7.8 -- 1.81 2,260 37.7

G07-195 1 09/07/1999 417 368 28.7 1.1 -- 459 35.8

G07-195 2 09/07/1999 417 368 -- -- -- 722 --

G07-255 NR 07/14/1998 -3 -52 -- -- -- -- 18.0

G07-255 purge 08/11/1998 25 -24 < 5.0 1.4 -- -- 18.0

G07-255 NR 08/11/1998 25 -24 5.3 1.3 -- -- 6.0

G07-255 NR 09/30/1998 75 26 < 5.0 286 293 -- 32.6

G07-255 NR 10/19/1998 94 45 -- -- 341 2,420 21.9

G07-255 NR 11/18/1998 124 75 < 5.0 275 -- 2,310 29.7

G07-255 NR 12/16/1998 152 103 16.0 110 -- 134 24.2

G07-255 NR 01/07/1999 174 125 -- 42.4 -- 8,500 19.1

G07-255 NR 02/25/1999 223 174 -- 8.1 -- 2,270 20.3

G07-255 NR 09/07/1999 417 368 37.7 <1.0 -- 90.1 24.4

G07-300 NR 07/14/1998 -3 -52 -- -- -- -- 60.0

G07-300 purge 08/11/1998 25 -24 < 5.0 1.1 -- -- 22.7

G07-300 NR 08/11/1998 25 -24 12.7 1.2 -- -- 7.0

G07-300 NR 08/19/1998 33 -16 < 5.0 -- -- -- 29.7

G07-300 NR 09/30/1998 75 26 < 5.0 133 -- 585 25.3

G07-300 NR 11/05/1998 111 62 -- -- 197 2,390 32.0

G07-300 NR 12/01/1998 137 88 < 5.0 150 -- 1,640 26.0

G07-300 NR 12/16/1998 152 103 < 5.0 72.8 -- 2,370 29.0

G07-300 NR 02/25/1999 223 174 -- 23.8 -- 1,690 15.8

95 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B2. Concentrations of fluorescein, bromide, and sulfur hexafluoride in ground-water samples

 collected from the tracer array at West Branch Canal Creek, Aberdeen Proving Ground,

 Maryland, July 14, 1998 through September 14, 1999--Continued

Days after Bromide, Bromide,

Days after bromide ion- colori- Sulfur Water

fluorescein and SF6 Fluore- selective metric hexa- volume

Site Date injection, injection, scein electrode method fluoride removed

name Replicate sampled 07/17/1998 09/04/1998 (μg/L) (mg/L) (mg/L) (ng/L) (mL)

07/17/1998 09/04/1998

G07-300 1 05/11/1999 298 249 < 5.0 4.0 2.90 866 65.4

G07-300 2 05/11/1999 298 249 -- 5.2 1.29 -- --

G07-300 NR 06/22/1999 340 291 < 5.0 2.3 -- 77.8 23.8

G07-300 NR 09/07/1999 417 368 5.1 <1.0 -- 181 36.3

G07-345 NR 07/14/1998 -3 -52 -- -- -- -- 20.0

G07-345 NR 08/03/1998 17 -32 < 5.0 1.1 -- < .01 14.0

G07-345 NR 09/17/1998 62 13 < 5.0 4.3 -- 30.6 22.4

G07-345 NR 10/19/1998 94 45 < 5.0 38.1 -- -- 26.7

G07-345 NR 10/21/1998 96 47 -- -- -- 23.0 2.7

G07-345 NR 11/18/1998 124 75 -- -- 82.2 -- 25.8

G07-345 NR 12/16/1998 152 103 8.5 71.1 -- 1,000 24.6

G07-345 purge 01/07/1999 174 125 -- 66.9 -- -- 13.6

G07-345 NR 01/07/1999 174 125 -- 55.8 -- 2,730 10.9

G07-345 NR 02/25/1999 223 174 -- 19.2 -- 2,430 12.8

G07-345 NR 05/11/1999 298 249 < 5.0 3.7 4.23 185 43.0

G07-345 NR 06/22/1999 340 291 < 5.0 3.6 -- 73.5 23.8

G07-345 NR 09/07/1999 417 368 < 5.0 1.1 -- 137 39.6

G14-022 NR 07/14/1998 -3 -52 -- -- -- -- 18.0

G14-022 NR 08/19/1998 33 -16 < 5.0 -- -- -- 15.2

G14-022 NR 09/30/1998 75 26 < 5.0 2.2 -- -- 14.0

G14-022 NR 11/05/1998 111 62 < 5.0 7.9 -- -- 17.2

G14-022 NR 12/16/1998 152 103 < 5.0 30.3 -- 352 12.0

G14-022 NR 01/07/1999 174 125 -- 49.2 -- 1,920 17.6

G14-022 purge 02/25/1999 223 174 -- 34.1 -- 1,000 11.4

G14-022 NR 02/25/1999 223 174 -- 22.8 -- 2,100 8.4

G14-022 NR 05/11/1999 298 249 < 5.0 -- 4.12 205 34.8

G14-022 NR 06/22/1999 340 291 < 5.0 2.9 -- -- 22.4

G14-022 NR 09/07/1999 417 368 < 5.0 < 1.0 -- 57.6 30.4

G14-105 NR 07/15/1998 -2 -51 -- -- -- -- 18.0

G14-105 purge 08/11/1998 25 -24 871 < 1.0 -- -- 22.0

G14-105 NR 08/11/1998 25 -24 1,120 1.9 -- -- 6.2

G14-105 NR 09/17/1998 62 13 713 32.5 -- 312 27.0

G14-105 NR 10/19/1998 94 45 402 95.8 -- -- 20.3

G14-105 1 11/18/1998 124 75 -- -- 122 3,720 46.2

G14-105 2 11/18/1998 124 75 -- -- 134 3,230 --

96 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B2. Concentrations of fluorescein, bromide, and sulfur hexafluoride in ground-water samples

 collected from the tracer array at West Branch Canal Creek, Aberdeen Proving Ground,

 Maryland, July 14, 1998 through September 14, 1999--Continued

Days after Bromide, Bromide,

Days after bromide ion- colori- Sulfur Water

fluorescein and SF6 Fluore- selective metric hexa- volume

Site Date injection, injection, scein electrode method fluoride removed

name Replicate sampled 07/17/1998 09/04/1998 (μg/L) (mg/L) (mg/L) (ng/L) (mL)

07/17/1998 09/04/1998

G14-105 NR 12/16/1998 152 103 703 73.3 -- 3,550 20.2

G14-105 NR 02/18/1999 216 167 -- 26.2 -- 4,620 21.8

G14-105 1 05/11/1999 298 249 145 4.8 4.52 1,760 57.8

G14-105 2 05/11/1999 298 249 -- -- 4.12 -- --

G14-105 NR 09/07/1999 417 368 147 1.1 -- 170 40.7

G14-165 NR 07/15/1998 -2 -51 -- -- -- -- 19.0

G14-165 NR 08/04/1998 18 -31 -- -- 0.07 -- 40.3

G14-165 NR 08/19/1998 33 -16 < 5.0 -- -- -- 28.6

G14-165 NR 09/30/1998 75 26 < 5.0 9.8 -- -- 24.0

G14-165 NR 11/18/1998 124 75 -- -- 21.2 270 39.4

G14-165 1 12/16/1998 152 103 < 5.0 15.5 -- 256 35.4

G14-165 2 12/16/1998 152 103 < 5.0 16.3 -- -- --

G14-165 NR 02/18/1999 216 167 -- 3.4 -- 592 24.6

G14-165 1 05/11/1999 298 249 < 5.0 -- 0.40 37.5 57.4

G14-165 2 05/11/1999 298 249 -- -- 0.44 -- --

G14-165 NR 09/03/1999 413 364 < 5.0 < 1.0 -- 10.8 24.7

G14-225 NR 07/15/1998 -2 -51 -- -- -- -- 14.0

G14-225 NR 08/19/1998 33 -16 < 5.0 -- -- -- 11.2

G14-225 NR 10/20/1998 95 46 < 5.0 18.2 -- -- 23.2

G14-225 1 12/01/1998 137 88 -- -- 24.0 89.7 34.6

G14-225 2 12/01/1998 137 88 -- -- 30.3 -- --

G14-225 1 12/16/1998 152 103 < 5.0 19.4 -- 140 28.4

G14-225 2 12/16/1998 152 103 < 5.0 -- -- -- --

G14-225 NR 02/18/1999 216 167 -- 2.6 -- 202 33.7

G14-225 1 05/11/1999 298 249 < 5.0 -- 0.26 63.6 50.8

G14-225 2 05/11/1999 298 249 -- -- 0.22 -- --

G14-225 NR 09/03/1999 413 364 < 5.0 < 1.0 -- 17.8 33.2

G14-285 NR 07/15/1998 -2 -51 -- -- -- -- 17.0

G14-285 purge 08/11/1998 25 -24 < 5.0 1.7 -- -- 20.2

G14-285 NR 08/11/1998 25 -24 < 5.0 1.4 -- -- 6.0

G14-285 NR 11/05/1998 111 62 < 5.0 4.8 -- -- 20.8

G14-285 1 12/16/1998 152 103 < 5.0 8.9 -- 70.4 28.4

G14-285 2 12/16/1998 152 103 -- -- -- 63.6 --

G14-285 NR 01/07/1999 174 125 -- 6.3 -- 114 21.1

G14-285 NR 02/18/1999 216 167 -- 2.3 -- 178 38.2

97 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B2. Concentrations of fluorescein, bromide, and sulfur hexafluoride in ground-water samples

 collected from the tracer array at West Branch Canal Creek, Aberdeen Proving Ground,

