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self lay water supply process) who can show they employ registered drainage operatives with the relative skills, will ensure a trouble free process. There is only one relatively easy and simple way to ensure a better compliance and that is for the entire workforce engaged on adoptable sewer laying to have the necessary construction and training skills. The scheme would prove to all parties that the workforce had the necessary skills for the type of work being carried out and, if linked to an accredited drain laying contractor process, would ensure that the water company had a guarantee that both material and workforce had all that was necessary to produce quality systems with minimum maintenance requirements. The water companies are looking to a minimum jetting requirement of 4,000psi (265 bar) but consideration should be given to the fact that the cause of blockages in sewers and drains are mostly the result of inappropriate materials being discharged down a sewer and poor laying of the pipes. To clear a blockage generally requires low pressures and a good water flow. A high pressure merely punches a hole through a blockage rather than clearing it. There is already a code of practice in use by the water jetting industry which recognises the need to use the correct jetting head and nozzle pressure appropriate to the pipe material and condition of the pipe to be jetted and, as all of the sewerage foul system and lateral drains will be under a water company control, they should have no difficulty in ensuring that only well trained and informed operators are working on their systems. Restricting pipes to be used for public sewers and lateral drains to a 4,000 psi minimum is in fact an over assessment of the requirements and will restrict the use of modern alternative materials in pipe design. Common sense says that realistic and cost effective design criteria, such as the use of concrete surrounds to concrete manhole rings, should only be required where it is known that ground water levels will cause infiltration to the foul system, and a modern design specification based on realistic probable water flows with a tightening of the construction quality can only be good for the whole industry. Why there is a suggestion that water companies could require a 100% bond when many have found the current practice of a 10% bond to be unnecessary, can only be guessed. The use of accredited contractors to lay new adoptable sewers would be of mutual benefit. Sustainable Urban Drainage Systems (SUDS) is another outstanding issue and it is still not yet known whether this will have any implications for the transfer where downstream pipes discharge to the surface water system. Provision has been made for an economic approach to construction and as long as the design process allows for responsible maintenance provision then this will be achieved. This has to take into account development sites where conventional piped solutions discharge to a reasonably close sewer or watercourse and where the pipe discharge does not require storage via an enlarged pipe which will inevitably be a lesser cost than the SUDS option. In addition, the maintenance costs of a SUDS system will be greater than the conventional pipe solution – grass cutting, weed control, silt, leaves and rubbish control. It is essential that existing definitions for drain and sewers are maintained to avoid conflict. In the same way, if there is a need for SUDS under general planning requirements then this needs to extend to cover Neighbourhood Development Orders and the like. To make this system clearer it would be preferable to make the sewerage undertaker responsible for all pipes, or for the SUDS Advisory Board (SAB) to have a duty to adopt the whole system from source to outfall. There needs to be a requirement, as in the July 2011 regulations for sewer adoption, for all private SUDS systems to be transferred to the SAB’s who will have the resources and skills to maintain them. The transitional arrangements should allow for a period of training and understanding before there is a need to commence work in the ground but it is hoped that this will all be in place by October 2013. All developers and contractors should be promoting the introduction of a register for drainage operatives and encouraging their operatives to be fully skilled in the necessary competencies to ensure a trouble free and cost effective process. q

Two examples of Sustainable Urban Drainage Systems (SUDS) – images courtesty of the British Geological Survey

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Environment UK Magazine  

Environment UK Directory and Magazine

Environment UK Magazine  

Environment UK Directory and Magazine