Storm Dennis Recovery

In February 2020 Storm Dennis hit the UK with devastating effects for many. In Merthyr Tydfil over 200 properties were flooded and in the early hours of 16 February, an emergency situation was declared.

Our emergency control room was set up at the civic centre and rest centres were activated at Merthyr Tydfil and Aberfan leisure centres. Officers and Councillors were also deployed to those areas worst affected to help with the substantial clean-up operation.

In the subsequent days and weeks, financial support was offered by the local authority by way of a £500 Local Authority Hardship Scheme grant and Council Tax relief, and The Welsh Government Discretionary Assistance Fun (DAF) was made available to those affected.

We also offered practical help to those that needed it, including extra waste collections, free bulky item collections, advice on insurance claims and help with grant applications.
In May we wrote to flooded property owners with information on how to recover after a flood and how to prepare for the worst-case scenario of it happening again.

As a result of Storm Dennis a total of 47 repair schemes have been identified in Merthyr Tydfil, worth over an estimated £8.6m. We have requested funding from Welsh Government to cover these costs.

Due to the scale of the works we have devised a three-year completion plan split in to three phases, which have been prioritised based on the risk of future flooding:
• Phase 1 is currently underway with 5 schemes already completed and another 14 due to start in the next few weeks;
• Phase 2 will take place in 2021;
• Phase 3 will take place in 2022.

The Covid-19 Pandemic has inevitably meant that some of these plans have been delayed, however our officers are now working hard to complete as many schemes as possible before the winter months.

The recovery works vary in nature from:
• Culvert repairs
• Reinstatement of river embankments
• Installation of trash screens and flood monitors to various culverts
• Increasing the capacity of watercourses
• Scour protection of bridges
• Stabilisation work to landslip areas

Troedyrhiw
The village of Troedyrhiw suffered extensive flooding during the storms so MTCBC appointed a specialist consultant to carry out flood modelling, that centred around the Plymouth Feeder, to determine the cause.

The Analysis of the Plymouth Feeder indicated that flooding of Troedyrhiw occurred due to record high levels in the river Taff, which caused water to back up into the feeder. The feeder could not contain the volume of water during this 1 in a 200-year event and the water eventually overtopped the feeder embankment. The river Taff was therefore a significant driver in contributing to flooding in this area during Storm Dennis. Work on the Plymouth Feeder is planned to start in September 2020.

To the east of the village lies a 100-year-old culvert of stone construction, which we are proposing to replace along its entire length, and consultants Capita have been appointed to carry out the design and progress the scheme. The new culvert will be designed with additional capacity to accommodate climate change and to ensure it will be able to contain heavy rainfall from any future storms.

Landslides
Eight landslides occurred during the storms, all of which are complex in nature, so we have a specialist geotechnical company assessing each one to provide recommendations on the remedial work. Whilst the landslides were not related to any coal tip, we have also been working with the Coal Authority, who have provided assistance in inspecting almost 60 tips. The majority of the tip inspection reports indicate that only minor work is required to a small number of tips.

Monitoring Equipment
Flood monitors will be installed on high risk culverts, including the Plymouth Feeder, to assist us with future flood warnings.

Gulley Sucker
We are currently looking at the option of purchasing a Gulley Sucker.