SITE INFORMATION AND CORRESPONDENCE

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r Mr. Joe Herrud, LeprinRoods - 2 - • 4 December 2013 Leprino Facility, 2401 MacArther Drive, Tracy Central Valley Water Board staff have reviewed Leprino's closure request. For Leprino's information, the following is a summary of the Water Code and other applicable requirements which must be met in order for the Central Valley Board to find that "No Further Action' is necessary at a site: Pursuant to Section 13304 of the California Water Code, when waste from a diesel spill has been discharged to the groundwater, or deposited into the soil such that it is, or probably will be, discharged to the groundwater, where such waste creates, or threatens to create, a condition of pollution or nuisance, the discharger can be required, by order of the board, to clean up the waste, or abate the effects of the waste. State Water Resources Control Board's Resolution 92-49, at Section III.G.3, states that the Regional Water Board "shall...ensure that dischargers are required to cleanup and abate the effects of discharges in a manner the promotes attainment of either background water quality, or the best water quality which is reasonable if background levels of water quality cannot be restored...in approving any alternative cleanup level less stringent than background...any such alternative cleanup level shall...not result in water quality less than that prescribed in the Water Quality Control Plan and Policies adopted by the State and Regional Water Boards". The Water Quality Control Plan (also known as the Basin Plan) adopted by the Central Valley Water Board prescribes the following water quality objective for ground waters: "Ground waters shall not contain taste- or odor-producing substances in concentrations that cause nuisance or adversely affect beneficial uses". Ground waters at the Site are designated for use as a municipal or domestic water supply. The taste and order threshold for diesel pollution in drinking water has been determined to be 100 micrograms per liter. In addition, State Water Resources Control Board's Resolution 92-49, at Section IIIA, states that the Regional Water Board "shall... concur with any investigative and cleanup and abatement proposal which the discharger demonstrates and the Regional Water Board finds to have a substantial likelihood to achieve compliance, within a reasonable time frame, with the cleanup goals and objectives that implement the applicable Water Quality Control Plans and Policies" (emphasis added). Leprino's request for closure fails to demonstrate that performing no further cleanup actions at the Site will have a substantial likelihood to achieve the cleanup goal for diesel of 100 pg/L within a reasonable time. Specifically: 1. The request for closure does not include an estimate of when remaining Site groundwater concentrations will reach the water quality objectives (WQOs). Site groundwater concentration levels need to show a downward trend such that the WQOs will be achieved within a reasonable timeframe. In order to make such a demonstration, Leprino will need to continue to collect groundwater monitoring data in order to evaluate the trends associated with concentration levels of the residual diesel pollution in groundwater.