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l _ 7 <br />2.7 <br />OR <br />The shallow groundwater is probably influenced by the San <br />Joaquin River which is approximately 1/8 mile from the site. <br />Proximity of private, municipal and irrigation wells: <br />A well search of the proximity <br />irrigation wells within a one <br />progress and will be presented at <br />Sampling plan/report preparation: <br />of private, municipal, and <br />half mile radius is in <br />a later date. <br />To assess the contribution of the former underground tanks <br />to soil and groundwater contamination at the site, WaterWork <br />proposes to drill and sample three groundwater monitoring <br />wells around the former tank pit, and two soil borings in <br />the center of each former tank pit. One well will be <br />located up -gradient from the former tank pit, two wells will <br />be installed down -gradient at the approximate locations <br />shown on Figure 2. <br />Underground utilities will be located by Underground Service <br />Alert prior to commencement of drilling activities. <br />Three soil borings will be drilled to provide for the <br />installation of the groundwater monitoring wells. These <br />wells will be completed"at a depth.of approximately 30 feet <br />below grade. Completion depth will be based on setting the <br />screen approximately 15 feet below the top of the saturated <br />zone. Two ten foot soil borings will be drilled in the <br />center of each former tank pit. These borings will be used <br />to determine if excavation of the former tank pits is <br />necessary to remove soils that maybe a continuing source of <br />groundwater contamination. Drilling will be conducted by a <br />licensed driller using a hollow auger drill rig. The wells <br />will be constructed of 2 inch diameter F480 PVC <br />screen/casing and completed as shown on Figure 3. <br />Drill cuttings will be logged continuously for <br />characterization of, contamination and soil type using the <br />Unified Soil Classification System. Descriptions of soils <br />encountered and monitoring well construction details will be <br />recorded on boring/well logs and included within the Problem <br />Assessment Report. Soil samples will be collected from each <br />boring at five foot intervals. The samples will be <br />collected, preserved and transported under chain--of-custody <br />in accordance with Wa'terWork's Soil Sampling Protocol <br />(Appendix I). Soils encountered will be monitored for <br />organic vapors by placing a small amount of representative <br />material in a sealed container, then measuring the <br />concentration of volatiles collected in the head space of <br />the container with a photoionization detector (PID) <br />calibrated to the isobutylene molecule. The values obtained <br />at each measurement point will be recorded on the boring <br />logs. <br />Pa <br />