Tinkers Pond Crown Hole, Barnsley

Civil Engineering, Earthworks & Drainage

Brief Description

On the BAH2 (Crigglestone Junction to Barnsley Station Junction) line at Tinkers Pond, Barnsley, a crown hole appeared at track level prompting CML’s on-call teams to respond. Initially our teams supported Network Rail to fill the void before implementing a robust monitoring system. This system enabled safe train operations under a speed restriction while discussions with the Mining Remediation Authority (MRA) assessed the next steps.

Given the known mining history in the area, CML worked closely with Network Rail, the MRA, and the adjacent landowner to conduct a Ground Penetrating Radar (GPR) survey and ground investigations to develop a comprehensive ground model and mining risk assessment, culminating in CML designing and delivering a bespoke remediation solution.

 

Scope Of Works

Upon identifying the root cause as a failed ancient mineworking, CML designed and delivered a bespoke remediation solution. Network Rail interfaced with key stakeholders (predominantly Northern Rail) to establish a 2-week blockade closure of the railway with a view to stabilising the suspected mining feature.

  • A 1200yd access road was established via 3rd party land and site compound mobilised within a week prior to the blockade.
  • Circa 30 metres of the railway track was removed to provide access and we deployed large C6 drill rigs to site.
  • To prevent excessive grout migration, we installed a grout curtain around the perimeter of the voids, drilling to 18 metres depth and injecting specialist grout.

Further targeted drilling allowed us to fill the voids and address settlement, using approximately 136 tonnes of grout in total.

Throughout the process we enforced stringent safety controls, including wet drilling, gas monitoring and exclusion zones due to the risk of mine gas and collapse.

Track reinstatement was completed by Network Rail, with CML providing post-installation monitoring to ensure long-term stability. The project was delivered ahead of schedule, with handover occurring three days early and a total cost, including initial intervention, monitoring, design and final remediation, of approximately £1.7 million.

Key Stakeholder Management

To ensure long-term stability, Network Rail coordinated with key stakeholders, including Northern Trains, to secure a two-week blockade of the railway. Within a week, CML mobilised to site, establishing a 1200-yard access road via third-party land to facilitate permanent remedial measures. The initial phase of the blockade focused on further exploratory drilling to identify a more targeted remediation plan. Due to the collapse risk, boreholes around the affected area were drilled from a frame to spread the load, requiring the removal of 30m of track on both the UP and DOWN lines. Given the potential for mine gases and explosion risks, strict control measures were enforced throughout the drilling operations.

Following extensive stakeholder meetings, CML, Network Rail, and the MRA agreed on a 16m x 16m grout curtain remediation plan, incorporating primary and secondary injection holes to stabilise the subsidence from the mine workings. Subcontractor Van Elle, under CML’s management, carried out the drilling and grouting operations, completing 70 holes at depths of 17.5 – 21m and injecting over 136 tonnes of grout.

Reinstatement of the Railway

Upon completion of the remediation works, the railway was reinstated along with track monitoring systems to check for any movement post completion. A key milestone was the successful compilation of the mining remediation mitigation report, which played a crucial role in Network Rail’s decision to reopen the railway to traffic.

Thanks to careful site management and collaboration, the project was completed with minimal disruption to the railway, with no accidents or incidents. An ORR visit midway through the blockade further validated the positive, collaborative approach undertaken by all stakeholders.

Looking ahead, planning is underway to design and install a reinforced concrete cap over the affected area to provide a long term permanent solution.

Commitment from our CML Teams

The success of the project was made possible by the commitment and dedication of the site teams, who worked on a 24/7 rota throughout the blockade. Their efforts reflected the organisation’s core values of delivery excellence, a people-focused approach, professionalism, and a strong commitment to meeting client needs.

Strong leadership and effective coordination ensured that both technical challenges and on-site operations were managed efficiently, enabling the team to maintain momentum throughout the works.

The project also exceeded its initial remediation target of 6m x 6m, ultimately securing a 16m x 16m area ahead of schedule. This represented a significant achievement for the delivery team and demonstrated the value of proactive planning, collaboration, and a highly motivated workforce.

More Case Studies

Subscribe to our Digital Newsletter

Keep up to date with our latest news, projects and industry developments

© 2026 Construction Marine Ltd. All rights reserved.

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.