Bio-Engineered Oyster Reef Demonstration (LA-08)

LA-08

Purpose:

The purpose of this project is to test a new, bio-engineered, product to address rapid shoreline retreat and wetland loss along the Gulf of Mexico Shoreline in areas with soils of low load bearing capacity. For example, at Rockefeller Refuge, the direct Gulf of Mexico frontage and extremely low soil load bearing capacity (250-330psf), coupled with an average shoreline retreat of 30.9 ft/yr, present unique engineering challenges with a subsequent direct loss of emergent saline marsh.

Restoration Strategy:

The goal of this demonstration project is to evaluate the proposed technique as a cost effective technique for protecting areas of Coastal Louisiana’s Gulf of Mexico Shoreline with poor load bearing capacities.The demonstration project would consist of an Oysterbreak, approximately 1000′ long. The Oysterbreak is a light-weight, modular shore protection device that uses accumulating biomass (an oyster reef) to dissipate wave energy. The bio-engineered structure is designed to grow rapidly into an open structured oyster reef utilizing specifically designed structural components with spat attractant (agricultural byproducts) and enhanced nutrient conditions conducive to rapid oyster growth.

Required Monitoring: [1]

  • Topographic and bathymetric surveys (elevation, water levels)
  • Ground-level photography
  • Aerial photography
  • Wave attenuation (wave energy effects)
  • Oyster and Water quality monitoring

The Oysterbreak is constructed by placing modular units into an open interlocked configuration. The units are sized to be stable under storm wave conditions. The height and width of the Oysterbreak are designed to achieve a moderate initial wave energy reduction. As successive generations of encrusting organisms settle on the Oysterbreak, the structure’s ability to dissipate wave energy increases.

Location:

The project is located along the Rockefeller Wildlife Refuge Gulf of Mexico shoreline west of Joseph Harbor canal in Cameron Parish, Louisiana.

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Project Effectiveness: [2]

The oysterbreaks are providing habitat for oyster settlement and the top layers of rings should be the most likely to support oyster colonies. Recommended improvements include:

  • Types of cement applications
  • Lessening the space available for coastal erosion (the gap between coast and oysterbreaks needs to reduce to prevent further erosion).
  • Crest elevation between the oysterbreaks performed well in wave attenuation and shoreline erosion
  • Increase the height of the structure to improve wave breaking potential

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Progress to Date:

The cooperative agreement between the National Marine Fisheries Service and the Louisiana Department of Natural Resources has been executed. Construction was finalized in February 2012. This project is on Priority Project List (PPL) 17.

More Information on this Project:

Further Websites Regarding Oyster Reef Restoration:

 

 

Work Cited:

[1] McGinnis and Pontiff. (pages 4-6) LA-08 2012 Operations, Maintenance, and Monitoring Plan, 30 April 2018, https://www.lacoast.gov/reports/project/4224379~1.pdf

[2] McGinnis and Pontiff. (page 22) 2014 Operations, Maintenance, and Monitoring Report for Bioengineered Oyster Reef Demonstration Project (LA-08)

 

 

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CWPPRA Project Selection

          The planning process leading up to project selection includes the nomination of a project followed by development and evaluation of proposed projects based on engineering, environmental improvements, and economics.

          A general breakdown of CWPPRA Project Selection is as follows:

  • CWPPRA projects are brought to the Task Force by the public, local municipalities, state agencies, and federal partners.
  • In January and February, each year 10-20 projects from each of the four regions become Priority Project List (PPL) candidates.
  • Parish representatives then rank projects in each region, and by the end of the spring the Technical Committee selects 10 projects from the annual PPL candidate projects for further development.
  • Of these 10 candidate projects, the Technical Committee recommends 4 projects for the design phase (Phase I) at their December meeting.
  • The Task Force must approve the 4 projects for design at their next meeting in January.
  • Projects already in design can request approval to proceed to Phase II for construction, and the Technical Committee will recommend 1-4 of these to the Task Force. Ultimately, the Task Force approves 1-4 of the recommended projects for construction.
  • Following the Technical Committee’s meeting and PPL recommendations in December, the Task Force will meet to finalize the approved projects. This year’s Task Force meeting is scheduled for January 25th. 

          Stay up-to-date on the project selection for this year’s Priority Project List by visiting our website. You can read more about CWPPRA Project Selection in Understanding CWPPRA.

