Faced with tightening permit constraints at their WWTPs, El Dorado Water Utilities (EDWU) pursued an innovative partnership with local industry to minimize financial impacts to their rate payers. The consortium constructed a joint pipeline to a less restrictive regulatory discharge location on the Ouachita River rather than implementing multimillion dollar improvements for each of their individual facilities. Hawkins-Weir’s (HW) role in this process was the design of effluent pump stations at each of EDWU’s two (2) WWTPs. The purpose of the pump stations is to allow the WWTPs to discharge their effluent into the joint pipeline.
The three (3) primary constraints for this project were budget, schedule, and complex variable discharge conditions. To fulfill EDWU’s need to minimize project cost, HW designed the pump stations with an open bottom can intake. This Hydraulic Institute approved design replaces a more traditional and expensive concrete wetwell with a coated steel header. To meet EDWU’s aggressive schedule, HW dedicated the resources necessary to complete the project design in less than four (4) months. The pump stations are required to match the variable output of the 5 MGD and 7 MGD WWTPs. To further complicate matters, the pressure in the joint pipeline can vary by over 100 psi depending on the rate of discharge of the pipeline partners. Careful pump selection, variable speed drives, and robust controls were needed to enable the Utility’s pump stations to match the respective plant flows regardless of the discharge pressure.