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E WGR Hi.,M Fater/16 February I99 BACKGROUND The former underground storage tanks and the waste oil lank were removed by Blaine Tech Services (BTS) of San Jose, California, b:twccn 6 and 10 January 1989. Results of the soil sampliug conducted by BTS during the tank removal were reported to Chevron on 17 January 1989. Total petroleum bydroca rbons were detected in soils excavated from the tank pit. Oil and grca�c were detected in soil excavated from the waste oil pit. A soil vapor survey(SE'S)was conducted by WGR on 13 and 1.1 February I989. Total volatile hydrocarbons were detected in vapor pointy sampled at about 15 ft below grade in Zhu vicinity of the former location of the underground storage tanks,along former product line locations,and adjacent to the former location of the pump islands. SITE PLAN A site plan that will be used to locate all former and existing tanks,pump islands,product transfer lines,and the proposed soil borings and monitoring wells will be prepared. For the purpose of this proposal, a draft site plan is attached that indicates the location of the proposed soil borings and monitoring wells(Figure 2 of Attachment 1). SITE SAFETY PLAN The site safety plan has been prepared and will be onsite during all field activities. An underground locating service will be employed to identify underground utilities and other possible obstacles. SOIL BORINGS AND SAMPLING WGR's standard operating procedure for collecting soil samples during boring installation is included as Attachment B. The proposed soil boring locations are indicated on Figure 2. Boring 11-1 is locatad adjacent to the location of the formerwaste oil tank. Proposed borings B-1 and B-5 are located is the vicinity of the former underground tank and pump islands. Boring B-2 is to the cast of the former pump islands and service station building. Soil boring B-1 is located at the northwest corner of the site. The location of the soil borings may have to be adjusted according to accessibility and underground utilities or obstacles. Soil samples will be collected from the borings at approximately 2.5 ft intervals for lithologic and hydrogeologic characterization and for possible chemical analysis. Soil samples will be screened with a pbotoionizatiun detector(PID) to qualitatively determine the concentration of volatile hydrocarbons which may be present. Soil cuttingswill be stored onsite in 55-gallon drums pending laborztory analysis. MONITORING WELL INS'T'ALLATION AND DEVELOPMENT PROCEDURE The WGR standard operating procedure for installing an developing groundwater monitoring wells is included as Attachment C. The borings will be completed as 4-inch-diameter monitoring wells. Figure 3 presents general well construction details.For each well the screen will extend 20 ft into the first water-bearing zone or the screen will terminate at less than 20 ft if 4 to 5 ft of confining material are i.- 1602Fe9