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' 25 April 2000 <br /> AGE-NC Project No. 98-0520 <br /> ' Page 6 of 7 <br /> • Depth to ground water at the site averaged approximately 18.69 feet bsg on 15 December <br /> ' 1999. <br /> • The ground water elevation was variable across the site, and the flow direction was - <br /> ' indeterminate from the 15 December 1999 data. <br /> • TPH-g was detected in ground water samples from MW-5 (former UST area) at 'a <br /> tconcentration of 31,000 ug/l. <br /> • Based on laboratory analysis of soil samples collected, petroleum hydrocarbon-impact has <br /> been defined vertically in MW-1, MW-2, and MW-3 at depths between 25 feet to'35 feet <br /> ' below surface grade(bsg).Additionally,as documented in the Preliminary Investigation and <br /> Evaluation Report dated 10 August 1999, data collected from probe boring B 1 during the <br /> preliminary site assessment suggests the vertical extent of petroleum hydrocarbon-impact to <br /> ' soil beneath the former area USTs is between 25 feet to 35 feet bsg. <br /> • TPH-g was detected in all five ground water monitoring wells on-site. Further lateral <br /> ' definition is necessary to determine the horizontal extent of hydrocarbon-impacted ground <br /> water. <br /> 6.0. RECOMMENDATIONS <br /> ' Based upon data collected from the site, AGE recommends: <br /> ' • Further site assessment to determine the lateral extent of petroleum hydrocarbon-impacted <br /> and TBA-impacted ground water. <br /> ' • Installation of a minimum of five ground water monitoring wells to define the plume of <br /> impacted ground water. Proposed monitoring well locations are presented on Figure 2. <br /> • Continued quarterly ground water monitoring. <br /> 1 . <br /> ' 7,0. LIMITATIONS <br /> Our professional services were performed using that degree of care and skill ordinarily exercised by <br /> ' environmental consultants practicing in this or similar localities.The findings were based upon field <br /> measurements and analytical results provided by an independent laboratory. Evaluations of the <br /> geo logic/hydro geologic conditions at the site for the purpose of this investigation are made from a <br /> ' limited number of available datapoints (i.e. soil borings and ground water samples) and subsurface <br /> conditions may vary away from these data points.No other warranty,expressed or implied, is made <br /> ' Advanced GeoE ovi ronmental,Inc. <br /> 1 <br />