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' Mr John Benedict Project 880039 IA October 25, 2001 ' Page 3 rThe groundwater samples were analyzed at Sequoia Analytical in Sacramento, California, for TPH-g using U S Environmental Protection Agency (USEPA) Modified ' Methods 8015, and for BTEX and MTBE using USEPA Method 8020 Copies of the chain-of-custody records and laboratory analysis reports are presented in Appendix C ' The results of laboratory analyses indicated that dissolved hydrocarbons were present in all three wells TPH-g was detected in MW-1R, VW-2, and VW-3 at a concentrations of 114, 38,600, and 9,930 micrograms per liter (µg/L), respectively Benzene, toluene and ' ethylbenzene were not detected in MW-1R Benzene was reported in VW-2 and VW-3 at 3,230 and 1,570 µg/L, respectively MTBE was below laboratory reporting limits in all three wells Results of laboratory analyses are summarized in the Table 1 The results of the point monitoring were used to evaluate the groundwater gradient The ' gradient is approximately 0 003 foot per foot to the southeast (Figure 2) Groundwater analytical data for the subject site and for the former ARCO facility 2168 are also summarized on Figure 2 1 � REMEDIATION SYSTEM STATUS: SECOND QUARTER 2001 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 ' Catalytic Oxidizer rated at 100 cubic feet per minute (cfrii) Startup of the remediation system occurred on February 3, 2000, under the supervision of regulatory personnel Subsequently, IT staff perform weekly system O&M, collect influent and effluent air samples monthly in accordance with air board permit requirements, and reports quarterly to the air board Sampling Results During the second quarter 2001, soil vapor samples were collected from influent and ' effluent sample ports on April 2, May 21, and June 4, 2001 The samples were submitted to Sequoia Analytical in Sacramento, California, a state-certified laboratory, for analysis of TPH-g and BTEX using USEPA Methods 8015 and 8020, respectively Influent TPH-g concentrations on April 2, May 21, and June 4, 2001 were reported to be 112, 847 and 120 milligrams per cubic meter (mg/m), respectively The corresponding ' effluent TPH-g concentrations were 13 5, <10 0 and<2 0 mg/m3, respectively it CORPORATION SAC111SACRFPIICOMMON1sacDP120011PRAPI818800391A lac doc-ONt 1 1