City Of Greeley

Wastewater Treatment

The Water Pollution Control Facility staff are dedicated environmental professionals providing quality, safe, cost effective wastewater treatment services for the citizens of Greeley. The staff treats wastewater to meet or exceed EPA and Colorado Department of Public Health & Environment requirements. What does this mean? The WPCF goal is to maintain or improve the water quality of the Cache la Poudre River. The staff also treats organics (biodegradable material) that enters the plant and converts them to biosolids that are used to improve soil composition and increase crop production for local farmers.

The WPCF has been recognized for its efficiency, innovations and record of meeting permit limits.

  • In 1990 and 1998, the WPCF won an Environmental Protection agency Region VIII Operations & Maintenance Award.
  • In 2000, the WPCF was 1 of 15 treatment plants across the country that received a "Platinum Award" from the Association of Metropolitan Sewerage Agencies. This award recognizes a perfect environmental compliance record achieved for the last five years.
  • The WPCF received the national first-place award for its outstanding Industrial Pretreatment Program from the EPA in 2000.
  • The WPCF received the 2011 Xcel Energy Custom Efficiency Achievement Award for reducing energy costs.

Jump to the following sections on this page:
    Wastewater Processes and Specifications
    WPCF Biosolids Program
    Industrial Pretreatment Program
    Public Education and Outreach Program
    Plant Operations & Maintenance
    WPCF Laboratory
    WPCF Administration
    Contact Wastewater Treatment

Reference Documents:
    2012 Biosolids Masterplan 

Wastewater Processes and Specifications

A primary service for Greeley citizens is to have excellent facility performance that meets or exceeds EPA, State and local requirements.

The WPCF is an advanced secondary wastewater treatment facility with vertical turbine high solids influent pumps; rotary bar screens; 30 inch Parshall flumes with flush-mounted open channel influent flow sensors; primary clarification; activated sludge system with fine bubble diffused aeration and gas cleaning system;  nitrification & de-nitrification capabilities; Trojan 300 Plus UV disinfection system; high-speed 300 HP turbo blowers; secondary clarification; ultrasonic effluent flow meters; anaerobic digesters with floating covers; spiral plate heat exchangers; iron sponge with regeneration, low pressure steam, gas fired boiler units; thickening and dewatering centrifuges; plant chemical counteract odor control system. In 2012, a 500 Kw photovoltaic solar array was installed adjacent to the WPCF. The solar system is projected to save the treatment plant approximately $800,000-$1,400,000 in electrical costs over the next 20 years.

Facility Specifications/Statistics
Data results from the year 2012

  • Plant Design Capacity: 14.7 Mgd
  • Annual Average Flow Capacity: 16.0 Mgd
  • Annual Average Flow: 7.41 Mgd
  • Peak Monthly Flow Average: 7.74 Mgd (September)
  • Average Daily Flow per Capita Day: 78 gallons (based on 2012 estimated population)
  • Cost to Treat 1000 Gallons of Wastewater: $1.02 ($0.79 thru June 2012) 
  • Percent Hydraulic Capacity Utilized: 50%
  • Percent Organic Capacity Utilized: 45% (54% thru June 2012)
  • Percent Removal of Biodegradable Organics: 99%
  • Percent Removal of Total Suspended Solids: 98%
  • Percent Removal of Ammonia-Nitrogen: 83%
  • Total Annual WPCF Budget: $2,841,090.00
  • Population Served: 92,889 (2010 census), 95,581 (2012 estimated) 
  • Average Effluent Total Suspended Solids: 7.2 Mg/L
  • Average Effluent Carbonaceous BOD: 2.8 Mg/L
  • Average Effluent Ammonia-Nitrogen: 5.4 Mg/L
  • Plant Discharge Point: Cache La Poudre River
  • Biosolids Land Applied on Area Farmland: 1,407 Dry Tons

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WPCF Biosolids Program

Environmental compliance is very important, quality management practices are in place to meet all EPA and State and local requirements. The City of Greeley WPCF is committed to do the best job possible.

Biosolids contain the same basic ingredients that compose fertilizer. Biosolids are organic materials that when added to the soil helps to retain moisture and as a fertilizer it produces a higher crop yield. Settable sludge collected from the bottom of each primary clarifier is pumped to large holding tanks called digesters to make biosoilds. Scum and other floating material that accumulates on the top of the primary clarifiers are also sent to the anaerobic digesters for treatment.

Activated sludge is composed of millions of microorganisms that utilize wastewater as their food source. The mass of the microorganisms continues to grow and excess microorganisms are sent to a thickening centrifuge to remove most of the water content. The thickened microorganisms from a centrifuge is called "cake". Cake processed by the thickening centrifuges is approximately 6 percent total solids. The cake is then pumped into the primary digesters.

