Trenchless Rehabilitation of Extra-Large Profiles under challenging Circumstances

Sewer systems are among the critical components of urban infrastructure. If a main sewer fails, entire regions can quickly be affected. In Barcelona, a large-diameter sewer that had sustained serious damage required urgent rehabilitation. The following article explains how the rehabilitation was successfully carried out using trenchless UV pipe lining.

In the Spanish metropolitan region of Barcelona, a large wastewater collector has been renovated using trenchless technology. The off spec profile sewer feeds the Gavà i Viladecans wastewater treatment plant, a facility with a capacity of 64 million litres per day. The aforementioned volume represents the requirements of around 300,000 people and the associated economic activity in the region.

Starting Position: Severe Damage and Groundwater Ingress

The collector in question showed considerable damage. The pipe section had collapsed and was severely damaged, with heavy cracking in the invert area. Immense groundwater ingress and the condition of the existing structure presented significant challenges for everyone involved.

Local site conditions only compounded matters further: The construction site was situated in deep sand on a barely navigable track. Before the actual rehabilitation works could begin, access routes had to be built. The installation itself was also hindered by the groundwater. To counter this, a wastewater diversion system was deployed to reroute the channel’s water from flowing into the treatment plant.

A Truly Non-Standard Profile

A unique requirement arose from the geometry of the sewer: The profile is round in the upper section between the 8 and 4 o’clock positions, and tapers downwards at an angle in a wedge shape. It is therefore a genuinely non-standard profile.

During execution, it also turned out that the sewer originally commissioned as nominal diameter DN 1980 was actually a DN 2000! According to the contractor, deviations like these can be managed effectively using the technology at hand. Technical implementation was executed using the IMPREGLiner.

Facts About the Installed IMPREGLiner

• DN: 2000 non-standard profile
• Wall Thickness (WT): 14 mm
• Length: 74 m
• Weight: 12.5 tonnes
• Curing: Completed in just 5 hours using three KASRO Jumbo cores (3 x 6 x 2000 W)

Jobsite preparation took around three weeks, while the installation itself was completed within a mere two days. Alongside groundwater, extreme dust was cited as a major complicating factor during the works. Despite these conditions, all parties commented that everything went smoothly and according to plan, with curing completed in five hours.