WORK PLANS - Laserfiche WebLink

Home Browse Search

LFR Inc. • The annular space around the screened interval will be packed with sand/gravel to enable collection of representative groundwater samples. • The annular space above and below the screened interval will be appropriately sealed. • The well will be adequately developed. 3.4.1 Soil Boring Advancement The well will be installed by a C-57 licensed drilling contractor using a hollow-stem auger drill rig equipped with a split-spoon sampler. Soil samples will be collected for lithologic description at 10-foot intervals (at a minimum) during advancement of the soil boring. Soil lithology will be recorded in a lithologic log by a field geologist using the Unified Soil Classification System. The lithologic log will be prepared under the direct supervision of a California Professional Geologist who has expertise in stratigraphic well logging. The total depth of the boring will be determined in the field, based on the lithology encountered. Based on lithologic and groundwater elevation data collected from other wells at the Site, it is anticipated that the total depth of the boring will be approximately 125 feet bgs. 3.4.2 Monitoring Well Construction and Development After the boring has been advanced to the desired depth, the groundwater monitoring well will be constructed using flush-threaded, 2-inch-diameter, polyvinyl chloride (PVC) casing. The well screen will be 0.010-inch-slotted PVC casing. The length of the well screen will be based on the thickness of the water-yielding sediment encountered. Based on data collected from the five existing groundwater monitoring wells, it is anticipated that the screened interval will be approximately 20 feet long with approximately 5 feet above the groundwater table to accommodate seasonal fluctuations. Blank PVC casing will be installed from the top of the screened interval to the ground surface. Figure 4 presents a typical well construction diagram. After the well casing has been placed inside the augers, the well annulus materials (sand, bentonite, and grout) will be added. The well annulus opposite the screened interval will be filled with clean Number 2/12 Monterey sand to a height of approximately 3 feet above the top of the well screen. A minimum of 3 feet of bentonite chips will be placed and hydrated above the sand pack to isolate the screened interval from material above and prevent the entrance of grout into the sand pack. After the bentonite seal has hydrated, a clean cement-bentonite grout mix will then be placed in the annular space above the bentonite seal to the ground surface to seal the remainder of the borehole from the possible infiltration of surface water. The SJCEHD will be notified before the wells are sealed so that a field inspector may witness this activity. After the well is completed, the top of casing will be surveyed to the nearest 0.01 foot and tied into the elevations of the existing wells by a licensed surveyor. Page 4 wp�MW-08_Insta11-FebO6-fina1-M2506.d.:LFR