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City of Stockton TL# 394-0027-01 <br /> March 10, 1994 Page 3 <br /> 4.0 PROPOSED FIELD ACTIVITIES <br /> Proposed field activities are summarized in the following <br /> subsections. Standard operating procedures (SOPs) , relevant to the <br /> field activities, are described in Appendix A. <br /> 4. 1 Monitoring Well Installation <br /> Twining proposes to drill two soil borings to a depth of 125 feet <br /> BSG using 7-5/8-inch diameter hollow-stem augers . Soil samples <br /> will be collected at five-foot intervals beginning at five feet BSG <br /> for lithologic purposes only. A Twining geologist will log the <br /> soils in accordance with the Unified Soil Classification System. <br /> Drill cuttings will be stored in California Department of <br /> Transportation (DOT) -approved 55-gallon drums. Soil disposal will <br /> be the responsibility of the client. <br /> The monitoring wells will be constructed of 2-inch diameter <br /> schedule 40 polyvinyl chloride (PVC) well casing and 0. 01-inch <br /> machine slotted well screen. Casing and well screen will be flush <br /> threaded. The screened section will extend from approximately five <br /> feet above first encountered groundwater to approximately 15 feet <br /> below first encountered water. <br /> Lonestar #3 washed sand, or its equivalent, will be placed from the <br /> bottom of the boring to approximately five feet above the top of <br /> the machine slotted casing. Three to five feet of bentonite <br /> pellets will be placed on top of the filter pack, and the remaining <br /> annular space will be filled with a sand-cement grout containing <br /> three to five percent bentonite. The wells will be sealed with a <br /> PVC slip cap. Steel standpipes will be installed to approximately <br /> 1.5 feet above ground surface, secured in place with concrete, and <br /> the lid will be secured with a lock. <br /> Drilling and well installation activities will be supervised by a <br /> Twining geologist. The Twining geologist will be working under the <br /> direct supervision of a California registered geologist. Twining <br /> understands that the SJCEHD requires oversight of grouting <br /> activities and that no charge will be applied for one hour or less <br /> per well. Twining anticipates completing the grouting for well <br /> abandonment and installation within the specified time frame. <br /> 4 .2 Well Development and Pump Installation <br /> Monitoring wells will be developed by bailing and pumping following <br /> installation. Development will not begin until at least 48 hours <br /> after installation. Development water will be contained in DOT- <br /> approved 55-gallon drums. Development will continue until <br /> relatively clear water is discharged or the well goes dry and does <br /> not recover in a reasonable time. It is estimated that no more <br />