Mystery deepens at Cwmfelin sinkhole as engineers uncover hidden tramway channel
The update comes from Cllr Peter Black, who said work at the former Cwmfelin Social Club has now exposed the culvert and cleared the first blockage. But instead of flowing cleanly through the system, water is diverting into a huge, fractured brick tramway running alongside it before dropping back into the culvert “further down the line”.
According to Cllr Black, the exact point where the water re‑enters the culvert is still unknown.
Engineers have uncovered a broken brick tramway arch beneath the Cwmfelin sinkhole, where most of the water is now flowing.(Image: Peter Black)A damaged brick tunnel revealed by the dig shows water spilling through collapsed sections of the old drainage system. (Image: Peter Black)
Fears over collapse risk
Cllr Black warned that the tramway route could become blocked if another collapse occurs inside the structure, which already has a break where water is spilling back into the culvert.
Because of that risk, he said pumps will remain on site “until such time that the council are content that the risk of flooding has been removed”.
The discovery adds yet another layer of complexity to a problem that has plagued the area for years, causing repeated flooding around Cwmbwrla roundabout and forcing the demolition of the Cwmfelin Club building after it was left teetering on the edge of the sinkhole.
The culvert and surrounding structures exposed as contractors dig deeper into the Cwmfelin sinkhole. (Image: Peter Black)Heavy machinery at the Cwmfelin site as crews work to reach a second collapse hidden beneath the ground. (Image: Peter Black)Four‑month operation ahead
Cllr Black said contractors will now remove material from the site to allow phase two of the operation to begin. That includes excavating down to a second collapse, clearing it, and assessing the damaged section between the two failures before re‑establishing the watercourse.
He added that the council is currently negotiating an agreement with Network Rail to allow the next stage of work to proceed.
The projected timescale for the operation is “potentially up to four months”, with Cllr Black describing the next phase as “a lot more complex than the initial dig down”.
A wide view of the excavation pit where engineers are working to trace the diverted watercourse beneath Cwmfelin. (Image: Peter Black)The former Cwmfelin Social Club pictured before demolition, with the original sinkhole visible beneath the building before excavation work began.Meanwhile, he said the council will continue monitoring Cwmbwrla for flooding during periods of heavy rain.
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