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i .y. <br /> La. - <br /> Doug Westerhaven Page 2 <br /> PHS/EHD recommends analysis of the remaining AFPC on site monitoring wells by EPA method 8010 to <br /> determine the onsite extent of the chlorinated hydrocarbon plume prior to initiating an investigation for an off <br /> site source. <br /> The most significant element of concern at this site is the potential for groundwater to return to the recorded <br /> depth of 35 feet in 1987. The Dames and Moore report elated August 1994 modeled contamination with the <br /> depth to groundwater at 35, 54 and 70 feet. The model suggested contamination by napathlene of 36.5 ppb, <br /> 2.98 ppb and .172 ppb respectively. The text of the report indicated that.ground water would remain at 70 <br /> feet for 25 years. The model of groundwater at 54 feet below grade was considered conservative based on <br /> long term trends and the 35 foot model was run at the request of PHS/EHD. Current groundwater depth is <br /> 60 feet. <br /> i <br /> In conclusion PHS/EHD has recalculated the total designated level of diesel; determined that there is evidence <br /> of a chlorinated hydrocarbon plume in the area of the former waste oil tank and observed the depth to <br /> groundwater fluctuation of 40 feet from 1987 to the present creating a significant element of concern for I <br /> modeling the proper amount of remaining soil contaminated with Diesel which may be left in place without <br /> degrading water quality. <br /> PHS/EHD recommends the analysis of DMW-1 through DMW 5 for chlorinated hydrocarbons using EPA <br /> method 601 in addition to BTEX using EPA method 602 and TPH-d using GCFID with a 3510 extraction <br /> during the next scheduled quarterly monitoring. PHS/EHD shall be notified 48 hours prior to the next <br /> quarterly monitoring which should be scheduled to occur prior to September 30, 1995. <br /> For further information please contact Steven Sasson at (209) 468-3459. <br /> Donna Heran, REHS, Director <br /> Environmental Health Division <br /> Steven Sasson, Senior REHS Diane M. Hinson, REHS <br /> Site Mitigation Unit Supervisor <br /> SS <br /> c: Elizabeth Thayer, CVRWQCB <br /> c: John Menke, Dames and Moore <br /> C, Bernie Sloop, American Moulding and Millworks <br />