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Reducing run times, increasing pump efficiency expected to yield savings for Wolcott, Conn.
America’s wastewater is conveyed daily by tens of thousands of pump stations, many of which were originally installed in the post-war boom era as our nation rapidly expanded. Many of these original stations still operate throughout the country, mostly in underground, dry-pit configurations. As such, municipalities with older pump stations are ultimately faced with the decisions of replacing them completely or finding less expensive routes through retrofitting internal equipment. Many times the station structure is fine, but the pumping equipment, controls and other integral elements can be replaced for improved performance and energy savings.
In the late fall of 2008, one such municipality, the Town of Wolcott, Conn., faced the prospect of rehabilitating four different pumps in two separate aging pump stations. Originally installed in the 1960s, the town’s underground Mattatuck Avenue and East Street Pump Stations each contained Allis-Chalmers 4 x 4 x 10LC model 300 pumps.
Town Administrator for Sewer and Water Phil Olmstead sought pump retrofit solutions, but it wasn’t as simple as one might surmise.
“They are deep can stations and any piping modifications, or to the piping layout, was crucial not to disturb the existing [shell],” Olmstead said. Major piping modifications would prove difficult because of the depth of bury—especially moving materials and tools up and down—and any welding inside a buried steel chamber can adversely affect the shell’s original integrity. Yet, it was still prudent to find ways to maximize pumping efficiency and performance.
While gathering information on the feasibility of retrofitting, Olmstead came into contact with Smith & Loveless (S&L) representative Sarah Gager of New England-based J&R Engineered Products. Gager met with Olmstead and visited the pump stations and helped Olmstead determine a correct solution that not only met his specific needs, but also delivered beneficial cost savings for the long term with less maintenance and power demands. Because S&L has manufactured pump stations continuously for more than 60 years, it has significant experience in retrofitting aging lift station equipment, including flooded suction pumps from a variety of original OEMs.
After examining the station, the S&L team was able to provide a solution that facilitated the change-out of all four pumps—without any piping modifications—while offering significant improvements in terms of performance, ease of maintenance and durability.
The original pumps were replaced with Model 4B2A S&L Pumps , including pump stands that were simply dropped in and bolted in place. The East Street station gained two 10-hp 4B2A S&L Pumps rated at 220 gal per minute (gpm) at 69 ft TDH, while the Mattatuck Avenue station received two 3-hp 4B2A S&L Pumps rated at 260 gpm at 23 ft TDH. These S&L Pumps are designed for decades of service life because they come equipped with oversized stainless steel pump shafts, bronze mechanical seal housings and custom-trimmed heavy cast-iron balanced impellers. This combination severely limits the potential of mechanical seal failure over time and the need for frequent pump rebuilds or replacement.
Just as importantly in these times, Wolcott’s new S&L Pumps also came equipped with NEMA-rated Premium Efficient motors, which combine with S&L’s published high pump efficiencies to provide superior energy-saving results. In fact, the Mattatuck Avenue station represented a minimum increase of 9% pump efficiency while the East Street station pumps improved by 5%. Factor in S&L’s premium efficient motors, typically at 90% and greater, and the result is a considerable difference in wire-to-water efficiency, reduction in energy demand and an improved bottom line for the town.
“I can already see a pretty substantial drop in [the] electricity bills,” Olmstead noted. “Plus, I’ve noticed that [the station’s] run times have dropped off substantially, also.”
This is particularly critical in Olmstead’s town, where an influx of seasonal wet weather can contribute to considerable infiltration in the town’s system. Reducing run times while increasing pump efficiencies can yield hundreds of dollars of savings annually from a single pump station. And when the energy demand required for these stations to operate 365 days a year is reduced, the carbon emissions required to produce that energy is also reduced, which makes for a more sustainable environment for all.
As a whole, the pump station retrofit has proven to be very positive for Olmstead and his town.
“From the get-go, I was very impressed from start to finish with the service, the treatment,” Olmstead reflected. “[The pumps] are running great, and it’s nice going down in there [inside the stations] knowing that the replacement parts, part numbers, all match serial numbers of the pumps.”