SITE INFORMATION AND CORRESPONDENCE_FILE 1

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EAEngineering,Science,and Tfihnology 14/ EA Western Regional Operations R E CE I V E "t5 te Circle ayerse,ene,CA 94549 ephone:415-283-7077 MAY 91990 Fax.415-283-3894 ENVIRONMENTAL HEALTH - PERMIT/SERVICES 3 May 1990 James Dobbins, Jr.,President Crestwood Hospitals P.O. Box 7343 Stockton,California 95207 Dear Mr. Dobbins: I am writing to you on behalf of our client,Exxon Company,U.S.A., asking for your coopera- tion with ongoing investigations of groundwater contamination in the vicinity of the former Exxon Retail Site(SS)7-3942 at 4444 North Pershing Avenue in Stockton. EA has been inves- tigating the extent of groundwater contamination resulting from a fuel release during station operation. As a result of groundwater movement, the contaminated plume extends northeasterly toward the Chateau Convalescent Hospital. To delineate the plume in the downgradient direc- tion, an additional monitoring well should be installed off the site in the direction of ground- water flow, as required by the Central Valley Regional Water Quality Control Board and the local Environmental Health Division. Knowing the extent of the plume will enable us to design and install a proper restoration system with sufficient capacity for groundwater cleanup. Because a monitoring well in front of the Chateau Convalescent Hospital was found to be contaminated, the next step in the investigation should be a well in the downgradient direction on the parking lot adjacent to the Gero-Psychiatric Hospital. To be able to continue our investigation,EA is asking you for access to the site and permission to install a monitoring well at the approximate location shown in Figure 1. The well would be used for quarterly or semiannual groundwater sampling, to monitor potential contaminant movement and also the effectiveness of the remediation system which will be installed and operated on the Exxon site. When the investigation and cleanup are completed, the well will be removed and the borehole filled in accordance with State Department of Water Resources Standards for water wells. There would be no interference with pedestrian or vehicular traffic after the installation work is com- pleted: the well top will be covered with a traffic box about one foot diameter and will be level with the surrounding pavement. Alternatively, the well could be installed in the planter area sur- rounding the parking lot. EA will provide proof of workman's compensation insurance, liability insurance,and will incorporate a hold-harmless clause for Crestwood Hospitals. Well installa- tion would require eight hours or less on one day,during which a part of the parking lot (about six parking spots) would have to be closed.