Design of a Green Infrastructure 'Retrofit' as an Alternative to Conventional Stormwater Management for a Residential Subdivision

摘要

Following city approvals of a site plan and stormwater management plan for a thirty-four unit residential subdivision in Syracuse, New York, a "retrofit" of the plan was evaluated to incorporate green infrastructure (GI) instead of the conventional stormwater management (i.e. connected impervious areas and a stormwater pond) approved for the project. Based on an initial screening process, porous pavements and green roofs were identified as technically feasible GI techniques to potentially be incorporated at the project, given the dense nature of the proposed development and seasonally shallow depth to groundwater. Hydrologic simulation of the project with green roofs and porous pavements incorporated into the design indicates that the site will behave similar from a hydrologic standpoint under the developed and the existing conditions for the 1-yr 24-hr precipitation event. A constructed wetland, to be incorporated into the eastern portion of the site plan, will effectively detain more extreme events. Concerns often exist, however, with both the continued structural integrity of porous pavements in cold climates and the maintenance of surrounding groundwater quality where shallow depth to groundwater exists. Porous asphalt roads associated with the project will be constructed with a 30 in infiltration basin to provide protection of the frost-susceptible subgrade soils, and the porous bituminious top course and asphalt-treated permeable base will be elevated above the surrounding landscape to provide drainage and frost protection for these frost-susceptible courses. Porous drives and walks will be constructed with a geocell surface matrix that is less susceptible to frost damage. In combination with the dwelling green roofs, it is demonstrated that New York State water quality volume (WQv) treatment requirements and protection of surrounding groundwater quality will also be achieved.