FACILITY BASIC INFORMATION
- Plant Name: Spring Creek Water Reclamation Plant
- Location: 3017 North 8th Street, Springfield, Sangamon County, Illinois
- Operating Authority: Sangamon County Water Reclamation District (SCWRD)
- Design Average Flow: 32.0 MGD
- Design Peak Flow: 80.0 MGD (Full Treatment) / 165 MGD (Wet Weather)
- Population Served: ~115,000 residents
- Service Area: City of Springfield, Village of Grandview, Leland Grove, Jerome, and unincorporated Sangamon County
- Receiving Water Body: Sangamon River (via Spring Creek)
- NPDES Permit Number: IL0021989
- Year Commissioned: 2012 (Current Consolidated Facility)
1. INTRODUCTION
The Spring Creek Water Reclamation Plant (WRP) represents the cornerstone of wastewater infrastructure for the capital city of Illinois. Operated by the Sangamon County Water Reclamation District (SCWRD), this advanced treatment facility manages wastewater for over 115,000 residents across the Greater Springfield metropolitan area. The current facility, commissioned in 2012 following a massive consolidation initiative, replaced aging infrastructure with state-of-the-art biological treatment capabilities.
With a design average flow of 32 million gallons per day (MGD) and a wet-weather peak capacity exceeding 160 MGD, the Spring Creek WRP is a critical asset in managing the region’s combined sewer system challenges. The plant utilizes advanced Vertical Loop Reactor (VLR) technology, setting a benchmark for nutrient removal efficiency and energy management in the Midwest. As the largest point-source discharge control in the Sangamon River watershed, the facility plays a pivotal role in maintaining the ecological health of downstream waterways.
2. FACILITY OVERVIEW
A. Service Area & Coverage
The facility serves a comprehensive 75-square-mile area encompassing the City of Springfield and surrounding municipalities including Grandview, Jerome, Leland Grove, and Southern View. The collection system is a hybrid network comprised of approximately 250 miles of sanitary sewers and substantial combined sewer areas in the historic city center. The district maintains 26 pumping stations that convey flow to the Spring Creek headworks.
B. Operational Capacity
The Spring Creek WRP operates with a Design Average Flow (DAF) of 32.0 MGD. Historically, the plant experiences significant diurnal and seasonal fluctuations due to the combined collection system.
- Average Daily Flow: ~18-22 MGD
- Peak Hydraulic Capacity: 80 MGD (Secondary Treatment)
- Excess Flow Treatment: Up to 165 MGD (Primary + Disinfection for CSO events)
The facility was designed with modular expansion capabilities to accommodate regional growth projected through 2040.
C. Discharge & Compliance
Treated effluent is discharged into the Sangamon River via Spring Creek under NPDES Permit No. IL0021989. The receiving stream is a critical waterway in Central Illinois, requiring stringent adherence to Ammonia-Nitrogen and dissolved oxygen standards. The SCWRD has maintained an exemplary compliance record, consistently achieving removal rates exceeding 98% for BOD and TSS.
3. TREATMENT PROCESS
The Spring Creek WRP utilizes an advanced activated sludge process configured for biological nutrient removal. The treatment train is designed to handle high-strength municipal waste while managing the hydraulic surges common to combined sewer systems.
A. PRELIMINARY TREATMENT
Raw influent enters the massive headworks building where it undergoes aggressive screening and grit removal to protect downstream mechanical equipment.
- Screening: Four mechanically cleaned bar screens (6mm spacing) remove rags and large debris.
- Grit Removal: Vortex grit chambers utilize centrifugal force to separate inorganic solids (sand, gravel) from the organic waste stream.
- Odor Control: The headworks facility is fully enclosed and ventilated through biological scrubbers to mitigate neighborhood nuisance odors.
B. PRIMARY TREATMENT / EXCESS FLOW
Unlike conventional plants that send all flow to primary clarifiers, Spring Creek utilizes a split-flow strategy during wet weather.
- Primary Clarifiers: Four circular primary clarifiers provide sedimentation for heavy solids.
- CSO Management: Flows exceeding the biological capacity (above 80 MGD) are diverted to dedicated excess flow clarifiers where they receive primary treatment and disinfection before blending with the final effluent, preventing raw sewage overflows.
