Changes in Ground-Water Quality near 

Two Granular-Iron Permeable Reactive 

Barriers in a Sand and Gravel Aquifer, 

Cape Cod, Massachusetts, 1997–2000

By Jennifer G. Savoie, Douglas B. Kent, Richard L. Smith, 

Denis R. LeBlanc, U.S. Geological Survey, and 

David W. Hubble, University of Waterloo

Prepared in cooperation with the

AIR FORCE CENTER FOR ENVIRONMENTAL EXCELLENCE and the 

UNIVERSITY OF WATERLOO

Toxic Substances Hydrology Program

Water-Resources Investigations Report 03-4309

U.S. Department of the Interior

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

Gale A. Norton, Secretary

U.S. Geological Survey

Charles G. Groat, Director

U.S. Geological Survey, Reston, Virginia: 2004

For sale by U.S. Geological Survey, Information Services

Box 25286, Denver Federal Center

Denver, CO 80225

For more information about the USGS and its products:

Telephone: 1-888-ASK-USGS

World Wide Web: http://www.usgs.gov/

Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply 

endorsement by the U.S. Government.

Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Suggested citation:

Savoie, J.G., Kent, D.B., Smith, R.L., LeBlanc, D.R., and Hubble, D.W., 2004, Changes in ground-water quality near two 

granular-iron permeable reactive barriers in a sand and gravel aquifer, Cape Cod, Massachusetts, 1997–2000: U.S. 

Geological Survey Water-Resources Investigations Report 03-4309 , 77 p.
 iii

CONTENTS

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

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

Permeable Reactive Barriers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Geochemical Conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Monitoring Changes in Ground-Water Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Installation of Monitoring Wells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Well Selection and Sampling Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Ground-Water-Sample Collection and Field Water-Quality Measurements. . . . . . . . . . . . . . . . . . . 6

Water-Sample Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Ground-Water Quality Downgradient from the Permeable Reactive Barriers . . . . . . . . . . . . . . . . . . . . . 10

Observed Ground-Water Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Specific Conductance, Sodium, and Chloride. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Dissolved Oxygen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

pH and Alkalinity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Nitrate, Ammonium, and Sulfate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Total and Dissolved Organic Carbon, Dissolved Inorganic Carbon, and Methane . . . . . . . 14

Major Cations and Boron . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Dissolved Iron, Phosphorus, and Trace Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Tetrachloroethene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Changes in Ground-Water Quality. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Estimated Ground-Water Velocity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Effects of Zero-Valent-Iron Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Changes in Concentrations of Ground-Water Solutes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Dissolved Oxygen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Nitrate and Ammonium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Sulfate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Dissolved Inorganic Carbon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Methane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Arsenic, Manganese, Cobalt, and Phosphorus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Changes in Chemical Conditions Within the Zone Downgradient from the B-Wall. . . . . . . 23

Summary and Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

References Cited. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Appendix 1. The Robowell Automated Sampling System by Kirk P. Smith . . . . . . . . . . . . . . . . . . . . . . . . 77
iv 

FIGURES

1, 2. Maps showing: 

1. Locations of the granular-iron permeable reactive barrier test site, the 

Chemical Spill-10 plume, and the altitude of the water table, 

Cape Cod, Massachusetts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2. Locations of monitoring wells, the Robowell sampling system, and the A-wall 

and B-wall permeable reactive barriers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3. Longitudinal section along A-A′ showing the locations of monitoring wells and the 

A-wall and B-wall permeable reactive barriers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

4–9. Time-series plots of: 

4. Specific conductance at wells RW 24B-0104 and RW 27-0102A, and dissolved

chloride and sodium concentrations at well RW 24B-0104, July 1997 to 

February 2000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

5. Dissolved oxygen concentrations and pH at wells RW 24B-0104 and 

RW 27-0102A, and alkalinity at well RW 24B-0104, July 1997 to February 2000 . . . . . . . 13

6. Dissolved nitrate, ammonium, and sulfate concentrations at well RW 24B-0104, 

July 1997 to February 2000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

7. Dissolved organic carbon, dissolved inorganic carbon including carbon 

dioxide, and methane concentrations at well RW 24B-0104, July 1997 to 

February 2000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

8. Dissolved calcium, magnesium, potassium, boron, and sodium concentrations 

at well RW 24B-0104, July 1997 to February 2000. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

9. Dissolved iron, manganese, arsenic, cobalt, and phosphorus concentrations 

at well RW 24B-0104, July 1997 to February 2000. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

TABLES

1. Location coordinates, top-of-casing and well-screen altitudes, water levels, and 

distances downgradient from A- and B-walls for monitoring wells near the 

granular-iron permeable reactive barriers, Massachusetts Military Reservation, 

Cape Cod, Massachusetts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

2. Selected inorganic-solute concentrations for quality-control samples. . . . . . . . . . . . . . . . . . . 10

3. Limitations of quantitation and relative precisions and accuracies for inorganic 

solutes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

4. Field water-quality analyses for ground-water samples collected near the 

granular-iron permeable reactive barriers, 1997–2000. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

5. Selected field water-quality analyses for ground-water samples collected by the 

Robowell system at well RW 27-0102A near the granular-iron permeable reactive 

barriers, June 1998 to October 1999 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

6. Anions and ammonium analyses for ground-water samples collected near the 

granular-iron permeable reactive barriers, 1997–2000. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

7. Carbon species analyses for ground-water samples collected near the granular-iron 

permeable reactive barriers, 1997–2000. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

8. Major- and minor-element analyses for ground-water samples collected near the 

granular-iron permeable reactive barriers, 1997–2000. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

9. Trace-element analyses for ground-water samples collected near the granular-iron 

permeable reactive barriers, 1997–2000. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

10. Tetrachloroethene analyses for ground-water samples collected near the 

granular-iron permeable reactive barriers, 1997–2000. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
 v

CONVERSION FACTORS, VERTICAL AND 

HORIZONTAL DATUM, AND ABBREVIATIONS

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

°F = 1.8°C + 32

Multiply By To obtain

foot (ft) 0.3048 meter (m)

inch (in) 2.54 centimeter (cm)

gallon (gal) 3.785 liter (L)

liter per minute (L/min) 0.264 gallon per minute (gal/min)

mile (mi) 1.609 kilometer (km)

ton 907.2 kilogram (kg)

Aluminum [Al] (μM) 26.98 Aluminum [Al] (μg/L)

Ammonium [NH4] (μM) 14.01 Ammonium [NH4 as N] (μg/L)

Arsenic [As] (μM) 74.92 Arsenic [As] (μg/L)

Barium [Ba] (μM) 137.3 Barium [Ba] (μg/L)

Boron [B] (μM) 10.81 Boron [B] (μg/L)

Cadmium [Cd] (μM) 112.4 Cadmium [Cd] (μg/L)

Calcium [Ca] (μM) 40.08 Calcium [Ca] (μg/L)

Carbon, inorganic, dissolved [DIC] (μM) 12.01 Carbon, inorganic, dissolved [DIC] (μg/L)

Carbon, organic, dissolved [DOC] (μM) 12.01 Carbon, organic, dissolved [DOC] (μg/L)

Carbon, organic, total [TOC] (μM) 12.01 Carbon, organic, total [TOC] (μg/L)

Chloride [Cl] (μM) 35.45 Chloride [Cl] (μg/L)

Chromium [Cr] (μM) 52.00 Chromium [Cr] (μg/L)

Cobalt [Co] (μM) 58.93 Cobalt [Co] (μg/L)

Copper [Cu] (μM) 63.54 Copper [Cu] (μg/L)

Iron [Fe] (μM) 55.85 Iron [Fe] (μg/L)

Lead [Pb] (μM) 207.2 Lead [Pb] (μg/L)

Lithium [Li] (μM) 6.941 Lithium [Li] (μg/L)

Magnesium [Mg] (μM) 24.31 Magnesium [Mg] (μg/L)

Manganese [Mn] (μM) 54.94 Manganese [Mn] (μg/L)

Methane [CH4] (μM) 12.01 Methane [CH4 as C] (μg/L)

Molybdenum [Mo] (μM) 95.94 Molybdenum [Mo] (μg/L)

Nickel [Ni] (μM) 58.71 Nickel [Ni] (μg/L)

Nitrate [NO3] (μM) 14.01 Nitrate [NO3 as N] (μg/L)

Nitrite [NO2] (μM) 14.01 Nitrite [NO2 as N] (μg/L)

Oxygen, dissolved [O2] (μM) 31.99 Oxygen, dissolved [O2] (μg/L)

Phosphorus [P] (μM) 30.97 Phosphorus [P] (μg/L)

Potassium [K] (μM) 39.10 Potassium [K] (μg/L)

Silicon [Si] (μM) 28.09 Silicon [Si] (μg/L)

Sodium [Na] (μM) 22.98 Sodium [Na] (μg/L)

Strontium [Sr] (μM) 87.62 Strontium [Sr] (μg/L)

Sulfate [SO4] (μM) 96.06 Sulfate [SO4] (μg/L)

Tetrachloroethene [PCE] (μM) 165.8 Tetrachloroethene [PCE] (μg/L)

Uranium [U] (μM) 238.0 Uranium [U] (μg/L)

Vanadium [V] (μM) 50.94 Vanadium [V] (μg/L)

Zinc [Zn] (μM) 65.37 Zinc [Zn] (μg/L)
vi 

Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929 

(NGVD 29). Horizontal coordinate information is referenced to the North American Datum of 1927 

(NAD 27).

AFCEE Air Force Center for Environmental Excellence

amp ampere

BOMARC Boeing Michigan Aeronautical Reserach Center

cm centimeter

CS-10 Chemical Spill-10

DIC dissolved inorganic carbon

DOC dissolved organic carbon

ICPAES Inductively Coupled Plasma Atomic Emission Spectroscopy

L liter

MMR Massachusetts Military Reservation

μm micron or micrometer

μg/L micrograms per liter

μL microliter

μM micromoles per liter

μS/cm microsiemens per centimeter

mg/kg milligrams per kilogram

meq/L milliequivalents per liter

mL milliliter

mN milliNormal

mM millimoles per liter

min minute

N Normal

NWQL National Water Quality Laboratory

PCE tetrachloroethene

PRB permeable reactive barrier

PVC polyvinyl chloride

TOC total organic carbon

USGS U.S. Geological Survey

UTES Unit Training Equipment Site

VOC volatile organic compound
Changes in Ground-Water Quality near 

Two Granular-Iron Permeable Reactive 

Barriers in a Sand and Gravel Aquifer, 

Cape Cod, Massachusetts, 1997–2000

By Jennifer G. Savoie, Douglas B. Kent, Richard L. Smith, 

Denis R. LeBlanc, and David W. Hubble

Abstract

Two experimental permeable reactive barriers (PRBs) 

of granular zero-valent iron were emplaced in the path of a 

tetrachloroethene plume (the Chemical Spill-10 plume) at the 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 

in June 1998. The goal of the field experiment was to achieve 

emplacement of a granular-iron PRB deeper than attempted 

before. The PRBs were expected to create a reducing 

environment and degrade the tetrachloroethene by reductive 

dechlorination. The goal of the work presented in this report 

was to observe temporary and sustained changes to the 

ground-water chemistry downgradient from the PRBs.

A hydraulic-fracturing method involving injection of the 

granular iron with a guar-biopolymer and enzyme slurry was 

used to install the parallel 30- to 33-foot-wide wall-shaped 

barriers at a depth of 82 to 113 feet below land surface. An 

acetic acid and enzyme mixture was subsequently injected in 

wells near the barriers to degrade the guar biopolymer.

Prior to the emplacement, tetrachloroethene 

concentrations in the Chemical Spill-10 plume at the study 

area were as high as 250 micrograms per liter. Other water 

properties in the plume generally were similar to the properties 

of uncontaminated ground water in the area, which typically has 

dissolved oxygen concentrations of 250 to 375 micromoles 

per liter, pH of 5.5 to 6.0, and specific conductance of 60 to 

90 microsiemens per centimeter. 

Water-quality samples were collected periodically 

from monitoring wells near the PRBs to determine how the 

emplacement of the granular-iron walls altered the groundwater quality. In addition, an automated well-sampling device 

measured temperature, specific conductance, pH, and dissolved 

oxygen every 1–4 days for 16 months in a well downgradient 

from the two parallel PRBs. 

Temporary increases (lasting about 5 to 6 months) in 

specific conductance were observed downgradient from the 

PRBs as a result of the sodium chloride, potassium carbonate, 

and other salts included in the slurry and the acetic acid and 

enzyme mixture that was subsequently injected to degrade the 

guar biopolymer. Temporary increases in the concentrations of 

major cations (sodium, potassium, magnesium, and calcium) 

were observed downgradient from the PRBs, as were temporary 

but substantial increases in the dissolved and total organic 

carbon concentrations. Methane was detected, sulfate 

concentrations decreased temporarily, and concentrations of 

dissolved inorganic carbon increased in samples from wells 

downgradient from the PRBs.

A sustained (longer than 12 months) reducing 

environment, in which dissolved oxygen concentrations 

decreased to zero, the pH increased to about 6.8, and dissolved 

iron concentrations increased substantially, developed as a 

result of the oxidation (corrosion) of the granular iron; this zone 

persisted at least 65 feet downgradient from the PRBs. The 

pH and dissolved iron concentrations increased with distance 

from the granular-iron walls. Concentrations of arsenic, 

cobalt, manganese, and phosphorus increased, and nitrate 

concentrations were reduced to below the detection limit 

downgradient from the walls. A sustained decrease of 

tetrachloroethene concentrations was not observed; however, 

reductive dechlorination products were observed at wells 

downgradient from the PRBs during several rounds of 

sampling.

The emplacement of zero-valent iron in the aquifer to 

remove tetrachloroethene from the ground water caused 

changes in the water chemistry that persisted farther 

downgradient from the PRBs than has been observed at other 

sites because of the low chemical reactivity of the quartzdominated aquifer sediments and the low ambient dissolved 

chemical concentrations in the ground water. The small 

transverse dispersion in the aquifer and the probable long-term 

persistence of the iron indicate that the chemically altered zone 

probably will extend a substantial distance downgradient from 

the PRBs for a substantial period of time (years); further 

investigation would be needed to determine this distance.
2 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000

Introduction

Permeable reactive barriers (PRBs) containing zero-valent 

iron have been used to attenuate concentrations of ground-water 

contaminants at more than 50 sites in North America and 

Europe (Gillham, 1996; U.S. Environmental Protection 

Agency, 1998; Naftz and others, 2002b). Zero-valent iron PRBs 

have been installed to remove a variety of ground-water 

contaminants, including volatile organic compounds (VOCs) 

(O’Hannesin and Gillham, 1998; McMahon and others, 1999), 

hexavalent chromium (Cr(VI)) (Puls and others, 1999), nitrate, 

uranium, and other inorganic contaminants (Gu and others, 

2002; Morrison and others, 2002a; Naftz and others, 2002a). 

In 1998, the University of Waterloo and GeoSierra 

LLC (formerly Golder Sierra LLC), in cooperation with the 

Air Force Center for Environmental Excellence (AFCEE), 

installed two pilot-scale PRBs of zero-valent granular 

iron on the Massachusetts Military Reservation (MMR) 

on Cape Cod, Massachusetts. The PRBs were installed in the 

path of a plume of ground water contaminated with chlorinated 

solvents, referred to as the Chemical Spill-10 (CS-10) plume 

(fig. 1), that emanates from a site that has been used by the 

Army National Guard from 1978 to the present (2003) for the 

Unit Training Equipment Site (UTES) facility to store and 

maintain military vehicles. From 1962 to 1973, the site was 

used by the U.S. Air Force to house and maintain Boeing 

Michigan Aeronautical Research Center (BOMARC) groundto-air missiles and launcher systems. The primary source of 

contamination was chemical spills and releases that occurred 

at both facilities (Air Force Center for Environmental 

Excellence, 2003a). The principal contaminant of concern in 

the ground water near the source is tetrachloroethene (PCE) at 

concentrations as high as 250 μg/L (Hubble and Forbes, 1999). 

The source of contamination is near the top of the ground-water 

mound beneath western Cape Cod, where ground water flows 

radially from areas of recharge to areas of discharge at streams, 

ponds, and coastal bays, which are distant (miles) from the 

MMR (fig.1) (LeBlanc and others, 1986).

At the southern boundary of the UTES facility, the plume 

extends from about 80 to 120 ft below land surface and is about 

400 ft wide. The depth to water is about 80 ft below land 

surface, and the horizontal ground-water-flow rate is about 

0.4 ft/d (Hubble and Gillham, 2001). The unconfined aquifer is 

composed of medium to coarse sand and gravel, was deposited 

as glacial outwash, and is underlain by finer sand and silt at 

depth (Masterson and others, 1997). The unconsolidated 

sediments near the UTES facility are about 300 ft thick and 

overlie crystalline bedrock. The sediments are composed 

predominantly of quartz and feldspar minerals; no carbonate 

minerals are present (Barber and others, 1992).

Permeable Reactive Barriers

The pilot-scale experiment at the MMR was designed to 

test the emplacement of granular iron at depth for the 

removal of chlorinated solvents through creation of a reducing 

environment. Zero-valent iron reductively dechlorinates 

chlorinated solvents, including PCE, to less harmful chemicals 

(such as ethene, ethane, methane, and chloride ions) as the 

contaminated water moves through the permeable barrier 

(Gillham and O’Hannesin, 1994; Gillham, 1996). The 

experimental wall-shaped PRBs near the CS-10 source area 

were designed to be 50 ft wide each and to intersect the 

PCE contamination from 80 to 120 ft below land surface. 

Emplacement of granular-iron PRBs to similar depths had 

not been attempted previously at the time of the MMR 

emplacement. An innovative method—vertical hydraulic 

fracturing and injection—was used to install the two walls 

(Hubble and others, 1997; Hubble and Gillham, 2001).

The two parallel experimental PRBs were installed in June 

1998 by vertical hydraulic fracturing and injection in wells 

FW A1 and FW A2 for the A-wall, and FW B1 and FW B2 for 

the B-wall (fig. 2). The A-wall was constructed of 100 percent 

granular iron, and the B-wall was constructed of a mixture of 44 

percent granular iron and 56 percent sand by weight. The grain 

size of the granular iron and sand was selected so that the 

permeability of the PRB would be greater than that of the 

aquifer sediments. The PRBs were about 20 ft apart from each 

other and were oriented perpendicular to ground-water flow. 

Ground water from the PCE source was expected to flow 

through the A-wall first and then through the B-wall. Detailed 

information about the method of emplacement can be obtained 

from Hubble and Gillham (2001) and Hubble (2003).

In the vertical hydraulic-fracturing and injection method, a 

slurry of granular iron (and sand in the B-wall) and a waterbased biodegradable guar polymer amended with cellulase 

enzyme, sodium chloride, potassium carbonate, and sodium 

borate is injected under pressure into the aquifer. The injection 

is made through the casing of wells by use of a proprietary tool 

so that a vertical fracture filled with the slurry is created in the 

unconsolidated material. After emplacement, the gelatinous 

guar biopolymer is expected to break down by the action of the 

enzyme and to leave behind the permeable granular-iron or 

granular-iron and sand wall. Approximately 44 tons of iron 

were injected at the A-wall between June 4 and 25, 1998, and 

11 tons of the iron and sand mixture were injected at the B-wall 

on June 29 and 30, 1998. Problems were encountered with the 

injection, and the B-wall was only partially completed (Hubble 

and Gillham, 2001).
Introduction 3

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50

MILES

KILOMETERS

MASSACHUSETTS

41 ̊ 42'

30"

Base from U.S. Geological Survey digital data

Universal Transverse Mercator projection

Zone 19, 1:24,000, 1991

CAPE COD

41 ̊ 32'

30"

70 ̊37' 30" 70 ̊27' 30"

2 3 4

1 3 4

EXPLANATION

WATER-TABLE CONTOUR—Shows altitude of water table, March 1993. Contour interval is 

10 feet. Datum is NGVD 29 (from Savoie, 1995)

CAPE COD CANAL

MASSACHUSETTS MILITARY RESERVATION

BUZZARDS BAY

CAPE COD

BAY

VINEYARD SOUND

NANTUCKET SOUND

ATLANTIC

OCEAN

60

Study

area

CHEMICAL

SPILL-10

PLUME

Figure 1. Locations of the granular-iron permeable reactive barrier test site, the 

Chemical Spill-10 plume, and the altitude of the water table, Cape Cod, Massachusetts. 

Study area shown in figure 2.
4 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000

A'

MW 14B-0097 A

MW 14A-0124

RW 25E-0120 25A-0092

FW A2

RW 26-0106

RW 26-0100

RW 26-0092

RW 26-0096

RW 26-0087

RW 30-0096

RW 30-0117

RW 30-0100

RW 30-0106

RW 27-0102A (Robowell)

RW 29-0111 RW 29-0107

RW 28-0107

FW A1

25B-0099

25C-0105

25D-0110

BASE FROM CAPE SURV, DRAWING C196P4, 09/02/99,

N

24C-0110

24D-0115 24A-0100

24B-0104

RW 27-0098

RW 27-0102

RW 27-0108

RW 27-0120

RW 27-0114

RW 24-0094

FW B2

FW B1

RW 30-0087

RW 

Chain-link fence

RW

RW

GENERAL DIRECTION OF

GROUND-WATER FLOW

A-Wall

B-Wall

A A'

EXPLANATION

FW A2

RW 26-0087

0

0 15 METERS

10 20 30 40 50 FEET

5 10

LINE OF SECTION—Section 

 is shown in figure 3.

MONITORING WELL 

 AND IDENTIFIER

GEOPHYSICAL WELL

GEOPHYSICAL WELL—Used 

 for acetic acid and enzyme 

 injectionafter iron 

 emplacement

HYDRAULIC-FRACTURE

 WELL AND IDENTIFIER

Figure 2. Locations of monitoring wells, the Robowell sampling system, and the A-wall and B-wall permeable reactive 

barriers. Well locations are approximate (Hubble and Gillham, 2001). Site location is shown in figure 1. 
Introduction 5

On the basis of observations of the PCE and inorganic 

concentrations collected during the first 2 months after 

emplacement, it was concluded that the guar biopolymer 

in the A-wall had not broken down and that the ground 

water was flowing around the wall. To initiate the breakdown 

process, about 28,000 gallons of an enzyme and acetic acid 

solution with a pH of 3.3 to 3.5 were injected on September 12–

15, 1998, about 3 months after the A-wall was installed. 

The enzyme and acetic acid mixture was injected into eight 

monitoring wells within about 10 ft on either side of the A-wall 

and into the four hydraulic-fracturing wells at the A- and Bwalls (Hubble and Gillham, 2001). Subsequent observations, as 

discussed later in this report, indicated that the efforts to initiate 

breakdown of the guar in the A-wall were not successful. In 

subsequent PRB installations by this method at other sites, 

improved enzyme formulations have resulted in successful 

breakdown of the guar (Hubble, 2003, p. 22–23).

The geometry and location of the PRBs were verified 

by five methods, including inclinometer measurements 

of horizontal displacement of monitoring wells near 

the walls, hydraulic-pulse testing in wells near the walls, 

and two geophysical methods—active borehole resistivity 

measurements and cross-hole, common-depth radar scanning— 

in an array of observation wells surrounding the walls. All 

surveys were conducted before and after the PRBs were 

installed, so that background measurements could be compared 

to post-emplacement measurements. Magnetic-field anomaly 

profiling also was conducted in selected wells after the PRB 

emplacement. Results of the surveys indicated that the PRBs 

were installed approximately at the planned locations. The 

cross-hole, common-depth radar scanning indicated that the 

wall-shaped barriers are about 30 to 33 ft wide at a depth from 

82 to 113 ft below land surface, and that both walls have 

complex shapes (the A-wall had two separate zones) in the 

plane of the injections, although no holes were evident within 

the boundaries of either wall (Lane and others, 2001). More 

information about the verification testing can be obtained from 

Hubble and Gillham (2001) and Hubble (2003).

Geochemical Conditions

The emplacement of zero-valent iron alters the 

geochemical conditions in the aquifer. Although the purpose 

of the PRB is to remove the contaminants of concern, the 

geochemical changes that result may be of concern themselves, 

especially if the geochemically altered water reaches 

downgradient supply wells or surface waters. The Cape Cod 

pilot-scale tests provided a unique opportunity to examine the 

persistence of these changes downgradient from the PRBs. In 

contrast to other sites where zero-valent-iron PRBs have been 

emplaced, the CS-10 source area has unconsolidated sediments 

with fairly uniform hydraulic properties. In addition, the 

ground-water chemistry was, with the exception of PCE, typical 

of uncontaminated ground water in the Cape Cod aquifer, which 

is fully oxygenated, has low concentrations of dissolved salts 

(specific conductance of 60 to 90 μS/cm), and is mildly acidic. 

These conditions simplify assessment of the effect of the 

zero-valent iron PRBs on ground-water quality at the site.

From July 1997 to February 2000, the U.S. Geological 

Survey (USGS), in cooperation with AFCEE and the University 

of Waterloo, conducted a study to document the water-quality 

changes downgradient from the experimental PRBs. Groundwater samples were collected from 31 monitoring wells located 

near the PRBs (fig. 2). Four sets of samples were collected in 

1997 and 1998 before the PRBs were installed, and 12 sets of 

samples were collected during 1998–2000 after the PRBs were 

installed. An automated sampling device (Robowell) was 

installed in one monitoring well to monitor temperature, 

specific conductance, pH, and dissolved oxygen concentration 

every 1–4 days for 16 months after the iron was emplaced.

The purpose of this report is to present the analytical 

results from the ground-water sampling, to describe the major 

effects on the ground-water quality from the emplacement 

of the zero-valent iron in the aquifer, and to examine the

major processes leading to the observed changes. Additional 

information about the emplacement of the PRBs, methods 

used to verify the shape and continuity of the PRBs, field 

measurements made by the University of Waterloo, and 

concentrations of volatile organic compounds in ground water 

near the PRBs is contained in Hubble and Gillham (2001) and 

Hubble (2003). The lateral and vertical extents of the two PRBs 

as evaluated by a cross-hole, common-depth, radar-scanning 

method are described by Lane and others (2001).

Acknowledgments

The authors thank Edward Pesce and Rose Forbes of 

AFCEE and Robert Gillham of the University of Waterloo for 

their support and management of the project. The authors 

acknowledge the efforts of Deborah Repert and Seanne 

Buckwalter of the USGS National Research Program for 

sample analysis. The authors also thank Lindsay Anderson, 

Kimberly Campo, Patrick Craft, Shannon Dionne, Matthew 

Gamache, Abbie Given, Kathryn Hess, Sarah Hollinshead, Tara 

King, John Kliever, Naila Moreira, Ariane Mercadante, 

Timothy McCobb, Kevin Reisig, Jason Ruf, and Joseph 

Sawicki of the USGS for assistance in collecting water samples. 

The authors thank Leslie DeSimone of the USGS for assistance 

with the chemical interpretation, Gregory Granato of the USGS 

for assistance with the compilation of the data collected from 

the automated well-sampling device, Glenn Berwick, Richard 

Perkins, David Kraemer, and Timothy McCobb of the USGS 

for conducting the drilling-related activities, and Peter 

McMahon, Jennifer Joye, and Peter Church of the USGS for 

their helpful reviews of this manuscript.
6 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000

Monitoring Changes in 

Ground-Water Quality

Monitoring wells were installed and water samples were 

collected to observe the effects of the granular iron on the 

geochemical environment downgradient from the two walls. 

The monitoring methods included an automated well-sampling 

device (Robowell) that provided nearly continuous waterquality information. Water samples were analyzed by USGS 

laboratories and the University of Waterloo for various 

chemical species. 

Installation of Monitoring Wells

Monitoring wells were installed with a hollow-stem-auger 

drilling method. The wells were installed in clusters, with each 

well in a cluster screened at a different altitude. In some 

clusters, separate boreholes were drilled for each well oriented 

in a line perpendicular to flow (for example, the RW 30 cluster 

in fig. 2), whereas in other clusters, more than one well was 

installed in a single borehole (for example, the RW 25 cluster).

The monitoring wells were constructed with 2.0- or 

2.5-in.-diameter polyvinyl chloride (PVC) well casing and 

screens and finished at the land surface with protective steel 

casings. The aquifer material was allowed to collapse naturally 

around the casing and screen. Well clusters RW 26, 27, 28, 29, 

and 30 were installed with 2-ft-long screens, and well clusters 

MW 14, RW 24, and RW 25 were installed with 5-ft-long 

screens (except for well RW 24-0094, which has a 2-ft-long 

screen). Monitoring wells were installed upgradient and 

downgradient from the PRBs, and most are screened at the same 

vertical location as one or both of the PRBs (fig. 3). All wells 

were developed by pumping until the discharging water became 

clear. Monitoring-well information is given in table 1.

Twenty-five geophysical monitoring wells for the 

borehole-radar, active-resistivity, and inclinometer 

measurements also were installed with hollow-stem-auger 

drilling methods (fig. 2). The 3.0-in.-diameter PVC wells 

are screened across two intervals from about 85 to 105 ft 

and from 115 to 120 ft below land surface and are finished 

with protective steel casings at the land surface. The wells 

were installed with long screens (20 ft) so that they could be 

used for discrete-interval water sampling as described by 

Hubble (2003). 

Well Selection and Sampling Frequency

Water-quality samples were collected upgradient and 

downgradient from the PRBs as much as 12 months before and 

19 months after emplacement of the PRBs. The sampling 

frequency was weekly for about 2 months after the 

emplacement, and subsequently reduced to monthly and, 

later, to bimonthly. Sampling of all the well clusters at one 

time (as many as 30 wells) was done only twice—once about 

1 month prior to emplacement of the PRBs and a second 

time about 1 year after emplacement. Most of the other 

sampling rounds included collection of samples from wells 

in clusters RW 24, 25, and 30 (fig. 2). The RW 25 cluster is 

located upgradient of both PRBs. Wells RW 25B-0099 and 

RW 25C-0105 were sampled the most frequently of the RW 25 

wells because they are screened at about the same vertical 

interval as the highest initial PCE concentrations and greatest 

chemical changes observed downgradient from the PRBs. 

The RW 30 cluster was installed 5 ft downgradient from the 

A-wall about 1 month after the PRB was installed. Therefore, 

there are no water-quality data for the RW 30 cluster prior to 

the PRB emplacement. The RW 24 cluster is downgradient 

from both PRBs and intercepts the chemically reducing zone 

that developed after the PRB emplacements.

Well RW 27-0102A (fig. 2) was instrumented with 

an automated well-sampling device, known as Robowell 

(Granato and Smith, 1999), because the well is screened 

downgradient from both PRBs in the vertical interval 

with the highest initial PCE concentrations. Robowell began 

sampling the day the PRB emplacement began (June 4, 1998). 

Sampling frequency was daily for 1 month, then every other 

day for 11 months, then every fourth day until Robowell 

was deactivated about 16 months after the PRB emplacement 

when the dissolved oxygen concentration, pH, and specific 

conductance had been stable for about 7 months. Detailed 

information about the operation of Robowell can be found 

in Appendix 1.

Ground-Water Sample Collection and 

Field Water-Quality Measurements

Ground-water samples were collected from the monitoring 

wells using a Keck Model SP-81 submersible pump fitted 

with Teflon tubing and an isolation packer. The pump intake 

was set about 2 ft above the top of the screen and the packer 

was inflated to isolate the water in the casing above the 

packer from the pump intake. The pumping rate was about 

1 L/min, and a minimum of three casing volumes below the 

packer was evacuated before field water-quality measurements 

were made.

The field water-quality measurements—specific 

conductance, pH, temperature, dissolved oxygen, and 

turbidity—were monitored in grab samples until the 

measurements stabilized during purging. The specific 

conductance was measured with a HACH Model 44600 

or an Orion Model 126 conductivity meter. The pH was 

measured with an Orion Model 250A meter, an Orion Ross 

Sure-Flow Model 81-72 pH electrode, and an Orion 

stainless-steel, temperature-compensating probe. Dissolved 

oxygen concentrations greater than 32 μM were measured 

with a Yellow Springs Instruments Model 54 dissolved 

oxygen meter and electrode in the field or laboratory. 
Monitoring Changes in Ground-Water Quality 7

ALTITUDE, IN FEET ABOVE NGVD 29

0

100

150

20

40

60

80

Land

surface

Water table

MW 14RW 25RW 26RW 30RW 24RW 27-0102A(ROBOWELL)RW 27RW 28RW 29

EXPLANATION

WELL AND DEPTH OF BOTTOM OF SCREEN

PERMEABLE REACTIVE

BARRIER

GENERAL DIRECTION

OF GROUND-WATER FLOW

0

50

70

90

110

130

150

Iron Sand/Iron

mixture

A-Wall

B-Wall

A A'

97

97

92

87

87

96 100 98

94

102A

102

108 107 107

111

114

120

110

104

115

100

106

117

92

96

100

106

99

105

110

120 124

DEPTH BELOW LAND SURFACE, IN FEET

0 100 150 50

DISTANCE, IN FEET

Figure 3. Longitudinal section along A-A′ showing the locations of monitoring wells and the A-wall and B-wall permeable reactive 

barriers. Location of section is shown in figure 2. Note that the wall locations are approximate and that the well-screen locations are 

projected onto the section line without accounting for borehole deviation from the vertical (Hubble and Gillham, 2001) and may deviate 

as much as 5 feet laterally from the positions shown in the diagram.
8 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000 Table 1. Location coordinates, top-of-casing and well-screen altitudes, water levels, and distances downgradient from the A- and B-walls for monitoring wells near the granular-iron permeable reactive barriers, Massachusetts Military Reservation, Cape Cod, Massachusetts. [Locations of wells are shown in figure 2. The Robowell sampling system was installed in well RW 27-0102A. Altitudes are in feet relative to NGVD 29; locations are in feet relative to NAD 27. Distances from walls are in feet in the general direction of ground-water flow (minus indicates well is upgradient of wall). USGS, U.S. Geological Survey; --, no data] Well number Easting Northing Date installed Installed by Altitude, top of casing Altitude, top of well screen Altitude, bottom of well screen Date of water-level measurement Altitude of water level Distances from A-Wall B-Wall MW 14B-0097 863119.5 249326.8 8-11-89 Mathes 152.35 57.8 52.8 6-23-99 69.21 -53 -73 MW 14A-0124 863126.4 249323.4 8-22-89 Mathes 152.66 30.8 25.8 -- -- -53 -73 RW 24-0094 863086.4 249242.9 7-28-97 USGS 149.00 57.27 55.31 6-22-99 69.14 38 18 RW 24A-0100 863089.0 249241.5 12-22-96 Dragin Drilling 149.03 54.2 49.2 -- -- 38 18 RW 24B-0104 863089.0 249241.5 12-22-96 Dragin Drilling 148.93 50.1 45.1 -- -- 38 18 RW 24C-0110 863083.7 249244.7 12-23-96 Dragin Drilling 149.37 44.6 39.6 -- -- 38 18 RW 24D-0115 863083.7 249244.7 12-23-96 Dragin Drilling 149.33 39.6 34.6 -- -- 38 18 RW 25A-0092 863116.8 249310.3 10-05-96 Dragin Drilling 149.74 63.2 58.2 6-23-99 69.18 -35 -55 RW 25B-0099 863116.8 249310.3 10-05-96 Dragin Drilling 149.70 55.8 50.8 -- -- -35 -55 RW 25C-0105 863116.8 249310.3 10-06-96 Dragin Drilling 149.70 49.8 44.8 -- -- -35 -55 RW 25D-0110 863116.8 249310.3 10-06-96 Dragin Drilling 149.70 45.0 40.0 -- -- -35 -55 RW 25E-0120 863111.6 249312.2 10-06-96 Dragin Drilling 149.15 34.7 29.7 -- -- -35 -55 RW 26-0087 863113.5 249289.4 7-28-97 USGS 148.99 67.22 65.27 6-23-99 69.19 -15 -35 RW 26-0092 863107.4 249291.6 7-28-97 USGS 149.14 59.82 57.86 -- -- -15 -35 RW 26-0096 863110.5 249290.9 7-28-97 USGS 149.13 55.54 53.59 -- -- -15 -35 RW 26-0100 863104.6 249292.8 7-24-97 USGS 149.14 51.76 49.81 -- -- -15 -35 RW 26-0106 863101.8 249293.9 7-24-97 USGS 149.18 45.53 43.57 -- -- -15 -35 RW 27-0098 863084.7 249226.5 7-23-97 USGS 148.58 53.25 51.3 6-22-99 69.14 55 35 RW 27-0102 863082.0 249227.7 7-23-97 USGS 148.68 49.38 47.42 -- -- 55 35 RW 27-0102A 863081.3 249232.8 7-23-97 USGS 151.35 49.39 47.43 -- -- 50 30 RW 27-0108 863079.3 249229.4 7-23-97 USGS 148.95 43.67 41.71 -- -- 55 35 RW 27-0114 863074.6 249232.2 7-16-97 USGS 148.67 37.48 35.53 -- -- 55 35 RW 27-0120 863077.1 249230.6 7-16-97 USGS 148.76 31.29 29.34 -- -- 55 35 RW 28-0107 863073.5 249215.4 5-20-98 USGS 149.01 43.92 41.95 4-06-99 69.25 70 50 RW 29-0107 863067.5 249202.3 5-20-98 USGS 148.79 44.05 42.09 4-06-99 69.25 85 65 RW 29-0111 863063.6 249203.4 5-21-98 USGS 148.93 40.11 38.14 -- -- 85 65 RW 30-0087 863103.2 249270.8 7-17-98 USGS 149.09 64.21 62.24 6-21-99 69.12 5 -15 RW 30-0096 863100.9 249272.0 7-17-98 USGS 149.04 55.41 53.44 -- -- 5 -15

RW 30-0100 863096.5 249274.4 7-16-98 USGS 149.07 51.21 49.25 -- -- 5 -15RW 30-0106 863094.2 249275.3 7-16-98 USGS 149.10 45.46 43.51 -- -- 5 -15RW 30-0117 863098.6 249273.2 7-16-98 USGS 149.22 34.35 32.39 -- -- 5 -15
Monitoring Changes in Ground-Water Quality 9

In the field, the electrode was inserted in a flow-through 

chamber attached directly to the pump discharge line. In the 

laboratory, the electrode was inserted into a biological oxygen 

demand bottle that had been filled in the field by placing the 

discharge line at the bottom of the bottle and overfilling the 

bottle by three volumes. Dissolved oxygen concentrations less 

than 32 μM were measured in the field with a quantitative 

colorimetric method (CHEMetrics VVR Photometer and selffilling reagent ampoules K-7503 or K-7553). Temperature was 

measured by using the YSI dissolved oxygen electrode in the 

flow-through chamber or the Orion stainless-steel temperature 

probe in conjunction with the pH probe. Turbidity was 

measured with a HACH Model 2100P portable turbidimeter. 

Alkalinity was determined in the field by an incremental 

titration method (Fishman and Freidman, 1989) and a HACH 

digital titrator.

Samples for analysis of cations, anions, metals, nitrate, and 

ammonium were filtered through an in-line 0.45-μm Gelman 

capsule filter; samples for analysis of dissolved organic carbon 

(DOC) were filtered through a 0.45-μm silver filter. The cations 

and metals samples were preserved with nitric acid to pH less 

than 2, the ammonium samples were preserved with sulfuric 

acid to pH less than 2, and the anion samples were frozen. 

