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Thanks Jeremy, not much help though I’m afraid. To add some more information: Response zone is not submerged Maximum methane recorded during gas monitoring is 17.7%v/v At STP the maximum solubility of methane in water is around 21.5mg/l We are getting results of around 130mg/l in the retest, previous results were in the region of 600mg/l!! No bubbling has been recorded in the well, and even if free methane was present, the results still don’t make sense. No fracking is taking place in the vicinity of the site. From: Jeremy Head [mailto:[log in to unmask]] Sent: 22 February 2017 08:47 To: Sarah Haines <[log in to unmask]> Cc: [log in to unmask] Subject: Re: supersaturated methane in groundwater? Hi Sarah The attached may be of use, I hope it is helpful. Regards Jeremy Head On Wed, Feb 22, 2017 at 8:08 AM, Sarah Haines <[log in to unmask]> wrote: Dear all – I have a conundrum. Have any of you experienced dissolved methane results that not only exceed the saturation limit for methane in groundwater, but also are equivalent to 300%+v/v methane in air when Henry’s Law is applied? If so, can you advise on the cause. Could there be something else in the GW affecting the results that is not picked up by standard GW analysis for volatiles etc.? Re-test has come back with similar results, the water is not saline, and is not taken from great depth, pH is normal. The site is an old landfill, with elevated methane & carbon dioxide. Hope someone can help, as the lab is not forthcoming. Thanks, Sarah -- Jeremy Head Needles Eye Rattlesden Road Drinkstone Suffolk IP30 9TL 01449 736 653 07980 698 683