CLS 2nd Edition Tree Protection

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#"&#%$ 3.1.1. PURPOSE STATEMENT AND INTENT 1. The intent of this section is to verify that the site to be developed is prepared in such a manner that it meets the performance goals of the landscape plan, complies with all local or municipal bylaws and provides worker and public safety. 2. All horticultural and non-horticultural elements contained within the site are assessed for preservation or removal; in the case of preservation, sites are subsequently managed in order to preserve or enhance their pre-construction condition. It is expected that horticultural elements deemed noxious or invasive in their locale be brought under a reasonable measure of control, based on specifications provided, and with management practices that reflect the local and/or municipal, provincial and federal bylaws and specific acts such as the Endangered Species Act and Migratory Bird Convention Act. 3.1.2. RELATED REFERENCES, STANDARDS AND LEGISLATION 1. Government a. NMS Section 32 01 90.33 Tree and Shrub Preservation b. NMS Section 35 01 40.92 Preservation of Water Courses and Wetlands c. Canada Occupational Health and Safety Regulations [Federal and Provincial] d. Canadian Environmental Protection Act [Federal and Provincial] e. C anada Wildlife Act [sections referring to birds, nests and eggs] f. T he Standards & Guidelines for the Conservation of Historic Places in Canada g. Weed Control Act [Federal and Provincial] h. Heritage Conservation Acts and resources [Provincial/Jurisdictional] i. Invasive Species Regulations [Provincial/ Jurisdictional] j. Agriculture Canada/Ministry of Agriculture [Federal and Provincial] k. Vegetation management for invasive plants and contaminated soils [Provincial/Jurisdictional] l. Tree Preservation/Protection Bylaws [Municipal] m. Underground Infrastructure Safety Enhancement Act 2. Industry a. American National Standards Institute ANSI A300 Tree Care Operations - Tree, Shrub, and Other Woody Plant Maintenance - Standard Practices b. N ational Voluntary Code of Conduct for the Ornamental Horticulture Industry, CSLA/CNLA 3.1.3. SITE ELEMENTS 1. Site elements and conditions may include, but are not limited to: a. Trees [individuals, groves or stands], shrubs and groundcovers b. Topography c. Natural systems d. Water sources: surface, ground, stormwater and wastewater e. Native soils and sub-soils f. Fauna g. Historical or archaeological elements h. Geologic [rock] formations i. Other important natural or man-made elements Page 2 







 


 


3.1.4. ASSESSMENT OF EXISTING SITE ELEMENTS AND PLANNING FOR PRESERVATION AND RELOCATION 1. Site inventory and identification for preservation and relocation a. Prior to any disruption of the project site, a qualified professional shall review and inventory all site elements that may be suitable/designated for preservation. b. Site elements should be considered in the context of their relationship and interaction with other elements located on the site. Feasibility of retention, preservation and relocation should be carefully considered and included as part of the contract documents where appropriate. c. Factors to be considered in preserving a site element include its condition, geographical location, health and accessibility; its relevance based on size and type, its ecological, historical, or unique qualities; anticipated success for preserva- tion or relocation, and susceptibility if disturbed at specific times of year. 2. Survey and element identification a. All elements determined to be suitable for retention, preservation or relocation shall be surveyed and documented before site planning is completed to determine: i. Exact location ii. Size, extent, and condition iii. Elevation iv. Relationship to proposed construction b. Existing tree and vegetation surveys should show accurate information regarding: i. Location ii. Elevation iii. Species iv. Trunk diameter [DBH - Diameter at Breast Height] v. Crown radius vi. Form and structure vii. Crown class viii. Plant health assessment ix. Soil composition c. Elements to be preserved should be tagged with number tags where appropriate to ensure that preservation instructions and recording will remain accurate throughout the construction process. 3. Assessment a. All elements identified for preservation shall be reviewed for hazards and safety by a qualified professional and appropriate hazard abatement measures shall be incorporated. b. Assessment findings and recommendations should be in writing and submitted as part of preliminary design work. 4. Trees a. An ISA Certified Arborist [CA], Registered Consulting arborists [RCA] or Tree Risk Assessment Qualified [TRAQ] professionals shall complete all tree assessments. b. Trees exhibiting abnormal growth patterns or characteristics which indicate instability shall be assessed prior to starting the project to verify that they are safe to retain. The following items should be considered: i. Tree species and rating ii. Structural condition iii. Biological health iv. Growth habit v. Trunk diameter [DBH] and crown radius vi. Preservation priority vii. Recommended action to preserve/remove/ relocate Page 3 






