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51.3 <br /> r � <br /> FIELD PROCEDURES <br /> N'LmMrrine_Well Constru�i�n <br /> Monitoring wells will be used to evaluate the ground-water flow direction and whether <br /> hydrocarbons are present in the ground water near suspected sources of hydrocarbons and <br /> at the margins of the site. Monitoring wells wid be constructed in the borings with thread- <br /> jointed, 4-inch-inner-diameter, Schedule 40 polyvinyl chloride (FVC) casing. Nt chemical <br /> cements, glues, or solvents wi:I be used in well construction. The screened portion of each <br /> well will consist of factory-perforated casing witti 0.020-inch-wide slots. The well screen will <br /> extend from the total depth of rhe well to .approximately 5 feet above the ground-Nvater <br /> surface. This screened interval wi!I allow sampling at the air-water interface during seasonal <br /> fluctuations of the ground-water level. The annular space in the well will be packed with <br /> number 3 sand to approximately 1 to 2 feet above the slotted interval. A 3-foot thick <br /> bentonite plug will be added above the sand pack to prevent the cement from entering the <br /> well pack. The remaining annulus will be backfilled to grade with a bentonite cement <br /> slurry. Well construction details are presented in the attached Schematic Well Design. <br /> Monitoring wells will be protected with a traffic-rated, cast-aluminum utility box equipped <br /> with a PVC skirt. The box will have a watertight seal to protect against surface-water <br /> infiltration and must be opened with a special wrench. The design of this box discourages <br /> vandalism and reduces the possibility of accidental disturbance of the well. <br /> Well Development <br /> RESNA Industries will wait a minimum of 24 hours after well installation before developing <br /> the ground-water monitoring wells to allow the grout to seal. Before developing the <br /> monitoring wells, a water sample will be collected for subjective analysis from near the <br /> water surface in the well with a Teflon bailer cleaned with a laboratory-grade detergent and <br /> deionized water. If floating product is encountered in the well,the thickness of the product <br /> will be measured with an interface probe and recorded and the water will not be sampled <br /> for chm-Acal analysis. Product will be bailed from the well and stored in appropriately <br /> labeled drums onsite. RESNA Industries will evaluate the disposal options and apprise <br /> r-.RCO of these options. <br /> }~ If no floating product is detected, the wells will be developed with a surge block and pump. <br /> Well development will continue until the discharge water is clear of silt and sand. Clay-size <br /> sediments derived from the screened portion of the formation cannot be entirely eliminated <br /> by well development. <br /> After the well has been allowed to stabilize for a minimum of 24 hours, the well will be <br /> purged of stagnant water and a sample :ii be collected for laboratory analysis. The well <br /> will be purged of approximately 3 to 5 well volumes of water with a submersible pump, or <br /> until pH, conductivity, and temperature of the purged water have stabilized. Water purged <br /> 3 JW9.4W <br />