Frequently Asked Questions
We have collated a list of commonly asked questions and the respective answers.
What is a 1 in 200 year flood event
It is often believed that a 1 in 200 year flood refers to a flood event that would happen, on average, once every 200 years. In fact, the term refers to the probability of a flood event occurring in any one year. “1 in 200 years” actually means that, each year, there is a 0.5% chance of a flood of this magnitude happening. This percentage is calculated on the basis of 1 divided by 200 times 100, a recognised formula for the calculation of annual flood risk. The lower the percentage probability the larger and more damaging a flood will be.
Would dredging reduce the risk of flooding?
Dredging has been considered and shown to offer only very limited benefit to reducing flood water levels in the rivers and burns. This activity is not a sustainable solution given the need to frequently re-dredge the watercourses. In the non tidal sections of the rivers and burns the additional capacity that would be generated by dredging is minimal in comparison to the volumes of water in an extreme flood, hence why it has so little benefit.
Who is funding the scheme?
The FPS process involves submitting an application for funding from the Scottish Government once the Scheme is confirmed. Funding grants of 80 percent of the eligible costs are available from the Scottish Government for confirmed schemes which meet specific technical,environmental and economic criteria. Falkirk Council and others would then fund the remaining 20 percent of the total cost.
Why can't the pumping stations deal with the flooding?
Most of the existing pumping stations in the Grangemouth area are Scottish Water Pumping Stations, which predominantly deal with foul water rather than surface water. The existing pumping stations would not be able to cope with the predicted flows for a 1 in 200-year event.
Does the scheme only protect the refinery
The scheme is not only protecting the refinery. The primary purpose of the scheme is to protect almost 3,000 homes and businesses in Grangemouth and surrounding areas from flooding from the River Carron, River Avon, Grange Burn and the Forth Estuary. The refinery and petrochemical works as well as Grangemouth Port will also be protected given the national importance of the infrastructure to Scotland and the UK economy. In addition, not protecting these areas would leave those resiential properties nearest the Forth Estuary at risk of coastal flooding given the land is low lying.
Will the flood defences be maintained after they are built?
The Flood Risk Management (Scotland) Act 2009 places duties on Falkirk Council to inspect and maintain the defences. They will therefore be kept in good condition and repair and to do so an operational and maintenance procedure will be developed and implemented
When will the scheme be built?
The project team are currently finalising the outline design. This will determine the type of flood defence e.g. wall or embankment and the likely form of construction as well as the height of defence and its location. Thereafter the team aim to publish the scheme in late 2021. If all goes to plan and all approvals are granted it is hoped that the main construction works would commence in 2024 with construction potentially being stretched over 10 years.
Will the views of the public be sought on the proposed defences?
To date the project team have held two separate public consultation events in 2018 and 2019 seeking feedback on the proposed scheme. In addition there has been consultation with elected councillors, community councils, statutory consultees and many others. The response to these consultation events are reflected in the proposed scheme. Further consultation was planned in 2020 and has been re-scheduled to early 2021. This engagement will continue throughout the development and implementation of the scheme.
Will the defences stop all future flooding
No, there always remains a risk with every Flood Protection Scheme that
there will be a storm event which delivers a flood bigger than the Scheme is
designed to protect against. The scheme is being designed to protect against flood events that have a 0.5% chance of occuring in any year.
How do flood gates work?
Flood gates are located in specific areas throughout the Scheme, where access through the new flood defences must be maintained. Flood gates are useful where constructing a ramp over the flood defence wall is not feasible and at existing bridges, where the bridge
cannot be raised to accommodate the new flood defence level. Falkirk Council will liaise with SEPA to determine the likely flood level and close the flood gates in preparation for a flood event.
What are flood cells?
The project team have divided the scheme into 6 discreet flood cells which are simply geographic areas. This has been done to make it simpler to refer to these specific areas and present statistics etc. The six cells are: Cell 1 - Upper Carron; Cell 2 - Lower Carron; Cell 3 - Port of Grangemouth; Cell 4 - Grange Burn and Flood Relief Channel; Cell 5 - River Avon; Cell 6 - Estuary Frontage.
Are all the trees in Zetland Park being removed?
No. Trees are only being removed where there is no alternative due to the damage their roots would sustain if they were left in place. Almost 90% of the trees within Zetland Park will be unaffected by the proposed flood defences.
Aren’t you going to destroy some natural habitats for birds, water mammals, fish and aquatic life?
Protecting natural habitats and enjoyment of the waterways whilst constructing flood defences that will safeguard communities across parts of Falkirk and Grangemouth is of paramount importance to the scheme. We are committed to minimising the risk of impacting natural habits during the construction of the flood defences and once they are operational. We are undertaking an environmental impact assessment of all aspects of the scheme and will be proposing ways of mitigating any impact. This study will be conducted in 2020/2021 and be published in late 2021.
Are the Kelpies at risk from future flooding?
We have carried out a detailed assessment of both river and coastal flood risk as part of the scheme. Our assessment does not predict any flooding of the Kelpies either now or as a result of climate change.
Why is the scheme required when there hasn't been any recent flooding?
Falkirk Council are taking a proactive approach to managing flood risk and hopefully the scheme will be in place before a devastating flood event occurs. An absence of large floods in recent decades does not mean there is no risk. Due to the low lying land around Grangemouth the extent of flooding if it occured would be significant with thousands of homes and businesses at risk. There have been numerous instances over the last 10 years where watercourses have been very close to spilling out of their banks and flooding property.
What options have been considered to reduce the risk of flooding?
Various options have been considered to reduce the risk of flooding. These have included dredging, natural flood management e.g. run-off reduction by tree planting, a new flood relief channel, using the Carron Valley reservoirs for flood storage, construction of new flood storage reservoirs, linear flood defence walls and embankments, flow control structures and tidal barriers and gates. Further information can be found on the pages for consultation event no. 1 and consultation event no. 2. Several of the options considered were found to offer very limited benefit or were not practical to implement.
What is the source of flooding?
Grangemouth and the communities protected by this scheme are at risk of flooding from multiple sources.
Why are you not protecting the north bank of the River Carron at Skinflats and Bothkennar
This area was not identified in the Local Flood Risk Management Plan as being part of the Grangemouth Flood Protection Scheme. The area is covered by SEPA’s Flood Warning System, which does provide advanced warning of extreme tidal levels. These areas are subject to review by Falkirk Council’s Flood Risk Management team.