GIWW – Perry Ridge West Bank Stabilization (CS-30)

Settlement plates such as the one pictured here will be used to determine if settling of the structure has occurred. Technicians from NRCS’s Crowley Watershed Office are shown taking baseline elevations before more rock is deposited. Future elevation readings will be taken after the structure is completed.

Location

The project is located along the northern bank of the Gulf Intracoastal Waterway (GIWW) between Perry Ridge and the Sabine River in Calcasieu Parish, Louisiana.

Problems

This section of the GIWW was dredged to allow the use of doublewide barges, and,  consequently, has intensified the occurrence of wake erosion. In addition, the construction of the Calcasieu Ship Channel and the deepening of Sabine Pass have increased the salinity and water currents within the GIWW. These activities have caused the GIWW shoreline to breach, thus impacting the interior marsh of the project area.

Restoration Strategy

Proposed project components involve installation of 9,500 feet of rock riprap along the northern bank of the GIWW from Perry Ridge to its intersection with the Sabine River.
An additional 2,200 feet of rock riprap will be installed from the Sabine/GIWW intersection north along the Sabine River. This proposed work is referred to as “construction unit number 2.” Approximately 22,952 linear feet of terraces will
be constructed in the shallow, open water areas north of the GIWW to reduce fetch (distance a wave can travel) and allow recovery of the interior marshes. Terraces will be
vegetated with 9,400 trade-gallon-sized plantings of California bulrush. This proposed work is referred to as “construction unit number 3.”

Progress to Date

Project construction is complete. The monitoring plan is currently in development and should be finalized in the spring of 2002.

The project is on Priority Project List (PPL) 9.

The Federal Sponsor is Natural Resources Conservation Service.

The Local Sponsor is CPRA.

Approved Date: 2000
Project Area: 1,132 acres
Approved Funds: $2.19 M
Total Est. Cost: $2.20 M
Net Benefit After 20 Years: 83 acres
Status: Completed
Project Type: Shoreline Protection

Little Vermilion Bay Sediment Trapping (TV-12)

High winds and waves prevent GIWW sediments transported down the Freshwater and Schooner bayous from settling and forming the basis of vegetated marsh. This same wind and wave energy also increases shoreline erosion rates.

This project involved the construction of a series of vegetated terraces to diminish waves in Little Vermilion Bay, helping to increase sediment deposition and reduce the rate of shoreline erosion. A pattern of channels was dredged 100-feet wide and 6-feet deep to beneficially distribute sediment from the GIWW through the Freshwater and Schooner bayous. Dredged sediments were used to construct 23 earthen terraces with a combined length of 23,300 feet. After settling, the average height of the terraces was 3.5 feet above mean sea level.

The bases of the terraces were planted with 20,450 containers of smooth cordgrass (Spartina alterniflora).

The design allows commercial and recreational fisherman to access the project area, and it stimulates fishery production by creating new habitat and increasing shoreline length.

In 1998 alone (prior to the project’s completion) 40 acres of wetland habitat were created.

This project is located in the northwestern corner of Little Vermilion Bay at its intersection with the Gulf Intracoastal Waterway (GIWW) in Vermilion Parish, Louisiana. The project area encompasses 964 acres.

Monitoring is underway and preliminary observations show that the terraces are growing in width, and bay depth between terraces is decreasing indicating marsh expansion in the project area.

This project is on Priority Project List 5.

The Federal Sponsor is NOAA NMFS

The Local Sponsor is CPRA