 Maryland, July 14, 1998 through September 14, 1999--Continued

Days after Bromide, Bromide,

Days after bromide ion- colori- Sulfur Water

fluorescein and SF6 Fluore- selective metric hexa- volume

Site Date injection, injection, scein electrode method fluoride removed

name Replicate sampled 07/17/1998 09/04/1998 (μg/L) (mg/L) (mg/L) (ng/L) (mL)

07/17/1998 09/04/1998

G14-285 NR 05/11/1999 298 249 < 5.0 -- 0.56 80.6 37.2

G14-285 NR 09/03/1999 413 364 < 5.0 < 1.0 -- 17.4 17.4

G14-330 NR 07/17/1998 0 -49 -- -- 0.03 -- 20.0

G14-330 NR 08/05/1998 19 -30 -- -- -- -- 6.4

G14-330 NR 08/19/1998 33 -16 -- -- -- -- 4.0

G14-330 NR 08/31/1998 45 -4 < 5.0 -- -- -- 7.0

G14-330 NR 10/20/1998 95 46 < 5.0 4.1 -- 26.0 40.8

G14-330 NR 11/18/1998 124 75 < 5.0 7.4 -- -- 14.6

G14-330 NR 12/16/1998 152 103 < 5.0 9.1 -- 30.7 25.2

G14-330 NR 02/18/1999 216 167 -- 6.2 -- 156 19.0

G14-330 1 05/11/1999 298 249 < 5.0 -- 1.21 46.4 41.6

G14-330 2 05/11/1999 298 249 < 5.0 -- -- -- --

G14-330 NR 06/22/1999 340 291 < 5.0 2.4 -- 14.1 24.0

G14-330 1 09/03/1999 413 364 < 5.0 < 1.0 -- 16.0 35.0

G14-330 2 09/03/1999 413 364 < 5.0 < 1.0 -- -- --

G18-180 NR 08/19/1998 33 -16 < 5.0 -- -- -- 31.4

G18-180 NR 11/05/1998 111 62 < 5.0 1.7 -- -- 24.4

G18-180 NR 12/16/1998 152 103 < 5.0 1.0 -- 49.0 21.9

G18-180 NR 02/18/1999 216 167 -- < 1.0 -- 211 33.6

G18-180 1 05/11/1999 298 249 < 5.0 -- 0.06 45.4 69.6

G18-180 2 05/11/1999 298 249 -- -- 0.05 -- --

G18-180 NR 09/02/1999 412 363 < 5.0 < 1.0 -- 30.9 32.0

H00-000 NR 07/14/1998 -3 -52 < 5.0 -- -- -- 51.0

H00-000 1 07/17/1998 0 -49 < 5.0 -- -- -- 45.0

H00-000 2 07/17/1998 0 -49 < 5.0 -- -- -- --

H00-000 purge 12/17/1998 153 104 -- -- -- 222,000 20.0

H00-000 NR 12/17/1998 153 104 35,800 E 28.2 -- 356,000 3.0

H00-000 purge 06/22/1999 340 291 1,460 3.7 2.69 -- 26.0

H00-000 NR 06/22/1999 340 291 1,560 42.6 -- 48,300 26.6

H00-000 1, purge 09/14/1999 424 375 1,920 1.9 -- 60,600 18.6

H00-000 2, purge 09/14/1999 424 375 1,940 -- -- -- --

H00-000 NR 09/14/1999 424 375 2,830 < 1.0 -- 8,190 14.6

H07-030 NR 07/14/1998 -3 -52 7.7 -- -- -- 21.0

H07-030 purge 08/11/1998 25 -24 268 1.3 -- -- 22.6

H07-030 NR 08/11/1998 25 -24 433 1.5 -- -- 7.0

98 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B2. Concentrations of fluorescein, bromide, and sulfur hexafluoride in ground-water samples

 collected from the tracer array at West Branch Canal Creek, Aberdeen Proving Ground,

 Maryland, July 14, 1998 through September 14, 1999--Continued

Days after Bromide, Bromide,

Days after bromide ion- colori- Sulfur Water

fluorescein and SF6 Fluore- selective metric hexa- volume

Site Date injection, injection, scein electrode method fluoride removed

name Replicate sampled 07/17/1998 09/04/1998 (μg/L) (mg/L) (mg/L) (ng/L) (mL)

07/17/1998 09/04/1998

H07-030 NR 09/17/1998 62 13 267 104 397 3,700 27.8

H07-030 NR 09/30/1998 75 26 46.3 225 286 1,970 27.1

H07-030 NR 11/05/1998 111 62 98.2 148 144 -- 24.7

H07-030 NR 12/01/1998 137 88 690 100 -- 2,580 26.4

H07-030 NR 12/16/1998 152 103 49.9 67.5 -- 3,670 18.6

H07-030 NR 01/07/1999 174 125 -- 40.9 -- 1,300 14.9

H07-030 NR 02/18/1999 216 167 -- 17.0 -- 1,920 21.6

H07-030 NR 05/11/1999 298 249 25.7 2.3 1.65 342 32.0

H07-030 NR 06/22/1999 340 291 < 5.0 2.1 -- 351 12.8

H07-030 NR 09/02/1999 412 363 10.6 -- -- 102 23.9

H07-090 NR 07/14/1998 -3 -52 -- -- -- -- 35.0

H07-090 NR 08/03/1998 17 -32 92.4 1.0 -- < .02 13.0

H07-090 NR 08/19/1998 33 -16 1,650 -- -- -- 24.1

H07-090 NR 10/19/1998 94 45 134 239 -- 4,660 30.7

H07-090 NR 11/18/1998 124 75 202 185 87.7 1,880 54.8

H07-090 purge 12/16/1998 152 103 134 116 -- -- 17.8

H07-090 NR 12/16/1998 152 103 129 80.3 -- 5,440 9.8

H07-090 1, purge 01/07/1999 174 125 -- 57.0 -- -- 18.1

H07-090 2, purge 01/07/1999 174 125 -- 56.7 -- -- --

H07-090 NR 01/07/1999 174 125 -- 37.5 -- 13,000 12.1

H07-090 NR 02/18/1999 216 167 -- 17.4 -- 6,220 27.7

H07-090 NR 05/11/1999 298 249 114 -- 1.34 895 40.2

H07-090 NR 06/22/1999 340 291 139 2.0 -- 493 26.0

H07-090 NR 09/02/1999 412 363 450 < 1.0 -- 589 32.6

H07-150 NR 07/14/1998 -3 -52 -- -- -- -- 39.0

H07-150 purge 08/11/1998 25 -24 < 5.0 -- -- -- 31.2

H07-150 NR 08/11/1998 25 -24 114 1.2 -- -- 6.0

H07-150 NR 08/19/1998 33 -16 83.4 -- -- -- 28.0

H07-150 NR 09/17/1998 62 13 17.6 123 -- 658 29.9

H07-150 NR 10/19/1998 94 45 -- -- 118 2,880 36.5

H07-150 NR 11/18/1998 124 75 7.5 84.1 -- 3,200 33.2

H07-150 NR 12/16/1998 152 103 10.1 39.6 -- 1,900 28.5

H07-150 NR 02/18/1999 216 167 -- 16.9 -- 4,380 16.6

H07-150 1 05/12/1999 299 250 14.7 -- 1.28 948 70.4

H07-150 2 05/12/1999 299 250 -- -- 0.80 -- --

99 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B2. Concentrations of fluorescein, bromide, and sulfur hexafluoride in ground-water samples

 collected from the tracer array at West Branch Canal Creek, Aberdeen Proving Ground,

