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EPA Review of the Draft DDJC-Tracy Well Monitoring Program, 2001 Annual Monitoring Report, December 2001 GENERAL COMMENTS 1. The Draft Well Monitoring Program 2001 Annual Monitoring Report for the Defense Distribution Depot San Joaquin California, Tracy Site, California (the Report) reports many of the same problems that were included in the Annual Monitoring Reports from the previous two years. Contaminant capture by the groundwater extraction system is still incomplete due to reduced or lack of pumping in some wells. Capture of the trichloroethene (TCE) plumes has decreased compared to the 2000 Annual Monitoring Report. The communication problem between Groundwater Treatment Plant (GWTP) 1 and many extraction wells, first observed in March 2000, continues to cause the system to be operated in manual mode only. Significant downtime occurs when the plant is not staffed (e.g., nights, weekends and holidays). No date has been set for the scheduled repairs. The limited effluent pump capacity at GWTP2 appears to have not been addressed, although a scheduled repair date was provided. There is a possibility that continued lack of progress may result in unfavorable findings during the five-year review in 2004.;Please revise the Report to include a proposed schedule for bringing the extraction and treatment systems to full design operation. In addition, please add a table that reviews the progress on last year's recommendations and plan to provide a table in the 2002 Annual Monitoring Report that discusses progress made on the recommendations made in this year's Final 2001 Annual Monitoring Report. 2. The reporting of dioxins/furans in the Report is unclear. Table 4.1-2 shows no established maximum contaminant level (MCL) for dioxins/furans, although there is a primary MCL of 0.00003 micrograms per liter(ug/L) established for 2,3,7,8- tetrachlorodibenzo p-dioxin (TCDD). It is common practice to multiply detected dioxin/furan congeners by a toxicity equivalency factor (TEF) and compare the sum of the corrected congeners to the standard for 2,3,7,8-TCDD, the most widely studied congener. On the other hand, Table 4.8-1 shows the "Groundwater Concentration Requiring Evaluation" for total dioxins/furans of 0.01 ug/L, but lists the individual congeners with units of nanograms per liter (ng/L). In addition to the individual congeners, the total dioxins and furans from a given sampling event should also be reported in the table, without correction by a TEF, using the same units for the reported concentrations and the Groundwater Concentration Requiring Evaluation. Please revise the presentation of dioxins/furans to include the TEF-corrected sum of congeners for comparison to MCL and total dioxins/furans for comparison to Groundwater Concentration Requiring Evaluation. 1