Unfiltered samples for analysis of VOCs and total organic 

carbon (TOC) were collected into 40-mL and 125-mL amber 

glass bottles, respectively, and preserved by chilling. Water 

samples for analysis of dissolved gases (methane (CH4) and 

dissolved inorganic carbon including carbon dioxide (DIC)) 

were collected into a syringe directly from the pump discharge 

line, and 15 mL were injected into a pretreated 30-mL serum 

bottle through a 22-gauge needle. The serum bottles had 

been prepared by adding 400 μL of 18N H2SO4, sealing with 

thick butyl rubber septa and crimps, and then flushing with 

ultra-high-purity-grade helium for 10 min. 

The pump and sample-collection equipment were 

decontaminated after sampling each well with laboratory-grade 

deionized water to prevent cross contamination from well to 

well. About 5 gal (about 6 times the internal volume of the 

pump and discharge line) of water were pumped through the 

pump and discharge line; the pump and line exterior were also 

rinsed with laboratory-grade deionized water. This method for 

decontamination was shown to be sufficient by analysis of the 

equipment-rinsewater samples (Savoie and LeBlanc, 1998; 

Hubble and Gillham, 2001).

Water-Sample Analysis

Most of the water samples were analyzed by the USGS 

National Research Program laboratories in Boulder, CO, and 

Menlo Park, CA. One round of samples, collected on May 19 

and 20, 1998, prior to emplacement of the walls, was also 

analyzed for major cations, anions, and dissolved organic 

carbon by the USGS National Water-Quality Laboratory 

(NWQL) in Lakewood, CO, according to the USGS methods 

and protocols described in Wershaw and others (1987) and 

Fishman and Friedman (1989). 

Anions, methane, DIC, DOC, and TOC concentrations 

were determined for water samples from the wells by the 

USGS National Research Program laboratory in Boulder, CO. 

Anions (nitrate, chloride, and sulfate) were analyzed by ion 

chromatography (Dionex Model DX-500) by using a Dionex 

AS15 Ion Pac analytical column and an AG15 guard 

column with 34 mN KOH eluant at a flow rate of 2 mL/min. 

Ammonium was analyzed by ion chromatography (Dionex 

Model DX-300) by using a Dionex CS12A Ion Pac analytical 

column and a CG12A guard column with a gradient elution of 

2.5 to 25 mN H2SO4 at a flow rate of 1.5 mL/min. Nitrite was 

quantified colorimetrically with a flow-injection autoanalyzer 

as described by Antweiler and others (1996). Methane was 

analyzed by gas chromatography with a flame-ionization 

detector by using a headspace equilibration technique (Smith 

and others, 1991b), and DIC was analyzed by using an infrared 

detector as described by Smith and others (1991a). DOC and 

TOC were analyzed by the heated persulfate oxidation method 

as described by Barber (1998). 

Concentrations of selected inorganic solutes were 

determined for water samples from the wells by the USGS 

National Research Program laboratory in Menlo Park, CA. The 

elements were analyzed by inductively coupled plasma atomic 

emission spectroscopy (ICPAES). Relative precision and 

accuracy for samples collected on or before September 18, 

1997, are given in Coston and others (1998). 

Samples collected after September 18, 1997, were 

analyzed on a Thermo Jarrell Ash IRIS AP-DV-S Advantage. 

The instrument was standardized as described in Coston and 

others (1998). A quality-control sample (QAQC 1), with 

approximate concentrations given in table 2, was analyzed 

periodically (usually every 16 samples). The instrument was 

restandardized if the concentrations of selected elements 

deviated by more than 10 percent from the value in the 

quality-control standard. An additional standard was analyzed 

periodically to assess instrument performance for major, minor, 

and trace elements at concentrations observed in ground-water 

samples or, for elements rarely detected, at concentrations near 

their detection limit (QAQC 2, table 2). Relative precisions and 

accuracies (table 3) were determined from 26 analyses of 

QAQC 1 and 15 analyses of QAQC 2 conducted in the 3 months 

during which all samples collected after September 18, 1997, 

were analyzed.
10 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000

Additional standards were analyzed to determine the extent to 

which solutes associated with emplacement of the PRBs 

affected the quality of the inorganics data. Neither acetic acid 

nor sodium at concentrations encountered during this study 

affected the precision or accuracy of the analyses of any of the 

elements in tables 2 and 3. Iron did not affect precision or 

accuracy at concentrations of 180 μΜ, but the precision and 

accuracy for arsenic, boron, cadmium, molybdenum, and nickel 

at concentrations in QAQC 2 (table 3) deteriorated considerably 

at iron concentrations of 850 μΜ. The precision and accuracy 

of these elements in the presence of 850 μΜ iron improved 

appreciably, however, as their concentrations were increased 

above those in QAQC 2.

PCE and other VOC concentrations were measured by the 

University of Waterloo, Ontario, Canada. The water samples 

were analyzed by using a gas chromatograph with an electron 

capture detector as described by Hubble and Gillham (2001).

Ground-Water Quality 

Downgradient from the Permeable 

Reactive Barriers

Ground-water quality was changed by both the 

emplacement of the guar biopolymer slurry and granular zerovalent iron used to form the walls, and by the subsequent 

injection of the acetic acid and enzyme solution used to degrade 

the biopolymer. Water-quality data from wells RW 24B-0104 

and RW 27-0102A are used in this section as the primary means 

to illustrate the water-quality changes caused by the PRB 

emplacement. Well RW 24B-0104, which is about 38 and 18 ft 

Table 2. Selected inorganic-solute concentrations for qualitycontrol samples.

[QAQC, quality-control sample; μM, micromoles per liter]

Element QAQC 1

(μM)

QAQC 2

(μM)

Aluminum 7.4 1.4

Arsenic 2.7 .15

Barium .72 .035

Boron 9.2 2.2

Cadmium .9 .009

Calcium 125 60

Chromium 1.9 .2

Cobalt 1.7 .08

Copper 1.6 .15

Iron 20 .17

Lead 4.8 .081

Lithium 7.2 .07

Magnesium 82 40

Manganese 1.8 .17

Molybdenum 2.1 .12

Nickel 1.7 .16

Phosphorus 65 18

Potassium 51 25

Silicon 89 100

Sodium 430 240

Strontium 1.1 .27

Uranium .84 1.0

Vanadium 2.0 .5

Zinc 1.5 .15

Table 3. Limitations of quantitation and relative precisions and 

accuracies for inorganic solutes

[LOQ, Limitation of quantitation; QAQC, quality-control sample; 

μM, micromoles per liter]

Element LOQ

(μM)

QAQC 1 QAQC 2

Relative 

precision

Relative 

accuracy

Relative 

precision

Relative 

accuracy

Aluminum 1.9 10 104 10 125

Arsenic .13 3 90 20 100

Barium .00073 3 100 3 100

Boron .28 2 96 11 106

Cadmium .009 2 100 13 108

Calcium .5 9 98 9 101

Chromium .20 4 102 20 101

Cobalt .020 4 101 6 97

Copper .050 5 99 19 99

Iron .090 4 100 10 108

Lead .072 2 99 10 98

Lithium .03 4 110 10 106

Magnesium 4.1 4 99 2 102

Manganese .035 2 99 3 99

Molybdenum .021 3 91 6 92

Nickel .051 4 101 9 106

Phosphorus 1.6 5 97 6 103

Potassium 5.1 4 95 4 102

Silicon .9 5 91 3 93

Sodium 2.2 5 101 7 108

Strontium .0057 4 106 4 109

Uranium .13 5 101 4 104

Vanadium .06 4 96 5 108

Zinc .038 4 98 4 99
Ground-Water Quality Downgradient from the Permeable Reactive Barriers 11

downgradient from the A- and B-walls, respectively (figs. 2 and 

3), was among the most frequently sampled wells during the 

study. Water-quality data from this well are representative of 

the reducing conditions observed downgradient from the 

B-wall. Field water-quality measurements collected by the 

Robowell system for well RW 27-0102A, which is located 

about 50 and 30 ft downgradient from the A- and B-walls, 

respectively (figs. 2 and 3), also indicate ground-water-quality 

changes associated with the emplacement of the PRBs.

Observed Ground-Water Quality

Temporary and sustained changes in the ground-water 

quality were monitored by field water-quality measurements 

and chemical analysis of water samples collected from the 

monitoring wells. The results of the field measurements and 

laboratory analyses are reported in tables 4–10, at the back of 

the report. Sampling rounds designated “pre” in the data tables 

were collected before the iron was emplaced, and sampling 

rounds designated “post” were collected after the iron was 

emplaced. Laboratory methods and analytical precision 

changed over the course of the study for some elements; 

therefore, detection limits for some elements, such as arsenic, 

iron, and phosphorus, varied. 

Specific Conductance, Sodium, and Chloride

Measurements of specific conductance of water samples 

collected from monitoring wells are reported in tables 4 and 5. 

Concentrations of chloride and sodium are reported in tables 6 

and 8, respectively. Increases in specific conductance were 

expected because sodium chloride and other salts were added to 

the slurry. The timing of the release of the sodium chloride from 

the gelatinous guar biopolymer is not known precisely because 

of the uncertainty concerning the breakdown of the guar.

The specific conductance measured in well RW 27-0102A 

increased temporarily from background values of 65 to 

70 μS/cm to greater than 900 μS/cm during the first 7 months 

following the initial PRB emplacement (fig. 4 and table 5). 

Two peaks in specific conductance were observed (929 μS/cm 

on September 30, 1998, and 841 μS/cm on December 21–23, 

1998). The first peak occurred 118 days after the start of 

emplacement of the A-wall (June 4, 1998) and 92 days after the 

end of emplacement of the B-wall (June 30, 1998). The 

temporary increase in specific conductance at well RW 27-

0102A lasted about 6 months.

An increase in the specific conductance, accompanied by 

increases in sodium and chloride concentrations, also was 

observed at well RW 24B-0104, where conductances increased 

from background values of 80 to 90 μS/cm to greater than 1,000 

μS/cm (fig. 4). Only one peak of increased specific conductance 

was observed at the RW 24 cluster. The absence of a second 

peak at the RW 24 cluster may be due to the sampling 

frequency, local heterogeneity of hydraulic properties, or the 

configuration of the monitoring wells relative to the locations of 

the PRBs, or a combination of these possibilities. The frequency 

of sample collection at wells farther downgradient than RW 27-

0102A was limited; however, an increase in specific 

conductance relative to background values of 80 to 90 μS/cm 

was observed as far downgradient as well cluster RW 29, the 

cluster that is the farthest from the two PRBs (85 and 65 ft 

downgradient from the A- and B-walls, respectively) (tables 1 

and 4).

An anomalously high concentration of chloride 

(1,693 μM) observed at well RW 24B-0104 on Sept. 17, 1997 

(fig. 4), before the PRBs were installed, was accompanied by 

smaller increased concentrations of sodium. The cause of the 

temporary increase is unknown.

Dissolved Oxygen

The dissolved oxygen concentration decreased from an 

average background concentration of 312 μM to zero at well 

RW 24B-0104 by about 4 months after the emplacement 

of the granular iron (fig. 5 and table 4). Dissolved oxygen 

concentrations remained at zero for the remainder of the 

study at the RW 24 cluster except in well RW 24D-0115 (the 

deepest well in the cluster), where concentrations returned to 

background concentrations (338 μM). Anoxic conditions were 

also observed farther downgradient at well RW 27-0102A 

(fig. 5 and table 5), in the three shallowest wells (RW 27-0098, 

-0102, and -0108) at the RW 27 cluster, and in the wells in 

clusters RW 28 and RW 29 (table 4). These results indicate that 

anoxic conditions persisted more than 65 ft downgradient from 

the B-wall 1 year after the wall’s emplacement.

Samples from some wells in the RW 30 cluster, which is 

between the two walls and 5 ft downgradient from the A-wall 

(figs. 2 and 3), showed a temporary decrease to low or 

zero dissolved oxygen concentrations after the granular-iron 

emplacement and the enzyme and acetic acid injection, and then 

an increase to concentrations typical of background conditions 

(250–350 μM) (table 4). The absence of a persistent decrease 

in dissolved oxygen concentrations below background 

concentrations only 5 ft downgradient from the A-wall 

indicated that the guar biopolymer had not broken down and 

that ground water was not flowing through the wall, but more 

likely around it.

Dissolved oxygen concentrations from samples at well 

RW 30-0096 did not follow the pattern of samples from the 

wells described above. Water sampled from this well was 

anoxic when collected shortly after the well was installed 

following emplacement of the PRBs; dissolved oxygen 

concentrations then slowly increased to about 150 μM near the 

end of the study. Well RW 30-0096 was determined to deviate 

7.1 ft northward from its map-view position at land surface 

(fig. 2), and may have been augered through the A-wall (Hubble 

and Gillham, 2001). Although the well screen may be located 

upgradient of the A-wall, dissolved oxygen concentrations are
12 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000

M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M

1997 1998 1999 2000

0

200

400

600

800

1,000

1,200

1,400

SPECIFIC CONDUCTANCE,

IN MICROSIEMENS PER CENTIMETER

RW 24B-0104

RW 27-0102A (Robowell)

Iron Injection

Period

Enzyme and Acetic Acid Injection

M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M

1997 1998 1999 2000

0

5,000

1,000

2,000

3,000

4,000

CONCENTRATION, IN MICROMOLES PER LITER

CHLORIDE

SODIUM

SPECIFIC CONDUCTANCE

Figure 4. Time-series plots of specific conductance at wells RW 24B-0104 and RW 27-0102A, and 

dissolved chloride and sodium concentrations at well RW 24B-0104, July 1997 to February 2000.

lower than background concentrations; this result indicates that 

some granular iron could have been carried northward to the 

screen location when the augers possibly penetrated the wall.

pH and Alkalinity

The pH increased from about 5.7 to 6.7 in well RW 24B0104 within 4 months after the initial emplacement of the 

granular iron (fig. 5 and table 4). The pH remained near 6.8 in 

the RW 24 cluster for the remainder of the study, except in well 

RW 24D-0115, where the pH returned to about background 

values (pH of about 5.1). A temporary decrease in pH caused

by the enzyme and acetic acid injection was observed at the 

two deepest wells at the RW 24 cluster (RW 24C-0110 and 

RW 24D-0115) during sampling on October 27, 1998, about 

1.5 months after the injection, with pH values decreasing to 

almost 5.

Increased pH values also were observed at well RW 27-

0102A (fig. 5 and table 5), in the three shallowest wells at the 

RW 27 cluster, and in the wells at the RW 28 and RW 29 

clusters (table 4). These results indicate that the zone of 

increased pH persisted at least 65 ft downgradient from the 

B-wall 1 year after the wall’s emplacement.

The pH in the RW 30 cluster located between the walls 

varied considerably with depth. The pH increased to almost 7 in 

well RW 30-0096 after the emplacement of the PRBs (table 4). 

The low pH (from 3.3 to 3.5) of the enzyme and acetic acid 

solution injected on September 12, 1998, however, caused the 

pH to decrease to about 4.5 to 5 in the four deepest wells 

(RW 30-0096, -0100, -0106, and -0117) in the cluster in the 

October 1998 sampling sets. The pH then returned to about 

background values at the RW 30 cluster, except at well RW 30-

0096, where the pH remained at about 6.5; the increased pH 

may reflect the presence of zero-valent iron at this well screen. 
Ground-Water Quality Downgradient from the Permeable Reactive Barriers 13

M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M

1997 1998 1999 2000

400

0

100

200

300

CONCENTRATION, IN MICROMOLES PER LITER

Iron Injection

Period

Enzyme and Acetic Acid Injection

M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M

1997 1998 1999 2000

4

8

5

6

7

pH, IN STANDARD UNITS

0

8

2

4

6

ALKALINITY, IN MILLIEQUIVALENTS PER LITER

RW 24B-0104 ALKALINITY

RW 24B-0104 pH

RW 27-0102A (Robowell) pH

RW 24B-0104

RW 27-0102A (Robowell)

DISSOLVED OXYGEN

Figure 5. Time-series plots of dissolved oxygen concentrations and pH at wells RW 24B-0104 and RW 27-

0102A, and alkalinity at well RW 24B-0104, July 1997 to February 2000

Substantial peaks in alkalinity were observed during 

the study. The alkalinity increased from about 0.07–0.2 to 

5–7 meq/L in the RW 24 cluster (except in the shallowest well, 

RW 24-0094) after the enzyme and acetic acid injection (fig. 5 

and table 4). The alkalinity then decreased to about 2 meq/L in 

wells RW 24A-0100 and RW 24B-0104 and to background 

values in well RW 24D-0115 (the deepest well in the cluster) 

about 6 months after the enzyme and acetic acid injection. 

Increased alkalinity also was observed in the RW 30 cluster, 

with values reaching a maximum of 8.7 meq/L in RW 30-0096 

and then decreasing to background values (less than 1 meq/L).

The substantial peaks in alkalinity are closely associated 

with acetate derived from the acetic acid injection, which 

complicates the use of the alkalinity data in interpreting effects 

of the granular iron on water quality. Acetate, which contributes 

to the alkalinity, was generated by reactions between the aquifer 

sediments and the acetic acid that was injected into the aquifer. 

The relative concentrations of acetic acid and acetate present in 

the aquifer at a given location depend on the pH. Concentrations 

of acetic acid and acetate are approximately equal at pH 4.7. At 

higher pH values, the concentration of acetate is greater than 

that of acetic acid. For example, the lowest pH value observed 

at any of the RW 24 wells was 5.04 (RW 24C-0110 on October 

27, 1998; table 4); at this pH, the ratio of acetate to acetic acid 

is approximately 2.2:1. Although acetic acid was injected into 

the aquifer, proton sorption and consumption (mostly by the 

aquifer sediments) had converted most of the acetic acid to 

acetate by the time it was transported to the RW 24 wells, which 

was reflected in the increased alkalinity. 
14 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000

Because the alkalinity changes were dominated by the 

acetate and provide little information on the chemical effects of 

the granular iron, alkalinity measurements were discontinued 

about 6 months after the enzyme and acetic acid injection. 

Concentrations of dissolved inorganic carbon including carbon 

dioxide provide data that are much more useful for interpreting 

processes that caused the observed changes in aquifer 

chemistry.

Nitrate, Ammonium, and Sulfate

Analyses of the major anions and ammonium are shown in 

table 6. The nitrate concentrations decreased in well RW 24B0104 from an average of 55 μΜ just before emplacement of the 

granular iron to below the detection limit within about 4 months 

(fig. 6 and table 6). The decrease began before the enzyme and 

acetic acid injection. Nitrate concentrations remained below the 

detection limit for about 1 year, until the last two sample sets of 

the study, which were collected in January and February 2000. 

Decreased nitrate concentrations also were observed farther 

downgradient at the RW 27, RW 28, and RW 29 clusters; thus, 

the zone of decreased nitrate values extended at least 65 ft 

downgradient from the B-wall 1 year after the wall’s 

emplacement.

A steady increase in ammonium from background 

concentrations (below the detection limit of 5.0 μM) to about 

19 μM was observed at RW 24B-0104 beginning about 

7 months after emplacement of the granular iron (fig. 6). 

Increased ammonium concentrations also were observed at

the RW 27 and RW 30 clusters and in wells RW 28-0107 and 

RW 29-0107. Ammonium concentrations above the detection 

limit were also observed occasionally at the RW 25 cluster 

upgradient of the A-wall (table 6); the cause of the ammonium 

increases at this cluster is unknown. 

Sulfate concentrations in well RW 24B-0104 decreased 

from an average background concentration of 83 μM to 

below the detection limit about 40 days after the enzyme 

and acetic acid injection (fig. 6), but returned to background 

concentrations by November 1999. The temporary decrease in 

sulfate concentrations was also observed at the other wells in 

the RW 24 cluster (table 6).

Total and Dissolved Organic Carbon, 

Dissolved Inorganic Carbon, and Methane

Total organic carbon and dissolved organic carbon 

concentrations were expected to increase because of the 

injections of the guar biopolymer, enzyme, and acetic acid. 

The biodegradation of the injected organic matter and the 

presence of carbonate that was added to the injected slurry were 

expected to increase dissolved inorganic carbon concentrations. 

The carbon species analyses are reported in table 7. DOC 

concentrations in well RW 24B-0104 increased temporarily 

from about 40–100 μΜ to greater than 16,000 μΜ (fig. 7), and 

TOC concentrations increased from about 40–100 μΜ to 

greater than 13,000 μΜ after emplacement of the PRBs. 

Even greater increases of DOC and TOC were observed at the 

RW 30 cluster between the two walls, where maximum 

concentrations of DOC and TOC exceeded 58,000 μΜ and 

63,000 μΜ, respectively. DOC concentrations decreased to 

near background values about 6 months after the enzyme and 

acetic acid injection. TOC analyses were discontinued after 

October 1998 because the exceedingly high carbon content 

posed substantive analytical problems in the laboratory. 

DIC concentrations at well RW 24B-0104 increased from 

about 1 mM to 4.6 mM in the 4 months after emplacement of 

the PRBs (fig. 7). Concentrations increased at the other wells of 

the RW 24 cluster and remained above background values 

(about 1 mM) except in the deepest well, RW 24D-0115, where 

DIC returned to near background concentrations (table 7) by 

March 25, 1999, the last sampling date for DIC. It is not known 

if the increased DIC concentrations persisted at the other RW 24 

wells after this date.

Methane concentrations increased in samples from the 

three shallowest wells (RW 24-0094, RW 24A-0100, and 

RW 24B-0104) of the RW 24 cluster about 130 days after 

the enzyme and acetic acid injection. In well RW 24-0094, 

concentrations increased from below the detection limit to 

greater than 140 μΜ. Methane concentrations in well RW 30-

0096, the well thought to penetrate the A-wall, also increased, 

reaching 34 μΜ methane on March 24, 1999. Methane samples 

were not collected after March 25, 1999; therefore, it is not 

known if the increased methane concentrations persisted 

beyond that date.

Major Cations and Boron

Concentrations of boron, calcium, magnesium, potassium, 

sodium, and other species are reported in table 8. Increased 

sodium concentrations were observed at well RW 24B-0104 

downgradient from the B-wall following emplacement of the 

granular iron (fig. 8). The increased sodium concentrations 

were accompanied by increased concentrations of calcium, 

magnesium, potassium, and boron (fig. 8). Concentrations of 

these elements decreased to almost background values within 

about 8 months after the PRBs were installed, although 

potassium concentrations remained slightly elevated (about 

50 μM) above background levels (about 25 μM) at RW 24B0104 in comparison to sodium, calcium, and magnesium 

concentrations; this observation is consistent with results of 

earlier studies showing that potassium is retarded by ionexchange reactions more extensively than other major cations 

(Ceazan and others, 1989; Kent and others, 2002a). 
Ground-Water Quality Downgradient from the Permeable Reactive Barriers 15

M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M

1997 1998 1999 2000

100

0

20

40

60

80

CONCENTRATION, IN MICROMOLES PER LITER

NITRATE

SULFATE

AMMONIUM

NITRATE AND AMMONIUM

DETECTION LIMIT

Iron Injection

Period

Enzyme and Acetic Acid Injection

M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M

1997 1998 1999 2000

0

200

50

100

150

CONCENTRATION, IN MICROMOLES PER LITER

SULFATE DETECTION LIMIT

Figure 6. Time-series plots of dissolved nitrate, ammonium, and sulfate concentrations at well 

RW 24B-0104, July 1997 to February 2000.

Dissolved Iron, Phosphorus, and 

Trace Elements

The reducing geochemical environment downgradient 

from the PRBs was expected to affect the concentrations of 

dissolved iron, manganese, phosphorus, and some trace metals. 

Iron, manganese, and phosphorus concentrations are reported in 

table 8. Arsenic, cobalt, and other trace metal concentrations are 

reported in table 9. 

Large increases in dissolved iron concentrations were 

observed downgradient from the PRBs. Dissolved iron 

concentrations increased from approximately the detection 

limit (0.09 μM) to greater than 3,300 μM in well RW 24B-0104 

after emplacement of the B-wall (fig. 9). Concentrations 

decreased to about 380 to 850 μM about 6-7 months after the 

emplacement and persisted thereafter at these values. Increased 

dissolved iron concentrations also were observed at all the other 

downgradient sites (table 8), and, thus, the zone of dissolved 

iron extended at least 65 ft downgradient from the B-wall 1 year 

after the wall’s emplacement. 

Increases in the concentrations of manganese, cobalt, and 

arsenic were observed in well RW 24B-0104 downgradient 

from the B-wall (fig. 9). Arsenic and cobalt concentrations in 

the well increased from less than the detection limit (0.13 μM 

and 0.020 μM, respectively) to maximum values of 0.542 μM 

and 3.70 μM, respectively, and remained at elevated, although 

lower, values for the remainder of the study.
16 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000

M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M

1997 1998 1999 2000

0

20,000

5,000

10,000

15,000

CONCENTRATION, IN MICROMOLES PER LITER

Iron Injection

Period

Enzyme and Acetic

Acid Injection

M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M

1997 1998 1999 2000

0

5,000

1,000

2,000

3,000

4,000

DISSOLVED INORGANIC CARBON INCLUDING

CARBON DIOXIDE, 

IN MICROMOLES PER LITER 

0

50

10

20

30

40

METHANE, IN MICROMOLES PER LITER

METHANE

DISSOLVED ORGANIC

CARBON

DISSOLVED INORGANIC

CARBON

Figure 7. Time-series plots of dissolved organic carbon, dissolved inorganic carbon including carbon dioxide, and 

methane concentrations at well RW 24B-0104, July 1997 to February 2000.

Phosphorus concentrations (table 8) also increased 

after emplacement of the granular iron. Phosphorus 

concentrations in well RW 24B-0104 (fig. 9) increased from 

less than the detection limit to a maximum value of about 

13 μM; concentrations then decreased to about 7–8 μM and 

persisted at these values for the remainder of the study.

Tetrachloroethene

Tetrachloroethene (PCE) (table 10) was the primary VOC 

of interest because its concentrations were substantially above 

the U.S. Environmental Protection Agency (EPA) maximum 

contaminant level (5 μg/L) (U.S. Environmental Protection 

Agency, 2002). Concentrations of PCE in wells upgradient 

of the PRBs varied during the study, although PCE 

concentrations generally decreased from June 1998 to February 

2000. An increase in upgradient concentrations to almost preemplacement values was measured in June 2001 by AFCEE 

(Hubble and Gillham, 2001), after data collection for this study 

had ended. Variable PCE concentrations also were measured in 

the wells downgradient from the PRBs. The VOC data indicate 

that there was no degradation attributable to the upgradient 

A-wall. As stated previously, ground water may have been 

flowing around the A-wall rather than through it. 

PCE concentrations measured by AFCEE in December 

2000 and June 2001 (data in Hubble and Gillham, 2001), after 

completion of this study, were lower in wells downgradient 

from the B-wall than in the upgradient wells. Also, the 

degradation product cis-1,2-DCE was found in some wells 
Ground-Water Quality Downgradient from the Permeable Reactive Barriers 17

CONCENTRATION, IN MICROMOLES PER LITER

M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M

1997 1998 1999 2000

0.1

10,000

1

10

100

1,000

EXPLANATION

CALCIUM

MAGNESIUM

POTASSIUM

BORON

SODIUM

Iron Injection

Period

Enzyme and Acetic Acid Injection

Figure 8. Time-series plots of dissolved calcium, magnesium, potassium, boron, and sodium concentrations 

at well RW 24B-0104, July 1997 to February 2000.

downgradient from the B-wall during the period from June 1999 

to December 2000. These data indicate that partial degradation 

of the PCE by reductive dechlorination may be occurring in the 

B-wall (Hubble and Gillham, 2001). 

Changes in Ground-Water Quality

The objective of this study was to document the effects of 

granular zero-valent iron PRBs on ground-water quality. In 

addition to sustained effects (lasting longer than 12 months), 

there were short-term effects (lasting about 5 to 6 months) 

owing to emplacement of each PRB and to the subsequent 

injection of acetic acid to induce breakdown of the guar 

biopolymer in the A-wall. These short-term effects complicate 

understanding of the potential sustained effects on water 

quality. In addition to the short-term effects, the observed 

chemical changes varied considerably among the wells, perhaps 

as a result of local aquifer heterogeneity. In addition, the 

sparseness of the monitoring network vertically and 

horizontally relative to the size of the PRBs resulted in 

considerable difficulty in relating the changes observed among 

the wells. The permeability contrast between the A-wall and the 

surrounding aquifer and its effect on ground-water flow also 

potentially affected the observed chemical changes, although 

ground-water-flow simulations indicated that the general flow 

pattern was altered only slightly as flowlines wrapped tightly 

around the poorly permeable wall. Despite these complications, 

various trends were evident from an analysis of the waterquality data.

Estimated Ground-Water Velocity

The arrival time of the first peak in specific conductance at 

well RW 27-0102A (fig. 4) can be used to estimate the groundwater velocity at the site. Because the increase in specific 

conductance at the well began before the enzyme and acetic 

acid injection took place, the initial increase must have been 

caused by the sodium chloride and other salts included in the 

slurry mixtures. The guar biopolymer in the A-wall may not 

have degraded (Hubble and Gillham, 2001); therefore, the first 

conductivity peak at well RW 27-0102A probably is a result of 

the B-wall injection. The peak arrived at the well on September 

30, 1998, about 92 days after the emplacement of the B-wall. 

This well is about 30 ft downgradient from the B-wall, so the 

estimated ground-water velocity is calculated to be about

0.3 ft/d. This value agrees reasonably well with the groundwater velocity of 0.4 ft/d estimated by using Darcy’s Law and 
18 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000

MJ J ASOND J FMAMJ J ASOND J FMAMJ J ASOND J FM

1997 1998 1999 2000

0.01

10,000

0.1

1

10

100

1,000

0.01

10,000

0.1

1

10

100

1,000

CONCENTRATION, IN MICROMOLES PER LITER

IRON

MANGANESE

Iron Injection

Period Enzyme and Acetic

Acid Injection

MJ J ASOND J FMAMJ J ASOND J FMAMJ J ASOND J FM

1997 1998 1999 2000

CONCENTRATION, IN MICROMOLES PER LITER

ARSENIC

COBALT

PHOSPHORUS

Arsenic Detection Limit

Cobalt Detection Limit

Iron Detection Limit

Phosphorus Detection 

 Limit

Manganese Detection

 Limit

Figure 9. Time-series plots of dissolved iron, manganese, arsenic, cobalt, and phosphorus concentrations at well RW 24B0104, July 1997 to February 2000. Arsenic data point <1.3 μg/L on November 24, 1998, not plotted because of uncertain 

detection limit.

water levels measured in nearby monitoring wells, an estimated 

hydraulic conductivity of 225 ft/d, and an estimated porosity of 

0.37 (Hubble and Gillham, 2001).

The second conductivity peak at well RW 27-0102A 

probably was the result of the acetic acid and enzyme injection 

because the peak coincides with low chloride concentrations 

observed at other nearby wells (fig. 4). This injection did not 

contain additional salts, as was the case with the slurry mixture 

used to emplace the iron. Acetic acid at a concentration of 6 to 

28 mM (calculated based on the target pH range of 3.3 to 3.5) 

was injected near the PRBs during a 3-day period (September 

12–15, 1998). It has been reported that pulses of low-pH ground 

water injected elsewhere in the Cape Cod aquifer have induced 

elevated cation concentrations through mineral-dissolution and 

ion-exchange reactions (Kent and others, 2002a). These 

reactions eventually caused the pH at these sites to return to 

background values, but the reactions also created a peak of 

increased alkalinity and concentrations of sodium and other 

cations that traveled in a conservative, non-reactive fashion 

(Kent and others, 2002b). The same trend can be seen at well 

RW 24B-0104 downgradient from the PRBs as a peak in 

specific conductance on November 24, 1998, that coincided 

with low chloride concentrations. The ground-water velocity 

calculated from the arrival of the second conductivity peak at 

well RW 27-0102A is about 0.4–0.5 ft/d. The good agreement 

between these values and that estimated from the average 

hydraulic conductivity and regional hydraulic gradient 

indicates that the emplacement of the PRBs did not have a 

substantial overall effect on average ground-water-flow rates 

through the study area.
Ground-Water Quality Downgradient from the Permeable Reactive Barriers 19

Effects of Zero-Valent-Iron Corrosion

Zero-valent iron (Fe) spontaneously reduces water to 

hydrogen gas. This reaction will be referred to as the Fe 

corrosion reaction in this discussion; the reaction can be 

written as

Fes + 2H+ = Fe2+ + H2 . (1)

Although reaction 1 is written with hydrogen ion (H+) 

as the oxidant, H2O is the ultimate oxidant (Reardon, 1995). 

Through sustained production of H2 and Fe(II) (iron in the plus 

two oxidation state) and consumption of H+ (thus raising the 

pH), the Fe corrosion reaction has a substantial effect on 

ground-water quality downgradient from zero-valent-iron 

PRBs.

Increases in Fe(II) concentrations at the RW 24 wells 

downgradient from the PRBs coincided with increases in 

chloride concentrations (figs. 4 and 9, and tables 6 and 8). This 

observation indicates that Fe(II) was produced rapidly after 

emplacement of the granular iron, sand, and guar mixture to 

form the B-wall. In contrast, at other sites where granular-iron 

PRBs were emplaced (with or without guar biopolymer), 

substantial Fe(II) concentrations were not observed in wells 

adjacent to the PRBs until long after emplacement (Puls and 

others, 1999; Gu and others, 2002).

The changes in pH measured at the RW 24 wells after 

emplacement of the B-wall (fig. 5) also differed from those 

reported at other sites with granular zero-valent-iron PRBs. 

Data from the RW 24 wells show no change from ambient pH 

values for about 3 months after the emplacement of the B-wall, 

after which the pH increased to higher values that subsequently 

remained constant. At other sites where granular-iron PRBs 

were installed, pH values in samples from wells adjacent to the 

PRBs either remained constant at ambient values after 

emplacement (Puls and others, 1999; Gu and others, 2002; 

Morrison and others, 2002a) or increased continuously after 

emplacement (Naftz and others, 2002a).

The delay in arrival of elevated pH values relative to 

dissolved iron at the RW 24 wells (figs. 5 and 9) is consistent 

with pH buffering by reactions at the mineral surfaces of the 

aquifer sediments (Mayer and others, 2001; Kent and others, 

2002b). The lack of substantial retardation of Fe(II) within the 

Cape Cod sand and gravel aquifer between the B-wall and the 

RW 24 wells indicates that there was minimal adsorption of 

Fe(II) on the aquifer sediments, as would be expected from the 

low pH values (5.5 to 5.8) in the ground water and known weak 

adsorption of Fe(II) at surfaces of minerals like ferrihydrite 

(Appelo and others, 2002). Ferrihydrite serves as a reasonable 

model for the minerals that coat the sediments in the shallow 

part of the Cape Cod aquifer and result in the adsorption of ions 

onto the mineral surfaces (Davis and others, 1998; Kent and 

others, 2002a).

Data from monitoring wells at this and other sites indicate 

that increases in the Fe(II) concentrations and pH driven by the 

Fe corrosion reaction are counteracted by other reactions within 

the PRBs. As pH values within granular-iron PRBs increase, 

aqueous Fe(II) undergoes further reactions that produce H+, 

including adsorption (Zachara and others, 2000; Appelo and 

others, 2002) and precipitation (Gu and others, 1999; Mayer 

and others, 2001; Ritter and others, 2002). The dominant Fecontaining corrosion products found in granular-iron PRBs 

emplaced under oxic or oxidizing conditions are Fe(III) 

oxyhydroxides such as akageneite and goethite (Phillips and 

others, 2000; Roh and others, 2000; Morrison and others, 

2002b). This reaction can be written as

4Fe2+ + O2 + 6H2O = 4FeOOHs + 8H+. (2)

Formation of these Fe(III) oxyhydroxides requires dissolved 

oxygen (or another strong oxidizing agent such as Cr(VI) or 

nitrate). Data from the RW 30 wells indicate that ground water 

upgradient of the B-wall had dissolved oxygen concentrations 

that were close to atmospheric equilibrium, except for brief 

periods after emplacement of the walls and within the pulse of 

acetic acid injected to attempt to break down the guar 

biopolymer in the A-wall (table 4). In addition to Fe(III) 

oxyhydroxides, mixed solids with both Fe(II) and Fe(III), such 

as magnetite (Fe(II)Fe(III)2O4, written from this point on as 

Fe3O4) and green rust (Fe(II)4Fe(III)2(OH)12SO4, written from 

this point on as Fe6(OH)12SO4), have been identified in 

granular-iron PRBs; similar to reaction 2, the reactions that 

form these products consume dissolved oxygen and produce 

H+. Fe(II) sulfide and hydroxide, as well as carbonate minerals, 

also have been shown to precipitate in granular-iron PRBs (Puls 

and others, 1999; Phillips and others, 2000; Roh and others, 

2000; Morrison and others, 2002b). In this study, the almost 

constant pH values (fig. 5) indicate that a steady state between 

the Fe corrosion reaction and the suite of precipitation reactions 

within the B-wall was achieved after a short time (1 to 2 

months). The almost constant Fe concentrations observed at the 

RW 24 wells (fig. 9) indicate that reaction 1, in combination 

with reactions between the granular iron and ground-water 

solutes (see “Changes in Concentrations of Ground-Water 

Solutes” section), produced an amount of dissolved Fe(II) in 

excess of the dissolved oxygen available from the incoming 

ground water.

Changes in Concentrations of 

Ground-Water Solutes

The substantial changes in concentrations of dissolved 

oxygen, nitrate, ammonium, sulfate, methane, dissolved 

inorganic carbon, and trace elements that were observed in 

ground water downgradient from the PRBs also can be related 

to chemical processes initiated by the emplacement of the 

barriers.
20 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000

Dissolved Oxygen

The loss of dissolved oxygen during transit through the Bwall (fig. 5) likely resulted primarily from oxidation of Fe(II) 

(reaction 2). However, microbial metabolism cannot be ruled 

out as a factor contributing to the observed loss of oxygen. This 

reaction can be written as

CH2O + O2 = H2CO3. (3)

CH2O is used to represent organic matter in reaction 3 because 

it reasonably depicts the stoichiometric relationship between 

reactants and products (Morel and Hering, 1993). Potential 

sustained sources of organic carbon include breakdown 

products released slowly from the guar biopolymer and, to a 

much lesser extent, impurities in the granular iron and sand 

forming the B-wall.

Nitrate and Ammonium

The observed disappearance of nitrate (fig. 6) is consistent 

with previous studies that have shown that granular-iron PRBs 

have the capacity to remove nitrate from ground water (Mayer 

and others, 2001; Gu and others, 2002). Laboratory studies have 

shown that the removal mechanism can be abiotic reduction of 

nitrate to ammonium by granular iron or its corrosion products 

(Hansen and others, 1996; Ottley and others, 1997; Huang and 

others, 1998; Till and others, 1998), or microbial reduction to 

gaseous products (nitrogen (N2) and nitrous oxide (N2O)) 

driven by H2 produced as a result of Fe corrosion (Till and 

others, 1998).

