Water at Naval Weapons Industrial 

Reserve Plant, Dallas, Texas 

Water-Resources Investigations Report 03–4046 

U.S. Department of the Interior 

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

U.S. Geological Survey 

Oxidation-Reduction Processes in Ground 

Water at Naval Weapons Industrial 

Reserve Plant, Dallas, Texas 

By S.A. Jones, Christopher L. Braun, and Roger W. Lee 

U.S. GEOLOGICAL SURVEY 

Water-Resources Investigations Report 03–4046 

In cooperation with the Southern Division Naval Facilities 

Engineering Command 

Austin, Texas 

2003 
U.S. DEPARTMENT OF THE INTERIOR 

Gale A. Norton, Secretary 

U.S. GEOLOGICAL SURVEY 

Charles G. Groat, Director 

Any use of trade, product, or firm names is for 

descriptive purposes only and does not imply 

endorsement by the U.S. Government. 

For additional information write to 

District Chief 

U.S. Geological Survey 

8027 Exchange Dr. 

Austin, TX 78754–4733 

E-mail: dc_tx@usgs.gov 

Copies of this report can be purchased from 

U.S. Geological Survey 

Branch of Information Services 

Box 25286 

Denver, CO 80225–0286 

E-mail: infoservices@usgs.gov 

ii 
CONTENTS

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


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


Purpose and Scope .................................................................................................................................................... 1


Description of Study Area ........................................................................................................................................ 2


Hydrogeology ........................................................................................................................................................... 2


Sampling and Analytical Methods and Results ................................................................................................................... 2


Volatile Organic Compounds .................................................................................................................................... 2


Dissolved Oxygen ..................................................................................................................................................... 6


Nitrate and Nitrite ..................................................................................................................................................... 6


Ferrous Iron and Total Iron ....................................................................................................................................... 6


Sulfate and Sulfide .................................................................................................................................................... 6


Dissolved Hydrogen ................................................................................................................................................. 6


Total Organic Carbon ............................................................................................................................................... 7


Oxidation-Reduction Processes ........................................................................................................................................... 7


Volatile Organic Compounds .................................................................................................................................... 8


Dissolved Oxygen ..................................................................................................................................................... 8


Nitrate and Nitrite ..................................................................................................................................................... 8


Ferrous Iron and Total Iron ....................................................................................................................................... 14


Sulfate and Sulfide .................................................................................................................................................... 14


Dissolved Hydrogen ................................................................................................................................................. 14


Total Organic Carbon ............................................................................................................................................... 14


Screening Results ..................................................................................................................................................... 14


Summary .............................................................................................................................................................................. 22


References Cited .................................................................................................................................................................. 22


Appendix—Data .................................................................................................................................................................. 31


FIGURES 

1.	 Map showing location of study area, wells sampled, and lithologic cross section 1–1' at the Naval


Weapons Industrial Reserve Plant, Dallas, Texas ................................................................................................. 3


2.	 Lithologic section 1–1' at the Naval Weapons Industrial Reserve Plant, Dallas, Texas ....................................... 4


3.	 Map showing water-level altitudes in shallow alluvial deposits at the Naval Weapons Industrial Reserve 


Plant, Dallas, Texas, March 1998 ......................................................................................................................... 5


4.	 Graph showing dissolved hydrogen concentrations associated with oxidation-reduction processes in


ground water ......................................................................................................................................................... 7


5–16. Maps showing:


5.	 Trichloroethene concentrations from wells screened in the upper or in the upper and middle parts 


of the shallow alluvial deposits at the Naval Weapons Industrial Reserve Plant, Dallas, Texas,


September 1997 ......................................................................................................................................... 9


6.	 cis-1,2-Dichloroethene concentrations from wells screened in the upper or in the upper and middle


parts of the shallow alluvial deposits at the Naval Weapons Industrial Reserve Plant, Dallas, Texas,


September 1997 ......................................................................................................................................... 10


7.	 Vinyl chloride concentrations from wells screened in the upper or in the upper and middle parts


of the shallow alluvial deposits at the Naval Weapons Industrial Reserve Plant, Dallas, Texas,


September 1997 ......................................................................................................................................... 11


8. 	 Dissolved oxygen concentrations from wells screened in the upper or in the upper and middle 


parts of the shallow alluvial deposits at the Naval Weapons Industrial Reserve Plant, Dallas, 


Texas, September 1997 .............................................................................................................................. 12


CONTENTS iii 
9.	 Dissolved oxygen concentrations from wells screened in the upper or in the upper and middle 

parts of the shallow alluvial deposits at the Naval Weapons Industrial Reserve Plant, Dallas, 

Texas, March 1998 ..................................................................................................................................... 13 

10.	 Nitrite concentrations from wells screened in the upper or in the upper and middle parts of the 

shallow alluvial deposits at the Naval Weapons Industrial Reserve Plant, Dallas, Texas, 

September 1997 .......................................................................................................................................... 15 

11.	 Ferrous iron concentrations from wells screened in the upper or in the upper and middle parts 

of the shallow alluvial deposits at the Naval Weapons Industrial Reserve Plant, Dallas, Texas, 

September 1997 .......................................................................................................................................... 16 

12.	 Ferrous iron concentrations from wells screened in the upper or in the upper and middle parts of 

the shallow alluvial deposits at the Naval Weapons Industrial Reserve Plant, Dallas, Texas, March 

1998 ............................................................................................................................................................ 17 

13.	 Sulfide concentrations from wells screened in the upper or in the upper and middle parts of the 

shallow alluvial deposits at the Naval Weapons Industrial Reserve Plant, Dallas, Texas, 

September 1997 .......................................................................................................................................... 18 

14.	 Sulfide concentrations from wells screened in the upper or in the upper and middle parts of the 

shallow alluvial deposits at the Naval Weapons Industrial Reserve Plant, Dallas, Texas, 

March 1998 ................................................................................................................................................ 19 

15.	 Dissolved hydrogen concentrations from wells screened in the upper or in the upper and middle 

parts of the shallow alluvial deposits and indicated oxidation-reduction processes at the Naval 

Weapons Industrial Reserve Plant, Dallas, Texas, September 1997 .......................................................... 20 

16.	 Dissolved hydrogen concentrations from wells screened in the upper or in the upper and middle 

parts of the shallow alluvial deposits and indicated oxidation-reduction processes at the Naval 

Weapons Industrial Reserve Plant, Dallas, Texas, March 1998 ................................................................. 21 

TABLES 

1.	 Well information and sampling dates for wells sampled at the Naval Weapons Industrial Reserve Plant, 

Dallas, Texas ......................................................................................................................................................... 24 

2.	 Selected constituents, methods, and procedures used to evaluate oxidation-reduction processes in 

ground water at the Naval Weapons Industrial Reserve Plant, Dallas, Texas ....................................................... 25 

3.	 Chemical results for selected volatile organic compounds from wells sampled at the Naval Weapons 

Industrial Reserve Plant, Dallas, Texas ................................................................................................................. 26 

4.	 Selected field and laboratory data from wells sampled at the Naval Weapons Industrial Reserve Plant, 

Dallas, Texas ......................................................................................................................................................... 28 

5.	 Mean first-order decay rates and computed half-lives for trichloroethene, dichloroethene, and vinyl 

chloride under five oxidation-reduction conditions .............................................................................................. 30 

ABBREVIATIONS AND VERTICAL DATUM 

°C, degree Celsius μg/L, microgram per liter


ft, foot mg/L, milligram per liter


ft/ft, foot per foot mL, milliliter


ft/mi, foot per mile mL/min, milliliter per minute


gal/min, gallon per minute nm, nanometer


in., inch nM, nanomolar


Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929 (NGVD of 1929). 

iv 
Oxidation-Reduction Processes in Ground 

Water at Naval Weapons Industrial 

Reserve Plant, Dallas, Texas 

By S.A. Jones, Christopher L. Braun, and Roger W. Lee 

Abstract 

Concentrations of trichloroethene in ground 

water at the Naval Weapons Industrial Reserve 

Plant in Dallas, Texas, indicate three source areas 

of chlorinated solvents—building 1, building 6, 

and an off-site source west of the facility. The 

presence of daughter products of reductive dechlorination of trichloroethene, which were not used at 

the facility, south and southwest of the source areas 

are evidence that reductive dechlorination is occurring. In places south of the source areas, dissolved 

oxygen concentrations indicated that reduction 

of oxygen could be the dominant process, particularly south of building 6; but elevated dissolved 

oxygen concentrations south of building 6 might be 

caused by a leaking water or sewer pipe. The nitrite 

data indicate that denitrification is occurring in 

places; however, dissolved hydrogen concentrations indicate that iron reduction is the dominant 

process south of building 6. The distributions of 

ferrous iron indicate that iron reduction is occurring in places south-southwest of buildings 6 and 1; 

dissolved hydrogen concentrations generally support the interpretation that iron reduction is the 

dominant process in those places. The generally 

low concentrations of sulfide indicate that sulfate 

reduction is not a key process in most sampled 

areas, an interpretation that is supported by dissolved hydrogen concentrations. Ferrous iron 

and dissolved hydrogen concentrations indicate 

that ferric iron reduction is the primary oxidationreduction process. Application of mean first-order 

decay rates in iron-reducing conditions for trichloroethene, dichloroethene, and vinyl chloride 

yielded half-lives for those solvents of 231, 347, 

and 2.67 days, respectively. Decay rates, and thus 

half-lives, at the facility are expected to be similar 

to those computed. A weighted scoring method to 

indicate sites where reductive dechlorination might 

be likely to occur indicated strong evidence for 

anaerobic biodegradation of chlorinated solvents 

at six sites. In general, scores were highest for 

samples collected on the northeast side of the 

facility. 

INTRODUCTION 

The Naval Weapons Industrial Reserve Plant 

(NWIRP) in Dallas, Tex., has been in operation since 

1941. The 314-acre NWIRP facility, which currently 

(2002) is operated by Vought Aircraft Industries Inc., 

manufactures military and commercial aircraft and aircraft components. Manufacturing processes associated 

with the facility’s operation include metal machining 

and treating; fabrication, painting, and stripping of aircraft or aircraft parts; and aircraft renovation. These 

processes use petroleum products and solvents and 

create wastes that include oils and fuels, chlorinated solvents, construction debris, and metals. The chlorinated 

ethenes trichloroethene (TCE), 1,2-cis-dichloroethene 

(cis-DCE), 1,2-trans-dichloroethene (trans-DCE), and 

vinyl chloride (VC) as well as chlorinated ethanes have 

been detected at various locations in the shallow alluvial 

deposits at the site (EnSafe/Allen & Hoshall, 1994, 

1996). Multiple ground-water contamination plumes 

exist in the shallow alluvial deposits at the site because 

of several source areas (EnSafe/Allen & Hoshall, 1996). 

Presently, the facility is operating under a Resource 

Conservation and Recovery Act Part B permit. 

Purpose and Scope 

This report describes the oxidation-reduction 

(redox) processes in ground water at NWIRP on the 

basis of data collected and analyzed by the U.S. Geological Survey (USGS) and private companies. The USGS 

Abstract 1 
collected ground-water samples from 51 wells in 

September 1997 and from 57 wells in March 1998 

(table 1, at end of report). The USGS analyzed the September 1997 samples in the field for specific conductance, pH, temperature, dissolved oxygen (DO), ferrous 

iron, total iron, sulfide, carbon dioxide, methane, and 

hydrogen; the March 1998 samples were analyzed in the 

field for specific conductance, pH, temperature, bicarbonate alkalinity, and selected volatile organic compounds (VOCs). The USGS sent September 1997 

samples to Quanterra Laboratories for analysis of bicarbonate alkalinity; sulfate; chloride; fluoride; silica; 

nitrate, nitrate plus nitrite, and ammonia nitrogen; 

orthophosphate phosphorus; boron; and total organic 

carbon (TOC). EnSafe/Allen & Hoshall (hereinafter, 

EnSafe), a consultant to the Navy, collected groundwater samples from about 150 wells and had them analyzed by a contract laboratory for selected VOCs and 

metals in September 1997. 

Description of Study Area 

The study area is in the southwestern corner of 

the city of Dallas (fig. 1). NWIRP is located north of 

Cottonwood Bay, which is a part of Mountain Creek 

Lake. The climate in north-central Texas is characterized by long, hot summers and short, mild winters. The 

average annual precipitation in north-central Texas is 

32 in., with most of the precipitation occurring during 

spring and fall. Land-surface altitudes at NWIRP range 

from about 500 to 460 ft above sea level west to east and 

north to south (fig. 1). Stormwater runoff drains into a 

manmade channel of Mountain Creek Lake locally 

referred to as Cottonwood Bay. 

