Ground Gas Protection Liverpool
Experts In Solutions For Ground Gas Membrane Verification
UK residents are facing increasing problems from dangerous, naturally occurring below-ground gasses and vapours. It is vital that the presence of ground gases and the risks associated with them are assessed and mitigated to protect the structure and its users.
Natural gasses or historical usage may cause gases to be present at a site.
The naturally occurring gases methane is carbon dioxide, nitrogen, and radon. However, these gases can also be found in soil in elevated concentrations relative with normal atmospheric gasses.
Sites used in the past for landfill, heavy industrial, or where petrol or oil may have leaked can also emit hazardous gases like methane or carbon dioxide.
The gases and vapours listed above can cause cancer if they are not used in sufficient quantities. They can also react chemically with concrete and plastic building materials, which could affect the structural integrity of the buildings. They can penetrate buildings and other structures both above and below the ground.
There are many types of gas.
- Radon
- Carbon Dioxide
- Nitrogen
- Methane
- Hydrogen
- Sulphide
- Volatile organic compounds (VOC)
Radon, carbon dioxide and methane gasses, as well as VOCs (Volatile Organic compounds such as hydrocarbons), pose a danger to your health. Therefore, new constructions must use the appropriate materials to keep them out.
According to CIRIA C735, a separate ‘Gas safety verification plan’ (or ‘Gas protection verification document’) is required. A robust design and construction process should then be followed to install the gas protection measures and the requirements of ‘verification plan’ implemented. After the construction has been verified, it is time to prepare handover documentation. This document should outline any additional measures that may be required, such as those necessary for preventing damage or during operation and maintenance.
It is recommended that specialist advice is obtained in the assessment of the ground gas data and at the risk assessment phase. Below are some of the key documents to be aware of and refer to:
- BS 8485:2015+A1:2019 - Codes of practice for the design of protective measures for methane and carbon dioxide ground gases for new buildings.
- CIRIA C748:2014 - Guidance on the use of plastic membranes as VOC vapour barriers
- CIRIA C682:2009 - VOC Handbook
- CIRIA C735:2014 - Good practice on testing and verification of protection systems to buildings from hazardous gases
- BS 8102:2009 - Code of practice for protection of below ground structures against water from the ground
BS8485+A1 2019 offers recommendations on ground-gas site characterisation and the selections of solutions to design integral gas protective mechanisms for new buildings. This is done in order to prevent methane and carbon dioxide from entering and maintain a safe interior environment. It provides a method that can be used for demonstrating that there are no risks from the possible or actual presence carbon dioxide and methane.
Contact our Liverpool team for further information on ensuring that the installation of your gas protection systems meets the required legislation & regulations
How does ground gas happen?
Why is ground gas becoming a problem?
In the past ground gases where not perceived as a risk to users and the buildings themselves. As it is becoming increasingly difficult to find suitable sites for development, there has been an increase in the number of brownfield sites. Brownfield sites may contain contaminants that can affect the ground or soil.
Due to the the increased awareness of the risks the Environment Agency has produced new legislation with a much stricter approach when dealing with potential ground gas issues.This legislation has been adopted by local authorities throughout the country.
It is important for you to know that potential risk factors can only been determined by an in-depth ground gas investigation. This must be done by a competent ground gas surveyor.
Assessment of ground gas risks
The risk from ground gases or vapours must be assessed first at the desk stage. If ground gas risks are identified, then borehole measurement will be performed. Existing buildings can be monitored using static measurement methods and diffusion tubes. Depending on the nature and severity of the risk, monitoring programmes can last from days to months.
After the investigation is complete, an interpretation of the measurement data can be used to determine whether ground gases or vapours are at risk.
Protection from below ground gasses
Ground gas protection is an extremely specialised operation. GeoShields Ground Gas specialists have the required knowledge, experience and skill levels.
Ground gas protection is often achieved by ventilation and ground membranes in construction. This provides primary and secondary protection against the ingress of gases. A foundation-based ground gas protection system is unlikely to be practical if you’re already a homeowner. Ventilation is therefore the most important factor. Ventilation can use a combination of natural ventilation for suspended floors, improved underfloor ventilation and the introduction of mechanical ventilation systems so that the harmful ground gases can be safely controlled and vented away from the property. In every case, validation of the construction methods and their installation is necessary.
Sometimes, the gas and vapours can pose a risk because they are a result of soil or groundwater contamination. In these cases, remediation may be possible.
What's the impact of not doing something?
The impact of not responding to the potential ground-gas risk depends on the type and extent of the ground gas. Some ground gases can affect your health, others may cause damage to the building’s integrity. Radiant exposure can lead to lung cancer. Carbon Dioxide may cause death from asphyxiation. Methane (and other volatile organic compounds) can ignite and be flammable. As low as 5% can make methane flammable.
The property may be deemed too dangerous for mortgage lenders.
What is Ground Gas Membrane?
Ground gases are dangerous and buildings need to be protected. This protects the structure’s integrity as well as anyone inside it. Protection is usually in the for of a ground gas membrane.
Ground gas protection membranes are usually constructed from polymers but also include other materials such as aluminium. This allows them to be lightweight, flexible and formable. They can stop gas from getting into buildings and the ground.