An aquifer test was carried out at a possible ground-water development site in Truro, Massachusetts. Average lateral hydraulic conductivity for material in the screened interval of the test well is 216 feet per day. Specific yield of the material at water-table depth is about 0.10. Anisotropy, or ratio of lateral hydraulic conductivity to vertical hydraulic conductivity, is between 1 and 5 for the uppermost 60 feet of saturated material, but is probably much higher at greater depths. Calculation of drawdown after pumping 200 days at 1 million gallons per day indicates lateral intrusion of saline water from the sea would not reach the well and that the area of ground-water contribution would be sufficient to intercept an amount of average annual recharge equal to pumpage. Using the previously determined aquifer constants and the maximum drawdown after 200 days of pumping at 1 million gallons per day, it was determined that a stable upconing adjustment of the fresh water/saline-water interface would occur below the pumping well, and saline water would not reach the well through vertical intrusion. (Woodard-USGS)
