Project Overview

The project involved the installation of 2,290 metres of 2000DN GRP jacking pipes across eight drives between shafts.

The longest tunnel measured 470 metres and was constructed in challenging ground conditions, including aquifers and high water pressures. The Iseki TCS tunnelling machine (TBM) was launched from shafts constructed by the main contractor, Haji Hassan.

In addition to the 2000DN tunnels, JGL also installed 290 metres of 1200DN pipe. The successful completion of the project was achieved through exceptional teamwork, meticulous planning, and effective collaboration between JGL and the client.

Challenges:

The project faced several key challenges:

Late Start:
Delays in shaft availability compressed the schedule, requiring an accelerated completion date of December 2024, which JGL committed to meeting.
High Water Tables and Aquifers:
Elevated water tables and pressurised aquifers presented significant risks, including potential pipe flotation and flooding.

Added Value

JGL leveraged extensive experience in Bahrain and the wider Middle East to complete this technically demanding tunnel installation ahead of schedule. By identifying key risks - such as high water tables and pressurised aquifers - early in the process, JGL worked closely with the client to optimise shaft designs.

Custom pipe breaks were engineered to counteract water pressure and prevent pipes from being pushed back into the shafts, ensuring a successful outcome.

Through meticulous planning and execution, JGL delivered the project two months ahead of the already accelerated deadline. This early completion enabled the client to expedite manhole construction within the shafts.

Additionally, JGL designed and fabricated custom pivoted recovery rails for the existing chambers, allowing the TBM to move and be positioned without disturbing cover slabs. All fabrications were completed in-house by JGL in Bahrain.

Project Highlights

The project’s standout achievement was the delivery of a high-quality product well ahead of schedule, accomplished with an unwavering commitment to safety.

The completed tunnels not only met but exceeded expectations, setting a new benchmark for excellence in the region. The precision and craftsmanship demonstrated throughout the installation have earned recognition as some of the finest tunnels ever constructed in the area. This performance reinforces our dedication to quality and timely delivery, strengthening our reputation as industry leaders.

Innovations

The design and fabrication of bespoke recovery rails and custom pipe breaks served as innovative solutions to the project’s unique challenges. Due to the lightweight nature of the GRP pipes, custom trolleys with added weights were engineered and installed within the tunnel.

These trolleys counteracted pipe buoyancy and ensured that tunnel alignment remained within precise tolerances.

JGL has submitted an application for the NCE Awards Tunnelling Team of the Year, and we are optimistic about our chances. Both JGL and the client, Haji Hassan, are highly deserving of this recognition for their exceptional collaboration in overcoming significant challenges. The award would honour the teamwork and innovation demonstrated throughout the project.