SITE INFORMATION AND CORRESPONDENCE 1995-2004

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• • James L. Tjosvold, P.E. ' January 24, 1997 Page 2 • On August 28, 1996, PG&E, DTSC and the RWQCB met to discuss input parameters to the VLEACH model;the groundwater mixing cell; preliminary VLEACH model results; and the application of VLEACH during the FS. In addition, agreement was reached on the soil data needs for defining Area I source areas. • On September 12, 1995,PG&E, DTSC and the RWQCB met to discuss technology screening for soil and groundwater; ARARs; the status of data needs for Areas I and H soils; and the installation of a Zone B groundwater monitoring well(s) along El Dorado Street(perimeter of Area II). • On October 11, 1996, PG&E, DTSC and the RWQCB met to discuss the results of sensitivity analysis performed on VLEACH input parameters; the details of the groundwater mixing cell model; and the use of the VLEACH model and mixing cell model during the FS. There was a general agreement that most of the parameters used in the VLEACH model are acceptable and that both the typical and "super run" scenarios will be used in evaluating areas for remediation. On July 9, 1996, PG&E received a letter from DTSC regarding the proposed FS approach (presented by PG&E in a June 6, 1996 letter) clarifying that DTSC considers background or non-detect to be the starting point for evaluating technologies in the FS. The letter also suggested that more information is needed to define soil source areas. PG&E prepared a response to this letter, dated August 6, 1996, which included agreement to do more soil borings in Area I to further define soil source areas. PG&E submitted its responses to DTSC and RWQCB comments received on the draft Soil OUFS (draft Soil OUFS submitted to agencies on November 7, 1995 and agency comments submitted to PG&E in a letter dated December 26, 1995) on August 19, 1996. PG&E received agency comments (July 9, 1996 letter) on the"Phase IV Groundwater Investigation Draft Report", which was submitted to the agencies on June 11, 1996. PG&E submitted a letter addendum to the Phase IV report addressing these agency comments on August 7, 1996. On September 6, 1996, DTSC and the RWQCB commented on our August 7, 1996 response. PG&E replied to these comments in a letter dated September 24, 1996. The results of quarterly groundwater monitoring done in September, 1996 were submitted to the agencies on October 31, 1996 in the"Quarterly Monitoring Report, PG&E Stockton Former MGP Site, Third Quarter 1996".