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Work Plan for Refined Plume Definition and Management of Floating Product-7500 WIN St., Tracy, CA. Page 33 .. 8.4 Well Design The well casings for the LNAPL monitoring wells will be 0.75-in. diameter PVC with 0.02- in. machine cut screen slots. The casing will be centered in the 2-in diameter well boring. The screen will extend from approximately 1 ft above the high groundwater elevation to the bottom of the well. To place a filter around the slotted portion of the casing, No. 3 Monterey sand filter media will be poured from the surface while a temporary length of blank casing is used to span the distance from the top of the slotted casing to a height of 1 or 2 ft above the ground surface. When the filter material has been placed, a new piece of blank casing equipped with a specially-manufactured casing, equipped with a self-expanding bentonite L) seal will be substituted for the original length of blank casing. The seal will be located approximately i ft above the slotted portion of the casing. The casing/seal system also �- includes a foamed plastic ring, located above the self-expanding bentonite seal, that serves to prevent debris from the surface or walls of the boring from falling down the annular space before the seal has been expanded. When the prefabricated casing/seal system has been installed, the well is completely filled with clean water and permitted to stand for a short period during which the bentonite expands to fill the annulus between the casing and the boring wall. The top of the casing will be closed with a plastic cap and the well head will be enclosed in a flush-mounted housing rated for heavy vehicular traffic. These and other details of the well construction are shown on Figure 10. 8.5 Well Development Following construction, the LNAPL monitoring wells will be developed by surging and bailing. The development water will be staged on-site in 55-gal., closed-top, steel drums, after which it will be pumped into a vacuum truck and shipped off-site for disposal at a permitted recycling facility.. 8.6 Survey of Well-head Locations and Elevations The locations of the new floating product monitoring wells will be surveyed, their latitude and longitude computed, and the elevations of both the top of the casing and the well head box cover frame of each will be determined relative to mean sea level (MSL) in compliance with California Bill AB 2886 (Water Code Sections 13195-13198). .r 8.7 Field Modification The California-licensed geotechnical engineer in responsible charge of the project will, as is discussed in Section 7.8, make such modification to the well locations, soil-sampling procedures and well construction details as may be dictated by the field conditions revealed during the progress of the work. sic