Technical Notes 2025, Issue 199 - Etive Park Bishopbriggs – Localised Flooding on 15 July 2025 - EDC investigations & Stantec’s Climate Ready Park flooding review briefing note October 2025

The purpose of this Technical Note is to update Members on the findings of the Stantec’s Climate Ready Park flooding review briefing note issued in October 2025.

• On 15 July 2025 severe rainfall events occurred across parts of the East Dunbartonshire Council area, which put existing drainage infrastructure under significant pressure. This caused localised flooding, particularly in Bishopbriggs. No flood alert was given by the Scottish Environmental Protection Agency (SEPA) at the time.
• This intense rainfall event overwhelmed local sewers and the culverted watercourse. Flooding reports indicated flooding from a manhole located on Springfield Road on the Bishopbriggs Burn culvert, upstream of the newly installed overflow manhole. There were further reports of two properties internally, several gardens and roads flooded other local areas. However, flood water receded once there was capacity within these piped systems.
• From sources known it is noted that the rainfall event experienced on the 15th of July 2025 was a 1 in 20-year return period event. A "1 in 20-year flood event" refers to a flood that has a 5% chance of occurring in any given year, based on historical data and statistical analysis.
• On the 17th of July our specialist contractors visited to inspect manholes created as part of the scheme and found no visible evidence of blockages upstream or downstream within the culverted watercourse or overflow manhole. 

• Following the flood event the Council were in discussions with our design consultants Stantec who were involved in the design and hydraulic modelling of the Climate Ready Park. EDC commissioned a model and design review briefing note attached on Appendix 1. This should be read in conjunction with the findings in this Technical Note.
• The Council requested Stantec to revisit the pervious hydraulic model to ensure all relevant information was captured. This involved reviewing the model used for the project. Stantec advised the model used was the model used by AECOM for the surface water management plans by WSP in 2014 and the baseline model was further updated by Stantec for the use in this project.
• The Council undertook further on-site investigations in the catchment to develop confidence in the baseline model, this investigation work has been detailed in the baseline briefing report in Appendix 1 and where required incorporated into any modelling assessment. CCTV survey of the culvert, climate ready park and manhole inspections were taken as part of these investigations. 

• Stantec’s flooding review briefing note in Appendix 1 was provided on the 20 of October 2025 after all investigation works, discussions with officers were completed to reassess the baseline hydraulic model used for the Climate Ready Park.
• Review of the design model scenarios was undertaken to determine any modelling factors which may impact the design. Only minor changes were experienced however the design model did not predict any flooding in this area for the 1 in 200 years (A "1 in 200 year flood event" refers to a flood that has a 0.5% chance of occurring in any given year) with a 41% climate change uplift. (As per the initial design). 
• Having investigated various locations in the catchment which included for some minor changes in the hydraulic model our design consultants could not replicate the flooding observed on the 15 of July, deemed to be a 1 in 20-year rainfall event.
• The findings have determined that the Service have been unable to pinpoint the root cause of the event on the 15th of July, which could be a result of unique circumstances on this specific day.
• As there is no way to determine the root cause the working theory is that there may have been a partial blockage in the pipe system which was removed due to the volume and flow of the water on the day. However, our investigation surveys show no evidence of this after the rainfall event in July 25. 

• It should be noted that the Service were unable to obtain historical flow monitoring data from Scottish Water and await their response on obtaining this information. Having this information will allow modellers to validate the hydraulic model with actual flow and observed data in terms of model predicted flows. However, there are no guarantee this would increase the risk of flooding.  

• Since the event on the 15 of July there have been no reported flooding incidents here. There is evidence of flows overspilling from the Bishopbriggs Burn into the SUDs Basin during rainfall, however this is what the scheme is designed to do and continue to monitor this location. 
• The Council will work with the designers to obtain additional historical flow monitoring data from Scottish Water when available however if this cannot be obtained new flow monitoring may be required to best allow modellers to verify the hydraulic model with actual flow and observed data in terms of model predicted flows. However, there are no guarantee this will replicate what was experienced on the 15 of July.
• Scottish Water have been contacted regarding their combined sewer overflow, and we await their response to upgrade this CSO overspill into the Bishopbriggs Burn, now we have constructed the Climate Ready Park SUDs Basin.  

• After the internal flooding of the two properties in July 2015 in Bishopbriggs details for Scottish Flood Forum was provided to those affected. It would be up to the homeowners as are the first line of defence for flooding and it is worth considering installing the recommended PLP.  For residents that have not had a survey, Scottish Flood Forums can be contacted via the link below to arrange a free consultation to PLP. 

• The Council is developing Surface Water Management Plans for Bearsden, Bishopbriggs and Milngavie under the Flood Risk Management (Scotland) Act 2009 (FRM). The Council will be working with Scottish Water to understand the mechanisms of flooding in these areas. The project team will propose and assess options to improve the management of surface water to minimise flood risk from surface water and sewer infrastructure.

• EDC Contact Centre 0300123510
• Scottish Water 0800 0778778 or contact them via email help@scottishwater.co.uk
• Scottish Flood Forum can be contacted via email.  An independent organisation which supports individuals and communities at risk of flooding and are able to help residents with insurance claims, drying out their home and seeking alternative accommodation. They also advise on appropriate property level protection.
• Visit our flooding webpage.