FSA EXCELLENCE AWARD for STORMWATER PROJECTS – III. DESCRIPTION Lee County Division of Natural Resources – Lakes Park Water Quality Restoration Project
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Lee County, FL encompasses 804 square miles, 255 square miles of which are estuaries designated
Outstanding Florida Waters with a population over 600,000 full-time residents. Lee County is an award-
winning tourist destination with over $3 billion economic impact annually. Lee County’s Division of
Natural Resources (LCNR) manages 1,041 miles of waterways through stormwater pollution/illicit
discharge prevention, hazardous waste management, water resource monitoring, hydrologic
reconnection projects and water quality restoration.
Lee County has experienced a general decline in the quality of its surface water over the last several
decades due to development, agriculture and other human activities resulting in harmful algal blooms,
negative impacts to human and wildlife health, our economy as well as limiting the use of our water
resources. In accordance with Florida Administrative Code 62-303, the Florida Department of
Environmental Protection (FDEP) adopted TMDLs and subsequently basin management action plans in
Lee County to address water quality degradation. The primary pollutant of concern in Lee County is
nutrients, particularly nitrogen.
The Lakes Park Regional Park Facility (Lakes Park) is located in the headwaters of Hendry Creek, impaired
water body, a tributary to the Estero Bay, Florida’s first Aquatic Buffer Preserve and an Outstanding
Florida Water. The total drainage area contributing to Lakes Park is 1,750 acres. The drainage basin is
comprised of high-density residential and commercial land uses, many of which were built prior to
implementation of current water quality standards.
The Lee County is currently conducting a multi-phased
retrofit of Lakes Park to improve water quality of
stormwater runoff by routing flows through a created filter
marsh system. In addition to the recent filter marsh
expansion, Lee County is actively researching bio-chemical
processes to develop a water quality treatment facility on-
site further enhancing nutrient removal.
The Lakes Park Water Quality Restoration Project consists
of 30 acres of created wetland filter marsh system that is part of a multi-
use regional park that receives approximately 500,000 visitors per year
and supports recreational and educational opportunities, wildlife habitat
and community gardens. The multi-use facilities are supported by Lee
FSA EXCELLENCE AWARD for STORMWATER PROJECTS – III. DESCRIPTION Lee County Division of Natural Resources – Lakes Park Water Quality Restoration Project
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County Parks & Recreation and the Lakes Park Enrichment Foundation. This public-private partnership
has brought in millions of dollars in funding support, adding value to the residents and visitors of Lee
County by providing educational and recreational venues and events.
The Lakes Park Water Quality Improvement Project cost is $2,829,037 with $510,000 in grant funding
through the Florida Department of Environmental Protection and $1.2 million in funding from the South
Florida Water Management District. Personnel involved in the project include the Director, Roland
Ottolini, P.E., Surface Water Program Manager, Anura Karuna-Muni, P.E., Staff Engineer, Brian Bates,
P.E., Water Quality Planner, Karen Bickford, NPDES Operations Manager, Tony Pellicer, and NPDES
Coordinator Leigh Simmons. Project design, permitting and nutrient load reduction estimates were
performed by AIM Engineering & Surveying, Inc., and Boylan Environmental Consultants.
FSA EXCELLENCE AWARD for STORMWATER PROJECTS - IV. SUPPORTING INFORMATION Lee County Division of Natural Resources – Lakes Park Water Quality Restoration Project
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Hendry Creek is a tributary to the Estero Bay, designated Outstanding Florida Waters and the first
Aquatic Preserve in the state of Florida. Located in the southwestern Lee County in southwest Florida,
approximately 3 miles south of the City of Fort Myers and 3 miles southeast of the city of Cape Coral, the
Hendry Creek has a TMDL and a BMAP for total nitrogen and fecal coliform. Estero Bay proper is a
shallow, subtropical lagoon with an area of 17.7 square miles (mi2) (11,317 acres) separated from the
Gulf of Mexico by the barrier islands. In the past, the naturally dispersed water patterns distributed
nutrients over broad areas of wetland vegetation. Increased development since the 1960s has led to
changes in the natural river systems around Estero Bay, altering freshwater inflow patterns (Florida
Department of Environmental Protection [FDEP] 2003). The headwaters of Hendry Creek are bounded
by high-density residential and commercial land uses. Much of the watershed was developed prior to
current environmental resource permitting practices and lack sufficient treatment for stormwater
runoff.
The Lakes Regional Park Facility
(Lakes Park) is located in the
headwaters of Hendry Creek. The
total drainage area is 1,750 acres,
including the 329 acre Reflection
Lakes development. The upstream
portions of the watershed are
comprised of high-density
residential and commercial land
uses. The drainage basin runoff is
routed through a series of
wetlands, canals, and or weirs
before discharging into the Lakes
Park system. A public bathing
beach in the park was closed
several years ago due to poor
water quality. Lakes Park is
currently undergoing a multi-
phased retrofit to improve water
quality of flows received from
these upstream urban land uses.