 Maryland, July 14, 1998 through September 14, 1999--Continued

Days after Bromide, Bromide,

Days after bromide ion- colori- Sulfur Water

fluorescein and SF6 Fluore- selective metric hexa- volume

Site Date injection, injection, scein electrode method fluoride removed

name Replicate sampled 07/17/1998 09/04/1998 (μg/L) (mg/L) (mg/L) (ng/L) (mL)

07/17/1998 09/04/1998

H07-150 NR 09/02/1999 412 363 19.9 < 1.0 -- 320 43.0

H07-210 NR 07/14/1998 -3 -52 -- -- -- -- 34.0

H07-210 purge 08/11/1998 25 -24 9.6 1.7 -- -- 22.8

H07-210 NR 08/11/1998 25 -24 832 1.9 -- -- 6.0

H07-210 NR 09/17/1998 62 13 106 194 265 2,210 26.7

H07-210 NR 09/30/1998 75 26 130 297 319 5,300 29.4

H07-210 NR 11/05/1998 111 62 -- -- 200 5,470 28.7

H07-210 NR 12/01/1998 137 88 298 130 -- 3,160 25.4

H07-210 purge 12/16/1998 152 103 -- -- -- 3,570 20.0

H07-210 NR 12/16/1998 152 103 594 52.9 -- 3,480 9.4

H07-210 NR 02/18/1999 216 167 -- 7.5 -- 5,950 27.5

H07-210 NR 05/12/1999 299 250 52.4 -- 0.55 453 53.2

H07-210 NR 09/02/1999 412 363 63.5 < 1.0 -- 197 24.0

H07-270 NR 07/14/1998 -3 -52 -- -- -- -- 58.0

H07-270 NR 08/03/1998 17 -32 < 5.0 1.1 -- < .03 11.0

H07-270 NR 08/19/1998 33 -16 9.7 -- -- -- 29.8

H07-270 NR 10/19/1998 94 45 < 5.0 58.7 -- 492 31.0

H07-270 1 11/18/1998 124 75 < 5.0 38.3 -- 413 35.6

H07-270 2 11/18/1998 124 75 < 5.0 38.0 -- -- --

H07-270 purge 12/16/1998 152 103 8.5 27.9 -- 1,750 26.1

H07-270 NR 12/16/1998 152 103 11.7 15.5 -- 922 10.2

H07-270 NR 02/18/1999 216 167 -- 4.9 -- 695 26.0

H07-270 1 05/12/1999 299 250 6.2 -- 0.25 74.6 68.9

H07-270 2 05/12/1999 299 250 -- -- 0.25 -- --

H07-270 NR 09/02/1999 412 363 5.2 < 1.0 -- 41.7 44.2

H07-330 NR 07/14/1998 -3 -52 -- -- -- -- 24.0

H07-330 NR 08/11/1998 25 -24 < 5.0 1.3 -- -- 7.6

H07-330 NR 09/17/1998 62 13 -- -- -- -- 5.6

H07-330 1 09/30/1998 75 26 11.8 82.9 155 542 55.4

H07-330 2 09/30/1998 75 26 12.5 81.1 119 425 --

H07-330 NR 11/04/1998 110 61 -- -- 78.0 1,190 32.6

H07-330 NR 12/01/1998 137 88 < 5.0 43.4 -- 985 29.6

H07-330 1 12/16/1998 152 103 < 5.0 20.7 -- 1,020 32.4

H07-330 2 12/16/1998 152 103 32.8 18.9 -- 879 --

H07-330 NR 02/18/1999 216 167 -- 1.9 -- 809 26.4

100 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B2. Concentrations of fluorescein, bromide, and sulfur hexafluoride in ground-water samples

 collected from the tracer array at West Branch Canal Creek, Aberdeen Proving Ground,

 Maryland, July 14, 1998 through September 14, 1999--Continued

Days after Bromide, Bromide,

Days after bromide ion- colori- Sulfur Water

fluorescein and SF6 Fluore- selective metric hexa- volume

Site Date injection, injection, scein electrode method fluoride removed

name Replicate sampled 07/17/1998 09/04/1998 (μg/L) (mg/L) (mg/L) (ng/L) (mL)

07/17/1998 09/04/1998

H07-330 NR 05/12/1999 299 250 19.2 -- 0.57 88.3 48.8

H07-330 NR 06/22/1999 340 291 44.9 1.7 -- 52.5 31.8

H07-330 NR 09/02/1999 412 363 47.8 < 1.0 -- 48.8 30.6

H14-000 NR 07/14/1998 -3 -52 -- -- -- -- 50.0

H14-000 NR 07/15/1998 -2 -51 -- -- -- -- 53.0

H14-000 NR 08/04/1998 18 -31 -- -- 0.04 -- 38.1

H14-000 NR 08/19/1998 33 -16 10.7 < 1.0 -- -- 28.0

H14-000 NR 10/19/1998 94 45 -- -- 43.7 4.22 47.2

H14-000 NR 11/18/1998 124 75 < 5.0 1.7 -- -- 31.8

H14-000 purge 12/16/1998 152 103 28.2 2.0 -- 77.4 11.2

H14-000 NR 12/16/1998 152 103 9.6 7.3 -- 206 41.0

H14-000 NR 02/18/1999 216 167 -- 3.3 -- 451 33.1

H14-000 1 05/12/1999 299 250 9.4 -- 0.85 238 76.2

H14-000 2 05/12/1999 299 250 -- -- 0.79 232 --

H14-000 NR 06/22/1999 340 291 45.8 1.6 0.36 166 56.6

H14-000 NR 09/02/1999 412 363 < 5.0 < 1.0 -- 119 44.2

H14-060 NR 07/14/1998 -3 -52 -- -- -- -- 150.0

H14-060 purge 08/11/1998 25 -24 6.4 -- -- -- 25.0

H14-060 NR 08/11/1998 25 -24 6.4 -- -- -- 8.0

H14-060 NR 08/31/1998 45 -4 5.1 -- -- -- 28.5

H14-060 NR 10/19/1998 94 45 < 5.0 3.3 -- -- 49.0

H14-060 NR 12/01/1998 137 88 23.5 19.4 -- 489 24.1

H14-060 purge 12/16/1998 152 103 38.4 16.9 -- 358 28.6

H14-060 1 12/16/1998 152 103 76.9 28.0 -- 1,580 17.0

H14-060 2 12/16/1998 152 103 75.3 28.4 -- 1,170 --

H14-060 NR 02/18/1999 216 167 -- 11.8 -- 5,890 48.3

H14-060 1 05/12/1999 299 250 51.9 -- 1.50 1,760 62.8

H14-060 2 05/12/1999 299 250 36.5 -- -- 1,470 --

H14-060 NR 06/22/1999 340 291 36.5 2.1 0.67 1,490 56.6

H14-060 NR 09/02/1999 412 363 46.5 < 1.0 -- 584 44.2

H14-120 NR 07/15/1998 -2 -51 20.6 -- -- -- 35.0

H14-120 NR 08/19/1998 33 -16 < 5.0 -- -- -- 37.2

H14-120 NR 09/30/1998 75 26 < 5.0 12.3 -- -- 24.4

H14-120 1 11/18/1998 124 75 -- -- 18.7 53.5 48.4

H14-120 2 11/18/1998 124 75 -- -- 18.0 -- --

101 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B2. Concentrations of fluorescein, bromide, and sulfur hexafluoride in ground-water samples

 collected from the tracer array at West Branch Canal Creek, Aberdeen Proving Ground,

 Maryland, July 14, 1998 through September 14, 1999--Continued

Days after Bromide, Bromide,

Days after bromide ion- colori- Sulfur Water

fluorescein and SF6 Fluore- selective metric hexa- volume

Site Date injection, injection, scein electrode method fluoride removed

name Replicate sampled 07/17/1998 09/04/1998 (μg/L) (mg/L) (mg/L) (ng/L) (mL)

