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PUBLIC HEALTH SERVICES ,aPQ �o <br /> SAN JOAQUIN COUNTY r. <br /> ENVIRONMENTAL HEALTH DIVISION .. ` <br /> Karen Furst, M.D., M.P.H., Health Officer �. P <br /> 304 East Weber Avenue, Third Floor • Stockton, CA 95202 <br /> 209/468-3420 u - •� <br /> DR A R GLOVER <br /> FAYETTE MANUFACTURING OCT 19 1999 <br /> PO BOX 61 <br /> TRACY CA 95378 <br /> RE: FAYETTE MANUFACTURING SITE CODE: 2233 <br /> 7675 W ELEVENTH STREET <br /> TRACY CA <br /> San Joaquin County Public Health Services Environmental Health Division (PHS/EHD) has received and <br /> reviewed the August 17, 1999 ATC Associates (ATC) Quarterly Monitoring Event Report for the above <br /> referenced site and provides the following comments and directives. <br /> Soil and groundwater petroleum hydrocarbon contamination has been documented to extend laterally <br /> approximately 100 feet north (MW-4) and north-west (MW-5) of the former tank locations. Free phase <br /> hydrocarbons have been documented laterally approximately 75 feet north-east(FPB-1 and FPB-2) of the <br /> former tank locations. Depth to groundwater has varied during this site investigation ranging from 6 to 9 <br /> feet below grade surface (bgs). Groundwater flow direction has varied north-west to north-east. <br /> Hydrocarbon distribution has not been observed at depths greater than 25' bgs in soil or groundwater to <br /> date. In most boreholes completed at this site a sandy water bearing horizontal preferential flow path is <br /> observed at approximately 10 to 20' bgs. No discussion regarding hydraulic communication vertically is <br /> provided. Limited data points exist east of a north-south arcing axis referenced by MW-1, MW-3,through <br /> MW-4. Free phase hydrocarbons were documented along the down gradient northern distal end of this <br /> arcing line segment. An on-site drinking water well in use at this site is located approximately 250 feet <br /> west of the former tank pits. All parcels surrounding this site currently use on-site drinking water wells. <br /> PHS/EHD interviews with the City of Tracy have concluded that no municipal drinking water supply is <br /> currently available to this or surrounding parcels and as such the dependence on groundwater in the area is <br /> documented. Further characterization east of the free-product boreholes (FPB-1 and FPB-2) may be <br /> necessary to define the hydrocarbon plume prior to the preparation of a closure request document. <br /> The August 17, 1999 ATC report does not recommend closure, however, telephone communications with <br /> Jeanne Homsey of ATC and PHS/EHD recognize that site closure may be attainable following the review <br /> of a detailed formal closure report(which addresses the lack of lateral and vertical plume definition north- <br /> east of MW-1,MW-3 and MW-4 and the presence of near by drinking water wells). <br /> In the event a closure request document is prepared, PHS/EHD recommends that the formal closure request <br /> document contain the following information: <br /> 1. All items found on the Central Valley Regional Water Quality Control Board (CVRWQCB) <br /> Checklist of Required Data for Closure of Underground Tank Sites(attached). <br /> 2. A site conceptual model which clearly describes current and future beneficial groundwater use in <br /> the area. This includes a description of the regional hydrogelologic setting near the site complete <br /> with vicinity maps to scale showing surface waters,recharge areas,and descriptions of water wells <br /> within 2000 feet of the site. PHS/EHD recommends that the closure document include supporting <br /> text related to aquifer and wellhead vulnerability, dependence upon groundwater as a drinking <br /> water supply,and the availability of alternative drinking water sources if any. <br /> PAGE 1 <br /> A Division of San Joaquin County Health Care Services <br />