How the Application of Environment Site Design Strategies and Low Impact Development Storm Water Treatment Systems Can Mimic the Natural Hydrologic Conditions in a Watershed and Provide a Resource for Carbon Sequestering

This paper will discuss how the application of Environmental Site Design Strategies (ESD) and the application of Low Impact Development (LID) storm water treatment can not only mimic the pre-development runoff curve number, but also remove non-point source pollutants from post-development runoff. ESD requires that civil engineers completely reevaluate the processes that they use to design a residential subdivision. ESD requires that the civil engineer evaluate the topography, soils, hydrology, vegetation and habitat on the site prior to the site design. This presentation will outline the necessary steps to evaluate the environmental parameters of the site prior to the design of a project. The environmental parameters to be evaluated include wetlands/watercourses/vernal pools, flood plains, steep slopes (generally >25%), unusual trees or vegetative systems, soils with high or moderate infiltration abilities, and other natural features. The ESD process is critical to achieving the LID goal of Hydrologic Transparency. By the implementation of LID treatment systems to treat runoff at its source, volumetric changes in runoff can be reduced and pollutants associated with non-point source runoff can be reduced through sedimentation, filtration, absorption and various chemical and biological reactions. Through the preservation of large extents of natural vegetated systems on a site, an additional environmental benefit can also be achieved. The preservation of large, contiguous areas of woodlands will provide a natural environment for the sequestering of carbon and the release of oxygen to the atmosphere. Lastly, this paper will show how the changing of the current development paradigm of prescriptive regulations to one utilizing ESD and LID, many of the adverse environmental impacts associated with development can be minimized while providing positive environmental benefits.