Wastewater Treatment and Management Resolved Using CIPP

Butler Reserve CWMS relining

Plumbing & Pipeline Solutions were engaged by the City of Tea Tree Gully to provide a wastewater treatment and management solution to repair a section of their wastewater pipeline system.

This section of 225mm diameter fibro-cement CWMS (Community Wastewater Management System) pipe was constructed in the early 1970’s. The pipeline runs through Butler Reserve, which is in the suburb of Banksia Park. This pipe carries the second biggest catchment of effluent (discharged from household septic tanks) throughout the City of Tea Tree Gully. During peak flow periods, the flow rates through this trunk main can reach up to and beyond 100 L/s. This stretch of pipeline represents the last 200m of Tea Tree Gullys CWMS for this catchment before it connects into the SA Water Sewer main on Hancock Road.

During peak flow periods, the flow rates through this trunk main can reach up to and beyond 100 L/s. This stretch of pipeline represents the last 200m of Tea Tree Gullys CWMS for this catchment before it connects into the SA Water Sewer main on Hancock Road.

Problem

The condition of this section of the CWMS network was inspected in mid-2010, during a connection replacement at 279 Hancock Road by Councils CWMS maintenance team. The top of the pipe was exposed during this inspection and the upper half of the fibro pipe was rated as being paper-thin in sections.

Due to the high importance of this pipeline in transferring effluent from Councils CWMS network into the SA Water sewer downstream, along with the residential and environmental surroundings of this pipe location, it was critical that City of Tea Tree Gully act, to prevent a potentially hazardous spill.

Due to the difficult location of this pipeline (through natural reserve, with a number of significant trees and a pronounced creekline, along with running through a number of residential properties), conventional methods of pipe replacement/renewal were not suitable for this project.

PPS Solution

Plumbing & Pipeline Solutions proposed to repair the damaged section of pipe using a process known as cured-in-place-pipe (CIPP).

CIPP allows PPS to create what is effectively a whole new pipe within the existing, deteriorated pipe without digging. The resultant seamless, jointless liner ensures a smooth, continuous inner surface with improved flow characteristics and saves the substantial cost of excavation and replacement, especially for easement locations. Maintaining the integrity of the pipeline before it ruptured was vital to avoid the high costs and negative publicity associated with emergency repairs. Restoring instead of replacing was seen as not only a more economical solution but highly ecological as well.

Maintaining the integrity of the pipeline before it ruptured was vital to avoid the high costs and negative publicity associated with emergency repairs. Restoring instead of replacing was seen as not only a more economical solution but highly ecological as well.

PPS Process

The installation process takes place after preliminary CCTV inspections have been conducted to measure and locate all lateral connections, this inspection also checks that no debris is lodged in the pipe. The next step is to create a bypass to ensure minimal disruption to households connected to the effected section of pipe.

Installation of the liner then begins at the upstream manhole using the inversion method. The resin impregnated liner is fed in to the host pipe, turned inside-out and propelled along the way by a head of water pressure. This pressure causes the soft liner to expand and take the form of the host pipe.

When the liner is half-way installed, a circulation hose is attached to the end of the lining which is connected to a boiler unit. Then, when the liner has been fed along the length of the host pipe, water at a temperature of 80-85 degrees is pumped through the liner to cause a cross-linking reaction that sets the resin impregnated liner.

Once the curing process is complete, cold water is introduced to cool the pipe.

Depending on the situation, a robotic cutting unit is used to open junctions along the length of the pipe. Following this a post-installation CCTV inspection is conducted and a comprehensive report is provided to the client.

Typically pipe lengths in excess of 200 metres can be lined in a single insertion within a 12 hour period.

The system can be varied to suit particularly aggressive effluent types with regard to chemical content and/or high temperatures.