The following specifications and standards of practice apply to cavity work on trees in the City:
1. Extensive cavity work should not be performed on a tree unless it is of sufficiently high value to justify the cost.
2. The sides and ends of all cavity openings shall conform with the direction of sap flow. The cambium edge shall be protected at all times during the work by the application of shellac. A cavity filling shall not protrude beyond the cambium layer at any point along the cavity edge.
3. Provisions shall be made for drainage from a cavity which may exude sap behind the filling.
4. As a general rule, cables should be placed as high as approximately two-thirds (2/3) of the distance between the crotch and branch ends. Rust-resistant cables, thimbles and lags shall be used. The ends of a cable shall be attached to hooks or eyes of the lags or bolts. Thimbles shall be used in the eye splice in each end of the cable. In no instance shall the cable be wrapped around a branch.