Hydrogeology 

NWIRP is located on shallow alluvial deposits 

about 40 to 80 ft above the present-day flood plain 

of the West Fork Trinity River. The alluvial deposits 

range from about 10 to 75 ft thick and overlie the 

Cretaceous-age Eagle Ford Shale (EnSafe/Allen & 

Hoshall, 1994). A previous study used borehole geophysical logging and cone penetrometer data to map 

the relative permeability of the shallow alluvial deposits 

at the NWIRP site (Anaya and others, 2000; Braun and 

others, 2000). In that study, the shallow alluvial deposits 

were divided into upper, middle, and lower parts of 

roughly equal thickness. A series of intersecting sections was developed (Anaya and others, 2000, pls. 1–3), 

which indicates that the shallow alluvial deposits occur 

as lenticular, interfingering beds of sand, silt, and 

clay atop the shale bedrock. The relative permeability of 

the beds is gradational and depends on the amounts of 

sand (most permeable), silt, and clay (least permeable) 

present (fig. 2). The shallow alluvial deposits have been 

replaced by permeable fill material in places. 

Ground water generally moves downgradient 

from a recharge area in the northwestern part of the 

study area through the shallow alluvial deposits underlying NWIRP toward the principal discharge area to the 

southeast, Cottonwood Bay (fig. 3). Lateral flow gradients steepen from about 25 ft/mi in the north to about 

75 ft/mi in the south. Downward vertical gradients (as 

much as 0.5 ft/ft under natural conditions) indicate that 

some water migrates between upper and lower parts of 

the shallow alluvial deposits. Downward migration is 

greatest in the northern part of the study area. Upward 

gradients near the east lagoon, west lagoon, and along 

the northern shore of Cottonwood Bay (fig. 3) indicate 

diffuse ground-water discharge to these topographically 

low areas (Barker and Braun, 2000). Specific-capacity 

tests at more than 20 wells produced 1.5 to 2.0 gal/min 

of sustained flow from each well (EnSafe/Allen & 

Hoshall, 1994). About 76 percent of NWIRP ground 

cover is impervious; most of the pervious (grassy) areas 

are near the south end of the facility adjacent to Cottonwood Bay (Barker and Braun, 2000). 

SAMPLING AND ANALYTICAL METHODS 

AND RESULTS 

Unfiltered ground-water samples were collected 

from wells using a peristaltic pump. Wells were pumped 

for at least 30 minutes before sampling. Constituents 

listed in table 2 (at end of report) were analyzed in the 

field or in the laboratory asindicated. The appendix lists 

selected additional data collected at NWIRP. 

Decontamination procedures consisted of equipment cleaning and rinsing between wells using deionized water, methanol (as needed), and a dilute detergent 

solution (as needed). Equipment cleaned included glass 

bubblers for headspace analyses, monitoring probes, 

and glassware used with the HACH colorimeters. New 

Teflon and Tygon tubing was used for each well. 

Volatile Organic Compounds 

VOC samples were collected by EnSafe in 

September 1997 and analyzed by a contract laboratory 

using the U.S. Environmental Protection Agency (1999) 

method 8260. The USGS collected samples and 

2 Oxidation-Reduction Processes in Ground Water at Naval Weapons Industrial Reserve Plant, Dallas, Texas 
490

480

460 460

470

500

470

490

480

COTTONWOOD 

 BAY (MOUNTAIN CREEK LAKE) 

D

WP–BG–6 

96o59'10" 96o59' 96o58'50" 96o58'40" 96o58'30" 96o58'20" 

To Naval Air Station 

32o44'40" 

EXPLA

Building 6 Building 1 

DWP–S2–D

W1 D

WP–S2–16 

D

W 1 

P–10–DW6 

D

WP–L2–DW1 

DWP–S2–2 

Gr

D

WP–10–6 

and Prairie

1 Ave. D

WP–L2–8 

D

WP–S2–D

W2 

D

WP–L2–DW2 

DWP–S2–5 

D

WP–L2–5 

DWP–OFF–5 

D

WP–S2–18 500

DWP–BG–4–3 

DWP–L2–4 

DWP–S1–7 

DWP–10–D

W1 DWP–10–1 

D

WP–10–2 32

DWP–BG–4 o44'30" 

D

WP–S1–D

W1 D

WP–10–DW4 

SE 14th St.

DWP–S1–4 

DWP–L2–1 

D

WP–S1–17 

DWP–S2–11 

DWP–L2–16 

DWP–BG–4–6 

D

WP–S1–DW2 

DWP–S1–18 DWP–4

D

WP–S1–10 

D

WP–S1–5 

DWP–128–1 

DWP–S1–11 

DWP–4–8 

DWP–5–12 

DWP–L1–5 

D

WP–4–5 

1'

D

WP–4–4 

DWP–S5–10 

D

WP–5–13 

DWP–4–2 

DWP–1–13 32o44'20" 

D

WP–4–9 

D

WP–7–6 

DWP–1–9 

D

WP–4–10 East GRAND lagoon 

West 

D

WP–4–14 

PRAIRIE 

DWP–BG–7 

lagoon 

DWP–OFF–10 

D

WP–OFF–11 

D

WP–BG–10 

32o44'10" 

Skyline Drive DWP–BG–8 

SAMPLING AND ANALYTICAL METHODS AND RESULTS

DWP–DBG–3 

D

WP–OFF–12 

DWP–OFF–14 

0 250 500 750 1,000 FEET 

3Figur

e 1. L

ocation of study area, wells s

a

m

pled, and lithologic cross secti

on 1–1' at the Naval W

e

apons Industrial R

eserve 
1 1'

EXPLANA

High 

PERMEABILITY

Oxidation-Reduction Processes in Ground Water at Naval Weapons Industrial Reserve Plant, Dallas, Texas 510 480 

DWP–L2–DW1 

DWP–L2–5 

DWP–L2–1 

DWP–L2–16 

DWP–L1–5 

DWP–S1–5

DWP–S1–18

DWP–L2–4

DWP–L2–DW2 

DWP–L2–8 

DWP-128-1 

470 460 

500 

Low 

490 

ALTITUDE, IN FEET ABOVE NGVD OF 1929 

Well identificat number 450 

440 

430 

420 

Bottom of borehole 

410 400 

Location of section shown in figure 1 0 200 400 FEET Note: Distance 

not to scale VERTICAL SCALE GREATLY EXAGGERATED 

Figur

e 2. Lithologic s

ection 1–1' at the Naval Weapons Industrial Res

erve Plant, Dallas, T

e

x

as (

modified fro

m Anaya and o

oth

ers, 2000). 

4 
460

480 460

470

500

470

485

480

475

470

COTTONWOOD BAY (MOUNTAIN CREEK LAKE) 490 460

460

465

96o59'10" 96o59' 96o58'50" 96o58'40" 96o58'30" 96o58'20" 

EXPLAN

480 

32o44'40" 

490 Building 6 Building 1	 

Grand Prairie  Ave. 

500 

32o44'30" 

SE 14th St. 

32o44'20" 

East 

GRAND lagoon West 

lagoon PRAIRIE 

0 250 

32o44'10" 

Skyline Drive 

SAMPLING AND ANALYTICAL METHODS AND RESULTS

Modified from Barker and Braun, 2000, figure 20 (water levels), figure 2 (topography) 

Figure 3. Water-level altitudes in shallow alluvial deposits at the Naval Weapons Industrial Reserve Plant, Dallas, Texas, 

 5
analyzed them with a field gas chromatograph (GC) in 

March 1998. The field GC results are considered semiquantitative but compare relatively well with the laboratory data. Samples analyzed in the field were collected 

in a 40-mL vial. At each well, 20 mL of sample was collected in the vial. The vial was placed in a water bath 

and brought to 30 °C, the vial was shaken vigorously, 

and a quantity of headspace was removed with a gastight syringe and injected into a Photovac 10S50 GC 

calibrated for TCE, cis-DCE, trans-DCE, and VC. 

Results of both laboratory and field GC analyses are 

listed in table 3 (at end of report). 

Dissolved Oxygen 

The concentration of DO was measured in the 

field using the indigo carmine method (Gilbert and 

others, 1982). Ground water was pumped through 

Teflon tubing (having a low oxygen-diffusion 

coefficient) into a sampling cell. An ampoule was 

placed into the overflowing sample cell, and the tip 

was broken to draw a fixed size of sample into the 

ampoule. The tip was covered to ensure against atmospheric contamination of the sample. The ampoule 

was inverted carefully several times to mix the colordeveloping reagents with the sample and allowed to 

react for 2 minutes. The ampoule then was placed in a 

CHEMetrics VVR photometer, and the DO concentration was recorded. The method detection limit for DO 

was 0.05 mg/L. Results of DO analyses are listed in 

table 4 (at end of report). 

Nitrate and Nitrite 

Nitrate as nitrogen and nitrate plus nitrite as nitrogen samples were collected by the USGS in September 

1997 and analyzed by Quanterra Laboratories using 

methods 300.0 and 353.2 (U.S. Environmental Protection Agency, 1993 and 1983, respectively). Nitrite concentrations are listed in table 4. Nitrate and nitrate plus 

nitrite concentrations are listed in the appendix. 

Ferrous Iron and Total Iron 

The concentration of ferrous iron was measured 

using the HACH phenanthroline powder pillow method 

(255), and the concentration of total iron was measured 

using the HACH FerroVer colorimetric method (265) 

(HACH Co., 1989). For ferrous and total iron, 25 mL of 

ground water was poured into each of four colorimetric 

vials. The ferrous and total iron reagents, respectively, 

were then added to the first and second sample vials; the 

vials were filled with sample and allowed to react for 3 

minutes. The third and fourth sample vials (the blanks) 

were placed in a DR2000 spectrophotometer, and the 

zero concentration was set at a 510-nm wavelength. 

The blank vials were removed, and each ground-watersample vial was placed in the spectrophotometer; after 

3 minutes, concentrations of ferrous and total iron, in 

milligrams per liter, were recorded. The lower and 

upper method detection limits for ferrous and total iron 

using the methods and instrumentation listed above 

were 0.01 and 3 mg/L, respectively. If a sample concentration was greater than 3 mg/L, a 50-percent dilution of 

the sample with deionized (DI) water was used, and the 

sample was re-analyzed. Several of the ferrous iron 

samples collected in September 1997 became cloudy 

during color development, causing incorrect readings 

on the spectrophotometer. The concentrations reported 

for cloudy ferrous samples in table 4 are qualified. 

Sulfate and Sulfide 

Sulfate samples were collected by the USGS in 

September 1997 and analyzed by Quanterra Laboratories (appendix). The concentration of sulfide was 

measured using the HACH methylene blue colorimetric 

method (690) (HACH Co., 1989). For sulfide a 25 mL 

sample of ground water was collected into a sample cell, 

and a second sample cell was filled with DI water. One 

mL of sulfide reagent 1 was added to each sample cell 

and swirled to mix. After mixing, 1 mL of sulfide 

reagent 2 was immediately added to each vial and 

swirled to mix. The methylene blue color was allowed 

to develop for 5 minutes. After 5 minutes, the blank 

sample was placed into the DR2000 spectrophotometer, 

and the zero concentration was set at a 665-nm wavelength. The blank sample cell was removed, the sample 

cell containing the ground-water sample was placed in 

the colorimeter, and the concentration of sulfide, in 

milligrams per liter, was recorded. The lower and 

upper method detection limits for sulfide using the 

method and instrumentation listed above were 0.001 

and 0.6 mg/L, respectively. Sulfide concentrations are 

listed in table 4. 

Dissolved Hydrogen 

The concentration of dissolved hydrogen was 

measured using the “bubble strip” method (Chapelle, 

1996) in which ground water was pumped through a 

glass bubbler fitted with a septum. Once flow was 

6 Oxidation-Reduction Processes in Ground Water at Naval Weapons Industrial Reserve Plant, Dallas, Texas 
established at about 500 mL/min and the bubbler was 

filled and free of gas bubbles, 20 mL of hydrogen-free 

helium was injected. The induced headspace was 

allowed to equilibrate with the flowing ground water for 

about 30 minutes. After 30 minutes, 10 mL of the headspace gas was withdrawn using a 10-mL gas-tight 

syringe with valve; after 5 minutes, a second 10-mL 

sample of the headspace gas was withdrawn into a second syringe. Both samples were analyzed for hydrogen 

using a reducing gas detector chromatograph (Trace 

Analytical, 1997) calibrated with standard gases. Dissolved hydrogen concentrations listed in table 4 are an 

average of the two measurements. 

Total Organic Carbon 

TOC samples were collected by the USGS in 

September 1997 and analyzed by Quanterra Laboratories using method 9060 (U.S. Environmental Protection 

Agency, 1999). TOC concentrations are listed in the 

appendix. 

