Herbert Hoover Structure Replacement S-286 & S-287

The work includes demolition and removal of the existing Herbert Hoover Dike Culverts HP-2 and HP-3 and the construction of new water control structures S-287 and S-286 at their respective existing locations.  The demolition and reconstruction efforts will require the installation of steel sheet pile cofferdams at both the landside and lakeside of each culvert in order to dewater each construction site.  These structures will include cast-in-place reinforced concrete foundations, headwalls, and box culverts.  Combination flap/slide gates will be installed at the lakeside headwall of each structure.  S-287 will consist of one (1) 7-foot by 7-foot culvert with an approximate barrel length of 96 feet.  S-286 will consist of one (1) 7-foot by 7-foot culvert with an approximate barrel length of 96 feet.  At the completion of each embankment the crest elevation will be reduced from its current crest elevation of 36 feet to a final crest elevation of 32 feet.  Riprap will be installed along the lakeside embankment faces, and control buildings will be installed on the lakeside work platform at each structure.  Work also includes by-pass pumping, grassing and turbidity monitoring.