ARCHIVED REPORTS XR0000562 - Laserfiche WebLink

Home Browse Search

S E C 0 R 2003 Feasibility Test Summary Report September 18, 2003 ' Page 3 3.1.2.3 Constant-Rate Pump Test Results ' On November 6, 2001, the constant-rate pump test was initiated. The test was performed at an approximate pumping rate of 0.75 gpm for approximately 3 days. Water level data compiled throughout the aquifer testing was later used to estimate hydraulic properties of the aquifer. ' 3.1.2.4 Pump Test Data Analysis Drawdown data collected from the wells during aquifer pumping activities was corrected for the observed ' antecedent trend and for fluctuations in barometric pressure prior to analyzing the data. AQTESOLV®, was used to perform quantitative analysis of the pumping test data. For comparison purposes, the test data was analyzed using one or more standard analytical solutions for non-equilibrium conditions such as ' those described by Theis (1935) and Cooper and Jacob (1946). SECOR utilized the software package AQTESOL\/0 to determine estimates of aquifer hydraulic properties. Based on results of aquifer test dataanalysis, transmissivity values determined from the pump test ' ranged from 45.72 ft2/day (MW-1) to 83.03 ft /day (MW-11). Storativity values ranged from approximately 0.004 (MW-1) to 0.023 (MW-2). Assuming a saturated aquifer thickness of 34 feet (the depth of water in well MW-9A), the resulting hydraulic conductivities would range from 1.35 ft/day (MW-1) to 2.44 ft/day ' (MW-11). Data plots are included in Appendix F. The results obtained from the aquifer test are within the range of published values (Freeze and Cherry, 1979) for unconsolidated silty sands. • 3.1.2.5 Groundwater Extraction Radius of Influence ' As discussed in section 3.1.1.1, boring logs do not indicate the presence of a confining layer at the site. Therefore, the equilibrium equation (Kuo, Jeff, 1999. Practical Design Calculations, pp. 188) for an unconfined aquifer was used to estimate the radius of the cone of depression. The equation assumes that all dynamic condition in the well and ground are in equilibrium; the pumping rate is constant, the ' drawdown and radius of influence have stabilized, and water enters the well in equal volumes from all direction. A conservative value of 1.35 ft/day (section 3.1.2.4) or 10.1 gallons per day per square feet (gal/day/ft) was used for calculation purposes. ' Equilibrium Equation: Q — K(hf —hi ' 1,055>og(r/R Where: ' Q = Pumping rate (gpm) from test K = Hydraulic conductivity (gal/day/ft) from pumping test data (section 3.1.2.4) hf = Steady state drawdown at observation well MW-2 measured from bottom of well to top of water ' column (ft) h; = Static water level at observation well MW-2 measured from bottom of well to top of water column (ft) ' r = Distance from pumping well MW-9A to observation well MW-2 (ft) R = Radius of cone of depression 1