Abiotic reduction of nitrate by granular iron can be written 

as

4Fes + NO3

-

 + 10H+ = 4Fe2+ + NH4

+ + 3H2O. (4)

Stoichiometric relations between reactants and products of 

abiotic reduction of nitrate by corrosion products, such as green 

rust, can be represented (Hansen and others, 1996) as 

4Fe6(OH)12SO4,s + NO3

-

= 8Fe3O4,s + NH4

+ + 4SO42- + 6H+ +19H2O , (5)

where magnetite is the iron-containing product. 

Microbial reduction of nitrate to nitrogen gas 

(denitrification), where nitrate serves as the terminal electron 

acceptor, can be written as

5H2 + 2NO3

-

 + 2H+ = N2 + 6H2O. (6)

Denitrification has been shown to be an important process in 

suboxic and anoxic ground water in the MMR Ashumet Valley 

plume, located about 3 mi south of the study area (Smith 

and others, 1991a; Smith and others, 1996). Degradation of 

organic matter drives denitrification in the Ashumet Valley 

plume (Smith and Duff, 1988), but H2 may be an important 

intermediate in denitrification (Lovley and others, 1994; Smith 

and others, 1994). The breakdown of the guar biopolymer 

could be the source of organic matter at the PRB site. The 

stoichiometry of denitrification driven ultimately by 

degradation of organic matter can be written as

5CH2O + 4NO3

-

 + 4H+ = 5H2CO3 + 2N2 + 2H2O. (7)

A second microbial process, dissimilatory nitrate reduction, can 

also reduce nitrate to ammonium. However, the major microbial 

end-product of nitrate reduction in the Cape Cod aquifer is N2

(Smith and others, 1991a).

The appearance of ammonium at all wells downgradient 

from the B-wall (fig. 6 and table 6) indicates that the observed 

loss of nitrate resulted primarily from abiotic reactions 

(reactions 4 and 5). Ammonium concentrations increased above 

background values of about 5 μM beginning in March 1999, but 

were substantially lower than nitrate concentrations prior to the 

onset of anoxic conditions (fig. 6). Ammonium has a high 

affinity for ion-exchange sites on the Cape Cod aquifer 

sediments, and the participation of ammonium in ion-exchange 

reactions could account, at least in part, for the observed 

attenuation of ammonium relative to nitrate concentrations 

(Ceazan and others, 1989). Participation of ammonium in ionexchange reactions could also account for the observed lag 

between the disappearance of nitrate and appearance of 

ammonium (fig. 6).

Although abiotic nitrate reduction was likely the primary 

nitrate-consuming reaction, microbial nitrate reduction may 

have accounted for part of the observed nitrate disappearance. 

An experimental study of nitrate reduction by zero-valent iron 

indicated that abiotic and microbial nitrate reduction can occur 

simultaneously and at similar rates at pH values below 10. The 

metabolic activity of denitrifiers was inhibited at pH values 

higher than 10 (Till and others, 1998). Increased populations of 

anaerobic microorganisms capable of reducing nitrate have 

been observed adjacent to at least one zero-valent-iron PRB (Gu 

and others, 2002). Values of pH greater than 10 have been 

observed within zero-valent-iron PRBs, but these high pH 

values appear to be restricted to narrow zones within the PRBs 

and to early times after emplacement (Puls and others, 1999; 

Mayer and others, 2001; Gu and others, 2002; Morrison and 

others, 2002a). It is likely that zones in and adjacent to zerovalent-iron PRBs where metabolic activities of denitrifiers 

would be inhibited by elevated pH values are small compared to 
Ground-Water Quality Downgradient from the Permeable Reactive Barriers 21

regions with elevated H2 concentrations capable of stimulating 

the growth of denitrifiers. The increase in nitrate concentrations 

in the RW 24 wells after November 1999 indicates a 

deterioration in the nitrate-reducing capacity of the B-wall over 

time, similar to what has been observed elsewhere (Gu and 

others, 2002).

Sulfate

The temporary loss of sulfate downgradient from the PRBs 

(fig. 6) may have resulted from precipitation of corrosion 

products or from sulfate reduction. The stoichiometry of the 

precipitation of corrosion products can be represented by the 

formation of sulfate green rust, which can be written as

12Fe2+ + O2 + 2SO4

2- + 22H2O 

= 2Fe6(OH)12SO4,s + 20H+. (8)

The incorporation of sulfate into corrosion products like 

green rust involves consumption of oxygen and Fe(II) and 

the production of H+. Experimental studies have suggested that 

abiotic reduction of sulfate by zero-valent iron does not occur at 

time scales relevant to transport through these PRBs (Huang 

and others, 1998; Morrison and others, 2002a). Laboratory 

studies have shown that H2 generated by Fe corrosion 

stimulates microbial sulfate reduction (Gu and others, 1999) 

and can be written as

4H2 + SO4

2- + 2H+ = H2S + 4H2O. (9)

Field investigations generally have supported the 

conclusion that sulfate reduction at zero-valent-iron PRBs is 

biologically mediated (Puls and others, 1999; Rowland, 2002). 

Alternatively, microbial sulfate reduction may have been 

stimulated by acetate from the acetic acid injected to promote 

breakdown of the guar biopolymer in the A-wall. The reaction 

can be written as

CH3CO2

-

 + SO4

2- + 3H+ = H2S + 2H2CO3. (10)

Reactions 9 and 10 show that sulfate reduction stimulated 

by H2 or acetate produces hydrogen sulfide and consumes H+. 

It is unlikely that dissolved sulfide would have been present at 

detectable concentrations downgradient from the PRBs at the 

MMR. High concentrations of Fe(II) and high pH values within 

the PRBs would cause the precipitation of Fe(II) sulfide (Puls 

and others, 1999; Gu and others, 2002). Although the pH 

downgradient from the B-wall increased, as expected from 

reactions 9 and 10, it is difficult to distinguish the effect on pH 

of reactions involving sulfate from that caused by other 

reactions. 

In contrast to reactions 8 and 9, sulfate reduction by 

acetate (reaction 10) yields DIC, which is the sum of 

concentrations of dissolved carbon dioxide, bicarbonate, and 

carbonate. However, it can be shown that the increase in DIC 

concentrations caused by sulfate reduction linked to microbial 

growth on acetate is too small to be detected. An increase in the 

DIC concentration of 3.6 mM was observed at well RW 24B0104; this increase coincided approximately with the peak in 

DOC from the acetic acid injection (fig. 7). Large increases in 

DIC concentrations were also observed at other RW 24 wells 

(table 7). If the observed decrease in sulfate concentration was 

caused entirely by sulfate reduction stimulated by acetate 

oxidation, then the increase in DIC resulting from the reduction 

of 80 μM sulfate (the approximate background sulfate 

concentration; see fig. 6) would be 160 μM. Therefore, the 

possible production of DIC by reaction 10 is so small compared 

to the DIC production by other reactions that changes in DIC 

cannot be used to help determine the relative importance of 

reaction 10 in the observed decrease in sulfate concentrations.

Sulfate concentrations increased after the transport of 

acetic acid and acetate past well RW 24B-0104 (shown as the 

peak in DOC concentrations in fig. 7). This observation may 

indicate that sulfate reduction linked to acetate was an 

important reaction contributing to the observed loss of sulfate 

(figs. 6 and 7). Sulfate concentrations at well RW 24B-0104 

increased to approximately 100 μM by the end of the study 

period (fig. 6). These concentrations are similar to those 

observed at this well prior to emplacement of the PRBs, but are 

lower than those observed in wells upgradient of the PRBs after 

emplacement of the walls. Therefore, the sand/iron PRB may be 

continuing to remove a portion of the incoming sulfate, either 

by precipitation of corrosion products or by microbial sulfate 

reduction.

Dissolved Inorganic Carbon

The only oxidation-reduction reactions that can lead to 

increased DIC concentrations are microbial metabolic reactions 

linked to the degradation of organic compounds. Thus, changes 

(or lack thereof) in the DIC should help determine the relative 

importance of these reactions. In order to minimize the 

variability in the data resulting from spatial and temporal 

variability in concentrations, the following discussion is 

restricted to the period between September and December 1998, 

when the injection of acetic acid and, possibly, partial 

breakdown of the guar biopolymer, provided sufficient organic 

carbon to stimulate microbial metabolism. DIC concentrations 

increased in a downgradient direction from approximately 

1.3 mM at the RW 30 wells between the walls to approximately 

2.8 mM at all but the shallowest RW 24 wells located 18 ft 

downgradient from the B-wall. Thus, the DIC concentration 

increased by approximately 1.5 mM as ground water flowed 

through the B-wall. 
22 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000

Comparison of the increase in DIC to decreases in 

concentrations of electron acceptors (dissolved oxygen, nitrate, 

iron(III), and sulfate) places constraints on the extent to which 

the observed increase in DIC resulted from microbial metabolic 

processes. The maximum decrease in dissolved oxygen 

concentrations over the distance between the RW 30 and RW 24 

clusters (approximately 32 ft) in the September-December 1998 

time period was 300 μM. Given that much of the decrease in 

dissolved oxygen concentration likely resulted from reactions 

with the zero-valent iron and its corrosion products, the increase 

in DIC concentrations corresponding to oxygen metabolism 

was much less than 300 μM. The maximum decrease in nitrate 

concentrations between the RW 30 and RW 24 sites during this 

period was approximately 120 μM. This decrease would yield a 

maximum of 150 μM DIC, but the actual yield was much less 

because of the importance of abiotic nitrate reduction to 

ammonium. Sulfate concentrations decreased about 70 to 

120 μM, which would yield a maximum of 140 to 240 μM of 

DIC (reaction 10). These calculations show that metabolic 

processes linked to oxygen, nitrate, and sulfate account for 

production of much less than 690 μM DIC. Note that 

measurable methane production was not evident until after 

December 1998 (fig. 7). Therefore, at least 0.81 mM and 

probably more than 1 mM of DIC production cannot be 

accounted for by microbial metabolism linked to these terminal 

electron acceptors. It is unlikely that metabolism linked to 

iron reduction can account for the excess DIC production. 

Generation of 1 mM DIC would result in production of 4 mM 

Fe(II), which is much more Fe(II) production than observed, 

especially considering that much of the observed dissolved iron 

(II) likely resulted from corrosion of the zero-valent iron.

Carbonate, in the form of a potassium carbonate solution, 

was added to the slurry mixture to adjust its pH during the 

emplacement of the PRBs (Hubble and Gillham, 2001). This 

added carbonate likely contributed substantially to the observed 

excess DIC. Water into which the guar biopolymer and enzyme 

were added in the initial stages of preparing the slurry was 

adjusted to pH 10. Although the concentration of potassium 

carbonate added is unknown, it can be estimated from the target 

pH to be approximately 200 μM. Additional carbonate, 

estimated to be equivalent to a concentration of about 1.2 mM, 

was added along with the granular iron. Therefore, an 

equivalent concentration of about 1.4 mM carbonate was 

added to the aquifer with the injected slurry. In addition to 

contributing to elevated DIC values, leaching of carbonate from 

the PRB also would result in elevated values of alkalinity.

The chemical forms of carbonate in the PRBs are 

unknown. Compositions of ground water observed at all RW 24 

wells indicated undersaturation with respect to calcite by at 

least a factor of 10 throughout the study period. It is possible 

that higher pH values within the PRBs, however, either during 

preparation of slurries to be injected or after emplacement, 

could have resulted in precipitation of one or more carbonate 

minerals.

Methane

Increased methane concentrations were observed in most 

RW 24 wells after the passage of the acetic acid and acetate 

peak (fig. 7 and table 7). These increases likely resulted from 

microbial methanogenesis stimulated either by the acetic acid 

injection or by the H2 produced by the Fe corrosion reaction 

(Weathers and others, 1997). Ground water at the RW 24 wells 

generally was anoxic and had zero or low nitrate concentrations, 

but substantial sulfate concentrations were observed at all 

depths. Interestingly, substantial concentrations of both 

methane and Fe were observed in the presence of dissolved 

oxygen, nitrate, and sulfate in well RW 30-0096. The cause of 

this co-occurrence of both oxidized and reduced substances is 

unknown, but it may indicate that acetate, H2, or both, 

stimulated microbial activity in discrete zones whose vertical 

extents were less than the 2-ft interval over which this well is 

screened. These zones could be related to the possible 

penetration of this well through the A-wall.

Arsenic, Manganese, Cobalt, and Phosphorus

Arsenic concentrations downgradient from the B-wall 

increased after the onset of anoxic conditions, the increase in Fe 

concentrations, and the increase in pH values (figs. 5 and 9). 

Comparison with other studies of arsenic concentrations and 

mobility in ground water supports the hypothesis that the 

observed increase in arsenic concentrations resulted from 

release of naturally occurring sediment-bound arsenic in 

response to the new chemical conditions resulting from 

reactions between granular iron and the ground water. Elevated 

concentrations of arsenic (above background concentrations) 

have been observed in many aquifers where ground water with 

anoxic conditions and neutral to alkaline pH values comes in 

contact with sediments that are not particularly high in arsenic 

(for example, 1–20 mg/kg) compared to the average abundance 

in the earth’s crust (approximately 1.8 mg/kg) (Smedley and 

Kinniburgh, 2002). These elevated concentrations likely result 

from reductive dissolution of iron oxyhydroxides associated 

with the sediments, which have a high affinity for adsorption of 

both arsenic(V) and arsenic(III), or also from the reduction of 

sediment-bound arsenic(V) to arsenic(III), which has a lower 

affinity for adsorption onto aluminum oxyhydroxides and 

aluminosilicates than does arsenic(V). An anoxic, ironcontaining zone located from about 700 to 1,000 ft 

downgradient from the former disposal beds at the MMR 

wastewater-treatment facility and within the Ashumet Valley 

plume contains concentrations of arsenic(III) similar to those 

reported here; arsenic(V) injected into this zone in the Ashumet 

Valley plume was reduced rapidly to arsenic(III) (Hoehn and 

others, 2001). Arsenic(V) can be reduced abiotically by sulfide 

(Rochette and others, 2000) or by anaerobic microorganisms 

capable of using arsenic(V) as a terminal electron acceptor, with 

either organic matter or H2 as the electron donor (Ahmann and 

others, 1997; Oremland and others, 2001). Sulfide may have 
Ground-Water Quality Downgradient from the Permeable Reactive Barriers 23

been present after the onset of anoxic conditions, organic matter 

could have been present because of the breakdown of the guar 

biopolymer in the B-wall, and H2 was present because 

of the corrosion reaction. The observed increase in arsenic 

concentrations after installation of the PRBs is interesting 

because of the proposed use of granular-iron PRBs for 

removing arsenic from contaminated ground water (Morrison 

and others, 2002a), in part because of extensive adsorption of 

arsenic(V) onto oxyhydroxides in iron-corrosion products 

(Farrell and others, 2001). This latter observation indicates that, 

although the injected PRB material cannot be ruled out as a 

source of the observed arsenic, it is unlikely that arsenic would 

have escaped the reactive material in the PRB.

Concentrations of cobalt (Co) and manganese (Mn) 

also increased after emplacement of the PRBs (fig. 9). The 

peaks in Mn and Co concentrations observed on November 24, 

1998, at well RW 24B-0104, which coincide with peaks in 

the concentrations of the major cations (fig. 8), are consistent 

with similar reported increases associated with ion-exchange 

reactions induced by an increase in sodium and potassium 

concentrations (Kent and others, 2002a).

After the peaks associated with ion exchange passed by 

well RW 24B-0104, Co and Mn concentrations remained 

substantially higher than concentrations prior to emplacement 

of the PRBs (fig. 9). Although the zero-valent iron cannot be 

ruled out as a source of the higher concentrations of these trace 

metals, it is likely that the higher concentrations resulted from 

release of the elements from the sediments because of reducing 

conditions that formed downgradient from the sand/iron PRB. 

Elevated concentrations of manganese have been observed in 

the suboxic (dissolved oxygen concentration below 30 μM) and 

anoxic zones of the Ashumet Valley plume (Kent and others, 

1994; Davis and others, 2000); such concentrations are 

consistent with expected concentrations from microbial 

oxidation-reduction reactions (Lee and Bennett, 1998). Cobalt 

concentrations similar to those reported near the PRBs also 

have been observed in the anoxic zone of the Ashumet Valley 

plume (Savoie and LeBlanc, 1998).

The increased phosphorus concentrations (fig. 9) likely 

resulted from mobilization of sediment-bound phosphate. 

Adsorption of phosphate on iron and aluminum oxyhydroxides, 

which occur as coatings on mineral grains and dominate the 

adsorption properties of the sediments, decreases with 

increasing pH. Therefore, the higher pH values caused by the 

iron-corrosion reaction would be expected to cause a decrease 

in the extent to which phosphate adsorbs on the sediments, 

thereby increasing its concentration in ground water and its 

mobility. Microbial reductive dissolution of iron oxyhydroxides 

in coatings on grain surfaces after the onset of anoxic conditions 

also may have contributed to the release of phosphate from 

sediments, as well as that of arsenic, and possibly other trace 

elements.

Changes in Chemical Conditions Within the 

Zone Downgradient from the B-Wall

Comparison of water-quality data from the RW 24 and 

RW 27 wells (approximately 18 and 35 ft downgradient from 

the B-wall, respectively) indicates that further reactions, 

possibly stimulated by the H2 generated by iron corrosion, 

occurred in the geochemically altered zone downgradient from 

the B-wall. Values of pH measured in February 2000 increased 

over a distance of about 17 ft from about 6.7-6.8 at the RW 24 

wells to 6.9-7.0 at RW 27 wells (table 4). Dissolved iron 

concentrations measured in February 2000 increased by about 

100 μM over the same distance (table 8). These increases are 

consistent with microbial Fe reduction stimulated by H2, 

written as

H2 + 2FeOOHs + 4H+ = 4H2O + 2Fe2+. (11)

The Cape Cod aquifer sediments have a low affinity for 

adsorption of aqueous Fe(II) species and a poor pH-buffering 

capacity. Therefore, the increase in Fe2+ concentrations and the 

decrease in pH values driven by reaction 11 would be weakly 

attenuated by reactions with the sediments. Measurements at 

other sites with granular-iron PRBs generally have shown 

dissolved iron concentrations that decrease and pH values that 

tend toward background values with increasing distance from 

the PRBs (O’Hannesin and Gillham, 1998; Puls and others, 

1999; Morrison and others, 2002a; Naftz and others, 2002a). 

The fact that increases in pH values and Fe(II) concentrations 

were observed downgradient from the PRBs at the MMR and 

not at other sites may be a result of the absence of solids, such 

as carbonate minerals, in the sediments that can react with 

aqueous Fe(II) species and buffer against the pH increase 

generated by reaction 11.

The chemical changes described above are known to have 

persisted 65 ft downgradient from the B-wall at least 1 year 

after emplacement of the zero-valent iron. The changes are 

likely to extend substantially farther downgradient than 65 ft 

and to persist substantially longer than 1 year. Zero-valent-iron 

PRBs typically are designed with sufficient iron to remove 

VOCs for a long time. Laboratory experiments and monitoring 

of PRBs at other sites have demonstrated this long-term effect 

(U.S. Environmental Protection Agency, 1998; Naftz, 2002b). 

Therefore, the iron emplacement at the MMR is likely to 

produce chemically altered ground water for many years.

The ground-water-flow velocity of 0.4 ft/d indicates that 

the chemically altered zone could advance more than 100 ft per 

year downgradient from the PRBs. Chemical reactions and 

dilution by dispersion will reduce the rate of advance and limit 

the length of the zone. Transverse dispersion is small in the 

aquifer (Garabedian and others, 1991), however, and 

contaminant plumes on the MMR extend up to 4 mi from their 
24 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000

sources (Air Force Center for Environmental Excellence, 

2003b). The small dispersion and limited capacity of the aquifer 

to sorb and buffer the chemical changes indicate that the 

chemically altered zone could extend substantially farther than 

65 ft from the PRBs. Further investigations and monitoring 

would be needed to determine how far and how long these 

changes would continue.

Summary and Conclusions

Two granular zero-valent-iron permeable reactive barriers 

(PRBs) were installed in June 1998 by the University of 

Waterloo and GeoSierra LLC (formerly Golder Sierra LLC), 

in cooperation with the Air Force Center for Environmental 

Excellence (AFCEE), in the path of the Chemical Spill-10 

(CS-10) contaminant plume at the Massachusetts Military 

Reservation, Cape Cod, Massachusetts. The CS-10 plume 

where the PRBs were emplaced contains tetrachloroethene 

(PCE) at concentrations as high as 250 μg/L. The PRBs 

were installed to test a method to treat plumes of dissolved 

chlorinated solvents emanating from source areas on the 

reservation. Zero-valent iron has been used at other sites in 

North America and Europe to remediate PCE contamination by 

reductive dechlorination.

The study area is located on the downgradient border of the 

source area of the CS-10 plume. The plume at this location is 

from 80 to 120 ft below land surface; emplacement of granulariron PRBs to these depths had not been attempted anywhere 

previously. An innovative method based on vertical hydraulic 

fracturing and injection was used to install the permeable 

barriers. Two walls (referred to as the A-wall and B-wall) were 

installed starting in June 1998 by injection of a slurry composed 

of guar biopolymer, granular iron, sand (only in the B-wall), an 

enzyme, sodium chloride, potassium carbonate, and sodium 

borate into four specially designed wells. The walls, which were 

designed to be about 50 ft wide and 40 ft high, are oriented 

parallel to each other and perpendicular to the ground-waterflow direction so that contaminated ground water would flow 

sequentially through the A and B walls. Chemical data collected 

for about 2-3 months after the emplacement suggested that 

ground water was flowing around rather than through the Awall. In September 1998, an enzyme and acetic acid solution 

with a pH of about 3.4 was injected into wells near the walls in 

an apparently unsuccessful effort to degrade the guar 

biopolymer in the A-wall.

During the period from June 1997 to February 2000, the 

U.S. Geological Survey, in cooperation with the University 

of Waterloo and AFCEE, collected ground-water samples 

from monitoring wells near the PRBs to determine how the 

emplacement of the granular-iron walls changed the groundwater quality. In addition, an automated well-sampling device, 

the Robowell system, measured temperature, specific 

conductance, pH, and dissolved oxygen concentration in one 

well about every 1–4 days for 16 months. Other than the 

presence of PCE, water properties in the CS-10 plume generally 

were similar to uncontaminated ground water, which typically 

has dissolved oxygen concentrations from 250 to 375 μM, pH 

from 5.5 to 6.0, and specific conductance from 60 to 90 μS/cm. 

The PRBs were expected to cause temporary (lasting about 5 to 

6 months) and sustained (longer than 12 months) changes in the 

ground-water chemistry downgradient from the walls.

A sustained reducing geochemical zone that extended at 

least 65 ft downgradient from the B-wall developed as a result 

of oxidation, or corrosion, of the zero-valent iron in the wall. In 

this zone, dissolved oxygen concentrations decreased to zero, 

the pH increased to about 6.8, and dissolved iron concentrations 

increased substantially. The loss of dissolved oxygen and 

increase in pH during transport through the B-wall likely 

resulted primarily from the iron-corrosion reaction, which 

consumes oxygen and hydrogen ions. The pH and iron 

concentrations increased with distance downgradient from the 

B-wall, probably because H2 produced by the iron corrosion 

reaction in the PRB caused reduction of iron oxyhydroxides in 

the aquifer that counteracted other reactions that would have 

attenuated the increased pH and dissolved iron concentrations 

with distance. The increasing pH and iron concentrations with 

distance have not been observed at other zero-valent-iron PRB 

sites, perhaps because the Cape Cod aquifer sediments, which 

are composed mostly of quartz and feldspar, have a lower 

affinity for Fe(II) adsorption and a poorer buffering capacity 

than sediments at other sites.

Concentrations of arsenic, cobalt, and manganese, which 

were below detection limits prior to emplacement of the walls, 

increased after emplacement of the PRBs. Although impurities 

in the granular iron and sand introduced in the aquifer cannot be 

ruled out as a source for these trace elements, observations in 

contaminant plumes elsewhere in the Cape Cod aquifer indicate 

that these species may have been mobilized from the aquifer 

sediments downgradient from the PRBs. A temporary peak in 

concentrations of cobalt and manganese in November 1998 

may have been caused by ion-exchange reactions associated 

with the transient passage of the major cations introduced as 

part of PRB emplacement and later by the acetic acid and 

enzyme injection. Sustained, but slightly lower, concentrations 

of cobalt and manganese, as well as the low concentrations of 

phosphorus and arsenic, observed for the remainder of the study 

most likely were caused by mobilization of these elements from 

the aquifer sediments in the persistent, chemically reducing 

environment downgradient from the B-wall.
Summary and Conclusions 25

Nitrate was removed from the ground water by the 

B-wall for about 1.5 years after the wall’s emplacement. 

The appearance of ammonium following the disappearance of 

nitrate indicates that most of the nitrate removal resulted from 

abiotic reduction by zero-valent iron or its corrosion products. 

Microbial nitrate reduction to nitrogen gas (denitrification) 

also may have accounted for part of the nitrate loss. Nitrate 

concentrations began to increase near the end of the study 

period (February 2000), indicating a deterioration in the 

nitrate-reducing capacity of the B-wall with time.

Concentrations of PCE downgradient from the PRBs had 

not decreased as of February 2000, although concentrations 

were variable spatially and temporally in both upgradient and 

downgradient wells. Some indication of PCE reduction and 

formation of degradation products was observed by AFCEE

in various wells downgradient from the B-wall after this 

study had ended. The PCE data indicated that there was no 

degradation attributable to the A-wall, however, and that it is 

possible that ground water is flowing around the A-wall rather 

than through it.

Temporary changes in ground-water quality also were 

caused by the introduction of the granular-iron and guar 

biopolymer slurry and associated additional salts, and the 

subsequent injection of the acetic acid and enzyme solution. 

Two peaks in specific conductance were observed at the 

automated well which was located 30 ft downgradient from the 

B-wall. The first peak was associated with sodium chloride 

and other salts introduced during the PRB emplacements; 

the second peak resulted from mineral-dissolution and ionexchange reactions associated with the acetic acid injection. 

Ground-water velocities estimated from the travel times of the 

specific conductance peaks were similar to those estimated 

from the average hydraulic conductivity, porosity, and regional 

hydraulic gradient. The good agreement between these 

estimates indicates that emplacement of the PRBs did not have 

a major overall effect on average ground-water-flow rates 

through the study area.

The sodium, potassium, and boron introduced with the 

slurry mixtures, and ion-exchange reactions driven by increased 

concentrations of these cations, caused temporary increases in 

the concentrations of the major cations (sodium, potassium, 

magnesium, and calcium) and boron in samples from wells 

downgradient from the PRBs. The ion-exchange reactions also 

caused temporary increases in the concentrations of other minor 

and trace elements, such as phosphorus, arsenic, and cobalt.

The temporary decrease in sulfate concentrations 

downgradient from the B-wall may have been caused by 

precipitation of corrosion products, such as green rust, 

or by microbial sulfate reduction. The increase in sulfate 

concentrations following passage of the acetic acid and acetate 

peak may be an indication that sulfate reduction linked 

to acetate biodegradation contributed to the temporary 

disappearance of sulfate. The persistently lower sulfate 

concentrations in wells downgradient from the PRBs than in 

upgradient wells indicate that the B-wall continues to remove a 

portion of the sulfate by precipitation of corrosion products or 

by sulfate reduction.

The guar biopolymer and 28,000 gal of the acetic acid 

solution were the major sources of organic compounds in 

ground water at the study area. A temporary but substantial 

increase in the concentrations of TOC and DOC downgradient 

from the PRBs indicated that there was little consumption 

during transport of the acetate derived from the acetic acid. The 

appearance of methane in ground-water samples after the 

passage of the organic-carbon peak associated with the acetic 

acid and acetate most likely was caused by microbial 

methanogenesis stimulated by either the acetate or the H2

produced by the iron corrosion reaction.

Dissolved inorganic carbon (DIC) concentrations also 

increased following emplacement of the PRBs and injection of 

the acetic acid and enzyme solution. Comparison of the increase 

in DIC concentrations to decreases in the concentrations of 

electron acceptors, such as dissolved oxygen, nitrate, iron (III), 

and sulfate, that would be involved in microbial degradation 

of the organic compounds, supports the conclusion that there 

was little consumption of the acetate during transport. The 

carbonate, which was added to the slurry mixture as potassium 

carbonate during emplacement of the PRBs, likely contributed 

substantially to the observed increase in DIC concentrations.

Water-quality results from this study indicate that the 

ground-water chemistry was changed by the emplacement of 

the zero-valent-iron PRBs, as had been expected. The changes 

persisted farther downgradient from the walls than has been 

observed at other PRB sites, however, because of the low 

chemical reactivity of the quartz-dominated aquifer sediments 

and the low ambient dissolved chemical concentrations in the 

ground water. Observations like these have not been reported at 

other PRB sites because of the relatively simple geochemical 

and hydrologic conditions found in the Cape Cod aquifer 

compared to other sites. The emplacement of iron in the Cape 

Cod aquifer to remove chlorinated solvents from the ground 

water caused substantial changes in the water chemistry by 

decreasing the dissolved oxygen concentration, increasing the 

pH and iron concentration, and increasing the presence of other 

sediment-bound elements such as arsenic, cobalt, manganese 

and phosphorus. The small transverse dispersion in this aquifer 

and the probable long-term persistence of the zero-valent iron 

indicate that the zone of altered chemical quality will extend a 

substantial distance downgradient from the PRBs for a 

substantial period of time. Further investigation would be 

needed, however, to determine how far downgradient the 

geochemically altered zone persists and how long these changes 

will continue. 
26 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000

References Cited

Ahmann, D., Krumholz, H.F., Hemond, H.F., Lovley, D.R., and 

Morel, F.M.M., 1997, Microbial mobilization of arsenic from 

sediments of the Aberjona watershed: Environmental 

Science & Technology, v. 31, no. 10, p. 2923–2930.

Air Force Center for Environmental Excellence, 2003a, 

Chemical Spill 10 (CS-10) Groundwater Plume, 

Massachusetts Military Reservation, Installation Restoration 

Program, accessed online August 4, 2003, at URL 

http://www.mmr.org/IRP/genprog/factshts/plumesumm/ 

cs-10plumeback.pdf

Air Force Center for Environmental Excellence, 2003b, 

Cleaning up the MMR, 2002, Annual Report: Air 

Force Center for Environmental Excellence, Massachusetts 

Military Reservation, Installation Restoration Program, 

11 p., accessed online August 3, 2003, at URL 

http://www.mmr.org/irp/reports/annual/2002/

AR2002_Final.pdf

Antweiler, R.C., Patton, C.P., and Taylor, H.E., 1996, 

Automated colorimetric methods for determination of nitrate, 

nitrite, ammonium, and orthophosphate ions in natural water 

samples: U.S. Geological Survey Open-File Report 93-638, 

123 p.

Appelo, C.A.J., van der Weiden, M.J.J., Tournassat, C., and 

Charlet, L., 2002, Surface complexation of ferrous iron and 

carbonate on ferrihydrite and the mobilization of arsenic: 

Environmental Science & Technology, v. 36, no. 14,

p. 3096–3103.

Barber, L.B., II, 1998, Organic carbon fractionation and 

specific organic compounds, in Savoie, Jennifer, and 

LeBlanc, D.R., eds., Water-quality data and methods of 

analysis for samples collected near a plume of sewagecontaminated ground water, Ashumet Valley, Cape Cod, 

Massachusetts, 1993–94: U.S. Geological Survey WaterResources Investigations Report 97-4269, p. 16–19.

Barber, L.B., II, Thurman, E.M., and Runnells, D.D., 1992, 

Geochemical heterogeneity in a sand and gravel 

aquifer—Effect of sediment mineralogy and particle size on 

the sorption of chlorobenzenes: Journal of Contaminant 

Hydrology, v. 9, no. 1, p. 35–54.

Ceazan, M.L., Thurman, E.M., and Smith, R.L., 1989, 

Retardation of ammonium and potassium transport through a 

contaminated sand and gravel aquifer—The role of cation 

exchange: Environmental Science & Technology, v. 23, no. 

11, p. 1402–1408.

Coston, J.A., Abrams, R.H., and Kent, D.B., 1998, Selected 

inorganic solutes, in Savoie, Jennifer, and LeBlanc, D.R., 

eds., Water-quality data and methods of analysis for samples 

collected near a plume of sewage-contaminated ground 

water, Ashumet Valley, Cape Cod, Massachusetts, 1993–94: 

U.S. Geological Survey Water-Resources Investigations 

Report 97-4269, p. 19–21.

Davis, J.A., Coston, J.A., Kent, D.B., and Fuller, C.C., 1998, 

Application of the surface complexation concept to complex 

mineral assemblages: Environmental Science & Technology, 

v. 32, no. 19, p. 2820–2828.

Davis, J.A., Kent, D.B., Coston, J.A., Hess, K.M., and Joye, 

J.L., 2000, Multispecies reactive tracer test in an aquifer with 

spatially variable chemical conditions—Experimental design 

and observed tracer movement: Water Resources Research, 

v. 36, no. 1, p. 119–134.

Farrell, J., Wang, J., O’Day, P., and Conklin, M., 2001, 

Electrochemical and spectroscopic study of arsenate removal 

from water using zero-valent iron media: Environmental 

Science & Technology, v. 35, no. 10, p. 2026–2032.

Fishman, M.J., and Freidman, L.C., eds., 1989, Methods for 

determination of inorganic substances in water and fluvial 

sediments: U.S. Geological Survey Techniques of WaterResources Investigations, book 5, chap. A1, 545 p.

Garabedian, S.P., LeBlanc, D.R., Gelhar, L.W., and Celia, 

M.A., 1991, Large-scale natural-gradient tracer test in sand 

and gravel, Cape Cod, Massachusetts—2. Analysis of spatial 

moments for nonreactive tracer: Water Resources Research, 

v. 27, no. 5, p. 911–924.

Gillham, R.W., 1996, In situ treatment of groundwater—Metalenhanced degradation of chlorinated organic contaminants, 

in Aral, M.M., ed., Advances in Groundwater Pollution and 

Control and Remediation—Proceedings of the NATO 

Advanced Study Institute on Advances in Groundwater 

Pollution Control and Remediation, Antalya, Turkey, June 1, 

1995: Netherlands, Kluwer Academic Publishers, p. 249–

274.

Gillham, R.W., and O'Hannesin, S.F., 1994, Enhanced 

degradation of halogenated aliphatics by zero-valent iron: 

Ground Water, v. 32, no. 6, p. 958–967.

Granato, G.E., and Smith, K.P., 1999, Robowell—An 

automated process for monitoring ground water quality using 

established sampling protocols: Ground Water Monitoring 

and Remediation, v. 19, no. 4, p. 81–89. 

Gu, B., Phelps, T.J., Liang, L., Dickey, M.J., Roh, Y., Kinsall, 

B.L., Palumbo, A.V., and Jacobs, G.K., 1999, 

Biogeochemical dynamics in zero-valent iron 

columns—Implications for permeable reactive barriers: 

Environmental Science & Technology, v. 33, no. 13, 

p. 2170–2177.

Gu, B., Watson, D.B., Phillips, D.H., and Liang, L., 2002, 

Biogeochemical, mineralogical, and hydrological 

characteristics of an iron reactive barrier used for treatment 

of uranium and nitrate, in Naftz, D.L., Morrison, S.J., Fuller, 

C.C., and Davis, J.A., eds., Handbook of Groundwater 

Remediation Using Permeable Reactive Barriers: New York, 

Academic Press, p. 305–342.

Hansen, H.C.B., Koch, C.B., Nanchke-Krogh, H., Borggaard, 

O.K., and Sorensen, J., 1996, Abiotic nitrate reduction to 

ammonium—Key role of green rust: Environmental Science 

& Technology, v. 30, no. 6, p. 2053–2056.
References Cited 27

Hoehn, R., Isenbeck-Schroeter, M., Niedan, V., Scholz, C., 

Tretner, A., Jann, S., Stadler, S., Kent, D.B., Davis, J.A., and 

Jakobsen, R., 2001, Tracer test with arsenic(V) in an ironreducing environment at the USGS Cape Cod Site (Mass., 

USA), in Cidu, R., ed., Water-Rock Interaction 2001: Lisse, 

Italy, Balkema, p. 1099–1102.

Huang, C.P., Wang, H.W., and Chiu, P.C., 1998, Nitrate 

reduction by metallic iron: Water Research, v. 32, no. 8, 

p. 2257-2264.

Hubble, D.W., 2003, Verification and monitoring of deep 

granular iron permeable reactive barriers emplaced by 

vertical hydraulic fracturing and injection for groundwater 

remediation: Waterloo, Ontario, Canada, Department of 

Earth Sciences, University of Waterloo, National Library of 

Canada, Ph.D. thesis, 179 p.

Hubble, D.W., and Forbes, R.H., 1999, Demonstration of a zero 

valent iron permeable reactive wall at the Massachusetts 

Military Reservation, in 15th Annual International 

Conference on Contaminated Soils and Water, Amherst, 

Massachusetts, October 20, 1999, Proceedings: Amherst, 

MA, University of Massachusetts, variously paged.

Hubble, D.W., and Gillham, R.W., 2001, Deep granular iron 

permeable reactive barrier field demonstration at 

Massachusetts Military Reservation: Waterloo, Ontario, 

Canada, Institute for Groundwater Research, Department of 

Earth Sciences, University of Waterloo, 134 p.

Hubble, D.W., Gillham, R.W., and Cherry, J.A., 1997, 

Emplacement of zero-valent metal for remediation of deep 

contaminant plumes, in International Containment 

Technology Conference, St. Petersburg, Florida, February 9–

12, 1997, Proceedings: Tallahassee, FL, Florida State 

University, p. 872–878.

Kent, D.B., Davis, J.A., Anderson, L.C.D., Rea, B.A., and 

Waite, T.D., 1994, Transport of chromium and selenium in 

the suboxic zone of a shallow aquifer—Influence of redox 

and adsorption reactions: Water Resources Research, v. 30, 

no. 4, p. 1099–1114.

Kent, D.B., Davis, J.A., Anderson, L.C.D., Rea, B.A., and 

Coston, J.A., 2002a, Effect of adsorbed metal ions on the 

transport of Zn- and Ni-EDTA complexes in a sand and 

gravel aquifer: Geochimica et Cosmochimica Acta, v. 66, no. 

17, p. 3017–3036.

Kent, D.B., Wilkie, J.A., Curtis, G.P., and Davis, J.A., 2002b, 

Modeling the influence of variable pH on zinc contamination 

in a quartz-sand aquifer [abs]: Geochimica et Cosmochimica 

Acta, v. 66, no. 15A, p. A394.

Lane, J.W., Jr., Joesten, P.K., and Savoie, J.G., 2001, Crosshole radar scanning of two vertical, permeable, reactive-iron 

walls at the Massachusetts Military Reservation, Cape Cod, 

Massachusetts: U.S. Geological Survey Water-Resources 

Investigations Report 00-4145, 17 p.

LeBlanc, D.R., Guswa, J.H., Frimpter, M.H., and Londquist, 

C.J., 1986, Ground-water resources of Cape Cod, 

Massachusetts: U.S. Geological Survey HydrologicInvestigations Atlas 692, 4 sheets, scale 1:48,000.

Lee, R.W., and Bennett, P.C., 1998, Reductive dissolution and 

reactive solute transport in a sewage-contaminated glacial 

outwash aquifer: Ground Water, v. 36, no. 4, p. 583–595.

