The Council has provided a progress update on the ongoing activity at the Tylorstown Landslip site, which continues to focus on the extended works in Phase Four of the Remediation Plan – with this work nearing completion. The contractor’s recent activity has largely centred round important drainage work.
The landslip on the Llanwonno hillside in February 2020 was triggered by the unprecedented rainfall in Storm Dennis. It blocked the river valley, broke a foul sewer, covered a water main with several metres of debris, and covered a shared footpath. A four-phase Remediation Plan has been implemented, with the project representing one of Wales’ flagship coal tip remediation schemes.
The first three phases of work included emergency clearance work in the weeks that followed the landslip (Phase One), embankment scour repairs (Phase Two), the removal of material from the valley floor to receptor sites and reinstatement of paths (Phase Three), and additional work to stabilise the slope (an extension of Phase Three).
Phase Four includes the remediation of the remaining tip on the hillside. The original drainage programme and the overall scope of this phase of work have been significantly extended, and is currently ongoing by contractor Prichard’s.
Current progress update - Phase four drainage work and other activity
Work is progressing towards the completion of Phase Four, after important progress has been made during 2026/27, particularly on the drainage activity.
The main spine drains that collect water from the reprofiled tip have been completed, while important attenuation work (to slow down the water flows before they are discharged to existing streams) is currently being progressed on site. The receptor site to the rear of the tip (near Old Smokey), where a large amount of the colliery spoil from the upper tip was transported, has been successfully regenerated. Ecologists have surveyed this area, and information on how revegetation has occurred is being awaited by the project team.
The contractor has brought specialist plant equipment to the work site to repair and maintain the channel outfall below a new cascade. This will future-proof the water run-off past the southern edge of the lower tip. Continuing soil nailing work (as pictured at Outfall A) represents the last major work at the bottom of the site, before the contractor works out and up the hill, towards establishing a maintenance track and reinstating the Public Right of Way.
Officers have recently visited to review the walking routes through the site, including the permanent Right of Way that has needed to be temporarily closed during the remediation work. This review process is ongoing. Current work is also ongoing to monitor the long-term management of the hillside – a process that will continue after the contractor has completed all works.
Meanwhile, a problem still exists with people illegally accessing the site with off-road vehicles. The tips have a network of drainage channels which are being damaged each time an off-road vehicle drives over them – which is extremely problematic in the management of water flows within this site. The contractor is reporting each and every incident to South Wales Police.
The overall completion date for Phase Four will depend upon the weather faced over the weeks and months ahead. The access track to the bottom of the site is long and steep, and the contractor’s progress may therefore be hampered if there is excessive rain or snow during the period ahead.
Councillor Andrew Morgan OBE, Rhondda Cynon Taf Council’s Cabinet Member for Environment and Capital Infrastructure, said: “The Tylorstown Landslip Remediation represents a huge operation, to firstly rectify the slip that occurred during Storm Dennis, and then to make safe the large remaining tip on the hillside. Central to the recent activity has been understanding the water movement on the site, and ensuring flows are channelled through and away in a safe manner. Drainage work in Phase Four has been significantly extended over the past two years, and is now entering its final stages.
“Inspecting, maintaining and repairing our former coal tip sites in Rhondda Cynon Taf remains a Council priority. We secured £13.7 million from Welsh Government’s Coal Tip Safety Grant this year, through which the Tylorstown Landslip Remediation continues to be funded. Our dedicated Coal Tip Safety Team administers a programme of work all year round using this funding. This does not include the £4.8 million funding commitment from the Coal Tip Safety Multi-year Grant Scheme, through which significant stabilisation work at Graigddu Tip in Dinas is taking place, having started on site this summer.
“At Tylorstown, alongside the hillside drainage activity, key work and consideration has progressed relating to the receptor sites, the temporarily closed Public Right of Way, and the future maintenance and monitoring of the area. Officers are also working with the police in relation to off-road vehicles that continue to access the site and cause damage to drainage infrastructure. As Phase Four nears completion, the Council will inform residents about the contractor’s concluding work, and the Council’s future activity beyond this.”
Find out more about the Council’s major investment in Highways and Engineering through our dedicated #TransformingRCT webpages.
Posted on 29/09/2026