INNOVATIVE STORMWATER MANAGEMENT
At
City Of Tavares, Florida
Brad Hayes1 and Reed Meriwether, PE2
1
Brad Hayes, City of Tavares Utility Director, 1000 Captain Hayes Road Tavares, FL 32778
2
ARCADIS, 14025 Riveredge Dr., Suite 600, Tampa, FL 33637
Introduction
The City of Tavares (Tavares), located in Lake County, has taken a proactive, collaborative
approach to improving the water quality of Lake Dora as part of its Downtown Community
Redevelopment Program . The Tavares is surrounded by Lake Harris, Lake Dora and Lake Eustis
and has a population of approximately 13,000. Since 2008, Tavares has actively pursued
improvements to its infrastructure in order to improve the quality of life for its citizens. Because
Lake Dora is the centerpiece of the community, Tavares established a vision and created a plan
built around it:
“TAVARES – the capital waterfront city of Lake County; building on a historic
foundation; creating an authentic, accessible community of neighborhoods,
businesses, and citizen services; distinguishing itself as the defining vision of
where you want to be.”
The Lake Front Improvement Plan
Tavares has invested heavily in the 6-acre Wooten Park, which includes:
• Seaplane Basin and Marina
• 36 boat slips/ 4 seaplane moorings marina and aviation fuel station
• Tavares to Mt. Dora Water Taxi service
• Tav-Lee Trailhead (10 mile shared-use trail from Tavares to Leesburg)
• Children’s spray Park
• Performance areas, sandy beach, lighted pier
• Canoe/kayak rentals
Tavares has also invested in the Pavilion on the Lake:
• 8,000 square foot facility positioned over Lake Dora
• Two (2) ballrooms
• Meeting rooms with capacity for 500 persons
In collaboration with the community, Tavares created a master plan for economic development
in the Downtown Community Redevelopment Area (CRA). The plan is designed to improve
the infrastructure of air, water and rail transportation assets to support new retail space, arts and
entertainment venues, and community events that attract residents, visitors and businesses alike.
The plan is designed to entice businesses, residents, and visitors into the heart of Tavares,
attracted by retail, the arts, and festivals, and brought to us through improved infrastructure for
air, water, and rail transport. The following improvements were proposed as part of the CRA
plan:
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Wastewater collection system improvements – replacement of 54,950 linear feet of
gravity sewer and force mains
Potable water system improvements – replacement of approximately 77,450 linear feet
of existing water main
Stormwater system improvements – construction of more than 8,000 linear feet of new
collection system in two (2) phases and new treatment wetland
Roadway improvements – construction of 60,000 linear feet of roadway
Funding the Plan
Tavares’ CRA abuts Lake Dora to the south. Lake Dora is considered part of the Upper
Oklawaha River Basin. Lake Dora has been established as impaired and the Florida Department
of Environmental Protection (FDEP) has established Total Maximum Daily Loads (TMDL) for
total phosphorus. Lake Dora is the focal point of the City’s downtown redevelopment plan with
the expansion of parks, trails, businesses and other mixed use activities along the water front. It
is vital to the CRA plan that the water quality of Lake Dora be improved. City Planners knew
that with all the proposed improvements, additional impervious cover would be created. A region
approach was considered more cost effective than individual efforts to mitigate stormwater
impacts. The City decided to incorporate improvements to the quality of Lake Dora into the plan
to improve the quality of life for its citizens. The goals included:
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Reduce nutrient loading to Lake Dora.
Reduce total suspended solids loading to Lake Dora.
Use a stainable treatment approach.
Provide public education on stormwater pollution issues.
Enhance the quality of life, community vibrancy, and economic development in the City
of Tavares.
Through a collaborative effort with City Planners, ARCADIS developed a comprehensive plan
to redirect stormwater away from Lake Dora toward a multi-cell stormwater treatment wetland.
The stormwater design was done in concert with other major improvements to streets and
drainage, water mains and sanitary sewers. The treatment wetland is designed to reduce the
discharges of total phosphorus, total nitrogen and total suspended solids into Lake Dora and
contribute in the reduction of Lake Dora TMDLs. This load reduction will help maintain
designated uses established by FDEP for recreation, as well as for the propagation and
maintenance of a healthy, well-balanced population of fish and wildlife. This is key to the
economic success of the City of Tavares’ Downtown Community Redevelopment Plan.
Since many of the regulating agencies also provide funding for various water quality
improvement projects, it was crucial to sell the agencies on the fact that that the CRA plan would
benefit Lake Dora as much as it benefits Tavares. The strategy was very successful. The City
was able to secure over $6 million in grant funding from various agencies in water quality related
grants including FDEP, TMDL legislative appropriations, 319 grant, St. John’s River Water
Management District (SJRWMD), Community Budget Issue Request (CIBR), and Lake County
Water Authority (LCWA). Now the regulators are also invested in the success of the project.
This grant money, combined with low interest State Revolving Fund (SRF) loans, means the City
of Tavares is well on the way to seeing its vision become a reality.
