Sandycroft and Pentre Drain Flood Remediation Works

The work will be completed in two phases:

The first phase is focused on improving the flow within these systems through clearance of blockages and accumulations of sediment and any other non-structural barriers to flow.

In the case of Sandycroft Drain (the open watercourse that flows from the Bridge Inn to the River Dee) this will see the clearance of debris, sediment accumulations and vegetation from approximately 400m of the open channel.

In the case of the Pentre Drain North (a piped watercourse that runs adjacent to the north side of Chester Road) this will involve the use of specialist vacuum tankers and associated machinery.

The second phase is subject to the findings of the initial works and will involve undertaking structural repairs to the Pentre Drain North culvert. This may involve replacing sections of large pipe and/or localised repairs or relining.

Where the need for such works is identified, we will speak with the individual landowners affected in advance to discuss detailed proposals.

The first phase of the works will commence in October 2024 and is expected to be completed before the end of January 2025. The nature of the works (such as working in watercourses) and the constraints that weather may place on progress, means that we cannot be more exact with our programme at this point.

Phase 2 will follow the first phase in the new year. The scale and nature of repairs needed during this phase is uncertain at this stage as will be directed by what is identified within phase 1. The project and the programme timescales will be updated once the scale of any works become clear.

The work is focused on two key lengths of main river watercourses, where it is expected that interventions will provide the greatest benefit and help improve the wider local drainage regime helping to manage flood risk. These are:

• Sandycroft Drain: This is the open watercourse that flows from the Bridge Inn adjacent to Station Road towards the River Dee. The works are concentrated on addressing channel capacity issues in the first 400m of this watercourse, from the Bridge Inn to the road crossing at Phoenix Street (North).
• Pentre Drain North: The length of culvert (piped watercourse) that runs adjacent to the north side of Chester Road from Glendale Avenue to where it connects to Sandycroft Drain (above) at the Bridge Inn.

Phase 1 will involve working within both watercourses. Phase 2 of the works is likely to be limited to only specific sections of Pentre Drain North. Where the need for such works is identified, we will speak with the individual landowners affected in advance to discuss detailed proposals.

For both phases, our Contractors will be working from a compound area on land adjacent to the Bridge Inn carpark off Station Road.

The Contractor who will be undertaking the works is William Hughes (Civil Engineering) Ltd.

Further updates will be provided on this webpage as the works progresses. The project team can be contacted directly with enquiries by emailing:

Sandycroftflood@naturalresourceswales.gov.uk .

Alternatively, you can phone Natural Resources Wales on 0300 065 3000 and leave details so that a member of the project team can contact you back by telephone.

Those residents and businesses directly impacted by the works have already been contacted by the project team. Alongside our Contractors we will continue to engage with these landowners on an individual basis to plan the works and ensure disruption is kept to a minimum. 

• Enquires related to non-main rivers, highway drainage and road gullies should be directed to Flintshire County Council via FloodRiskManagement@flintshire.gov.uk
• Enquiries related to sewer blockages and associated flooding should be directed to Dŵr Cymru Welsh Water. Please refer to Sewer blockages and flooding | Dŵr Cymru Welsh Water (dwrcymru.com)
• If you are unclear as to who you should contact about a concern then please contact the NRW Project Team as above and a member will be able to advise further.

The booklet in the link below explains about rights and responsibilities in relation to watercourses. The riparian owner ultimately has responsibility to manage and maintain any watercourse.

A guide to your rights and responsibilities of riverside ownership in Wales (naturalresources.wales)

Risk Management Authorities, have permissive powers to enter land and undertake certain works for the wider benefit of managing flood risk.

In the case of Natural Resources Wales, these powers extend to ‘Main Rivers’ and in the case of Flintshire County Council to ‘Ordinary Watercourses’. Recent maintenance activities undertaken by NRW included Pentre Drain South the ‘main river’ (adjacent to Chester Road).

NRW’s powers do not extend to allow us to undertake works on other local watercourses. The two authorities are working in cooperation to coordinate and communicate our future local maintenance plans and schedules. 

