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win, 11mu May g, 1991 I` Page Two The intent of soil removal/remediation is to protect groundwater from a continuing source of contamination. Based on the limited magnitude of soil contamination and the lack of appreciable groundwater impact (see below) it is difficult to understand why soil removal would be recommended. In previous correspondance San Joaquin Co. never suggested that soil excavation would be necessary. We feel that no remedial efforts are warranted. 2) Monitoring well #1 was non-detect on October 30, 1990, however, on January 14, 1991, detectable concentrations of tol- uene and xylene were found. zero lines have not been estab- lished, therefore, additional monitoring wells should be in- stalled to show zero lines. At least one of the monitoring wells should be installed downgradient (northwest) of the former tank location. " The levels of toluene and xylenes found in water from monitoring well #1 (MW-1) during January approach the laboratory detection limit. This, combined with the lack of detectable TPHD and the fact that MW-1 is upgradient of the former tank pit throw doubt on the veracity of those data. MW-1 was not found to contain any detectable constituents during the April, 2991 sampling round (WaterWork, second quarter, 1991 report) . G5i5:> At the written request of San Joaquin Co. , Monitoring well #4 (MW-4) was installed at the immediate downgradient location from the tank pit. A water sample from this well, collected during the April, 1991 sampling round was found to contain 1.1 parts per billion (ppb) ethylbenzene. No other constituent was present in detectable concentrations. With the exception of the sample collected from this well on 5/22 90 immediately atel _ . following com- pletion,pletion, no well on-site has ever shown concentrations of any analyte above State action levels or MCLS (Table 2, attached) . The anomalous concentrations detected in the sample from MW-4 on 5/22/90 were thought to be a result of incomplete development. Successive rounds of sampling have confirmed this inference. For all Practical purposes the entire site falls within a "zero line". Additional monitoring wells would provide no useful infor- mation of significance. 3 ) "On-site there are two production wells. The influence on hydraulic gradient should bi explored. If both these wells are not being used, one should be abandoned or destroyed under PHD/EHD permit. " It is clear from the groundwater data collected from the monitor- 1 ing wells on-site (see Table Z and Figure 2, WaterWork's April 26, 1991 report and previous reports) that the production wells i.