Launch Slideshow

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Friends Indeed

Friends Indeed

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    To eliminate erosion and safety hazards in one of the system's canal, a stormwater system with ditch bottom inlets was installed. Photo: Orange County Public Works Department

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    During several projects, a bypass system was built to protect construction sites from the quick-rising waters that are typical of central Florida's wet season.

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    A Florida public works department used rip-rap to stabilize rivers in a canal system that suffered severe erosion in the aftermath of a destructive hurricane season.

The triple threat of hurricanes Charlie, Frances, and Jeanne pounded Florida in 2004, causing several locations of Orange County's canal network to fail. That left the county's Public Works, Roads & Drainage Division with few options to address costly $3 million repairs to the various canal and pond systems, whose banks eroded severely and threatened the foundations of both public and private properties as well as the county's water quality.

Faced with budgetary constraints, the county needed additional funding to fully restore severely damaged stream banks and conveyance systems of half a dozen rivers, ponds, and canals. Florida Natural Resources Conservation Service (NRCS) stepped in and offered a 75% matching grant for the project. The catch? To secure the additional funding, the division had to design, permit, and retrofit the banks within 180 days.

To expedite the project, the division sought engineering consulting services and processed the proposals for design and construction on an emergency basis through the County's Purchasing Department. That brought in the Florida Water Management District (WMD) and NRCS for requirements needed for the bidding process, which involved a variety of challenges in both topography and water flow.

The project was a major challenge and involved reinforcing and stabilizing eroded banks of Eastbrook Canal, Park Manor Canal, the north and south branches of Little Wekiva River, Nashville Avenue Pond, and Lake Underhill Canal.

Mats Stabilize Outfall

An outfall into Eastbrook Canal had experienced chronic erosion problems that were further aggravated by the hurricanes.

Steep side slopes presented a safety hazard, and the area was difficult to access because it was located between a residential subdivision and an apartment complex. Contractors arranged an agreement with the complex to store material and access the site while the division evaluated options to stabilize the canal banks, prevent future erosion, and enable timely construction.

Although the division considered enclosing the canal with a pipe system (an expensive project in itself), it settled on a more feasible approach: to stabilize the banks with armoring. That would reduce stabilization and erosion issues, maintain the canal's flow, and accommodate a low-lying lateral storm-sewer pipe that discharges into the canal.

The division chose to use an articulated concrete mat system known as “cable concrete,” which is more expensive than other armoring options but requires little long-term maintenance plus, it's pervious, aiding in the infiltration and water quality benefits of the canal. Installation occurred within the existing right of way, so no additional easements were necessary.

  • Construction: $389,000
  • Design: $30,000