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b1(- 0%TC <br /> � <br /> A S S O C I A T 1_ 8 1 N C <br /> = (6.300+4.000+3.500)13,] %TPHq x 1 kg x 3.78.1=. x 6,850 gal <br /> 1"LWater 1,,000,000,000,ug 1 gal 1 day <br /> = 0.12.ka TPHa x 2.2 Ib = 0.26 pounds of TPHg removed per day <br /> day 1 kg <br /> Concentration of benzene in groundwater sample <br /> = (19+13+9.9)/3-ucLTPHq x 1 kg x 3.78 L _ x 6.850 gal <br /> 1 L Water. 1,000,000,000 ug 1 gal 1 day <br /> k = 0.0004 k benzene x 2.2 lb = 0.0008 pounds of MTBE removed per day <br /> Li <br /> day 1 kg <br /> 4.0 DISCUSSION <br /> The groundwater extraction pilot'test yielded a pumping rate of approximately 4.76 gpm and a <br /> L' ROI of up to 85 feet. As discussed in Section 3.5, approximately 0.52 pounds of TPHg and <br /> 0.002 pounds of benzene were removed during the 48-hour groundwater pumping pilot test. <br /> Assuming that a permanent groundwater extraction well and pump were to be installed just south <br /> of the former tank excavation, the ROI would extend beyond the eastern edge of the site beneath <br /> Locust Avenue and the northern edge in the downgradient direction. Installation of a <br /> groundwater extraction well near the southern edge of the former tank excavation and treatment <br /> 1 system would likely prevent additional impacted groundwater from migrating off-site. <br /> 5.0 RECOMMENDATIONS <br /> ATC Associates recommends preparing a Corrective Action Plan. In the plan, bioattenuation, <br /> groundwater extraction, and air sparge methods will be considered. Upon regulatory concurrence <br /> L of the preferred remedial action method and client approval, ATC Associates will prepare and <br /> submit a final remediation plan, which will include a conceptual design of the remediation system. <br /> ATC will continue to monitor wells MW 1 through MW3 quarterly. <br /> r <br /> a <br /> �f <br /> w:lwordpro11498I\reportslpump tes1.doo 5 <br />