Mexia Wastewater Treatment Plant

In 2003, new permitted effluent limits required that the existing 0.85 MGD package-type wastewater treatment plant for the City of Mexia be abandoned. The City hired KSA Engineers, Inc. to upgrade the plant.

KSA completed all civil engineering for the project, including: Preliminary Engineering Report, permitting, environmental assessment, hydraulic profiles, treatment unit sizing, equipment selection/specification, bidding/construction oversight and O&M Manual.

The project involved construction of a new 2 MGD average annual flow wastewater treatment plant with 8 MGD peak 2-hour flow using the extended aeration mode including:

  • Mechanical climber-type screen and manual bar screens
  • Grit chambers (vortex type)
  • Lift station with 4 submersible pumps with VFD’s
  • Influent splitter box
  • Aeration basins, 2 each with floating aerators
  • Two clarifiers with algae sweeps, full radius scum arm, and sludge level meter
  • UV disinfection with automatic flow pace and self-cleaning wipers (2 channels, 4 banks)
  • Effluent meter with cascade aeration for increased dissolved oxygen
  • Sludge pump station with 3 submersible pumps with VFD’s
  • Aerobic digester/sludge holding tank with floating aerator
  • Digested sludge pump station (grinder and 2 progressive cavity pumps)
  • Centrifuge (for sludge dewatering)
  • Administration and lab building
  • Electrical and generator
  • Plant on-site reuse system (pressure tank, pumps, chlorine)
  • Site piping, grading, roads, fencing

The project also involved abandonment of the old treatment plant, and it was funded by the Texas Water Development Board - Clean Water SRF program.