Around 40 homes in Cwmtillery were evacuated late in the night on Sunday, 24th November following a landslide on a disused coal tip. This occurred during the devastating effects of Storm Bert. Residents were supported by the Council during the evacuation and the days afterwards and were advised they could return their homes five days later on Friday 29th November.
Debris carried by a flow of water had slid from the edge of the coal tip (not the main part of the tip) down to the road below, entering a small number of properties, some gardens and causing damage to infrastructure. A strong water issue had developed due to the weather conditions experienced during Storm Bert and had saturated an area of the tip dislodging the material and causing it to slip.
Our immediate priority was finding the source of this water flow. Once this was identified, a programme of work was quickly developed to rectify this, which involved capturing the water flow and diverting it into an existing offsite drainage system. Contractors were on site early the very next morning to start this work.
Residents were only advised they could return to their homes after the drainage solution was established to be successful and working, with rainfall experienced since it has been in place.
Contractors remain on site carrying out the last of this work and this will continue until Saturday evening (December 7th). Reprofiling works have also been undertaken to the area of slip material and the immediate slip area. The reprofiled slopes will be covered by geojute matting to provide protection to the bare material.
The work carried out on this particular issue has removed the immediate risk. Moving forward we will work with Welsh Government and partners to access additional expertise and funding from the coal tip safety grant to deliver significant capital investment to secure the long-term stability and resilience of the tip to protect the communities of Cwmtillery. Work has already started to ensure delivery with detailed topographical, drainage and site investigation surveys in the planning.
We are looking to have an independent assessment into the work we have carried out to date by an external consultant to provide further reassurance.
We continue to monitor the site closely. This will include twice daily visits during periods of heavy rainfall. The Coal Authority/Mining Remediation have also agreed to inspect the site weekly.
Local Authority staff and contractors have also carried out a thorough clean-up of the affected streets, removing material and washing the streets affected.
We have been working in close partnership throughout this incident with the Welsh Government and the Coal Authority/Mining Remediation Authority,
The affected coal tip in Cwmtillery is a Category D coal tip. This means a tip with the 鈥榩otential鈥� to impact public safety which is to be inspected at least twice a year. In response to the Tylorstown landslide in 2020, the Welsh and UK Governments set up a joint Coal Tip Safety Taskforce. This was set up to assess the immediate status of disused coal tips in Wales.
The Welsh Government provides information on its website about Category C and D tips and their locations. An inspection schedule was put in place by Welsh Government as part of their work and tips categorised D require twice yearly inspections.
The last inspection at Cwmtillery was in August this year (2024). This identified no major issues. Some minor seepage was observed on the main section of the tip, not in the area where the landslide occurred. The landslide was on the edge of a separate section of the tip. The seepage observed is being captured by mitigation measures (i.e enhanced drainage) which was put in place earlier this year. This continues to work well.
There were potential indicators for 鈥榮hallow creep鈥� which refers to the surface of the tip only. This is not uncommon and is a longstanding feature of the site. Importantly, no ground movement was detected on any section of the tip at the time of the last inspection.