SITE INFORMATION AND CORRESPONDENCE

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Former Donna Gardner Property - 2 - 12 May 2010 26090 N. Thornton Rd Thornton, San Joaquin County monitoring wells water levels were automatically measured and calibrated for changes in atmospheric pressure. Since 1991, monitoring of Well #2 has consistently reported non- detect for petroleum hydrocarbons. In May 2008, three SVE wells (VW-1 through VW-3) and one AS well (AW-1) were installed for an 8-hour SVE and a 72-hour SVE/AS pilot test conducted in August 2008; along with one groundwater monitoring well (MW-7) installed 20' south of Well #2, to monitor for plume stability during the pilot test. Petroleum hydrocarbons were not detected in soil gas after 24 hours of the 72-hour pilot testing, or in groundwater at MW-7. Maximum groundwater concentrations for MW-4 in May 2009, the last monitoring event, were TPHg, 1,400 ug/L; ethylbenzene, 6.1 ug/L; and xylenes, 3.8 ug/L. Risk Assessment Investigations to date show the bulk of onsite soil contamination existed from 11' below ground surface (bgs) down to 25' bgs, where the consultant determined residual soil contamination poses minimal risk to human health from direct exposure. The August 2008 SVE/AS 72-hour pilot study reported non-detect for soil vapor sample results over the last 48 hours of testing, and the consultant determined there was no risk from vapor intrusion. The consultant determined that residual petroleum hydrocarbons in soil and groundwater did not pose a significant threat to human health or the environment. Land use (commercial) is not expected to change in the foreseeable future. Sensitive Receptor Survey The 26 October 2009 Closure Summary Report (Report) identified one active municipal well located 70' north (upgradient) of the Site, screened from 135' bgs to 245' bgs, with a sanitary seal extending from surface to a filter pack starting at 70' bgs. The nearest surface water body, the Mokelumne River, is approximately 2,000 feet east of the Site. The consultant determined that sensitive receptors are not threatened by residual groundwater contamination. Site Geology and Hydrogeology The Report listed Site soils as inter-fingered beds of sands, silts and clays down to 45'bgs, the total depth investigated. From 2004 to 2008, depth to water varied from approximately 4' bgs to 12' bgs, with water table elevations ranging from approximately 2' below to 6' above mean sea level. The downgradient groundwater flow direction varied from northeast to southwest. The groundwater gradient varied from 0.0009 ft/ft to 0.009 ft/ft. Residual Mass Calculation At the conclusion of the soil remediation in 2008, the consultant estimated the contaminant mass removed from soil as 3.4 gallons of TPHg, and approximately 0.04 gallons of TPHg remain in groundwater. The original mass was not calculated.