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11 S [E cC O R r Mr Mike Infurna x 9 February 26, 2004 ,r Page 3 'z Supply Well Survey According to IT's Site Assessment Report, dated February 25, 2000, IT performed a water supply well search to locate any water supply wells within 2,000 feet of the subject site Review of well logs r at the California Department of Water Resources (DWR) Indicated the presence of one water supply well within the 2,000-foot search radius, located at 1521 N Hunter Street Well construction details and usage of the well was not documented on the DWR well log The San Joaquin County Environmental Health Department(SJCEHD) attempted to locate the well, however the well was not found Additional well searches conducted in the area(adjacent LUFT site ARCO 4932, 16 E Harding Way) indicated that 4 wells were located approximately 2000 feet east of the site at the Stockton State Hospital and approximately 2,000 feet northwest at the Intersection of Wyandotte and Commerce (As Indicated by SJCPHS In their letter dated Nov 21, 2000) The sensitive receptor survey Is presented ; in SECOR's report Additional Site Assessment Report dated November 9, 2001 for ARCO 4932 Remedial Action Summary Source removal conducted at the site to date consists of over-excavation of obviously Impacted sod during the UST, dispenser and product line removal conducted In 1999 A total of approximately 1,707 tons of soil was transported off-site for disposal at the Forward Landfill In Manteca, California PROPOSED SCOPE OF WORK `t The scope of work for this site assessment will include the drilling and Installation of three deep groundwater monitoring wells onsite (Figure 2) The specific scope of work is discussed below .w Site Specific Health and Safety Plan As required by the Occupational Health and Safety Administration (OSHA) Standard "Hazardous Waste Operations and Emergency Response" guidelines (29 CFR 1910 120), and by California Occupational Health and Safety Administration (Cal-OSHA) "Hazardous Waste Operations and Emergency Response" guidelines (CCR Title 8, Section 5192), SECOR will prepare a Site-Specific Health and Safety Plan prior to the commencement of fieldwork The Site-Specific Health and Safety Plan will be reviewed by the field staff and contractors before beginning field operations at the site Permitting Groundwater monitoring well Installation permits and soil boring permits will be obtained from SJCEHD prior to initiating work Deep Well Installation Three groundwater monitoring wells will be Installed at the location shown on Figure 2 Groundwater is anticipated to be encountered at approximately 30 feet below ground surface (bgs) The soil boring will be drilled using an air rotary casing hammer drill rig equipped with 8-inch diameter heavy-walled downhole casing The casing hammer will be advanced following the ' drill rods In order to seal the upper groundwater bearing zone from the lower groundwater bearing zone Upon completion of drilling, a 2-Inch diameter groundwater monitoring well will be Installed in the boring The well will be screened with 2-Inch diameter,flush-threaded, Schedule 40 PVC casing with 0 010-inch factory-slotted screen within a sand zone The well Is anticipated to be Install from approximately 110 to 120 feet bgs Approximately five feet of screen will be placed in the bottom of r " the boring A grade of sand appropriate to the screen size will be placed in the annular space across " • the entire screened Interval, and will extend approximately two foot above the top of the screen for , the wells A bentonite pellet seal will extend two to four feet above the sand pack The monitoring ConocoPhillips/44091work plansNVP For Vertical Assessment y