Field Tests of Polyethylene-Membrane 

Diffusion Samplers for Characterizing 

Volatile Organic Compounds in 

Stream-Bottom Sediments, Nyanza 

Chemical Waste Dump Superfund Site, 

Ashland, Massachusetts 

Nater-Resources' Investigations Report 00-4108 

vl~i .~lv v'IEN ~ tC : IIOiV AGENLY` 

EPA 

w.USGS


cience for a changing world 
U.S. Department of the Interior 

U.S. Geological Survey 

Field Tests of Polyethylene-Membrane 

Diffusion Samplers for Characterizing 

Volatile Organic Compounds in 

Stream-Bottom Sediments, Nyanza 

Chemical Waste Dump Superfund Site, 

Ashland, Massachusetts 

By FOREST P. LYFORD, RICHARD E . WILLEY, and SCOTT CLIFFORD


Water-Resources Investigations Report 00-4108


Prepared in cooperation with the


U.S . ENVIRONMENTAL PROTECTION AGENCY


Northborough, Massachusetts


2000

UBRUCE 

U

Charles 

.S.S .

.GEOLOGICAL DEPARTM

G

BABBITT, 

. Groat, Director 

SURVEY 

Secretary OF THE INTERIOR
 The use of trade or product names in this report is for identification 

purposes only and does not constitute endorsement by the 

U.S . Geological Survey. 

For additional information write to: 

Chief, Massachusetts-Rhode Island District


U.S. Geological Survey


Water Resources Division


10 Bearfoot Road


Northborough, MA 01532


or through our website at 

http://ma.water .usgs.gov 

Copies of this report can be purchased from :


U.S. Geological Survey


Branch of Information Services


Box 25286


Denver, CO 80225-0286

CONTENTS 

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

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

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

Study Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 

Distribution of Volatile Organic Compounds Detected in Vapor-Diffusion Samplers . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 

Equilibration Time for Volatile Organic Compounds in Diffusion Samplers . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 

Comparison of Chemical Analytical Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 

Vapor- and Water-Diffusion Samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 

Water-Diffusion Samples and Seepage-Meter Samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 

Water-Diffusion Samples and Sediment Samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 

Use of Diffusion Samplers as Reconnaissance Tools. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 

Summary . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 

References . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 

FIGURES 

1, 2. Maps showing: 

1. Location of Nyanza Chemical Waste Dump Superfund Site, sampling locations, potentiometricsurface contours for the surficial aquifer, and directions of ground-water flow, Ashland, 

Massachusetts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 

2. The extent of contaminants in ground water and concentrations of chlorobenzene and 

trichloroethene detected in vapor-diffusion samplers on February 16, 1999 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 

3. Stream-stage hydrograph for the Sudbury River at Saxonville, Massachusetts, and the Assabet River at 

Maynard, Massachusetts, and sampling dates, December 1998 to February 1999 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . 6 

4. Diagram showing the locations of clusters of vapor-diffusion samplers relative to locations of (A) seepage 

meter PW02-01, and (B) seepage meter PW07-01 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 

5-7. Graphs showing: 

5. Concentrations of chlorobenzene and trichloroethene detected in vapor-diffusion samplers at 

(A) sample location 02-01 and (B) sample location 07-01, January and February 1999 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 

6. Concentrations of (A) chlorobenzene and (B) trichloroethene in vapor- and water-diffusion samplers, 

February 16, 1999 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 

7. Concentrations of selected volatile organic compounds detected in water-diffusion samplers and 

concentrations in water from seepage meters . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 

TABLES 

1 . Summary of sample numbers at sampling locations, Nyanza Chemical Waste Dump Superfund Site, 

Ashland, Massachusetts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 

2. Concentrations of volatile organic compounds detected in vapor from vapor-diffusion samplers retrieved 

on February 16, 1999, near the Nyanza Chemical Waste Dump Superfund Site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 

3. Concentrations of volatile organic compounds detected in clusters of vapor-diffusion samplers retrieved 

during January and February 1999 near the Nyanza Chemical Waste Dump Superfund Site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 

4. Concentrations of volatile organic compounds in vapor-diffusion samplers, water-diffusion samplers, 

seepage meters, and sediments, December 1998 to February 1999, Nyanza Chemical Waste Dump 

Superfund Site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 

Contents III 
CONVERSION FACTORS, VERTICAL DATUM, AND ABBREVIATIONS 

CONVERSION FACTORS 

Multiply By To obtain 

feet (ft) 0.3048 meters 

inches (in.) 2.54 centimeters 

mil (mil) 0.0254 millimeters 

Temperature in degrees Celsius (°C) may be converted to


degrees Fahrenheit (°F) as follows:


°F=1 .8 °C+32


VERTICAL DATUM 

Sea level: In this report, "sea level" refers to the National Geodetic Vertical Datum of 1929 (NGVD 

of 1929)-a geodetic datum derived from a general adjustment of the first-order level nets of the 

United States and Canada, formerly called Sea Level Datum of 1929 . 

ABBREVIATIONS 

cis-DCE cis-1,2-dichloroethene 

ppb v parts per billion by volume 

mg/kg milligrams per kilogram 

mL milliliter 

PCE tetrachloroethene


SVOCS semi-volatile organic compounds


TCE trichloroethene 

Ng/kg micrograms per kilogram 

Rg/L micrograms per liter 

pS/cm microsiemens per centimeter at 25°C 

VOCS volatile organic compounds 

1V Contents 
Field Tests of Polyethylene-Membrane Diffusion 

Samplers for Characterizing Volatile Organic 

Compounds in Stream-Bottom Sediments, 

Nyanza Chemical Waste Dump Superfund Site, 

Ashland, Massachusetts 

By Forest R Lyford, Richard E. Willey, and Scott Clifford 

Abstract 

Aplume of volatile organic compounds 

(VOCs) in ground water extends from the Nyanza 

Chemical Waste Dump Superfund site in Ashland, 

Massachusetts, northward toward a mill pond on 

the Sudbury River and eastward toward the 

Sudbury River and former mill raceway 

downstream from the mill pond. Polyethylenemembrane water-to-vapor (vapor) and water-towater (water) diffusion samplers were installed in 

January 1999 in bottom sediments along the 

Sudbury River and former mill raceway in a pilot 

study to determine if vapor samplers would be 

useful in this setting for delineating a plume of 

contaminants in ground water near the river and 

raceway, to evaluate equilibration time for vapordiffusion samplers, and to determine if diffusion 

samplers might be an alternative to seepage meters 

(inverted steel drums) and sediment sampling for 

evaluating concentrations of VOCs in bottom 

sediments. 

Of five tested compounds (benzene, trichloroethene, toluene, tetrachloroethene, and chlorobenzene), chlorobenzene and trichloroethene 

were most frequently detected in vapor from 

vapor-diffusion samplers. The distribution of 

VOCs was generally consistent with a previously 

mapped plume of contaminants in ground water. 

The field evaluation of equilibration times for 

vapor-diffusion samplers was inconclusive 

because of changing hydrologic conditions that 

may have affected concentrations of VOCs, 

possible variations in concentrations ofVOCs over 

short distances, and imprecise sampling and analytical methods. The limited data, however, indicated that equilibration may require 3 weeks or 

more in some settings. 

VOCs detected in samples from waterdiffusion samplers and their concentrations were 

comparable to results from seepage meters, and 

VOCs detected in vapor-diffusion samplers correlated with VOCs detected in water-diffusion 

samplers. These results indicate that either vaporor water-diffusion samplers would serve as an economical alternative to seepage meters for sampling 

of VOCs in pore water from stream-bottom 

sediments. Results from diffusion samplers correlated poorly with results from sediment samples, 

partly because of high quantitation limits for 

chemical analyses of sediments. In general, results 

from the diffusion samplers better represented the 

distribution of VOCs than the results from the sediment samples. This pilot study indicates that diffusion samplers are an economical means of 

identifying "hot spots" for contaminants in bottom 

sediments and can provide insights on transport 

pathways for contaminants near surface-water 

bodies. After establishing equilibration times for a 

particular site, diffusion samplers also may be 

useful for studying variations in concentrations of 

VOCs over short distances, variations with time 

and changing hydrologic conditions, and processes such as chemical transformations by biodegradation and exchanges between surface water 

and ground water in the hyporheic zone. 

Abstract 1 
INTRODUCTION 

Volatile organic compounds (VOCs) and semivolatile organic compounds (SVOCs) are present in 

ground water near the Nyanza Chemical Waste Dump 

Superfund site (Nyanza site) in Ashland, Mass. (Roy F. 

