April 11th at 2:00 pm - 3:30 pm

AL/MS Water Joint Annual Conference

Monday, April 11, 2022 | Mobile, AL 

 

Tunneling Versus Pumping Cost Effectiveness for Handling 45 MGD Lift Station Expansion

Presented by Gresham Smith Senior Project Manager Wayne Hunter, P.E.

2:00 p.m. – 2:45 p.m. CT in Room 106 A

The North Texas Municipal Water District (NTMWD) is a regional Water, Wastewater, and Solid Waste Services provider to 80 cities and districts lying in 10 counties in north central Texas. NTMWD’s service area includes some of the fastest growing cities in the US and NTMWD’s service demands are expected to double by year 2050.

One of NTMWD’s 25 lift stations, the Buffalo Creek Lift Station (BCLS) and Force Main is rated to convey 30 MGD of wastewater from the cities of Rockwall, Heath, and Forney to the nearby plant for treatment prior to discharge. In 2019, NTMWD confirmed that the BCLS would soon reach capacity and that improvements should accommodate an additional 45 MGD in addition to the existing 30 MGD served by the existing system. NTMWD management established two options for expanding the BCLS: a conventional expansion with a parallel lift station and force main sized for the additional planned 45 MGD, or accommodating the additional 45 MGD, or the full 75 MGD, in a gravity interceptor. In this presentation, Wayne Hunter will highlight how Gresham Smith evaluated each of the three options and selected the best infrastructure investment option for addressing the required improvements to the BCLS.

 

Scrap and Start Over or Modify Existing? How Scaled Physical Modeling of a Critical Pump Station Can Provide the Answer

Presented by Gresham Smith Vice President Tim O’Brien, P.E., ENV SP

2:45 p.m. – 3:30 p.m. CT in Room 106 A

The City of Monroe, Louisiana uses Lake Bartholomew as a source of water for their Water Treatment Plant. The lake receives water from Bayou Bartholomew via the Bartholomew Pump Station, which is located on a platform in the bayou and uses two, 250 HP vertical mixed-flow pumps with a 25,000-gpm capacity to transfer raw water. The bayou’s pumps have experienced frequent failures due to inadequate hydraulic conditions, compromising the City’s ability to transfer flow and maintain the critical water source’s levels.

The City of Monroe engaged Gresham Smith to determine root causes for the premature pump failures, which had already led to excessive pump station rehabilitation in years past. After an extensive evaluation, Gresham Smith developed alternatives for fixing the pump station: one option involved completely replacing the station—scrap and start over—while the second option called for modifications to the existing station to alleviate the submergence issues, such as lowering the pumps’ intake into a new suction trench, incorporating Formed Suction Intakes, and other various alternatives.

During this presentation, Tim O’Brien will share how a scaled physical model of the existing station helped identify which option would provide the most value and help the City, ultimately calling for simpler modifications that could save the City up to $10M.