OXIDATION-REDUCTION PROCESSES 

The most common redox processes in ground 

water are the reduction of oxygen, nitrate (denitrification), ferric iron, sulfate, and carbon dioxide (methanogenesis). The reduced chemical species produced 

during redox reactions are used in biological processes 

that facilitate reductive dechlorination of chlorinated 

solvents. The efficiency of the reductive dechlorination 

process varies depending on redox conditions. Dechlocarbon dioxide as electron acceptors. Dissolved hydrogen concentrations can be used to identify which redox 

process is dominant at a particular location (fig. 4). 

Of the reducing environments noted above, methanogenesis consumes the least hydrogen. Hydrogen concentrations in ground water are expected to be greater 

than 5.0 nM under methanogenic conditions. If sulfate 

reduction is the dominant redox process, hydrogen concentrations will range from 1.0 to 4.0 nM. If ferric iron 

reduction is the dominant redox process, hydrogen 

concentrations will range from 0.2 to 0.8 nM. If denitrification is the dominant redox process, hydrogen 

concentrations will be less than 0.1 nM (Chapelle, 

1996). 

In addition to dissolved hydrogen concentrations, 

concentrations of the reduced species nitrite, ferrous 

iron, sulfide, and methane are useful for identifying 

redox processes. In some cases, determination of dissolved hydrogen concentrations might not be necessary; 

but when concentrations of the reduced species produce 

conflicting information, hydrogen concentrations are 

critical. For example, ferrous iron, sulfide, and methane 

can be transported by ground-water flow in the subsurface. The constituents could be produced upgradient 

and transported to the well where the measurement is 

made. To determine which redox process is dominant at 

the well where the measurement is made, dissolved 

hydrogen concentrations are needed. 

6 

rination of the more highly chlorinated solvents 

(tetrachloroethene [PCE], TCE, and DCE) can occur 

in mildly reducing environments, such as those associated with ferric iron reduction, but dechlorination is 

more efficient in sulfate-reducing or methanogenic 

conditions (Chapelle, 1996; Suarez and Rifai, 1999). 

VC typically requires a more strongly reducing environment such as methanogenesis to degrade but also will 

degrade under iron-reducing conditions and under 

aerobic conditions (Bradley and Chapelle, 1998). Table 

5 (at end of report) lists mean first-order decay rates 

for TCE, DCE, and VC under five redox conditions and 

the computed half-lives associated with the respective 

decay rates. In general, the larger the first-order decay 

DISSOLVED HYDROGEN CONCENTRATION, NANOMOLAR 5 

4 

3 

2 

1 

0 

1.0 – 4.0 

Greater than 5.0 

Less than 0.1 

0.2 – 0.8 

rate, the more efficient the reductive dechlorination DENITRIFICATION IRON REDUCTION SULFATE METHANOGENESIS 

REDUCTION 

process. 

Hydrogen is produced during anaerobic microbial Figure 4. Dissolved hydrogen concentrations 

metabolism. It is then used by respirative microorgan- associated with oxidation-reduction processes in 

isms that most commonly use ferric iron, sulfate, or ground water (modified from Chapelle, 1996). 

OXIDATION-REDUCTION PROCESSES 7 
Volatile Organic Compounds 

The concentrations of chlorinated solvents at 

NWIRP are controlled partially by reductive dechlorination, which in turn is controlled by redox processes in 

ground water. Under anaerobic conditions, reductive 

dechlorination of TCE proceeds as follows: 

TCE => cis-DCE + Cl => VC + 2Cl => ethene + 3Cl. (1) 

The presence of cis-DCE and VC usually indicates that reductive dechlorination of TCE is occurring. 

Normally cis-DCE is not used as a primary solvent. It is 

more commonly a product of the degradation of a more 

highly chlorinated compound. Neither cis-DCE nor VC 

was used at NWIRP (EnSafe/Allen & Hoshall, 1996). 

Therefore, the presence of these daughter products indicates that TCE is degrading. The presence of VC indicates that cis-DCE is degrading; but it also indicates that 

complete reductive dechlorination (eq. 1) might not be 

occurring in all areas of the facility. Figures 5, 6, and 7 

show the distributions of TCE, cis-DCE, and VC, 

respectively, in shallow ground water at NWIRP. These 

maps were created using data collected by EnSafe in 

September 1997 from about 150 wells. Most of the 

wells were screened in the upper part of the shallow 

alluvial deposits only; some were screened in the upper 

and middle parts; and a few were screened in the middle 

and (or) lower part. The high dilution factors used during laboratory analyses might have masked smaller concentrations of VC in some samples. Concentrations less 

than the method detection limit were not used in the 

generation of the concentration maps. 

The three primary source areas for chlorinated 

solvents in ground water at NWIRP are building 1, 

building 6, and an off-site source west of the facility. 

Concentrations of chlorinated solvents are highest near 

these areas (figs. 5, 6, and 7). Each of three plumes (one 

from each source area) has distinctly different chemistry 

with respect to chlorinated solvents. The plume originating from the building 1 area contains chlorinated 

ethenes and chlorinated ethanes including trichloroethane and 1,1-dichloroethane (appendix). The plume 

originating from the building 6 area primarily is composed of chlorinated ethenes. The source area of building 6 generally has a larger TCE/cis-DCE ratio than 

other areas of NWIRP. Larger ratios generally indicate 

that reductive dechlorination is less efficient than in 

areas where the ratio is smaller. The plume that originates off-site is the only plume in which PCE concentrations are greater than 10 μg/L. Wells DWP–OFF–5, 

DWP–BG–4, and DWP–BG–4–3 had PCE concentrations of 170, 98, and 43 μg/L, respectively (appendix). 

Dissolved Oxygen 

DO concentrations greater than about 0.50 mg/L 

indicate that oxygen reduction is the dominant microbial process (U.S. Environmental Protection Agency, 

1998). Oxygen reduction occurs as follows: 

CH2O + O2 => CO2 + H2O. (2) 

Ground water is unconfined in shallow alluvial 

deposits at NWIRP, and both anaerobic (DO less than 

0.50 mg/L) and aerobic (DO greater than 0.50 mg/L) 

(U.S. Environmental Protection Agency, 1998) groundwater conditions were observed at various locations. 

DO concentrations tended to be less than 1.00 mg/L but 

were as high as 2.29 mg/L (table 4); the mean concentration was 0.55 mg/L for samples collected in September 1997 and 0.35 mg/L for samples collected in March 

1998. Several wells sampled south of building 6, a primary source area, had DO concentrations greater than 

1.00 mg/L during both sampling events (figs. 8, 9). 

These concentrations are higher than would be expected 

near the source of a plume. One possible explanation is 

a leaking underground water or sewer pipe. Barker and 

Braun (2000) indicated that near the area where DO 

concentrations are larger, recharge was added to a 

ground-water-flow model of NWIRP to simulate an 

additional source of water other than infiltration of precipitation. The authors believe the observed DO concentrations more likely are related to an inflow of water 

rather than oxygen reduction. In general, the distribution of DO was similar for September 1997 and March 

1998. 

Nitrate and Nitrite 

Nitrate is reduced to nitrite as follows: 

CH2O + 2NO3

-

 => 2NO2

-

 + CO2 + H2O. (3) 

Because of this process, an increase in nitrite 

would be expected where nitrate reduction is occurring. 

The mean concentration of nitrite in those samples 

containing nitrite collected in September 1997 was 

0.36 mg/L. The nitrite data indicate that nitrate 

reduction is occurring in places. Nitrite concentrations 

equal to or greater than 0.5 mg/L were detected in six 

wells (screened in the upper or in the upper and middle 

parts of the shallow alluvial deposits)—DWP–4–2, 

DWP–4–4, DWP–4–9, DWP–L2–1, DWP–L2–16, and 

8 Oxidation-Reduction Processes in Ground Water at Naval Weapons Industrial Reserve Plant, Dallas, Texas 
CO

 alluvial deposits 

TTONW

AY (MOUNTAIN CREEK LAKE) B OOD 

96o59'10" 96o59' 96o58'50" 96o58'40" 96o58'30" 96o58'20" 

EXPLA

T

32o44'40" c

m

Building 6 Building 1 1

1

Grand Prairie 1 Ave. 

1

32o44'30" 1 

SE 14th St. N

Wloa

32o44'20" 

East 

GRAND lagoon West 

Area missing lagoon  upper part of the shallow

 PRAIRIE 

32o44'10" 

Skyline Drive 

0 250 

OXIDATION-REDUCTION PROCESSES

Figure 5. Trichloroethene concentrations from wells screened in the upper or in the upper and middle parts of the shallow Naval Weapons Industrial Reserve Plant, Dallas, Texas, September 1997. (Concentration datapoints provided by EnSafe/A

9 
CO

alluvial 

AIN CREEK LAKE)

deposits 

TTONW

AY (MOUNT

B

OOD 

10 Oxidation-Reduction Processes in Ground Water at Naval Weapons Industrial Reserve Plant, Dallas, Texas 96o59'10" 96o59' 96o58'50" 96o58'40" 96o58'30" 96o58'20" EXPLA

c

32o44'40" c

m

1

1

Grand Prairie Building 6 Building 1 1 Ave. 1 

N

32o44'30" 

SE 14th St.

Wla

32o44'20" 

East 

GRAND lagoon West 

Area missing lagoon  upper part of the shallo

w

 PRAIRIE 

32o44'10" 

Skyline Drive 

0 250 

Figur

e 6. cis-1,2-Dichloro

ethene concentrati

ons fro

m wells screened in the upper or in the upper and mid

dle parts of the s

at the Naval W

e

apons Industrial R

eserv

e Plant, Dallas, T

exas, September 1997. (

Concentration datapoints provide

d by En
COTTONWOOD BAY (MOUNTAIN CREEK LAKE) alluvial deposits 

96o59'10" 96o59' 96o58'50" 96o58'40" 96o58'30" 96o58'20" 

EXPLA

Vc

32o44'40" 

m

1

1

Building 6 Building 1 

Grand Prairie 1 Ave. 

1 

N

32o44'30" 

SE 14th St. W

loa

32o44'20" 

East 

GRAND lagoon West 

Area missing lagoon  upper part of the shallow

 PRAIRIE 

32o44'10" 

Skyline Drive 

0 25

OXIDATION-REDUCTION PROCESSES 

Figure 7. Vinyl chloride concentrations from wells screened in the upper or in the upper and middle parts of the shallow alNaval Weapons Industrial Reserve Plant, Dallas, Texas, September 1997. (Concentration datapoints provided by EnSafe/A

11 
12 Oxidation-Reduction Processes in Ground Water at Naval Weapons Industrial Reserve Plant, Dallas, Texas Building 6 Building 1 GRAND PRAIRIE

SE 14th St.

Grand Prairie Ave.

Skyline Drive

0 

EX

0.17 0.22

0.24

0.22

0.54

0.54

1.55

1.80

0.35

0.27

0.38

1.50

1.75

0.23

2.29

1.47

0.20

0.27

0.32 0.65

0.22

0.27

0.32

0.30 0.22

0.24

0.36

0.27

0.69

0.27

1.47

0.77

96o 96 58'20" o 96 58'30" o 96 58'40" o 96 58'50" o 96 59' o59'10"

32o44'40"

32o44'30"

32o44'20"

32o44'10"

COTTONWOOD BAY (MOUNTAIN CREEK LAKE)

West

lagoon

East

lagoon

Figure 8. Dissolved oxygen concentrations from wells screened in the upper or in the upper and middle parts of the shallow 

Naval Weapons Industrial Reserve Plant, Dallas, Texas, September 1997.
OXIDATION-REDUCTION PROCESSES 13 Figure 9. Dissolved oxygen concentrations from wells screened in the upper or in the upper and middle parts of the shallow 

Naval Weapons Industrial Reserve Plant, Dallas, Texas, March 1998.

EX

ND

Building 6 Building 1

GRAND PRAIRIE

SE 14th St.

Grand Prairie Ave.

Skyline Drive

0.11 0.16

0.15

0.230.21

0.30

0.06

0.85

1.16

0.19

0.12

2.21

0.34

1.80

0.10

0.10

0.25

0.03

0.57

0.03

0.23

ND

0.09 0.05

0.06 0.24

0.08

0.15

0.22

1.55

0.09

0.04

1.92

0.66

0.07

0 

96o 96 58'20" o 96 58'30" o 96 58'40" o 96 58'50" o 96 59' o59'10"

32o44'40"

32o44'30"

32o44'20"

32o44'10" COTTONWOOD BAY (MOUNTAIN CREEK LAKE)

West

lagoon

East

lagoon
DWP–L2–5 (fig. 10). The three “L2” wells are located 

south of building 6, where nitrite (and nitrate) concentrations were larger than in most other areas of NWIRP. 

