Agenda: Efforts will be made today to free the jailed Corrib gas pipeline protesters. They have much local support behind them. . . and a few experts as well, reports Lorna Siggins

If and when Minister for the Marine Noel Dempsey approves installation of the Corrib gas onshore pipeline, he won't just be establishing a mineral exploration footprint in north Mayo. He will be sanctioning an environmental and public safety precedent for the exploitation of further gas and oil- related reserves off the Irish coastline for decades to come.

Experts are divided on the quantity of such reserves, but critics warn that this precedent will be highly hazardous, given that the Corrib gas pipeline was exempt from normal planning procedures and outside the remit of the Health and Safety Authority.

The proposed gas terminal or refinery was the subject of two Bord Pleanála rulings, but the pipeline was and is in the hands of the Minister for Marine and Natural Resources under the foreshore and gas Acts.

Public consultation was limited to an information meeting hosted and videotaped by one of Mr Dempsey's predecessors, Frank Fahey, in Geesala on July 25th, 2001.

It is for this reason that five north Mayo residents - retired schoolteacher Micheál Ó Seighin, whose most serious offence to date has been a £2 fine for not having a parking light on his car outside Healy's Hall in Glenamoy in 1965, and landowners Willie Corduff, Brendan Philbin, Philip and Vincent McGrath - have spent almost two weeks so far in Cloverhill prison for their defiance of a court order routing the pipeline through their property.

The men, to whom press access has not yet been permitted, are said to be in good spirits and still resolute despite being in a more mentally demanding environment than the physically harsh but beautiful blanket bog and seascape of the Erris peninsula.

Two are in one cell, three in the other. Local TDs Jerry Cowley and Michael Ring have visited them regularly.

Two separate applications to discharge the order made against the men are listed for the High Court today.

At protest rallies, held in Mayo, Galway, Ennis, Co Clare, and Dublin since their jailing, the men's families, supporters and critics of the project have highlighted the lack of information on safety aspects of the underground pipeline, and an independent assessment of same.

Such risks extend from the fact that the onshore pipeline landfall area will not be covered by a major State port authority which would have some monitoring capabilities to the fact that the route will be outside the responsibility of any State agency once the Minister has given consent.

In the Dáil on June 30th, Mr Dempsey promised an "independent monitoring and auditing regime which would be installed prior to any gas passing through the pipeline", but gave no further details.

Information commissioned by the Minister before approving the pipeline has been criticised for its lack of independence, conflicting data and omissions in relation to explosion risks by Prof Werner Blau, professor of physics at Trinity College, Dublin, and Brian Coyle, a Galway-based structural engineer.

The first review commissioned by the Minister was carried out by BPA, a company half-owned by Shell, and a second review, published on the Minister's website last week, was written by AEA Technology (AEAT), a company which does business with Shell.

AEAT was formerly part of the British Atomic Energy Agency - which sanctioned British Nuclear Fuel's Sellafield plant, Prof Blau points out. On this factor alone, it lacks public credibility, he says.

The Minister's department argues that it is "inevitable that any consultancy firm will have performed tasks for most if not all of the large multinationals" because of the limited size of the exploration sector. Prof Blau and Mr Coyle discount this.

"Investigators of pipeline accidents may be the best people to commission, and they tend to be independent of oil and gas exploration companies by their very nature," Mr Coyle says.

Such investigators know all about the risk of vapour cloud explosions (VCE), like that which killed 21 people and injured 131 in a series of blasts in the town of Ghislenghien outside Brussels last July. The high-pressure natural gas pipeline was jointly owned by Royal Dutch Shell and Suez Tractebel.

A 400m area was destroyed and the sound of the explosion was heard 10km away.

VCEs are caused by the ignition of fugitive flammable vapours or gases. Usually they occur in confined or congested areas, like the Flixborough petro-chemical complex in Britain or the Piper Alpha explosion in which 167 died in the North Sea in 1998.

The pattern is unpredictable when the leak occurs. One of the largest man-made non-nuclear explosions occurred in forestry and open lands in Siberia in 1989. A railway train several kilometres away from a leaking pipeline ignited a massive cloud of propane and mixed gas liquids, and it has been estimated that the explosion was the equivalent of 10,000 tonnes of TNT.

