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r./ highly possible that the spill arcU,red dUrictg tank and lute removal. 2.0 Site Description The site is at an elevation of 35 feet above sea level with a surface gradient from the southeast to the northwest. Surface water flow is to the northwest. The Tracy Public Works Department established the groundwater at 10-13 feet at this location. Measurements at the time of tank removal indicated water at 12 feet. The groundwater gradient has been established from shallow groundwater data obtained from the abandoned Mobil Oil Distribution Center site located approximately 500 feet to the east. Domestic water service tar Tracy is supplied by treated canal water and deep wells. The approximate depth of city water wells is 1,000 feet. The nearest city well is approximately 1.5 miles west of the DPC facii 'y. There are several private irrigation wells within one mile of the facility. Sand problems forced the city to abandon a well immediately to the east of this facility. DPC had two septic systems iiYunediateiy north of :he tank site. The septic tants are still in place but not connected to the plant sewer system and no longer in use. A primary electric cable indicated on the site map as overhead service to the yard rest room is now buried and passes north of the excavation site. The yard rest room is currently plumbed to the main plant with .nater and sewer service buried to the north of the building. 3.0 Plan for Determining Extent of Sail Contamination on Site Bruning Associates, Inc. (BAD proposes to place four hollow stern auger borings in the area around the tanks as shown in Figure 2 and place one hand auger boring in the excavation area corresponding to the location of the single contaminated soil sample. Three of the borings will be converted to one monitoring well and two piezometers after soil siampling is complete. The hand auger baring uill be placed at the location of the contaminated soil sample obtained during the tank removal. A hand auger method will be used because the location is not accessible by a drill rig. Samples will be collected every five feet or at r nv significant change in lithology using a modified California split spoon sampler containing brass tubes. Borings will be placed to a depth of where groundwater is encountered, approximately 10-12 feet. Soil borings and samples will be logged by a qualified geologist or engineer according to the unified soil classification system {tTSCS). All sampling equiprr:ent will be decontaminated before use by using a triple rinse procedure as below: • Water and detergent wash; • Water rinse; BRtNSING ASSOCIATES, INC.