REPORT OF INVESTIGATIONS NO. 75


            TRANSMISSIVITY AND STORAGE COEFFICIENT

      The transmissivity (T) and the storage coefficient (S) of the aquifer, or zone, are related respectively to -the hydraulic conductivity (K) and the specific storage (Ss) by the equations


T=mK S = mS


(11)

(12)


where m   is thickness. These equations assume that K      and Ss are uniform.
Computed values of T and S for porosities ranging from 10 to 90 percent are presented in table 2.


                                 TABLE 2
             Estimated values of transmissivity and storage coefficient for porosities ranging from 10 to 90 percent.

         0    ,     percent porosity

         T    ,     transmissivity, ft2 day-1

         S          storage coefficient, dimensionless


6.4 x 105 1.3 x 106 1.9 x 106 2.6 x 106 3.2 x 106 3.9 x 106 4.5 x 106 5.1 x 106 5.8 x 106


    S'

3.1 x 10-6 6.1 x 10-6 9.2 x 10-6 1.2 x 10-5 1.5 x 10-5 1.8 x 10-5 2.1 x 10-5 2.4 x 10-5 2.8 x 10-5


Based on a 15-foot thickness of aquifer.


      The caliper - flowmeter log of the Peninsula well showed that the cavernous water-bearing zone extends in depth from 2,930 to about 2,945 feet, a thicknessof 15 feet. If the porosity is assumed to be about 50 percent, then the transissivity and storage coefficient would be 3.2 x 106 ft2 per day and 1.5 x 10-5, respectively. The same values of T and Swould apply for a 105-foot