Weston, Inc., 1998). Water-quality data and water-level 

data from monitoring wells indicate that contaminated 

ground water discharges to the surface in two areas: 

(1) along the Sudbury River at the upstream end of a 

mill pond and (2) along the Sudbury River and a former 

mill raceway downstream from the mill pond and 

parallel to the river (fig . 1) (Roy F. Weston, Inc., 1998). 

During 1998--99, the U.S . Environmental Protection 

Agency (USEPA), through the U.S . Army Corps of 

Engineers (USACE), supported a study by Roy F. 

Weston, Inc. (1999b) of contaminants in bottom 

sediments along the Sudbury River and former mill 

raceway. In this study, water was extracted from 

inverted steel drums (seepage meters) placed in streambottom sediments. Bottom sediments also were 

sampled for VOCs, SVOCs, and mercury. The USEPA 

requested that the USGS use polyethylene-membrane 

water-to-vapor diffusion samplers (referred to as vapordiffusion samplers in this report) to test their 

application for delineating the distribution of VOCs in 

ground-water discharge areas and as a pilot study to 

determine if vapor- and polyethylene-membrane waterto-water-diffusion samplers (referred to as waterdiffusion samplers in this report) might serve as costeffective alternatives to other methods for 

characterizing contaminants at the interface between 

ground water and surface water. Also of interest to 

USEPA is the time needed for VOC concentrations in 

ground water to re-equilibrate after sediments have 

been disturbed by emplacement of vapor-diffusion 

samplers. 

The objectives of this study were to : 

1 . Determine if the distribution and concentrations 

of VOCs detected in vapor-diffusion samplers, 

which were placed in stream-bottom sediments, 

are consistent with the previously mapped 

distribution of contaminants in ground water 

near the Nyanza site, Ashland, Mass. 

2. Determine the time needed for VOCs in bottom 

sediments to re-equilibrate after installation of 

the samplers . 

3. Determine if vapor- and water-diffusion samplers 

might serve as alternatives to other sampling 

techniques, specifically seepage meters and 

sediment sampling, to characterize the 

occurrence of VOCs in stream-bottom 

sediments. 

This report (1) describes the distribution of 

VOCs along the Sudbury River and mill raceway 

determined by use of vapor-diffusion samplers; 

(2) presents results of an experiment to determine 

equilibration times for VOCs after installation of 

samplers in sediments; (3) compares results from 

vapor-diffusion samplers to results from water 

diffusion samplers, seepage meters, and sediment 

sampling; (4) discusses considerations for using 

diffusion samplers on the basis of results from this pilot 

study, and suggests additional studies that would 

further test and refine the use of diffusion samplers for 

characterizing contaminants at the interface between 

ground water and surface water. 

USGS personnel constructed, installed, and 

retrieved vapor and water-diffusion samplers. The 

vapor-diffusion samples were analyzed on site by 

Scott Clifford, USEPA. Water samples from diffusion 

samplers and water samples from seepage meters were 

submitted by Roy F. Weston, Inc., personnel to a 

private laboratory for analysis . Appreciation is 

extended to Sharon Hayes, USEPA Site Manager, 

and Kathleen Taylor, Roy F. Weston, Inc., for logistical 

support and assistance during the study. 

DESCRIPTION OF STUDY AREA 

The study area is along the Sudbury River in 

Ashland, Massachusetts. At its closest point, the river is 

approximately 700 ft north of the Nyanza site (fig . 1). 

The upstream part of the study area is within a former 

mill pond. The downstream part of the study area 

below the mill pond includes the Sudbury River and a 

former mill raceway. 

2 Tests of Diffusion Samplers for Characterizing VOCs in Sediments, Nyanza Chemical Waste Dump Superfund Site, Ashland, Mass. 
------------

606,000 607,000 608,000 609,000 610,000 

460,000 

459,000 

458,000 

MILL PON1) 

(w-01 

RAILROAD 

NYANZA 

CHEMICAL 

WASTE DUMP 

SUPERFUND 

SITE 

w w 

TES \ \ , channel -A I 

07-02 

MMW4405B\~ a-2 s,a . . " 

~Z v a- 1/1 

EXPLANATION 

APPROXIMATE BOUNDARY OF NYANZA CHEMICAL 

WASTE DUMP SUPERFUND SITE 

1s0- POTENTIOMETRIC CONTOUR IN SURFICIALAQUIFERShows altitude at which waterlevel would have stood in wells 

completed in surficial materials. Dashed where 

approximately located. Interval is 5 feet. Datum is sea level. 

Data from Roy F. Weston, Inc., 1998 

GENERAL DIRECTION OF GROUND-WATER FLOW 

IN SURFICIAL AQUIFER 

01-01 LOCATION ANDNUMBER OF MULTI-SAMPLE 0 GROUP-Sample groups include vapor- and waterdiffusion pairs, seepage meters, and sediment samples. 

May also include clusters of vapor-diffusion samplers 

Vla VAPOR-DIFFUSION SAMPLER ONLY 

02-01 MULTI-SAMPLE GROUP IEI 

MW-305B SELECTED MONITORING WELL 

0 200 400 600 FEET 

0 100 METERS 

_-____--___--____-____-____-___ : 

Base map modified from area site plan, Department of the


Army New England District Corps of Engineers,


Concord, Massachusetts and Weston Managers Designers/Consultants,


1,000 foot grid based on Massachusetts State coordinate system, mainland zone


Figure 1 . Location of Nyanza Chemical Waste Dump Superfund Site, sampling locations, potentiometric-surface contours for the surficial aquifer, and 

directions of ground-water flow, Ashland, Massachusetts. 
The ground-water system includes a surficial 

aquifer that consists of glacial lake deposits, till, and 

fractured crystalline rock. The glacial lake deposits 

range in grain size from silt to coarse sand and gravel . 

The thickness of fine-grained sediments increases 

eastward, and the till layer is discontinuous beneath the 

lake sediments (Ebasco Services, Inc., 1991, figs . 3-5 

to 3-12). The depth to bedrock increases from less than 

30 ft in the mill pond area to nearly 80 ft in an eastwest trending trough that passes through the area near 

wells MW405A and MW405B downstream from the 

dam (Ebasco Services, Inc., 1991, fig. 3-1) (fig . 1). 

Most of the Superfund Site is on till-covered bedrock. 

In general, ground water flows northward and 

eastward from the Nyanza site toward the Sudbury 

River. Apotentiometric surface map for the surficial 

aquifer (Roy F Weston, Inc., 1998) (fig. 1) indicates 

that ground water in the western part of the study 

area flows northward toward the Sudbury River at 

the upstream end of the mill pond. The close spacing 

of potentiometric contours within the Nyanza site 

reflects the occurrence of ground water in poorly 

transmissive till . The direction of ground-water flow 

shifts eastward near the downstream end of the mill 

pond and downstream from the mill pond. Water-level 

data presented by Roy F. Weston, Inc. (1998), also 

indicate that water infiltrates from the pond to the 

aquifer downstream from sampling location 04-01. 

The raceway appears to receive much of its water 

from ground-water sources. During the study period, 

however, the upstream end of the raceway was 

receiving some flow from the Sudbury River through 

a connecting channel (fig . 1). 

Aplume of contaminants in the surficial and 

bedrock aquifer system extends from the area of the 

Nyanza site northward to the Sudbury River and mill 

pond. The plume also extends eastward to the river 

and raceway downstream from the dam (fig . 2). VOCs 

that have been detected in ground water include 1,1,1-

trichloroethane, benzene, chlorobenzene, cis-DCE, 

PCE, TCE, and vinyl chloride (Roy F Weston, Inc., 

1999a; 1999b) . Chlorobenzene, TCE, and cis-DCE are 

the VOCs most commonly detected in ground water. 

Concentrations of VOCs in water from monitoring 

wells near the mill pond (fig. 1) are highest in well 

MW-305A, which was completed in bedrock. VOCs 

detected in a sample collected from this well in January 

1999 included chlorobenzene (2,400 pg/L), cis-DCE 

(82 [ug/L), TCE (2,700 jig/L), and vinyl chloride 

(2 pg/L). Also detected were mercury (1 .38 [tg/L) and 

the SVOCs 1,2,4-dichlorobenzene (71 Rg/L), 1,2-

dichlorobenzene (1,700 [tg/L), 1,3-dichlorobenzene 

(69 [g/L), and 1,4-dichlorobenzene (350 ~tg/L) . VOC 

concentrations in a water sample collected from well 

MW-305B completed in surficial materials at the same 

location were less than 10 [g/L, mercury concentration 

was 0.109 [g/L, and SVOCs were not detected . 

