Study Duration: 2013-2016

This case study is for landscape architects, engineers, and asset owners, who would like to understand more about how ECOncrete’s technologies are integrated into projects and deliver a unique return on investment. By implementing a technology that makes concrete environmentally beneficial, projects enjoy facilitated permitting, lower mitigation penalties, and streamlined construction, not to mention the value that comes with thriving waterfront ecosystems. While ECOncrete’s technology can be applied to any marine concrete, this pilot project was the first to validate ECOncrete’s technologies when applied to coastal armor and pile jackets. 

 

Problem & Solution

In our marine environment, we build 70% of infrastructures from concrete. While it’s strong and versatile, this material is detrimental to life underwater, leaving our waterfront assets, ecosystems, and communities vulnerable to a changing climate. Concrete’s underwater impacts are a consequence of three design features: a toxic chemical composition and smooth surface textures discourage marine life from growing on the structure, resulting in less local biodiversity and more invasive species. Flat-plane designs provide little shelter and few growth points for marine biology, resulting in infrastructure that stays lifeless for decades. These design failures combine to create infrastructure with high environmental penalty costs, higher maintenance needs, and lower resilience.  

 

ECOncrete resolves these three features with a patented admix, texture agents, and molds proven to improve the structural and ecological performance of concrete. The admixture seals and strengthens concrete by up to 10%, while a combination of texture agents, liners, and molds bring high surface complexity and design features. ECOncrete’s technology enables a rich layer of marine life, like oysters, tubeworms, and corals to grow, thereby generating an active carbon sink and biodiverse ecosystem, while creating structural benefits, such as greater strength and durability. The technology meets industry standards, is flexibly sourced, and can be easily integrated into any concrete marine infrastructure.

 

Project Details

Brooklyn Bridge Park is a post-industrial 85-acre public space on the Brooklyn side of the East River. An environmental initiative has revitalized the park’s 1.3-mile (2.1 km) waterfront, and, as part of its renovation, ECOncrete installed two projects that serve the local aquatic ecosystem and retrofit critical infrastructure. At Pier 4, ECOncrete installed precast coastal armor units within the existing riprap to provide shore stabilization and increase biodiversity. The water-retaining coastal armor units hold a volume of thirteen gallons (fifty-nine liters) of seawater each, mimicking the intertidal habitats of natural rock pools and providing shelter for species at low tide. The armor units were placed between the mean low and mean high water lines to accommodate an array of species typically absent from standard riprap.  

 

At Pier 6, ECOncrete designed a concrete jacket to encase the pier’s wooden piles and offer a substrate for the buildup of marine life. Textured forms give the jacket a rough surface and dimensionality, effectively encouraging marine life like oysters and tubeworms to easily attach and grow. Both the coastal armor and pile jackets, like any ECOncrete solution, support a wide array of biodiversity critical for a healthy marine system and can be adapted to promote specific species of conservational value.

 

Biological Monitoring

The study compared ECOncrete’s tide pool-like coastal armoring to the rocky area surrounding them. After nine months, in August 2014, the Pier 4 coastal armor units showed 89%-100% live cover. Various algae, copepods, amphipods, isopods, and Sabellidae and Spirorbis worms covered the armor.  In addition, the tide-pools contained two Harris mud crabs (Rhithropanopeus harrisii) and seventeen post-larval and juvenile fish. In contrast, the rocky area surrounding the pools had poor biological functioning.  

 

The study also compared ECOncrete’s jackets to Portland-cement and fiberglass based jackets. Monitoring at three, ten, and fourteen months post-deployment revealed 70%-100% live cover on ECOncrete’s pile jackets. In comparison, the control jackets presented only 20%-50% live cover and only one-tenth of the biomass accumulation shown on ECOncrete’s jackets. There were significant amounts of filter-feeding organisms on the ECOncrete pile jackets, such as barnacles, sessile polychaetes, sponges, and bivalves, which contribute to improving the local water quality. Several blue crabs (Callinectes sapidus) mated on the jackets, and ecosystem engineering species, such as barnacles and sessile polychaetes, were found. In addition to creating the basis for a thriving ecosystem, these sessile, or sedentary marine creatures cement their calcium carbonate shells to the concrete, and build an additional layer of protection from hydrodynamic forces and chloride penetration, known as bioprotection. This layer leads to reduced maintenance costs and a more durable pile jacket. A hands-on (level II) inspection conducted by CH2MHILL engineers a year post-deployment found hard and sound concrete. 

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