Pennsylvania Wastewater Treatment Plants

Pennsylvania Wastewater Treatment Plants

Introduction

Pennsylvania’s wastewater infrastructure represents one of the most complex and historic networks in the United States. With a unique topography that spans the Delaware, Susquehanna, and Ohio River basins, the Commonwealth manages a vast array of treatment facilities ranging from massive metropolitan plants in Philadelphia and Pittsburgh to critical rural lagoons. Currently, Pennsylvania faces a dual challenge: aging infrastructure in legacy industrial cities and strict nutrient removal requirements driven by the Chesapeake Bay Total Maximum Daily Load (TMDL) mandates.

The state is home to over 1,000 publicly owned treatment works (POTWs), serving a population of nearly 13 million. The Pennsylvania Department of Environmental Protection (PA DEP) oversees a regulatory environment that is increasingly focused on wet weather management, specifically the reduction of Combined Sewer Overflows (CSOs). With billions in capital investment currently in motion, facilitated by PENNVEST and federal IIJA funding, Pennsylvania is a primary market for engineering firms, equipment vendors, and infrastructure developers.

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Recent Developments & Market Outlook

In the last 36 months, Pennsylvania has seen an unprecedented surge in capital improvement planning, driven largely by consent decrees and the availability of low-interest financing. The most significant development is the aggressive implementation of Long-Term Control Plans (LTCPs) to address CSOs in Pittsburgh, Harrisburg, and Philadelphia. Unlike many states focusing solely on gray infrastructure, Pennsylvania—particularly Philadelphia—has pioneered the integration of green stormwater infrastructure (GSI) alongside traditional treatment upgrades.

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Key developments include:

  • The ALCOSAN Clean Water Plan: A multi-billion dollar initiative in Allegheny County involving massive deep tunnel construction and plant expansion.

  • Bioenergy Initiatives: A growing trend among mid-sized authorities (10-50 MGD) to upgrade anaerobic digesters for Combined Heat and Power (CHP) and Renewable Natural Gas (RNG) production.

  • PFAS Monitoring: The PA DEP has ramped up sampling requirements for Per- and Polyfluoroalkyl Substances (PFAS), prompting early-stage designs for advanced filtration retrofits.

  • Federal Funding Influx: The Infrastructure Investment and Jobs Act (IIJA) has injected over $240 million annually into the state’s Clean Water State Revolving Funds (SRF), accelerating projects that were previously stalled due to budget constraints.

Top 20 Largest Wastewater Treatment Plants in Pennsylvania

The following table ranks Pennsylvania’s largest wastewater treatment facilities by Design Capacity (MGD). These facilities represent the backbone of the state’s sanitary infrastructure.

Rank Plant Name City/Location Design Capacity (MGD) Operating Authority
1 Southeast Water Pollution Control Plant Philadelphia 250 MGD Philadelphia Water Department (PWD)
2 ALCOSAN Main Treatment Plant Pittsburgh 250 MGD Allegheny County Sanitary Authority
3 Northeast Water Pollution Control Plant Philadelphia 210 MGD Philadelphia Water Department (PWD)
4 Southwest Water Pollution Control Plant Philadelphia 200 MGD Philadelphia Water Department (PWD)
5 Erie Wastewater Treatment Plant Erie 68.6 MGD Erie Sewer Authority
6 DELCORA Western Regional Treatment Plant Chester 50 MGD Delaware County Regional Water Quality Control Authority
7 Wyoming Valley Sanitary Authority Hanover Township 50 MGD Wyoming Valley Sanitary Authority
8 Capital Region Water AWTF Harrisburg 45 MGD Capital Region Water
9 Kline’s Island Wastewater Treatment Plant Allentown 40 MGD Lehigh County Authority
10 Lancaster Advanced Wastewater Treatment Plant Lancaster 32 MGD City of Lancaster
11 Fritz Island Wastewater Treatment Plant Reading 28.5 MGD City of Reading
12 Scranton WWTP Scranton 25 MGD Pennsylvania American Water
13 York City Wastewater Treatment Plant York 26 MGD York City Sewer Authority
14 Bethlehem Wastewater Treatment Plant Bethlehem 20 MGD City of Bethlehem
15 Williamsport Sanitary Authority Central Plant Williamsport 19.5 MGD Williamsport Sanitary Authority
16 University Area Joint Authority (UAJA) State College 14.8 MGD University Area Joint Authority
17 Lower Bucks County Joint Municipal Authority Levittown 15 MGD LBCJMA
18 Norristown Wastewater Treatment Plant Norristown 14.5 MGD Municipality of Norristown
19 Altoona Westerly Wastewater Treatment Facility Altoona 14 MGD Altoona Water Authority
20 East Norriton-Plymouth-Whitpain Joint Sewer Plymouth Meeting 13.5 MGD ENPWS Authority

Profiles of Top 5 Largest Facilities

1. Southeast Water Pollution Control Plant (Philadelphia)

  • Location: Philadelphia, PA (Delaware River)

  • Design Capacity: 250 MGD (Peak wet weather: 500+ MGD)

  • Population Served: Approx. 1 million (South Philadelphia/Suburbs)

  • Operating Authority: Philadelphia Water Department (PWD)

  • Treatment Process: Pure oxygen activated sludge, secondary clarification, hypochlorite disinfection.