Drainage basin boundaries,
system flow-through and
structures are indicated in Figure 1
(right).
The first phase of the project known as Reflection Lakes Flow Way located at the northern most in-flow
to Lakes Park is a sinuous marsh-type flow-way that creates an organic filtering system to help reduce
the quantity of surface water pollutants currently discharging into the Lakes Park from The Reflection
Figure 1
FSA EXCELLENCE AWARD for STORMWATER PROJECTS - IV. SUPPORTING INFORMATION Lee County Division of Natural Resources – Lakes Park Water Quality Restoration Project
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Lakes development. Reflection Lakes Flow Way is a 10.3 acre meandering flow way constructed by back-
filling portions of the existing borrow-pit, creating peninsulas which increase the littoral area along the
flow-way, supporting native plantings for water quality improvement. Reflection Lakes is a 329.28-Acre
mixed-use development bound on the North and West by Cypress Lake Boulevard and Summerlin Road
respectively. In 1998 Engle Homes/Southwest Florida, Inc., the developer and owner at the time,
obtained permits for the Reflection Lakes Flow Way as part of the development. The flow way
construction was completed and operational in July 2000 and deeded to the County in 2006. The
Reflection Lakes Flow Way is an additional retention/filtration best management practice built by the
developer, who in return received park impact fee credits from Lee County to the offset water quality
impacts to Lakes Park.
The next phase of the water quality improvement project included improvements to circulation through
the west lake during periods of flow, and enhanced nutrient removal from the west lake by the addition
of littoral “benches”. New structures to enhance circulation within Lakes Park included an inflow
structure at the north end of the west lake (Figure 1, LPCT-1) and an outflow structure at the south end
of the west lake (Figure 1, LPCT-3). The west lake inflow and outflow structures were modified with
operable gates to achieve the overall permitted discharges and to prevent saltwater backflow through
the existing outflow structure. Three existing spoil islands near the public beach area were modified to
create littoral “benches” through the removal of excess spoil material and exotic vegetation and native
wetland plantings.
The third phase of the project utilized the “East Lake” and “West Lake” of the Lakes Park system as an
extension of the existing filter marsh (the Reflection Lakes Flow Way) to the north leading into Lakes
Park. The new filter marsh consists of a series of “peninsulas" alternating from the east and west bank of
the East Lake to create a sinuous flow path similar to the Reflection Lakes Flow Way to the north. This
sinuous path maximizes the flow distance and contact time between the lake water and the vegetative
plantings surrounding the peninsulas. The peninsulas are varying in width and height with the highest
point being less than 1.0 foot above the control elevation (2.83 ft above sea level) of the East Lake.
During high flow events, most of the peninsulas will be submerged. The peninsulas are planted with
trees, shrubs, and herbaceous vegetation native to Florida. The area surrounding the peninsulas is
underwater "littoral shelves" that extend
horizontally at a shallow slope out to a depth of 0.5
ft below sea level. The shelf supports native
herbaceous and floating plants to absorb nutrients
from the water. Beyond that point, the slope
steepens to the bottom of the lake (average depth
approximately -6.0 ft below sea level) to create a
main flow way for storm water and provide aquatic
life refugia. The West Lake filter marsh construction
included removing top material and exotic
vegetation from the spoil islands in the middle of
Lakes Park to convert those areas into shallow,
FSA EXCELLENCE AWARD for STORMWATER PROJECTS - IV. SUPPORTING INFORMATION Lee County Division of Natural Resources – Lakes Park Water Quality Restoration Project
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submerged, meandering littoral shelves to support wetland vegetation plantings. Construction of the
filter marshes was completed in November 2012. Lee County estimates that the filter marsh system
alone will remove approximately 8,000 lbs/yr TN and 500 lbs/yr TP by macrophyte uptake, settling and
denitrification as well as bi-annual plant harvesting. Load reduction estimates were calculated as
follows:
Mass Removal Rate (MRR) and Annual Removal Rate (ANR) Calculations – Following the load reduction estimate includes Kadlec and Knight (1996) and the MRRs for the Lakes Park system were estimated using measured data from a project with similar environmental conditions and native vegetation as the project under consideration. The Ten Mile Canal filter marsh, located less than a mile from Lakes Park, was deemed appropriate for this purpose. Boylan Environmental Consultants (2010) first determined the MRR for Ten Mile Canal using monitoring data then adjusted these MRRs to account for the “operational” differences between the filter marsh systems. Specifically, the MRRs were adjusted to account for the fact that Lakes Park is an inline system, so losses via percolation into the surrounding soils is not expected to occur and if so, at a reduced rate compared with Ten Mile Canal. The adjustments were made by assuming that the outflow volume for Ten Mile Canal equals the inflow volume minus evapotranspiration losses. The adjusted MRRs were then used to determine the ANR for Lakes Park according to the equation: MRR (lb/acre/yr) x Filter Marsh Area (acres) = ANR (lbs/yr)
The calculated adjusted MRRs for TN and TP are 231.13 and 14.43 lb per acre per year, respectively. For purposes of estimating the ANR for the Reflections Flow Way, it was assumed that the MRRs for Reflection Lakes are the same as those calculated for West Lake and East Lake. The following table summarizes the estimated annual nutrient load reductions for each of the three project components. Component Treatment Acres MRR (lb/ac/yr) ARN (lb/yr)
East Lake 17.04
TN 231.13 3,938.5
TP 14.43 245.9
West Lake 8.95
TN 231.13 2,068.6
TP 14.43 129.1
Reflection Lakes Flow Way 10.3
TN 231.13 2,380.6
TP 14.43 148.6
Total 36.29
TN 8,387.7
TP 523.6
Because a filter marsh alone might not achieve the water quality improvement objectives for the much
more turbid West Lake, other treatment processes to reduce nutrients were proposed. The two
processes Lee County is currently considering for additional treatment includes alum injection and ultra-
violate (UV) bio-carbon treatment.
