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1 � S E C O R Mr Ed Ralston February 12, 2003 Page 3 well Installation permits and City of Lathrop encroachment permits are included as Attachment B • Geoprobe Soil Borings The off-site exploratory geoprobe soil borings were advanced using standard direct push equipment to an approximate depth of 11 to 12 feet bgs Soil samples were collected at depths of 5 and 10 feet bgs for logging purposes with the 10 foot sample submitted for laboratory analysis A groundwater "grab" sample was collected at each geoprobe boring location via a hydropunch, driven to a depth of 15 feet bgs and screened from 12 to 15 feet bgs Boring details are included in Table 1 • Monitoring Well Installation Six off-site groundwater monitoring wells (MW-10 through MW-15) were drilled to a depth of 25 feet bgs The wells were constructed with 2-inch diameter schedule 40 PVC casing with approximately 20 feet of 0 020-Inch slotted screen material The well screen Interval extended from approximately 5 to 25 feet bgs Following installation of the wells on November 5 and 6, 2002, SECOR developed and sampled the wells on November 21, 2002 Boring and well construction details are included in Table 1 Boring logs and well construction details are included in Attachment C Field and laboratory procedures are presented in Attachment D Well development sheets, certified laboratory analytical report, and chain-of-custody documentation are presented in Attachment E • Soil Analytical Results Soil samples at 10 feet bgs from geoprobe borings GP-1 through GP-9 were collected and submitted for laboratory analysis Soil samples were analyzed for TPHg, BTEX, and fuel oxygenates (MtBE, EtBE, DIPS, TAME, TBA, EDB, 1,2-DCA, and ethanol) by EPA Method 8260B No detectable concentrations of petroleum hydrocarbons were reported in the soil samples from GP-1 through GP-9 Based on field observatation, three soil samples were collected from monitoring well MW-12 for chemical analysis Samples were analyzed for the presence of TPHg, benzene, toluene, ethylbenzene, and xylenes (BTEX), and fuel oxygenates by EPA Method 8260B Ethylbenzene, xylenes, and MtBE were reported in MW-12 at maximum concentrations of 0 73 mg/kg, 3 0 mg/kg, and 0 15 mg/kg, respectively Sod analytical results are included in Table 2 Field and laboratory procedures are presented in Attachment D The certified laboratory analytical report and chain-of-custody documentation are presented in Attachment E • Groundwater Analytical Results. Groundwater "grab" samples collected from each of the geoprobe boring locations were analyzed for TPHg, BTEX, and fuel oxygenates (MtBE, EtBE, DIPS, TAME, TBA, EDB, 1,2-DCA, and ethanol) by EPA Method 82608 TPHg was reported in four of the geoprobe locations at a maximum concentration of 17,000 ppb (GP-1), Benzene was reported in three samples at a maximum concentration of 170 ppb (GP-2) MtBE was reported in two sample at a maximum concentration of 230 ppb Groundwater samples from the newly installed wells reported concentrations of MtBE ranging from 0 51 ppb (MW-10) to 1,300 ppb (MW-12) Benzene was reported in one of the new wells at a concentration of 13 ppb (MW-12) and TPHg was not detected in the new wells Groundwater analytical results are included in Table 3 and shown on Figure 2 The certified laboratory analytical report and chain-of-custody documentation are presented in Attachment E • Stockpiled Soil Analytical Results Approximately 8 56 tons of soil were generated during assessment activities Four samples collected from the stockpiled sod were composited at the laboratory, and analyzed for the presence of TPHg, BTEX, and MtBE by EPA Method 8260B, and total lead by EPA Method 6010B Results are included in Table 4 The certified laboratory analytical report and chain-of-custody documentation are presented In Attachment E Waste disposal confirmation is included in Attachment F I%ConocoPhillipffosco Marketing112051Reports\AssmtRpt doc