As a result of a referral from Commissioner Meiner, the Public Works Department researched the feasibility and benefits of installing hybrid seawalls with 3D printed living shorelines. Staff contacted two companies (The Reef Design Lab and The Addition Company) that manufacture 3D printed living shorelines that are compatible with seawalls. These two alternatives were assessed and compared against the construction of conventional concrete seawalls. Both companies create products that propose to improve the water quality of the surrounding water bodies by:

• Creating additional spaces for marine organisms to grow;

• Providing additional shade and water retention critical for tidal marine life;

• Creating a protective habitat for filter feeders such as oysters; 

• Creating a complex habitat that offers protection and foraging areas for fish and invertebrates

The Addition Company

Miami-based company founded by Anya Freeman that has developed 3D printed concrete seawall panels that replace the traditional concrete panel of seawalls and create complex micro habitats. The panels are made by mixing concrete with recycled marine plastic fibers and can be constructed with or without structural rebar. The Addition Company is initially launching the panels with structural rebar to meet the requirements of the local building codes however this will reduce the life expectancy of the 3D printed seawalls to equal the life expectancy of traditional seawall panels due to the corrosive impact saltwater has on rebar.

The Addition Company’s 3D printed panels are installed in place of the traditional concrete seawall panels and are considered structurally equivalent to the traditional sea wall panel. The panels are sold to contractors at a cost similar to those of concrete seawall panels and are installed using the same methods. Additionally, the company is local, and the cost of transporting would be minimal. This means that traditional seawall panels can be replaced with the 3D printed panels at no additional cost.

The Addition Company is familiar with the local Miami-Dade design standards and codes as they have a few pilot projects currently underway in Miami-Dade County: a private seawall replacement (100 LF) located on the Miami River working alongside consultant Moffit and Nichol, in which the conventional seawall panel will be replaced with a 3D printed seawall panel with rebar to meet local regulations; a private seawall replacement on the Miami River, near the Flagler Bridge; and another local private seawall replacement located in Key Biscayne. Additionally, they have a project in the British Virgin Islands in which the conventional seawall panels will be replaced with a 3D printed seawall panel without rebar. All projects are currently projected for installation in late July and early August. Furthermore, The Addition Company’s panels are subjected to laboratory testing for various structural conditions, with and without reinforcement, and the testing reports will become available in the near future as more testing is completed.

The Reef Design Lab

The Reef Design Lab is an Australian-based Not-for-Profit multidisciplinary design organization, founded by Alex Goad, that develops marine habitat infrastructure for a range of research and commercial applications. They developed 3D printed modular habitat tiles that are retrofitted to seawall panels to create complex micro habitats, such as crevices and rock pools. The Reef Design Lab has launched projects around Australia and other European countries and is currently studying the impacts that their tiles may have on water quality.

The Reef Design Lab currently has projects in Australia, Europe (Wales and Gibraltar), and Asia (Singapore) all installing the 3D printed tiles on existing seawalls as an addition to the structural seawall panel. The tiles do not require extensive structural analysis as they are attached to existing seawall panel. This is good for retrofit of existing seawalls. The ongoing projects are currently undergoing water quality monitoring and analysis in collaboration with the Sydney Institute of Marine Sciences.

Qualitative Comparison of the Two Alternatives
Both products provide similar water quality improvements and create similar habitats for marine life, with the main different being costs of materials and shipping of the tiles from Australia. A list of the pros and cons of each company’s products can be found in the table below:

Cost Comparison

The Addition Company panels are sold to contractors at a cost similar to those of concrete seawall panels and are installed using the same methods. The Reef Design Lab’s 3D Modular Tiles are constructed on top of the traditional seawall and are an additional expense. Each tile costs approximately $150.00 (USD) and must be freighted from Melbourne, Australia to Miami, which incurs incredible additional costs. The table below compares the rough cost of installation for the two alternatives.