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Mr . Scott Walker <br /> November 22 , 1988 <br /> 202/799-5027 . 02 <br /> Page 3 <br /> WORK STEPS <br /> A minimum of four additional groundwater monitoring wells would <br /> be installed in order to better define the extent of groundwater <br /> contamination at the site . The proposed well locations are <br /> shown in Figure 3 (Attachment I ) . To accomplish these well <br /> installations , GTI would perform the following work steps : <br /> Drill soil borings to 75 feet below surface with a <br /> truck-mounted drill rig using 7-inch diameter hollow- <br /> stem augers . <br /> Attempt to collect soil samples at 5-foot intervals in <br /> each bore hole. <br /> " Install 2-inch diameter PVC monitoring wells in each <br /> bore hole . <br /> Develop and survey each newly-installed monitoring <br /> well . <br /> - Monitor and sample water in all the wells at the site . <br /> Submit groundwater and selected soil samples collected <br /> from each bore hole for laboratory analysis of fuel <br /> hydrocarbons . <br /> Soil borings would be drilled with a truck-mounted drill rig <br /> using 7-inch diameter hollow-stem augers . Each bore hole would <br /> be completed to a maximum depth of 75 feet below grade with <br /> cuttings logged by a GTI field geologist following the Unified <br /> Soil Classification System and working under the direction of a <br /> California registered geologist . <br /> Soil samples would be collected at 5-foot intervals during <br /> drilling, using a split-spoon sampler lined with three 2 . 5-inch <br /> diameter by 6-inch long brass sample tubes . Each sample would be <br /> field screened by visual observation, and with a photo-ionization <br /> detector (PID) . <br /> Following completion of each boring, a 2-inch PVC monitoring well <br /> would be installed using 30 feet of . 020-inch slotted well screen <br /> threaded to 45 feet of 2-inch blank casing to surface . The <br /> annular space in the bore hole would be filled with a well pack <br /> consisting of #20 Monterey sand from the bottom of the boring to <br />