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fit)rn <br /> AN Ms Lon Duncan <br /> May 20, 1999 <br /> Page 5 of 6 <br /> • groundwater samples are summarized in Table 3 Laboratory reports and chain of custody <br /> documentation are included to Attachment 2 <br /> 5.0 CONCLUSIONS AND RECOMMENDATIONS <br /> 5.1 Conclusions <br /> • Soil beneath the former UST has been significantly impacted by petroleum hydrocarbons, <br /> solvent related VOCs, and lead Impacted soil extends vertically from approximately 5 feet bgs <br /> to at least 31 feet bgs <br /> • The vertical extent of soil contamination has been defined No contaminants were detected at a <br /> depth of approximately 36 feet bgs <br /> • Soil contamination extends laterally at least 15 feet to the northwest, where impacted soil was <br /> encountered at approximately 16 feet bgs and extended to approximately 26 feet bgs No soil <br /> contamination was detected at 30 feet bgs in this location <br /> • Soil contamination appears to be limited to the southwest No soil contamination was detected <br /> in soil samples collected from boring SB2, located approximately 20 feet southwest of the <br /> former UST <br /> • Due to the relative immobility of lead and laboratory evidence of vertical attenuation, the <br /> volume of soil impacted by lead appears to be somewhat limited <br /> • Evidence of groundwater was initially encountered at a depth of approximately 23 feet bgs and <br /> recovered to approximately 12-16 feet bgs Laboratory analyses confirmed that groundwater <br /> beneath the site has been impacted in the vicinity of the former UST excavation at levels that are <br /> indicative of floating product <br /> Groundwater contam nation extends at least 15 feet northwest of the former tank, but less than <br /> 20 feet southwest of the former UST, confirmed by laboratory analyses Z No o� sem,.-�4,srs�z <br /> • The lateral extent of soil and groundwater contam�nat�on has not been completely defined No <br /> data was obtained southeast of the former UST <br /> 5.2 Recommendations <br /> Based upon field and analytical data collected during this investigation, Ground Zero recommends <br /> the following additional work <br /> • Advance additional bonng(s) southeast of the former UST excavation to investigate the lateral <br /> extent of soil and groundwater contamination in that direction <br /> • Advance additional bonng(s) north of boring SB 1 to investigate the lateral extent of soil and <br /> groundwater contamination in that direction <br /> • Install a minimum of three groundwater monitoring wells in the vicinity of the former UST <br /> excavation to determine the local groundwater gradient and to investigate the lateral extent of <br /> groundwater contamination at the site <br /> is <br /> gr0Undzelgabbardlsumrpt doc <br />