Dustpan Maintenance Dredging Operations for Marsh Creation in the Mississippi River Delta Demonstration (MR-10)

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Hopper dredges must dispose of their material in deep
water, making the spoil material unavailable for direct
marsh creation, although the material may still provide
nourishment for the system. In comparison to hopper
dredges, spoil from dustpan and cutterhead dredges can be
disposed of in shallow, open waters for marsh creation.

The project demonstrated the safe operation of a dustpan
hydraulic dredge in the critical Head of Passes reach of the
Mississippi River. This demonstration enables the use of
this type of dredge for the maintenance of this reach and
additional opportunity for the beneficial use of the dredge
material. Over the course of this demonstration project,
approximately 40 acres of deteriorated marsh that had
converted to shallow open water was restored with
approximately 222,000 cubic yards of dredge material
over the course of 8 days or 192 operating hours with the
expectation of an increase in marsh.

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The project is located in Plaquemines Parish, Louisiana, in
the Mississippi River Modern Delta. Dredging took place
near Cubit’s Gap, Head of Passes, and Southwest Pass.

The demonstration was completed in June 2002.
This project is on Priority Project List 6.

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Lake Hermitage Marsh Creation (BA-42)

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The project is within the West Pointe a la Hache Mapping Unit which lost 38 percent of its marsh from 1932 to 1990. By the year 2050, 28 percent of the 1990 marsh acreage is expected to be lost. That loss is expected to occur even with operation of the West Pointe a la Hache Siphon (State project BA-04). Significant marsh loss has occurred south and east of Lake Hermitage and along the eastern lake shoreline. Deterioration of the lake rim has exposed interior marshes to the wave energy of Lake Hermitage and increased tidal exchange. Based on USGS land-water data from 1985 and 2006, the project area has an annual loss rate of -1.64%.

The original project features included dredging in the Mississippi River and pumping sediments via pipeline to create 549 acres of marsh. Additionally, 6,300 feet of shoreline restoration using river material and 7,300 linear feet of terraces were included. Fortunately, a favorable bid on the construction contract allowed for project expansion and the marsh creation feature was increased to encompass a total of 795 acres.

Funding from the Louisiana Oil Spill Coordinator’s Office, the Louisiana Department of Natural Resources – Office of Coastal Management, and Deepwater Horizon Early Restoration allowed construction of an additional 215 acres of marsh. Terraces were removed from the CWPPRA project to provide an area for marsh creation with Deepwater Horizon Early Restoration funding.

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The project area is located in the Barataria Basin, south and east of Lake Hermitage in Plaquemines Parish, Louisiana near the community of West Pointe a la Hache.

The Louisiana Coastal Wetlands Conservation and Restoration Task Force approved funding for engineering and design in February 2006 and approved construction funding in January 2009. Construction began in February 2012 and was completed in June 2015.

This project is on Priority Project List 15.

The Federal Sponsor is USFWS

The Local Sponsor CPRA

Goose Point/Point Platte Marsh Creation (PO-33)

Interior ponding and, to a lesser extent, shoreline erosion are the major causes of wetland loss in the project area. Loss rates were highest during the period from 1956 to
1978. Those high loss rates were associated with hydrologic alterations which allowed salt water to penetrate the fresher marshes. During the transition to a more brackish plant community, large ponds were formed. A narrow strip of land separates those ponds from Lake Pontchartrain. Although the shoreline erosion rates are relatively low, the shoreline is already breached in several areas, and marsh loss in the interior ponds is expected to increase if the shoreline fails.

The goal of this project is to re-create marsh habitat in the open water behind the shoreline. This new marsh will maintain the lake-rim function along this section of the north shore of Lake Pontchartrain by preventing the formation of breaches into interior ponds. Sediment will be dredged from Lake Pontchartrain and contained in cells within the interior ponds to create approximately 417 acres of marsh. In addition, 149 acres of degraded marsh will be nourished with dredged material. Marsh will be created to widen the shoreline so that the ponds will not be breached during the course of normal shoreline retreat.

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The project is located on the north shore of Lake Pontchartrain between Fontainebleau State Park and Louisiana Highway 11 and within the Big Branch Marsh National Wildlife Refuge in St. Tammany Parish, Louisiana. The project area at Goose Point also includes a portion of the St. Tammany State Wildlife Refuge.

On February 12, 2009, a final inspection of the project site was conducted. All construction activities are complete. This project is on Priority Project List 13.

 

The Federal Sponsor is USFWS

The Local Sponsor is CPRA

Little Lake Shoreline Protection/Dedicated Dredging Near Round Lake (BA-37)

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The Little Lake mapping unit has high wetland loss caused by shoreline erosion, subsidence, and channel construction. The project is located in an area protecting approximately 3,000 acres of fragile interior marshes between the Little Lake shoreline and Bayou L’Ours Ridge. Project area wetlands are subject to high shoreline erosion rates (20 to 40 feet per year) and subsidence deteriorating interior marshes. Without construction, the project area marsh was expected to convert to mainly open water over the next 20 years.

The project’s goals were to:
1) prevent erosion along roughly 4 miles of Little Lake shoreline;
2) create 488 acres of intertidal wetlands along the Little Lake shoreline;
3) nourish and maintain 532 acres of intermediate marsh; and
4) reduce land loss rates by 50 percent over the 20-year life of the project.

The project consists of two major features, a shoreline protection structure and a marsh creation and nourishment area. The 25,976 ft foreshore rock dike was constructed by placing rocks on top of a geotextile foundation. The dike was constructed using three lifts and include gaps every 1,000 to 1,500 ft for fisheries access.

