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All, My experience is that the guidance is satisfactory but that consultants in a non-negligible number of instances either don’t understand it or apply it incorrectly. Commonest issues. 1.Number of monitoring rounds v worst case conditions being misunderstood (Regulators can be overly prescriptive here, but I’m sympathetic as we consultants often seem to struggle with the concept of falling pressure or evidencing it) 2. Up grading the risk from CS1 to CS2 based on one off peak/steady methane or carbon dioxide concentration results that marginally exceed the 1% or 5% thresholds rather than considering the source/CSM/type of result and whether this is justified. 3. CSM - frequently there isint a viable source and monitoring for gas occurs anyway. A marginally raised CO2 value occurs (as the borehole introduced some oxygen to the ground) with no flow and gas protection gets recommended due to issue 2. 4. Data collection - I’ve lost count of the number of sites I’ve seen with gas protection recommended due to flow rates that are an artifact of ground water being in the plain pipe work. Or where the gas concentrations sum to a lot more or less than a 100%. 5. Field staff training -Over the years I’ve asked a lot of field staff do you know why your doing this and know what the values your recording mean and frequently been told no. I won’t start on verification issues as I’ll explode. James James Wilson Fugro GeServices Limited [log in to unmask] Sent from ProtonMail Mobile On Fri, Mar 15, 2019 at 12:05, John Naylor <[log in to unmask]> wrote: > Hi Paul, All > > I’m probably coming at this from a slightly skewed angle as I tend to see quite a lot of the more difficult and challenging sites. Some of which don’t meet the expected behaviour as guidance is written and we can’t cover for everything. > > 1, C665 is over 10 years old – why not update it? I’d like to see Radon recognised more too! > > 2. Practitioners do tend to use the guidance correctly, they just rarely go beyond generic assessments and rudimentary CSM development. Ground gas can be very complex, and in a lot of instances, there just isn’t enough data (as in SI locations and other information) to provide enough confidence. Observation and measurement form a key element to justification. > > 3. Fit for purpose – they largely are. Over cautious approach – yes, particularly if you leave it at generic level and this is how its designed. It costs time and money to push to the next tiers. The outcome may still be they require gas protection, but at least you can look at the design requirements more closely. > > Proving the negative (as in you don’t need gas protection) rightly requires sufficient confidence in the understanding of the CSM and gas regime. This is why I think the default of CS2 is adopted under the precautionary principle where a potential pollution linkage exists. > > Installation of gas protection measures is improving, but still a long way to go. Verification is an important tool to improve standards and I think making a positive difference. > > Remember also that we do need to be cautious, with a sufficient factor of safety in mind. Let’s not ‘under risk’ ground gas either. We need strong practitioners (regulators and consultants) to keep this in mind. > > Kind regards > > John > > John Naylor |Technical Director > > T +44 (0) 161 232 7465 > > M +44 (0) 7856 244 224 > > E [log in to unmask] > > W[www.ggs-uk.com](http://www.ggs-uk.com/) > > [linkedin-grey-5](https://www.linkedin.com/company/ggs-) [twit-grey-2](https://twitter.com/GroundGas) > > Head officePythia House (Unit 10), Bamford Business Park, Hibbert Street, Stockport, SK4 1PL > > GGS is a proud member of the following organisations: > > [Logos July 2018 chop] > > From: Contaminated Land Management Discussion List <[log in to unmask]> On Behalf Of paul nathanail > Sent: 15 March 2019 10:50 > To: [log in to unmask] > Subject: Ground gases - a question: what's the real issue? > > Dear list, > > We have an opportunity to flag up our collective concerns at next week's National Brownfield Land forum. > > To help me accurately reflect the topic, i'd be interested to know if anyone thinks: > > 1. Ciria C665 needs updating > > 2. Practitioners are not using existing standards and guidance correctly > > 3. Current standards and guidance are no longer fit for their intended purpose and resulting in over cautious decisions > > Feel free to reply to the list as whole so all can see the suggestions. I will feedback the outcomes of next week's meeting. > > Thanks > > Paul Nathanail > > Geological Society rep on brownfield forum (& Deputy Chair of the Forum) > > Sent from my BlackBerry 10 smartphone. > > --------------------------------------------------------------- > > To unsubscribe from the CONTAMINATED-LAND-STRATEGIES list, click the following link: > https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CONTAMINATED-LAND-STRATEGIES&A=1 > > --------------------------------------------------------------- > > To unsubscribe from the CONTAMINATED-LAND-STRATEGIES list, click the following link: > https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CONTAMINATED-LAND-STRATEGIES&A=1 ######################################################################## To unsubscribe from the CONTAMINATED-LAND-STRATEGIES list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CONTAMINATED-LAND-STRATEGIES&A=1