Specification of Inspection Chambers
When it comes to the specification of Inspection Chambers, Sewers for Adoption 7 and a vastly improved new British Standard are leading the way.
As well as providing comprehensive design and layout guidance for adoptable drainage systems, WRc’s Sewers for Adoption 7th Edition (SfA7) is big news for anyone considering the specification of plastic Inspection Chambers (ICs). For the first time, the use of plastic ICs to a maximum invert depth of 3 metres has been authorised for non-man entry chambers by means of the incorporation into the document of standard details: Figures B16, B17, B21 and B22 which show standard installation requirements.
In addition to the standard details SfA7 Part E: Civil Engineering Specification, Clause E2.31 states: Plastic chambers and rings, including demarcation chambers, shall comply with BS EN 13598-1 and BS EN 13598-2.
This new standard recognises that not all plastic ICs are equal and there are now several ways in which BS EN13598 offers a more robust benchmark for the industry than the previous standard i.e. BS 7158.
Three key improvements contained within the new standard are outlined below.
Material used for Inspection Chambers
While Part 1 of the new standard (covering ICs up to invert depth of 1.2m) hasn’t changed greatly over BS 7158, Part 2 for deep chambers introduces a new requirement for thorough testing of the material’s durability. In the case of virgin plastic, this is 1000 hours and, for reformulated or recycled plastic, it’s an extensive 3000 hours, so any specifier can be assured that the material is fit for purpose.
Structural Integrity of Inspection Chambers
On the specific area of structural integrity, BS EN 13598-2 requires not only 1000 hour testing for the first time for plastic chambers, but also that a 50 year deformation projection is developed. This requirement means that the material is predicted to last 50 years with no cracks during normal use, offering reassurance of longevity and endurance.
Impact requirements of BS EN 13598-2 and BS EN 13598-1
Recognising that maintenance is a key factor, the new tighter BS EN 13598-2 requires impact testing of the internal base configuration to ensure fitness of purpose, the standard calls for testing using a 1kg weight drop from a height of 2.5m with no resultant cracking.
This substantial set of new guidance will give specifiers, engineers and developers new confidence in plastic ICs for adoptable installations, enabling them to make the leap from traditional concrete solutions which are often restrictive in use. In contrast, plastic ICs offer a lightweight, easy to handle solution with a host of health and safety benefits on site, but also a leak-proof, highly engineered construction.
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