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-W <br /> i <br /> 3. The six soil samples will be composited into three and �k <br /> analyzed for benzene, toluene and xylene (BTX) and total tY <br /> purgeable hydrocarbons (TPH) as gasoline by State Department of �►FS <br /> Health Services (DOHS) standard test methodology. <br /> 0 <br /> 4. If contamination is detected by field inspection, <br /> preparations will be made for additional backhoe excavation. <br /> Soils would be excavated until field evidence indicates no <br /> hydrocarbons remain. At this point, soil sampling and analysis <br /> would be conducted as outlined in the above sections 2 and 3. <br /> B. Monitoring Well Installation <br /> 1. Prior to initiating any .field activities, underground <br /> Service Alert (USA) will be contacted to locate underground <br /> utilities at the site. <br /> 2. Three soil borings will be drilled to a depth of 15 <br /> feet below the water table to provide for installation of a <br /> groundwater monitoring well. Depth to water recorded on our May <br /> 1988 monitoring was approximately 10 feet below grade at the <br /> site. Drilling will be conducted by Ostenberg and Stewart with a <br /> hollow stem auger drill rig under a California C57 license <br /> w- #446670, as required. To define the lateral extent of potential <br /> groundwater contamination in the down and cross gradient <br /> direction, the monitoring well will be placed down gradient of <br /> the former tank pit and MW4, which is known to be contaminated <br /> (Figure 5) . The well will be constructed of two inch F480 PVC <br /> casing and completed as shown on Figure 6. <br /> 3. Soil samples will be collected during drilling at a <br /> minimum of five foot intervals starting at five feet below grade <br /> for field characterization. Because the soil samples analyzed <br /> from MW4 located adjacent to and down gradient of the former tank <br /> pit did not detect the presence of hydrocarbons, the soils from <br /> the. proposed borings/wells, which are located further from the <br /> source, should not be contaminated. As such, we propose to not to <br /> conduct laboratory testing on samples collected from this boring <br /> unless field evidence by visual and olfactory inspection detects <br /> the presence of hydrocarbon contamination. Samples would be <br /> analyzed for BTX and TPH by DOHS methodology. <br /> 4. Subsequent to installation, the wellhead of the newly <br /> installed monitoring wells will be surveyed to the existing <br /> wellhead elevation. Groundwater levels will be monitored in all <br /> wells to determine depth and permit calculation of the gradient. <br /> 5. A water sample will, be collected from the three newly <br /> --installed- -monitor ing- wells--after-purging a- minimum--of four well <br /> volumes (casing and sand pack) . The purged water will remain on <br /> site, in secured 55 gallon drums, until laboratory results are <br />