Lovley, D.R., Chapelle, F.H., and Woodward, J.C., 1994, Use 

of dissolved H2 concentrations to determine distribution of 

microbially catalyzed redox reactions in anoxic groundwater: 

Environmental Science & Technology, v. 28, no. 7, p. 1205–

1210.

Masterson, J.P., Stone, B.D., Walter, D.A., and Savoie, 

Jennifer, 1997, Hydrogeologic framework of western Cape 

Cod, Massachusetts: U.S. Geological Survey HydrologicInvestigations Atlas HA-741, 1 pl.

Mayer, K.U., Blowes, D.W., and Frind, E.O., 2001, Reactive 

transport modeling of an in situ reactive barrier for the 

treatment of hexavalent chromium and trichloroethylene in 

groundwater: Water Resources Research, v. 37, no. 12, 

p. 3091–3103.

McMahon, P.B., Dennehy, K.F., and Sandstrom, M.W., 1999, 

Hydraulic and geochemical performance of a permeable 

reactive barrier containing zero-valent iron, Denver Federal 

Center: Ground Water, v. 37, no. 3, p. 396–404.

Morel, F.M.M., and Hering, J.G., 1993, Principles and 

applications of aquatic chemistry: New York, John Wiley 

and Sons, 588 p.

Morrison, S.J., Carpenter, C.E., Metzler, D.R., Bartlett, T.R., 

and Morris, S.A., 2002a, Design and performance of a 

permeable reactive barrier for containment of uranium, 

arsenic, selenium, vanadium, molybdenum, and nitrate at 

Monticello, Utah, in Naftz, D.L., Morrison, S.J., Fuller, C.C., 

and Davis, J.A., eds., Handbook of Groundwater 

Remediation Using Permeable Reactive Barriers: New York, 

Academic Press, p. 371–399.

Morrison, S.J., Metzler, D.R., and Dwyer, B.P., 2002b, 

Collection drain and permeable reactive barrier for treating 

uranium and metals from mill tailings near Durango, 

Colorado, in Naftz, D.L., Morrison, S.J., Fuller, C.C., and 

Davis, J.A., eds., Handbook of Groundwater Remediation 

Using Permeable Reactive Barriers: New York, Academic 

Press, p. 435–463.

Naftz, D.L., Fuller, C.C., Davis, J.A., Morrison, S.J., Feltcorn, 

E.M., Freethey, G.W., Rowland, R.C., Wilkowske, C., and 

Piana, M., 2002a, Field demonstration of three permeable 

reactive barriers to control uranium contamination in 

groundwater, Fry Canyon, Utah, in Naftz, D.L., Morrison, 

S.J., Fuller, C.C., and Davis, J.A., eds., Handbook of 

Groundwater Remediation Using Permeable Reactive 

Barriers: New York, Academic Press, p. 401–434.

Naftz, D.L., Morrison, S.J., Fuller, C.C., and Davis, J.A., eds., 

2002b, Handbook of groundwater remediation using 

permeable reactive barriers: New York, Academic Press, 

544 p.

O’Hannesin, S.F.O., and Gillham, R.W., 1998, Long-term 

performance of an in-situ “iron wall” for remediation of 

VOCs: Ground Water, v. 36, no. 1, p. 164–170.
28 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000

Oremland, R.S., Newman, D.K., Kail, B.W., and Stolz, J.F., 

2001, Bacterial respiration of arsenate and its significance in 

the environment, in Frankenberger, W.T., ed., Environmental 

Chemistry of Arsenic: New York, Marcel Dekker, p. 273–

295.

Ottley, C.J., Davison, W., and Edmunds, W.M., 1997, 

Chemical catalysis of nitrate reduction by iron (II): 

Geochimica et Cosmochimica Acta, v. 61, no. 9, p. 1819–

1828.

Phillips, D.H., Gu, B., Watson, D.B., Roh, Y., Liang, L., and 

Lee, S.Y., 2000, Performance evaluation of a zerovalent 

iron reactive barrier—Mineralogical characteristics: 

Environmental Science & Technology, v. 34, no. 10, 

p. 4169–4176.

Puls, R.W., Paul, C.J., and Powell, R.M., 1999, The application 

of in situ permeable reactive (zero-valent iron) barrier 

technology for the remediation of chromate-contaminated 

groundwater—A field test: Applied Geochemistry, v. 14, 

no. 8, p. 989–1000.

Reardon, E.J., 1995, Anaerobic corrosion of granular 

iron—Measurement and interpretation of hydrogen evolution 

rates: Environmental Science & Technology, v. 29, no. 12, 

p. 2936–2945.

Ritter, K., Odziemkowski, M.S., and Gillham, R.W., 2002, An 

in situ study of the role of surface films on granular iron in 

the permeable iron wall technology: Journal of Contaminant 

Hydrology, v. 55, no. 1-2, p. 87–111.

Rochette, E.A., Bostick, B.C., Li, G., and Fendorf, S., 2000, 

Kinetics of arsenate reduction by dissolved sulfide: 

Environmental Science & Technology, v. 34, no. 22, 

p. 4714–4720.

Roh, Y., Lee, S.Y., and Elless, M.P., 2000, Characterization of 

corrosion products in permeable reactive barriers: 

Environmental Geology, v. 40, no. 1-2, p. 184–194.

Rowland, R.C., 2002, Sulfate-reducing bacteria in the zerovalent iron permeable reactive barrier at Fry Canyon, Utah, 

in Naftz, D.L., Morrison, S.J., Fuller, C.C., and Davis, J.A., 

eds., Handbook of Groundwater Remediation Using 

Permeable Reactive Barriers: New York, Academic Press, 

p. 281–304.

Savoie, Jennifer, 1995, Altitude and configuration of the water 

table, western Cape Cod, Massachusetts, March 1993: U.S. 

Geological Survey Open-File Report 94-462, 1 sheet.

Savoie, Jennifer, and LeBlanc, D.R., 1998, Water-quality data 

and methods of analysis for samples collected near a plume 

of sewage-contaminated ground water, Ashumet Valley, 

Cape Cod, Massachusetts, 1993–94: U.S. Geological Survey 

Water-Resources Investigations Report 97-4269, 208 p.

Smedley, P.L., and Kinniburgh, D.G., 2002, A review of the 

source, behavior, and distribution of arsenic in natural 

waters: Applied Geochemistry, v. 17, no. 5, p. 517–568.

Smith, R.L., Ceazan, M.L., and Brooks, M.H., 1994, 

Autotrophic, hydrogen-oxidizing, denitrifying bacteria in 

groundwater—Potential agents for bioremediation of nitrate 

contamination: Applied and Environmental Microbiology, 

v. 60, no. 6, p. 1949–1955.

Smith, R.L., and Duff, J.H., 1988, Denitrification in a sand and 

gravel aquifer: Applied and Environmental Microbiology, 

v. 54, no. 5, p. 1071–1078.

Smith, R.L., Garabedian, S.P., and Brooks, M.H., 1996, 

Comparison of denitrification activity measurements in 

ground water using cores and natural gradient tracer tests: 

Environmental Science & Technology, v. 30, no. 12, 

p. 3448–3456.

Smith, R.L., Howes, B.L., and Duff, J.H., 1991a, 

Denitrification in nitrate-contaminated ground water— 

Occurrence in steep vertical geochemical gradients: 

Geochimica et Cosmochimica Acta, v. 55, no. 7, p. 1815–

1825.

Smith, R.L., Howes, B.L., and Garabedian, S.P., 1991b, In situ 

measurement of methane oxidation in groundwater by using 

natural-gradient tracer tests: Applied and Environmental 

Microbiology, v. 57, no. 7, p. 1997–2004.

Till, B.A., Weathers, L.J., and Alvarez, P.J.J., 1998, Fe(0)-

supported autotrophic denitrification: Environmental 

Science & Technology, v. 32, no. 5, p. 634–639.

U.S. Environmental Protection Agency, 1998, Permeable 

reactive barrier technologies for contaminant remediation: 

Washington, D.C., U.S. Environmental Protection Agency, 

EPA/600/R-98/125, September 1998, variously paged.

U.S. Environmental Protection Agency, 2002, List of 

contaminants & their MCLs, accessed on June 17, 2003, 

at URL http://www.epa.gov/safewater/mcl.html

Weathers, L.J., Parkin, G.F., and Alvarez, P.J., 1997, 

Utilization of cathodic hydrogen as electron donor for 

chloroform cometabolism by a mixed methanogenic culture: 

Environmental Science & Technology, v. 31, no. 3, p. 800–

885.

Wershaw, R.L., Fishman, J.J., Grabbe, R.R., and Lowe, L.E., 

1987, Methods for the determination of organic substances 

in water and fluvial sediments: U.S. Geological Survey 

Techniques of Water-Resources Investigations, book 5, 

chap. A3, 80 p.

Zachara, J.M., Smith, S.C., and Fredrickson, J.K., 2000, The 

effect of biogenic Fe(II) on the stability and sorption of 

Co(II)EDTA[2-] to goethite and a subsurface sediment: 

Geochimica et Cosmochimica Acta, v. 64, no. 8, p. 1345–

1362.
Tables 4–10

Table 4 31

Table 4. Field water-quality analyses for ground-water samples collected near the granular-iron permeable reactive barriers, 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.

[Locations of wells are shown in figure 2. meq/L, milliequivalents per liter; μM, micromoles per liter; μS/cm, microsiemens per centimeter at 25 degrees Celsius; 

NTU, Nephelometric Turbidity Units; na, only field parameters measured; --, no data]

Well number

Date

sample

taken

Sampling 

round

Specific 

conductance 

(μS/cm)

pH

(standard units)

Alkalinity 

(meq/L)

Oxygen, 

dissolved

(μM)

Temperature 

(°C)

Turbidity

(NTU)

MW 14B-0097 7-02-97 pre 1 89 5.69 -- 304 13.9 1.7

MW 14B-0097 7-23-97 pre 2 105 5.64 0.12 338 12.3 .2

MW 14B-0097 9-18-97 pre 3 66 5.78 .12 338 12.6 1.6

MW 14B-0097 6-23-99 post 13 137 5.54 -- 356 14.0 .8

MW 14A-0124 7-02-97 pre 1 62 5.68 -- 316 13.8 1.6

MW 14A-0124 7-23-97 pre 2 64 5.66 .08 338 12.1 .5

MW 14A-0124 9-18-97 pre 3 59 5.69 .07 344 12.5 3.9

MW 14A-0124 6-23-99 post 13 309 5.28 -- 309 14.3 --

RW 24-0094 9-17-97 pre 3 117 5.85 .17 300 12.2 1.4

RW 24-0094 5-19-98 pre 4 86 5.52 .40 272 13.2 18.6

RW 24-0094 7-09-98 na 78 6.06 -- -- 12.1 8.8

RW 24-0094 7-14-98 post 1 71 6.01 .21 329 14.9 3.0

RW 24-0094 7-29-98 post 3 76 5.95 .23 252 16.8 8.8

RW 24-0094 8-05-98 post 4 81 5.93 .22 218 14.7 4.9

RW 24-0094 8-14-98 post 5 102 5.86 .23 209 12.7 1.7

RW 24-0094 8-20-98 post 6 112 5.91 .27 181 12.4 1.1

RW 24-0094 9-02-98 post 7 208 5.75 .20 141 12.6 .6

RW 24-0094 10-02-98 post 8 318 5.72 .14 16 12.8 .6

RW 24-0094 10-27-98 post 9 364 5.77 .22 103 12.0 2.1

RW 24-0094 11-24-98 post 10 534 5.74 .24 18 12.5 1.9

RW 24-0094 1-26-99 post 11 283 6.84 1.64 0 9.1 1.5

RW 24-0094 3-25-99 post 12 257 6.70 1.42 0 11.8 2.5

RW 24-0094 6-23-99 post 13 170 6.85 -- 0 13.1 1.8

RW 24-0094 11-2-99 post 15 167 6.58 -- 0 13.4 .5

RW 24-0094 1-11-00 post 16 153 6.83 -- 0 11.7 .8

RW 24-0094 2-09-00 post 17 150 6.78 -- 0 9.9 1.0

RW 24A-0100 7-01-97 pre 1 149 5.72 .14 237 16.7 9.5

RW 24A-0100 7-21-97 pre 2 206 5.59 .12 266 13.2 .7

RW 24A-0100 9-17-97 pre 3 203 5.58 .10 275 11.9 1.0

RW 24A-0100 5-19-98 pre 4 84 5.90 .17 281 13.6 6.9

RW 24A-0100 7-09-98 na 90 5.80 -- 12.0 1.9

RW 24A-0100 7-14-98 post 1 83 5.81 .17 256 14.9 2.4

RW 24A-0100 7-29-98 post 3 89 5.78 .17 178 16.9 90.0

RW 24A-0100 8-05-98 post 4 108 5.72 .19 120 16.7 2.8

RW 24A-0100 8-14-98 post 5 105 5.69 .19 119 12.4 1.2

RW 24A-0100 8-20-98 post 6 218 5.81 .45 63 13.1 1.6

RW 24A-0100 9-02-98 post 7 526 6.26 1.82 3 12.8 1.1

RW 24A-0100 10-02-98 post 8 410 6.89 2.46 0 12.8 1.6

RW 24A-0100 10-27-98 post 9 508 6.60 4.84 0 12.0 5.3

RW 24A-0100 11-24-98 post 10 871 6.81 3.43 1 13.3 1.8

RW 24A-0100 1-26-99 post 11 270 6.81 1.96 0 11.0 1.7
32 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000

RW 24A-0100 3-25-99 post 12 318 6.54 2.10 0 11.7 6.7

RW 24A-0100 4-06-99 post 12.5 272 6.70 -- 0 11.8 .9

RW 24A-0100 6-22-99 post 13 167 6.82 -- 0 13.1 .7

RW 24A-0100 11-02-99 post 15 171 6.88 -- 0 13.3 .8

RW 24A-0100 1-11-00 post 16 159 6.73 -- 0 11.6 .6

RW 24A-0100 2-09-00 post 17 157 6.62 -- 10 10.3 9.2

RW 24B-0104 7-01-97 pre 1 93 5.68 .16 319 13.0 1.4

RW 24B-0104 7-21-97 pre 2 101 5.68 .13 303 12.3 .9

RW 24B-0104 9-17-97 pre 3 230 5.48 .07 281 12.2 10.0

RW 24B-0104 5-19-98 pre 4 84 5.80 .15 309 13.3 3.3

RW 24B-0104 7-09-98 na 82 5.79 -- -- 11.9 4.4

RW 24B-0104 7-14-98 post 1 72 5.95 .14 281 10.0

RW 24B-0104 8-14-98 post 5 90 5.62 .12 191 12.5 2.3

RW 24B-0104 8-20-98 post 6 102 5.62 .14 159 13.7 7.7

RW 24B-0104 9-02-98 post 7 282 5.93 .64 28 12.5 1.6

RW 24B-0104 10-02-98 post 8 520 6.64 2.66 0 13.7 1.5

RW 24B-0104 10-27-98 post 9 740 6.63 7.12 0 12.2 5.3

RW 24B-0104 11-24-98 post 10 1,031 6.57 7.28 1 13.7 2.0

RW 24B-0104 1-26-99 post 11 194 6.70 .72 0 10.7 --

RW 24B-0104 3-25-99 post 12 306 6.60 1.82 0 12.1 1.8

RW 24B-0104 6-22-99 post 13 190 6.72 -- 0 12.5 1.0

RW 24B-0104 11-02-99 post 15 157 6.71 -- 0 12.9 .9

RW 24B-0104 1-11-00 post 16 144 6.70 -- 0 11.6 .8

RW 24B-0104 2-09-00 post 17 145 6.58 -- 0 10.6 1.0

RW 24C-0110 7-01-97 pre 1 79 5.51 .08 300 13.5 8.6

RW 24C-0110 7-21-97 pre 2 76 5.54 .12 306 12.3 1.7

RW 24C-0110 9-17-97 pre 3 75 5.54 .09 303 12.1 3.0

RW 24C-0110 5-19-98 pre 4 74 5.63 .10 300 11.6 .7

RW 24C-0110 7-09-98 na 77 5.60 -- -- 12.0 22.0

RW 24C-0110 7-15-98 post 1 70 5.50 .10 275 14.9 3.4

RW 24C-0110 8-14-98 post 5 59 5.74 .11 306 12.6 8.9

RW 24C-0110 10-02-98 post 8 185 5.56 .36 147 12.4 .9

RW 24C-0110 10-27-98 post 9 428 5.04 3.54 2 12.3 5.3

RW 24C-0110 11-24-98 post 10 778 6.51 5.15 0 12.5 1.7

RW 24C-0110 1-26-99 post 11 500 6.88 3.93 1 10.1 1.6

RW 24C-0110 3-25-99 post 12 237 6.72 2.26 0 11.3 1.2

RW 24C-0110 6-22-99 post 13 139 6.90 -- 0 12.5 .9

RW 24C-0110 11-02-99 post 15 223 6.42 -- 58 13.2 .7

RW 24C-0110 1-11-00 post 16 200 6.53 -- 82 11.9 2.6

RW 24C-0110 2-09-00 post 17 195 6.47 -- 9 10.3 2.0

Table 4. Field water-quality analyses for ground-water samples collected near the granular-iron permeable reactive barriers, 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.—Continued

[Locations of wells are shown in figure 2. meq/L, milliequivalents per liter; μM, micromoles per liter; μS/cm, microsiemens per centimeter at 25 degrees Celsius; 

NTU, Nephelometric Turbidity Units; na, only field parameters measured; --, no data]

Well number

Date

sample

taken

Sampling 

round

Specific 

conductance 

(μS/cm)

pH

(standard units)

Alkalinity 

(meq/L)

Oxygen, 

dissolved

(μM)

Temperature 

(°C)

Turbidity

(NTU)
Table 4 33

RW 24D-0115 7-01-97 pre 1 75 5.57 0.14 281 16.1 5.7

RW 24D-0115 7-21-97 pre 2 72 5.66 .14 313 12.8 1.3

RW 24D-0115 9-17-97 pre 3 72 5.59 .10 303 11.7 8.7

RW 24D-0115 5-19-98 pre 4 68 5.63 .13 306 11.6 1.9

RW 24D-0115 7-09-98 na 67 5.63 -- -- 11.9 5.8

RW 24D-0115 7-15-98 post 1 61 5.69 .10 269 14.3 4.7

RW 24D-0115 8-14-98 post 5 70 5.60 .11 322 12.7 19.1

RW 24D-0115 10-02-98 post 8 83 5.65 .49 253 12.2 .8

RW 24D-0115 10-27-98 post 9 178 5.29 -- 194 11.9 1.7

RW 24D-0115 11-24-98 post 10 639 5.96 5.10 0 11.7 1.8

RW 24D-0115 1-26-99 post 11 227 6.68 1.76 1 9.2 1.5

RW 24D-0115 3-25-99 post 12 109 5.88 .21 97 11.4 .9

RW 24D-0115 6-22-99 post 13 85 5.60 -- 244 12.8 .4

RW 24D-0115 11-02-99 post 15 220 5.19 -- 293 12.8 .6

RW 24D-0115 1-11-00 post 16 215 5.04 -- 310 11.8 .4

RW 24D-0115 2-09-00 post 17 213 5.11 -- 338 9.8 .4

RW 25A-0092 7-02-97 pre 1 100 5.89 .17 325 13.2 5.3

RW 25A-0092 7-22-97 pre 2 92 5.90 .25 319 13.1 1.8

RW 25A-0092 9-18-97 pre 3 71 5.94 .22 334 12.5 21.0

RW 25A-0092 5-20-98 pre 4 68 5.94 .21 347 12.6 49.0

RW 25A-0092 6-23-99 post 13 96 5.61 -- 349 14.4 1.2

RW 25A-0092 8-10-99 post 14 128 5.39 -- 311 13.2 1.3

RW 25A-0092 11-03-99 post 15 105 5.47 -- 347 12.5 .9

RW 25A-0092 1-11-00 post 16 108 5.61 -- 344 12.3 .5

RW 25A-0092 2-08-00 post 17 108 5.70 -- 361 10.6 .6

RW 25B-0099 7-02-97 pre 1 115 5.56 .09 300 13.8 3.7

RW 25B-0099 7-22-97 pre 2 92 5.65 .13 303 12.6 1.1

RW 25B-0099 9-18-97 pre 3 79 5.68 .15 325 12.2 29.0

RW 25B-0099 5-20-98 pre 4 82 5.61 .13 331 12.5 8.7

RW 25B-0099 7-14-98 post 1 70 5.65 .13 291 14.7 5.9

RW 25B-0099 7-23-98 post 2 70 5.71 .15 294 17.5 12.9

RW 25B-0099 8-13-98 post 5 72 5.68 .15 331 12.2 10.3

RW 25B-0099 10-01-98 post 8 83 5.58 .15 341 12.1 12.5

RW 25B-0099 10-26-98 post 9 112 5.37 .16 306 13.1 4.5

RW 25B-0099 11-23-98 post 10 143 5.64 .13 326 11.3 1.9

RW 25B-0099 1-26-99 post 11 160 5.57 .69 335 9.2 1.3

RW 25B-0099 3-24-99 post 12 111 5.87 .12 342 10.8 3.2

RW 25B-0099 4-06-99 post 12.5 125 5.57 -- 336 12.2 .7

RW 25B-0099 6-21-99 post 13 104 5.59 -- 343 13.0 .5

RW 25B-0099 8-10-99 post 14 104 5.45 -- 338 13.5 .5

RW 25B-0099 11-03-99 post 15 123 5.60 -- 281 12.4 .6

RW 25B-0099 1-11-00 post 16 148 5.55 -- 347 12.0 .5

RW 25B-0099 2-08-00 post 17 159 5.63 -- 378 10.4 .5

Table 4. Field water-quality analyses for ground-water samples collected near the granular-iron permeable reactive barriers, 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.—Continued

[Locations of wells are shown in figure 2. meq/L, milliequivalents per liter; μM, micromoles per liter; μS/cm, microsiemens per centimeter at 25 degrees Celsius; 

NTU, Nephelometric Turbidity Units; na, only field parameters measured; --, no data]

Well number

Date

sample

taken

Sampling 

round

Specific 

conductance 

(μS/cm)

pH

(standard units)

Alkalinity 

(meq/L)

Oxygen, 

dissolved

(μM)

Temperature 

(°C)

Turbidity

(NTU)
34 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000

RW 25C-0105 7-02-97 pre 1 100 5.55 0.10 278 15.3 9.0

RW 25C-0105 7-22-97 pre 2 104 5.46 .11 303 12.5 1.6

RW 25C-0105 9-18-97 pre 3 72 5.61 .11 325 12.5 9.9

RW 25C-0105 5-20-98 pre 4 78 5.58 .11 328 12.1 9.7

RW 25C-0105 7-14-98 post 1 73 5.52 .12 272 14.9 7.0

RW 25C-0105 7-23-98 post 2 73 5.63 .10 300 17.1 12.9

RW 25C-0105 8-13-98 post 5 73 5.59 .16 331 12.1 6.5

RW 25C-0105 10-02-98 post 8 81 5.58 .10 331 12.3 44.0

RW 25C-0105 10-26-98 post 9 92 5.42 .11 295 11.7 2.3

RW 25C-0105 11-23-98 post 10 122 5.64 .09 307 11.2 4.7

RW 25C-0105 1-26-99 post 11 177 5.55 .19 322 8.8 1.3

RW 25C-0105 3-24-99 post 12 176 5.71 .06 318 10.1 1.0

RW 25C-0105 4-06-99 post 12.5 214 5.41 -- 322 11.9 .7

RW 25C-0105 6-21-99 post 13 148 5.54 -- 322 13.8 3.0

RW 25C-0105 8-10-99 post 14 127 5.38 -- 289 11.1 .8

RW 25C-0105 11-3-99 post 15 135 5.38 -- 372 12.8 .6

RW 25C-0105 1-11-00 post 16 125 5.57 -- 335 11.4 .5

RW 25C-0105 2-08-00 post 17 120 5.77 -- 360 10.7 .5

RW 25D-0110 7-02-97 pre 1 66 5.57 .09 300 13.2 5.3

RW 25D-0110 7-22-97 pre 2 80 5.47 .10 303 12.4 1.9

RW 25D-0110 9-18-97 pre 3 66 5.62 .11 325 12.5 23.0

RW 25D-0110 5-20-98 pre 4 65 5.61 .14 338 12.1 19.0

RW 25D-0110 4-06-99 post 12.5 115 5.80 -- 296 12.5 1.3

RW 25D-0110 6-23-99 post 13 153 5.42 -- 309 13.3 .6

RW 25D-0110 8-10-99 post 14 207 5.20 -- 305 11.1 .4

RW 25D-0110 11-03-99 post 15 190 5.30 -- 313 13.1 1.1

RW 25D-0110 1-11-00 post 16 173 5.43 -- 333 11.3 2.6

RW 25D-0110 2-08-00 post 17 162 5.63 -- 340 10.6 .5

RW 25E-0120 7-22-97 pre 2 78 5.60 .11 325 12.1 2.8

RW 25E-0120 9-18-97 pre 3 71 5.65 .07 341 12.5 10.5

RW 25E-0120 5-20-98 pre 4 84 5.57 .11 350 12.0 20.0

RW 25E-0120 6-23-99 post 13 67 5.72 -- 331 13.0 1.4

RW 25E-0120 8-10-99 post 14 67 5.66 -- 333 13.2 .9

RW 25E-0120 11-03-99 post 15 75 5.57 -- 353 12.4 1.8

RW 25E-0120 1-11-00 post 16 74 5.67 -- 360 10.7 1.1

RW 25E-0120 2-08-00 post 17 72 5.98 -- 386 9.9 .4

RW 26-0087 5-20-98 pre 4 191 5.86 .20 387 12.1 8.4

RW 26-0087 6-23-99 post 13 205 5.85 -- 328 14.6 2.4

RW 26-0087 8-10-99 post 14 285 5.92 -- 333 14.0 4.9

RW 26-0092 5-20-98 pre 4 84 5.74 .13 375 12.1 4.0

RW 26-0092 6-23-99 post 13 115 5.65 -- 280 14.8 .8

RW 26-0092 8-10-99 post 14 117 5.83 -- 263 14.1 .8

RW 26-0096 5-20-98 pre 4 84 5.74 .17 356 11.8 .5

RW 26-0096 8-10-99 post 14 119 5.69 355 13.6 1.0

Table 4. Field water-quality analyses for ground-water samples collected near the granular-iron permeable reactive barriers, 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.—Continued

[Locations of wells are shown in figure 2. meq/L, milliequivalents per liter; μM, micromoles per liter; μS/cm, microsiemens per centimeter at 25 degrees Celsius; 

NTU, Nephelometric Turbidity Units; na, only field parameters measured; --, no data]

Well number

Date

sample

taken

Sampling 

round

Specific 

conductance 

(μS/cm)

pH

(standard units)

Alkalinity 

(meq/L)

Oxygen, 

dissolved

(μM)

Temperature 

(°C)

Turbidity

(NTU)
Table 4 35

RW 26-0100 5-20-98 pre 4 78 5.56 0.14 331 12.0 10.0

RW 26-0100 8-10-99 post 14 112 5.86 329 13.8 1.2

RW 26-0106 5-20-98 pre 4 74 5.55 .10 344 11.8 1.5

RW 27-0098 5-19-98 pre 4 66 6.06 .17 313 11.9 3.1

RW 27-0098 7-15-98 post 1 87 5.78 .17 316 16.9 4.3

RW 27-0098 4-06-99 post 12.5 252 6.98 -- 0 12.0 2.0

RW 27-0098 6-22-99 post 13 158 6.98 -- 0 14.5 1.5

RW 27-0098 2-09-00 post 17 171 6.93 -- 1 10.1 1.3

RW 27-0102 5-19-98 pre 4 102 5.82 .17 313 11.8 .7

RW 27-0102 7-15-98 post 1 68 5.99 .15 294 16.8 8.3

RW 27-0102 4-06-99 post 12.5 378 6.86 -- 0 11.9 1.6

RW 27-0102 6-22-99 post 13 196 6.97 -- 0 14.5 2.0

RW 27-0102 2-09-00 post 17 159 6.90 -- 0 10.6 .7

RW 27-0108 5-19-98 pre 4 80 5.72 .13 313 11.7 1.5

RW 27-0108 7-15-98 post 1 67 5.44 .12 284 16.9 3.6

RW 27-0108 4-06-99 post 12.5 648 7.03 -- 0 11.6 2.2

RW 27-0108 6-22-99 post 13 182 7.17 -- 0 14.2 1.3

RW 27-0108 2-09-00 post 17 202 6.99 -- 0 10.5 2.2

RW 27-0114 5-19-98 pre 4 72 5.77 .16 266 11.8 14.0

RW 27-0114 7-15-98 post 1 68 5.82 .22 269 15.2 8.0

RW 27-0114 6-22-99 post 13 134 6.91 -- 0 12.9 1.4

RW 27-0114 2-09-00 post 17 226 5.41 -- 270 10.6 3.4

RW 27-0120 5-19-98 pre 4 75 5.66 .13 266 11.3 1.5

RW 27-0120 7-15-98 post 1 121 5.70 .23 272 15.5 26.0

RW 27-0120 6-22-99 post 13 132 6.63 -- 0 13.5 2.1

RW 27-0120 2-09-00 post 17 149 5.29 -- 313 10.6 .6

RW 28-0107 4-06-99 post 12.5 461 6.98 -- 0 11.6 2.5

RW 28-0107 6-22-99 post 13 334 7.01 -- 0 14.6 3.0

RW 29-0107 4-06-99 post 12.5 624 6.94 -- 0 11.4 1.9

RW 29-0107 6-22-99 post 13 240 7.08 -- 0 13.8 2.5

RW 29-0111 4-06-99 post 12.5 274 6.89 -- 0 11.3 3.7

RW 29-0111 6-23-99 post 13 207 6.90 -- 0 13.7 2.2

RW 30-0087 7-23-98 post 2 413 5.58 .07 297 16.3 40.0

RW 30-0087 7-29-98 post 3 405 5.46 .05 262 18.2 8.7

RW 30-0087 8-05-98 post 4 435 5.28 .05 315 16.0 17.3

RW 30-0087 8-13-98 post 5 382 5.69 .04 322 10.9 5.0

RW 30-0087 8-20-98 post 6 388 5.35 .05 319 13.2 1.9

RW 30-0087 9-02-98 post 7 299 5.30 .07 341 13.0 .5

RW 30-0087 10-02-98 post 8 714 5.08 .004 319 13.2 12.4

RW 30-0087 10-26-98 post 9 808 5.37 .06 169 12.2 3.6

RW 30-0087 11-23-98 post 10 989 5.11 .03 130 11.9 .9

RW 30-0087 1-25-99 post 11 337 5.22 .12 235 9.3 1.0

Table 4. Field water-quality analyses for ground-water samples collected near the granular-iron permeable reactive barriers, 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.—Continued

[Locations of wells are shown in figure 2. meq/L, milliequivalents per liter; μM, micromoles per liter; μS/cm, microsiemens per centimeter at 25 degrees Celsius; 

NTU, Nephelometric Turbidity Units; na, only field parameters measured; --, no data]

Well number

Date

sample

taken

Sampling 

round

Specific 

conductance 

(μS/cm)

pH

(standard units)

Alkalinity 

(meq/L)

Oxygen, 

dissolved

(μM)

Temperature 

(°C)

Turbidity

(NTU)
36 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000

RW 30-0087 3-24-99 post 12 147 5.26 0.02 261 10.1 1.3

RW 30-0087 6-21-99 post 13 437 4.86 -- 280 13.2 .4

RW 30-0087 11-02-99 post 15 290 5.11 -- 282 13.4 1.8

RW 30-0087 2-08-00 post 17 373 4.83 -- 233 10.0 .6

RW 30-0096 7-23-98 post 2 553 6.50 1.19 0 19.1 137.0

RW 30-0096 7-29-98 post 3 439 6.77 1.52 0 18.1 23.0

RW 30-0096 8-05-98 post 4 390 6.98 1.62 1 17.1 25.2

RW 30-0096 8-13-98 post 5 340 6.79 1.63 9 12.9 5.0

RW 30-0096 8-20-98 post 6 397 6.76 1.52 0 12.8 3.8

RW 30-0096 9-02-98 post 7 293 6.70 1.36 1 12.7 2.0

RW 30-0096 10-02-98 post 8 1,482 5.03 8.70 7 13.4 7.6

RW 30-0096 10-26-98 post 9 313 5.98 2.60 0 12.2 1.5

RW 30-0096 11-23-98 post 10 201 6.18 .78 38 11.7 4.1

RW 30-0096 1-25-99 post 11 153 6.18 .32 150 9.3 --

RW 30-0096 3-24-99 post 12 140 6.16 .65 149 10.5 5.7

RW 30-0096 6-21-99 post 13 179 6.21 -- 147 13.9 .7

RW 30-0096 11-02-99 post 15 148 5.68 -- 152 13.6 1.2

RW 30-0096 2-08-00 post 17 174 6.55 -- 143 8.6 2.2

RW 30-0100 7-23-98 post 2 540 5.07 .28 54 19.0 6.0

RW 30-0100 7-29-98 post 3 411 5.11 .25 24 16.3 12.3

RW 30-0100 8-05-98 post 4 135 5.78 .38 128 15.5 8.7

RW 30-0100 8-13-98 post 5 114 5.87 .37 172 12.8 3.5

RW 30-0100 8-20-98 post 6 116 5.96 .29 225 12.7 3.7

RW 30-0100 9-02-98 post 7 106 5.72 .29 259 13.0 1.0

RW 30-0100 10-02-98 post 8 468 4.34 .22 123 13.2 4.6

RW 30-0100 10-26-98 post 9 112 4.66 .19 160 12.3 1.2

RW 30-0100 11-23-98 post 10 108 5.44 .08 241 12.5 3.2

RW 30-0100 1-25-99 post 11 144 5.43 .14 305 9.3 3.1

RW 30-0100 3-24-99 post 12 132 5.49 .11 298 10.1 1.0

RW 30-0100 6-21-99 post 13 116 5.56 -- 306 13.2 .5

RW 30-0100 11-02-99 post 15 136 5.23 -- 356 13.2 .5

RW 30-0100 2-08-00 post 17 121 5.55 -- 354 10.2 .4

RW 30-0106 7-23-98 post 2 118 5.96 .21 199 18.3 102.0

RW 30-0106 7-29-98 post 3 155 5.85 .18 113 18.0 6.0

RW 30-0106 8-05-98 post 4 162 5.73 .21 106 17.8 3.9

RW 30-0106 8-13-98 post 5 200 6.09 .64 3 13.1 1.5

RW 30-0106 8-20-98 post 6 172 6.13 .44 91 12.9 3.1

RW 30-0106 9-02-98 post 7 103 6.03 .26 188 13.2 .7

RW 30-0106 10-02-98 post 8 176 5.20 1.30 9 13.0 3.7

RW 30-0106 10-26-98 post 9 731 4.38 6.72 4 12.2 .8

RW 30-0106 11-23-98 post 10 224 4.51 1.32 25 12.4 1.8

RW 30-0106 1-25-99 post 11 113 5.72 .28 191 8.0 1.3

Table 4. Field water-quality analyses for ground-water samples collected near the granular-iron permeable reactive barriers, 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.—Continued

[Locations of wells are shown in figure 2. meq/L, milliequivalents per liter; μM, micromoles per liter; μS/cm, microsiemens per centimeter at 25 degrees Celsius; 

NTU, Nephelometric Turbidity Units; na, only field parameters measured; --, no data]

Well number

Date

sample

taken

Sampling 

round

Specific 

conductance 

(μS/cm)

pH

(standard units)

Alkalinity 

(meq/L)

Oxygen, 

dissolved

(μM)

Temperature 

(°C)

Turbidity

(NTU)
Table 4 37

RW 30-0106 3-24-99 post 12 85 6.36 0.07 199 9.8 0.5

RW 30-0106 6-21-99 post 13 171 4.88 -- 250 13.7 .4

RW 30-0106 11-2-99 post 15 138 4.98 -- 310 12.8 .9

RW 30-0106 2-08-00 post 17 125 5.02 -- 349 10.1 .4

RW 30-0117 7-23-98 post 2 85 5.72 .16 259 17.0 14.0

RW 30-0117 7-29-98 post 3 82 5.76 .13 262 17.2 26.0

RW 30-0117 8-05-98 post 4 80 5.74 .13 276 15.4 31.6

RW 30-0117 8-13-98 post 5 80 5.70 .18 325 12.3 9.6

RW 30-0117 8-20-98 post 6 97 5.73 .12 319 12.3 9.9

RW 30-0117 9-02-98 post 7 88 5.74 .12 341 11.9 1.6

RW 30-0117 10-02-98 post 8 1,057 4.57 4.26 66 12.8 6.9

RW 30-0117 10-26-98 post 9 76 4.73 .07 153 12.3 .8

RW 30-0117 11-23-98 post 10 82 5.04 .01 185 11.5 1.1

RW 30-0117 1-25-99 post 11 87 4.80 .03 350 9.1 1.1

RW 30-0117 3-24-99 post 12 89 4.82 .00 312 9.7 1.8

RW 30-0117 6-21-99 post 13 121 5.08 -- 297 12.5 .5

RW 30-0117 11-02-99 post 15 175 5.34 -- 321 13.3 .5

RW 30-0117 2-08-00 post 17 210 5.44 -- 347 9.9 .6

Table 4. Field water-quality analyses for ground-water samples collected near the granular-iron permeable reactive barriers, 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.—Continued

[Locations of wells are shown in figure 2. meq/L, milliequivalents per liter; μM, micromoles per liter; μS/cm, microsiemens per centimeter at 25 degrees Celsius; 

NTU, Nephelometric Turbidity Units; na, only field parameters measured; --, no data]

Well number

Date

sample

taken

Sampling 

round

Specific 

conductance 

(μS/cm)

pH

(standard units)

Alkalinity 

(meq/L)

Oxygen, 

dissolved

(μM)

Temperature 

(°C)

Turbidity

(NTU)
38 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000

Date

sample

taken

Specific

conductance

(μS/cm)

pH

(standard

units)

Oxygen,

dissolved

(μM)

6-04-98 69 5.73 302

6-05-98 70 5.72 305

6-06-98 70 5.74 297

6-08-98 68 5.72 309

6-09-98 68 5.72 307

6-10-98 69 5.74 307

6-11-98 69 5.79 300

6-12-98 68 5.79 296

6-13-98 69 5.79 290

6-17-98 67 5.78 272

6-18-98 68 5.83 274

6-19-98 65 5.83 261

6-20-98 67 5.81 262

6-21-98 65 5.79 258

6-22-98 64 5.81 254

6-23-98 66 5.81 256

6-24-98 65 5.80 246

6-25-98 65 5.79 263

6-26-98 66 5.82 277

6-27-98 65 5.80 268

6-28-98 66 5.79 266

6-29-98 67 5.81 259

6-30-98 66 5.82 267

7-01-98 69 5.82 276

7-02-98 68 5.82 287

7-03-98 70 5.81 284

7-04-98 70 5.80 282

7-05-98 69 5.82 284

7-06-98 72 5.86 294

7-07-98 70 5.81 286

7-08-98 72 5.82 290

7-09-98 74 5.78 322

7-10-98 73 5.76 303

7-11-98 74 5.77 312

7-12-98 72 5.76 305

7-13-98 76 5.79 316

7-14-98 75 5.76 305

7-15-98 76 5.79 308

7-16-98 78 5.78 314

7-17-98 78 5.77 315

7-18-98 80 5.77 324

7-19-98 81 5.77 329

7-20-98 81 5.78 333

7-22-98 86 5.78 344

7-24-98 86 5.79 339

7-26-98 88 5.80 342

7-28-98 92 5.76 336

7-30-98 97 5.73 320

8-01-98 105 5.76 292

8-03-98 119 5.72 240

8-05-98 128 5.67 194

8-07-98 150 5.64 140

8-09-98 195 5.59 90

8-11-98 233 5.53 45

8-13-98 298 5.48 9

8-15-98 331 5.44 18

8-17-98 391 5.45 9

8-19-98 407 5.52 12

8-21-98 398 5.60 14

8-23-98 423 5.58 16

8-25-98 423 5.62 9

8-27-98 449 5.65 5

8-29-98 453 5.76 5

8-31-98 467 5.84 5

9-02-98 508 5.92 6

9-04-98 579 5.99 4

9-06-98 619 6.04 6

9-08-98 665 6.06 5

9-10-98 704 6.10 5

9-12-98 728 6.10 6

9-14-98 756 6.12 7

9-16-98 772 6.14 7

9-18-98 762 6.16 6

9-20-98 791 6.15 7

9-22-98 809 6.16 8

9-24-98 821 5.91 0

9-26-98 874 5.89 0

9-28-98 916 5.87 0

9-30-98 929 5.88 0

10-02-98 904 6.09 0

Date

sample

taken

Specific

conductance

(μS/cm)

pH

(standard

units)

Oxygen,

dissolved

(μM)

Table 5. Selected field water-quality analyses for ground-water samples collected by the Robowell system at well RW 27-0102A near 

the granular-iron permeable reactive barriers, Massachusetts Military Reservation, Cape Cod, Massachusetts, June 1998–October 1999.

