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Aldridge defends safety position in wake of Shell ‘spin’

First let me welcome the statement by Minister Dempsey that the illegal pipeline at Ballanaboy will be totally removed. Perhaps this represents a recognition that the current proposed track of this ‘upstream’ pipeline is totally wrong, by the Minister and his staff. In reply to the continuing campaign of misinformation from Shell, including the letter from Gerry Costello criticising the findings contained in my original report concerning the level of hazard posed to people of Rossport, Pollatomish and the surrounding area ,I believe all the following is valid. Despite the howls of derision coming from Shell since my report was released, I, the author, continue to assert that the explanation and calculations described in it represent a fair statement of a likely outcome of a failure of this pipeline under the meteorological conditions specified, ie inversion and fog (zero wind) and that my conclusions are supported by the mass of published data in the US and in England by the UK Health and Safety Executive and others. The results in the report were never intended to be fine grained but rather to answer to the questions ‘How unsafe?’ and ‘How big a bang worst case?’ As a retired naval offier and member of the IEEE, the world premier engineering body, I am bound by it’s code of ethics which in part that state members are required: “to accept responsibility in making engineering decisions consistent with the safety, health and welfare of the public, and to disclose promptly factors that might endanger the public or the environment; to avoid real or perceived conflicts of interest whenever possible, and to disclose them to affected parties when they do exist; to be honest and realistic in stating claims or estimates based on available data; to reject bribery in all its forms; and to avoid injuring others, their property, reputation, or employment by false or malicious action.” A standard against which ‘Official Ireland’, or Shell, hardly measures up. If this pipeline is built, it has the potential to deliver a devastating blast amounting to the equivalent of some 4 kilotons of TNT. Shell is adding nothing constructive to the debate by attempting to rubbish my use of TNT as a reference material — this is standard international practice when evaluating the risks associated with the production and storage of hazards materials such as chemicals including petrochemicals. As for the comments on how I reached my conclusions, Shell has failed to fully comprehend the meteorological conditions (inversion) I specified as part of the worst case scenario on which my calculations are based, despite having been sent a draft copy of my report. Inversion is the atmospheric condition that causes smoke to not rise above roof top height, and to hang in the air near the ground. This happens in late winter during fog, and no wind. I concluded that under those conditions the escaping gas will be trapped in a layer up to 15 to 21 feet from the ground and will spread sideways until an ignition source is reached. As for the amount of gas released, Shell states in the EIS that the throughput of the refinery (and this pipeline) is up to 10,000,000 cubic meters a day. A calculation based on a throughput of 83 per cent of maximum at 345 barg shows that the time to release a weight of gas equivalent to the volume of the pipeline (93 Km as stated in the EIS) after the pipe is ruptured is between 6 and 12 minutes. If the pressure in the pipeline before the burst were down to 80 barg then the release time for this volume of gas increases to between 6.5 and 13 minutes. Since this upstream pipeline is unique as to gas characteristics and pressure as well as the intention to drive it through the middle of an inhabited area and despite all statements to the counter by Shell, there are no equivalent pipelines any were in the world and I consider the request for information on equivalent pipeline explosions just more Shell spin. However if Pyle and Costello are really that uninformed and have a month or so to spare, they should try Google-ing ‘Pipeline Explosions+High Pressure’. A good place to start would be the New Mexico explosion, operating on processed gas at much lower pressure, that hurled a 200-ton chunk of pipeline a considerable distance and left a number of people dead from that blast. It is my opinion that the scope of the current safety review is too narrow. That the key question remains: why, other than a desire to do the job on the cheap, is the gas not to be processed offshore? The current setup with the ‘refinery’ on-shore and connected with what amounts to 93 Km of ‘riser’ possesses the potential for a further failure mode. In the event that the inlet valve to the ‘refinery’ closes under emergency conditions, and a well-head pressure control valve fails, the pipeline through Rossport will be subject to the full pressure of the gas in the well, which Minister Dempsey stated in the Dail on October 4, 2005 to be ‘much higher ’ (than 345 barg). On this basis the upstream pipeline has a high probability of failure. Since there are, according to the published information, six valves (one per well), I estimate the probability of this happening as once in 12.82 years, a conclusion that is now incorporated to an updated version of my report. Yours sincerelyCapt Dave J Aldridge Charlestown, County Mayo,

Posted Date: 
14 November 2005 - 8:20am