The site's location and large size made it difficult to comply with new regulations. Geotechnical investigations revealed that the existing site conditions – low slope, high groundwater, and clay soils with low infiltration rates – would make it difficult, if possible, to implement common infiltration techniques.
This site is located on flat terrain and has limited stormwater management options. In contrast to other locations farther away, where low impact development solutions are cost-effective and manageable, there are more options.
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Although there are no nutrient banks in the area, the civil team looked into purchasing credits from nutrient banking, which allows owners to purchase credits towards compliance.
The limited lot size presented significant challenges and only limited options for managing runoff after the zoning requirements for parking, loading, and facility were met.
This experience demonstrated the importance of owner and developer knowledge about the impacts of stringent regulations. Developers naturally want to maximize return on investment and minimize costs.
However, sometimes purchasing more land is more cost-effective than paying for the design, construction, maintenance, and management costs for stormwater management within a smaller area.
The civil design team created a 'treatment track' to maximize the green space. It consists of several stormwater management elements that work together to reduce runoff and replicate natural water filtration processes.
Rooftop disconnects, soil-amended and amended swales, permeable pavements, amended soils, and a type 2 wet swale are all part of the treatment train. This large wet swale, which measures 22 feet in width, plays an important role in managing the runoff from the site. The flow direction is indicated by the arrows in between treatment areas.