Example of a matured living shoreline, which Strawn estimates to take about five years. Contributed photo

FL - $200000 state grant awarded to Craven County for living shoreline, a natural shoreline protecter

A state grant will be utilized to stabilize 300 feet of a coastal waterline at the Hwy 17/70 bridge on-off ramp, using natural materials.

Craven County was awarded $200,000 from the North Carolina Department of Justice Environmental Enhancement grant program to install a protective living shoreline and marsh sill on this section of the New Bern highway. The Hwy 17/70 bridge on-off ramp, where the living shoreline will be, is located near the Bridgepointe Marina in downtown New Bern.

Planning and Inspections Director Chad Strawn announced that the county was awarded this grant during the Dec. 4 Craven County Board of Commissioners meeting. Strawn described a living shoreline as a protected stabilized coastal edge made of natural materials such as plants, sand and rock.

First, a marsh sill rock wall, made of granite, will be installed about 15 yards offshore, according to Strawn. The living shoreline will be composed of native marine grass plantings and after the initial sediment is deposited other plants will establish growth, Strawn said.

The rock barrier wall will decrease wave energy, allowing the planted marine grasses to propagate in shallow water, since the grasses are protected from wave action, according to the county grant application.

“Unlike a concrete sea wall or other hard structure, which impedes growth of plants and animals, living shorelines grow over time,” Strawn explained. “The proposed project was strategically selected to protect the Hwy 17/ 70 abutment from sustaining future damages, like what we saw in the aftermath of Hurricane Florence.”

During Hurricane Florence in 2018, the East Front St. Causeway/Bridge and the Hwy 17/70 Bridge at the Intersection of Howell Drive and East Front St., was severely flooded from high tides and storm surge, according to the county grant application. Estimates of flood height at this key intersection adjacent to the bridge Indicated showed the surge topping 11 feet above sea level.

Floodwater heights caused the on-off ramp to flood and become impassable, which made the ramp inaccessible. The grant application further explained that emergency vehicles were unable to travel in or out of downtown New Bern, and flooding on the causeway closed an evacuation route.

The grant application listed multiple long term benefits of the living shoreline and marsh sill to include:

  • Provides measures to combat sea level rise, resulting in long term benefits to transportation infrastructure.
  • Provides immediate flood mitigation/alleviation to vulnerable transportation infrastructure.
  • Provides additional armor to a major bridge system to defend wave action, pilling scouring and floodwater.
  • Prevents vegetation and storm debris from accumulating and overtopping the causeway at East Front Street and Howell Road.
  • Provides mitigation and protection of municipal water/sewer infrastructure buried in the should of East Front Street causeway.
  • The living shoreline component of the project will filter and improve water quality in the Neuse River, as well as provide sustainable habitat and spawning grounds for marine life.
  • The project is a “green project” which promotes environment enhancement of water quality in the Neuse River.
  • The project benefits the underserved community of Craven County by protecting the water main buried under the Front Street causeway that serves this community.

Over time, as the living shoreline flourishes, the native marsh grasses will fully mature and grow away from the shoreline, towards the rock wall, filling the open space with more living shoreline.

“I think in two years you’ll start seeing a good amount of accretion of land behind that breakwater,” Strawn said. “Depending on the establishment of the wetland species that take effect behind that marsh sill, I think you’ll see pretty good maturity within five years.”

In order to avoid delays and down time in achieving progress on this project, some precursor project studies have already been completed, according to the grant application.

“The preliminary studies undertaken to date have enabled a qualitative determination that this site Is, In fact, favorable and well suited to support construction of a properly designed marsh sill and living shoreline,” is written in the grant application.

Strawn told the Commissioners that their goal is to install the breakwater, or marsh sill, within the next six months.

Read more.