BUREAU OF GEOLOGY


with the ocean would be expected. Cooler temperatures are to be expected in zones of large solutional caverns where larger volumes of water and increased velocities of flow are present, when compared to zones of lower transrnissivities."v

      To date (1973), the direction and amount of flow, if any, can only be speculated upon because of the lack of definitive data on hydraulic gradients and the horizontal extent and interconnection of the caverns. No pumping tests have been made to determine the hydraulic characteristics of the Boulder Zone. Therefore an analysis of natural water-level fluctuations rhay provide useful information on the hydraulic characteristics, including transmissivity of the aquifer system and the extent of hydraulic connection with the adjacent Straits of Florida.

      WATER - LEVEL FLUCTUATIONS IN THE BOULDER ZONE

      Fluctuations of the water level in the Peninsula well were continuously recorded from February 12 to March 1, 1970, and from November 25, 1970 to February 12, 1971. Long-term water-level fluctuations, lasting weeks or months, were related chiefly to changes in the density of the water column in the well due to dispersion of salt water and thermal conduction, to changes in atmospheric (barometric) pressure, and, perhaps, to seasonal changes in tides. Short-term cyclic fluctuations, lasting hours or days were related chiefly to' ocean and earth tides, and to atmospheric tide.

      A summary of events before and after collection of water-level data follows to help explain some of the variation in the water levels. Construction of the Peninsula well began June 19, 1969, and ended December 15, 1969. The well was drilled to a depth of 2,947 feet and contained 1,810 feet of 16-inch steel casing. On December 16, 1969, the well was pumped at about 3,-000 gpm (gallons per minute) with compressed air to clear cuttings from the hole, and caliper and fluid-velocity logs were obtained by the Florida Bureau of Geology. On December 17, 1969, the well was pumped for about 2 hours at 3,000 gpm and a water sample was collected for analysis by the U. S. Geological Survey. The temperature of the sample was 16"C (60.8'F), and its chloride content was 19,300 mg/i. The water level in the well was 0.4 foot above msl 35 minutes after pumping ceased. Subsequent measurements indicated a slow rise in the water level.

      From January 9 through January 29, 1970, fresh water from a nearby canal was intermittently injected into the well at rates ranging from 1,000 to 4,000 gpm for testing. On February 6, 1970, cement bond, electric, and gamma-ray logs were obtained. During February 12 through March 1, 1970,