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. Mr Ron Rowe February 24, 1999 Page 5 of 6 (<0 020 ppm) and 40 feet bgs (<1 0 ppm) Analytical results of the groundwater sample collected at a depth of 65 feet from SB2 indicated that elevated levels of gasoline petroleum hydrocarbon constituents remain in the vicinity of the former USTs Benzene was detected at 910 parts per billion (ppb), ethylbenzene was detected at 380 ppb, toluene was detected at 430 ppb, total xylenes were detected at 830 ppb, TPHg was detected at 9,600 ppb, and MTBE was detected at 620 ppb Soil and groundwater analytical results for BTEX and TPHg are summarized in Table 1 Analyses for gasoline oxygenate additives are summarized in Table 2 Laboratory reports and chain-of-custody documentation are included in Attachment C SUMMARY AND CONCLUSIONS • Groundwater beneath the site occurs at a depth of approximately 62 to 65 feet bgs • No details regarding construction of the existing water supply well are available • No water sample can be collected directly from the site well until downhole equipment is removed to allow access • The nearest known downgradient water supply well is located approximately 600 feet . northeast of the site o Relatively low levels of petroleum hydrocarbons, including benzene and MTBE, were detected in soil to a depth of at least 72 feet bgs in the vicinity of the former USTs o No TPHg or BTEX were detected in samples collected beneath the former dispenser island However, MTBE was detected at levels ranging from 0 22 to 12 ppm o A groundwater sample collected from approximately 65 feet bgs in the vicinity of the former USTs contained petroleum hydrocarbon constituents, including benzene at 910 ppb and MTBE at 620 ppb RECOMMENDATIONS C � S Based upon field and analytical data collected during this investigation, Ground Zero recomme• �d,s� the following �L�l�c e.S Cb to Y 2 '� • Remove the downhole equipment from the site water supply well and investigate the well using 1( vtd o meo me ethods to determine construction details and evaluate the integrity of the well, • ect a ter sam 1 from the site water supply well once do nh le a uipm nt is wa p� removed for a eum hydrocarbon constituents, Determine th verti al�eltent`' f soil contamination to the vicinity of the USTs and investigate the lateral extent of soil contamination at the site in the north and east directions, • Install 0 ree roun wa er monitorin wellsl o confirm groundwater impacts to the site, to investigate the lateral extent of dissolved petroleum hydrocarbons, and to determine local . / -o Gfy1k & groundz Itukburglimti rt doe I