Water and Effluent Treatment Magazine
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10 WET NEWS MAY 2014 2011 and planning approval was received that September. Dee Valley Water had to beef up the screening onsite to hide the new plant building from local villages, which was done through the planting of more trees. "It went quite smoothly, really," he says. Before construction could start, the new treatment works had to be designed. Reef says: "We put the tender documents together in such a way in that the tenderers were asked to price for the design and construction of Type 1 works, and for the design only of Type 2 works. Type 1 works accounted for approxi- mately 45% of all works including the main process plant building construction, whilst Type 2 works accounted for the remaining works. "The cost of constructing all Type 2 works was finalised during the six-month design phase allowing a target cost for all works to be agreed." Black & Veatch led the design but Reef and his team ensured Dee Valley Water's considerations were taken on board. However, the target cost proved unaccepta- ble, exceeding the budget availa- ble. An intensive value engineer- ing period followed where "Black & Veatch worked hard with Dee Valley Water to bring the cost down to an affordable level Manganese removal It was decided that the capacity of the old works was sufficient for the new one, so 47.5Mld was agreed for treated water. The old site increased its maximum throughput by 50% to 47.5Mld in 1999, following an extensive refurbishment, to meet the demands of an increasing popu- lation as well as replacement treatment capacity of smaller facilities that were planned for closure. The project also provided an ONSITE ASSET MANAGEMENT construction; embedded and operational carbon footprints; energy efficiency; chemical usage; and operator attendance. Construction began in October 2011 and was completed in June 2013, enabling commissioning to start from June 2013 with full ser- vice from August. Before work could start, though, there was careful planning to ensure a con- tinuous and uninterrupted sup- ply of drinking water from the old works at Llwyn Onn. But before that could happen, planning permission was needed along with the design of the new building. Planning process In April 2011, Dee Valley Water selected Black & Veatch as the main contractor for the project. Black & Veatch employed locally based subcontractors to work on the project including North Wales civil contractor Mulcair; Wrex- ham-based electrical contractor Lloyd Morris Engineering; mechanical contractor JB Fabrica- tions, also from Wrexham; and Llay-based Tycon Automation, which designed the soŸware con- trolling the works. The work created many local jobs over the 18-month construc- tion period helping boost the con- struction and engineering econ- omy in North Wales, particularly in Wrexham. Civil engineering students from Yale College (now known as Coleg Cambria) were also able to benefit from the pro- ject with two site tours, one dur- ing construction and one aŸer completion, which allowed them to experience how a real-life con- struction project unfolds. The planning process for the rebuild was relatively smooth. Dee Valley Water had pre-warned the local authority of its plans in August 2010 but it was part of Black & Veatch's remit to put together the planning applica- tion. This was submitted in May Raw water is now stored at the nearby Marchwiel Reservoir. Also, the raw water water qual- ity dictated the treatment process The tight construction schedule meant careful phasing was required to ensure tasks did not affect other work areas