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The tidal flux could influence the groundwater below the site by raising and lowering the water level. Such water level fluctua- tion could interfere with aquifer characteristic testing which is base) on the precise correlation between a controlled pumping rate and water level response. Tidal flux could cause an unex, 2cted change in the water levels during the test. If the tida . influence is known prior to testing, then that influence can ae removed loom the test results. Another potential tidal influence is the deflection of the natural groundwater gradient direction. This might result in temporary but significant changes in the direction of plume migration. WESTOi+ proposes to perform a tidal ir_fluence study in order to define the effect of the tidal flux on the groundwater system beneath the site. Water levels will be measured continuously on three monitoring wells for a period of one week (5 days) , If. there is a tidal influence at the site, the groundwater levels recorded will reflect the changes in the tidal stage, as triese changes will be graphically represented by a sinusoidal) pattern on a recorder chart. 2.7 DETERMINATION OF AQUIFER CHARACTERISTICS To determine actual aquifer hydraulic characteristics, a pumping rest will be performed. Data from this test will aid in assess- ing the feasibility of groundwater extraction and treatment as a remedial alternative. A single well pumping test will be performed. The test will utilize the monitor well with the highest yield (based on sampling purge data) as the pumping well. The single-well puny test will involve a minimum of two hours of continuous pumping M. followed by either two hours of recovery measurements or 95 percent recovery. The test will continue until sufficient data is collected from the well for analysis. The water level in the closest adjacent monitoring well will be measured to determine what influence the pumping well has on the surrounding aquifer. A tape and probe device will be used manually to take all water level measurements during the pump test. �. 2.7.1 Aquifer Test Procedures The pumping test will be performed in accordance with the procedures described below. All field data will be recorded on a '- field data sheet. 1. Tide tables for the period of the pumping test will be -- reviewed to assess potential barometric and tidal effects on the aquifer. 2 - 6