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Session 12B: Collection & Conveyance - Pumping Systems
10:30am - 11:15am
Decoding Water Hammer: Comparing Real Measurements With Modeling Predictions
Brown and Caldwell, United States of America; firstname.lastname@example.org
Transient pressures can cause significant damage to force mains and pumping systems, leading to pump station down-time, sewage overflows or water loss, and costly repairs. Numerical modeling can help address the issue, but results can be difficult to understand or implement correctly. This presentation will use three case studies to explain water hammer and how numerical modeling helps to avoid problems with transient pressures in pumping and pipeline systems.
In the first case, an existing sewage force main experienced pressure damage. After monitoring data confirmed hydraulic transient presence, numerical modeling identified that installing a surge tank at the pump station would be the most effective mitigation strategy. Following the installation of the tank, field measurements closely agreed with pressures predicted by the modeling.
In the second case, monitoring equipment detected transient pressures during the startup of a new pump station. Using field measurements to calibrate a numerical model of the system, the team determined that the addition of flywheels on the pumps would address the issue. Field measurements closely agreed with pressures predicted by the modeling following the flywheel installations.
In the third case, a numerical modeling study performed during design led to a recommendation to install surge tanks at the pump station. Transient pressure measurements obtained during pump station startup closely agreed with those predicted in the numerical modeling study.
This presentation will detail the convincing evidence that transient pressure numerical modeling is a critical step for developing resilient force main and pumping system designs. Numerical modeling provides reliable data for developing a surge mitigation strategy and reliably assess when a surge mitigation strategy is successful.
11:15am - 12:15pm
Challenges and Opportunities Presented by Diversion Pump Stations
When sewer trunk systems reach capacity, agencies occasionally elect to install a pump station to pump past the bottlenecks rather than upsize the line or build a parallel pipe. This is typically due to the higher capital expense of a trunk sewer caused by environmental mitigation requirements, pipe depth, and traffic disruptions. On the upside, constructing a diversion pump station can often be the more expedient way to meet upstream development demands or reduce risk of overflows. Conversely, a diversion pump station also provides new challenges for Operations through increased maintenance time and cost. However, the facility can also offer flexibility to an agency’s overall operations, providing opportunities to address operational concerns elsewhere in the system through automation, flow control, and redirection of flow to underutilized infrastructure in the conveyance and treatment facilities.
This presentation will provide two recent case studies in diversion pumping: the City of Vancouver’s Burnt Bridge Creek Pump Station, a 7-mgd diversion pump station that was mothballed 20 years ago because of maintenance-related issues; and Clean Water Services’ Dawson Pump Station, a 20-mgd facility built to increase conveyance capacity for supporting industrial growth, hampered by constituents in the industrial wastewater. Discussion will include the projects’ origins, the operational issues encountered along the way, the solutions engineered to optimize the facility’s operation, and the opportunities to use the diversion to further improve overall conveyance system performance and reliability.