New Haven County, Connecticut – PRIME led the engineering team that performed the various engineering certification analyses for Systems 2 and 3 of the Naugatuck River Flood Protection Project in order for this existing levee system to receive FEMA accreditation in accordance with 44 CFR Section 65.10.
This levee system built in the early 1970s consists of a combination of 5,800 linear feet of earthen levees, 7,800 linear feet of reinforced concrete floodwalls, numerous passive drainage structure closures, eight (8) railroad and street closure structures, six (6) sluice gate structures, and three (3) pumping stations. These systems protect the City of Ansonia, Connecticut from the floodwaters of the Naugatuck River and Beaver Brook.
FEMA advised the City of Ansonia that they would be updating flood maps for New Haven County and that the land behind the levees would be remapped as areas protected by Provisionally Accredited Levees (PALs). FEMA also indicated that they would begin the process of revising the Flood Insurance Rate Map (FIRM) to redesignate the areas behind the levees as prone to flooding, unless engineering certifications were not completed to show that the levee components were still functioning as originally intended in accordance with 44 CFR 65.10.
The work included, but was not limited to, the following: (1) determine required freeboard to satisfy 44 CFR Section 65.10; (2) inspection of levee system closure devices (flap valves, sluice gates, closure structures, etc.) and identify their repair requirements; (3) assessment of levee (rip rap) protection against erosion and scour; (4) assessment of the levee’s embankment and foundation stability; (5) assessment of the interior drainage systems within the protected areas behind the levees to ensure that drainage was effective (pumping stations, pressure conduits, channels, piped drainages systems); (6) assessment of Operation Plans and Maintenance Manuals; and (7) other miscellaneous items that were required for Levee System to meet current standards and requirements.
The various analyses resulted in a comprehensive report of the current state of the levee system with recommendations and cost estimates for remedial action necessary to be addressed before the City could obtain FEMA Accreditation for this system for necessary adjustments to the FIRM. The outcome of the report was that the levee system was functioning as intended and needed minor rehabilitation work performed to it. Certification was completed in December 2011.