The City of Miami Beach (CITY) receives potable water from the Miami-Dade Water and Sewer Department (MDWASD) by means of four transmission mains. One of these transmission mains is located along the Venetian Causeway. Water is conveyed into the Venetian Islands from MDWASD through one 30-inch ductile iron pipe (DIP) water main that splits into two parallel 16-inch water mains at each bridge crossing. These parallel mains travel aerially along the Venetian bridges on the north and south face of each bridge, with the exception of the recently installed subaqueous segment between Rivo Alto Island and Belle Isle.

Similarly, sewage is transmitted from the Venetian Islands due east through a series of sewer main aerial crossings on the Venetian Causeway historic bridges. Each bridge carries a DIP force main that ranges in size from 8 to 12 inches. The crossings between Rivo Alto Island and Belle Isle, and between Belle Isle and Dade Boulevard on the main island, were recently replaced sub-aqueously through emergency projects.

The overall condition of the remaining water and sewer main aerial crossings along Venetian Causeway is poor. The replacement of these aerial water and sewer mains crossings were prioritized in the City Water and Sewer Master Plans due to high probability and consequence of failures. Mechanically, all the aerial TR Flex bell and spigot pipe (inspected under a previous service order) have a failed coating system or are uncoated, resulting in significant corrosion. Air release valves (ARV) show extensive corrosion from exposure to the saltwater. Furthermore, in multiple locations failed water main supports have caused pipe deflections that appear to exceed manufacturer recommendations for the TR Flex joints. From a structural standpoint, in general pipe hangers show signs of significant corrosion. Some pipe supports are failing and/or missing at most of the bridges along Venetian Causeway. Several pipe failures have caused significant impact to our residents and to the environment.

The City retained Hazen and Sawyer, PC, Prime Water and Sewer Consultant, to design the replacement of the pipes as recommended in the Master Plan, per Resolution No. 2020-31211. The design effort is now completed and is currently in permitting. The scope of work includes the following:

• Four horizontal directional drill segments to replace water main bridge-aerial crossings between San Marco, San Marino, Di Lido and Rivo Alto Island and between Belle Isle and Dade Blvd in Miami Beach.

• Two horizontal directional drill segments to replace sanitary force main bridge-aerial crossings between San Marino, DiLido and Rivo Alto Islands.

There will be no fiscal impact as this is a request to waive the independent cost estimate requirements and authorize the competitive bidding of the Venetian Causeway Water Mains and Force Mains Replacement (Phase 2) Project.  The project's construction cost was estimated in October 2023 by the engineer of record at $20 million (Class 2 estimate with +20% to -15% accuracy, thus in the range of $17 million to $24 million). This project is fully funded as part of Capital Project No. 28520 Water and Wastewater Mains and Rehab.

This pipeline replacement project is anticipated to have a construction duration of approximately 18 months, and it is required to be completed prior to July 2025, when the Miami-Dade County Department of Transportation and Public Works (DTPW) plans to initiate the construction of the Venetian Causeway Bridge Replacement Project.