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Water Flowing through Mead Garden
The southernmost headwaters of Howell Creek, flowing through Mead Garden, originate near the Orlando Magic Arena. After flowing through Mead, they enter the Winter Park chain of lakes, then make their way all the way to Jacksonville and the Atlantic Ocean. The quality of Howell Creek waters is vital to the quality of the major Winter Park lakes.
Winter Park received a federal EPA grant in 2006 for $270,000 to construct storm water improvements in and around Mead Garden. The grant was administered through the Florida Department of Environmental Protection. The completed project included three separate phases that will improve the quality of storm water entering Howell Creek as it flows through MG. This project will also help restore the hydroperiod and habitat value of the large wetland in the north section of the Garden:
The first phase created more stormwater storage in the “clay pit” area near the western end of the park by Denning Drive. Improvements include construction of low berms to allow water to stage up (store before it flows) and debris to settle out during rainfalls; building of boardwalks and trails; and reforestation of the pit with native wetland species.
Phase two involved the installation of a low weir on the outfall of the large northern wetland to create a more natural hydroperiod for that area.
The final phase involved the construction of a sediment removal system for storm water entering the wetland from the area around the intersection of Pennsylvania and Melrose avenues.
The following is an interview with Tim Egan, Winter Park's Environmental Resource Manager, responsible for Lakes and Waterways in the City.
Q. Please explain the more natural hydroperiod you are striving for.
A. The wetland in Mead Garden has been channelized to let high water run off quickly to Howell Creek. The result is that water does not get as high as normal or stay in the wetland as long as it naturally would. We can’t practically raise the high water level due to surrounding development, but we can keep water in the wetland through most of the wet season by constructing a weir across the channel that drains to the creek.
The weir, with walls formed of aluminum or vinyl sheets, will be mostly hidden by walkways. It will keep the wet season high water level at about where it is now and stop water from running out quickly when rainfall tapers off ... the transition from wet to dry will be more subtle, much longer than it is now. The weir will allow us to restore the hydroperiod (the seasonal timing and duration of high and low water levels in a wetland) more closely to the Garden’s natural conditions. These conditions are estimated from statistical data of yearly water levels, and from natural indicators such as soils, vegetation types, and topography.
Q. How will the berms be built?
A. They will be earthen walls that form three “containers” in descending stepwise order across the bottom of the clay pit area and will hold water from rainfalls. The topography of the pit will not be altered.
Q. How do the berms work?
A. In a rainfall, they will hold back most of the storm water runoff, although some water will flow through. A “bleed down” mechanism designed into the berms will control the rate of water outflow with two results: it mimics a natural flowing wetland that normally leaks water downstream at a low rate, and it allows us to recover storage volume for the next storm. Slowing of the flow provides treatment... sediments fall out, and biological activities remove nutrients or convert them to less available forms.
Q. How will all this improve habitat?
A. The clay pit was altered by human activity, and now has a large amount of non-native vegetation. We will replant with native trees and shrubs; the species chosen will match the hydrologic conditions we will create with the berms. Within the wetland, the extended high water time will prevent loss of wetland soils to oxidation, thereby improving the health of canopy trees and reducing their high wind susceptibility. The increased wetness will reduce some of the exotic plants now growing in profusion.
Q. What trees do you have in mind?
A. We envision a full canopy of cypress and bay trees, keeping the bays that are growing there now. The camphor trees at the bottom of the pit will be removed or left as roost trees. They most likely will die with changes in water levels. For the most part, trees on the slopes will not be affected.
Q. What will be the storm water retrofits?
A. All of the above projects are storm water retrofits:
- The clay pit to store more water and remove pollutants;
- The outfall channel in the wetland with a weir to extend high water conditions;
- The existing storm water pipes outside the park to remove sediments and debris before rainfall runs into the wetland and creek.
Tim Egan can be reached at Tim Eagan.