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Ms. Anne C. Conner September 22, 2009 7 WELL DECOMMISSIONING AND SITE CLOSURE FIELDWORK: PHASE II On September 8, 2009 the PG&E biological contractor inspected each soil mound for open burrows and evidence of burrowing owls and removed the one-way doors. No evidence was found that burrowing owls were present, so MSE and RSI were able to complete most decommissioning activities on that day. MSE arrived at the site early in the morning to confirm that the flush-mounted markers for all previously decommissioned wells were still present,pending a SJCEHD inspection that had been scheduled for later in the morning. Monitoring wells MW-1 RD, MW-3, MW-9 and the unknown conduit were decommissioned in accordance with SJCEHD standards (SJCEHD, 2005). Based on verbal approval by CVRWQCB staff during the August 4, 2009 site visit and written confirmation by SJCEHD (SJCEHD, 2009d), soil mounds around these wells and the unknown conduit, and excess soil generated during installation of mushroom caps, were spread and leveled on the surface adjacent to the wells and the unknown conduit. Observations on the unknown conduit were as follows. There was an outer metal pipe about six inches in diameter that contained two 2-inch metal pipes that were both sounded at about 17 feet depth. The inner pipes appeared to be cemented inside the outer pipe. It could have been reasonably assumed that this conduit was an undestroyed and unmarked set of nested piezometers, but the similar depth of the inner pipes makes this unlikely unless one or both of the inner pipes had filled with debris to 17 feet depth. However, the outer pipe was easily pulled out with the backhoe and found to be hollow at the bottom and about 17 feet long. The hole that remained after removing the pipe did not collapse and was pressure grouted. The SJCEHD inspector arrived at about 9:30 a.m. to complete an inspection. He confirmed the decommissioning of 20 wells and piezometers during the Phase I fieldwork and observed that the four of the remaining five wells and piezometers (including the unknown conduit) were being decommissioned during the Phase II fieldwork. The inspector also observed a mushroom cap that had not been backfilled. On September 9 the inspector acknowledged that Permit SR#0057924 could be finalized once MW-11 was decommissioned (see below). RSI was not able to obtain a non-sparking saw to complete the decommissioning of MW-11 on September 8. However, RSI had procured the appropriate equipment by the end of that week and was able to complete the decommissioning on September 14. Because the saw was hand-held and not powered, it had a long horizontal handle for cutting the MW-11 steel conductor with a circular blade that was tightened around the conductor. RSI needed to shovel a hole around the casing that was about six feet in diameter and four feet deep (the maximum depth to safely enter a hole without shoring or benching). Once the casing was cut off at 2.5 feet bgs, the hole was backfilled and compacted to three feet diameter before the mushroom cap was placed. 'Also on September 14, MSE removed staff gauges in Whiskey Slough to complete the site closure process. Staff gauges WSSE-4, -5, -6 and -7 were observed to still be present during the May 21, 2009 reconnaissance described above. WSSE-5 and-7 were removed and WSSE-4 and-6, which were both found lying on their sides, were picked up.