ARCHIVED REPORTS_XR0006937 - Laserfiche WebLink

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Monitoring Well Construction Monitoring wells are constructed in borings using thread-jointed, 2-inch inner diameter, Schedule 40 polyvinyl chloride (PVC) casing No chemical cements, glues, or solvents are used in well construction The screened portion of each well consists of factory-perforated casing with 0 020-inch wide slots If unconfined aquifer conditions exist, the well screen is installed from the total depth of each well to approximately 10 feet above the uppermost water-bearing unit If confined conditions exist, the uppermost water-bearing unit is screened exclusively Unperforated casing is installed from the top of each screen to the ground surface The annular space in the well is packed with number 3 sand to approximately 1 to 2 feet above the slotted interval A bentonite plug is added above the sand pack to prevent cement from entering the well pack The remaining annulus is backfilled to grade with a slurry of Portland cement The monitoring wells are protected with a traffic-rated steel utility box equipped with a galvanized sheet steel skirt The box has a watertight seal to protect against surface-water infiltration The design of this box discourages vandalism and reduces the possibility of accidental disturbance of the well Well Development ERI waits a nummum of 24 hours before development of the monitoring wells to allow the grout to seal Initially, a water sample is collected for subjective analysis before development of the monitoring wells This sample is collected from near the water surface in the well with a Teflon banter cleaned with a laboratory-grade detergent and deionnzed water The wells are developed with a surge block and pump Well development continues until the discharge water is clear of silt and sand Clay-size sediments derived from the screened portion of the formation cannot be eliminated by well development ERI coordinates with Unocal for recycling or disposal of the purged water