​​​Underwater Pipeline Crossing Surveys & Remedial Works​​

Northern Gas Networks (NGN) requires the provision of specialist river crossing survey and assessment services across its gas distribution network to monitor the condition, integrity, and ongoing safety of pipeline assets located within river crossings and associated watercourses.

The scope of services includes, but is not limited to:

- Determination of pipeline cover depths and profiles within river crossings.

- Identification and assessment of changes to riverbeds, banks, and watercourses that may affect pipeline integrity or stability.

- Confirmation of pipeline locations through topographical and hydrographic survey techniques, supported by geomorphological assessments where required.

- Surveying of riverbed and bank levels to identify erosion, scour, exposure, or other changes in condition.

- Inspection and assessment of exposed pipeline sections.

- Evaluation of the condition and construction of riverbeds, banks, and associated crossing infrastructure.

- Close Interval Polarised Potential (CIPP) Surveys and other corrosion monitoring activities where specified by NGN.

The appointed supplier shall provide comprehensive survey reports detailing the methodology employed, survey findings, identified risks, and recommendations for any remedial or risk mitigation measures. Where required, the contract may also include the provision of remedial works arising from survey findings to maintain the safety, integrity, and operational performance of the pipeline network.

This procurement seeks to establish a contract for the delivery of these specialist services across NGN's geographical operating area, ensuring the continued monitoring, assessment, maintenance, and protection of pipeline river crossings. The contract will support NGN in maintaining compliance with applicable engineering, environmental, and safety requirements while ensuring the long-term resilience and integrity of its gas distribution infrastructure.