San Jacinto River Authority Regional Wastewater Treatment Plant

FACILITY BASIC INFORMATION

• Plant Name: SJRA Woodlands Division Wastewater Treatment Plant No. 1 (Flagship Facility) & Regional System
• Location: 2436 Sawdust Rd, The Woodlands, Montgomery County, Texas
• Operating Authority: San Jacinto River Authority (SJRA) – Woodlands Division
• Combined Permitted Capacity: 20.1 MGD (System Total)
• Plant No. 1 Capacity: 7.8 MGD
• Current Average Flow: ~13-14 MGD (System Wide)
• Population Served: ~118,000 residents
• Service Area: The Woodlands Township (Montgomery County MUDs)
• Receiving Water Body: Panther Branch and Lower Panther Branch (tributaries to Spring Creek/San Jacinto River)
• NPDES/TPDES Permit Number: WQ0010304001 (Plant 1)
• Year Commissioned: 1975 (Original construction)

TARGET AUDIENCE

• Municipal consulting engineers evaluating regionalized treatment systems

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• Wastewater treatment plant operators and managers
• Equipment vendors researching plant specifications
• Environmental regulators (TCEQ/EPA) and compliance officers
• Engineering firms pursuing Capital Improvement Plan (CIP) projects
• Municipal decision-makers planning aging infrastructure rehabilitation

1. INTRODUCTION

The San Jacinto River Authority (SJRA) Woodlands Division operates a comprehensive regional wastewater system that serves as the sanitary backbone for The Woodlands, one of the nation’s premier master-planned communities. Central to this infrastructure is Wastewater Treatment Plant No. 1 (WWTP No. 1), the largest and administrative hub of a three-plant interconnected system. Commissioned in 1975, the facility has undergone multiple expansions and rehabilitations to keep pace with the region’s explosive population growth, which now exceeds 118,000 residents.

Operating under the Texas Commission on Environmental Quality (TCEQ), the system manages an average daily flow of approximately 13-14 million gallons per day (MGD) across the three facilities, with a total permitted capacity of 20.1 MGD. As a wholesale service provider to eleven Municipal Utility Districts (MUDs), the SJRA system represents a model of regional cooperation and efficiency. Following a comprehensive 10-year asset management plan initiated in 2017, the facility is currently in the midst of significant capital reinvestment aimed at modernizing aging assets, improving energy efficiency, and ensuring resilience against Gulf Coast weather events.

2. FACILITY OVERVIEW

A. Service Area & Coverage

The facility serves The Woodlands Township located in southern Montgomery County, Texas. The service area is primarily residential and light commercial, defined by a unique governance structure where SJRA acts as the wholesale provider for water and wastewater services, while the Municipal Utility Districts (MUDs) function as retail providers. The collection system is extensive, relying on gravity mains feeding into a network of over 30 lift stations that convey flow to the three treatment plants. The demographics are characterized by high-density suburban development with strict aesthetic and environmental standards.

B. Operational Capacity

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The Woodlands Division wastewater system operates three distinct facilities that function as a regional unit:

• WWTP No. 1: 7.8 MGD Permitted Capacity (Main Complex)
• WWTP No. 2: 6.0 MGD Permitted Capacity
• WWTP No. 3: 6.3 MGD Permitted Capacity (Serves the western sector)

Historically, the system operates at approximately 65-70% of its total hydraulic capacity, providing sufficient buffer for wet weather events. However, rapid intensification of the service area has necessitated strategic rerouting of flows between plants to balance loading.

C. Discharge & Compliance

Treated effluent from WWTP No. 1 is discharged into Panther Branch, which flows into Spring Creek and ultimately the West Fork of the San Jacinto River. The facility operates under a Texas Pollutant Discharge Elimination System (TPDES) permit administered by the TCEQ. The receiving waters are sensitive regarding dissolved oxygen and nutrient loading, requiring strict adherence to Carbonaceous Biochemical Oxygen Demand (CBOD) and Ammonia-Nitrogen limits. The plant has maintained a “High Performer” classification in compliance history, despite challenges posed by heavy rainfall and inflow/infiltration (I/I) issues common in the Gulf Coast region.

3. TREATMENT PROCESS

The SJRA Regional Plants utilize a conventional activated sludge process designed for nitrification to meet ammonia limits. The following detailed description focuses on the process train at the primary facility, WWTP No. 1.

