BACKGROUND
Northern Gas Networks (NGN) own and operate the Lamesley Above Ground Installation (AGI) site at the Team Valley Trading Estate in Gateshead. This is adjacent to the A1 motorway and supplies natural gas, at varying pressures, to the local network.
NGN needed to move their existing infrastructure in preparation for the construction of the new A1 Improvement Scheme from: Allerdene Railway Bridge to Birtley Interchange – taking place between A1 junctions 65 to 67.
The scheme forms part of the wider Highways England strategy to upgrade the A1 Newcastle Gateshead Western Bypass, one of the most congested sections of motorway in the North East.
Works involved the improvement and widening of 6.5km’s of motorway and the replacement of the Allerdene railway bridge.
The existing NGN pipeline(s) and AGI were in close proximity to the proposed roadworks and needed to be relocated in advance.
The pipeline crossing the A1 needed to be upgraded to a new 600NB steel pipe buried at a greater depth with better geometric alignment to allow for the widening, repositioning, and new elevation of the A1 motorway.
This required demolition of the existing AGI at Lamesley, construction of 2 new AGIs and the diversion of 9 gas pipelines as follows:
- 1 x 450NB High Pressure (HP) steel main
- 5 x Intermediate Pressure (IP) mains
- 2 x Medium Pressure (MP) mains
- 1x Low Pressure (LP) main
ABOUT NGN
NGN delivers gas to over 2.7 million homes and businesses in the Northeast, Northern Cumbria and much of Yorkshire.
Over the next few years, they aim to replace over 3,800 km’s of old underground pipework with new modern pipelines.
SCOPE
Rayden Engineering Limited (REL) were employed in the role of Principal Contractor (under CDM 2015) to complete all necessary works of this vital national infrastructure project.
Due to its critical importance the work was assigned as Nationally Significant Infrastructure Project (NSIP) status, as defined by the Planning Act 2008. For further information please see – A1 to Birtley to Coalhouse Improvement Scheme.
A key factor of the pipeline diversion was to maintain security of gas supply and increase the wider health of the infrastructure by upgrading any aged pipework and equipment, where possible.
Project scope consisted of:
- Demolition, decommissioning & disinvestment of existing Lamesley AGI & redundant pipework.
- Construction of new Lamesley AGI on opposite side of A1 to South.
- Construction of new AGI (Governor Station) North of A1 at Allerdene (next to old Lamesley AGI).
- Construction of new HP & IP pipelines to supply new Lamesley AGI.
- Construction of a Microtunnel for pipeline route under A1.
- Construction of new MP & IP pipelines from new Lamesley AGI to local network & to new Allerdene AGI.
- Construction of new LP, MP & IP pipelines from the new Allerdene AGI to the local network.
- Construction of new LP pipeline for Coal House Roundabout to replace existing.
- All Existing pipeline to be replaced with new, upgraded 600mm diameter pipework buried at greater depth.
All new pipework was constructed in accordance with IGEM/TD/1 Edition 5 and other applicable NGN specifications that were required.
Ariel view of A1 Birtley to Coalhouse Gas Pipeline Project
SERVICES DELIVERED
Two new AGIs
The existing AGI at Lamesley was demolished and a new upgraded replacement AGI was constructed on the opposite side of the A1 (to the South).
This comprised of two sets of regulators to carry out pressure reduction across two pressure tiers (IP and MP), new filters, new metering skid, a boiler house package, new heat exchangers, a backup generator and electrical and instrumentation kiosk.
Work also included a connection to facilitate a future CNG filling station.
A second smaller AGI (Governor Station) was constructed North of the A1 at Allerdene (next to old AGI).
This provided gas to the Team Valley Trading Estate and the Low Fell area of Gateshead. This AGI comprised of two sets of regulators (IP/MP and IP/LP) and a new electrical and instrumentation kiosk.
New pipeline underneath A1
A new 600NB IP pipeline was constructed and diverted underneath the A1 using the microtunnelling trenchless system.
To mitigate any risk of surcharge loading from the proposed new embankment of the motorway, the new pipeline, in sleeve tunnel, was positioned at much greater depth than normally required.
The new pipeline was 300m long in total with just over half of this, running through the tunnel section so works could easily accommodate A1 widening. This was routed between the foundations of the new road bridge and included two 6m deep reception / receiving shafts.
This new pipeline was connected to a new Allerdene and Lamesely AGIs.
Once the tunnel had been constructed and the two new AGIs were commissioned, work involving the abandonment and diversions of the HP, IP, MP and LP pipelines was carried out.
Material “won” from any work completed on site was recycled for use throughout the project, where possible.
Once all phases of work were complete the site was backfilled and reinstated.
Plan of works completed
REL completed the following works:
- Completion of full Ground Penetrating Radar (GPR) & geometric survey of site for intended works.
- All civil works required to construct pipeline diversion including excavation, backfill & reinstatement.
- Excavation works to tie-in locations to perform P18 works.
- Diversion & tie-in of existing 17 bar 450mm pipeline into the new Lamesley AGI (welding to NGN/SP/P/2 NDT to NGN/SP/NDT/2).
