City Of Atlanta Utoy Creek Water Reclamation Center

INTRODUCTION

The Utoy Creek Water Reclamation Center (WRC) serves as a cornerstone of the City of Atlanta’s wastewater infrastructure, managing the treatment needs of Southwest Atlanta and surrounding municipalities. As one of three major reclamation facilities operated by the Department of Watershed Management—alongside R.M. Clayton and South River—Utoy Creek plays a pivotal role in the “Clean Water Atlanta” program, an extensive initiative designed to improve water quality and ensure regulatory compliance.

Permitted for 44 million gallons per day (MGD), the facility discharges highly treated effluent into the Chattahoochee River, a critical water resource for the tri-state area of Georgia, Alabama, and Florida. Following the rigorous Consent Decree requirements established in the late 1990s, the facility has seen significant capital investment aimed at modernizing its solids handling, disinfection capabilities, and nutrient removal efficiency. Today, Utoy Creek stands as a model of advanced secondary and tertiary treatment, utilizing modern UV disinfection and biological nutrient removal to protect regional watersheds.

FACILITY OVERVIEW

A. Service Area & Coverage

The Utoy Creek WRC service basin encompasses approximately 38 square miles within the southwestern quadrant of the City of Atlanta and unincorporated Fulton County. It also treats wastewater flows from the City of East Point via inter-jurisdictional agreements. The service area is a dense mix of residential neighborhoods, commercial corridors, and light industrial zones. The collection system feeding the plant is gravity-dominated, though it relies on several key lift stations to convey flow from lower-lying sub-basins. As part of Atlanta’s hydraulic optimization strategy, flows can be partially diverted between basins during emergency conditions or maintenance events.

B. Operational Capacity

The facility is designed for a hydraulic maximum month flow of 44 MGD. While historical average daily flows hover between 24 and 30 MGD, the plant is engineered to handle peak hydraulic loading significantly higher during wet weather events, a critical feature given Atlanta’s history with Inflow and Infiltration (I/I). The plant utilizes roughly 60-70% of its design capacity on average, providing a buffer for future population growth in the flourishing southwest corridor of the metro area.

C. Discharge & Compliance

Treated effluent is discharged via an outfall into Utoy Creek, which flows directly into the Chattahoochee River. Because the Chattahoochee is a primary drinking water source and a recreational asset, the Georgia Environmental Protection Division (EPD) enforces strict NPDES permit limits. The facility must meet stringent standards for Dissolved Oxygen, Total Suspended Solids (TSS), and nutrients—specifically Phosphorus, due to downstream eutrophication concerns. The plant has maintained a strong compliance record in recent years following the completion of Consent Decree-driven upgrades.

TREATMENT PROCESS

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The Utoy Creek WRC employs a multi-stage advanced treatment train designed to remove organics, solids, and pathogens effectively. The process flow moves from preliminary screening to tertiary filtration and UV disinfection.

A. PRELIMINARY TREATMENT

Raw wastewater enters the headworks facility where it undergoes physical screening and grit removal.

• Screening: Mechanically cleaned bar screens remove large debris (rags, plastics, wood) to protect downstream pumps. Screenings are washed, compacted, and sent to landfills.
• Grit Removal: Vortex grit chambers utilize centrifugal force to settle out inorganic solids like sand, gravel, and coffee grounds. This prevents abrasion on mechanical equipment and volume reduction in digesters.
• Odor Control: The headworks are enclosed and ventilated to chemical scrubbers to mitigate odors for neighboring communities.

B. PRIMARY TREATMENT

Flow is directed to primary clarifiers where gravity settling occurs.

• Clarification: Large circular clarifiers reduce flow velocity, allowing settleable solids to drop to the bottom as primary sludge, while grease and oils float to the surface for skimming.
• Efficiency: This stage typically removes 50-60% of Total Suspended Solids (TSS) and 30-40% of Biochemical Oxygen Demand (BOD).

C. SECONDARY TREATMENT

The biological heart of the plant utilizes an Activated Sludge process configured for Biological Nutrient Removal (BNR).

