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AkM <br /> Western Stone ProdUCLS, Inc., Tracy, CA �� <br /> April 30, 1992 <br /> Page 2 <br /> San Joaquin County, however, has expressed concern regarding the possibility of a threat to <br /> groundwater quality from in place soils and has requested additional investigation. While <br /> acknowledging that we have not established beyond any doubt the lack of a threat, we have <br /> resisted further work for the following reason. It is clear that some doubt will always exist in <br /> any investigation and realistic limits must be established regarding the scope of investigation. <br /> An example would be the automatic closure extended to underground tank sites where no overt <br /> evidence of a leak is observed. Depending on the history of tank use, soil type, actual sampling <br /> locations, and a dozen other variables, it is conceivable that no evidence of contamination is <br /> found beneath the tank when, in fact, a problem exists at depth. Nevertheless these criteria have <br /> been adopted in order to bring some semblance of reason to the regulatory process and to avoid <br /> what in most cases would be wasted expenditure. <br /> Our concerns were expressed in the meeting and, I believe, taken seriously by Mary Meays and <br /> Diane Hinson. Ms. Hinson, in particular, appeared to understand our frustration and expressed <br /> a desire to move forward toward closure. <br /> The County suggested that additional investigation of soil in the immediate vicinity of the former <br /> tank pit would, in all likelihood, provide enough data to determine if a credible threat to <br /> groundwater exists. We indicated that we would be willing to undertake this work, provided <br /> a clear understanding existed between WSP and the County as to what the subsequent action <br /> would be. We suggested that if the soil sampling clearly indicated no threat to groundwater we <br /> would expect the County to immediately recommend closure to the CRWQCB. If, on the other <br /> hand, the data was inconclusive we would agree to continued groundwater monitoring, modified <br /> as appropriate, in order to establish empirically that no threat existed. In the worst case, where <br /> significant contamination was discovered, we would undertake all necessary investigation and <br /> remediation. We requested that the County provide a "decision tree" in order to concretely chart <br /> the next course of action. <br /> The March 3 letter from San Joaquin County certainly reflected positive efforts in this regard. <br /> The County directed WSP to "...include a request for closure" if no contamination is detected. <br /> In the event contamination is detected WSP is requested to "...estimate the residual <br /> contamination and suggest remedial alternatives and possible modifications of quarterly <br /> monitoring well sampling". Implicitly these directives are in accord with what was discussed <br /> in the meeting. It would have been reassuring, however, if the County had indicated how they <br /> would respond to a request for closure or a modified sampling schedule. <br /> The enclosed workplan includes a decision matrix and our expectations of County response to <br /> the various scenarios. We will view your approval of the workplan as concurrence with these <br /> expectations and a commitment to act accordingly. We understand that you probably feel that <br /> you cannot promise a specific response to a given situation. Within certain bounds, however, <br /> L-040792.0PS <br />