SITE INFORMATION AND CORRESPONDENCE

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FROM 1997. -14 17:47 #888 P.11/24 Februaiy 14. 1997 Pa,e 10 Well MW-I 1 is screened from 43 to 7; bgs. Review of the quarterly monitoring data indicate a marked trend of attenuation to non detectable concentrations of petroleum hydrocarbons prior to the well becoming submerged. It is true that 67 ppb TPPH-g was reported in July 27, 1995 (with no detectable benzene) when the well Was submerged (by less than six inches). The October 1995 sampling of Well N4W-1 I U6th approximately three inches of submerged screen again reported no detectable concentrations of petroleum hydrocarbons. The well is currently submerged by over i-feet however.the trend of attenuating concentrations of petroleum hydrocarbons to near or below detectable concentrations was established prior to the well becoming significantly submersed. Weil MW-S was located adjacent to Well MW-11, had a much shorter screen length (24 to;9 feet), and was screened across the groundwater surface. Well MW-13 located less than 25 feet from Well MW-11 and closer to the source area reports no detectable concentrations of petroleum hydrocarbons in groundwater and, as concurred by the SJCEHD is representative of downgradient groundwater quality conditions. Groundwater sampling results are deemed representative of site conditions with the exception of Wells MW-9 and MW-13. Groundwater Monitoring Wells MW-10, MW-11, MW-14, and MW-2R all reported non-detectable concentrations of petroleum hydrocarbons in groundwater prior to the well screens becoming submerged. Therefore, those data arc viewed as being representative. Wells MW-9 and MW-13 reported detectable Concentrations of petroleum hydrocarbons prior to, and after becoming -submerged. Well MW-4 is located proximal to submerged Well MW-9, and Wells MW-5 and MW-6 are located between the source area and submerged Well MW-13. During the April and July and October 1996 sampling events, rising groundwater was sampled in Wells MW-4 through MW-6, and is therefore representa- tive of site conditions. The SJCEHD disagree that the groundwater sampling results[with the exception of Wells MW-9 and MW-13] arc representative of site conditions. Also, the welts which were installed in/989 which are properh1 screened for current water levels have been destroyed to accommodate the development of the site_ One Hell, MW-8 was destroyed despite PHSIEHD's protest that it was not within the proposed development's footprint and it provided the downgradient well which could monitor representative groundwater quality. Due to the rising groundwater conditions and prior to being abandoned,Well MW-8 was sampled during three consecutive events during 1996. No concentrations of petroleum hydrocarbons were detected. The SJCEHD concurred that Well MW-8 prior to,being abandoned provided representative downgradient groundwater quality data. Additionally, as discussed previously, Well MW-11 also defines the extent of petroleum 320133791CLOSLRD