Case Study: Exposing a Blocked Sewer During High-Rise Construction in Manchester

The challenge

High-rise construction can present significant challenges when existing underground utilities are located close to piling operations.

Piling involves creating deep concrete foundations within the ground to support tall structures. Where existing sewers, drains or other services are located nearby, there is a risk that they can be disturbed or damaged during the works.

In this Manchester city-centre project, a section of existing pipework had become blocked after concrete entered the service during piling operations. The blockage created the potential for sewage or surface water to back up, making it essential that the affected section of pipe was located, exposed and replaced.

The challenge was accessing the pipe without causing further damage to the surrounding services.

The approach

The Galvac team were brought in by the main contractor to carry out controlled vacuum excavation around the existing underground services.

Using a Dino 3 vacuum excavator, the team carefully removed the surrounding ground to reach the affected pipe at a depth of approximately 5 metres.

The excavation area was approximately 5 metres long by 1 metre wide, meaning the team could expose the required section of pipe while keeping the overall excavation footprint as small as possible.

This was particularly important in a city-centre environment, where minimising excavation and disruption can have a significant impact on the wider project.

Working around existing services

The excavation involved working through a number of existing underground services to reach the blocked pipe.

Rather than relying solely on excavation with conventional mechanical equipment, vacuum excavation allowed the surrounding material to be removed in a much more controlled way.

This gave the contractor access to the affected pipe while helping to reduce the risk of damaging neighbouring services during the excavation.

For projects involving congested or uncertain underground infrastructure, controlled exposure can provide the visibility needed before repair or replacement work begins.

The result

Within two shifts, the Galvac team had:

• Vacuum excavated to approximately 5 metres deep
• Worked through a congested area containing existing services
• Exposed and cleared the ground around the blocked pipe
• Created a sufficiently small excavation zone for the contractor to access the damaged section
• Enabled the blocked section of pipe to be replaced
• Supported the subsequent reinstatement of the excavation

By keeping the excavation area to approximately 5m x 1m, the contractor was able to replace the affected section without the need for a significantly larger excavation.

Why vacuum Excavation was the right approach

This project demonstrates the value of vacuum excavation when access to underground infrastructure needs to be precise and controlled.

In a busy city-centre construction environment, the objective isn’t simply to remove ground. It’s to understand what’s below, safely reach the required service and give the contractor the access they need to keep the project moving.

For Galvac, that’s where vacuum excavation adds real value.

Before you build, know what’s below.