Stonbury takes the heat out of UU reservoir project

Specialist contractor Stonbury has completed refurbishment of a 40Ml underground service reservoir located just outside Everton and serving Liverpool district. The work was carried out on behalf of United Utilities and took place under a five-year reservoir maintenance framework contract with the water company. Water for the 41-year-old reservoir is pumped in from Huntington water treatment works in Chester. The main driver for the project was water quality, which risked being compromised by heavy ingress from rainwater. The reservoir comprises two equal-sized compartments. The works was undertaken in two phases. Work on compartment one ran from April to September 2018 and on the second compartment from December 2018 to May 2019. External works to seal the roof were delivered first, to prevent rainwater from entering the roof structure. The ingress was caused by the deterioration of the joint sealant between the concrete panels, a common problem in tanks of this age. Outside of the work scope, one of the main challenges to the first compartment was the extremely warm weather experienced in the UK during the summer of 2018. United Utilities’ requirements for drinking water projects state that diesel-powered excavation equipment is not permitted onto the roofs of reservoirs, so all work is carried out manually. The site agent managing the delivery team took the decision that more rest breaks were required than usual. This substantially reduced the risk of fatigue and the possibility of a health and safety incident, allowing the operatives to manage the heavy work in high temperatures. A water cooler and a gazebo were also brought in to provide additional refreshment and shade on the roof. Externally, securing the roof from ingress was the priority, so the concrete roof panels were prepared first, using grinders, before being thoroughly cleaned. MasterSeal 933 was applied with brushes before the 300mm-width overbanding was rolled out along the 27 roof joints in each tank. All materials used internally were required to conform to the DWI Regulation 31 list of approved products for use in public water supply. A major requirement is control of the environment within the reservoir to meet the criteria detailed within the manufacturers’ instructions for use (IFU) documentation. Adherence to the IFU, and providing appropriate evidence, is critical for both the application and curing of sealing products. The inspection undertaken jointly by United Utilities and Stonbury identified that the existing bitumen joint sealant was past its service life. Therefore, MasterSeal 933 adhesive and MasterSeal 930 overbanding, were applied. The IFU stated that a minimum temperature of 7oC was required at all times within the reservoir during the application works. Initial discussions and budget costs identified that the size of the reservoir compartments would require installation of a large temporary power source to provide adequate heating and lighting during the works. Given the size of the diesel-powered generators required, a potential noise pollution hazard was identified as the site is in a residential area. As the plant would need to run 24/7, there was also an increased risk of attracting trespassers onto site. This meant security would be required overnight and at weekends, further adding to the cost of the scheme. Following detailed conversations the decision was made to install a permanent electricity supply into the valve house building. This eradicated the noise pollution issue and negated the requirement for security. United Utilities paid for the cabling required for the heating and lighting to be retained on site as an efficiency for future maintenance works within the reservoir. The decision gave the utility a permanent onsite power source and saved over £50,000 in project costs. Initially, mechanical preparation of the concrete substrate was undertaken. This provided a key for the BASF Masterseal 933 overbandage adhesive. Samples of adhesive were applied to the prepared areas. This allowed pull-off tests to be carried out to prove the adequacy of the preparation as part of Stonbury’s quality assurance (QA) procedures.   Some 40 rolls (800 linear meters) of BASF MasterSeal 930 overbandage were used in each of the two compartments, fixed to the adhesive-coated walls. Lengths were run down each wall joint and two meters onto the floor to ensure the tanks were completely watertight. Stonbury maintained detailed application and cure records at all times and datalogging equipment constantly recorded the exact temperature within the tank. The information was downloaded and passed to UU as a record of compliance with the manufacturer’s IFU along with all other QA records. A baffle wall running down the centre of each compartment also required replacement to bring materials into line with DWI approvals. The baffles ensure the water circulates throughout the tank so no dead areas occur, which is likely in this instance due to the inlet and outlet both being situated on the same side of the tank. Operatives from Waterlines Solutions installed the company’s DWI-approved Flagon thermoplastic membrane liner. Flood tests were carried out internally and externally post-repair. Fire hoses transported water from onsite hydrants onto the roofs and visual inspection to identify any further ingress was carried out from within the tanks. Whilst the initial scope for the external works was successful, water ingress subsequently occurred through previously dry areas. These were remediated by applying the same techniques until the tank was passed as defect-free. The project time extended from 10 to 26 weeks as a result of extra ingress points on the roof being identified and additional sealing work taking place. A further 24-hour flood test involved bringing water into the tank for 24 hours via sprinklers before carrying out sampling to identify potential contamination caused by ingress. Onsite health and safety risk management included mitigating against potential trips, slips and falls due to open excavation. Procedures for working in confined spaces, at height and using scaffolding were also followed. Regular site audits were undertaken by Stonbury’s quality, safety & environment department and no health and safety incidents occurred during this project. The client was kept informed about the works throughout the project using the Stonbury Client Portal. Once the job set-up was activated all the stakeholders were notified by email and invited to log into the portal for project updates. These postings were made at least twice a week and regular site meetings were also arranged.