- Prefabrication, welding, testing, installation, coating & painting of all pipework.
- Construction of a Microtunnel under the A1 motorway approx. 160m long and 1.2m diameter using a closed face Microtunnel Bore Machine (MTBM).
- Installation of precast concrete to build structural tunnel sleeve with newly diverted gas pipeline inserted.
- Laying of new 600mm IP pipeline from new Lamesley AGI & to Allerdene AGI including insertion into micro tunnel sleeve under A1.
- All pipework was tested to the relevant standards/specifications & dried where applicable.
- Welding at Hot Tap locations included material sampling (Q/10) and construction, testing/installation of any required bridle/bypass pipework.
- Removal of redundant pipelines where possible & compaction of ground after removal was to specifications requested by Highways England.
- Where pipelines could not be removed, they were grout filled, i.e. existing pipelines underneath the A1.
- Fabrication, welding & testing M & LP pipework, hot taps & bypasses.
- All welding on HP pipeline was to NGN/SP/P/2 (2018) & for I, M & LP pipelines to NGN/SP/P/1 (2019).
- Hot tap welding was to NGN/SP/P/9 (2019).
AGI works included:
- Demolition of old Lamesley AGI site including removal & disposal of all pipework & redundant equipment (above & below ground).
- Demolition of redundant transformer & regulator buildings.
- All civil works required to construct the new Allerdene and Lamesley AGIs, including all excavation works, buildings, concrete bases & pipe supports, skid units, filter bank, heat exchangers, E&I kiosk generator, transformer & meter kiosk..
- Ground of existing Lamesley AGI site was graded & levelled using site won materials.
- 90% of pipework was prefabricated off-site at the REL HQ workshop & then installed on-site to agreed designs & programme.
- Welding within AGIs was to NGN/SP/P/8 (2017).
- Prefabrication & installation of all pipe supports for new pipework.
- Installation of all new pipework & painting in accordance with NGN/P/A/10 and CW5 specifications.
- Construction of new access roads & paths.
- Supply & installation new perimeter fencing for AGI.
As principal contractor under CDM REL also provided:
- A dedicated project management team – including site-based staff such as: Project Manager, Project Engineer & Site Manager along with REL office-based personnel including a Contracts , Commercial, Procurement, QHSE Managers, admin & document control.
- RELs project management system was implemented to enable effective planning, scheduling, cost & document control & collaboration with NGN.
- Management, organisation & control of subcontractors & suppliers.
- Project accommodation & site welfare in line with The Workplace (Health, Safety and Welfare) Regulations 1992 (L24) & NGN/PM/EHS/12 procedure.
- Design of all temporary works, including installation of new diverted pipelines, protection of existing pipelines, installation of tunnelling shafts.
- Any other services needed in & around working areas to enable completion of works, including any works undertaken by NGN & others.
- All temporary works in accordance with BS5975 & HSE guidance publication L153
- Suitable protection for all existing services to avoid damage to any water, gas pipes, drains, sewers, culverts, telephone, electric cables, ducts, production services, specified borehole monitoring wells & all other apparatus during the works.
- Aided NGN with mechanical de-commissioning & commissioning in line with the SCO4 (NRO procedures) & NGN/PM/RE/18 requirements.
- REL NRO author drafted all initial NROs & assumed role of SCO4 NRO coordinator for duration of all de-commissioning.
- Prepared full RE18 pack prior to commissioning & included all relevant test results for mechanical, civil and cathodic protection disciplines.
- Development, operation & management of Health, Safety, Environmental & Quality Plans, RAMS, detailed programme of works & all relevant CDM requirements for the project in conjunction with NGN’s requirements.
- Site access control & traffic management.
- Waste management for site.
- Supply of independent & competent HAZCON chairperson.
OUTCOME
As always, REL approached this contract as we do all others, by working very closely with our client NGN to efficiently deliver a project that was on programme, in budget and on time – all without any major difficulties.
A notable saving was made during the project in relation to time and costs onsite. This was because the majority of the AGI pipework was prefabricated offsite at our specialist fabrication workshop at head offices.
Around 90% of all AGI pipework was constructed to specification, with inspection, pressure testing and painting taking place at REL before being transported to site for installation and commissioning.
Additionally, the microtunnelling technique REL employed to lay the new pipeline, under the A1 motorway, provided many benefits as opposed to the traditional open cut method.
This technique meant that work could be completed very quickly, safely and in all weathers – without disturbing the ground above. This caused minimal disruption to traffic flow (on the busy A1) and to the local community.
The amount of excavated soil and backfill for reinstatement was condensed which meant less machinery and footfall on site. This cleaner process was much more environmentally friendly with less carbon footprint and a negligible impact on local wildlife and the wider environment.
The advanced laser guidance technology of the MTBM also meant that REL could be extremely accurate for tunnelling and the exact trajectory of for pipeline diversions.
All works for this project were completed within 14 months in line with the approved design and RAMS. REL fully satisfied their duties under CDM 2015 and provided full handover on completion in March 2022.
