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1 <br /> 4.2 Laboratory Analysis of Groundwater Samples <br /> 1 No petroleum hydrocarbons were detected in samples from MW-5, MW-6, MW-7 or MW-8. <br /> TPH as gasoline was detected in samples from MW-i and MW-4 at concentrations of 9,200 <br /> Ag/L (ppb) and 130 ppb, respectively. Benzene, toluene, and xylenes were detected in <br /> samples from MW-1 and MW-4. Ethylbenzene were detected only in the sample from MW- <br /> 1. The analytical results of all water samples are summarized in Table 2. The laboratory <br />' report and chain-of-custody are included in Appendix B. <br />' 5.0 CONCLUSIONS & RECOMMENDATIONS <br /> 5.1 Hydrocarbon Impacted Groundwater <br /> Petroleum hydrocarbons continue to fluctuate greatly in MW-1. Between June 1994 and <br /> October 1994, TPH concentrations in MW-1 decreased from 88,000 ppb to 9,200 ppb. A <br />' less dramatic decrease in TPH concentrations was observed in MW-4 (from 440 ppb to 130 <br /> ppb). No apparent pattern can be seen from the existing data. <br /> 1 Benzene, toluene and xylenes have been detected only intermittently in MW-5; TPH has not <br /> been detected in MW-5 since October 1992. However, no petroleum hydrocarbons were <br />' detected in MW-5 during the October 1994 sampling. Wells MW-5, MW-6, MW-7 and <br /> MW-8 continue to delineate the impacted groundwater at the site. <br /> Groundwater flow direction has been consistently south/southwest since the installation of <br /> MW-6 through MW-8 in April 1993. However, the mounding effect observed near MW-1 <br /> may have given erroneous flow direction information before the installation of MW-6 <br />' through MW-8. <br /> Since no petroleum hydrocarbons have ever been detected in MW-6, MW-7 or MW-8 and <br />' a reliable flow direction has been determined, GeoAudit once again recommends the <br /> sampling of MW-6, MW-7 and MW-8 only on an annual basis. Groundwater depth <br /> measurements should continue on a quarterly basis in all wells. The next quarterly sampling <br />' should be scheduled for January 1994. <br />' 5.2 Soil and Groundwater Remediation <br /> GeoAudit will begin installation of the remediation system as soon as an access.agreement <br /> is obtained from the owner of the A & W site. We anticipate initiating installation <br />' procedures in January 1995. <br /> G-1.0ml A`&S.M-.N. <br /> An A A.nb ONMO-W-1.41 <br />