[Location of well RW 27-0102A is shown in figure 2. μM, micromoles per liter; μS/cm, microsiemens per centimeter at 25 degrees Celsius]
Table 5 39

Date

sample

taken

Specific

conductance

(μS/cm)

pH

(standard

units)

Oxygen,

dissolved

(μM)

10-04-98 864 6.12 0

10-06-98 813 6.17 0

10-08-98 768 6.21 0

10-10-98 711 6.24 0

10-12-98 715 6.25 0

10-14-98 678 6.28 0

10-16-98 664 6.29 0

10-18-98 636 6.31 0

10-20-98 592 6.33 0

10-22-98 547 6.37 0

10-24-98 509 6.39 0

10-26-98 438 6.39 0

10-28-98 422 6.42 0

10-30-98 430 6.44 0

11-01-98 437 6.44 0

11-02-98 396 6.47 0

110-4-98 410 6.44 0

11-06-98 414 6.43 0

11-08-98 438 6.42 0

11-10-98 462 6.41 0

11-12-98 475 6.38 0

11-14-98 490 6.38 0

11-16-98 508 6.36 0

11-18-98 538 6.36 0

11-20-98 559 6.35 0

11-22-98 563 6.33 0

11-24-98 575 6.32 0

12-09-98 578 6.49 0

12-11-98 596 6.48 0

12-13-98 640 6.47 0

12-15-98 702 6.43 0

12-17-98 765 6.41 0

12-19-98 823 6.37 0

12-21-98 841 6.33 0

12-23-98 841 6.30 0

12-25-98 838 6.28 0

12-27-98 824 6.29 0

12-29-98 811 6.29 0

1-04-99 751 6.35 0

1-06-99 705 6.32 0

1-08-99 651 6.34 0

1-10-99 579 6.36 0

1-11-99 543 6.28 0

1-13-99 496 6.26 0

1-15-99 457 6.28 0

1-17-99 440 6.31 0

1-19-99 405 6.28 0

1-21-99 401 6.27 0

1-23-99 387 6.24 0

1-25-99 357 6.29 0

1-27-99 291 6.28 0

1-29-99 263 6.36 0

1-31-99 249 6.37 0

2-02-99 251 6.36 0

2-04-99 247 6.40 0

2-06-99 246 6.41 0

2-08-99 224 6.43 0

2-09-99 193 6.40 0

2-11-99 173 6.28 0

2-13-99 172 6.35 0

2-15-99 173 6.33 0

2-17-99 171 6.31 0

2-19-99 170 6.33 0

2-21-99 169 6.30 0

2-23-99 167 6.28 0

2-25-99 167 6.27 0

2-27-99 167 6.26 0

3-01-99 166 6.28 0

3-03-99 166 6.25 0

3-05-99 164 6.22 0

3-07-99 164 6.23 0

3-09-99 163 6.20 0

3-11-99 162 6.20 0

3-13-99 161 6.20 0

3-16-99 158 6.24 0

3-17-99 161 6.23 0

3-18-99 162 6.24 0

3-19-99 161 6.20 0

3-20-99 161 6.20 0

3-21-99 160 6.18 0

Date

sample

taken

Specific

conductance

(μS/cm)

pH

(standard

units)

Oxygen,

dissolved

(μM)

Table 5. Selected field water-quality analyses for ground-water samples collected by the Robowell system at well RW 27-0102A near 

the granular-iron permeable reactive barriers, Massachusetts Military Reservation, Cape Cod, Massachusetts, June 1998–October 

1999.—Continued

[Location of well RW 27-0102A is shown in figure 2. μM, micromoles per liter; μS/cm, microsiemens per centimeter at 25 degrees Celsius]
40 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000

Date

sample

taken

Specific

conductance

(μS/cm)

pH

(standard

units)

Oxygen,

dissolved

(μM)

3-22-99 161 6.18 0

3-23-99 161 6.16 0

3-24-99 160 6.15 0

3-25-99 160 6.15 0

3-26-99 160 6.14 0

3-27-99 162 6.18 0

3-28-99 161 6.14 0

3-29-99 160 6.13 0

3-30-99 160 6.14 0

3-31-99 160 6.11 0

4-01-99 160 6.13 0

4-02-99 160 6.11 0

4-13-99 175 5.81 0

4-15-99 174 5.84 0

4-17-99 175 5.85 0

4-19-99 176 5.86 0

4-21-99 178 5.88 0

4-23-99 178 5.89 0

4-25-99 177 5.88 0

4-27-99 178 5.90 0

4-29-99 178 5.90 0

5-01-99 180 5.92 0

5-03-99 179 5.92 0

5-05-99 179 5.97 0

5-07-99 180 5.95 0

5-09-99 181 5.95 0

5-15-99 182 6.02 0

5-17-99 183 6.03 0

5-19-99 183 6.02 0

5-21-99 182 6.07 0

5-23-99 184 6.07 0

5-25-99 184 6.10 0

5-27-99 183 6.10 0

5-29-99 183 6.10 0

5-31-99 184 6.16 0

6-02-99 184 6.17 0

6-04-99 184 6.16 0

6-06-99 184 6.20 0

6-08-99 183 6.20 0

6-10-99 181 6.24 0

6-16-99 179 6.25 0

6-18-99 172 6.22 0

6-20-99 174 6.20 0

6-22-99 174 6.20 0

6-24-99 172 6.18 0

6-26-99 171 6.17 0

6-28-99 172 6.18 0

6-30-99 170 6.18 0

7-02-99 168 6.14 0

7-04-99 167 6.13 0

7-06-99 168 6.16 0

7-08-99 167 6.15 0

7-10-99 166 6.14 0

7-12-99 167 6.14 0

7-14-99 164 6.18 0

8-11-99 162 6.13 0

8-15-99 151 6.16 0

8-18-99 153 6.19 0

8-23-99 152 6.21 0

8-27-99 152 6.22 0

8-31-99 151 6.24 0

9-04-99 151 6.27 0

9-08-99 150 6.29 0

9-12-99 148 6.29 0

9-16-99 147 6.32 0

9-20-99 144 6.36 0

9-24-99 142 6.37 0

9-28-99 140 6.39 0

10-02-99 139 6.40 0

10-06-99 136 6.43 0

Date

sample

taken

Specific

conductance

(μS/cm)

pH

(standard

units)

Oxygen,

dissolved

(μM)

Table 5. Selected field water-quality analyses for ground-water samples collected by the Robowell system at well RW 27-0102A near 

the granular-iron permeable reactive barriers, Massachusetts Military Reservation, Cape Cod, Massachusetts, June 1998–October 

1999.—Continued

[Location of well RW 27-0102A is shown in figure 2. μM, micromoles per liter; μS/cm, microsiemens per centimeter at 25 degrees Celsius]
Table 6 41

M

Table 6. Anions and ammonium analyses for ground-water samples collected near the granular-iron permeable reactive barriers, 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.

[Well number: 1Source of data: U.S. Geological Survey National Water Quality Laboratory. Source of nitrite, nitrate, ammonium, chloride, and sulfate data: 

Richard L. Smith, U.S. Geological Survey, National Research Program, Boulder, CO. Locations of wells are shown in figure 2. -D, duplicate; μM, micromoles per 

liter; --, no data; <, actual value is less than value shown]

Well number

Date

sample

taken

Sampling

round

Nitrite,

dissolved

(μM)

Nitrate,

dissolved

(μM)

Ammonium,

dissolved

(μM)

Chloride,

dissolved

(μM)

Sulfate,

dissolved

(μM)

MW 14B-0097 7-23-97 pre 2 <0.7 62.2 <5.0 546 47.1

MW 14B-0097 9-18-97 pre 3 <.7 26.0 <5.0 172 98.0

MW 14B-0097 6-23-99 post 13 <.7 101.9 8.3 653 116.5

MW 14A-0124 7-23-97 pre 2 <.7 78.3 6.0 222 45.3

MW 14A-0124 9-18-97 pre 3 <.7 43.0 <5.0 224 45.9

MW 14A-0124 6-23-99 post 13 <.7 98.4 5.3 2,163 22.2

RW 24-0094 9-17-97 pre 3 <.7 14.0 <5.0 624 52.2

RW 24-0094 5-19-98 pre 4 <.7 40.8 9.8 200 44.7

RW 24-00941 5-19-98 pre 4 .7 34.0 <5.0 214 35.2

RW 24-0094 7-14-98 post 1 <.7 96.1 <5.0 300 34.7

RW 24-0094 7-29-98 post 3 <.7 86.2 <5.0 389 22.5

RW 24-0094 8-05-98 post 4 <.7 73.2 <5.0 444 25.1

RW 24-0094 8-14-98 post 5 <.7 56.5 <5.0 636 22.2

RW 24-0094 8-20-98 post 6 <.7 65.7 <5.0 574 25.9

RW 24-0094 9-02-98 post 7 <.7 58.2 <5.0 1,394 60.4

RW 24-0094 10-02-98 post 8 <.7 100.6 <5.0 2,010 97.0

RW 24-0094 10-27-98 post 9 <.7 143.7 <5.0 2,519 111.0

RW 24-0094 11-24-98 post 10 <.7 23.7 <5.0 1,677 76.1

RW 24-0094 1-26-99 post 11 <.7 <5.0 <5.0 596 43.1

RW 24-0094-D 1-26-99 post 11 -- -- <5.0 --

RW 24-0094 3-25-99 post 12 <.7 <5.0 17.2 453 12.5

RW 24-0094 6-23-99 post 13 <.7 <5.0 16.2 545 24.0

RW 24-0094 11-02-99 post 15 <.7 <5.0 7.3 614 64.0

RW 24-00941 11-02-99 post 15 <.7 -- -- -- --

RW 24-0094 2-09-00 post 17 <.7 9.4 5.8 620 47.1

RW 24A-0100 7-01-97 pre 1 <.7 38.2 <5.0 1,001 48.7

RW 24A-0100-D 7-01-97 pre 1 <.7 37.6 <5.0 1,034 50.1

RW 24A-0100 7-21-97 pre 2 <.7 28.4 12.2 1,422 30.7

RW 24A-0100 9-17-97 pre 3 <.7 16.8 <5.0 1,448 35.6

RW 24A-0100 5-19-98 pre 4 <.7 48.9 5.7 331 57.7

RW 24A-01001 5-19-98 pre 4 <.7 43.6 4.4 367 49.0

RW 24A-0100 7-14-98 post 1 <.7 68.0 <5.0 403 43.5

RW 24A-0100 7-29-98 post 3 <.7 60.4 6.2 499 53.7

RW 24A-0100 8-05-98 post 4 1.34 44.7 <5.0 646 63.3

RW 24A-0100 8-14-98 post 5 <.7 42.9 <5.0 641 59.6

RW 24A-0100 8-20-98 post 6 <.7 19.2 <5.0 1,244 54.6

RW 24A-0100 9-02-98 post 7 <.7 <5.0 <5.0 2,728 39.5

RW 24A-0100 10-02-98 post 8 <.7 <5.0 <5.0 1,453 21.0

RW 24A-0100 10-27-98 post 9 <.7 <5.0 <5.0 1,017 36.8

RW 24A-0100 11-24-98 post 10 <.7 <5.0 <5.0 2,370 <5.0
42 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000

RW 24A-0100 1-26-99 post 11 <0.7 <5.0 8.2 382 16.7

RW 24A-0100 3-25-99 post 12 <.7 <5.0 16.5 602 <5.0

RW 24A-0100 6-22-99 post 13 <.7 <5.0 17.6 474 59.1

RW 24A-0100 11-02-99 post 15 <.7 <5.0 12.7 475 89.5

RW 24A-0100 1-11-00 post 16 <.7 13.2 14.1 481 103.2

RW 24A-0100 2-09-00 post 17 <.7 27.1 17.4 539 88.3

RW 24B-0104 7-01-97 pre 1 <.7 65.1 <5.0 373 99.4

RW 24B-0104 7-21-97 pre 2 <.7 60.8 9.2 465 81.3

RW 24B-0104 9-17-97 pre 3 <.7 32.3 <5.0 1,693 42.8

RW 24B-0104 5-19-98 pre 4 <.7 61.0 <5.0 264 98.6

RW 24B-01041 5-19-98 pre 4 .7 57.4 3.7 282 93.6

RW 24B-0104 7-14-98 post 1 <.7 65.6 10.3 289 74.1

RW 24B-0104-D 7-14-98 post 1 <.7 67.3 5.0 301 85.6

RW 24B-0104 8-14-98 post 5 <.7 65.9 6.7 458 81.6

RW 24B-0104 8-20-98 post 6 <.7 56.8 <5.0 458 82.4

RW 24B-0104 9-02-98 post 7 <.7 13.5 <5.0 1,485 80.2

RW 24B-0104 10-02-98 post 8 <.7 <5.0 <5.0 2,193 45.6

RW 24B-0104 10-27-98 post 9 <.7 <5.0 <5.0 1,834 <5.0

RW 24B-0104 11-24-98 post 10 1.02 <5.0 <5.0 676 <5.0

RW 24B-0104-D 11-24-98 post 10 1.08 <5.0 <5.0 768 <5.0

RW 24B-0104 1-26-99 post 11 <.7 <5.0 5.0 410 23.2

RW 24B-0104-D 1-26-99 post 11 <.7 <5.0 -- 421 23.8

RW 24B-0104 3-25-99 post 12 <.7 <5.0 11.0 727 6.5

RW 24B-0104-D 3-25-99 post 12 <.7 <5.0 7.5 743 6.9

RW 24B-0104 6-22-99 post 13 <.7 <5.0 9.3 774 48.6

RW 24B-0104 11-02-99 post 15 <.7 <5.0 15.9 382 98.3

RW 24B-0104-D 11-02-99 post 15 <.7 <5.0 16.1 384 97.0

RW 24B-0104 1-11-00 post 16 <.7 7.9 18.9 383 105.0

RW 24B-0104 2-09-00 post 17 <.7 15.6 16.9 447 93.0

RW 24C-0110 7-01-97 pre 1 <.7 67.3 13.5 223 105.3

RW 24C-0110 7-21-97 pre 2 <.7 69.8 <5.0 195 97.8

RW 24C-0110-D 7-21-97 pre 2 <.7 70.6 <5.0 191 95.6

RW 24C-0110 9-17-97 pre 3 <.7 70.7 <5.0 202 117.1

RW 24C-0110 5-19-98 pre 4 <.7 58.7 9.6 217 91.3

RW 24C-01101 5-19-98 pre 4 .7 52.9 3.3 231 86.4

RW 24C-0110 7-15-98 post 1 <.7 67.5 <5.0 269 108.2

RW 24C-0110 8-14-98 post 5 <.7 45.7 <5.0 159 96.5

RW 24C-0110 10-02-98 post 8 .82 24.6 <5.0 815 94.9

RW 24C-0110 10-27-98 post 9 <.7 <5.0 <5.0 812 59.8

Table 6. Anions and ammonium analyses for ground-water samples collected near the granular-iron permeable reactive barriers, 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.—Continued

[Well number: 1Source of data: U.S. Geological Survey National Water Quality Laboratory. Source of nitrite, nitrate, ammonium, chloride, and sulfate data: 

Richard L. Smith, U.S. Geological Survey, National Research Program, Boulder, CO. Locations of wells are shown in figure 2. -D, duplicate; μM, micromoles per 

liter; --, no data; <, actual value is less than value shown]

Well number

Date

sample

taken

Sampling

round

Nitrite,

dissolved

(μM)

Nitrate,

dissolved

(μM)

Ammonium,

dissolved

(μM)

Chloride,

dissolved

(μM)

Sulfate,

dissolved

(μM)
Table 6 43

RW 24C-0110-D 10-27-98 post 9 <0.7 <5.0 <5.0 794 58.3

RW 24C-0110 11-24-98 post 10 <.7 <5.0 <5.0 325 15.0

RW 24C-0110 1-26-99 post 11 <.7 <5.0 <5.0 225 <5.0

RW 24C-0110 3-25-99 post 12 <.7 <5.0 6.6 190 35.4

RW 24C-0110 6-22-99 post 13 2.16 <5.0 15.1 235 64.6

RW 24C-0110 11-02-99 post 15 <.7 27.2 7.4 1,261 10.2

RW 24C-0110 1-11-00 post 16 <.7 34.2 6.0 1,110 44.1

RW 24C-0110 2-09-00 post 17 <.7 35.3 <5.0 1,048 47.1

RW 24D-0115 7-01-97 pre 1 <.7 77.4 17.1 160 106.1

RW 24D-0115 7-21-97 pre 2 <.7 73.2 7.0 146 118.9

RW 24D-0115 9-17-97 pre 3 <.7 68.1 <5.0 139 109.2

RW 24D-0115-D 9-17-97 pre 3 <.7 68.6 <5.0 137 116.5

RW 24D-0115 5-19-98 pre 4 <.7 56.5 13.4 135 104.5

RW 24D-01151 5-19-98 pre 4 <.7 51.3 3.6 149 102.9

RW 24D-0115 7-15-98 post 1 <.7 56.8 <5.0 153 114.4

RW 24D-0115 8-14-98 post 5 <.7 96.9 6.2 189 100.0

RW 24D-0115 10-02-98 post 8 1.39 80.6 <5.0 189 110.7

RW 24D-0115 10-27-98 post 9 1.41 72.5 <5.0 256 116.4

RW 24D-0115 11-24-98 post 10 <.7 0.0 <5.0 204 <5.0

RW 24D-0115 1-26-99 post 11 <.7 20.6 6.0 217 31.8

RW 24D-0115 3-25-99 post 12 <.7 59.9 24.7 216 107.4

RW 24D-0115 6-22-99 post 13 2.14 117.6 10.9 264 101.5

RW 24D-0115 11-02-99 post 15 <.7 108.7 <5.0 1,479 42.7

RW 24D-0115 1-11-00 post 16 <.7 112.7 <5.0 1,458 48.2

RW 24D-0115 2-09-00 post 17 <.7 124.7 <5.0 1,456 49.4

RW 25A-0092 7-02-97 pre 1 <.7 21.8 9.4 422 88.9

RW 25A-0092 7-22-97 pre 2 <.7 22.3 <5.0 327 78.7

RW 25A-0092 9-18-97 pre 3 <.7 24.6 <5.0 176 69.3

RW 25A-0092 5-20-98 pre 4 <.7 89.8 10.6 172 45.6

RW 25A-00921 5-20-98 pre 4 .7 88.5 5.1 192 35.2

RW 25A-0092 6-23-99 post 13 2.27 87.8 12.3 344 121.9

RW 25A-0092 11-03-99 post 15 <.7 123.6 <5.0 389 112.5

RW 25A-0092 1-11-00 post 16 <.7 143.9 <5.0 407 120.5

RW 25A-0092 2-08-00 post 17 <.7 159.3 <5.0 385 117.8

RW 25B-0099 7-02-97 pre 1 <.7 50.4 <5.0 629 106.6

RW 25B-0099 7-22-97 pre 2 <.7 70.9 9.6 312 98.5

RW 25B-0099 9-18-97 pre 3 <.7 81.4 <5.0 246 97.0

RW 25B-0099 5-20-98 pre 4 <.7 110.1 12.2 244 71.3

RW 25B-00991 5-20-98 pre 4 <.7 108.5 4.9 262 65.5

Table 6. Anions and ammonium analyses for ground-water samples collected near the granular-iron permeable reactive barriers, 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.—Continued

[Well number: 1Source of data: U.S. Geological Survey National Water Quality Laboratory. Source of nitrite, nitrate, ammonium, chloride, and sulfate data: 

Richard L. Smith, U.S. Geological Survey, National Research Program, Boulder, CO. Locations of wells are shown in figure 2. -D, duplicate; μM, micromoles per 

liter; --, no data; <, actual value is less than value shown]

Well number

Date

sample

taken

Sampling

round

Nitrite,

dissolved

(μM)

Nitrate,

dissolved

(μM)

Ammonium,

dissolved

(μM)

Chloride,

dissolved

(μM)

Sulfate,

dissolved

(μM)
44 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000

RW 25B-0099 7-14-98 post 1 <0.7 109.6 <5.0 236 68.9

RW 25B-0099 7-23-98 post 2 <.7 108.1 <5.0 256 66.4

RW 25B-0099 8-13-98 post 5 <.7 99.2 13.4 257 71.0

RW 25B-0099 10-01-98 post 8 <.7 102.9 <5.0 360 75.6

RW 25B-0099 10-26-98 post 9 <.7 106.5 <5.0 476 71.3

RW 25B-0099 11-23-98 post 10 <.7 106.0 5.8 613 59.2

RW 25B-0099 1-26-99 post 11 <.7 112.4 <5.0 718 61.6

RW 25B-0099 3-24-99 post 12 <.7 109.3 9.3 476 97.9

RW 25B-0099 6-21-99 post 13 2.10 101.4 11.1 369 125.3

RW 25B-0099 11-03-99 post 15 <.7 175.0 <5.0 445 120.7

RW 25B-0099 1-11-00 post 16 <.7 241.2 <5.0 622 127.2

RW 25B-0099 2-08-00 post 17 <.7 242.8 <5.0 718 118.2

RW 25C-0105 7-02-97 pre 1 <.7 56.8 13.4 502 74.8

RW 25C-0105 7-22-97 pre 2 <.7 62.5 <5.0 539 70.2

RW 25C-0105 9-18-97 pre 3 <.7 67.1 <5.0 191 89.5

RW 25C-0105 5-20-98 pre 4 <.7 74.4 19.7 247 81.4

RW 25C-01051 5-20-98 pre 4 .8 69.6 3.9 268 76.1

RW 25C-0105 7-14-98 post 1 <.7 101.9 9.9 290 68.9

RW 25C-0105 7-23-98 post 2 <.7 109.0 13.6 295 68.2

RW 25C-0105 8-13-98 post 5 <.7 109.5 <5.0 295 72.5

RW 25C-0105 10-02-98 post 8 <.7 93.7 <5.0 332 74.7

RW 25C-0105 10-26-98 post 9 <.7 91.2 <5.0 384 82.0

RW 25C-0105 11-23-98 post 10 <.7 93.2 9.1 482 59.5

RW 25C-0105 1-26-99 post 11 <.7 105.9 <5.0 816 42.2

RW 25C-0105 3-24-99 post 12 <.7 114.0 9.7 953 36.8

RW 25C-0105 6-21-99 post 13 2.07 117.2 11.2 870 64.9

RW 25C-0105 11-03-99 post 15 <.7 136.7 <5.0 607 117.1

RW 25C-0105 1-11-00 post 16 <.7 154.3 <5.0 496 149.6

RW 25C-0105 2-08-00 post 17 <.7 168.0 <5.0 381 162.6

RW 25D-0110 7-02-97 pre 1 <.7 57.5 10.3 180 103.1

RW 25D-0110 7-22-97 pre 2 <.7 61.7 5.4 304 75.9

RW 25D-0110 9-18-97 pre 3 <.7 63.7 <5.0 150 92.5

RW 25D-0110 5-20-98 pre 4 <.7 49.8 <5.0 155 92.8

RW 25D-01101 5-20-98 pre 4 <.7 42.8 3.5 158 91.7

RW 25D-0110 6-23-99 post 13 2.15 111.6 8.3 976 38.0

RW 25D-0110 11-03-99 post 15 <.7 130.7 <5.0 1,193 33.5

RW 25D-0110 1-11-00 post 16 <.7 131.8 <5.0 1,085 51.6

RW 25D-0110 2-08-00 post 17 <.7 128.1 <5.0 981 70.0

RW 25E-0120 7-22-97 pre 2 <.7 134.7 9.1 207 75.7

RW 25E-0120 9-18-97 pre 3 <.7 87.2 <5.0 219 74.4

RW 25E-0120 5-20-98 pre 4 <.7 146.9 6.5 224 81.3

RW 25E-01201 5-20-98 pre 4 .7 149.9 4.4 245 74.9

RW 25E-0120 6-23-99 post 13 <.7 6.5 5.6 318 74.9

Table 6. Anions and ammonium analyses for ground-water samples collected near the granular-iron permeable reactive barriers, 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.—Continued

[Well number: 1Source of data: U.S. Geological Survey National Water Quality Laboratory. Source of nitrite, nitrate, ammonium, chloride, and sulfate data: 

Richard L. Smith, U.S. Geological Survey, National Research Program, Boulder, CO. Locations of wells are shown in figure 2. -D, duplicate; μM, micromoles per 

liter; --, no data; <, actual value is less than value shown]

Well number

Date

sample

taken

Sampling

round

Nitrite,

dissolved

(μM)

Nitrate,

dissolved

(μM)

Ammonium,

dissolved

(μM)

Chloride,

dissolved

(μM)

Sulfate,

dissolved

(μM)
Table 6 45

RW 25E-0120 11-03-99 post 15 <0.7 <5.0 <5.0 376 63.9

RW 25E-0120 1-11-00 post 16 <.7 8.7 <5.0 376 71.3

RW 25E-0120 2-08-00 post 17 <.7 7.9 <5.0 359 69.8

RW 26-0087 5-20-98 pre 4 <.7 130.7 13.4 812 197.8

RW 26-00871 5-20-98 pre 4 <.7 132.8 4.8 874 197.8

RW 26-0087 6-23-99 post 13 <.7 151.9 6.3 1,015 209.2

RW 26-0087 8-10-99 post 14 <.7 166.6 <5.0 1,625 203.0

RW 26-0092 5-20-98 pre 4 <.7 124.7 10.9 231 84.4

RW 26-00921 5-20-98 pre 4 .7 122.8 1.7 243 80.2

RW 26-0092 6-23-99 post 13 <.7 67.9 5.6 525 107.2

RW 26-0092 8-10-99 post 14 <.7 55.7 <5.0 568 101.7

RW 26-0096 5-20-98 pre 4 <.7 87.8 <5.0 312 36.7

RW 26-00961 5-20-98 pre 4 .7 86.4 4.9 338 25.9

RW 26-0096 8-10-99 post 14 <.7 93.7 <5.0 529 119.8

RW 26-0100 5-20-98 pre 4 <.7 88.3 11.2 228 79.0

RW 26-01001 5-20-98 pre 4 .7 83.5 4.9 248 74.9

RW 26-0100 8-10-99 post 14 <.7 115.3 5.3 390 144.6

RW 26-0106 5-20-98 pre 4 <.7 50.7 <5.0 211 95.7

RW 26-0106-D 5-20-98 pre 4 <.7 50.4 8.3 211 95.4

RW 26-01061 5-20-98 pre 4 .7 44.2 4.9 231 92.6

RW 26-0106-D1 5-20-98 pre 4 <.7 44.0 4.5 228 93.6

RW 27-0098 5-19-98 pre 4 <.7 32.2 11.3 200 57.8

RW 27-00981 5-19-98 pre 4 .8 26.4 3.9 214 47.7

RW 27-0098 7-15-98 post 1 <.7 68.1 10.7 525 26.5

RW 27-0098 6-22-99 post 13 <.7 <5.0 7.9 396 72.3

RW 27-0098 2-09-00 post 17 <.7 <5.0 16.7 595 81.7

RW 27-0102 5-19-98 pre 4 <.7 65.4 <5.0 379 88.2

RW 27-01021 5-19-98 pre 4 <.7 61.5 1.6 395 85.5

RW 27-0102 7-15-98 post 1 <.7 54.1 7.7 255 73.9

RW 27-0102 6-22-99 post 13 <.7 <5.0 10.8 660 45.9

RW 27-0102 2-09-00 post 17 <.7 <5.0 24.4 483 89.6

RW 27-0108 5-19-98 pre 4 <.7 62.1 <5.0 240 90.4

RW 27-0108-D 5-19-98 pre 4 <.7 60.4 9.4 234 88.3

RW 27-01081 5-19-98 pre 4 <.7 58.8 5.4 251 88.6

RW 27-0108-D1 5-19-98 pre 4 <.7 57.8 4.2 248 86.4

RW 27-0108 7-15-98 post 1 <.7 63.5 <5.0 239 83.3

RW 27-0108-D 7-15-98 post 1 <.7 62.5 <5.0 229 85.1

RW 27-0108 6-22-99 post 13 <.7 <5.0 6.1 259 14.6

RW 27-0108 2-09-00 post 17 <.7 <5.0 <5.0 795 60.2

Table 6. Anions and ammonium analyses for ground-water samples collected near the granular-iron permeable reactive barriers, 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.—Continued

[Well number: 1Source of data: U.S. Geological Survey National Water Quality Laboratory. Source of nitrite, nitrate, ammonium, chloride, and sulfate data: 

Richard L. Smith, U.S. Geological Survey, National Research Program, Boulder, CO. Locations of wells are shown in figure 2. -D, duplicate; μM, micromoles per 

liter; --, no data; <, actual value is less than value shown]

Well number

Date

sample

taken

Sampling

round

Nitrite,

dissolved

(μM)

Nitrate,

dissolved

(μM)

Ammonium,

dissolved

(μM)

Chloride,

dissolved

(μM)

Sulfate,

dissolved

(μM)
46 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000

RW 27-0114 5-19-98 pre 4 <0.7 59.6 <5.0 130 106.6

RW 27-01141 5-19-98 pre 4 .7 54.3 3.1 138 104.2

RW 27-0114 7-15-98 post 1 <.7 53.6 <5.0 139 92.4

RW 27-0114 6-22-99 post 13 <.7 <5.0 25.7 297 90.7

RW 27-0114 2-09-00 post 17 <.7 112.2 <5.0 1,576 43.7

RW 27-0120 5-19-98 pre 4 <.7 93.8 11.4 181 86.3

RW 27-01201 5-19-98 pre 4 .9 92.8 3.9 195 84.2

RW 27-0120 7-15-98 post 1 <.7 127.8 12.4 600 98.8

RW 27-0120 6-22-99 post 13 <.7 <5.0 12.4 637 22.2

RW 27-0120 2-09-00 post 17 <.7 45.0 <5.0 919 104.0

RW 28-0107 6-22-99 post 13 <.7 <5.0 11.9 769 <5.0

RW 29-0107 6-22-99 post 13 <.7 <5.0 16.1 437 <5.0

RW 29-0111 6-23-99 post 13 <.7 <5.0 5.4 229 41.5

RW 30-0087 7-23-98 post 2 <.7 244.7 <5.0 3,267 99.5

RW 30-0087 7-29-98 post 3 <.7 229.3 <5.0 3,070 122.9

RW 30-0087 8-05-98 post 4 <.7 225.6 <5.0 2,917 125.9

RW 30-0087 8-13-98 post 5 <.7 201.2 <5.0 2,044 124.6

RW 30-0087 8-20-98 post 6 <.7 187.1 <5.0 2,184 155.7

RW 30-0087 9-02-98 post 7 <.7 176.1 <5.0 1,908 200.8

RW 30-0087 10-02-98 post 8 2.27 307.1 <5.0 6,270 137.0

RW 30-0087 10-26-98 post 9 5.90 235.9 <5.0 6,048 70.9

RW 30-0087 11-23-98 post 10 <.7 87.8 <5.0 2,346 44.6

RW 30-0087 1-25-99 post 11 <.7 162.6 <5.0 2,098 202.2

RW 30-0087 3-24-99 post 12 <.7 140.1 12.4 560 244.1

RW 30-0087 6-21-99 post 13 <.7 209.5 16.1 2,939 134.6

RW 30-0087 11-02-99 post 15 <.7 166.9 <5.0 1,809 193.6

RW 30-0087 2-08-00 post 17 <.7 197.2 6.3 2,596 151.0

RW 30-0096 7-23-98 post 2 <.7 7.0 <5.0 3,179 101.5

RW 30-0096 7-29-98 post 3 .71 26.0 <5.0 2,557 63.4

RW 30-0096 8-05-98 post 4 1.18 28.9 <5.0 1,850 49.0

RW 30-0096-D 8-05-98 post 4 1.21 30.8 <5.0 1,747 49.9

RW 30-0096 8-13-98 post 5 2.93 28.7 <5.0 1,338 35.9

RW 30-0096-D 8-13-98 post 5 3.05 29.6 <5.0 1,315 36.8

RW 30-0096 8-20-98 post 6 2.14 19.0 <5.0 1,296 27.4

RW 30-0096 9-02-98 post 7 <.7 45.3 15.9 967 48.7

RW 30-0096 10-02-98 post 8 3.43 37.2 24.1 1,190 113.2

Table 6. Anions and ammonium analyses for ground-water samples collected near the granular-iron permeable reactive barriers, 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.—Continued

[Well number: 1Source of data: U.S. Geological Survey National Water Quality Laboratory. Source of nitrite, nitrate, ammonium, chloride, and sulfate data: 

Richard L. Smith, U.S. Geological Survey, National Research Program, Boulder, CO. Locations of wells are shown in figure 2. -D, duplicate; μM, micromoles per 

liter; --, no data; <, actual value is less than value shown]

Well number

Date

sample

taken

Sampling

round

Nitrite,

dissolved

(μM)

Nitrate,

dissolved

(μM)

Ammonium,

dissolved

(μM)

Chloride,

dissolved

(μM)

Sulfate,

dissolved

(μM)
Table 6 47

RW 30-0096 10-26-98 post 9 <0.7 32.2 <5.0 421 79.3

RW 30-0096 11-23-98 post 10 <.7 59.5 13.2 344 68.8

RW 30-0096 1-25-99 post 11 <.7 76.0 8.5 365 76.1

RW 30-0096 3-24-99 post 12 <.7 79.3 15.5 510 64.5

RW 30-0096 6-21-99 post 13 <.7 73.6 13.8 978 60.2

RW 30-0096 11-02-99 post 15 <.7 88.5 <5.0 553 103.8

RW 30-0096 2-08-00 post 17 <.7 94.4 <5.0 1,000 77.3

RW 30-0100 7-23-98 post 2 <.7 19.3 <5.0 3,414 71.9

RW 30-0100 7-29-98 post 3 <.7 13.6 <5.0 2,156 81.4

RW 30-0100-D 7-29-98 post 3 <.7 13.1 <5.0 2,215 81.3

RW 30-0100 8-05-98 post 4 1.93 48.2 <5.0 644 83.8

RW 30-0100 8-13-98 post 5 <.7 63.1 6.9 492 78.3

RW 30-0100 8-20-98 post 6 1.18 75.8 8.9 395 83.2

RW 30-0100-D 8-20-98 post 6 .82 78.6 8.8 387 84.2

RW 30-0100 9-02-98 post 7 <.7 91.4 8.4 376 90.5

RW 30-0100-D 9-02-98 post 7 <.7 91.7 7.4 377 101.3

RW 30-0100 10-02-98 post 8 2.71 87.6 12.8 464 130.6

RW 30-0100-D 10-02-98 post 8 2.75 85.8 18.4 452 128.9

RW 30-0100 10-26-98 post 9 .71 77.9 <5.0 292 117.5

RW 30-0100 11-23-98 post 10 <.7 94.9 6.3 347 88.8

RW 30-0100 1-25-99 post 11 <.7 110.1 <5.0 594 70.5

RW 30-0100-D 1-25-99 post 11 <.7 130.1 -- 683 71.1

RW 30-0100 3-24-99 post 12 <.7 126.3 9.6 712 69.9

RW 30-0100-D 3-24-99 post 12 <.7 124.0 12.9 700 68.5

RW 30-0100 6-21-99 post 13 <.7 118.8 <5.0 485 112.8

RW 30-0100-D 6-21-99 post 13 <.7 117.8 5.3 483 113.5

RW 30-0100 11-02-99 post 15 <.7 122.7 <5.0 615 120.7

RW 30-0100-D 11-02-99 post 15 <.7 118.3 <5.0 633 116.3

RW 30-0100 2-08-00 post 17 <.7 262.1 <5.0 450 168.9

RW 30-0100-D 2-08-00 post 17 <.7 264.5 <5.0 451 168.1

RW 30-0106 7-23-98 post 2 <.7 67.6 6.3 573 92.3

RW 30-0106-D 7-23-98 post 2 <.7 65.0 <5.0 565 92.4

RW 30-0106 7-29-98 post 3 <.7 40.5 <5.0 966 78.3

RW 30-0106 8-05-98 post 4 <.7 18.6 <5.0 1,006 104.5

RW 30-0106 8-13-98 post 5 <.7 8.7 <5.0 1,166 71.1

Table 6. Anions and ammonium analyses for ground-water samples collected near the granular-iron permeable reactive barriers, 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.—Continued

[Well number: 1Source of data: U.S. Geological Survey National Water Quality Laboratory. Source of nitrite, nitrate, ammonium, chloride, and sulfate data: 

Richard L. Smith, U.S. Geological Survey, National Research Program, Boulder, CO. Locations of wells are shown in figure 2. -D, duplicate; μM, micromoles per 

liter; --, no data; <, actual value is less than value shown]

Well number

Date

sample

taken

Sampling

round

Nitrite,

dissolved

(μM)

Nitrate,

dissolved

(μM)

Ammonium,

dissolved

(μM)

Chloride,

dissolved

(μM)

Sulfate,

dissolved

(μM)
48 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000

RW 30-0106 8-20-98 post 6 <0.7 14.5 <5.0 745 87.4

RW 30-0106 9-02-98 post 7 1.00 37.1 <5.0 350 106.8

RW 30-0106 10-02-98 post 8 2.36 17.4 <5.0 537 137.2

RW 30-0106 10-26-98 post 9 <.7 25.4 <5.0 549 81.2

RW 30-0106-D 10-26-98 post 9 .80 26.5 <5.0 566 87.9

RW 30-0106 11-23-98 post 10 <.7 36.8 7.8 228 20.6

RW 30-0106 1-25-99 post 11 <.7 68.7 <5.0 273 72.0

RW 30-0106 3-24-99 post 12 <.7 76.6 <5.0 385 64.7

RW 30-0106 6-21-99 post 13 <.7 104.4 <5.0 1,096 37.7

RW 30-0106 11-02-99 post 15 <.7 104.8 <5.0 1,104 37.3

RW 30-0106-D 11-02-99 post 15 <.7 119.3 <5.0 623 116.9

RW 30-0106 2-08-00 post 17 <.7 172.1 <5.0 722 120.7

RW 30-0117 7-23-98 post 2 <.7 147.6 <5.0 296 84.7

RW 30-0117 7-29-98 post 3 <.7 165.2 <5.0 239 78.3

RW 30-0117 8-05-98 post 4 <.7 160.4 <5.0 234 83.7

RW 30-0117 8-13-98 post 5 <.7 161.2 <5.0 231 84.0

RW 30-0117 8-20-98 post 6 <.7 162.3 <5.0 236 84.6

RW 30-0117 9-02-98 post 7 <.7 154.0 <5.0 235 88.3

RW 30-0117 10-02-98 post 8 3.35 87.9 <5.0 574 176.8

RW 30-0117 10-26-98 post 9 <.7 106.9 <5.0 216 88.4

RW 30-0117 11-23-98 post 10 <.7 72.2 <5.0 217 92.5

RW 30-0117 1-25-99 post 11 <.7 40.8 <5.0 232 102.1

RW 30-0117-D 1-25-99 post 11 -- -- <5.0 -- --

RW 30-0117 3-24-99 post 12 <.7 73.1 <5.0 435 74.2

RW 30-0117 6-21-99 post 13 <.7 122.3 <5.0 646 75.3

RW 30-0117 11-02-99 post 15 <.7 134.6 -- 753 64.7

RW 30-0117 2-08-00 post 17 <.7 104.4 <5.0 1,161 105.2

Table 6. Anions and ammonium analyses for ground-water samples collected near the granular-iron permeable reactive barriers, 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.—Continued

[Well number: 1Source of data: U.S. Geological Survey National Water Quality Laboratory. Source of nitrite, nitrate, ammonium, chloride, and sulfate data: 

Richard L. Smith, U.S. Geological Survey, National Research Program, Boulder, CO. Locations of wells are shown in figure 2. -D, duplicate; μM, micromoles per 

liter; --, no data; <, actual value is less than value shown]

Well number

Date

sample

taken

Sampling

round

Nitrite,

dissolved

(μM)

Nitrate,

dissolved

(μM)

Ammonium,

dissolved

(μM)

Chloride,

dissolved

(μM)

Sulfate,

dissolved

(μM)
Table 7 49

Table 7. Carbon species analyses for ground-water samples collected near the granular-iron permeable reactive barriers, 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.

