L-30 Seepage Management

As Part Of The Comprehensive Everglades Restoration Plan (CERP)

The purpose of the L-30 Seepage Management Project was to develop information necessary to resolve critical uncertainties associated with seepage management technologies. GFA was contracted to install 4 monitoring wells and rehabilitate 3 existing wells within and on the L-30 levee. The wells for the L-30 project were designed to extend deeper and in a high flow zone creating drilling problems with loss of circulation and difficulty with maintaining an open hole for USGS logging. Once wells were logged and screen intervals were identified. GFA constructed the wells with 4” PVC and stainless steel wire wrapped screen. The orientation of the screen had to be carefully placed and identified.

Our services on this project included:

  • Installed floating turbidity barriers for wells located in or adjacent to WCA-3B
  • Installed surface casing several feet into the limestone formation
  • Advanced a 4-inch diameter continuous core to approximately -50 feet NGVD (the top of the Fort Thompson Formation). Split spoon samples were collected at one-half foot increments until the top of the limestone unit was encountered
  • Reamed borehole to the appropriate final well diameter for the monitoring. All boreholes were a minimum of a 2-inch annulus between the proposed well casing and the borehole
  • Developed the borehole until it produced clear, sediment free water
  • Backfilled the borehole, as necessary, to a depth that corresponded to approximately 10 inches below the base of the screened interval
  • Install a gravel pack around the well screen to approximately 10 inches above the top of the screen
  • Injected a slurry of bentonite and water through a tremie pipe above the top of the screen
  • Injected under pressure neat cement to the top of the borehole
  • Developed the well until discharge water was largely sediment free and ph, temperature, and specific conductance have stabilized for 12 consecutive hours
  • Constructed the well heads and demobilized equipment and restore the site to pre-construction conditions