Stormwater Improvements
To improve the water quality in Lake Dora, the first phase of the stormwater improvements
include a stormwater interceptor to divert the first 1-inch of stormwater from seven existing Lake
Dora outfalls into a wet detention pond. The project will contribute to the reduction of the FDEP
implemented TMDL for total phosphorus (TP), as well as total nitrogen (TN), and total
suspended solids (TSS). The project will also be used to inform and educate the public about
stormwater pollution issues. Phase 1 includes the construction of the following facilities:
• 8.5 acre stormwater treatment pond
• 3,400 linear feet of reinforced concrete pipe ranging from 15-inch to 36-inch pipe
• The elimination of four (4) out of seven (7) outfalls into Lake Dora
• The CRA drainage area encompasses nearly 400 areas of mixed-use commercial and
residential
• The system was modeled using Interconnected Channel and Pond Route (ICPR)
Innovative Wet Pond Design
The existing 8.5 acre wetland is a partially natural and manmade facility that has been in use as a
stormwater detention pond since the 1960s. The existing system provides little treatment, is
overgrown and is unmaintainable. Because it was left in an unmanaged state for so long, the
USACE has designated the facility as natural wetlands. The proposed project would impact
approximately 7.52 acres of the wetlands. Tavares plans to mitigate this loss through the
preservation of approximately 172 acres of forested uplands it owns within the same Southern
Ocklawaha River drainage basin. The proposed preservation area will be placed under a
conservation easement to the SJRWMD.
ARCADIS, in partnership with Griffey Engineering Inc., developed hybrid wetland systems with
enhanced nutrient removal capabilities, stormwater detention and a park-like setting. Treatment
wetland and ponds have become widely accepted as urban stormwater treatment devices over the
past two decades and are increasingly being integrated into water sensitive urban design
practices. This growing popularity has been largely due to the fact that wetland and pond based
systems offer the advantages of providing a relatively passive, low-maintenance and
operationally simple treatment solution while potentially enhancing habitat and aesthetic values
within the urban landscape. The system incorporates a more recent development, managed
aquatic plant systems (MAPS), which are floating treatment wetland and are an emerging variant
of constructed wetland technology. MAPS consist of emergent wetland plants growing
hydroponically on structures floating on the surface of a pond-like basin. They represent a means
of potentially improving the treatment performance of conventional pond systems by integrating
the beneficial aspects of emergent vegetation without being constrained by the requirement for
shallow water depth. In MAPS, the plant stems remain above the water level, while their roots
grow down through the buoyant structure and into the water column. In this way, the plants grow
in a hydroponic manner, taking their nutrition directly from the water column in the absence of
soil. Beneath the floating mat, a hanging network of roots, rhizomes and attached biofilms is
formed. This hanging root-biofilm network provides a biologically active surface area for
biochemical processes as well as physical processes such as filtering and entrapment.
For Tavares, ARCADIS combined all three aspects into one designed system. The initial deep
cell allows coarse sediment to collect. Deeper segments also combine aerobic, anoxic and
anaerobic zones for variable treatment
of organics and nutrients. As the water
passes to the next cell, a cascade
provides aeration. Emergent vegetation
in the shallow zones provides a thick
stem matrix for attached aerobic
bacterial along with the natural uptake
of nutrients from the plants. Fountains
may be added to provide aeration and
mixing while MAPS provide additional
nutrient reduction. Walking paths
traverse the entire system and offer an
enjoyable nature botanical garden like
experience. Water control structures
allow for raised water levels and shortterm detention during storm events for
permitted outfall control.
The MAPS are aquatic plant-based
BMPs, which remove nutrients through
a variety of processes related to
nutrient uptake, transformation, and
microbial activities. Examples include
planted littoral zones and floating
wetland. They can be incorporated into
a wet detention BMP treatment train to
provide additional treatment and
nutrient removal after the wet pond has
provided reduction of pollutants
through settling and other mechanisms.
The FDEP established BPM reductions
at 20 percent TP and 20 percent TN.
One of the most common trade names
for MAPS is Beemats.
Combined Nutrient Removal
The anticipated removal efficiencies for TP from the stormwater treatment pond are
estimated at 61.5 percent using the SJRWMD Lake Apopka Hydrologic Basin Pollutant Loading
Analysis. Removal efficiencies for TSS are estimated at 67 percent using the National Pollutant
Discharge Elimination System (NPDES) description of wet ponds. In order to qualify for certain
grant funding, a higher level of phosphorus removal is required. The final design includes a
series of deep and shallow cells.
This arrangement extends the littoral shelf areas in balance with deep open water sections.
The open water sections are enhanced with the floating MAPS.
In addition to plant uptakes, bacteria attach to the stem matrix to reduce organic compounds and
uptake nitrogen. Anaerobic zones in the deep cells provide nitrification followed by shallow cells
and denitrification. Shallow cells composed mostly of littoral zones increase soil contract with
phosphorus for more uptake along with plants. The modeled uptake results are stated below.
System
TP Reduction
TN Reduction
TSS Reduction
61.5%
43%
67%
Floating MAPS (> 5% Coverage)
20%
20%
-
Littoral Shelf and Marsh Cells
25%
25%
-
Bacteria / Denitrification
35%
35%
-
85%
78%
67%
Wet Ponds (Deep)
Total
Conclusion
The project is designed to meet the goal of significantly reducing the nutrient loading in Lake
Dora. It will do so through a sustainable treatment wetland in a park like setting. The City will
develop programs for public education that focus on the use of natural systems and the
importance of improving stormwater quality. The estimated project cost for Phase 1 is $3
million. The wetland will not only enhance the water quality, but also the quality of life for the
citizens of Tavares.