NAI Principles In Gwinnett County By Cornelius Ani, LSIT, CFM Contributors: Adena Fullard, P.E., CPSWQ Rudresh Bihalli, P.E., CFM Ken Kagy, P.E., CPESC, CPSWQ Ligia Negru, M. Sc., CFM Maja Radovic, CPESC, CFM
No Adverse Impact (NAI) NAI provides tools for communities to provide a higher level of protection for their citizens and to prevent increased flooding now and in the future. 1 1
No Adverse Impact (NAI) Floodplain management is an approach that ensures the action of any community or property owner, public or private, does not adversely impact the property and rights of others 1 2
2011 Major Disaster Declaration How many major Federal Disaster Declarations has occurred since the beginning of 2011? 8 How many of these Declarations involved flooding? 5
NAI Principles In Gwinnett County Hazard Mitigation and Flood Mapping Education and Public Outreach Planning Regulations and Development Standards Master Planning and Monitoring Mitigation Actions (Corrective Actions) Infrastructure
Hazard Mitigation and Flood Mapping Continuous update 230-390 stream miles in less than a decade Add l 400 miles between 2006 & 2009 LOMA and LOMR attachment to Parcel
Hazard Mitigation and Flood Mapping Flood Insurance Rate Maps (FIRM) Drainage easements Flowage easement 150 feet on NRCS dams Existing/natural swales 20 feet to natural swales 6
Hazard Mitigation and Flood Mapping SWM review all Building Permit for properties within the SFHA Big Haynes Creek 7 mile radius 100 feet buffer 150 impervious setback
Hazard Mitigation and Flood Mapping No detention required when stormwater discharge directly into the floodplain Sheet flow over 100 feet Delayed effect on peak discharge Flood study 10-year future conditions Cut and Fill Compensation
Education and Public Outreach Training: local, FEMA etc Mandated yearly training hours Publications in professional journals 9
Education and Public Outreach One on One Through SWM Customer service plan review On the phone
Education and Public Outreach Gwinnett County Flood Information Portal http://www.gwinnettfloodplain.com Depicts the existing flood hazard zones over Google Maps. View flood hazard information at the structure level Provides user access to hydraulic and hydrologic models used for the flood hazard information
Education and Public Outreach Dedicated Resource for Request for Floodplain Information Fax In person/email Phone
Education and Public Outreach Dedicated Resource for Public outreach Approximately 7 workshops per year depending on demand Target audience County residents Developers Engineers & Surveyors General public
Rain Garden Education and Public Outreach Capture runoff from impervious areas Slow seepage into the ground Reduce flows into the floodplain
Planning Multi Objective Management (MOM) Parks and Recreation Planning & Development Gwinnett County Emergency Management Department of Water Resources 15
Planning Parks & Recreation Four Year Finalist 2004-2008 Voted the best park in 2008 by National Recreation & Park Association Nearly 50 sites About 9000 acres 2.7 miles of greenways (interconnected?) About 3.2 % dedicated permeable surface and conservation
Regulations and Development Standards More stringent Regulation 3 feet above BFE 50 feet undisturbed buffer 25 feet impervious setback Big Haynes Creek 7 mile radius 100 feet buffer 150 impervious setback 17
Regulations and Development Standards Zoning Resolution includes a Conservation Subdivision Ordinance) 3.0 density units per acre- 50% open space 2.3 density units per acre- 40% open space Open Space Conservation for Gwinnett County Greenways Compensatory storage Engineered foundations No rise Certification No Rise: (GC-0.01 feet Vs NFIP standard) Stormwater credit for water quality, channel protection and detention 18
Regulations and Development Standards NRCS Dams - Rehabilitation of Flood Control Structures Continue operation and maintenance Upgrade to meet modern dam safety design criteria Rehabilitate to balance flood control, safety and aesthetics Emergency spillway rehabilitation (2009 Flooding)
Master Planning and Monitoring New master plan by Dewberry Davis State led contract currently underway Restudy the Upper Chattahoochee River Basin Provide water surface elevation grids for numerous rainfall events countywide Probability of flooding of structures within a 30 yr period 20
Mitigation Actions (Corrective Actions) Master Flood Protection Planning Continuity Of Operation Plan (COOP) 21
Infrastructure Sizing of new bridges and culverts Sizing of existing bridges and culverts replacement Identified over 250 road crossings Developed conceptual Capital Improvement Project designs Master ranking of structures to prioritize construction schedule Land Acquisition 22
Stream Restoration Stream bed Stream bank Infrastructure During construction After Before After
Emergency Services Pre Disaster Policy development Access vulnerability Reduce vulnerability 24
Emergency Services Post disaster Mitigation Procedures Residential Substantial Damage Estimator Mitigation Funding Increased Cost of Compliance Sustainability
NAI Principles In Gwinnett County Questions?
CRS-NAI Linkage Source of Help Hazard Identification Filling the data gaps Building Block/Tool 1 Toolkit CRS State State Page Section NFIP EMA FEMA # # Detailed data in approximate A Zones 16 411.a x x Detailed data in X Zones 16 411.a x Better base map 16 411.a x Cooperating Technical Partner 17 411.f x x Mapping other flood-related hazards 17 411.f x x Higher mapping criteria Future conditions hydrology 20 411.b x More restrictive floodway standard 20 411.c x
CRS-NAI Linkage Source of Help Toolkit CRS State State Building Block/Tool 1 Page Section NFIP EMA FEMA # # # # Prevent Loss or storage/increase in velocity 21 x CTP cost-sharing on studies 22 410.f x x Education and Outreach Outreach Projects Provide FIRM Information 25 321 x
Youtube http://www.youtube.com/watch?v=qrs6a MVGP1Q http://www.youtube.com/watch?v=afqrp w_6am0&feature=related