WET News

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 IS YOUR MACHINE IN NEED OF A HOLIDAY?... ..WHY NOT ARRANGE NEW FLIGHTS? 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Reef explains: "In the old works we only had single stage GAC filters for taste and odour removal. We now also have second stage rapid gravity filters containing polarite media for manganese removal, which we have a problem with in our local area. "Whilst it is not harmful to health, it can cause discoloured water resulting in some custom- ers contacting the company con- cerned about the colour." The company has already completed several schemes to deal with the issue of manganese in the raw water including ice pig- ging of the Wrexham Ring Mains. This project used crushed ice to wash out all manganese, which had settled out in the ring main over the years. The scheme took about two months to physically carry out on site but was in the planning for 18 months to minimise dis- ruption to the water supply, says Reef. Llwyn Onn WTW is using de- alkalised water to not only carry lime to the dosing point but for batching purposes as well. Sul- phuric acid is used to de-alkalise the water, preventing the lime from precipitating out within the dosing lines. Reef comments: "There's a lot less flushing of the dosing lines. Since the works went live, there have not been any manual flush- ing requirements of the dosing lines whereas before it was every day or every other day. That's a huge saving." Dee Valley Water has also included a recycling facility at Llwyn Onn which means a lot less water is put to waste. "What- ever we can recycle means we don't have to pump up from Sess- wick pumping station on the River Dee, which is a 70m li'. Pumping recycled water toi the head of the works is a li' of less than 10m, so we're saving a lot of energy here." Up to 10% of the works throughput can be recycled, although only 4% is currently being recycled, says Reef. It is when the works gets dirty raw water coming in that the filters might need to be washed more and the DAF lanes may need to be flushed more, creating more water for recycling. The DAF de-sludge is a hydraulic operation in the new works. At other older sites Dee Valley Water has mechanical scrapers that require regular maintenance, which normally requires partial shutdowns. The hydraulic de-sludge removes this maintenance requirement. Savings Reef says it is too early to say what savings are being achieved at the new plant but Dee Valley Water is already seeing better optimisation of the chemical usage. Reef expects the site's electricity bill to be comparative with the old facility. While much more efficient motors are in use they are power- ing a larger amount of equip- ment, such as the recycling facil- ity which was not there previously. Also, the new low-li' pumps have a greater li' than the old ones due to the addi- tional headloss through the sec- ond stage filters.. But what the company will see, says Reef, is a saving at Sess- wick (the main intake off the River Dee) because whatever is recycled in the works "means we're not pumping up from Sesswick". And Dee Valley Water's investment at Llwyn Onn is con- tinuing as further work takes place with the planned rebuild- ing of both the treated water stor- age reservoir and the Wrexham pumping station. n The Ovivo® screw compactor incorporates the original Jones+A wood™ features that have a proven record of reliability and robustness. Our new design now receives flows from water powered launders and incorporates a 9mm thick drainage trough for ruggedness and 6mm TAPERED holes for improved drainage– built with lowering TOTEX in mind. Available in 5 standard sizes the Ovivo screw compactor loading capacity ranges between 0.5 and 9.5 (M³/Hr) and launder flows up to 8.0l/s. OVIVO ® Screw Compactor Call: 0121 511 2400 or visit: www.ovivowater.com © 2014 GLV Inc. All rights reserved. incorporates the original Jones+A wood™ features that have a proven record of reliability and robustness. Our new design now receives Screw Compactor Screw Compacting since 1986! Old Dog. New Tricks. Great Plug. C M Y CM MY CY CMY K Screw Compactor Ad 0314_PRINT READY.pdf 1 19/03/2014 5:02:20 PM

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