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The analytical results for the samples are presented in boldface type in Table 1, along with <br /> previous data The laboratory analytical report and chain-of-custody documentation are included <br /> as Appendix B <br /> Detectable concentrations of TPH-g in the samples ranged from 71 ug/L (MW7) to 72,000 µg/L <br /> (V3) The concentration of TPH-g in the sample collected from MW8, located adjacent to the <br /> Shell service station and upgradient of the site, was 42,000µg/L Detectable benzene <br /> concentrations ranged from 9 3 ,ug/L (MW4) to 1,700 MglL (RW4) MTBE was detected in <br />' samples at concentrations ranging from 13 µg/L (P2) to 1,800 ,ug/L(MW 10) Groundwater <br /> sample analytical results are shown in Figure 1 <br /> 3. SOIL VAPOR EXTRACTION AND TREATMENT SYSTEM <br /> A vapor extraction system (VES) has been operating at the site since May 1994 The system was <br /> shut down in November 1996 to allow for installation of a groundwater remediation system <br /> (UVB) The UVB system began start-up on 6 February 1997 <br /> Details of the installation and operation of the UVB system will be submitted in a separate report <br /> Starting in the next quarter, the vapor extraction system will run concurrently with the UVB <br /> system, following a modification to the system manifold Tables of the past performance of the <br /> VES are included in Tables 2 and 3 of this report <br /> 4 WORK PROPOSED FOR NEXT QUARTER <br /> Groundwater elevations will be measured and groundwater samples will be collected in May <br /> 1997 The samples will be analyzed for TPH-g, BTEX, and MTBE <br /> Because of the proximity of wells IW1 and MW4, well P1 is sampled only twice a year <br /> Similarly, because of the proximity of wells IW 1 and RW2, well MW2 is sampled only twice a <br /> year On the same basis, well MW 1 is sampled only twice a year, because of its proximity to <br /> well P2 Because concentrations of petroleum hydrocarbons in wells MW 12 and MW 13 have <br /> been consistently below method detection limits for at least the last eight quarterly sampling <br /> events, those wells will only be sampled once a year <br /> The UVB system will be operated and monitored and results reported <br /> WP61 73942Q297 TX 3 2 <br />