Perfecting Pressure

Hixson, Tenn., is fortunate to have a reliable water source from aquifers, coupled with strong leadership that enables Hixson Utility District (HUD) to deliver high-quality, low-cost water to its growing population. With close to 500 miles of water mains, it has around 26,000 metered connections and 26 full-time employees responsible for maintaining its distribution system on a daily basis. HUD’s water network is a gravity system, so major pressure fluctuations are not expected.


A New Perspective

As water distribution manager for HUD, Jeff Elrod always is paying attention to technology advancements that provide better end-user experiences. “With advancements being made in remote cellular pressure monitoring, it became evident to me that we needed a better way to monitor our distribution system outside of the normal techniques the district had in place,” Elrod said.

Most water utilities monitor their physical plants (tanks, pump stations, treatment plants, etc.), but there is much more data that can be captured in a distribution system. Prior to deploying remote cellular pressure sensors, water personnel would travel to sites to manually gather pressure information with gauges or other short-time-span recording devices. This methodology not only takes valuable personnel time, but also provides only a snapshot of what is occurring in the system at that precise moment.

Initially, HUD simply wanted to record water pressures without the need to visit locations routinely to check pressures using static water pressure gauges on hydrants and faucets. “Our plan was to install two Mueller HydroGuard remote pressure monitoring sensors as a trial. One sensor was strategically placed to monitor a specific area’s pressure; the second was placed in one of our pressure zones to see what data it would actually provide us,” Elrod said.

One of the advantages of the sensors is that they can be installed anywhere. The first sensor was installed directly into the water main using a corporation stop fitting in an area where it did not have a vacant meter setter. The second sensor was installed in a high-priority area that conveniently had a vacant customer connection available. “We simply used adapters and installed the sensor into the existing water meter setter that had not been active in years,” Elrod said.

Flow tests then were performed in areas monitored by the sensors to simulate different levels of water loss due to a variety of scenarios. The recordings during these simulations were studied to determine when a text alert from the sensors was sent to management; the severity of the issue could be determined based on the pressure drop. Weekly analysis was performed to study the regular pressure fluctuations during the 24-hour daily use pattern to determine normal and abnormal fluctuations. After testing and reviewing normal pressures in the selected distribution areas, high and low alert points were set to allow the sensors to alert water distribution operators to system anomalies that need to be reviewed.

Detailing Drops

HUD’s new sensors have provided alerts notifying personnel of water pressure drops in the system that should not occur if it is operating as planned. These pressure drops coincide with major water usage and/ or loss. “Several times, the alerts received by the sensors have allowed us the opportunity to put employees in the field to find leaks and turn off water prior to customers notifying us,” Elrod said.

This advance notice can save large volumes of treated water by getting staff on the scene to stop a water main break as soon as it is detected, and can potentially save further property damage in cases where the leak is in the pavement. In the water industry, there always is the possibility of catastrophic water loss, such as a large water main break at night that would go unnoticed by the general public, or a SCADA low-water tank level alarm failure that is supposed to notify the utility. In these scenarios, thousands of gallons of water already have been lost. A pressure sensor alarm alerting personnel of significant pressure drops allows emergency crews to address the problem quickly.

“As a person with a data-driven mindset, I was  pleasantly surprised with all the analytics that were captured, even within the first month of monitoring,” Eldrod said. “We used this information to plan for system maintenance for an issue we could see developing. Without this data, we would have waited for a system event for the issue to be dealt with.”

The sensors can be scheduled to upload data to a website multiple times a day and will automatically upload data when an issue is detected. They are suitable for monitoring system components such as pressure-reducing valves that regulate pressure zones or district metered areas. “In systems where pressures are greatly influenced by mechanisms such as pressure-reducing valves, I see a critical need for a remote method to monitor downstream water pressures more greatly than what we have,” Elrod said.

Sensors can monitor system components and provide that data to a network that can be accessed from a SCADA system at a utility or from handheld devices in the field.

Building a Bridge

There are other sensor technologies found in traditional SCADA systems that also have these capabilities, but some small utilities still have limited SCADA implementations. Even those utilities fortunate to have better SCADA capabilities often have areas where a SCADA sensor is not feasible due to a lack of power or communication lines or terrain obstacles. Cellular technology bridges the gap to monitor water pressures in areas where SCADA monitoring is not a possibility. “[We have] the confidence that we will be aware of major system issues quicker [and that] is the most significant benefit,” Elrod said. “The analytics that are continuously provided are also extremely valuable for planning and maintenance purposes. A proactive water management style is needed for the aging distribution systems of today’s infrastructure, and these types of sensors provide the ability to be more proactive and less reactive.

“Personally, as the individual supervising the distribution system, I would install as many as could be approved by a budget,” Elrod said. HUD now has four Hydro-Guard pressure monitoring sensors installed, with a plan to add two more within the next couple of months. 

Click here to view this article on pg 52-53 of Water & Wastes Digest