Concentrations ofVOCs in water from 

monitoring wells MW-405A and MW-405B located 

between the Sudbury River and the mill raceway are 

highest in well MW-405B completed in the surficial 

aquifer. VOCs detected in a sample collected from 

this well in January 1999 included chlorobenzene 

(5,600 pg/L), cis-DCE (120 ~ug/L), and TCE 

(7,600 pg/L). Vinyl chloride was below the detection 

limit of 2 [tg/L. Also detected were mercury 

(0.0124 [tg/L) and the SVOC 1,2-dichlorobenzene 

(450 pg/L). The SVOCs 1,3-dichlorobenzene, and 1,4-

dichlorobenzene were below the detection limits of 

220 gg/L. VOCs detected in a water sample collected 

from well MW-405A, which was completed in bedrock 

at the same location, were chlorobenzene (29 [tg/L) 

and TCE (34 [ug/L) . Mercury was detected at a 

concentration of 0.0256 [tg/L, and concentrations of 

SVOCs were below 50 Rg/L. 

Stream-bottom materials near sampling site 01-

01 are cobbles and pebbles. Downstream from this site, 

the bottom material is a thick layer of soft organic 

matter. In the cove of the mill pond near sampling site 

05-05, bottom materials along the shore are rocks and 

gravel . The river bottom downstream from the dam 

consists of rocks and coarse gravel . Bottom materials 

along the raceway are mainly soft and organic-rich, 

except near the downstream sampling location (08-01) 

where the bottom consists of gravel . 

At the time samplers were installed on January 

19-20,1999, the mill pond was ice covered except in a 

few open areas near the shore. Several samplers were 

placed through holes cut in the ice. The river and 

raceway downstream from the dam were ice free . 

Several rain storms and periods of snowmelt caused 

streamflow and stream stage to rise during the period 

when samplers were in place. The pond was largely ice 

free when samplers were retrieved on February 16, 

1999. Stage hydrographs for the Sudbury River at 

Saxonville, Mass., and the Assabet River at Maynard, 

Mass. (fig . 3), located several miles from Ashland, 

indicate that streamflow conditions varied during the 

study period . 

4 Tests of Diffusion Samplers for Characterizing VOCs in Sediments, Nyanza Chemical Waste Dump Superfund Site, Ashland, Mass. 
606,000 607,000 608,000 609,000 610,000 

TCE-ND 

CB-ND 

460,000 

459,000 

Rp TCE-ND 

CB-78 

N'7-1 / . . w V8-2 

i ' V7b-1 VSa-1 TCE-35 (LOST) ,~v8-1

CB-1780 

EXPLANATION 

STANDARDS FOR DRINKING WATER FROM GROUND 

WATER EXCEEDED-Shows area whereat least one chemical 

in ground waterthat is believed to originate from Nyanza site exceeds 

Massachusetts criteria for drinking water. The location of this line 

was determined on the basis of water samples from numerous wells 

not shown on this map (Roy F. Weston, Inc., 1999a) 

CONCENTRATIONS OF TRICHLOROETHENE (TCE) AND 

TCE-34 CHLOROBENZENE (CB) IN VAPOR-DIFFUSION SAMPLERSCB-130	 Numbers are concentrations in parts per billion by volume on 

February 16, 1999 ; ND, not detected . See table 2 for other chemicals 

458,000 V1 

Base map modified from area site plan, Department of the


Army New England District Corps of Engineers,
 Concord, Massachusetts andWeston Managers Designers/Consultants,


1,000foot grid based on Massachusetts State coordinate system, mainland zone


detected in vapor-diffusion samplers . 

VAPOR SAMPLER LOCATION ANDNUMBER 

0 500 1000 FEET 

I I

I I I r 

0 100 200 300 METERS 

Figure 2. The extent of contaminants in ground water and concentrations of chlorobenzene and trichloroethene detected in vapor-diffusion samplers on 

February 16, 1999, Ashland, Massachusetts . 
Z

0

a 

w 

U

Z 

w 

w 

w 

w 

O 

m 

H

w

w 

Z 

O 

w 

w 

O

Q

O 

14 21 28 4 11 18 25 1 8 15 22 

DECEMBER JANUARY FEBRUARY 

1998 1999 

Figure 3. Stream-stage hydrograph for the Sudbury River at Saxonville, Massachusetts, and the Assabet 

River at Maynard, Massachusetts, and sampling dates, December 1998 to February 1999. 

STUDY METHODS 

Vapor- and water-diffusion samplers were 

constructed using methods modified slightly from 

those described by Vroblesky and others (1996), 

Vroblesky and Hyde (1997), and Vroblesky and others 

(1999) . Vapor samplers consisted of an uncapped 

40-mL, air-filled bottle inside two layers of 4-mil 

thick polyethylene tubing that had been secured with 

plastic cable ties . Upon retrieval, the outer layer of 

polyethylene was removed and a cap was placed on the 

bottle over the inner layer. Water-diffusion samplers 

consisted of a 4-mil thick polyethylene tube filled with 

deionized water and heat sealed at both ends. The tube 

contained enough water to fill three 40-mL vials. 

Table 1 summarizes sample numbers for each sample 

type at each location . For this report, a location may 

include several samplers or sampling points within a 

radius of about 6 feet . Sample sites and numbers are 

shown on figure 1 . 

Vapor- and water-diffusion samplers (sampler 

pairs) were placed together in a wire cage for 

protection and inserted in bottom sediments at nine 

locations (fig . 1) on January 19-20, 1999. The samplers 

were placed at a distance of 5 to 6 feet from seepage 

meters to minimize effects, if any, of sampler 

installation on operation of the seepage meters . The 

samplers were inserted manually into a hole formed 

behind a narrow-bladed shovel inserted into the bottom 

sediments to depths of 6 to 8 in . below the stream 

bottom . The vapor- and water-diffusion pair was 

omitted at location 08-02, but a single vapor-diffusion 

sampler was installed. 

Two clusters of three closely spaced (within 1 

foot laterally) vapor-diffusion samplers were placed 

near the seepage meters at each of the locations 02-01 

and 07-01 to evaluate the equilibration time in two 

areas where concentrations of VOCs were likely to be 

elevated (fig . 4) . The clusters were placed 5 to 6 ft from 

the seepage meters, and one cluster at each of the two 

6 Tests of Diffusion Samplers for Characterizing VOCs in Sediments, Nyanza Chemical Waste Dump Superfund Site, Ashland, Mass. 
Table 1 . Summary of sample numbers at sampling locations, Nyanza Chemical Waste Dump Superfund Site, Ashland, 

Massachusetts 

[No., number] 

Sampling 

location No. 

Sediment 

sample No. 

Seepage Vapor-diffusion 

meter No. sample No. 

Water-diffusion 

sample No. 

Vapor-diffusion 

cluster No. 

Sudbury River in Millpond 

01-01 SW01-01 PW01_01 Vl W1 none 

02-01 SW02-01 PW02-01 V2 W2 V2-Cla, b, and c 

V2-C2a, b, and c 

03-01 SW03-01 PW03-01 V3 W3 none 

04-01 SW04-01 PW04-01 V4 W4 none 

05-01 SW05-01 PW05-01 V5 W5 none 

Sudbury River Downstream from Dam 

06-01 SW06-01 PW06-01 V6 W6 none 

07-02 SW07-02 PW07-02 V7-2 W7-2 none 

08-02 SW08-02 PW08-02 V8-2 none none 

Former Mill Raceway 

07-01 SW07-01 PW07-01 

08-01 SW08-01 PW08-01 

seepage meters was at the location of the vapor- and 

water-diffusion pair. Clusters at location 02-01 were 

labeled V2-Cla, b, and c and V2-C2a, b, and c, and 

clusters at location 07-01 were labeled V7-Cla, b, and 

c and V7-C2a, b, and c (table 1, fig. 4) . 

Additional vapor-diffusion samplers were placed 

at 13 locations near and between sampling locations 

(fig . 1) to better define the extent of VOCs in bottom 

sediments. Labels for these samplers included lowercase letters a and b in downstream order from the 

sampling location . For example, Vla is downstream 

from location 01-01 and V2a is downstream from 

location 02-01. Vapor samplers Vlz near location 01-

01 and V8a-1 near location 08-01 are exceptions to this 

labeling scheme. Duplicate vapor-diffusion samplers 

were placed at four of these locations for quality 

assurance. Asampler (V7b-1) placed in the raceway 

disappeared prior to retrieval. Installation points were 

limited downstream from the dam on the Sudbury 

River because of steep banks, deep and swift water, and 

rocky bottom materials. 

