Quail West Surface Water Management System Improvements

The Quail West Foundation hired the JR Evans Engineering team to prepare a calibrated hydrology and hydraulic model for the Quail West community’s surface water management system, with the objective of proposing and designing multiple drainage improvement projects. During the significant rain events of late August 2017 and Hurricane Irma, the Quail West community experienced extended periods of elevated roadway flooding, even impacting several residential structures. The initial steps of the project included comprehensive data collection, obtaining additional survey information, verifying permitted conditions and verifying the conditions of the drainage infrastructure (e.g. debris/sediment blockages within lake interconnects). Once all the data was collected and complied, an existing conditions ICPR4 hydrology and hydraulic model was created and calibrated.

The model included sub-basins with land cover-soil complex data, lake interconnects with material and debris/sediment blockage data, and storage nodes with LiDAR based stage-area data. The ICPR4 model utilized georeferenced map layers for quicker data processing of the required hydrologic parameters. Map layers for the project area’s hydrologic soil groups, land cover/land uses, NEXRAD rainfall cells and basin boundaries were prepared in ArcGIS.

The model was calibrated using the NEXRAD rainfall data specific to the project area from August 20th, 2017 to September 20th, 2017, during which time the storm events INVEST 92L and Hurricane Irma occurred. Drone video and aerial photography taken between September 12th and September 14th, 2017 were used to estimate peak stages in each of the twenty-three (23) sub-basins. Adjustments were made to several parameters during the calibration process until peak model stages were consistent with the observed peak stages.

Once the ICPR4 Model was calibrated, the JR Evans Engineering team analyzed the results of each sub-basin and lake interconnect within the system to evaluate potential problem areas in the community. Problem areas were identified by reviewing the calibrated model results and noting where large differences in peak stages of adjacent sub-basins occurred and where incoming flows were much greater than outgoing flows in a sub-basin. Problem areas were also identified during the data collection phase when documenting the observed peak stages throughout the development’s sub-basins.

The JR Evans Engineering team determined fourteen (14) improvement projects that would prove beneficial to the community when implemented. The improvement projects were determined using an iterative process and with cost in mind, resulting in the greatest benefit to the community without unjustified costs. Implementation methods and potential impacts of the improvement projects were also considered to limit the disruption to the golf course, traffic/residential roadways and existing homes. The project included preparing map exhibits of the proposed improvements, cost estimates and permitting requirements for the implementation of the improvement projects.