Engineers Journal I Volume 63: Issue 4 I May 2009
An aerial view.
Corrib Gas terminal sets environmental management standard in construction The environmental management standards for the Corrib Natural Gas Project’s onshore terminal are amongst the highest in the world and are carefully controlled by a comprehensive environmental management system, recently rated class-leading among Shell’s global construction activities, writes Liam Dunne
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he Corrib gas field is located in the Slyne Trough, some 83km off the County Mayo coastline in 350m of water. The field contains high-purity natural gas with very small amounts of hydrocarbon liquids and water. It is being developed by Shell E&P Ireland Ltd. (SEPIL) and its partners Statoil Exploration Ireland Ltd. and Marathon International Petroleum Hibernia Limited as a long-range sub-sea tieback to the shore (i.e. sub-sea wells connected together and joined to shore by a sub-sea pipeline). The gas will be received and treated to meet sales gas specification in the onshore terminal at Bellanaboy Bridge. The purpose of the terminal is to process gas, treat the fluids received and control the operation of the gas field. The gas is processed at the terminal to meet the gas network transmission specification set by Bord Gáis. Prior to construction of the terminal, the site was prepared by removing 450,000 tonnes of peat. The peat was transferred to a former Bord na Móna peat extraction deposition site at Srahmore, near Bangor Erris. This was completed in two phases, the second phase involving the transfer of 350,000 tonnes in a 12-week period and
requiring 20,000 round trips covering 500,000km. The exercise was completed six weeks ahead of schedule and without any safety or environmental incidents. Integrated management PM Group (PM) is employed as construction management contractor (CMC) by SEPIL. Effective management of the construction site has been achieved by combining elements of the PM and SEPIL site management teams. An integrated structure was developed, making best use of the resources of both teams. A number of SEPIL people, including HSE, QA/QC and engineering personnel, were seconded to the PM construction team. This combined team approach enables efficient delivery of the project by encouraging an open and non-confrontational culture. Environmental excellence The Environmental Management System, under the control of the Site Environmental Manager, is driven by a team of ten personnel - two environmental advisors, an Axonics (Waste Water Treatment) plant engineer assisted by two
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A diagram showing the major elements of the project.
The Axonics plant.
operatives, two general operatives monitoring the site environmental facilities and two dedicated personnel who manage all waste generated on site. The planning conditions set down by Mayo County Council for construction of the terminal are strictly monitored. Potential environmental effects from the project include visual impact, traffic, noise, air and water quality, however, there are detailed mitigation measures and controls in place. The environmental management system in place at the terminal was audited internally last year against Shell’s industry leading standards. The terminal was rated classleading among Shell’s global construction operations and the systems and documentation developed on the Bellanaboy site have since been recommended for use on all Shell construction sites. Management through monitoring It is the responsibility of the CMC to ensure surface water, ground water, dust, noise and vibration levels do not exceed authorised limits. The environmental monitoring team record information from a strategic array of testing points in and adjacent to the site. Samples collected at the monitoring points are analysed in the laboratory on-site and by a fully accredited facility off-site. All results are posted fortnightly on Mayo County Council’s website. Erris water supply The Bellanaboy Bridge terminal site lies within the catchment area of Carrowmore Lake, which is the source for the Erris Regional Water Supply Scheme. Mayo County Council set the standard for construction site water run-off at close to
drinking water quality levels and put a strict enforcement regime in place. Prior to construction the water quality in local rivers and Carrowmore Lake was established through a detailed baseline study allowing criteria to be established for run-off and drainage from the terminal site. Surface and ground water quality will be monitored for the duration of the project. Water management The construction site has been set up and is operated to the highest standards including measures such as dedicated refuelling areas, bunding of all tanks, use of trip trays and segregation and storage of waste. Rainwater that falls on any part of the construction area is intercepted and treated using electro-flocculation to ensure full compliance with strict water quality limits. Settlement ponds capable of handling storm rainfall conditions are linked to the internal drains to allow potential silt to settle out prior to releasing water into local watercourses. The quality of the discharge water from the silt ponds is monitored continuously. Axonics technology Treatment of all surface water occurs in the Axonics plant. This plant, the largest of its kind in the world, is capable of treating over 1,000 m3 of surface water per day. It has been specifically designed to meet the Mayo County Council discharge limits for turbidity, aluminium content and suspended solids. The Axonics plant uses an electrochemical treatment process involving the use of electricity and small quantities of chemicals to remove fine particles from the
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water. The first stage involves inducing an electrical charge into the mineral rich water that causes the particles to attach to each other. The particles are then chemically treated to form larger grouped particles known as flocs. The water containing these grouped particles is then passed into a large settling tank known as a clarifier where settlement of the particles occurs in the bottom of the tank and the cleaner water on top is discharged as treated water. The larger mass of particles that settles out is also treated on site using a dryer, which literally spin-dries the material, reducing its volume and making it easier to handle. A dedicated plant engineer who is supported by two fulltime maintenance operators manages the plant and specialist contractor staff as required. The treated water from the plant is monitored round the clock and if the discharge from the plant exceeds the limits set the water is returned for further treatment. Emergency response An emergency response framework operates on site to alleviate the risk of any potential environmental emergencies. In addition to permanent spill kits strategically placed around the site, all mobile plant must have a spill kit. As part of site induction all contractors and sub-contractors are made aware of the site rules for dealing with spills. An emergency response team consisting of representatives from every contractor working on site carry out bi-monthly training exercises. The emergency response team are trained to assess a situation and, where safe to do so, contain the situation and minimise release.