• Aeration Basins: The plant uses fine-bubble diffused aeration to provide oxygen to microorganisms that consume dissolved organic matter. The basins are configured with anoxic zones to facilitate denitrification, reducing total nitrogen levels.
• Secondary Clarifiers: Mixed liquor flows to secondary clarifiers where biological floc settles out. A portion of this sludge is returned to the aeration basins (Return Activated Sludge – RAS) to maintain the biological population, while excess growth is removed (Waste Activated Sludge – WAS).

D. TERTIARY TREATMENT

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To meet the strict limits for the Chattahoochee River discharge, Utoy Creek employs tertiary filtration.

• Filtration: Deep bed sand filters polish the secondary effluent, capturing remaining suspended solids and particulate-bound phosphorus. This step is essential for meeting low TSS permit limits (often < 10 mg/L).
• Chemical Precipitiation: Metal salts (Alum or Ferric) are added upstream of clarification or filtration to precipitate soluble phosphorus, ensuring the plant meets limits often as low as 0.3 mg/L or 0.5 mg/L.

E. DISINFECTION

In a major shift from historical chlorination, the plant now utilizes Ultraviolet (UV) disinfection.

• UV System: The flow passes through channels containing banks of high-intensity UV lamps. The UV light disrupts the DNA of bacteria and viruses, rendering them unable to reproduce.
• Benefits: This method eliminates the need for hazardous chlorine gas storage and removes the need for dechlorination chemicals (sulfur dioxide/bisulfite) prior to discharge, resulting in a safer effluent for aquatic life.

F. SOLIDS HANDLING

Solids processing is a critical component of the Utoy Creek operation.

• Thickening: Primary sludge and WAS are thickened (typically via gravity belt thickeners or rotary drums) to reduce water content before digestion.
• Anaerobic Digestion: Thickened sludge is stabilized in anaerobic digesters. This process reduces volatile solids, destroys pathogens, and produces biogas (methane).
• Dewatering: Digested sludge is dewatered using high-speed centrifuges to produce a “cake” with higher solids content.
• Disposal: The resulting biosolids are hauled off-site for landfill disposal or land application, depending on current regulatory allowances and cake quality.

INFRASTRUCTURE & FACILITIES

A. Physical Plant

The Utoy Creek site spans a significant footprint in a developed area of Southwest Atlanta. The architecture is functional/industrial, with recent additions (such as the UV building) reflecting modern utility design standards. The site includes a dedicated Administration Building housing the SCADA control room and process control laboratories.

B. Energy Systems

The plant is a major energy consumer, with aeration blowers and main influent pumps driving the load. The City of Atlanta has implemented energy efficiency programs, including VFD (Variable Frequency Drive) installations on major pumps and blowers to match energy use with flow demand. Biogas produced in the digesters is flared, though the City has explored cogeneration options in its master planning to offset grid reliance.

C. Odor Control

Given the proximity of residential neighborhoods, Utoy Creek utilizes extensive odor control technologies. Packed tower wet scrubbers and activated carbon adsorption units are deployed at the headworks, primary clarifiers, and solids handling buildings. Negative pressure is maintained in these buildings to prevent fugitive emissions.

RECENT UPGRADES & MAJOR PROJECTS

Disinfection & Safety Improvements (2018-2020)

Project Scope: Transition from chlorine gas/sulfur dioxide disinfection to UV technology.
Project Value: Approx. $15 Million
Technical Highlights: Installation of a TrojanUV Signa or similar large-scale municipal UV system. This project included the demolition of existing chlorine contact chambers and the construction of new UV channels and a canopy structure.
Drivers: Elimination of hazardous chemical storage (inherently safer technology), reduction of disinfection by-products, and improved operational safety.

Biosolids Management Improvements (2019-2022)

Project Scope: Comprehensive rehabilitation of the solids handling train.
Project Value: Part of a larger system-wide $50M+ initiative.
Technical Highlights:

• Replacement of aging centrifuges with modern, high-efficiency dewatering units.
• Rehabilitation of anaerobic digester covers and mixing systems to improve volatile solids reduction.
• Upgrades to sludge conveyance and truck loading facilities.

Drivers: Aging infrastructure causing reliability issues and increased disposal costs due to poor dewatering performance.

