Plum Creek Water Reclamation Authority

Plum Creek Water Reclamation Authority (PCWRA) operates a Biological Nutrient Removal (BNR) wastewater treatment process with a permitted capacity of 6.44 million gallons per day (MGD) that serves the Town of Castle Rock, Castle Pines Metropolitan District, and Castle Pines North Metropolitan District. The facility is an activated sludge process designed to remove nutrients (nitrogen and phosphorous compounds) biologically. This is achieved by controlling the quantity of microorganisms in the process and altering their environmental conditions to obtain different results. By controlling these conditions effectively, Operations staff can exceed treatment goals by optimizing processes within the facility. The current treatment process consists of influent screening to remove inorganic material followed by complete mix oxidation basins with upstream anerobic selectors, secondary clarifiers, up-flow tertiary sand filtration, and disinfection with ultraviolet light.

PCWRA also operates a full-service wastewater laboratory that performs over 98 percent of all facility analysis in-house and is a Colorado certified laboratory for testing of Coliforms in drinking water. The primary role of the laboratory is to analyze samples collected from various unit processes. This data provides vital information to Operations staff for optimizing treatment performance. The laboratory data also defines whether regulatory conditions are being met and verifies that discharged water is safe for the aquatic environment and downstream uses.

Reuse: As the demand for water grows, Plum Creek Water Reclamation Authority understands the importance of recycling water. At PCWRA the water is treated to meet the high-quality standards put in place by the Colorado Department of Health and the federal EPA. After treatment using naturally occurring bacteria, the water is filtered and then disinfected with ultraviolet light. The water is then delivered to four local golf courses where it is used for irrigation and course maintenance. This process allows the community to use a renewable resource for irrigation while conserving precious non-renewable groundwater sources.

Biosolids Program: Plum Creek Water Reclamation Authority uses naturally occurring bacteria for the treatment of wastewater and as these microorganisms accumulate, they must be removed from the system. The resulting microorganisms and organic matter are then concentrated through a thickening process and treated using a specialized digestion process to reduce the volume of organic matter and pathogenic organisms. After the digestion process, the liquid is dewatered using centrifuges to increase the solids content of the final product to 22-26%. Once dewatered, the final product creates a nutrient-rich organic material that is transported to permitted sites in Colorado to be beneficially reused as a fertilizer and soil amendment in crop and rangeland. This process has been used for decades in the United States.

PCWRA completed a large facility expansion in 2021 to increase treatment capacity by an additional 3 MGD. Project upgrades included: increased aeration capabilities for additional nutrient removal and optimization, new headworks building with improved screening and flow equalization throughout the treatment trains, Autothermal Thermophilic Aerobic Digestion (ATAD) process with the ability to produce class A biosolids in the future, increased UV disinfection capacity and redundancy, and tertiary sand filters for phosphorous and suspended solids removal in the final effluent. Once final permitting is received from the Colorado Department of Health and Environment, total treatment capacity will be increased to 9.44 MGD to accommodate the anticipated growth in the PCWRA service area.