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Ms. Anne C. Conner September 22, 2009 4 There were 35 Pond 3 soil sample results for each of the COCs presented in that report. The composite sample averages fell into the following upper percentiles for these CDCs: barium 100% (35 of 35 samples were lower), sulfate 94% (33 of 35 samples were lower), sodium 51% (18 of 35 samples were lower), chloride 20% (7 of 35 samples were lower) and pH 0% (0 of 35 samples were lower). The pH results for the soil mound composites were in the acidic range and were lower than the pH for all Pond 3 subsurface soil samples: However, it is noted that 16 of the 35 Pond 3 samples had a pH below 7.0, ranging from slightly acidic to acidic, and the soil mounds have likely been exposed to acidic precipitation over a long period of time. Most of the composite results for the other COCs (barium, sulfate, sodium and chloride) were close to, or lower than, the background concentrations established for Pond 3 soils, and barium results were less than five percent of the hazardous waste characteristic criterion from California Code of Regulations Title 22, Division 4.5, Chapter 11. Because the barium and sulfate results might have possibly exceeded background, it was conservatively decided that the Request for Bid would be prepared assuming the soil mounds would be removed by the driller and stockpiled for PG&E offsite disposal at a Class III landfill. However, based on verbal approval by CVRWQCB staff and written confirmation by SJCEHD during implementation of well decommissioning, soil mounds around these wells, as well as excess soil generated during installation of mushroom caps, were spread and leveled on the surface adjacent to the wells (see final section below). REQUEST FOR BID, DRILLER SELECTION AND WELL PERMIT APPLICATION APPROVAL On June 5, 2009 a Request for Bid(RFB) was released to prospective drillers. This RFB was subsequently revised based on PG&E providing a survey report showing survey coordinates for WP-1 (see below). SJCEHD approved the original RFB as an acceptable work plan for well decommissioning (SJCEHD, 2009a) and also approved the revised RFB as an acceptable work plan (SJCEHD, 2009b). Attachment 3 to this report provides the revised RFB. MSE evaluated bids received based on the original RFB and chose RSI Drilling(RSI) to perform the decommissioning activities. The SJCEHD Well Permit Application was then completed and submitted to SJCEHD. The Application was approved on July 30, 2009 and is provided as Attachment 4 to this report. Upon the recommendation of SJCEHD, the Application did not list P-6A or WP-1 pending possible location of these piezometers. If the piezometers were located, SJCEHD would list them on the finalized Application. ADDITIONAL PG&E SURVEY DATA, WP-1 RESURVEY AND SITE UTILITY LOCATION To limit the extent of any clearing and scraping that would be required in attempting to locate 'P-6A and WP-1, MSE requested that PG&E search for historical survey data that might have been originally used to plot the locations of these piezometers on figures presented in previous reports. PG&E was able to locate survey data for existing monitoring wells, piezometers and staff gauges in a survey completed on October 25, 2000, which included