The Comprehensive Everglades Restoration Program (CERP) has helped spur investigation of various
nutrient reduction technologies as well as refining our understanding of the issues that drive nutrient
reduction in various treatment systems. An important finding from CERP is that dissolved inorganic
FSA EXCELLENCE AWARD for STORMWATER PROJECTS - IV. SUPPORTING INFORMATION Lee County Division of Natural Resources – Lakes Park Water Quality Restoration Project
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nitrogen (DIN) are labile and can be treated effectively in passive treatment systems such as filter
marshes by macrophyte uptake and dentrification, whereas dissolved organic nitrogen (DON) is
recalcitrant and cannot be utilized by macrophytes nor denitrify, leading to export of nitrogen from the
system. This led to the realization that to effectively treat surface water runoff for nitrogen, we have to
convert DON to DIN to allow macrophyte uptake and anaerobic denitrification.
Aluminum Sulfate ("Alum") injection is used commonly to accomplish algae precipitation in drinking
water treatment systems. Lee County’s Olga Water Treatment Plant uses Alum (with other processes) to
make drinking water from the Caloosahatchee River. Alum has also been used extensively for sediment
control on construction projects and nutrient removal for lake restoration most prominently by the
Reedy Creek Improvement District in Orange County, Florida. While alum has been implemented with
success for stormwater treatment in other locations it has high operation and maintenance costs. The
results of Lee County’s pilot alum testing project completed in 2010 at Lakes Park for surface water
treatment were compelling; nutrient removal efficiencies of 33% for TN and 78% for TP optimized at 70
ppm alum. As indicated in the Lakes Park final alum pilot test report, the County would have to factor in
sludge processing, handling, pH management in the returning waters and removal options that would
include variations on cost, staff, and other park-affecting requirements. Taking this into consideration
Lee County is currently conducting research at Lakes Park to compare the costs and benefits of UV/bio-
carbon treatment in addition to alum treatment.
Ultra-violet/bio-carbon treatment is an emerging field of research. The lead investigator for this pilot
project, HSA Engineers & Scientists, Inc., the County’s engineering consultant, specialized in nutrient
removal optimization for CERP. To date HSA has conducted literature research finding strong evidence
from various bodies of work1 that ultra-violet light can be used to cleave organic nitrogen and that the
resulting product are labile nitrogen forms; ammonia and nitrate. Ammonia and nitrate/nitrite are
relatively easy forms of nitrogen to treat aerobically or anaerobically. Ammonia is easily converted to
nitrate by denitrifying bacteria under aerobic conditions and under anaerobic conditions nitrate in the
presence of bio-carbon is readily converted to nitrogen gas (denitrification), effectively removing it from
surface waters.
Upon conclusion of the UV/bio-carbon pilot study and comparison of Alum and UV/bio-carbon
treatment costs and benefits, Natural Resources will select the most cost effective of the two treatment
technologies and proceed to design and permit a full scale (2 MGD) treatment facility situated and
hidden from view so as not to disturb park visitors or wildlife. The facility will provide a complete
“turnover” of West Lake water twice a year. The clarified water from the treatment facility will be
returned to the headwaters of the West Lake for repeated passes through a new filter marsh for further
nutrient removal. Along the route of the recirculating line, lateral lines will be installed to allow for
additional aeration and circulation within the West Lake. It is projected that over time, the quality of
water in the Park will be restored to levels that will allow uses currently not possible, and reduce the
impact on the downstream estuarine system.
1Phase I Pilot Testing To Reduce Nitrogen Content of Surface Waters, HSA Engineers & Scientists, Inc., March 17, 2011.
FSA EXCELLENCE AWARD for STORMWATER PROJECTS - IV. SUPPORTING INFORMATION Lee County Division of Natural Resources – Lakes Park Water Quality Restoration Project
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BEFORE
Before After