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903808-SS4 CON-45 detected in groundwater from 17 wells, with all results except for LM 29 (0.46 mg/1) , located in Contaminant Area 2, being below detection. The presence of TPHs in Well LM 29, which is within 50 feet of LM 39, further suggests that Contaminant Area 2 may be a source area for toluene. 4.3.5.6.3 Organochlorine Pesticides and PCBs (EPA 608) . Of the 12 locations sampled, all but one location (LM 49) was below detection for all compounds tested. The compound detected in LM 49 was dieldrin at a concentration of 0. 15 ug/l , which is only slightly above the detection limit of 0.10 ug/l . Because of the low concentration and few number of samples collected, with none being upgradient of LM 49, the presence of this compound is uncertain. 4.3.5.6.4 Purgeable Organics (EPA 624) . Acetone was detected in three wells (LM 58, LM 61, and LM 68) out of the 11 sampled for purgeable organics, with concentrations ranging from 41 to 48 ug/1 . The concentrations are believed to be laboratory artifacts rather than site- related contamination. 4.3.5.6.5 Base/Neutral , Acids and Pesticides (EPA 625) . A total of 16 monitoring wells were sampled for base/neutral , acids, and pesticides with all results being below detection except for the compound bis(2-ethylhexyl) phthalate, which is believed to be a laboratory artifact and not related to site contamination. 4.3.6 Summary of Groundwater Contamination Based on the laboratory results to date, and on the discussions of contaminant sources presented in Sections 1.2.2.3 and 4.1, a summary of the groundwater contamination level and extent is provided for each contaminant area in the sections below. 4.3.6.1 Contaminant Area 1. In evaluating Contaminant Area 1, it is convenient to divide the area into eastern and western parts by the north- south road that runs through the area approximately along the 2100 East coordinate. 4-189