The city will now move forward on design work for the expansion. The first phase of construction, which is scheduled to be completed by 2020, includes engineering design and construction to increase flow capacity by 30 percent.
The Pflugerville Central Wastewater Treatment Plant reached 75 percent of its permitted capacity in 2016. Projections presented by Pflugerville City Engineer Amy Giannini show the Central Wastewater Treatment Plant will reach 90 percent capacity by 2020.
In all, the Central Wastewater Treatment Plant will be done in three phases with construction wrapping up in 2028. The city expects to invest approximately $40 million in the first phase of the plant expansion. City documents state that funding for the project is provided through wastewater impact fees and bond funding.
Freese and Nichols’ proposed expansion would have a maximum capacity of 10 million gallons per day (MGD) at the end of its full build out in 2028. The plant has a current maximum capacity of 5.3 MGD.
“This is very specialized work… it’s a complicated project,” Giannini said.
The supplemental agreement with Freese & Nichols was previously put on hold two weeks ago after council members asked to see alternative design plans. At that time, council members shared concerns that the proposed design may not have been large enough in scope to meet the demands of the city at full build out.
Kendall King, group manager for Freese and Nichols’ Treatment, Transmission and Utilities team, presented an alternative measure to address increased capacity in the future: a membrane bioreactor expansion in the future, as needed.
Membrane bioreactor treatment is a combination of filtration with a biological wastewater treatment process, according to King. The membrane bioreactor process is different from the treatment methods currently used at the Central Wastewater Treatment Plant, but that expansion would only be constructed as necessary and is not expected to be needed for many years, officials said.
“It’s a backup—40 to 50 years from now—if we need it,” Giannini said.
King added that technologies may change by that time, leaving the membrane bioreactor unnecessary.
Once design work is completed, the city will open the project to bids for construction. No timeline on those bids has been made immediately available.