Stormwater Quality Design Manual (May 2007) - City of Sacramento ...

Runoff Reduction Control Measure Fact SheetInterceptor TreesExisting TreesConservation of existing trees provides aesthetic value to a site as well as a water quality benefit. Creditsmay be applied for protected trees located within 25 feet of an impervious surface, as long as the trees arenot located in the designated “open space” for the project, for which credit has already been applied.Design CriteriaDesign criteria for interceptor trees are listed in Table INT-1.Table INT-1. Design Criteria for Interceptor TreesAlso see Appendix D for information on calculating runoff reduction credits and a list of Trees Qualifying forInterceptor Tree Runoff Reduction Credits.Variation Parameter CriteriaAll Planted Trees Size 15 gallon container (min.)New Evergreen andDeciduous TreesLocationMust be planted within 25 feet of ground-levelimpervious surfaces. Must not be spaced such that thecrowns overlap (at 15 years of growth).Installation and Irrigation Trees must be installed and irrigated in accordance withlocal permitting agency Landscaping Standards.See Appendix D for suggested tree species meeting size requirement.Existing Trees Species Any landscape appropriate tree speciesConstruction ConsiderationsNew trees• Do not allow soil in planter areas to be compacted during construction.• Do not allow soil in planter areas to become contaminated with construction related materialssuch as lime or limestone gravel.• Install irrigation system according to proper specifications.• When installing lawn around trees, install the grass no closer than 24 inches from the trunk.• Install protective fencing if construction is ongoing, to avoid damage to new trees.• Mulch with hardwood chips (not redwood or cedar)Existing trees• Proposed development plans and specifications must clearly state protection procedures for treesthat are to be preserved.• Existing trees must be protected during construction through the use of high-visibilityconstruction fencing set at the outer limit of the critical root zone. The fence must preventequipment traffic and storage under the trees. Excavation within this zone should beaccomplished by hand, and roots 1/2" and larger should be preserved. It is recommended thatpruning of the branches or roots be completed by, or under the supervision of, an arborist. Soilcompaction under trees should to be avoided.• Ensure that trees that receive irrigation continue to be watered during and after construction.Stormwater Quality Design Manual for the Sacramento and South Placer RegionsINT-4 May 2007