SITE INFORMATION AND CORRESPONDENCE_FILE 1

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Equilon Enterprises • - 3 - August 11, 2011 Site Description The Site is located at 6131 Pacific Avenue in Stockton, California. The Site is bounded by businesses to the west and south, Porter Avenue to the north and Pacific Avenue to the east. The surrounding land use is commercial. Site History/Assessments In February 1990, leaking UST system was identified by inventory control. To date, 16 monitoring wells have been installed and monitored regularly. A Site map showing the location of the current and former USTs, monitoring wells and groundwater level contours is provided at the end of this five year summary. In addition, a site map with monitoring wells and chlorinated solvent concentration is shown. Remediation Summary • Free Product: No free product was documented throughout the life of this case. • Soil Excavation: An unknown volume of impacted soil was removed and disposed offsite in 1990 • In-Situ Soil/ Groundwater Remediation: Dual phase extraction, conducted from April 2007 through February 2009 removed approximately 2,543 pounds of TPH-G. In February 2009 the rate of removal was 3.1 pounds of TPH-G/day. In-situ chemical oxidation is proposed. General Site Conditions • Geology and Hydrogeology: The Site is underlain by interbedded and intermixed sand, silt and clay. The depth to groundwater varies seasonally between 30-33 feet bgs and the groundwater gradient is southeast at approximately 0.003 feet/foot. • Groundwater Trends: There are more than 21 years of groundwater monitoring data for this Site. Benzene trends are shown below, source area (VEW-2), near down gradient (MW-15) and far down gradient (MW-4) BENZENE Results for VEW-2 i +zaoa xPo fi � '.i I. BENZENE T.mO BENZENE Results for MW-15 .ow i xal i S 2.i a ,.✓P .�,. lie R fir;