 


 

 viii. Specific defects ix. Special characteristics x. Potential targets c. Trees identified for preservation should have a recorded condition rating to enable accurate monitoring throughout site construction. Retention should be based on the following considerations: i. Species ii. Present age and life expectancy iii. Health and disease susceptibility iv. Structure v. Aesthetic values vi. Importance to the landscape design vii. Extent and feasibility of preservation mea- sures required viii. Sentimental, historical, heritage, or special considerations ix. Adaptability to a new environment 5. Critical protection zones a. Critical protection zones represent the area surrounding any element that shall be preserved and protected to enable the safety or survival of the element. These zones shall be assessed and documented prior to commencing work. b. Critical protection zones containing horticultural elements shall be monitored and kept sufficiently moist throughout the work. This may require supplementary irrigation. c. Critical protection zones for trees or plants are where most of their root mass is located. Under normal conditions 95 % of the root structures for most trees are found in the upper 30-45cm (12-18in.) of soil with root development extending beyond the canopy radius. Since most trees develop root structures beyond the canopy radius, the drip line radius of a tree should not be used as a guideline for critical root zone definition. d. The final location of the critical protection zone should be established after careful consideration of those factors that will affect the health of the tree. The distances outlined are only intended to be general guidelines in establishing Critical Protection Zones and in the absence of detailed work these distances could suffice. This work should be undertaken by a certified arborist or qualified professional and may result in an area that is larger than or perhaps smaller than that distance determined by dripline or DBH calculations. e. Municipal bylaws or other regulations may dictate measures to be undertaken regarding the critical protection zone. 3.1.5. DOCUMENTATION FOR PRESERVING SITE ELEMENTS 1. Preservation of site element specifications shall form part of the contract documents for all stages of work including: a. Demolition b. Site preparation c. Clearing and grubbing d. Landscape and maintenance plans 2. Site planning, design and project documents should include drawings and specifications for protection. Where proposed work will encroach on any critical protection zone the project documents should include specific details for adequate protection of the affected elements noted for preservation. 3. Onsite instruction should be provided to the site supervisor, and all project personnel shall be made aware of the exact location of site elements to be preserved and of protection requirements. Penalties associated with failure to comply with protection requirements shall be reviewed at that time. 3.1.6. PLANNING AND DOCUMENTATION FOR RELOCATING SITE ELEMENTS 1. Relocating site elements [e.g. large trees] is encouraged as an environmentally sound means of retaining existing elements when conditions permit. Page 4 







 


 


