Featured in IQ: 2011 Volume 3 Issue 3
In this post-Hurricane Katrina era, the Federal Emergency Management Agency (FEMA) has adopted a more conservative approach to renewing the nation's Flood Insurance Rate Maps. Levee certifications must meet the requirements detailed in the federal statute Mapping of Areas Protected by Levee Systems (44 CFR Section 65.10) or be "erased" from the updated maps.
If the levee is not included in the calculations, landowners can be dramatically affected. When a levee is not certified, new flood limits are determined as if the levee does not exist. Property owners with federally backed or insured mortgages within the revised flood areas are then required by law to purchase flood insurance from FEMA.
This policy's effect has been widespread in Arkansas due to an abundance of levee-protected land along the Arkansas, White and Black rivers. This year, landowners and their levees have been challenged and tested by both record floods and levee certification requirements.
Garver has been working with communities to certify and provide FEMA with evidence that levees meet current design, construction, maintenance and operation standards to adequately protect against a one-percent-annual-chance flood. Garver has inspected both earthen levees and concrete floodwalls. The resulting Engineer's Report provides volumes of analysis, archival information and operational guidance.
Newport, Ark. faced flooding in May when the White River rose to record levels. Garver had recently prepared the city's levee certification for 8 miles of earthen levee and a half mile of concrete floodwall. Because Garver modified the Operations Plan during the certification process to include state highway box culvert closures and pumping, potential underseepage and sand boils were prevented. The levee held and protected residential areas from destructive flooding.
Newport Levee Board Chairman Kaneaster Hodges, Jr. said Garver provided creative and insightful assistance during the certification process. "Garver brought the needed technical engineering expertise to the table, and their team has a work ethic and mentality to make things happen in difficult situations," Hodges said.
Garver has completed engineering reports on 26 miles of levee, 1.8 miles of concrete flood wall and 9 pump stations on the Arkansas and White rivers, and work will soon begin for a levee district on the Black River.
"We understand the levee mapping process and how to comply with National Flood Insurance Program requirements," said Garver Levee Certification Project Leader Bill Ruck, PE, PS, CFM. "The completed levee certification report offers a great benefit because it provides a long-term evaluation of a levee, its history and present condition, and a survey that shows how the levee relates to the flood level. We enjoy helping people work through the certification challenges."
Legal compliance requires a coordinated team to perform the following certification tasks.
Field surveys determine the flood height against the levee and freeboard, which is the levee's height above the 100-year flood.
Levee and wall inspections examine all openings through or under the levee. Pipe culverts less than 18 inches in diameter require video inspections.
Geotechnical investigations reveal settlement potential, levee permeability and stability problems, surface erosion potential and underseepage.
Floodwall inspections evaluate conditions above and below ground.
Interior drainage system analyses test the levee's gravity flow and pump stations to prevent internal flooding.
Surface erosion analyses predict erosion hazards using soil types and water velocities.
Tree removal sites are excavated or inspected to discover conditions that often lead to levee failure.
Operation and Maintenance Manuals provide a reference for routine and emergency actions.
Engineer's Reports document the certification effort from history to current conditions.
Remedial action lists identify defects that the owner needs to correct prior to FEMA submittal.