Teamwork makes pumping station upgrade a 'resounding success'
When one of Northumbrian Water's largest wastewater treatment plants needed upgrading it was going to be fraught with possible problems, especially given the proximity of public amenities. Rigorous planning, strategic safeguards and smooth teamworking were vital to ensure this important project avoided disruption or disaster.
Special care must be taken during upgrade and maintenance work when temporary pumping equipment is deployed while the permanent plant is out of action. Unless adequate allowance is made for the flows, and a comprehensive pumping system is specified, the consequences could be disastrous.
With this in mind, contractor Byzak chose 14 Super Wispaset 300 pumps from Sykes Pumps to carry the load during a £3M civil engineering and M&E upgrade at the Old River Tees Pumping Station in Middlesbrough.
Andy Laundon, general manager for Byzak's Mechanical & Electrical Division, says: "Old River Tees, one of Northumbrian Water's largest pumping stations, has a capacity for dealing with flows up to 6,000l/s. It is located close to a large retail park with a bowling alley, cinema, bingo hall and various restaurants within 100m. This added to the sensitivity of this temporary over-pumping operation.
"It was imperative that over-pumping was carefully planned and executed in a professional and safe manner, minimising noise levels and reducing the risk of an environmental incident."
Fourteen pumps in total were used in the operation - two dry weather flow (DWF), nine storm and three standby. The DWF pumps discharged into the station from where flow was then pumped to Portrack sewage treatment works. The storm pumps were controlled using ultrasonic level sensing devices, and pumped storm flows into the new screening chamber.
The three standbys pumps were installed for providing critical back-up.
The whole operation was manually 24 hours a day with GSM modem back-up. Response time for emergency call-outs was reduced to two hours, in order to ensure prompt attention for any incidents at this critical site.
Sykes Pumps was engaged to assist with early planning and preparations for the work. The planning and delivery of this operation has been a team effort, involving Northumbrian Water, Byzak, Sykes Pumps and MWH.
On-site installation was carried in a safe and effective manner with significant contributions from all parties. The temporary system operated for five weeks without a single unplanned incident.
Brian Ford, Northumbrian Water project manager, says: "Temporary over-pumping of this scale takes a great deal of planning. The early involvement of all parties has led to this element of the project being a resounding success."
The pumping station, located on an old loop of the river downstream from the Tees Barrage, receives sewage generated in Stockton, Thornaby and Middlesbrough before transferring it across the river through rising mains located in a 700m tunnel.
Byzak, one of the framework contractors responsible for implementing Northumbrian Water's AMP4 capital delivery programme, is carried out the first major upgrade of the Old River Tees pumping station since its original construction in the 1970s.
The work included the reconstruction of the overflow chamber to accommodate new screens. New pumps were installed in the dry well, and various modifications were made to the two main wet wells. Byzak also upgraded the main control room.
The 14 pumps were used to over-pump flows to bypass part of the pumping station while the upgrade work was carried out. The temporary pumps were installed in early May and remained on site for seven weeks.
During this time, the pumps were expected to cope with stormwater flows in addition to the normal flow of sewage. Heavy rain can increase flows enormously, so, to accommodate this potential surge, the temporary pumping arrangement was designed to carry exceptional peak flows of up to 3,000l/s.
Because such a surge is very rare, most of the 14 Sykes pumps operated only occasionally - some weren't even deployed at all.
Two pumps controlled DWF, with only one required to operate continuously. The second was programmed to start up immediately should the first fail for any reason. Nine pumps were provided to manage the storm weather flows, with another three provided as standby units.
All the pumps, with the exception of the standby units were "super-silenced" to avoid disturbing people living and working nearby.
Byzak project manager Chris Thompson explains: "The pumping station is located near to Teesside Park, which is a retail and leisure park for the local community. There's no doubt that un-silenced pumps would have caused a disturbance."
To avoid such a situation, the pumps were subject to continuous monitoring and frequent inspection. "Sykes sends out a fitter each day to check the pumps. If there are storm flows, the fitter will remain to ensure the pumps run and he will give us a report on the condition of the pumps and diesel levels," adds Thompson.
Byzak staff attended the site at weekends to check pumps, hoses and fuel levels. When neither Sykes nor Byzak was on site, the site security guard carried out 30-minute checks to ensure that at least one dry weather flow pump was running and that incoming sewage was at a low level.
Any anomalies were relayed to Sykes, who remained on call at all times.
"The pumps are all electronically monitored and will alert us if there's any malfunction," says Sykes Pumps technical hire and sales representative Darren Watson. "When this happens, the pump sends a signal to a GMS telemetry unit which automatically dials three mobile phone numbers - two for us and one for Byzak."
To ensure continuous operation, the dry weather flow pumps were supplied with fuel from a 2,800l Sykes diesel storage tank containing sufficient fuel for ten days' continuous running.
The stormwater flow pumps, which did not run continuously, were topped up from a separate storage tank. "When these pumps are required, then the storage tank will be checked daily and filled up by our fuel supplier as required," says Thompson.
The contract was carried out under partnering principles involving a teamwork approach. Close liaison was maintained during all stages to ensure the uninterrupted operation of the station.
3D modelling was used to check the configuration and optimisation of pumps, valves, pipework and cabling layout.
This level of planning allowed Watson to strike an optimistic note during the refit: "If it stays dry, then only one or two of the pumps will be operating at any time. But if we have heavy rain then perhaps half or more of the pumps will be required."