Water and Effluent Treatment Magazine
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Service reservoir project refreshes supply in Burton-on-Trent •Stonbury's project to construct a new service reservoir for South Staffs Water achieved the best whole- life asset solution while overcoming challenges relating to ecology and weather Background South Staffs had originally been awarded planning per- mission for a new reservoir on the footprint of Reservoir No. 1 in 2014. The project was delayed due to unexpected work on other schemes within the South Staffs Water supply network. Whilst the site was still able to function it was important that both storage capacity and resilience of the site were increased. The decision was made to locate the new reservoir on a greenfield area of the site rather than in the footprint of Reservoir 1 to reduce the over- all construction programme and meet supply demand. This would not only enable South Staffs to operate two reservoirs at all times, but also opened up the opportunity to build an additional reservoir in the future on the footprint of Res- ervoir No1. This investment will help to guarantee the quality and reliability of the local water supply for the next 100 years, and play a key part in meeting growing demand from new housing being built in the area. The contract Stonbury has worked closely with South Staffs Water for many years, currently holding a five-year Framework for Res- ervoir Refurbishment. Although nationally the company typically refurbishes around 450 reservoirs annu- ally, this is the first time Ston- bury have been responsible for a new build reservoir. The tender process involved a high level of optioneering of all possible solutions, including tem- porary tanks, steel tanks and GRP tanks. The option selected was a hybrid solution for a reinforced concrete structure, which included precast concrete col- umns and roof structure. This was deemed to be the most cost-effective solution in respect of both whole life costs and design life, as well as one capable of being delivered to the very challenging programme. Stonbury subsequently completed the detailed design stage, which developed the outline design, submitted at tender stage. It was decided to split the reservoir into two 5Ml tanks to speed construction and enable delivery of one of those tanks into service at the earliest opportunity and fur- ther increasing long term stor- age resilience. From the date that Stonbury gained access to the site on the 9 March 2017, there was a 16-week timeline specified by South Staffs before commis- sioning the first reservoir by 1 July 2017. Ecology evaluation Shortly before work was due to begin, an ecology evaluation ONSITE WATER RESOURCES 8 WET NEWS FEBRUARY 2018 challenge of the project. South Staffs Water agreed to adjust the budget to allow for 12-hour day and weekend working by the team, with some personnel then on duty every weekend. The team of people assigned included up to 25 operatives at any one point. Whilst the team were able to work the additional hours to bring the project in on time, accelerating the schedule meant that problems arose with the timely delivery of key materials. Commissioning The original date set for com- missioning the reservoir on 1 July 2017 was met, and the first stage was to fill it for its sev- en-day testing. The final inspection was conducted by the client and the project deemed completed and handed over. The reservoir was then dropped, re-cleaned, filled and sampled for return to service the week commencing 10 July, just 17 weeks from breaking ground. Community engagement Ahead of work beginning on site, Stonbury and South Staffs embarked on a community engagement programme with local residents. The reservoir is close to housing, and concerns had been expressed during the planning process that lorries entering and leaving the site highlighted the presence of Great Crested Newts on a hous- ing development adjacent to the site. As a European pro- tected species, these animals, their eggs, breeding sites and resting places are safeguarded by law. Following a full ecological survey an environmental spe- cialist and licensed ecologists were brought to site to work alongside Stonbury to prepare the site for construction in the shortest possible timescale. Whilst no GCN or nests were physically found on site the erection of reptile barrier fenc- ing and hibernaculum ensured the protection of GCN during and beyond construction. Coping with the delay The steps taken to protect the Great Crested Newts did, how- ever, have a severe knock-on effect on the work schedule. A full eight days were lost on the commencement of excavation work. An additional element was also added to the original specification: the construction of a concrete valve chamber to house all the pipework coming into and out of the reservoir. This was to be a 12.8m long by 6.8m wide by 4.85m high structure. These delays, as well as heavy rain severely affecting progress on several days, pre- sented Stonbury with the main W hen Stonbury were tasked with the replacement of a ser- vice reservoir for South Staffs Water, the project team were able to deliver an impressive whole-life asset solution while engaging with the community effectively and ensuring conti- nuity of supply. Outwoods Reservoir was originally constructed in 1882 in Burton upon Trent. Follow- ing an increase in demand, Outwoods Reservoir No.2 was added in 1962. In 2016 Reser- voir No.1 was finally taken out of service a—er proving increas- ingly expensive to update and maintain. In 2017 South Staffs Water awarded Stonbury the contract to replace Outwoods Reservoir No.1. The Outwoods supply zone, fed from a number of storage reservoirs at Outwoods in Bur- ton Upon Trent, includes approximately 26,000 proper- ties in Burton upon Trent, Rolleston on Dove, Barton under Needwood, Alrewas, Fradley, and Streethay, with a combined total average daily demand of 23 million litres. The project was challenging with a tight programme and proximity of protected species, but achieving the deadline has ensured the supply network can continue to operate and provide a safe and reliable water supply for current and future generations.