Vapor-diffusion samplers were installed with a 

narrow-bladed shovel as discussed above, or, in areas 

of deep water (generally greater than 2 ft), through a 

hole formed by driving a pipe assembly that consisted 

of a 2-inch outer pipe and a 1 .5-inch, pointed inner pipe 

into bottom sediments. In general, samplers were at 

V7-1 W7-1 V7-Cla, b, and c 

V7-C2a, b, and c 

V8-1 W8-1 none 

depths that ranged from 8 to 12 in . in bottom 

sediments. Samplers at each cluster, however, were at a 

uniform depth of 12 in . 

One vapor-diffusion sampler from each of the 4 

clusters was retrieved once a week for 3 weeks after 

installation and transported with a trip blank to the 

USEPA Lexington laboratory for analysis . The 

remaining vapor samplers and water-and vapordiffusion sampler pairs were retrieved four weeks after 

installation when water samples were collected from 

seepage meters. Installation and retrieval dates are 

shown with stream-stage data on figure 3. 

Vapor-diffusion samples were analyzed for 

VOCs in accordance with the Region I standard air 

screening method (U.S . Environmental Protection 

Agency, 1998) with a Photovac gas chromatograph 

equipped with a 4-foot by 1/8-inch SE-30 column and 

photoionization detector. Samples were analyzed 

within 3 hours of sample collection . Samples collected 

on February 16, 1999, were analyzed onsite in a mobile 

laboratory. Target compounds for vapor samples were 

benzene, toluene, TCE, PCE, and chlorobenzene. 

Water samples were decanted from the 

polyethylene tubes to 40-mL glass vials that contained 

hydrochloric acid as a preservative . These samples 

were shipped with samples from the seepage meters to 

a contract laboratory for analysis of VOCs using 

USEPA Method 8260. The VOCs that were analyzed 

using Method 8260 are as follows: 

Study Methods 7 
Chloromethane Carbon Tetrachloride 1,1,1,2-Tetrachloroethane 

Bromomethane Bromodichloromethane 1,1,2,2-Tetrachloroethane 

Vinyl Chloride 1,2-Dichloropropene Toluene 

Chloroethane t-1,3-Dichloropropene Chlorobenzene 

Methylene Chloride Trichloroethene Ethylbenzene 

Trichlorofluoromethane Dibromochloromethane Acetone 

1,1-Dichloroethylene c-1,3-Dichloropropene Carbon Disulfide 

1,1-Dichloroethane 1,1,2-Trichloroethane 2-Butanone (MEK) 

1,2-Dichloroethylene isomers Benzene 2-Hexanone 

Chloroform 2-Chloroethylvinyl ether 4-Methyl-2-Pentanone (MIBK) 

1,2-Dichloroethane Bromoform Styrene 

1,1,1-Trichloroethane Tetrachloroethene Xylenes (total) 

Seepage meters were installed on December 31, 

1998, by Roy R Weston, Inc., personnel (Roy F. 

Weston, Inc., 1999b) at locations summarized in table 

1. Aseepage meter consisted of a section of a 55-gallon 

steel drum that was inserted open-end down into 

bottom sediments. Water samples were collected 

through a valve placed in the top of the steel drum. 

Ideally, samples would be collected in a polypropylene 

bag attached to the valve that filled under natural 

seepage conditions after surface water trapped in the 

drum had been fully purged . Observations of seepage 

rates indicated that the drums would not fully purge 

during the study period. To reduce the time needed for 

purging, the seepage meters were pumped at a slow 

rate on January 18, 1999, using a peristaltic pump, 

while temperature, pH, specific conductance, 

oxidation-reduction potential, and dissolved oxygen 

were monitored to detect the possible breakthrough of 

surface water. Results from purging on January 18, 

1999, were used to determine optimum pumping rates 

during sampling . Samples were collected from the 

seepage meters on February 15 and 16, 1999, by 

purging with a peristaltic pump at a rate of less than 

300 mL/min. Again, the field parameters listed above 

were monitored to detect the possible breakthrough of 

surface water; the breakthrough of surface water was 

not apparent during sampling (Roy F. Weston, Inc., 

1999b) . 

Sediment samples collected from the river, mill 

pond, and river and mill raceway by Roy F. Weston, 

Inc., personnel from December 26 to 30, 1998, were 

analyzed for mercury, arsenic, SVOCs, VOCs, and 

grain size (Roy F. Weston, Inc., 1999b) . Anumber of 

these samples were collected at locations other than 

those shown on figure 1 and are not discussed in this 

report . All samples were collected at depths of 0 to 6 in . 

Sample numbers are consistent with numbers used for 

other sampling methods. For example, sediment 

sample SDOl-01 is at location 01-01 (table 1) . 

DISTRIBUTION OF VOCS DETECTED IN 

VAPOR-DIFFUSION SAMPLERS 

In general, the distribution of VOCs detected in 

vapor-diffusion samplers collected on February 16, 

1999, is consistent with the mapped distribution of 

contaminants in ground water that exceed 

Massachusetts criteria for drinking water (fig . 2). 

Chlorobenzene and TCE were the principal VOCs 

detected in vapor-diffusion samplers (table 2) . Either 

chlorobenzene, TCE, or both were detected at 10 of 13 

samplers upstream from the dam (not including 

duplicate samples), 1 of 4 samplers along the Sudbury 

River downstream from the dam, and 4 of 4 samplers 

along the raceway. Chlorobenzene and TCE typically 

were detected in the same samples, except at V1, 

Vlz and Vla where TCE was detected but not 

chlorobenzene and at V7-2 where chlorobenzene was 

detected but not TCE. Benzene was detected at five 

samplers (V4, V7-1, V7a-1, and V8-1, V8a-1), toluene 

was detected at a trace concentration in sampler V4b, 

and cis-DCE was identified at several samplers, but 

concentrations were not determined. TCE detections 

at location O1-01 were somewhat upstream from the 

mapped plume. The absence of chlorobenzene and 

TCE at samplers V4b and V5 at the downstream end of 

the mill pond is consistent with observations that the 

pond is a recharge source to ground water in that area . 

The absence of VOCs at sampler V3b cannot be 

explained on the basis of current knowledge about 

ground-water pathways. 

8 Tests of Diffusion Samplers for Characterizing VOCs in Sediments, Nyanza Chemical Waste Dump Superfund Site, Ashland, Mass. 
S(/I)BC!RYRI[-TR 

Figure 4. Locations of clusters of vapor-diffusion samplers relative to locations of (A) seepage meter PW02-01 and 

(B) seepage meter PW07-01, Ashland, Massachusetts. 

Distribution of Volatile Organic Compounds in Vapor-Diffusion Samplers 9

-- -- -- -- --

0	 Table 2. Concentrations of volatile organic compounds detected in vapor from vapor-diffusion samplers retrieved on February 16, 1999, near the Nyanza Chemical 

Waste Dump Superfund Site, Ashland, Massachusetts 

N (Volatile organic compound: Compoundnot detected at the reporting limit given in parentheses . PCE, tetrachloroethene ; TCE, trichloroethene ; trace, compound detected at concentration below reporting 0 limit. Other compounds detected and comments : DCE, dichloroethene ; EUPs, early unidentified peaks on gas chromatograph . dup, field duplicate sample ; ppb v, parts per billion by volume; v --, not analyzed]


c


y Vapor Date Bottom 

Volatile organic compound Other compounds
 sampler installed material Benzene TCE Toluene PCE Chlorobenzene detected and comments 3 name (ppb v) (ppb v)

v (ppb v) (ppb v) (ppb v) 

N Sudbury River in Millpond 

O VI 1-19-99 Cobbles and pebbles (12) 18 (40) (20) (40) n 

A Vla (dup) 1-19-99 Organic (12) 49 (40) (20) (40) 

N Vlb 1-19-99 Organic (12) 220 (40) (20) 52 

c V2 1-19-99 Organic -very soft (12) 560 (40) (20) 960 

s Vlz 1-19-99 Cobbles and pebbles (12) 23 (40) (20) (40) d 

m Vla 1-19-99 Organic (12) 37 (40) (20) (40) n 

O V2a 1-19-99 Organic (12) 43 (40) (20) 520 n

N V2a (dup) 1-19-99 Organic (12) 80 (40) (30) 490 

7 

CO 

a V3 1-19-99 Organic (12) 1,910 (40) (20) 2,250 

3 Via 1-19-99 Organic (12) 23 (40) (20) 1,270 

N 

Z 

V3b 

V4 

1-19-99 

1-19-99 

Organic 

Organic 

(12) 

54 

(12) 

430 

(40) 

(40) 

(20) 

(20) 

(40) 

