DHL rescued from ‘that sinking feeling’

A DHL warehouse in Northamptonshire was faced with safety risks and significant operational issues due to subsidence. A small office building (20m x 15m), attached to the distribution warehouse (205m x 80m), had sunk by 70mm and needed to be raised and re-levelled. The smaller building was regularly used by staff as it housed the main office and staff amenities. It was therefore vital to maintain safe access to all staff areas throughout the project.

The contractor took on full project design and management of the remediation and handled all the steps necessary to locate, remove and reinstate all third-party services (gas, electricity etc.).

A bespoke combination of non-invasive, computer-controlled grouting and resin injection was used to provide the necessary ground improvement and lift of the office building without causing business disruption.

Before commencing ground improvement and re-levelling works, the contractor discovered that the main gas pipe was running in front of the building and was posing safety risks. The project team managed the additional risks, ensuring the subsidence rectification works could continue as planned.

Multiple injection ports needed to be installed through the concrete pads along the subsided sections of the building. Through these ports, the contractor inserted JOG high mobility cement grout under computer control. This enabled the team to lift the office building gradually and in a precisely controlled manner, moving the building back to its neutral position – all without causing business interruption. 

The contractor developed a customised plan to place the injection ports, to fit the structural elements of the building, ensuring it could safely continue to function as a workspace. A Teretek resin injection solution was then used to provide the necessary ground improvement, as well as raise and void fill the internal floor slab.

This approach also allowed for work to be tailored around busy periods, enabled successful management of noise levels and achieved project completion with minimal disruption to the day-to-day business.

The tenant said: “This was a difficult project with a strict time limit. We were extremely pleased that Mainmark managed to complete the project so efficiently and professionally, with absolutely no disruption to our day-to-day business operations. The team were helpful, knowledgeable and kept us informed every step of the way. We would absolutely recommend Mainmark’s services to other clients.”

The office was raised by 57mm, with the ground improved to the required specification, in 27 days, providing a long-term solution for the ground issues. 

Mainmark was chosen as the principal contractor thanks to its market leading ground improvement solutions and its extensive experience working with large commercial warehouses. Mainmark’s advanced technologies offer non-invasive, cost-effective and time-efficient solutions. For this project, Mainmark used its JOG Computer-Controlled Grouting (JOG) technology – which offers the higher level of precision and control needed to lift such a substantial structure – and its proprietary Teretek resin injection, a non-invasive solution able to deliver both ground improvement and re-levelling.