SITE INFORMATION AND CORRESPONDENCE

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River City Petroleum -4 15 April 2014 Connell Motor Lift Truck 2211 North Wilson Way Stockton, San Joaquin County wells (0W1 and 0W2) were installed in April 2002. An aquifer pumping test was conducted in extraction well EW-1 and a soil vapor extraction pilot test using VW-1A through VW-5A, and VW-1B through VW-5B was conducted in May 2002. Table 2B maximum CMLT groundwater results are in micrograms per Liter (ug/L). PCE was not detected in groundwater. Date TPHg TPHd TPHss B T E X MTBE 1,2-DCA EDB TBA 2-99 NA NA NA NA NA NA NA NA NA NA NA 7-99 120,000 330 120,000 96 72 210 760 <0.5 1.4 <50 <250 2-01 180 11 99 <0.5 <0.5 <0.5 <0.5 <1.0 22 <1.0 <5.0 7-03 30,000 NA 27,000 <0.5 <0.53 2003 <0.53 <0.5 27 <1.0 <5.0 12-03 17,000 NA 17,000 40 79 190 830 <0.5 45 <0.5 <50 2-12 <50 NA 800 _ <0.5 <0.5 7.6 13 <1 <0.5 <0.5 <10 TPHg= total petroleum hydrocarbons as gasoline TPHd= as diesel TPHss = as Stoddard Solvent B = benzene T = toluene E = ethylbenzene X = xylenes MTBE = methyl tert butyl ether Pb = total lead EDB = ethylene dibromide TBA = tert butyl alcohol NA = not analyzed ND = non-detect In November 2002, the CMLT consultant met with Regional Board staff to discuss the Stoddard plume, and the presence of the gasoline lead scavenger 1, 2- dichloroethane (1, 2-DCA) in CMLT wells at 100' below ground surface (bgs). The source of the 1, 2-DCA was suspected as originating from the RCP USTs release, since the 1, 2-DCA groundwater plume was intercepting the Stoddard plume at a deeper water-bearing zone, and 1, 2-DCA plume concentrations were an order of magnitude higher in the RCP plume source area. 1,2 DCA concentrations extended vertically from the former RCP area to the CMLT portion of the of the Site at depths up to 180' bgs. Regional Board staff directed CMLT to conduct interim soil vapor extraction while RCP performed additional 1, 2-DCA investigation under SJCEHD oversight. A CMLT Corrective Action Plan for interim remediation (SVE) was submitted in February 2003; however implementation was placed on hold pending the commingled plume evaluation. Commingled Plume By January 2003, the groundwater data consistently showed the RCP petroleum hydrocarbon pollution (including 1, 2-DCA down to 180' bgs) migrated from the USTs to the west and commingled with the CMLT Stoddard release. On 23 January 2003, the SJCEHD referred the RCP case to Regional Board staff for oversight of both the RCP and CMLT cases by one agency. In a letter dated 15 September 2003, Regional Board staff requested RCP and CMLT monitoring reports be merged into one report for efficiency, remediation efforts target the entire commingled pollutant plume, and monitoring wells be renumbered to remove potential confusion due to duplication of well identifiers. Connell then consolidated the RCP and CMLT investigations under Advanced GeoEnvironmental Inc. After renumbering the wells, additional deeper monitoring wells were required and installed down to 248' bgs (Figures 3 and 3B) from September 2004 to July 2005, for a total of forty eight (48) monitoring wells (MW-1 through MW-48). The pollutant plume was defined horizontally and vertically to a depth of 248 feet bgs and extended under Wilson Way about 100 feet to the east. Initially SVE (2004) and later Air Sparging (AS, 2008) were pilot tested and implemented as the soil and groundwater remediation. Prior to AS, an ozone injection bench scale test was conducted in August 2006; however a spike in hexavalent chromium and bromate concentrations, along with a successful AS pilot study in 2008, resulted in a recommendation for implementing AS for groundwater remediation. In April 2004, twenty SVE wells (VW-6A through VW- 15A, and VW-6B through VW-15B) were installed. From January 2007 to June 2008, fourteen AS wells