Question asked in Parliament Mar 9, 2016
The Hon. J.A. DARLEY (14:59:30): I seek leave to make a brief explanation before asking the Minister for Water and the River Murray questions in regard to pipe maintenance.
The Hon. J.A. DARLEY: I understand that a number of years ago SA Water undertook a preventative maintenance program which included inspections of the pipe network, a register of the age and condition of the pipe network, and information pertaining to soil reactivity in areas across the state. My questions are:
Can the minister advise if SA Water still have a preventative maintenance program or if this has been replaced by a breakdown maintenance program?
Can the minister provide details as to whether SA Water still maintain a register for the age and condition of the pipe network and how often this is reviewed and updated?
What was the date of the last review of the pipe network, including pipes and pipe joints, in Campbelltown, Newton and Paradise?
When was the pipework originally laid?
Can the minister table the last review results?
Can the minister advise if SA Water conducts regular soil testing on soils that are known to be particularly reactive? If so, can the minister advise if the soil in Campbelltown, Newton and Paradise has been tested and, if so, the date of that test and the type of soil found, including the extent of expansion and contraction?
The Hon. I.K. HUNTER (Minister for Sustainability, Environment and Conservation, Minister for Water and the River Murray, Minister for Climate Change) (15:01:02): I thank the honourable member for his most important questions. It was incredibly detailed, and some of it I will have to take on notice and come back with some answers for him, but I can put some general remarks on the record for him.
Over the past four years, 2011-12 to 2014-15, SA Water has spent $51.4 million per annum on average, I am advised, on direct routine maintenance repairs, including breakdowns to its infrastructure right across the state. This cost is directly attributable to maintenance activities, I am advised. Those activities are undertaken on individual assets and do not include the cost of operating, monitoring and managing those assets on a day-to-day basis.
In addition to the asset maintenance cost, SA Water also invests significant capital in the ongoing renewal of its infrastructure. Over the past three years, SA Water has invested on average $325 million per annum, I am advised, on the renewal and upgrade of its pipe networks, treatment plants, water storages and other related infrastructure. The 2014-15 spend, I am advised, has reached approximately $243 million.
The results of SA Water's Customer Engagement Program have determined that customers were satisfied with the level of service and reliability provided by SA Water. In terms of the condition and age of the network, SA's water pipe network is in good condition, I am advised. The average age of the water mains is 51 years, with those water mains in regional areas being slightly older than metropolitan Adelaide water mains on average.
The Australian water industry anticipates that water pipes will have useful lives, between an average of 80 and 150 years, depending on soil conditions, pipe material and construction standards. SA Water's pipe network is therefore relatively young by urban water industry standards. SA Water owns 27,078 kilometres of water mains with a gross replacement value of $7.3 billion, I am advised, as of June 2015, in order to supply water to 682,749 metered connections across the state. I assume that relates to the same date.
I can also say that in terms of comparing the failure rate of water mains of interstate providers, it does demonstrate how favourably SA Water performs in this regard. The national performance report compares the failure rate of water mains of utilities between comparative interstate providers, that is, those with a customer base of over 100,000 customers. I am advised that for 2013-14, South Australia statewide had a failure rate of 11.5 failures per hundred kilometres per year and, in comparison, as I said earlier, Western Australia experienced 17.3 failures, Victoria experienced 32.2 failures and Sydney Water experienced 30 failures. I read into the record previously what those actual figures were and, again, they show that SA Water performs remarkably well in comparison to those other utilities.
I don't think you asked a question about wastewater mains. I will undertake to take those other detailed questions the honourable member asked and bring a response back to the chamber on his behalf.
May 17, 2016
In reply to the Hon. J.A. DARLEY (9 March 2016).
The Hon. I.K. HUNTER (Minister for Sustainability, Environment and Conservation, Minister for Water and the River Murray, Minister for Climate Change): The Minister for Water and the River Murray has received this advice:
I am advised that SA Water's maintenance program follows both preventative and breakdown maintenance methodology.
I am advised that SA Water maintains an asset register of the location and asset attributes of every pipe, valve, fireplug and water meter in the network.
The condition and performance of individual pipes within the water network are also monitored and recorded every day by SA Water. A large detail desktop review of the total water network is conducted between February and March each year to set the following financial years capital works programme. Outside that period SA Water investigates individual pipes under individual projects and set priorities for either replacement or inspection.
As per the previous point, the entire water system including the suburbs of Campbelltown, Newton and Paradise are analysed between the months of February and March to set the capital programme. Outside that period SA Water investigates individual pipes and set priorities for either replacement or inspection.
Within the suburb of Campbelltown, there is 53.1 km of water mains laid between 1880 to 2014. The Campbelltown water network has an average age of 55 years.
Within the suburb of Newton, there is 35.5 km of water mains laid between 1889 and 2015. The Newton water network has an average age of 50.
Within the suburb of Paradise, there is 55.3 km of water mains laid between 1889 and 2014. The Paradise water network has an average age of 51 years.
A State of the Assets Report is tabled in parliament twice a year which reflects the performance of water main assets.
Within the metropolitan area, SA Water uses soil data that was collected and tested by the Department of Mines and Energy in 1996. Between 2006 and 2009, SA Water undertook an extensive investigation into soil movement and water main failures. This relationship between soil and pipe failures is still monitored by SA Water today with failure patterns observed in 2009 consistent in 2016.
Soil within metropolitan Adelaide is separated into two horizons. The A horizo n is the higher level and the B horizon is the lower level.
There are 21 soil classification categories identified within the A soil horizon, which ranged from sandy alluvial material to the aggressive red brown and black earth clays and a variety of clays types within the lower (B) horizon. They include the Keswick c lay and Hindmarsh clay to name a few.
Across Adelaide, Gilgai formations commonly occur when the increase in moisture content of a lower soil horizon (B) causes the soil to swell and heave itself upwards through the upper soil horizon (A) to provide micro relief. Within Adelaide the most significant occurrence of Gilgai formations would occur within a Keswick or Gley clay B horizon and a black earth A horizon.
Unfortunately the suburbs of Paradise, Newton and Campbelltown are predominately located within Black earth soils as an A horizon and Keswick clay as a B horizon. As a result, the majority of failures within this region are attributed to circumferential cracking and ground movement.
The influence of aggressive soil movement, due to changes in moisture content in both horizons, has the potential to apply multiple forces on the water main. First frictional forces from soil cracking can pull against the main, and second, swelling of soils can cause uplift and result in negative bending moments applied to the main. This supports the monthly failure trend within the network and sees peak number of water main failures in March to June and significantly lower number of failures in October and September.