City Of Aurora Prairie Waters Project Water Reclamation Facility

The Peter D. Binney Water Purification Facility serves as the cornerstone of the City of Aurora’s landmark Prairie Waters Project. As one of the most advanced potable water reuse facilities in the United States, this plant transforms South Platte River water—captured downstream of the Denver metro area—into pristine drinking water. With a design capacity of 50 million gallons per day (MGD) and a state-of-the-art multi-barrier treatment train involving UV oxidation and activated carbon, the facility represents a model for drought resilience and sustainable water resource management in the arid West.

FACILITY BASIC INFORMATION

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1. INTRODUCTION

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The Peter D. Binney Water Purification Facility is a critical component of Colorado’s water infrastructure, designed to close the loop on the region’s water cycle. Faced with severe drought in the early 2000s and limited access to new mountain water sources, Aurora Water launched the Prairie Waters Project to recapture return flows from the South Platte River. The facility is physically located near the Aurora Reservoir but draws water from a North Campus intake 34 miles away near Brighton, Colorado.

This facility is technically classified as an advanced water purification plant supporting an Indirect Potable Reuse (IPR) scheme, though it utilizes valid water rights exchanges. It employs a rigorous “multi-barrier” approach to remove contaminants, including pharmaceuticals and personal care products (PPCPs), ensuring water quality that exceeds all state and federal Safe Drinking Water Act standards. Since its commissioning in 2010, the plant has increased Aurora’s water supply reliability by 20%, securing resources for a growing population in a semi-arid climate.

2. FACILITY OVERVIEW

A. Service Area & Strategic Importance

The facility serves the City of Aurora, the third-largest city in Colorado. Unlike many municipalities that rely solely on snowmelt, Aurora’s service area is geographically distinct from its primary water sources. The Prairie Waters Project acts as a drought insurance policy; during dry years, the facility can operate at higher capacities to offset reduced mountain snowpack. The system supports a diverse demographic mix, including residential neighborhoods, the Buckley Space Force Base, and a growing commercial sector.

B. Operational Capacity and Conveyance

The Prairie Waters Project is not just a treatment plant; it is a massive conveyance system. Water is captured at the North Campus near Brighton, where it undergoes Riverbank Filtration (RBF). It is then pumped through a 34-mile, 60-inch diameter pipeline, ascending roughly 1,000 feet in elevation to reach the Binney Facility. The plant was designed with a modular expansion philosophy. While initial operations began at 10 MGD, the civil and hydraulic infrastructure was constructed to accommodate an ultimate build-out of 50 MGD.

C. Discharge & Distribution

Unlike a wastewater plant that discharges to a river, the Binney Facility discharges its treated product directly into the Aurora distribution system or the Aurora Reservoir for storage. This requires adherence to drinking water permits rather than NPDES discharge permits. The facility operates under strict oversight from the Colorado Department of Public Health and Environment (CDPHE), meeting Maximum Contaminant Levels (MCLs) for potable water.

3. TREATMENT PROCESS

The Peter D. Binney Water Purification Facility utilizes a sophisticated multi-barrier treatment train designed specifically to address the water quality challenges of the South Platte River, which includes treated effluent from upstream wastewater plants, agricultural runoff, and naturally occurring hardness.

A. BARRIER 1: Riverbank Filtration (RBF) & Aquifer Recharge

Location: North Campus (Brighton, CO)
Before water enters the pipeline to the main facility, it undergoes natural pretreatment. Wells located adjacent to the South Platte River draw water through the alluvial aquifer. The riverbed and soil act as a natural filter, removing particulate matter, turbidity, and some organic compounds. This process, known as Riverbank Filtration (RBF), provides a consistent water quality and dampens shock loads from the river.

B. BARRIER 2: High-Rate Chemical Softening

Upon arrival at the Binney Facility, the water is characterized by high hardness and alkalinity. The plant utilizes high-rate ballasted flocculation (e.g., Actiflo® type technology) combined with chemical precipitation to soften the water.

