Overview
Network Plus acts as the Construction Management Organisation (CMO) for Cadent Gas, delivering both Mains Replacement and Non‑Mains Replacement programmes across the North West and East Midlands, representing approximately £150 million of annual investment. One of the major schemes delivered under this framework was a 2,850 m, 180 mm HDPE intermediate‑pressure diversion near Melton Ross, involving complex engineering, deep excavations, HDD works beneath the A180, and extensive CDM and stakeholder coordination.
Background
Through this partnership, Cadent relies on Network Plus to manage and deliver major capital works through a combination of in‑house expertise and specialist Local Delivery Partners. The Melton Ross diversion was required to strengthen network resilience and involved specialist flow‑stopping operations:
PE main installation, hazardous‑area mitigation near Humberside Airport, deep excavations, geotechnical design, ecological controls, and a trenchless HDD crossing beneath the A180. The project also required full CDM compliance, temporary works governance, and coordination with National Highways, local authorities, landowners, and multiple design houses.
Solution
Pre‑Construction and Planning
Network Plus led a full HAZID, HAZOP, and HAZCON process with Cadent to identify and manage hazards including missile generation, corrosion, utility conflicts, and restricted site access.
As Principal Designer and Principal Contractor, we validated the diversion design, ensured CDM 2015 compliance, and coordinated temporary works, safety engineering, and G17 appraisals.
Geotechnical and HDD Planning (condensed narrative)
The deep crossing beneath the A180 required a carefully engineered HDD solution. Network Plus developed a detailed HDD bore profile to meet National Highways’ surface‑settlement trigger levels, with drilling depths reaching 8.55 m. We coordinated pipeline integrity checks and facilitated joint design reviews between two design houses to secure Cadent Deviation Approval. Geotechnical planning included boreholes, topographical surveys, and CD622‑compliant design appraisal undertaken with National Highways and the appointed designer. Multiple pre‑construction meetings, design reviews, and RAMS approvals ensured alignment, while surface monitoring points were installed and tracked throughout drilling to confirm no impact on the A180 foundations.
Environmental and Site Controls
Preliminary Ecological Appraisals were completed, including badger‑trap coordination. Impact protection slabs were designed and constructed to safeguard the new pipeline from heavy quarry plant movements. Temporary access roads, secure entry systems, and defined transport routes were established to manage site logistics safely.
Project and Stakeholder Management
Network Plus provided full project governance, including programme development, resource planning, and oversight of specialist contractors for HDD, welding, pressure testing, and reinstatement. Engagement with National Highways, local authorities, and landowners ensured timely permits, street works notices, and access arrangements.
Operational Delivery
The diversion was delivered through coordinated multi‑disciplinary activities including 6″ UPT and Double Stopple operations, mechanical welding and QA inspections, installation of the 180 mm PE main and valve assemblies, construction of three M1 valve chambers, and execution of the HDD crossing beneath the A180. All works were delivered in accordance with G/PM/G/17 and Cadent’s SCO procedures, supported by site inductions, toolbox talks, and ongoing audits.
Handover & Closeout
Network Plus coordinated a streamlined closeout process with Cadent, including joint inspections, snagging, verification of construction and pressure‑test records, and submission of as‑laid drawings, red‑line mark‑ups, and certificates into Cadent’s asset systems. Reinstatement was completed to HAUC standards with local‑authority sign‑off. Commercial reconciliation, risk management, and final valuation were completed in line with framework governance. Lessons learned were captured with Cadent and the supply chain to support continuous improvement.
Customer
Cadent Gas, the UK’s largest gas distribution network, is responsible for maintaining and upgrading critical gas infrastructure across multiple regions. This project provided Cadent with a fully managed, CDM‑compliant construction solution, robust safety and environmental assurance, seamless stakeholder coordination, and a future‑proofed intermediate‑pressure diversion delivered to the highest engineering standards.
