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en viroso <br /> Request to Install Ground Water Monitoring Wells in lieu of Geoprobes <br /> • We concur with SJCPHS that installation of ground water monitoring wells and the ability <br /> to collect reproducible samples is necessary for delineation of petroleum hydrocarbons in <br /> ground water However, Shell does not wish to install additional wells whictr do not serve <br /> to complete delineation of the plume (i a install additional wells from which ground water <br /> is not non-detect) Use of the geoprobe is proposed as a reconnaissance tool to determine <br /> whether the limits of the plume have been reached Upon receipt of the ground water <br /> chemical analytical data from the geoprobes, if data indicate that ground water conditions <br /> are non-detect (ND) for constituents of concern, installation of ground water monitoring <br /> wells will be completed <br /> If ground water conditions are not ND in the locations of the geoprobes, revised locations <br /> will be proposed in a "step-out" manner Drilling activities in these locations will proceed <br /> upon approval and receipt of permits from SJCPHS and acquisitions of encroachment <br /> and/or right-of-entry agreements <br /> Request for Additional Monitoring Well to the Southwest of MW-3 <br /> The geoprobe Iocations proposed in the work plan were selected based on SJCPHS <br /> December 13, 1996 letter which stated that "additional ground water investigation is <br /> necessary west of Geo3, and south of Geol and Geo4," and the south/southeasterly <br /> ground water flow direction which has been observed If SJCPHS feels that investigation <br /> west of MW-3 is necessary, we would propose that the geoprobe planned to the west of <br /> Geo3 be moved south, to the location Shown on the attached Plate 2 It would then address <br /> investigation cross-gradient of both Geo3 and MW-3 <br />• Request for Additional Soil Investigation in the Former Dispenser Island Area <br /> Discussions held with the former consultant regarding the need for investigation in the <br /> former dispenser island area were apparently not communicated to Enviros during the <br /> transfer of the project We apologize for this lack of communication We have noted from <br /> the site file that results from the sampling done during the tank and line replacement were <br /> submitted to you by Fugro on December 11, 1995 A review of the laboratory data sheets <br /> shows that Table 3B "Soil Analytical Results - Product Line Trenches," contains errors in <br /> reporting of benzene and toluene for sample TR-1 and in benzene for sample TR-2 <br /> Corrected results are as follows <br /> Sample Benzene Toluene <br /> TR-1 0 021 0 008 <br /> TR-2 3 7 ----- <br /> (results in parts per million) <br /> Full documentation of sampling in the former dispenser island areas is provided in Aegis <br /> Environmental's "Preliminary Subsurface Investigation/Tank Closure Report," dated June <br /> 18, 1990 <br /> Geoprobe borings are proposed in the locations shown on Plate 2 to delineate the lateral <br /> and vertical extent of petroleum hydrocarbons in soil The proposed depth of these borings <br />. is 10 feet below grade (fbg) Borings adjacent to sample locations TR-4 and TR-2 will be <br /> drilled to depths as necessary to delineate the vertical extent of petroleum hydrocarbons in <br /> soil <br /> 2 <br />