Excavating Around Trees
When digging or excavating around trees there is an absolute need to be mindful of the roots as if these are damaged it can cause significant harm to the tree and even kill it.
In an ideal world no excavation will occur in what is called the root zone of a tree. The root zone is calculated by measuring the diameter of the trunk. This is then used to calculate the area that should not be dug in as there is a high risk to causing damage to the roots of the tree.
However, it is often necessary to dig around them and sometimes near them when building foundations or inserting utilities. So how can we help?
What happens when you need to dig near a tree?
If you need to dig near a tree to put in a foundation or utilities, we will follow the following process:
- We would come out and conduct a survey of the tree and area. This allows us to look at multiple factors that will influence our recommendations and enables us to advise not only what is best for the health of the tree but also from a commercial perspective.
- We would then put together a detailed report and method statement; all our reports are to BS5837:2012 standard.
- The report would contain detailed recommendations that would normally enable the work to be carried out whilst also protecting the health of the tree and meeting the requirements of the council’s Arboriculture officer.
How close can you excavate next to a tree?
Typically, the “rootzone” area has a radius of 12x the diameter of the trunk. Outside this area you can carry out ground works unhindered. However, within this area you will require a tree survey carried out by a qualified arboriculturist and a report with recommendations along with a detailed method statement.
How do you protect tree roots during excavation?
If we need to excavate within the rootzone of a tree we can use an “air-spade”. This is the recommended way of excavating in an area that is likely to have roots. This does take significantly longer than simply digging with a digger, but it enables us to dig without damaging the roots. If there are small roots that are less than 30mm in diameter these can be carefully cut with a pruning saw or secateurs. However, any larger roots will need to be looked at on an individual basis as these may need to be excavated around.
Can you dig around tree roots?
Yes, you can dig around roots, however this needs to be done very carefully. We would use an air-spade or soil pick. This selective excavator breaks up porous and semi-porous soils, whilst leaving non-porous objects unaffected. This is achieved by firing an airstream that is supersonic travelling at Mach 2, leaving both utilities and tree roots unaffected.
How deep do you need to dig around a tree?
It is quite possible to dig under a tree as it is rare that tree roots are deeper than 1m. However, when digging under a tree you still need to be very careful to ensure that there are no roots. By careful moling and use of cameras this can be achieved successfully especially when digging at 1m or greater below the majority of trees. As with anything there is always the exception to the rule and some trees have substantial tap roots. In these cases, these need to be avoided and dug around.
Trees on construction sites:
This is where most of our work takes place and with 20+ years of experience there is not much we have not previously encountered.
We aim to be commercially minded, with the aim of supporting the architect or builder to achieve the construction of property or wall with the minimum disruption to the site, whilst keeping the cost down for the needed works to enable the build to proceed smoothly.
If you need any advice on excavating or digging around trees or through their rootzone, please do phone or email. We aim to answer all calls within three rings and emails within the hour.
