CRMC to work with City of EP, TNC on nature-based infrastructure project

January 16, 2020, East Providence — The City of East Providence is partnering with the Rhode Island Coastal Resources Management Council (CRMC) and The Nature Conservancy to create two different types of hybrid shoreline in East Providence, to examine how they might slow erosion on the area’s steep coastal bluffs at Rose Larisa Park.

A view of the beach at the park, and the eroded bank

The project includes two phases using different shoreline treatments, and is part of a larger regional project in New England coastal states designed to analyze different nature-based infrastructure used for erosion control. The project is funded through the National Oceanic and Atmospheric Administration’s (NOAA) Coastal Resiliency Fund.

The over-steepened bluffs at the site of the former Crescent Park and adjacent shoreline rise 20 to 30 feet above the narrow beach. Erosion has carved out the lower third of the bluff in several sections of the shoreline. Fallen trees where the root systems have been undermined are common features.

Phase I of the project will be the construction of an intertidal stone sill, consisting of three low stone structures that will be topped by seawater at high tide, and about three feet high at low tide. Sand fill will be added landward of the sill and planted in order to create saltmarsh. Phase II is a bluff treatment that uses stone at the base and logs made of coconut fiber farther up the slope. The bluff will be planted with native vegetation. Both shoreline treatments are considered hybrid because they use “hard” (stone) and “soft” (biodegradable materials and vegetation) elements. Unlike concrete or stone walls the hybrid shorelines are designed to prevent erosion while also improving habitat.

This picture shows a section of an older, failed revetment now fallen onto the beach

Both areas will be monitored using topographic surveys, photographic documentation, and vegetation monitoring. Signage will be placed on-site and the project progress and monitoring results will be posted on the City of East Providence website.

This section of East Providence’s shoreline contains debris from various failed attempts at erosion control such as bulkheads, seawalls, and riprap. In some cases, debris comprised of large concrete slab sections over 20 feet long sit at the bottom of the bluff. In addition to posing a public safety hazard, this debris does little to absorb incoming wave energy, and is actually exacerbating the erosion problem.

“One of the goals of this project is to find an effective, convenient erosion control method that does not worsen erosion in adjacent areas, and also provides habitat benefits,” said Janet Freedman, CRMC coastal geologist. “The erosion control structures that already exist in the area do offer protection against storm-induced erosion, but to the detriment of beach and bluff habitat. Many of these structures already extend into the intertidal area. As sea levels rise, the intertidal habitat and limited lateral shoreline access will disappear altogether. We need something better, and are hoping this project will provide valuable insight and solutions.”

This section of the beach at Rose Larisa will be the site of the hybrid shoreline project

CRMC data shows there is an increasing demand for erosion control and protection from area homeowners and businesses. According to the CRMC staff report, a search of the CRMC data base indicated that there were 47 applications for shoreline protection within a mile of the Rose Larisa Park. Ten of the applications were for new shoreline protection structures, 36 were to maintain or replace existing structures, and one was for non-structural treatment.

Phase I has been funded by the NOAA grant, and according to The Nature Conservancy, Phase II will likely cost approximately $100,000 and the CRMC has secured permits for both phases. The CRMC permit will be valid for three years, and Freedman said it is the partners’ hope that funding will be secured for Phase II within that time frame.

According to Freedman, a recent workshop on this method in North Carolina showed that it costs more to repair and maintain hardened structures like bulkheads or rip-rap than it does to construct these living shoreline structures.

The eroded and destabilized bank is littered with failed revetments, fallen trees, and debris, posing a safety hazard

“The City of East Providence has been a great partner, and it’s a perfect potential demonstration site, since we have some failed erosion control structures on-site,” said Caitlin Chaffee, CRMC coastal policy analyst. “We’re going to be removing some of the debris, and we are also testing these new techniques. This compliments what we’re looking to do with CRMC policy, to encourage these nature-based strategies, and we hope to show that they’re just as viable as other structures.”

Chaffee informed the CRMC Council that the partners had also submitted a proposal for Phase II to be funded at least in part through the R.I. Coastal and Estuarine Habitat Restoration Program and Trust Fund, which is administered by the CRMC. Out of the projects that received the regional funding from NOAA, Rhode Island and Maine were the only states that planned to install new projects. The others were studies of previously installed projects, Freedman said.

 "The city's shoreline and access to the bay are some of our most treasured features," East Providence Mayor Bob DaSilva said. "We'd hate to lose any of our existing shoreline to erosion and welcome this project as a way to find the best erosion control method. We thank Rhode Island Coastal Resources Management Council and The Nature Conservancy for its support on slowing the erosion of the coastal bluffs at Rose Larisa Park."

“Much of Rhode Island’s coastline is eroding, and it’s a problem with no easy fix,” said CRMC Chair Jennifer Cervenka. “This nature-based erosion control is one of the first of its kind in Rhode Island, and New England, and it could mean a better solution for coastal managers like the CRMC, and for coastal property owners. We can’t stop erosion completely, but living shoreline infrastructure like this might buy our shores some valuable time.”

The CRMC plans to install wooden camera posts at the site so the public can put their camera or smart phone/device in the same spot to take pictures of the project’s progress. The public is also encouraged to upload pictures of the site when they visit Rose Larisa Park to the https://mycoast.org/ri/coastal-resilience web site.