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LaBranche Central Marsh Creation

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Dredging of access/flotation canals for construction of I-10 resulted in increased salinity & altered hydrology that exacerbated conversion of wetland vegetation into shallow open water bodies. Land loss is estimated to be -0.543 percent/year based on USGS data from 1984 to 2011 within the extended project boundary.

The primary goal is to restore marsh that converted to shallow open water. Project implementation will result in an increase of fisheries and wildlife habitat, acreage, and diversity along with improving water quality. The proposed project will provide a protective wetland buffer to the railroad and I-10, the region’s primary westward hurricane evacuation route, and complement hurricane protection measures in the area.

The proposed solution consists of the creation of 762 acres of emergent wetlands and the nourishment of 140 acres of existing wetlands using dedicated dredging from Lake Pontchartrain. The marsh creation area will have a target elevation the same as average healthy marsh. It is proposed to place the dredge material in the target area with the use of retention dikes along the edge of the project area. If degradation of the containment dikes has not occurred naturally by Target Year 3, gapping of the dikes will be mechanically performed. Successful wetland restoration in the immediate area (PO-17 constructed in 1994) clearly demonstrates the ability for these wetlands to be restored using material from a sustainable borrow area (outlet end of Bonnet Carre Spillway). Engineering monitoring surveys of the marsh creation area and borrow area are planned as well.

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This project is located in the Pontchartrain Basin (Region 1), St. Charles Parish. It is bounded to the north by the railroad running parallel to I-10, to the west by the marsh fringe just east of Bayou LaBranche, to the south by Bayou Traverse and to the east by marsh fringe west of a pipeline canal.

This project is on Priority Project List (PPL) 21.

The LaBranche Central Marsh Creation project sponsors include:

Keep up with this project and other CWPPRA projects on the project page.

Oyster Bayou Marsh Creation

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Altered hydrology, drought stress, saltwater intrusion and hurricane induced wetland losses have caused the area to undergo interior marsh breakup. Recent impacts from Hurricane Rita in 2005 and Hurricane Ike in 2008 have resulted in the coalescence of Oyster Lake with interior water bodies increasing wave/wake related erosion. Based on USGS hyper temporal data analysis (1984 to 2011), land loss for the area is -0.75% per year. The subsidence rate is estimated at 0.0 to1.0 ft per century (Coast 2050, Mud Lake mapping unit).

The project boundary encompasses 809 acres. Specific goals of the project are: 1) create 510 acres of saline marsh in recently formed shallow open water; 2) nourish 90 acres of existing saline marsh; 3) create 17,500 linear feet of terraces; and, 4) reduce wave/wake erosion.

Approximately 510 acres of marsh would be created and 90 acres would be nourished. Sediment needed for the fill would be mined approximately one and a half miles offshore in the Gulf of Mexico. Half of the created acres would be planted. Tidal creeks and ponds would be constructed prior to placement of dredged material and retention levees would be gapped to support estuarine fisheries access to achieve a functional marsh. Approximately 17,500 linear feet of earthen terraces would be constructed and planted.

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This project is in Region 4, Calcasieu-Sabine Basin, located west of the Calcasieu Ship Channel and south of the west fork of the Calcasieu River.

This project is on Priority Project List (PPL) 21.

The Oyster Bayou Marsh Creation project sponsors include:

Keep up with this project and other CWPPRA projects on the project page.

 

Terracing

CWPPRA Restoration Technique: Terracing

The goal of building terraces is to achieve some of the same objectives as full marsh creation but over a larger area of open water, where marsh creation alone is not feasible. Terraces are long, earthen berms that are built by mechanically dredging material and piling and shaping the material to a desired height. Most terraces average around 3 feet tall, with shallow side slopes and a wide base. This size and shape optimize the amount of terrace that falls in the intertidal zone and will support wetland vegetation.

The objectives of constructing terraces are several and depend upon the location in which they are built. These include acting as a sediment trap to help build new land, reducing wave fetch and erosion on adjacent marsh shorelines, creating habitat for fish and waterfowl, and improving water quality to promote the growth of aquatic vegetation. Terracing projects constructed under CWPPRA have achieved each of these goals, with sediment trapping being most evident near the openings of sediment-laden bays or navigational waterways.

