A complex flood alleviation project completed on time, on budget and with the highest standards of health and safety. It is possible.
Thames Water’s £4m Haydon End project in Swindon to reduce the risk of flooding in the Haydon Wick area of the town was completed last December. Swindon has suffered regular and some major flooding, notably in 2007 when the town saw some of the worst flooding in its history, with homes sinking under two feet of water. Now the project is finished, the likelihood of flooding in this area has been reduced to once in 30 years.
It took seven months to complete the construction of two tanks at Haydon End, a job undertaken by Optimise joint venture partner J Murphy & Sons. The company is a long standing member of the British Safety Council and a multi-site winner of the International Safety Awards in 2014.
Optimise, which also comprises Barhale Construction, Clancy Docwra and MWH, has been contracted to undertake other major capital works on the network infrastructure for both clean and waste water, covering the Thames Valley and north London regions with an estimated value of £500m over five years. It will continue replacing London’s worn-out Victorian water mains, upgrading sewers to protect customers’ homes from sewer flooding and installing monitoring equipment (SCADA). This is just one of the flood alleviation projects undertaken by or on behalf of Thames Water to prevent a repetition of the 2007 floods.
A risky project
To achieve the objective of reducing the risk of flooding it has been necessary to increase the storage capacity of the sewer network. This scheme will also allow for future housing development in the Haydon End area. Colin Joyce, the site manager, notes the complexity of the work and the need for efficiency in a project that was finalised in record time and without any safety incident.
“The purpose of the two tanks is to help alleviate flooding. The principle is quite simple, when the SCADA equipment detects that the sewerage system is overloaded with the potential to cause flooding, the two tanks are used to hold the ‘overfill’. When the sensor detects that the risk of flooding has subsided, the pumps kick back in and return the content of the tanks back into the sewerage drainage system. The likelihood of flooding in this area, once the tanks have been constructed and completed, is very remote. The pumps are likely to be in action only a few times a year.”
The construction work
Colin described the difficulties of the task: “Here at the south site we were going 18 rings deep – that is 18 metres deep. What we built was essentially a vertical tunnel. Normally we did a complete ring every two days. We spent a day digging and another day hanging and grouting the ring. The site is small and tight and there is a limit on how much material can be stored on site. There was very little space in fact.”
He continues: “It’s hot down there. We had an air mover to help working conditions, but the ground conditions here are excellent, you could not ask for better. We made sure that the team stayed covered up to protect them from the sun during the summer months.
“The deeper we got, the more challenges we faced. It takes longer to remove and lift the excavated soil out of the hole and longer to lift the rings and grouting in”.
Biggest risks and hazards
David McCulloch, J Murphy Group’s health and safety manager, explained that the biggest risk faced by the team on the project was confined spaces, which required a range of measures including a ‘permit to entry’ system, a two-way means of access (ordinarily the workers are lowered in to the tunnel by a cage suspended from a crane; there had to be an emergency means of escape in the event of the crane failing and in this case there were ladders), and the monitoring and recording of the atmosphere in the tunnel.
The measures to control the risk of falls from height include an exclusion zone, fall arrest netting and top segment edge protection. The risk of hand arm vibration was controlled through a range of measures including PPE, job rotation, low vibration tools and a high standard of tool maintenance.
Approximately 35 people worked on the project, with an average of 10 and up to a maximum of 18 operatives on site at any given time and there were around 15 subcontractors from different firms over the duration of the project.
David continues: “The team on the project was hand-picked and were directly employed by J Murphy & Sons. This is the fourth sewer shaft we have worked on over the last 12 months and we will be starting our fifth in 2015. The team members are instinctive in the way they work. Although not an employee of the Murphy Group, the crane driver is a regular in our projects and works well with the team. Trust in each other is essential.”
David describes the various mechanisms used on site to maintain a strong and lasting focus on health and safety. “We start each day with a briefing with all members of the team where we review what is happening. We use a range of mechanisms to discuss health and safety issues including toolbox talks, stand downs, alert briefings, open space forums, our safety committee, team briefs and our newsletter.”
Engaging with the community is essential on this large-scale project. Colin explains that the residents were concerned about the noise of the pumps. “The reality is that once the manhole covers of the pump stations are on you will not hear the whirring of the pumps. Residents were also worried that the tanks could overfill and flood the local area. The designers and engineers calculate that the tanks have sufficient spare in-built capacity to make this likelihood remote.
Health and safety vision
David explains that the company vision is built on a health and safety culture that ensures everyone goes home safely.
“The health, safety and welfare of everyone who works for us is of paramount importance and we recognise that achieving excellence in the management of health and safety is an overall part of our business success. Our health and safety policy applies to all employees, partners or contractors working for or on behalf of Optimise.”
Optimise’s vision is summed up by the philosophy they want every one of their workers to identify with and proclaim: ‘I want to work here’.
J Murphy & Sons’ experience in bigger projects was also paramount in the safe completion of the project. Its activities are underpinned by the structured management of one of the construction’s industry’s largest permanent workforces – 3,951 people directly employed at the end of 2013.
The company places great belief in long-lasting business and employee relationships. “Our structure provides unrivalled stability to our employees. Our portfolio of top-level supply chain partners delivers suitable support by operating, when required, as part of the Murphy family,” says David.
Key to J Murphy’s success (the business generated a turnover of £954m in 2013, with a pre-tax profit of £35m), is the company’s focus on its people, its clients and understanding and planning for the future. The company ethos is, “safety has to be paramount in all that we plan and do, across all the market sectors with which Murphy is involved. We keep our people, our clients and the public safe, which in turn ensures the safe delivery of projects,” David explains.
He considers that essential to success is investing in people – keeping their welfare and safety in mind, sharing knowledge and best practice and constantly improving internal processes.
J Murphy & Sons has a long and proud record of delivering iconic construction projects. In 2006 it secured the first major contract on the Olympic Park to construct major cable tunnels and associated sub-stations to allow the overhead power lines to be dismantled. This Olympic Park cable tunnel contract won the Association of Project Management’s project of the year in 2009. The Haydon End work in Swindon is another successful story added to their portfolio.
Neal Stone is acting chief executive and Joscelyne Shaw acting director of policy and communications at the British Safety Council
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