  • Infrastructure Highlights: Features a massive biogas cogeneration facility. The “Biosolids Recycling Center” located here processes sludge from all three PWD plants into “PhillyEarth” compost.

  • Recent Upgrades: Major electrical distribution upgrades ($70M+) and ongoing Act 537 upgrades for wet weather optimization.

2. ALCOSAN Main Treatment Plant (Pittsburgh)

  • Location: Pittsburgh, PA (Ohio River)

  • Design Capacity: 250 MGD (Expanding to 480-600 MGD wet weather capacity)

  • Population Served: 825,000 across 83 municipalities

  • Operating Authority: Allegheny County Sanitary Authority

  • Treatment Process: Screening, grit removal, primary sedimentation, conventional activated sludge, chlorination/dechlorination.

  • Infrastructure Highlights: The hub of the region’s wet weather plan. It utilizes deep bed gravity thickeners and centrifuges for solids handling.

  • Compliance: Currently under a major federal consent decree to reduce annual CSO volume by 7 billion gallons by 2036.

3. Northeast Water Pollution Control Plant (Philadelphia)

  • Location: Philadelphia, PA (Delaware River)

  • Design Capacity: 210 MGD

  • Population Served: 600,000+ (Northeast Philly and Montgomery County suburbs)

  • Operating Authority: Philadelphia Water Department (PWD)

  • Treatment Process: Modified aeration activated sludge.

  • Infrastructure Highlights: This is one of the oldest plants in the system but has undergone extensive modernization. It serves a heavily industrialized corridor.

  • Key Projects: Ongoing replacement of preliminary treatment facilities and headworks to manage grit and screenings more effectively.

4. Southwest Water Pollution Control Plant (Philadelphia)

  • Location: Philadelphia, PA (Schuylkill River)

  • Design Capacity: 200 MGD

  • Population Served: 800,000 (West Philly and Delaware County suburbs)

  • Operating Authority: Philadelphia Water Department (PWD)

  • Treatment Process: Oxygen-activated sludge.

  • Compliance: Critical for protecting the Schuylkill River ecosystem before it meets the Delaware.

  • Recent Upgrades: Installation of new high-efficiency aeration blowers and a comprehensive digester heating system upgrade.

5. Erie Wastewater Treatment Plant

  • Location: Erie, PA (Lake Erie)

  • Design Capacity: 68.6 MGD

  • Population Served: ~200,000

  • Operating Authority: Erie Sewer Authority

  • Treatment Process: Activated sludge with rigorous phosphorus removal requirements due to Great Lakes discharge.

  • Infrastructure Highlights: Operates a fluidized bed incinerator for solids handling.

  • Notable Features: Given its discharge into Lake Erie, the plant adheres to strict International Joint Commission water quality standards.

Plants with Approved Budgets & Expansion Projects

Pennsylvania is currently experiencing a construction boom in the wastewater sector, driven largely by Consent Decree compliance and the modernization of assets dating back to the mid-20th century. Below are the most significant active and planned projects.

A. Major Projects Under Construction (2024-2026)

ALCOSAN – Clean Water Plan (Plant Expansion & Tunnels)

  • Location: Pittsburgh, PA

  • Total Budget: $2+ Billion (Multi-phase)

  • Project Scope:
    • Expansion of plant wet weather capacity from 250 MGD to 480 MGD.

    • Construction of the Ohio River Tunnel segment (part of the regional tunnel system).

    • New main pump station and chlorine contact tank expansion.

  • Funding: Revenue Bonds, WIFIA Loans, PENNVEST.

  • Key Contractors/Engineers: Arcadis, HDR, CDM Smith (Program Management).

  • Status: Active construction on plant expansion; Tunnel design/early works ongoing.

  • Drivers: Federal Consent Decree to eliminate sanitary sewer overflows (SSOs) and reduce combined sewer overflows (CSOs).

Capital Region Water – City Beautiful H2O Program

  • Location: Harrisburg, PA

  • Total Budget: $315 Million (Long-term plan)

  • Project Scope:
    • Advanced Wastewater Treatment Facility (AWTF) upgrades including primary clarifier rehabilitation.

