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With the launch of Practice Note 5 on Stormwater Drainage Condition Assessment, we held a series of workshops late last year on the application of PN 5. Since then, NAMS.AU has been busy with a number of our partner organisations in developing further resources to help practitioners in the area of SWD.

Since the workshops, we have commenced a number of projects, briefly outlined as follows:

1. Development of Appendix D for the new WSAA Code – Conduit Inspection Reporting Code of Australia, version 3.1. Appendix D focuses on the scoring of defects and grading the condition of stormwater drains. We are fortunate in having a team of industry experts working on this project who can carry out field surveys of SWD defects as well as provide training on the application of the WSAA Code. It will include procedures for non-manufactured conduits (brick and stone structures), as well as conventional materials. It will also include a comprehensive portfolio of photos demonstrating various defects and how these should be graded. We anticipate the update will be available on the WSAA website for holders of the code, by midyear.

2. Development through AUS-SPEC of a specification for CCTV inspection of drainage pipes. Again, we are lucky to have good industry-based support for input on this project. The need for such a standard specification was made clear in the recent workshops, where a number of practitioners highlighted the difficulties they had in specifying the appropriate outcomes required from contractors engaged in providing CCTV surveys – often at considerable cost. Again we hope to have this available by midyear.

3. Allied to the above, is the development of a guide for preliminary survey, and a coding system for surveys carried out by zoom cameras lowered into pits, either by contract or by in-house staff. We are fortunate to have strong industry expertise in the development of this guide. A number of councils have indicated an interest in trialing the guide.

4. A longer term project is to develop a spreadsheet-based toolkit for the transfer of data from the survey process into actions and funding programs that can feed into the long term financial plan of an organisation. As part of this project, there is also an intent to look at how the quality of data can be improved and consistently provided.

Lessons learned from Practice Note 5 workshops

There were a number of lessons learned from talking to nearly 200 practitioners at the workshops. Here is a summary of some key messages taken away from the lecture rooms:

• There is a need to boost awareness among buyers of SWD survey by CCTV services as to what constitutes appropriate quality of reporting. Better-informed purchasers would assist, and training offered on application of the WSAA Code by appropriate RTOs is commended. Associated with this is the need to schedule inspections on risk based criteria, namely: large pipes, assets in fine grained soils, assets regularly subjected to surcharge conditions during heavy rainfall, assets under or near critical infrastructure, flooding impacts where hydraulic capacity is reduced by blockages, assets on potentially unstable slopes, etc.  Considerable money may be wasted inspecting assets with a low risk profile.

• Similarly, training of operators by RTOs on the WSAA Code is recommended and use of only properly trained and accredited personnel is recommended.

• The use of fixed zoom cameras lowered into pits for initial inspections was highlighted as providing a good cost effective method to allow a more targeted approach for follow-up cleaning and CCTV if warranted.

• There were several examples cited of very significant early damage to RCP SWD due to acid sulfate attack - both inside and outside pipes. This highlights the need for asset managers to have a good understanding of their particular soil environments and discharges.

• The instances of damage to SWD infrastructure by other agencies having little regard for the SWD system were alarming, and it highlights the need for implementing better controls to circumvent such occurrences. Clearly, ongoing work across all levels of government is required to address that problem.

• Damage to new SWD infrastructure through poor construction practice still appears to be occurring – it seems more vigilance by councils is needed to ensure that donated assets are not in a compromised condition when handed over. The standard of construction in many stormwater assets is poor - what may appear as a defect often turns out to be built in.  Spalling is also common in concrete stormwater pipes, particularly at the ends.  Care in handling also seems lacking in most suppliers and contractors. Flush joints in stormwater are a source of significant operational problems – root entry, ingress of soil, radial displacement. Lifting holes can also be a source of significant problems

If you have any queries about the above, or wish to provide feedback, please feel free to contact IPWEA – NAMS.AU

Peter Way PSM
Chair NAMS.AU, IPWEA
pway@ipwea.org.au