WET News

ADVERTisEmEnT fEATuRE T he case study is a great example of the challenges faced by contractors and clients in wastewa- ter treatment projects. Extensions or upgrades to such works by definition are located on the site of existing works. These sites have often been built on, extended or renovated over many decades. All of the challenges a contractor might encounter on a multi kilometre pipeline are condensed within the boundaries of the works and typically over 50m-100m pipe runs. Contractors find themselves dealing with a 'perfect storm' of existing services and buildings, pipelines required above ground on plinths or at extreme depth, contaminated and aggressive soil as well as changes to design as work progresses and unforeseen challenges present themselves. All of this means a far higher level of day-to-day technical support is required from pipeline suppliers than would normally be required. This support, if sought at the early stages of design, can head off issues before they become major problems. Socket spigot systems are ideal for the relatively short pipe runs that typically navigate around the services of existing buildings typically found at wastewater treatment sites. They offer the flexibility to cut on site to required lengths to adjust the position of Pipelines in wastewater treatment projects Simon Cottingham, major projects director of Saint-Gobain PAM UK, takes a look at some of the pipeline issues presented by wastewater treatment works projects. fittings and to accommodate design changes. In order to provide thrust restraint for socket spigot pipelines most designers specify concrete blocks. As a pipe diameter increases, so does the size and cost of concrete thrust blocks, and this can become a deterrent to specifying socket spigot systems. Occasionally, flange pipe and fittings are specified as a way of negating the need for thrust blocks, but the lack of flexibility of a flange joint in buried applications will almost certainly result in premature failure. Boltless mechanical anchorage systems such as our Universal and PAMLOCK anchored joints are flexible, simple and quick to install and are a cost-effective alternative to concrete thrust blocks. Since they do not require external bolts to lock the system together there is no requirement for post-installation wrapping to protect the integrity of the bolts. On a recent project, a contractor installing a 1,200mm diameter Universal anchorage system took on average 15 minutes to complete the installation of each joint, which is 75% faster than the typical installation time of a traditional bolted anchor system. The idea that anchorage is required at every joint is also a common misconception. This is rarely the case. Using our Pipespec anchorage calculation tool our technical team can consider all of the parameters relevant to minimise the number of joints requiring anchorage. In many cases water and wastewater is not being transported at high pressures within the confines of a treatment works and the mechanical anchorage required can be minimal. The savings in design and construction costs can be significant as well as negating the disruption to adjacent services and buildings caused when trying to position a large concrete thrust block. There exists another major issue for contractors and clients requiring assurance of long-term system integrity. This is the fact that treatment works are often built on brownfield sites with relatively aggressive ground conditions. The implications for not applying the appropriate level of corrosion protection is unlikely to have an immediate impact on the client, but can result in an expensive and highly disruptive system failure at some point in the future. At Saint-Gobain PAM UK we offer soil surveys and ground investigation reports to enable us to provide bespoke external pipe corrosion protection systems for even the most aggressive ground conditions. Corrosion protection can be localised to the soil conditions at each pipe and any addi- tional protection limaited to areas of need rather than across the entire pipeline. Once again, early involvement of our technical team allows decisions to be made on the most appropriate level of corrosion protection to minimise cost whilst providing assurance of long-term pipeline performance. Contact dertails For further information on the range of ductile iron pipes that are ideal for wastewater treatment works including our Integral range, barrier coatings, Universal and PAMLOCK boltless mechanical anchorage systems, valves, couplings, adaptors, dismantling joints visit http://www.saint-gobain-pam.co.uk. Case study: a major wastewater treatment works in the north-west of england Project overview: Construction of a new process stream, capable at peak of treating 5,500 litres per second of raw sewerage coming into the works. Saint-Gobain PAM UK products used: Pipework diameters from 200mm to 1,800mm; range of anchorage systems including Universal and PAMLOCK; a range of external corrosion protection systems; standard coated pipes; TT PUX and PECS coated pipes. Challenges Overcome: Threading pipeline through lots of existing services and structures; numerous changes in level and direction of the pipelines; overcame need for concrete thrust blocks through using Saint-Gobain PAM UK's mechanical anchorage system; pipes pulled through tunnels; some pipes to be positioned on plinths and others laid in trenches. key Performance information: l Up to 4.5 bar test pressure l Laid at depths of up to 5m l Laid in aggressive soils containing, among other things, high concentrations of ammonia l Laid between existing structures and roads, resulting in a high proportion of fittings relative to pipe length AUGUST 2017 WET NEWS 5

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