 
)&%  3.2.1. SCHEDULING 1. Work shall be carefully planned and scheduled to minimize damage to the environment and protected elements. 3.2.2. SAFETY 1. The work shall be carried out in compliance with applica- ble standards and regulations pertinent to construction site safety. 2. Utility installations such as sewer, telephone, fuel, hydro, waterlines, fiber optics or other underground and over- head installations shall be identified, and appropriate safety measures implemented. 3. Reference Canadian Common Ground Alliance CCGA Best Practices, current edition. 3.2.3. CRITICAL PROTECTION ZONES 1. General a. Critical protection zones shall be established before the start of work in compliance with all municipal bylaws, legislation, codes, regulations and standards. 2. Horticultural elements a. Protective fencing shall be located as required to define the critical protection zone unless other- wise specified or directed. b. Critical protection zones for trees should be determined by referencing Table T-3.1. Guideline For Determining Critical Protection Zones For Trees. Protection areas for unique situations such as leaning or columnar trees may vary from Table T-3.1. Guideline for determining critical protec- tion zones for trees. c. Critical protection zones for horticultural ele- ments depend on accurate evaluation of a variety of factors including: i. Pre-existing site conditions ii. Species tolerance to disturbance iii. Plant age and projected longevity 2. Recommendations regarding relocating site elements should be determined by a qualified professional. 3. Relocation or transplanting should be scheduled to coincide with other site construction work. 4. Factors to be considered in relocating horticultural elements include: a. Quality and health b. Size c. Ecological value, heritage, or historical significance d. Species e. Health and safety f. Growing medium and moisture levels at the new location g. Optimal lead time for root pruning h. Possibility of requiring storage i. Method of relocation and distance of move j. Time of year and weather conditions k. Projected success rate l. Cost benefit 5. Relocation procedures and on-going maintenance during and after relocation should be documented. 6. Relocated site elements shall be protected as required by this section before, during storage and after relocation. 3.1.7. REPORTING CHANGES OR DAMAGE 1. Any damage to elements designated for preservation shall be documented and reported to the consultant. 2. Any changes or damage to a designated critical protection zones shall be documented and reported to the consultant. 3. Any proposed changes to the size or location of a critical protection zone shall be approved by the consultant or qualified professional prior to any changes being made and verified by the consultant. Page 5 






 


 

 iv. Plant health and vigour v. Root spread and depth [root mass] vi. Site exposure and prevailing winds vii. Soil texture, structure and depth viii. Site hydrology %
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%#$ 3.2.4. PROTECTIVE FENCING 1. Physical protection barriers, silt fences, shade or erosion protection shall be erected at the edge of the critical protection zones before clearing, grubbing, excavation, grading, or any other sitework occurs in proximity. 2. Physical protection barriers shall meet all applicable municipal bylaws and regulatory requirements. 3. As a minimum, protective fencing should be erected outside the dripline or as shown in Table T-3.1. Guideline For Determining Critical Protection Zones For Trees. 4. Signage should be provided at regular intervals along protective fencing indicating the function of the fencing, i.e. “Tree/Plant Protection Area - Do Not Enter”. 5. Protective fencing and signage should be well main- tained for all element critical protection zones throughout construction. Damaged fencing or signs shall be repaired or replaced immediately. 6. Areas of trees and vegetation critical protection zones shall be fenced off by means of: a. Chain link fence of at least a 1.2m (4ft.) height mounted on steel or sturdy wooden posts. Fence posts should be installed no farther than 2.4m (8ft.) apart. b. Solid plywood hoarding mounted securely to steel or sturdy wooden posts. Posts should be installed no farther than 2.4m (8ft.) apart. c. Board fencing consisting of posts minimum of 2x4 (1.5in. x 3.5in. or 38mm x 89mm) set securely in the ground and extending at least 1m (39in.) above the ground shall be installed with a mini- mum of two 4cm x 8cm (2in.x4in.) horizontal boards fastened securely between posts. Fence posts should be installed no farther than 2.4m (8ft.) apart. d. Plastic fencing, [‘international orange’ polyeth- ylene web fencing – also known as snow fence or safety barrier] securely mounted on a wooden framework consisting of posts minimum of 4cm x 8cm (2in. x 4in.) set securely in the ground and extending at least 1m (39in.) above the ground and with minimum 4cm x 8cm (2in. x 4in.) top and bottom rail. Fence posts should be installed no farther than 2.4m (8ft.) apart. 7. Protective fencing shall be removed only when all construction is fully completed. 3.2.5. RELOCATION OF EXISTING ELEMENTS 1. Relocation or transplanting of elements should proceed when conditions are favorable for success and prior to any site construction, or, shall be scheduled to fit with other site construction work such that the elements to be Trunk Diameter [DBH] Minimum Protection Radius 20cm (8in.) 1.6m (5.0ft.) 25cm (10in.) 2.0m (6.5ft.) 30cm (12in.) 2.4m (8.0ft.) 35cm (14in.) 2.8m (9.0ft.) 40cm (16in.) 3.2m (10.5ft.) 45cm (18in.) 3.6m (12ft.) 50cm (20in.) 4.0m (13ft.) 55cm (22in.) 4.4m (14ft.) 60cm (24in.) 4.8m (16ft.) 75cm (30in.) 6.0m (20ft.) 90cm (35in.) 7.2m (24ft.) 100cm (39in.) 8.0m (26ft.) 120cm (47in.) 9.6m (31ft.) Page 6 







