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r s Page 2 SITE BACKGROUND On March 5, 1987,Kleinfeldcr consultants report:d that 3 monitor wells(MW-1 through MW-3) were installed on March 2,1987,south,north and northwest,respectively,of the former underground storage tank location. The wells were developed and sampled March 3, 1987. Groundwater was encountered-t 13 feet below ground surface- All groundwater samples were analyzed for total petroleum hydrocarbons as gasoline('ITH-g)and benzene,toluene,cthylbenzene and xylenes(BTE}). All samples were non detect except for benzene,detected at 3.5 parts per billion(ppb)in MW-1 and 13 ppb in MW-3. On November 13, 1987,Kleinfelder requested to dispose of purge and sample water collected from the wells. The purge and sample water collected April 28, 1987 were non detect. On June 21, 1988,Kleinfelder report documented that groundwater samples collected May 27, 1988 were non detect. The depth to groundwater was 20 feet below ground surface. In a November 12, 1990 report,Dames and Moore documented that groundwater samples were collected on October 24, 1990. All saiuples were non detect Depth to groundwater was 25.3 feet below ground surface. SITE PLAN A site plan map is attached that indicates the locations of the proposed soil borings which will be converted into monitor wells(Figure 1). The tsl of the work plan and an estimate for the schedule of the project follow. TASK 1 - DEVELOP WORK PLAN AND SITE SAFETY PLAN The site safety plan,included with this work plan(see attachment),will be on-site during all field activities. An underground locating service will be employed to identify underground utilities and other possible subsurface obstacles. A minimum of Level D safety equipment is required for all field activities. The work plan will be submitted to the San Joaquin County Environmental Health Division and Regional Water Quality Control Board- TASK 2 - DRILL SOIL BORING Parker Environmental staff,including a state-registered geologist,James A.Jacobs,will supervise the drilling of 1 boring by Aqua Science Engin:ers,Inc.,state-licensed well driPer. The standard operating procedures for drilling sail borings and obtaining soil samples are included in the Attachments. The proposed soil boring will be drilled into native soils. The proposed location of the soil boring may have to be adjusted according to drill-rig accessibility,underground utilities or obstacles. Soil samples will be collected from the boring at approximate intervals of every 5.0 fect,for lithologic and hydrologic characterization,and for possible chemical analysis. The samples will be screened with an organic vapor analyzer(OVA)or a photoionization detector(PID)to be qualitatively evaluated for the concentration of volatile hydrocarbons that may be present. This screening will aid in the selection of the soil samples to be analyzed in a state-ccrtified lab for TPH-g and for BTEX. Parker standard operating procedures for collecting organic vapor data are described in the Attachments. Parker Environmental services, 4165 waito Court, Pittsburg, GA 94565.6116 Phone (415) 4394024. Fax (415) 439-2566