Floodplain Management Strategies in Forsyth County Georgia Association of Floodplain Management 7 th Annual Technical Conference March 2012 Renee Hoge, P.E., CFM Forsyth County Department of Engineering Patrick Gervais, P.E., CFM CH2M HILL
Presentation Agenda Forsyth County s mapping update program. Public Relations, communications management and helping local citizens with floodplain issues. Using floodplain data for infrastructure planning and management What s next for Forsyth County floodplain management.
The Mapping Update Program Two main watersheds: Lake Lanier/Chattahoochee River Etowah River Forsyth has been working to meet the district mapping requirements since 2007. The County adopted a multi-year progressive mapping program. Forsyth County currently has preliminary maps that will go effective late 2012
The Mapping Program Timeline 2007 Big Creek LDS 2008 Big Creek Detailed phase 1 2009 Big Creek Detailed phase 2 MapMod FIRMs Sept 2007 The Great Recession 2012 Etowah Detailed Phase 2 2011 Etowah Detailed Phase 1 Lake Lanier / Chattahoochee Tribs 2010 Etowah LDS Future Lake Lanier / Chattahoochee Tribs Future Conditions LDS: Limited Detail Study
LOMA Support Typical Request can be summarized as: Is my house really in the floodplain? My mortgage company says I have to buy flood insurance? Looking for: General information and explanation. Location of house relative to floodplain. Map exhibit. Floodplain elevation for Zone A areas.
Types of request: Was in the floodplain before and want to see the difference Effective floodplain in the Big Creek Basin Zone A areas now have elevations (LDS) Preliminary floodplain Newly added
LOMA Support CH2M HILL provided Forsyth County with a summary of elevations table for the models developed for Zone A areas. These elevations are considered Best Available Data for Zone A areas. Should not be used for areas with BFEs because the models are not yet effective.
Forsyth Map Exhibit
Forsyth Study Elevation Data
FEMA FIRMette
Homeowner Feedback Hi Renee, Thank you so much for providing this documentation so quickly. It was exactly what I was trying to find. I really do appreciate your help in this matter. On a personal note...i continue to be impressed by the employees in the Forsyth County offices. I am glad we chose to live here when we moved to the area in 2009. Everyone I have contacted has been so helpful...and your website is great in keeping us informed of what is happening in the county. Keep up the great work! Renee: I just received a letter from FEMA removing our property from the special flood zone and they will be doing additional studies. I want to thank you and your department for all your help. You really went above and beyond our expectations and we really appreciate it. I look forward to our flood insurance premium going down :) Thanks again. Thanks again,
Public Relations Forsyth County has sought to proactively reach out to local citizens: Providing best available data for LOMA applications. Notifying citizens of impending changes to flood maps and public meetings. Graphical templates showing locations of floodplains. Explaining the requirements of the National Flood Insurance Program.
RiskMAP Pilot Program County approached by FEMA/EPD to participate in an early notification program. RiskMAP identified categories of change in status and evacuation predications. Identified biggest response as new additions to floodplains 2,800 notifications issued for public notice. Public meeting was held on May 24, 2011 and was well attended.
Infrastructure Planning The new floodplain models have been used to size replacement culverts at two locations Fowler Road Drew Road HEC-RAS model helps to perform no-rise analysis because it includes backwater conditions. HY-8 can t do this. Ideal opportunity to use existing modeling data
Fowler Road Culvert Replacement Existing Culvert 36-in CMP. 1,150 acres of upstream drainage area. Proposed Culvert: four 10 x5 culverts. Culvert needed to be replaced because: Frequent road overtopping. Bad condition. Close to fire station Emergency Access.
Fowler Road Culvert Replacement Existing Bridge Cross-Section Proposed Bridge Cross-Section Profile Comparison Plot
Fowler Road Culvert Replacement Before Replacement (Image Date: April 8, 2010) After Replacement (Image Date: October 16, 2011) Image Source: Google Earth
The Future for Forsyth County Floodplain Management Future conditions mapping for Chattahoochee Tributaries. Improving CRS rating.
Lessons Learned County has experienced budgetary setbacks after 2008 and has had to find ways to use its resources more effectively. Good mapping data has made administration much easier. Program has provided some up-front experience that helped deal with large number of requests from homeowners.
Questions? Patrick Gervais, P.E., CFM Senior Project Engineer Northpark 400-1000 Abernathy Road NE, Suite 1600 Atlanta, GA 30328 Phone - (678) 530-4130 pgervais@ch2m.com Solutions without Boundaries