ARCHIVED REPORTS XR0011751 - Laserfiche WebLink

Home Browse Search

Work Plan for Refned Plume Definition and Management ofFloating Product-7500 W 111h St., Tracy, CA. Page 25 —' 7.4 Well Design The majority of the casings for the groundwater monitoring wells will be 2-in. diameter PVC y- with 0.02-in. machine cut screen slots. Those casings will be centered in the 8-in diameter well boring. In the case of the 6 in. diameter casings the well boring will be 12 in. in diameter. The screens will extend from approximately 1-ft above the high groundwater �. elevation to the bottom of the well. The annular space between the screened interval and the y boring wall will be filled with No. 3 Monterey sand, which will serve as a filter. Above that, 2 ft of bentonite will form the well seal. The casing will be equipped with a water-tight, lockable casing cap and the well head will be enclosed in a flush-mounted well head housing rated for heavy vehicular traffic. These and other details of the well construction are shown on Figure 8, r. 7.5 Well Development Following construction, the wells will be developed by pumping and surging and by bailing a minimum of 10 well volumes from each. The development water will be staged on-site in 55-gal., closed-top, steel drums. When data is available on the concentrations of analytes of concern in samples recovered from the newly installed groundwater-quality monitoring wells, drums that contain clean water will be emptied by decanting them onto the site. Drums containing water affected by r hydrocarbons will be pumped into a vacuum truck and their contents shipped off-site for disposal at a permitted recycling facility. 7.6 Survey of Well-head Locations and Elevations `~ The locations of the new wells will be surveyed by an appropriately licensed California registered civil engineer or land surveyor, their latitude and longitude computed, and the elevations of both the top of the casing and the wellhead 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). 7.7 Groundwater-quality Monitoring .. After the new groundwater-quality monitoring wells have been installed and developed they will be used together with the existing wells at the site to establish a new, expanded groundwater monitoring program. The procedures to be used for groundwater-quality monitoring are described below. 7.7.1 Determination of Groundwater Elevations After a delay of at least one week following development of the newly-installed groundwater-quality monitoring wells, the depth from the top of the casing to the water table .., will be measured using a conductivity meter in all monitoring wells that will be extant at the site at that time. That data will be used to compute the groundwater table elevations relative sic