Project Background and Purpose:

• Under contract with both Orange and Seminole Counties in Florida, SAI conducted a comprehensive drainage investigation of the Little Econlockhatchee River watershed.

• The purpose of the study was to identify flooding problems, characterize existing water quality and ecological concerns, and present a plan to alleviate stormwater quantity and quality problems.

 

 

Project Design / Implementation:

• The project involved coordination between two counties and local regulatory agencies as well as a number of stakeholders (cities, property owners, developers, etc.).

• Tabulated drainage inventory was used to compare level of protection provided by various design alternatives to existing levels of service.

• Flooding was evaluated and a minimum of 3 alternative designs were developed for problem areas in 13 major drainage sub-systems.

• Extensive home and road flooding was predicted for several areas within the watershed. Severely degraded water quality was identified in several locations of the watershed as well.

• Recommendations included several regional stormwater facilities (one 98-ac. facility) and various other BMP technologies as well as extensive channel and culvert modifications.

• The recommended improvements were evaluated for cost, regulatory considerations, and land acquisition requirements.

• The project also included flood plain mapping, preparation of a public information pamphlet,  and public presentations.

 

Stormwater Modeling / Investigation:

• Comprehensive stormwater modeling of the 92 square mile watershed was conducted using the FEMA approved ICPR model.

• The watershed is highly urbanized with little or no stormwater treatment.

• The project involved the review of hundreds of reports, previous studies, permits, and over 450 construction plan sets.

• The model included over 1,100 drainage sub-basins and nodes. Extensive field reconnaissance was performed to review and inventory the primary drainage infrastructure and document problems.

• The model was calibrated/verified based on data from Tropical Storm Gordon (1994).

• Modeling involved complex bridge structures, amil gates, and dams.

• The model input data, results and flood impacts, cost estimates, and pollutant load calculations were managed or conducted using a graphical information system (GIS).