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' Off-Site Groundwater Investigation Work Plan Page 3 Rainwater Car Wash, Manteca, California 95336 May 30,2012 1 3.2.3 AGE, Sensitive Receptor Survey, September 8, 2000 ' AGE conducted a sensitive receptor survey to locate potential vertical conduits within a 2,000-foot radius of the site. The sensitive receptor survey located four City of Manteca Public Works Department(CMPWD)municipal water wells and 25 groundwater monitoring wells located within one mile of the site. ' Sensitive Receptors Name Distance from the Site Description CMPWD Well#276- 1,900 feet northwest Non-operational water well located 200 feel north of the Almond Almond Avenue Avenue and Yosemite Avenue intersection CMPWD Well#431 - 3,000 feet northeast Non-operationsl water well located 100 feet east of the Pine Pine Street Street and Garfield Avenue intersection CMPWD Well#331 - Operational water well located 100 feet east of the Jessie Street Jessie Street ' 1,500 feet south and Oregon Street intersection CMPWD Well#613-EI 3,200 feet southwest Operational water well located 100 feet east of the Tenaya Court Capitan Avenue and Portal Avenue intersection 11 Groundwater 1,500 feet east Diamond Lumber,151 South Main Street ' Monitoring Wells 14 Groundwater 1,800 feet east Golden Grain,229 Moffat Boulevard Monitodng Wells ' 3.2.4 AGE, Cone Penetrometer Testing Site Investigation — Fourth Quarter 2000, February 7, 2001 ' AGE advanced four additional soil borings(P-7 through P-10)on-site,using cone-penetrometer testing(CPT) technology to characterize the geologic/hydrogeologic framework and to assess preferential contaminant migration pathways. Based on the initial CPT data,AGE informally identified four potential hydrogeologic flow units(designated as the First, Second,Third and Primary Water Zones),and located at depths between 15 and 47 ' feet below ground surface(bgs), 58 and 92 feet bgs, 102 and 115 feet bgs,and 128 and 150 feet bgs, respectively. Significant concentrations of dissolved petroleum hydrocarbons were reported from the First Water Zone,and low to moderate concentrations of dissolved petroleum hydrocarbons and chlorinated solvents(tetrachloroethene and trichloromethane)were reported from the Second,Third and Primary Aquifer Zones. 3.2.5 AGE, Ground Water Aquifer Pumping Test Report— Second Quarter 2001, May 15, ' 2001 AGE installed groundwater extraction well EW I and groundwater observation well MW6 at the site for performance of a groundwater pumping test. Soil borings EW 1 and MW6 were advanced to 45 feet bgs. Boring EW 1 was single-completed as a 6-inch-diameter groundwater extraction well and MW6 single-completed as a 2- inch-diameter groundwater observation well with screened intervals between 20 and 45 feet bgs.No soil or groundwater samples were collected during this investigation. A groundwater aquifer pumping test was performed at well EW 1 to assess the general groundwater aquifer characteristics at the site. From the pump test,a transmissivity value was calculated at 955 square feet per day,a storativity value at 0.032,a hydraulic conductivity value of 0.013 centimeters per second,and a groundwater radius of influence projected at 140 feet, using a semi-logarithmic plot of drawdown versus distance. 3.2.6 AGE, Interim Remediation Work Plan- June 2001, 21 June 2001 Interim groundwater pump-and-treat remediation was initiated at the site by continuous extraction of groundwater from well EW 1 at a rate of approximately 5 gallons per minute. The extracted groundwater was processed through ' a groundwater treatment system consisting of 8,000 pounds of granular activated carbon.Following treatment, Ami Adini ' �Assoctates.inc.