C. SECONDARY TREATMENT (Vertical Loop Reactors)
The heart of the Spring Creek WRP is the biological treatment stage, utilizing Vertical Loop Reactors (VLR).
- Configuration: The plant operates multiple VLR trains. These are essentially deep oxidation ditches flipped on their side, utilizing surface aerators to drive oxygen and mixing deep into the tanks.
- Process: The VLRs operate in an extended aeration mode with anoxic zones to facilitate simultaneous nitrification and denitrification. This configuration offers superior energy efficiency compared to traditional diffused air basins.
- Secondary Clarification: Mixed liquor flows to four 140-foot diameter secondary clarifiers where biological floc settles. Rapid sludge removal mechanisms return activated sludge (RAS) to the VLRs to maintain biomass.
D. DISINFECTION
Moving away from hazardous gas chlorination, the facility employs high-intensity Ultraviolet (UV) Disinfection.
- System: Two open-channel UV banks containing thousands of lamps.
- Mechanism: UV light disrupts the DNA of pathogens (bacteria/viruses), rendering them unable to reproduce.
- Benefit: This eliminates the formation of chlorinated disinfection byproducts and removes the need for dechlorination chemicals (sulfur dioxide).
E. POST-AERATION
Before entering the river, the effluent cascades down a step-aeration structure. This physical turbulence increases the Dissolved Oxygen (DO) concentration to meet the >6.0 mg/L requirement for aquatic life protection in the Sangamon River.
F. SOLIDS HANDLING
Sludge captured from primary and secondary processes is stabilized and dewatered.
- Thickening: Gravity belt thickeners concentrate waste activated sludge.
- Stabilization: Aerobic digestion stabilizes the sludge, reducing volatile solids and pathogen content.
- Dewatering: High-solids centrifuges or belt filter presses dewater the biosolids to a cake consistency.
- Disposal: The Class B biosolids are land-applied on local agricultural fields as a nutrient-rich fertilizer, completing the resource recovery cycle.
4. INFRASTRUCTURE & FACILITIES
A. Physical Plant
The site occupies a significant footprint along the Sangamon River levee system. The architectural design of the control buildings emphasizes durability and flood resilience. The Administration Building houses a fully accredited environmental laboratory capable of performing all NPDES-required analyses (BOD, TSS, Ammonia, Fecal Coliform) on-site.
B. Energy Efficiency
Energy management was a primary driver in the 2012 plant design. The VLR aeration system utilizes variable frequency drives (VFDs) linked to dissolved oxygen sensors, allowing the plant to modulate aeration intensity based on real-time biological demand. This automation reduces energy consumption by approximately 20-30% compared to constant-speed systems.
5. RECENT UPGRADES & MAJOR PROJECTS
Spring Creek Plant Consolidation (2009-2012)
Cost: ~$110 Million
Scope: This historical project represented the largest infrastructure investment in the District’s history. It involved the decommissioning of the aging North Plant and the original Spring Creek facility to create a single, centralized regional treatment hub.
- Key Drivers: Aging infrastructure (50+ years old), new ammonia limits, and the need for CSO reduction.
- Technology: Installation of Vertical Loop Reactors, UV disinfection, and new headworks.
- Funding: Financed largely through the Illinois EPA State Revolving Fund (SRF) low-interest loan program.
- Outcome: Consolidated operations reduced O&M costs, improved effluent quality significantly, and eliminated wet-weather bypasses.
Phosphorus Removal Optimization (Current/Ongoing)
Status: Planning/Implementation Phase
Drivers: Illinois EPA’s statewide nutrient loss reduction strategy targeting phosphorus discharge limits of 0.5 mg/L or lower.
- Scope: Implementation of Biological Phosphorus Removal (Bio-P) zones within the existing VLR trains and potential chemical polishing facilities (ferric chloride or alum addition).
- Goal: To meet upcoming NPDES permit limits for Total Phosphorus without requiring massive new concrete tankage.
6. REGULATORY COMPLIANCE & ENVIRONMENTAL PERFORMANCE
A. Permit Requirements
The facility operates under a strict NPDES permit. Key parameters typically include:
- CBOD5: Monthly average limit of 10 mg/L.
