Until now, the installation of ground gas containment systems has been an important but largely unregulated area of the construction sector.
Installation companies could work on brownfield sites using materials expected to contain ground gases – whether radon, methane, CO2 or hydrocarbons – and, once installed, the new buildings would be constructed as planned.
Installation companies, some more experienced than others, are expected to provide a solution that completely protects the building from the ingress of ground gas. However, there was not any particular requirement for the work of the company to be tested by an independent source, to make sure the installation was absolutely solid.
But with the recent publication of the CIRIA document C735 Good practice on the testing and verification of protection systems for buildings against hazardous ground gases, there is now clear industry advice about why gas protection systems should be tested, how this should be done and who should carry out the verification.
I assisted with the development of this document and am extremely pleased that we now have this guidance on which to base testing and verification of installations. The implications of a faulty gas protection system can be severely damaging not only in terms of health and safety problems caused by the leak itself, but additionally the cost of repairs or re-installation and potential harm to the reputation of the installation company.
Contractors and building companies need to ensure that they are fully aware of this new guidance and the full implications. The industry is looking for all gas membrane installers to be approved by the CITB to NVQ level 2 within the next couple of years; however CIRIA document C735 states that “at this time it would be reasonable and practicable to expect the workforce engaged in such specialist activities to hold such a qualification”.
“Contractors and building companies need to ensure that they are fully aware of this new guidance and the full implications”
All independent inspectors should be experienced and qualified to carry out inspections and integrity tests so that tests are carried out to a consistent standard and by an expert in the field. The guidance aims to ensure the verification of the installation of gas/vapour barriers in accordance with the design and specification; promote testing of the integrity of gas/vapour barriers and ensure accurate recording and reporting of all testing and verification carried out.
It explores the various testing methods and looks at the advantages and disadvantages in a range of circumstances and defines the need and scope for certain verification activities during construction, providing advice on what needs to be inspected and when. At the end of this month I will be attending the first national verification and integrity testing course, run by the British Geomembrane Association in conjunction with the CITB CSkills scheme, to ensure I have the necessary qualification.
Good business sense
My company, set up earlier this year, provides a range of services to the construction sector including tracer gas integrity testing of installed geomembrane/gas membrane systems, gas remediation system checking and validation along with pre-contract testing report provision for new project planning.
Having worked in the gas protection system design, supply and installation industry for many years, I have seen first-hand the positive impact of testing and verification to ensure higher standards and improved quality of installations, which helps to drive up the overall quality of construction jobs, protecting both contractors and clients.
It makes good business sense to build independent inspection and validation services into all ground gas barrier jobs and now is the time to ensure contractors, local authorities and installation companies alike know what the contents of CIRIA C735 mean for their operations.
Barrie Ackroyd is director of Membrane Testing Solutions