Draft Sectoral Marine Plans for Offshore Renewable Energy in Scottish Waters: Socio - Economic Assesment

B14. Waste Disposal

B14.1 Overview

This sector includes the disposal of material, dredged from ports, harbours and marinas, into the marine environment. This type of waste disposal is only allowed where the material cannot be used beneficially, for example to replenish beaches or in construction projects. Figure B14 shows an overview of tourist activity in relation to Draft Plan Option areas. Information sources used in the assessment are listed in Table B14.1.

Table B14.1 Information Sources

Scale	Information Available	Date	Source
UK	Dredge disposal sites and volumes disposed of in the OSPAR Maritime Area	2009	OSPAR, (2009): http://www.ospar.org/documents/dbase/publications/p00433_JAMP%20Dumping%20Assessment.pdf
Scotland	Potential future port developments	2009	National Planning Framework for Scotland (Scottish Government, 2009b).
Scotland	Locations and tonnage at open disposal sites	2011	Baxter et al. (2011)

B14.2 Future Trends

The Scottish National Planning Framework 2 (Scottish Government, 2009b) identified future port developments, which may require dredging, including the development of ports and sites in the Inner Moray Firth. A strategy prepared by the Highland Council highlighted Cromarty Firth, which provides service base facilities and sheltered moorings for offshore Oil and Gas industry, and the potential of Nigg as a facility for decommissioning Oil and Gas installations and the manufacture and support services required by the renewable energy industry. In addition, the NRIP identified Nigg, Aberdeen, Ardersier, Peterhead and Wick as sites in this region which may support the offshore wind and/or wave and tidal industries. Infrastructure development at these sites may require dredging, for example, the NRIP identified potential dredging requirements to fulfil infrastructure requirements at Ardersier (dredging of sand would be required for the outer channel) and Aberdeen (widening of entrance channel to accommodate large vessels) (Scottish Enterprise and Scottish Highlands and Islands Enterprise, 2010b).

B14.3 Potential for Interaction

Table B14.2 shows potential interaction pathways between waste disposal and wind, wave and/or tidal arrays.

Explanation of column content:

Column 1: Describes the potential interaction between the activity and any renewable technology;

Column 2: Identifies the types of offshore renewable development (wind, wave or tidal) for which the interaction may arise;

Column 3: Identifies the potential socio-economic consequence associated with the interaction identified in Column 1;

Column 4: Indicates whether detailed assessment will or will not be required if activity is scoped in;

Column 5: Identifies how the socio-economic impact will be assessed.

Table B14.2 Potential for Interaction

1	2	3	4	5
Potential Interaction	Technology Relevance (Wind, Wave, Tidal)	Potential Socio-economic Consequence	Scoped in (√) or Out (X) of Assessment	How the Economic Impact Will be Assessed
Loss or reduced use of dredge material disposal sites	All arrays, export cables	Increased costs of disposal	√	See Section B14.4
Access to dredged material disposal grounds	All arrays	Increased cost of disposal (vessel steaming times)	√	See Section B14.4

B14.4 Scoping Methodology

B14.4.1 Loss or Reduced Use of Dredge Material Disposal Sites

Potential negative impacts on waste disposal may occur through the loss or reduced use of dredge material disposal sites causing increased disposal costs as a direct result of displacement by arrays. For the purposes of this assessment, this potential negative effect is only considered to be significant for Draft Plan Option areas in which arrays are likely to occupy more than 5% (Wind and Tidal) or 1% (Wave) of the Draft Plan Option areas. Using this assumption:

• Draft Plan Option areas which do not overlap with dredge disposal sites or Draft Plan Option areas which overlap with dredge disposal sites but where the arrays only occupy <5% of the Draft Plan Option areas were scoped out of the assessment.
• Draft Plan Option areas which overlap with dredge disposal sites and where the arrays occupy >5% of Draft Plan Option area were considered to require a more detailed assessment. Cable routes which traverse disposal sites were also scoped into the assessment.

The output of this scoping exercise is presented in Appendix C14.

B14.4.2 Access to Dredged Material Disposal Grounds

Potential negative impacts on waste disposal may also occur through arrays increasing the cost of disposal through the disruption of access to disposal sites (increasing fuel and staff costs). For the purposes of this assessment, this potential negative effect was considered only likely to occur where Draft Plan Option areas lie inshore of dredged material disposal sites. Using this assumption:

• Draft Plan Option areas which are offshore from dredge disposal sites were scoped out the assessment; and
• Draft Plan Option areas which lie directly inshore of disposal sites were considered to require a more detailed assessment.

The output of this scoping exercise is presented in Appendix C14.

B14.5 Assessment Methodology

B14.5.1 Loss or Reduced Use of Dredge Material Disposal Sites

Data on the amounts disposed at current disposal sites is available. However, no information is available on turnover or GVA associated with this activity. A quantitative estimate has therefore been derived that evaluates the additional steaming cost involved to use an alternative disposal site in response to the loss of reduced use of a nearby site. This quantitative assessment has been applied as a proxy for potential impact on GVA of nearby ports, harbours and marinas should a nearby disposal site be closed.

The additional steaming cost is derived from the additional distance travelled by vessels to get to an alternative disposal in relation to the fuel cost required to make the journey. The additional steaming distance is calculated as the difference in distance between the original theoretical route from the port to the disposal site and modified route to an alternative disposal site. The fuel cost is in turn based on an assumed fuel consumption rate, based on the typical average vessel fuel consumption per day of a dredging vessel.

Using the additional steaming distance and fuel price, the costs associated with the deviation and additional steaming distance was calculated where the additional cost of steaming time was calculated as:

Current route (distance in nautical miles) compared to additional steaming distance (nautical miles) x fuel costs per nautical mile. The calculation uses an assumed average vessel speed to arrive at fuel consumption per vessel movement. To then infer the annual cost, the journey fuel consumption was multiplied by the anticipated number of transits in one year.

Currently there is still uncertainty surrounding the routes which cables will be laid. This makes any assessment of economic impacts difficult. However, given that disposal sites generally only cover small areas, a large degree of overlap occurring between a cable route and aquaculture site is unlikely. In addition, it is assumed that cable routes will generally be able to be modified slightly to avoid disposal sites. Loss or reduced use of dredge material disposal sites due to cable routes has therefore not been assessed in more detail as part of this study.

B14.5.2 Access to Dredged Material Disposal Grounds

For sites which lie directly inshore of disposal sites an estimation of the additional steaming cost associated with the vessel deviation has also been completed. The assessment follows the same methodology described for the loss or reduced use of dredge material disposal sites impact described above.

The results of the above assessment are presented in Appendix C14.