SITE INFORMATION AND CORRESPONDENCE FILE 2

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, PUBLIC I-EALTH SERVII11:ES SAN JOAQUIN COUNTY ? ^ .� ENVIRONMENTAL HEALTH DIVISION ` Karen Furst, M.D., M.P.H., Health Officer 304 East Weber Avenue, Third Floor • Stockton, CA 95202 c9 'FoR� a 209/468-3420 ALEX PEREZ SEP 15 SHELL OIL COMPANY PO BOX 4023 CONCORD CA 94524 Re; Shell Service Station Site Code: 1070 2575 Country Club Stockton CA 95204 San Joaquin County Public Health Services Environmental Health Division(PHS/EHD)has reviewed the Enviros"Revised Site Assessment Work Plan"dated September 9, 1997. PHS/EHD has prepared the following comments for your consideration and response. Enviros stated that"A revised scope of work is presented to respond to SJCPHS's requests regarding the investigation. This proposed scope is presented in lieu of and supersedes the scope proposed in the August 13, 1997 addendum." Please note that PHS/EHD concurred with the drilling and the sampling of the two proposed borings to further define the vertical extent of soil contamination in the areas identified in the addendum. PHS/EHD requested additional investigation to evaluate the vertical extent of the soil and/or groundwater contamination. PHS/EHD will concur with the installation of the two newly proposed shallow monitoring wells since Enviros has expressed the belief that the contamination evidenced in the domestic well located at 2468 is the result of shallow groundwater migration. The work plan included the installation of three deep groundwater monitoring wells and reconnaissance borings drilled to evaluate lithology which will be used to determine final deep well design. PHS/EHD concurs that reconnaissance drilling will be necessary to evaluate prior to the proposal of final deep well construction designs. Inadequate information was provided with regards to the proposed depths or sampling methodology. Gregg Drilling and Gregg In-situ are two separate businesses with two separate C-57 licenses; therefore, depending on the selection of drilling contractor, an additional permit may be required. Please submit clarification regarding the selection of the drilling contractor and the tasks that the selected contractor will perform. Please submit copies of the request for a City of Stockton encroachment permit and for right of entry for access to the private road. Since Shell has already worked out with the City of Stockton what permit information will be required, the City of Stockton permitting should not take the time it has in the past, particularly if a complete permit package is submitted. It would appear that the possibility exists that there may be additional wells in the vicinity which may have not been identified in the well survey performed by Shell's previous consultant. Please prepare a description of the methodology used, if available, otherwise, please perform and submit a more thorough well survey. All off site wells with should be sampled quarterly with the owner's permission. As noted previously,all field actives which have been directed by PHS/EHD and any required feasibility studies must be completed by October 31, 1997 and a corrective action plan submitted by December 31, 1997. A Division of San Joaquin County Health Care Services