5,330 

V4b 1-19-99 Gravel (12) (12) trace (20) (40) 

V2b 1-19-99 Organic (12) 340 (40) (20) 210 

m 

N VS 1-19-99 Gravel (12) (12) (40) (20) ( 40)


0
3 Sudbury River Downstream from Dam
 fD
 3


V6 1-19-99 Gravel (12) (12) (40) (20) (40) 

V7-2 1-19-99 Gravel (12) (12) (40) (20) 78 

_', °

0 V7a-2 (dup) 

V8-2 

1-19-99 

1-19-99 

Gravel 

Gravel 

(12) 

(12) 

(12) 

(12) 

(40) (20) 

(40) (20) 

(40) 

(40) 

N Former Mill Raceway 

c 

V7a-2 1-19-99 Gravel (12) (12) (40) (20) (40) u

V7-1 1-19-99 Organic 18 590 (40) (20) 940 

c


o'


N V7a-1 1-19-99 Organic 55 35 (40) (20) 1,780


V7a-1 (dup) 1-19-99 Organic 51 37 (40) (20) 1,630 

y V7b-1 (lost) 1-19-99 Organic 

iv V8-1 1-19-99 Gravel 15 34 (40) (20) 130 

a V8a-1 1-19-99 Gravel 15 26 (40) (20) 93 

d

N

N 

EUPs


EUPs. Sampler placed 6 ft from V1


Installed in ice-free water near bank


Installed in ice-free water near bank . EUPs, cis-DCE


At location of V2-C1 cluster.


EUPs, cis-DCE


EUPs, cis-DCE


EUPs, cis-DCE


EUPs, cis-DCE


EUPs, cis-DCE


EUPs, cis-DCE


EUPs, cis-DCE


EUPs, cis-DCE


EUPs


EUPs


EUPs


EUPs


EUPs


EUPs


EUPs, cis-DCE. Placed at location of


V7-C2 cluster.


EUPs, cis-DCE


EUPs, cis-DCE


Placed between PW7-1 and PW8-1 in raceway


EUPs, cis-DCE


EUPs, cis-DCE. Located about 1 ft from V8-1 .

Although data are limited, results from vapor 

samplers indicate that the VOCs in bottom sediments 

along the Sudbury River were present in low 

concentrations (chlorobenzene detected at a 

concentration of 78 ~Ig/L at location V7-2) or absent 

downstream from the dam at the time of the study. The 

presence of elevated concentrations in samplers placed 

along the raceway (table 2, fig. 2), however, is 

consistent with the mapped extent of the contaminant 

plume in ground water (fig . 2) . VOCs detected at 

location 08-01 in the raceway beyond the mapped 

extent of the plume may reflect the presence of VOCs 

in surface water at this location (Roy F. Weston, Inc., 

1999b) and an exchange of VOCs between surface 

water and ground water. Similar conditions for the 

Royal River near Gray, Maine, downstream from a 

TCE plume in ground water, have been described by 

Lyford and others (1999) . 

EQUILIBRATION TIME FOR VOCS IN 

DIFFUSION SAMPLERS 

Results of analyses for vapor samplers retrieved 

about once a week from the 4 clusters were not 

conclusive with regard to equilibration time (table 3, 

figs . 5A and 5B). Results of experiments elsewhere 

have shown that concentrations of VOCs in vapordiffusion samplers equilibrate within less that 24 

hours when placed in a solution that has a known 

concentration ofVOCs. Equilibration after 

emplacement can be within a period of 24 hours 

when placed in sandy materials, but can take several 

days when placed in fine-grained materials (D.A. 

Vroblesky, U.S . Geological Survey, written commun., 

1999) . Apparent general increases in concentrations of 

chlorobenzene and TCE with time at clusters V2-C1 

and V7-C2 (table 3, fig. 5) may reflect slow 

equilibration times of 3 weeks or more at these 

Table 3. Concentrations of volatile organic compounds detected in clusters of vapor-diffusion samplers retrieved during

January and February 1999 near the Nyanza Chemical Waste Dump Superfund Site, Ashland, Massachusetts 

[Volatile organic compound: Compound not detected at the reporting limit given in parentheses . PCE, tetrachloroethene ; TCE, trichloroethene ; trace, compound detected at concentration below reporting limit. Other compounds detected and comments : DCE, dichloroethene ; EUPs, early unidentified peaks on 

gas chromatograph . ppb v, parts per billion by volume] 

Volatile organic compound

Vapor Date Date Bottom Other compounds sampler installed retrieved material Benzene TCE Toluene PCE Chlorodetected and comments name benzene (ppb v) (ppb v) (ppb v) (ppb v) (ppb v) 

V2-Cla 1-20-99 1-28-99 Organic (20) 380 (50) (30) 650 EUPs, cis-DCE 

V2-Clb 1-19-99 2- 2-99 Organic (12) 610 (40) (20) 520 EUPs, cis-DCE 

V2-Clc 1-19-99 2- 8-99 Organic (12) 990 (40) (20) 940 EUPs, cis-DCE; other unidentified 

peaks 

V2 1-19-99 2-16-99 Organic- (12) 560 (40) (20) 960 At location of V2-C1 cluster. 

very soft 

V2-C2a 1-19-99 1-28-99 Organic (12) 330 (50) (30 160 EUPs, cis-DCE 

V2-C2b 1-19-99 2- 2-99 Organic (12) 770 (50) (30) 780 EUPs, cis-DCE 

V2-C2c 1-19-99 2- 8-99 Organic (12) 690 (40) (20) 520 EUPs, cis-DCE; other unidentified 

peaks 

V7-Cla 1-19-99 1-28-99 Organic (20) 490 (50) (30) 720 EUPs, cis-DCE 

V7-Clb 1-19-99 2- 2-99 Organic 12 73 (40) (20) 610 EUPs, cis-DCE 

V7-Clc 1-19-99 2- 8-99 Organic trace 170 (40) (20) 500 EUPs, cis-DCE 

V7-C2a 1-20-99 1-28-99 Organic (20) 150 (50 (30) 52 EUPs, cis-DCE 

V7-C2b 1-19-99 2- 2-99 Organic (12) 390 (40) (20) 460 EUPs, cis-DCE 

V7-C2c 1-19-99 2- 8-99 Organic (12) 1,330 (40) 40 920 EUPs, cis-DCE 

V7-1 1-19-99 2-16-99 Organic 18 590 (40) (20) 940 EUPs, cis-DCE. Placed at location 

of V7-C2 cluster. 

Equilibration Time for Volatile Organic Compounds in Diffusion Samplers 1 1 
w 

J 

0 

m 

Z 

0 

J

J 

m 

w 

a 

n 

a 

z 

z

0 

a 

LU 

w

U

Z 

0

U 

A. SAMPLE LOCATION 02-01 

1,200 

1,000 

800 

800 

400 

200 

0 

1/25/99 1/30/99 2/4/99 2/9/99 2/14/99 2/19/99 

a. SAMPLE LOCATION 07-01 

1,400 

1,200 

1,000 

800 

800 

400 

200 CLUSTE 

0 v~ 

1/25/99 1/30/99 2/4/99 2/9/99 2/14/99 2/19/99 

Figure 5. Concentrations of chlorobenzene and 

trichloroethene detected in vapor-diffusion samplers at (A) 

sample location 02-01 and (8) sample location 07-01, 

January and February 1999, Ashland, Massachusetts . 

locations . Other factors, however, that may cause 

apparent changes in concentrations with time include 

varying river stages (fig . 3) that affect rates of groundwater flow to or from the stream, spatial variations over 

short distances, or a combination of these factors. 

Variability can also be attributed, in part, to the 

sampling and analytical methods as indicated by 

differences observed between duplicate samples at 

sampler V2a (table 2) where chlorobenzene 

concentrations were similar in the two samples but 

TCE concentrations differed by a factor of 2. Differing 

characteristics of bottom sediments (table 2) had no 

obvious effects on equilibration time. No VOCs were 

detected in trip blanks transported to the laboratory 

with cluster samples. 

The vapor- and water-diffusion pairs at the 

locations of clusters V2-C1 and V7-C2 (fig . 4) that 

were retrieved on February 16, 1999, one week after 

retrieving the last sample in each cluster of 3 vapor 

samples at the same locations, provide a fourth sample 

for comparison to samples collected previously . The 

concentration of chlorobenzene in the vapor sampler of 

each pair was about the same as the concentration in 

the last sampler retrieved, but the concentration of TCE 

decreased by about one half (table 3) . The presence of 

the water-diffusion sampler may have affected 

concentrations ofVOCs in the vapor-diffusion 

samplers for unknown reasons. Of possible 

significance was the observation that several vapordiffusion samplers were iron-stained upon retrieval, 

indicating that oxygen was diffusing from air in the 

bottles to water outside the bottles and altering the 

geochemistry of the solution locally. It is not known, 

however, if this process affected concentrations of 

VOCs in air relative to their concentrations in water. 