However, dissolved hydrogen concentrations indicate 

that the dominant redox process south of building 6 is 

ferric iron reduction. 

Nitrate concentrations in uncontaminated shallow 

ground water generally are less than 2 mg/L (U.S. Geological Survey, 1999). Nitrate concentrations in wells 

DWP–L2–1, DWP–L2–16, and DWP–L2–5 were 25, 

14.8, and 8.4 mg/L, respectively (appendix). The presence of nitrate at these relatively high concentrations, in 

addition to the larger DO concentrations, supports the 

possibility that an underground sewer pipe might be 

leaking south of building 6. 

Ferrous Iron and Total Iron 

Ferric iron is reduced to ferrous iron by the 

reaction 

- CH2O + 4Fe(OH)3 + 7H+ => 4Fe+2 + HCO3 

+ 10H2O. (4) 

Because of this process, an increase in ferrous 

iron concentration is expected where ferric iron reduction is occurring. Concentrations greater than about 

1.00 mg/L indicate that iron reduction is probable (U.S. 

Environmental Protection Agency, 1993). The concentrations of ferrous iron in September 1997 and March 

1998 (figs. 11, 12) indicate places where iron reduction 

probably is occurring, assuming that sulfide production 

from sulfate reduction is negligible. 

Sulfate and Sulfide 

Sulfate is reduced to hydrogen sulfide during 

sulfate reduction as follows: 

2CH2O + SO4

-2 => HCO3-

 + HS- + CO2 + H2O. (5) 

Because of this process, an increase in sulfide 

is expected where sulfate reduction is occurring, 

assuming that locally, sulfide production exceeds iron 

reduction. The generally low concentrations of sulfide 

(figs. 13, 14) indicate that sulfate reduction is not a 

key process in the parts of the shallow alluvial deposits 

sampled. 

Dissolved Hydrogen 

Dissolved hydrogen concentrations (figs. 15, 16) 

indicate that ferric iron reduction is the most common 

redox process at the sampled wells. Dissolved hydrogen 

concentrations ranged from less than the method detection limit to more than 2,000 nM (table 4). Extremely 

large concentrations of hydrogen (greater than 50 nM) 

can be produced in newly installed wells, in wells 

pumped with direct-current-driven submersible pumps, 

and in wells with iron casing or screens (Chapelle and 

others, 1997). The relatively large hydrogen concentrations measured in this study are attributed to the installation of new wells. Excluding hydrogen concentrations 

greater than 50 nM, the median concentration of samples containing dissolved hydrogen was 0.53 nM for 

samples collected in September 1997 and 0.45 nM for 

samples collected in March 1998. These concentrations 

are typical indicators of ferric iron reduction (fig. 4). 

Suarez and Rifai (1999) compiled a database of 

mean first-order decay rates for chlorinated solvents 

(table 5) from field and laboratory studies. From the 

table, the mean first-order decay rate associated with 

iron reduction for TCE is 0.003 day-1. Using the general 

equation for first-order decay, 1n (0.5) = -kt1/2, where k 

is the decay rate, and t1/2 is the half-life, a mean half-life 

of 231 days is computed for TCE. The computed mean 

half-life for DCE in iron reducing conditions is 347 

days and for VC is 2.7 days. Decay constants were not 

computed for NWIRP, but it is expected that decay rates 

at NWIRP would be similar to the decay rates thus 

computed. 

Total Organic Carbon 

Analytical screening criteria were developed by 

USEPA as part of a weighted scoring method to indicate 

where reductive dechlorination might be likely to occur 

(U.S. Environmental Protection Agency, 1998). (See 

next section.) The criterion for TOC is that 20 mg/L is 

required for reductive dechlorination to proceed efficiently. TOC concentrations at NWIRP ranged from 

less than the method detection limit to 11.9 mg/L in 

samples collected in September 1997 (appendix). 

Results of VOC analysesfrom September 1997 samples 

showed very few wells with anthropogenic carbon 

compounds such as benzene, toluene, ethylbenzene, or 

xylene. The lack of a sufficient organic carbon source, 

whether naturally occurring or anthropogenic, can be a 

limiting factor for efficient reductive dechlorination 

(Suarez and Rifai, 1999). 

Screening Results 

The USEPA has developed a weighted scoring 

method to indicate sites where reductive dechlorination 

14 Oxidation-Reduction Processes in Ground Water at Naval Weapons Industrial Reserve Plant, Dallas, Texas 
OXIDATION-REDUCTION PROCESSES 15 Figure 10. Nitrite concentrations from wells screened in the upper or in the upper and middle parts of the shallow alluvial d

Weapons Industrial Reserve Plant, Dallas, Texas, September 1997.

Building 6 Building 1

GRAND PRAIRIE

SE 14th St.

Grand Prairie Ave.

Skyline Drive

0 

EXP

0.1

0.4

0.3

1.1

0.1

0.3

1.1 0.8 ND

0.4

ND ND

ND ND

ND

0.2

0.5

0.2

0.6

0.5

ND

ND

1.1

0.3

ND

0.4

ND

0.2

0.2

0.1

0.1

ND

ND

ND

96o 96 58'20" o 96 58'30" o 96 58'40" o 96 58'50" o 96 59' o59'10"

32o44'40"

32o44'30"

32o44'20"

32o44'10" COTTONWOOD BAY (MOUNTAIN CREEK LAKE)

West

lagoon

East

lagoon
16 Oxidation-Reduction Processes in Ground Water at Naval Weapons Industrial Reserve Plant, Dallas, Texas Building 6 Building 1 GRAND PRAIRIE

SE 14th St.

Grand Prairie Ave.

Skyline Drive

0 2

<1.00 <1.00

<1.00

ND

1.44

ND

<1.00

<1.00

<1.00

ND

<1.00

<1.00

<1.00

<1.00

<1.00

<1.00

2.66 <1.00

<1.00

<1.00 <1.00

3.04

1.56

4.94 <1.00

5.02

<1.00

ND

1.80

<1.00

ND

ND

< indic

<1.00

<1.00

3

2

1

EXPLA

96o 96 58'20" o 96 58'30" o 96 58'40" o 96 58'50" o 96 59' o59'10"

32o44'40"

32o44'30"

32o44'20"

32o44'10"

COTTONWOOD BAY (MOUNTAIN CREEK LAKE)

West

lagoon

East

lagoon

Figure 11. Ferrous iron concentrations from wells screened in the upper or in the upper and middle parts of the shallow al

Naval Weapons Industrial Reserve Plant, Dallas, Texas, September 1997.
OXIDATION-REDUCTION PROCESSES 17 Figure 12. Ferrous iron concentrations from wells screened in the upper or in the upper and middle parts of the shallow al

Naval Weapons Industrial Reserve Plant, Dallas, Texas, March 1998.

Building 6 Building 1

GRAND PRAIRIE

SE 14th St.

Grand Prairie Ave.

Skyline Drive

0 250 

EXPLA

ND

< indi

ND ND

ND

ND

ND

1.13

<1.00

<1.00

<1.00

<1.00

<1.00

ND

ND

ND

<1.00

<1.00

<1.00

<1.00

2.75

<1.00 ND

4.10

1.96

3.80 <1.00

<1.00

4.16 ND

4.76

<1.00 <1.00

2.56

<1.00

ND

<1.00

96o 96 58'20" o 96 58'30" o 96 58'40" o 96 58'50" o 96 59' o59'10"

32o44'40"

32o44'30"

32o44'20"

32o44'10" COTTONWOOD BAY (MOUNTAIN CREEK LAKE)

West

lagoon

East

lagoon
18 Oxidation-Reduction Processes in Ground Water at Naval Weapons Industrial Reserve Plant, Dallas, Texas 

Figure 13. Sulfide concentrations from wells screened in the upper or in the upper and middle parts of the shallow alluvial 

Weapons Industrial Reserve Plant, Dallas, Texas, September 1997. 

Building 6 Building 1

GRAND PRAIRIE

SE 14th St.

Grand Prairie Ave.

Skyline Drive

0 

ND

0.003

0.002

0.005

0.002

ND

0.005

0.033

0.007

0.009

ND

ND 0.002

0.008

0.002

0.003

0.005

0.005

0.003 0.017

0.002 0.001

0.002

0.001

ND

ND

ND ND

ND

ND ND

0.004

0.006

EXP

ND

96o 96 58'20" o 96 58'30" o 96 58'40" o 96 58'50" o 96 59' o59'10"

32o44'40"

32o44'30"

32o44'20"

32o44'10"

COTTONWOOD 

 BAY (MOUNTAIN CREEK LAKE)

West

lagoon

East

lagoon
OXIDATION-REDUCTION PROCESSES 19 Figure 14. Sulfide concentrations from wells screened in the upper or in the upper and middle parts of the shallow alluvial 

Weapons Industrial Reserve Plant, Dallas, Texas, March 1998. 

Building 6 Building 1

GRAND PRAIRIE

SE 14th St.

Grand Prairie Ave.

Skyline Drive

0 

0.001

0.021

0.012

ND

0.002

0.005

0.011

0.006

0.001

ND

ND

0.003 ND

0.003

ND

0.011

0.009

0.003

0.012

ND ND

0.002

0.004

0.005

ND

0.082 ND

ND

ND

0.006

0.016

ND

0.006

0.001

ND

EXPL

ND

96o 96 58'20" o 96 58'30" o 96 58'40" o 96 58'50" o 96 59' o59'10"

32o44'40"

32o44'30"

32o44'20"

32o44'10"

COTTONWOOD BAY (MOUNTAIN CREEK LAKE)

West

lagoon

East

lagoon
20 Oxidation-Reduction Processes in Ground Water at Naval Weapons Industrial Reserve Plant, Dallas, Texas Building 6 Building 1 GRAND PRAIRIE

SE 14th St.

Grand Prairie Ave.

Skyline Drive

0 2

ND ND

0.3

ND

0.7

0.5

0.1

0.1

ND

ND

ND

2.7

0.4

0.2

0.1

0.1

ND 0.2

0.3

ND

0.2

0.2

0.8 ND

ND 1.8

0.2

ND

0.2

0.5

1.1 0.1

1.1

1 

0 

0 

N

N

EXPLA

Hnin

ND

96o 96 58'20" o 96 58'30" o 96 58'40" o 96 58'50" o 96 59' o59'10"

32o44'40"

32o44'30"

32o44'20"

32o44'10"

COTTONWOOD BAY (MOUNTAIN CREEK LAKE)

West

lagoon

East

lagoon

Figure 15. Dissolved hydrogen concentrations from wells screened in the upper or in the upper and middle parts of the shand indicated oxidation-reduction processes at the Naval Weapons Industrial Reserve Plant, Dallas, Texas, September 199
OXIDATION-REDUCTION PROCESSES 21

Building 6 Building 1

GRAND PRAIRIE

SE 14th St.

Grand Prairie Ave.

Skyline Drive

1 

0 

0 

N

NTcpc

EXPLA

Hnin

ND

96o 96 58'20" o 96 58'30" o 96 58'40" o 96 58'50" o 96 59' o59'10"

32o44'40"

32o44'30"

32o44'20"

32o44'10"

ND ND

0.1

ND

0.4

ND

0.2

ND

0.1

ND

ND

0.5

0.7

0.2

0.2

ND ND

ND

0.3

0.3

2.1

ND

0.1 0.1

0.2 0.5

0.5 0.3

0.2

ND

0.1

0.2

0.9

ND

ND

0 2

COTTONWOOD BAY (MOUNTAIN CREEK LAKE)

West

lagoon

East

lagoon

Figure 16. Dissolved hydrogen concentrations from wells screened in the upper or in the upper and middle parts of the shand indicated oxidation-reduction processes at the Naval Weapons Industrial Reserve Plant, Dallas, Texas, March 1998.
might be likely to occur (U.S. Environmental Protection 

Agency, 1998). Monitored natural attenuation (MNA) 

scores for sites (wells) are computed on the basis of concentrations of selected constituents. An MNA score of 0 

to 5 of a possible 49 indicates inadequate evidence for 

anaerobic biodegradation of chlorinated solvents; a 

score of 6 to 14 indicates limited evidence for anaerobic 

biodegradation of chlorinated solvents; a score of 15 to 

20 indicates adequate evidence for anaerobic biodegradation of chlorinated solvents; and a score greater than 

20 indicates strong evidence for anaerobic biodegradation of chlorinated solvents. The work at NWIRP was 

done before the USEPA released its list of screening 

constituents; therefore not all the screening constituents 

were analyzed for this study. To score the ground-water 

samples collected from NWIRP in September 1997, 

a possible total score of 30 rather than 49 was used. 

