SITE INFORMATION AND CORRESPONDENCE

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1 , Blue Star - 2 - 25 October 2013 4040 E. Main St. Stockton, San Joaquin Country 4,000-gallon diesel USTs were removed. The station was demolished and the site has remained vacant. The property is zoned commercial, and the current property owner has not provided any future development plans. 5) Maximum soil concentrations detected from the UST removal were total petroleum hydrocarbons as gasoline (TPHg), 24 milligrams per kilogram (mg/kg); TPH as diesel (TPHd), 0.015 mg/kg; benzene, 0.023 mg/kg; toluene, 0.054 mg/kg; ethylbenzene, 0.57 mg/kg; and xylenes, 13.6 mg/kg. MTBE was not detected in soil. 6) Maximum grab groundwater concentrations from boings advanced in April 2003 were TPHg, 180 micrograms per Liter (ug/L); toluene, 5.6 ug/L; ethylbenzene, 3.0 ug/L; xylenes, 15.5 ug/L; methyl tert-butyl ether (MtBE), 68 ug/L; and 1, 2-dichloroethane (1, 2-DCA), 170 ug/L. On 13 March 2013, maximum groundwater monitoring results were TPH as diesel, 270 ug/L; MTBE, 11 ug/L; and 1,2-DCA, 45 ug/L. Comprehensive groundwater monitoring data is presented on Table 2. 7) A Site Conceptual Model has been developed. Submission of multiple reports has resulted in development of a comprehensive site conceptual model including sampling of the groundwater. Depth to groundwater varied from 65' below ground surface (bgs) in May 2005 to 50' bgs in March 2013. The groundwater flow direction has varied from southeast to northeast at very low gradients of 0.0003 ft/ft in March 2013 to 0.0005 ft/ft in February 2012. Groundwater flow and gradient data are included in Table 1.Horizontal and vertical characterization is provided by monitoring wells MW-7A through MW-7C (100' east) and MW-9A through MW-9C (200' southeast) as shown in Figure 2B, constructed as part of the investigation of the Jamar Service, 4075 E. Main St. Well and boring construction details are presented on Table 3. 8) A prediction of when WQOs would be met was not provided by GHD. GHD did conclude that based on groundwater monitoring, that the residual groundwater plume will not migrate beyond the current conditions. 9) Pollutant impacts from the Jamar Service Station overwhelm the pollutant discharges from Blue Star. While there appears to be some commingling of the two plumes, the Blue Star plume has been orders of magnitude lower in pollutant concentrations than the Jamar Service plume. Groundwater impacts from the Jamar Service Station are detected more than 300 feet away from the Jamar property while impacts at Blue Star are believe to be confined to the Blue Star property limits based on results of soil sampling from borings B-1 through B-3 and MW-4 and MW-5 (see Table 4 for results). Ethylene dichloride (1, 2-DCA) levels in MW-4 (45 ug/L) are believed to originate from Jamar Service. Jamar Service is undergoing remediation by soil vapor extraction and ozone sparging for its plume, east of the Blue Star plume. 10)The Site appears to meet the general criteria of the State Water Resources Control Board's (State Water Board's) Low-Threat Underground Storage Tank Case Closure Policy (LTCP) as follows: • The site is within the service area of a public water system. The site is within the service area of the California Water Service (CWS) of Stockton, CA.