BPF produces new guidance for drain & sewer design

BPF produces new guidance for drain & sewer design

Jason Shingleton, BPF Pipes Group, talks us through the new guidance.

Wouldn’t it be useful in designing and building drains and sewers to be able to quickly refer to easily accessible guidance?

The BPF Pipes Group has produced new guidance: Specifications for Plastic Pipes, Chambers, Manholes and Covers for Drainage and Sewerage Applications, which can be accessed at: www.bpfpipesgroup.com/media/21445/Drains-and-Sewers-guidance.pdf. This guidance document clearly and concisely sets out information on product standards for pipes, chambers, manholes and covers; which are current and detail what to use where for all applications from private drains to public sewers.

The guidance has been prepared ahead of the publication of two key documents, the European Standard BS EN 752: 2017 with its UK National Annex and Sewers for Adoption 8th edition for the design and construction of private and public drains and sewers. The revision of Sewers for Adoption, following hot on the heels of the European Standard, represents the first real opportunity for designers and installers to obtain clear and consistent advice covering the full spectrum, from private drains built to Building Regulations, through to publicly adopted sewers

In October 2011, existing private sewers in England and Wales were transferred to water and sewerage companies and new sewers and lateral drains were required to be adopted. Installers who had traditionally been building for the private market, are now building for public adoption.  This means that the advice and requirements contained in existing documents Approved Document H 2002 and amendments 2010 and 2015, Sewers for Adoption 6th edition 2006 and 7th edition 2012, BS EN 752 2008 and amendments 2013 has become ‘out of step’, confusing for the end user and in some cases not aligned with modern practice.

What’s new?
This new BPF Pipes Group guidance provides quick access to key information for those designing and installing sewer pipework, chambers and manholes. It is divided into five clear sections: Drains and Sewer Pipes; Inspection Chambers; Manholes; Covers for Inspection Chambers and Manholes; Proving the Integrity of the Wastewater System. In each of the first four sections, the correct and current product specifications are identified and summarised, terminology is demystified, and key recommendations given. The final section succinctly explains the requirements for whole system integrity testing following construction.

Prioritising safety of the public and personnel working on the drain or sewer
This has been fundamental to updating the National Annex; everything follows the principles of Confined Spaces Regulations 1997 for operations to be carried out without entering a confined space. This introduces a new challenge to designers, to adopt above-ground working as the new default, and having to justify where below-ground working is needed (for example in deep installations and at high maintenance points). This applies even for large diameter public sewers. To help, the new Annex has addressed the confusion over clear opening sizes for access points by explaining the reasoning behind sizing, and by providing consistent and easy to follow text which applies equally to private and public systems.

Accurate and consistent definitions
The BPF Pipes Group guidance shows how many different terms are used to describe the same system components. Providing definitions which can be used across the industry will minimise confusion and save time. For example, the four defined access points are now:

  • Rodding points (small diameter connections at the upstream end of a drain or sewer that permit entry into the system for cleaning or inspection downstream, and which can include gullies incorporating rodding points);
  • Access fittings (normally located near the upstream end of a drain or sewer, permitting entry into the system for cleaning or inspection.  Restricted access means operations to remove debris using suction hoses are not possible);
  • Inspection chambers (chambers with working space at ground level only, used to introduce equipment for testing, inspection and maintenance.  The chamber’s working space normally permits additional operations to those carried out through an access fitting, such as debris removal using suction hoses or over-pumping from one chamber to another);
  • Manholes (chambers with working space at drain/sewer level used for entry of personnel and equipment).

The BPF Pipes Group is pleased to be able to offer this new guidance and welcomes the update to EN 752: 2017 and its UK National Annex. These together will go a long way to providing end users of the guidance with clear information and will be of considerable benefit for projects going forward.

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