U.S Geological Survey, South Florida Ecosystem Program: Place-Based Studies

Project: Evaluation of Methods to Determine Groundwater Seepage Beneath Levee 30, Dade County, Florida

Web Site: Evaluation of Methods to Determine Groundwater Seepage Beneath Levee 30, Dade County, Florida

Location: Southeast Coast; Miami-Dade County

Principal Investigator: Roy Sonenshein, sunshine@usgs.gov, 305.717.5824

Project Personnel: Sally Garson (now with U.S. Army Corps of Engineers)

Other Supporting Organizations: U.S Army Corps of Engineers

Associated Projects: Evaluation of Methods to Determine Groundwater Seepage Beneath Levee 31N, Dade County, Florida (Helena Solo-Gabriele, hmsolo@miami.edu, 305.284.3489)

Overview & Status: The amount of water seeping under the protective levee system between Water Conservation Area 3B (WCA3B) and the Pennsuco wetlands to the east is poorly estimated. The objective of this project is to evaluate methods of determining seepage from WCA3B near Levee 30 and ground-water seepage beneath Levee 30. Plans to restore historical hydrologic conditions in the northeast section of ENP include the raising of water levels in ENP and WCA 3B, which overlie the Biscayne aquifer, an extremely permeable aquifer. The increase in water levels is likely to cause an increase in seepage losses to the east under Levee 30. Groundwater level and surface-water stage data, canal discharges, and vertical seepage data have been collected and evaluated with respect to vertical seepage from the Everglades and horizontal flow in the Biscayne aquifer. A ground-water flow model has been developed to quantify ground-water seepage beneath the protective levee.

Needs & Products: The groundwater flow model developed through this project is needed to estimate the effects of changing water levels in Water Conservation Area 3B (WCA 3B). The results of the study will be used by the South Florida Water Management District as part of the Lake Belt study in Miami-Dade County. The final report, "Methods to Quantify Seepage Beneath Levee 30, Miami-Dade County, Florida" will document the results of the data collection and modeling efforts. The water level and stage data are available on the SOFIA web site for use by other researchers. Additional data will be made available upon final approval of the report. The U.S. Army Corps of Engineers coordinated the drilling of the monitor wells. Results published include: 1) Seepage Beneath Levee 30 in Northern Dade County: USGS Fact Sheet 132-96: 2) Quantifying Seepage Beneath Levee 30, Dade County, Florida: Abstract in U.S. Geological Survey Program on the South Florida Ecosystem - Proceedings of the Technical Symposium in Ft. Lauderdale, Florida, August 25-27, 1997: USGS OFR 97-385.

Application to Everglades Restoration: The accounting of all significant hydrologic inflows and outflows to the Everglades ecosystem of the south Florida mainland is a key element of the South Florida Ecosystem Program. The model results will be used to predict seepage losses from Water Conservation Area 3B based on future restoration scenarios.