Assessment of Cumulative Effects

The cumulative effects of the project have been assessed in accordance with the EIA Regulations and guidance contained in DMRB Volume 11.

Cumulative impacts result from multiple actions on receptors and resources over time and can be additive or interactive in nature. They can also be considered as impacts which result in incremental changes caused by other projects in the past, present or reasonably-foreseeable future.

“Reasonably-foreseeable” is interpreted in the DMRB guidance as projects that are “committed”. There are two types of cumulative effects:

• Those arising from a single project due to the interaction of a number of different environmental topics and impacting upon a single receptor/resource;
• Those arising as a result of the combined action of a number of different projects in combination with the project being assessed on a single receptor/resource. This could include multiple impacts of the same type from various projects on the same receptor/resource.

Determination of significance of cumulative effects is based on the extent that the receptor/resource is able to accommodate them. The determination takes into account:

• the nature of the receptor/resource;
• how the activity or activities will affect the condition of the resource;
• what the probabilities of such effects occurring are; and
• how able the receptor/resource is to absorb further impacts before irreversible changes occur.

Assessment of cumulative effects arising from the combined action of a number of different projects is summarised in Table 9.1. This includes those arising from this particular project and the combined effects from other current or reasonably foreseeable projects in the vicinity of the proposed works.

Works have been carried out on upgrading electricity cables and pylons near Allt Lagain Bhain (see Figure 9.1). However, there could still be some site works associated with upgrading the electricity power lines adjacent to the A887 Allt Lagain Bhain Bridge. Consequently, there could be construction-related cumulative impacts in combination with the A887 Allt Lagain Bhain Bridge Replacement scheme.

Expansion of the Marine Harvest Inchmore Fish Hatchery, located adjacent to the A887 west of Lagain Bhain Bridge, is currently being carried out (2016).

Planning permission (Ref. 13/01878/FUL) was obtained in 2013 for retaining a road to provide permanent access from land north west of Torgoyle Lodge to the A887. This road includes three crossings of the Allt Lagain Bhain, the nearest of which is approximately 350 m upstream of the A887 bridge. It is believed that at least part of this road follows the line of the Beauly Denny access road used for upgrade of the electricity power cables.

Outline planning permission (Ref. 05/01053/OUTIN) was given in 2007 for two dwelling houses near Allt Lagain Bhain upstream of the A887 Bridge. Access was to be from the existing field onto the A887 and this is in close proximity to the scheme. However, the Highland Council Planning Portal website does not indicate that full planning permission was given. No houses have been built at this location. If access was to be gained to the A887, it is understood that this would require approval from Transport Scotland.

Works have been undertaken by BEAR Scotland in 2016 to slightly widen a single track section of the A887 (within the trunk road boundary) between Torgolye Bridge and Allt na h-Innse Beag approximately 0.6 km south of the proposed scheme. Minor culvert and ditch clearance maintenance works were also proposed in 2016, further west from Allt na h-Innse Beag, approximately 1.2 km south-west of the proposed scheme. None of these works are likely to cause construction-related cumulative effects, since they are complete or are likely to be complete by the time the proposed scheme (A887 Allt Lagain Bhain Bridge replacement scheme) commences. No significant construction or operational impacts were identified for the widening or ditch clearance works. Consequently, it is considered that there will be no significant cumulative operational impacts in combination with the proposed scheme.

 

The only other foreseeable larger Transport Scotland project in the vicinity of the works is the replacement of the Allt na h-Innse Beag Bridge located approximately 1 km to the west. Construction is likely to be staggered with that of the proposed scheme (A887 Allt Lagain Bhain Bridge) to avoid cumulative effects to vehicular travellers and local residents although it is possible that construction could be concurrent with the proposed scheme. In the latter case, careful consideration should be given to the traffic management arrangement to mitigate the effects of two schemes within approximately 1 km.

Table 9.1 Assessment of cumulative effects from combined action of a number of different projects

Mitigation numbers refer to Item Nos. in Table 11.1

Air Quality

Resource Value or Sensitivity - High

Construction: No residential receptors within 200 m; expansion of Inchmore Fish Hatchery and minor maintenance works likely to be complete before the proposed scheme (A887 Allt Lagain Bhain) commences. Proposed scheme is far enough away from Allt na h-Innse Beag not to affect receptors there.

