Ultrasonic flowmeters squash sanitary sewer overflows in Illinois

Lift stations are an integral part of each municipal water and wastewater treatment network, and flow measurement is a critical component for optimal performance.

Operators need detailed flow data for inflow and infiltration (I&I) studies, flow surveys and lift station performance analysis, and to determine the volume of wastewater conveyed to treatment plants from specific basins throughout town.

Management through measurement

As sewage networks and wastewater treatment plants strive for greater efficiency and cost reduction, it is imperative that they monitor and control operations more precisely.

Like other municipalities, the Village of Lombard, Illinois, relies on sanitary lift stations to pump wastewater from lower to higher elevations, resulting in costly excavation depths and high sewer construction costs.

The village has 14 existing sanitary lift stations that require 24/7 monitoring. The amount of wastewater entering and being treated by the local treatment plant is also a key metric that operators monitor.

“We had no idea of the actual flow we were pumping from the different lift stations, whether it was dry weather or wet weather flow,” said Luke Sharp, water treatment and wastewater pumping supervisor for the Village of Lombard. “We knew our sanitary stations ran a lot more due to I&I and sump pump connections and we needed to address this problem quickly so we could generate better flow data.”

In recent years, the village has experienced several sanitary sewer overflows (SSOs) and basement backups because of heavy rains in the spring and fall. This also occurred when warm temperatures during winter quickly melted snow. These types of events overwhelmed the sanitary sewer collection system.

The village’s water and wastewater treatment division decided that an instrumentation upgrade was necessary to:

• Eliminate chronic SSOs during both major and minor rainfall events;
• Eliminate chronic basement backups during both major and minor rainfall events;
• Reduce I&I within the entire collection system;
• Prevent potential high-risk failures within the collection system;
• Better analyze discharge flow information from each lift station;
• Reduce wastewater treatment costs; and
• Provide analytics to evaluate capacity for future major development projects.

The right meter in the right place

After careful consideration of different flow measurement solutions, Lombard’s utility workers found that ultrasonic transit time flow meters were the best approach for its lift stations.

Ultrasonic transit time meters enable improved diagnostics to accurately measure flow, help identify potential pump failures and initiate appropriate preventative maintenance programs on equipment at the stations, thus extending the life of assets.

These meters measure flow rate by propagating ultrasound waves into liquid-filled pipes and measuring the time of flight. The clamp-on flow meter is also an ideal solution when users cannot shut down their wastewater operations to install a traditional in-line meter. Because the ultrasonic meter measures from outside the pipe wall, there is no wear on the device, which makes it virtually maintenance free.

“Our goal was to install working, reliable flow meters at each of our lift stations in the most economical way, and the Badger Meter team was great to work with,” Sharp said.

The Dynasonic TFX-5000 ultrasonic clamp-on flow meter measures volumetric flow rates containing clean liquids as well as liquids with small amounts of suspended solids, such as surface water or raw sewage. The meter is available in a variety of configurations to meet particular application requirements.

Automated alarms and SCADA monitoring

Depending on programming and integration into the programmable logic controller (PLC), users can be alerted to out-of-specification flow conditions and access a history with the most recent alarms, error and event codes. In addition, the flow meter supports an encoder output for use with cellular endpoints for connecting to the AquaCUE or BEACON cloud-based software suites.

The village uses a supervisory control and data acquisition (SCADA) system to monitor lift stations in its network. All information is transferred to a centralized location where operators monitor and maintain each station. The SCADA system data is continuously monitored to ensure the highest possible level of efficiency.

Sharp’s team of four operators installed the ultrasonic clamp-on meters using existing conduits in the lift station flow meter manholes. Badger Meter representatives assisted with startup by visiting each site with a portable ultrasonic device to verify actual flow readings and calibrate the installed flow meters. The entire project took just two days to complete.

“The Dynasonics ultrasonic flow meters give us dry and wet weather flow readings right from the station so that we can extrapolate pertinent information and analyze I&I conditions related to sump pumps, leaky laterals or sewer mains,” Sharp said. “This allows us to focus future repair work in basins using the data we’re seeing from the meters. At the same time, access to detailed flow data enables our department to calculate the existing capacity of lift stations to support any new commercial or residential developments in the area.”

In Lombard, routine maintenance programs based on continuous monitoring activities have proven effective in increasing efficiencies at lift stations. With accurate flow data, operators can quickly respond to pumps showing a decline in performance. Operators inspect and remedy issues before they become critical problems, which could lead to basement backups or SSOs.

Friction-free operations

Demanding lift station applications in the water and wastewater industry call for a reliable, accurate and non-invasive flow measurement solution. Crucially, the flow metering equipment has to be easy to set up at a lift station without the need to shut down normal operations.

“The ultrasonic clamp-on meters were easy to install, which reduced our overall project costs,” Sharp said. “We can use the accurate flow data to better plan for capital improvement projects related to I&I and verify the costs from the wastewater treatment plant in order to prioritize our budget allocations.”