From Ground Water Currents, June 1996, Issue No. 15

Issues: The EPA Regional Ground Water Forum

The EPA Regional Ground Water Forum is a group of EPA professionals representing Regional Superfund and Resource Conservation and Recovery Act Offices committed to the identification and resolution of ground water issues impacting the remediation of Superfund and RCRA sites. The Forum has three GROUND WATER ISSUE publications of interest to the readers of GROUND WATER CURRENTS related to nonaqueous phase liquids (NAPLs) and low-flow sampling. All of these publications can be ordered by calling the Center for Environmental Information (CERI) at 513-569-7562 and referring to the Document Numbers (given below).

"Nonaqueous Phase Liquids Compatibility with Materials Used in Well Construction, Sampling and Remediation" (Document No. EPA/540/S-95/503) provides a comprehensive literature review regarding the compatibility of NAPLs with a wide variety of materials used at hazardous waste sites. A condensed reference table of compatibility data for 207 chemicals and 28 commonly used well construction and sampling equipment materials is provided. Field experiences illustrating incompatibility problems of common wastes are also included. This will assist monitoring and recovery system design personnel with the decision making process concerning the most effective materials to be used in heavily contaminated subsurface environments.

"Light Nonaqueous Phase Liquids" (Document No. EPA/540/S-95/500) contains a discussion of LNAPL transport. It addresses LNAPL transport through porous media and transport parameters such as density, viscosity, interfacial tension, wettability, capillary pressure, saturation and residual saturation and relative permeability. LNAPL migration at the field scale is discussed, including Darcy's Law, field scale versus pore scale, migration through the vadose zone, accumulation at the water table, smearing due to fluctuating water table, migration in fractured media and migration through man-made pathways. The publication also addresses the fate of LNAPLs in the subsurface, site characterization, LNAPL characteristics, sampling and remedi-ation. Extensive references are provided.

"Low-Flow (Minimal Drawdown) Ground-Water Sampling Procedures" (Document No.EPA/540/S-95/504) is intended to provide background information on the development of low-flow sampling procedures and its application under a variety of hydro-geologic settings. It is hoped that the paper will support the production of standard operating procedures for use by EPA regional personnel and other environmental professionals engaged in ground water sampling. It addresses monitoring objectives and design considerations, definition of low-flow purging and sampling, low-flow (minimal drawdown) sampling protocols, low-permeability formations and fractured rock and contains a list of scientific/technical references.