SITE INFORMATION AND CORRESPONDENCE FILE 1

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PUBLIC REALTH SERNICES aQ,4�IN �o SAN JOAQUIN COUNTY ENVIRONMENTAL HEALTH DIVISION Karen Furst, M.D., M.P.H., Health Officer �•.. �� 304 East Weber Avenue, Third Floor • Stockton, CA 95202 L E C O 209/468-3420 JOHN PARKER NOV 12 1998 2151 COUNTRY CLUB BLVD STOCKTON CA 95204 RE: Boulevard Auto Service SITE CODE: 2424 2151 Country Club Blvd. Stockton, CA., 95204 San Joaquin County Public Health Services, Environmental Health Division (PHS-EHD), has reviewed the "Work Plan Addendum - October 14, 1998" that was submitted by Advanced Geo Environmental Consultants on October 27, 1998 and has the following comments. The soil sample collection proposal states, "At least one soil sample from each boring will be submitted for laboratory analysis". This sampling proposal is unsatisfactory and will require a revision. PHS-EHD will require at least three soil samples from each boring (ie., monitoring, vapor, or air sparge well) to be submitted for laboratory analyses. Soil samples to be analyzed shall be collected from the current vadose-saturated interface and two that confirm vertical delineation (minimum depth, determined by historical drought depth to water of 25' to 30' below ground surface). All soil samples shall be analyzed for Total Petroleum Hydrocarbons as Gasoline and Diesel, Benzene, Toluene, Ethyl-Benzene, Xylene, and the seven oxygenates noted in the enclosed PHS- EHD policy. Additional soil samples may be required to be analyzed if the PHS-EHD inspector onsite during the drilling activities observes significant changes in the subsurface conditions. Monitoring well construction details included in your consultants proposal will need to revised. The proposal to place the sand filter pack three feet over the screen interval is excessive and unacceptable. A maximum of two feet of sand is to be placed over the screened interval of the well casing. The upper bentonite (sanitary) seal shall not be more than two feet above the top of the filter pack. In Section 2.3 of the workplan, "at least one ground water monitoring well is proposed as a dual-completed in-situ air sparging (IAS)/soil vapor extraction (SVE) well". PHS-EHD is unclear how a "dual-completed' in-situ IAS-SVE well can also serve as a monitoring well. The proposed fifteen feet (15') of deep screened interval in the dual casing well is too long. This deep screened interval, whether for an air sparging or monitoring well, should not be greater than five feet in total length. This deep casing should be installed within the most permeable soil layer at, or closest to, the 1978 historical drought depth to first groundwater. Please have your consultant clarify how each casing of the "dual- completed welr can function for three purposes. A Division of San Joaquin Counry Health Care Services