Considerately modernising a Severn Trent water treatment plant in the Peak District – MWH Treatment Ltd
MWH Treatment is a strategic consulting, technical engineering and construction services firm, leading the water-related infrastructure sector.
Its Bakewell Severn Trent Water (STW) project, carried out in close partnership with client Severn Trent Water, involved the extensive refurbishment of a water treatment plant in Bakewell, Derbyshire.
This project involved the construction of a new pocket Activated Sludge Plant (ASP), two final settlement tanks and a new wash water system. The 60-week project, valued at £5m, also entailed the construction of a new sludge handling facility, as well as water inlet modifications.
MWH Treatment Site Manager, Philip Dunn said:
“The new scheme replaces the existing works to provide a more compact up-to-date treatment process for the local community and the environment. On a lot of our sites we have a very low public interface level due to the location being tucked away out of sight.
“We aim to have high public engagement where possible, to keep people updated on progress and any high levels of vehicle movements, which could cause a level of disruption. This is achieved by letter drops, council meetings if required, and by generally engaging with locals in conversation, adopting an open door policy at all times.”
The biggest challenge the team faced on the project was the sheer volume of groundwater which had to be removed and controlled as a result of the various deep excavations carried out.
“This has to be managed so as not to cause any flooding or pollution to the local area. The solution was to use some existing redundant structures on site as settling lagoons. This enabled any silt particles to settle out prior to pumping into an existing culvert, which eventually made its way to the River Wye – a river of great natural beauty.
“We investigated ground water levels prior to the job commencing on site and liaised with the Environment Agency at an early stage to explain our proposal and discuss various options and solutions. We agreed on a final solution and the operations ran without a problem, ensuring the project was a great success. We were pumping approximately 60 litres of water a second 24 hours-a-day, seven days-a-week for approximately 300 days. This equates to well over one billion litres of water in total.”
Respecting the community and protecting the beautiful environment within the Peak District National Park was a major consideration for MWH Treatment Ltd during these major works.
“We take our duty of care to the local population and the environment very seriously and we spend a lot of time planning and preparing robust solutions. Throughout the construction phase, we had the challenge of access into the new tanks and structures for all of our tradesmen.
“Ladders are a last resort, so we built in low-level access ways. This enabled operatives to walk between cells without going up and over the 5m high walls which greatly reduces the risk level. We also have the issue of self-rescue from the closed deep structures; we do not rely on the emergency services to facilitate our entire rescue situations as this would possibly leave us vulnerable to an injured person being isolated for too long. We run emergency rescue drills to prove our competence as required.”
Another challenge the site team faced was access to the site; the only way in was over a narrow stone bridge with a 40t weight limit.
You can find out how the MWH Treatment Ltd project team addressed this challenge and carried out best practice initiatives by clicking on the sliders below:
- With the only route of access over a narrow stone bridge with a 40t weight limit, this affected a lot of the construction methods the team employed as only certain sized cranes and lorries could comply with the weight and width restrictions. This in turn dictated the size and slope angles of excavations, as well as reach limits for the cranes and concrete pumps and so on.
- Pre-start information was sent to the local town council and three properties and farms within the nearby vicinity.
- Support to the local area was very good and the use of ‘improve it’ cards enabled subcontractors to make improvement suggestions; for every card submitted, the company donated £1 and this was match-funded by the subcontractor for the benefit of local causes.
- The site team also re-ditched a local field and opened up culverts along the approach road to improve public access.
- The site location will return to its natural state upon project completion, with the final effluent waste plant benefitting the entire local area which is serviced by the plant.
- Although community involvement was limited due to the remote location of the works, local residents were personally visited by Philip Dunn and updated on works progress.
- There was a high water table in the area, particularly at the works site, so various pumps were in use 24-hours a day, with pumping of the water being a major part of the finished scheme.
- An ecology survey was carried out at the start, with no concerns noted. Clean water which had been filtered through the water table was then pumped into the River Wye, which runs alongside the site.
- There was an excellent incident response and procedures in place as a result of training which took place, supplemented by spill response drills.
- Only nominated staff were allowed to refuel plant and equipment.
- Working methods were very well planned due to the logistical issues resulting from the restricted entry over a humpbacked bridge.
- On completion of the project, rare plant species were introduced around the Final Settlement Tank (FST), to further enhance this beautiful area.
- Access is exceptional, from the lodge to the car park where cars are asked to reverse park to the pedestrian access to site, with various crossing points, all protected by pedestrian barriers.
- The construction of the cells for the ASP restricted escape routes, so the site created a system and carried out rescue drills, using the wall walkway and self-rescue Davitt arm and winch system between cells under construction.
- Cycling awareness posters were displayed at the entrance, with FORS and CLOCS promoted to the supply chain.
- There was an on-site company trainee manager displaying the company’s commitment to new people in the industry.
- Piped filtered water was available in the canteen and in reception cabins.
- Workforce healthcare support, similar to BUPA/AXA was made available and covered counselling, financial advice, confidence building and stress management.
- The company was trialling pre-enrolment which also included compliance and the right to work in the UK, as part of its commitment to reducing illegal workers.
- Wi-Fi was available on site.