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Mr. Ron Rowe CAMBRIA August 14, 1997 Permits: We will obtain well permits from the San Joaquin County Department of Public Health Services (SJCPHS) for the installation of the wells. Soil Borings: Cambria will use a 7-inch diameter hollow-stem auger drill rig to drill three soil borings to define the extent of hydrocarbons in soil and ground water. Two of the borings will be drilled at the two potential hydrocarbon source areas identified during the tank and piping replacement work(Figure 1). We recommend installing the third well at the anticipated down gradient property line to monitor the down gradient extent of any hydrocarbons detected in the two source area borings.Based on your information, we anticipate encountering ground water at about 15 to 20 ft depth. Therefore,we anticipate drilling to about 30 to 35 feet depth, depending on water depth. The boring adjacent to the former tank locations will be logged continuously and representative samples from each major lithologic unit encountered will be analyzed for physical parameters as discussed below. We will select soil samples from each boring for chemical analysis based on observations of staining and odor and on the results of field screening with a portable vapor analyzer. Our sampling protocol is described in Attachment A. Monitoring Well Construction:The borings will be competed as two-inch diameter ground water monitoring wells screened about 5 feet above and 15 feet below the static water table. The actual well screen will be determined based on lithology encountered during drilling. Standard well construction procedures are described in Attachment A. Well Development and Sampling: Cambria will develop the monitoring wells using surge block agitation and ground water evacuation. The wells will be sampled at least 48 hours after development. Before purging the wells for sampling,we will measure the depth to water using an electronic depth sounder. We will record pH,electrical conductivity,and temperature during the well purging and will sample when these parameters stabilize. Specific well development and sampling procedures are described in Attachment A. Chemical Analysis: The soil and ground water samples will be analyzed for total petroleum hydrocarbons as gasoline using modified EPA Method 8015,benzene,toluene,ethyl benzene,and xylenes,and methyl tert- butyl ether (MTBE) using EPA Method 8020. If MTBE is detected, we will confirm the highest MTBE sample using EPA Method 8260. Physical Analysis: As you requested, we will analyze soil samples from each major lithologic unit encountered in the boring adjacent to the former tank location for physical parameters including moisture content,permeability,dry bulk density and the organic carbon fraction. Since we will have analytic data for these samples, we will also calculate the organic carbon fraction excluding hydrocarbon mass. You had requested that we analyze for the organic carbon fraction from a clean location away from the tanks, however, calculating the organic carbon fraction excluding hydrocarbons for each major lithologic unit encountered should be sufficient. 2