While the city of Sublimity, Oregon, relies on a nearby municipality for wastewater treatment, the city utilizes its own sewer collection system. Built in 1975, portions of the collection system had exceeded the expected lifespan and become inefficient, with growing maintenance needs. The population of Sublimity had also grown to about 3,000 residents since the system’s construction, with three new 100-parcel subdevelopments approved.
One failing pump station in the system had become unable to handle the increase in pump run times and household flushables. This resulted in increased wear, higher maintenance costs, and more labor-intensive maintenance tasks.
The city of Sublimity sought a solution that would help eliminate the clogging issues and increase the efficiency of the pump station, allowing the staff to be more productive with their time, reducing maintenance costs, and leading to power savings.
The cost of pump clogging
With increased demands on the wastewater system, the station’s two vortex pumps began to clog on a regular basis. Each incident required a two-man crew to remove the clog and reset the equipment – a four-hour process, made more difficult by the limited maintenance accessibility of the pumps and the wet well. That was a whole man-day of lost productivity. This was especially troublesome for Sublimity’s Public Works Department (DPW) as it oversees not only the sewer pump stations but also the water distribution system, maintenance of the two city parks, streets, and city hall upkeep.
This single pump station was costing the city $3,360 in annual labor costs alone. The buildup of rags and other debris in the wet well required the city to also contract for a quarterly vacuum truck callout, an additional $8,000 per year.
The Sublimity DPW team had a two-fold challenge:
- Address the time-consuming nature and inefficiencies of a failing pump system
- Improve capacity to address the current and future needs of a growing residential area
Partnering for a solution
Like many municipalities, the Sublimity DPW works under tight budget constraints. DPW leadership worked directly with Xylem representatives to engineer a complete design-build (DB) solution with full technical support. DB project delivery methods allow the customer more input into the design and equipment selection, while also shortening the overall project schedule. With the time saved, the DB process can create a lower overall price tag for the project. For Sublimity, direct procurement saved the city nearly $50,000 and allowed them to work directly with Xylem experts throughout the entire process. Xylem was also able to engineer and provide a temporary bypass system, using Xylem’s Godwin pumps, to avoid service interruption during the work.
Xylem’s application engineering team designed a solution that leveraged Flygt Concertor pumps, a controls building, TOP wet well insert and new valve vault. The centerpiece of the design was the Flygt Concertor XPC, an intelligent wastewater pumping solution with advanced control capabilities.
For the city of Sublimity, Flygt Concertor’s automatic clog detection and pump cleaning was key in addressing ongoing clogging issues. The Concertor pump features the Flygt Adaptive N® impeller, which moves axially to allow larger debris to pass through. The built-in intelligence of the Concertor pump adds another layer of protection by detecting any clog forming and automatically initiating a self-cleaning sequence to clear it.
Flygt Concertor can also operate across a broad performance range, instead of being limited to a single pump curve. The city was able to replace the aging 15 and 20 hp pumps with more efficient, versatile 10 hp Flygt Concertor pumps, decreasing the overall installed power. The improved pumping performance of the Flygt Concertor XPC is in fact delivering the same duty point at only 3.5 hp, saving the community a considerable amount of energy.
Short- and long-term operational benefits
The upgrade to the lift station has provided numerous immediate benefits in operating costs, efficiency and maintenance requirements. Since the new pumps’ commissioning, the station has experienced no clogs, compared to monthly clogs and callouts with the previous system. The solution has also reduced the daily run time of the pump station to 30 to 45 minutes, compared to 2 to 3 hours with the previous vortex pumps. Furthermore, the efficiency of the Concertor XPC pump system has left the city of Sublimity with 6.5 hp of untapped capacity – ready for future residents without needing expensive upgrades or retrofits.
Operations and maintenance staff are able to review both real-time and historical pump performance, complete with trending analysis, on-site via the HMI touchscreen or through their SCADA. Fine tuning operations is straightforward with the Concertor XPC software platform.