Laserfiche WebLink
EPA' S COMMENTS ON THE <br /> DRAFT FEASIBILITY STUDY (JUNE-92) FOR OPERABLE UNIT #1 <br /> DDRW-TRACY, CALIFORNIA <br /> GENERAL COMMENTS <br /> 1. Subsequent to the RI investigation and the drafting of the <br /> RI report, DLA has raised questions regarding the <br /> representativeness of the total metals ground water data <br /> which indicate elevated levels of metals associated with <br /> suspected sources of contamination. DLA's concerns are <br /> based on the sampler' s qualitative observations of turbidity <br /> at the time samples were taken. The current metals data <br /> base in the RI for OU-1 document a health threat associated <br /> with metals in ground water. However, the draft FS <br /> concludes that, due to the uncertainties regarding this <br /> data, metals contamination will be addressed in the <br /> subsequent Comprehensive RI/FS (draft Comprehensive FS <br /> currently scheduled for December 6, 1993) . Consequently, <br /> the draft FS for OU-1 does not present a plan of remedial <br /> action for metals. <br /> This "redefinition" of OU-1 to exclude metals from <br /> consideration at this time results in a fundamental <br /> disconnect between the OU-1 RI and the OU-1 FS. <br /> Although partly explained in the text of the current <br /> draft FS, the change in definition for OU-1, the <br /> rationale for the change, as well as how and when the <br /> question of metals contamination will be addressed, <br /> needs to be more strongly emphasized and explained in <br /> the Executive Summary, the Introduction, and the <br /> sections addressing Nature and Extent of Contamination <br /> and the Risk Assessment. <br /> Additionally, it will be necessary for the FS to <br /> describe the steps to be taken to assure that metals <br /> contamination will be appropriately addressed should it <br /> be present in the extracted ground water. The FS <br /> should state how the ground water will be monitored; <br /> include concentrations which will not be acceptable for <br /> the organics treatment process and/or for injection to <br /> the aquifer. The FS should also discuss what will <br /> occur if metals are detected in unacceptable levels in <br /> the effluent. <br /> 2 . The redefinition of OU-1 discussed above does not exclude <br /> the other volatile organic compounds (VOCs) listed as <br /> chemicals of concern in the RI . However, as currently <br /> written, the draft FS does not address contamination other <br /> 1 <br />