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Monitoring Well and Sparge Points installation Report—Fortner Unocal Station#2859,Stockton,CA August 19,2002 During the May 13 and 14, 2002 event, TPHg range hydrocarbons were reported in wells MW-2 (18,000 ppb), MW-10 (100,000 ppb), MW-11 (40,000 ppb), MW-17 (65 ppb), and NP-1 (53 ppb) Benzene was reported in wells MW-2 (2,300 ppb), MW-10 (3,300 ppb), MW-11 (790 ppb), MW-20 (1 2 ppb), and NP-1 (0 53 ppb) Methyl tert-butyl ether (MtBE) was reported in well MW-9 at a concentration of 5 3 ppb by EPA Method 8021 B Vapor Extraction Test GR performed a five-day vapor extraction (VE)test at the site from June 18 through 22, 2001 The purpose of the VE test was to evaluate the feasibility of the VE technology and collect needed site specific data for the design of a VE system if deemed necessary The VE test was performed for a total of 39 hours An IC engine was used to extract vapors from wells VW-1,VW-2, and VW-3 Air samples were collected from the influent and effluent vapor streams Petroleum hydrocarbon concentrations detected in the influent vapor stream were up to 311 ppmv of TPHg, and up to 2 2 ppmv of benzene MtBE was not detected The only well where significant concentrations of petroleum hydrocarbons were removed was well VW-3 Based on the VE monitoring data, no significant amount of TPHg or benzene were removed during the pilot test It is estimated that less than one pound per day of petroleum hydrocarbons could be extracted Vapor extraction would have little or no effect at this site • FIELD ACTIVITIES In order to further delineate the extent of the dissolved petroleum hydrocarbon plume in the vicinity of the subject site and to remediate groundwater beneath the site, GR installed two additional off-site groundwater monitoring wells (MW-20 and MW-21) and installed eight on-site C-Sparge"m wells and supporting equipment at the locations shown on Figure 2 Field work was performed in accordance with GR's Site Safety Plan #240072 06, dated February 28, 2002 GR Field Methods and Procedures are included in Appendix A Underground Service Alert was notified at least 48 hours prior to beginning site activities The wells were installed by Woodward Drilling, Inc (C57 #710079) under SJCPHS-EHD permits #28980 and #28981, and City of Stockton encroachment permit #66460 Copies of the permits are included in Appendix B The two groundwater monitoring wells and eight C-SpargeTM wells were installed on March 4 through 8, 2002 Wells MW-20 and MW-21 were drilled to depths of 90 and 60 feet bgs, respectively C-SpargeTM wells SP-lA, SP-2A, and SP-3A were drilled to a depth of approximately 30 feet bgs, wells SP-113, SP-213, and SP-313 were drilled to a depth of approximately 60 feet bgs, and wells SP-1C and SP-2C were drilled to a depth of approximately 90 feet bgs A truck-mounted drill rig equipped with 8-inch-diameter hollow-stem augers was used to drill all wells A GR geologist observed the drilling activities For wells MW-20 and MW-21, soil samples were collected at five-foot intervals for description and preparation of a log, and for possible chemical analysis Soil samples were not collected from the C-SpargeTM well borings Locations of newly installed wells are shown on Figure 2 Boring logs and copies of the Well Completion Reports are included in Appendix C is 24007206-1 3