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Appendix B Advanced AGE Project No. 99-0559 Environmental Page 4 of 12 n.M 9 INSTALLATION OF GROUNDWATER EXTRACTION SYSTEM The groundwater extraction system consisting of the groundwater treatment unit and associated piping was installed between 18 February and 26 June 2003. GROUNDWATER TREATMENT OPERATION The groundwater treatment system is designed to operate at a maximum flow rate of up to 10 gallons per minute (GPM); each of the four recovery wells extracts groundwater at a flow rate of approximately 2 to 2.5 GPM, by extracting on an intermitting cycle. The operation of the pumps allowed for a hiatus when water fall below the pump inlet to allow the well to recharge, after which the pump will reactivate. The groundwater treatment system operates on a batch basis, with a daily total of up to 4,000 gallons. Once the sediment holding tank fills, approximately 250 gallons of extracted groundwater is treated and discharged. The discharge of treated water (effluent) to the City of Stockton was adjusted at a flow rate of approximately 10 GPM. A total of 12,568 Ibs/2,010 gallons of petroleum hydrocarbons, 701.4 Ibs/112 gallons of benzene and 1,253 Ibs/200 gallons of MTBE were removed from the site since the initiation of SVE operation (May 2003). The groundwater remediation — extraction and treatment was discontinues in October 2016. SOIL VAPOR EXTRACTION SYSTEM INSTALLATION AND OPERATION In early September seven SVE wells VW-1 VW1, VW-2A/B, VW-3A/B and VW4A/B and one severely impacted monitoring well near the former UST area (MW-2) were connected below grade to the remediation area. In October 2006 a Solleco thermal oxidizer SVE unit was delivered to the site and installed with a fenced enclosure surrounding the groundwater remediation system. In late November and December 2006 a dedicated electrical service and high pressure natural gas line were connected to their respective meters which service the building at the site. The SVE unit was tested in thermal mode for operational readiness in early December. The system was receiving adequate concentrations of hydrocarbons to warrant operation in the high temperature thermal mode. The SVE system began operation on 13 December 2006 in accordance with San Joaquin Unified Air Pollution Control District (APCD) permit. Between 13 December and 26 December 2006, the SVE unit operated for approximately 316 hours. The SVE unit operated at variable operational rates during the observation period. Extraction flow rates were calculated to range from 50 scfm for startup testing, 150 scfm for start operation to approximately 180 cfm after one week of full operation. A total of 2,293 kilograms or 5,054 Ibs or represented as 808.6 gallons of petroleum hydrocarbons were removed from the site in the first seven days of operation (between 13 to 19 December 2006). In July 2008,