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a 19 eggg October 17, 1991 Lammersville School District Page 3 02320 029000 TASK 2: Monitoring Well installation We propose to drill at least two additional soil borings,and install monitoring wells in order to define the lateral extent of dissolved hydrocarbons in the wate•table.The proposed well vocations are down gradient of the known extent of dissolved hydrocarbons(Figure 6,Appendix A). If there are indications that soil or groundwater contain hydrocarbons in these primary locations (Figure 6) based upo:•field screening methods, additional wells will be placed at the alternate locations. The alternate locations will not be drilled if no hydrocarbons are encountered in the soil and groundwater at the primary locations. Task 2a: Scd Boring and Sampl*.ng Each boring will tae drilled with a truck mounted rig using 8-inch diameter (or similar) hollow-stem augers. Each bar -1 will be drilled to a depth of ten-feet below the water table or approximately 20' feet below grade. During drilling,five-foot soil cores will be collected from the borings. Cores will be field screened using a photo-ionization detector and selected samples will be collected from these cores in brass tubes (i.e. 2-inch by 6-inch or similar). Sampling protocol includes labeling each brass tube (samplers name,date,boring number,depth,time,and analyses request),sealing each brass tube with aluminum foil arid plastic end caps,wrapping ends with tape ,with non-organic adhesi%,p), and placing the tube on ice for transport. Analyses will consist of EPA methods 35F018020?8015 (modifiedl• Selected samples will be submitted to a State of California Department of Health Services certified laboratory under chain-of-custody, and analyzed for benzene, toluene, ethylbenzene and xylenes (BTEX)and TPH-G G61centratiors. All drilling and sampling equipment will be steam cleaned between drill holes and sampling intervals. All soil and rinsate water produced curing drilling will be stared in Department of Transportation(DOT)-approved 17-H,55-gallon containers pending results of laboratory analyses. Task 2b: Monitoring Well Installation Each monitoring well will be completed as shown on Figure 7, (Appendix A). Each well will be constructed using two-inch diameter PVC pipe, flt:sh threaded to two-inch diameter 0.020-inch-slot well screen. 'Well screen will be installed from the bottom of each boring(approximately 20 feet below grade) to approximately 3 to 5 feet above the level at which groundwater is encountered, 1n the annular space, #2 :,and will be placed from the Bottom of the boring to one foot above the screen -- - - - interval -A one-foot-thick hydrated bentonite plijg will be placed on the sand overlain by cement grout to grade. Concrete will be poured around the outside of a water-proof traffic-rated r�ad box to secure GROLJNMV,rTER TECHNOLOGY,INC. ,