Energy and Climate Change CommitteeWritten evidence submitted by Cardiff Council (SEV89)
Firstly thank you for affording Cardiff this additional time to submit evidence regarding the Hafron Power Severn Barrage proposals to the Energy and Climate Change Committee. It has been identified by both UK Government and Hafren Power that the proposals are incomplete, Hafren Power will release more information if they receive Government commitment to the scheme. This brief report cannot make any clear conclusions until further information on tide cycles, impoundment heights and turbine design are provided however, the following comments are provided on a best available information basis.
Key matters considered:
Climate Change objectives.
Flood risks and opportunities posed.
Ecological impact and opportunities.
Economic opportunities and impacts and Other tidal opportunities.
Community engagement.
Climate Change Objectives
It is widely recognised that the development of a Cardiff to Weston barrage traversing the Severn estuary could produce 5% of the UK energy requirements and would support the challenge to reduce carbon and greenhouse gas emissions by 80% by 2050. Clearly this is a significant single contribution to renewable clean energy resources, which is very welcomed, notwithstanding the carbon cost of this major construction which should not be underestimated.
Flood Risk & Opportunities
If the retained upstream tide height is increased, then: A longer period to reduce sea level during ebb condition would result in a longer tide-lock at Cardiff Barrage, hence re-modelling will be required. This may be mitigated by large pumps or an additional sluice may be needed to discharge flood storage during extreme conditions. In essence the permanent Severn Estuary retained level needs to accommodate highest river flows in Cardiff Bay and the retained level may result in a longer retention period of required flood storage in Cardiff Bay.
Evidence presented by Hafren Power indicates that the level of water above the proposed barrage may have a lower peak height but the retained period at a high level may be longer. It includes several options and therefore it is not possible to really identify the impact on the Cardiff Barrage at this stage of the project as there does not seem to be one fixed design with definitive water levels. However, clearly the Severn Barrage would offer an overall improved defence for eastern Cardiff, it is the interface with existing structures that is the question and how the higher retention level affects the Rhymney and it’s tributaries.
The designed water levels for the barrage will need to consider the impact on the Cardiff barrage so that the flood defence afforded by Cardiff Bay Barrage and established ecology are not compromised.
A Severn Barrage built between Lavernock and Weston (Brean Down) may result in a retained level of sea water that will impact on Cardiff Barrage and the Bay, therefore the retained level height is crucial to impact and opportunity. At the present time no firm information is available on how the Severn barrage will operate. A higher than current spring tide allowed upstream of Severn Barrage will have a High impact.
Cardiff also has concerns regarding the River Rhymney which is still a tidal river and therefore will be affected by raised tidal levels and the knock on effect that would potentially have have on Roath Brook and any increased river flow coming downstream during high rainfall events.
Increased ground water levels pose a risk that will require careful assessment to understand the impacts on the Internal Drainage Board (IDB) and the levels, Cardiff bay water quality—ecology impacts, impacts on the local farming community due to changing soil conditions and salinity, discharge levels, flooding risks and erosion of infrastructure and greater risk of over topping in eastern Cardiff.
Other concerns would be regarding coastal erosion and whether or not this would increase with a higher level of water in the estuary. Also would the building of the barrage negate the predicted rise in sea levels due to climate change and hence add to the protection of the Wentlooge Levels or would the drainage of the land be affected would need to be assessed.
Navigation
Navigation through locks will not be affected with a retained level in the Severn Estuary provided retained level is greater than -0.5mAOD. Navigation through the locks could be quicker as the retained level increases between -0.5 and 4.0mAOD. Increased dredging may be needed due to increased deposition of silt in the lead-in channel to the outer harbour.
Environment & Ecology
If there is an increase in saline intrusion this could affect the ecology of the Cardiff Bay. It is not expected to affect the passage of fish through the existing Fish Pass, assuming fish are able to reach Cardiff Bay through the Severn Barrage.
Since impoundment, Cardiff Bay has been invaded by a wide range of nuisance or invasive species, this will need to be considered. Some of these were predicted, such as the Chironomids or Non-biting Midges. Although not an environmental problem as such, they caused a significant nuisance problem to residents and businesses, requiring large financial and technical input to resolve.
Impounding the Severn Estuary could lead to a slight reduction in salinity. This may be low enough to allow salt tolerant midge species to thrive. However, the operation of the Barrage may be such that any population would be washed out during each generating cycle. This will be clearer when more information is provided by Hafren Power. Equally flora species that help prevent coastal erosion may be removed due to changes in feeding habits by animals/birds or the increase salinity, so accelerating the issues above. Impacts on the current sites of special interest would require careful consideration their loss being heavily considered against other gains. There is a risk that flora species that help prevent coastal erosion may be rapidly eroded or removed due to changes in feeding habits by animals/birds or the increase salinity, so accelerating the coastal erosion issues we face, strengthening the sea wall will need to be a consideration for further infrastructure to accompany the barrage.
Economic Opportunities and Impacts and Other Tidal Opportunities
Hafren Power claim that the project will create 20,000 new jobs during construction phase, and 30,000 additional jobs which will be a vital a huge boost to regional employment as well as Cardiff’s local economy.
It will contribute towards vital energy resilience for British industry and for citizens and compliment Cardiff’s own growing energy agenda.
The components will need to be manufactured near the construction site. Port Talbot is earmarked by Hafren Power for this an investment that will create highly skilled jobs in the local economy.
If accompanied by a transport link it will bring Bristol, the South West and Cardiff much closer together, bringing major economic benefits to both cities abd the Esturine Region as well as supporting the Welsh City Region and Metro.
The barrage would position Cardiff as a world leader in green energy, attracting inward investment, public and private sector R & D, and tourists.
Water leisure use could increase significantly as there will be a large more protected water body available. Although the designs could include transport links it is understood these would need additional funding. If provided this could increase economic activity in the areas close to the barrage. The barrage would impact significantly on the Docks upstream of the barrage including Cardiff Docks as vessels would have to transit at least two locks.
However, Bristol and Associated British Ports see the project as damaging to Avonmouth port they put forward that it will result in 60% job losses at Avonmouth.
The barrage will rely on a massive public subsidy (in the shape of a guaranteed energy price). Some consider that a persuasive argument is that this public funding could be much better spent, for instance on a major housing retrofit project which would create local jobs, reduce energy bills (in particular for those in fuel poverty), drive innovation in localised energy production and reduce CO2 emissions.
Community Engagement
In additions there are other options to consider of smaller, less.
Capital intensive tidal lagoons could operate with much smaller and limited impact on local ecology, existing industry and ports and may be deliverable to faster timescales. Cardiff would wish governments to consider all opportunities. Given the challenges such a major infrastructure project would entail it is essential that all affected communities of the barrage are consulted widely, not just those that may have historical established forums, the project must establish strong and cooperative communications from the outset.
March 2013