The possibility that pore water chemistry, 

including concentration of VOCs, was changing at 

cluster locations during the study period is supported 

by specific-conductance measurements for water from 

seepage meters on January 18 and again on February 

15-16, 1999. For example, the specific conductance 

increased from 360 to 450 ~tS/cm at seepage meter 

PW02-01 and from 910 to 1,020 gS/cm at seepage 

meter PW07-01 between measurements . By contrast, 

the specific conductance of water in the Sudbury River 

decreased from about 320 to 250 gS/cm between 

measurements (Roy F. Weston, Inc., 1999b, Appendix 

B). 

COMPARISON OF CHEMICAL 

ANALYTICAL RESULTS 

VOCs were detected in bottom sediments along 

the Sudbury River and mill raceway using vapor 

diffusion-samplers discussed above, water-diffusion 

samplers, seepage meters, and chemical analyses of the 

sediments. Each sampling method has its attributes in 

terms of ease, expense, and reliability of results. This 

section will qualitatively compare results from the four 

methods using tables and graphs . Concentrations of 

VOCs for samples collected by the four methods at 

each location are given in table 4. 

Vapor- and Water-Diffusion Samples 

When in equilibrium, the concentration ofVOCs 

in air should correlate with the concentrations in water, 

as predicted by Henry's Law. Factors that will affect 

the relation between concentrations in air and concen1 2 Tests of Diffusion Samplers for Characterizing VOCs in Sediments, Nyanza Chemical Waste Dump Superfund Site, Ashland, Mass. 
Table 4. Concentrations of volatile organic compounds in vapor-diffusion samplers, water-diffusion samplers, seepage meters, and sediments, December 1998 to 

February 1999, Nyanza Chemical Waste Dump Superfund Site, Ashland, Massachusetts 

[Data for seepage meters and sediment from R.F. Weston, Inc ., 1999 Sample type and units : PW seepage meter sample ; SD, sediment sample ; V vapor-diffusion sample ; W water-diffusion sample.


V and W samples collected on February 16, 1999 ; PW samples collected on February 15-16, 1999; SD samples collected on December 26-30, 1998 . Compound not detected at the reporting limit given in


parentheses . J, the compound was detected but near the practical quantitation limit; ns, not sampled or not analyzed ; ppb v, parts per billion by volume ; gg/kg, micrograms per kilogram ; pg/L, micrograms


per liter]


Volatile organic Sample type Sample location (fig . 1) 

compound and units 01-01 02-01 03-01 04-01 05-01 06-01 07-01 07-02 08-01 08-02 

3 

Acetone V (ppb v) ns ns ns ns ns ns ns ns ns ns 

W(gg/L) 4J (5) 5 4J 6 5J 4J 3J 6 ns 

PW (ffg/L) 4J (5) 3J 3J (5) (5) (5) (5) (5) (5 .0) 

SD (pg/kg) 9101 1,000 220J 2107 520 260 340 (240) (220) (700) 

Benzene V (ppb v) (10) (10) (10) 54 (10) (10) 18 (10) 15 (10) 

W(p g/L) (1 .0) .81 1 4 (1 .0) (1 .0) 1 (1 .0) .8J ns 

PW (pg/L) (1 .0) .6J .8J 3 (1 .0) (1 .0) 2 (1 .0) (1 .0) (1 .0) 

SD (pg/kg) (1,600) (1,000) (310) (300) (410) (240) (340) (240) (220) (700) 

2-Butanone V (ppb v) ns ns ns ns ns ns ns ns ns ns 

W ()tg/L) 4J (5) 5 (5) (,5) (5) (5) (5) (5) ns 

PW (pg/L) (5) (5) (5) (5) (5) (5) (5) (5) (5) (5) 

SD (gg/kg) (1,600) (1,000) 2607 200J (410) (240) 480 (240) (220) (700) 

Chlorobenzene V (_ppb v) (40) 960 2,250 5,330 (40) (40) 940 78 130 (40) 

W(gg/L) (1 .0) 50 120 180 (1 .0) (1 .0) 61 .8J 5 ns 

PW (p g/L) (1 .0) 38 74 140 (1 .0) .91 58 (1 .0) 2 (1 .0) 

SD (pg/kg) (310) 1,300 120 360 (82) (49) 980 (49) (45) 140) 

m Chloroform V (ppb v) ns ns ns ns ns ns ns ns ns ns 

c W(pgAL) (1 .0) (1 .0) (1 .0) (1 .0) (1 .0) (1 .0) (1 .0) (1 .0) (1 .0) ns 

c PW (pg/L) (1 .0) (1 .0) (1 .0) (1 .0) (1 .0) .6J (1 .0) (1 .0) (1 .0) (1 .0) 

0 SD (pg/kg) (310) (210) (62) (61) (82) (49) (69) (49) (45) (140) 

3 Chloromethane V (ppb v) ns ns ns ns ns ns ns ns ns ns 

m W(leg/-) (2) (2) (2) (2) (2) (2) (2) (2) (2) ns 

PW ()tg/L) (2) (2) 4 (2) (2) 9 (2) (2) (2) 4 

w SD (ltg/kg) (620) (420) (120) (120) (160) (98) (140) (98) (90) (280) 

1,1-Dichloroethene V (ppb v) ns ns ns ns ns ns ns ns ns ns 

W(gg/L) (1 .0) (1 .0) 1 1 (1 .0) (1 .0) 2 (1 .0) (1 .0) ns y

~_ PW (pg/L) (1 .0) .6J .5J 1 (1 .0) (1 .0) (1 .0) (1 .0) (1 .0) (1 .0) 

SD (pg/kg) (310) (210) (62) (61) (82) (49) (69) (49) (45) (140) i 

w 
--

Table 4. Concentrations of VOCs in vapor-diffusion samplers, water-diffusion samplers, seepage meters, and sediments, December 1998 to February 1999, 

Nyanza Chemical Waste Dump Superfund site, Ashland, Massachusetts-Continued 

Volatile organic

compound 

Sample type

and units 01-01 02-01 03-01 04-01 

Sample location (fig . 1) 

05-01 06-01 07-01 07-02 08-01 08-02 

cis-1,2-Dichloroethene V (ppb v) ns ns ns ns ns ns ns ns ns ns 

(cis-DCE) (total 1,2- W(pg/L) (2 .0) 25 70 70 (2 .0) (2 .0) 62 (2 .0) 4 ns 

Dichloroethene for 

sediment samples) 

PW (ltg/L) 

SD (gg/kg) 

(2 .0) 

(310) 

47 

230 

44 

(72) 

60 

44J 

(2 .0) (2 .0) 

(82) (49) 

67 

240 

(2 .0) 

(49) 

5 

(45) 

(2 .0) 

(140) 

trans- 1,2-Dichloroethene V (ppb v) ns ns ns ns ns ns ns ns ns ns 

W(pg/L) (2 .0) (2 .0) 11 (2 .0) (2 .0) (2 .0) 11 (2 .0) (2 .0) ns 

PW (ltg/L) (2 .0) (2 .0) (2 .0) (2 .0) (2 .0) (2 .0) 11 (2 .0) (2 .0) (2 .0) 

SD (gg/kg) ns ns ns ns ns ns ns ns ns ns 

Ethylbenzene V (ppb v) ns ns ns ns ns ns ns ns ns ns 

W( .tg/L) (1 .0) (1 .0) (1 .0) (1 .0) (1 .0) (1 .0) (1 .0) 4 (1 .0) ns 

PW (gg/L) (1 .0) (1 .0) (1 .0) (1 .0) (1 .0) (1 .0) (1 .0) (1 .0) (1 .0) 

SD (gg/kg) (1,600) (1,000) (310) (300) (410) (240) (340) (240) (220) (700) 

Tetrachloroethene (PCE) V(ppb v) (20) (20) (20) (20) (20) (20) (20) (20) (20) (20) 

W41g/L) 

PW (ggAL) 

(1 .0) 

(1 .0) 

(1 .0) 

(1 .0) 

(1 .0) 

(1 .0) 

(1 .0) 

(1 .0) 

(1 .0) (1 .0) 

(1 .0) (1 .0) 

.5J 

(1 .0) 

(1 .0) 

(1 .0) 

(1 .0) 

(1 .0) 

ns 

(1 .0) 

