32 FLORIDA GEOLOGICAL SURVEY
These aquifers are separated by material having a low vertical permeability.
2. The water supply for Venice, other than that for emergencies, is withdrawn from 42 wells that tap either the first or the second artesian aquifer or both. The water from the first artesian aquifer is generally of a better quality than that from the second artesian aquifer.
Water from the Floridan aquifer is highly mineralized but is used during emergencies.
3. At least two of the wells at the Venice water plant are open to both the second artesian aquifer and the Floridan aquifer. Water from the Floridan aquifer moves up these wells into the second artesian aquifer and contributes in part to a poorer quality of water in the second artesian aquifer.
4. A coefficient of transmissibility of 5,600 gpd per ft, a coefficient of storage of 8.7 x 10-5, and a coefficient of leakage of 1.3 x 10-' gpd per ft:' were calculated from a pumping test on well 9S. The wells used in the test were open to both the first and second artesian aquifers. From a test on well 31, the coefficient of transmissibility was calculated to be 8,500 gpd per ft; the coefficient of storage, 1.3 x 10-'; and the coefficient of leakage, 7 x 10-3: gpd per ft'. The wells used in the test were open to the first artesian aquifer.
5. Should the proposed waterway be constructed, the salt-watcr will form a wedge in the water-table aquifer beneath the waterway. If the Venice well field is pumped intensively, salt water will seep from the waterway into the first artesian aquifer and then into the well field.
The estimates of the increase in the chloride content of the pumped water under certain conditions range from 80 to 1,800 ppm.
CONCLUSIONS
1. Wells at the Venice well field, which are cased only through the first artesian aquifer but which tap the Floridan aquifer, allow water of an inferior quality from the Floridan aquifer to contaminate the second artesian aquifer. This contamination can be prevented by extending the casing through the second artesian aquifer.
2. Grouting or otherwise treating the section of the waterway along the well field so as to make the formations less permeable