Synopsis
Brief Synopsis
‘In the evening of Wednesday 23 May 1984, a group of 44 people including 8 employees of the North West Water Authority, was assembled in a valve house set into a hillside at the outfall end of the Lune/Wyre Transfer Scheme at Abbeystead’ (HSE, 1984).
‘The visitors, mainly from the local Parish of St Michaels on Wyre, were attending a presentation being part of a programme to allay local residents' anxieties on the effects of the installation on the winter flooding of the lower Wyre Valley’ (HSE, 1984).
‘As part of this presentation, water was to be pumped over the weir regulating the flow of water into the Wyre. Shortly after pumping commenced, with the visitors congregated in the valve house which was virtually underground, there was an intense flash, followed immediately by an explosion causing severe damage to the valve house’. ‘Sixteen people were killed; no one escaped without injury from the valve house’ (HSE, 1984).
‘The Health and Safety Commission directed the Health and Safety Executive to investigate and to make a special report in accordance with Section 14(2)(a) of the Health and Safety at Work etc Act 1974’ (HSE, 1984).
Unknown photographer, image from (BBC, 2014).
Courtesy of the Health and Safety Executive (HSE, 1984).
Courtesy of the Health and Safety Executive (HSE, 1984).
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Courtesy of the Health and Safety Executive (HSE, 1984).
Courtesy of the Health and Safety Executive (HSE, 1984).
Courtesy of the Health and Safety Executive (HSE, 1984).
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Further information hoping to be identified and still to be located.
Main findings, key lessons & areas for learning
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Fire & Rescue Service summary of main findings, conclusions, key lessons & recommendations;
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FBU summary of main findings, conclusions, key lessons & recommendations;
Further information hoping to be identified and still to be located.
Other report summary of main findings, conclusions, key lessons &recommendations;
Taken from; The Health and Safety executive. (1984). The Abbeystead explosion; a report of the investigation by The Health and Safety Executive into the explosion on 23 May 1984 at the valve transfer house of the Lune/Wyre water transfer scheme at Abbeystead. (pdf). Her Majesty’s Stationary Office. ISBN 0 11 883795 8
Conclusions
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103 The explosion was caused by ignition of a mixture of methane and air which had accumulated in the wet room of Abbeystead Valve House. The methane had been displaced from a void which had formed in the Abbeystead end of the Wyresdale Tunnel during a period of 7 days before the explosion when no water was pumped through the system. When pumping was resumed on 23 May 1984, while the visiting party was inside the Valve House, the water level in the tunnel rose slowly and pushed out the methane and air mixture in the void through the air valves near the end of the tunnel. Most of the air/gas mixture passed through the eight air valves mounted above the access end of the tunnel into a closed vent chamber, from where it flowed through a large open vent pipe into the
Valve House.
104 The design of the Lune-Wyre Link was novel in certain respects for the water supply industry. Its most unusual feature in relation to the explosion was the dis charge of water and vented air from the tunnel into an enclosed Valve House situated below ground. Although ventilation ponds were installed in the external wall of the Valve House, they were not so positioned nor of such a size as to disperse the volume of gas which arose on the night of the explosion. lf a water discharge sys tem open to atmosphere had been used, an explosion would almost certainly not have occurred.
105 No source of ignition for the explosion has been positively identified. Thorough examination and testing of the electrical equipment has not revealed any faults likely to have ca used ignition and there is insufficient evidence to confirm any of the other explanations which have been considered. Smoking in the Valve House was not prohibited because the likelihood of a flammable atmosphere arising there had not been envisaged.
106 The void in the tunnel was produced by loss of water through a washout valve at Abbeystead which had been left permanently open to minimise silt accumulation in the end of the tunnels beyond the Valve House. A maximum loss of water, approximately 1.5 Ml, was possible through this washout although the evidence indicates that the actual loss at the time of the explosion was between 0.97 Ml and 1.42 Ml. A void of the same order of magnitude would be created in the tunnel, which had been designed to remain full of water at all times, except when drained intentionally for maintenance or inspection.
107 Use of the washout valve m the way described in the previous paragraph was not in accordance with the operating manual provided by the designers of the sys tem. It had been introduced a year or two after the system became operational, apparently without the knowledge or approval of senior operational and technical staff employed by the NWWA. If more detailed operating instructions had been issued and stricter working procedures followed the change in the use of the washout valve might have been detected, but the possible disastrous consequences of the new procedure would almost certainly not have been recognised by anyone operationally involved.
108 Almost all the methane was of ancient geological origin, although small quantities probably arose from decomposition of organic matter in the tunnel. Most of the methane percolated in through the concrete walls of the tunnel bet ween 2 and 2.5k m from Abbeystead , either in a gaseous form or in solution in water under pressure. The fact that significant quantities of methane might be dissolved in water does not appear to have been recognised by the personnel concerned with the design and operation of the Lancashire Conjunctive
Use Scheme, and probably not by the water industry generally. Information obtained in the course of the enquiry indicates that it has been widely regarded as an insoluble gas, its solubility under normal atmospheric conditions being very low. References to the presence of dissolved methane in water supply systems have been traced in published literature but they do not appear to have achieved wide circulation, particularly amongst the sections of the Civil Engineering Profession concerned with water supply schemes.
