Client Yorkshire Water has temporarily suspended work on construction of the $91.4m, 8.7km long Humbercare sewage tunnel project in Hull, UK, after a 15m section of the tunnel became distorted, causing sand, silt and water to seep in.
In a precautionary move, ten miners working in the tunnel at the time abandoned the TBM and evacuated the tunnel. No injuries occurred.
The 15m distorted section of the 3.6m diameter, reinforced concrete lined tunnel had been recently completed and was some 150m behind the TBM. Investigations were still under way as T&T International went to press to ascertain the cause of the incident.
The contractor, Miller Civil Engineering, initially stabilised the tunnel using compressed air to prevent the ingress of water and sands. Subsequently, the tunnel has been filled with water to maintain stabilisation while investigations continue.
No residential properties were affected by the subsidence, although police closed some surrounding streets until a full assessment had been made. Two water mains were damaged, which meant that some properties experienced some loss of pressure or supply.
The rest of the 8km length of tunnel has been examined and there is no evidence of distortion in any other areas.
The tunnel is an integral part of Yorkshire Water’s $330m wastewater treatment scheme.
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