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s ' Monitoring Well Installation Report-Tosco(Former BP)Service Station No 11192 SePteMber 26,2001 As part of the subsurface investigation in April 2001, GR conducted a well search and Sensitive Receptor Survey (SRS) in the vicinity of the subject site The well search was conducted within a F/2 mile radius around the site Based on the 'available, data supplied by the California Department of Water Resources (DWR), three municipal wells were identified within the 112 mile radius of the study area, the closest well being located approximately 1000 feet north- northwest of the site The depths of all three wells were reported to exceed 550 feet bgs and they were reported to have screened intervals beginning at least 350 feet bgs The study area for the SRS was a circle with a 500 foot radius centered around the subject site The SRS involved distributing questionnaires to all residence and businesses within the study area The questionnaires were 'used, to collect information about potential groundwater receptors GR distributed 141 questionnaires via the U S Post Office and 36 of the distributed questionnaires were returned to GR (GR, 2001) Subsequent to GR's report submittal on June 7,'2001, 13 additional questionnaires (49 total questionnaires returned) were returned to GR None on the returned questionnaires identified the presence of a well within the study area 3.0 FIELD WORK Field work was conducted in accordance with GR's Work Plan dated July 6, 2001, GR Field Methods and Procedures (Appendix A) and the Site Safety Plan dated July 12, 2001 Four drilling permits were obtained from the San Joaquin County PHS-EHD (Permit Nos 0027000 - 0027003) and three encroachment permits were obtained from the City of Stockton Department of~Public Works (Permit Nos 196CC - 198CC) Copies of the permits are included in Appendix B Underground Service Alert was notified 48 hours prior to drilling at the site, as required by law As a precaution, Cruz Brothers Locators Inc , a private utility locating service, was hired to check the well locations for underground utilities s 31 Drilling Activities - On August 8, 9 and 10 2001, a GR geologist observed Woodward Drilling Inc (Woodward, C-57 #710079) install three off-site monitoring wells and one on-site monitoring well (MW-8 through - MW-11) at the locations shown on Figure 2 The four well borings were drilled using hollow-stem augers (HSAs) driven by a truck-mounted drilling ng Soil samples were collected from the bonngs every five feet at a minimum The GR geologist prepared boring logs for each well and ' field screened the soil samples for the presence of volatile organic compounds utilizing a photoionization detector (PID) Lithologic descriptions and field screening data are presented on the boring logs (Appendix B) , The three shallow off-site wells MW-8, MW-9 and MW-10 were installed on August 9, 2001 with • 8-inch diameter HSAs to depths ranging from 28 feet 29 feet bgs The three wells were constructed 14024505-2 4