Ōwairaka Slipline Project a Success

The Ōwairaka site team was abuzz with excitement last month at the successful installation of a 240-metre-long wastewater pipe using the ‘Slipline method’ – a complex operation that went without a hitch.

Sliplining is a safer, trenchless method for installing pipes underground. It involves pulling a new pipe through an existing pipe.

The team was motivated to hit its weekly milestones to ensure the installation went smoothly. Everyone involved gained valuable experience and new skills from the complicated operation.  

The new pipe connects the wastewater system between two locations on Hargest Terrace and properties on Hendon Avenue.  In this case, the old pipe dispensed stormwater and wastewater. Now that there is a separate stormwater system, the existing pipe will be redundant, used only as housing for the new, slimmer wastewater pipe.

Laying the new pipe using an open trench was not an option, as the existing pipe runs under nearly 30 homes. Sliplining was the least intrusive method for the job.

A major challenge was that wastewater services could not be switched off. The team had to figure out how to maintain wastewater for three weeks for affected homes and businesses, as well as Ōwairaka District Primary School. The least disruptive option was a temporary wastewater system of nine below-ground and three above-ground temporal tanks, with the system checked and emptied daily.

As well as all the engineering logistics, keeping the neighbourhood informed was a top priority. The site management team met with residents to explain how the wastewater installation would work. Keeping the community updated meant residents understood what was happening and supported the project.

On the day of the operation, the pulling head was attached to the long pipe string and the pull started. Pulled and welded in three sections, all went smoothly and was a great success.  

Curing with UV light  

In conjunction with the slipline works, Piritahi also completed 'Cured In Place Pipe' upstream on sections of a wastewater pipe. The pipe is cured in place underground by UV light. By using these underground trenchless methods, we have significantly reduced the disruption to residents compared to traditional methods.

Ōwairaka Slipline Project a Success

The Ōwairaka site team was abuzz with excitement last month at the successful installation of a 240-metre-long wastewater pipe using the ‘Slipline method’ – a complex operation that went without a hitch.

Sliplining is a safer, trenchless method for installing pipes underground. It involves pulling a new pipe through an existing pipe.

The team was motivated to hit its weekly milestones to ensure the installation went smoothly. Everyone involved gained valuable experience and new skills from the complicated operation.  

The new pipe connects the wastewater system between two locations on Hargest Terrace and properties on Hendon Avenue.  In this case, the old pipe dispensed stormwater and wastewater. Now that there is a separate stormwater system, the existing pipe will be redundant, used only as housing for the new, slimmer wastewater pipe.

Laying the new pipe using an open trench was not an option, as the existing pipe runs under nearly 30 homes. Sliplining was the least intrusive method for the job.

A major challenge was that wastewater services could not be switched off. The team had to figure out how to maintain wastewater for three weeks for affected homes and businesses, as well as Ōwairaka District Primary School. The least disruptive option was a temporary wastewater system of nine below-ground and three above-ground temporal tanks, with the system checked and emptied daily.

As well as all the engineering logistics, keeping the neighbourhood informed was a top priority. The site management team met with residents to explain how the wastewater installation would work. Keeping the community updated meant residents understood what was happening and supported the project.

On the day of the operation, the pulling head was attached to the long pipe string and the pull started. Pulled and welded in three sections, all went smoothly and was a great success.  

Curing with UV light  

In conjunction with the slipline works, Piritahi also completed 'Cured In Place Pipe' upstream on sections of a wastewater pipe. The pipe is cured in place underground by UV light. By using these underground trenchless methods, we have significantly reduced the disruption to residents compared to traditional methods.

Ōwairaka Slipline Project a Success

The Ōwairaka site team was abuzz with excitement last month at the successful installation of a 240-metre-long wastewater pipe using the ‘Slipline method’ – a complex operation that went without a hitch.

Sliplining is a safer, trenchless method for installing pipes underground. It involves pulling a new pipe through an existing pipe.

The team was motivated to hit its weekly milestones to ensure the installation went smoothly. Everyone involved gained valuable experience and new skills from the complicated operation.  

The new pipe connects the wastewater system between two locations on Hargest Terrace and properties on Hendon Avenue.  In this case, the old pipe dispensed stormwater and wastewater. Now that there is a separate stormwater system, the existing pipe will be redundant, used only as housing for the new, slimmer wastewater pipe.

Laying the new pipe using an open trench was not an option, as the existing pipe runs under nearly 30 homes. Sliplining was the least intrusive method for the job.

A major challenge was that wastewater services could not be switched off. The team had to figure out how to maintain wastewater for three weeks for affected homes and businesses, as well as Ōwairaka District Primary School. The least disruptive option was a temporary wastewater system of nine below-ground and three above-ground temporal tanks, with the system checked and emptied daily.

As well as all the engineering logistics, keeping the neighbourhood informed was a top priority. The site management team met with residents to explain how the wastewater installation would work. Keeping the community updated meant residents understood what was happening and supported the project.

On the day of the operation, the pulling head was attached to the long pipe string and the pull started. Pulled and welded in three sections, all went smoothly and was a great success.  

Curing with UV light  

In conjunction with the slipline works, Piritahi also completed 'Cured In Place Pipe' upstream on sections of a wastewater pipe. The pipe is cured in place underground by UV light. By using these underground trenchless methods, we have significantly reduced the disruption to residents compared to traditional methods.