Dáil Éireann - Volume 598 - 24 February, 2005

Written Answers. - Gas Pipelines.

[970]   113. Mr. Ring asked the Minister for Communications, Marine and Natural Resources if it is considered satisfactory that the onshore pipeline design for the gas terminal (details supplied) in County Mayo is an upstream pipeline that will carry raw, untreated odourless gas when Bord Gáis Éireann does not operate upstream pipelines and only transports clean odorised gas where mercaptan has been added for smell as a safety measure. [6374/05]

  114. Mr. Ring asked the Minister for Communications, Marine and Natural Resources if it is considered satisfactory that the onshore pipeline design for the gas terminal (details supplied) in County Mayo does not conform to IS 328:2000, the code of practice for gas transmission pipelines and installations, as operated by Bord Gáis Éireann. [6375/05]

  115. Mr. Ring asked the Minister for Communications, Marine and Natural Resources if it is considered satisfactory that the onshore pipeline trench connecting the wellhead to the refinery at the gas terminal (details supplied) in County Mayo will carry an upstream pipeline of 20 in. in length, a waste pipe of 10 in. and umbilical cable operating at pressure of 610 bar, when Bord Gáis Éireann carries just one pipe in its trench lines. [6376/05]

  Mr. N. Dempsey:I propose to take Questions Nos. 113 to 115, inclusive, together.

At the outset, I inform the Deputy that the questions posed by him in regard to the design of the upstream pipeline compared to the design of the transmission pipelines used by Bord Gáis Éireann do not compare like with like.

Transmission pipelines used by Bord Gáis Éireann are designed using IS 328. In the case of the Corrib onshore gas pipeline, BS8010 is used for the design code. IS 328 has been used as a supplement to BS8010 where it was considered beneficial. Design codes in general allow themselves to be supplemented by other similar codes where they are either silent or do not provide clear guidance. What is not normally permitted is for sections of one design code to be substituted by another one.

The Corrib onshore pipeline has certain design considerations, which are unusual and unique both within Ireland and also within Europe, and for this reason there is no direct precedent. The design requires consideration to be given to the choice of design code best suited to the project. The Corrib export pipeline has, for the onshore section, an extremely high design pressure of 345 bar. Thus, the pipeline is well above the normal design pressure experienced for onshore distribution gas pipelines. This has resulted from the [971] relatively rare occurrence where the pipeline is connected directly to the producing wells and not via an intermediate platform or processing facility as happens in most other cases.

Since the onshore pipeline has no direct precedent either within Ireland or elsewhere for the reasons stated above, it is clear that strict use of the Irish design standard applied to all Bord Gáis Éireann transmission and distribution pipelines, IS 328, results in a design that is not optimised for wall thickness and less practical to construct.

The Deputy is aware that an independent evaluation of the onshore pipeline design code was commissioned by my Department. This was carried out by Mr. Andrew Johnston, an experienced petroleum pipeline consultant. His report, Corrib Gas Pipeline Project: Report on Evaluation of Onshore Pipeline Design Code, was submitted to my Department on 28 March 2002 and its recommendations have been included as conditions attaching to the consent to construct pipelines issued in April 2002.

Mr. Johnston concluded as follows: the pipeline design code has been selected in accordance with best public safety considerations and is appropriate for the pipeline operating conditions; the design of the onshore pipeline is generally in accordance with code selection and best national and international industry practice, provided that the actions recommended in section 2.2 of his report are followed; the pipeline is considered to be adequately protected from third-party interference by burial to 1.2 m and provision of marker tape above the pipeline; and the pipeline is considered to meet public safety requirements as outlined in the selected design code, provided that the actions recommended in section 2.2 are followed. As stated above, the recommendations of section 2.2 have been incorporated in the statutory approvals issued for the Corrib pipeline development. I have forwarded a copy of Mr. Johnston’s report to the Deputy.

I should also point out that the upstream pipeline will be buried in a trench generally of 2 m in depth adjacent to the umbilical and the waste pipe in the same trench. While the umbilical will carry high-pressure liquids the volumes are very small and the umbilical will also be buried to a depth of 2 m so these liquids will pose no threat to people in the area.