SD (pg/kg) (310) (1,000) (62) (61) (82) (49) (69) (49) (45) (140) 

Toluene V(ppb v) (40) (40) (40) (40) (40) (40) (40) (40) (40) (40) 

W(1tg/L) (1 .0) (1 .0) .7J .8J (1 .0) (1 .0) (1 .0) (1 .0) (1 .0) ns 

PW (pg/L) (1 .0) (1 .0) (1 .0) (1 .0) (1 .0) (1 .0) (1 .0) (1 .0) (1 .0) (1 .0) 

SD (lag/kg) (1,600) (1,000) (310) (300) (410) (240) (340) (240) (220) (700) 

Trichloroethene (TCE) V(ppb v) 18 560 1,910 430 (12) (12) 590 (12) 34 (12) 

W(ggAL) 1 5 110 11 (1 .0) (1 .0) 22 (1 .0) 4 ns 

PW (gg/L) 1 16 60 16 (1 .0) (1 .0) 35 (1 .0) 5 (1 .0) 

SD (pg/kg) (310) 240 (62) (61) (82) (49) 700 (49) (45) (140) 

Vinyl chloride V(ppb v) ns ns ns ns ns ns ns ns ns ns 

W(pgAL) (2 .0) 13 9 67 (2 .0) (2 .0) 19 (2 .0) 2 ns 

PW (pg/L) (2 .0) 6 7 58 (2 .0) (2 .0) 23 (2 .0) 3 (2.0) 

SD (pg/kg) (620) (420) (120) (120) (160) (98) (140) (98) (90) (280) 

Total Xylenes V(ppb v) ns ns ns ns ns ns ns ns ns ns 

W(ggAL) (1 .0) (1 .0) (1 .0) (1 .0) (1 .0) (1 .0) (1 .0) 29 (1 .0) ns 

PW (gg/L) (1 .0) 0.7J (1 .0) (1 .0) (1 .0) (1 .0) (1 .0) (1 .0) (1 .0) (1 .0) 

SD (jig/kg) (1,600) (1,000) (310) (300) (410) (240) (340) (240) (220) (700) 
trations in water are temperature, pressure, and molecular weight of a compound. Calculations made using 

information provided by Rathbun (1998) about Henry's 

Law constants and their variation with temperature 

indicate that TCE concentrations in air, in units ofparts 

per billion by volume, can be 20 to 30 times its concentration in water, in micrograms per liter, for a temperature range of 1°C to 10°C. For chlorobenzene, the 

concentration in air can be from 10 to 16 times its concentration in water for that same temperature range. 

Several VOCs were detected in water from 

water-diffusion samplers, but the principal compounds 

and maximum concentrations detected were for 

chlorobenzene (180 [tg/L at location 04-01), TCE 

(110 [tg/L at location 03-01), cis-DCE (70 [tg/L at 

locations 03-01 and 04-01), and vinyl chloride 

(67 [tg/L at location 04-01) (table 4). Chemical 

analyses for water included a larger number of 

chemicals than the 5 target compounds for vapordiffusion samples. Table 4 reports all of the VOCs that 

were detected in the water-diffusion samples. In 

general, the target compounds detected in vapor 

samples were consistent with compounds detected in 

water samples at each sampling location. Exceptions 

were benzene, which was detected in vapor samples at 

only three of the five locations where it was detected in 

water samples, and toluene, which was detected at low 

concentrations (less than 1 itg/L) at two locations 

(03-01 and 04-01) in water samples but not in vapor 

samples at the same locations. 

Figure 6 shows the relation of concentrations in 

vapor to concentrations in water at vapor- and waterdiffusion sampler pairs for chlorobenzene and TCE, the 

major compounds detected in vapor and water. Also 

shown is the range of concentrations that might be 

expected on the basis of Henry's Law, assuming a 

temperature range of 1°C to 10° C and samples 

collected at atmospheric pressure . The temperature 

range from 1°C to 10°C represents a possible range 

during the study period from near 0°C at times in 

surface water to a maximum of 10°C in ground water. 

Although a fair correlation is apparent for the two types 

of samples, deviations from concentrations predicted 

by Henry's Law indicate that either the vapor samples, 

water samples, or both, had not equilibrated with 

sediment pore water. Uncertainties in chemical 

analytical results could also affect the apparent relation 

between concentrations in air and concentrations in 

water. 

A. CHLOROBENZENE 

200 

180 

160 

140 

120 W

F

J 100 

Q W 80

a 60 

40 

°0 20 

z 

F B. TRICHLOROETHENE 

120 z 

z


0 100


F


F 80
 2


W


U


z 60


0


0


40 

20 

0 

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

CONCENTRATION IN VAPOR, IN PARTS 

PER BILLION BY VOLUME 

Figure 6. Concentrations of (A) chlorobenzene and (8) trichloroethene in vapor- and water-diffusion samplers,

February 16, 1999, Ashland, Massachusetts. 

Water-Diffusion Samples and SeepageMeter Samples 

Results of chemical analyses of water samples 

extracted from seepage meters (Roy F. Weston, Inc., 

1999b) are included in table 4 for comparison to results 

from water-diffusion samplers. In general, the principal 

compounds detected by the two methods are consistent, 

and concentrations for the major constituents are 

similar, as shown in figure 7. At concentrations of 

individual constituents greater than about 50 Rg/L, the 

concentrations in water-diffusion samples were 

generally higher than concentrations in seepage-meter 

samples. This indicates that analyses of water from 

seepage meters may have underestimated 

concentrations in pore water. If the water-diffusion 

samplers had not fully equilibrated, as discussed above, 

then both methods may underestimate actual 

concentrations in pore water, at least at the higher 

concentrations . 

Comparison of Chemical Analytical Results 15 
160 

w W 140


I- i-


W J


:~ CC 120 

W CC Z C7 80


-O


Z CC


02 60


QMZ_ 

Z u.i 

40 

W J 

_

O 20 

DQ 

0 

VINYL CHLORIDE 

Cis1,2-DICHLOROETHENE 

TRICHLOROETHENE 

CHLOROBENZENE 

50 

CONCENTRATION IN WATER-DIFFUSION SAMPLE, IN MICROGRAMS PER LITER 

Figure 7. Concentrations of selected volatile organic compounds detected in water-diffusion samplers and 

concentrations in water from seepage meters, Ashland, Massachusetts. 

Several compounds that were present near the 

detection limit in some diffusion samplers were not 

detected in nearby seepage meters, and some 

compounds were detected in seepage meters but not in 

diffusion samplers . Compounds that were present in 

concentrations appreciably above the detection limit 

were total xylenes, which were detected in diffusion 

sampler W7-2 but not in the nearby seepage meter, and 

chloromethane, detected in water from seepage meters 

PW03-01 and PW06-01 but not in nearby diffusion 

samplers. No patterns that might be related to the 

sampling method were apparent. Differences in 

compounds detected and concentrations may be 

attributable, in part, to variations in plume chemistry 

over distances of several feet between the seepage 

meters and diffusion samplers . 

Water-Diffusion Samples and 

Sediment Samples 

Results of chemical analyses of sediment 

samples collected at the locations of seepage meters 

(Roy F. Weston, Inc., 1999b) are included in table 4 for 

comparison to results from other sampling methods. In 

general, the principal VOCs detected in sediment are 

consistent with those detected in water-diffusion 

samplers (and water from seepage meters as discussed 

above) . Examination of concentrations reported in 

table 4 [accounting for different units for the two types 

of samples ([ug/L for water and mg/kg for sediment)], 

however, indicate a poor correlation for the two 

methods. At several locations, such as 01-01, 03-01, 

04-01, and 08-01, TCE was present in water-diffusion 

samples but was not detected in sediment samples. 

Other compounds that were detected in water-diffusion 

samples but not in sediment included vinyl chloride, 

1,1,-dichloroethene, and benzene. The apparent 

absence of some compounds in sediments may result 

from relatively high quantitation limits for the sediment 

analyses and a shallower sampling depth (6 in. or less) 

than the depths of the water-diffusion samplers (6 to 

8 in .) . These results indicate that the other three 

sampling methods yielded a better representation of the 

VOCs present in sediments than chemical analyses of 

the sediments. Concentrations of total organic carbon 

at the sampling locations considered here ranged from 

4,900 to 116,000 mg/kg (Roy F. Weston, Inc., 1999b) . 

The relative concentration of VOCs in water samples 

and sediment samples are not obviously affected by the 

concentration of total organic carbon in sediment, 

although this possibility cannot be thoroughly assessed 

with the limited data available. 

