Sewers for Adoption 7th Edition - notes on interpretation

Introduction

These notes have been prepared by Civils Store Ltd to support  our customers with regard to the requirements of the new standard. Whilst the new standard is not yet in statute many authorities are already insisting on the specification. We hope that these brief notes will help our customer base in ordering materials that comply with the standard.

Disclaimer

No responsibility can be accepted for the accuracy of these notes and customers should always check with their appropriate water authority.

Liaison with the local inspector is paramount.

General – Design

Given the requirement for water authorities to now adopt all drainage to the boundary of the property and to adopt all drains carrying 2 or more properties much historical private drainage has now become the responsibility of the water authority and hence changes in future design requirements.
Access is required to the adoptable drain of each property without necessitating access to a neighbouring property. For example an inspection chamber is now required both sides of a boundary where a drain crosses a boundary.

Inspection chambers – flexible material

Small inspection chambers (300mm dia) are limited to a maximum depth of 2000mm, Fig B.21.
Typical Inspection Chamber Detail – Type 4, maximum depth from cover level to soffit of pipe 2m, non entry.

  • Joints between chamber base and risers and risers to risers to be sealed

Civils Store recommend the use of Mini Access chamber ref D800 range.

Where inspection chambers are positioned on 90 degree corners always use the main channel by fitting 45 degree bends on the inlet and outlet.

Large inspection chambers (450mm dia) are limited to a maximum depth of 3000mm, Fig b.16
Typical Inspection Chamber Details – Type 3, maximum depth from cover level to soffit of pipe 3m, non entry.

  • All Joints between chamber base and risers to risers to be sealed.
  • 450mm dia large Inspection chamber (LIC) for use with chambers up to 3mtr depths. Please note for chamber depths above 1mtr access needs to be restricted to 350mm. Frames with restricted access are available
  • Base units to have all connections with a diameter greater than 150mm set at a soffits level
  • DOT Type 1 sub base or concrete surround

Covers complying with BS EN 124 and BS 7903 – Gardens shall be Class A15
Covers complying with BS EN 124 and BS 7903 – Driveway, footways and landscaped area shall be Class B125

PVC Pipe systems – flexible materials

110mm and 160mm pipe systems shall be either:

  • PVC construction to BS EN1401
  • Structured wall PVC (foam core) to BS EN 12476-2 and WIS 4-35-01 providing the pipe has a ring stiffness not less than 8kN pm2 (SN8)


Over the weeks and months ahead Civils Store will update this section of our web site to ensure that it becomes a valuable reference for changes in regulations and of major industry news stories with downloads and links made available.