According to CIRIA, the ground gas monitoring rounds should:-
Encompass varying climatic conditions (specifically atmospheric pressure), including at least one period of falling pressure and one after/during heavy rainfall; Regular monitoring rounds over a period of stable conditions will determine the existence of variations in ground gas presence that are not due to changes in weather
Where regular fluctuations in the water table occur (e.g. in tidal regions), ground gas monitoring should be carried out throughout the cycle to determine influences on the ground gas regime and the presence or absence of a time lag in response to such water table changes.
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