Operation: No change and no significant effects are predicted from the proposed scheme (A887 Allt Lagain Bhain) during operation.

Mitigation: 1, 2, 76-79, 82, 86-90, 92

Significance of Cumulative Effect: Not significant.

Cultural Heritage

Resource Value or Sensitivity - High

Construction and Operation: Effect from the proposed scheme (A887 Allt Lagain Bhain), however no further significant effect anticipated from Allt na h-Innse Beag or minor maintenance works. Based on the Historic Environment Scotland PastMap website, it is considered unlikely that the Inchmore Fish Hatchery expansion scheme will have significant effects on recorded sites of cultural heritage significance although potential effects on unrecorded remains are not known.

Mitigation: 1, 2, 3-8

Significance of Cumulative Effect: Not significant.

Ecology and Nature Conservation

(refer to Chapter 6)

Resource Value or Sensitivity - Very high

Construction: Effect from the proposed scheme (A887 Allt Lagain Bhain). The Allt na h-Innse Beag watercourse also flows into River Moriston so there is potential for effect. The fish hatchery expansion is adjacent to the River Moriston and there is potential for effects from this scheme, for example there is a risk of pollution during construction.

Operation: During operation of the proposed scheme (A887 Allt Lagain Bhain), there are predicted to be no significant effects. If there is an abstraction and/or discharge for the Inchmore Fish Hatchery expansion scheme, this will be regulated by SEPA under the CAR regime. Consequently, potential effects on the River Moriston are anticipated to be appropriately controlled. Therefore, no significant in-combination operational phase effects are predicted from the proposed scheme (A887 Allt Lagain Bhain), A887 Allt na h-Innse Beag and the Inchmore Fish Hatchery expansion.

Mitigation: 1, 2, 9-42

Significance of Cumulative Effect: 

Significant: Moderate during construction if construction phases for both Allt na h-Innse Beag and the proposed scheme are simultaneous. (If the proposed scheme works and Allt na h-Innse Beag coincide with any works on the nearby electricity power cables, the effect is not predicted to be any greater than Moderate.)

Not significant: Slight if construction staggered. The hatchery expansion project is expected to be complete by construction date for Allt Lagain Bhain.

Landscape Effects

Resource Value or Sensitivity - Low

Construction and Operation: Potential for both bridge replacement projects to create a local impact if not reinstated properly. Planting schemes could affect ecology either in a positive or negative way depending on species chosen.

Inchmore Fish Hatchery is well-screened by trees in summer but not in winter.

Mitigation: 1, 2, 43-49

Significance of Cumulative Effect: 

Not significant: Slight

(If any of the proposed scheme works and Alt na h-Innse Beag coincide with works on the electricity cables, the cumulative effect is not anticipated to be any greater than Slight.)

Land Use

Resource Value or Sensitivity - Low

No cumulative effect predicted.

Mitigation: 48, 49

Significance of Cumulative Effect: Not Significant.

Noise and Vibration

Resource Value or Sensitivity - Medium

Construction: No residential receptors within 200 m; expansion of Inchmore Fish Hatchery and minor maintenance works likely to be complete before the proposed scheme (A887 Allt Lagain Bhain) commences. Far enough away from A887 Allt na h-Innse Beag Bridge not to affect receptors there.

Operation: No change and no significant effects are predicted from the proposed scheme (A887 Allt Lagain Bhain) during operation.

Mitigation: 86-92

Significance of Cumulative Effect: Not Significant.

Pedestrians, Equestrians, Cyclists and Community Effects

(see Item 93 in Table 11.1)

Resource Value or Sensitivity - High

Construction: No cumulative impact in combination with the Inchmore Fish Hatchery expansion is anticipated. If the proposed scheme (A887 Allt Lagain Bhain) and A887 Allt na h-Innse Beag construction phases are staggered, no cumulative impact is predicted.

Operation: The proposed scheme (A887 Allt Lagain Bhain) will have no significant effects. No anticipated impacts from the fish hatchery expansion and minor maintenance works once these schemes are completed.

