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EPA GROUND WATER ISSUE: Ground Water Sample Preservation at ISCO Sites – Recommended Guidelines
Citation:
HULING, S. G., S. Ko, AND B. Pivetz. EPA GROUND WATER ISSUE: Ground Water Sample Preservation at ISCO Sites – Recommended Guidelines. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-12/049, 2011.
Impact/Purpose:
Ground water issue paper on guidelines for sample preservation at ISCO sites
Description:
In-situ chemical oxidation (ISCO) involves the introduction of a chemical oxidant into the subsurface for the purpose of transforming ground water contaminants into harmless byproducts. Due to oxidant persistence, ground water samples collected at hazardous waste sites may contain both the contaminant(s) and the oxidant in a “binary mixture”. Detailed laboratory studies have been conducted involving the analysis of binary mixtures containing volatile organic compounds (VOCs), including but not limited to benzene, toluene, m-xylene, perchloroethylene, and trichloroethylene. In these samples, significant loss in VOC concentrations was measured using gas chromatography (GC) purge and trap, and GC mass spectroscopy headspace methods. Preservation of aqueous binary mixture samples can be achieved through the addition of ascorbic acid. High concentrations of ascorbic acid did not interfere in the measurement of the VOCs, and did not negatively impact the analytical instruments. This Ground Water Forum Issue Paper is intended to provide background information and general guidelines in the preservation of ground water samples at ISCO sites where permanganate or persulfate have been used. These guidelines are intended to support the production of standard operating procedures for use by EPA Regional personnel and other environmental professionals engaged in ground-water sampling.