Floodgates at Roads and Waterways

Access through the flood protection would be via levee ramps, highway ramps, floodwalls transitioning to vehicular swing type floodgates, and/or some combination thereof. There are several locations where, for certain hydraulic conditions, the design levee protection would be as high as elevation +15.0 NGVD 1988 datum and the natural ground is near elevation 0.0 NGVD. When road or highway access through the levee is required in the areas where excessively high floodwall and floodgates would be required, construction structures may not prove to be feasible. Therefore, for each levee crossing, three options are being considered. 

Option 1 Transition from the levee embankment to floodwall (T-wall and/or I-wall) and then from floodwall to floodgate at the location of the levee crossing.

Option 2 Construct a highway ramp from natural ground to the design elevation of protection at the levee crossing.

Option 3 Construct a highway ramp from natural ground to the minimum elevation where only I-wall is necessary (i.e. no T-wall floodwall required) to transition from the levee crown to the floodgate.

A floodgate would then be located at the intersection of the I-wall and the highway ramp. Five roads have been identified for proposed floodgates

Where waterways intersect the project levee alignment, two types of floodgate structures were analyzed. One using conventional construction methods built in the dry (Cast-In Place Structure) and the other using pre-constructed float-in methods (Float-In Structure). Braced steel sheet pile walls would tie the floodgate structure into the adjacent levee. Several structure designs are based on the design for other structures with similar loading and foundations conditions as noted. The following floodgates are proposed:

  Project Features Map