SITE INFORMATION AND CORRESPONDENCE

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River City Petroleum - 6- 15 April 2014 Connell Motor Lift Truck 2211 North Wilson Way Stockton, San Joaquin County Residual Mass Calculation In 2012, based on pre-remediation data the consultant estimated initial mass of petroleum in the subsurface as 16,885 lbs in soil (Figures 4 through 7, and 7B,) and 313.2 lbs in groundwater (Figures 8 and 9); however, SVE removed 41,097 lbs of petroleum hydrocarbons from soil. The remaining dissolved TPH mass in groundwater is estimated as 1.3 lbs (Figures 10 and 11). The Stoddard mass was determined to be less than 5% of the total RCP/CMLT commingled mass based on distribution of mass removed from soil and groundwater. Public Participation Public participation was conducted from 15 August 2012 to 15 October 2012 with no comments received. Low Risk Closure Policy (LTCP) Review The Site meets the criteria for a low risk closure under the State Water Resources Control Board Low Risk Closure Policy, based on the following: Groundwater Specific Criteria (2) a. The contaminant plume that exceeds water quality objectives is less than 250 feet in length. There is no free product. The nearest existing water supply well or surface water body is greater than 1,000 feet from the defined plume boundary. The dissolved concentration of benzene is less than 3,000 micrograms per liter (pg/l), and the dissolved concentration of MTBE is less than 1,000 pg/I. See above Table 2 and Sensitive Receptors section. Petroleum Vapor Intrusion to Indoor Air Appendix 3, Scenario 3, Figure B. Benzene in groundwater is less than 1000 ug/L and TPH in soil is less than100 mg/kg down to 10' bgs. Although post excavation TPH results exceeded 1,000 mg/kg for TPHg at 9' bgs, it is reasonable to expect that implementation of SVE has reduced that concentration significantly and the above criteria have been met. Soil vapor extraction well confirmation data, all non- detects for benzene and ethylbenzene in February 2011 one month after SVE was shut down, supports this determination. Direct Contact and Outdoor Air Exposure Maximum concentrations of petroleum constituents in soil listed in Table 1 for the specified depth below ground surface (bgs). The results indicate concentrations are less than the LTCP limits for 0 to 5 feet bgs to protect from ingestion of soil, dermal contact with soil, and inhalation of volatile soil emissions and inhalation of particulate emissions. The results indicate concentrations from 5 to 10 feet bgs are lower than LTCP limits to protect from inhalation of volatile contaminants. Both the 0 to 5 feet bgs concentration limits and the 5 to 10 feet bgs concentration limits for Commercial/Industrial use are satisfied. Conclusion Based on available data, the Site meets the criteria for closure under the State Water Board's Low Threat Closure Policy. Residual soil and groundwater pollution do not pose a risk to human health or identified sensitive receptors in the area. WQ0s are predicted to be met by 2037. Based on the stable plume with limited vertical and lateral extent of pollution, lack of threats to sensitive receptors from groundwater, or risk from soil and soil vapor intrusion, no further action is warranted at this Site. Staff recommends closure of this case. The required public participation comment period was conducted from 15 August 2012 to 15 October 2012 (with no adverse comments). All 48 monitoring wells (MW-1 through MW-48) and 48 remediation wells (VW-1 through VW-5, VW-6A through VW-19A, VW-6B through VW- 19B, IAS-1 through IAS-14, and EX-1) were properly destroyed and all investigation-derived waste was