MANASOTA & PEACE RIVER BBDs Meeting Notebook 10-21-09.docx

N072
(Completed) Lake Eva Water Quality Improvement Project
Project Type Cooperative Funding
AOR(s)
Flood Protection, Water Quality
Basin(s) Peace River
Cooperator(s)
Haines City
Project Manager KOLASA, KEITH
Task Manager(s)
Status Completed
Description
The purpose of this Lake Eva stormwater project is to reduce nonpoint source pollutant loadings to the lake and
downstream water bodies. The proposed structure is a nutrient separating baffle box strategically located to collect
untreated stormwater runoff from a 180-acre urban basin, approximately 25% of the Lake Eva watershed. This
stormwater BMP project will reduce a significant amount of pollutant loading to the lake and the downstream water
bodies. Currently, less than 1% of the total contributing area to Lake Eva is served by a permitted stormwater
management system. This project was recommended within the recently completed Haines City Watershed
Management Plan (cooperatively funded by SWFWMD). This proposed stormwater project is ranked third within the
City's Capital Improvement Projects (CIPs) with funding allocated for the project through the City's stormwater utility.
Benefits
This project will enhance water quality of Lake Eva within the heart of Haines City by treating stormwater runoff in a
highly urbanized basin. The basin that will be retrofitted has had a history of water quality related to untreated runoff.
TSS loading from the downtown drainage basin is estimated to be 18,749 lb/yr while nutrient loading (nitrogen and
phosphorus) is estimated to be 620 lb/yr. The installation of the nutrient separating baffle box will reduce TSS by
approximately 80% and the nutrient loading by approximately 60%. The project will be located on City owned land to
eliminate land costs, will minimize culvert relocations to lower overall construction costs and the BMP structure will be
located in an accessible area for ease of maintenance.
Costs
The FY2009 budget is $500,000, of which 50% has been funded by Haines City ($250,000) in their FY2008 budget,
and 50% is requested to be funded by the Peace River Basin Board ($250,000). The funding table below includes
District staff salaries, travel and central garage charges.
Additional Information
The BMP for this water quality improvement project is a nutrient separating baffle box to be installed along an existing
outfall pipe to Lake Eva. The proposed system will capture and treat runoff at the 5th Street outfall where the majority
of the downtown drainage basin flows into Lake Eva (sub-basin of the Lake Eva basin). Lake Eva outfalls to the
Haines City Drainage District (HCDD) Ditch watershed, which drains to Lake Hamilton and ultimately to the Peace
Creek Drainage Ditch. The unit will be placed entirely underground. Ground level hatches are opened and the foliage
and sediment is vacuumed out of the unit during maintenance. A preliminary ICPR model was run to evaluate peak
discharge through the outfall pipe. Model results indicate that a 25 year, 24-hour storm event will produce a discharge
rate of 118 cfs through the pipe. The dimensions of the baffle box proposed for this location are 10-foot by 16-foot by
10.5-foot, which will be able to handle a 25-yr, 24-hr discharge rate through the 60-inch culvert. In combination with
the BMP, the existing outfall pipe will be slip-lined with HDPE, an end-wall treatment will be constructed and
downstream erosion control will be provided. The outfall pipe discharges to an open ditch that has eroded during past
years. The banks of the ditch are very steep and continued erosion causes bank failure. This stormwater BMP
project will also include bank excavation to reduce the steep slope, bank stabilization with geo-textile, and
sodding/landscaping. Landscaping will include upland and wetland native species. A preliminary spreadsheet
pollutant load analysis was performed for the downtown drainage basin using EMC values presented in the Watershed
Management Plan. A pre-application meeting was held with a SWFWMD permitting engineer and environmental staff
on December 12, 2007. SWFWMD staff indicated that the project was feasible and could be permitted through a
General Permit based on the presented information.
020 - Peace River Basin 330