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Wastewater Lift Station, Colorado, USA


Location: Denver, USA
Industry: Water and Sanitation
Timeline: 2022


Roxborough Lift Station was in need of an upgrade. A specification was written for pumps, variable frequency drives, and a harmonic filter to increase facility capacity for future expansion. Owned and maintained by the Roxborough Water and Sanitation District (RWSD), the station is responsible for pumping wastewater to a treatment plant 14 miles away. It has three intakes from the region and is equipped with 1-200HP, 150HP, and 2-160HP pumps with VFDs which lift the sewage the first 7 miles of the journey, while gravity takes care of the final 7 miles.


The station’s 15-year-old pumps will be replaced with new, larger pumps, motors, VFDs, and active harmonic filter. The updated design will handle an increasing amount of sewage from the Denver area. RWSD wanted to ensure that all harmonics from the VFDs would be properly taken care of in accordance with IEEE 519. An existing passive filter would also need to be replaced, and so RWSD contacted Comsys for help. 



When Comsys studied the system design, it was realized that not all VFDs would be able to run on the existing utility distribution transformer. After determining continuous operational load vs. back up pumps for “emergency conditions only”, operation of the facility was understood. Using the Comsys Sizing Tool to calculate the harmonics, we were able to arrive at a suitable solution. The station’s passive filter was replaced with two Comsys ADF PPM300 modules installed inside a standard Comsys CAB8 cabinet. The use of an expanded enclosure will allow future installation of another 110-amp module in the same enclosure if required.

Commissioning was carried out by a local partner in collaboration with a Comsys technician who participated remotely via an internet “Teams” connection on a laptop connected to the Comsys filter at the site. No custom software was required. The solution also involved a feature unique to Comsys – the ability for the customer to plug a laptop into the filter and enable Comsys to remotely monitor the filter’s performance (voltage and current distortion) and make changes in real time. 



Comsys has provided a solution by designing a system that met the customer’s needs, arrived on time, and surpasses customer expectations in performance. The Comsys ADF Filter meets the required IEEE-519, has flexible packaging, and can determine faults online. If trouble arises, Comsys technicians can review wave forms for the past 12 months by having the customer connect the filter online to our Technical Service Group, thus eliminating the need for an initial onsite service call. The Comsys installation has been operational since October 2022. The facility’s engineers have been trained and are able to monitor the ADF P300 filter online if desired by connecting an Ethernet cable to the LAN connector on the front of the CM CAB control module.

At Comsys, we pride ourselves on delivering solutions that meet our customers' needs and exceed their expectations. The Roxborough Lift Station project is a testament to that, as we designed a system that not only met the required IEEE-519 standards but also provided real-time monitoring capabilities for the customer.

Michael Tibbitts

Regional Sales Manager