The Florida Department of Transportation (FDOT) - District Five (D5), utilized B&N’s 2016 Districtwide Drainage Design contract to execute the design and preparation of construction plans for the District’s first regional stormwater quality treatment facility, the Lake Harris Regional Stormwater Facility.
Water Quality and the Florida Eco-System
Since 1982, the State of Florida and more specifically, the Florida Department of Environmental Protection (FDEP), has regulated stormwater quality discharged from new developments by delegating authority to the State’s five Water Management Districts (WMD). Since the implementation of regulations governing development, refinements to FDEP’s water quality treatment rules have been ongoing. Most recently, Senate Bill 712, also known as Stormwater 2020, required FDEP to review the Statewide Stormwater Rule to identify its successes and shortcomings and provide recommendations to improve water quality within Florida’s natural ecosystem.
In addition to the regulatory responsibilities of the FDEP, this agency also conducts water quality monitoring and assesses the condition of most Florida watersheds on a four- or five-year cycle. The water quality assessments identified water basins exhibiting high nutrient levels of total nitrogen (TN) and total phosphorus (TP) and designated those basins as impaired.
In response to the impaired designation, the WMD’s have adopted specific rules for new developments discharging to an impaired basin, requiring a net improvement of the stormwater quality discharged as a result of development. In addition, local stakeholders have been tasked with developing best management action plans (BMAPs) to reduce the total maximum daily loads (TMDL) of TN and TP being discharged into jurisdictional Federal and State waters such as natural wetlands, waterways, ponds and lakes.
A Benefit for FDOT and the Environment
This project provides significant reductions of TN, TP, sediment, trash and debris being conveyed by stormwater runoff from a 500-acre contributing drainage basin. In addition to the benefit gained by the region, a portion of the nutrient reduction will be credited back to the FDOT via an Environmental Resource Permit (ERP), enabling them to widen a segment of State Road 19 without having to provide for project-specific water quality treatment.
Some of the key aspects and considerations contributing to the success of this regional stormwater facility are summarized as follows.
- The 10-acre parcel used for the regional facility was owned by FDOT, eliminating right-of-way costs.
- Runoff from the 500-acre watershed drains via three inflow locations into the FDOT property. As a result, no work was required outside the FDOT right-of-way.
- The property consisted of predominantly nuisance/exotic plants, so its functional value was low and wetland mitigation was minimized.
- No protected species were identified within the project area.
- Overall removal efficiencies were 36% for TN and 62% for TP.
- Total load removals were 587 lbs. per year for TN and 111 lbs. per year for TP.
- A key feature of the facility included a 100-foot-long, concrete, broad crested weir.
Honors & Awards
The Lake Harris Regional Stormwater Facility received the 2022 Outstanding Environmental Project Award from the American Council of Engineering Companies of Florida and the Florida Department of Transportation.