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augers. The bottom of the screened interval will be fitted with an end plug and the top of the well casing will be equipped with an expandable, water-tight, locking cap. The well screen will intersect the water table and account for anticipated seasonal variations within the aquifer. No glue will be used in this assembly. The annular space between the well screen and the wall of the borehole will be filled with clean sand to provide filtration capacity and impede movement of sand or silt into the well. The sandpack will extend about 1 to 2 feet above the top of the well screen. A 2-foot thick plug of hydrated bentonite will be placed above the sandpack and the remaining annular space will be backfilled with a neat cement grout with 5% powdered bentonite. The grout will be pumped or tremied into the hole if necessary. The monitoring well will be protected from vandalism or the entry of surface fluids. The wellhead will be finished with either a watertight, security traffic box or a locking standpipe which is secured in place with concrete. Well Development The monitoring well will be developed at least 48 hours after well completion with a vented surge block and bailer used to surge the water around the screened interval to remove fine particles and stabilize the sandpack materials around the well screen. After several well volumes of water have been surged and bailed, the well will be pumped (or bailed) until the discharge water is relatively free of sand or silt. After well development, the elevation of the monitoring well (i.e., the top of casing) will be surveyed to mean sea level. The benchmark located on the bridge where Undine Road crosses Middle River will be used as the survey datum. The elevation of the arbitrary datum used to survey the elevations of the temporary well screen and casing installed in the exploratory borings will also be tied into the benchmark, thereby allowing the depth to water level measurements made from the boreholes to be adjusted to mean sea level. All surveyed elevations will be performed to an accuracy of 0.01 foot. Monitoring Well Sampling and Analytical Procedures Prior to purging, the water level in the well will be measured using a Solinst immersion probe (or equivalent) to an accuracy of 0.01 foot and the well will be sampled with a clear bailer (or measured with an interface probe) in order to inspect the well for the possible presence of floating hydrocarbons. The monitoring well will be purged prior to collecting groundwater samples for chemical analyses. During the purging process, approximately three to five well volumes of groundwater will be discharged from the well using either a pump or bailer. The well will be properly purged when the physical parameters of the groundwater (i.e., pH, temperature, and conductivity) have stabilized. If the well is evacuated prior to the removal of three to five well volumes, a sample of the groundwater will be collected when the water level is sufficient to provide a representative sample (i.e., return to 80% or more of the static water level). cca/9-30-92/8913a/JAWP13 11