Our Giles Sommerwill, was pleased to attend the CIRIA virtual conference today ‘Good Site Management for Hazardous Ground Gases’ (C801) which introduced how the new guidance will help consultants, developers, and site staff to facilitate successful construction, verification and protection of ground gas protection measures.
Many development sites in the UK require the incorporation of gas protection measures to prevent ground gas from getting into buildings. The gas may occur because of local ground conditions, prevailing geology, local areas of landfilling, and the presence of ground contamination or mine workings.
Hazardous ground gases can cause serious problems to residential, industrial and commercial developments. Whilst industry’s understanding about how to carry out appropriate risk assessment, and how to install and verify protection measures have improved in the past decade, ground gas problems still exist in many developments.
Key themes discussed today and featuring in the new guidance include:
- Appropriate and proportionate design and verification;
- Raising awareness amongst site staff to ensure the protection measures are offered adequate status and protection through the build;
- Promoting good practice;
- Highlighting common problems and failures, such as lack of sealing around service ducts, or damage to installed membranes;
- Specifying protection practices/measures (eg. puncture resistance) in addition to the key protection components (eg. protective membrane);
- A design report outlining objectives, specifications, watchpoints, checklists;
- Documenting QA/QC Verification.
ESP have wide-ranging experience in the assessment of ground gas hazards from both naturally occurring sources as well as brownfield sites, which often begins with a Phase 1 Desk Study at an early stage prior to purchase of the land. Where the potential for gassing sources is either anticipated or known (due to site use and/or previous preliminary investigation), a more detailed Contaminated Land Risk Assessment can be implemented from the offset. Ground gas monitoring can range from “spot monitoring” regimes over a period of weeks-months within boreholes, and on occasions continuous 24hr monitoring relayed by telemetry can be advantageous.
Once the ground gas regime and source potential is reasonably understood, we can recommend and assist in designing proportionate protective measures, and the validation of those being suitably installed can be inspected and recorded. Find out more here.