At its May 4, 2022 meeting, the City Commission approved a referral to the Public Safety and Neighborhood Quality of Life Committee (PSNQLC) to discuss the practicality of 3D printed “living” seawalls; and

At its January 11, 2023 meeting, the PSNQLC members discussed the item at length and made a motion for Public Works to explore the feasibility of incorporating a seawall pilot program and replace traditional concrete panels used in seawall construction with 3D printed concrete seawalls.

At its May 23, 2023 meeting, Public Works presented the PSNQLC members, information on a 3D panel option that is planned to be produced by a Miami-Dade County based manufacturer.  Committee members made a motion to proceed with a pilot program as recommended by Public Works.

A seawall pilot project with 3D panels is expected to have a similar cost and a similar construction installation method as constructing the seawall with the traditional pre-cast concrete panels specified in the City’s Public Works Manual. The 3D panels can be used to meet the City’s requirement of the top of cap seawall elevation of +5.7 feet (NAVD). Compared to a traditional seawall project, the project timeline for 3D panels is expected to be 3 to 9 months longer due to permitting.

Cost

The total capital cost of a seawall project is expected to be similar for seawalls using 3D panels as for seawalls using traditional concrete panels. The average cost for a typical, 40 – 100 linear foot City of Miami Beach seawall project is $3,550/linear foot (in 2023 dollars): $850/linear foot for design and $2700/linear foot for construction, based on recent City projects.  Structural testing of the 3D panels suggests that the 3D panels will have a 50-year design life, similar to traditional concrete panels. Accordingly, the frequency of replacement is expected to be similar, indicating a comparable equivalent annual cost for seawalls with 3D panels as for seawalls with concrete panels.

If the permitting agencies consider the 3D panels to have an environmental mitigation value, then this may reduce or eliminate the need for installation of rip-rap in the vicinity of 3D panel seawalls, thereby reducing the overall project cost. The costs of other seawall components such as the precast piles and the concrete cap is expected to be unchanged, regardless of the type of panel.

Permitting

The permitting process for a traditional seawall (no environmental resources impacts) has a typical duration of 6 months. The Public Works Department anticipates that the permitting timeframe will be approximately 9 – 12 months for a seawall with 3D panels, considering that this is a new and untested technology that may be closely scrutinized by the regulatory agencies.

At least three regulatory agencies are typically responsible for issuing permits for seawall projects. These agencies are Miami-Dade County Department of Environmental Resources Management (DERM), South Florida Water Management District (SFWMD), and U.S. Army Corps of Engineers. These permitting agencies have not issued a permit for a seawall using 3D panels, nor have they provided an estimate of the duration of the permitting process for seawalls using 3D panels. Kind Designs has had initial discussions with Miami-Dade County DERM, and DERM is supportive of a pilot project to evaluate the 3D panels in lieu of riprap mitigation that is currently required.