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Boyd Lake WTP Disinfection Evaluation

Project Details

Client
City of Greeley Water & Sewer Department

Location
Greeley, CO

Services Provided
Water Treatment

Strategy & Planning

Project Highlights

  • 40 MGD WTP
  • 1190 LF of FRP Baffle Walls Installed
  • Baffling Factor of 0.7 Achieved

This project involved the evaluation and design of disinfection improvements at the 40 MGD Boyd Lake WTP to comply with the surface water treatment removal requirements to ensure the water treated meets regulatory disinfection requirements.

The design included new baffles in the WTP clearwell, new VFDs for the high service pump station, a new backwash pump, and other miscellaneous piping improvements.

Providence Infrastructure Consultants (PIC) was retained by the City to evaluate the Boyd Lake WTP disinfection practices and develop the strategy for meeting and proving compliance with the EPA and CDPHE disinfection rules. This study performed an evaluation of the WTP to meet the Log Inactivation requirements for Giardia and viruses to verify compliance with Federal and Colorado Department of Public Health and Environment (CDPHE) Surface Water Treatment Rules (SWTRs). The evaluation showed that the Boyd WTP disinfection practices could meet log inactivation requirements within the WTP by adding baffles to the clearwell to achieve a baffling factor of 0.7. In addition, the project evaluated and designed changes to the sampling points for chlorine residual to optimize and confirm the disinfection credit calculations.

The project also included improvements to the filter backwash water supply system, improvements to the high service pump station and the addition of a finished water return line to aid in the start-up of the WTP. Specifically, work on the WTP included furnishing and installing a new backwash supply pump, adding approximately 1,190 LF of FRP baffle walls to the clearwell, adding VFDs for the high service pumps, improvements to a valve vault, adding piping and valves for a treated water return line for use during the annual plant start-up, as well as integrating all the improvements into the WTP SCADA system.