ARCHIVED REPORTS_XR0002669 - Laserfiche WebLink

Home Browse Search

Groundwater cleanup levels are approved on a case-by-case basis by the Board. Proposed final cleanup levels are based on a discharger-developed feasibility study of cleanup alternatives that compares effectiveness, cost, time to achieve cleanup standards, and a risk assessment to determine impacts on beneficial uses, human health and the environment. Cleanup levels must also take into account the mobility, toxicity, end volume of pollutants. Feasibility studies of cleanup alternatives may include the guidance provided by Subpart E of the National Oil and Hazardous Substances Pollution Contingency Plan (40 CFR 300); Section 25356.1(c)of the California Health and Safety Code; U.S. EPA's Comprehensive Environmental Response, Compensation, and Liability Act; the State Water Board's Resolutions Nos. 68-16 and 92-49; and the Regional Water Board's Resolution No. 88-160. 25. Final cleanup levels for polluted groundwater shall be background water quality if feasible, but shall not be greater than the California (State) DHS drinking water Action Level (AL) or Maximum Contaminant Level (MCL), whichever as more stringent An AL does not apply if an MCL has been adopted for the chemical pollutant - 26. The Federal EPA has adopted Maximum Contaminant Levels MCLS for pollutants, and the State and Federal MCLS are not always identical. The Federal EPA has also adopted Maximum Contaminant Level Goals (MCLGs) for certain chemicals, which may be lower than the Federal MCLs. Groundwater cleanup standards for the site are the more stringent of the Federal or State MCLS. The current Federal and State MCLs/MCLGs for VOCs of interest, and the appropriate MCL for this site, are tabulated below, in Table 1. Table l: MCLS for VOCs of Interest (ug/l) ` k Chemical Federal MCLlMCLG State MCL 1,1-DCE 7 6 1,1-DCA _ 5 1,1,1 TCA 200/200 200 NON-ATTATNMENT AREA r 27. Available options for removing or treating in situ groundwater pollution are limited. At many sites in this region and elsewhere, pump and treat technology is not adequate to meet low cleanup standards because the costs and timeframe may be prohibitive Groundwater pollution cleanup is a lengthy process which requires significant resources 28 Varian has documented the following in its RI/FS a An appropriate cleanup program, including adequate source removal, has been frilly implemented and reliably operated for a period of time which is adequate to understand both the hydrogeology of the site and pollutant dynamics, and b Groundwater pollutant levels have reached an asymptotic level, and 6