Rates of oxygen-depletion in granular Lambeth Group strata and evidence for barometric pumping

Laboratory experiments have been performed to demonstrate significant levels of oxygen depletion within samples of Upnor Formation of the Lambeth Group deposits. These have been used to explain the reasons for several incidences of confined space hypoxia during underground construction within the st...

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Bibliographic Details
Published in:Quarterly journal of engineering geology and hydrogeology 2020-11, Vol.53 (4), p.645-654
Main Authors: Newman, T. G, Ghail, R. C
Format: Article
Language:English
Subjects:
Atmospheric pressure
Boreholes
Confined spaces
confining pressure
Construction
Depletion
Deposits
Dewatering
England
Environmental geology
Europe
experimental studies
gases
Geochemistry
geologic hazards
granular materials
Great Britain
ground water
Hypoxia
Laboratory experiments
laboratory studies
Lambeth Group
London England
Monitoring
natural hazards
Oxygen
Oxygen depletion
physicochemical properties
Pumping
rock, sediment, soil
Safety
sampling
site exploration
soil mechanics
soil quality
trace elements
Underground construction
United Kingdom
Upnor Formation
water table
Western Europe
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Summary:Laboratory experiments have been performed to demonstrate significant levels of oxygen depletion within samples of Upnor Formation of the Lambeth Group deposits. These have been used to explain the reasons for several incidences of confined space hypoxia during underground construction within the stratum beneath London. Further investigation, using a relatively small-scale field pump-out test, revealed the rapid effects of dewatering on the generation of hypoxic gas (within the ground) and that the amount of oxygen falls to fatal levels within a very short time after commencement of pumping. Monitoring of boreholes during ground investigation for the Thames Tideway Tunnel has indicated barometric control on the release of hypoxic gas from installations within granular deposits of the Lambeth Group, namely the Upnor Formation, as well as channel sand deposits within the Laminated Beds. In these, reduced levels of oxygen coincide with low and/or falling barometric pressure. Continuous 24-hour monitoring demonstrates that the reduction is almost instantaneous and has serious implications for the Health and Safety of underground construction personnel.
ISSN:1470-9236
2041-4803
DOI:10.1144/qjegh2019-177