Renovating a Houston-based Detention Pond’s Stormwater Pumping System
Three new pumps, a “smart” controller and SCADA monitoring makes this detention pond a fully monitored system that is easy-to-operate and provides operational savings and peace of mind to the property owner.
Construction EcoServices maintains the stormwater detention pond at a large retail complex on behalf of a national property management firm. The pond is 4-acres and collects runoff from several more acres of parking lots and shopping center roofs. The pond itself drains to a stormwater pump station through three large gravity pipes.
In 2018, the property management company had a problem. Two of the station’s pumps – long-shaft mixed flow pumps – failed, leaving only the third pump running. What made the problem worse is that the size of the pumps made them difficult to remove from the station. The pumps were 31-feet long, not including the motors, and their size made them costly to remove for maintenance. “Just to have the old pumps pulled out cost about $9,000 to $10,000 each time,” said Stephen Thomson, a detention pond system specialist at Construction EcoServices. “And, it would take a full day. Plus, we also pull the pumps out each year to clean the station of sediment”, he added.
With two of the station’s pumps out of service and deemed beyond repair, replacing them was a must. For this project, Construction EcoServices partnered with the local distributor of a trusted pump manufacturer. Working hand and hand with the distributor and the pump manufacture’s Applications Engineer, the team decided upon a combined solution of two 60-HP pumps, a “smart” controller, and SCADA to provide remote monitoring and diagnostics. The chosen pumps are close-coupled, mixed-flow pumps with much shorter shafts. And, since the pump manufacturer also manufactures its own motors, there is will be no future need to contact a separate motor vendor. Future maintenance of this solution will be far simpler and faster.
This solution would replace the 90-HP pumps with more efficient motors while matching the 7300 GPM flow for each pump. The new pumps would require less power, and their compact size would make maintenance easier.
However, complicating the upgrade, were three pump tubes at the site. The tubes were cast-in-place in the shape of three parallel L’s at the base of the station. Stormwater would flow by gravity from the pond into the horizontal leg of each L. The pumps were installed in the vertical leg of each L. The L’s would have to stay in place, but they were too large for the new pumps. To overcome the issue, the team designed smaller-diameter tubes to fit inside the existing L’s and house the new pumps.
With the two new pumps, controller and SCADA in place, the system worked as intended until one year later, when the system began to identify very short run times for pump number three – the one old pump that had not been replaced. The pump was failing, and the system caught it. As a result, the team came together again to replace the third pump in 2020. Today, with all three pumps replaced, the stormwater station is an easy-to-operate, fully monitored system that provides savings and peace of mind.
“We still pull the pumps once a year to clean the station of sand and sediment,” Thomson says. “Only now, these new pumps can be pulled with smaller equipment. So, instead of $9,000 to $10,000 per site visit, it’s just a minor service charge now. And, if the pumps ever need service, they could be serviced right there on site.”
The compact size of the new pumps, their efficiency, and their connectedness to SCADA have proven to be a great value to the customer. The property owner is able to monitor the levels of the lift station, monitor for power outages, and capture run times with the SCADA system. Now, the customer has the peace of mind they wanted in the face of future hurricanes and flash floods.