[Well number: 1Source of data: U.S. Geological Survey National Water Quality Laboratory. Source of data: Richard L. Smith, U.S. Geological Survey, National 

Research Program, Boulder, CO. Dissolved Inorganic Carbon: The values in this column include all the inorganic carbon species, including carbon dioxide. 

Locations of wells are shown in figure 2. -D, duplicate; μM, micromoles per liter; mM, millimoles per liter; <, actual value is less than value shown; --, no data]

Well number Date sample

taken Sampling round

Dissolved

organic carbon

(μM)

Total organic 

carbon

(μM)

Dissolved 

inorganic carbon 

including carbon 

dioxide

(mM)

Methane

(μM)

MW 14B-0097 7-23-97 pre 2 83 115 1.1 <0.2

MW 14B-0097 9-18-97 pre 3 48 49 1.0 <.2

MW 14A-0124 7-23-97 pre 2 61 75 .8 <.2

MW 14A-0124 9-18-97 pre 3 37 29 .3 <.2

RW 24-0094 9-17-97 pre 3 61 64 1.1 <.2

RW 24-0094 5-19-98 pre 4 57 69 .9 <.2

RW 24-00941 5-19-98 pre 4 42 -- -- --

RW 24-0094 7-14-98 post 1 44 43 .9 <.2

RW 24-0094 7-29-98 post 3 59 54 1.0 --

RW 24-0094 8-05-98 post 4 89 69 1.1 --

RW 24-0094 8-14-98 post 5 118 101 1.4 <.2

RW 24-0094 8-20-98 post 6 124 87 1.1 --

RW 24-0094 9-02-98 post 7 108 142 1.2 --

RW 24-0094 10-02-98 post 8 323 281 1.2 <.2

RW 24-0094 10-27-98 post 9 433 341 1.3 <.2

RW 24-0094 11-24-98 post 10 204 -- -- <.2

RW 24-0094 1-26-99 post 11 1,890 -- 2.6 18.0

RW 24-0094-D 1-26-99 post 11 1,910 -- -- --

RW 24-0094 3-25-99 post 12 -- -- 1.9 141.1

RW 24A-0100 7-01-97 pre 1 109 86 1.1 <.2

RW 24A-0100-D 7-01-97 pre 1 97 80 -- --

RW 24A-0100 7-21-97 pre 2 72 83 1.0 <.2

RW 24A-0100 9-17-97 pre 3 69 58 1.0 <.2

RW 24A-0100 5-19-98 pre 4 45 44 1.0 <.2

RW 24A-01001 5-19-98 pre 4 42 -- -- --

RW 24A-0100 7-14-98 post 1 47 69 1.1 <.2

RW 24A-0100 7-29-98 post 3 73 56 1.1 --

RW 24A-0100 8-05-98 post 4 98 92 1.2 --

RW 24A-0100 8-14-98 post 5 108 105 1.5 <.2

RW 24A-0100 8-20-98 post 6 940 933 1.7 --

RW 24A-0100 9-02-98 post 7 3,237 3,450 2.8 --

RW 24A-0100 10-02-98 post 8 2,237 2,400 2.9 <.2

RW 24A-0100 10-27-98 post 9 8,200 7,983 2.8 <.2

RW 24A-0100 11-24-98 post 10 4,533 -- 3.3 <.2

RW 24A-0100 1-26-99 post 11 1,533 -- 2.3 7.5

RW 24A-0100 3-25-99 post 12 -- -- 3.3 45.6

RW 24B-0104 7-01-97 pre 1 114 97 1.2 <.2

RW 24B-0104 7-21-97 pre 2 66 63 1.1 <.2

RW 24B-0104 9-17-97 pre 3 57 55 1.1 <.2

RW 24B-0104 5-19-98 pre 4 50 47 1.1 <.2

RW 24B-01041 5-19-98 pre 4 50 -- -- --
50 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000

RW 24B-0104 7-14-98 post 1 46 43 1.0 <0.2

RW 24B-0104-D 7-14-98 post 1 49 53 -- --

RW 24B-0104 8-14-98 post 5 82 50 1.3 <.2

RW 24B-0104 8-20-98 post 6 155 83 .9 --

RW 24B-0104 9-02-98 post 7 1,422 1,800 1.8 --

RW 24B-0104 10-02-98 post 8 3,193 3,147 3.2 <.2

RW 24B-0104 10-27-98 post 9 12,233 13,100 4.6 <.2

RW 24B-0104 11-24-98 post 10 16,833 -- 2.9 .2

RW 24B-0104-D 11-24-98 post 10 16,583 -- -- --

RW 24B-0104 1-26-99 post 11 383 -- 2.2 1.7

RW 24B-0104 3-25-99 post 12 -- -- 3.2 19.4

RW 24B-0104-D 3-25-99 post 12 -- -- 2.9 18.8

RW 24C-0110 7-01-97 pre 1 87 79 1.2 <.2

RW 24C-0110 7-21-97 pre 2 104 124 1.2 <.2

RW 24C-0110-D 7-21-97 pre 2 98 103 -- --

RW 24C-0110 9-17-97 pre 3 52 39 1.3 <.2

RW 24C-0110 5-19-98 pre 4 93 34 1.2 <.2

RW 24C-01101 5-19-98 pre 4 50 -- -- --

RW 24C-0110 7-15-98 post 1 34 34 1.1 <.2

RW 24C-0110 8-14-98 post 5 33 30 1.3 <.2

RW 24C-0110 10-02-98 post 8 1,025 1,030 1.3 <.2

RW 24C-0110 10-27-98 post 9 12,167 12,383 3.9 <.2

RW 24C-0110-D 10-27-98 post 9 11,667 12,450 -- --

RW 24C-0110 11-24-98 post 10 8,850 -- 2.8 <.2

RW 24C-0110 1-26-99 post 11 4,967 -- 2.8 .2

RW 24C-0110 3-25-99 post 12 -- -- 2.8 .6

RW 24D-0115 7-01-97 pre 1 218 48 1.2 <.2

RW 24D-0115 7-21-97 pre 2 71 83 1.2 <.2

RW 24D-0115 9-17-97 pre 3 38 43 1.2 <.2

RW 24D-0115-D 9-17-97 pre 3 50 31

RW 24D-0115 5-19-98 pre 4 41 31 1.2 <.2

RW 24D-01151 5-19-98 pre 4 25 -- -- --

RW 24D-0115 7-15-98 post 1 28 38 1.0 <.2

RW 24D-0115 8-14-98 post 5 36 36 1.3 <.2

RW 24D-0115 10-02-98 post 8 278 80 1.1 <.2

RW 24D-0115 10-27-98 post 9 3,542 2,925 1.7 <.2

RW 24D-0115 11-24-98 post 10 9,833 -- 3.4 <.2

RW 24D-0115 1-26-99 post 11 1,442 -- 1.4 <.2

RW 24D-0115 3-25-99 post 12 -- -- 1.3 <.2

Table 7. Carbon species analyses for ground-water samples collected near the granular-iron permeable reactive barriers, 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.—Continued

[Well number: 1Source of data: U.S. Geological Survey National Water Quality Laboratory. Source of data: Richard L. Smith, U.S. Geological Survey, National 

Research Program, Boulder, CO. Dissolved Inorganic Carbon: The values in this column include all the inorganic carbon species, including carbon dioxide. 

Locations of wells are shown in figure 2. -D, duplicate; μM, micromoles per liter; mM, millimoles per liter; <, actual value is less than value shown; --, no data]

Well number Date sample

taken Sampling round

Dissolved

organic carbon

(μM)

Total organic 

carbon

(μM)

Dissolved 

inorganic carbon 

including carbon 

dioxide

(mM)

Methane

(μM)
Table 7 51

RW 25A-0092 7-02-97 pre 1 96 115 1.0 <0.2

RW 25A-0092 7-22-97 pre 2 66 62 1.0 <.2

RW 25A-0092 9-18-97 pre 3 55 63 1.0 <.2

RW 25A-0092 5-20-98 pre 4 83 53 1.0 <.2

RW 25A-00921 5-20-98 pre 4 42 -- -- --

RW 25B-0099 7-02-97 pre 1 93 89 1.1 <.2

RW 25B-0099 7-22-97 pre 2 88 113 1.2 <.2

RW 25B-0099 9-18-97 pre 3 66 56 1.3 <.2

RW 25B-0099 5-20-98 pre 4 51 62 1.3 <.2

RW 25B-00991 5-20-98 pre 4 50 -- -- --

RW 25B-0099 7-14-98 post 1 49 52 1.2 <.2

RW 25B-0099 7-23-98 post 2 51 46 1.1 <.2

RW 25B-0099 8-13-98 post 5 45 44 1.2 <.2

RW 25B-0099 10-01-98 post 8 79 89 1.2 <.2

RW 25B-0099 10-26-98 post 9 66 -- 1.1 <.2

RW 25B-0099 11-23-98 post 10 61 -- 1.2 <.2

RW 25B-0099 1-26-99 post 11 63 -- 1.3 <.2

RW 25B-0099 3-24-99 post 12 -- -- 1.9 <.2

RW 25C-0105 7-02-97 pre 1 70 98 1.2 <.2

RW 25C-0105 7-22-97 pre 2 73 113 1.1 <.2

RW 25C-0105 9-18-97 pre 3 47 48 1.3 <.2

RW 25C-0105 5-20-98 pre 4 43 46 1.2 <.2

RW 25C-01051 5-20-98 pre 4 33 -- -- --

RW 25C-0105 7-14-98 post 1 40 40 1.1 <.2

RW 25C-0105 7-23-98 post 2 41 42 1.0 <.2

RW 25C-0105 8-13-98 post 5 40 37 1.0 <.2

RW 25C-0105 10-02-98 post 8 47 60 1.1 <.2

RW 25C-0105 10-26-98 post 9 33 -- 1.0 <.2

RW 25C-0105 11-23-98 post 10 33 -- 1.1 <.2

RW 25C-0105 1-26-99 post 11 38 -- 1.4 <.2

RW 25C-0105 3-24-99 post 12 -- -- 1.4 <.2

RW 25D-0110 7-02-97 pre 1 74 70 1.2 <.2

RW 25D-0110 7-22-97 pre 2 63 95 1.2 <.2

RW 25D-0110 9-18-97 pre 3 39 46 1.2 <.2

RW 25D-0110 5-20-98 pre 4 32 35 1.2 <.2

RW 25D-01101 5-20-98 pre 4 25 -- -- --

RW 25E-0120 7-22-97 pre 2 78 90 1.0 <.2

RW 25E-0120 9-18-97 pre 3 33 33 1.0 <.2

RW 25E-0120 5-20-98 pre 4 51 44 1.1 <.2

RW 25E-01201 5-20-98 pre 4 33 -- -- --

Table 7. Carbon species analyses for ground-water samples collected near the granular-iron permeable reactive barriers, 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.—Continued

[Well number: 1Source of data: U.S. Geological Survey National Water Quality Laboratory. Source of data: Richard L. Smith, U.S. Geological Survey, National 

Research Program, Boulder, CO. Dissolved Inorganic Carbon: The values in this column include all the inorganic carbon species, including carbon dioxide. 

Locations of wells are shown in figure 2. -D, duplicate; μM, micromoles per liter; mM, millimoles per liter; <, actual value is less than value shown; --, no data]

Well number Date sample

taken Sampling round

Dissolved

organic carbon

(μM)

Total organic 

carbon

(μM)

Dissolved 

inorganic carbon 

including carbon 

dioxide

(mM)

Methane

(μM)
52 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000

RW 26-0087 5-20-98 pre 4 59 67 1.0 <0.2

RW 26-00871 5-20-98 pre 4 50 -- -- --

RW 26-0092 5-20-98 pre 4 76 59 1.0 <.2

RW 26-00921 5-20-98 pre 4 50 -- -- --

RW 26-0096 5-20-98 pre 4 54 56 1.3 <.2

RW 26-00961 5-20-98 pre 4 50 -- -- --

RW 26-0100 5-20-98 pre 4 47 61 1.4 <.2

RW 26-01001 5-20-98 pre 4 50 -- -- --

RW 26-0106 5-20-98 pre 4 31 39 1.2 <.2

RW 26-0106-D 5-20-98 pre 4 57 39 -- --

RW 26-01061 5-20-98 pre 4 33 -- -- --

RW 26-0106-D1 5-20-98 pre 4 25 -- -- --

RW 27-0098 5-19-98 pre 4 43 52 1.0 <.2

RW 27-00981 5-19-98 pre 4 42 -- -- --

RW 27-0098 7-15-98 post 1 42 46 .9 <.2

RW 27-0102 5-19-98 pre 4 42 42 1.2 <.2

RW 27-01021 5-19-98 pre 4 83 -- -- --

RW 27-0102 7-15-98 post 1 50 42 .9 <.2

RW 27-0108 5-19-98 pre 4 35 38 1.3 <.2

RW 27-0108-D 5-19-98 pre 4 43 36 -- <.2

RW 27-01081 5-19-98 pre 4 25 -- -- --

RW 27-0108-D1 5-19-98 pre 4 50 -- -- --

RW 27-0108 7-15-98 post 1 39 40 1.1 --

RW 27-0108-D 7-15-98 post 1 36 51 -- --

RW 27-0114 5-19-98 pre 4 36 36 1.4 <.2

RW 27-01141 5-19-98 pre 4 42 -- -- --

RW 27-0114 7-15-98 post 1 40 38 1.0 <.2

RW 27-0120 5-19-98 pre 4 33 33 1.3 <.2

RW 27-01201 5-19-98 pre 4 33 -- -- --

RW 27-0120 7-15-98 post 1 49 39 .9 <.2

RW 30-0087 7-23-98 post 2 67 52 .7 <.2

RW 30-0087 7-29-98 post 3 46 52 .7 --

RW 30-0087 8-05-98 post 4 53 45 1.0

RW 30-0087 8-13-98 post 5 50 48 .9 <.2

RW 30-0087 8-20-98 post 6 54 57 .8 --

Table 7. Carbon species analyses for ground-water samples collected near the granular-iron permeable reactive barriers, 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.—Continued

[Well number: 1Source of data: U.S. Geological Survey National Water Quality Laboratory. Source of data: Richard L. Smith, U.S. Geological Survey, National 

Research Program, Boulder, CO. Dissolved Inorganic Carbon: The values in this column include all the inorganic carbon species, including carbon dioxide. 

Locations of wells are shown in figure 2. -D, duplicate; μM, micromoles per liter; mM, millimoles per liter; <, actual value is less than value shown; --, no data]

Well number Date sample

taken Sampling round

Dissolved

organic carbon

(μM)

Total organic 

carbon

(μM)

Dissolved 

inorganic carbon 

including carbon 

dioxide

(mM)

Methane

(μM)
Table 7 53

RW 30-0087 9-02-98 post 7 71 79 0.8 --

RW 30-0087 10-02-98 post 8 53 77 .7 <0.2

RW 30-0087 10-26-98 post 9 66 -- .9 <.2

RW 30-0087 11-23-98 post 10 43 -- .7 <.2

RW 30-0087 1-25-99 post 11 59 -- 1.1 <.2

RW 30-0087 3-24-99 post 12 -- -- 1.2 <.2

RW 30-0096 7-23-98 post 2 9,500 10,667 1.7 <.2

RW 30-0096 7-29-98 post 3 7,083 7,992 1.7 --

RW 30-0096 8-05-98 post 4 6,042 6,758 1.6 --

RW 30-0096-D 8-05-98 post 4 5,875 6,750 1.5 --

RW 30-0096 8-13-98 post 5 5,125 4,500 1.5 <.2

RW 30-0096-D 8-13-98 post 5 5,167 4,333 -- --

RW 30-0096 8-20-98 post 6 5,250 4,875 1.5 --

RW 30-0096 9-02-98 post 7 3,650 4,088 1.2 --

RW 30-0096 10-02-98 post 8 51,250 53,333 1.2 <.2

RW 30-0096 10-26-98 post 9 6,617 -- 1.2 .4

RW 30-0096 11-23-98 post 10 2,104 -- 1.2 5.2

RW 30-0096 1-25-99 post 11 804 -- 1.3 13.1

RW 30-0096 3-24-99 post 12 -- -- 1.3 34.0

RW 30-0100 7-23-98 post 2 11,083 11,167 1.1 <.2

RW 30-0100 7-29-98 post 3 6,750 6,775 1.2 --

RW 30-0100-D 7-29-98 post 3 6,750 6,808 1.3 --

RW 30-0100 8-05-98 post 4 2,279 2,250 1.4 --

RW 30-0100 8-13-98 post 5 1,417 1,217 1.4 <.2

RW 30-0100 8-20-98 post 6 598 779 1.2 --

RW 30-0100-D 8-20-98 post 6 1,050 613 -- --

RW 30-0100 9-02-98 post 7 404 367 1.2 --

RW 30-0100-D 9-02-98 post 7 384 305 -- --

RW 30-0100 10-02-98 post 8 30,333 30,333 1.4 <.2

RW 30-0100-D 10-02-98 post 8 30,500 33,375 1.5 <.2

RW 30-0100 10-26-98 post 9 391 -- 1.2 <.2

RW 30-0100 11-23-98 post 10 140 -- 1.3 .2

RW 30-0100 1-25-99 post 11 98 -- 1.5 .4

RW 30-0100-D 1-25-99 post 11 -- -- -- 1.1

RW 30-0100 3-24-99 post 12 -- -- 1.5 .9

RW 30-0100-D 3-24-99 post 12 -- -- 1.9 --

Table 7. Carbon species analyses for ground-water samples collected near the granular-iron permeable reactive barriers, 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.—Continued

[Well number: 1Source of data: U.S. Geological Survey National Water Quality Laboratory. Source of data: Richard L. Smith, U.S. Geological Survey, National 

Research Program, Boulder, CO. Dissolved Inorganic Carbon: The values in this column include all the inorganic carbon species, including carbon dioxide. 

Locations of wells are shown in figure 2. -D, duplicate; μM, micromoles per liter; mM, millimoles per liter; <, actual value is less than value shown; --, no data]

Well number Date sample

taken Sampling round

Dissolved

organic carbon

(μM)

Total organic 

carbon

(μM)

Dissolved 

inorganic carbon 

including carbon 

dioxide

(mM)

Methane

(μM)
54 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000

RW 30-0106 7-23-98 post 2 155 86 1.1 <0.2

RW 30-0106-D 7-23-98 post 2 145 75 -- --

RW 30-0106 7-29-98 post 3 245 272 1.2 --

RW 30-0106 8-05-98 post 4 172 137 1.3 --

RW 30-0106 8-13-98 post 5 751 684 1.5 <.2

RW 30-0106 8-20-98 post 6 112 107 1.4 --

RW 30-0106 9-02-98 post 7 81 82 1.2 --

RW 30-0106 10-02-98 post 8 8,733 4,217 1.3 <.2

RW 30-0106 10-26-98 post 9 43,750 -- 1.2 <.2

RW 30-0106-D 10-26-98 post 9 45,833 -- -- --

RW 30-0106 11-23-98 post 10 8,217 -- 1.3 <.2

RW 30-0106 1-25-99 post 11 166 -- 1.7 .2

RW 30-0106 3-24-99 post 12 -- -- 1.6 <.2

RW 30-0117 7-23-98 post 2 72 43 1.1 <.2

RW 30-0117 7-29-98 post 3 54 36 1.1 --

RW 30-0117 8-05-98 post 4 47 36 1.1 --

RW 30-0117 8-13-98 post 5 40 30 1.2 <.2

RW 30-0117 8-20-98 post 6 35 35 1.0 --

RW 30-0117 9-02-98 post 7 53 47 .9 --

RW 30-0117 10-02-98 post 8 58,333 63,750 1.2 <.2

RW 30-0117 10-26-98 post 9 135 -- .9 <.2

RW 30-0117 11-23-98 post 10 37 -- .8 <.2

RW 30-0117 1-25-99 post 11 40 -- .9 <.2

RW 30-0117-D 1-25-99 post 11 38 -- -- --

RW 30-0117 3-24-99 post 12 -- -- 1.1 <.2

Table 7. Carbon species analyses for ground-water samples collected near the granular-iron permeable reactive barriers, 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.—Continued

[Well number: 1Source of data: U.S. Geological Survey National Water Quality Laboratory. Source of data: Richard L. Smith, U.S. Geological Survey, National 

Research Program, Boulder, CO. Dissolved Inorganic Carbon: The values in this column include all the inorganic carbon species, including carbon dioxide. 

Locations of wells are shown in figure 2. -D, duplicate; μM, micromoles per liter; mM, millimoles per liter; <, actual value is less than value shown; --, no data]

Well number Date sample

taken Sampling round

Dissolved

organic carbon

(μM)

Total organic 

carbon

(μM)

Dissolved 

inorganic carbon 

including carbon 

dioxide

(mM)

Methane

(μM)
Table 8 55

Table 8. Major- and minor-element analyses for ground-water samples collected near the granular-iron permeable reactive barriers, Massachusetts Military Reservation, Cape 

Cod, Massachusetts, 1997–2000.

[Well number: 1Source of data: U.S. Geological Survey National Water Quality Laboratory. Source of data: Douglas B. Kent, U.S. Geological Survey, National Research Program, Menlo Park, CA. Locations of 

wells are shown in figure 2. -D, duplicate; μM, micromoles per liter, <, actual value is less than value shown; --, no data]

Well number

Date

sample

taken

Sampling

round

Boron, 

dissolved

(μM)

Calcium, 

dissolved 

(μM)

Iron, 

dissolved

(μM)

Magnesium, 

dissolved

(μM)

Manganese, 

dissolved

(μM)

Potassium, 

dissolved 

(μM)

Silicon, 

dissolved 

(μM)

Sodium, 

dissolved 

(μM)

Strontium, 

dissolved 

(μM)

Phosphorus, 

dissolved

(μM)

MW 14B-0097 7-23-97 pre 2 6.13 69.4 <0.20 96.7 <0.20 16.4 133 514 0.304 <3.2MW 14B-0097 9-18-97 pre 3 4.81 45.9 <.20 64.4 <.20 15.2 138 331 .184 <3.2MW 14B-0097 6-23-99 post 13 4.19 133 <.09 201 .12 31.0 205 599 .645 <1.6MW 14A-0124 7-23-97 pre 2 .590 40.0 <.20 56.5 <.20 36.3 174 296 .200 <3.2MW 14A-0124 9-18-97 pre 3 .499 37.3 <.20 51.5 <.20 28.6 173 281 .176 <3.2MW 14A-0124 6-23-99 post 13 5.38 361 <.09 507 .15 90.9 211 792 1.93 <1.6RW 24-0094 9-17-97 pre 3 7.81 35.4 <.20 46.3 <.20 18.1 108 810 .156 <3.2RW 24-0094 5-19-98 pre 4 4.43 30.5 <.09 42.2 .17 49.6 81.6 559 .146 1.9RW 24-00941 5-19-98 pre 4 -- 29.9 <.18 38.7 .18 -- 78.9 -- .137 --RW 24-0094 7-14-98 post 1 5.86 30.3 <.09 41.5 .0335 30.4 142 776 .152 <1.6RW 24-0094 7-29-98 post 3 23.7 28.6 .247 35.5 .0444 21.4 113 658 .140 <1.6RW 24-0094 8-05-98 post 4 55.2 33.4 .192 43.2 .111 21.3 122 711 .162 <1.6RW 24-0094 8-14-98 post 5 100 57.9 8.59 74.0 1.21 25.6 129 898 .276 <1.6RW 24-0094 8-20-98 post 6 121 73.4 30.5 97.7 2.10 34.2 204 1,170 .364 1.7RW 24-0094 9-02-98 post 7 128 165 22.0 236 3.11 48.7 192 1,520 .849 <1.6RW 24-0094 10-02-98 post 8 44.2 252 7.48 330 4.42 58.4 153 1,720 1.16 <1.6RW 24-0094 10-27-98 post 9 78.2 398 9.02 533 5.27 96.2 -- 3,300 2.09 <1.6RW 24-0094 11-24-98 post 10 62.2 434 328 575 18.7 83.9 166 3,530 2.26 2.55RW 24-0094 1-26-99 post 11 92.3 376 404 478 42.8 28.1 258 1,290 1.35 3.25RW 24-0094 3-25-99 post 12 70.5 117 575 133 16.4 85.7 -- 789 .854 4.13RW 24-0094 6-23-99 post 13 53.7 106 456 68.9 11.4 65.4 178 595 .500 5.55RW 24-0094 11-02-99 post 15 51.2 119 355 42.3 9.37 68.5 135 507 .468 5.62RW 24-0094 2-09-00 post 17 43.6 129 324 52.7 8.72 67.8 147 554 .419 7.29RW 24A-0100 7-01-97 pre 1 7.77 62.5 <.20 97.0 .218 38.1 117 927 .303 <3.2RW 24A-0100-D 7-01-97 pre 1 8.05 64.1 <.20 99.8 <.20 30.8 119 989 .313 <3.2RW 24A-0100 7-21-97 pre 2 8.59 95.2 <.20 154 <.20 31.9 121 1,170 .474 <3.2RW 24A-0100 9-17-97 pre 3 8.90 118 <.20 203 <.20 23.8 126 1,100 .547 <3.2RW 24A-0100 5-19-98 pre 4 6.36 31.7 <.09 53.3 <.02 17.9 -- 704 .169 <1.6
56 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000 RW 24A-0100 7-14-98 post 1 4.87 28.7 <0.09 45.9 <0.02 15.5 -- 642 0.150 <1.6 RW 24A-0100 7-14-98 post 1 6.53 39.2 <.09 63.9 <.02 20.6 -- 846 .206 RW 24A-0100 7-29-98 post 3 28.1 50.3 .571 80.5 <.02 21.0 -- 679 .255 <1.6 RW 24A-0100 8-05-98 post 4 82.8 72.2 .172 117 .779 21.1 -- 706 .361 <1.6 RW 24A-01001 8-05-98 post 4 -- 25.0 <.18 38.3 <.07 -- 105 -- .126 RW 24A-0100 8-14-98 post 5 98.6 86.1 6.50 146 2.03 22.1 -- 673 .424 <1.6 RW 24A-0100 8-20-98 post 6 432 290 58.4 452 13.6 39.4 -- 1,250 1.29 <1.6 RW 24A-0100 9-02-98 post 7 1,450 631 365 916 61.2 51.5 -- 3,450 2.95 <1.6 RW 24A-0100 10-02-98 post 8 581 264 391 401 30.9 18.8 167 2,420 1.01 <1.6 RW 24A-0100 10-27-98 post 9 304 662 1,350 863 80.2 30.0 - 2,700 2.47 6.50 RW 24A-0100 11-24-98 post 10 270 510 2,720 595 70.0 48.9 - 5,020 2.85 4.40 RW 24A-0100 1-26-99 post 11 47.0 89.4 1,120 71.8 12.9 110 - 677 1.32 4.55 RW 24A-0100 3-25-99 post 12 94.1 59.6 1,010 63.2 9.41 79.0 - 1,040 .656 7.17 RW 24A-0100 6-22-99 post 13 21.7 70.5 851 58.0 10.0 66.6 - 617 .375 11.3 RW 24A-0100 11-02-99 post 15 24.2 71.5 498 31.2 6.44 60.8 - 512 .237 9.19 RW 24A-0100 2-09-00 post 17 8.56 96.5 451 58.5 5.79 88.9 - 523 .285 11.0 RW 24B-0104 7-01-97 pre 1 5.99 40.2 <.20 81.6 .36 28.5 131 512 .207 <3.2 RW 24B-0104 7-21-97 pre 2 6.90 53.9 <.20 110 <.20 20.0 142 536 .275 <3.2 RW 24B-0104 9-17-97 pre 3 7.54 203 <.20 423 .290 32.4 146 720 .942 <3.2 RW 24B-0104 5-19-98 pre 4 5.73 30.2 <.09 65.3 .0945 13.8 133 495 .181 <1.6 RW 24B-01041 5-19-98 pre 4 -- 29.9 <.18 57.6 .111 -- 120 -- .160 -- RW 24B-0104 7-14-98 post 1 6.37 37.3 <.09 78.3 .0812 15.9 156 569 .215 <1.6 RW 24B-0104 8-14-98 post 5 26.7 56.9 .195 119 .267 17.1 146 541 .321 <1.6 RW 24B-0104 8-20-98 post 6 59.5 91.8 3.31 183 .868 25.0 213 721 .491 <1.6 RW 24B-0104 9-02-98 post 7 526 265 72.4 488 18.5 29.6 154 1,290 1.35 1.93 RW 24B-0104 10-02-98 post 8 828 367 514 731 47.8 23.9 153 2,500 1.57 4.84 RW 24B-0104 10-27-98 post 9 645 733 1,280 1,140 94.6 34.5 188 4,570 3.30 <1.6 RW 24B-0104 11-24-98 post 10 220 749 3,350 1,000 111 70.5 235 2,230 4.33 12.9 RW 24B-0104 1-26-99 post 11 19.6 66.1 528 54.4 5.96 43.8 197 270 .592 5.77 RW 24B-0104 3-25-99 post 12 75.6 124 855 167 12.4 51.7 219 952 .869 7.13

RW 24B-0104 6-22-99 post 13 13.6 114 705 111 13.7 30.3 240 474 .430 7.69

Table 8. Major- and minor-element analyses for ground-water samples collected near the granular-iron permeable reactive barriers, Massachusetts Military Reservation, Cape 

Cod, Massachusetts, 1997–2000.—Continued

[Well number: 1Source of data: U.S. Geological Survey National Water Quality Laboratory. Source of data: Douglas B. Kent, U.S. Geological Survey, National Research Program, Menlo Park, CA. Locations of 

wells are shown in figure 2. -D, duplicate; μM, micromoles per liter, <, actual value is less than value shown; --, no data]

Well number

Date

sample

taken

Sampling

round

Boron, 

dissolved

(μM)

Calcium, 

dissolved 

(μM)

Iron, 

dissolved

(μM)

Magnesium, 

dissolved

(μM)

Manganese, 

dissolved

(μM)

Potassium, 

dissolved 

(μM)

Silicon, 

dissolved 

(μM)

Sodium, 

dissolved 

(μM)

Strontium, 

dissolved 

(μM)

Phosphorus, 

dissolved

(μM)
Table 8 57

RW 24B-0104 11-02-99 post 15 13.9 61.2 447 35.8 7.42 38.1 179 351 0.248 7.51RW 24B-0104 2-09-00 post 17 9.52 71.3 383 60.0 6.44 77.0 210 359 .318 7.81RW 24C-0110 7-01-97 pre 1 3.84 59.3 <.20 112 <.20 22.1 188 282 .272 <3.2RW 24C-0110 7-21-97 pre 2 4.11 60.2 <.20 116 <.20 17.0 200 287 .283 <3.2RW 24C-0110 7-21-97 pre 2 4.13 56.9 <.20 108 <.20 16.8 189 275 .267 <3.2RW 24C-0110 9-17-97 pre 3 4.04 59.4 <.20 112 <.20 15.7 195 282 .260 <3.2RW 24C-0110 5-19-98 pre 4 4.23 64.3 <.09 128 .0907 18.2 225 230 .322 <1.6RW 24C-01101 5-19-98 pre 4 -- 64.9 <.18 115 .0947 -- 181 -- .285 --RW 24C-0110 7-15-98 post 1 4.67 77.6 <.09 152 .115 22.2 267 316 .385 <1.6RW 24C-0110 8-14-98 post 5 9.64 64.8 <.09 124 .0937 20.2 260 258 .311 <1.6RW 24C-0110 10-02-98 post 8 300 156 .18 312 7.41 30.2 226 838 .789 <1.6RW 24C-0110 10-27-98 post 9 324 895 347 1,400 162 62.4 369 1,470 4.19 <1.6RW 24C-0110 11-24-98 post 10 119 594 1,480 978 127 16.8 284 793 2.10 <1.6RW 24C-0110 1-26-99 post 11 33.4 403 1,500 473 69.2 10.1 284 498 1.06 <1.6RW 24C-0110 3-25-99 post 12 14.0 189 928 204 33.4 7.34 291 279 .626 2.70RW 24C-0110 6-22-99 post 13 8.11 90.6 506 109 14.9 21.2 288 249 .625 5.11RW 24C-0110 11-02-99 post 15 6.03 135 430 187 20.4 30.8 241 379 .920 3.40RW 24C-0110 2-09-00 post 17 7.44 116 415 145 18.7 41.5 253 516 .801 2.17RW 24D-0115 7-01-97 pre 1 3.34 62.8 .422 97.9 .824 40.0 190 263 .290 <3.2RW 24D-0115 7-21-97 pre 2 3.93 63.1 <.20 101 <.20 33.3 205 281 .306 <3.2RW 24D-0115 9-17-97 pre 3 3.90 63.0 <.20 101 <.20 26.7 200 249 .285 <3.2RW 24D-0115 9-17-97 pre 3 3.68 62.5 <.20 101 <.20 29.5 199 249 .282 <3.2RW 24D-0115 5-19-98 pre 4 3.80 60.0 <.09 100 .0576 27.9 205 214 .304 <1.6RW 24D-01151 5-19-98 pre 4 -- 59.9 <.18 94.6 <.07 -- 181 -- .285 --RW 24D-0115 7-15-98 post 1 4.85 74.7 <.09 123 .0577 34.0 250 256 .372 <1.6RW 24D-0115 8-14-98 post 5 9.96 75.7 <.09 123 .0548 36.7 235 312 .389 <1.6RW 24D-0115 10-02-98 post 8 15.4 82.1 <.09 140 .183 38.3 228 359 .416 <1.6RW 24D-0115 10-27-98 post 9 58.8 455 6.22 705 16.3 74.0 327 631 2.20 <1.6

Table 8. Major- and minor-element analyses for ground-water samples collected near the granular-iron permeable reactive barriers, Massachusetts Military Reservation, Cape 

Cod, Massachusetts, 1997–2000.—Continued

[Well number: 1Source of data: U.S. Geological Survey National Water Quality Laboratory. Source of data: Douglas B. Kent, U.S. Geological Survey, National Research Program, Menlo Park, CA. Locations of 

wells are shown in figure 2. -D, duplicate; μM, micromoles per liter, <, actual value is less than value shown; --, no data]

Well number

Date

sample

taken

Sampling

round

Boron, 

dissolved

(μM)

Calcium, 

dissolved 

(μM)

Iron, 

dissolved

(μM)

Magnesium, 

dissolved

(μM)

Manganese, 

dissolved

(μM)

Potassium, 

dissolved 

(μM)

Silicon, 

dissolved 

(μM)

Sodium, 

dissolved 

(μM)

Strontium, 

dissolved 

(μM)

