Saving Texas Largest Freshwater Marshes: McFaddin NWR Presented By: - PowerPoint PPT Presentation

Saving Texas’ Largest Freshwater Marshes: McFaddin NWR Presented By: Stephanie L. Gonzales, PE LJA Engineering, Inc.

Overview ! ! Project Area and Background ! ! Marsh Impacts ! ! Protection Berm ! ! Design ! ! Construction ! ! Beach and Dune Nourishment ! ! Sand Source Investigation ! ! Preliminary Design ! ! Dredging Method ! ! Sediment Delivery

Project Area and Background ! ! McFaddin Beach and National Wildlife Refuge

Project Area and Background Need ! ! Salt Bayou Watershed – 100,000 ac. of Fresh and Brackish Marsh ! ! Feeding and resting habitat for waterfowl ! ! Protective buffer between the Gulf of Mexico and the GIWW Purpose • ! Reduce frequency of saltwater inundation into the interior marshes • ! Protect the marshes from high tide and low energy storm events. • ! Reduce Erosion to that of typical sandy beaches

Marsh Impacts: Storm Events September 9, 2008 October 2, 2008 September 15, 2008

Marsh Impacts: Annual Erosion Rates Erosion Rates Entire Shoreline: Aug ‘05 to Feb ‘09 = -21.4 ft/yr Feb ‘09 to Apr ‘10 = -34.0 ft/yr White’s to Perkins: Aug ‘05 to Feb ‘09 = -25.6 ft/yr Feb ‘09 to Apr ’10 = -33.4 ft/yr

Design of Protection Berm ! ! 5 yr. Storm Approximation with +5ft NAVD88 Protection Berm

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Beach and Dune Nourishment Alternatives Analysis ! ! Key Points ! ! Borrow Source Identification ! ! Sediment Configuration ! ! Dredge Type ! ! Sediment Delivery ! ! Screening Factors ! ! Costs ! ! Construction Time ! ! Impacts to the Environment ! ! Navigation

Sand Source Investigation Investigation Area

Sand Source Investigation

Preliminary Design

Trailing Suction Hopper Dredge • ! Low Mobilization & Operating Costs • ! Utilizes Short Pipelines • ! Can “Bottom Dump” Overburden • ! Can work in Adverse Conditions • ! Higher Risk to Endangered Species • ! Lower Production Rates

Sediment Delivery – Hopper Dredge

Cutter Suction Dredge • ! High Mobilization & Operating Costs • ! Operates in Fair Weather • ! High Production • ! Low Risk to Endanger Species • ! Works Well in Various Sediments • ! Continuous Pumping ! ! ! ! ! !

Sediment Delivery - CSD

Beach and Dune Nourishment

Interagency Efforts Protection Berm (Phase I & II): • ! US Fish and Wildlife Services (USFWS) and Jefferson County providing funding for construction (CIAP) • ! Texas General Land Office (GLO) providing management and oversight • ! Jefferson County and GLO Disaster Recovery (DR) providing funding for engineering & environmental management (CIAP) Beach and Dune Nourishment (Phase III): • ! CIAP providing initial funding for construction • ! Texas General Land Office providing management and oversight • ! GLO providing funding for engineering (CEPRA)

Questions / Comments? Contact Information: Stephanie Gonzales slgonzales@ljaengineering.com