An accurately measured topographical survey should be undertaken showing all relevant features.
- Spot levels at the base of trees and throughout the site at an interval appropriate to meet design requirements, recorded as a grid and interpolated as contours, ensuring that any abrupt changes, embankments, ditch inverts and retaining features are recorded;
- The position of all trees within the site with a stem diameter of 75 mm or more, measured at 1.5 m above highest adjacent ground level;
- The position of trees with an estimated stem diameter of 75 mm or more that overhang the site or are located beyond the site boundaries within a distance of up to 12 times their estimated stem diameter;
- For individual trees, the crown spread taken at four cardinal points; for woodlands or substantial tree groups, the overall extent of the canopy;
- The extent, basal ground levels and height of shrub masses, hedges, hedgerows and stumps;
- Other relevant landscape features and artifacts, such as streams, buildings and other structures, boundary features and means of enclosure, trenching scars near to trees, and overhead and underground utility apparatus, including drainage runs with manholes and invert levels.
Based on British Standard 5837:2012 Trees in relation to design, demolition and construction - Recommendations.