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drilled out. Since there was no detection of bromoform in <br /> Well 2 samples, it is again assumed that the drilling fluid <br /> sample was retrieved after the fluid was pumped into a <br /> holding tank, where it may have been contaminated, after <br /> drilling of Well 2 . Field operations for the abandonment of <br /> Well 1 did not begin until June 8 . <br /> • An explanation of the chronology of this field <br /> procedure is needed, as well as the significance of <br /> these bromoform results which have not been reported <br /> elsewhere in groundwater analyses at DDRW-Tracy. <br /> 6. The results of analyses of groundwater which showed the <br /> presence of 4 , 4 ' -DDD, and 4, 4 ' -DDE above EPA Action Levels <br /> (AL) in the groundwater samples retrieved from Well 1 are <br /> noted. Dieldrin, a Class B2 carcinogen, was also detected <br /> in these samples at significant levels. The 10-6 risk level <br /> for Dieldrin is defined as . 002 µg/L. <br /> 7 . The results of analyses on two soil samples, or drill <br /> cuttings as they are alternately called, from Well 1 (20 <br /> feet) and Well 1 (650 feet) are reversed in Table 5. 1. The <br /> laboratory analysis sheets showed that benzene and o-xylene <br /> were actually detected in the sample retrieved from a depth <br /> of 650 feet, not 20 feet. Because the sample from 650 feet <br /> was retrieved from well below the piezometric surface, these <br /> results are significant in the evaluation of the possible <br /> impact on the groundwater from these constituents. Since <br /> the analysis of the sample retrieved from 20 feet in Well 1 <br /> was performed 39 days after sample retrieval (25 days beyond <br /> holding time) , no determination is possible as to whether <br /> the benzene and 0-xylene may have come from a nearby source. <br /> SPECIFIC COMMENTS <br /> 1. Section 3, Table 3-2 <br /> Table 3-2 differs in some, perhaps insignificant, details <br /> from corresponding Table 5-3 from the Final Work Plan. Some <br /> of the extraction/preparatory methods differ. However, all <br /> methods applied appear to be adequate. <br /> Two details in Table 3-2 need corrections: <br /> • The Department of Health Services (DHS) Leaking <br /> Underground Fuel Tank (LUFT) method was used as the <br /> preferred extraction procedure for total petroleum <br /> hydrocarbons (TPH) analyses in water samples. <br /> • Since semi-volatile analyses (EPA Methods 3520/8270) <br /> were used on groundwater samples, these methods should <br /> be included in Table 3-2 . <br /> 2 <br />