29Aug / 2018
As technology advances, environmental monitoring data is increasing in volume and expanding in range. The potential for these advances to refine the accuracy and speed of ground gas risk assessments is significant. Nonetheless, choosing the right technology, technique and team to perform these often complex on-site risk assessments is still a crucial consideration.
For a steadfast ground gas risk assessment, sources, pathways and receptors must be identified and accurately characterised for each pollutant linkage. Sources often include landfill, peat deposits or formerly industrial or brownfield land.
It is important to identify the worst-case ground gas risk in order to recommend appropriate remedial measures. Current generic guidance is often too conservative for many sites. Robust techniques such as continuous ground gas monitoring with continuous flow can assist in determining the most appropriate remedial measures required for a development by providing decisive and accurate data.
How have ground gas risk assessment techniques changed?
Previous to the introduction of continuous ground gas and flow monitoring, risk assessment data was often supplemented by periodic or “spot” readings. Flow measurements taken periodically are often affected by the ground conditions, barometric pumping or the piston effect, rather than a result of gas generation.
Continuous ground gas monitoring can help to identify the real gas regime at a site. It produces greater data accuracy leading to higher quality risk assessments. In the past readings taken using periodic measurements were often confused and misleading, resulting in erroneous conceptual site models and ultimately lost time and money.
Continuous ground gas monitoring identifies potential ground gas drivers early through multiple high frequency data sets, including ground gas concentrations and flow, atmospheric pressure, temperature and ground water level. Detailed analysis can then be performed in order to obtain a true understanding of the ground gas regime at a site. This consequently gives a higher level of confidence in the resulting conclusions and that an appropriate risk classification has been applied.
What benefits does the new continuous monitoring technology have for ground gas risk assessment?
As the number of new wave monitoring devices entering the market increases, the client is given more choice than ever when it comes to choosing an instrument. Developments like telemetry enables heightened data capture and long-term deployment, resulting in better quality data but also time and cost savings. Clients are less restricted as to the type of site conditions they are able monitor meaning services can be tailored to meet the needs of specific and complex sites.
When deciding which device is best suited to a site, it is important to consider:
- Is it discrete and secure enough to protect against theft and vandalism?
- Has it been developed by experts with an adequate level of experience?
- Does it fit into existing boreholes and well covers?
- Is the battery life adequate?
- Can it monitor the exact environmental conditions required?
- Do the sensors have the appropriate range and resolution?
- How quickly can it deliver the data?
These are just some of the considerations taken into account when producing the GasSentinel®. GGS’ exclusive in-house continuous monitoring instrument is a transportable, continuous, multi-gas analyser. With two-way telemetry, it is easy to use for both short term and long-term monitoring of landfill, contaminated land and onshore petroleum sites.
The GasSentinel’s® versatile remote data acquisition capabilities through an intuitive dashboard provide automated reporting for cost effective regulatory compliance.
The benefits of using the GGS Gas Sentinel® include but are not restricted to:
- Continuous gas concentration and flow monitoring
- Continuous barometric and borehole pressure, relative humidity and temperature monitoring
- Secure in-borehole installation
- High resolution sub-floor void monitoring
- Long battery life for extended site deployment
- Telemetry enabled device for remote data acquisition
- Compact transportable design
- Intrinsically safe design (certification imminent)
- Developed by experts with over thirty years of ground-gas contamination experience.
- British designed and made technology
What’s next for ground gas risk assessments?
It is clear that continuous ground gas monitoring has revolutionised ground gas risk assessment. Following a multiple lines of evidence approach, it allows for a detailed understanding of a variety of site conditions. New state of the art technology combined with continuous ground gas monitoring is increasingly resulting in cost-effective risk assessments that are delivered quickly and to a higher standard.
GGS is proud to be at the head of the industry providing leading edge technology and best practice techniques that meet client, regulator and community requirements.
Contact GGS today to discuss your requirements on 0161 232 7465 or click here for our enquiry form.
Find out more about GGS’ ground gas risk assessment services here.
Learn more about continuous ground gas monitoring here.