Significantly, VCEs and explosion risks are not covered in the reports submitted to the Minister beyond references to the risk of jet flames and flash fires in the immediate vicinity of a pipeline rupture. The AEAT report accepts the developer's contention that "over pressure risk" (developer-speak for explosions) is not a factor as Rossport is not a "congested" or industrial area.

In fact, the Bord Pleanála hearing into the terminal application (not the pipeline) did dwell on the risk of VCEs due to the proximity of a school, a public house and a forested area in the vicinity.

"A kid lighting a fag outside the school toilet on the day of a pipeline rupture would be enough to cause a VCE," a source involved in planning aspects of the Corrib project told The Irish Times.

Meteorological conditions are also not adequately dealt with yet Erris generally and Belmullet specifically are know as the windiest parts of Ireland.

Prof Blau, who is a part-time resident of Rossport, Co Mayo, says that due to the large energy content of transported gas and other substances such pipelines have a well-documented global history of failure.

The US Office of Pipeline Safety has recorded 1,586 incidents, including 61 fatalities, 235 injuries and over $408 million (€340.9 million) in property damage, for the 19-year period from 1986 to 2004.

He refers to risk-audit literature which states that a pipeline at a pressure of 68 bar will cause burn damage up to 610ft or 186m either side of its corridor. A "bar" or barometric pressure is equivalent to 14.5 pounds of pressure per square inch. The design pressure of the Corrib pipeline is 345 bar, giving a burn radius of at least 900m.

In two recent submissions to the Minister, Prof Blau questions the almost exclusive reliance on British design standards for the pipeline, and points out that as the pipeline is unprecedented - to use Mr Dempsey's own description in the Dáil last February - the probabilities explored in the quantified risk assessments (QRAs) and reviews of same fall outside the range of validated data.

He says the reviews contain omissions and selective choice of QRA input data.

Similar questions have been raised by Mr Coyle, who believes the proximity to houses breaches the Seveso II directive on transporting hazardous substances.

He says the technical literature, including the QRA and reviews of same before the Minister, haven't looked at key aspects of pipeline failure.

He also highlights a reference in the recent review published by the Minister on his department's website which says that the critical beach valve, which will control pressure on the landslide of the system if something goes wrong at the wellhead or in the Atlantic, "should have received specific attention" in the original QRA.

Shell E&P Ireland has stated in one of its daily bulletins since the jailing of the five north Mayo residents that the pipeline has been built to "world class standards", will never transmit gas at 345 bar, and will normally operate at a pressure of 120 bar. Bord Gáis pipelines transmit at a maximum of 70 bar.

In fact, one of the QRA reviews by Andrew Johnston confirms that the design pressure of 345 bar is to allow for a shut down situation, where an offshore well valve does not close tightly.

There's also the risk posed by other substances in the umbilical system attached to the Corrib pipeline, which will transport chemicals such as methanol from the refinery at Bellanaboy to the well-head, as well as transporting gas in.

Shell will not have total control over the transmission pressure as it owns the pipeline with two shareholders, Statoil and Marathon, which will be competing on the European market.

Dr Jerry Cowley believes that just as the government of the time accepted the assurances given by Gulf Oil on safety at the Whiddy oil terminal in Bantry Bay, site of the Betelgeuse disaster which claimed 51 lives just over 26 years ago, so little effort has been made by the authorities over the past five years to question information given to it by the developers of Corrib - Shell, Statoil and Marathon.

A truly independent and comprehensive safety and environmental audit of the €900 million project is imperative, he says. He also believes an offshore terminal is the only option.

Serious consideration of this option was urged by Bord Pleanála inspector Kevin Moore in his ruling in 2003 which turned down the first terminal plan,and it was also recommended in a report compiled for Erris fishermen back in 2001 by Dr Alex Rogers of Southampton University.

He said BP had floating facilities in deeper water than that of the 350m Corrib field off the west coast of Scotland.

Fr Kevin Hegarty, of Kilmore parish, one of the 10 priests from the Erris deanery who issued a statement expressing concern about the jailed men last week, believes the barrage of scientific evidence on both sides gives the Government just one option - an independent environmental, health and social impact study of the entire Corrib gas project, as recommended by him in the bi-monthly magazine Céide in April/May 2001.