Okaloosa County BOCC — December 16, 2014 — Bluewater MSBU HMGP Application 12-9-14 Attachment A — reading text

ATTACHMENT A Curacoa Way/Southwind Drive Flood Mitigation Program Bluewater Bay Municipal Services Benefit Unit (MSBU) Okaloosa County, Florida December 2014 PROJECT NARRATIVE On the night of April 29, 2014 and extending into the next morning, northwest Florida experienced a rare storm event resulting in significant flood damage. Some areas received well over one‐foot of rain and many roads and other infrastructure improvements were compromised by the resulting stormwater runoff. A federal emergency declaration was issued for the region: FEMA‐4177‐DR‐FL. Okaloosa County experienced widespread damage, including significant flooding in the Bluewater Bay neighborhood. Bluewater Bay is an unincorporated residential development located in Okaloosa County east of the Niceville city limits. The Bluewater Bay Municipal Services Benefit Unit (MSBU) is a local subdivision of Okaloosa County formed to facilitate maintenance of common areas within the MSBU limits. A portion of an approximately 350‐acre stormwater drainage basin within the Bluewater Bay MSBU limits includes a stormwater pond that rose to unprecedented levels during that storm event and flooded many of the 23 single‐family homes surrounding the pond. The stormwater pond is bordered by Southwind Drive, Dominica Way, Aruba Way and Curacao Way. Upstream from the pond was an existing earth berm adjacent to Hole #7 on the Bluewater Bay Lake Course. The earth berm was breached and failed during the storm and the existing pipes below Curacao Way appeared to be inadequate for discharging the volumes of water in the pond. These factors may have contributed to unprecedented stormwater volume in the pond and the possible compromise of the pavement at the Southwind Drive pipe crossing. Flood waters touched 20 of the 22 homes bordering the pond, with the first floor living areas of two of these homes becoming completely submerged. Following the storm event of April 29/30, many of the homes have continued to be threatened with similar recurring flooding during storms of much less intensity. It is clear the stormwater drainage system no longer provides the same performance as originally designed. Flood waters touched 20 of the 22 homes bordering the pond. The first floor living areas of two of these homes were completely submerged. 1 To repair the stormwater drainage system and to mitigate the possibility for future flooding, Okaloosa County is considering the following four‐phase approach: 1. Topographic Survey and Hydraulic Study: A topographic survey of the drainage basin is necessary to confirm the basin boundaries, pipe invert elevations, inlet top elevations, and other drainage features. The drainage basin contributing to the pond is estimated to measure approximately 350 acres. The hydraulic study will include a complete inventory of the drainage basin, identification of stormwater runoff characteristics from high‐intensity storm events, and modeling of the drainage basin using AdICPR software. The study will result in a comprehensive assessment of the drainage basin, including the identification of deficiencies associated with the assumed storm events. The model will also consider any tailwater impacts on the system resulting from the water levels at the basin outfall, just south of Curacao Way. The study will culminate in recommended improvements to the drainage system to mitigate future flooding. 2. Design and Permitting Services: Based on the recommendations of the hydraulic study, design phase services will include the development of professionally certified bidding/construction documents to implement infrastructure repairs with hazard mitigation improvements as needed. These services will also include coordination and applicable permitting with the Northwest Florida Water Management District (NWFWMD) and the Florida Department of Environmental Protection (FDEP). In addition, the permitting services are anticipated to include the services of a certified biologist to consider the removal of existing beaver dams downstream from the outfall location if needed. It is commonly assumed that the tailwater conditions could be improved with the elimination of the dams constructed in upper reaches of Grass Lake. 3. Bidding and Construction Phase Services: The bidding phase services will include professional assistance to the County in procuring qualified suppliers through applicable County and federal procurement processes to provide the construction materials. Construction phase services will include independent administration of the construction work to monitor compliance with the construction documents and to professionally certify the work completed. Limited inspection services are proposed to monitor the installation of pipes and other underground improvements prior to backfilling. 4. Construction: The construction activities are expected to include a series of pipe replacement improvements in four separate locations. The work will include removal of existing pipe and drainage structures as necessary, followed by the installation of new reinforced concrete pipes and inlets consistent with the recommendations of the hydraulic study. The work will include three road crossings (i.e. Southwind Drive, Curacao Way, and Woodlands Drive) where the asphalt section will be cut and replaced to facilitate the new pipe installation. Okaloosa County staff will provide in‐kind assistance in performing the labor required by the construction documents. The value of their in‐kind assistance will contribute to the local share for this project. 2