The water sampling point.
Communications The terminal environmental manager prepares and presents a report to each meeting of the project monitoring committee (PMC), which was established as part of the planning conditions to ensure regulatory control during the development. The PMC comprise two representatives of the developer and two representatives of Mayo County Council, the North West Regional Fisheries Board, the Department of the Environment, Heritage and Local Government, the Environmental Protection Agency and two representatives of the local community. PMC meetings are also attended by the Department of Communications, Energy and Natural Resources, An Garda SĂochĂĄna and Bord Na MĂłna. The first PMC meeting was held in December 2004 and the committee convenes bi-monthly. The meetings serve the purpose of addressing any issues, updating members on the progress of works on site and providing a forum for discussion of local issues such as employment, grant allocations, including the third-level scholarship programme, and the social investment scheme. The social investment scheme is part funded by all the contractors on site as well as the Corrib Gas Partners. External site inspections Regular site inspections are carried out by Mayo County Council and meetings are held, both on- and off-site, to review environmental aspects of the development. During site inspections SEPIL staff accompany Mayo County Council staff to deal with any issues that may arise and to take duplicate water samples for comparative purposes. Any concerns are noted, followed up and closed out. The North Western Regional Fisheries Board and members of the PMC also visit the site on an occasional basis.
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Informing the community A public information office has been established by the project in Belmullet where members of the public are free to drop in to view project documents including results of environmental monitoring at the site. The office also operates a free phone service where members of the public can request information or raise any issues they may have about the project. Public notices are published regularly in all the local newspapers outlining details of works, including environmental works, being carried out on the project and any issues of relevance to the local community. A project newsletter is published bi-monthly dealing with topics including environmental issues that are of relevance to the general public. DVDs are also distributed periodically to update the community on the status of the project and to show the status of construction, including environmental matters. SEPIL encourages the local community to visit the site regularly by organising monthly local tours. Participants are presented with a general site update, a tour of the terminal and are given the opportunity to have a question and answer session with members of the terminal management team. No room for complacency Whilst the Corrib Project has an enviable record of environmental management to the highest standards, the team can never afford to be complacent. The Corrib team believes that the experience of this project will bring longterm performance benefits for all of the contractors involved and for the Irish construction industry as a whole, and looks forward to delivering a world-class plant in the near future.
Liam Dunne, PM Group, works as a project engineer with the Corrib Gas Terminal Construction Management Team. A manufacturing engineering graduate from DIT, Bolton Street, Liam completed the graduate management training programme with Smurfit Kappa Group before taking up a role as safety and quality manager with Smurfit Kappa Irish Paper Sack. Liam joined PM Group in 2007 and is currently responsible for development of the project Safety File and day-to-day monitoring of completion of the mechanical contract on the Corrib Gas Terminal. PM Group is an international provider of professional services in engineering, architecture and project management. Headquartered in Ireland, PM Group’s 1,800-strong, multi-disciplinary teams deliver complex capital projects to clients in the Biopharmaceuticals; Advanced Manufacturing; Medical Technologies; Energy, Food and Nutritionals; Research and Development; Transportation; Healthcare; Education; Environmental and Commercial sectors.
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