Penrhiwceiber Colliery Weir

Penrhiwceiber Colliery or as it was known Penrikyber was sunk between 1872 and 1879. By 1896 there were 1,463 men employed there and by 1908 this had grown to 1,787. Figures like this show the importance of the coal industry to employment at that time. This was even though accidents and other dangers to those working under ground such as gas were common place. At its peak 2,236 men were employed and it produced 350,000 Tons of coal. It closed in October 1985.

On this site a very large weir had, since the shutting of the old colliery, broken away from both banks creating substantial erosion on east and west banks with the possibility, if not removed of undermining them completely.

It was not easily accessed so exploratory work to try to cut the concrete up with power tools and disc cutters and portable hydraulic hammer proved unsuccessful and it was decided to use a large track machine with a hydraulic pecker.

Access was difficult and over land with knotweed prominent on both sides, however consultation with Rhondda Cynon Taf Biodiversity Officer on how to eliminate the spread of the knotweed by following suggested procedures allowed us to proceed.

The river had formed a deep hole on the downstream side of the weir this was caused by large floods flowing over the top and the scour action they caused. We had to stabilise the river bed and to do this the hole had to be filled in. This was done by using the large broken sections from the weir as a base and some dry large river shoal that was available on site.

When breaking up the weir we came across some amazing reinforcement material from metal bars to twisted wire and in the final section a whole car engine, waste not want not was a slogan used in those far off days that we could practice more today. On completion the river was regraded, the banks reinforced.

Successive floods have done the final grading, and erosion of the banks has now stopped.

Whilst this weir was regarded as passable at all flows, the main benefits of the work are; improved channel diversity, river connectivity, reduced build-up of debris, reduced bank erosion particularly towards the railway line. It has also scoured and cleaned the gravels downstream of the site improving conditions for spawning fish. No mean feat on a recovering industrial river.