cwppra terracing and marsh creation south of big mar project (ba-24)

CWPPRA Terracing and Marsh Creation

South of Big Mar Project(BA-24)

Project Kickoff Meeting

April 17, 2013

Meeting Goals• Review project background• Discuss project features and potential changes

or additional features to investigate• Discuss engineering and design tasks

necessary to reach 30% design milestone• Discuss other Phase 1 tasks – landrights,

permits, NEPA• Develop a schedule for Phase 1 tasks to reach

30% design

Background

• Developed to restore the marsh platform scoured by Hurricane Katrina

• Will work in concert with the Lake Lery Shoreline Protection Project (BS-16) to reinforce the historic Lake Lery Shoreline

• Terraces will reduce wave fetch in the large open water areas and promote conditions conducive to growth of marsh vegetation and submerged aquatic vegetation.

• Will also benefit from freshwater, sediments, and nutrients provided by the Caernarvon Freshwater Diversion Project.

Address other projects in the area

Terracing

• ~ 65,000 linear feet of terraces (50 acres)

Project Features

Marsh Creation

335 acres of marsh created and restored

Marsh Creation

• Approximately 2.5 M cubic yards of material would be dredged from a borrow site proposed in Lake Lery

• Retention levees gapped/degraded to support estuarine fisheries access and to achieve a functional marsh

• Pipeline layout initial design:

Project Features (Cont.)

Project Features (Cont.)

• Terraces LF was not based on the standard >>> 250 ft apart, 70.2 LF per acre

– which would result in 67,883 LF comprising 967 acres of terraces

• GIS effort was conducted that placed the terraces 300-400 feet apart with 65,000 LF of terraces in approximately 1,000 acres.

Top Width ft 15.0 Side Slope 1V:5.0 H Length of Terraces lf d) 65,000 Height of Material Quantity (b - a + c) ft e) 4.4

Volume of Material yd3 394,771

Vegetative Plantings 5 ft spacing 2rows per side 2rows on crest 78,006total plants req'd

Terraces

• Benefits: 307 net acres of intermediate marsh over 20 years.

• Fully funded cost = $23,843,953• Phase 1 cost = $2,258,696• Approved for Phase 1 funding by the CWPPRA

Task Force on January 24, 2013.

Benefits/Costs

Design Considerations

• Configuration of terracing

• Borrow Area/Dredge pipe route

• Dewater locations

• Gapping vs. degrading

• Tidal creeks

• Identify additional /alternative areas that would benefit from terraces or marsh creation

CRMS Locations

Engineering & Design and other Phase 1 Tasks

• Surveys • Wave analysis – same borrow area• Geotechnical Investigation• Gage Installation• Landrights• NEPA• Permit Application• Cultural Resources

Discussion