Adopting a new approach for foul & surface water sewers

New legislation scheduled for later this year will demand a new approach from house builders, ground workers and contractors when it comes to the design, planning and installation of foul water & surface water sewer systems.

Terry Hill, Technical Support Manager at specialist water management company JDP says the new legislation need not be seen as another headache for the industry if the right advice is followed from the start of the design and planning process. Driven by the Flood and Water Management Act 2010, mandatory ‘adoption’ and new standards for all (new and existing) foul water sewers is coming.

Currently, not all sewers are adopted. When the new legislation, scheduled to be implemented from Oct 2013, is finalised by Defra this will all change. Every sewer and lateral drain that serves two or more properties and connects to the public sewerage network must be adopted and will therefore become the responsibility of the relevant Water and Sewerage Company.

For house builders the implications are that they must have a Section 104 agreement in place with the water company before construction can start. To achieve a Section 104 agreement a new approach will be demanded to the design and construction of sewers and lateral drains according to new building standards.

The content of the new building standards is yet to be finalised with current recommendations published in August 2013 by Water UK, which represents all major UK water and wastewater service suppliers, and in the design guidance document, Sewers for Adoption 7 (SfA 7), which was published in August 2012.

The proposed standards under SfA 7 will require the foul water and surface water drainage design to be submitted at planning application stage and will no longer be dealt with under reserved matters. Through its dedicated technical design department JDP provides expert design, advice and support for all projects involving Surface Water & Foul Water Management systems. In turn this helps developers and contractors comply with the new legislation using solutions, which best meet the site requirements. The Technical Design department uses the latest technology in hydraulic modelling, (Microdrainage), to design these systems, produce CAD drawings and provide a 24-hour turn round take-off service to ensure clients can comply with the new standards and save time and cost.

Under SfA 7 new rules and specification guidance is given on accessibility. The emphasis here is on ease of access for the water companies with regard to inspection and maintenance. Wherever possible sewers and lateral drains should be laid in highways or public open spaces and manholes are required in a limited number of situations. The standard also requires a number of non-man entry access points.

A key requirement of the new standard is that plastic inspection chambers are now accepted for use in adoptable areas provided they comply with BS EN13598-1 and 2, or have the equivalent independent approval.

Part 1 covers chambers for installations down to a maximum invert depth of 1.2 metres and Part 2 to a maximum invert depth of 3 metres. Traditionally the use of concrete chambers would have required a hole of much greater diameter than that possible using a modern plastic chamber. The use of plastic chambers can lead to savings in installation time of up to 50%, saving cost both in time and also supporting materials, and in addition offering non-man entry access as outlined in the new standard. JDP has developed its Axedo range of plastic inspection chambers suitable for access points of up to 3 metres deep and offering full compliance with the requirements of SfA 7.

Providing impartial expertise and advice on the best system solution to suit an individual project and ensuring

SfA 7 compliance also requires a new approach, where products are not simply supplied within the confines of a single manufacturer’s range but consideration is given to the design of the project as a whole. This is where JDP’s service excels.