What is a root protection area ?

The root protection area

The root protection area is the minimum area around a tree that it is considered is necessary to protect its root system from damage such as construction or compaction.

Arborists calculate it either by a formula or by drawing it manually.

How is a root protection area calculated?

Under the British Standard BS5837 for each tree, the arborist calculates the RPA by multiplying the diameter breast height ( DBH ) of the tree in meters by 12.  A simple circle is then drawn around the centre point of the trunk to this distance.  A maximum RPA of a radius of 15m is assumed.  There are more complex rules for calculating trees with multiple stems.

The arborist can hence provide a simple diagram of the root protection areas for trees, which is easy to calculate and understand.

How is a root protection area estimated manually ?

Although root protection areas are drawn simplistically as a circle, often in practice they are asymetrical or even irregular shapes.

Drawing a root protection area manually is more complicated than the formula approach  and requires input from an experienced arborist. The estimation may also often involve further ground investigations. This might include digging of small test pits to look for roots or other specialist equipment. The arborist will allow for the factors like :

  • hard surfaces,
  • previous trenching works,
  • water sources,
  • soil conditions
  • and the ecology of the tree.

Accurate manual drawing of root protection areas is particularly important on resticted sites or for large trees and important specimens.

How is a root protection area used ?

Architects and planners can use root protection area in site design for buildings and roads, but service trenches as well.  The arborist will use it later for a detailed Arboricultural Method Statement to show how to protect tree roots in constuction.

 

 

Photo gallery for newts

Update: Great Crested Newt licencing and mitigation review

Natural England is reviewing its approach to great crested newt licencing and mitigation approach, which will be introduced across the country. In each county, the approach will begin with a study to identify where newts are, and then create a map of the potential impacts of development to form appropriate conservation strategies in partnership with local government bodies. In the meantime, the existing methods of great crested newt mitigation for development projects withstand and there are no plans to abolish the laws protecting this species.

Great Crested Newt on hand

Read more about it in our previous newsletter article

If you want advice about how these changes might affect your company please contact us.

 

Suction solution for no-cut root route

In June 2017, Anglian Water began work on a pipeline renewal scheme at Belstead Water Tower, Ipswich. Trenching 1.2m deep by 0.5m wide was required to allow pipe-laying, but the only route out of the compound was in the Root Protection Area (RPA) of large oak, an important group of TPO trees.

Norfolk Wildlife Services worked with Anglian Water and Conroys to create an Arboricultural Method Statement [AMS].   An innovative solution  practical  technology –  a suction excavator [Conroy Vac Ex] – to prevent need to cut roots with ground protection techniques to protect tree roots of the protected trees from vehicle damage.

The suction excavator removes the soil around the roots, eliminating the need to cut through them in order to create the trench.  Major roots were left intact which means the trees ability to take up water and nutrients was not compromised.  Exposed roots were wrapped with wet hessian to prevent desiccation.  The pipe was then laid underneath the routes and the trench was then backfilled with the original soil, minimising disruption to the trees’ water supply in a period of dry weather.

Ground protection techniques help prevent compaction of the soil around the tree roots

 

Work begins on suction excavation of trench around tree roots using Conroy Vac Ex

Work with Conroy Vac Ex suction excavator continues on open trench and tree roots

 

Wet hessian bags were wrapped around the roots to avoid desiccation.

 

Pipe laying commences

 

 

 

Great crested newt mitigation and translocation

When should I think about great crested newt mitigation ?

If you are planning on developing a site and have had an ecological survey to assess impacts to wildlife read on. The results of this survey have identified potential impacts on great crested newts in and around the proposed development area.  You need to start thinking about mitigation for great crested newts at this point. For example you may need to create new habitats offsite to offset any damage on site.

What happens if there are great crested newts in an area for proposed development?

You must apply for a European Protected Species Mitigation (EPSM) licence from Natural England (NE). There is no charge by NE for EPSM licenses, however, the development must pass three legal tests. The activity must be for a purpose of public interest (for example, for providing housing ). There must be no satisfactory alternative that will cause less harm to the species. The activity must not harm the long-term conservation status of the species.

Planning permission for any development of the proposed site should be granted prior to applying for an EPSM licence. Once a licence has been applied for, you can usually expect a licensing decision within 30 days, but NE is currently assessing a large volume of applications.

A mitigation strategy forms part of the licence application. This both safeguards the great crested newt population before and after works and prevents harm to the individual animals. There will be a legally binding Method Statement which will include methods e.g. for translocation to remove individual newts, and a timetable.  Although these can be varied if something unexpected happens, not complying with the licence is a legal offence, so they need to be well thought through.

Translocation

Sometimes it is not possible to retain newt populations within a development site. In this case they will need to be moved – known as “translocation” or trapping out.  Translocation of Great Crested Newts will always involve a licence application to Natural England.

In the application Natural England will want to see that :

– The translocation site is as near as possible to the original site. In general over a mile would be unacceptable to them except in exceptional circumstances.  This is because the mitigation needs to maintain the populations at a local level, but also due to the risks of spreading chytrid and other amphibian diseases across the countryside.

– Any ponds removed or adversely affected will be replaced, preferably at a least a 2:1 ratio, . This is based on the presumption that not all ponds will be successful for newts.  Sometimes enhancement of existing ponds is possible e.g. old overgrown ponds now unsuitable for newts. SUDS ponds or balancing lagoons are not suitable.  The pond needs to be specifically for the species.

– There will need to be new habitat created or enhanced at least equal in area to that lost and/or of a higher quality. Examples might include arable land being replaced by grassland or improved grass leys replaced by scrub and woodland.

– In general you will need a survey to see if there are newts already at the translocation site. Translocating newts into ponds with existing populations is not acceptable, as there is no net gain for the species, since they just compete with newts already there.

– The management of the site will need to be guaranteed “in perpetuity” – normally by a Section 106 agreement with the landowner.  This is clearly less complex where the land is within the blue line of the development site owner or even with the red line.

Trapping a site out can be a lengthy process and take over a year allowing for licence application and seasons.  Trapping will normally be for 60 suitable days, but with additional requirements for breeding ponds. Suitable days are normally during spring and autumn, when temperatures are warm enough but not too dry for the newts to move around. When conditions are not suitable ( e.g. there is no rain for several days or it is too cold ), then trapping nights become “invalid” and the period of time needs to be extended.  Thus 60 trapping nights could in reality extend over an additional nights say or be caught short by the autumnal frost or a summer drought.

Planning law says that the local planning authority have to assess whether a European Protected Species for a site is likely to be granted by Natural England ( e.g. Morge versus Hants and more recently Elsworthy Farm judgement ) prior to granting permission.

How does the licence work when developing a site?

You need to keep a copy of the licence on site, and you may be inspected by Natural England to see if you are complying with it – they can request to see this copy.  Certain works will be carried out or supervised by your licenced ecologist, but there will be other responsibilities resting on the client. Make sure all contractors coming on site are inducted on it, and stick to what it says. At the end of the works, you need to make a licence return to prove that they have been carried out, and monitoring of any new ponds is necessary to give some measure of success.

For great crested newt legislation, see this post.