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0 • <br /> URS <br /> Ms.Margaret Lagorio Page 5 <br /> San Joaquin County Environmental Health Department <br /> January 13,2004 <br /> slotted well screen will be set from approximately 95 to 100 feet bgs for the purpose of assessing deep <br /> groundwater for potential 1,2-DCA impacts.Exact screen interval will be determined in the field by a <br /> URS geologist. A Monterey No. 3 silica sand filter pack will be installed from the bottom of the boring <br /> to 2 feet above the well screen. A 3-foot bentonite seal will be placed above the sand pack and neat <br /> cement will be used to seal the remaining annular space to the surface. A locking well cap will be placed <br /> on the top of the casing and the surface will be completed with a traffic-rated,flush-mounted well box. <br /> A URS geologist will direct completion of the well and completion details will be presented on a boring <br /> log. <br /> Shallow Monitoring Well Installation (if necessary) <br /> If additional shallow monitoring wells are required based on grab groundwater laboratory results these <br /> groundwater monitoring wells will be constructed using 2-inch-inside-diameter,Schedule 40,flush- <br /> threaded PVC well casing. Fifteen feet of 0.020-inch machine-slotted well screen will be set from 5 feet <br /> above to 10 feet below first encountered groundwater. A Monterey No. 3 silica sand filter pack will be <br /> installed from the bottom of the boring to 2 feet above the well screen. A 3-foot bentonite seal will be <br /> placed above the sand pack and neat cement will be used to seal the remaining annular space to the <br /> surface. A locking well cap will be placed on the top of the casing and the surface will be completed <br /> with a traffic-rated,flush-mounted well box. A URS geologist will direct completion of the well and <br /> completion details will be presented on a boring log. <br /> Groundwater Monitoring Well Development, Sampling, and Surveying <br /> The groundwater monitoring well(s)will be developed,no less than 72 hours following installation,by <br /> rigorously surging over the length of the screen interval and by pumping approximately 10 casing <br /> volumes of water from the well(s). The pH,temperature,conductivity, and turbidity of the development <br /> water will be measured and recorded periodically during the development process. <br /> Groundwater samples will be collected from the groundwater monitoring well(s)no less than 48 hours <br /> after development. The groundwater samples will be analyzed for GRO,by EPA method 8015B,and <br /> BTEX,MtBE,TBA,DIPE,ETBE,TAME, 1,2-DCA,EDB,by EPA Method 8260B. Trip blanks will be <br /> collected and placed on hold as part of this investigation. <br /> The well location(s)will be surveyed with respect to northing and easting positions. The top-of-casing <br /> elevation(s)will be surveyed with respect to mean sea level. Survey data will be uploaded to <br /> GeoTracker. <br /> Equipment Decontamination and Waste Disposal <br /> All down-hole drilling equipment used for both grab groundwater sampling and monitoring well <br /> installation will be thoroughly decontaminated between drilling locations by steam cleaning. Soil <br /> KAWprocess\J5 BP ARCO\00760\2004 Assessment\760 GW Workplan 04.doc <br />