 


 


moved are protected as required by this section both before and after relocation. 2. Considerations for relocation of horticultural elements include: a. Plants should be relocated during their least active or dormant period. Reference Section 6, Plants & planting, for more details on suitable transplant periods. b. The growing medium should be irrigated to a depth of 50cm (20in.), 2 to 3 days prior to digging. Do not saturate soil. c. Rootball size for relocating plants should be determined based on such factors as soil type, species, size and condition. d. Rootball size for trees shall be determined by a qualified professional. As a minimum, rootball diameter should be 12 times the diameter of the trunk [or combined trunk diameters for multi-stemmed trees], measured 1m (39in.) above the existing undisturbed grade at the base of the tree. e. Root pruning in advance of tree relocation is recommended and should be scheduled for dormant season whenever possible. Roots should be pruned to the depth of the proposed excavation and 25cm (10in.) in from the line of excavation. Thorough watering after root pruning is recommended. f. After excavation, roots shall be cut cleanly with clean, sharp pruning tools. g. Once excavated, the rootball shall be kept moist and the plant should be planted as per Section 6, Plants & Planting or heeled in as soon as possible. The growing medium around roots shall be watered to eliminate air pockets. h. Table T-3.2. Root Pruning provides a guideline for root pruning different tree sizes. %
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!#& 3.2.6. HANDLING AND STORAGE OF HORTICULTURAL ELEMENTS 1. Reference Section 6, Plants & Planting. 3.2.7. PROTECTION OF THE ENVIRONMENT AND SITE ELEMENTS 1. Machinery a. There shall be no parking, fueling or servicing of vehicles or equipment within or close to vegeta- tion critical protection zones at any time through- out demolition, site preparation and construction phases. b. Where large construction equipment is stationed for extended periods on a site, care should be taken to prevent damage to plants from heat from exhaust pipes. c. There should be no passage of machinery of any kind through or within vegetation/horticultural element protection areas at any time, including the demolition and site preparation phases. d. Where equipment travels or other activities occur that are unavoidable within the critical protection zones, measures shall be taken to protect the root zone and minimize compaction as determined by Trunk Diameter (DBH) Distance from Trunk Minimum Preferred 15.0cm (6in.) 1.2m (4ft.) 1.5m (5ft.) 22.5cm (9in.) 1.2m (4ft.) 1.5m (5ft.) 30.0cm (12in.) 1.2m (4ft.) 1.8m (6ft.) 37.5cm (15in.) 1.5m (5ft.) 2.1m (7ft.) 45.0cm (18in.) 1.8m (6ft.) 2.4m (8ft.) 52.5cm (21in.) 2.1m (7ft.) 2.7m (9ft.) Page 7 






 


 