07/17/1998 09/04/1998

H14-120 purge 12/16/1998 152 103 < 5.0 16.2 -- -- 20.0

H14-120 1 12/16/1998 152 103 < 5.0 12.6 -- 113 13.0

H14-120 2 12/16/1998 152 103 -- -- -- 105 --

H14-120 NR 02/18/1999 216 167 -- 6.5 -- 224 29.1

H14-120 1 05/12/1999 299 250 < 5.0 -- 1.33 540 46.0

H14-120 2 05/12/1999 299 250 -- -- -- 300 --

H14-120 NR 09/02/1999 412 363 < 5.0 < 1.0 -- 92.2 30.8

H14-180 NR 07/15/1998 -2 -51 -- -- -- -- 25.0

H14-180 NR 08/04/1998 18 -31 -- -- -- -- 7.2

H14-180 NR 08/05/1998 19 -30 378 2.0 -- -- 34.5

H14-180 NR 08/19/1998 33 -16 284 -- -- -- 9.3

H14-180 NR 11/04/1998 110 61 -- -- 13.9 74.3 20.9

H14-180 NR 12/01/1998 137 88 83.1 12.0 -- 7.8 31.2

H14-180 NR 12/16/1998 152 103 68.7 7.8 -- 99.9 15.5

H14-180 NR 01/07/1999 174 125 -- 4.3 -- 359 17.6

H14-180 NR 02/18/1999 216 167 -- 1.2 -- 190 14.3

H14-180 NR 05/12/1999 299 250 52.1 -- 0.18 90.9 29.4

H14-180 NR 09/02/1999 412 363 19.2 < 1.0 -- 16.3 44.3

H14-240 NR 07/15/1998 -2 -51 -- -- -- -- 23.0

H14-240 purge 08/11/1998 25 -24 6.4 1.0 -- -- 23.0

H14-240 NR 08/11/1998 25 -24 5.3 -- -- -- 6.5

H14-240 NR 09/17/1998 62 13 < 5.0 2.5 -- 1.45 35.5

H14-240 NR 09/30/1998 75 26 < 5.0 7.3 -- -- 29.4

H14-240 NR 10/20/1998 95 46 -- -- 32.8 1.52 118.3

H14-240 NR 11/04/1998 110 61 -- -- 11.9 16.1 22.8

H14-240 NR 11/18/1998 124 75 -- -- -- -- 7.8

H14-240 NR 12/01/1998 137 88 -- 6.9 -- -- 24.7

H14-240 purge 12/16/1998 152 103 7.5 6.5 -- 8.04 19.0

H14-240 NR 12/16/1998 152 103 17.3 4.7 -- 31.9 7.9

H14-240 NR 02/18/1999 216 167 -- < 1.0 -- 16.8 30.0

H14-240 NR 05/12/1999 299 250 9.3 -- -- -- 24.0

H14-240 NR 09/02/1999 412 363 < 5.0 < 1.0 -- 6.19 47.3

H14-300 NR 07/15/1998 -2 -51 -- -- -- -- 100.0

H14-300 NR 08/19/1998 33 -16 15.1 < 1.0 -- -- 27.0

H14-300 NR 08/31/1998 45 -4 43.4 -- -- -- 34.9

102 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B2. Concentrations of fluorescein, bromide, and sulfur hexafluoride in ground-water samples

 collected from the tracer array at West Branch Canal Creek, Aberdeen Proving Ground,

 Maryland, July 14, 1998 through September 14, 1999--Continued

Days after Bromide, Bromide,

Days after bromide ion- colori- Sulfur Water

fluorescein and SF6 Fluore- selective metric hexa- volume

Site Date injection, injection, scein electrode method fluoride removed

name Replicate sampled 07/17/1998 09/04/1998 (μg/L) (mg/L) (mg/L) (ng/L) (mL)

07/17/1998 09/04/1998

H14-300 1 10/19/1998 94 45 < 5.0 10.1 -- -- 84.6

H14-300 2 10/19/1998 94 45 < 5.0 12.0 -- -- --

H14-300 NR 11/18/1998 124 75 < 5.0 6.6 -- -- 28.8

H14-300 purge 12/16/1998 152 103 14.1 4.2 -- 22.0 26.4

H14-300 1 12/16/1998 152 103 24.8 3.1 -- 29.7 17.4

H14-300 2 12/16/1998 152 103 26.1 3.1 -- -- --

H14-300 NR 02/18/1999 216 167 -- 1.1 -- 92.2 48.8

H14-300 1 05/12/1999 299 250 < 5.0 -- 0.21 12.6 65.9

H14-300 2 05/12/1999 299 250 -- -- 0.21 -- --

H14-300 NR 06/22/1999 340 291 37.4 1.4 -- 3.42 25.6

H14-300 1 09/02/1999 412 363 < 5.0 < 1.0 -- 9.95 58.4

H14-300 2 09/02/1999 412 363 -- < 1.0 -- -- --

I06-285 NR 05/12/1999 299 250 -- -- -- -- 22.0

I06-285 NR 09/02/1999 412 363 < 5.0 < 1.0 -- 11.8 27.0

I07-112 NR 05/12/1999 299 250 < 5.0 -- -- 90.2 52.3

I07-112 1 09/03/1999 413 364 < 5.0 < 1.0 -- 6.48 73.3

I07-112 2 09/03/1999 413 364 < 5.0 < 1.0 -- -- --

J06-000 NR 05/12/1999 299 250 < 5.0 -- -- 19.9 60.4

J06-000 NR 06/22/1999 340 291 37.4 1.2 -- 1.55 49.0

J06-000 1 09/03/1999 413 364 < 5.0 < 1.0 -- 2.84 51.8

J06-000 2 09/03/1999 413 364 < 5.0 < 1.0 -- 0.86 --

J07-187 NR 05/12/1999 299 250 < 5.0 -- -- 20.2 67.0

J07-187 NR 09/02/1999 412 363 < 5.0 < 1.0 -- 3.29 49.6

103 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B3. Concentrations of volatile organic compounds in ground-water samples collected from

 the tracer array at West Branch Canal Creek, Aberdeen Proving Ground, Maryland,

 August 4, 1998 through September 13, 1999

[μg/L, micrograms per liter; NR, no replicate was collected for this sample; <, less than; - -, no data; E, estimated value]

1,1,2,2- 1,1,2- 1,2- 1,1- cis-1,2-

Tetra- Tri- Di- Di- Tetra- Tri- Dichloro- chloro- chloro- chloro- Chloro- chloro- chloro- chloroSite Date ethane ethane ethane ethane ethane ethene ethene ethene

name Replicate sampled (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L)

A00-300 NR 05/05/1999 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 

A06-300 NR 02/19/1999 < .5 < .5 0.7 < .5 < .5 < .5 < .5 0.6

A06-300 NR 05/05/1999 < .5 < .5 < .5 < .5 < .5 < .5 < .5 < .5 

A06-300 NR 09/13/1999 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 

A07-037 NR 02/19/1999 < .5 < .5 < .5 < .5 < .5 < .5 < .5 1.3

A07-142 NR 05/05/1999 < .5 < .5 < .5 < .5 < .5 < .5 < .5 < .5 

A07-247 NR 09/13/1999 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 

A13-300 NR 08/12/1998 < .5 0.5 < .5 < .5 < .5 < .5 0.5 < .5 

A14-127 NR 08/04/1998 0.6 < .5 < .5 < .5 < .5 < .5 < .5 1.0

A14-127 NR 10/21/1998 < .5 < .5 < .5 < .5 < .5 < .5 < .5 0.7

B07-202 NR 08/04/1998 < .5 < .5 1.0 < .5 < .5 < .5 0.5 1.7

B07-202 NR 05/05/1999 < .5 < .5 < .5 < .5 < .5 < .5 < .5 < .5 

B07-352 NR 05/05/1999 < .5 < .5 < .5 < .5 < .5 < .5 < .5 1.2

B14-037 NR 08/12/1998 < .5 < .5 < .5 < .5 < .5 < .5 0.8 3.3

B14-037 NR 09/09/1999 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 

B14-187 NR 02/19/1999 < .5 < .5 < .5 < .5 < .5 < .5 < .5 0.8

B14-337 NR 10/21/1998 3.1 2.5 1.2 < .5 < .5 < .5 1.5 6.3

B14-337 NR 02/19/1999 < .5 < .5 0.8 < .5 < .5 < .5 < .5 1.9

B14-337 NR 09/13/1999 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 

C07-007 NR 02/19/1999 < .5 < .5 < .5 4.9 5.3 < .5 < .5 24.0

C07-007 1 05/06/1999 < .5 < .5 < .5 < .5 < .5 < .5 < .5 24.9

C07-007 2 05/06/1999 < .5 < .5 < .5 < .5 < .5 < .5 < .5 26.5

C07-067 NR 09/13/1999 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 26.0

C07-127 NR 02/19/1999 < .5 < .5 < .5 < .5 < .5 < .5 < .5 25.7

C07-127 1 05/06/1999 < .5 < .5 < .5 < .5 < .5 < .5 < .5 28.0

C07-127 2 05/06/1999 < .5 < .5 < .5 < .5 < .5 < .5 < .5 20.9

C07-262 NR 09/13/1999 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 7.4

C14-172 NR 10/21/1998 < .5 1.1 < .5 < .5 < .5 < .5 2.1 E 16.2

C14-322 NR 08/05/1998 < .5 < .5 0.5 < .5 < .5 < .5 0.9 55.9

C14-322 NR 10/21/1998 < .5 < .5 0.5 < .5 < .5 < .5 1.9 E 34.3

D07-022 1 08/05/1998 < .5 < .5 < .5 < .5 < .5 < .5 0.8 80.8

D07-022 2 08/04/1998 < .5 < .5 < .5 < .5 < .5 < .5 0.9 51.4

D07-105 NR 02/19/1999 < .5 < .5 < .5 < .5 < .5 < .5 < .5 33.6

D07-165 NR 02/19/1999 < .5 < .5 < .5 < .5 < .5 < .5 < .5 48.1

D07-165 1 05/06/1999 < .5 < .5 < .5 < .5 < .5 < .5 < .5 40.9

 Chlorinated Ethanes Chlorinated

104 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
trans-1,2- 1,1- Di- Di- TriDi- Di- bromo- chloro- chlorochloro- chloro- Vinyl Chloro- Chloro- Bromo- chloro- difluoro- fluoroethene ethene chloride form methane methane methane methane Toluene methane Site

(μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) name

 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 0.8 < 0.5 < 0.5 < 0.5 < 0.5 A00-300

 0.6 < .5 < .5 < .5 < .5 0.7 < .5 < .5 < .5 < .5 A06-300

 < .5 < .5 < .5 < .5 < .5 < .5 < .5 < .5 < .5 < .5 A06-300

< 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 2.2 A06-300

 1.7 < .5 < .5 < .5 < .5 < .5 < .5 0.7 < .5 < .5 A07-037

 < .5 < .5 < .5 < .5 < .5 < .5 < .5 < .5 < .5 0.5 A07-142

< 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 3.2 A07-247

 < .5 < .5 < .5 < .5 1.0 0.6 < .5 0.9 < .5 3.1 A13-300

 0.7 < .5 < .5 < .5 < .5 < .5 < .5 < .5 < .5 2.8 A14-127

 0.6 < .5 0.6 < .5 < .5 < .5 < .5 < .5 < .5 < .5 A14-127

 < .5 < .5 5.3 < .5 < .5 < .5 < .5 < .5 0.9 1.0 B07-202

 < .5 < .5 2.4 < .5 < .5 < .5 < .5 < .5 < .5 0.6 B07-202

 < .5 < .5 24.4 < .5 < .5 < .5 < .5 < .5 < .5 < .5 B07-352

 2.4 < .5 15.7 < .5 < .5 0.8 < .5 < .5 1.4 1.1 B14-037

< 2.0 < 2.0 7.4 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 2.3 B14-037

 < .5 < .5 < .5 < .5 < .5 0.9 < .5 0.7 < .5 < .5 B14-187

 9.8 < .5 17.3 1.2 < .5 < .5 < .5 < .5 < .5 < .5 B14-337

 1.2 < .5 < .5 < .5 < .5 < .5 < .5 1.4 2.5 < .5 B14-337

< 2.0 < 2.0 4.6 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 2.6 B14-337

21.1 < .5 9.3 < .5 < .5 0.8 < .5 0.8 < .5 < .5 C07-007

22.1 < .5 87.9 < .5 < .5 < .5 < .5 < .5 < .5 < .5 C07-007

16.7 < .5 94.8 < .5 < .5 < .5 < .5 < .5 < .5 < .5 C07-007

 2.9 < 2.0 92.1 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 C07-067

17.5 < .5 19.8 < .5 < .5 0.8 < .5 0.8 < .5 < .5 C07-127

13.5 < .5 68.7 < .5 < .5 < .5 < .5 < .5 < .5 < .5 C07-127

12.9 < .5 47.0 < .5 < .5 < .5 < .5 < .5 < .5 < .5 C07-127

< 2.0 < 2.0 34.9 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 3.0 C07-262

 4.6 < .5 19.4 < .5 < .5 < .5 < .5 < .5 < .5 < .5 C14-172

74.5 < .5 86.4 < .5 < .5 < .5 < .5 < .5 < .5 0.8 C14-322

34.5 < .5 24.9 < .5 < .5 < .5 < .5 < .5 < .5 0.5 C14-322

126 < .5 66.5 < .5 < .5 < .5 < .5 < .5 < .5 0.9 D07-022

78.4 < .5 40.7 < .5 < .5 < .5 < .5 < .5 < .5 2.1 D07-022

39.2 < .5 33.6 < .5 < .5 0.6 < .5 < .5 < .5 < .5 D07-105

47.7 < .5 51.8 < .5 < .5 0.5 < .5 < .5 < .5 < .5 D07-165

32.6 < .5 92.6 < .5 < .5 < .5 < .5 < .5 < .5 < .5 D07-165

Ethenes Additional Volatile Organic Compounds 

105 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B3. Concentrations of volatile organic compounds in ground-water samples collected from

 the tracer array at West Branch Canal Creek, Aberdeen Proving Ground, Maryland,

 August 4, 1998 through September 13, 1999--Continued

1,1,2,2- 1,1,2- 1,2- 1,1- cis-1,2-

Tetra- Tri- Di- Di- Tetra- Tri- Dichloro- chloro- chloro- chloro- Chloro- chloro- chloro- chloroSite Date ethane ethane ethane ethane ethane ethene ethene ethene

name Replicate sampled (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L)

D07-165 2 05/06/1999 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 35.3

D14-052 NR 09/10/1999 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 62.4

D14-247 NR 09/10/1999 2.4 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 59.2

D14-352 NR 05/07/1999 < .5 < .5 < .5 < .5 < .5 < .5 < .5 7.2

D24-045 NR 09/03/1999 4.1 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 9.9 49.2

E07-000 NR 09/10/1999 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 80.5

E07-120 NR 05/07/1999 < .5 < .5 < .5 < .5 < .5 < .5 1.6 59.1

E07-307 NR 05/10/1999 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 43.9

E14-007 NR 10/20/1998 < .5 < .5 < .5 < .5 < .5 < .5 4.3 62.6

E14-082 NR 09/07/1999 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 86.9

E14-157 NR 08/05/1998 < .5 < .5 < .5 < .5 < .5 < .5 6.4 98.2

E14-217 NR 10/20/1998 1.1 < .5 < .5 < .5 < .5 < .5 2.5 80.6

E14-217 NR 02/16/1999 < .5 < .5 < .5 < .5 34.9 < .5 < .5 67.7

E14-277 NR 02/16/1999 < .5 < .5 < .5 < .5 23.6 < .5 < .5 45.8

E14-315 NR 08/12/1998 < .5 < .5 0.6 < .5 < .5 < .5 4.0 58.7

E14-315 NR 09/08/1999 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 5.8 82.5

F07-015 NR 02/16/1999 < .5 < .5 < .5 < .5 13.6 < .5 2.6 79.7

F07-015 NR 05/10/1999 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 2.7 63.4

F07-157 NR 02/16/1999 1.2 < .5 < .5 < .5 < .5 < .5 2.2 71.1

F07-157 NR 05/10/1999 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 2.6 56.6

F14-045 NR 08/05/1998 4.7 < .5 < .5 < .5 < .5 < .5 12.8 47.8

F14-135 NR 10/19/1998 < .5 < .5 < .5 < .5 < .5 < .5 18.8 62.7

F14-135 NR 09/07/1999 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 14.1 67.2

F14-210 NR 09/07/1999 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 2.5 77.0

F14-292 NR 08/04/1998 < .5 < .5 < .5 < .5 < .5 < .5 11.0 < .5 

F14-292 NR 09/07/1999 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 3.0 94.0

G14-022 NR 09/07/1999 22.3 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 13.9 48.3

G14-165 NR 08/04/1998 6.4 4.1 < .5 < .5 < .5 1.9 20.8 43.1

G14-225 NR 10/21/1998 < .5 < .5 < .5 < .5 < .5 < .5 4.4 29.6

G14-225 NR 02/18/1999 1.3 < .5 < .5 < .5 < .5 < .5 5.4 57.7

G14-225 NR 09/03/1999 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 9.6 54.3

G14-285 NR 02/18/1999 3.2 < .7 < .7 < .7 < .7 < .7 7.0 52.7

G14-330 NR 10/20/1998 20.2 2.4 < .5 < .5 < .5 1.4 18.7 46.5

G14-330 NR 09/03/1999 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 2.2 17.8 55.5