Accordingly, the scoring also was modified—an MNA 

score of 0 to 3 indicated inadequate evidence for anaerobic biodegradation of chlorinated solvents; a score 

of 4 to 9 indicated limited evidence for anaerobic biodegradation of chlorinated solvents; a score of 10 to 12 

indicated adequate evidence for anaerobic biodegradation of chlorinated solvents; and a score greater than 

12 indicated strong evidence for anaerobic biodegradation of chlorinated solvents. The MNA score for each 

well is listed in table 3. Six wells had scores greater 

than 12. In general, scores were highest for samples 

collected on the northeast side of the facility, although 

three wells in the central part of the facility, DWP–5–12, 

DWP–S1–10, and DWP–S1–4 had scores greater than 

12. 

SUMMARY 

Concentrations of TCE in ground water at 

NWIRP indicate three source areas of chlorinated solvents—building 1, building 6, and an off-site source 

west of the facility. The presence of cis-DCE and VC, 

products of reductive dechlorination of TCE that were 

not used at the facility, south and southwest of the 

source areas are evidence that reductive dechlorination 

is occurring. 

The efficiency of reductive dechlorination in 

ground water is controlled by redox processes. The 

most common redox processes in ground water are the 

reduction of oxygen, nitrate (denitrification), ferric iron, 

sulfate, and carbon dioxide (methanogenesis). Concentrations of reduced species (for example, nitrite, ferrous 

iron) at a particular site can indicate which redox process is dominant, but sometimes concentrations of 

reduced species are not definitive. In such cases, concentrations of dissolved hydrogen in specific ranges can 

indicate which redox process is dominant. In places 

south of the source areas, DO concentrations indicated 

that reduction of oxygen could be the dominant process, 

particularly south of building 6; but elevated DO concentrations south of building 6 might be caused by a 

leaking water or sewer pipe. The nitrite data indicate 

that denitrification is occurring in places; however dissolved hydrogen concentrations indicate that iron 

reduction is the dominant process south of building 6. 

The distributions of ferrous iron indicate that iron 

reduction is occurring in places south-southwest of 

buildings 6 and 1; dissolved hydrogen concentrations 

generally support the interpretation that iron reduction 

is the dominant process in those places. The generally 

low concentrations of sulfide indicate that sulfate reduction is not a key process in most sampled areas, an interpretation that is supported by dissolved hydrogen 

concentrations. 

Dissolved hydrogen concentrations at sampled 

wells were most frequently in the range that indicated 

ferric iron reduction is the primary redox process. 

Applying mean first-order decay rates for TCE, cisDCE, and VC in iron-reducing conditions from a recent 

study resulted in mean half-lives for TCE, cis-DCE, and 

VC of 231, 347, and 2.67 days, respectively. Decay rates 

were not computed for NWIRP, but it is expected that 

decay rates, and thus half-lives, at NWIRP would be 

similar to those computed. 

Small concentrations of TOC indicate the lack of 

an organic carbon source, which could be a limiting factor for efficient reductive dechlorination at NWIRP. 

The USEPA has developed a weighted scoring 

method to indicate sites where reductive dechlorination 

might be likely to occur. At NWIRP, a score greater than 

12 indicated strong evidence for anaerobic biodegradation of chlorinated solvents. Scores greater than 12 were 

computed for six sites. In general, scores were highest 

for samples collected on the northeast side of the facility, although three sites in the central part of NWIRP 

had scores greater than 12. 

REFERENCES CITED 

Anaya, Roberto, Braun, C.L., and Kuniansky, E.L., 2000, Use 

of borehole geophysical logs for improved site characterization at Naval Weapons Industrial Reserve Plant, 

22 Oxidation-Reduction Processes in Ground Water at Naval Weapons Industrial Reserve Plant, Dallas, Texas 
Dallas, Texas: U.S. Geological Survey Water-Resources 

Investigations Report 00–4150, 10 p. 

Barker, R.A., and Braun, C.L., 2000, Computer-model 

analysis of ground-water flow and simulated effects of 

contaminant remediation at Naval Weapons Industrial 

Reserve Plant, Dallas, Texas: U.S. Geological Survey 

Water-Resources Investigations Report 00–4197, 44 p. 

Bradley, P.M., and Chapelle, F.H., 1998, Microbial mineralization of VC and DCE under different terminal electron 

accepting conditions: Anaerobe, v. 4, p. 81–87. 

Braun, C.L., Anaya, Roberto, and Kuniansky, E.L., 2000, 

Borehole geophysical logs at Naval Weapons Industrial 

Reserve Plant, Dallas, Texas: U.S. Geological Survey 

Open-File Report 00–076, 232 p. 

Chapelle, F.H., 1996, Identifying redox conditions that favor 

the natural attenuation of chlorinated ethenes in contaminated ground-water systems, in Symposium on Natural 

Attenuation of Chlorinated Organics in Ground Water, 

Dallas, Tex., 1996, Proceedings: U.S. Environmental 

Protection Agency, EPA/540/R–96–509, p. 17–20. 

Chapelle, F.H., Vroblesky, D.A., Woodward, J.C., and 

Lovley, D.R., 1997, Practical considerations for measuring hydrogen concentrations in groundwater: Environmental Science and Technology, v. 31, no. 10, p. 2,873– 

2,877. 

EnSafe/Allen & Hoshall, 1994, Comprehensive long-term 

environmental action—Navy stabilization work plan; 

Revision I: Prepared for Southern Division Naval Facilities Engineering Command, Charleston, S.C., 83 p. 

______1996, Draft RCRA facility investigation report, Naval 

Weapons Industrial Reserve Plant, Dallas, Texas— 

Volume 1: Prepared for Southern Division Naval Facilities Engineering Command, Charleston, S.C., 135 p. 

Gilbert, T.W., Behymer, T.D., and Castaneda, H.B., 1982, 

Determination of dissolved oxygen in natural and wastewaters: American Laboratory, American Society for 

Testing and Materials ASTM D 888–87, p. 119–134. 

HACH Co., 1989, Water analysis handbook: Loveland, Colo., 

691 p. 

Suarez, M.P., and Rifai, H.S., 1999, Biodegradation rates for 

fuel hydrocarbons and chlorinated solvents in groundwater: Bioremediation Journal, v. 3, no. 4, p. 337–362. 

Trace Analytical, 1997, RGA reduction gas analyzer operating manual: Menlo Park, Calif., 45 p. 

U.S. Environmental Protection Agency, 1983, Methods for 

chemical analysis of water and wastes: EPA/600/4–74– 

020 [variously paged]. 

______1993, Methods for determination of inorganic substances in environmental samples: EPA/600/R–93–100 

[variously paged]. 

______1998, Technical protocol for evaluating natural 

attenuation of chlorinated solvents in ground water: 

EPA/600/R–98–128, 233 p. 

______1999, Test methods for evaluating solid wastes, 

physical/chemical methods (3d ed.): EPA/SW–846 

[variously paged]. 

U.S. Geological Survey, 1999, The quality of our Nation’s 

waters—Nutrients and pesticides: U.S. Geological 

Survey Circular 1225, 82 p. 

REFERENCES CITED 23 
Table 1 Table 1. Well information and sampling dates for wells sampled at the Naval Weapons Industrial Reserve Plant, 

Dallas, Texas—Continued 

Table 1. Well information and sampling dates for wells sampled at the Naval Weapons Industrial Reserve Plant, 

Dallas, Texas 

[“Both” indicates that the screen penetrates both the upper and middle parts of the shallow alluvial aquifer] 

Well 

number 

(fig. 1) 

Date sampled 

USGS 

EnSafe/ 

Allen & 

Hoshall 

Well depth 

(feet below 

land surface) 

Screened interval 

(feet below 

and surface) 

Part of shallow 

alluvial aquifer 

in which well 

is screened 

Well altitude 

(feet above 

NGVD of 1929) 

DWP–10–1 9/97 and 3/98 9/97 24 8–23 Both 486.6 

DWP–10–2 3/98 -- 29 13–28 Both 486 

DWP–10–6 3/98 -- 24 13–23 Upper 490 

DWP–10–DW1 3/98 9/97 59 50–55 Lower 486 

DWP–10–DW4 9/97 and 3/98 9/97 64 59–64 Lower 490.1 

DWP–10–DW6 3/98 9/97 54 34–54 Middle & lower 492 

DWP–1–13 9/97 and 3/98 9/97 19 3–18 Middle 471.4 

DWP–128–1 9/97 and 3/98 9/97 25 4.5–24.5 Upper 484.9 

DWP–1–9 9/97 and 3/98 9/97 29 13–28 Lower 464.5 

DWP–4–10 9/97 and 3/98 9/97 14 3–13 Middle 458.4 

DWP–4–14 9/97 and 3/98 9/97 22 10–20 Lower 461.5 

DWP–4–2 9/97 and 3/98 -- 22 11–21 Both 479.7 

DWP–4–4 9/97 and 3/98 -- 31 10–30 Both 483.1 

DWP–4–5 9/97 and 3/98 9/97 29 13–28 Both 490.2 

DWP–4–8 9/97 and 3/98 9/97 33 17–32 Both 489.6 

DWP–4–9 9/97 and 3/98 9/97 29 13–28 Both 476.6 

DWP–5–12 9/97 and 3/98 -- 32 16–31 Upper 488.7 

DWP–5–13 9/97 and 3/98 9/97 29 13–28 Both 485.3 

DWP–7–6 9/97 and 3/98 -- 32 15–25 Middle 476.9 

DWP–BG–10 9/97 and 3/98 9/97 21 5–20 Both 486.8 

DWP–BG–4 9/97 and 3/98 9/97 34 18–33 Middle 501.7 

DWP–BG–4–3 9/97 and 3/98 9/97 28 18–28 Both 503.2 

DWP–BG–4–6 9/97 and 3/98 9/97 30 15–30 Both 500.2 

DWP–BG-6 9/97 and 3/98 -- 39 23–38 Lower 470.8 

DWP–BG–7 9/97 and 3/98 9/97 29 13–28 Upper 499.6 

DWP–BG–8 9/97 and 3/98 -- 19 3.5–18.5 Both 478.9 

DWP–DBG–3 9/97 and 3/98 9/97 47 38–43 Lower 479 

DWP–L1–5 9/97 and 3/98 9/97 34 18–33 Middle 488.7 

DWP–L2–1 9/97 and 3/98 9/97 34 18–33 Upper 496.6 

DWP–L2–16 9/97 and 3/98 9/97 29 13–28 Upper 494.6 

DWP–L2–4 9/97 and 3/98 9/97 29 13–28 Upper 494.6 

DWP–L2–5 9/97 and 3/98 -- 27 11–26 Upper 494.6 

DWP–L2–8 9/97 and 3/98 9/97 27 11–26 Upper 494.9 

DWP–L2–DW1 9/97 and 3/98 9/97 60.5 55–60 Lower 495 

DWP–L2–DW2 9/97 and 3/98 9/97 48 42–47 Middle 495 

24 Oxidation-Reduction Processes in Ground Water at Naval Weapons Industrial Reserve Plant, Dallas, Texas 
Table 2 

Table 1. Well information and sampling dates for wells sampled at the Naval Weapons Industrial Reserve Plant, 

Dallas, Texas—Continued 

Well 

number 

(fig. 1) 

Date sampled 

USGS 

EnSafe/ 

Allen & 

Hoshall 

Well depth 

(feet below 

land surface) 

Screened interval 

(feet below 

and surface) 

Part of shallow 

alluvial aquifer 

in which well 

is screened 

Well altitude 

(feet above 

NGVD of 1929) 

DWP–OFF–10 9/97 and 3/98 9/97 29 13–28 Upper 495.3 

DWP–OFF–11 9/97 and 3/98 9/97 24 13–23 Both 493.9 

DWP–OFF–12 3/98 9/97 24 16–23.5 Lower 458 

DWP–OFF–14 3/98 9/97 20 13–18 Lower 459 

DWP–OFF–5 9/97 and 3/98 9/97 34 18–33 Both 501.8 

DWP–S1–10 9/97 and 3/98 9/97 29 13–28 Middle 474.8 

DWP–S1–11 9/97 and 3/98 -- 39 23–38 Middle 486.5 

DWP–S1–17 9/97 and 3/98 9/97 29 21–26 Upper 488.5 

DWP–S1–18 9/97 and 3/98 9/97 27 11–26 Upper 487.6 

DWP–S1–4 9/97 and 3/98 9/97 32 13–31 Upper 495.4 

DWP–S1–5 9/97 and 3/98 -- 26 10–25 Upper 485.0 

DWP–S1–7 9/97 and 3/98 9/97 30 14–29 Upper 493.2 

DWP–S1–DW1 9/97 and 3/98 9/97 62.5 52–62 Lower 489 

DWP–S1–DW2 9/97 and 3/98 -- 48 38–45.5 Middle 488 

DWP–S2–11 9/97 and 3/98 9/97 27 11–26 Upper 491.2 

DWP–S2–16 9/97 and 3/98 9/97 29 13–28 Upper 492 

DWP–S2–18 9/97 and 3/98 9/97 27 11–26 Both 490 

DWP–S2–2 9/97 and 3/98 9/97 35 20–35 Upper 494.7 

DWP–S2–5 9/97 and 3/98 9/97 33 17–32 Both 491.5 

DWP–S2–DW1 9/97 and 3/98 9/97 71.5 62.5–67.5 Lower 492 

DWP–S2–DW2 9/97 and 3/98 9/97 57 41–56 Middle 492 

DWP–S5–10 9/97 and 3/98 9/97 32 15–30 Upper 497.8 

Table 2. Selected constituents, methods, and procedures used to evaluate oxidation-reduction processes in 

ground water at the Naval Weapons Industrial Reserve Plant, Dallas, Texas 

[GCMS, gas chromatography/mass spectroscopy] 

