Agenda - Planning Commission - 04/07/2016

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Accounting for Flood Hazards in the Subdivision Approval Process By Chad Berginnis and James C. Schwab, A!CP Along with zoning, the subdivision ordinance is a cornerstone of land -use controls for local governments in the U.S. In fact, many smaller jurisdictions that have never enacted zoning ordinances nonetheless have subdivision ordinances of necessity. Carving up smaller residential. parcels out of large blocks of land has long been the path to growth at the local level. Later this year, the American Planning Association will publish a new Planning Advi- sory Service (PAS) report, Subdivision Design and Flood Hazard Areas, the result of a project funded by the Federal Emergency Management Agency (FEMA) and led by APA's Hazards Plan- ning Center, in cooperation with the Associa- tion of State Floodplain Managers. The report examines how, and how well, communities incorporate consideration of flood hazard areas into their subdivision approval process, and recommends best practices. The project extends the work of a 1997 PAS report by Marya Morris, Subdivision Design in Flood Hazard Areas (PAS 473), which pursued similar ques- tions and identified both problems and recom- mended solutions. But why focus on floodplain management as a subdivision issue? Isn't flooding a larger community problem? The answer to the latter question is obviously yes, but that does not ne- gate the value of specifically scrutinizing how subdivision design may contribute to the prob- lem —or the solution. There are aspects of the subdivision approval process that are impor- tant factors in the creation of overall flood risk in a community. This issue of Zoning Practice Note the stack of wood pallets and woody debris for campfires in one of this subdivision's stormwater retention areas. If the retention area was flooded, the woody debris could clog the outlet, threatening the integrity of the retention area berm and causing more significant flooding. draws on the forthcoming PAS report to high- light those questions and suggest answers. Our research during the project revealed that the following issues in subdivision design are of particular concern to justify this attention: • It is not at all the case that flood hazard areas have all been appropriately identi- fied, thus making it feasible to decide where subdivisions should or should not be located. • Floodplains are not static features of the landscape, but rather are dynamically af- fected by new development, which can potentially increase flood risks by reducing impervious surface. • There is also a need to protect the natural and beneficial functions of floodplains that is often not recognized adequately during the process of reviewing and approving subdivision plans. With that in mind, the purposes of the new report, and of this article, are to: 1) update the recommended standards for subdivisions with respect to flood hazard areas; 2) examine applicable new knowledge in the field of flood - plain management, including data related to climate change; and 3) place this information fn the larger context of overall land -use plan- ning in the community. This article does not attempt to sum- marize all aspects of the PAS report. It focuses instead on specific areas of concern for up- dating subdivision standards to improve the management of flood risk. The report includes a wider discussion of the overall issue and a number of case studies highlighting valuable lessons from states and communities. ZONINGPRACTICE 3.16 AMERICAN PLANNING ASSOCIATION I page 2