Information about the McClellan-Kerr
Arkansas River Navigation System
Prepared by: Bill Ruck, PE, PS, CFM Garver, North Little Rock, AR
The FEMA Map Modernization Program is alive and well, but there are changes being made which may not be known to many waterway users until 2012. Hurricane Katrina resulted in significant administrative changes in the National Flood Insurance Program.
The most visible change is that all levees on Flood Insurance Rate Maps must now be certified by professional engineers in accordance with 44 CFR 65.10. Calculations for the next FIRM update are done as if the uncertified levees do not exist. Thus, the resulting FIRM has a greatly expanded flood plain, and those landowners with federally backed mortgages are required to obtain flood insurance. Arkansas is one of the first states on the list to receive new FIRMs.
A number of levee owners along the Arkansas River in Arkansas have attempted to become certified. This attempt to prove that an existing levee will withstand the 100-year flood includes topographic surveying, borings and geotechnical analysis, and a complete design check of all the physical facilities - including pump stations, flood walls, crossing culverts, gates, and other closure devices. Operations-and- maintenance manuals must be created or updated to insure that manpower and materials are available and sufficient for flood events.
All levee deficiencies must be corrected by the levee owner prior to acceptance by FEMA. Replacement of old culverts is complicated by their depth below the present day pool of the River and generations of infrastructure over them. Pipe lining systems or conventional trenching must be evaluated for cost effectiveness. Several levee districts in the Little Rock area face major pipe culvert replacements costing $100,000 to $200,000 each. Many levee districts are in the repair stage of the process at the time of this writing, while only a few are fully certified or have corrected all known defects.
The above process has only two obvious results: the levee is either certified or, if not, it is removed from the FEMA map, thus affecting the purchase of flood insurance and land use. FEMA is developing a rating program which gives credit for the apparent benefits of the levee without completing all of the milestones. No details have been released at the time of this writing, but we expect to see announcements late in 2011 on this new policy.
In addition, FEMA has produced its RiskMAP program which enhances the NFIP map-making process using public input on physical flood hazards and programmatic challenges. FEMA published and is distributing the attached process diagram in order to assure complete public understanding.