Agenda - Planning Commission - 04/07/2016

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away from the development site and into storm sewers, detention ponds, or nearby water bod- ies. However, new concepts are shifting the momentum in a new direction. Low -impact development (LID) is a set of techniques with the goal to restore or maintain predevelopment hydrological conditions, usually focused on retaining more stormwater where it falls. LID is generally focused on the site scale and uses natural systems and engineered systems. Simi- larly, green infrastructure is a set of techniques utilizing natural resources to manage stormwa- ter and help preserve the ecological function of watersheds. Green infrastructure can occur at both the site and larger scale (neighborhood, municipal, regional, or watershed). Forexam- ple, while using porous pavement in a parking lot for a commercial subdivision is definitely a LID technique, some may not consider it a green infrastructure technique. Both techniques are decentralized storm - water management strategies that provide on -site water quantity and quality treatment, which is their main difference from traditional gray -infrastructure -based stormwater manage- ment. See the Resource Box for more infor- mation. It is also important to keep in mind that green and gray are not entirely mutually exclusive choices. Both have a role to play in addressing stormwater management problems, but they work in very different ways. Communities can require the use of green infrastructure and LID techniques in both stormwater management and roadway design sections of subdivision regulations. These design elements can include bioswales, enhanced infiltration ditches along roadsides, and the general reduction of impervious surface area through the use of LID roadway and parking design standards. They can also require that postdevelopment peak storm flows and runoff be no higher than it was prior to development. Finally, they can require, prior to any site alterations, the development and sub- mittal of a stormwater control plan, stormwater operations maintenance manual, and budget. A good example of using LID comes from Rhode Island's LID Site Planning and Design Manual, which recommends requiring, for parking lots of io or more spaces, that io percent of the parking tot area be dedicated to landscaped ar- eas that can include LID stormwater practices. Finally, communities can also focus more on habitat protection through a number of measures in subdivision approval, including identifying conservation land priorities such as protecting wetlands, undisturbed riparian areas, and the protection of rare or endangered species. Habitat assessments can be prepared to demonstrate that any subdivision activities will not adversely impact the habitat and spe- cies supported by the site and describe appro- priate mitigation measures. CONCLUSION This article has focused specifically on a range of subdivision approval standards that can be adopted to enhance the management of flood risks connected with subdivision development. There is little question that, in many parts of the nation, there is ample room for tightening requirements and ramping up expectations for performance in this regard. What this article does not cover so much, but the forthcoming PAS report does, is the set of larger issues and principles that should underlie the subdivision approval process as we move toward a much better -informed planning process with regard to floodptain management. It is important, as emphasized nearly six years ago in Hazard Mitigation: Integrating Best Practices into Plan- ning (PAS 56o), the best overall approach is to incorporate these subdivision standards into a holistic planning approach to risk manage- ment. The best way to anchor these enhanced subdivision standards is in a larger community strategy to achieve disaster resilience. ABOUT THE AUTHORS Chad Berginnis is executive director of the Association of State Floodplain Managers (ASFPM). Since 1993, his work has focused on floodptain management, hazard mitigation, and land -use planning at the state and local levels. Prior to joining ASFPM in zo11, he worked for the State of Ohio; Perry County, Ohio; and Michael BakerJr., Inc. James C. Schwab, AICP, is a senior research associate for the American Planning Association and the manager ofAPA's Hazards Planning Research Center. He is also coeditor of Zoning Practice. Q Floodplain boundary markers are required in Licking County, Ohio. These permanent markers are steel posts, approximately four feet high with a clear label. In this subdivision, a floodptain boundary marker is required every other lot. ZONINGPRACTICE 3.16 AMERICAN PLANNING ASSOCIATION I page 6