Groundwater contaminant detection

Lappala, E. and G. Thompson. Detection of Groundwater Contamination by Shallow Soil Gas Sampling in the Vadose Zone and Applications. In Management of Uncontrolled Hazardous Waste Sites Proceedings, Hazardous Materials Control Research Institute,Washington, D.C., 1984. 

A possible source for much of the groundwater contamination is landfill leachate containing trichloroethylene. Trichloroethylene was the most commonly found chemical at NPL sites in New York State (Mumtaz et al. 1994). The compound was detected in leachate samples from Minnesota municipal solid waste landfills at levels ranging from 0.7 to 125 pg/L (0.7-125 ppb) and in groundwater near landfills at levels ranging from 0.2 to 144 pg/L (0.2-144 ppb) (Sabel and Clark 1984). Trichloroethylene was also detected in landfill leachate from a landfill in New Jersey at concentrations of up to 7,700 pg/L (7,700 ppb) (Kosson et al. 

The monoaromatic compounds benzene, toluene, ethylbenzene and xylene, commonly found in crude oil, are often jointly called BTEX compounds. The most harmful of these compounds is benzene, which is a known carcinogen. BTEX compounds occur naturally near natural gas and petroleum deposits and are detected in the fumes of forest fires. Most of the highly volatile BTEX compounds released by human activity originate from fuel use and end up as pollutants in the air. Inhaling BTEX-polluted air is also the greatest hazard to humans by these compounds. BTEX compounds are water-soluble, and therefore, improper handling can also cause groundwater contamination. 

As a result of these sampling efforts two locations (Bruno, Nebraska and Waverly, Nebraska were placed on EPA s National Priorities List (NPL) for clean-up of carbon tetrachloride contamination. The EPA entered into an Administrative Order on Consent with USDA for the groundwater contamination at Murdock, Nebraska. All locations that had detections that exceeded the drinking water standard were provided alternate sources of drinking water (i.e., bottled water, connection to public water supply). 

Neumayr [3] carried out soil atmosphere studies using capillary gas chromatography and electron capture and flame ionization sequential detection and used this as a means of pinpointing zones of soil and groundwater contamination. 

Groundwater contamination by agrochemicals from non-point sources has been well documented in a number of countries [26-28, 30-32], The pesticides that have been detected in regional council groundwater surveys include 2,4-D, Amitrole, Picloram, Simazine and Atrazine [20]. 

Pfannkuch, H. O., 1984, Determination of the Contamination Source Strength from Mass Exchange Processes at the Petroleum-Groundwater Interface in Shallow Aquifer Systems In Proceedings of the National Water Well Association and American Petroleum Institute Conference on Petroleum Hydrocarbons and Organic Chemicals in Groundwater — Prevention, Detection and Restoration, November, Houston, TX. 

Free-phase NAPL refers to NAPL that exists as an independent phase, not as a dissolved component in the pore water or pore atmosphere. The environmental concerns associated with sites affected with free-phase NAPLs revolve around hydrocarbon-impacted soil (residual hydrocarbon), the NAPL itself (which can serve as a continued source for groundwater contamination), dissolved hydrocarbon constituents in groundwater, and hydrocarbon vapors. The detection of free-phase NAPLs in the subsurface presents many challenges. Two questions frequently arise at sites impacted by NAPLs how much is there and how long will it take to clean up. Before one can address these two questions, assessments of the type and subsurface distri-... 

Improvements in analytical technology to identify groundwater contaminants revealed that soil gas analysis may enhance the effectiveness of traditional sampling and analysis (Kerfoot 1990). Carbon tetrachloride has properties that make it amendable to detection by soil gas analysis. 

Kerfoot FIB. 1990. Soil-gas surveys for detection and delineation of groundwater contamination. Trends in Analytical Chemistry 9 157-163. 

The Office of Technology Assessment reported that incidences of groundwater contamination have been found in every state and tliat a number of organic and inorganic chemicals were detected in various groundwater supplies (Thompson, 1986). Many of these contaminants are known toxins and carcinogens. 

Ethylbenzene was listed as one of the 58 most frequently detected chemicals associated with groundwater contamination in the United States. It was detected in over 4% of the surface water samples and 11% of the groundwater samples analysed at the 1177 National Priority List (NPL) sites (Agency for Toxic Substances and Disease Registry, 1997a). 

In a groundwater contamination study of 28 of California s 58 counties that evaluated over 50 pesticides (from both point and nonpoint sources), diazinon was detected in 12 samples (Cohen 1986). Diazinon is included as an analyte of interest in the EPA Pesticides in Ground Water Database (EPA 1989a) and was... 

Table 1. Degradability ofhalogenated organic compounds in the presence ofzerovalent iron (Adapted from Gavaskar etal., 1998 and EPA, 1998). Compounds indicated in bold face are among the 25 most frequently detected groundwater contaminants at hazardous waste sites (NRC, 1994). ...

Kerfoot, El. B. (1987). Soil-gas measurement for detection of groundwater contamination by volatile organic compounds. Environmental Science and Technology, 21, 1022-1024. 

Recent field evidence indicates that the occurrence of these reaction products may be relatively common in hypoxic groundwaters which have been contaminated by bromoaliphatic compounds. Schwarzenbach et al. (1) reported the presence of a complex mixture of alkyl and chloroalkyl sulfides in a hypoxic groundwater polluted by a variety of bromo- and chloroaliphatic compounds. Ethanethiol (at a concentration of approximately 2 pM) was detected by Jackson et al. (5Q) in groundwater contaminated by a variety of chlorinated and brominated solvents beneath a municipal/industrial landfill. In addition, Watts and Brown (51 cited in 2) have reported the presence of ethanethiol, diethyl disulfide and triethyl disulfide in Florida groundwaters contaminated by 1,2-dibromoethane. 

Chudyk WA, Carrabba MM, Kenney JE. 1985. Remote detection of groundwater contaminants using far-ultraviolet laser-induced fluorescence. Anal Chem 57 1237-1242. 

The project will also secure the groundwater system to reduce the impact of operations on the hydrologic system. Wherever groundwater contamination is detected, stations will be installed locally to pump and send polluted water to treatment plants. 

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