FLORIDA GEOLOGICAL SURVEY


per unit change in head normal to that surface. This storage coefficient for an artesian aquifer is a measure of the small amount of water released or taken into storage when the aquifer compresses or expands due to changes in water pressure.


                       AQUIFER TESTS
    The coefficients of transmissibility and storage are determined by the analysis of data obtained by aquifer tests or pumping tests. Three aquifer tests were carried out during the field investigation of the Econfina Creek basin utilizing available wells in the Floridan aquifer. In each of the three tests conducted, a well was pumped at a constant rate while water levels were measured in the pumped well and in one observation well.
    A test of short duration was run at Bid-a-wee (fig. 5) using a standby supply well and an observation well belonging to the city of West Panama City Beach. The pump was operated for a period of 6 hours at a rate of 55 gpm (gallons per minute). The rate of drawdown and the rate of recovery of the water level were measured in the observation well'. 49 feet from the pumped well.
    A similar test was made at Long Beach (fig. 5) in which one well was pumped for a period of 5 hours at a rate of 328 gpm. In this test the observation well was 1,800 feet from the pumped well.
    The third test was made at the Lansing Smith Steam Plant (fig. 5) northwest of Lynn Haven. In this test one well was pumped at a rate of 504 gpmi for a period of 50 hours. The observation well was 1,195 feet away.
    The Theis graphical method (Theis, 1935) was used to compute values of T (coefficient of transmissibility) and S (coefficient of stora ge) from the test data. The following values of T and S were computed:
    Bid-a-wee test                          T=2,000 gpd/ft
                                            S=1.2X 10-4
    Long Beach test                         T = 4,000 gpd/ft
                                            S=5 X10-4
     Lansing Smith Steam Plant test         T =30,000 gpd/ft
                                            S=3X10-4
     These computations are based on the assumptions that the aquifer is (1) of uniform thickness; (2) of infinite areal extent; and (3) homogeneous and isotropic (transmits water equally in all directions). Determinations of T and S from data collected during these three tests give a wide range of values and show considerable change in the hy-