ARCHIVED REPORTS XR0001334 - Laserfiche WebLink

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of each well consisted of factory-perforated casing with 0 020-inch-wide slots The well screen extends from the total depth of the well to approximately 5 or 10 feet above the ground-water surface This screened interval allows sampling at the air-water interface dunng seasonal fluctuations of the ground-water level. The annular space in the well was packed with number 3 sand to approximately 1 to 2 feet above the slotted interval. A 3-foot thick bentonite plug was added above the sand pack to prevent the cement from entenng the well pack. The remaining annulus was backfilled to grade with a bentonite cement slurry. Monitoring wells were protected with a traffic-rated, cast-alununum utility box equipped with a PVC skirt. The box has a watertight seal to protect against surface-water infiltration and must be opened with a special wrench. The design of this box discourages vandalism i and reduces the possibility of accidental disturbance of the well. Well Development We waited a minimum of 24 hours after well installation before developing the ground- water monitoring wells to allow the grout to seal. Before developing the monitonng wells, a water sample was collected for subjective analysis from near the water surface in the well with a Teflon bailer cleaned with a laboratory-grade detergent and deionized water Floating product was not encountered The wells were developed with a surge block and pump Well development continued until the discharge water was clear of silt and sand. Clay-size sediments denved from the screened portion of the formation cannot be entirely eliminated by well development After the wells stabilized for a minimum of 24 hours, the wells were purged of stagnant water and a sample was collected for laboratory analysis. The well was purged of approximately 3 to 5 well volumes of water with a submersible pump, or until Ph, conductivity, and temperature of the purged water have stabilized. Water purged from the wells was stored in labeled, 55-gallon, steel drums approved for this use by the Department of Transportation until suitable disposal options were selected based on laboratory analysis i Ground-Water Sampling The static water level in each well was measured to the nearest 0A1 foot with a Solinst electnc water-level sounder cleaned with a laboratory-grade detergent and deioruzed water before use in each well. A clean bailer was used to obtain a sample from the surface of the t water in the well for subjective analysis of hydrocarbons The sample was retrieved and examined for floating product, sheen, color, and clanty. Approximately 3 well volumes (approximately 50 gallons) were purged from each well with a stainless-steel electrical submersible pump to allow sampling of representative formation ` water The pump, cables, and hoses were cleaned with a laboratory-grade detergent and water before use in each well The wells were purged until pH, temperature, and electrical 06Z6=r 31009-4 2 1