138 REPORT OF INVESTIGATIONS NO. 50
total drawdown was only about 1 inch. This probably indicates a very cavernous spongelike formation with solution channels forming an interconnected system. The cavernous nature of the lower zone of the Floridan aquifer is shown also on the logs of wells drilled into it. Only one observation well was available, therefore the coefficients computed from well 832-120-14 could not be checked to determine if they are representative of the aquifer in the area of influence of the pumped well.
The record of test 4 was difficult to analyze because of the small drawdown, the surging of the well, and the relatively large amount of extraneous influence on the water level in the observation well. However, the coefficient of transmissibility of 4.3 million gpd/ft probably is of the correct order of magnitude. Similar results were obtained in a similar test made by Mr. Charles Black of Black and Associates, consulting engineers, Gainesville, on two other wells cased into the lower zone of the Floridan aquifer in Orlando (oral communication, 1962).
Thus, the lower zone of the aquifer in the Orlando area appears to have about 8 times the water transmitting capability of the upper zone. A transmissibility of 500,000 gpd/ft indicates a very productive aquifer. The transmissibility of over 4 million shows the aquifer to be one of the most productive in the country.
The principal difficulty in determining aquifer coefficients in Orange County is that the Floridan aquifer is not homogenous and isotropic as assumed in the mathematical model aquifer. Also there are no wells in the area that are open to most of 2,000 feet of the aquifer. Therefore, the coefficients in table 14 are at best approximations of the characteristics of different sections of the aquifer. Flow net analyses using the discharge of springs in the county and also using pumping rates in the Cocoa well field indicate transmissibility values of about 2 million gal/day/ft. This value may be more representative of the average T of the Floridan aquifer in Orange County than is table 14.
When a well in the lower zone of the Floridan aquifer is pumped, the cone of influence spreads very rapidly for adistance of several miles. The pumping records of two wells in the Primrose plant in Orlando (832-120-3 and 832-121-20) were compared with the recorder chart from an observation well (833-120-3), 1.4 miles from the Primrose plant for a period of one month. Small, but very sharp and distinct, changes in water level in the observation well were detected each time one or both of the supply wells were turned on or off. (See fig. 42). Because the wells draw water from a large