Item A: Green Infrastructure and Low-Impact Development

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The underlying principal of low-impact development is the integration of land use planning and stormwater management. The following are examples from Eugene and Portland of prescriptive and incentive based approaches to low-impact development – The City of Eugene’s Local Street Plan was adopted in 1996 and later incorporated into the Arterial and Collector Street Plan which was adopted in 1999. The Local Street Plan set design standards for “skinny streets.” The “skinny street” design standards were established to meet the goals of enhancing livability, safety, and quality of life. Stormwater management was not an identified goal of “skinny streets.” Because “skinny streets” cost less to construct and require less right-of-way, there is an incentive to build “skinny streets” in new development. As a result, most new local streets are 21-feet wide which allows two-way travel and parking on one side of the street. The overall effect has been a reduction in the amount of new impervious area and less impact to the hydrologic regime within the urban watershed than prior to the adoption of “skinny street” standards. The City of Portland adopted amendments to the regulations concerning Floor Area Ratios in the Development Standards for the Central City Plan District to allow additional floor area if an eco-roof is incorporated into the building design. Eco-roofs are stormwater facilities that reduce stormwater runoff, counter the increased heat of urban areas, and provide habitat for birds. Eco-roofs are one of the design methods allowed in the City of Eugene’s Stormwater Management Manual, however, there are not any incentives in the development code that would encourage the use of eco-roofs. The City of Portland adopted amendments to its development code related to parking lots to promote the integration of stormwater management facilities into parking lot layout. The amendments require interior landscaped areas sufficiently large to provide on-site stormwater management, improved planting of interior landscaped areas, and improved shading of parking areas. Vehicle parking capacity is maintained by reducing the minimum required sizes of parking spaces and aisles. The City of Eugene’s development code has landscape standards for parking lots, but does not specifically integrate stormwater management into parking lot standards. The stormwater development standards and Stormwater Management Manual were modeled on the best managements practices researched throughout the Northwest. They include the following prescriptive and incentive based approaches to require and/or encourage the use of low-impact development practices: The stormwater development standards require stormwater flow control (headwaters) to protect waterways in the headwater areas from the erosive effects of increases in stormwater runoff peak flow rates and volumes resulting from development. This is a regulatory approach to maintaining the pre-development hydrologic regime and meets the objective of Low Impact Development. The Stormwater Management Manual identifies impervious area reduction techniques that reduce the total amount of impervious area with a corresponding reduction in the amount of runoff to be treated. The techniques include eco-roofs, pervious pavements, contained planters, and credits for preserving or planting trees The Stormwater Management Manual includes the provision of SDC and user fees credits and incentives for private stormwater facilities that treat runoff from impervious areas not subject to the stormwater development standards. L:\CMO\2007 Council Agendas\M070117\S070117A.doc