The four industry professionals agreed that Trenchless Technology plays an essential role in inspection and repair programs. Mr Mahalingam explained that the Albury City Council uses Trenchless Technology extensively. Mr Scott says that SA Water chooses Trenchless Technology wherever possible depending upon factors such as cost and applicability.
Mr Basu of Sydney Water offered his personal assessment of asset management. He says that almost all sewer repair and renovation is carried out utilising no-dig methods. Mr Moller agrees that for sewer work they utilise trenchless technologies such as relining and directional boring for water mains replacement.
We asked the contributors the length of assets their authority is responsible for. According to Mr Scott, SA Water has 25,892 km of water line in diameters ranging from 20 mm – 2,475 mm. The authority maintains 8,011 km of gravity sewer pipes, 402 km of pumped sewer pipes and 276 km of reclaimed.
Mr Mahalingam says that Albury City is responsible for 594.6 km of water, 509.9 km of wastewater and 324.2 km of stormwater. The asset management program in use is the Huefner Asset Management System (PipePAK).
Mr Basu says that Sydney Water is responsible for 22,000 km of sewer and an equal length of water line, varying in size from retic to trunk mains. There is a thirty year asset management program in place, based on life cycle cost.
The Goulburn Mulwaree Council is responsible for 250 km of water distribution network and 196 km of sewer distribution network, says Mr Moller. The council has engaged an external consultant to prepare an asset management plan.
Mr Scott says that for pipe assets each program has specific strategies underpinning the approach adopted. The approaches will vary depending on risk, condition and performance and KPIs. The asset programs for water are the water network reticulation mains renewal, trunk mains renewal and major pipelines renewal. The sewer program includes the sewer network reticulation mains renewal, trunk mains renewal and pumping mains renewal. The asset program for reclaimed water is the reclaimed network reticulation mains renewal.
Inspection programs are an essential tool to monitor the condition of underground assets. Water authorities and councils utilise trenchless technologies such as CCTV to identify potential problems and defects and techniques such as relining and pipe jacking to repair the assets.
When asked about the current works to inspect or repair assets Mr Mahalingam says that the Council budgets $A500,000 per year for sewer rehabilitation work involving lining, slip lining and pipe cracking. The council allocates a further $A500,000 for water replacement works. Mr Moller adds that the Goulburn Mulwaree Council will be relining approximately 1 km of the sewer network this financial year. The funding per annum is also $A500,000 for sewer works and $A500,000 for water works.
When asked the value and length of inspection works undertaken annually Mr Mahalingam says that the inspection of 5,000 m equals approximately $A1,000,000.
He says that around 1,500 m in sewer pipes and 3,000 m of Albury Council’s water assets are repaired or replaced each year. The Albury City council inspects less than one per cent of their assets annually.
Mr Scott says that the funding at SA Water varies from year to year. He explains that major water pipelines are inspected approximately every 15 years via a walk along by the Materials Science Group. In the past water trunk mains have had an ad hoc assessment; however SA Water is commencing a more strategic approach to determine the length of suspected poor condition trunk mains as a part of the planned renewals. Condition assessment techniques will include Linear Polarisation Resistance and Mainscan. The sewer inspection program involves a CCTV program in place targeting the larger, older reinforced concrete mains and also the mechanical and chemical cleaning of sewer assets.
SA Water has a CCTV inspection target of 100 km per year says Mr Scott. The authority repairs approximately 4,000 water main bursts each year. He adds that they replace about 47 km of water mains annually and this increase each year based on deterioration modelling.
SA Water deal with approximately 4,000 sewer main chokes per year, with an estimated 20,000 sewer connection chokes per year, and relines around 5 km annually.
Mr Basu says that Sydney Water inspect between 300 – 500 km every year. He adds that the proportion of assets repaired or replaced annually depends on the condition and operating context, however he estimates 35 km per year. Mr Moller says that 2 – 3 km of sewer pipelines are inspected using CCTV annually. The inspection and repair schedule is planned five years in advance.
When asked if there are any limitations that prevent the works from being completed Mr Mahalingam says that competitive pricing in the country area is a problem. Mr Scott listed technology output as a challenge, for example translating technological results into a probability of failure with known degrees of accuracy.
Mr Basu says that technological barriers include the inspection and/or assessment of the condition of large sewers by non-man entry techniques, the rehabilitation of non-circular sewers and root prevention are challenges.
The funding of inspection and repair programs also imposes limitations upon asset management. Mr Moller and Mr Mahalingam agree that funding is a factor in their ability to implement the management programs.
Asset management in built up areas and sensitive environments whether urban or country relies on different applications of Trenchless Technology. Mr Mahalingam says that the main trenchless techniques used by the Albury Council are pipe cracking and lining. Mr Basu says that Sydney Water utilised cleaning, CCTV, lining and coating to maintain their assets. Mr Scott says that SA Water uses CCTV, HDD, spiral wound lining, swagelining, spray lining and pipe bursting.
Mr Scott says that the value and length of annual rehabilitation works also varies but generally increases. Planned renewals are based on the projected lengths for replacement, called deterioration modelling, unit rates are then applied to these lengths.
Trenchless Technologies provide a practical solution to many of the problems encountered when inspecting or repairing water and sewerage assets around Australia. The use of these diverse and innovative products reduces the disruptions to traffic and the general public. Navigating other utilities and services is made easier. Finally, technological advances in machinery, inspection tools and other products is ensuring efficient, cost-effective and safer solutions in the urban and country environments.
