On 29 August 2017, three workers were carrying out preparatory work in a sewer for the Thames Tideway Tunnel at East Greenwich, which is controlled by Thames Water Utilities Limited (TWUL). A 150-year-old cast iron penstock failed, engulfing the workers and carrying them along the sewer.
The three workers suffered minor physical injuries but have been mentally affected. One worker has been treated for long-term traumatic stress because of the incident which has prevented him from continuing work in his specialised career.
Investigating, the HSE found that TWUL had planned individual work activities but failed to properly coordinate these as the permission and authorisation system was fragmented. The company had no effective means of collating, comparing and adapting to the impact of multiple work activities.
Due to an unrelated planned power outage, sewage pumps vital to the control of sewage levels for the work being undertaken at East Greenwich were not available for use which resulted in the failure.
Thames Water Utilities Limited of Clearwater Court, Reading, Berkshire, pleaded guilty to breaching Regulation 3(1)(b) of the Confined Spaces Regulations 1997 and was fined £300,000 with costs of £16,419.
Drowning in sewage
Speaking after the hearing, HSE Inspector James Goldfinch said: “This serious incident endangered the lives of three workers and caused lasting adverse mental health effects; the workers narrowly avoided death by drowning in sewage.
“It should serve as a warning and a reminder to all those that work in confined spaces that work in these challenging environments must be properly planned, coordinated and managed.”
A spokesperson for Thames Water said: “We very much regret what happened as the safety of all our employees, partners and customers is at the heart of how we do business. Following the incident, we offered as much support as we could to those affected and launched a full investigation to establish what went wrong and why, to reduce the risk of it ever happening again.
“As a result of that investigation, we’ve worked with the HSE and our contract partners to share our learning and introduce the water industry’s first Independent Authorising Body, which now has oversight and control of all entries into our sewer network. We’ve also strengthened our policies and procedures on confined space working and are using more technology to reduce the need for people to enter our sewers.”
In the statement, Thames Water added that it had five iron penstock gates closed and all diverting wastewater away from the works area before the failure of the asset which led to the sewage flooding.
The company also stated that it recorded a 32% reduction in injuries leading to absence from work this year.
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