AgdaPkt 2020-06-22 Joint SA PFA - Laserfiche WebLink

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6.1. - Page 24 of 52 i. The specific techniques employed shall be consistent with ISA A300 standards and ISA's Best Management Practices for the size and species of tree being trimmed. All dead, broken, damaged, diseased or insect infested limbs shall be removed at the trunk or main branch. All cuts shall be made so that wound closure can readily start under normal conditions. All limbs 2" or greater shall be made with proper pruning cuts to prevent splitting. The remaining limbs and branches shall not be split or broken at the cut. All crossed or rubbing limbs shall be removed unless removal will result in large gaps in the general outline of the tree. j. Cut laterals to preserve the natural form of the tree, leaving the head open enough for the branching system to show and permitting the dead material to be easily cleaned out and light to show through the head. Tree foliage shall be reduced by at least fifteen (15%) percent but no more than thirty (30%) percent. k. Trim to remove dead wood or weak, diseased, insect -infested, broken, low, or crossing limbs. Branches with an extremely narrow angle of attachment should normally be removed. I. Small limbs, including suckers and waterspouts, shall be cut close to the trunk or branch from which they arise. m. Heading cuts and/or topping will not be allowed unless specifically requested by the City. n. Heading, rounding over, or stubbing shall not be an accepted practice for reducing the size or the framework of any tree. iii. Pruning for Traffic Clearances Tree pruning for traffic clearances shall provide clearances of at least fourteen (14') feet above finish grade for moving vehicles within the traveled roadway, and eight (8') for pedestrians on sidewalks in accordance with standards set forth by the International Society of Arboriculture Pruning Standards (Best Management Practices) and the ANSI A300 Standards under "Pruning to Raise." Clearance trims are performed on a grid system or on a street -by -street basis. Clearances for adjacent structures and their connecting utility lines (service drops), shall be determined by the City's Tree Maintenance Leader and/or other authorized City staff and conform to the following: a. The minimum clearance under trees within the street right-of-way shall be fourteen (14') feet over the traveled road, and eight feet (8') over the curb line and the sidewalk side of the tree. When pruning the bottom branches, care shall be given to obtain a balanced appearance when viewed from across the street immediately opposite the tree. b. Cut to laterals to preserve the natural form of the tree. Remove lateral branches at their point of origin, or shorten the length of a branch by cutting to a lateral, which is large enough to assume leadership. c. When cutting back, avoid cutting back to small suckers. Remove smaller limbs and twigs in such a manner as to leave the foliage pattern evenly distributed. PUBLIC WORKS SERVICES DEPARTMENT FY 2019-20 RFP FOR COMPREHENSIVE STREET TREE MAINTENANCE SERVICES 10 OF 37 235