Project at a Glance

A municipality in the Pacific Northwest needed a sewer bypass to support a civil contractor working in their fixed facility. The civil contractor estimated the project would take five weeks, plus two weeks for system set-up and one week for system removal. During the project, the municipality required the guaranteed delivery of 21 million gallons per day (MGD) of fluid from a source well to their trickling filters. Failure to provide the full amount of fluid would degrade the trickling filter media and not allow sufficient dilution of effluent discharged into the Snohomish River. If a spill occurred that did not meet water quality standards, the Environmental Protection Agency would fine the municipality.

The fail-safe configuration developed for the project included redundant pumps and power, and PumpSentri telematics to alert the system operations team if issues arose that would threaten delivery of the required fluid. Response and repair time were critical to ensure the trickling filters always received the 21 MGD required.

Challenge: Replacing an On-Site Pump Watch with a Virtual One

To ensure the bypass pumps were always operating according to plan, Sunbelt Rentals provided PumpSentri for virtual pump watch. With the customer’s crew working on-site during the day and PumpSentri tracking operating data around the clock, project managers could be confident they’d be alerted immediately of any issues—saving the city the cost of personnel performing pump watch 24/7. To move the fluid, Sunbelt Rentals provided three 150-hp 12” electric skid-mount primary pumps with variable frequency drives (VFD) and a backup pump. All pumps were equipped with PumpSentri for telematics, which provided the team with extensive data on all pump parameters.

Set-up: Providing Redundancy for Pumps and Power

The project set-up included four pumps plus two generators from the Sunbelt Rentals Power and HVAC division, two I-line power distribution panels, and two automatic transfer switches. Although the bypass ran on power from the municipality, in a power failure, the backup generators were available to immediately switch on.

Fluid was pumped from the wet well through a common suction header and HDPE piping into a manifold, where it was discharged to the TPU piping and the trickling filters.

The flow control was transducer-based from a wet well 750’ from the pump site. To provide a steady flow, Sunbelt Rentals engineered a common suction system so the suction header was always in a state of prime. This allowed the correct amount of flow the moment a change occurred, regardless of the number of pumps running. Sunbelt Rentals programmed the VFDs to maintain a wet-well level, automatically adjusting flow to demand. The three primary pumps went on and offline as necessary. Suction and discharge both used 18” high-density polyethylene (HDPE) piping.

Pumping liquid up and over the wall through the HDPE piping and back down to the pumps created its own challenges. “Lift” was within spec for the desired flow, but an unexpected system shutdown would have created an uncontrolled siphon condition. No personnel were on-site at night, so the team developed a siphon breaker at the discharge end to eliminate the possibility of siphoning from the well and a spill. Again, that helped eliminate the need for the 24/7 pump watch.

In the discharge manifold, gate valves isolated each pump on both the suction and discharge sides. Discharge connected with a run of 16” thermoplastic polyurethane (TPU) hoses commonly used in fracking for water transfer. TPU is flexible, durable, and fast to deploy, making the pipe material ideal for a sewer bypass.

Solution: Using Telemetry Data and Alerts to Manage a Mishap

Several weeks into the project, the customer inserted a layflat discharge hose into the same well used to supply fluid for the bypass. The layflat hose became lodged in the suction inlet of the pump. The layflat was pulled into the suction stinger (the end section of pipe located about 8’ from the suction inlet).

Several weeks into the project, Sunbelt Rentals received an alert of elevated axial vibration. The goal is for axial vibration not to exceed 0.4 inches per second (in/s), depending on the system and pumps, but the reading was nearing 0.6 in/s. As soon as they received the alert, the Sunbelt Rentals team headed to the site.

Around 5 pm, the end of the hose tore away from the source due to tension. The camlock fitting at the end of the layflat hose traveled through the Sunbelt Rentals piping and wedged in a pump impeller, causing a spike in vibration. The team shut off the pump, then ran the pump up and down trying to shake out the object. The pump was run intermittently because continuing to run the pump with the camlock in the impeller and spinning at roughly 1000 rpm would have caused irreparable damage to the pump wear parts.

PumpSentri alerts and data provided the intelligence needed to support the project when a mishap threatened to shut down the required fluid delivery to the trickling filters.

Thankfully, the backup pumps were in place to kick in whenever needed. To continue providing 21 MGD, the team had to tune the other pumps to give the municipality the fluid guaranteed.

Results: Keeping an Incident from Becoming an Emergency

A virtual pump watch with fast, accurate alerts and data notified the right people about the increasing vibration and ensured an issue in the wet well didn’t become an emergency. Sunbelt Rentals was able to respond swiftly and resolve the situation.

“With PumpSentri, the pump team keeps an eye on every project no matter who’s running it or what time of day it is,” said Bariel. “We’re prepared for anything that will impact the customer, the public, or Sunbelt Rentals.”

Telematics makes having a 24/7 pump watch less necessary, because Sunbelt Rentals can set alerts for critical parameters like low/high water or fuel levels. Additionally, PumpSentri can provide alerts for parameters that on-site personnel cannot accurately observe, such as excessive vibration, flow, temperature, and faults. Instead of visiting a site at night, personnel can view data from anywhere to ensure all is well—and react only if it’s not.

“When an incident arises, telematics can ensure on-call personnel have the information they need to respond with the people, parts, and materials to resolve it quickly and safely,” Bariel added.