Case Study: 340 Houses in North East England
The site had been classified as an NHBC - AMBER 2 (Characteristic Situation 3) risk and required integrity testing of the gas membrane installation on all plots as part of the validation process. Initially the site had a specialist gas membrane installation contractor, a separate independent integrity testing contractor and a consultant to validate the full protection system installation, which was proving costly to the main contractor.
We were asked to look over the site risks in the site investigation and the remediation strategy, along with the original design, to see if we could offer any cost savings. In conjunction with strategic partners we produced a report to reduce the site risk to AMBER 1 and whilst liaising with the local authority, provided a risk assessment, which allowed us to negate the requirement for integrity testing on all plots. Also, given the installation contractor had NVQ level 2 in gas membrane installation, we took the requirement for validation down to one in ten plots with the rest under contractor CQA. This equated to an approximate saving of £90,000 for the main contractor on the whole project.
On sites with a lower risk than Characteristic Situation 2 or AMBER 1 we can in many cases eliminate the requirement for gas protection systems altogether. The earlier we can look at site information, the easier we can arrange approval of any design changes through the local authority/design team.