Reducing Backups in the Back River Wastewater Treatment Plant

The City of Baltimore Back River Wastewater Treatment Plant is making improvements to eliminate hydraulic restrictions and sanitary sewer overflows in its 100-year old collection system. Improvements to the facility will include construction of two new pump stations in conjunction with new fine screen, grit, and equalization facilities. NHC was contracted to provide a conceptual design review and design recommendations for the proposed influent and equalization pump stations, and then conduct a physical model study of the preferred initial design for each pump station according to the Hydraulic Institute Standards (ANSI/HI 9.8-2012). 

Both models were constructed at a scale of 1:8. The Influent Pump Station model included the downstream portion of the two influent sanitary sewers, the junction chamber, the coarse screen facilities, the two self-cleaning trench type wet wells, and the pump suction piping for all eight pumps to the location of the pump suction flange. The Equalization Pump Station model included 164 feet (prototype) of the distribution channel leading to the pump station, the trench type wet well, and the pump suction piping for the four proposed pumps. The overall objective of each study was to evaluate and identify potential hydraulic problems with the initial pump station design prior to construction, optimize the wet well design to improve the approach flow hydraulics to the pumps, and then confirm performance of the selected design over the range of expected operating conditions. In addition, the physical model was used to optimize the screen channel design to produce more uniform flow and reduce solids deposition, and confirm the cleanout cycle performance for each wet well.

The physical model study was conducted by NHC's Kara Hurtig and Thomas Demlow, with model testing by Greg Grzybowski. The project was recently featured in Water Environment & Technology (WE&T) magazine. Click here to view article.