Scottish Trunk Road Infrastructure Project Evaluation 1YA Evaluation Report for A9(T) Crubenmore Extension
Appendix B: Environment
This section provides details of the 1-year after evaluation undertaken for the Environment criterion in the Scottish Trunk Road Infrastructure Project Evaluation (STRIPE). The 1-year after evaluation includes a ‘high level’ assessment of the environmental impacts of the project (where possible), a review of whether the environmental mitigation measures proposed in the project’s Environmental Statement (ES) have been implemented (commenting on their success where possible) and a check of whether specific requirements of the appraisal process have been met.
The environmental mitigation measures originally proposed for A9 Crubenmore were obtained from the project’s ES. A review of the environmental mitigation measures was carried out in November 2013. Following this review a site visit was undertaken, on 13 November 2013, to establish whether or not the proposed mitigation measures as set out in the Schedule of Committed Mitigation within the ES had been implemented.
Noise and Vibration
The ES identified that a thin wearing course (low noise surface) was assumed for the project to reduce noise impacts for locally sensitive receptors. From the site visit undertaken it is unclear whether low noise surfacing has been utilised in the construction of the scheme, however further investigation confirmed that a low noise thin surface course was used.
Noise modelling carried out to inform the ES determined there would be a negligible change to the level of traffic noise following completion of the scheme. Therefore, no noise monitoring has been undertaken as part of this review to confirm whether noise levels experienced by any affected receptors on this section of A9 are higher or lower than those experienced prior to construction.
Similarly the ES concluded there would no adverse impacts due to groundbourne or airborne vibration at any of the receptors located within the project area. These criteria have therefore not been considered in this review.
Global and Local Air Quality
The ES determined that traffic flow or proportion of HGVs is not expected to change and concluded there would be negligible change in the concentration of pollutants to this section of A9 following completion of the scheme.
Given this, no mitigation measures to reduce the impact upon global or local air quality were identified outside the construction period.
Air quality was not assessed as part of this review.
Water Quality, Drainage and Flood Defence
There are a number of watercourses in and around the project area, including River Truim, part of a Special Area of Conservation (SAC) and Loch Etteridge, a designated Site of Special Scientific Interest (SSSI). Assessment undertaken as part of the ES determined that mitigation required for the operation of the scheme was to include the provision of filter drains running along the length of each carriageway. To improve the performance of the filter drains the new surface was to be built without kerbs to allow sheet flow from the carriageway.
Both these measures have been put in place as required. At the time of this review some sections of the filter drain were not in an acceptable condition. Along the northbound carriageway there were areas of weed growth (Figure 2). The ongoing maintenance of the filter drain is the responsibility of the current Trunk Road Operating Company and not the Contractor. There was also evidence of discarded road surface material in the filter drain which may be either a construction issue or maintenance issue (Figure 3). There were gaps in the filter drain along the southbound carriageway (Figure 4), and a comparison of the detailed design and as-built drawings would be required to determine whether this gap was intentional and, if it was not intentional, the implications should be considered of the potential impacts on nearby watercourses and the SAC if there is connectivity or in the effectiveness of the road drainage.
Catch pits and oil interceptors have been included at various locations as required.
An impermeable barrier to collect embankment and field drainage, to reduce drainage from a raised bog and prevent road run-off reaching the bog was also included in the mitigation measures required. Following a review at the detailed design stage, it was recognised that implementation of this would have impacts (flooding/ground saturation) to adjacent land and the impermeable barrier was therefore not constructed. The existing drainage regime is not considered to be adversely affected by the scheme design and it has been confirmed that road run-off will not impact on the area of bog in the opinion of the design team
Assessments undertaken as part of the ES determined that no mitigation measures were necessary for the operation of the scheme. No issues relating to geology were identified during the environmental mitigation measures review.
Biodiversity and Habitats
To mitigate against loss of nesting habitat in the long term, the ES contained a commitment to tree planting, woodland translocation and enhancement of adjacent habitat.
Tree planting has been carried out a number of locations along the northbound carriageway as shown in Figures 5 and 6. This has been undertaken at a suitable distance from the road verge. The source and type of trees was not confirmed during this review.
No tree planting was evidenced along the southbound carriageway, as per the ES, which advised against planting trees opposite existing woodland. This helps to prevent any future wildlife crossing opportunities being created.
The site visit identified that some mature trees were within the project area, indicating that they had been retained as per the proposed mitigation. However, it was not possible to determine whether mature trees had been removed (if any) without sight of any pre-construction tree survey reports or the scheme’s tree protection plans to enable a comparison of pre and post construction.
It is understood that a mycology specialist (Liz Holden of Mar Estates) was engaged in preparing the contract specification for translocation and mitigation for fungi, and that she also oversaw and monitored translocation activities on site during construction. The client has confirmed that she has been monitoring annually the success of the translocation activity for up to three years post construction. The monitoring programme concludes in 2014. During the site visit, fungi was present in places on the verge along the northbound carriageway.
The ES included a commitment for the contractor to collect and remove all construction litter. A degree of litter and debris was observed along both carriageways. A certain amount of this will most likely be windblown or left by road users. However, there was evidence of construction debris including discarded plastic road studs and a metal traffic sign frame. The Contractor has been made aware of this issue.
