Earlier this month, we hosted the first of three Technical Briefing Webinars on ground gas presented by Steve Wilson of EPG. In this webinar, Steve presented a number of case studies where an argument for no (or reduced) ground gas protection has been successfully built and justified by correctly following BS8485. In particular, the need for a robust Gas Conceptual Site Model (gCSM) was highlighted; one that is supported by multiple lines of evidence and not simply reliant in the derivation of often erroneous Gas Screening Values. One of the lines of evidence relied upon were Ternary Gas Composition Plots as discussed and defined in Ground Gas Information Sheet No 1. Ternary plots provide a simple graphical approach to examining your ground gas data and investigating the potential for differences in the nature and source of the gas encountered at different locations and areas.
LQM would now like to announce the release of a Ternary Gas Composition Tool which makes producing and interrogating your gas data within a Ternary plot quick and easy. Like our other tools this Excel Spreadsheet does all the time-consuming work for you; simply cut & Paste in your data and the tool will instantly generate 3 different ternary plots that can be used as figures in your report to provide direct, science-based justification for your interpretation of the gas regime at a site. The tool includes multiple filter fields that allow you to interrogate the data within the ternary plots to explore differences in the gas composition with for example, depth, zone or landuse, etc.
In some of the case studies presented in the webinar, ternary plots provided part of the evidence necessary to justify why gas protection measures were not need (i.e. CS1) to provide sufficient protection at sites where carbon dioxide exceeded the trigger value of 5% cited in BS8485. Where this elevated carbon dioxide is likely to be the result of limited and localised microbial respiration, it is unlikely that any substantial advective flow into a structure is possible. Consequently, consultants armed with a Ternary plot can provide robust evidence that the risks do not warrant the increase to CS2 allowed for within BS8485. This can provide client’s with a considerable cost saving but more importantly promotes the science-based redevelopment of such sites in a sustainable manner avoiding the costly conservatism that can result from the blind and uneducated application of BS8485. In other cases they demonstrated that ground gases detected on site were the result of landfill gas migration and dilution rather than on-site generation.
The LQM Ternary Gas Composition Tool is now available for purchase. If you are interested, please visit our website https://www.lqm.co.uk/products/gastool1/ for more details of just how simple it is to use. Purchases are by online card payment only, to minimise procurement effort for you and us. Just like the tools in our PAH Toolkit, the price includes personalisation with a logo of your choice on the graphical ouputs. Once we receive you order, we will email you with a logo specification and send you your personalized version as soon as possible by email.
P.S. Due to demand, recordings of the first Technical Briefing Webinar (Ground gas) entitled “Correct application of BS 8485” are also now available from our website.
P.P.S. Steve Wilson will be discussing advanced methods of data analysis of continuous gas monitoring datasets in his 7th June 2019 webinar in which ternary plots can provide a useful line of evidence.