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DUNSTER & ASSOCIATES Environmental Consultants Ltd. ___________________________________________________________________________ Tree Survey and Plan Specifications Development plans often involve working around trees. In order to ensure accurate depiction of trees within plans the following specifications should be used. These will save time and money for all parties involved. These specifications should be used in all private and municipal surveys and all development plans. For all Surveys and Development Plans 1 Check local bylaws and ensure that all bylaw sized trees are included in the survey. 2 Each bylaw sized tree needs to be identified by : - trunk diameter size in centimetres measured at a set point above ground. This varies by locality and is defined in the local tree bylaw, typically 1.3 or 1.4 metres above ground. - species (at a minimum differentiate conifers from deciduous trees) - crown spread in metres measured as a radius from edge of canopy to trunk The project arborist may add additional details such as present and predicted condition and health, risk, and required design issues. - if trees are identified on site with numbered tags, place these systematically at the same point on each tree, such as 1 metre above ground on the North side. - make sure the finished plans include the tag numbers correlated to a table of tree details. 3 All survey plans shall plot the trees accurately and to scale. - trunk diameters and crown spread shall be proportionately scaled. - tree locations shall be plotted using the centre of the tree trunk as the point location. Ground surveys should include an offset equal to the radius of the tree trunk to ensure accuracy. Trunk diameters are measured using a standard diameter tape that provides diameter as a direct reading. NOTE The use of a single CAD icon that is not correctly scaled is not acceptable. These give no indication of relative tree size and mislead the reader about possible development effects close to the tree. Differentiate the symbols between conifers and deciduous trees. 4 All setback zones or Tree Protection Zones (TPZ) shall be accurately plotted to scale. Many municipalities require fencing around trees, using the trunk diameter as the basis for sise of TPZ. The TPZ must be correctly plotted based on an accurate depiction of the tree trunk (be centre of trunk) and trunk size (diameter). Often the TPZ will also be the required location of the tree protection fence. ___________________________________________________________________________ 4621 Cliffwood Place, Victoria, B.C. Canada V8Y 1B6 Tel: 778 433 8465 email: jd@dunster.ca www.dunster.ca DUNSTER & ASSOCIATES Environmental Consultants Ltd. ___________________________________________________________________________ 5 All plans shall include a scale bar with scale shown in metres. The use of a scale ratio alone is not sufficient as plans may be photocopied and distorted, or copied at sizes other than the originally intended scale, and not all users have access to architect's or engineer's scales. The gradations should include at a minimum, divisions of 1 and 2 metres so that fine detail can easily be scaled right on the plans without needing to check for errors of distortion. 6 All plans shall include a North arrow, date, and source of the survey plan. - any details extracted from the base plans shall provide the same details. 7 Provide a separate sheet for tree location and retention details. Many development plans include multiple sheets of information. Providing a separate sheet for the tree data saves time and money as a reference point. Because project approval may take several years, it is often useful to be able to upgrade the one sheet alone - it may be required as a final condition of development permit approval. Updates required may include: - either, check tree diameters are current and that fencing layout details match the new diameters or, provide a note on the plan that the fencing location is based in the tree diameters originally measured. That helps site inspectors determine if fencing is or is not correctly placed. - check that all trees originally inventoried and depicted are still alive. Remove any dead trees from the base plans and ensure that all interested parties know why the tree symbols are now removed from updated plans. - make sure the tree plan sheet is dated and any revisions are noted in a side panel. If necessary, cross reference the plan to additional reports provided by the project arborist. Revision 2. 2012. DUNSTER & ASSOCIATES Environmental Consultants Ltd. ___________________________________________________________________________ 5 All plans shall include a scale bar with scale shown in metres. The use of a scale ratio alone is not sufficient as plans may be photocopied and distorted, or copied at sizes other than the originally intended scale, and not all users have access to architect's or engineer's scales. The gradations should include at a minimum, divisions of 1 and 2 metres so that fine detail can easily be scaled right on the plans without needing to check for errors of distortion. 6 All plans shall include a North arrow, date, and source of the survey plan. - any details extracted from the base plans shall provide the same details. 7 Provide a separate sheet for tree location and retention details. Many development plans include multiple sheets of information. Providing a separate sheet for the tree data saves time and money as a reference point. Because project approval may take several years, it is often useful to be able to upgrade the one sheet alone - it may be required as a final condition of development permit approval. Updates required may include: - either, check tree diameters are current and that fencing layout details match the new diameters or, provide a note on the plan that the fencing location is based in the tree diameters originally measured. That helps site inspectors determine if fencing is or is not correctly placed. - check that all trees originally inventoried and depicted are still alive. Remove any dead trees from the base plans and ensure that all interested parties know why the tree symbols are now removed from updated plans. - make sure the tree plan sheet is dated and any revisions are noted in a side panel. If necessary, cross reference the plan to additional reports provided by the project arborist. Revision 2. 2012. ◆ Are the facts being presented supported by the available evi- dence? There will be many situations where simple evidence will suf- fice to make a decision, so it is unwise to expect reams of detail in all cases. For example, tree height may be irrelevant in some applications, but vital in others. Trunk diameter is almost always a good criterion since most bylaws and ordinances have that as a threshold. But not all risk assess- ments require an advanced level of investigation, and not all aspects of every tree are always readily apparent, even if a lot of time and effort is expended. Location on site is always import- ant, so make sure the tree(s) are correctly mapped. That means making sure that all plans and CAD symbols are correctly por- trayed. Trunk and crown spread symbols must be plotted propor- tional to their actual size, and not simply what the designer felt would look good! If you need evi- dence about the potential effect of disturbances within a critical root zone, and that is calculated based on trunk diameter, then be sure the diameter was correctly measured, is up-to-date, and CAD symbols are correctly scaled from that data. Finally, when checking reports, be sure to check that the facts are supported by evidence. Evidence should not have been fabricated to support a foregone conclusion, and facts cannot be spontaneous- ly generated without supporting evidence. Many aspects of arbo- riculture are subjective, but under no circumstances should the con- clusion or opinion be arbitrary. It should always be clearly support- ed with well-presented evidence that is systematically laid out. 30 City Trees