So at this point, we have waste activated sludge, primary scum and primary settable solids being sent to the primary digesters. Primary digesters contain anaerobic bacteria that use the waste activated sludge, scum and primary clarifier settable solids as a food source. The microorganisms are very temperature sensitive; they perform best when at 98 degrees Fahrenheit. The microorganisms consume about 60 percent of the sludge; this process is called volatile solids reduction. The microorganisms also produce gas, about 70 percent methane gas and 30 percent carbon dioxide gas. The methane gas is used to heat the digesters to 98 degrees F. Excess gas is used to produce heat for buildings. The sludge is kept in the digester about 20-30 days to complete the digestion process. Biosolids is the name for this material once this process is complete.

The primary digester solids are sent to holding tanks until processed by a dewatering centrifuge. Biosolids at 2 percent total solids enter the dewatering centrifuge, where the dewatering centrifuge spins at nearly 6000 rpm to remove excess water from the solids. The cake leaving the centrifuge is approximately 20 percent total solids, or the consistency of potting soil. The thickened cake is stored in a large hopper until a truck arrives.

Biosolids are applied to local area farms. The hauling and land application process has been privatized since 1988. Liquid Waste Management Inc. of Longmont, Colorado applies the biosolids to dry-land wheat farms. They perform soil tests and monitor application rates to comply with all EPA and CDPHE regulations. The WPCF monitors sites and all testing to ensure the regulatory compliance is always met.

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Public Education and Outreach Program

Facility tours are welcomed and the staff can provide classroom training for groups and individuals.

A facility tour can be arranged by calling the administrative assistant at (970) 350-9360. Tours can last from 1 hour for a short tour, and up to 2 hours for a more comprehensive tour. Also, the staff can help setup a wastewater related training session.

  • Promotes pollution prevention/elementary education program.
  • Classroom presentations on water quality topics.
  • Provides information on household hazardous waste program.
  • Provides information on modern wastewater treatment practices.

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Plant Operations & Maintenance

The operations and maintenance personnel ensure that the equipment is always maintained and operated in a manner to consistently achieve the best results in the treatment of wastewater. Not only is wastewater treated, biosolids are also processed, power generation equipment and a methane gas collection system are maintained and operated by best management practices. Safety is an important aspect for all personnel due to the nature of wastewater and heavy equipment routinely encountered on the job. Safety training is a continuous objective to ensure public and personal safety at all times. The facility operates 24 hours per day and 7 days per week

Operators make sure that the plant is meeting all National Pollution Discharge Elimination System (NPDES) requirements. All of the facility's eight operators have received the highest State of Colorado wastewater treatment certification (Class "A"). The operators perform the following tasks, including: process control changes, operating centrifuges, laboratory analysis, site security, coordination of biosolids hauling, chemical addition, training and plant tours.

The maintenance staff keeps the plant equipment and infrastructure in excellent condition. Their work includes the repair and maintenance of almost everything at the plant site. This includes the maintenance of pumps, motors, valves, mixers, electrical equipment, electronic PLC's, power generation equipment and centrifuges. The staff is also responsible for painting, yard maintenance and training.

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WPCF Laboratory

The laboratory performs analysis in accordance with the facility's National Pollution Discharge Elimination System permit requirements. The laboratory collects samples and performs microbiological, chemical and physical analysis of wastewater and biosolids in order to determine the efficiency of plant processes and to monitor for the NPDES permit requirements.

Other duties include:

  • Collect and preserve samples for independent laboratory analysis.
  • Maintain complete and accurate laboratory bench-sheets and records.
  • Perform quality control work in the laboratory at all times.
  • Maintain and calibrate laboratory equipment on a daily basis.
  • Performs standard EPA laboratory test procedures and samples.
  • Prepare bacteriological media, chemical reagents and stock solutions.

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WPCF Administration

The function of the Administration section is to provide administrative support for all WPCF sections. This includes data and records management, financial and administrative management, career development, training programs, process analysis, SCADA system, and regulatory interaction to assure compliance with all local state and federal regulations.

Function Summary

  • Assures compliance with all State of Colorado and U.S. Environmental Protection Agency issued permits and regulations by maintaining appropriate documentation and records.
  • Directs and manages all wastewater treatment projects.
  • Coordinates on-going staff training programs.
  • Maintains in-house computer programs.
  • Prepares reports and correspondence for regulatory agencies and various management and departmental purposes.
  • Maintains operating capital improvement budgets for the division.
  • Provides administrative and personnel assistance to employees.

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Contact WPCF

Please use the following information to contact us with any wastewater treatment questions.

300 East 8th Street
Greeley, CO 80631
(970) 350-9360
fax: (970) 350-9366

Operation hours: Monday - Friday, 7:30 a.m. to 4:00 p.m.

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