- Suspended Solids: Monthly average limit of 12 mg/L.
- Ammonia Nitrogen: Seasonal limits (tighter in summer, approx 1.5 mg/L).
- Phosphorus: Monitoring required, with future caps pending.
B. Compliance History
Since the 2012 commissioning, the Spring Creek WRP has maintained a high level of compliance. The facility consistently produces effluent with BOD and TSS levels well below 5 mg/L, often achieving single-digit concentrations that rival the water quality of the receiving stream. The District actively participates in the Sangamon River study groups to model watershed health.
7. OPERATIONAL EXCELLENCE
The SCWRD maintains a staff of Illinois EPA certified operators. The Spring Creek facility utilizes a comprehensive SCADA (Supervisory Control and Data Acquisition) system based on Rockwell Automation/Allen-Bradley platforms. This system provides operators with real-time trending of flows, dissolved oxygen levels, and tank levels, allowing for remote adjustments via tablet or control room workstations.
8. CHALLENGES & FUTURE PLANNING
A. Nutrient Regulations
The primary challenge facing Spring Creek (and all Illinois wastewater plants) is the aggressive tightening of nutrient standards. Removing Total Phosphorus and Total Nitrogen requires complex process adjustments that can compete with carbon removal. The District is currently evaluating “side-stream” treatment technologies to manage nutrient loads returned from the sludge dewatering process.
B. Aging Collection System
While the plant is modern, the collection system in historic Springfield dates back to the early 1900s. Infiltration and Inflow (I/I) remain significant challenges, causing hydraulic peaking at the plant during storm events. The District’s Long-Term Control Plan (LTCP) focuses on separating sewers where feasible and maximizing the capture of “first flush” storm flows at the plant.
9. COMMUNITY & REGIONAL IMPACT
The Spring Creek WRP is vital to the economic development of Springfield. By ensuring reliable wastewater capacity, the District supports the expansion of local industries and the medical district. Furthermore, the high-quality effluent supports the recreational value of the Sangamon River, a popular resource for fishing and boating enthusiasts in Central Illinois.
10. TECHNICAL SPECIFICATIONS SUMMARY
| Parameter | Specification |
|---|---|
| Facility Type | Advanced Secondary (Activated Sludge) with BNR |
| Design Average Flow | 32.0 MGD |
| Peak Wet Weather Flow | 165 MGD (Total Hydraulic Capacity) |
| Secondary Treatment | Vertical Loop Reactors (VLR) |
| Disinfection | Ultraviolet (UV) Irradiation |
| Nutrient Removal | Nitrification/Denitrification (Bio-P in progress) |
| Biosolids Class | Class B (Land Application) |
| Receiving Water | Sangamon River |
| NPDES Permit | IL0021989 |
| Operating Authority | Sangamon County Water Reclamation District |
| Major Upgrade Year | 2012 (Plant Consolidation) |
11. RELATED FACILITIES
The Spring Creek WRP works in conjunction with the Sugar Creek Plant, a smaller 10 MGD facility operated by SCWRD that serves the eastern and southern portions of the service area. This dual-plant strategy allows for redundancy and better hydraulic management across the diverse topography of Sangamon County.
12. FAQ SECTION
Technical Questions
Q: What is the hydraulic retention time (HRT) of the VLRs?
A: The Vertical Loop Reactors operate with a typical HRT of 12-16 hours during average flow, significantly longer than conventional aeration to ensure complete nitrification.
Q: Does the plant utilize chemical addition for phosphorus removal?
A: Currently, the plant relies primarily on biological mechanisms, but facilities for backup chemical precipitation (Alum or Ferric) are integrated into the future nutrient removal plan.
Q: Is the Spring Creek plant part of CWLP?
A: No. While City Water, Light and Power (CWLP) provides electricity and drinking water, the wastewater plant is owned and operated by the Sangamon County Water Reclamation District (SCWRD), a separate taxing body.
Public Interest Questions
Q: Where does the treated water go?
A: The treated, disinfected water is discharged into Spring Creek, which flows immediately into the Sangamon River.
Q: How are odors controlled at the plant?
A: The headworks (where raw sewage enters) is fully enclosed with negative pressure ventilation scrubbed through biological media filters to neutralize odors before air is released.