No-Rise / No-Impact Certification
The client requested to perform No-Rise / No-Impact evaluations for proposed new buildings on several lots that may involve encroachment into FEMA designated floodplains on Billy and Mullock Creeks located in unincorporated areas of Lee County, Florida.
- CLIENT
- Habitat for Humanity
- YEAR
- 2019
- APPLIED SKILLS
- H&H Modeling: Data mining & processing; conceptualization & setup
- CONSULTING AREAS
- Stormwater management
Flooding assessment - SOFTWARE
- HEC-RAS, ArcMap.
Specifics
LAGO refined the corresponding FEMA HEC-RAS models available from the latest Flood Insurance Study (FIS) for Lee County. The refinement included a higher spatial resolution by inserting new cross sections around the parcels to be developed, as well as reducing model tolerances to diminish numerical errors. Then, the refined model cross sections are modified to include the proposed grading and the new buildings.
In all proposed developments, the comparison of the 100-year water surface elevations from the pre- and post-development models showed a difference of 0.00 ft at the cross-sections adjacent to the development sites, which indicated no rise of flood stages caused by the buildings.
Outcome
No-Rise Certificates were issued by one of our Professional Engineers for all the proposed developments. The certificates were accompanied by support files detailing the evaluation performed.