The project sought to inform the design of the upgraded carriageway by establishing baseline groundwater conditions and monitoring changes during a programme of drilling and grouting beneath the highway.

The widening scheme aimed to expand the existing dual carriageway to three lanes in each direction, a significant infrastructure improvement to enhance capacity and reduce congestion on one of the North East’s busiest transport corridors.

Scope of Groundwater Monitoring Works

Igne’s ground investigation remit was to provide robust, factual data on subsurface and groundwater conditions, with a particular focus on the potential impacts of grouting activities.  The works were designed to ensure that grouting operations did not induce rapid groundwater level changes that could affect nearby residential foundations or cause the migration of mine gases into adjacent properties.

The scope in bullet points!

• Sixteen rotary open-hole drill-holes advanced to depths of up to 30 metres below ground level.
• Continuous in-situ groundwater monitoring using data-logger instruments.
• Installation of 50 mm internal diameter groundwater monitoring standpipes.
• Baseline and post-works groundwater level data collection and analysis.
• Decommissioning and backfilling of all monitoring wells following completion. 

How did we do it? 

Fieldwork was delivered over around coordinated traffic management operations to minimise disruption to road users.  All drilling, installation, and monitoring activities were undertaken during night-time hours to align with wider site logistics and safety requirements.

Each borehole was drilled using rotary open-hole techniques with water flush and continuous gas monitoring both at the rig and at the top of each hole.  Once installed, data-loggers were used to capture continuous groundwater level data, supplemented by periodic manual readings.

Monitoring continued for approximately nine months, extended by a further two months to gather residual data following completion of grouting.  This programme provided essential information on pre- and post-treatment groundwater conditions, supporting safe design and environmental assurance.

And what was the outcome?

Igne successfully delivered a comprehensive factual ground investigation report, providing the client with the critical baseline and monitoring data required to assess the effects of drilling and grouting on local hydrogeological conditions.

Monitoring confirmed that groundwater level changes remained within expected parameters and that mitigation measures were effective in protecting nearby properties from adverse effects.

All wells were decommissioned and reinstated following the conclusion of post-works monitoring.

 

What does this mean for you?

Well, this project demonstrates Igne’s capability to plan and execute technically complex ground investigations in live, high-traffic environments.  Working collaboratively with the client and their consulting engineers, Igne ensured all activities were completed safely, accurately, and in compliance with the project’s design and environmental requirements - supporting National Highways’ ambition to deliver a resilient and future-ready A1 corridor.

Projects like the A1 widening demand absolute confidence in subsurface conditions.  Igne delivers the data, assurance, and experience needed to design and construct safely on complex ground.

If you’re planning infrastructure that depends on accurate ground and groundwater intelligence - talk to us!