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' Work Plan Page 7 <br /> Former Manna Pro Site <br /> l <br /> Project No 207 3 <br /> ie August 16, 1999 <br />' 3.0 DEEPER GROUNDWATER CHARACTERIZATION <br /> In order to determine the depth to the deepest gasoline impacted groundwater, a deep, <br />' exploratory soil boring will be installed and soil and groundwater samples will be <br /> collected for analysis After the deepest impacted groundwater has been identified, the <br />' boring will be terminated and then converted to a deep groundwater monitoring well <br /> The well will later be used as a basis in planning possible additional deep monitoring <br /> wells, if any, for later construction <br /> 3.1 Soil Boring Installation <br /> A soil boring to be designated as MWD-11 will be drilled to a total depth of 50 feet using <br /> a 8 inch o d (outside diameter) hollow stem auger rig operated by a C-57 licensed drilling <br /> contractor During drilling, the boring will be drilled, logged and sampled by a <br /> professional geologist supervised by a registered geologist The boring will then be <br /> overdrilled using 15 inch o d auger stem After the boring has been completed to <br /> approximately 50 feet, a 8 5/8 inch diameter steel conductor pipe will be placed in the 15 <br /> inch diameter hole and the annulus grouted with neat cement If the boring is terminated <br /> in sandy or porous soil, the bottom of the conductor pipe will be sealed with bentonite <br /> pellets or cement <br /> 3.2 Deep Exploratory Monitoring Well Boring Installation <br /> Past drilling experience at the site immediately north of the Manna Pro Property (Cutter <br /> I Lumber) has shown that heaving sand layers exist beneath the clay layers encountered <br /> from 0-40 feet below grade After the grout around the conductor pipe has been allowed <br /> to set for 24 hours, the boring will be continued using mud-rotary drilling tools to <br /> mitigate the potential for sand heaving into the boring The mud will be a bland, gel and <br /> water mixture, and the boring will be drilled with a 7 718 inch diameter mill tooth, tri- <br /> cot bit <br /> During drilling soil cuttings and drilling mud will be stockpiled or placed in 55 gallon <br /> drums on the location pending profiling and proper disposal All of the borings will be <br /> Ilogged and sampled by a licensed California Registered Geologist <br /> 3.3 Monitoring Well Construction <br /> SimulProbe sampling equipment will be used to collect groundwater samples at intervals <br /> not less than 20 feet below the base of the conductor casing After each groundwater <br /> 2937 Venernan Ave, #8240 Geo-Phase Environmental Inc. Phone(209) 569-0293 <br /> Modesto,CA 95356 Fax(209)569-0295 <br />