A. PRELIMINARY TREATMENT

Raw wastewater enters the headworks where it undergoes physical screening and grit removal. The facility utilizes mechanical bar screens to remove large debris, plastics, and rags to protect downstream pumps. Following screening, flow enters aerated grit chambers where velocity is controlled to allow inorganic sands and grit to settle while keeping organic matter in suspension. The grit is mechanically removed, washed, and disposed of in a sanitary landfill. Recent upgrades have focused on odor control at the headworks using chemical scrubbers to mitigate nuisance odors near residential zones.

B. SECONDARY TREATMENT (Activated Sludge)

The core biological treatment is achieved through a conventional activated sludge process.

• Aeration Basins: The flow enters multiple parallel aeration basins. These rectangular basins utilize fine-bubble diffused aeration systems to provide the necessary oxygen transfer for microbial metabolism. The system operates in a complete-mix regime.
• Biological Process: The biological community is managed to target Carbonaceous Biochemical Oxygen Demand (CBOD) removal and nitrification (conversion of ammonia to nitrate). The Solids Retention Time (SRT) is manipulated seasonally to maintain nitrification efficiency, particularly during cooler months.
• Secondary Clarification: Mixed liquor flows to circular center-feed secondary clarifiers. Here, the biological floc settles by gravity to the bottom, while clear supernatant flows over the weirs. The clarifiers are equipped with suction-header sludge collectors.
• RAS/WAS: Settled sludge is returned to the aeration basins via Return Activated Sludge (RAS) pumps to maintain mixed liquor suspended solids (MLSS) concentrations. A portion is wasted (WAS) to the solids handling train to control the biological population age.

C. DISINFECTION

Before discharge, the clarified effluent undergoes disinfection to eliminate pathogenic organisms. The facility utilizes Chlorination via chlorine gas or sodium hypochlorite solution, followed by a contact time in serpentine basins. Following the contact period, the effluent is Dechlorinated using sulfur dioxide or sodium bisulfite to remove residual chlorine, preventing toxicity to aquatic life in Panther Branch.

D. SOLIDS HANDLING

SJRA operates a centralized solids handling strategy.

• Digestion: Waste Activated Sludge (WAS) is pumped to aerobic digesters. The aerobic digestion process stabilizes the sludge, reducing volatile solids and pathogen content while producing a Class B biosolid.
• Thickening/Dewatering: Digested sludge is thickened and then dewatered using Belt Filter Presses. This mechanical separation produces a sludge cake with 15-20% solids content.
• Disposal: The dewatered cake is hauled off-site to a sanitary landfill.

E. PROCESS CONTROL

The facility utilizes a Supervisory Control and Data Acquisition (SCADA) system for real-time monitoring of lift stations, flow rates, and equipment status. An on-site laboratory performs daily process control testing (settleability, microscopy, pH, DO) while compliance samples are analyzed for TPDES reporting.

4. INFRASTRUCTURE & FACILITIES

A. Physical Plant

WWTP No. 1 is situated on a multi-acre site that also houses the Woodlands Division administrative headquarters, maintenance shops, and a central laboratory. The architecture of the visible buildings is designed to blend with the forested aesthetic of The Woodlands. The site is fully fenced and secured, with critical electrical infrastructure elevated or protected against localized flooding.

B. Energy Systems

Energy management is a critical operational focus. The aeration blowers represent the largest electrical load. The facility has implemented Variable Frequency Drives (VFDs) on major blowers and pumps to match energy consumption with biological demand. Emergency power is provided by onsite diesel generators capable of running the plant’s critical hydraulic components during grid outages—a vital feature during hurricane season.

C. Odor Control

Given the proximity to high-value residential properties and commercial districts, odor control is paramount. The facility employs chemical wet scrubbers and biological treatment units at the headworks and solids handling buildings. Atmospheric dispersion modeling is periodically reviewed to ensure odor plumes do not impact the surrounding community.

5. RECENT UPGRADES & MAJOR PROJECTS

The SJRA Woodlands Division has been executing a robust 10-Year Project Plan to address aging infrastructure from the original 1970s construction. Major recent and ongoing projects include:

Wastewater Treatment Plant No. 1 Rehabilitation – Phase 1 & 2

• Project Scope: Comprehensive rehabilitation of the treatment train, including replacement of coarse and fine bubble diffusers, structural repairs to aeration basins, and upgrades to the electrical distribution system.
• Timeline: 2018–2022 (Phased)
• Investment: Approx. $8 – $12 Million (Cumulative phases)
• Key Technical Highlight: Installation of high-efficiency turbo blowers to replace aging centrifugal blowers, resulting in significant electrical efficiency gains. Replacement of belt filter presses to improve solids capture.

