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| MD-DE-DC Water Science Center |
U.S. GEOLOGICAL SURVEY
Open-File Report 01-292
The purpose of this report is to describe the occurrence and distribution of volatile organic compounds in surface-water samples collected by the U.S. Geological Survey in the Canal Creek area of Aberdeen Proving Ground, Maryland, from November 1999 through September 2000. The report describes the differences between years with below normal and normal precipitation, the effects of seasons, tide stages, and location on volatile organic compound concentrations in surface water, and provides estimates of volatile organic concentration loads to the tidal Gunpowder River. Eighty-four environmental samples from 20 surface-water sites were analyzed. As many as 13 different volatile organic compounds were detected in the samples. Concentrations of volatile organic compounds in surface-water samples ranged from below the reporting limit of 0.5 micrograms per liter to a maximum of 50.2 micrograms per liter for chloroform.
Chloroform was detected most frequently, and was found in 55 percent of the environmental samples that were analyzed for volatile organic compounds (46 of 84 samples). Carbon tetrachloride was detected in 56 percent of the surface-water samples in the tidal part of the creek (34 of 61 samples), but was only detected in 3 of 23 samples in the nontidal part of the creek. 1,1,2,2-Tetrachloroethane was detected in 43 percent of the tidal samples (26 of 61 samples), but was detected at only two nontidal sites and only during November 1999. Three samples were collected from the tidal Gunpowder River about 300 feet from the mouth of Canal Creek in May 2000, and none of the samples contained volatile organic compound concentrations above detection levels. Volatile organic compound concentrations in surface water were highest in the reaches of the creek adjacent to the areas with the highest known levels of ground-water contamination. The load of total volatile organic compounds from Canal Creek to the Gunpowder River is approximately 1.85 pounds per day (0.84 kilograms per day), or 674 pounds per year.
Volatile organic compounds that reach the Gunpowder River become substantially diluted. Although natural-attenuation processes in the study area such as biodegradation are highly effective at reducing contaminant concentration in ground water before it discharges to the creek, natural attenuation is not 100 percent effective at all locations or under all tidal, seasonal, and climatic conditions as indicated by detection of volatile organic compounds in Canal Creek.
Abstract
Introduction
Purpose and scope
Previous investigations
Description of study area
Hydrogeologic setting
Ground water
Surface water
West Branch Canal Creek discharge at Magnolia Road gaging station
Acknowledgments
Methods of investigation
Inorganic analyses
Organic analyses
Water-quality data
Inorganic water-quality data
Organic water-quality data
Quality assurance of volatile organic compound data
Field blanks
Trip blanks
Field replicates
Matrix spikes
Assessment of volatile organic compounds in surface water
Distribution of total volatile organic compounds
Comparison of samples collected in 1999 and 2000
Comparison of samples collected during different seasons
Comparison of samples collected during different tide stages
Comparison of samples collected at different locations
Distribution of individual volatile organic compounds
Chloroform
Carbon tetrachloride
1,1,2,2-Tetrachloroethane
Estimated volatile organic compound load to the Gunpowder River
Estimated volatile organic compound concentrations
Estimated discharge volume
Load calculation
Summary and conclusions
Selected references
Appendixes
A. Graphs showing daily rainfall totals at Aberdeen Proving Ground, and tidal fluctuations at the
Hanlon Road tide gage, West Branch Canal Creek, Aberdeen Proving Ground, Maryland,
October 1, 1998 to September 30, 2000
B. Organic constituents in surface-water samples from the Canal Creek area,
Aberdeen Proving Ground, Maryland, November 1999 through September 2000
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For more information about USGS activities in Maryland, Delaware and the District of Columbia contact:
Director
MD-DE-DC Water Science Center
U.S. Geological Survey
8987 Yellow Brick Road
Baltimore, MD 21237
Telephone: (410) 238-4200
Fax: (410) 238-4210
or access the USGS Water Resources of Maryland, Delaware, and District of Columbia home page at: http://md.water.usgs.gov/.
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