G18-180 NR 02/18/1999 130 4.6 < .5 < .5 < .5 1.8 13.5 29.0

 Chlorinated Ethanes Chlorinated

106 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
trans-1,2- 1,1- Di- Di- TriDi- Di- bromo- chloro- chlorochloro- chloro- Vinyl Chloro- Chloro- Bromo- chloro- difluoro- fluoroethene ethene chloride form methane methane methane methane Toluene methane Site

(μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) name

32.1 < 0.5 79.8 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 D07-165

57.7 < 2.0 111 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 2.8 D14-052

42.9 < 2.0 97.9 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 3.4 D14-247

 2.3 < .5 56.2 < .5 < .5 < .5 < .5 < .5 2.3 < .5 D14-352

126 < 2.0 65.5 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 D24-045

140 < 2.0 35.9 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 2.2 E07-000

128 < .5 37.6 < .5 < .5 < .5 < .5 < .5 < .5 < .5 E07-120

76.9 < 2.0 22.1 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 E07-307

143 < .5 43.2 < .5 < .5 < .5 < .5 1.0 < .5 4.0 E14-007

175 < 2.0 36.8 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 2.4 E14-082

210 < .5 20.5 < .5 < .5 < .5 < .5 < .5 < .5 3.3 E14-157

123 < .5 26.4 < .5 < .5 < .5 < .5 < .5 < .5 2.4 E14-217

95.7 < .5 63.4 < .5 < .5 1.6 < .5 < .5 < .5 < .5 E14-217

71.8 < .5 44.4 < .5 < .5 1.8 < .5 < .5 < .5 < .5 E14-277

151 < .5 17.6 < .5 < .5 < .5 < .5 < .5 0.6 0.9 E14-315

156 < 2.0 49.8 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 2.3 E14-315

173 < .5 23.7 < .5 1.2 1.3 < .5 < .5 < .5 0.6 F07-015

125 < 2.0 19.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 F07-015

157 < .5 24.9 < .5 < .5 1.3 < .5 < .5 < .5 < .5 F07-157

130 < 2.0 13.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 F07-157

196 < .5 7.4 < .5 < .5 < .5 < .5 < .5 < .5 1.0 F14-045

184 < .5 7.7 < .5 < .5 < .5 < .5 < .5 < .5 < .5 F14-135

192 < 2.0 12.2 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 2.3 F14-135

141 < 2.0 25.9 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 2.7 F14-210

154 < .5 7.8 < .5 < .5 < .5 < .5 < .5 < .5 0.7 F14-292

164 < 2.0 27.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 2.1 F14-292

137 < 2.0 11.3 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 2.9 G14-022

136 < .5 3.8 < .5 < .5 < .5 < .5 < .5 < .5 0.8 G14-165

51.2 < .5 1.7 < .5 < .5 < .5 < .5 < .5 < .5 < .5 G14-225

125 < .5 19.2 < .5 < .5 1.0 < .5 < .5 < .5 < .5 G14-225

121 < 2.0 13.7 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 3.0 G14-225

110 < .7 16.3 < .5 < .5 1.5 < .5 < .5 < .5 < .5 G14-285

146 < .5 6.6 < .5 < .5 < .5 < .5 < .5 < .5 1.9 G14-330

179 < 2.0 17.3 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 G14-330

54.4 < .5 4.0 < .5 0.7 0.9 < .5 < .5 < .5 < .5 G18-180

Ethenes Additional Volatile Organic Compounds 

107 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B3. Concentrations of volatile organic compounds in ground-water samples collected from

 the tracer array at West Branch Canal Creek, Aberdeen Proving Ground, Maryland,

 August 4, 1998 through September 13, 1999--Continued

1,1,2,2- 1,1,2- 1,2- 1,1- cis-1,2-

Tetra- Tri- Di- Di- Tetra- Tri- Dichloro- chloro- chloro- chloro- Chloro- chloro- chloro- chloroSite Date ethane ethane ethane ethane ethane ethene ethene ethene

name Replicate sampled (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L)

G18-180 NR 05/11/1999 122 3.2 < 2.0 < 2.0 < 2.0 < 2.0 19.8 17.3

G18-180 NR 09/02/1999 1.5 8.1 < 1.0 < 1.0 < 1.0 2.3 79.7 31.1

H07-030 NR 09/02/1999 69.4 4.7 < 1.0 < 1.0 < 1.0 2.0 21.4 43.6

H07-090 NR 09/02/1999 21.7 2.8 < 1.0 < 1.0 < 1.0 2.5 26.7 42.1

H07-150 NR 05/12/1999 75.6 < .5 < .5 < .5 < .5 < .5 42.6 101 

H07-150 NR 09/02/1999 141 6.5 < 1.0 < 1.0 < 1.0 2.0 19.5 35.4

H07-210 NR 05/12/1999 < .5 3.8 < .5 < .5 < .5 < .5 18.5 20.4

H07-210 NR 09/02/1999 44.2 3.7 < 1.0 < 1.0 < 1.0 2.1 18.0 31.4

H07-330 NR 09/02/1999 35.1 < 4.0 < 4.0 < 4.0 < 4.0 < 4.0 12.2 31.0

H14-000 NR 08/04/1998 248 7.4 < .5 < .5 < .5 2.2 26.3 17.9

H14-000 NR 09/02/1999 85.1 < 4.0 < 4.0 < 4.0 < 4.0 < 4.0 31.6 35.8

H14-060 NR 10/19/1998 203 8.7 < .5 < .5 < .5 2.5 21.6 E 20.6

H14-060 NR 02/18/1999 144 3.5 < .5 < .5 < .5 1.9 11.1 26.7

H14-060 NR 09/02/1999 138 5.4 < 1.0 < 1.0 < 1.0 2.6 21.9 23.8

H14-120 NR 09/02/1999 28.5 4.7 < 1.0 < 1.0 < 1.0 1.7 17.3 40.3

H14-180 NR 09/02/1999 145 8.2 < 1.0 < 1.0 < 1.0 1.5 17.7 28.8

H14-240 NR 09/02/1999 114 7.6 < 4.0 < 4.0 < 4.0 < 4.0 18.1 32.0

H14-300 1 10/19/1998 98.7 5.9 0.5 < .5 < .5 2.1 21.7 E 37.3

H14-300 2 10/19/1998 103 5.9 < .5 < .5 < .5 2.4 21.7 42.0

H14-300 NR 02/18/1999 114 2.9 < .5 < .5 < .5 1.9 10.8 38.4

H14-300 NR 09/02/1999 52.8 4.5 < 1.0 < 1.0 < 1.0 2.0 17.3 38.2

I06-285 NR 09/07/1999 211 4.8 < 2.0 < 2.0 < 2.0 < 2.0 11.9 11.9

I07-112 NR 05/13/1999 162 6.0 < .5 < .5 < .5 1.4 48.9 4.1

I07-112 NR 09/03/1999 236 5.4 < 2.0 < 2.0 < 2.0 < 2.0 22.5 6.3

J06-000 NR 09/03/1999 616 E 6.1 < 2.0 < 2.0 < 2.0 3.2 12.1 5.7

J07-187 NR 09/03/1999 262 6.6 < 2.0 < 2.0 < 2.0 < 2.0 42.8 3.2

WashBlank NR 09/02/1999 < 1.0 < 1.0 < 1.0 < 1.0 < 1.0 < 1.0 < 1.0 < 1.0 

WashBlank NR 05/05/1999 < .5 < .5 < .5 < .5 < .5 < .5 < .5 < .5 

WashBlank NR 05/06/1999 < .5 < .5 < .5 < .5 < .5 < .5 < .5 < .5 

WashBlank NR 05/07/1999 < .5 < .5 < .5 < .5 < .5 < .5 < .5 < .5 

WashBlank NR 05/10/1999 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 

WashBlank NR 05/10/1999 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 

WashBlank NR 05/11/1999 < .5 < .5 < .5 < .5 < .5 < .5 < .5 < .5 

WashBlank NR 05/12/1999 < .5 < .5 < .5 < .5 < .5 < .5 < .5 < .5 

Quality-Assurance Blanks

 Chlorinated Ethanes Chlorinated

108 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
trans-1,2- 1,1- Di- Di- TriDi- Di- bromo- chloro- chlorochloro- chloro- Vinyl Chloro- Chloro- Bromo- chloro- difluoro- fluoroethene ethene chloride form methane methane methane methane Toluene methane Site

(μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) (μg/L) name

33.1 < 2.0 4.2 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 G18-180

68.9 < 1.0 2.8 < 1.0 < 1.0 < 1.0 < 1.0 < 1.0 < 1.0 1.6 G18-180

125 < 1.0 7.0 < 1.0 < 1.0 < 1.0 < 1.0 < 1.0 < 1.0 2.2 H07-030

141 < 1.0 7.4 < 1.0 < 1.0 < 1.0 < 1.0 < 1.0 < 1.0 1.9 H07-090

147 0.5 11.6 < .5 9.3 4.3 < .5 < .5 < .5 1.4 H07-150

87.0 < 1.0 4.3 < 1.0 < 1.0 < 1.0 < 1.0 < 1.0 < 1.0 1.6 H07-150

58.0 < .5 3.0 < .5 < .5 < .5 < .5 < .5 < .5 < .5 H07-210

105 < 1.0 4.9 < 1.0 < 1.0 < 1.0 < 1.0 < 1.0 < 1.0 1.6 H07-210

99.7 < 4.0 7.3 < 4.0 < 4.0 < 4.0 < 4.0 < 4.0 < 4.0 6.1 H07-330

25.2 < .5 0.5 1.0 < .5 < .5 < .5 < .5 < .5 0.7 H14-000

78.4 < 4.0 5.3 < 4.0 < 4.0 < 4.0 < 4.0 < 4.0 < 4.0 6.7 H14-000

62.1 < .5 1.1 < .5 < .5 < .5 < .5 < .5 < .5 < .5 H14-060

77.9 < .5 5.1 < .5 < .5 1.5 0.9 < .5 < .5 < .5 H14-060

92.0 < 1.0 3.1 < 1.0 < 1.0 < 1.0 < 1.0 < 1.0 < 1.0 1.5 H14-060

121 < 1.0 5.7 < 1.0 < 1.0 < 1.0 < 1.0 < 1.0 < 1.0 1.1 H14-120

40.9 < 1.0 1.7 < 1.0 < 1.0 < 1.0 < 1.0 < 1.0 < 1.0 1.5 H14-180

90.9 < 4.0 5.6 < 4.0 < 4.0 < 4.0 < 4.0 < 4.0 < 4.0 5.6 H14-240

89.8 < .5 2.3 < .5 < .5 < .5 0.9 < .5 < .5 < .5 H14-300

99.9 < .5 2.7 < .5 < .5 < .5 1.2 < .5 < .5 < .5 H14-300

72.7 < .5 5.4 < .5 < .5 1.2 < .5 < .5 < .5 < .5 H14-300

106 < 1.0 5.3 < 1.0 < 1.0 < 1.0 < 1.0 < 1.0 < 1.0 1.8 H14-300

19.7 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 I07-285

 5.4 < .5 0.6 < .5 < .5 < .5 < .5 < .5 < .5 < .5 I07-112

 2.9 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 I07-112

 6.1 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 2.1 J06-000

< 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 J07-187

< 1.0 < 1.0 < 1.0 < 1.0 < 1.0 < 1.0 < 1.0 < 1.0 < 1.0 1.3 WashBlank

 < .5 < .5 < .5 < .5 < .5 < .5 < .5 < .5 < .5 < .5 WashBlank

 < .5 < .5 < .5 < .5 < .5 < .5 < .5 < .5 < .5 < .5 WashBlank

 < .5 < .5 < .5 < .5 < .5 < .5 < .5 < .5 < .5 < .5 WashBlank

< 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 WashBlank

< 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 < 2.0 WashBlank

 < .5 < .5 < .5 < .5 < .5 < .5 < .5 < .5 < .5 < .5 WashBlank

 < .5 < .5 < .5 < .5 < .5 < .5 < .5 < .5 < .5 < .5 WashBlank

Ethenes Additional Volatile Organic Compounds 

109 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B4. Concentrations of methane in ground-water samples collected from the

 tracer array at West Branch Canal Creek, Aberdeen Proving Ground,

 Maryland, August 1998 and September 1999

[μg/L, micrograms per liter; <, less than]

Methane Methane

Site name (μg/L) Site name (μg/L)

A13-300 2,450 A00-300 2,880 

A14-127 4,530 A14-015 2,000 

B14-037 1,830 A14-127 1,740 

C14-322 750 B07-202 3,040 

D07-022 191 B07-292 2,880 

D07-277 198 C14-270 2,560 

E14-157 <77.6 C14-322 2,780 

E14-315 121 D14-352 3,780 

F14-045 <78.3 D24-045 2,440 

F14-292 <75.0 E07-120 342 

G14-165 <79.1 E07-180 356 

H14-000 <78.3 E14-277 518 

H14-180 <60.8 F07-315 213 

F14-135 135 

G07-060 100 

G07-195 109 

H00-000 <49.7

H07-270 <78.0

H14-060 <76.8

H14-180 <77.3

H14-240 <78.6

I06-285 <72.3

J06-000 <77.0

J07-187 <77.5

Wash Blank <76.1

Wash Blank <79.4

Wash Blank <76.7

August 1998 September 1999

 110 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD
Appendix B5. Concentrations of fluorescein, bromide, and sulfur hexafluoride in quality-assurance blanks

 collected during the tracer test at West Branch Canal Creek, Aberdeen Proving Ground,

 Maryland, July 15, 1998 through October 7, 1999

[SF6, sulfur hexafluoride; μg/L, micrograms per liter; mg/L, milligrams per liter; ng/L, nanograms per liter; mL, milliliters; --, not analyzed;

<, less than]

Days after Bromide, Bromide,

Days after bromide ion- colori- Sulfur

fluorescein and SF6 Fluore- selective metric hexaSample Date injection, injection, scein electrode method fluoride

type sampled 07/17/1998 09/04/1998 (μg/L) (mg/L) (mg/L) (ng/L)

Ambient Blank 07/15/1998 -2 -51 < 5.0 -- -- --

Ambient Blank 07/17/1998 0 -49 < 5.0 -- -- --

Wash Blank 08/19/1998 33 -16 < 5.0 < 1.0 -- --

Wash Blank 08/19/1998 33 -16 < 5.0 -- -- --

Ambient Blank 08/20/1998 34 -15 < 5.0 -- -- --

Wash Blank 08/20/1998 34 -15 < 5.0 -- -- --

Wash Blank 09/17/1998 62 13 < 5.0 < 1.0 -- < 0.01

Wash Blank 09/17/1998 62 13 < 5.0 < 1.0 0.01 < 0.01

Ambient Blank 09/18/1998 63 14 < 5.0 < 1.0 -- --

Wash Blank 09/18/1998 63 14 < 5.0 < 1.0 -- --

Wash Blank 09/23/1998 68 19 -- < 1.0 -- --

Wash Blank 09/30/1998 75 26 < 5.0 < 1.0 -- --

Wash Blank 09/30/1998 75 26 < 5.0 < 1.0 0.10 --

Wash Blank 10/01/1998 76 27 < 5.0 < 1.0 -- --

Wash Blank 10/09/1998 84 35 -- < 1.0 -- --

Wash Blank 10/09/1998 84 35 -- < 1.0 -- --

Wash Blank 10/19/1998 94 45 < 5.0 < 1.0 -- --

Wash Blank 10/19/1998 94 45 < 5.0 < 1.0 0.02 --

Ambient Blank 10/20/1998 95 46 -- < 1.0 -- --

Wash Blank 10/20/1998 95 46 < 5.0 < 1.0 -- --

Wash Blank 10/20/1998 95 46 < 5.0 -- -- --

Wash Blank 10/21/1998 96 47 < 5.0 < 1.0 -- --

Ambient Blank 11/04/1998 110 61 < 5.0 -- -- --

Wash Blank 11/05/1998 111 62 < 5.0 < 1.0 -- --

Ambient Blank 11/09/1998 115 66 < 5.0 < 1.0 -- --

Wash Blank 11/09/1998 115 66 -- < 1.0 -- --

Wash Blank 11/19/1998 125 76 -- < 1.0 -- --

Air Blank 11/18/1998 130 81 -- -- -- 1.52

Air Blank 11/19/1998 129 80 -- -- -- <1.20

Ambient Blank 12/02/1998 138 89 < 5.0 -- -- --

Appendixes 111
Appendix B5. Concentrations of fluorescein, bromide, and sulfur hexafluoride in quality-assurance blanks

 collected during the tracer test at West Branch Canal Creek, Aberdeen Proving Ground,

 Maryland, July 15, 1998 through October 7, 1999--Continued

Days after Bromide, Bromide,

Days after bromide ion- colori- Sulfur

fluorescein and SF6 Fluore- selective metric hexaSample Date injection, injection, scein electrode method fluoride

type sampled 07/17/1998 09/04/1998 (μg/L) (mg/L) (mg/L) (ng/L)