Constituent Method Procedure 

Volatile organic compounds 18260 and field chromatography GCMS (laboratory) and gas chromatography (field)


Dissolved oxygen Indigo carmine2 Colorimetric analysis (field)


Nitrate and nitrate + nitrite 3300.0 and 4

353.2 Ion chromatography (laboratory)


Ferrous and total iron HACH5 methods 255 and 265 Colorimetric analysis (field)


Sulfide HACH5

 method 690 Colorimetric analysis (field)


Dissolved hydrogen Bubble strip6 Reduction gas analysis (field)


Total organic carbon 79060 Wet oxidation (laboratory)


1

 U.S. Environmental Protection Agency, 1999. 5 HACH Co., 1989. 
 2 Gilbert and others, 1982. 6 Chapelle, 1996. 
 3

 U.S. Environmental Protection Agency, 1993. 7 U.S. Environmental Protection Agency, 1999.
 4

 U.S. Environmental Protection Agency, 1983.


Table 2 25 
Table 3 

Table 3. Chemical results for selected volatile organic compounds from wells sampled at the Naval Weapons 

Industrial Reserve Plant, Dallas, Texas—Continued 

Table 3. Chemical results for selected volatile organic compounds from wells sampled at the Naval Weapons 

Industrial Reserve Plant, Dallas, Texas 

[September 1997 data collected by EnSafe and analyzed by laboratory gas chromatograph/mass spectrometer; March 1998 

data collected by USGS and analyzed by portable field gas chromatograph. μg/L, micrograms per liter; MNA, monitored 

natural attenuation; <, less than; ND, not detected; >, greater than; --, no data] 

Well 

number 

Trichloroethene 

(μg/L) 

cis-1,2­

Dichloroethene 

(μg/L) 

trans-1,2­

Dichloroethene 

(μg/L) 

Vinyl 

chloride 

(μg/L) 

Ratio of 

trichloroethene 

to cis-1,2­

dichloroethene 

MNA 

score 

9/97 3/98 9/97 3/98 9/97 3/98 9/97 3/98 9/97 3/98 9/97 

DWP–10–1 36 12 <10 16 <10 ND <10 12 >3.6 0.3 14 

DWP–10–2 -- 50 -- 54 -- ND -- 94 -- .9 --

DWP–10–6 -- 450 -- 1

4 -- ND -- ND -- 112.5 --

DWP–10–DW1 252,000 13,000 2960 7,900 19 13 146 13 54.2 1.6 --

DWP–10–DW4 2

3,000 27 2680 18 111 ND 127 ND 4.4 3.4 10 

DWP–10–DW6 15,000 5,000 1

320 47 <1,000 12 <1,000 ND 46.9 106.4 --

DWP–1–13 2180 220 2350 300 13 10 120 13 .5 .7 10 

DWP–128–1 2

940 29 2200 12 12 11 63 12 4.7 2.4 11 

DWP–1–9 260 350 180 350 5 5 32 7 1.4 1.0 10 

DWP–4–10 ND 5 130 150 1.8 11 61 33 0 0 10 

DWP–4–14 180 110 240 140 1

8 14 80 7 .8 .8 10 

DWP–4–2 -- 250 -- 160 -- 10 -- ND -- 1.6 --

DWP–4–4 -- 16 -- 1,900 -- 8 -- 84 -- 0 12 

DWP–4–5 3,100 2,200 1

280 230 <500 15 <500 14 11.1 9.6 3 

DWP–4–8 510 310 540 350 1

29 13 <50 11 .9 .9 6 

DWP–4–9 420 310 200 130 123 10 <50 ND 2.1 2.4 5 

DWP–5–12 -- 27 -- 5 -- ND -- 1

1 -- 5.4 14 

DWP–5–13 2510 660 186 95 1

9 8 17 11 5.9 6.9 12 

DWP–7–6 -- 260 -- 78 -- 4 -- 1

1 -- 3.3 4 

DWP–BG–10 120 170 <10 ND <10 ND <10 ND >12.0 >170.0 --

DWP–BG–4 680 640 63 55 <50 ND <50 ND 10.8 11.6 8 

DWP–BG–4–3 110 66 11 6 <10 ND <10 ND 10.0 11.0 8 

DWP–BG–4–6 19 20 <10 ND <10 ND <10 ND >.9 >20.0 4 

DWP-BG-6 -- 33 -- 12 -- ND -- ND -- 16.5 4 

DWP–BG–7 590 450 28 36 <50 13 <50 ND 21.1 12.5 3 

DWP–BG–8 -- 9 -- ND -- ND -- ND -- >9.0 1 

DWP–DBG–3 -- 7 -- 1

1 -- ND -- ND -- 7.0 12 

DWP–L1–5 ND 390 <10 280 <10 ND <10 ND 0 1.4 11 

DWP–L2–1 3,000 1,400 300 220 <200 ND <200 ND 10.0 6.4 3 

DWP–L2–16 2

1,200 290 2220 170 1 ND <10 ND 5.5 1.7 3 

DWP–L2–4 27,000 12,000 1310 230 <2,000 2 <2,000 ND 87.1 52.2 3 

DWP–L2–5 -- 450 -- 6 -- ND -- ND -- 75.0 4 

Footnotes at end of table. 

26 Oxidation-Reduction Processes in Ground Water at Naval Weapons Industrial Reserve Plant, Dallas, Texas 
Table 3. Chemical results for selected volatile organic compounds from wells sampled at the Naval Weapons 

Industrial Reserve Plant, Dallas, Texas—Continued 

cis-1,2- trans-1,2- Ratio of Trichloro- Vinyl Dichloro- Dichloro- trichloroethene MNA 

Well ethene ethene ethene 

chloride to cis-1,2- score 

number (μg/L) (μg/L) (μg/L) (μg/L) dichloroethene 

9/97 3/98 9/97 3/98 9/97 3/98 9/97 3/98 9/97 3/98 9/97 

DWP–L2–8 5,600 3,200 65 90 <500 ND <500 ND 86.2 35.6 11


DWP–L2–DW1 200 350 1

3 25 <20 1 <20 ND 66.7 14.0 3


DWP–L2–DW2 4,500 2,200 125 620 <250 ND <250 ND 180.0 3.5 8


DWP–OFF–10 2

420 620 11 14 <10 ND <10 ND -- 155.0 5


DWP–OFF–11 2

270 340 <10 11 <10 ND <10 ND >27.0 340.0 -­


DWP–OFF–12 36 58 22 15 1

1 11 <10 ND 1.6 3.9 -­ 


DWP–OFF–14 16 23 14 11 1

1 ND 12 ND 1.1 2.1 -­ 


DWP–OFF–5 13,000 6,800 4,500 2,700 <1,000 8 <1,000 24 2.9 2.5 8


DWP–S1–10 214,000 5,600 2970 520 100 33 170 10 14.4 10.8 13


DWP–S1–11 -- 700 -- 17 -- 11 -- ND -- 41.2 9 


DWP–S1–17 12 27 <10 16 <10 13 <10 10 0 1.7 9 


DWP–S1–18 2

4,600 2,400 2430 320 10 3 66 13 10.7 7.5 10 


DWP–S1–4 2

440 290 23 15 <10 ND 27 11 19.1 19.3 14 


DWP–S1–5 -- 8 -- 3,200 -- 410 -- ND -- 0 -­


DWP–S1–7 23 45 <10 2 <10 ND <10 ND >2.3 22.5 6


DWP–S1–DW1 1.5 66 <10 12 <10 ND <10 ND 0 33.0 6 


DWP–S1–DW2 <10 9 <10 ND <10 ND <10 ND 1.0 >9.0 6


DWP–S2–11 1

400 150 22,700 1,100 64 14 186 13 .1 .1 12 


DWP–S2–16 2

3,400 4,300 29,300 1,100 147 37 2420 180 .4 3.9 16


DWP–S2–18 2720 1,030 130 134 15 13 17 12 5.5 7.7 10 


DWP–S2–2 13 46 180 150 26 19 1

3 2 .1 .3 10


DWP–S2–5 <10 ND 21,500 540 1

36 7 24,400 170 0 0 16


DWP–S2–DW1 17 18 1

4 21 <10 ND <10 550 1.8 .9 11


DWP–S2–DW2 1

430 17 141 270 <10 ND <10 12 10.5 .1 5 


DWP–S5–10 240 210 <10 1

1 <10 ND <10 ND >24.0 210.0 4


1

 Estimated.
 2 Sample diluted during analysis. 


Table 3 27 
Table 4 

Table 4. Selected field and laboratory data from wells sampled at the Naval Weapons Industrial Reserve Plant, 

Dallas, Texas—Continued 

Table 4. Selected field and laboratory data from wells sampled at the Naval Weapons Industrial Reserve Plant, 

Dallas, Texas 

[Nitrite data from laboratory, all other data analyzed from unfiltered samples in the field. mg/L, milligrams per liter; nM, 

nanomolar; ND, not detected; --, no data] 

Well 

number 

Dissolved 

oxygen 

(mg/L) 

Nitrite 

(mg/L) 

Ferrous 

iron 

(mg/L) 

Sulfide 

(mg/L) 

Dissolved 

hydrogen 

(nM) 

9/97 3/98 9/97 3/98 9/97 3/98 9/97 3/98 9/97 3/98 

DWP–10–1 0.24 0.08 ND -- 5.02 14.76 0.002 ND 1.8 0.2 

DWP–10–2 -- .06 -- -- -- 14.16 -- .001 -- .5 

DWP–10–6 -- .24 -- -- -- ND -- .006 -- .3 

DWP–10–DW1 -- 1.28 -- -- -- .90 -- ND -- .6 

DWP–10–DW4 .19 .14 ND -- .84 1.22 .003 .007 ND .3 

DWP–10–DW6 -- .06 -- -- -- .10 -- .008 -- ND 

DWP–1–13 .14 2.04 ND -- 3

.02 ND .001 .002 ND .1 

DWP–128–1 .22 2.03 ND -- 13.04 1

4.10 .005 ND .2 2.1 

DWP–1–9 .20 .45 .6 -- 3

.10 ND .002 .001 ND .2 

DWP–4–10 .44 2.04 ND -- .14 .02 ND .001 .4 .2 

DWP–4–14 .27 .13 .2 -- ND ND ND ND .2 ND 

DWP–4–2 1.47 1.92 .6 -- .01 ND ND ND .1 ND 

DWP–4–4 .27 2.04 .5 -- 1.8 2.56 ND ND 1.1 .9 

DWP–4–5 .69 .09 .2 -- ND .05 ND .011 .2 .1 

DWP–4–8 .27 .22 ND -- .04 .02 .001 .009 .5 .2 

DWP–4–9 .77 1.55 .5 -- ND .04 ND .003 1.1 ND 

DWP–5–12 .35 .06 .1 -- 1.44 1.13 ND .006 .7 .4 

DWP–5–13 .27 .07 .1 -- ND .06 .003 .016 .5 ND 

DWP–7–6 .20 .34 .4 -- 3

.10 ND .003 .006 ND .3 

DWP–BG–10 1.55 .66 .2 -- ND .04 ND .004 ND ND 

DWP–BG–4 .15 .78 .2 -- .02 ND .001 ND ND ND 

DWP–BG–4–3 .22 .16 .1 -- .03 ND ND ND ND ND 

DWP–BG–4–6 .24 .15 .4 -- 3

.09 ND .006 ND .3 .1 

DWP–BG-6 .32 .16 ND -- .01 ND ND ND ND .1 

DWP–BG–7 .54 .21 ND -- .02 ND .002 ND .1 .2 

DWP–BG–8 1.8 1.16 1.1 -- .05 .02 .005 .005 ND ND 

DWP–DBG–3 .19 2.02 .8 -- 1.78 1.18 .014 ND 1.3 1.8 

DWP–L1–5 .32 .15 .3 -- .75 1

1.16 .007 .004 .5 1.7 

DWP–L2–1 2.29 1.80 1.1 -- 3

.37 .02 ND .002 ND ND 

DWP–L2–16 1.47 .10 .8 -- 3

.06 .04 .002 .005 .2 ND 

DWP–L2–4 1.75 2.21 .3 -- 3.19 ND .009 .012 .2 ND 

DWP–L2–5 1.50 .12 1.1 -- 3

.16 ND .007 .021 .4 .7 

Footnotes at end of table. 

