The Town and Country Planning (Environment Impact Assessment) Regulations 2017: EIA Screening Opinion - letter from Oliver Rendell to Tanya Ruseva

The purpose of the proposed development is to stabilise the banks either side of the C13 road at Dinahs Hollow to prevent a major land slip and improve safety of the public highway.

The proposed works would occupy an area of approximately 2.1ha.

The slopes would be stabilised using soil nailing techniques. 

The works would firstly involve removing the vegetation in the works area, including some trees, and installing drainage at the top of the slopes, within the slopes and on the highway.

The soil nails would then be installed to reinforce the stability of the slope.

The soil nails would be faced with a flexible facing comprising a high strength mesh to support the soil between nail locations and prevent any local loss of material. Erosion protection matting is also proposed to be installed underneath the mesh.

Low level exposed aggregate concrete panels and kerbs would be installed at the toes of the slopes to prevent damage to the slopes from vehicles.
The slopes would be replanted by either hydro-seeded to promote vegetation growth on retained soils and/or allowed to regenerate naturally from retained seed banks.

The development site would include a site compound and access track.

There is a requirement to consider the cumulative effects of the development in accordance with Paragraph 1b of Schedule 3 of the EIA Regulations. The impacts of the proposed development will be considered in combination with the existing and approved development in the areas surrounding the site, including development at Shaftesbury to the north of the proposed development.

The greatest potential for nuisance during the construction phase of the development is likely to be as a result of noise and dust, typical of construction works. These impacts are considered short term and temporary, and the implementation of best practice construction methods is considered likely to reduce the potential impact to the extent that significant impacts for the purposes of EIA are considered unlikely. During the operational phase, the nature of the development is such that there will be no emissions generated. As such, there are not anticipated to be any significant nuisance or pollution effects, for the purposes of the EIA. 

The use of standard best practice construction methods relating to working on the slopes and the highway is considered sufficient in preventing a significant risk of accidents during the works for development of this scale and type, for the purposes of EIA.
 
 

The site comprises the C13 public highway and adjacent slopes at Dinahs Hollow, Melbury Abbas approximately 1.8km to the south of Shaftesbury.

The C13 runs in a deep hollow at this location, with sleep slopes on either side of the road. The average slope gradient is approximately 50 degrees from the horizontal at the mid-slope and in general steeper at the toe of the slope. The maximum heights of the slopes are approximately 14m to the west and 10m to the east. The slopes are densely vegetated and include a large number of trees.

The areas immediately surrounding the development site are largely rural and undeveloped. There is a small vineyard located adjacent to the west at the southern end of the hollow. There are buildings adjacent to the south and north of the site.

The EIA regulations define ‘sensitive areas’ in Regulation 2(1). An Environmental Impact Assessment is more likely to be required if the proposed development affects the features for which the sensitive area was designated.

The proposed development is situated within a sensitive area, as the site is within the Cranborne Chase & West Wiltshire Downs National Landscape.

The sensitive areas surrounding the site include the Fontmell & Melbury Downs Special Area of Conservation (SAC) and Sites of Special Scientific Interest (SSSI) approximately 390m to the south of the site and the following Scheduled Monuments:

• “Cross dyke and linear boundary on Melbury Hill and Compton Down” located approximately 690m to the south; and
• “Melbury Beacon and circular enclosure on Melbury Hill” located approximately 980km to the southeast of the site

Environmental designations which are not defined as ‘sensitive areas’ but are nevertheless important in determining whether or not EIA is required include:

• Sites of Nature Conservation Interest (SNCI) including:
  • Melbury Abbas SNCI approximately 180m to the east; and
  • Melbury Hill approximately 400m to the southwest of the site
• Grade II* Listed ‘Church of St Thomas, approximately 200m to the south of the site
   

The Planning Practice Guidance on Environmental Impact Assessment (‘the guidance’) provides an indicative threshold above which development is more likely to require EIA and an indication of the key issues to consider for each development type. This can be used to help determine whether EIA is necessary.

As previously explained, the proposed development does not fall neatly within a description of development in Schedules 1 or 2 of the EIA regulations, but perhaps the proposed development falls most closely within paragraphs 10(b) and 10(f) of Schedule 2 as an urban development project within a rural area involving roads. 

The indicative thresholds and key issues advice may be less relevant in this instance given that the proposals don’t fall easily within a development type. 
However, the guidance indicates that EIA is more likely to be required for schemes of greater than 5ha or that have a significant urbanising effect, or for roads of over 2km in length.

The key issues for development of these types which are relevant in this instance are the physical scale of the development, noise and emissions, increases in traffic, visual intrusion (including impacts upon the setting of heritage assets) and the impact on the surrounding ecology. The characteristics of impact associated with these key issues are considered below.

Size

The indicative thresholds, above which EIA is more likely to be required, are schemes of greater than 5ha in area, those that have a significant urbanising effect, or roads of over 2km in length. The proposed scheme would occupy approximately 2ha, significantly below the 5ha threshold, and once complete, the stabilisation works would not result in a significant urbanising effect as the land would be replanted or allowed to regenerate naturally. The scheme does not involve the establishment of new road, but the section of road in question is approximately 550m in length, substantially under the 2km threshold.

