SITE INFORMATION AND CORRESPONDENCE_FILE 2

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Roek Construction - 2 - September 2012 Claim No. 7881 ATTACHMENT SUMMARY OF BASIC SITE INFORMATION (Conceptual Site Model) Site Location/ History • The Site is located at 102 South Wilson Way in Stockton, California and is an active tire store. • The Site is bounded by South Wilson Way to the west, East Market Street to the north, a business to the east and a gasoline station to the south. The surrounding land use is mixed residential and commercial. • In June 1988, soil contamination was identified during an environmental investigation. To date, 26 active monitoring wells have been installed and monitored regularly. • A Site map showing the location of the monitoring wells and groundwater level contours is provided at the end of this five year summary. Pollutant Source • Nature of Contaminants of Concern: Petroleum hydrocarbons only. • Source, Date reported, and Status of Release: UST system, 10 June 1988, USTs removed. • Free Phase Hydrocarbons: None reported. Geology/ Hydrogeology • Stratigraphy: The Site is underlain by interbedded and intermixed sand, silt and clay. • Maximum Sample Depth: 140 feet below ground surface (bgs). • Minimum Groundwater Depth: 33.97 feet bgs at monitoring well VW-1. • Maximum Groundwater Depth: 46.24 feet bgs at monitoring well MW-11. • Current Average Depth to Groundwater: 35 feet bgs. • Saturated Zones(s) Studied: 35 to 120 bgs. • Groundwater Flow Direction: Northeast at approximately 0.001 feettfoot. Groundwater Trends: There are more than 17 years of groundwater monitoring data for this Site. Benzene trends are shown below: Source area (MW-2), Near down gradient (MW-5), Intermediate down gradient (MW-8), and Far down gradient (MW-10). BENZENE Results for MW2 3500 2300. q',300 yY 1333 4 '4e r L w__BENZENE ��w Teq