REPORT OF INVESTIGATIONS No. 41


draulic character of that part of the aquifer penetrated by the wells at each of the test site locations. The wells used in the tests penetrated the upper 330 feet of the aquifer at Bid-a-wee, 245 feet at Long Beach and about 250 feet at the Lansing Smith Steam Plant. None of the wells used in these tests penetrated the full thickness of the aquifer. Deeper wells would draw water from a greater thickness of the aquifer and would, consequently, give higher values.
   The values of the coefficient of storage from these tests are* consistent with values for the Floridan aquifer in other areas. The coefficient of transmissibility of the aquifer at the Lansing Smith Steam Plant is higher than at the other test sites. This may indicate vertical leakage into the aquifer from the overlying formations. Because the tests show considerable differences in the coefficient of transmissibility of the aquifer within the bay area, the coefficient of transmissibility determined from pumping tests nearest a proposed well field should be used. Additional tests should be made at distant locations before a well field is designed.
   In order to predict the amount and areal extent of drawdowns that will result from different rates of pumping and different well spacings, computations were -made using the Theis formula (Theis, 1935) and the coefficients of transmissibility and storage determined at the Lansing Smith Steam Plant, at Bid-a-wee, and at Long Beach. Figure 14 shows theoretical drawdowns in the vicinity of a well discharging at a constant rate for different lengths of time at the Lansing Smith Steam Plant, the Long Beach, and the Bid-a-wee locations. These drawdowns represent the conditions that would result from continuous pumping at this rate. Because drawdowns vary directly with discharge, drawdowns for greater or lesser rates of discharge can be computed from these curves. For example, the drawdown 100 feet from a well at the Lansing Smith Steam Plant discharging at 500 gpm. would be 24 feet after 100 days of pumping. If the well had discharged at 100 gpm for the same length of time, the drawdown at the same distance would have been only one-fifth as much, or about 5 feet.
   The graph of drawdowns along a line of 10 wells, spaced 2,000 feet apart, at a rate of 200 gpm, are shown in figure 15. The values used to determine this profile were obtained by summing the overlapping drawdowns for each well in the line as read from the 100-day curve for the Long Beach test (fig. 14). Similar graphs can be computed to determine the drawdown that would result from different pumping rates or different well spacings (Lang, 1961, Theis, 1957).
   The cone of depression in the vicinity of a well or a well field being pumped at a constant rate will eventually stabilize if a balance