16 Tests of Diffusion Samplers for Characterizing VOCs in Sediments, Nyanza Chemical Waste Dump Superfund Site, Ashland, Mass. 
USE OF DIFFUSION SAMPLERS AS 

RECONNAISSANCE TOOLS 

This study has reaffirmed that vapor-diffusion 

samplers placed in bottom sediments are useful 

reconnaissance tools for determining the distribution of 

VOCs in ground water and variations in concentrations 

across the width of a contaminant plume that 

discharges to a surface-water body. Others who have 

demonstrated uses of vapor-diffusion samplers for this 

purpose include Vroblesky and others (1996), Savoie 

and others (1999), and Lyford and others (1999) . 

Sampling results can also provide useful information 

about ground-water flow patterns . For example, the 

vapor samplers used for this study, although few in 

number, confirmed a likely losing reach in the 

downstream end of the mill pond and indicated 

minimal discharge of contaminants to the Sudbury 

River downstream from the dam. This scenario differs 

from a previous conceptual model of contaminant 

movement that showed the plume of contaminants 

extending to the Sudbury River (fig . 2). Although 

beyond the scope of this study, a network of vapordiffusion samplers placed within the mill pond area 

might have identified discharge points for ground water 

that contained higher concentrations of VOCs, 

consistent with concentrations in deep ground water, 

than those apparent near the shore. Networks of vapordiffusion samplers have been used to delineate groundwater discharge areas and flow patterns near ponds on 

Cape Cod (D.R. LeBlanc, U.S . Geological Survey, oral 

commun., 1999). Diffusion samplers may have 

limitations where VOCs are present in surface water, 

because the source of VOCs could be either surface 

water or ground water. 

Experience at the Nyanza site and other sites in 

New England has demonstrated that one person can 

construct as many as 100 samplers per day, and a crew 

of 3 can install 50 to 150 samplers per day; these totals 

depend somewhat on ease of access to, the study area 

and character of the bottom sediments. Retrieval times 

and personnel requirements are less for retrieval than 

for installation . An analyst using a gas chromatograph 

can analyze about 50 vapor samples in a day. 

Therefore, a considerable amount of information can 

be generated in a short time relative to other sampling 

methods. 

Comparison ofVOCs in vapor-diffusion 

samplers to VOCs in adjacent water-diffusion samplers 

indicates that different equilibration times after 

emplacement might limit the use of either method for 

reliably determining actual concentrations of VOCs in 

pore water. At present, the equilibration times for various types of bottom materials and various hydrologic 

conditions are not well defined. Other factors that 

might affect concentrations and interpretation of results 

are time-varying hydrologic conditions that affect the 

flux of contaminated ground water to streams, variations in concentrations over short distances, and 

exchanges between ground water and surface water 

in the hyporheic zone, which is the subsurface zone 

where stream water flows through short segments of its 

adjacent beds and banks (Winter and others, 1998). 

The results of this study indicates that waterdiffusion samplers are a viable alternative to seepage 

meters for identifying the types of VOCS that are 

present in bottom sediments. Awater-diffusion sampler 

can be constructed, installed, and retrieved in a total 

time of an hour or less . This contrasts with a time of 

several hours for installation and sampling of seepage 

meters . Seepage meters or other techniques for 

sampling pore water, however, are needed to determine 

concentrations of other contaminants such as metals or 

SVOCs in bottom sediments. 

Elevated concentrations of SVOCs and metals in 

ground water near the Nyanza site are associated with 

elevated concentrations of VOCs (Roy F. Weston, Inc., 

1998). This condition is commonly observed at 

contaminated sites. In areas where VOCs are indicators 

of other contaminants in ground water, vapor-diffusion 

samplers can quickly and economically identify "hot 

spots" and guide the sampling of bottom sediments for 

other contaminants . 

Vapor- and water-diffusion samplers may be 

useful for assessing geochemical processes such as 

biodegradation in bottom sediments. For example, 

results from water-diffusion samplers and seepage 

meters identified elevated concentrations of vinyl 

chloride (9 to 67 p,g/L in water-diffusion samples) at 

four locations. Concentrations of vinyl chloride in 

water from wells near the river and raceway where 

ground water is discharging to surface water, however, 

are generally less than 2 p,g/L. This concentration 

pattern indicates possible transformation of TCE by 

biodegradation as ground water moves upward through 

the organic-rich bottom sediments toward surface 

water. Biodegradation of chlorinated VOCs as ground 

water flows vertically upward through wetland 

sediment has been described by Lorah and Olsen 

(1999) . Anetwork of vapor- or water-diffusion 

Use of Diffusion Samplers as Reconnaissance Tools 1 7 
samplers could be useful for identifying active areas of 

biodegradation for chlorinated VOCs. Networks of 

vapor-diffusion samplers may also be useful for 

studying patterns of exchanges between surface water 

and ground water in the hyporheic zone, where VOCs 

are known to be discharging from ground water to 

surface water. 

Because results from this study and studies in 

other New England settings have confirmed the value 

of vapor-diffusion samplers as simple and economical 

reconnaissance tools, further testing for this purpose is 

not warranted. If a goal is to determine actual 

concentrations of VOCs at the interface between 

ground water and surface water, however, additional 

studies are needed to evaluate equilibration times in 

various geohydrologic settings. Also needed to 

accomplish this goal is a better understanding of 

variations in concentrations over short distances of a 

few feet and possible changes in concentrations with 

changing hydrologic conditions . Networks of closelyspaced vapor samplers retrieved and analyzed over an 

extended time in several geohydrologic settings could 

provide useful insights on spatial and temporal 

variability. 

SUMMARY 

Polyethylene-membrane water-to-vapor (vapor) 

and water-to-water (water) diffusion samplers were 

installed during a pilot study in January 1999 in bottom 

sediments along the Sudbury River and former mill 

raceway to determine if vapor samplers would be 

useful in this setting for delineating a plume of 

contaminants in ground water near the river and 

raceway, to evaluate equilibration time for vapordiffusion samplers, and to determine if diffusion 

samplers might be an alternative to seepage meters 

(inverted steel drums) and sediment sampling for 

evaluating concentrations of VOCs in bottom 

sediments. 

VOCs were detected in all but 5 of 21 vapordiffusion samplers (excluding samples from clusters 

and duplicate samples). Of 5 tested compounds 

benzene, trichloroethene, toluene, tetrachloroethene, 

and chlorobenzene-chlorobenzene and 

trichloroethene were detected most frequently. The 

distribution of VOCs was generally consistent with the 

mapped plume of contaminants in ground water. The 

absence of VOCs in the downstream part of the mill 

pond was consistent with water-level well data, which 

indicated that water was leaking from the pond to the 

surficial aquifer in this area. The general absence of 

VOCs along the Sudbury River downstream from the 

dam indicated that the discharge ofVOCs to the river 

was limited at the time of the study. Result from the 

experiment to evaluate equilibration times for vapordiffusion samplers were inconclusive because of 

changing hydrologic conditions that may have affected 

concentrations of VOCs, possible variations in 

concentrations of VOCs over short distances, and 

imprecise sampling and analytical methods. The 

limited data from this study, however, indicated that 

equilibration times may exceed 3 weeks in some 

settings. 

Analyses of water from water-diffusion samplers 

included a larger suite of chemicals than analyses for 

vapor from vapor-diffusion samplers. The principal 

compounds and maximum concentrations detected 

in water-diffusion samplers were chlorobenzene 

(180 pg/L), trichloroethene (110 Rg1L), cis 1,2-

dichloroethene (70 gg/L), and vinyl chloride (67 gg/L). 

Highest concentrations of TCE and chlorobenzene in 

water samples were found at the same locations as the 

highest concentrations detected in vapor samples. 

Concentrations of chlorobenzene and TCE detected in 

vapor-diffusion samplers generally correlated with 

concentrations detected in water-diffusion samplers. 

Also, the VOCs and concentrations detected in waterdiffusion samplers were generally consistent with those 

detected in water from seepage meters . 

Results from this pilot study reaffirm results 

from previous studies that diffusion samplers are a 

simple and economical means of identifying "hot 

spots" for contaminants in bottom sediments, and can 

provide insights on pathways for contaminants near 

surface-water bodies . Diffusion samplers may also be 

useful for studying variations in concentrations of 

VOCs across short distances, variations with time and 

changing hydrologic conditions, and processes such as 

chemical transformations and exchanges between 

surface water and ground water in the hyporheic zone. 

1 8 Tests of Diffusion Samplers for Characterizing VOCs in Sediments, Nyanza Chemical Waste Dump Superfund Site, Ashland, Mass. 
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degradation : Water Resources Research, v. 35, no. 12, 

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