Hydromatic pumps used in lift station upgrade

As the Lake County, Illinois area continues its rapid growth, the public works department found itself faced with a challenge. The Milwaukee Ave/Route 21 lift station originally installed in 1987, needed to be upgraded from its present capacity of 2100 GPM, or 3 MGD, to handle an ultimate flow of 8 MGD without interrupting service.

Working closely with Lake County public works engineer Raja Parikh, Mark Emory of Christopher Burke Engineering developed a plan to supplement the existing station without bypassing or shutting it down throughout the nine-month construction period. In addition, the original equipment would stay in service rather than being abandoned.

The contractor, A Ritacca & Son, installed a concrete wet well and valve vault adjacent to the original prefab steel structure and less than 20 feet from the Milwaukee Ave. right-of-way. The wet well was set 3’ deeper than the original 35.7’ deep station and a 36" diameter steel interconnecting tube was added to the original structure 5’ above the bottom to allow sewage to flow from the old station to the new during high flow periods. A further modification was made to the existing station. When first placed into service, the finished grade was 9’ lower than the plans called for in the rehab, so steel entrance extensions were fabricated and installed on top of the old steel structures. The guide rails were extended to allow removal of the existing pumps, whenever necessary. The valve vault received additional modifications. Site construction was supervised by project superintendent Charlie Defilippis of A. Ritacca & Son, project manager Carl Carani of A. Ritacca & Son and Dave Daniels of Lake County Public Works.

Now that the site work on the lift stations is complete, the unique operational aspects of this project are apparent. The original station utilized a constant speed triplex with Hydromatic S6L 40 HP pumps while the new station is designed around two Hydromatic S8LX 150 HP pumps rated at 2080 GPM each using variable speed drives to control pumping rates. Metropolitan Pump provided the variable speed drives and control section with operator interface and P.L.C. which controls not only the new pumps, but also a new motorized valve located on the old 14" force main. During low flow periods, the primary force main is a new 16" main. As flow exceeds 2400 GPM (sensed by a flow meter), a signal is sent, opening the 14" motorized valve allowing high flows to be discharged through two parallel force mains. The pumps in both wet wells are staged to allow a combination of constant speed and variable speed operation for an ultimate rate of 6000 GPM, or over 8 MGD.

Pentair, Inc. (NYSE: PNR) with annual sales of $2.7 billion, is a diversified manufacturer operating in three principal markets: tools, enclosures, and water technologies. Headquartered in St. Paul, Minnesota, Pentair was incorporated in 1966, with 50 operations and distribution locations in North America, Europe and Asia.