Wash Blank 12/02/1998 138 89 < 5.0 < 1.0 -- --

Wash Blank 12/02/1998 138 89 < 5.0 < 1.0 -- --

Wash Blank 12/02/1998 138 89 < 5.0 < 1.0 -- --

Wash Blank 12/02/1998 138 89 < 5.0 < 1.0 -- --

Ambient Blank 12/07/1998 143 94 < 5.0 < 1.0 -- --

Ambient Blank 12/07/1998 143 94 < 5.0 < 1.0 -- --

Ambient Blank 12/07/1998 143 94 < 5.0 < 1.0 -- --

Wash Blank 12/16/1998 152 103 < 5.0 < 1.0 -- --

Wash Blank 12/16/1998 152 103 < 5.0 < 1.0 -- --

Wash Blank 12/16/1998 152 103 < 5.0 < 1.0 -- --

Wash Blank 12/16/1998 152 103 < 5.0 < 1.0 -- --

Wash Blank 12/17/1998 153 104 < 5.0 < 1.0 -- --

Wash Blank 12/17/1998 153 104 < 5.0 < 1.0 -- --

Wash Blank 01/07/1999 174 125 -- < 1.0 -- --

Wash Blank 02/25/1999 223 174 -- < 1.0 -- < 0.08

Wash Blank 02/25/1999 223 174 -- < 1.0 -- --

Wash Blank 05/11/1999 298 249 -- -- 0.05 --

Wash Blank 05/13/1999 300 251 -- -- 0.05 --

Wash Blank 05/13/1999 300 251 -- -- 0.10 --

Wash Blank 05/13/1999 300 251 -- -- 0.33 --

Wash Blank 05/17/1999 304 255 < 5.0 -- -- --

Wash Blank 05/17/1999 304 255 < 5.0 -- -- --

Wash Blank 05/17/1999 304 255 < 5.0 -- -- --

Wash Blank 06/22/1999 304 255 < 5.0 < 1.0 -- --

Wash Blank 06/22/1999 304 255 < 5.0 < 1.0 -- --

Wash Blank 09/08/1999 418 369 -- -- -- 0.74

Wash Blank 09/10/1999 420 371 -- -- -- 0.92

Wash Blank 09/13/1999 423 374 < 5.0 -- -- < .55

Wash Blank 09/13/1999 423 374 < 5.0 < 1.0 -- < .96

Wash Blank 09/14/1999 424 375 -- -- -- 0.72

Appendixes 111
Appendixes 113 

Appendix C. Sample calculation of sulfur hexafluoride concentrations in ground-water samples 

1. Determine the partial pressure of the SF6 standard used at the Reston Chlorofluorocarbon Laboratory, 

PSF6RCL: 

PSF6RCL = PSF6STD H (PRCL / PSTD), (1) 

where: 

PRCL = atmospheric pressure at the Reston Chlorofluorocarbon Laboratory, 0.987 atm 

PSTD = atmospheric pressure at standard conditions (0°C dry air at sea level), 1 atm 

PSF6STD = the partial pressure of 0.104 ppt (parts per trillion, vol/vol) SF6 calibration gas at 

 standard conditions, 1.04H10-10 atm 

PSF6RCL = 1.03H10-10 atm (1) 

2. Determine the number of moles of SF6 calibration gas injected during calibration, n: 

 Solve the ideal gas law, PV=nRT, for n: 

 n = PV/RT, (2) 

 where: 

 P = PSF6RCL from equation 1, 1.026H10-10 atm 

 V = volume of the sample loop, 3.015H10-4 L 

 R = ideal gas constant, 8.206H10-2 Latm/molK 

 T = room temperature, 298.15 K 

 n = 1.265H10-15 mol (2) 

3. Determine the concentration of SF6 in the diluted headspace of the environmental sample 

 (SF6-TS1A analyzed on January 5, 2001), CDHSP: 

 CDHSP = A H RFC3.015, (3) 

where: 

A = instrument response measured as the area of the SF6 peak for the environmental sample, 

 42,610 

RFC3.015 = instrument response factor for the 0.3015-mL sample loop calculated as the 

 concentration of the calibration standard divided by the area of the SF6 peak, 

 averaged for several calibration runs, 4.768H10-3 

 CDHSP = 203.15 ppt (3) 
114 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD 

Appendix C. Sample calculation of sulfur hexafluoride concentrations in ground-water samples—Continued 

4. Determine the concentration of undiluted SF6 in the headspace of the 25-mL serum vial, CHSP: 

 CHSP = CDHSP H (Vdv / Va) (4) 

 where: 

 CDHSP = CDHSP from equation 3, 203.15 ppt 

Vdv = volume of the dilution vessel, 292.8 mL 

Va = volume of the aliquot of headspace withdrawn from the serum vial, 1.00 mL 

CHSP = 59,481 ppt (4) 

5. Determine the number of moles of SF6 in the diluted of headspace of the environmental sample, 

 nDHSP: 

 nDHSP = A H RFN3.015 (5) 

where: 

A = the instrument response (area) used in equation 3; 42,610 

RFN3.015 = the instrument response factor for the 0.3015-mL sample loop calculated as 

 the number of moles of the calibration standard (from equation 2) divided by 

 the area of the SF6 peak , averaged for several calibration runs, 5.798H10-20 

 nDHSP = 2.470H10-15 mol (5) 

6. Determine the number of moles of SF6 in the 1.00-mL aliquot of undiluted headspace of the 

 environmental sample, nAHSP: 

 nAHSP = nDHSP H (Vdv / Va) (6) 

where: 

nDHSP = nDHSP from equation 4, 2.470H10-15 mol 

Vdv = the volume of the dilution vessel, 292.8 mL 

Va = the volume of the aliquot of headspace withdrawn from the serum vial, 1.00 mL 

nAHSP = 7.258H10-13 mol (6) 
Appendixes 115 

Appendix C. Sample calculation of sulfur hexafluoride concentrations in ground-water samples—Continued

7. Determine the total number of moles of SF6 in the entire volume of headspace in the 25-mL serum 

 vial of environmental sample, nHSP: 

nHSP = nAHSP H VHSP (7) 

 where: 

 nHSP = nAHSP from equation 5, 7.258H10-13 mol 

 VHSP = the volume of headspace in the 25-mL serum vial, 22.485 mL 

nHSP = 1.632H10-11 mol (7)

8. Determine the Henry’s law constant at 25.0°C (298.15 K), KH: 

 KH = 2.4396H10-4 mol/Latm (Wilhelm and others, 1977) (8) 

9. Calculate the concentration of SF6 in the aqueous phase in the 25-mL serum vial, CAQ: 

Solve Henry’s Law, KH = CAQ / CHSP, for CAQ: 

CAQ = KH H CHSP (9) 

 where: 

 KH = KH from equation 8, 2.4396H10-4 mol/Latm 

 CHSP = CHSP from equation 4, 5.948H104

 ppt or 5.948H10-8 atm 

CAQ = 1.451H10-11 mol/L (9) 

10. Determine the number of moles of SF6 in the aqueous phase in the 25-mL serum vial, nAQ: 

 nAQ = CAQ H VAQ (10) 

 where: 

 CAQ = CAQ from equation 9, 1.451H10-11 mol/L 

 VAQ = volume of aqueous phase in 25-mL serum vial, 2.634 mL or 2.634H103 L 

 nAQ = 3.822H10-14 mol (10) 
116 Ground-Water Tracer Test, West Branch Canal Creek, Aberdeen Proving Ground, MD 

Appendix C. Sample calculation of sulfur hexafluoride concentrations in ground-water samples—Continued

11. Determine the total number of moles of SF6 in both phases in the 25-mL serum vial, nT: 

 nT = nHSP + nAQ (11) 

 where: 

 nHSP = nHSP from equation 7, 1.632H10-11 mol 

nAQ = nAQ from equation 10, 3.822H10-14 mol 

nT = 1.636H10-11 mol (11) 

12. Determine the original concentration of SF6 in the ground-water sample at the time of sample 

 collection, prior to partitioning, C: 

CM = nT / VAQ (12) 

 where: 

nT = nT from equation 11, 1.636H10-11 mol

VAQ = volume of ground-water sample, also used in equation 10, 2.634H103 L 

CM = 6.210H10-9 mol/L (12) 

13. Convert the concentration of SF6 in the ground-water sample to units of ng/L: 

C = CM H Mm H (1,000,000,000 ng / 1 g) (13) 

 where: 

 CM = CM from equation 12, 6.210H10-9 mol/L 

 MM = the molar mass of SF6, 146.1 g/mol 

 C = 907 ng/L (13) 

 (Result is rounded based upon the least precise measurement used throughout the equations.)