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• <br /> James L. Tjosvold, P.E. <br /> April 24, 1996 <br /> Page 2 <br /> action (shallow soil stabilization) was also discussed. DTSC and the RWQCB provided <br /> their preliminary comments on the draft Soil OUFS at this meeting. <br /> The third quarter monitoring report was submitted to DTSC and the RWQCB on October <br /> 31, 1995. Monthly groundwater elevation measurements continued through December, <br /> 1995. The fourth quarter monitoring event was conducted December 4 and 5, 1995. The <br /> results of this fourth quarter monitoring event were presented in the fourth quarter <br /> monitoring report submitted to DTSC and the RWQCB on January 31, 1996. <br /> II. Activities Performed During, Current Quarter: <br /> The draft Soil OUFS recommended that a treatability study be conducted to further <br /> evaluate the effectiveness of the proposed soil remedial action, in-situ shallow soil <br /> stabilization. Details of the treatability study were discussed with DTSC and the RWQCB <br /> in a series of conference calls from December 7, 1995 to January 25, 1996. During the <br /> conference calls, agreement was reached on the leaching procedure to be used to evaluate <br /> the effectiveness of in-situ shallow soil stabilization. The treatability study, which will <br /> evaluate several potential soil stabilization mixtures, began in late January, 1996. Soil <br /> samples for the treatability study were collected from the site on January 25 and 26, 1996 <br /> and sent to the laboratory performing the treatability study. The final results of the <br /> treatability study (which is being conducted in several phases) will be available in early <br /> May, 1996. A conference call to discuss these results with DTSC and the RWQCB will <br /> be scheduled in May, 1996. <br /> Results of fate and transport modeling conducted by PG&E's consultant, CH2M Hill, are <br /> summarized in a report titled "Evaluation of Potential Groundwater Impacts from <br /> Residues in Soil" which was submitted to DTSC and the RWQCB on March 13, 1996. <br /> This modeling was conducted in response to DTSC and RWQCB comments on the draft <br /> Soil OUFS regarding the effectiveness of the proposed soil remedial action. The report <br /> utilizes VLEACH modeling, chemical-specific travel times, and diesel residual soil <br /> concentrations to demonstrate quantitatively that remediation of four soil source areas <br /> (identified in the Soil Feasibility Study) is protective of groundwater at the site. PG&E <br /> plans to incorporate the results of this report into Chapters 4 and 5 of the Soil OUFS. <br /> On April 3, 1996, PG&E and CH2M 911 conducted a conference call concerning the fate' <br /> and transport modeling report with DTSC and the RWQCB. During the conference call, <br /> DTSC and the RWQCB agreed to provide comments on this report as soon as possible. <br /> RWQCB and DTSC comments on the report will be addressed in revised Soil OUFS <br />