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Kennedy/Jenks/Chilton detected during the previous sampling of site soils and the absence of nitrates in the deeper samples, the Cal-Farm site may not be the primary source for the nitrates detected in the water sample. Initial research into the history of the area indicate a nearby spill of 4800 gallons of urea ammo- nium nitrate which could be a potential source of nitrate contamination in the shallow aquifer. To further evaluate this possibility, surface soil samples will be collected over a wide area of the site to assess nitrate concentrations. Based on the previous sampling, samples from a depth of one foot should provide an indica- tion of the general presence of nitrates. Depending upon the results of this shallow sampling, additional deeper sampling may be required at a later date to investigate areas where surface spills may have occurred. The original work pian has been amended to provide analysis of discrete rather than compos- ite soil samples. This change has been made as a result of recent information indicating that DDT may have been formulated or processed at the Cal Farm site. A second soil boring is also recommended to investigate the possible leakage of hydrocarbon products from an additional underground fuel tank which may exist on the site which has recently been brought to our attention. Both tanks reportedly remain on the site. Analysis of four soil samples for Dioxin from the area where three storage containers are located is recommended based on the possibility that original containers storing the herbicide Siivicide may be present. Because the poten- tial for Dioxin exists, this analysis will also be performed. PROPOSED SCOPE OF WORK Described below are the tasks that will be performed during the preliminary site assessment. Task 1 - Monitoring Well Installation and Sampling Four monitoring wells will be installed at the approximate locations shown on Figure 1. The monitoring wells will be drilled to a depth of 5 to 10 feet below groundwater, depending on the depth of confining soils present below the first encountered saturated zone. Based on Spring 1985 groundwater elevation data, which indicate a depth to groundwater of approximately 10 feet (San Joaquin Flood Control and Water Conservation District Semi-Annual Groundwater Report, Spring 1985) , we have assumed a maximum monitoring well depth of 20 feet below the ground surface. Borings for monitoring wells will be drilled using an 8-inch diameter hollow-stem auger. Soil samples will be collected at 5-foot intervals beginning at the ground surface using a modified split-spoon sampler with 6-inch brass liners inserted inside to help retain the samples. One brass liner at each drive interval containing the soil samples will be sealed at both ends with a Teflon sheet secured by a plastic cap. Electrical duct tape will be wrapped around both ends to prevent cap slippage during transport. Each liner will be labeled as to date, boring number, sample number, depth, time, and collector. After 2