Division 32 - Tree Protection & Trimming

  1. This information provides guidelines for tree protection and trimming. Temporary facilities, schedule of penalties for damaged trees, and controls are covered in other parts of these standards or are available from the WWU project representative. 
  2. WWU project representative, Facilities Maintenance (FM), Outdoor Maintenance, Public Safety Office, and Environmental Health and Safety Office shall approve selection of materials, means, and methods. Unless otherwise approved, the design intent requires means and methods that provide minimal disruption to adjacent building activities and operations. 
  3. When working adjacent to occupied buildings, require means and methods that protect occupants from exposure to noise, dust, traffic, and other hazards.
  4. WWU project representative shall inform Outdoor Maintenance and other campus departments or groups affected by the planned tree trimming operations. 
  5. Indicate in Specification if a certified arborist is to be used on the project.
  6. FM project representative shall walk the site with Outdoor Maintenance before releasing the project for bid to determine locations of any vulnerable trees, overhanging limbs, and any items that may raise questions at a pre-bid walkthrough. The WWU project representative shall review requests from bidders for trimming in the field with Outdoor Maintenance. Identify in Addendum if trimming is substantial enough to warrant a change in scope to contract.
    • The contractor shall notify WWU project representative with requests for trimming by Western. If no tree trimming is called for in the construction documents, Outdoor Maintenance shall perform work under M&O Cost Center.  
    • Require Outdoor Maintenance approval prior to minor trimming by contractor.
  7. Install tree protection fencing prior to any site preparation grading or clearing and grubbing work. Fencing shall be a minimum four feet high of wood, chain link, or poly construction fencing. Maintain throughout construction.
  8. Protect root zone of trees designated to remain. 
  9. Critical Root Zone (CRZ) is:
    • 18" times the diameter breast height expressed in inches of tree trunk or trunks or encompasses an area determined for an individual tree to be the necessary root area for the    tree’s continued normal growth as demonstrated in a written report by a certified arborist and based on a documented field investigation and non-destructive physical testing, including but not limited to non-destructive excavation to delineate the root system to a minimum depth of 24" below grade, and no more than 48" below grade.
  10. Work within CRZ shall be limited to hand work.
  11. Any vehicular access required within a CRZ requires an 18" mat of woodchips and/or plywood sheets to avoid soil compaction and damage to roots.

Latest update

2023-11-06