New sensors, data transmission technology improves sewer system management

By Greg Quist

Our cities are facing a crisis. Infrastructure that has served us well for decades is aging, degrading and failing. While the impacts of failed water systems rapidly become apparent with supply interruptions and leaks flooding roads and neighborhoods, sewer and stormwater systems are typically unmonitored and, therefore, difficult to manage and control.

Exacerbating the problem is that these systems are being subjected to operational conditions beyond their design parameters. Recent data suggests that extreme rainfall events have been increasing in number since 1950, with severities that routinely exceed common engineering design criteria like the “100-year storm”. This analysis is the embodiment of the fact that the conditions to which we designed in the past will not apply in the future.

These new operating conditions are straining engineered systems to the point of routine failure, placing life, health and property at risk when untreated water gets discharged into the receiving environment.

This mismatch of increasing flow versus capacity is part of the funding deficit in water infrastructure that communities will be facing over the next 20 years. While the need exists, the funding often does not. As a result, utilities need to be able to maximize the operational availability and capacity of their existing infrastructure.

This requires expanding the focus from “grey and green infrastructure” to include “data infrastructure”, which is the equipment, systems, communications and platforms necessary to monitor, control and optimize that infrastructure. The benefits of doing so will allow for active, rather than passive, management of our collection systems, resulting in the ability to:

• Reduce or eliminate sewer backups and street flooding;
• Reduce or eliminate sanitary sewer overflows;
• Reduce or eliminate combined sewer overflows;
• Avoid excessive sediment deposition in the sewers;
• Optimize cleaning routines;
• Manage flows during an unplanned (not anticipated) system disturbance, such as major equipment failure or security-related incidents;
• Manage the rate of flow arriving at the wastewater treatment plant.

Most importantly, understanding the condition of collection systems in real time means utilities can continue to protect public health at lower operational and capital costs. SmartCover has developed, deployed and operated “data infrastructure” that allows utilities of any size to have a monitored sewer system.

Moving beyond The green and grey: data infrastructure

In order to fully understand the dynamic operation of any system, insight is needed into the operational conditions existing in it, while recognizing the impact of external factors on those operational conditions. Ideally, we must be knowledgeable enough to deduce the response of the system to those internal and external forces.

Historically, sanitary and stormwater systems have been passive, leaving little opportunity to understand their real-time condition and maximize their utility. The availability of systems like those offered by SmartCover is changing that by enabling the collection and analysis of data and providing operators with the tools to take action.

Data collection

For sewer collection and stormwater management systems, data collection is hampered by geographic extent, the hazardous operating environment, and the fact that power and communication infrastructure is often not available in most locations.

As they are distributed throughout a community, the necessary sensors must be inexpensive enough to be able to be deployed at a density that provides a view into the operation of the entire system. Also, their deployment needs to be optimized to provide maximum information with minimum costs.

Operating in the hazardous environment of confined spaces complicates the technology options and is potentially deadly for operators. In order to avoid confined space risks, sensors that are mounted and maintained outside that environment (in the open air) and capable of withstanding all conditions (IP-68 rated) are critical.

Finally, as direct power connections are not possible within these environments, a sealed high power-density battery system designed for reliable, long life and consistent delivery of power in the harsh wastewater environment is vital.

SmartCover sensors are contained in a sealed unit with lithium thionyl chloride primary batteries and have a typical operational transmitting life of more than two years under normal operating conditions.

Communication

Along with power to operate sensors, the capability to transmit that data so that it may be analyzed is also needed. Again, with the distributed nature of these systems, providing a low-cost, reliable communication network is essential. A unique factor in monitoring sanitary and stormwater systems is that the failures are typically correlated with large-scale external factors, such as high-intensity storms, floods, hurricanes or earthquakes.

Unfortunately, in many cases, these same events can disrupt wired, radio and cellular communication networks. While an operations centre will be provided with emergency power and “backup” communications, absent a reliable communication mechanism, data from distributed systems will not be there.

This is where the advantage of using low cost, low bandwidth, highly reliable satellite communications comes to the fore. SmartCover’s communication network is powered by the Iridium constellation of 66 cross-linked Low Earth Orbit (LEO) satellites. At an orbit of only 780 km, Iridium’s LEO network means pole-to-pole coverage, shorter transmission path, stronger signals, and lower latency than other satellite systems. Most importantly, this network is unaffected by local conditions, even during times of natural disasters. This means that, provided the SmartCover system can see the sky, the utility will get its data.

Supporting the data uplink stability provided by the Iridium satellite network is Iridium’s extensive ground infrastructure, which provides the utility with reliable access to the sensor data packets.

Curation

Once data is collected and transmitted, it must be provided with a place to reside until called for analysis. While the actual data packet being received from a particular sensor may be small, the frequency of data collection and the sheer number of sensors often leads to terabytes of information being collected over even short time frames. When dealing with utility-scale systems, there is a need to compare not only hourly and diurnal patterns but also seasonal, annual and decadal analyses. As such, a highly scalable storage platform is needed.

In addition to being stored, this data must be rapidly retrievable for analysis. This type of access demands an architecture that is designed to store, secure, host and serve the data with very low latency. As the volume of data increases, the limitations of relational databases rapidly become evident and so specialized time-series or NoSQL database architectures are required.

With SmartCover, utilities can avail themselves of the Software-as-a-Service (SaaS) delivery methodology that includes a rapidly scalable data storage and retrieval platforms, combined with access to the tools necessary to analyze and act on the data.

Analysis and action

Data is useless without the means to analyze it and turn it into decisions. However, automated data collection generates a significant amount of data, often with competing conditions, that can overwhelm operations staff.

SmartCover addresses this data overload potential directly by applying the tools of artificial intelligence (AI) to the data. The AI platform has been trained with over 200 million hours of sewer and stormwater monitoring data to identify common issues with our collection system infrastructure. Critically, these analytical capabilities have been integrated into a real-time decision support tool that provides staff with early warning and the time necessary to prevent failures.

Results

Canada is a relatively new market for SmartCover, and it is anticipated Canadian users will, as they scale their implementations, see results like those shared by earlier adopters. So far, employing sensors and AI-driven decision support tools have resulted in savings for 36 Canadian cities. Their systems are used to mitigate risks associated with sanitary sewer overflows and combined sewer overflows, to monitor systems during construction, and to optimize cleaning schedules.

Conclusion

The combination of safe sensors, cloud-based services for data management and AI-driven decision support tools is bringing our sanitary and stormwater collection systems into the 21st century on a wave of data. The ability to install sensors with integrated communication technology in any location is increasing the understanding of the dynamic conditions existing in sewers.

Greg Quist is with SmartCover Systems. This article appears in ES&E Magazine’s December 2019.