Ballough AGI Bypass

Our team designed a new 85bar Above Ground Installation (AGI) and associated pipelines to bypass the existing Ballough AGI.  

Designed to reduce the strategic importance of Ballough AGI and allow for a future phase which would establish a two tier (85bar / 70bar) transmission network. The project also involves a number of modifications to the existing Ballough AGI and construction sequencing involving several stopple, gassing and de-gassing operations. 

Our scope included environmental and planning inputs, detailed mechanical, civil, structural, electrical and instrumentation design, supervision of site investigations and the PSDP role.  It also included support to GNI in  procuring materials and contract documents for the construction tender. Key technical challenges include various hot tap / stopple works (750mm and 900mm) and a trenchless crossing of the M1 motorway.

Key details

Project name:

Ballough AGI Bypass Project

Client:

Gas Networks Ireland (GNI)

Location:

Fingal, North County Dublin, Ireland

Services provided*:

  • AGI site selection and pipeline route selection
  • Preliminary and Detailed design (Civil, Mechanical, Electrical & Instrumentation, construction sequencing)
  • Assessment of alternative trenchless crossing methods for motorway & 110kV lines crossing
  • Site investigations design and supervision
  • Support to materials procurement process
  • Support to construction procurement process
  • Environmental Impact Assessment Report covering:
    • Ecology (including surveys and reporting) and practical recommendations to limit impacts on local biodiversity
    • Landscape & visual including impact assessment report, generation of photomontages and design
    • Flood risk assessment
    • Appropriate Assessment screening
    • oils, geology & land use,
    • traffic, air quality & climate, noise & vibration,
    • hydrology & drainage, and
    • material and waste management, biodiversity
  • Planning application
  • Draft Construction Environmental Management Plan (CEMP)
  • Support Gas Act application to CRU
  • Support Motorway Act application to TII
  • Engagement with statutory bodies including Fingal County Council, TII, ESB Networks and Eir
  • Project Supervisor for the Design Process (PSDP)
  • Chairing and reporting on HAZID / HAZOP process

 

Challenge

Located in Fingal, north Co. Dublin, Ballough AGI is is an important installation in the Irish Gas Transmission network.  A number of key strategic gas transmission pipelines enter  and  leave the site.  The M1 motorway and a 110kV overhead electricity line are also located adjacent to the site.  The general hinterland is low lying and the potential for flooding is a local concern.  Other local concerns included the extent of existing infrastructure in the area and the potential for further impact on homes and businesses.  Collectively, these constraints meant that finding a suitable site for a new installation to bypass Ballough AGI was challenging.   

Maintaining gas flows at all times while building a new AGI and bypass pipeline was also a key challenge for the project.  Various features were incorporated in the design to ensure that this can be done safely.

Ballough AGI Bypass Challenge.JPG

Solution

Our team carried out a site selection process for the new AGI and associated assessment of alternative routes for the bypass pipeline and other connecting pipelines. A total of thirteen sites were examined, followed by short-listing and final selection of the preferred site. 

Using GNI’s initial design concept, we developed a step-by-step construction process using a series of Engineering Line Diagrams. The final approach minimises the amount of degassing to atmosphere and ensures that there will be no interruption of gas supply during the works.  A total of nine hot tap operations will be required.

The final AGI design, which received planning approval in 2019, incorporates a raised platform to meet the requirements of the OPW and minimise the risk of flooding to the site.  Surface water management at the site will involve an attenuation feature which has potential to be enhanced with biodiversity features.

A range of protective measures and requirements for the development (and captured in the outline CEMP) have been recommended to ensure the protection standard measures for surface water management and Biodiversity. These include the undisturbed retention of a riparian zone with clearly demarcated silt-fence, 10 metres back from the Ballough River to minimise disturbance to banks and in-stream habitats, and a prohibition on the soil stockpiles beyond that. Furthermore, works in the area will be scheduled to coincide with dates that will be approved by IFI and/or other agencies

Project timeline

  • November 2017

    Project commences 

  • April 2018

    Preliminary Design complete

  • June 2019

    Detailed Design complete

  • August 2019

    Planning permission granted

  • March 2020

    ‘For Construction’ Documents issued and Preconstruction surveys commenced 

  • May 2020

    Anticipated construction start

  • November 2020

    Anticipated construction completion

1 /07
November 2017

Project commences 

April 2018

Preliminary Design complete

June 2019

Detailed Design complete

August 2019

Planning permission granted

March 2020

‘For Construction’ Documents issued and Preconstruction surveys commenced 

May 2020

Anticipated construction start

November 2020

Anticipated construction completion

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