US Army Corps of Engineers BUILDING STRONG ® Greater New Orleans Hurricane and Storm Damage Risk Reduction System Armoring Brief Team New Orleans U.S. Army Corps of Engineers July 20, 2011

BUILDING STRONG ® HSDRRS Armoring Brief Authority  Congress stated in the 4 th and 6 th supplement: “…armor critical elements of the New Orleans hurricane and storm damage risk reduction system….” 2

BUILDING STRONG ® HSDRRS Armoring Brief Definition of Armoring  A natural of artificial material placed on or around a levee, floodwall or other structure to reduce the risk to the system or component, to prevent breaching or major damage when confronted with wave attack, overflow and overtopping associated with a greater and 100-yr storm surge event. 3

BUILDING STRONG ® HSDRRS Armoring Brief Research and Development  Colorado State: ► Erected world’s largest wave flume ► Tested erosion resistance of an array of common levee construction and armoring materials  Texas A&M: ► Modeling / Analysis of Transition Armoring ► Erosion resistance testing of compacted clay and stabilized soil  LSU ► Grass / Root study  ERDC ► Flood side erosion technical publication  International Subject Matter Experts ► Flume design (Dr. van de Meer) ► Testing methodology (Drs. van de Meer and Hughes) ► Interpret test results / establish performance ranges of armoring materials (Royal Haskoning, Dr. Thornton and Dr. Hughes) 4

HSDRRS Armoring Brief CSU Test Results 5 Material Test No. Material Max. Flow Tested At flow Total Hours Tested Result 1Clay0.2 cfs/ft Failed after 1hr 0.2cfs/ft 2Bermuda Grass4.0 cfs/ft424No Visible Erosion 3Bahia Grass3.0 cfs/ft417No Visible Erosion 4TRM/Bermuda4.0 cfs/ft39.0No Visible Erosion 5HPTRM/Bermuda4.0 cfs/ft39.0No Visible Erosion 6Bermuda Grass w/ruts4.0 cfs/ft36.0No propagation 7Bermuda w/ruts & bare spot4.0 cfs/ft33.0No propagation 8Lime Stabilized Clay4.0 cfs/ft0.30.4Failure at 1.0 cfs/ft 9ACB4.0 cfs/ft33No Visible Erosion 10Dead Bermuda Grass2.5 cfs/ft13.2Failed at 2.0 cfs/ft 11Dead Bermuda Grass w/HPTRM4.0 cfs/ft36.0No Visible Erosion

BUILDING STRONG ® HSDRRS Armoring Brief Performance Ranges Material Range cfs/ft Grass HPTRM ACB>4 6

HSDRRS Armoring Brief Armoring Types Articulated Concrete Block & TRM Installing Articulated Concrete Block Turf Reinforcement Mat Articulated Concrete Block after 4 months of Grass Growth 7

HSDRRS Armoring Brief Using B.C Spillway Clay, Grass Grown at ERDC & Trucked to CSU Grass Growth & Wave Overtopping Testing at CSU 8

BUILDING STRONG ® HSDRRS Armoring Brief 9

BUILDING STRONG ® HSDRRS Armoring Brief Risk Informed Decision Making  Commissioned members of IPET Risk Assessment Team to run probabilistic analyses of flood inundation that might be expected with each of the armoring alternatives in place for 500-yr and 750-yr storm surge events  Used IPET risk assessment model to analyze armoring alternatives based on fragilities to make recommendations 10

BUILDING STRONG ® HSDRRS Armoring Brief Alternative Formulation  Analyzed overtopping rates for storms of varying intensities (500-yr and 750-yr) impacting the perimeter  Developed alternative armoring configurations based on performance ranges of armoring materials as established by completed R&D  Project Delivery Team included membership of non-federal sponsor and flood protection authorities 11

BUILDING STRONG ® HSDRRS Armoring Brief Alternative Evaluation Process  Conducted in phases to allow maximum consideration of NFS perspectives  Multi-criteria decision analysis  Alternatives evaluated against 5 weighted criteria ► Risk and Reliability (Performance) – 45% ► Operation and Maintenance – 30% ► Cost – 10% ► Schedule – 10% ► Environmental – 5% 12

BUILDING STRONG ® HSDRRS Armoring Brief Armoring Alternative Configurations 500-yr Alternatives  Alt 1 – Uniform 500-yr resiliency  Alt 2 – Hardened crown, adjust armoring material in accordance with resultant overtopping rate  Alt 3. – Uniform 500-yr resiliency plus risk informed additions 750-yr Alternatives  Alt 4 – Uniform 750-yr resiliency  Alt 5 – Hardened crown, adjust armoring material in accordance with resultant overtopping rate  Alt 6. – Uniform 750-yr resiliency plus risk informed additions 13

BUILDING STRONG ® HSDRRS Armoring Brief Alternative Evaluation Process (cont.)  Analyzed 6 alternatives (25 May) ► Team recommendation: Alternative 3  Summary of outcome provided to NFS (6 June)  Follow-up meeting conducted (20 June)  Written feedback from NFS provided (24 June) ► Use no TRM or ACB ► Use gravity walls to lower overtopping rate below 1 cfs (within erosion resistance of grass) ► Gravity wall alternative found inconsistent with authorization Exceeds 100-yr system authorization Fails to add resiliency for over topping 14

BUILDING STRONG ® HSDRRS Armoring Brief Armoring Alternative Configurations  Final AEP conducted 28 June – Alternative 7 added to minimize use of TRM / ACB ► Alt 7 – Uniform 500-yr resiliency plus risk informed additions (enhanced grass in lieu of TRM for risk informed additions) 15

BUILDING STRONG ® HSDRRS Armoring Brief Alternatives RankAlternativeDescription yr Overtopping resiliency and Risk Assessment Results (HPTRMS only) yr Overtopping resiliency + hardened crown yr Overtopping resiliency and Risk Assessment Results (HPTRMS only) yr Overtopping resiliency and Risk Assessment Results (HPTRMS only) + NFS O&M considerations yr Overtopping resiliency + hardened crown yr Overtopping resiliency only yr Overtopping resiliency only 16

HSDRRS Armoring Brief 17

HSDRRS Armoring Brief 18

BUILDING STRONG ® HSDRRS Armoring Brief Challenges  Future Levee Lifts  Future Authority for Armoring  NFS O&M Concerns  Expedited Implementation 19

BUILDING STRONG ® HSDRRS Armoring Brief Path Forward  Re-allocation of Funds for Armoring  Complete Design – Dec 2011  Begin Construction – Mar 2012  Armoring In Place – 1 June

BUILDING STRONG ® HSDRRS Armoring Brief Discussion 21

BUILDING STRONG ® HSDRRS Armoring Brief Sponsor / Stakeholder Participation  Project Delivery Team participation since July 2010  Formulation of armoring alternative for evaluation 22