Phosphorus, 

dissolved

(μM)
58 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000 RW 24D-0115 11-24-98 post 10 66.8 864 667 1,230 138 64.3 263 586 3.54 <1.6 RW 24D-0115 1-26-99 post 11 10.3 134 367 206 25.2 20.7 277 382 .455 3.02 RW 24D-0115 3-25-99 post 12 8.43 66.9 120 85.5 12.7 67.1 265 278 .481 2.41 RW 24D-0115 6-22-99 post 13 7.94 83.0 33.1 112.5 14.2 71.8 266 291 .676 <1.6 RW 24D-0115 11-02-99 post 15 4.57 250 .702 368.1 17.5 60.8 223 469 1.57 <1.6 RW 24D-0115 2-09-00 post 17 4.94 208 1.56 334.8 2.12 59.3 234 813 1.00 <1.6 RW 25A-0092 7-02-97 pre 1 8.37 32.9 <.20 40.7 <.20 27.6 109 660 .152 <3.2 RW 25A-0092 7-22-97 pre 2 8.72 31.6 <.20 39.9 <.20 23.7 109 636 .147 3.76 RW 25A-0092 9-18-97 pre 3 6.77 23.1 <.20 28.8 <.20 16.7 110 518 .104 3.47 RW 25A-0092 5-20-98 pre 4 5.60 24.8 <.09 33.1 .0184 20.6 136 579 .129 3.81 RW 25A-00921 5-20-98 pre 4 -- 22.0 <.18 26.7 <.07 -- 107 -- .102 -- RW 25A-0092 6-23-99 post 13 7.82 119 <.09 169 .0739 42.4 205 450 .653 <1.6 RW 25A-0092 11-03-99 post 15 6.59 114 2.86 147 .291 45.7 159 423 .549 2.48 RW 25A-0092 2-08-00 post 17 7.08 113 <.09 161 .0830 34.4 164 373 .567 <1.6 RW 25B-0099 7-02-97 pre 1 8.18 87.0 <.20 135 <.20 29.4 139 537 .375 <3.2 RW 25B-0099 7-22-97 pre 2 7.81 66.5 <.20 99.3 <.20 16.4 139 434 .278 <3.2 RW 25B-0099 9-18-97 pre 3 6.04 62.3 <.20 97.4 <.20 10.2 139 338 .247 <3.2 RW 25B-0099 5-20-98 pre 4 5.60 78.4 <.09 131 .0869 20.6 156 303 .369 2.02 RW 25B-00991 5-20-98 pre 4 -- 77.3 <.18 115 .0837 -- 130 -- .320 -- RW 25B-0099 7-14-98 post 1 5.91 70.3 <.09 114 .0768 18.7 154 341 .322 <1.6 RW 25B-0099 7-23-98 post 2 7.09 69.0 <.09 113 .0794 19.1 149 354 .321 <1.6 RW 25B-0099 8-13-98 post 5 16.5 95.2 .315 160 .123 28.6 180 482 .455 1.64 RW 25B-0099 10-01-98 post 8 12.0 120 .238 198 .145 28.6 205 427 .576 1.90 RW 25B-0099 10-26-98 post 9 11.1 224 <.09 328 .252 44.3 266 606 1.02 3.46 RW 25B-0099 11-23-98 post 10 7.82 158 <.09 271 .239 33.0 225 426 .833 1.78 RW 25B-0099 1-26-99 post 11 9.40 159 .161 261 .204 29.4 183 402 .803 1.62 RW 25B-0099 3-24-99 post 12 9.38 125 <.09 191 .146 24.7 180 371 .593 1.68 RW 25B-0099 6-21-99 post 13 8.00 141 <.09 218 .162 28.7 219 416 .662 2.09 RW 25B-0099 11-03-99 post 15 7.07 125 <.09 189 .146 26.8 183 459 .584 <1.6 RW 25B-0099 2-08-00 post 17 5.71 144 <.09 226 .153 26.7 167 570 .691 <1.6 Table 8. Major- and minor-element analyses for ground-water samples collected near the granular-iron permeable reactive barriers, Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.—Continued

[Well number: 1Source of data: U.S. Geological Survey National Water Quality Laboratory. Source of data: Douglas B. Kent, U.S. Geological Survey, National Research Program, Menlo Park, CA. Locations of 

wells are shown in figure 2. -D, duplicate; μM, micromoles per liter, <, actual value is less than value shown; --, no data]

Well number

Date

sample

taken

Sampling

round

Boron, 

dissolved

(μM)

Calcium, 

dissolved 

(μM)

Iron, 

dissolved

(μM)

Magnesium, 

dissolved

(μM)

Manganese, 

dissolved

(μM)

Potassium, 

dissolved 

(μM)

Silicon, 

dissolved 

(μM)

Sodium, 

dissolved 

(μM)

Strontium, 

dissolved 

(μM)

Phosphorus, 

dissolved

(μM)
Table 8 59

RW 25C-0105 7-02-97 pre 1 4.02 93.5 <0.20 169 0.382 34.5 184 256 0.427 <3.2RW 25C-0105 7-22-97 pre 2 4.72 100 <.20 182 .329 20.3 192 280 .470 <3.2RW 25C-0105 9-18-97 pre 3 4.77 66.5 <.20 113 <.20 16.2 169 239 .268 <3.2RW 25C-0105 5-20-98 pre 4 4.24 73.2 <.09 129 .181 19.4 199 215 .332 <1.6RW 25C-01051 5-20-98 pre 4 -- 72.4 <.18 123 .180 -- 158 -- .308 --RW 25C-0105 7-14-98 post 1 4.44 87.1 <.09 153 .209 21.7 206 235 .387 <1.6RW 25C-0105 7-23-98 post 2 5.16 83.6 .199 147 .212 21.7 190 235 .377 <1.6RW 25C-0105 8-13-98 post 5 8.90 93.5 .290 169 .253 25.4 182 272 .432 <1.6RW 25C-0105 10-01-98 post 8 9.26 137 .432 255 .348 38.9 213 427 .657 <1.6RW 25C-0105 10-26-98 post 9 7.36 147 <.09 270 .363 42.2 349 463 .730 <1.6RW 25C-0105 11-23-98 post 10 4.66 123 <.09 218 .302 32.0 251 329 .613 <1.6RW 25C-0105 1-26-99 post 11 5.37 223 .170 348 .549 47.6 275 459 1.11 <1.6RW 25C-0105 3-24-99 post 12 5.65 233 <.09 361 .578 46.7 239 490 1.15 <1.6RW 25C-0105 6-21-99 post 13 6.96 145 <.09 255 .390 38.9 219 508 .805 <1.6RW 25C-0105 11-03-99 post 15 6.92 119 .187 193 .309 34.7 188 448 .610 <1.6RW 25C-0105 2-08-00 post 17 6.52 105 <.09 170 .228 31.3 184 432 .534 <1.6RW 25D-0110 7-02-97 pre 1 3.75 60.2 <.20 110 <.20 28.5 198 211 .287 <3.2RW 25D-0110 7-22-97 pre 2 4.13 73.9 <.20 136 <.20 22.4 199 229 .356 <3.2RW 25D-0110 9-18-97 pre 3 3.72 58.8 <.20 109 <.20 13.8 203 204 .267 <3.2RW 25D-0110 5-20-98 pre 4 4.10 58.2 <.09 78.1 .0852 15.4 213 138 .210 <3.2RW 25D-01101 5-20-98 pre 4 -- 57.4 <.18 103 .0856 -- 181 -- .274 --RW 25D-0110 6-23-99 post 13 4.45 159 <.09 350 .347 45.5 250 429 1.07 <1.6RW 25D-0110 11-03-99 post 15 5.60 148 .204 304 .316 44.1 203 623 .912 <1.6RW 25D-0110 2-08-00 post 17 7.43 134 .148 270 .254 44.1 229 767 .822 <1.6RW 25E-0120 7-22-97 pre 2 1.54 65.3 <.20 98.5 <.20 39.7 190 267 .315 <3.2RW 25E-0120 9-18-97 pre 3 1.41 60.1 <.20 91.9 <.20 32.4 184 239 .273 <3.2RW 25E-0120 5-20-98 pre 4 3.82 68.6 <.09 112 .0336 39.2 188 278 .366 <1.6RW 25E-01201 5-20-98 pre 4 -- 72.4 <.18 107 <.07 -- 181 -- .331 --RW 25E-0120 6-23-99 post 13 2.97 59.6 <.09 96.5 .0269 37.6 187 264 .311 <1.6RW 25E-0120 11-03-99 post 15 1.94 54.6 .190 89.2 .0865 37.6 160 264 .286 <1.6RW 25E-0120 2-08-00 post 17 2.59 56.4 .190 91.4 .0442 38.6 185 348 .298 <1.6

Table 8. Major- and minor-element analyses for ground-water samples collected near the granular-iron permeable reactive barriers, Massachusetts Military Reservation, Cape 

Cod, Massachusetts, 1997–2000.—Continued

[Well number: 1Source of data: U.S. Geological Survey National Water Quality Laboratory. Source of data: Douglas B. Kent, U.S. Geological Survey, National Research Program, Menlo Park, CA. Locations of 

wells are shown in figure 2. -D, duplicate; μM, micromoles per liter, <, actual value is less than value shown; --, no data]

Well number

Date

sample

taken

Sampling

round

Boron, 

dissolved

(μM)

Calcium, 

dissolved 

(μM)

Iron, 

dissolved

(μM)

Magnesium, 

dissolved

(μM)

Manganese, 

dissolved

(μM)

Potassium, 

dissolved 

(μM)

Silicon, 

dissolved 

(μM)

Sodium, 

dissolved 

(μM)

Strontium, 

dissolved 

(μM)

Phosphorus, 

dissolved

(μM)
60 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000 RW 26-0087 5-20-98 pre 4 6.22 108 <0.09 258 0.0610 28.6 179 941 0.561 <1.6 RW 26-00871 5-20-98 pre 4 -- 110 <.18 235 <.07 -- 159 -- .502 -- RW 26-0087 6-23-99 post 13 5.19 148 <.09 379 .0846 48.1 243 1,100 .907 <1.6 RW 26-0087 8-10-99 post 14 4.69 211 <.09 492 .118 57.3 236 1,560 1.17 <1.6 RW 26-0092 5-20-98 pre 4 5.48 47.6 <.09 68.6 .0326 24.0 140 493 .236 <1.6 RW 26-00921 5-20-98 pre 4 -- 47.4 <.18 61.7 <.07 -- 122 -- .205 -- RW 26-0092 6-23-99 post 13 14.7 159 5.63 235 .345 46.1 224 536 .822 <1.6 RW 26-0092 8-10-99 post 14 9.49 135 14.1 177 .538 34.3 168 396 .612 <1.6 RW 26-0096 5-20-98 pre 4 4.96 35.3 <.09 53.5 .0521 14.9 119 476 .177 <1.6 RW 26-00961 5-20-98 pre 4 -- 37.4 <.18 53.5 <.07 -- 113 -- .171 -- RW 26-0096 8-10-99 post 14 2.76 102 2.57 155 .189 23.0 157 477 .490 <1.6 RW 26-0100 5-20-98 pre 4 5.29 77.0 <.09 131 .137 18.7 154 242 .354 <1.6 RW 26-01001 5-20-98 pre 4 -- 79.8 <.18 119 .137 -- 136 -- .320 -- RW 26-0100 8-10-99 post 14 5.76 109 <.09 172 .199 25.0 175 394 .500 <1.6 RW 26-0106 5-20-98 pre 4 4.27 68.4 <.09 113 .174 29.7 189 244 .354 <1.6 RW 26-01061 5-20-98 pre 4 -- 67.4 <.18 103 .173 -- 164 -- .308 -- RW 26-0106-D1 5-20-98 pre 4 -- 69.9 <.18 107 .162 -- 164 -- .320 -- RW 27-0098 5-19-98 pre 4 5.30 13.9 .319 21.1 .0384 11.6 124 489 .072 <1.6 RW 27-00981 5-19-98 pre 4 -- 13.7 <.18 19.3 <.07 -- 98.6 -- .064 -- RW 27-0098 7-15-98 post 1 5.48 38.0 .490 59.0 .0945 21.3 157 870 .196 <1.6 RW 27-0098 6-22-99 post 13 16.2 95.6 592 78.4 13.5 29.7 280 492 .586 7.29 RW 27-0098 2-09-00 post 17 6.53 59.0 474 22.9 7.02 124 239 526 .675 7.57 RW 27-0102 5-19-98 pre 4 6.05 34.4 <.09 73.6 .0561 16.0 153 619 .207 <1.6 RW 27-01021 5-19-98 pre 4 -- 34.9 <.18 65.8 <.07 -- 118 -- .183 -- RW 27-0102 7-15-98 post 1 5.61 25.9 <.09 54.6 .0450 12.9 155 490 .151 <1.6 RW 27-0102 6-22-99 post 13 12.2 73.6 574 104 9.31 33.1 179 366 .466 6.00 RW 27-0102 2-09-00 post 17 11.1 54.2 576 37.2 8.87 69.0 233 428 .371 9.17 RW 27-0108 5-19-98 pre 4 4.28 49.5 <.09 103 .133 15.6 173 340 .248 <1.6 RW 27-01081 5-19-98 pre 4 -- 49.9 <.18 98.7 .153 -- 156 -- .228 --

RW 27-0108-D1 5-19-98 pre 4 -- 52.4 <.18 103 .131 -- 159 -- .240 <1.6RW 27-0108 7-15-98 post 1 4.82 57.5 <.09 121 .152 18.0 196 357 .286 <1.6RW 27-0108-D 7-15-98 post 1 4.83 56.5 <.09 120 .154 18.9 192 358 .287 --

Table 8. Major- and minor-element analyses for ground-water samples collected near the granular-iron permeable reactive barriers, Massachusetts Military Reservation, Cape 

Cod, Massachusetts, 1997–2000.—Continued

[Well number: 1Source of data: U.S. Geological Survey National Water Quality Laboratory. Source of data: Douglas B. Kent, U.S. Geological Survey, National Research Program, Menlo Park, CA. Locations of 

wells are shown in figure 2. -D, duplicate; μM, micromoles per liter, <, actual value is less than value shown; --, no data]

Well number

Date

sample

taken

Sampling

round

Boron, 

dissolved

(μM)

Calcium, 

dissolved 

(μM)

Iron, 

dissolved

(μM)

Magnesium, 

dissolved

(μM)

Manganese, 

dissolved

(μM)

Potassium, 

dissolved 

(μM)

Silicon, 

dissolved 

(μM)

Sodium, 

dissolved 

(μM)

Strontium, 

dissolved 

(μM)

Phosphorus, 

dissolved

(μM)
Table 8 61

RW 27-0108 6-22-99 post 13 44.4 143 359 242 20.3 5.30 140 550 0.377 5.27RW 27-0108 2-09-00 post 17 11.4 171 551 142 30.8 10.6 191 525 .563 3.13RW 27-0114 5-19-98 pre 4 3.68 66.9 <.09 116 .0623 24.3 173 216 .322 <1.6RW 27-01141 5-19-98 pre 4 -- 67.4 .250 111 <.07 -- 159 -- .308 --RW 27-0114 7-15-98 post 1 5.79 115 <.09 205 .0557 32.1 294 311 .509 <1.6RW 27-0114 6-22-99 post 13 8.90 84.8 330 88.8 16.4 32.4 242 269 .469 2.32RW 27-0114 2-09-00 post 17 4.34 257 1.37 350 28.8 66.1 228 657 1.58 <1.6RW 27-0120 5-19-98 pre 4 1.67 62.8 <.09 89.9 .0551 30.0 143 250 .310 <1.6RW 27-01201 5-19-98 pre 4 -- 59.9 <.18 94.6 <.07 -- 181 -- .285 --RW 27-0120 7-15-98 post 1 4.69 149 <.09 234 .0719 46.5 233 742 .680 <1.6RW 27-0120 6-22-99 post 13 6.45 55.3 348 62.2 8.66 58.5 257 424 .599 6.32RW 27-0120 2-09-00 post 17 5.94 142 .18 192 15.8 57.8 201 508 .781 <1.6RW 28-0107 6-22-99 post 13 72.4 352 1,020 480 43.0 9.69 200 739 .976 3.39RW 29-0107 6-22-99 post 13 77.5 283 727 414 53.8 7.09 195 689 .615 3.80RW 29-0111 6-23-99 post 13 18.1 189 504 325 42.0 7.14 172 353 .477 3.02RW 30-0087 7-23-98 post 2 8.37 325 .25 478 1.99 113 148 2,670 1.77 <1.6RW 30-0087 7-29-98 post 3 5.13 204 <.09 383 1.44 60.2 134 2,260 1.51 <1.6RW 30-0087 8-05-98 post 4 18.1 365 1.10 456 1.88 72.6 151 2,730 2.06 <1.6RW 30-0087 8-13-98 post 5 8.96 290 <.09 344 1.36 56.0 147 2,180 1.48 <1.6RW 30-0087 8-20-98 post 6 5.49 246 <.09 308 1.12 48.6 141 1,780 1.25 <1.6RW 30-0087 9-02-98 post 7 5.84 283 <.09 322 1.28 55.1 185 1,880 1.42 <1.6RW 30-0087 10-01-98 post 8 4.29 620 .195 763 2.43 78.9 152 3,970 3.13 <1.6RW 30-0087 10-26-98 post 9 3.06 630 .490 643 3.63 118 181 5,520 3.51 <1.6RW 30-0087 11-23-98 post 10 3.71 514 1.25 639 3.99 150 218 5,120 2.96 <1.6RW 30-0087 1-25-99 post 11 6.10 216 .175 342 1.29 58.6 220 2,120 1.12 <1.6RW 30-0087 3-24-99 post 12 6.24 97.2 .166 171 .969 36.9 185 672 .467 <1.6RW 30-0087 6-21-99 post 13 6.38 304 <.09 571 1.52 71.1 218 2,550 1.47 <1.6RW 30-0087 11-02-99 post 15 5.20 157 .791 339 .668 45.7 200 1,580 .910 <1.6RW 30-0087 2-08-00 post 17 4.62 162 .441 384 .487 48.6 161 2,020 1.07 <1.6

Table 8. Major- and minor-element analyses for ground-water samples collected near the granular-iron permeable reactive barriers, Massachusetts Military Reservation, Cape 

Cod, Massachusetts, 1997–2000.—Continued

[Well number: 1Source of data: U.S. Geological Survey National Water Quality Laboratory. Source of data: Douglas B. Kent, U.S. Geological Survey, National Research Program, Menlo Park, CA. Locations of 

wells are shown in figure 2. -D, duplicate; μM, micromoles per liter, <, actual value is less than value shown; --, no data]

Well number

Date

sample

taken

Sampling

round

Boron, 

dissolved

(μM)

Calcium, 

dissolved 

(μM)

Iron, 

dissolved

(μM)

Magnesium, 

dissolved

(μM)

Manganese, 

dissolved

(μM)

Potassium, 

dissolved 

(μM)

Silicon, 

dissolved 

(μM)

Sodium, 

dissolved 

(μM)

Strontium, 

dissolved 

(μM)

Phosphorus, 

dissolved

(μM)
62 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000 RW 30-0096 7-23-98 post 2 1,430 177 289 104 8.26 109 124 5,310 0.652 <1.6 RW 30-0096 7-29-98 post 3 1,060 183 244 98.8 6.84 101 126 4,810 .611 4.78 RW 30-0096 8-05-98 post 4 685 186 215 102 6.78 87.2 143 3,590 .582 4.89 RW 30-0096 8-13-98 post 5 385 140 189 73.9 5.85 62.0 133 3,490 .419 5.19 RW 30-0096 8-20-98 post 6 506 246 336 156 11.6 97.1 191 3,560 .712 6.86 RW 30-0096 9-02-98 post 7 228 174 228 116 10.4 68.1 162 1,780 .519 5.65 RW 30-0096 10-01-98 post 8 292 1,120 5,890 655 95.8 435 405 2,310 5.31 <1.6 RW 30-0096 10-26-98 post 9 82.8 152 1,060 44.5 15.3 1,440 241 881 .503 3.82 RW 30-0096 11-23-98 post 10 44.3 115 293 21.6 6.81 110 176 640 .323 3.54 RW 30-0096 1-25-99 post 11 25.9 123 187 54.6 7.34 44.6 176 529 .428 <1.6 RW 30-0096 3-24-99 post 12 17.9 113 183 108 4.22 30.1 153 455 .390 <1.6 RW 30-0096 6-21-99 post 13 16.8 179 138 231 2.71 37.5 164 635 .575 <1.6 RW 30-0096 11-02-99 post 15 13.2 128 137 145 2.05 31.9 148 544 .423 <1.6 RW 30-0096 2-08-00 post 17 17.9 181 186 239 2.88 41.1 157 666 .761 <1.6 RW 30-0100 7-23-98 post 2 1,460 380 3.27 554 13.7 145 174 3,570 2.11 <1.6 RW 30-0100 7-29-98 post 3 1,250 283 15.6 403 12.7 104 213 3,790 1.52 <1.6 RW 30-0100 8-05-98 post 4 220 102 10.1 131 4.04 81.0 166 1,020 .434 <1.6 RW 30-0100 8-13-98 post 5 149 116 32.4 156 4.95 56.6 188 786 .489 <1.6 RW 30-0100 8-20-98 post 6 80.3 125 38.8 162 5.17 44.0 194 551 .492 <1.6 RW 30-0100 9-02-98 post 7 15.4 90.0 22.8 111 4.71 26.9 196 392 .459 <1.6 RW 30-0100 10-01-98 post 8 34.8 955 191 1,160 30.7 78.1 299 762 5.05 2.77 RW 30-0100 10-26-98 post 9 34.9 119 34.6 167 4.33 31.3 193 461 .473 <1.6 RW 30-0100 11-23-98 post 10 12.5 94.3 25.2 122 4.21 25.4 204 418 .468 <1.6 RW 30-0100 1-25-99 post 11 8.76 117 4.77 193 1.70 22.1 167 322 .501 <1.6 RW 30-0100 3-24-99 post 12 9.89 141 2.29 244 <.02 25.4 177 373 .610 <1.6 RW 30-0100 6-21-99 post 13 9.81 142 .163 235 <.02 28.6 210 432 .631 <1.6 RW 30-0100 11-02-99 post 15 5.88 134 .174 215 <.02 27.0 178 474 .599 <1.6 RW 30-0100 2-08-00 post 17 6.87 127 .312 198 <.02 27.1 190 492 .559 <1.6 Table 8. Major- and minor-element analyses for ground-water samples collected near the granular-iron permeable reactive barriers, Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.—Continued

[Well number: 1Source of data: U.S. Geological Survey National Water Quality Laboratory. Source of data: Douglas B. Kent, U.S. Geological Survey, National Research Program, Menlo Park, CA. Locations of 

wells are shown in figure 2. -D, duplicate; μM, micromoles per liter, <, actual value is less than value shown; --, no data]

Well number

Date

sample

taken

Sampling

round

Boron, 

dissolved

(μM)

Calcium, 

dissolved 

(μM)

Iron, 

dissolved

(μM)

Magnesium, 

dissolved

(μM)

Manganese, 

dissolved

(μM)

Potassium, 

dissolved 

(μM)

Silicon, 

dissolved 

(μM)

Sodium, 

dissolved 

(μM)

Strontium, 

dissolved 

(μM)

Phosphorus, 

dissolved

(μM)
Table 8 63

RW 30-0106 7-23-98 post 2 30.1 120 0.209 165 2.68 159 202 486 0.506 <1.6RW 30-0106 7-29-98 post 3 176 190 .769 285 8.35 132 235 752 .828 <1.6RW 30-0106 8-05-98 post 4 139 135 3.67 218 8.58 49.4 180 727 .630 <1.6RW 30-0106 8-13-98 post 5 360 189 99.4 335 20.0 37.3 188 1,200 .877 2.01RW 30-0106 8-20-98 post 6 142 104 103 180 11.2 28.4 190 746 .492 2.33RW 30-0106 9-02-98 post 7 42.1 70.9 27.5 115 6.54 32.5 182 445 .333 <1.6RW 30-0106 10-01-98 post 8 105 565 39.1 836 42.2 50.9 226 855 2.76 1.69RW 30-0106 10-26-98 post 9 139 2,010 1,370 1,870 190 184 524 1,750 13.3 <1.6RW 30-0106 11-23-98 post 10 17.5 274 196 365 27.4 49.6 259 329 1.42 2.07RW 30-0106 1-25-99 post 11 7.14 83.4 120 113 11.2 31.4 203 239 .405 1.76RW 30-0106 3-24-99 post 12 6.71 97.6 33.6 122 10.5 37.8 223 274 .470 <1.6RW 30-0106 6-21-99 post 13 6.99 255 10.1 333 21.5 75.7 252 532 1.31 <1.6RW 30-0106 11-02-99 post 15 6.95 122 .295 198 3.16 37.5 191 504 .583 <1.6RW 30-0106 2-08-00 post 17 6.54 98.1 .556 170 .745 33.1 187 507 .445 <1.6RW 30-0117 7-23-98 post 2 20.0 79.7 .439 113 .525 49.2 198 423 .383 <1.6RW 30-0117 7-29-98 post 3 6.63 84.2 .232 115 .546 45.1 197 327 .385 <1.6RW 30-0117 8-05-98 post 4 8.23 94.3 .252 131 .470 39.8 221 306 .418 <1.6RW 30-0117 8-13-98 post 5 6.04 87.4 <.09 131 .289 28.9 218 269 .393 <1.6RW 30-0117 8-20-98 post 6 4.71 87.1 <.09 133 .268 25.5 215 263 .389 <1.6RW 30-0117 9-02-98 post 7 5.74 100 <.09 162 .266 26.7 257 322 .462 <1.6RW 30-0117 10-01-98 post 8 72.2 793 4,710 605 203 87.6 408 485 5.58 <1.6RW 30-0117 10-26-98 post 9 6.94 27.2 19.5 35.0 6.42 67.3 294 346 .212 <1.6RW 30-0117 11-23-98 post 10 7.30 54.6 .413 72.7 14.2 77.9 300 326 .387 <1.6RW 30-0117 1-25-99 post 11 6.44 41.0 .218 65.9 5.02 27.0 183 225 .245 <1.6RW 30-0117 3-24-99 post 12 9.96 60.7 2.67 111 1.79 33.1 186 319 .316 <1.6RW 30-0117 6-21-99 post 13 17.5 145 <.09 263 .942 64.3 301 592 .726 <1.6RW 30-0117 11-02-99 post 15 8.10 163 .395 282 .469 53.5 194 465 .942 <1.6RW 30-0117 2-08-00 post 17 5.50 159 .148 278 .324 63.9 235 1,020 1.04 <1.6

Table 8. Major- and minor-element analyses for ground-water samples collected near the granular-iron permeable reactive barriers, Massachusetts Military Reservation, Cape 

Cod, Massachusetts, 1997–2000.—Continued

[Well number: 1Source of data: U.S. Geological Survey National Water Quality Laboratory. Source of data: Douglas B. Kent, U.S. Geological Survey, National Research Program, Menlo Park, CA. Locations of 

wells are shown in figure 2. -D, duplicate; μM, micromoles per liter, <, actual value is less than value shown; --, no data]

Well number

Date

sample

taken

Sampling

round

Boron, 

dissolved

(μM)

Calcium, 

dissolved 

(μM)

Iron, 

dissolved

(μM)

Magnesium, 

dissolved

(μM)

Manganese, 

dissolved

(μM)

Potassium, 

dissolved 

(μM)

Silicon, 

dissolved 

(μM)

Sodium, 

dissolved 

(μM)

Strontium, 

dissolved 

(μM)

Phosphorus, 

dissolved

(μM)
64 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000

Table 9. Trace-element analyses for ground-water samples collected near the granular-iron permeable reactive barriers, 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.

[Well number: 1Source of data: U.S. Geological Survey National Water Quality Laboratory. Source of data: Douglas B. Kent, U.S. Geological Survey, National 

Research Program, Menlo Park, CA. The elements aluminum, chromium, lead, lithium, molybdenum, and vanadium were reported at or near their respective 

detection limits in table 3 and are not included in this table. Locations of wells are shown in figure 2. -D, duplicate; μM, micromoles per liter, <, actual value is 

less than value shown; --, no data]

Well number

Date

sample

taken

Sampling

round

Arsenic, 

dissolved 

(μM)

Barium, 

dissolved 

(μM)

Cadmium, 

dissolved 

(μM)

Cobalt, 

dissolved 

(μM)

Copper, 

dissolved 

(μM)

Nickel, 

dissolved 

(μM)

Zinc, 

dissolved 

(μM)

MW 14B-0097 7-23-97 pre 2 <0.67 -- <0.04 -- <0.10 <0.51 --

MW 14B-0097 9-18-97 pre 3 <.67 -- <.04 -- <.10 <.51 --

MW 14B-0097 6-23-99 post 13 <.13 0.0894 <.009 <0.020 <.050 <.051 <0.038

MW 14A-0124 7-23-97 pre 2 <.67 -- <.04 -- <.10 <.51 --

MW 14A-0124 9-18-97 pre 3 <.67 -- <.04 -- <.10 <.51 --

MW 14A-0124 6-23-99 post 13 <.13 .450 <.009 <.020 <.050 <.051 .0763

RW 24-0094 9-17-97 pre 3 <.67 -- <.04 -- <.10 <.51 --

RW 24-0094 5-19-98 pre 4 <.13 .0370 <.009 <.020 <.050 <.051 .228

RW 24-00941 5-19-98 pre 4 -- -- -- <.20 -- -- --

RW 24-0094 7-14-98 post 1 <.13 .0405 <.009 <.020 <.050 <.051 .264

RW 24-0094 7-29-98 post 3 <.13 .0382 <.009 <.020 <.050 <.051 .285

RW 24-0094 8-05-98 post 4 <.13 .0418 <.009 <.020 <.050 <.051 .046

RW 24-0094 8-14-98 post 5 <.13 .0591 <.009 <.020 <.050 <.051 .084

RW 24-0094 8-20-98 post 6 <.13 .0794 <.009 .0623 <.050 <.051 .103

RW 24-0094 9-02-98 post 7 <.13 .196 <.009 .0619 <.050 <.051 .110

RW 24-0094 10-02-98 post 8 <.13 .351 <.009 .0867 <.050 <.051 .130

RW 24-0094 10-27-98 post 9 <.13 .529 <.009 .101 <.050 <.051 <.038

RW 24-0094 11-24-98 post 10 <.13 .504 <.009 .324 <.050 <.051 <.038

RW 24-0094 1-26-99 post 11 .345 .114 <.009 .287 <.050 <.051 <.038

RW 24-0094 3-25-99 post 12 <.13 .140 <.009 .273 <.050 <.051 <.038

RW 24-0094 6-23-99 post 13 .396 .097 <.009 .174 <.050 <.051 <.038

RW 24-0094 11-02-99 post 15 .155 .097 <.009 .132 <.050 <.051 <.038

RW 24-0094 2-09-00 post 17 .173 .096 <.009 .129 <.050 <.051 <.038

RW 24A-0100 7-01-97 pre 1 <.67 -- <.04 -- <.10 <.51 --

RW 24A-0100 7-01-97 pre 1 <.67 -- <.04 -- <.10 <.51 --

RW 24A-0100 7-21-97 pre 2 <.67 -- <.04 -- <.10 <.51 --

RW 24A-0100 9-17-97 pre 3 <.67 -- <.04 -- <.10 <.51 --

RW 24A-0100 5-19-98 pre 4 <.13 .0308 <.009 <.020 <.050 <.051 <.038

RW 24A-01001 5-19-98 pre 4 -- -- -- <.20 -- -- --

RW 24A-0100 7-14-98 post 1 <.13 .0278 <.009 <.020 <.050 <.051 <.038

RW 24A-0100 7-14-98 post 1 <.13 .0376 <.009 <.020 <.050 <.051 <.038

RW 24A-0100 7-29-98 post 3 <.13 .0458 <.009 <.020 <.050 <.051 <.038

RW 24A-0100 8-05-98 post 4 <.13 .0541 <.009 <.020 <.050 <.051 <.038

RW 24A-0100 8-14-98 post 5 <.13 .0570 <.009 .0884 <.050 <.051 <.038

RW 24A-0100 8-20-98 post 6 <.13 .140 <.009 .435 <.050 <.051 <.038

RW 24A-0100 9-02-98 post 7 <.13 .277 <.009 1.26 <.050 <.051 <.038

RW 24A-0100 10-02-98 post 8 .148 .0738 <.009 .442 <.050 <.051 <.038

RW 24A-0100 10-27-98 post 9 <.13 .150 <.009 .879 <.050 <.051 <.038
Table 9 65

RW 24A-0100 11-24-98 post 10 <0.13 0.241 <0.009 1.21 <0.050 <0.051 <0.038

RW 24A-0100 1-26-99 post 11 <.13 .127 <.009 .508 <.050 <.051 <.038

RW 24A-0100 3-25-99 post 12 <.13 .101 <.009 .372 <.050 <.051 <.038

RW 24A-0100 6-22-99 post 13 .179 .0623 <.009 .218 <.050 <.051 <.038

RW 24A-0100 11-02-99 post 15 .161 .0377 <.009 .0801 <.050 <.051 <.038

RW 24A-0100 2-09-00 post 17 .197 .0837 <.009 .231 <.050 <.051 <.038

RW 24B-0104 7-01-97 pre 1 <.67 -- <.04 -- <.10 <.51 --

RW 24B-0104 7-21-97 pre 2 <.67 -- <.04 -- <.10 <.51 --

RW 24B-0104 9-17-97 pre 3 <.67 -- <.04 -- <.10 <.51 --

RW 24B-0104 5-19-98 pre 4 <.13 .0434 <.009 <.020 <.050 <.051 .165

RW 24B-01041 5-19-98 pre 4 -- -- -- <.20 -- -- --

RW 24B-0104 7-14-98 post 1 <.13 .0474 <.009 <.020 <.050 <.051 .194

RW 24B-0104 8-14-98 post 5 <.13 .0636 <.009 <.020 <.050 <.051 .0569

RW 24B-0104 8-20-98 post 6 <.13 .0922 <.009 <.020 <.050 <.051 .129

RW 24B-0104 9-02-98 post 7 <.13 .214 <.009 .596 <.050 <.051 .119

RW 24B-0104 10-02-98 post 8 <.13 .167 <.009 1.01 <.050 <.051 .0883

RW 24B-0104 10-27-98 post 9 .329 .352 <.009 1.58 <.050 <.051 <.038

RW 24B-0104 11-24-98 post 10 <1.3 .614 <.09 3.70 <.50 <.51 <.38

RW 24B-0104 1-26-99 post 11 .481 .0770 <.009 .318 <.050 <.051 <.038

RW 24B-0104 3-25-99 post 12 .533 .123 <.009 .414 <.050 <.051 <.038

RW 24B-0104 6-22-99 post 13 .542 .0631 <.009 .208 <.050 <.051 <.038

RW 24B-0104 11-02-99 post 15 .447 .0526 <.009 .100 <.050 <.051 <.038

RW 24B-0104 2-09-00 post 17 .430 .122 <.009 .170 <.050 <.051 <.038

RW 24C-0110 7-01-97 pre 1 <.67 -- <.04 -- <.10 <.51 --

RW 24C-0110 7-21-97 pre 2 <.67 -- <.04 -- <.10 <.51 --

RW 24C-0110 7-21-97 pre 2 <.67 -- <.04 -- <.10 <.51 --

RW 24C-0110 9-17-97 pre 3 <.67 -- <.04 -- <.10 <.51 --

RW 24C-0110 5-19-98 pre 4 <.13 .183 <.009 <.020 <.050 <.051 .433

RW 24C-01101 5-19-98 pre 4 -- -- -- <.20 -- -- --

RW 24C-0110 7-15-98 post 1 <.13 .134 <.009 <.020 <.050 <.051 .221

RW 24C-0110 8-14-98 post 5 <.13 .110 <.009 <.020 <.050 <.051 .0828

RW 24C-0110 10-02-98 post 8 <.13 .317 <.009 .454 <.050 .090 .0849

RW 24C-0110 10-27-98 post 9 <.13 1.49 <.009 6.86 <.050 <.051 .225

RW 24C-0110 11-24-98 post 10 <.13 .266 <.009 2.61 <.050 <.051 .114

RW 24C-0110 1-26-99 post 11 <.13 .103 <.009 .981 <.050 <.051 .170

RW 24C-0110 3-25-99 post 12 <.13 .0475 <.009 .539 <.050 <.051 .104

RW 24C-0110 6-22-99 post 13 <.13 .0663 <.009 .340 <.050 <.051 .106

RW 24C-0110 11-02-99 post 15 <.13 .253 <.009 .639 <.050 <.051 .120

RW 24C-0110 2-09-00 post 17 <.13 .355 <.009 .585 <.050 <.051 .149

Table 9. Trace-element analyses for ground-water samples collected near the granular-iron permeable reactive barriers, 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.—Continued

[Well number: 1Source of data: U.S. Geological Survey National Water Quality Laboratory. Source of data: Douglas B. Kent, U.S. Geological Survey, National 

Research Program, Menlo Park, CA. The elements aluminum, chromium, lead, lithium, molybdenum, and vanadium were reported at or near their respective 

detection limits in table 3 and are not included in this table. Locations of wells are shown in figure 2. -D, duplicate; μM, micromoles per liter, <, actual value is 

less than value shown; --, no data]

Well number

Date

sample

taken

Sampling

round

Arsenic, 

dissolved 

(μM)

Barium, 

dissolved 

(μM)

Cadmium, 

dissolved 

(μM)

Cobalt, 

dissolved 

(μM)

Copper, 

dissolved 

(μM)

Nickel, 

dissolved 

(μM)

Zinc, 

dissolved 

(μM)
66 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000

RW 24D-0115 7-01-97 pre 1 <0.67 -- <0.04 -- <0.10 <0.51 --

RW 24D-0115 7-21-97 pre 2 <.67 -- <.04 -- <.10 <.51 --

RW 24D-0115 9-17-97 pre 3 <.67 -- <.04 -- <.10 <.51 --

RW 24D-0115 9-17-97 pre 3 <.67 -- <.04 -- <.10 .511 --

RW 24D-0115 5-19-98 pre 4 <.13 0.115 <.009 <0.020 <.050 <.051 0.202

RW 24D-01151 5-19-98 pre 4 -- -- -- <.20 -- -- --

RW 24D-0115 7-15-98 post 1 <.13 .139 <.009 <.020 <.050 <.051 .254

RW 24D-0115 8-14-98 post 5 <.13 .150 <.009 <.020 .0559 <.051 .0786

RW 24D-0115 10-02-98 post 8 <.13 .161 <.009 <.020 <.050 <.051 .0698

RW 24D-0115 10-27-98 post 9 <.13 .762 <.009 .289 <.050 <.051 .150

RW 24D-0115 11-24-98 post 10 <.13 .889 <.009 1.58 <.050 <.051 <.038

RW 24D-0115 1-26-99 post 11 <.13 .108 <.009 .398 <.050 <.051 .0873

RW 24D-0115 3-25-99 post 12 <.13 .321 <.009 .389 <.050 <.051 .128

RW 24D-0115 6-22-99 post 13 <.13 .443 <.009 .380 <.050 <.051 .150

RW 24D-0115 11-02-99 post 15 <.13 1.00 <.009 .875 <.050 .146 .296

RW 24D-0115 2-09-00 post 17 <.13 .809 <.009 .269 <.050 <.051 .176

RW 25A-0092 7-02-97 pre 1 <.67 -- <.04 -- <.10 <.51 --

RW 25A-0092 7-22-97 pre 2 <.67 -- <.04 -- <.10 <.51 --

RW 25A-0092 9-18-97 pre 3 <.67 -- <.04 -- <.10 .511 --

RW 25A-0092 5-20-98 pre 4 <.13 .0341 <.009 <.020 <.050 <.051 .232

RW 25A-00921 5-20-98 pre 4 -- -- -- <.20 -- -- --

RW 25A-0092 6-23-99 post 13 <.13 .128 <.009 <.020 <.050 <.051 .0685

RW 25A-0092 11-03-99 post 15 <.13 .123 <.009 <.020 .163 <.051 1.11

RW 25A-0092 2-08-00 post 17 <.13 .110 <.009 <.020 <.050 <.051 <.038

RW 25B-0099 7-02-97 pre 1 <.67 -- <.04 -- <.10 <.51 --

RW 25B-0099 7-22-97 pre 2 <.67 -- <.04 -- <.10 <.51 --

RW 25B-0099 9-18-97 pre 3 <.67 -- <.04 -- <.10 <.51 --

RW 25B-0099 5-20-98 pre 4 <.13 .0489 <.009 <.020 <.050 <.051 .237

RW 25B-00991 5-20-98 pre 4 -- -- -- <.20 -- -- --

RW 25B-0099 7-14-98 post 1 <.13 .0452 <.009 <.020 <.050 <.051 .183

RW 25B-0099 7-23-98 post 2 <.13 .0484 <.009 <.020 <.050 <.051 .225

RW 25B-0099 8-13-98 post 5 <.13 .0628 <.009 <.020 <.050 <.051 .0903

RW 25B-0099 10-01-98 post 8 <.13 .0778 <.009 <.020 <.050 <.051 .0883

RW 25B-0099 10-26-98 post 9 <.13 .13 <.009 <.020 <.050 <.051 .151

RW 25B-0099 11-23-98 post 10 <.13 .12 <.009 <.020 <.050 <.051 .0512

RW 25B-0099 1-26-99 post 11 <.13 .11 <.009 <.020 <.050 <.051 .0705

RW 25B-0099 3-24-99 post 12 <.13 .0777 <.009 <.020 <.050 <.051 <.038

RW 25B-0099 6-21-99 post 13 <.13 .0848 <.009 <.020 <.050 <.051 <.038

RW 25B-0099 11-03-99 post 15 <.13 .0824 <.009 <.020 <.050 <.051 <.038

RW 25B-0099 2-08-00 post 17 <.13 .102 <.009 <.020 <.050 <.051 <.038

Table 9. Trace-element analyses for ground-water samples collected near the granular-iron permeable reactive barriers, 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.—Continued

