Construction Near City Trees
- Anyone performing Any and All work within 10 feet of a city tree must possess a permit issued by the Springfield Forestry Division to avoid unsafe, hazardous and other conditions which may be detrimental or potentially detrimental to any city tree. It is incumbent upon the applicant to ascertain whether or not there are any trees or tree roots situated within the city right of way. Any and all trees that fall with the jurisdiction of the city of Springfield are protected by law from any and all damage thereto including but not limited to any incidental damages, damage to the canopy, or damage to the trunk or root zone during and in the course of any and all construction activities, and also the aftermath of any and all construction activities. No cutting or otherwise damaging of tree roots is permitted. Any and all tree work must be permitted. Tree work performed absent a permit can precipitate serious financial and legal repercussions.
- Applicants shall notify Springfield Forestry at least 20 business days prior to the commencement of any work requiring a permit.
- The contractor shall take extreme care to protect the root systems of the existing trees. The tree protection zone (TPZ) of any tree, or within ten (10) ft. of the trunk (whichever is greater). Every inch of DBH (diameter at breast height) of the tree represents one required radial foot of tree protection. This is done to minimize surface and subsurface root and soil compaction.
- If any machinery is operating within the TPZ, the affected area shall be covered with mulch to a depth of at least twelve (12)-inches and covered with plywood, Alturnamats, or metal plates to distribute weight in order to protect roots from damage caused by heavy equipment. Such covering shall be maintained during the course of construction and removed by hand or as specified by the city forester.
- When a deficiency in tree protection is determined by a city forester it must be remedied immediately. Failure to correct the deficiency immediately may result in violations and summons.
- Any damage to existing trees during construction shall be the contractor’s responsibility. The contractor shall perform remedial work to damaged trees at the contractor's expense; this work shall meet all Springfield forestry regulations.
- Roots over one (1)-inch in diameter shall not be cut without the written permission of the Forestry division.
- During excavation, to best protect tree roots, the contractor shall exercise extreme care in removing concrete or asphalt within the TPZ of existing trees. Pavement should be lifted rather than dragged. Any excavation within the TPZ shall be done by hand, or by pneumatic excavation to city forester’s specifications. Contractor is to schedule appointment with city forester prior to any excavation.
- If roots are to be exposed for a period greater than forty-eight (48)-hours, the exposed area shall be covered with at least six (6)-inches of mulch and maintained moist during the course of construction until the area can be properly backfilled. Photos to be taken periodically and reported to the forestry division.
- No runoff or spillage of noxious materials while mixing, placing, or storing construction material shall occur within the tree pit or TPZ. No ponding, eroding, or excessive wetting caused by dewatering operations shall occur within tree pit or TPZ.
- Preparatory pruning work shall be performed only when directed by a city forester. This work shall be performed in accordance with ANSI a300 standards and by a qualified, licensed & insured arborist or tree service company. Contractor is to follow all Springfield forestry permit & work order regulations. Contractor is responsible for scheduling the appointment with city forester.
- At the request of the City Forester, the presence of an ISA/MAA certified arborist shall be present during excavation within the TPZ. The certified arborist shall be contracted through an outside consulting firm and the cost shall be incorporated with all bids.
City Tree and Infrastructure Conflicts
In urban settings, limited distances between trees and infrastructure can restrict root space and increase the likelihood of infrastructure conflicts. Infrastructure repairs, as well as new construction, may necessitate excavation and root pruning. Improper excavation and root pruning too close to the trunk may directly destabilize trees and can also encourage root and root collar decay that can compromise stability.
Infrastructure obstructions and restrictive soils can limit the horizontal development of roots. In some cases, root development may be highly limited on one side of the tree. It should not be assumed that horizontal root development is symmetrical and uniform around the trunk of the trees in locations where restrictive soils and/or infrastructure obstructions exist.
Selective Root pruning prior to construction
Selective root pruning consists of soil excavation using supersonic air tools or hand tools, followed by cutting individual roots. This can make it possible to cut as few roots as possible or make several smaller cuts instead of a single larger diameter cut. Tools used for this are usually hand pruners, loppers, hand saws, reciprocating saws, oscillating saws or small chainsaws.
When tools not specifically designed for root cutting–such as trenchers, excavators, or backhoes—are used, they result in torn, splintered, and crushed roots, and thus are not acceptable. Root pruning is most efficiently accomplished with root pruning equipment specifically designed for that purpose pruning (e.g., Vermeer, Imants, or Dosko Root Pruner). Large circular saws used to cut concrete, and rock saws also are effective. The saws must cut through the woody roots to the depth of the required excavation. When excavation must occur within the TPZ, it may be necessary to dig soil away with a shovel, then cut the exposed root with a saw.
Process for Pruning Roots during excavation
- Stake the edge of excavation
- Cut with root pruning equipment at the edge of the excavation
- Dig a trench along the staked line. Equipment such as a backhoe can be used until roots 1 inch in diameter are encountered. Then, dig with a shovel
- When a root is encountered, expose it by removing soil by hand, and prune it off cleanly. Prune to a lateral root when possible. If excavation is for installing underground utilities, leave the roots intact and thread the lines underneath.
- Any exposed root end should be pruned rather than left torn or crushed. The final cut should result in a flat surface with the adjacent bark firmly attached.
Consequences of Root Pruning on Tree Stability
Root loss can affect tree health and stability. Cutting roots within the TPZ has a negative effect on both the health and stability of the tree. Approximately 75% of a tree’s roots exist within the TPZ. Cutting roots any closer to the tree is more likely to compromise stability.
Glossary of Terms
DBH- diameter of the trunk of the tree at chest (breast) height.
TPZ- the tree protection zone is DBH x 8 = TPZ radius in inches
Root Collar – the transition from trunk to roots. It is also called the root flare because on most tree species, the transition causes this area to expand, or flare.