• Chemicals Used: Lime and ferric chloride are typically added to raise pH and precipitate calcium and magnesium.
• Ballasted Flocculation: Microsand is injected to act as a seed for floc formation, significantly reducing the settling time required compared to conventional sedimentation.
• Objective: Reduction of hardness, alkalinity, heavy metals, and suspended solids.

C. BARRIER 3: Filtration

Following softening, the water passes through deep-bed gravity filters. These filters reduce turbidity to very low levels (typically <0.1 NTU), preparing the water for the advanced oxidation process. The filtration stage protects downstream UV reactors from fouling and interference.

D. BARRIER 4: UV / Advanced Oxidation Process (UV-AOP)

This is the technological heart of the facility regarding micropollutant destruction.

• Technology: High-intensity Ultraviolet (UV) light combined with Hydrogen Peroxide (H2O2).
• Mechanism: The UV light disinfects pathogens (Giardia, Cryptosporidium). The addition of hydrogen peroxide creates hydroxyl radicals—extremely potent oxidizers—that break down complex organic molecules, including pharmaceuticals, endocrine disruptors, and pesticides.
• Capacity: The UV reactors are sized to handle peak flows while maintaining strict UV transmittance (UVT) requirements.

E. BARRIER 5: Granular Activated Carbon (GAC) Adsorption

Following oxidation, the water flows through GAC contactors.

• Function: The activated carbon acts as a “polishing” step. It adsorbs any remaining organic carbon, taste and odor compounds (Geosmin/MIB), and quenches residual hydrogen peroxide from the AOP step.
• Bio-Filtration: Over time, the GAC operates biologically (BAC), where beneficial bacteria consume organic matter on the carbon surface, extending the life of the media and further reducing Total Organic Carbon (TOC).

F. DISINFECTION & DISTRIBUTION

The final step involves chlorination (typically conversion to chloramines) to maintain a residual disinfectant in the distribution system. The water is stabilized to prevent corrosion in the municipal piping network before being blended with Aurora’s other water sources.

G. SOLIDS HANDLING

Chemical sludge from the softening process is thickened and dewatered using centrifuges. The resulting cake is disposed of in accordance with environmental regulations, often at sanitary landfills or through beneficial reuse programs where applicable.

4. INFRASTRUCTURE & FACILITIES

A. The Conveyance System

The Prairie Waters Project includes three major pump stations required to lift water from the South Platte valley to the treatment facility. These stations utilize high-horsepower vertical turbine pumps. The 34-mile pipeline required tunneling under Interstate 76 and the E-470 tollway, representing a significant engineering feat in hydraulic conveyance.

B. Energy Recovery

Given the energy intensity of pumping water 34 miles and 1,000 feet uphill, energy efficiency is paramount. The system utilizes Variable Frequency Drives (VFDs) on major pumps to optimize energy usage based on flow demand. While the pumping is energy-intensive, the treatment process itself is optimized to minimize chemical usage through real-time water quality monitoring.

C. Site Layout

The Binney Facility is located on a campus that allows for modular expansion. The architectural design of the facility reflects the prairie landscape, utilizing local materials and low-profile structures to minimize visual impact. The site includes a dedicated operations building with a state-of-the-art SCADA control room and a water quality laboratory.

5. RECENT UPGRADES & MAJOR PROJECTS

Current & Future Planning

Capacity Expansion: While the civil infrastructure supports 50 MGD, the process mechanical equipment was installed for lower initial flows. Aurora Water plans capital expenditures to install additional pumping capacity and treatment trains (additional UV reactors and GAC contactors) as demand dictates. The “North Campus Expansion” is a key element of the long-term plan to fully utilize the 50 MGD water rights.

PFAS Mitigation Strategies: Like all advanced water treatment facilities, the Binney Facility is monitoring the regulatory landscape regarding PFAS (Per- and polyfluoroalkyl substances). The existing GAC contactors provide a significant barrier against these compounds, placing the facility in a strong position relative to upcoming EPA regulations, though media change-out frequencies may be adjusted for compliance.