28 Oxidation-Reduction Processes in Ground Water at Naval Weapons Industrial Reserve Plant, Dallas, Texas 
Table 4. Selected field and laboratory data from wells sampled at the Naval Weapons Industrial Reserve Plant, 

Dallas, Texas—Continued 

Well 

number 

Dissolved 

oxygen 

(mg/L) 

Nitrite 

(mg/L) 

Ferrous 

iron 

(mg/L) 

Sulfide 

(mg/L) 

Dissolved 

hydrogen 

(nM) 

9/97 3/98 9/97 3/98 9/97 3/98 9/97 3/98 9/97 3/98 

DWP–L2–8 0.38 0.19 0.3 -- 0.03 ND 0.033 0.001 2.7 0.5 

DWP–L2–DW1 1.24 .16 .3 -- 3

.13 .03 .002 ND .1 2.4 

DWP–L2–DW2 .54 .26 .4 -- .12 .53 .001 .055 7.3 .3 

DWP–OFF–10 .54 .30 .4 -- 3.10 .02 .005 .002 .1 ND 

DWP–OFF–11 -- .85 .3 -- 3

.14 .02 .002 ND ND .1 

DWP–OFF–12 -- 1.67 -- -- -- .06 -- .001 -- .7 

DWP–OFF–14 -- .24 -- -- -- .08 -- ND -- 1 

DWP–OFF–5 .17 .11 ND -- .01 ND ND .082 ND ND 

DWP–S1–10 .27 .13 .4 -- 3

.12 .02 .004 .003 .15 1.0 

DWP–S1–11 .22 .22 .4 -- 3

.17 ND .012 .012 1.9 .5 

DWP–S1–17 .27 2.03 ND -- 2.66 2.75 .003 .001 ND .3 

DWP–S1–18 .32 .10 ND -- 3

.15 .03 .008 .011 .3 ND 

DWP–S1–4 .2 .25 .4 -- .01 .05 .002 .006 .14 .2 

DWP–S1–5 .65 .57 ND -- 3

.12 ND .005 ND .2 .3 

DWP–S1–7 .23 .34 .1 -- 3.03 .01 ND ND .1 .2 

DWP–S1–DW1 .32 .06 ND -- .86 .88 .021 ND 2.0 .2 

DWP–S1–DW2 .32 .05 ND -- ND .03 ND .021 4

670 42,100 

DWP–S2–11 .36 .15 ND -- .16 .02 ND .003 ND ND 

DWP–S2–16 .32 ND ND -- 1.56 1.96 .017 ND ND .1 

DWP–S2–18 .22 .05 .2 -- .01 .03 .001 .012 ND .5 

DWP–S2–2 .27 .23 ND -- .31 .16 .003 .003 .8 .1 

DWP–S2–5 .3 .09 ND -- 14.94 1

3.80 .002 ND .2 .2 

DWP–S2–DW1 .54 2.04 ND -- 2.02 1.15 .024 ND 4

290 .9 

DWP–S2–DW2 1.14 .20 ND -- .37 1.72 .006 .003 .6 2.4 

DWP–S5–10 .22 .23 .2 -- ND ND .004 ND ND ND 

1 Sample diluted during analysis. 


2 Estimated.
 3

 Erroneous value because of cloudy sample.
 4 Erroneous value because of new well construction. 


Table 4 29 
Table 5 

Table 5. Mean first-order decay rates and computed half-lives for trichloroethene, dichloroethene, and vinyl 

chloride under five oxidation-reduction conditions (Suarez and Rifai, 1999) 

[--, no data] 

Dichloro- Trichloro- Vinyl Oxidation-reduction Half-life ethene Half-life Half-life ethene chloride 

condition (days) (all isomers) (days) (days) day-1 

day-1 day-1 

Oxygen reduction (aerobic oxidation) 0.005 139 -- -- 0.087 7.97 

Nitrate reduction (denitrification) -- -- -- -- -- -­

Iron reduction .003 231 0.002 347 .26 2.67 

Sulfate reduction .011 63 .045 15.4 -- -­

Carbon dioxide reduction (methanogenesis) .015 46.2 .047 14.7 .23 3.01 

30 Oxidation-Reduction Processes in Ground Water at Naval Weapons Industrial Reserve Plant, Dallas, Texas 
Oxidation-Reduction Processes in Ground Water 

at Naval Weapons Industrial Reserve Plant, 

Dallas, Texas 

Appendix—Data Appendix—Data 

Appendix—Data 31 
Field d

ata collected b

y the USG

S, S

e

ptemb

er 1997 and M

arch 1998—Continued 

32 Oxidation-Reduction Processes in Ground Water at Naval Weapons Industrial Reserve Plant, Dallas, Texas 

Field d

ata c

ollected b

y the USG

S, S

e

ptemb

er 1997 and M

arch 1998 

[μS, microsiemens per centimeter at 25 

degrees 

Celsi

us; m

M, milli

molar; μM, 

micromolar; mg/L, milligrams per liter; N

D, not detecte

September 1997 

March 1998 

Well number 

Specific 

conductance 

(μS) 

pH 

(standard 

units) 

Carbon 

dioxide 

(mM C

O2) 

Methane 

(μM CH4) Well nu

mber 

Specific 

conductance 

(μS) 

pH 

(standard 

units) 

Alkalinity

bicarbona

(mg/L HC

O

D

W

P–10–1 950 6.88 0.01 ND 

D

WP–10–1 703 6.61 455 

D

WP–10–DW4 910 6.77 .48 ND 

DWP–10–2 846 7.25 478 

D

W

P–1–13 6,080 7.51 1.77 7.87 

D

WP–10–6 720 7.13 405 

D

WP–128–1 930 6.74 2.17 34.20 DWP–10–

D

W1 1,103 7.40 401 

D

W

P–1–9 970 7.39 1.57 ND 

D

WP–10–D

W4 1,178 7.08 398 

D

W

P–4–10 1,150 6.6 3.75 .87 

D

WP–10–D

W6 803 7.22 371 

D

W

P–4–14 1,030 6.56 2.21 ND 

D

WP–1–13 1,101 6.95 528 

D

WP–4–2 -- -- 2.23 ND 

DWP–128–1 1,104 6.94 638 

D

W

P–4–4 -- -- 1.94 61.49 

D

WP–1–9 1,126 6.50 459 

D

WP–4–5 1,160 6.75 2.28 .46 DWP–4–10 1,220 6.82 646 

D

WP–4–8 920 7.9 1.22 ND 

DWP–4–14 1,122 6.73 485 

D

W

P–4–9 1,210 6.61 2.67 ND 

D

WP–4–2 1,228 6.81 516 

D

W

P–5–12 705 6.86 1.20 72.12 D

W

P–4–4 995 6.77 520 

D

W

P–5–13 677 6.77 1.29 .57 D

W

P–4–5 1,160 6.79 559 

D

WP–7–6 -- -- 1.89 2.86 DWP–4–8 930 6.99 476 

D

W

P–B

G–10 830 6.74 2.33 ND 

D

WP–4–9 1,210 6.84 540 

D

W

P–B

G–4 1,160 7.91 1.19 ND 

D

WP–5–12 802 6.92 450 

D

W

P–B

G–4–3 1,030 6.79 1.58 ND 

D

WP–5–13 798 6.81 379 

D

W

P–B

G–4–6 1,190 7.72 1.10 ND 

D

WP–7–6 976 6.80 469 

D

W

P–B

G–6 798 6.43 1.94 ND 

D

WP–

B

G–10 1,036 6.58 521 

D

W

P–B

G–7 1,240 6.61 2.84 ND 

D

WP–

B

G–4 1,028 6.97 418 

D

W

P–B

G–8 1,050 7.84 2.11 ND 

D

WP–

B

G–4–3 1,090 6.80 481 

D

W

P–DBG–3 1,050 7.84 1.39 ND 

D

WP–

B

G–4–6 1,002 6.95 479 

D

W

P–L1–5 717 6.86 .69 447.55 D

W

P–BG–6 924 6.98 428 

D

W

P–L2–1 741 6.96 1.08 ND 

D

WP–

B

G–7 1,138 6.86 516 

D

W

P–L2–16 757 7.02 .74 ND 

D

W

P–BG–8 1,031 7.11 513 

D

W

P–L2–4 -- -- .36 ND 

D

W

P–D

B

G–3 991 6.85 447 

D

W

P–L2–5 -- -- 1.19 ND 

D

WP–

L1–5 700 7.07 455 
Field data collected by the USGS, September 1997 and March 1998—Continued 

September 1997 March 1998 

Well number 

Specific 

conductance 

(μS) 

pH 

(standard 

units) 

Carbon 

dioxide 

(mM CO2) 

Methane 

(μM CH4) Well number 

Specific 

conductance 

(μS) 

pH 

(standard 

units) 

Alkalinity

bicarbonat

(mg/L HCO

DWP–L2–8 980 6.93 ND ND DWP–L2–1 949 7.22 327 DWP–L2–DW1 1,620 11.08 .10 ND DWP–L2–16 937 6.90 504 DWP–L2–DW2 825 7.14 1.01 6.66 DWP–L2–4 613 7.12 216 DWP–OFF–10 921 6.68 2.68 ND DWP–L2–5 1,055 6.95 385 DWP–OFF–11 1,240 6.59 3.34 ND DWP–L2–8 1,020 6.84 413 DWP–OFF–5 1,490 6.33 2.01 2.89 DWP–L2–DW1 4,000 11.84 289 DWP–S1–10 865 6.67 1.51 32.34 DWP–L2–DW2 889 7.02 411 DWP–S1–11 -- -- 1.28 ND DWP–OFF–10 1,169 6.87 529 DWP–S1–17 628 6.98 3.08 3.75 DWP–OFF–11 1,194 6.87 546 DWP–S1–18 734 6.6 .99 ND DWP–OFF–12 905 6.93 481 DWP–S1–4 734 6.79 2.26 6.71 DWP–OFF–14 903 7.91 496 DWP–S1–5 -- -- 1.34 ND DWP–OFF–5 1,557 7.00 498 DWP–S1–7 1,170 7.33 1.81 ND DWP–S1–10 921 6.78 470 DWP–S1–DW1 -- -- .95 ND DWP–S1–11 870 6.89 423 DWP–S1–DW2 -- -- .01 ND DWP–S1–17 683 7.09 368 DWP–S2–11 950 7.65 2.43 3.62 DWP–S1–18 787 6.90 397 DWP–S2–16 960 6.87 1.93 43.60 DWP–S1–4 924 6.95 334 DWP–S2–18 765 6.75 1.96 ND DWP–S1–5 849 7.19 403 DWP–S2–2 936 7.6 1.73 .93 DWP–S1–7 950 6.87 433 DWP–S2–5 699 6.95 2.08 132.75 DWP–S1–DW1 792 7.23 411 DWP–S2–DW1 1,510 7.03 .59 ND DWP–S1–DW2 1,497 11.63 78 DWP–S2–DW2 756 7.09 .46 ND DWP–S2–11 1,031 6.79 456 DWP–S5–10 1,240 6.71 2.83 ND DWP–S2–16 920 6.95 501 

DWP–S2–18 931 6.80 516 DWP–S2–2 1,005 6.88 491 DWP–S2–5 923 6.80 518 DWP–S2–DW1 1,584 7.13 420 DWP–S2–DW2 1,231 7.01 395 DWP–S5–10 1,038 6.83 520 

Appendix—Data 33 
Data from EnS

afe/Allen & H

oshall c

ontract laborator

y, September 1997—Continued 

34 Oxidation-Reduction Processes in Ground Water at Naval Weapons Industrial Reserve Plant, Dallas, Texas Data from EnS

afe/Allen & Hoshall contract lab

oratory, September 1997 

[mg/L, milligrams per liter; μg/L, micrograms per liter; ND, not detected; --, not analyzed] 

Well 

nu

mber 

Dissolved 

solids, 

calculated 

(mg/L) 

Calcium 

(mg/L) 

Magnesium 

(mg/L) 

Sodium 

(mg/L) 