Stonbury Limited secure position on Yorkshire Water £1bn Civil Engineering Framework

Stonbury have been successful in securing a framework award for Yorkshire Water, covering their Minor Civils Framework, Lot 2. Stonbury have been working with Yorkshire Water since the late 1980s. The relationship enhanced when they secured the first Framework agreement with Yorkshire Water in 2000, covering ‘The refurbishment and repair of potable water structures’ for AMP3 and subsequent frameworks covering AMP4 to AMP6, which is due to expire on March 2020. As framework contractor for Yorkshire Water, Stonbury have successfully worked on a vast number of Yorkshire Water assets across the region and are thrilled to have secured a place on the lot 2 Minor Civils Framework. Divisional Managing Director, Jon Featherstone, said ‘As Stonbury’s longest-standing client, we are extremely proud to retain the confidence of Yorkshire Water to deliver critical works, ensuring the long-term stability of their assets. This is a testament to the professionalism and dedication of all our staff employed on this framework over the last years’. Initially running for a 5-year term, 2020 – 2025, there is an opportunity for the extension of the agreement up to 2028. The framework covers specialist works on water retaining structures, including the refurbishment/repair/waterproofing of potable and wastewater assets, both above and below ground. Stonbury will continue to service the Yorkshire Water Framework from their Northern based office in Beverley, East Yorkshire, offering clients full access for hot-desking facilities and meetings, promoting collaborative working. Yorkshire Water are working to develop a collaborative approach with all AMP 7 appointed contractors and recently held a Civils Contractors Welcome Event. Several of the Stonbury team attended the event, deeming the day a total success and an excellent opportunity to build relationships with fellow contractors. “We are excited about the emphasis on collaborative working, and thoroughly enjoyed meeting the contract partners at the welcome event. Using collaboration to drive efficiency and innovation has always played an important role in the work we deliver at Stonbury, and we believe we can add genuine value through our allocated framework, in partnership with the other framework contractors.” Richard Harrison, Framework Delivery Manager Stonbury looks forward to working with Yorkshire Water and their partners over the next AMP period, embracing new challenges and helping achieve their goals throughout AMP7.       

Successful growth for Stonbury in Scotland

With Stonbury fully established across Scotland, we are looking forward to SR21 and the opportunities for further development. Following the launch of Stonbury in Scotland, a little over a year ago, we have seen fantastic growth across the area. Our Scotland team has dramatically increased in size and recently expanded to a second location in Central Scotland. “We wanted to share our expertise in Scotland for quite some time but waited until we had the right people in the right place, and the decision to do this has absolutely paid off. Headed by Iain Weir, who I have known for many years, the Scotland team are delivering work to a high standard, with the relevant skills to support Scottish Water in SR21 and beyond”. James Stonor, Stonbury CEO We have already successfully delivered various growth and capital maintenance packages for Scottish Water through their delivery alliance ESD and are thrilled to have been recently awarded another fantastic scheme with them. The works include the refurbishment of three large service reservoirs over a 38-week period. “The partnership we have built with ESD over the past year has, and continues to be extremely positive and has allowed us to grow the business in key areas and invest in the people we need to ensure we are delivering high quality, safe projects.” Iain Weir, Managing Director, Scotland Area Initially supported by Stonbury delivery teams across the UK, the Scotland team, now comprised entirely of locally-based staff, are fully set up to allow growth at a sustainable pace and look forward to the further development of the team structure.      

CoSHH Awareness and Skin Protection

As specialists in the refurbishment of water retaining structures, our teams use CoSHH materials on a daily basis. These products are DWI Regulation 31 approved products and are known to contain skin sensitizers. In some cases, contact with these sensitisers can cause an allergic response to an individual, with severe consequences. We have recently implemented a number of safety alerts, training exercises and VTBT’s across the company to ensure operatives working with these products have a full understanding of the risks to both themselves and others. A key part of the training has been to ensure our teams understand the risk of onset or increased sensitisation through repeated and prolonged exposure to certain materials. We also focused on demonstrating the importance of following the correct PPE removal procedures. A practical task was set for all operatives working with CoSHH substances, where coveralls and gloves coated in jam, were to be removed without the jam touching any area of skin, the jam was a representation of the uncured materials used on site. The exercise was a complete success and gave our QSE team the chance to remind and reinforce the working procedures around skin protection. This was followed up with a video toolbox talk on the prevention of skin sensitisation and dermatitis. As DWI Regulation 31 products develop, we will ensure the importance of skin protection, washing procedures and effective aftercare is reinforced throughout the company. You can view our ‘Skin Protection VTBT’ here.

DWI Regulation 31

Creating an environment where all water companies buy into a single code of practice to create unity and encourage best practice. The water industry is highly-regulated, most particularly to ensure that drinking water is safeguarded and fit for human consumption. The Drinking Water Inspectorate (DWI), formed in 1990, holds responsibility for regulation in England and Wales. The DWI inspects the laboratories where water companies rigorously test their drinking water and ensure that water operations are of a high standard. These standards are set down in national regulations for England and Wales and comply with laws set down by the European Union. It is in the DWI’s role to issue and assess approval for the use of products that fall under Regulation 31. Regulation 31 of the Water Supply (Water Quality) Regulations 2016 implements Article 10 of the Council of the European Union Drinking Water Directive (DWD) in England and Wales for all chemicals and construction products used by water undertakers, from the source of the water, up to the point of delivery to the consumer’s building. It defines which construction products and materials may be used safely, having been found not to prejudice water quality and consumer safety. Read the full article here, published by UK Water Projects. 

