Agenda - Planning Commission - 10/04/2012

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As the largest natural resource component of the green infrastructure network, the urban forest should ideally be addressed through an integrated green infrastructure code and management structure that optimizes the ecological, social, and financial benefits it yields as part of a larger system. mine how much capacity they have to commit to enforcement. A higher level of complexity in regulations may require more staff commit- ment. However, the regulations do not have to be complex to be effective. They do need to be clearly tied to the objectives of the community and should be enforced by the proper profes- sionals with in-depth knowledge of trees (i.e., arborists, foresters, or landscape architects) and established authority for enforcement and applying penalties. RELATIONSHIP TO OTHER ORDINANCES The tree preservation ordinance, when closely tied to community objectives and properly enforced, is a powerful tool for protecting and enhancing the urban forest. Yet it is only one of several municipal codes that impact urban forestry and interact to achieve the social, environmental, and eco- nomic benefits of the urban forest. Stormwater Management Ordinances Trees have an important function in storm - water management, including intercepting rainwater and filtering pollutants. These functions can be incorporated into storm - water management ordinances by requiring tree preservation and replacement stan- dards as part of the stormwater manage- ment infrastructure and factoring the pres- ence of trees in pre- and postdevelopment calculations for stormwater flow. Zoning Ordinances Tree preservation regulations are often included in zoning and development codes as a stand-alone chapter or section. However, trees also typically appear in several other sections of the code, includ- ing landscaping standards, parking lot design, and riparian buffer requirements. The zoning ordinance should consider the various vegetative requirements in each section and make sure they are comple- mentary and not redundant or conflicting. Development standards, such as setbacks, minimum lot sizes, and parking regula- tions should also be conceived with tree coverage in mind to make sure the required amount of trees can be accommodated on a site. As an example, Seattle allows for reduced front and rear yard setbacks of up to five feet to protect existing healthy trees. Reductions of more than five feet may be approved by special exception. Erosion and Sedimentation Control Ordinances Like stormwater management, trees can be incorporated into the traditionally en- gineered standards for managing the im- pacts of development on streambanks and steep slopes. Trees stablilize streambanks and slopes by binding soil and preventing sedimentation. Arlington County, Virginia, requires a landscape conservation plan, a stormwater management plan, and an ero- sion and sediment control plan for develop- ment projects that would disturb at least 2,50o square feet of land. The landscape conservation plan helps ensure the health and survival of trees. Subdivision Ordinances Right-of-way requirements and street- and sidewalk -design standards are typically found in subdivision regulations. Right- of-way and street and sidewalk design are ZONINGPRACTICE 9.12 AMERICAN PLANNING ASSOCIATION Ipage 6