Subject:
Title
Resolution to adopt the North Merritt Island Hydrologic and Hydraulic Study and Stormwater Model.
End
Fiscal Impact:
None
Dept/Office:
Natural Resources Management Department
Requested Action:
Recommendation
Adopt the Resolution accepting the North Merritt Island (NMI) Hydrologic and Hydraulic Study (HHS) and Model (Model) for use in the NMI Area in accordance with Chapter 62, Article X, Division 5, entitled Floodplain Protection.
End
Summary Explanation and Background:
Brevard County has documented increasing flooding impacts in the NMI area from tropical storms, hurricanes, and other storm events. This has resulted in damage to homes, negative effects on septic systems, and sections of major roads flooding, sometimes until impassable and blocking property access.
Recommendation 7 of the draft NMI Small Area Study proposes that Brevard County significantly improve the current Federal Emergency Management Agency (FEMA) stormwater model for NMI. It was further recommended that the Model be used to demonstrate whether proposed development would result in any adverse flooding impacts to properties or infrastructure.
Discussions of NMI-specific flood modelling study occurred at the August 2 and 15, 2018, Board meetings. On August 21, 2018, the Board approved the proposed upgrade of the NMI Model. This study was completed by Singhofen & Associates, Inc., under Task Order No. 20-4663-001-HHM.
The study spans 38 square miles, from the Barge Canal north to Nasa Parkway. An integrated surface water-groundwater model was created for this specific watershed. The Model will be used for analysis of current and future flooding conditions, and will be helpful as a base model when evaluating potential flood control and natural system improvement projects.
Section 62-3724(4) establishes stormwater criteria on NMI for the area from Hall Road, north to State Road 405, excluding federally owned lands (Area). Section 62-3724(4)(b) requires engineers of record to certify that proposed development will not increase flood stages, and will not increase the duration of the peak flood stages within the Area. Certification must be accompanied by a report supporting the certification. This report must include full engineering data and analysis, in compliance with good engineering practices, and any and all applicable standards, criteria, and regulatory requirements, including the hydraulic and hydrologic modelling and analysis demonstrating that there is no impact. The HHS and Model, if approved, will serve as that required hydraulic and hydrologic modeling and analysis.
Section 62-3724(4)(d) allows a waiver from compensatory storage where the engineer of record certifies that the proposed design does not increase peak flood stage or duration, based on a stormwater model accepted by the Board of County Commissioners. Any such stormwater model must be based on best available data addressing, at minimum: water storage, water volume, groundwater elevations, peak stages, and peak rates for the Area. The HHS and Model, if approved, will serve as that required model.
This model will be updated as future development occurs thus it will remain current, retaining relevance as best available data as well as modeling for use by development interests as those development opportunities are considered. This model will allow for County staff and development interests to build upon the model as well as consider potential improvements to the drainage system without requiring a costly foundational recreation of the model in order to demonstrate the effects of a proposed development or other improvement.
Clerk to the Board Instructions:
None