Editor-in-Chief Elisabeth Lisican showcases a handful of features to read in the April 2017 issue of Water & Wastes Digest.
Pump technology helps Louisiana parish reduce callouts
St. Tammany Parish, La., which has a population of approximately 250,000, sits north of New Orleans on the opposite side of Lake Ponchartrain. Utilities Inc. of Louisiana (UIL) operates 192 sewage lift stations and 30 wastewater treatment plants in St. Tammany Parish. In 2011, Gulf States Engineering Co. Inc. – a Xylem distributor from Covington, La. – began a working relationship with UIL to replace lift station equipment that was dealing with an increasingly problematic wastewater stream.
Using the Flygt N-pump, Gulf States began a program to replace all of UIL’s major lift station equipment, which previously had been plagued with clogs resulting from a difficult wastewater stream riddled with “flushables” and other debris. To date, UIL has been very satisfied with its energy savings, reduced unscheduled maintenance due to clogging and overall dramatic improvement in the quality of its stations.
When UIL was approached regarding the Concertor trial for the southern U.S., featuring an integrated and intelligent pumping solution, it jumped at the opportunity to participate. Concertor combines a fully integrated control system with IE4 motor efficiency, state-of-the-art adaptive N-hydraulics and intelligent functionalities. By integrating a control system that can automatically adapt to an ever-changing wastewater environment, the optimal level of performance is delivered while significantly reducing total cost of ownership. All of this has been achieved with a much smaller footprint.
The sewage lift station chosen for the installation was a commercial site near a major shopping center in an area that serves retail, restaurants and private residences. The existing station had been upgraded in the past two years with a pair of Flygt NP3127 HT 10-hp pumps that were working well at the time of the upgrade. The desire to participate in the trial allowed UIL to determine how the use of variable frequency drives (VFDs) may reduce operation costs while simultaneously testing new technology.
In August 2015, one of the existing pumps was removed from the station completely and its controls were elevated so they could operate only during periods of high inflow or demand. The Concertor trial pump was then installed with its own monitoring system in about an hour and began operation. One of the key drivers in UIL’s participation was the fact that this station pumps into a 16-in. manifold force main and directly to a treatment plant about two miles away. Knowing that off-peak demand would benefit from the use of a variable-rate pumping system, UIL wanted the opportunity to determine how much might be saved by utilizing current technology.
Within a short period of time, significant energy savings of $1,000 per month were observed at the site due to reduced power consumption during off-peak periods. What is more, demand charges were reduced due to the use of the integrated VFD in the unit, which completely eliminated inrush current during starting.
Additionally, the Concertor pump features several other benefits observed by UIL. The built-in sump and pump-cleaning feature rendered the station completely free of grease and floatables previously observed. Accordingly, the need for frequent and regular station cleaning that was normally a part of UIL’s protocol was eliminated. UIL estimates that the cost of each cleaning was approximately $350.
A second feature of the system that was highlighted is the clog detection feature. The station has not required any unscheduled maintenance or callouts during the trial period, resulting in additional costs savings over the previous pump setup – unscheduled callout maintenance is valued at $1000 per incident, and they previously occurred about twice a year.