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■ Z1 INC <br /> • The additional site characterization activities (WZ1, 1993) which are summarized in Exhibits <br /> 3 through 8, consisted of 1) inclined soil boring AB-3 (included in this report in Appendix <br /> 111) and two vertical sod borings (T-4, T-6 in Appendix Ill) adjacent to the concrete tank <br /> that were advanced to a total depth of 47 feet below ground surface (Exhibit 5), 2) three <br /> shallow sod borings (D-6, D-7, D-8 in Appendix III) to a maximum depth of 16 5 feet below <br /> ground surface at Area"D"where previous data indicated that trace to minor hydrocarbon <br /> and chlorinated hydrocarbon compounds impacted the shallow subsurface from surface <br /> spillage, and 3) exploratory excavation of three shallow trenches to a depth of 7 feet to <br /> investigate shallow hydrocarbon sod impact from surface spillage at Area "A" <br /> 1111. PROPOSED REMEDIAL ACTION PLAN <br /> The proposed Remedial Action Plan only addresses the diesel hydrocarbon-gasoline, and <br /> oil and grease hydrocarbon contamination Because of the relative immobility of the <br /> heavy fraction hydrocarbons and distance of over 35 feet between identified base of <br /> contamination and current depth to ground water at 55 feet, no ground water <br /> investigation for hydrocarbon compound impact on local ground water is believed <br /> warranted Chlorinated hydrocarbon contamination will only be addressed as it impacts <br /> the aeration and waste disposal permuting of the diesel and oil and grease contamination <br /> The potential impact to local ground water due to chlorinated hydrocarbons is not part <br /> of this proposed remedial action plan It will be addressed separately <br /> The average concentrations of heavy fraction hydrocarbon compound impacted sod is <br /> estimated at 500 to 2,500 parts per million All significant heavy fraction hydrocarbon <br /> impacted sod consists primarily of diesel fuel and oil and grease Volatile hydrocarbon <br /> concentrations (TPH-G) of impacted sod are estimated to average 100 ppm based on <br /> subsurface sampling and are estimated to affect approximately 450 cubic yards of soil <br /> i <br /> Page 2 <br />