109 On the strength of their experience during the driving of the tunnel, both Binnie and Partners and the NWWA believed, and still believe, that methane was not emerging from the strata in quantities which were significant. During the construct ion period, some testing for methane was carried out in accordance with standard contract clauses for safety in the construction operation. The results of those tests which were carried out showed on three occasions what might have been very low levels of methane. But the instrument used was susceptible to other gases likely to be present and the readings therefore cannot be regarded as confirming the presence of methane; in addition the majority of the tests were carried out when forced draught ventilation was in operation.
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Recommendations
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110 The recommendations concerning design, construction and operation are intended to apply to TUNNELLED RAW WATER TRANSFER SYSTEMS which are not of water tight construction. They also apply to closed raw water transfer systems in which methane is liable to be generated. They do not apply to treated water distribution systems using watertight pipes.
Design and construction
111 Systems conveying water should be so designed that any air or gas discharged , either during filling or at any other time, is vented to a safe place in the open air.
112 Where it proves impracticable to comply with Recommendation I in a particular case, comprehensive tests should be made to ascertain the nature of any contaminants which might enter the system or be generated in it, and appropriate precautions should be incorporated in the design to deal with them.
113 The controls for washout valves should either be so located that they cannot be operated by unauthorised persons or should incorporate arrangements for the valves to be locked in the closed position.
114 During tunnelling work, sufficient tests should be carried out at frequent and regular intervals to establish the presence or otherwise of flammable gases using instruments able to provide a quantitative reading of acceptable accuracy. On completion, and before the commissioning of any tunnel forming part of a water transfer scheme, further tests for flammable gas should be carried out with no ventilating system in operation. The results of such tests should be recorded and retained; positive results should be reported immediately to the designers of the installation and to the organisation which will be responsible for its operation.
Operation
115 Operators of existing raw water transfer systems should review the possibility of methane being present in the system and, where appropriate, should consult with the designers in assessing the safety of the installation, particularly where significant voids may be formed in the system.
116 Safe systems of work covering all aspects of operation and maintenance should be laid down in comprehensive operational instructions, the observance of which should be monitored by management.
117 The training of operating. Technical and supervisory staff concerned with water transfer systems should include measures to ensure that they are made fully aware of the significance of any special features of the installation with which they are concerned, any potential hazards which may be anticipated in the course of operations and the appropriate precautions to deal with the hazard.
General
118 The fact that methane is soluble in water and increasingly so above ambient pressure, and that it can be given off by ground water entering workings, should be widely publicised throughout the civil engineering profession and incorporated in professional training courses.
Action by HSE
119 Following the Abbeystead explosion, HSE wrote to water authorities alerting them to the possible dangers of water transfer and comparable systems where methane may create a risk.
120 Interim advice on the risk of gas evolution at water boreholes has been produced for the guidance of users.
121 Further advice on the wider aspects of methane evolution from ground water is being prepared.
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Further information hoping to be identified and still to be located.
IFE Commentary & lessons if applicable;
None produced at this time.
Known available source documents
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FRS Incident Report/s;
Further information hoping to be identified and still to be located.
FBU Incident Report/s;
No information identified to date and/or still to be located.
Health & Safety Executive (HSE) Incident Report/s and/or improvement notices;
The Health and Safety executive. (1984). The Abbeystead explosion; a report of the investigation by The Health and Safety Executive into the explosion on 23 May 1984 at the valve transfer house of the Lune/Wyre water transfer scheme at Abbeystead. (pdf). Her Majesty’s Stationary Office. ISBN 0 11 883795 8
Further information hoping to be identified and still to be located.
Known available source documents
Further information hoping to be identified and still to be located.
FRS Incident Report/s
No information identified to date and/or still to be located.
FBU Incident Report/s;
No information identified to date and/or still to be located.
Health & Safety Executive (HSE) Incident Report/s and/or improvement notices;
The Health and Safety executive. (1984). The Abbeystead explosion; a report of the investigation by The Health and Safety Executive into the explosion on 23 May 1984 at the valve transfer house of the Lune/Wyre water transfer scheme at Abbeystead. (pdf). Her Majesty’s Stationary Office. ISBN 0 11 883795 8
Further information hoping to be identified and still to be located.
Lancashire Constabulary Incident Report/s
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North West Ambulance Service Incident Report
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Building Research Establishment (BRE) Reports/investigations/research;
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Coroner’s report/s
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Dear Chief Officer Letters (DCOL), FRS Circulars, FRS Notices and/or Bulletins etc and/or Related Government Correspondence.
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Notifications from National Operational Learning User Group (NOLUG) and/or Joint Emergency Services Interoperability Principles (JESIP).
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Other information sources
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Service learning material
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Videos available
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BBC. (2014). Abbeystead disaster: what on earth caused this blast? [online]. Available at http://www.bbc.co.uk/news/uk-england-lancashire-27506941 Accessed 30th November 2016.
Website links to relevant information if available
Further information hoping to be identified and still to be located.
Wikipedia. (unknown date). Abbeystead disaster. [online]. https://en.wikipedia.org/wiki/Abbeystead_disaster Accessed 30th March 2017.
Lancaster Guardian. (2014). Abbeystead 30 years on: what went wrong? [online]. http://www.lancasterguardian.co.uk/news/abbeystead-30-years-on-what-went-wrong-1-6631461 Accessed 30th March 2017.