USGS - science for a changing world

Environmental Health - Toxic Substances

Toxics Program Remediation Activities

Delineating Discharge Areas of Contaminant Plumes with Diffusion Samplers

Type Site Characterization
Location Johns Pond, Cape Cod, Massachusetts
Partners
Technology Passive-Vapor-Diffusion Samplers
Contaminants
  • Chlorinated Solvents (Volatile organic compounds VOCs)
    • Trichloroethene (TCE)
    • Tetrachloroethene (PCE)
Description

USGS scientists and their partners tested the use of passive-vapor-diffusion samplers to characterize and delineate the discharge area of a plume of volatile organic compounds (VOCs) discharging into Johns Pond, Cape Cod, Massachusetts. Passive-vapor-diffusion samplers are empty glass vials placed inside of two layers of polyethylene membrane tubing. When placed in contaminated sediments, the air in the vial equilibrates with the VOCs in the pore water of the sediments. The VOCs contained in the air of the vial indicate the presence and likely magnitude of VOCs in sediments. Common everyday zipper-locking polyethylene bags available at grocery stores can be used instead of the polyethylene tubing.

The objective of the test was to confirm that VOCs contained in the Massachusetts Military Reservation's Storm Drain-5 (SD-5) plume were discharging into Johns Pond from the bottom of the pond. USGS scientists placed and retrieved samplers at 267 locations along several lines in the sediments of Johns Pond at three different times. Scuba divers buried each of the samplers about half a foot into the pond-bottom sediments. The samplers were allowed to equilibrate for two weeks before they were retrieved. The scientists unexpectedly detected a localized spot of higher concentrations of VOCs separate from the other grouping of contaminants nearby. Further investigations revealed that a previously unidentified plume of trichloroethene (TCE) was responsible for the spot of high TCE concentrations. The newly discovered plume is a branch of another plume (CS-10) that emanated from an abandoned missile site on the military base more than 3 miles from the pond.

The new passive-vapor-diffusion samplers are potentially an inexpensive and effective method to locate discharge areas of contaminated ground water in streams and ponds. A newly released USGS report prepared in cooperation with the U.S. Environmental Protection Agency provides guidance on the use of the diffusion samplers.

Ashument pond
View of Massachusetts Military Reservation and Ashumet Pond. Johns Pond is in lower right corner.
(Click on photo for larger version)
Adding the diffusion samplers on a line
Connecting diffusion samplers to a line before placement in pond sediments.
(Click on photo for larger version)
Map of the SD5 area
Map of the extent of discharge for storm drain-5 (SD-5) plume in Johns Pond, Massachusetts. Contour lines are TCE concentrations in parts per billion (ppb). Note the TCE "hot spot" separate from the main discharge area. Further investigations showed that the "hot spot" was from another plume.
(Click on photo for larger version)
Map of subsurface plumes
Map of the extent of discharge for storm drain-5 (SD-5) plume in Johns Pond, Massachusetts. Contour lines are TCE concentrations in parts per billion (ppb). Note the TCE "hot spot" separate from the main discharge area. Further investigations showed that the "hot spot" was from another plume.
(Click on photo for larger version)
More Information
Contact
  • Jennifer Savoie, USGS, Northborough, MA,
  • Denis R. LeBlanc, USGS, Northborough, MA,
Publications
 
Links

Other Toxics Remediation Studies on Cape Cod

Information on Ground-Water Contamination on Cape Cod

Information on Site Characterization

Back to Toxics Program Remediation Activities Index

USGS Home Water Climate Change Science Systems Ecosystems Energy and Minerals Environmental Health Hazards

Accessibility FOIA Privacy Policies and Notices

Take Pride in America logo USA.gov logo U.S. Department of the Interior | U.S. Geological Survey
URL: http://toxics.usgs.gov/topics/rem_act/contaminant_plumes.html
Page Contact Information:
Page Last Modified: Tuesday, 30-Jul-2013 12:27:36 EDT