Day after day, thousands of people drive through the intersection of 163rd & Central Avenue. It’s a good bet that hardly any of them realize that just a few feet below the intersection there is an underground booster station that sends drinking water to almost a quarter of a million people in the Chicago suburb. This booster station, owned and operated by the Village of Oak Lawn, assists the two main stations in providing water to 330,000 people and helps Oak Lawn overcome the elevation difference between themselves and their customer communities.
Municipalities are required to have enough redundant capacity to meet pumping requirements, which is why this #2 Booster Station needed to be expanded. The addition of these new units, scheduled to be installed in 2017, is projected to accommodate the upcoming need for increased capacity. Since 2010, the Nijhuis pump drives have operated reliably in the #2 Booster Station, exhibiting long service life and low maintenance for the Oak Lawn Water Department. When it came time to expand the station, it was an easy choice to add two more of the exact same units, which are projected to provide the same reliable performance as demand for clean drinking water grows in the Chicago suburbs.
The expansion of Oak Lawn Booster Station #2 involves the installation of two vertically-mounted split case centrifugal pumps, supplied by Pentair. The pumps are rated for 6000 GPM at 80 ft. total dynamic head. Each of these Pentair Fairbanks Nijhuis vertical split case pumps, model 10” 2844A with 14”x18” Turbo Free Elbows, is equipped with a Dynamatic® eddy current drive which operates with a small, digital controller. The combined eddy current drives and 150HP 1200 RPM motors are mounted on top of the vertical pumps with the support of fabricated steel structures to accommodate the weight and rotating load of the equipment.
These incoming units are identical to the existing 3 units which have been operating in the Oak Lawn Booster Station since 2010. The Pentair 10”2844A pumps were selected for the original installation because of the following reasons:
Performance – The energy required to move 6000 GPM is significant, and over the life of the booster station every percent of efficiency matters. The Pentair 10” 2844A are over 85% efficient at the design point, and 88% at their best efficiency point, helping to minimize the total energy consumed. To further reduce the total energy losses of the system, Pentair also supplied their Turbo Free elbow with these pumps which provide the performance benefits of a long radius reducing elbow in the space of a short radius elbow.
Footprint – Due to the layout of the pump room, space is at a premium. To overcome the space issues of traditional horizontal split case, the Fairbanks Nijhuis pumps were mounted vertically, reducing the required floor space by over 40%. Additionally, the Pentair Turbo Free elbows provide the same performance of a traditional long radius elbow in the footprint of a short radius elbow, saving an additional 5” of total length, without the reduced performance of a short radius elbow.
Durability – Pentair Fairbanks Nijhuis is known for providing long lasting durable pumps. Since their install in 2010, these pumps have not required any maintenance or service beyond what is typically required.
Materials of Constructions – Since these pumps are supplying drinking water, they were built using stainless steel wear components such as the wear rings and shaft sleeves and nickel aluminum bronze impellers for resistance to chlorination in the water as well as eliminating lead from the main components in contact with the water.