Laserfiche WebLink
Mr. Maurice Benson - 2 - 21 January 2011 <br /> Defense Logistics Agency <br /> The Draft Plan sets the Warning Level concentrations at promulgated maximum <br /> contaminant levels (MCLS) for the VOC constituents and the aquifer cleanup level (ACL) <br /> for dieldrin published in the Tracy site ROD documents. However, when a COC <br /> concentration in a private well reaches an MCL or ACL, contingencies for water supply <br /> replacement should be implemented. In addition to establishing COC Levels that require <br /> immediate supply of alternate water for users of private wells, the Final Plan should <br /> establish concentrations that would trigger more frequent monitoring. Also, the <br /> contingency plan should set a realistic time schedule for DLA to supply bottled water, and <br /> provide an alternate water source or wellhead treatment. DLA should also designate guard <br /> wells that would trigger more frequent monitoring of private wells, and would trigger an <br /> evaluation study for water supply replacement in the event that a private well becomes <br /> impacted in the future. <br /> The Final Plan should be structured similar to the June 2010 Final Off-Depot Potable Well <br /> Contingency Plan for the DLA Sharpe depot in Lathrop. As you know, that plan <br /> establishes three Levels for each COC in a private well: Notification Level, Trigger Level, <br /> and Action Level. If confirmation sampling of any private well exceeds one of these Levels, <br /> a pre-defined action plan is set into motion. The actions range from increased monitoring <br /> frequency to water supply replacement. <br /> If you have any questions, please contact me at (916) 464-4675, or by email at <br /> jbrownell@waterboards.ca.gov. <br /> James R. Brownell, P.G. <br /> Engineering Geologist <br /> cc: Mr. Phillip Ramsey, USEPA Region 9, San Francisco <br /> Mr. Christopher Sherman, DTSC Region 1, Sacramento <br /> Mr. Harlin Knoll, San Joaquin County Environmental Health Department <br /> Mr. Charles O'Neil, HDR, Folsom <br /> Mr. Michael Thomas, URS, Sacramento <br /> Mr. David Hofmann, Booz, Allen, Hamilton Inc., San Antonio, Texas <br /> California Environmental Protection Agency <br /> ec1 Recycled Paper <br />