Sample Tap Training

As part of many of our contracts with water companies across the UK, we complete the installation and refurbishment of regulatory sample taps. Over the last 3-4 years we have refurbished and installed approximately 75 separate points for Yorkshire Water, this includes both walk-in cabinets and roadside kiosks, along with sunken sample pits to ensure gravity flow and new connection to mains where required. Prior to a new batch of sample tap works starting in early 2019 and to improve our continual quality standard for these installations, our workforce on this contract have undertaken the BPEC Plumbing Training in relation to Water Regulations compliance and fittings, delivered by Yorkshire Water. As a nationally recognised course, we are delighted to soon hold accreditation in this area, along with a planned extension course for groundwork pipework. The information learnt will be put into practice, as we resolve more challenging sample points across the Yorkshire Water area.

Whittle Dene Clarifier Refurbishment

Whittle Dene Water Treatment Works is Northumbrian Water’s fourth largest treatment works with a deployable output of 118Ml/d, supplying 228,000 properties. Located in Northumberland, 13 miles west of Newcastle, it is a strategically important works to Newcastle, Gateshead, North Tyneside, South Northumberland and Tyne Valley regions. Raw water at the site comes from adjacent reservoirs supplied by a number of impounding reservoirs in Northumberland and is further supplemented by the River Tyne. The treatment process at the works comprises; (i) clarification, (ii) filtration, (iii) GAC filters and (iv) disinfection and emergency disinfection. An asset need has been identified to address the very poor condition of the internal walls and floors of the clarifier units which have been subject to excessive concrete degradation in the 24 years since their construction in 1992. Project need The clarifiers comprise a large hexagonal footprint containing six separate chambers in an above-ground reinforced concrete structure. A structural survey identified the deterioration had resulted in an estimated 5 to 10 years residual asset life with only 5 years for the structural columns. Beyond this the structure would have a high risk of being irreparable and would require a full replacement at a high capital cost. The scope proposed by this project comprises refurbishment of the tanks to prolong their asset life and safeguard the treatment process into the future. The agreed scope identified in the Asset Need also includes for replacement of the launder channels which are in very poor condition and contribute to increased algal growth, causing problems in the downstream process. Undertakings Following agreement of a price of £2.5m NWG commissioned Stonbury to deliver the defined solution through an NEC 3 Option B re-measurable three-year contract. This commenced in January 2017 with the release of the first of the 6 (No.) compartments by reducing the works deployable output to 97MLD. Stonbury then commenced the initial clean down of the residual sludge in the compartment before building a scaffold platform with two working levels for the full height of the 6m high walls. The work required close coordination with Operations due to the connectivity between each compartment to prevent any overtopping of the common outlet channel discharging into the isolated chamber. Mortar repair In order to comply with the specification to meet the requirements of the Secretary of State for the Environment under Regulation 31(4) (a) for products used in contact with potable water Stonbury proposed the use of MasterSeal products. The chosen products were MasterEmaco S420 which is a rapid setting, high strength repair mortar in conjunction with MasterSeal 586 which is a smooth finish waterproof render. This was applied to the floors and walls of the clarifier in climatically controlled conditions to ensure adequate curing conditions were achieved. Launder channels In addition to the concrete repair work the existing launder channels were to be replaced due to their inoperability caused by their design which results in algal growth blocking the outlet holes. A new ‘V’ notch design was agreed which would provide a more even distribution of the clarified water for a more even and consistent discharge of the settled water. Phased refurbishment Following completion of Clarifier No. 6, Stonbury was handed No.1 to commence the second phase of the contract. Through a lessons-learned review Stonbury was able to improve their working methods and hence shorten the programme for the next phase. Whittle Dene WTW Clarifer RefurbishmentDesigners, contractors & suppliers Client Northumbrian Water Main Contractor Stonbury Limited Designer Wood Group LLP Main Supplier MasterSeal Wind bracing assessment The Fluid Group Climate control for the curing Polygon   Wind assessment and bracing Finally following feedback from Operations on the performance of the clarifiers due to their exposure to prevailing winds The Fluid Group was commissioned to carry out an assessment of the existing wind bracing. Following their assessment, it was established that the existing mesh panel arrangements were set at the optimum height and they were then replaced like for like due to their deteriorating condition. Progress to date At the time of writing (May 2018) the work on the Clarifier No.1 is substantially complete but due to operational constraints work has been suspended since January to allow the works to increase its deployable output to meet network resilience demands. It is envisaged that work will recommence in June 2018 to complete No.1 and move on to the next compartment in due course. During the outage of each compartment the opportunity was taken to carry out further refurbishment work to the outlet valves and rotorks as they were also at the end of their asset life. In addition, non-compliant handrailing is being replaced to allow future public access visits to recommence on site.