Potassium 

(mg/L) 

Iron 

(mg/L) 

Manganese 

(mg/L) 

Tetrachloroethene 

(μg/L) 

1,1-Dichloroethene 

(μg/L) 

1,1,1­

Trichloroethane 

(μg/L) 

1,1-

roe

(

D

W

P–10–1 416 82.3 13.5 48.7 1.47 11.3 0.795 ND ND ND 

D

W

P–10–D

W1 -- 103 11 120 3.30 3.36 .336 7 ND 

ND 

D

W

P–10–D

W4 771 117 8 84.6 1.54 .267 .386 ND 

ND 

ND 

D

W

P–10–D

W6 -- 99 5.44 81.4 3.75 1.56 .196 ND ND ND 

D

W

P–1–13 722 135 9.24 121 1.19 .178 .073 ND 3 ND 

D

W

P–128–1 568 110 6.5 103 1.81 .86 1.43 ND 4 ND 

D

W

P–1–9 762 115 9.37 106 1.19 .122 .039 ND ND ND 

D

W

P–4–10 763 134 14.6 137 .475 .93 1.67 ND 1 ND 

D

W

P–4–14 723 181 10.7 67.4 1.31 .035 .022 ND ND ND 

D

W

P–4–2 -- -- -- -- -- -- -- ND 

ND 

ND 

D

W

P–4–4 -- -- -- -- -- -- -- ND 

ND 

ND 

D

W

P–4–5 724 109 7.67 150 1.06 .039 .29 ND 

ND 

ND 

D

W

P–4–8 574 83.1 6.5 109 1.03 .106 .009 ND ND ND 

D

W

P–4–9 732 108 7.69 136 .9 .026 .007 ND ND ND 

D

W

P–5–12 463 62.9 5.31 104 .56 1.71 .948 ND 

ND 

ND 

D

W

P–5–13 528 102 6.32 62.9 1.9 .029 .006 3 3 ND 

D

W

P–7–6 -- -- -- -- -- -- -- ND 

ND 

ND 

D

W

P–B

G–10 617 109 5.58 115 1.37 .102 .006 ND ND ND 

D

WP–

B

G–4 604 92.2 5.64 109 1.3 .11 .009 98 

ND 

ND 

D

WP–

B

G–4–3 697 113 11.6 128 1.86 .019 .005 43 ND 

ND 

D

W

P–B

G–4–6 584 66.3 5.49 144 1.25 .061 .002 ND ND ND 

D

W

P–B

G–6 564 151 6.09 33 1.36 .69 .013 ND 

ND 

ND 

D

W

P–B

G–7 717 136 7.82 119 .99 .049 .001 ND ND ND 

D

W

P–BG–8 625 80.9 3.44 146 .825 .146 .003 ND ND ND 

D

W

P–DBG–3 603 82.6 3.51 147 .846 .166 .003 ND 

ND 

ND 

D

W

P–L1–5 426 46.5 3.6 117 .74 3.55 .36 ND 

ND 

ND 

D

WP–L2–1 502 117 6.1 85.8 .9 .25 .05 ND 200 

ND 
Data from EnSafe/Allen & Hoshall contract laboratory, September 1997—Continued 

Appendix—Data 

Well 

number 

Dissolved 

solids, 

calculated 

(mg/L) 

Calcium 

(mg/L) 

Magnesium 

(mg/L) 

Sodium 

(mg/L) 

Potassium 

(mg/L) 

Iron 

(mg/L) 

Manganese 

(mg/L) 

Tetrachloroethene 

(μg/L) 

1,1-Dichloroethene 

(μg/L) 

1,1,1­

Trichloroethane 

(μg/L) 

1,1-

roe

(μ

DWP–L2–16 438 97.3 5.62 67.3 0.88 0.36 0.009 ND 54 ND DWP–L2–4 345 87.6 4.5 36.2 1.08 5.18 .14 ND ND ND DWP–L2–5 -- -- -- -- -- -- -- ND ND ND DWP–L2–8 693 118 8.65 98 1.21 .32 .01 ND ND ND DWP–L2–DW1 774 3.15 .67 167 .102 .006 ND 3 ND DWP–L2–DW2 607 88.2 8.01 108 4.41 5.75 .453 ND ND ND DWP–OFF–10 734 143 8.53 118 1.2 .37 .009 6 ND ND DWP–OFF–11 805 156 8.73 127 1.42 .31 .008 ND ND ND DWP–OFF–12 -- 158 8.71 28.7 2.2 .704 .496 ND ND ND DWP–OFF–14 -- 161 9.4 39.4 3.2 7.21 2.36 ND ND ND DWP–OFF–5 1,001 138 13.7 200 1.88 .322 .03 170 ND ND DWP–S1–10 551 112 5.78 81.9 1.73 .19 .085 1 77 ND DWP–S1–11 -- -- -- -- -- -- -- ND ND ND DWP–S1–17 384 81.2 7.4 54.5 1.2 3.28 .77 ND ND ND DWP–S1–18 411 76.1 4.17 93 .99 .23 .006 1 70 ND DWP–S1–4 120 7.43 75.1 .68 .18 .15 .9 270 ND DWP–S1–5 -- -- -- -- -- -- -- ND ND ND DWP–S1–7 598 119 7.2 103 1.07 .11 .006 8 1,100 18 DWP–S1–DW1 -- -- -- -- -- -- -- ND ND ND DWP–S1–DW2 -- -- -- -- -- -- -- ND ND ND DWP–S2–11 614 122 5.94 95.3 .97 .18 .014 ND 5 ND DWP–S2–16 564 93.5 9.05 99.9 1.29 2.06 1.22 ND 12 ND DWP–S2–18 578 103 9.46 98.8 2.23 1.73 .096 ND 2 2 DWP–S2–2 624 91.6 6.64 136 2.18 1.77 .81 ND 8 ND DWP–S2–5 558 94.4 7.66 101 2.65 5.32 1.52 ND 4 ND DWP–S2–DW1 1,264 105 18 295 6.47 1.93 .143 ND ND ND DWP–S2–DW2 603 87.5 10.3 97.2 3.77 .375 .269 ND ND ND DWP–S5–10 694 140 9.24 96.9 1.06 .019 .002 ND ND ND 

35 
Data c

ollected by USG

S and analyze

d by 

Quanterra Laboratories, S

e

ptemb

er 1997—Continued 

36 Oxidation-Reduction Processes in Ground Water at Naval Weapons Industrial Reserve Plant, Dallas, Texas Data collected b

y US

G

S and analyzed b

y Quanterra Labor

atories, September 1997 

[mg/L, 

milligrams per liter; ND, not detected] 

Well nu

mber 

Alkalinity, 

bicarbonate 

(mg/L HCO3) 

Sulfate 

(mg/L S

O4) 

Chloride 

(mg/L Cl) 

Fluoride (mg/L F) 

Silica 

(mg/L Si

O2) 

Nitrate 

nitrogen 

(mg/L NO3) 

Nitrate plus 

nitrite nitrogen 

(mg/L 

NO3 + NO2) 

Am

monia 

nitrogen 

(mg/L NH4) 

Orthophospha

 phosphorus 

(mg/L PO4) 

D

WP–10–1 449 4.9 16.6 

ND 12.2 ND 

ND 1.1 ND 

D

WP–10–D

W4 387 326 21.5 

ND 17.8 ND 

ND 1 ND 

D

WP–1–13 491 146 42.4 1 21.6 

ND 

ND 

ND ND 

D

W

P–128–1 318 104 61.9 1.3 19.7 1.2 1.4 .47 

ND 

D

W

P–1–9 460 115 52.6 1.2 21.3 ND .39 ND 

ND 

D

WP–4–10 690 70.1 40.2 

ND 19.1 

ND 

ND .23 .42 

D

WP–4–14 519 124 55 ND 23.6 ND 

ND .3 .51 

D

W

P–4–2 546 141 18.7 ND 25.3 2.8 3.4 ND .16 

D

W

P–4–4 478 86.5 39.1 ND 17.3 ND 

ND 2.2 ND 

D

W

P–4–5 554 120 34.8 ND 24.1 1.6 1.8 ND 

ND 

D

WP–4–8 472 92.3 24.5 .58 21.1 1.1 1.3 ND .22 

D

W

P–4–9 581 135 29.9 ND 23.7 ND .46 .21 .14 

D

WP–5–12 433 5.9 42.6 1.7 22.1 

ND 

ND .11 ND 

D

W

P–5–13 375 57.8 24.7 1.4 22.8 ND 

ND 

ND 

ND 

D

WP–7–6 500 67.7 28.4 .83 24.6 1 1.1 ND ND 

D

WP–B

G–10 522 69.5 30.2 .65 24.8 2.3 2.4 ND ND 

D

W

P–B

G–4 410 133 34.9 .97 22.6 2 2.4 ND .12 

D

WP–B

G–4–3 480 148 32.1 .95 22.4 1.9 2.1 ND ND 

D

WP–B

G–4–6 441 86.8 38.3 1.1 21.4 1.2 1.4 ND .056 

D

W

P–B

G–6 427 102 31.5 .64 24.6 2.6 2.7 ND 

ND 

D

W

P–B

G–7 538 105 53.4 .65 26.2 1 1.4 ND .61 

D

WP–B

G–8 514 84.5 28.4 1.1 23.4 2.1 2.2 ND ND 

D

W

P–DBG–3 455 55.6 64 1.1 21.4 ND 

ND .17 

ND 

D

W

P–L1–5 395 ND 42.2 1.5 15 ND ND 1.2 ND 

D

WP–L2–1 337 71.2 29.1 .76 23.4 25 26.1 ND ND 
Data collected by USGS and analyzed by Quanterra Laboratories, September 1997—Continued 

Appendix—Data 

Well number 

Alkalinity, 

bicarbonate 

(mg/L HCO3) 

Sulfate 

(mg/L SO4) 

Chloride 

(mg/L Cl) 

Fluoride 

(mg/L F) 

Silica 

(mg/L SiO2) 

Nitrate 

nitrogen 

(mg/L NO3) 

Nitrate plus 

nitrite nitrogen 

(mg/L 

NO3 + NO2) 

Ammonia 

nitrogen 

(mg/L NH4) 

Orthophosphat

 phosphorus 

(mg/L PO4) 

DWP–L2–16 271 75.4 33.7 0.82 22.3 14.8 15.6 ND ND DWP–L2–4 218 42.7 37.3 .79 20.9 3.2 3.5 ND ND DWP–L2–5 386 108 59 ND 25.1 8.4 9.5 ND ND DWP–L2–8 682 79.3 20.5 1.5 25.8 ND ND .93 ND DWP–L2–DW1 406 128 41.5 ND 27.6 3.9 4.2 ND ND DWP–L2–DW2 497 60 54.2 2.5 29.8 ND ND ND ND DWP–OFF–10 528 107 66.6 .68 25.2 2.8 3.1 ND ND DWP–OFF–11 538 123 95.2 ND 24.4 1.5 1.8 ND .091 DWP–OFF–5 495 278 96.1 ND 25.8 2.3 2.7 ND .18 DWP–S1–10 425 71.8 43.3 ND 21.5 2.1 2.5 ND ND DWP–S1–11 422 88.7 21.3 .65 21.9 ND .25 ND ND DWP–S1–17 348 25.5 18.1 1.6 17.9 ND .12 .87 ND DWP–S1–18 271 54.8 22.9 .83 23.2 2 2.4 ND ND DWP–S1–4 372 62.9 33.8 1.3 25.5 ND ND ND ND DWP–S1–5 398 59.8 35.1 1.4 23.2 1.7 2.1 ND ND DWP–S1–7 442 85.5 35.1 .75 26.2 1.5 1.9 .5 ND DWP–S1–DW1 247 55.7 27.7 .89 21.9 ND ND .89 ND DWP–S1–DW2 420 61.6 19 ND 20.2 ND ND .32 ND DWP–S2–11 488 75.8 45 ND 24.5 ND .35 ND ND DWP–S2–16 494 60 30.4 .64 19.1 ND ND .42 .12 DWP–S2–18 520 59.2 21.3 .83 22.3 ND .12 .41 .57 DWP–S2–2 520 65 38.7 .78 21 ND ND .21 .41 DWP–S2–5 513 32.3 39.1 .59 18 ND ND 1.9 .18 DWP–S2–DW1 389 594 32.3 1.8 16.5 ND ND 1.4 ND DWP–S2–DW2 293 220 21.2 .69 15.4 ND ND .37 .083 DWP–S5–10 494 130 45.4 .65 24.4 1.6 1.8 ND .094 

37 
Jones, Braun, and Lee— Oxidation-Reduction Processes in Ground 

Water at Naval Weapons 

Industrial Reserve Plant, Dallas, Texas