South Contract 1 L67 A Structures, Spoil Mound Removal, and L 67 C Gapping for the Central Everglades Planning Project

Description of Project: The three structures are multi-barreled gated culverts with vertical slide gates, and a total length of 60 feet. The upstream and downstream inverts were determined based on historical low TW elevations (7.50 ft. NGVD in the gap between L-67 A and L-67 C Canals) and adjusted to accommodate the height of the barrel plus one foot of clearance. The upstream and downstream inverts were set to 1.50 ft. NGVD. The design flow for the three structures is 500 cfs with a design hydraulic head of 1.5 feet. The design velocity through the structures is 4.2 fps. The Scope of Work for this project will be to complete the design process for the project’s features. These features include the following four (4) items, (A) Install the proposed L 67 A levee structures; S-631, S-632, and S-633 detailed as new gated flood control culverts, with 5.5-ft. x 5.5-ft. manual vertical slide gates, two (2) sets of stop logs, each with total design capacity of 500 cubic feet per second (cfs) to convey water from WCA 3A to WCA 3B; (B) Remove the existing spoil islands directly to the west of the proposed structures to enhance the sheet flow into the S-631, S-632, and S-633 structures; (C) Excavate the corresponding gaps within the L-67 C levee to convey water from WCA 3A to WCA 3B; (D) Backfill the existing east-west agricultural canal between the L 67 A and L 67 C levees, to enhance the sheet flow through the WCA 3A, by removing an east-west ditch that currently redirects the sheet flow perpendicular to the natural southern sheet flow through the WCA 3A. The project’s consists of the installation of levee cofferdams, dewatering, excavation, clearing and grubbing, demolition, installation of HDPE piping, cast-in-place headwalls, zoned embankment backfill, the installation of needle gates, barge transportation of equipment, associated gate controls and instrumentation; site work grading and rip rap along the culvert’s discharge. Location of Project The L 67 A and C project is located in western Miami-Dade County, between WCA-3A and WCA-3B, west of C-111, north of the Tamiami Trail (US-41). This project will direct the sheet flow from WCA-3A through three (3) proposed gate structures; then flow southeastward through WCA-3B; then the water flows southward through structures under Tamiami Trail (US 41), and ultimately the flows continue south through Taylor Slough to Everglades National Park (ENP). Specific Project Challenges The structures S-631, S-632, and S-633 are proposed to be constructed on the existing L 67 A levee with the project, with a limited vehicular access for materials, equipment, or labor. The construction access to the project site will be from US Highway 41 (Tamiami Trail) by S-333 along L-67A and L-67C levees. The northern access is from S-9 Pump Station or by Everglades Holiday Park along the L-67A Canal. The site layout includes these features: Access, Staging of Equipment/Disposal, S-631, S-632, and S-633 Culvert structures, L 67 C Gap, and L 67 C backfill treatments. The contractor has sole responsibility for providing the necessary traffic control devices and responding appropriately for the protection of the public and his personnel. The general construction vehicular access is from US 41 (Tamiami Trail) by the S-333 structure along the L-67A and L-67C levees. The contractor will be required to access the west side of the L 67 A canal, adjacent to the L 67 A levee, with heavy equipment, to remove existing spoil islands on the west side of the canal. The contractor will also be required to fill an existing agricultural ditch that travels east west between the L 67 A and L 67 C. Environmental Conditions Contractor to assume all construction will be performed with surface water present. The Contractor will arrange their construction sequencing to work within the existing wetlands, surface waters, and permitting requirements. Consolidation Conditions The intent is for structures in this project will be built by one contractor, for the coordination of the project construction sequence. The northernmost structure, S-633, will require substantial completion, with the work moving southward to S-632. In this way, the contractor’s materials, labor, and equipment will not cross the recompleted structure. The coordination of this work sequencing, limited access, and environmental considerations, requires extensive coordination of one contractor. The degrade sections of the L 67 C levee will be required to be completed from the northern most degrade section southward, again so that the contractor’s materials, labor, and equipment will not cross the recompleted work. Industry is requested to identify strengths and weaknesses you may encounter with consolidating or not consolidating the work described above.

Division 03 -	Concrete, Precast Concrete.
Division 33 -	Utilities, Storm Drainage Utilities, Storm Utility Drainage Piping, Storm Utility Water Drains, Storm Drainage Structures.