    • Large-scale green infrastructure implementation to reduce CSO volume.

    • Sewer rehabilitation and interceptor improvements.

  • Funding: PENNVEST Low-interest loans, Revenue Bonds.

  • Expected Benefits: 40% reduction in nutrients discharged to the Susquehanna River/Chesapeake Bay.

  • Status: Ongoing implementation (Phased).

DELCORA – Tunnel & Treatment Modification

  • Location: Chester, PA / Delaware County

  • Total Estimated Budget: $500 – $800 Million

  • Project Scope:
    • Construction of a deep rock tunnel to convey flow from Eastern Delaware County to the Western Regional Treatment Plant (WRTP).

    • Major upgrades to WRTP to handle increased load and industrial flow.

  • Drivers: Resolving the impending disconnection from Philadelphia’s Southwest plant treatment agreement and addressing CSOs.

  • Status: Design and early procurement phases.

B. Projects in Design/Planning Phase (2025-2027)

  • Lehigh County Authority (Kline’s Island) Master Plan:
    • Budget: ~$300 Million+ projected.

    • Scope: Regional solution for inflow/infiltration (I/I) reduction and capacity expansion to 50+ MGD to support Lehigh Valley growth.

    • Status: Act 537 Plan revision and preliminary engineering.

  • Scranton Sewer Authority (PA American Water) Improvements:
    • Budget: $140 Million (Capital plan).

    • Scope: CSO separation projects and treatment plant modernization following the privatization/acquisition.

    • Status: Ongoing phased design and construction.

C. Summary Statistics

  • Total Active Capital Investment: >$3.5 Billion (Statewide major projects)

  • Primary Project Driver: Wet Weather/CSO Compliance (70% of spend)

  • Funding Source Dominance: PENNVEST (State Revolving Fund) provides the majority of low-interest financing.

  • Key Technology Trend: Retrofitting for nutrient removal (BNR) and high-rate wet weather treatment (ballasted flocculation).

Regulatory & Compliance Landscape

Engineering and operations in Pennsylvania are dictated by strict adherence to both state and interstate compacts.

Chesapeake Bay Watershed Implementation Plan (WIP)

Approximately half of Pennsylvania drains into the Chesapeake Bay. Plants in the Susquehanna and Potomac basins face the strictest Nitrogen and Phosphorus limits in the region. This has driven a wave of Biological Nutrient Removal (BNR) upgrades over the last decade and continues to drive optimization projects.

Act 537 (Sewage Facilities Act)

All municipalities must maintain an up-to-date Act 537 plan. Engineering firms are frequently retained to update these comprehensive plans, which is often the precursor to major capital project procurement. Without an approved Act 537 plan, DEP will not issue construction permits.

Combined Sewer Overflows (CSO)

Pennsylvania has the highest number of CSO communities in the nation. The EPA and PA DEP enforce Long-Term Control Plans (LTCPs), which require utilities to capture and treat a high percentage (typically 85%+) of wet weather flow. This drives the market for:

  • Deep tunnel storage systems.

  • High-rate treatment technologies (e.g., Actiflo, CoMag).

  • Real-time control (RTC) sensors and SCADA upgrades.

Resources for Engineers & Operators

  • Pennsylvania Municipal Authorities Association (PMAA) – Key association for utility managers.

  • Pennsylvania Water Environment Association (PWEA) – The state WEF member association; hosts the annual PennTec conference.

  • PENNVEST – The primary funding authority for water infrastructure loans and grants.

  • PA DEP Wastewater Construction – Permitting and technical guidance.

Frequently Asked Questions

What is the largest wastewater treatment plant in Pennsylvania?

The Southeast Water Pollution Control Plant in Philadelphia is the largest, with a design capacity of 250 MGD and the ability to treat significantly higher peak flows.

What funding is available for wastewater projects in PA?

PENNVEST is the primary source, offering low-interest loans and grants. Additionally, the federal WIFIA program supports large-scale projects like ALCOSAN, and H2O PA grants are available for high-hazard dam and sanitary projects.

Why are there so many sewer projects in Pittsburgh and Philadelphia?

Both cities have older “combined” sewer systems where stormwater and sewage share pipes. Federal Consent Decrees require these cities to reduce overflows into rivers, necessitating billions in investment for tunnels, plant expansions, and green infrastructure.

What are the nutrient removal requirements in PA?

Plants discharging to the Chesapeake Bay watershed generally face strict caps on Total Nitrogen (TN) and Total Phosphorus (TP). Many facilities engage in nutrient credit trading if they cannot meet limits solely through technological upgrades.

Who regulates wastewater treatment in Pennsylvania?

The Pennsylvania Department of Environmental Protection (PA DEP) Bureau of Clean Water administers the NPDES program and oversees compliance.