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s <br /> associares frac . <br /> j <br /> Groundwater Monitoring Wells Construction Details <br /> The three soil borings will be completed as shallow groundwater monitoring wells. If field <br /> conditions indicate that the deep soil boring is clean at 70 feet bgs, the boring will be backfilled <br /> with grout to approximately 57 feet bgs prior to completion of the monitoring well. The <br /> remaining two soil borings will also be completed as monitoring wells to depths of approximately <br /> .57 feet bgs. The monitoring wells will be constructed of 2-inch inside diameter schedule 40 PVC <br /> well screen and casing. A 0.020-inch well screen slot and #2/12 mesh sand pack will be used. <br /> Neat cement will be used to seal the wells in accordance with California Well Standards <br /> (December 1981). To protect the integrity of the wells, locking, water-tight well plugs will be <br /> installed on each well and a water-tight wellhead labeled"'monitoring well" will be concreted over <br /> each well. The top of casing of the new wellheads will be surveyed to assess groundwater <br /> gradient and flow direction. Groundwater monitoring well construction details are shown on <br /> Figure 4. <br /> If soil in the deep boring appears to be impacted with hydrocarbons at a depth of approximately <br /> 70 feet.bgs, a deep screened monitoring well will be completed in this boring. The deep well will <br /> be nested within the same boring as a shallow well. The 8-inch hollow stem auger will be <br /> removed and the boring will be reamed out using 10-inch hollow stem augers. The monitoring <br /> well will be constructed of 2-inch diameter schedule 40 PVC well screen and casing. <br /> Approximately 5-feet of screen will be used and the screen will be placed in the most permeable <br /> layer near the-contamination.. A 0.020-inch well screen slot and #2112 mesh sand pack will be <br /> used. A bentonite seal will be placed above the sandpack. The shallow well will then be <br /> constructed as previously described. Neat cement will be used to seal the wells in accordance <br /> with California Well Standards (December 1981). To protect the integrity of the wells, locking, <br /> water-tight well plugs will be installed on each well and a water-tight wellhead labeled <br /> "monitoring well" will be concreted over the wells. The top of casing of the new wellheads will <br /> be surveyed to assess groundwater gradient and flow direction. Groundwater monitoring well <br /> construction details for the nested wells are shown on Figure 5, <br /> Groundwater Monitoring Well Development <br /> 4 <br /> Measurement of depth to water in the three wells will be completed to evaluate the direction and <br /> magnitude of the groundwater gradient beneath the site. The new wells will be developed using <br /> f surge and bail techniques until the produced water is relatively sediment free. Prior to the <br /> collection of groundwater samples, a minimum of three well volumes (casing and sand pack) will <br /> be purged. Temperature, pH, water elevation, .and electric conductivity will be measured and <br /> allowed to stabilize. Water samples will be collected using disposable bailers, one dedicated to <br /> each well. <br /> wA17295Veporislwkpadd.doc 4 <br />