Classroom Construction and Cut Roots

Damage Assessment for a Large Douglas-Fir – Lynnwood, WA

An elementary school was in process of building a new science classroom. The excavation and construction occurred within the dripline of two large Douglas-Firs (Pseudotsuga menziesii) that were each more than 30 inches diameter and over 100 feet tall. The term “dripline” describes the outer limit of branches and foliage. The area inside is the zone of greatest importance for tree health and stability. Root loss or damage within the dripline can have significant consequences for tree stability and long-term health.

Several large roots were damaged during excavation, prior to construction. Now, the contractors were preparing to back-fill around the foundation and had a limited timeframe to address the situation. The school administration and contractor were concerned about negative impacts to the trees and risk to new classroom structure. They wondered, should the trees be retained or removed?

Tree133 was contacted for a professional risk assessment and inspection of the damage. We promptly conducted a site visit with school administrators, engineers and contractors. It was fortunate the school could provide pictures of the site prior to construction. Beyond direct inspection of the mechanical damage to roots, these pictures helped us to determine the estimated root loss due to construction.

Our assessment determined the root loss was minimal due to prior site conditions. Further, we found the damage did not affect structural roots. We concluded these factors did not substantially increase the likelihood of failure and the trees could be reasonably retained on the site.

Additionally, Tree133 provided recommendations to help the client modify landscaping and irrigation plans to improve growing conditions and promote root growth. All findings and recommendations were delivered in a comprehensive Arborist Report.

If you are concerned about construction impacts for your trees, contact Tree133 for a site visit and professional risk assessment.