Upcoming/Ongoing: Nutrient Removal Optimization

As part of the City’s ongoing Capital Improvement Program (CIP), Utoy Creek is slated for continual optimization of its aeration basins to maximize biological phosphorus uptake, reducing chemical dependency. This includes upgrades to aeration blowers and dissolved oxygen control strategies.

REGULATORY COMPLIANCE & ENVIRONMENTAL PERFORMANCE

A. Permit Requirements

Utoy Creek operates under an NPDES permit issued by the Georgia EPD. Key parameters generally include:

• BOD/TSS: Typically < 10-15 mg/L monthly average.
• Phosphorus: Strict limits (often 0.5 mg/L or lower seasonally) to protect the Chattahoochee.
• Fecal Coliform: < 200 col/100mL (Monthly Geometric Mean).
• Ammonia: Seasonal limits to prevent toxicity to aquatic life.

B. Compliance History

Following the First Amended Consent Decree, the City of Atlanta has made massive strides in compliance. Utoy Creek has moved from a history of wet-weather violations (in the 1990s) to becoming a reliable facility that consistently meets effluent standards. The transition to UV disinfection further secured compliance with pathogen limits without risking residual chlorine violations.

OPERATIONAL EXCELLENCE

A. Staffing

The facility is staffed 24/7 by a team of state-licensed wastewater operators, industrial mechanics, and instrumentation technicians. Operators must hold Georgia State Board of Examiners certifications (Class I, II, or III), with shift supervisors typically holding Class I licenses.

B. Technology

The plant utilizes a centralized SCADA (Supervisory Control and Data Acquisition) system, allowing for real-time monitoring of flows, tank levels, and dissolved oxygen concentrations. Automated control loops adjust chemical dosing and aeration rates based on online instrumentation, optimizing treatment efficiency and reducing chemical waste.

CHALLENGES & FUTURE PLANNING

A. Current Challenges

Inflow and Infiltration (I/I): Like much of Atlanta, the collection system serving Utoy Creek is older. During heavy rain events, stormwater enters sanitary sewers, causing rapid spikes in flow that stress the plant’s hydraulic capacity.

Aging Workforce: The “Silver Tsunami” of retiring senior operators presents a knowledge transfer challenge, driving the Department to invest heavily in apprenticeship and training programs.

B. Future Planning

The Department of Watershed Management’s strategic plan emphasizes “One Water” management. Future projects at Utoy Creek focus on:

• Resiliency: Hardening electrical systems against severe weather.
• Resource Recovery: Potential future implementation of phosphorus recovery or enhanced biogas utilization (Co-Gen) to reduce the facility’s carbon footprint.

TECHNICAL SPECIFICATIONS SUMMARY

FAQ SECTION

Technical/Professional Questions

1. What is the hydraulic capacity of the Utoy Creek WRC?
The plant is permitted for a maximum monthly flow of 44 MGD. Hydraulic peak capacity during wet weather events is significantly higher to accommodate surges from the collection system.

2. Does Utoy Creek utilize chemical addition for phosphorus removal?
Yes. While the plant utilizes biological phosphorus removal (Bio-P) in the anaerobic zones of the aeration basins, metal salts (typically Alum or Ferric Chloride) are used as a polishing step to ensure compliance with strict effluent limits.

3. How are biosolids handled at the facility?
Sludge undergoes anaerobic digestion and is then dewatered using centrifuges. The resulting cake is hauled off-site for disposal in landfills or land application, depending on regulatory approvals and solids quality.

4. Has the facility transitioned away from Chlorine gas?
Yes. The facility completed a major capital project to replace chlorine gas disinfection with Ultraviolet (UV) light disinfection, improving safety and eliminating the need for dechlorination.

Public Interest Questions

5. How many people does the Utoy Creek plant serve?
The facility serves a population of approximately 250,000 to 300,000 residents in Southwest Atlanta, Fulton County, and East Point.

6. Does the plant smell?
Wastewater treatment inherently generates odors, but Utoy Creek utilizes advanced odor control scrubbers and carbon filters at key process areas (headworks and solids handling) to minimize impact on the surrounding community.

7. Is the treated water safe for the river?
Yes. The effluent discharged into the Chattahoochee River often meets or exceeds the quality of the river water itself regarding suspended solids and clarity. It is disinfected to kill bacteria and viruses before release.