Emissions and noise

As noted in section 1 of this letter, the greatest potential for noise is during the construction phase of the development. There will be some emissions associated with the use of machinery. These impacts are considered short term and temporary, and the implementation of standard construction methods is considered likely to reduce the potential impact to the extent that significant impacts for the purposes of EIA are considered unlikely. 
During the operational phase of the proposed development, there will be no noise or emissions generated.

Traffic

The C13 public highway will be closed for a period to allow for the works to take place. A simple diversion, perhaps using West Lane and Mill Hollow Lane, would ensure that traffic is relatively unaffected during the construction phase of the works. The operational phase of the works is likely to protect the road from landslips, allowing the road to remain open.

Landscape and visual

The proposed development is within the Cranborne Chase National Landscape, a sensitive area according to the EIA regulations. 

Dinah’s Hollow is one of several historic holloways in the Lower Greensand. The significance of holloways in the north Dorset landscape has been identified in the Cranborne Chase and West Wiltshire Downs National Landscape (Formerly AONB) Landscape Character Assessment. It is within the Chalk Escarpment Character area which is characterised as ‘hanging woodland and sunken lanes are features of the steep, enclosing chalk combes’.

The Landscape and Ecology Report (
‘Landscape and Ecology Report Dinah’s Hollow Melbury Abbas for Dorset Council Highways Version 1’, prepared by Danny Alder Ecology and Conservation and Tony Harris Landscape and Ecological Design and Management, August 2024) indicates that the nearby views of the site are limited due to the undulating landform and linear belts of mature trees, and longer range views are of the scheme will have a limited, minor impact on the overall panorama.

However, there are 6 viewpoints which are considered to have a moderate adverse impact or greater. These impacts are likely to temporary, albeit over a period of 5-10 years post-construction, when the ground flora, coppiced and pollarded trees regenerate and the new planting areas mature. This will reduce the impacts on the wider landscape by integrating the scheme into the surrounding landscape.

Other mitigation in the Landscape and Ecology Report will also help to soften, naturalise and therefore integrate the slopes into the surrounding landscape.

There are undoubtably landscape and visual impacts which will need to be addressed through the planning process. However, it is concluded that the proposed development will not result in significant landscape and visual impacts for the purposes of EIA considering the impact upon the National Landscape sensitive area, restricted to the Holloway, the temporary nature of this impact, and the proposed landscape mitigation.

Heritage assets

The Scheduled Monuments, considered sensitive areas by the EIA regulations, in the areas surrounding the site include the “Cross dyke and linear boundary on Melbury Hill and Compton Down” located approximately 690m to the south and “Melbury Beacon and circular enclosure on Melbury Hill” located approximately 980km to the southeast of the site.

In addition, the Grade II* Listed ‘Church of St Thomas’, is located approximately 200m to the south of the site. Whilst not a sensitive area, it is nevertheless a key heritage asset in the area surrounding the site.

According to the Landscape and Ecology Report, views of the site from the south where the heritage assets are located will be changed by the scheme. This will potentially result in a Medium to High magnitude of change in the view resulting in a Moderate to Substantial Adverse level of landscape effect. However, this impact is temporary, and will gradually reduce to a Slight Adverse landscape effect in the longer term as the vegetation regenerates and grows. These changes will not be as substantial when viewed from the Scheduled Monuments, and to a degree the Grade II* listed church, given that these assets are located a substantial distance to the south and the overall character of the surrounding areas is unlikely to be significantly altered to the extent that the experience of these assets is suignificantly effected.

Ecology

The Fontmell & Melbury Downs SAC and SSSI, a sensitive area according to the EIA regulations, is located approximately 390m to the south of the site.
Fontmell & Melbury Downs SAC and SSSI is characterised by unimproved chalk grassland with scrubland facies, and supports species including Early Gentian Gentianella anglica. The principal pressures and threats to the site include air pollution and land management (inappropriate scrub control, agricultural practices in the surrounding areas, grazing on the site).

The proposed development will not result in changes in air quality and will not amend land management practices at or in areas adjacent to the Fontmell & Melbury Downs SAC and SSSI, and therefore there is no viable pathway between the proposal and an impact upon the designated site.

The local wildlife sites in the areas surrounding the site include the Melbury Abbas SNCI approximately 180m to the east, which is characterised by neutral grassland and wetland, and Melbury Hill SNCI approximately 400m to the southwest of the site, which is a thin strip of chalk grassland. The proposed stabilisation works is considered unlikely to significantly impact upon these grassland and wetland habitats.

The Ecological surveys have indicated that protected species, including dormice and bats, are present at the site. The Ecological Mitigation suggested in the Landscape and Ecology Report , in addition to other regimes such as Licencing, will prevent a significant effect upon protected species.

Conclusion

Following consideration of the relevant selection criteria for screening Schedule 2 development presented in Schedule 3 of the EIA regulations, the Planning Authority conclude that the proposed development is unlikely to result in significant environmental impacts. Therefore, in exercise of the powers conferred on it by Regulation 6(6) of the EIA Regulations and based on the information submitted, the Planning Authority hereby adopts an EIA screening opinion that an EIA is not required in this instance. 

If you have any questions about the information submitted in this letter, please do not hesitate to contact me.

Yours sincerely

Oliver Rendle

Planning and Community Services
County Hall, Colliton Park, Dorchester, Dorset, DT1 1XJ