600 RIVERSIDE RD 2022-01-25 - Laserfiche WebLink

CITY OF EVERETT STORMWATER MANAGEMENT MANUAL • The windthrow hazard of Pacific Silver Fir and Madrona is high, while that of Western hemlock is moderate. The danger of windthrow increases where dense stands have been thinned. Other species (unless they are on shallow, wet soils less than 20 inches deep) have a low windthrow hazard. • Cottonwoods, maples, and willows have water -seeking roots. These can cause trouble in sewer lines and infiltration fields. On the other hand, they thrive in high moisture conditions that other trees would not. • Thinning operations in pure or mixed stands of Grand Fir, Pacific Silver Fir, Noble Fir, Sitka Spruce, Western Red Cedar, Western Hemlock, Pacific Dogwood, and Red Alder can cause serious disease problems. Disease can become established through damaged limbs, trunks, roots, and freshly cut stumps. Diseased and weakened trees are also susceptible to insect attack. Maintenance Standards 1. Inspect flagged and/or fenced areas regularly to make sure flagging or fencing has not been removed or damaged. If the flagging or fencing has been damaged or visibility reduced, it shall be repaired or replaced immediately and visibility restored. 2. If tree roots have been exposed or injured, prune cleanly with an appropriate pruning saw or lopers directly above the damaged roots and recover with native soils. Treatment of sap flowing trees (fir, hemlock, pine, soft maples) is not advised as sap forms a natural healing barrier. 3.2.2 BMP C102: Buffer Zones Purpose An undisturbed area or strip of natural vegetation or an established suitable planting that will provide a living filter to reduce soil erosion and runoff velocities. Conditions of Use Natural buffer zones are used along streams, wetlands and other bodies of water that need protection from erosion and sedimentation. Vegetative buffer zones can be used to protect natural swales and can be incorporated into the natural landscaping of an area. Critical -areas buffer zones shall not be used as sediment treatment areas. These areas shall remain completely undisturbed except as allowed by the Planning Department. Design and Installation Specifications 1. Preserving natural vegetation or plantings in clumps, blocks, or strips is generally the easiest and most successful method. 2. Leave all unstable steep slopes in natural vegetation. 3. Mark clearing limits and keep all equipment and construction debris out of the natural areas. High visibility plastic fencing is the most effective method in protecting sensitive areas and buffers. Alternatively, wire -backed silt fence on steel posts is marginally effective. Flagging alone is typically not effective. 4. Keep all excavations outside the dripline of trees and shrubs. 5. Do not push debris or extra soil into the buffer zone area because it will cause damage from burying and smothering. 6. Vegetative buffer zones for streams, lakes or other waterways shall be established by the City or other state or federal permits or approvals. Volume 11 — Construction Stormwater Pollution Prevention 3-3