 the consultant, e.g. 30-45cm (12-18in.) of wood chips, bark mulch, or horticultural compaction mats. 2. Toxic chemicals and building materials a. There shall be no storage of equipment or building materials, no dumping of fluids, chemi- cals and no disposal of construction debris within the vegetation/horticultural element critical protection zones. b. Appropriate measures shall be taken so that no spillage of fuels, toxic construction materials or other toxic wastes occurs. Where use of such materials is necessary, adequate containment facilities and clean-up equipment shall be avail- able and utilized. c. No toxic or waste materials shall be dumped into water courses or any other water body either on or off the job site. d. No toxic materials, fertilizers, or fuels shall be stored adjacent to water courses or in a location where spillage could result in seepage into a watercourse. e. All toxic wastes and other construction material shall be disposed of in a manner acceptable to the owner and in accordance with municipal bylaws, and provincial and federal regulation. 3. Stockpiling a. There shall be no stockpiling of soils, fill, sand, gravel, or any construction materials within the vegetation/horticultural element critical protec- tion zones at any time during demolition, site preparation, and construction phases. b. Stockpiled soil or subsoil shall not be placed in low areas where natural drainage or stormwater could pond or erode these materials during inclement weather. 4. Fires a. There shall be no fires of any kind, for any reason, within a distance equal to four times the drip-line radius of the largest tree in the area of protection or within a predetermined minimum area unless otherwise specified by the consultant, qualified professional, and contractor. 5. Trenching or tunneling a. Tunneling [hydro excavation] rather than trench- ing should be considered when installing under- ground utilities and drainage lines to minimize damage to existing trees. Such work shall be planned and monitored by the consultant. b. Except as otherwise approved at the planning stage and in the field by the consultant, there shall be no trenching for drains or other services through or within critical protection zones. c. Where tunneling [hydro excavation] takes place within the critical protection zones, it shall be done as far away from the tree roots as possible. d. Where tunneling [hydro excavation] or trenching has exposed the roots of a tree, roots shall be protected and kept moist with wet burlap or peat moss until the trench or tunnel can be filled. e. Damaged or cut roots shall be cut cleanly with pruning tools. 6. Site drainage a. There shall be no direct discharge of storm or site drainage from construction areas through or into vegetation/horticultural elements protection areas, watercourses or ravines. b. All drainage water shall be filtered through acceptable sedimentation filtration systems before being discharged into the storm system, or as stipulated by the authority having jurisdic- tion. Measures such as retention ponds, siltation screens, and dikes shall be installed where necessary to prevent rapid runoff into water- courses as directed by a qualified professional or other governing authority. c. Prior to directing drainage to a storm system, the consultant should determine if the system can handle the water volume. Page 8 







 


 


j. Cover topsoil that has been piled for long term storage with a suitable cover crop to maintain agricultural potential of soil. 3.2.8 CLEARING AND GRUBBING 1. Existing site elements shall always be protected during clearing and grubbing operations. 2. Unusual or abnormal surface or subsurface conditions encountered on site during clearing and grubbing shall be documented and reported immediately to the consultant. 3. Cleared and grubbed materials shall be stockpiled separately from growing medium stockpiles. 4. Where noxious, undesirable weeds, or designated invasive species are found on site, grubbed materials shall be disposed of off-site as approved by the authority having jurisdiction. These materials shall not be used as a constit- uent of, or as a growing medium. 5. Stumps and visible surface roots shall be removed except where removal might adversely affect the health or stability of a nearby tree or other preserved element that has been identified for retention. 6. In natural areas, stumps and roots are an essential part of the natural system, adding stability, nutrients, protec- tion and habitat components to the site. Individual stumps and roots shall be assessed by the consultant to determine whether they should remain or be removed safely. Stumps and standing dead wood may be required to be retained for habitat or removed as in the case of termite protection zones as per local bylaws. Decisions should be document- ed in writing and included in the project documents. 7. Where stump removal is not recommended, the stump can be reduced by means of a mechanical stump grinder or retained as is, cut flush with the ground. 3.2.9. PRUNING 1. All pruning shall conform to ANSI A300 Tree Care Operations - Tree, Shrub, and Other Woody Plant Maintenance - Standard Practices. 2. Pruning prescriptions should be developed by a qualified professional with extensive knowledge of the site, the species in question, preservation techniques and objectives. 3. Risk reduction pruning shall be completed by or done under the direction of a qualified professional. 7. Erosion controls a. Temporary erosion control measures shall be provided to prevent excessive runoff to adjacent sites, or watercourses, or where a soil or subsoil erosion hazard exists. b. Temporary measures may include silt [sediment control] fencing, mulching, diking, ponding, terracing, or other means capable of reducing/ mitigating the effects of surface runoff. 8. Pruning a. There shall be no cutting of branches or roots of trees within critical protection zones at any time without written approval from the consultant. 9. Soil stripping a. Soil stripping operations shall be carried out in such a manner as to avoid release of silt, or sediment into any stream or other water body. b. Soil stripping procedures are conducted in accordance with applicable local/municipal requirements. c. Strip topsoil prior to commencement of con- struction to avoid compaction of topsoil intended for stripping and stockpiling. d. Handle topsoil only when in dry and unfrozen state. e. Strip topsoil by scraping Horizon A [topsoil] to depths determined by geotechnical report or as instructed. f. Stockpile topsoil in berms in designated location(s). g. Stockpiled height not to exceed 3 m. h. Protect stockpiles from contamination, erosion and compaction. i. Cover topsoil that has been piled for temporary storage with an environmental blanket or uni- formly applied blown hay or straw. Page 9 