The road operator is to monitor the number and type of animal casualties in the first three to five years of operation. Four instances of road kill were identified during the site visit, one bird on the northbound carriageway, two birds on the northbound verge and a deer located on the central reserve. It is not known when these incidents of road kill had occurred, but it could be possible to compare pre-construction levels with post-construction levels if the road operator is collating comparable data for this particular section. See the landscape section below for information about the decision not to install the hedgerow that had been recommended in the ES to help minimise bird loss at this location.
Landscape & Visual Amenity
Mitigation measures recommended within the ES for landscape and visual effects include planting of additional vegetation adjacent to the A9 to replace areas of woodland removed during construction. As detailed in the section above, this measure has been implemented. As this review was carried out only one year on and during the winter period, much of these mitigation measures have not yet had time to mature.
The ES stated that verges, embankments and central reserve were to be sown with acid grassland mix. Whilst the verges and embankments have been seeded and grass can now be seen growing along both carriageways (Figure 7) the central reservation has been filled with stone chips (Figure 8). It is understood that the design change in relation to the stone chip was because grass central reservations have considerably greater maintenance requirements, such as cutting and weeding, than those which are stone chipped. These activities would require lane closures to allow them to be carried out safely. By using stone chips, the maintenance requirements are significantly reduced, along with the risks to road workers when working in the central reserve. Red stone chips have been used at strategic locations to emphasise the presence of the central reserve.
There are some areas, particularly along the southbound carriageway where the ground is covered in small rock. It is not clear whether this is discarded construction material but it creates patchy areas of grass which detract from the overall look of the landscape (Figure 9). It is expected that over time, the appearance of the verge will improve as the grass becomes more established.
According to the ES, a native hedgerow was to be planted to the south east of A9 to act as a physical barrier which would encourage birds to fly higher than most vehicles. During the detailed design stage, further consideration was given to this mitigation measure which concluded that it would not be in keeping with the landscape character at this location. It is understood that it was also considered to have minimal benefit to raising the height of low flying birds given its location at the toe of the adjacent trunk road embankment would be approximately two to three metres below road level.
Further mitigation required re-use of excavated topsoil to be placed in niches and ledges on the newly exposed rock face. This would allow naturally occurring seed within the soil to colonise the rock face over time. During the site visit it was not obvious that this had been completed. There were signs of grass growing on the rock, as shown in Figure 10, which indicates the presence of soil in the crevices but it cannot be established whether this is windblown or soil that has been deliberately used here.
Along the southbound carriageway the newly exposed rock face, in its current state, does not sit particularly well within the surrounding landscape (Figure 11). However, cutting into rock will inevitably create a more uncharacteristic visual aspect, which should soften over time as vegetation takes root and the rock weathers.
Overall the scheme works well within the wider landscape of the area, particularly along the northbound carriageway and down the embankment towards the cycle path (Figure 12). This area has successfully regenerated creating a naturalistic transition between verges, cycleway and woodland.
Agriculture and Soils
Assessments undertaken as part of the ES determined that no mitigation measures were necessary for the operation of the scheme. No issues relating to agriculture and soils were identified during the environmental mitigation measures review.
Assessments undertaken as part of the ES determined that no mitigation measures were necessary for the operation of the scheme. No issues relating to cultural heritage were identified during the environmental mitigation measures review.
Assessments undertaken as part of the ES determined that no mitigation measures were necessary for the operation of the scheme. The cycle path, part of National Cycle Route 7 (NCN7), has been retained and is currently in an acceptable condition, as shown in Figure 13. No other issues relating to physical fitness were identified during the environmental mitigation measures review.
Assessments undertaken as part of the ES determined that no mitigation measures were necessary for the operation of the scheme. The scheme area was mainly within the pre-existing A9 footprint, with only minimal additional land take, the impact of which was assessed to be neutral. No issues relating to land use were identified during the environmental mitigation measures review.
Assessments undertaken as part of the ES determined that no mitigation measures were necessary for the operation of the scheme. Mitigation undertaken during construction and reported in sections above include planting of vegetation, native trees and use of excavated topsoil on the exposed rock cutting. For vehicle travellers these measures, together with re-profiling of embankment cuttings, should improve ‘the view from the road’. This is expected to create a slight beneficial impact given the increase in distance and availability of views. No other issues relating to land use were identified during the environmental mitigation measures review.
Most of the mitigation measures included within the ES that are relevant during operation have been implemented and were seen to be in reasonable condition during the review. Two aspects that could not be confirmed during the site visit are understood not to have been implemented due to scheme changes at the detailed design stage: the impermeable barrier to collect embankment and field drainage, and the native hedgerow that was to be planted to encourage birds to fly higher than the height of traffic. These changes were considered by the design team not to have had a detrimental impact on the environment, or the general integration of the project into its surroundings.
The timing of the site visit, only one year on and during the winter period, does not necessarily allow for most of the landscaping and visual amenity measures to be observed at their best. It is expected over time that natural regeneration will allow further assimilation into the wider landscape and create a more naturalistic transition between the boundaries of the scheme and the surrounding environment.