Urban Forestry — Abstract of Paper


Supersonic Air Jets Preserve Tree Roots in Underground Pipeline Installation
Rob Gross¹ and Michelle Julene²


Tree roots are often damaged during construction projects, particularly during trenching operations for pipeline installation. Although mechanical soil excavation using heavy equipment, such as an excavator or backhoe is considered the fastest the most economical method, it damages and destroys tree roots and can lead to unintentional tree loss, poor public relations, fines, and litigation. In sensitive areas around tree roots, soil excavation can be completed by hand although this is very slow and expensive. Alternate soil excavation methodologies are available, including a special technique that uses supersonic air streams to explode soil around non-porous items such as pipes, fiber optic cables, sewer and phone lines, and tree roots. This paper discusses the use of this technique for "high value" coast live oak trees (Quercus agrifolia) in urbanized areas. A case study is presented that discusses an appropriate application of the pneumatic soil excavation method. The pneumatic method is a valuable technique for root zone soil excavation. It preserves tree roots during construction to allow retention of the structural integrity of the root system and provides an opportunity to accurately understand actual root, soil, and tree conditions. This improves discussions with an affected tree owner, or other interested party, regarding future management options of the tree.