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EPA COMMENTS <br /> ON THE DRAFT FINAL WELL EVALUATION <br /> AND ABANDONMENT ENGINEERING REPORT (SEP-92) <br /> DDRW-TRACY <br /> GENERAL COMMENTS <br /> Organochlorine pesticide contamination in the Lower Tulare <br /> should be addressed in the Comprehensive Remedial Investigation <br /> and Feasibility Study (RI/FS) being performed for DDRW-Tracy. <br /> The approach to addressing this concern should be described in <br /> one of the upcoming addenda to the Comprehensive RI/FS work plan. <br /> The Well Evaluation and Abandonment Report recommends <br /> further investigation of the Lower Tulare by installing and <br /> sampling two monitoring wells about 100 feet downgradient of <br /> recently abandoned Well 1. A regional presence of these <br /> contaminants has been noted by the RWQCB. <br /> Prior to installing additional wells in the lower Tulare, <br /> EPA suggests that DDRW-Tracy: <br /> investigate all potential surface and subsurface <br /> organochlorine pesticide source areas and evaluate <br /> organochlorine pesticide values to determine potential <br /> impacts beneath DDRW-Tracy in both the Upper and Lower <br /> Tulare. <br /> sample and analyze for organochlorine pesticides in <br /> groundwater from selected off-site wells screened in <br /> the Lower Tulare to verify the existence of a regional <br /> pesticide plume in the vicinity of DDRW Tracy and to <br /> assist in determining the groundwater gradient of the <br /> Lower Tulare (Note: Groundwater well surveys have been <br /> conducted and presented in previous documents, however, <br /> there is no indication that organochlorine pesticide <br /> analysis has ever been performed on groundwater samples <br /> from these off-site wells [WCC-Feb. 1991, WCC-Feb. <br /> 1992] . ) <br /> • Compile analytical data which may exist in other <br /> investigations (e.g. , RWQCB) to document a regional <br /> organochlorine pesticide plume in the Lower Tulare in <br /> the area of DDRW-Tracy. <br /> The upcoming work plan addenda and the Comprehensive RI/FS <br /> are the appropriate mechanisms for DDRW-Tracy to (1) provide for <br /> a unified approach to address the subject of potential <br /> contamination in the Lower Tulare, (2) to summarize existing <br /> data, and (3) obtain regulatory concurrence on any decisions to <br /> 1 <br />