Attachment_Number_0002_140P4321Q0044_CACO_tree_protection_and_tree_root_BMPs.docx

CACO Tree and Root Protection – Best Management Practices and Recommendations

PLANNING/PRIOR TO CONSTRUCTION -

Establish a Critical Root Zone (CRZ) for both large and small trees. Identify potential issue trees and determine if they should be removed prior to construction.

· Some tree species are more tolerant of damage and disturbance in the CRZ than others. A tree’s tolerance depends not only upon the species but also upon conditions present prior to and at the time of the damage. Tree health, age of the tree, soil aeration and moisture, the time of year the damage occurs, its severity, and the weather conditions prior to, during, and after the damage all contribute to the tree’s response.

· An experienced, certified arborist can analyze these variables and make specific recommendations to retain or recover a tree’s health and safety during and after the construction process.

· Most tree roots over 4 inches in diameter are likely to be structural roots; cutting these roots may impact the structural stability of the tree, creating the potential for catastrophic failure (the tree may fall over).

· Never remove more than 25 percent of a root system.

Have an certified arborist perform any advance pruning that will reduce physical damage to low limbs, etcetera, especially considering the clearances required by equipment.

DURING CONSTRUCTION -

Soil compaction

· Heavy equipment should be located outside the root cut line or remain on existing pavement or on a soil-protecting surface.

· Temporary staging areas for excavated soil should be located at a safe distance on the side of the trench furthest from the trunk.

Root cutting (subterranean)

· If appropriate, assign an arborist to monitor construction and assure that damage to trees is kept to a minimum.

· When possible, complete work in the early spring and end all root cutting my mid-summer. This will allow for maximum root recovery before dormancy.

· Roots should be cut with equipment that minimizes cracking the wood and tearing the bark. Where tree roots must be cut, make only sharp, clean cuts to promote root callusing and regeneration.

· Root pruning tools shall include but are not limited to: handsaws; lopping shears; chisels; hand shears; chain saws; reciprocating saws; and, circular saws.

· Cuts should be clean and perpendicular to the natural growth direction. Also, backfill within an hour of cutting roots and water the tree within 24 hours. Severing roots can have a significant impact on tree health and survival, as well as tree stability.

· If this is not achievable, replace the backfill on the same day if at all possible. Cover exposed roots with wet burlap to prevent them from drying out (from wind and sun); in hot dry conditions, small roots may be injured in as little as 30 minutes.

· Where cuts are to occur, root pruning shall be to a depth of 24" or to the depth of the excavation, whichever is less.

· If earthwork specifications allow it, firm the backfill to the same compaction as the surrounding soil and no more. Water the backfill to prevent excessive root drying.

· Do not allow chemicals, trash, or other foreign debris to become mixed with the backfill.

· Monitor tree health and compliance with tree protection requirements regularly during construction.

Root cutting (surface roots)

· If a surface root absolutely must go, excavate the soil adjacent to the root in order to make a clean vertical cut. Then remove the offending root.

· After a tree's root is cut, leave the cut end of the root exposed to the open air and not cover with soil for 2-3 days. This will provide sufficient time for the root to form a healing layer of cells over the wound tissue and to deter invasion by any fungal disease pathogens that may be present in the soil. You don't need to apply a pruning paint or fungicide.

· After removing a surface root, help the tree recover by providing supplemental water during dry weather periods.

Barrier installation tips

· Place the barriers sufficiently away from the structure (like six inches) to be protected so that expansion of the root will keep the root from touching the path.

· Root barriers must remain visible (extend at least 2.5 cm above the soil and mulch line) to prevent surface roots from growing over the top. If the soil should settle, be sure the barrier does not.

· Rigid plastic materials must be UV resistant or the exposed edge will possibly deteriorate; also plastic is a durable material but can become brittle in freezing weather.

POST CONSTRUCTION -

Complete postconstruction tree maintenance, including mulch, fertilization, irrigation, soil aeration, and pruning where necessary.

· In the absence of adequate rainfall, apply at least 1 inch of water per week by deep soaking methods.

· Fertilize trees with phosphorus, potassium, calcium, magnesium, and other macro- and micro-nutrients as indicated by a soil test but wait at least 1 year to apply any nitrogen.

· Fertilize lightly with nitrogen after 1 year. If recommended by an arborist, light annual applications of nitrogen may be made for the next 3 to 5 years.

· Whenever large roots are cut, there is a corresponding loss of branches; be prepared to remove dying branches in the future.

· Inspect trees annually for at least 3 to 5 years after construction to look for changes in condition and signs of insects or disease, and to determine maintenance needs.

2021/6/2