10.12 Tree Protection & Preservation

Existing urban trees and forest should be preserved if they are in good health. Construction should be planned to provide for the preservation of significant trees. All trees deemed necessary for removal are subject to Referenced Memorandum DAIM-ED, 11 Jan 2007. This policy dictates that all merchantable wood products on Army Lands may not be abandoned, destroyed, or donated. Fort Carson had a merchantable wood products sales program. All wood greater than 8" diameter will be cut into 14-16" lengths and dropped off at Building 155 woodlot (Community Recycle Center east of Gate 3).

It is recommended that any contractors cutting trees on Fort Carson have a minimum license with Colorado Springs (City of Colorado Springs Tree Service Licensing, City Code 2.3.301) to do so, preferably the contractor is an ISA certified arborist. The city requires contractors to take a pruning text to ensure that they can cut correctly.

During the clearing and construction process, trees should be protected from damage. Construction barricades should be erected to protect the existing trees to be preserved. The barricades should be no closer to the trunk of the tree than one-half the distance from the trunk to the drip line. Existing trees that cannot be preserved should be considered for transplanting to a different location on site or to a different site.

Changes in the grade of the soil around trees can cause extensive root damage and eventually the death of the tree. To prevent damage to a tree, it is important to maintain the existing grade for least the size of the tree’s canopy (the drip line).

For more information see in FHWA/TX-04/0-4548-1 (partially included below) for further the tree protection standards on Fort Carson.

10.12.1 recommended tree and landform protections standards (portion of document fhwa/tx-04/0-4548-1

10.12.1.1 Protected Root Zone

The protected root zone is the area from the edge of the tree trunk outward for a distance equal to one and one-half (1½) times the distance from the trunk to the outer edge of the tree canopy foliage (drip line) at it farthest dimension.

Preferred Root Protection Zone – recommended area to be designated for protection, 1 ½ times the distance to the drip line.

Critical Root Zone – minimum area to be designated for protection, the distance to the drip line.

Prohibited activities:

Parking of any vehicles
Erection of any shed or structure
Storage of any equipment or materials
Use by people for any reason
Dumping of any waste materials or liquids
Impoundment of water
Addition of fill-soil
Excavation of any type

10.12.1.2 Barrier Fences

6’ chain-link fence (or High Density Polyethylene) on 8’ steel “T-post” spaced 6’ on-center and driven 2’ deep into the ground. Barriers will be erected on the line established by the engineer and/or according to the details and notes on the plan.

10.12.1.3 Wood Planking

To protect the trunk against any accidental contact with heavy equipment or tools, whenever construction activities must take place within 6 ft, secure wood completely planking around the trunk. The planking should be 2x4 lumber, self spaced around the trunk, and bound with a durable wire or rope material. Do not use any nails or screws to affix the planks as this will damage the tree. As soon the construction within the root zone area is complete, remove the planking and the surface protection. Use hand tools to remove mulch or gravel surface protection.

10.12.1.4 Filtration Berms

Shredded hardwood mulch berm placed immediately inside the protective fencing. Compost is optional.

10.12.1.5 Grade Changes (cut & fill)

Grade changes are discouraged within the protected root zone. Grade changes within the CRZ must follow procedures shown in the details.

10.12.1.6 Trenching

Trenching within the protected root zone is discouraged and forbidden within the CRZ except under specific conditions and using specific construction methods. Within the CRZ: bore at 3’ below grade Outside CRZ: bore beneath, expose roots and prune, or expose roots and thread utilities below roots.

10.12.1.7 Exposed Roots

Roots exposed within the protected root zone will be covered with an approved material within 24 hours after exposure. Hardwood mulch; compost optional.

10.12.1.8 Root Pruning

Where root removal is required, roots greater than 1” in diameter must be exposed without damaging them and cut with approved tools.

10.12.1.9 Sidewalks near Trees

Maintain minimum clearance of 3’ between tree and new sidewalks. If closer than 3’ consider flexible paving (pavers). Recommend use of root barriers behind curbs if tree species warrants.

10.12.1.10 Watering

Supplemental irrigation will be not be required unless roots are damaged or removed within the CRZ. Recommended but left to engineer.

10.12.1.11 Soil Compaction

Area of the protected root zone exposed to pedestrian or vehicular traffic must be covered with four inches of shredded hardwood bark or well-graded gravel over the affected area. For temporary or permanent situations. Must be removed when access is no longer needed.

10.12.1.12 Pruning

Pruning must be performed by a qualified arborist in accordance with the International Society of Arboriculture’s Tree-Pruning Guidelines and/or the ANSI 300 Pruning Standard.

Pruning will be required:

For reasons of safety
To allow clearance of equipment near the CRZ where breakage may otherwise occur
For removal of limbs that are dead or diseased
Clearance above present or future travel lanes

10.12.1.13 Chemical insect control

Chemical control of damaging insect pests will be required only if the pest is present (exceptions include engraver beetles) and only by a qualified tree specialist.

10.12.1.14 Dust control

There will be no requirement to spray trees or plants to remove foliar dust.

10.12.1.15 Protection of sensitive landforms

The protection of sensitive landforms shall conform to the standards for tree protection. See guidelines for discussion of possible sensitive landforms.

10.12.1.16 Signage during construction (optional)

Metal signs at 50’ spacing through the length of the fence. Single trees will have a minimum of two signs placed on opposite sides of the tree 12” wide, 8” tall, 1” tall bold black letters.

10.12.1.17 Post-construction activities

Post-construction assessment required by certified tree specialist. See guidelines for list of inspection items.

10.12.1.18 Post-construction protection alternatives for sensitive areas

Sensitive areas will receive post-construction protection. Three alternative procedures are provided. See guidelines for list.

10.12.1.19 Damage to Existing Trees

The Contractor will be assessed for damages to trees designated to be protected that result from the Contractor's negligence or failure to comply with the requirements of the specifications. Damages should be assessed in accordance with the criteria established in the guide for plant appraisal, (using the current revised edition), by the International Society of Arboriculture. Damages at the rate applicable therein should be deducted from any monies due the Contractor as liquidated damages.