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INC <br /> Exceeds <br /> Maximum Maximum Maximum Primary <br /> Chlorinated Hydrocarbon Prima MCL at 15 feet at 40 feet Site Levels MCL <br /> T (ppm) (ppm) (ppm) (ppm) <br /> 1,1 Dichloroethane 0 005 53 0027 53 Yes <br /> 1,1 Dichloroethene 0 006 038 NO 038 Yes <br /> 1,1,1 Tnchloroethane 0200 0 025 011 0 025 No <br /> Trichloroethene 0 005 006 00087 0 060 Yes <br /> CRWQCB Primary MCL concentrations for ground water have been exceeded for 1,1 <br /> Dichloroethane, 1,1 Dichloroethene, and Trichloroethene in the soil at depths of 15 feet <br /> below ground surface <br /> With the exception of 1,1,1-Trichloroethane, all chlorinated hydrocarbon compounds <br /> appear to significantly attenuate their soil concentrations by an order of magnitude or <br /> more from 15 to 40 feet below ground surface The 1,1,1-trichloroethane concentrations <br /> • appear to attenuate approximately 50% ver the same distance At a depth of 40 feet, <br /> efte- <br /> only 1 - ane exceeds the CRWQCB Primary MCL goals This level is very <br /> low and exceeds the Primary MCL goals by only 20% A slight potential for ground water <br /> contamination by the chlorinated hydrocarbon compounds is present at the site <br /> 6.3 Area A <br /> Area A was investigated by WZl using previous TMG (1992) data to determine the <br /> subsurface extent and nature of soil reported by TMG to have been slightly impacted by <br /> heavy hydrocarbons TMG drilled three shallow soil borings to a maximum depth of 6 5 <br /> feet and one boring to a maximum depth of 16 5 feet in Area A Boring A-2 drilled by <br /> TMG (1992) reported a maximum of 36 ppm of Total Petroleum Hydrocarbons as Diesel <br /> and 380 ppm Total Petroleum Hydrocarbons from a depth of approximately 2 to 3 5 feet <br /> No other hydrocarbon impacted soil was found to be present (Appendix 1) <br /> 12270010 013 Page 21 <br />