The marsh creation and nourishment phase of this project consisted of containment dikes, marsh creation in open water areas, and marsh nourishment over existing marsh. Approximately, 920 acres of marsh were created and nourished through placement of 3,165,121 cubic yards of sediment from Little Lake. The marsh creation area was planted with 17,000 Spartina alterniflora (smooth cordgrass) plugs.map.jpg

The project is located in the central Barataria Basin in Lafourche Parish, Louisiana. The project area is bounded by the East and West Forks of Bayou L’Ours and the southern shoreline of Little Lake from Plum Point westward to Breton Canal.

This project was selected for Phase I (engineering and design) funding at the January 2002 Task Force meeting and for Phase II (construction) funding in November 2003. Construction was completed in 2007.

The project is listed on Priority Project List 11.

Raccoon Island Shoreline Protection/ Marsh Creation (TE-48)

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The Isles Dernieres barrier island chain is experiencing some of the highest erosion rates of any coastal region in the world. Raccoon Island is experiencing shoreline retreat both gulfward and bayward, threatening one of the most productive wading bird nesting areas and shorebird habitats along the gulf coast.

An existing demonstration project on the eastern end of the island, Raccoon Island Breakwaters Demonstration project (TE-29), has proven that segmented breakwaters can significantly reduce, and perhaps even reverse, shoreline erosion rates. The primary goal of this project is to protect the Raccoon Island rookery and seabird colonies from the encroaching shoreline by: 1) reducing the rate of shoreline erosion along the western, gulfward side and 2) extending the longevity of northern backbay areas by creating 60 acres of intertidal wetlands that will serve as bird habitat. This project has been separated into two construction phases, Phase A and Phase B. Phase A includes the construction of eight additional segmented breakwaters gulfward of the island and immediately west of the existing breakwaters demonstration project and an eastern groin that will connect existing Breakwater No. 0 to the island. Phase B involves the construction of a retention dike along the northern shore to create a back bay enclosure that will be filled with sediments dredged from the bay and/or gulf, followed by vegetative plantings.

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The project is located in the Terrebonne Basin on the western-most island of the Isles Dernieres barrier island chain in Terrebonne Parish, Louisiana.

This project was selected for engineering and design funding at the January 2002 Breaux Act Task Force meeting. Construction funding for Phase A was approved in October 2004. Request for Phase B construction funding is anticipated to occur in January 2008.

This project is on Priority Project List 11.

The Sponsors include:

Federal Sponsor: NRCS

Local Sponsor: CPRA

Bayou Cane Marsh Creation (PO-181)

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Problems:
In 2005, the marshes in the North Shore Mapping Unit sustained severe damage due to Hurricane Katrina. Hundreds of acres of emergent marsh within this mapping unit were lost, resulting in hundreds of acres of shallow open water and scour ponds averaging about 2 ft deep. USGS calculated a 1984 to 2016 area loss rate of -0.91 % per year. Currently there is one area along the shoreline that looks as if a breach is forming. This area also has a small pond immediately behind the critical shoreline. If there were a breach in this area it would allow direct connection between the fresher interior marshes and higher salinity waters of Lake Pontchartrain.
Restoration Strategy:
The overall goal of this project is to restore marshes that were lost and/or damaged due to the effects of Hurricane Katrina. Restoring the marshes should reduce salinity effects on interior emergent marshes.
The proposed features of this project consist of filling approximately 384 acres of shallow open water and nourishing an additional 65 acres of fragmented and/or low marsh with material hydraulically dredged from Lake Pontchartrain. Target settled marsh elevation would be +1.2 NAVD 88, but will ultimately correspond to surrounding healthy marsh.
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Progress to Date:
This project was approved for Phase I Engineering and Design on February 9th, 2018.
This project is on Priority Project List (PPL) 27.
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Goose Point/Point Platte Marsh Creation (PO-33)

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Interior ponding and, to a lesser extent, shoreline erosion are the major causes of wetland loss in the project area. Loss rates were highest during the period from 1956 to 1978. Those high loss rates were associated with hydrologic alterations which allowed salt water to penetrate the fresher marshes. During the transition to a more brackish plant community, large ponds were formed. A narrow strip of land separates those ponds from Lake Pontchartrain. Although the shoreline erosion rates are relatively low, the shoreline is already breached in several areas, and marsh loss in the interior ponds is expected to increase if the shoreline fails.

The goal of this project is to re-create marsh habitat in the open water behind the shoreline. This new marsh will maintain the lake-rim function along this section of the north shore of Lake Pontchartrain by preventing the formation of breaches into interior ponds.

Sediment will be dredged from Lake Pontchartrain and contained in cells within the interior ponds to create approximately 417 acres of marsh. In addition, 149 acres of degraded marsh will be nourished with dredged material. Marsh will be created to widen the shoreline so that the ponds will not be breached during the course of normal shoreline retreat.

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The project is located on the north shore of Lake Pontchartrain between Fountainebleu State Park and Louisiana Highway 11 and within the Big Branch Marsh National Wildlife Refuge in St. Tammany Parish, Louisiana. The project area at Goose Point also includes a portion of the St. Tammany State Wildlife Refuge.

On February 12, 2009, a final inspection of the project site was conducted. All construction activities are complete.

This project is on Priority Project List 13.

 

Federal Sponsor: USFWS

Local Sponsor: CPRA