SITE INFORMATION AND CORRESPONDENCE FILE 1

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PUBLIC nEALTH SERVICES U, AI SAN JOAQUIN COUNTY ENVIRONMENTAL HEALTH DIVISION y I Ernest M. Fujimoto, M. D., M.P.H., Acting Health Officer 304 East Weber Avenue, Third Floor • Stockton, CA 95202 �.� _ i;F6R` 209/468-3420 L, U BRETT HUNTER APR G 7 697 CHEVRON USA PO BOX 5004 SAN RAMON CA 94583-0804 Re: Ron's Chevron Site Code: 1039 139 South Center Stockton CA 95202 San Joaquin County Public Health Services, Environmental Health Division (PHS/EHD) has completed review of the recently submitted "3,d Quarter 1996 Monitoring Report" dated November 7, 1996 and the "4th Quarter 1996 Monitoring Report" dated December 5, 1996, both of which were prepared by Blaine Tech. As PHS/EHD indicated in correspondence dated February 7, 1997 quarterly reports should be submitted within 45 days following the completion of field activities. PHS/EHD has prepared the following comments for Chevron consideration and response. Chevron stated in the cover letters dated February 28, 1997 for the above mentioned reports that the screened interval for all of the wells were submerged but that trends had been established that indicated that concentrations detected in the downgradient wells were either decreasing or were relatively stable indicating that the plume is not migrating. Chevron further requested that wells MW1, MW2, MWS, MW6, and MW7 be sampled and gauged semi-annually instead of quarterly and that monitoring of MW3 and MW4 be discontinued entirely and that analytical results be submitted in an annual report without potentiometric surface maps. Chevron requests are denied. The concentrations evidenced in the most recently installed (11/30/95) downgradient well, MW7, that was first sampled as a completed well on May 16, 1996, do not suggest that the plume is stable and that it is not migrating. PHS/EHD has directed Chevron since August 23, 1991 to install the groundwater monitoring wells necessary to define the extent of groundwater contamination. PHS/EHD requested in correspondence dated December 13, 1995 that any additional groundwater monitoring wells necessary to define the extent of the groundwater contamination plume be installed by May 1, 1996. Sufficient wells to determine the extent of the groundwater contamination plume have not been installed as directed. PHS/EHD in correspondence dated August 26, 1996 requested that the work plan to complete contaminant characterization be submitted by September 27, 1996 and that a copy of the Caltrans encroachment permit application be included. The work plan submitted and the addendum failed to respond to PHS/EHD's directives that the addendum include a scope of work necessary to also evaluate remedial alternatives. Pacific Environmental did include a copy of the Caltrans permit application that was dated September 24, 1997 which PHS/EHD assumes must already have been issued. In response, PHS/EHD in correspondence dated Feb 7, 1997, directed that a map locating the additional groundwater monitoring well be submitted along with the necessary PHS/EHD permit applications with permit fees and the encroachment permit from Caltrans or the City of Stockton since it was unclear which agency had jurisdiction. A Division of San Joaquin County Health Care Services