Increasing the value of wastewater network monitoring

Increasing the value of wastewater network monitoring

Innovation is the key to delivering ever-increasing performance

Asset owners around the world are looking for innovative ways to deliver on the challenge of increasing wastewater network performance targets. With improved technology and the ability to handle large amounts of data, it’s become significantly easier to monitor flow and depth patterns, and highlight issues within a network that trigger a maintenance response prior to a flooding or pollution incident occuring

waste water monitoring

Radar level and IoT telemetry device from Metasphere (Sense Level, ART Sewer)
Wastewater monitoring can generate a return on investment when they prevent flooding and pollution incidents.

Of course, there is no point in installing monitors for the sake of it, they should be positioned so that they have the greatest value. Having monitors in areas that don’t generate a return on investment is not prudent, therefore knowledge of current system performance and planning is required to determine the optimal locations that will provide a positive return when installed in locations that are most likely to prevent flooding or pollution incidents. 

The most important part of the puzzle in locating monitors is to understand the characteristics of the most common failures within the network; blockages. A previous UKWIR project  identified the following: 

  • 20% of blockages reported over a year are repeats at property level and this increases to between 40% and 60% when analysed at the postcode level. 
  • The proportion of repeats increases to 30% and 70% at a property and postcode resolution respectively when there are 5 years of data available. 
  • Approximately 50% of postcodes and 4% of properties have suffered 1 or more blockages over a 9-year period, this reduces to 23% of postcodes and 1.2% of properties suffering repeat blockages over the same period. 

 

Picture of sewer blockage

Analysis of historic blockage data indicates blockages repeat at the same location over time.

This analysis shows repeat blockages happen at the same location and that if monitors are located correctly, they can be effective in preventing major incidents. 

 The report also identified the most common causes of blockages: high density of interceptors, high densities of FOG (fats. oils & grease) generating properties, older properties, terraced / high rise properties, small diameter sewers and lower affluence. 

 This suggests that taking remedial action such as removing interceptors, root cutting, repairing structural defects and educating customers about the use of FOGs and wet wipes would mitigate the probability of repeat blockages. Fixing the root cause will prevent having to constantly reattend to carry out blockage clearance maintenance, which causes inconvenience for the customers and increases operational costs. 

 In a perfect world asset owners would repair and replace all the defects in a wastewater network. The reality of course is there is no bottomless pit of money for this activity and funding will continue to be challenged given the current focus on the affordability of utility bills.  

Person calculating his expenses

The affordability challenge associated with utility bills means there will never be sufficient funding to repair all defects on the network.

Repairs are not always practical or cost effective

 This is where asset management comes in and provides us with the capability to effectively balance the cost, risk and performance triangle depending on the objectives of the asset owner. For example, In the case of complicated wastewater networks that may run beneath buildings with a flat gradient that increases the blockage probability, then the implementation of a proactive cleansing programme is likely the best approach to balance cost, risk and performance.  The use of monitoring in these situations allows the proactive maintenance costs to be optimised and ensure cleansing is only completed when it is required. 

Cost, risk and performance triangle

Asset Management provides the capability to balance the cost, risk and performance triangle to deliver the asset owner’s objectives.

Alternatively, the installation of a monitor where roots have been identified or where a partial collapse has occurred is unlikely to balance the triangle correctly. It will likely be more efficient to mitigate the root cause (e.g. cut out the roots or repair the collapse) compared to monitoring the location.  

Data is key to making informed decisions

The ability to adapt the correct balance of cost, risk and performance for each scenario is based on having the right data available to understand the root cause of a flooding or pollution location.  Using CCTV pipe inspection data provides the ability to understand the root cause and enables monitors to be installed at locations where they can generate the greatest Return on Investment (ROI).  The historic challenges with CCTV pipe inspection data have been its cost (e.g. it is not cost-effective to survey the entire network) and the ability to provide the outputs in a format that allows good investment decisions. 

 VAPAR uniquely combines Artificial Intelligence, the latest software capability and human input, reducing the cost of CCTV pipe inspections and making the outputs more accessible to decision-makers. Reducing the cost of CCTV pipe inspections makes it more economical to either complete CCTV pipe inspections prior to installing a monitor or use existing inspection data as part of the monitoring decision-making process. A great example of making the CCTV pipe inspection data more accessible is the visualisation of the survey results via a GIS, where the defect locations can be understood relative to the proposed monitor location on the pipe network. 

Pipe network and defects seen on GIS using VAPAR

VAPAR’s capability to visualise CCTV pipe inspection data allows monitoring locations to be identified that will deliver the greatest ROI.

Conclusion

It is fundamental for Asset Managers to look at alternate and innovative ways of managing pipe networks if they are to deliver the increasingly challenging financial and performance targets. The use of network monitoring provides one of these innovative ways, however, it will not provide a ‘Silver Bullet’ in isolation.  The use of VAPAR alongside monitoring will allow CCTV pipe inspection data to inform the decision-making process on where to install monitors. Ultimately this will balance cost, risk and performance and ensure the return on investment from monitoring is realised. 

Nathan Muggeridge - Author

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