Mitigation: 93-94

Significance of Cumulative Effect:

Not significant: Temporary disruption during construction. Unlikely to be a cumulative effect unless A887 Allt na h-Innse Beag is constructed at the same time, in which case cumulative impact is assessed as Slight. (If any of the proposed scheme works and Alt na h-Innse Beag coincide with works on the electricity cables, the cumulative effect is not anticipated to be any greater than Slight.)

Vehicle Travellers

(see Item 93 in Table 11.1)

Resource Value or Sensitivity - Medium

Construction: Timing of construction for both bridges likely to be staggered. Fish hatchery expansion and minor maintenance works likely to be complete before construction of A887 Allt Lagain Bhain.

Operation: Overall beneficial impact on completion. No significant adverse impacts are predicted for the proposed scheme (A887 Allt Lagain Bhain).

Mitigation: 93-94

Significance of Cumulative Effect:

Not significant. If works are not staggered, there will be a cumulative impact considered to be Slight.

(If any of the proposed scheme works and Alt na h-Innse Beag coincide with works on the electricity cables, the cumulative effect is not anticipated to be any greater than Slight.)

Road Drainage and the Water Environment

(refer to Chapter 8)

Resource Value or Sensitivity - High

Construction: Potential cumulative impacts along with A887 Allt na h-Innse Beag. The Inchmore Fish Hatchery expansion project is expected to be complete by construction date for the proposed scheme (A887 Allt Lagain Bhain).

Mitigation: 1, 2, 50-75

Significance of Cumulative Effect:

Significant: Moderate during construction if construction phases for the proposed scheme (A887 Allt Lagain Bhain Bridge Replacement) and A887 Allt na h-Innse Beag Bridge Replacement are simultaneous. (If the proposed scheme works and Allt na h-Innse Beag coincide with any works on the nearby electricity power cables, the effect is not predicted to be any greater than Moderate.)

Not significant: Slight if staggered.

Geology and Soils

Resource Value or Sensitivity - Low

Construction and Operation: None predicted

Mitigation: 48, 49

Significance of Cumulative Effect: Not significant

 

Effects arising from the proposed scheme (A887 Allt Lagain Bhain) owing to the interaction of different environmental topics on a single receptor or resource are discussed in the following paragraphs.

There will be an interaction between cultural heritage and landscape in terms of effects on the old masonry bridge. Chapter 5 (Cultural Heritage) identifies a residual effect of Moderate significance as a result of the loss the old masonry bridge whilst Chapter 7 (Landscape Effects) identified a residual effect of Moderate significance. However, it is not considered that there would be an additional significant cumulative effect when these effects from these two topic areas are taken together.

The loss of woodland trees will entail an effect in terms of ecology and landscape.  Chapter 6 (Ecology and Nature Conservation) identifies the residual effect on woodland on the Ancient Woodland Inventory as significant at a County scale.   Chapter 7 (Landscape Effects) identifies the effect on woodland from a landscape perspective as of Slight significance during the first year after construction and Neutral significance by 15 years.  In this case, the main effect is considered to be ecological as from a landscape perspective, the planted trees will in time bring the landscape back to a similar quality. Consequently, there is considered to be no significant additional cumulative effect.

There is predicted to be a residual effect of Moderate significance on Allt Lagain Bhain in Chapter 8 (Road Drainage and the Water Environment). Chapter 6 (Ecology and Nature Conservation) assesses the potential effects on aquatic species such as Atlantic salmon but the effect on Allt Lagain Bain itself is covered in Chapter 8. There is not considered to be an additional cumulative effect as Chapter 8 inherently takes account of potential effects on aquatic ecology.

Overall, there will be moderate cumulative effects in relation to ecology and the water environment. These will be reduced, as far as practicable, through mitigation measures, as detailed in Chapter 11 (Schedule of Environmental Commitments) of this ES. With the implementation of these mitigation measures, the residual cumulative effects are predicted to still be of Moderate significance. However, if the proposed scheme and A887 Allt na h-Innse Beag scheme construction phases are staggered, the cumulative effects are predicted to be of Slight significance.