SewerFix is a major program undertaken by Sydney Water Corporation (SWC) to reduce the discharge of sewage into the environment. It is also part of Sydney Water’s strategic program to meet the objectives of the sewage treatment system licences issued to SWC by the Environment Protection Authority (EPA) in May 2000.
SWC has identified sewer catchment areas in the Blue Mountains just west of Sydney that have choke and sewage overflow problems. SWC issued two major contracts to carry out cleaning, inspection and rehabilitation of nominated Sydney Water sewers to meet the EPA licence standards.
The first of these contracts was awarded to Kembla Watertech P/L in March 2002 and to this day represents the largest single rehabilitation contract ever awarded in Australia. Work on this contract was completed in late 2003.
Kembla Watertech was subsequently awarded the second Blue Mountains SewerFix contract in early 2004 and this contract is scheduled for completion in December 2004.
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Case Study: The benefits of a partnering arrangement for sewer rehabilitation
South East Water Limited (SEWL) is one of three metropolitan water companies providing retail water and sewerage services to Melbourne. With over $A1 billion in assets including over 7,000 km of gravity sewer mains, SEWL has an ongoing requirement for sewer renewals.
Kembla Watertech Pty Ltd, as a leading Australian pipeline rehabilitation service provider, offers a wide range of pipeline rehabilitation solutions nationally. SEWL and Kembla Watertech have now entered into a partnering contract for the delivery of Sewer Rehabilitation Services throughout the entire SEWL area.
Services provided to SEWL as part of the partnering contract include sewer re-lining using Kembla’s EX and Enviro-liner methods, pipe cracking, short form patch linings, slip lining and repairs via civil excavation. A close fit exists between SEWL’s needs for sewer rehabilitation and the services provided by Kembla Watertech both in type and capacity.
Contract styles used by SEWL to deliver Sewer Rehabilitation have evolved from multiple Lump Sum annual contracts prior to 1998/99, followed by a one year schedule of rates contract in 1998/99, which was extended for a further two years as the first partnering contract. The success of this delivery mechanism led to the second generation three year partnering contract currently in place. The evolution of contract style has been driven by the changing needs of SEWL as it has sought to improve its asset management strategies, customer service and risk management.
The benefits of the partnering approach in place to both parties are flexibility of rehabilitation technique, management of one contractor (i.e. multiple in-house rehabilitation solutions), faster response to emergency works, consistent base of work allowing stability in the workforce and improved productivity and quality.
Additionally, further benefits of the second generation contract to both parties include a multi-level relationship, improved issue resolution when compared to lump sum contracts, cost effectiveness (‘right price’ rather than ‘lowest price’), safety, flexibility and consistent work flow management.
Current trends in the water industry indicate a greater acceptance of this style of service delivery as more authorities embrace the benefits. It is Kembla’s belief that, given the right partner, the benefits of a partnering approach to pipeline rehabilitation has seen a move towards seamless delivery of asset rehabilitation solutions.
Trenchless Technology to the fore in heritage-listed site
SewerFix is a rehabilitation program aimed at minimising the impact of infiltration/exfiltration on existing sewerage infrastructure throughout Sydney Water’s area of operations. Infiltration and exfiltration can be the result of a number of pipeline defects including cracks, fractures, gas attack, root ingression, blockages and open/displaced joints.
Kembla Watertech Pty Ltd was contracted by Sydney Water to inspect and repair sewer lines in the Blue Mountains including areas within the environmentally sensitive South Katoomba Sewer Catchment Area.
Sydney Water has identified that the use of Trenchless Technology represents an effective method to rehabilitate sewers, using modern technology to produce an ecologically sustainable rehabilitation program.
Specific Problem
A section of 375 mm - 300 mm diameter sewer main identified for lining was located through the Peckmans Road Open Space Area, which is also known as Katoomba Falls Reserve. A Review of Environmental Factors (REF) undertaken by Sydney Water identified this area as an open plain grassland reserve with significant designated heritage sites. In order to install the lining, it was necessary to access the chambers located in the middle of the paddock. However, the whole area was listed as both an Aboriginal and European heritage site which was protected and not to be disturbed or damaged in any way. This required a non-invasive approach to be taken to all aspects of the rehabilitation.
Lining process
Kembla’s Enviroliner system was employed to overcome the unique and difficult access problems whereby the installation trucks could only get to within 200 metres of the manhole. The Enviroliner System is a process for the renovation of pipelines by the installation of a resin impregnated, flexible tube which is inverted into the existing conduit by the use of a hydrostatic head or pressure. The tube is then cured to a hardened state while held in intimate contact with the conduit. The end result is a strong, joint free pipe within a pipe designed to last for over 50 years.
Job Successfully Completed
A small scaffold platform was erected over the access chamber to provide the head of water needed to install the Enviroliner. The hoses needed for water supply and curing of the lining were laid out across the paddock for the 200 m to the nearest public access point. This point was also where the special hot water heating unit had to be located. Once everything was in place the resin impregnated Enviroliner was man-handled onto the platform from where it was inverted into the sewer pipe section. Because of the distance of the boiler unit from the chamber, a special low heat-loss hose was used to circulate the hot water through the now installed, but still soft, Enviroliner. Thermocouple sensing devices were used to measure temperature rises within the lining and confirm that a full cure or hardening of the resin had been achieved. It is not normal practice to have the installation equipment so far away and this job represented the longest ever undertaken by this process.
In response to the unique circumstances of this particular job Kembla was able to extend the boundaries of the existing technology in order to achieve the result required by the client and other stakeholders.
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