Asset Management

Stormwater asset quality assessment

  • 1.  Stormwater asset quality assessment

    Posted 07 August 2018 21:39
    ​Sutherland Shire Council owns and manages an extensive network of grey and green stormwater & waterway infrastructure assets.  The asset inventory data currently stored in the Council's Asset Management System is being updated. The data related to condition (structural as well as serviceability) of the underground pipes is currently missing. CCTV inspections of stormwater pipes are usually carried out on a reactive basis.

    In order to develop a prioritised asset inspection programme, Council is in the process of developing a strategy OR approach to capture the asset quality data, which will be utilised to prioritise CCTV inspections and develop management response/long term planning.  The strategy is primarily based on analysing stormwater asset data (initially pipes) in GIS to assign preliminary asset quality ratings (criticality, condition and serviceability) using multi criteria approach. The main parameters considered for MCA include pipe dia, depth, slope, location of stormwater pipe with respect to buildings/structures, above floor flooding, location with respect to transport corridor etc… Based on these ratings, preliminary risk ratings will be worked out for each pipe reach and mapped in GIS. CCTV inspection will then be programmed for high risk assets. The outcome of CCTV inspection will be mapped in GIS and asset quality/risk ratings updated. The revised asset quality ratings will be used to prepare immediate management response or consider these assets for long term planning.

    However, we are not sure if this is the best approach. I am sure other Council's must have adopted a similar OR different approach to prioritise CCTV inspections. If anyone out there willing to share their knowledge & experience on this matter would be much appreciated.


  • 2.  RE: Stormwater asset quality assessment

    Posted 09 August 2018 19:40
    ​We have an ongoing CCTV inspections program for our stormwater network in Wollongong City Council. Previously we were only carrying out inspections reactively (i.e. customer complaint) or before roadwork. Now we prioritise CCTV inspections work based on the following factors.


    1. Internal and external customer requests relating stormwater issues. We usually complete these inspections within 4 weeks. For example - notification from depot regarding suspected pipe failure, complains from resident.
    2. Investigations into complementary operational and capital projects (such as flooding investigation, road reconstruction projects etc). It has proven a worthwhile exercise. This practice has saved us from digging up failed pipes after the road has been reconstructed. Significant effort has been invested to complete the CCTV inspections at least 12 month out from commencement of construction to allow for design, procurement etc. We usually charge our CCTV inspect to the related capital works project to free up operational funding.
    3. known problem areas. Due to our ongoing inspection, we have gained local knowledge to identify problem areas. We inspect these areas proactively
    4. Large diameter pipes under collector/distributor roads in geotechnical unstable area. It is still a big driver for the carrying out CCTV inspections. However we are incorporating this factor as part of other inspections.


    We also inspect all the pipes on a network of pipes, rather than inspecting single (or few) pipes. Rational behind the approach - it is cheaper and more efficient to inspect and fix a number of pipes in one go rather than keeping going back to inspect or fix them in isolation.


    At this stage, less than 5% CCTV inspections accounts for reactive inspections. Rest of the inspections comprises of operational projects, capital works program and known problem areas.


    In my opinion, it is very important to communicate with other departments and cater for their needs as part of the inspections.


    Hope this helps.


  • 3.  RE: Stormwater asset quality assessment

    Posted 09 August 2018 19:40
    ​Hi Jogarao,
    The City of Stirling has been carrying out CCTV inspection of stormwater assets for a number of years.  We started with a sample plan, similar to the criteria you propose. This was stage 1 of our journey.
    We structured the inspections to assess each criteria (material, size, depth, ect.) to have a 95% acceptance of the age based condition assessment.  From this data, we then were able to identify pipes that had the most deviation from the aged based condition rating, when assessed against the WSAA 05 2008 code.
    Then, we developed a prioritised asset inspection programme for those pipes that are most likely to have imminent issues were identified as higher priority on our inspection schedule.  We have found some really bad pipes in ground that on paper shouldn't be a problem for decades.
    If you want to discuss this further, I'd be happy to share what we have learnt.
    Yours faithfully,
    Luke Matthews

    Technical Officer Engineering Maintenance
    City of Stirling
    08 9205 7052
    0416 951 446