Belmond Reserve – CLOMR
Using a model in ICPR4 software, LevelUp obtained permits through the Water Management District (SWFWMD) and Hillsborough County for a project in the Alafia River Watershed. However, FEMA did not approve the MT-2 submittal for a CLMOR after several attempts. By the time LevelUp contacted LAGO, there were still 5 comments from the FEMA reviewers pending to be addressed and LAGO was contracted to do it.
- CLIENT
- LevelupFL
- YEAR
- 2023
- APPLIED SKILLS
- Surface water Modeling
Scenario evaluations - CONSULTING AREAS
- Conditional Letter of Map Revision (CLOMR).
- SOFTWARE
- ArcMap, ICPR, LAGO ToolBox.
Specifics
FEMA comment 1: Ensure all modeled structures are the same as the effective model or based on new as-built survey. LAGO Approach: In the case that they differ, we provided as-built survey for pipes, other man-made structures, and channel cross section surveys. For overland weirs LAGO used the most recent LiDAR for cross section profiles.
FEMA comment 2: Revise the proposed mapping. Submit modeling consistent with the proposed mapping. LAGO Approach: The small depression will receive runoff until overflows to the remaining “Wetland A” area. Thus, the peak level of the small depression shall be higher than the one in the “Wetland A” basin.
FEMA comment 3: The boundary conditions are generally acceptable. However, node 730950 shall be a boundary condition/node ….. LAGO Approach: The five boundary-conditions (time/stage) nodes were pulled from FEMA effective model SWMM4, and they use time-varying hydrographs. Using the BFE as a constant boundary condition seems like doing a steady state simulation in HEC-RAS. No HEC model for the area. The approach to using time-varying hydrographs should be accepted. All boundary condition nodes are downstream from the project area.
FEMA comment 4: submit supporting hydrologic data (Tc, CNs, DA map) for pre-project hydrologic analysis and model. LAGO Approach: After georeferencing the ICPR models, we loaded the DEM raster as well as maps for land use, soil, and subbasins and use them to do the requested calculations (CN values, stage-area table at subbasins/nodes, and cross section elevation profiles for overland flow weirs).
FEMA comment 5: Ensure that the only difference between the pre- and proposed model is within the subject project. For example: External hydrograph at Node 730987, (either apply to post-model, or remove from pre-project to match post-model. LAGO Approach: All model features were checked, and all were displayed properly in the exhibits. The spatial data submitted was consistent with the submitted exhibits and models.
Outcome
Model files, GIS maps and documentation were delivered to support the response.