Tree Management Protocol & Guidance

For full information about the Association of Tree Officer’s Risk Limitation Strategy, please visit: https://ltoa.org.uk/resources/risk-limitation-strategy

The following information will be required to prove subsidence damage has been caused by a Council owned tree.  The level of information required will depend upon the relative value of the tree and therefore the benefits it provides to the local area:

Low Value Tree: A low value tree that could be removed and replaced.

Site Information

• Report on damage to building.
• Plan and profile of foundations.
• Plan of site showing location of building in relation to all trees and significant vegetation in the vicinity of the site.

Test Results

• Trial pit cross section to underside of foundation depth plus borehole through base of trial pit to a minimum depth of 3m (explanation to be provided if borehole unable to reach 3m depth). Borehole log to be provided.
• Root ID from beneath underside of foundation.

Medium Value Tree: A medium value tree that makes an important contribution to the area.

Site Information

• The same site information is required as with Low Value Trees.

Test Results

• The same test results are required as with Low Value Trees, plus:
• Soil moisture content readings at 0.5m centres, starting at the underside of the foundation, down to 3m depth of B/H.
• Liquid limit test results at underside of foundation and approx. 2m depth.
• Plastic limit test results at underside of foundation and approx. 2m depth.
• Soil plasticity calculated from LL – PL.
• Control borehole to 3m depth with log, with same tests as above, if it is possible to locate such a borehole on the site and remote from the influence of any vegetation. If impossible then explanation needed.
• Oedometer or suction test results at underside of foundation & 1.0m centres down depth of 3m borehole ONLY when there is NO control borehole. If there is a control borehole then other tests listed are sufficient.
• Shear vane test results at 0.5m centres, starting at the underside of the foundation, down to 3m depth of borehole(s).
• CCTV & hydraulic testing to drains (excluding Water Board owned) located within 3m distance of area of subsidence damage. If unable to water test due to no access/blind entries/etc then give reason.
• Crack monitoring is required on a 6 weekly frequency and is to be set up ideally at time of first visit by building insurer representative or within 7 days of 1st visit. Send all available readings with Submission of Evidence.

High Value Tree: A high value tree that makes an extremely important contribution to the area.

Site Information

• The same site information is required as with Low and Medium Value Trees.

Test Results

• The same test results are required as with Low and Medium Value Trees, excluding crack monitoring.  In its place the following information will be required:
• Control borehole (if possible) & point of subsidence borehole, each to 5m depth (not 3m as for medium value).
• Level monitoring commencing at outset of claim for a relevant period (max. 12 months) using a deep datum (if possible) to 8m depth, otherwise use deep manhole.
• Particle Size Distribution Analysis to BS 1377 Part 2 test 9.0 on a single soil sample taken from a 1m zone below the underside of foundation (Only if drains are present within 3m of the site of damage).