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Diffusion and Drive-Point Sampling to Detect Ordnance-Related Compounds in Shallow Ground Water Beneath Snake Pond, Cape Cod, Massachusetts, 2001-02

Water-Resources Investigations Report 03-4133

By Denis R. Leblanc

ABSTRACT

Diffusion samplers and temporary drive points were used to test for ordnance-related compounds in ground water discharging to Snake Pond near Camp Edwards at the Massachusetts Military Reservation, Cape Cod, MA. The contamination resulted from artillery use and weapons testing at various ranges upgradient of the pond.The diffusion samplers were constructed with a high-grade cellulose membrane that allowed diffusion of explosive compounds, such as RDX (Hexahydro-1,3,5-trinitro-1,3,5-triazine) and HMX (Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine), into deionized water inside the samplers. Laboratory tests confirmed that the cellulose membrane was permeable to RDX and HMX. One transect of 22 diffusion samplers was installed and retrieved in August-September 2001, and 12 transects with a total of 108 samplers were installed and retrieved in September-October 2001. 

The diffusion samplers were buried about 0.5 feet into the pond-bottom sediments by scuba divers and allowed to equilibrate with the ground water beneath the pond bottom for 13 to 27 days before retrieval. Water samples were collected from temporary well points driven about 2-4 feet into the pond bottom at 21 sites in December 2001 and March 2002 for analysis of explosives and perchlorate to confirm the diffusion-sampling results.

The water samples from the diffusion samplers exhibited numerous chromatographic peaks, but evaluation of the photo-diode-array spectra indicated that most of the peaks did not represent the target compounds. The peaks probably are associated with natural organic compounds present in the soft, organically enriched pond-bottom sediments. The presence of four explosive compounds at five widely spaced sites was confirmed by the photo-diode-array analysis, but the compounds are not generally found in contaminated ground water near the ranges. No explosives were detected in water samples obtained from the drive points. Perchlorate was detected at less than 1 microgram per liter in two drive-point samples collected at the same site on two dates about 3 months apart. The source of the perchlorate in the samples could not be related directly to other contamination from Camp Edwards with the available information.

The results from the diffusion and drive-point sampling do not indicate an area of ground-water discharge with concentrations of the ordnance-related compounds that are sufficiently elevated to be detected by these sampling methods. The diffusion and drive-point sampling data cannot be interpreted further without additional information concerning the pattern of ground-water flow at Snake Pond and the distributions of RDX, HMX, and perchlorate in ground water in the aquifer near the pond.

CONTENTS

Abstract
Introduction
Acknowledgments
Field Investigation and Results
Diffusion-Sampler Design
Laboratory Test of Diffusion Samplers
Diffusion Sampling of Ground Water
August–September 2001 Transect
September–October 2001 Transects
Drive-Point Sampling of Ground Water

Ordnance-Related Compounds in Shallow Ground Water Beneath Snake Pond
Summary
References Cited

FIGURES

  1. Map showing locations of Camp Edwards military ranges, Snake Pond, test borings with validated detections of explosives and perchlorate, and altitude of the water table, Cape Cod, Massachusetts, 2001–02
  2. Photograph of diffusion sampler showing inner core, slip-on end caps, cellulose membrane, and outer mesh<
3-5. Maps showing:
  1. Locations of diffusion samplers set in the bottom sediments of Snake Pond, August–October 2001
  2. Locations of validated detections of ordnance-related compounds in diffusion and drive-point water samples collected from bottom sediments of Snake Pond, August 2001-March 2002
  3. Locations of temporary drive points installed in the bottom sediments of Snake Pond, December 2001 and March 2002

TABLES

  1. Results of laboratory tests of prototype diffusion samplers constructed of tubular cellulose membranes, July 2001
  2. Locations, site identifiers, and installation and retrieval dates of diffusion samplers set in the bottom sediments of Snake Pond, Cape Cod, Massachusetts, August–October 2001
  3. Target chemical compounds included in analysis of diffusion and drive-point ground-water samples collected beneath Snake Pond
  4. Validated detections of ordnance-related compounds in diffusion and drive-point samples collected from the pond-bottom sediments of Snake Pond, August 2001–March 2002
  5. Locations, site identifiers, sampling depths and dates, and specific conductance of water samples collected from a temporary well point driven into the bottom sediments of Snake Pond, December 2001 and March 2002

AVAILABILITY

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PDF version of report: (5.2 MB) --25 pages

The citation for this report, in USGS format, is as follows:

Leblanc, D. R., 2003, Diffusion and Drive-Point Sampling to Detect Ordnance-Related Compounds in Shallow Ground Water Beneath Snake Pond, Cape Cod, Massachusetts, 2001-02: U.S. Geological Survey Water-Resources Investigations Report 03-4133, 25 p.

For more information about USGS activities in Massachusetts-Rhode Island District, visit the USGS Massachusetts-Rhode Island Home Page



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