 


 

 3.2.13. WATER AND IRRIGATION 1. Water used for irrigation shall meet this Standard as outlined in Section 2.1.18. Water and Irrigation. 2. Supplemental watering may be necessary during drought conditions or when an adequate site water source is not available. Provide for available irrigation water source prior to construction. 3. Horticultural elements whose root systems have undergone disturbance shall be provided with supplemen- tal water during dry weather periods. 4. Plants with significant root removal should be moni- tored regularly for irrigation needs. In the absence of precipitation, foliar and root watering shall be done as determined by the consultant. 5. Excessively compacted growing medium in the immedi- ate area of plants should be aerated or scarified while minimizing root damage and provided with supplemental watering during periods of dry weather. 6. During demolition, site preparation, and construction phases, irrigation lines should not be installed within the critical protection zone but shall be designed to spray water into the protection areas avoiding tree trunks. 7. Refer to Irrigation Association Landscape Irrigation Best Management Practices May 2014, Water Quality Assessment Table 1. 3.2.14. MAINTENANCE 1. A qualified professional shall prescribe care and mainte- nance for all trees. Should damage to protected trees occur the following maintenance guidelines should be followed: a. If the soil has become compacted over the root zone of any tree, the topsoil should be suitably aerated. b. Damage to the crown, trunk, or root system of any tree shall be repaired immediately. c. Damaged roots shall be cleanly cut. d. All tree limbs damaged during construction or removed for any other reason shall be cut outside the branch collar or reduced to an appropriately sized lateral limb. 3.1 General requirements 4. Maintenance pruning during the site preparation stage shall consist of crown cleaning to remove all dead, diseased, damaged, defected, and selective crossing branches and shall be done by or under the direction of a qualified professional. 5. Tree conditions not correctable by sound horticultural pruning shall be identified and brought to the owner and/ or consultant’s attention. 3.2.10. CABLING AND BRACING 1. The objectives of tree support systems should be defined prior to installation. 2. Where required, mechanical support systems should be used to provide supplementary support to leaders and individual limbs of trees to reduce risk and prolong tree retention. This practice is generally limited to high value individual specimens in high profile locations. All objec- tives and recommendations for support systems shall be provided in writing by a qualified professional familiar with tree growth habits, weights, and wood strength and included in project documents. 3. Installation shall conform to ANSI A300 Tree Care Operations - Tree, Shrub, and Other Woody Plant Maintenance - Standard Practices. 3.2.11. INSECT AND DISEASE CONTROL 1. An integrated pest management [IPM] and plant health care program should be developed to protect plants and trees which may have been weakened or stressed and made susceptible to diseases and insects. 2. Horticultural elements impacted to any degree by construction operations should be noted and monitored for changes. Instructions and maintenance procedures developed should be included in project documents. 3.2.12. INVASIVE SPECIES MANAGEMENT 1. Natural areas should be virtually free of invasive plant species. Invasive plant species should be eradicated at the time of construction. Depending on the extent, type and density of invasive plant cover, pre-planting treatments shall be undertaken and may include removal, repeated mowing during the growing season, and regulated herbi- cide treatment. 2. Municipal bylaws or other regulations may dictate measures to be undertaken regarding control and eradica- tion of invasive species.