Case Studies

Tree Condition Surveys & Inventory – St Albans Cathedral , London

Tree condition surveys, inventory and tree management plan for 250 trees in the grounds of St Albans Cathedral, London.

Crown Tree Consultancy were commissioned to carry out tree surveys at St Albans Cathedral, London. The tree surveys were predominantly for safety reasons. We were also asked to produce an inventory and record the condition of all trees within the cathedral grounds.

Within our report we produce tree location plans showing the location of individual trees as well as tree groups, giving them T numbers and management recommendations, if any should be required. In total we surveyed circa 250 trees.

Decay Detection in Cedar of Lebanon

Following the condition report, we were then further charged with undertaking decay detection of a Cedar of Lebanon tree using our specialist equipment:

• a PiCUS Sonic Tomograph
• Resi Drill™.

PiCUS Sonic Tomograph

The purpose of a PiCUS test being to determine the extent of decay throughout the stem of a tree by sending sound waves through the wood, the density of the wood is determined by how fast the sound travels through the wood (the quicker the sound travels the more decayed the wood is).

Resi Drill™

A Resi Drill™ is also used to help determine the extent of decay throughout the stem of a tree based on the drilling resistance. A Resi Drill™ is used with a hand held drill and a spinning probe is inserted in to the wood. The device measures the resistance that the wood offers while drilling. The obtained data can be recorded electronically and then transmitted, evaluated and processed on a PC with specific software. The measurement profile recorded whilst drilling provides information about the internal condition of the wood and any decayed zones.

Air Spade Investigation

We were also further commissioned to oversee an air spade investigation to determine the extent of the rooting activity around the Cedar of Lebanon. The main purpose of this being to assess what the impact of development within the surrounding area would have on the tree and its roots.

Our investigation concluded that providing any large roots were not harmed and an arborist present throughout construction stages, the proposed development would impose no harm to the tree’s condition and/or stability.

In conclusion, we will offer our services for an updated tree condition survey in approximately three years’ time to comply with British Standards.