6. REGULATORY COMPLIANCE & ENVIRONMENTAL PERFORMANCE

A. Drinking Water Compliance

The facility operates under the oversight of the Colorado Department of Public Health and Environment (CDPHE). Because the source water is technically surface water (South Platte River), the facility must comply with the Surface Water Treatment Rule and Long Term 2 Enhanced Surface Water Treatment Rule (LT2). The multi-barrier approach achieves high log-removal credits for Cryptosporidium and Giardia.

B. Emerging Contaminants of Concern (CECs)

A primary driver for the UV-AOP and GAC selection was the removal of CECs. Routine monitoring demonstrates that the facility effectively removes trace pharmaceuticals, endocrine disruptors, and industrial chemicals to non-detectable levels, often exceeding the quality of traditional mountain runoff sources.

7. OPERATIONAL EXCELLENCE

A. Staffing and Certification

The complexity of the Binney Facility requires operators with the highest level of certification (Colorado Class A Water Treatment licensure). The staff includes process engineers, SCADA specialists, and maintenance technicians skilled in both hydraulic systems and advanced chemical processes.

B. SCADA and Automation

The plant utilizes a robust Supervisory Control and Data Acquisition (SCADA) system that integrates data from the North Campus intake (34 miles away) and the main treatment plant. Automated control loops manage chemical dosing based on real-time TOC and UVT analyzers, ensuring the Advanced Oxidation Process remains within the optimal destruction window.

8. CHALLENGES & FUTURE PLANNING

A. Source Water Variability

The South Platte River is a dynamic water source. Water quality can change rapidly due to storm events, agricultural runoff cycles, or operational changes at upstream wastewater plants. The Binney Facility’s operators must constantly adjust chemical dosages (softening and oxidation) to handle fluctuations in hardness, alkalinity, and organic loading.

B. Brine and Residuals Management

The softening process produces significant quantities of calcium carbonate sludge. Managing the disposal and beneficial reuse of these solids is an ongoing operational logistic and cost center.

C. Public Acceptance

Historically, “toilet-to-tap” stigma plagues reuse projects. However, Aurora Water’s extensive public outreach and the branding of “Prairie Waters” (emphasizing the natural filtration and multiple barriers) successfully gained public trust. Maintaining this trust requires transparency and consistent water quality excellence.

9. TECHNICAL SPECIFICATIONS SUMMARY

10. FAQ SECTION

Technical Questions

1. Is the Binney Facility considered Direct Potable Reuse (DPR)?
No. It is effectively Indirect Potable Reuse (IPR). The water is drawn from the river (environmental buffer), treated, and then often blended in the Aurora Reservoir or distribution system. However, the connection is closed-loop infrastructure rather than discharging to a reservoir and withdrawing later.

2. How does the facility handle Total Dissolved Solids (TDS)?
The chemical softening process removes hardness (calcium/magnesium), which reduces some TDS. However, the facility does not currently use Reverse Osmosis (RO), so monovalent ions (like sodium and chloride) are not removed. Source control and blending are used to manage salinity.

3. What is the UV Transmittance (UVT) target for the AOP system?
To ensure efficient hydroxyl radical generation, the water entering the UV reactors typically requires a UVT of >95%. The upstream softening and filtration processes are critical to achieving this clarity.

Public Interest Questions

4. Is the water safe to drink?
Yes. The water produced by the Binney Facility is often cleaner than traditional mountain sources regarding emerging contaminants. It meets or exceeds all state and federal drinking water standards.

5. Why did Aurora build this instead of finding more mountain water?
Available water rights in the mountains are scarce, expensive, and legally difficult to obtain. The Prairie Waters Project allows Aurora to use its existing water rights more efficiently by recapturing water it has already used once.

6. Does the water taste different?
The Granular Activated Carbon (GAC) filters are specifically designed to remove taste and odor compounds. Most consumers cannot distinguish between Prairie Waters flow and mountain snowmelt.