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Wastewater Treatment - General Information

Wastewater Treatment - General Information

2013 Updates

Project construction was completed in May, 2013 for:

  • an ultraviolet (UV) disinfection system that will replace the chlorine / sulfur dioxide disinfection system;
  • digester modifications; and
  • headworks modifications.

The Nutrient Compliance Study finalized early in 2013 looks ahead to determine how the City of Boulder may comply with more stringent future wastewater discharge regulations, including:

  • daily maximum nitrate and ammonia limits (effective December 2017);
  • Colorado Regulation 85: Technology-based nutrient limits (effective approximately 2022); and
  • Colorado Regulation 31: Water quality-based nutrient limits (effective approximately 2030).

The one-megawatt solar electric system at the Wastewater Treatment Facility has generated more than three million kilowatt-hours of energy, saving city ratepayers more than $75,000.

General Information

The 75th Street Wastewater Treatment Facility is designed to treat more than 25 million gallons per day of wastewater from the City of Boulder, including the Gunbarrel area.

  • Currently, it treats approximately 12.5 million gallons per day and discharges a high-quality effluent to Boulder Creek.
  • Wastewater is treated using several different treatment processes, including:
    • physical;
    • microbiological;
    • chemical; and
    • biosolids.
  • Treated wastewater (effluent) is discharged to Boulder Creek just east of 75th Street.
  • Many samples are collected from the effluent discharge to ensure that the discharge is meeting or exceeding the permit that has been issued by the State of Colorado.
  • The City of Boulder is regulated under permit number CO-0024147 issued by the Colorado Department of Public Health and Environment (CDPHE).

Industrial Pretreatment

The Industrial Pretreatment Program is also located at the city's wastewater treatment facility.


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