Terracing has become a widely used technique that is expanding across the Gulf Coast because of the success and cost-effectiveness demonstrated through CWPPRA and privately funded projects. Although these features may not look like natural marsh and often use geometric configurations, they are able to perform a lot of the functions of natural marsh in areas that have become vast open water. Developing this cost-effective technique for use in areas that have few other restoration options is a testament to CWPPRA’s ability to adapt to funding constraints and a quickly changing environment.

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TV-12 Little Vermilion Bay Sediment Trapping

 

 

 

 

Caminada Headlands Back Barrier Marsh Creation

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The Caminada Headland has experienced some of the highest shoreline retreat rates in Louisiana. Historically the shoreline has migrated landward at about 40 feet per year. Between 2006 and 2011, shoreline migration increased dramatically, exceeding 80 feet per year in near Bay Champagne and 110 feet per year in the Bayou Moreau area. The increased losses occurred in the wake of Hurricanes Katrina and Rita in 2005 as the breaches remained open for an extended length of time. The losses were exacerbated by Tropical Storm Fay and Hurricanes Gustav and Ike in 2008. Significant prolonged breaches greatly increase the net export of sediment from the headland.

In addition to the shoreline migration, the area is also experiencing high loss rates of interior marshes. As the beach and dune continue to migrate landward, overwashed sediment will be lost into newly formed open water and land loss rates will be exacerbated. The continued deterioration of Caminada Headland threatens thousands of acres of wetland habitat as well as critical infrastructure, including Port Fourchon, LA Highway 1, and the lower Lafourche levee system.

The goals of this project are to: 1) Create and/or nourish 385 acres of back barrier marsh, by pumping sediment from an offshore borrow site; 2) Create a platform upon which the beach and dune can migrate, reducing the likelihood of breaching, improving the longevity of the barrier shoreline, and protecting wetlands and infrastructure to the north and west. The proposed project is expected to slow the current trend of degradation in the headland.

This project would create 210 acres of back barrier intertidal marsh and nourish 175 acres of emergent marsh behind 3.5 miles of the Caminada beach using material dredged from the Gulf of Mexico. The marsh creation and nourishment cells are designed to minimize impacts on existing marsh and mangroves. Assuming some natural vegetative recruitment, vegetative plantings are planned at a 50% density, with half planned at project year one and half planned at project year 3. Containment dikes will be degraded or gapped by year three to allow access for estuarine organisms.

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The project area is defined as the area south of Louisiana Highway 1 between Belle Pass and Caminada Pass, directly behind Caminada Headland beach covering areas in and around Bay Champagne and areas east of Bayou Moreau. The Caminada Headlands Back Barrier Marsh Creation project is located along the Louisiana coastline in LaFourche Parish in CWPPRA Planning Region 2.

A kick-off meeting was held in June 2014. The project team has completed preliminary engineering and design, environmental compliance, real estate negotiations, operation & maintenance and monitoring planning, and a cultural resources investigation, all to the 95% design level as required by the CWPPRA standard operating procedures. The 30% design review meeting was held July 28, 2016 and the 95% design review was held on October 28, 2016. The Phase II Request for construction funding was presented to the CWPPRA Tech Committee on December 7, 2016.

This project is on Priority Project List (PPL) 23.

The Caminada Headlands Back Barrier Marsh Creation project sponsors include:

Keep up with this project and other CWPPRA projects on the project page.

Freshwater and Sediment Diversions

CWPPRA Restoration Technique: Freshwater and Sediment Diversions

The present location of the Mississippi River has been confined by levees constructed in response to the devastating flood of 1927. Although necessary for protecting life and property, the levees prevent the natural processes of delta building and sediment deposition that are vital for sustaining wetlands. Without this nourishment, the wetlands will eventually succumb to subsidence, storms, and anthropogenic impacts.

The CWPPRA program has been finding solutions to optimize river resources and help rebuild wetlands with minimal impact to other stakeholders. Controlled diversions route river water through strategic locations in the levees to feed starving marshes. Crevasses, or cuts, are constructed through levees to allow passive creation of smaller deltas. Siphons suction fresh river water and direct flow into wetlands suffering from saltwater intrusion. Water-control structures and channel maintenance help distribute river water diverted from large-scale structures constructed under other authorities.

The river presents the greatest opportunity for rebuilding land but also the greatest challenges, as competing needs are inevitable. The human and natural environments must be able to coexist because they are inextricably connected. Together with stakeholders, CWPPRA projects are helping to reverse land loss on an ecosystem scale and support the economy on which coastal Louisiana has come to depend.

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MR-03 West Bay Sediment Diversion