Arboricultural site monitoring during construction

An arboricultural condition usually requires two documents and one ongoing activity. The method statement and the tree protection plan are produced before work starts. The monitoring schedule runs through the build, and it is the part contractors treat as optional and planning officers treat as the evidence that the other two were followed.

Get the monitoring right and the condition closes out on a single final report. Get it wrong and you are negotiating replacement planting with an officer who has photographs.

What a monitoring schedule contains

The schedule is set out in the arboricultural method statement, recommended by BS 5837, and approved with it. At a minimum it should state:

• the named arboriculturist and their qualifications, with a deputy
• the hold points at which attendance on site is required
• the frequency of routine visits between hold points
• what is inspected at each visit
• the form of the site record and who signs it
• the reporting interval to the local planning authority
• the procedure where a non-conformity is found
• the final inspection and sign-off

Vague schedules are the problem. "The arboriculturist will visit periodically" gives the contractor nothing to programme against and gives the officer nothing to check. Write dates against activities, not against the calendar, because build programmes move.

Hold points that need attendance

A hold point is a stage the contractor cannot pass until the arboriculturist has attended and recorded that the condition on site is as approved. The standard set:

1. Before anything arrives on site, to confirm the position of protective fencing and ground protection against the tree protection plan.
2. Before demolition of any structure within or adjacent to a root protection area.
3. Before any excavation inside a root protection area, including the method to be used.
4. During that excavation, because hand digging and air excavation need watching rather than describing.
5. Before the construction of any no-dig surfacing, to confirm the build-up and the geotextile.
6. Before service trenches are set out, to check the route against the trees and the agreed alternative where a direct line is not possible.
7. Before any approved tree surgery, to confirm the specification.
8. Before the protective fencing is removed at the end.

The fencing inspection is the one that matters most, because fencing erected after the first deliveries have been made has already failed. Our note on tree protection fencing specification and timing covers what the fence itself has to be.

Who signs the site record

Both the arboriculturist and the site manager. A record signed by one party is an opinion, and a record signed by both is a shared position that is far harder to dispute six months later.

The record for each visit should carry the date and time, who attended, the weather and ground conditions where relevant, the hold point or routine visit reference, what was inspected, photographs with locations identified, any non-conformity found, the action required, and the date by which it must be done.

Number the records sequentially and keep them in one file. At close-out you hand the file over, and a complete numbered set answers most questions before they are asked.

Reporting to the authority

The condition sets the interval. Common forms are a report within a stated number of working days of each hold point, a monthly summary, or both. Where the condition is silent, agree an interval with the tree officer in writing and follow it, because an officer who receives nothing for eight months will assume nothing happened.

Keep the reports short. A covering page with the site, the permission reference, the condition number and the period covered, then the numbered site records with their photographs. Officers are not reading for pleasure.

Report non-conformities in the report in which they occurred rather than after they are fixed. An authority that learns about an incursion from the remediation report rather than from the incident report draws conclusions about what else it has not been told.

When the protection zone is breached

It happens on most sites. What matters is the response.

The common thread is to stop, record and assess before anything else. Photographs taken before the contractor tidies up are the ones that matter, both for the tree and for the conversation with the authority.

Remember that where a tree is protected by an order, wilful damage or destruction is a criminal offence, so a serious incursion is not only a condition breach. Where damage to roots is extensive, the root protection area calculation gives you a basis for assessing the proportion lost, and our note on root protection area calculations covers the method, including the multi-stem case.

Remedial measures, and when to stop work

Remediation depends on the damage, and the honest arboricultural position is that most of it reduces harm rather than reverses it.

For compaction, decompaction with compressed air tools followed by mulching and, in dry periods, irrigation. For severed roots, cutting back to clean wounds rather than leaving crushed ends, then mulch and water. For bark damage, leave the wound undressed and monitor, because wound paints trap decay rather than preventing it. For soil contamination, excavate and replace under supervision.

Crown reduction is sometimes proposed to balance root loss, and it is a judgement call that needs the authority's agreement, since the tree is usually protected.

Stop work entirely where continuing would make the damage worse, where the structural stability of the tree is in question, or where the extent of root loss cannot be assessed while plant is operating. Write the authority to stop into the method statement, because an arboriculturist without that authority has only persuasion.

Closing out the condition

The final inspection confirms that the fencing and ground protection are removed only after the last operation that needed them, that the approved surfacing was built as specified, and that any planting required by other conditions is in place.

The close-out report should include the numbered site records, the photographic record, a statement of any non-conformities and how they were remedied, a condition assessment of each retained tree compared with the original tree survey, and a recommendation on aftercare for the next few seasons.

Where trees have been lost or are likely to decline, deal with replacement in the same report rather than waiting to be asked. Replacement planting obligations can run for years, and our note on tree replacement conditions and how long they bind explains the usual periods.

Build the monitoring into the construction programme and the sub-contract documents, not just the Construction Management Plan. An arboriculturist appointed by the client and unknown to the groundworks sub-contractor arrives to find the trench already open.

An illustrative case: a 14 unit scheme retaining two mature limes. Fencing went up correctly, then a drainage sub-contractor ran a trench three metres inside the root protection area over a weekend. The arboriculturist attended on the Monday, recorded severed roots up to 60 mm, stopped the works, and agreed a diverted route with hand excavation for the remainder. Both trees survived. The honest caveat is that the outcome would have been different in a dry summer, and nobody could have said so in advance.

Browse the report types PlanScope drafts if you need an arboricultural document structured before a qualified arboriculturist reviews it.

PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval. For specialist technical reports, qualified professional input may be required.