We can never stop all flooding. Floods are natural occurrences that happen during and following heavy and/or persistent rainfall. The Welsh Government National Strategy for Flood and Coastal Erosion Risk Management in Wales promotes a holistic approach to managing flooding, adopting a range of measures to reduce the risk of flooding, and increase resilience if flooding occurs. This includes hard-engineered defences with natural flood management implementation where appropriate, improved community resilience, accurate flood forecasting and warnings, efficient emergency response and citing development away from at risk areas.

The longer-term objective of NRW would be to complete an assessment of historic, current and future flood risk to the wider catchment area, review current practices and identify where improvements could be made. This falls outside of the project scope , but information obtained during this work would feed into such a wider review. This is included in NRW’s medium-term plan, but we are unable to provide a specific date on when this assessment will be carried out.  

NRW make decisions on the best way to tackle any increased flood risk on a site-specific basis based on evidence of how each river might respond to sediment removal.

The main river channels undergo annual maintenance in the form of weed cutting and vegetation management. Removal of blockages in the river channels is also done as needed. De-silting can be more effective in some locations than in others.

De-silting is considered alongside other options by NRW when assessing how to manage flood risk. In many circumstances de-silting is not a sustainable long-term or economical solution.

The nature of these watercourses within the built-up area is such that effective regular maintenance is technically challenging compared to more readily accessible open channels.

NRW’s local ‘Integrated Engineering’ and ‘Integrated Workforce’ teams are involved with the project team and our contractors to identify and put in place measures that  will ease future inspection and maintenance. A review of the current maintenance regime will be undertaken once more details of the systems is established.

Continued cooperation and collaboration with partner Risk Management Authorities; Flintshire County Council and Dŵr Cymru Welsh Water, as well as working with community representatives, will help shape and support future maintenance plans.

The works are focused on a localised site within the wider context of the Broughton Brook catchment. A characteristic of the catchment is that of historic development in the flatter low lying land (reclaimed tidal estuary) that borders the tidal River Dee to the north, with higher ground immediately south. The low-lying nature of the area, the associated lack of gradient and the influence of tide levels in the River Dee are all factors that can contribute to high water levels in local drainage systems. These systems have been heavily modified over time to try to improve drainage but as low gradient systems are susceptible to sediment accumulating due to lack of flow, periodically, intervention is required to avoid a loss of conveyance (flow) over time.

As part of the remediation work, NRW in partnership with Flintshire County Council (FCC) as the Highway Authority will be investigating the culverts system to establish the location and condition of any connections underneath Chester Road, which link Sandycroft Drain North and Sandycroft Drain South / Pentre Drain North and Pentre Drain South.

Where there is a need for remedial or clearance work we will discuss and progress options in conjunction with Flintshire County Council.  

The tidal door where Sandycroft Drain outfalls to the River Dee is a passive structure, it functions automatically based on a difference in water pressure either side of the door.

During times when the tide is high, the pressure on the door is greater than that coming from water upstream in the river, therefore the door remains closed and no water upstream can discharge, which is referred to as a ‘tide locked’ scenario. As the tide goes out, the pressure is greater on the upstream side of the door, meaning the door will open to allow water in the river channel to discharge into the River Dee. 

Sandbags are mainly used to protect groups of residents, for example by diverting the path of flowing water, and directing it towards gullies and manholes.

Unfortunately, NRW do not provide sandbags. If you live in a flood risk area and feel you would like to have a few sandbags at home to use in the event of a flood, you can buy sandbags from hardware or DIY stores. There are also other bespoke systems available to protect doorways and air bricks.

Further information can be found at Blue Pages (Blue Pages)

Welsh Government funding was confirmed for remediation works along Pentre Drain North and Sandycroft Drain in March 2024. In the interim period a Contractor has been appointed, the relevant environmental surveys have been undertaken and the relevant permits obtained to allow phase one of works to start in October.

Once complete these works are expected to provide significant improvements to the efficiency of the drainage networks in the area and to help manage flooding.

Queensferry Community Council is seeking flood wardens. This voluntary role involves working with Flintshire County Council and NRW to ensure their community is prepared for flooding.

The role involves:

• Ensuring members of the community have received direct flood warnings, understand what they mean and where to get further information.
• Helping to identify vulnerable people within the community who may need extra help.
• Reporting blocked drains, ditches, etc to the relevant authority.

Anyone wishing to become a flood warden in their area should contact:

dee@queensferrycommunitycouncil.gov.uk  or clerk@queensferrycommunitycouncil.gov.uk