Next-Generation Wastewater Operations: Immokalee Water & Sewer District's Fully Integrated Sensor Network and Real Time Monitoring Platform for Enhancing Operational Efficiency and Disaster Resiliency

The Immokalee Water & Sewer District has a wastewater system primarily constructed in 1982 with over 80 miles of gravity collection lines, 42 lift stations, and 30 miles of force main. Because of the age of the system there has been increasing Inflow and Infiltration Issues (I&I) causing operational issues at the lift stations and wastewater treatment plant. Traditional methods such as temporary flow monitoring, smoke testing, and field surveys were useful but had limited durations and impacts. This also placed workload strains on the operations staff installing and removing the temporary solutions. To overcome this and take a more permanent and innovative approach they developed a real time wastewater sensor and software monitoring platform.

The main benefit of this system is to allow the District to have the operational intelligence to deploy assets from a priority proactive basis, as opposed to the reactive options available to the District now.

This began as a pilot test in June 2021 with three manhole level sensors permanently deployed. Since then, the District has expanded the program into 174 wastewater sensors and multiple database integrations into a fully integrated Wastewater Advanced Metering Infrastructure (AMI) system used by their Wastewater Collection Department for real-time monitoring of sewer flows, levels, hydrogen sulfide, and critical assets in areas of concerns.

Once the Smart Wastewater system was integrated into several basins, the District began to immediately see the benefits of having system-wide data, with numerous use cases for capitalizing on the real-time information.

This allows the District to rapidly identify and respond to issues, frequently before disasters occur. If a flow monitoring location measures a 'no flow' or 'high level' condition, the EOC immediately receives a text message alerting them to the situation. In fact, upon implementing the program, the District decided to utilize the flow meter high-high alarm system and directly integrated the alerts into their rapid-response dispatch system. As a result, many alarms have led to automatic web-site inspections and field verifications by 'on-call' staff resulting in less operator time wasted investigating nonexistent field issues.

#In another instance, the District's Smart Wastewater system alerted them to a dramatic change in flow characteristics. Upon investigation, it was determined that an upstream obstruction was causing the change. Consequently, the District had the line cleaned and the flow characteristics immediately reverted to their previous patterns.

What makes this system a solid resiliency platform is the use of multiple data communication platforms. Radio on the Sensus FlexNet Network. Satellite on the Iridium satellite network. Cell communications utilizing Verizon LTE-M. The combination of multiple communication channels provides resiliency during hurricanes, storms, and other weather events. This keeps the District fully informed in case the primary systems are offline. They also act as additional warning devices, monitoring for surcharging events during power outages at these lift stations.

The District is currently developing its sewer maintenance program, and their O&M department is intelligently utilizing the flow monitors to better understand silt levels and blockages by grease and/or debris. As they clean, they can immediately record changes in flow conditions, validating the positive results of their efforts from segment to segment within the system.

With meters installed at 42 sites throughout Immokalee, the District has been able to utilize the site condition assessments generated by flow meter system as 'extra inspectors.' Without the luxury of time during installation to pre-inspect and/or pre-clean each site, the District utilizes the data collected by the installation team (manhole conditions and gas levels) to help determine cleaning priorities and areas of focus.

An example of the benefits of this approach was on August 21st, 2023, the Wastewater Collection Department received an alarm indicating that there was a higher flow level than normal and the threshold for a potential sanitary sewer overflow (SSO) had been triggered. The District's Emergency Operations protocol was set into motion, and staff and sewer vacuum assets were deployed to respond.

After further evaluation by field supervisors, it was determined that there were multiple blockages that were threatening a SSO in dry weather conditions. The District quickly acted and eliminated the blockages returning the sewer basin to normal operation. This event provided operational intelligence of a blockage event.

Another event that led to the expansion of the program was the identification of illegal dumping in near real time. This event occurred in December 2022. The pilot software identified an anomaly in Basin PS-W. It was an increase in level identified by the manhole level monitoring system.

The District design includes ADS Flow Meters, SmartCover's, Xylem Emergency Lift Station level monitoring systems and integration with the flow meters at the Wastewater Treatment Plant. Future steps include full deployment of the drinking water platform to monitor water loss, water quality, water leaks, and a real time monitoring platform. This approach has been adapted from Miami Dade Water & Sewer's Wastewater AMI Program.