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Mr Tom Busenbark Project No 880-039 lA July 9, 2003 Page 3 GROUNDWATER MONITORING: SECOND QUARTER 2003 On May 29, 2003, a Shaw employee was on-site to measure depth to groundwater and collect groundwater samples from wells MW-1R through MW-4R(D), and VW-2 through VW-4 for laboratory analyses Shaw coordinated joint quarterly sampling with the adjacent service station sites Free product was not observed in groundwater monitoring wells (see Table 1 and Appendix A) Shaw used the second quarter 2003 data to evaluate changes in concentrations of dissolved petroleum hydrocarbons in the groundwater Shaw sampling and analysis procedures are presented in Appendix B The groundwater samples were analyzed by Columbia Analytical in Redding, California, for TPHg using U S Environmental Protection Agency (USEPA) Method 8015M, and for BTEX and MTBE using USEPA Method 8260B The results of laboratory analyses indicate that TPHg were present in all wells sampled except for wells MW-2R and MW-3R, at concentrations ranging from 290 to 50,000 micrograms per liter (pg/L) Benzene was reported in wells MW-4R(S), MW4R(D), VW-2, VW-3, and VW-4 at concentrations ranging from 9 4 to 6,300 ug/L MTBE was not detected by USEPA Method 8260B in any of the seven wells sampled Copies of the chain-of-custody records and laboratory analytical report are presented in Appendix C The groundwater gradient was approximately 0 003 with groundwater flow to the east (Figure 3) Groundwater analytical data are summarized on Table 1 TPHg and benzene concentrations are shown on Figure 4 REMEDIATION SYSTEM STATUS: SECOND QUARTER 2003 The remediation system consists of four shallow zone and three deep zone soil vapor extraction (SVE) wells, from which soil vapors are extracted using a Stealth Bobcat 1 Catalytic Oxidizer rated at 100 cubic feet per minute Startup of the remediation system occurred on February 3, 2000, under the supervision of regulatory personnel Subsequently, Shaw staff perform weekly system O&M, collect influent and effluent air N\sacDP%20031PrJ\88"800391 A 3afdoc Shaw Environmental, Inc (01050000)