As the Forest Preserve District constructs new amenities and site improvements to enhance the public’s experience within the preserves, the District is required to mitigate negative effects on the adjacent areas through construction of stormwater best management practice (BMP) enhancements. Negative impacts include the reduction of groundwater infiltration and increase of stormwater runoff as a result of impervious surfaces such as parking lots and structures.
In order to offset the impervious areas and their negative effects, the District constructs a variety of BMPs to improve water quality and enhance the aesthetics of the preserves. These BMPs are vegetated with plants native to DuPage County and consist of rain gardens, bio-swales, detention basins, filter strips and enhancements to existing features such as wetlands and wetland buffers. The BMPs slow down and contain the stormwater runoff onsite. By doing so they reduce peak flows in rivers; prevent sediments and pollutants from entering a local body of water; reduce the temperature of runoff; and allow for groundwater infiltration; all of these are just some of the benefits of BMPs, which also provide habitat for native plants, wildlife, and local pollinators.
This project consists of the construction and vegetative management of BMPs associated with completed construction projects. All permitted BMPs are required to meet or exceed certain performance criteria set forth in the DuPage County Stormwater & Flood Plain Ordinance. To achieve the performance criteria, the BMPs shall be diversely vegetated with native plants to create a dynamic habitat that can handle drought, flooding and polluted stormwater runoff.
To ensure that the criteria is met and exceeded, the District performs selective mowing and herbicide applications to control and eliminate invasive, weedy and nonnative plants; provides supplemental seeding and plant augmentation to stabilize the soil and add plant diversity; and performs annual vegetation and site surveys to monitor the condition of the BMPs.
This project is ongoing at the following forest preserves: Blackwell, Danada, East Branch, Hawk Hollow, Herrick Lake, Mallard Lake, Mayslake, Songbird Slough, Timber Ridge and Waterfall Glen. The contractor shall perform management under direction of the District’s project manager and the work generally shall not affect trail access or preserve use.
Approximately $210,000 has been budgeted in yearly Capital Development Funds to cover all costs associated with the design, permitting, and management of 16 capital improvement project (CIP) stormwater management enhancement sites throughout the District.