[Well number: 1Source of data: U.S. Geological Survey National Water Quality Laboratory. Source of data: Douglas B. Kent, U.S. Geological Survey, National 

Research Program, Menlo Park, CA. The elements aluminum, chromium, lead, lithium, molybdenum, and vanadium were reported at or near their respective 

detection limits in table 3 and are not included in this table. Locations of wells are shown in figure 2. -D, duplicate; μM, micromoles per liter, <, actual value is 

less than value shown; --, no data]

Well number

Date

sample

taken

Sampling

round

Arsenic, 

dissolved 

(μM)

Barium, 

dissolved 

(μM)

Cadmium, 

dissolved 

(μM)

Cobalt, 

dissolved 

(μM)

Copper, 

dissolved 

(μM)

Nickel, 

dissolved 

(μM)

Zinc, 

dissolved 

(μM)
Table 9 67

RW 25C-0105 7-02-97 pre 1 <0.67 -- <0.04 -- <0.10 <0.51 --

RW 25C-0105 7-22-97 pre 2 <.67 -- <.04 -- <.10 <.51 --

RW 25C-0105 9-18-97 pre 3 <.67 -- <.04 -- <.10 <.51 --

RW 25C-0105 5-20-98 pre 4 <.13 0.0742 <.009 <0.020 <.050 <.051 0.198

RW 25C-01051 5-20-98 pre 4 -- -- -- <.20 -- -- --

RW 25C-0105 7-14-98 post 1 <.13 .0867 <.009 <.020 <.050 <.051 .219

RW 25C-0105 7-23-98 post 2 <.13 .0839 <.009 <.020 <.050 <.051 .265

RW 25C-0105 8-13-98 post 5 <.13 .0888 <.009 <.020 <.050 <.051 .174

RW 25C-0105 10-01-98 post 8 <.13 .130 <.009 <.020 <.050 <.051 .250

RW 25C-0105 10-26-98 post 9 <.13 .169 <.009 <.020 <.050 <.051 .0688

RW 25C-0105 11-23-98 post 10 <.13 .138 <.009 <.020 <.050 <.051 .0717

RW 25C-0105 1-26-99 post 11 <.13 .248 <.009 <.020 <.050 <.051 .0676

RW 25C-0105 3-24-99 post 12 <.13 .306 <.009 <.020 <.050 <.051 .0641

RW 25C-0105 6-21-99 post 13 <.13 .246 <.009 <.020 <.050 <.051 <.038

RW 25C-0105 11-03-99 post 15 <.13 .190 <.009 <.020 <.050 <.051 <.038

RW 25C-0105 2-08-00 post 17 <.13 .152 <.009 <.020 <.050 <.051 <.038

RW 25D-0110 7-02-97 pre 1 <.67 -- <.04 -- <.10 <.51 --

RW 25D-0110 7-22-97 pre 2 <.67 -- <.04 -- <.10 <.51 --

RW 25D-0110 9-18-97 pre 3 <.67 -- <.04 -- <.10 <.51 --

RW 25D-0110 5-20-98 pre 4 <.13 .108 <.009 <.020 <.050 <.051 .239

RW 25D-01101 5-20-98 pre 4 -- -- -- <.20 -- -- --

RW 25D-0110 6-23-99 post 13 <.13 .368 <.009 <.020 <.050 <.051 .0571

RW 25D-0110 11-03-99 post 15 <.13 .383 <.009 <.020 <.050 <.051 .0540

RW 25D-0110 2-08-00 post 17 <.13 .340 <.009 <.020 <.050 <.051 <.038

RW 25E-0120 7-22-97 pre 2 <.67 -- <.04 -- <.10 <.51 --

RW 25E-0120 9-18-97 pre 3 <.67 -- <.04 -- <.10 <.51 --

RW 25E-0120 5-20-98 pre 4 <.13 .114 <.009 <.020 <.050 <.051 .278

RW 25E-01201 5-20-98 pre 4 -- -- -- <.20 -- -- --

RW 25E-0120 6-23-99 post 13 <.13 .0727 <.009 <.020 <.050 <.051 <.038

RW 25E-0120 11-03-99 post 15 <.13 .0657 <.009 <.020 <.050 <.051 <.038

RW 25E-0120 2-08-00 post 17 <.13 .0747 <.009 <.020 <.050 <.051 <.038

RW 26-0087 5-20-98 pre 4 <.13 .188 <.009 <.020 <.050 <.051 .0574

RW 26-00871 5-20-98 pre 4 -- -- -- <.20 -- -- --

RW 26-0087 6-23-99 post 13 <.13 .235 <.009 <.020 <.050 <.051 .168

RW 26-0087 8-10-99 post 14 <.13 .381 <.009 <.020 <.050 <.051 .151

RW 26-0092 5-20-98 pre 4 <.13 .0585 <.009 <.020 <.050 <.051 .0565

RW 26-00921 5-20-98 pre 4 -- -- -- <.20 -- -- --

RW 26-0092 6-23-99 post 13 <.13 .0817 <.009 <.020 <.050 <.051 .0505

RW 26-0092 8-10-99 post 14 <.13 .0671 <.009 <.020 <.050 2.09 .0863

RW 26-0096 5-20-98 pre 4 <.13 .0278 <.009 <.020 <.050 <.051 .126

RW 26-00961 5-20-98 pre 4 -- -- -- <.20 -- -- --

RW 26-0096 8-10-99 post 14 <.13 .0603 <.009 <.020 <.050 .535 .0672

Table 9. Trace-element analyses for ground-water samples collected near the granular-iron permeable reactive barriers, 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.—Continued

[Well number: 1Source of data: U.S. Geological Survey National Water Quality Laboratory. Source of data: Douglas B. Kent, U.S. Geological Survey, National 

Research Program, Menlo Park, CA. The elements aluminum, chromium, lead, lithium, molybdenum, and vanadium were reported at or near their respective 

detection limits in table 3 and are not included in this table. Locations of wells are shown in figure 2. -D, duplicate; μM, micromoles per liter, <, actual value is 

less than value shown; --, no data]

Well number

Date

sample

taken

Sampling

round

Arsenic, 

dissolved 

(μM)

Barium, 

dissolved 

(μM)

Cadmium, 

dissolved 

(μM)

Cobalt, 

dissolved 

(μM)

Copper, 

dissolved 

(μM)

Nickel, 

dissolved 

(μM)

Zinc, 

dissolved 

(μM)
68 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000

RW 26-0100 5-20-98 pre 4 <0.13 0.0468 <0.009 <0.020 <0.050 <0.051 0.211

RW 26-01001 5-20-98 pre 4 -- -- -- <.20 -- -- --

RW 26-0100 8-10-99 post 14 <.13 .0725 <.009 <.020 <.050 <.051 .0734

RW 26-0106 5-20-98 pre 4 <.13 .1009 <.009 <.020 <.050 <.051 .215

RW 26-01061 5-20-98 pre 4 -- -- -- <.20 -- -- --

RW 26-0106-D1 5-20-98 pre 4 -- -- -- <.20 -- -- --

RW 27-0098 5-19-98 pre 4 <.13 .0296 <.009 <.020 <.050 <.051 .405

RW 27-00981 5-19-98 pre 4 -- -- -- <.20 -- -- --

RW 27-0098 7-15-98 post 1 <.13 .0382 <.009 <.020 <.050 .125 .281

RW 27-0098 6-22-99 post 13 .192 .0359 <.009 .209 <.050 <.051 .0867

RW 27-0098 2-09-00 post 17 .148 .110 <.009 .171 <.050 <.051 .0799

RW 27-0102 5-19-98 pre 4 <.13 .0494 <.009 <.020 <.050 <.051 .173

RW 27-01021 5-19-98 pre 4 -- -- -- <.20 -- -- --

RW 27-0102 7-15-98 post 1 <.13 .0349 <.009 <.020 <.050 <.051 .186

RW 27-0102 6-22-99 post 13 .171 .0542 <.009 .24 <.050 <.051 .0941

RW 27-0102 2-09-00 post 17 .237 .103 <.009 .16 <.050 <.051 .0948

RW 27-0108 5-19-98 pre 4 <.13 .0708 <.009 <.020 <.050 <.051 .168

RW 27-01081 5-19-98 pre 4 -- -- -- <.20 -- -- --

RW 27-0108-D1 5-19-98 pre 4 -- -- -- <.20 -- -- --

RW 27-0108 7-15-98 post 1 <.13 .0772 <.009 <.020 <.050 <.051 .162

RW 27-0108-D 7-15-98 post 1 <.13 .0769 <.009 <.020 <.050 <.051 .203

RW 27-0108 6-22-99 post 13 <.13 .0219 <.009 .172 <.050 <.051 .0592

RW 27-0108 2-09-00 post 17 <.13 .0384 <.009 .278 <.050 <.051 .0707

RW 27-0114 5-19-98 pre 4 <.13 .110 <.009 <.020 <.050 <.051 .179

RW 27-01141 5-19-98 pre 4 -- -- -- <.20 -- -- --

RW 27-0114 7-15-98 post 1 <.13 .137 <.009 <.020 <.050 <.051 .257

RW 27-0114 6-22-99 post 13 <.13 .121 <.009 .20 <.050 <.051 .0846

RW 27-0114 2-09-00 post 17 <.13 .969 <.009 .69 <.050 .170 .173

RW 27-0120 5-19-98 pre 4 <.13 .0671 <.009 <.020 <.050 <.051 .170

RW 27-01201 5-19-98 pre 4 -- -- -- <.20 -- -- --

RW 27-0120 7-15-98 post 1 <.13 .118 <.009 <.020 <.050 <.051 .232

RW 27-0120 6-22-99 post 13 <.13 .080 <.009 .270 <.050 <.051 .0632

RW 27-0120 2-09-00 post 17 <.13 .397 <.009 .323 <.050 <.051 .208

RW 28-0107 6-22-99 post 13 <.13 .0572 <.009 .529 <.050 <.051 .121

RW 29-0107 6-22-99 post 13 <.13 .0372 <.009 .401 <.050 <.051 .0915

RW 29-0111 6-23-99 post 13 <.13 .0563 <.009 .247 <.050 <.051 .0517

RW 30-0087 7-23-98 post 2 <.13 1.27 <.009 <.020 <.050 <.051 .281

RW 30-0087 7-29-98 post 3 <.13 1.14 <.009 <.020 <.050 <.051 .191

RW 30-0087 8-05-98 post 4 <.13 1.53 <.009 <.020 <.050 <.051 .328

RW 30-0087 8-13-98 post 5 <.13 1.19 <.009 <.020 <.050 <.051 .111

RW 30-0087 8-20-98 post 6 <.13 .926 <.009 <.020 <.050 <.051 .100

Table 9. Trace-element analyses for ground-water samples collected near the granular-iron permeable reactive barriers, 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.—Continued

[Well number: 1Source of data: U.S. Geological Survey National Water Quality Laboratory. Source of data: Douglas B. Kent, U.S. Geological Survey, National 

Research Program, Menlo Park, CA. The elements aluminum, chromium, lead, lithium, molybdenum, and vanadium were reported at or near their respective 

detection limits in table 3 and are not included in this table. Locations of wells are shown in figure 2. -D, duplicate; μM, micromoles per liter, <, actual value is 

less than value shown; --, no data]

Well number

Date

sample

taken

Sampling

round

Arsenic, 

dissolved 

(μM)

Barium, 

dissolved 

(μM)

Cadmium, 

dissolved 

(μM)

Cobalt, 

dissolved 

(μM)

Copper, 

dissolved 

(μM)

Nickel, 

dissolved 

(μM)

Zinc, 

dissolved 

(μM)
Table 9 69

RW 30-0087 9-02-98 post 7 0.138 1.03 <0.009 <0.020 <0.050 <0.051 0.126

RW 30-0087 10-01-98 post 8 .147 2.69 <.009 <.020 <.050 <.051 .102

RW 30-0087 10-26-98 post 9 <.13 3.38 <.009 <.020 <.050 <.051 .149

RW 30-0087 11-23-98 post 10 <.13 3.82 <.009 <.020 <.050 <.051 .152

RW 30-0087 1-25-99 post 11 <.13 1.58 <.009 <.020 <.050 <.051 .106

RW 30-0087 3-24-99 post 12 <.13 .626 <.009 <.020 <.050 <.051 .0665

RW 30-0087 6-21-99 post 13 <.13 .829 <.009 <.020 <.050 <.051 .166

RW 30-0087 11-02-99 post 15 <.13 .949 <.009 <.020 <.050 <.051 .172

RW 30-0087 2-08-00 post 17 <.13 .870 <.009 <.020 <.050 <.051 .158

RW 30-0096 7-23-98 post 2 <.13 .193 <.009 .0804 <.050 <.051 .167

RW 30-0096 7-29-98 post 3 <.13 .153 <.009 <.020 .0518 <.051 .453

RW 30-0096 8-05-98 post 4 <.13 .155 <.009 <.020 .0851 <.051 .536

RW 30-0096 8-13-98 post 5 <.13 .0932 <.009 <.020 <.050 <.051 <.038

RW 30-0096 8-20-98 post 6 <.13 .126 <.009 <.020 <.050 <.051 <.038

RW 30-0096 9-02-98 post 7 <.13 .0856 <.009 <.020 <.050 <.051 .0607

RW 30-0096 10-01-98 post 8 <.13 4.21 <.009 2.29 <.050 <.051 1.81

RW 30-0096 10-26-98 post 9 <.13 .443 <.009 .106 <.050 <.051 <.038

RW 30-0096 11-23-98 post 10 <.13 .224 <.009 .0820 <.050 <.051 <.038

RW 30-0096 1-25-99 post 11 <.13 .239 <.009 .135 <.050 .0886 .0531

RW 30-0096 3-24-99 post 12 <.13 .282 <.009 .113 .0505 .194 .0482

RW 30-0096 6-21-99 post 13 <.13 .482 <.009 .100 .0735 .254 .0503

RW 30-0096 11-02-99 post 15 <.13 .0703 <.009 <.020 <.050 .0916 .0543

RW 30-0096 2-08-00 post 17 <.13 .111 <.009 .0696 <.050 .227 .0727

RW 30-0100 7-23-98 post 2 <.13 .728 <.009 .701 <.050 <.051 .406

RW 30-0100 7-29-98 post 3 <.13 .533 <.009 .690 <.050 <.051 .512

RW 30-0100 8-05-98 post 4 <.13 .123 <.009 .200 .0500 <.051 .311

RW 30-0100 8-13-98 post 5 <.13 .100 <.009 .212 <.050 <.051 .0913

RW 30-0100 8-20-98 post 6 <.13 .0871 <.009 .190 <.050 <.051 .110

RW 30-0100 9-02-98 post 7 <.13 .135 <.009 .216 <.050 <.051 .121

RW 30-0100 10-01-98 post 8 .146 1.25 <.009 1.40 .0598 .166 .563

RW 30-0100 10-26-98 post 9 <.13 .0794 <.009 .160 <.050 <.051 .0799

RW 30-0100 11-23-98 post 10 <.13 .115 <.009 .170 <.050 <.051 .0621

RW 30-0100 1-25-99 post 11 <.13 .099 <.009 .0765 <.050 <.051 .0768

RW 30-0100 3-24-99 post 12 <.13 .0888 <.009 <.020 <.050 <.051 <.038

RW 30-0100 6-21-99 post 13 <.13 .0873 <.009 <.020 <.050 <.051 .0486

RW 30-0100 11-02-99 post 15 <.13 .0850 <.009 <.020 <.050 <.051 .0358

RW 30-0100 2-08-00 post 17 <.13 .0783 <.009 <.020 <.050 <.051 .0679

RW 30-0106 7-23-98 post 2 <.13 .217 <.009 .0804 <.050 <.051 .229

RW 30-0106 7-29-98 post 3 <.13 .267 <.009 .405 <.050 <.051 .368

RW 30-0106 8-05-98 post 4 <.13 .168 <.009 .471 <.050 <.051 .106

RW 30-0106 8-13-98 post 5 <.13 .173 <.009 .766 <.050 <.051 .0782

RW 30-0106 8-20-98 post 6 <.13 .103 <.009 .425 <.050 <.051 .0699

Table 9. Trace-element analyses for ground-water samples collected near the granular-iron permeable reactive barriers, 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.—Continued

[Well number: 1Source of data: U.S. Geological Survey National Water Quality Laboratory. Source of data: Douglas B. Kent, U.S. Geological Survey, National 

Research Program, Menlo Park, CA. The elements aluminum, chromium, lead, lithium, molybdenum, and vanadium were reported at or near their respective 

detection limits in table 3 and are not included in this table. Locations of wells are shown in figure 2. -D, duplicate; μM, micromoles per liter, <, actual value is 

less than value shown; --, no data]

Well number

Date

sample

taken

Sampling

round

Arsenic, 

dissolved 

(μM)

Barium, 

dissolved 

(μM)

Cadmium, 

dissolved 

(μM)

Cobalt, 

dissolved 

(μM)

Copper, 

dissolved 

(μM)

Nickel, 

dissolved 

(μM)

Zinc, 

dissolved 

(μM)
70 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000

RW 30-0106 9-02-98 post 7 <0.13 0.097 <0.009 0.279 <0.050 <0.051 0.0883

RW 30-0106 10-01-98 post 8 <.13 .818 <.009 2.07 <.050 <.051 .213

RW 30-0106 10-26-98 post 9 <.13 6.29 <.009 13.2 .0622 .251 2.47

RW 30-0106 11-23-98 post 10 <.13 1.04 <.009 1.65 <.050 <.051 .464

RW 30-0106 1-25-99 post 11 <.13 .249 <.009 .418 <.050 <.051 .108

RW 30-0106 3-24-99 post 12 <.13 .350 <.009 .526 <.050 <.051 .188

RW 30-0106 6-21-99 post 13 <.13 .994 <.009 1.10 <.050 <.051 .243

RW 30-0106 11-02-99 post 15 <.13 .454 <.009 .253 <.050 <.051 .160

RW 30-0106 2-08-00 post 17 <.13 .376 <.009 .098 <.050 <.051 .134

RW 30-0117 7-23-98 post 2 <.13 .101 <.009 <.020 <.050 <.051 .266

RW 30-0117 7-29-98 post 3 <.13 .0936 <.009 <.020 <.050 <.051 .305

RW 30-0117 8-05-98 post 4 <.13 .098 <.009 <.020 <.050 <.051 .140

RW 30-0117 8-13-98 post 5 <.13 .0839 <.009 <.020 <.050 <.051 .0691

RW 30-0117 8-20-98 post 6 <.13 .0804 <.009 <.020 <.050 <.051 .100

RW 30-0117 9-02-98 post 7 <.13 .098 <.009 <.020 <.050 <.051 .101

RW 30-0117 10-01-98 post 8 <.13 3.15 <.009 6.56 <.050 <.051 2.19

RW 30-0117 10-26-98 post 9 <.13 .438 <.009 .191 <.050 <.051 .164

RW 30-0117 11-23-98 post 10 <.13 .678 <.009 .398 <.050 .0900 .288

RW 30-0117 1-25-99 post 11 <.13 .264 <.009 .153 <.050 <.051 .128

RW 30-0117 3-24-99 post 12 <.13 .315 <.009 .0709 <.050 <.051 .131

RW 30-0117 6-21-99 post 13 <.13 .431 <.009 <.020 <.050 <.051 .122

RW 30-0117 11-02-99 post 15 <.13 .243 <.009 <.020 <.050 <.051 .0656

RW 30-0117 2-08-00 post 17 <.13 .294 <.009 <.020 <.050 <.051 <.038

Table 9. Trace-element analyses for ground-water samples collected near the granular-iron permeable reactive barriers, 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.—Continued

[Well number: 1Source of data: U.S. Geological Survey National Water Quality Laboratory. Source of data: Douglas B. Kent, U.S. Geological Survey, National 

Research Program, Menlo Park, CA. The elements aluminum, chromium, lead, lithium, molybdenum, and vanadium were reported at or near their respective 

detection limits in table 3 and are not included in this table. Locations of wells are shown in figure 2. -D, duplicate; μM, micromoles per liter, <, actual value is 

less than value shown; --, no data]

Well number

Date

sample

taken

Sampling

round

Arsenic, 

dissolved 

(μM)

Barium, 

dissolved 

(μM)

Cadmium, 

dissolved 

(μM)

Cobalt, 

dissolved 

(μM)

Copper, 

dissolved 

(μM)

Nickel, 

dissolved 

(μM)

Zinc, 

dissolved 

(μM)
Table 10 71

Table 10. Tetrachloroethene analyses for ground-water samples collected near the granular-iron permeable reactive barriers, 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.

[Source of data: David W. Hubble, University of Waterloo, Ontario, Canada. Locations of wells are shown in figure 2. μM, micromoles per liter; <, actual value is 

less than value shown]

Well number Date sample

taken

Tetrachloroethene 

(μM)

MW 14B-0097 7-02-97 0.92

MW 14B-0097 7-23-97 .62

MW 14B-0097 9-18-97 .09

MW 14B-0097 6-23-99 .34

MW 14A-0124 7-02-97 .01

MW 14A-0124 7-23-97 .01

MW 14A-0124 9-18-97 .01

MW 14A-0124 6-23-99 .13

RW 24-0094 9-17-97 .04

RW 24-0094 5-19-98 .07

RW 24-0094 7-14-98 .14

RW 24-0094 7-29-98 .22

RW 24-0094 8-05-98 .25

RW 24-0094 8-14-98 .09

RW 24-0094 8-20-98 .08

RW 24-0094 9-02-98 .04

RW 24-0094 10-02-98 .03

RW 24-0094 10-27-98 .02

RW 24-0094 11-24-98 .02

RW 24-0094 1-26-99 .22

RW 24-0094 3-25-99 .30

RW 24-0094 6-23-99 .03

RW 24-0094 11-02-99 .03

RW 24-0094 1-11-00 .07

RW 24-0094 2-09-00 .03

RW 24A-0100 7-01-97 .22

RW 24A-0100 7-21-97 .10

RW 24A-0100 9-17-97 .07

RW 24A-0100 5-19-98 .30

RW 24A-0100 7-14-98 .69

RW 24A-0100 7-29-98 .61

RW 24A-0100 8-05-98 .56

RW 24A-0100 8-14-98 .75

RW 24A-0100 8-20-98 .78

RW 24A-0100 9-02-98 .52

RW 24A-0100 10-02-98 .79

RW 24A-0100 10-27-98 .74

RW 24A-0100 11-24-98 .05

RW 24A-0100 1-26-99 .94

RW 24A-0100 3-25-99 .11

RW 24A-0100 4-06-99 0.14

RW 24A-0100 6-22-99 .20

RW 24A-0100 11-02-99 .20

RW 24A-0100 1-11-00 .39

RW 24A-0100 2-09-00 .36

RW 24B-0104 7-01-97 .49

RW 24B-0104 7-21-97 .39

RW 24B-0104 9-17-97 .26

RW 24B-0104 5-19-98 .38

RW 24B-0104 7-14-98 .49

RW 24B-0104 8-14-98 .30

RW 24B-0104 8-20-98 .33

RW 24B-0104 9-02-98 .49

RW 24B-0104 10-02-98 .55

RW 24B-0104 10-27-98 .43

RW 24B-0104 11-24-98 .32

RW 24B-0104 1-26-99 .60

RW 24B-0104 3-25-99 .51

RW 24B-0104 6-22-99 .68

RW 24B-0104 11-02-99 .42

RW 24B-0104 1-11-00 .51

RW 24B-0104 2-09-00 .50

RW 24C-0110 7-01-97 .46

RW 24C-0110 7-21-97 .43

RW 24C-0110 9-17-97 .40

RW 24C-0110 5-19-98 .33

RW 24C-0110 7-15-98 .28

RW 24C-0110 8-14-98 .16

RW 24C-0110 10-02-98 .21

RW 24C-0110 10-27-98 .21

RW 24C-0110 11-24-98 .30

RW 24C-0110 1-26-99 .23

RW 24C-0110 3-25-99 .24

RW 24C-0110 6-22-99 .19

RW 24C-0110 11-02-99 .39

RW 24C-0110 1-11-00 .37

RW 24C-0110 2-09-00 .41

Well number Date sample

taken

Tetrachloroethene 

(μM)
72 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000

Table 10. Tetrachloroethene analyses for ground-water samples collected near the granular-iron permeable reactive barriers, 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.—Continued

[Source of data: David W. Hubble, University of Waterloo, Ontario, Canada. Locations of wells are shown in figure 2. μM, micromoles per liter; <, actual value is 

less than value shown]

Well No. Date sample

taken

Tetrachloroethene 

(μM)

RW 24D-0115 7-01-97 0.10

RW 24D-0115 7-21-97 .11

RW 24D-0115 9-17-97 .13

RW 24D-0115 5-19-98 .10

RW 24D-0115 7-15-98 .08

RW 24D-0115 8-14-98 .06

RW 24D-0115 10-02-98 .07

RW 24D-0115 10-27-98 .06

RW 24D-0115 11-24-98 .21

RW 24D-0115 1-26-99 .07

RW 24D-0115 3-25-99 .03

RW 24D-0115 6-22-99 .06

RW 24D-0115 11-02-99 .16

RW 24D-0115 1-11-00 .21

RW 24D-0115 2-09-00 .32

RW 25A-0092 7-02-97 .02

RW 25A-0092 7-22-97 .03

RW 25A-0092 9-18-97 .03

RW 25A-0092 5-20-98 .07

RW 25A-0092 6-23-99 .06

RW 25A-0092 11-03-99 .06

RW 25A-0092 1-11-00 .08

RW 25A-0092 2-08-00 .10

RW 25B-0099 7-02-97 .78

RW 25B-0099 7-22-97 1.04

RW 25B-0099 9-18-97 1.26

RW 25B-0099 5-20-98 1.40

RW 25B-0099 7-14-98 1.22

RW 25B-0099 7-23-98 1.31

RW 25B-0099 8-13-98 1.27

RW 25B-0099 10-01-98 1.25

RW 25B-0099 10-26-98 1.15

RW 25B-0099 11-23-98 .83

RW 25B-0099 1-26-99 .81

RW 25B-0099 3-24-99 .71

RW 25B-0099 4-06-99 .60

RW 25B-0099 6-21-99 .46

RW 25B-0099 8-10-99 .72

RW 25B-0099 11-03-99 .35

RW 25B-0099 1-11-00 .27

RW 25B-0099 2-08-00 .29

RW 25C-0105 7-02-97 0.30

RW 25C-0105 7-22-97 .32

RW 25C-0105 9-18-97 .57

RW 25C-0105 5-20-98 .73

RW 25C-0105 7-14-98 .76

RW 25C-0105 7-23-98 .84

RW 25C-0105 8-13-98 .80

RW 25C-0105 10-02-98 .44

RW 25C-0105 10-26-98 .27

RW 25C-0105 11-23-98 .24

RW 25C-0105 1-26-99 .35

RW 25C-0105 3-24-99 .68

RW 25C-0105 4-06-99 .64

RW 25C-0105 6-21-99 .70

RW 25C-0105 8-10-99 .82

RW 25C-0105 11-03-99 .25

RW 25C-0105 1-11-00 .12

RW 25C-0105 2-08-00 .06

RW 25D-0110 7-02-97 .23

RW 25D-0110 7-22-97 .24

RW 25D-0110 9-18-97 .21

RW 25D-0110 5-20-98 .29

RW 25D-0110 4-06-99 .13

RW 25D-0110 6-23-99 .24

RW 25D-0110 8-10-99 .68

RW 25D-0110 11-03-99 .50

RW 25D-0110 1-11-00 .41

RW 25D-0110 2-08-00 .31

RW 25E-0120 7-22-97 .02

RW 25E-0120 9-18-97 .02

RW 25E-0120 5-20-98 .02

RW 25E-0120 6-23-99 .01

RW 25E-0120 8-10-99 .01

RW 25E-0120 11-03-99 <.007

RW 25E-0120 1-11-00 .01

RW 25E-0120 2-08-00 <.007

RW 26-0087 5-20-98 .03

RW 26-0087 6-23-99 .01

RW 26-0087 8-10-99 .01

Well No. Date sample

taken

Tetrachloroethene 

(μM)
Table 10 73

Table 10. Tetrachloroethene analyses for ground-water samples collected near the granular-iron permeable reactive barriers, 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 1997–2000.—Continued

[Source of data: David W. Hubble, University of Waterloo, Ontario, Canada. Locations of wells are shown in figure 2. μM, micromoles per liter; <, actual value is 

less than value shown]

Well number Date sample

taken

Tetrachloroethene 

(μM)

RW 26-0092 5-20-98 0.06

RW 26-0092 6-23-99 .05

RW 26-0092 8-10-99 .06

RW 26-0096 5-20-98 1.03

RW 26-0096 8-10-99 .25

RW 26-0100 5-20-98 1.28

RW 26-0100 8-10-99 .62

RW 26-0106 5-20-98 .41

RW 27-0098 5-19-98 .13

RW 27-0098 7-15-98 .49

RW 27-0098 4-06-99 .55

RW 27-0098 6-22-99 .45

RW 27-0098 2-09-00 .38

RW 27-0102 5-19-98 .26

RW 27-0102 7-15-98 .36

RW 27-0102 4-06-99 .21

RW 27-0102 6-22-99 .61

RW 27-0102 2-09-00 .48

RW 27-0108 5-19-98 .50

RW 27-0108 7-15-98 .43

RW 27-0108 4-06-99 .55

RW 27-0108 6-22-99 .24

RW 27-0108 2-09-00 .23

RW 27-0114 5-19-98 .10

RW 27-0114 7-15-98 .09

RW 27-0114 6-22-99 .04

RW 27-0114 2-09-00 .31

RW 27-0120 5-19-98 .07

RW 27-0120 7-15-98 .08

RW 27-0120 6-22-99 .02

RW 27-0120 2-09-00 .06

RW 28-0107 4-06-99 .26

RW 28-0107 6-22-99 .04

RW 29-0107 4-06-99 .52

RW 29-0107 6-22-99 .11

RW 29-0111 4-06-99 .01

RW 29-0111 6-23-99 .02

RW 30-0087 7-23-98 .01

RW 30-0087 7-29-98 .01

RW 30-0087 8-05-98 <.007

RW 30-0087 8-13-98 .01

RW 30-0087 8-20-98 .01

RW 30-0087 9-02-98 0.02

RW 30-0087 10-02-98 .01

RW 30-0087 10-26-98 .01

RW 30-0087 11-23-98 .02

RW 30-0087 1-25-99 .01

RW 30-0087 3-24-99 .02

RW 30-0087 6-21-99 .01

RW 30-0087 11-02-99 .01

RW 30-0087 2-08-00 <.007

RW 30-0096 7-23-98 .17

RW 30-0096 7-29-98 .14

RW 30-0096 8-05-98 .15

RW 30-0096 8-13-98 .14

RW 30-0096 8-20-98 .16

RW 30-0096 9-02-98 .25

RW 30-0096 10-02-98 .20

RW 30-0096 10-26-98 .63

RW 30-0096 11-23-98 .51

RW 30-0096 1-25-99 .56

RW 30-0096 3-24-99 .39

RW 30-0096 6-21-99 .14

RW 30-0096 11-02-99 .31

RW 30-0096 2-08-00 .17

RW 30-0100 7-23-98 .60

RW 30-0100 7-29-98 .81

RW 30-0100 8-05-98 .91

RW 30-0100 8-13-98 .94

RW 30-0100 8-20-98 .90

RW 30-0100 9-02-98 .79

RW 30-0100 10-02-98 .63

RW 30-0100 10-26-98 .95

RW 30-0100 11-23-98 .82

RW 30-0100 1-25-99 .72

RW 30-0100 3-24-99 .47

RW 30-0100 6-21-99 .44

RW 30-0100 11-02-99 .40

RW 30-0100 2-08-00 .17

RW 30-0106 7-23-98 .25

RW 30-0106 7-29-98 .20

RW 30-0106 8-05-98 .25

RW 30-0106 8-13-98 .27

RW 30-0106 8-20-98 .23

Well number Date sample

taken

Tetrachloroethene 

(μM)
74 Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers, Cape Cod, MA, 1997–2000

Table 10. Tetrachloroethene analyses for ground-water samples 

collected near the granular-iron permeable reactive barriers, 

Massachusetts Military Reservation, Cape Cod, Massachusetts, 

1997–2000.—Continued

[Source of data: David W. Hubble, University of Waterloo, Ontario, Canada. 

Locations of wells are shown in figure 2. μM, micromoles per liter; <, actual 

value is less than value shown]

Well No. Date sample

taken

Tetrachloroethene 

(μM)

RW 30-0106 9-02-98 0.36

RW 30-0106 10-02-98 .65

RW 30-0106 10-26-98 .42

RW 30-0106 11-23-98 .48

RW 30-0106 1-25-99 .29

RW 30-0106 3-24-99 .20

RW 30-0106 6-21-99 .43

RW 30-0106 11-02-99 .40

RW 30-0106 2-08-00 .25

RW 30-0117 7-23-98 .04

RW 30-0117 7-29-98 .03

RW 30-0117 8-05-98 .03

RW 30-0117 8-13-98 .03

RW 30-0117 8-20-98 .02

RW 30-0117 9-02-98 .02

RW 30-0117 10-02-98 .12

RW 30-0117 10-26-98 .02

RW 30-0117 11-23-98 .02

RW 30-0117 1-25-99 .01

RW 30-0117 3-24-99 .03

RW 30-0117 6-21-99 .06

RW 30-0117 11-02-99 .04

RW 30-0117 2-08-00 .19
Appendix 1. The Robowell Automated 

Sampling System

Appendix 1 77

Appendix 1. The Robowell Automated Sampling System

By Kirk P. Smith

Selected ground-water properties were monitored at 

well RW 27-0102A (fig. 2) by using the Robowell system. 

Robowell is an automated well-sampling device that was 

developed and tested by the USGS to provide a method 

for monitoring ground-water quality in accordance with 

protocols used for manual sampling (Granato and Smith, 1999; 

Granato and Smith, 2001). The process involves programmed 

instructions that activate equipment on a preset schedule to 

monitor and record ground-water quality as the well is purged. 

The purge-and-measurement process continues until purge 

criteria are met. Once the purge criteria are achieved, the 

final field measurements are stored electronically and can 

be retrieved remotely by cellular phone. The Robowell system 

was installed to provide nearly continuous water-quality 

information that would record any abrupt chemical changes 

that might occur between manual samplings.

The Robowell system consisted of a Campbell Scientific, 

Inc. (CSI) CR10X datalogger as the control module for the 

process. A 100-amp-hour battery recharged by two 30-watt 

solar panels was used to power the controller and other 

instruments; compressed nitrogen gas was used to power a QED 

bladder pump through a pneumatic logic controller; and a CSI 

VS1 voice/data telephone modem in conjunction with a 

Motorola cellular phone was used for communications. Purge 

water was captured in 55-gal drums because it contained 

substantial quantities of VOCs. To reduce the quantity of purge 

water, a QED inflatable packer under datalogger control was 

installed in the well just above the screen. Two opposing check 

valves were incorporated into a tee fitting at the beginning of 

the flow train. The inline check valve prevented backflow of 

purge water during the bladder-pump respiration cycles. The 

opposing check valve capped with a 0.45-μm filter allowed the 

pump tubing to drain through the pump weep holes after 

pumping was completed, thus protecting the line from freezing 

during the winter months. A hand-operated Plastomatic threeway valve was placed near the beginning of the flow train at the 

surface to divert water for manual collection of samples. All 

parts in contact with sample water—the bladder pump, pump 

tubing, and flow train—were constructed of Teflon or stainless 

steel. A 1.27-cm-diameter Data Industrial flow sensor was used 

to monitor the flow rate of ground water pumped through the 

system during purge and recording cycles. A Hydrolab 

Multiprobe under datalogger control was used to measure water 

temperature, pH, specific conductance, and dissolved oxygen 

concentration in a flow cell. The Hydrolab Multiprobe was 

calibrated monthly.

After a time-based activation, the system energized a 

series of solenoid valves that pressurized the inflatable packer 

and activated the pneumatic bladder-pump controller by 

using pressurized nitrogen gas. The datalogger compiled 

and recorded a running total of pump flow measured by the 

inline flow sensor. Water temperature, specific conductance, 

dissolved oxygen concentration, and pH were measured and 

recorded every 3 min throughout the purge cycle. Once the total 

pump flow was greater than or equivalent to the borehole 

volume beneath the inflatable packer, the last five water-quality 

measurements were compared to assess stability. The purge 

criteria programmed into the datalogger followed the groundwater sampling protocol developed for the USGS National 

Water-Quality Assessment Program, which is based on the 

assumption that geochemical stability indicates representative 

sampling from the aquifer opposite the screened interval 

(Koterba and others, 1995). The well was considered purged 

when the values of five successive water-quality measurements 

were within the ranges around the respective medians specified 

for physiochemical stability—water temperature, 0.2°C; 

pH, 0.1 standard units; specific conductance, 5 percent; 

and dissolved oxygen concentration, 9.4 μM. The final 

measurement of pH and the medians of the last five 

measurements of each of the other properties were recorded as 

the final values. Upon completion of the purge cycle, the system 

compared final water-quality properties to previously defined 

thresholds, depressurized the packer, and returned to a standby 

mode. When final water-quality properties or other system 

conditions (for example, lack of measured flow) exceeded 

previously defined thresholds, the datalogger called a specified 

phone number through the voice/data modem and reported the 

current condition. Recorded data were routinely downloaded 

remotely by means of the cellular phone and modem. 

References Cited

Granato, G.E., and Smith, K.P., 1999, Robowell—An 

automated process for monitoring ground water quality using 

established sampling protocols: Ground Water Monitoring 

and Remediation, v. 19, no. 4, p. 81-89.

Granato, G.E., and Smith, K.P., 2001, Automated process for 

monitoring ground-water quality using established sampling 

protocols, accessed on June 4, 2001, at URL http://

ma.water.usgs.gov/automon

Koterba, M.T., Wilde, F.D., and Lapham, W.W., 1995, Groundwater data-collection protocols and procedures for the 

National Water-Quality Assessment Program—Collection 

and documentation of water-quality samples and related data: 

U.S. Geological Survey Open-File Report 95-399, 113 p.