Resources for Designers
Successful tree management plans begin with thoughtful design and a basic understanding of tree biology. Efforts to protect existing trees should begin with the very first concept sketch and continue on long after the construction is complete. Be sure to include all the members of the design and construction team, property owners, and maintenance staff in strategies to create projects that will protect and enhance this vital and dynamic natural resource.
1. Start with a complete site plan. Make sure that utility locations (overhead and underground), existing and proposed contours and all proposed improvements are shown. Show existing site improvements and proposed demolition, if any.
2. Perform a site visit. Aerial photography and survey information are valuable tools to determining a baseline for existing tree locations and general site conditions, but a site visit is a critical step to evaluating the health of existing trees and planning for the establishment of new trees. Consider coordinating your site visit with the ACC Arborist (706-613-3515) or Community Forester (706-613-3561).
4. Show your work. Include the length of street frontages to show that the plan meets street tree requirements; include parking space counts to show that plan provides adequate parking lot trees; label square footages on groups of trees to show where calculations come from. The clearer the information is, the less guesswork there is for the reviewer which will result in a faster review!
5. Avoid common mistakes. Remember that canopy is always calculated as a percentage of total site acreage, not as a percentage of existing tree canopy. If tree conservation is required, show how fencing will be placed to adequately protect the tree protection zone, but remember that disturbance can never be closer than 10’ from a trunk. If the canopies of existing trees significantly overlap, the total canopy area should be calculated as a group rather than for individual credit.
6. Pick the right trees. Overhead utilities, minimum separation distances and open soil surface can all present challenges to tree species selection. Begin with the requirements for streetscape and parking lot trees found in 8-7-15(j)&(k) and work back to maximize tree canopy contribution where possible. Refer to the ACC Tree Species list for canopy contribution, applicability in certain site conditions and general planting information.
7. Consider the circumstances. With a clear plan in place, consider how the phases of construction might impact the design. Will tree protection fencing need to be moved during the course of demolition? Will construction be completed at a time of year that is stressful for tree planting? Talk any concerns out during the Plans Review process in order to avoid a delay in certificate of occupancy issuance or a costly stop-work order.
8. Fill in the details. Add standards notes and planting details. If there are special circumstances, such as installation of structural soils, make sure to include appropriate construction details and notes.
Provide a planting detail and standard notes in accordance with the technical standards found in section 8-7-19 of the Athens-Clarke County Unified Code of Ordinances. Suggested notes and details are available for download below.
The critical root zone (CRZ) is a more or less circular area above, and extending 24" below, the ground around the trunk of a tree. The radius of the CRZ is equivalent to the dripline of the tree, or 1.25 times the diameter breast height of the tree, whichever is greater. The CRZ increases in size as the tree grows.