Client: Florida Department of Transportation, District 4
Location: St. Lucie and Martin Counties, Florida, USA
Challenge. Determine appropriate repairs or replacement of articulated concrete block (ACB) mattress installed to protect nearly 14 miles of roadway and embankment
Solution. County Road 707 along the Indian River experienced major damage during the 2004 hurricane season. Subsequent emergency repairs to the roadway and its embankment included installing ACB mattress. Storm events in 2005 caused considerable damage to portions of the repaired shoreline. INTERA assessed the condition of the existing ACB, modeled wave conditions at the site, and developed appropriate alternatives for repair or replacement of the ACB. Our engineering evaluation revealed that the damaged ACB mattress revetment could only withstand conditions corresponding to an approximately three-year return period event. Given these facts, INTERA developed three conceptual alternative designs. Alternatives considered removal of the existing revetment. Since this would have required significant costs and further disturbed this environmentally sensitive area, the desired alternative incorporated the existing protection and provided for offshore wave attenuation via mangrove plantings. This alternative had the advantage of a low cost, the environmental benefits associated with a mangrove forest, incorporating the existing revetment, and not interfering with any protection installed by homeowners because it sat below mean high water.