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Remediation Report - 152 East I lth Street, Tracy, California Page 7 Y g to remove contaminated soil from the subsurface, the regulatory limits on discharges to surface waters and to the air and local noise abatement ordinances (Ref 2, 3 and 13)) The applicability of a number of alternate remedial technologies was studied in the context of the prevailing, site-specific geotechnical, hydrogeologic, groundwater-quality, construction engineering, and site infrastructure and usage parameters and the interactions between them (Refs 13 and 14) Following consultation with the SJCPHS, it was decided that the most viable site-specific corrective action program would be to demolish the existing structures on the site, excavate contarrunated soil from the accessible subsurface and provide, as necessary, for supplementary groundwater remediation by limited pumping of contaminated water from the remedial excavation and treating the pumped water prior to discharging it to the municipal storm-water sewer Of vital concern in planning the remedial excavation and any groundwater pumping that might be required was concern for the safety of close-by, old, unreinforced brick buildings at 124 and 208 East 11 th Street and the potential for arealy extensive settlement of the paving on East 11th and F Streets This concern was raised by the geotechnical properties of the very loose sands that lie at depth beneath the site Instability of the walls of the remedial excavation, quick-sand conditions, or bottom heave might develop, either due to the excavation work itself or due to pumping groundwater from the pit, unless the depth, areal extent, excavation methods, backfilling and groundwater pumping procedures were carefully controlled A final version of a CAP (Ref 17) together with an engineer's estimate of the cost to implement the plan (Ref 18) was submitted to the SJCPHS for review on November 18, 1995 The CAP and estimate were approved by that agency on December 20, 1995 On the same day, the SJCPHS issued a Public Notice of Findings to initiate the public participation process that is required prior to final approval of a CAP The requisite period for public comment closed on January 19, 1996 without objection from any party TESTS FOR PESTICIDES AND OTHER ANALYTES IN GROUNDWATER On November 15 1995m 1 sa p es were recovered from groundwater-quality monitoring wells installed for the Navarras on and around the 152 East 11th Street property (Ref 19) The samples were analyzed for components of gasoline in compliance with the established groundwater-quality monitoring plan that had been established for the site (Ref 8) However, on that occasion, to check for the presence of other analytes that might be of concern when the proposed remediation program was initiated, additional samples were recovered from wells NAV 3 and NAV 4 and analyzed for chlorinated pesticides, chlorinated volatile hydrocarbons, aromatic volatile hydrocarbons, general minerals (Note Samples from wells NAV 3, NAV 4 and NAV 6 had been analyses for total led on February 22, 1996 ) The certificates of analysis that document the results of the analyses together with the associated chain of custody documentation are included in Appendix C No lead or elevated concentrations of any analytes of concern other than components of gasoline were detected