Forums Posts

by Clarence Valley Council Joined 01-01-0001 12:00 AM Posts 7

Water Directorate colleagues and observers For the next revaluation of water pipeline assets, CVC is investigating ways to undertake condition assessments of pressure pipelines. Previously we have based the condition assessment largely on age and pipe material, with an "over-ride" of break history. However, in the last revaluation of the sewer network when we undertook an expanded CCTV inspection program, we discovered that a much higher proportion of the sewer network was in poor or very poor condition than had previously been determined using age and pipe material. We are wondering what methods other LWUs have been using to undertake the condition assessment of pipeline network? (We have received a proposal for an AI methodology which we understand has not previously been used in NSW but a potential concern is with the data requirements. The methodology uses more than 30 predictors and we do not old many of the data parameters so our concern is that the AI may end up with a GIGO - i.e. garbage in = garbage out result). Greg

by Shoalhaven City Council Joined 01-01-0001 12:00 AM Posts 31

Greg, Like Clarence Valley we have traditionally used age and break history as the main parameters to determine condition as the cost of large scale inspection programs is usually outside the capacity of water utilities. I did however try to set up a program to use adhoc inspections such as service installations, dig ups and our internal CCTV program to provide a more cost effective system as we are out there every day digging up our assets so why not use that opportunity to record condition and atributes data to extrapolated but also confirm asset data. I used the Collector App in ArcGis and we have been recording data over the last few years but It needs a champion in the operational area to keep the awareness up as it can fall away over time as staff move on.

Anonymous

Hi Greg, Depending on the pipe material, a sewer pipe condition cannot always be determined from a visual assessment alone. Also, it might appear structurally sound, but be functionally impaired (excessive infiltration). Section 1.3 of the Reference rates manual says: To obtain the fair value of assets, the current replacement cost using the Reference Rates should be reduced to reflect the portion of the useful life of the asset that has been used up; and, It is expected that these would be used for calculating the fair value and the current replacement cost depreciation of assets. That is, it is appropriate to determine the WDV as the remaining life proportion of the CRC, ie straight line depreciation. Which is also the most equitable intergenerationally. With this approach, the only factors that impact on the fair value assessment is the CRC valuation and the Useful Life (not condition). Using the useful lives in attachment 2 will satisfy the auditors. I've found that where you determine the useful life to be less than indicated in the table, these are accepted without question (as this increases the total depreciation expense), but if you were to try and extend the useful life indicated then you will need to provide evidence (ie a condition assessment). That is, you should only need to condition assess pipelines for the fair value revaluation if you wanted to extend their useful life beyond 70 years. I prefer to stick with the Reference Rates Manual approach for Fair Value Asset Revaluation, and use our CCTV program only for identifying defects for repairs / informing our relining program. The CCTV program can then be more targeted to areas of higher infiltration / high blockages, which isn't representive of the whole network and therefore isn't a fair assessment for valuation. Regards Brett Corven