Sanitary Sewer Rehabilitation & Lift Station Renewals

• Project Scope: A systematic rehabilitation of the 30+ lift stations serving the regional plants. This includes pump replacements, coating of wet wells to prevent corrosion from hydrogen sulfide (H2S), and electrical panel upgrades.
• Drivers: Aging infrastructure and Inflow/Infiltration (I/I) reduction.
• Result: Improved reliability and reduced peak flows during storm events.

Future/Ongoing: Biosolids Management Improvements

• Status: Planning/Design Phase
• Scope: Evaluation of long-term solids handling strategies, including potential upgrades to sludge dewatering technologies (e.g., screw presses) to reduce hauling costs and improve cake dryness.

6. REGULATORY COMPLIANCE & ENVIRONMENTAL PERFORMANCE

A. Permit Requirements

The facility operates under TPDES Permit No. WQ0010304001. Key effluent limitations typically include:

• CBOD (5-day): 10 mg/L (Average)
• Total Suspended Solids (TSS): 15 mg/L (Average)
• Ammonia-Nitrogen (NH3-N): 3 mg/L (Average)
• E. Coli: 126 CFU/100 ml
• Minimum Dissolved Oxygen: 4.0 – 6.0 mg/L

B. Compliance History

SJRA has maintained a strong record of compliance with TCEQ standards. The facility participates in the Sanitary Sewer Overflow (SSO) Initiative, a voluntary program to address collection system overflows through proactive maintenance and capital improvements rather than enforcement actions. The Authority routinely monitors Panther Branch to ensure discharge does not degrade water quality or aquatic habitats.

7. OPERATIONAL EXCELLENCE

The Woodlands Division employs a dedicated staff of licensed operators, mechanics, and electricians. SJRA requires high levels of certification; Lead Operators typically hold Class A or B Wastewater Treatment licenses from TCEQ. The division utilizes a computerized maintenance management system (CMMS) to track asset lifecycle and schedule preventive maintenance, shifting the operational culture from reactive to proactive. Safety is emphasized through regular training on confined space entry, chemical handling (chlorine/sulfur dioxide), and electrical safety.

8. CHALLENGES & FUTURE PLANNING

A. Aging Infrastructure

With major components approaching 50 years of age, the primary challenge is the rehabilitation of concrete structures and underground piping without disrupting service. The corrosive nature of wastewater (H2S) has necessitated extensive coating and structural repair projects.

B. Subsidence and Groundwater

Montgomery County has historically relied on groundwater, leading to subsidence issues. SJRA has led the conversion to surface water (via the Surface Water Treatment Plant at Lake Conroe), but the wastewater plants must still contend with the geotechnical realities of the region, requiring careful monitoring of structural foundations and gravity main slopes.

C. Inflow and Infiltration (I/I)

During heavy Gulf Coast thunderstorms, the collection system experiences spikes in flow due to I/I. The Authority continues to work with the MUDs on smoke testing and televising lines to identify and seal illicit connections and compromised pipes.

9. COMMUNITY & REGIONAL IMPACT

The reliability of the SJRA wastewater system is a cornerstone of The Woodlands’ economic success. By maintaining high-quality effluent discharge, the plant protects the aesthetic and recreational value of the local waterways, including The Woodlands Waterway and Lake Woodlands. The facility operates with a “good neighbor” policy, prioritizing odor control and aesthetics to ensure the plant remains unobtrusive to the surrounding high-end residential and commercial developments.

10. TECHNICAL SPECIFICATIONS SUMMARY

12. FAQ SECTION

Technical Questions

1. What is the total permitted capacity of the SJRA Woodlands Division?
The combined permitted capacity of the three regional plants is 20.1 MGD, with Plant No. 1 accounting for 7.8 MGD.

2. Does the facility utilize nutrient removal?
Yes, the facility is designed for nitrification to remove Ammonia-Nitrogen. While total nitrogen and phosphorus limits are not as stringent as some regions, the process is optimized for nutrient reduction.

3. How are biosolids handled?
Sludge is aerobically digested, thickened, and dewatered using belt filter presses. The resulting Class B cake is hauled to a sanitary landfill.

4. Who is responsible for the collection system?
The 11 individual Municipal Utility Districts (MUDs) own the internal collection lines, while SJRA owns and operates the major trunk lines, lift stations, and treatment plants.

Public Interest Questions

5. Does the plant smell?
SJRA utilizes advanced chemical scrubbers and biological filters to neutralize odors. While occasional odors may occur during maintenance or extreme weather, the facility is designed to be odorless at the fence line.

6. Where does the treated water go?
The highly treated effluent is discharged into Panther Branch, which feeds into Spring Creek, supporting local aquatic life and maintaining stream levels.