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Fico/71-51-1C 7.0 REMEDIAL. ACTION OPTIONS This section deals with the identification and evaluation of viable remedial action options or technologies for the cleanup of contaminated soils and groundwater at the Caltrans Shop 10 facility The feasibility study is based upon the following considerations o The site is used as a maintenance yard o Soil and groundwater are both contaminated, generally around the area where fuel underground tanks were formerly located o The groundwater beneath the site is a source of potable water o Water quality must be returned to levels acceptable to regulatory agencies and that the 1990 DOHS Action Levels for Drinking Water and EPA Maximum Contaminated Levels (MCLs) apply (see Table 9, Appendix C) Benzene and toluene levels exceed water quality limits in MW10 (and SB17) Benzene exceeds the limits in MW11 o The lithology of the soil indicates that within the contaminated area, in general, the soil is clay and silt o Soil and groundwater in the other areas (i a waste oil tank area, wash rack area, front, of shop building) are generally clean and do not need any remediation o A new building will soon be constructed that will span over part of the soil and groundwater contaminated areas 71 Develo ment of Remedial Action Objectives The initial step in this process is the development of remedial action objectives These objectives consist of specific goals for protecting human health and the environment and are based on the contaminants of concern (gasoline-derived contaminants including benzene, toluene and xylenes), exposure routes and receptors, and an acceptable contaminant level of each exposure route Based on the considerations listed above, the following are proposed to be the remedial action option objectives o Return water quality to levels that meet the 1990 DOHS Action Levels from 21