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Attachment 2: Landscaping and Tree Preservation Standards - REVISED JUNE 21, 2010 Page 9 b. Planting Requirements: 1) To promote development of a large, healthy canopy, trees shall be planted in accordance with the requirements in the following table and illustration: Tree Size Minimum island width for roots (back of curb to back of curb) Minimum tree opening Minimum planting soil depth Minimum cubic feet of soil available per tree in a single bed Minimum cubic feet of soil available per tree in a shared bed or three sided island Large Tree 9, -0" 4' x 6' or 5'x5' 30" 440 CF 400 CF Medium Tree : 6' -0" 5' x 5' or 30" 300 CF 270 CF Small Tree 5' -0" 4' x 5' 30" 250 CF 225 CF Minimum Island Width 2' 16' typical car space Planting Soil Engineered Planting Soil Calculate planting soil volume by Length x Width x Depth Minimum Island Width dimension can be reduced to the Minimum Tree Opening dimension if engineered planting soils are used beneath adjacent hardscape to achieve required soil volume. 2) Soils: Landscaped areas need high quality soils that retain moisture for plants to use, but drain adequately. Soil shall be uncompacted existing soil, new planting soil or engineered soils designed to allow plant growth. Proper soil preparation helps to ensure long term survival of the plants and to reduce the need for ongoing maintenance, additives, and pest control. If soil compaction exceeds 1400 kPa (200 psi) at the time of planting, the soil shall be loosened. Preexisting soils may be used and should be protected from compaction during construction. 3) Mulch: Mulch helps plant health by keeping the soil moist, protecting soil nutrients, preventing erosion, encouraging infiltration, and inhibiting weed growth. Mulch from decomposing materials such as wood chips enriches the soil over time. Although decomposing mulch needs to be replenished approximately twice a year to maintain • •