Wastewater Treatment Plant Improvements, York City Sewer Authority, PA

The City of York’s Wastewater Treatment Plant was originally constructed in 1916 and has been enlarged and upgraded with six major projects. The plant has a 26 MGD capacity and is located north of York City in Manchester Township on 41.6 acres. The plant serves eight municipalities: The City of York, North York and West York Boroughs, and Manchester, Spring Garden, Springettsbury, West Manchester, and York Townships.

The first major plant project was completed in the early 1950s and converted the primary treatment plant to an activated sludge plant using the contact stabilization process. This project also added anaerobic sludge digestion. The rated plant capacity at the time was 18 MGD.

The next major upgrade was completed in the early 1980s and expanded the plant from 18 MGD to the current rating of 26 MGD. This expansion was accomplished by the construction of an 8 MGD pure oxygen treatment system designated as Train 1 and the existing 18 MGD treatment facility was named Train 2. This upgrade also added chemical phosphorus removal.

By the mid-1980s nitrification became a regulatory requirement, and the plant was then again upgraded. This time, a third treatment train, Train 3, was added on acquired property adjacent to the existing plant property. Train 3 provided the additional tankage required to accomplish nitrification and allowed the phosphorus removal process to be converted from chemical to biological removal. The project also added an effluent filtration system and converted the disinfection process from chlorine to ultraviolet (UV) light disinfection. At the time, York’s UV disinfection system was the largest in the eastern United States. A state-of-the-art, plant-wide computer control and monitoring system was added along with an engine-driven, 1,500 kW cogeneration system using the digester gas. Most of the other existing treatment facilities were improved under this major project completed by 1990.

In 1996, a need to increase the disinfection peak hydraulic treatment capacity to 57 MGD prompted a new design to replace the original UV disinfection system. To replace the existing system, a low-pressure, high-intensity system was selected and was installed within the existing channels with minor modifications. The installation of the new system was sequenced to maintain continuous operation of the facility.

By the mid-2000s, nitrogen removal was required, and the treatment process was again modified to meet the new biological nutrient removal (BNR) requirement. This time, the aeration system was modified to include de-nitrification while maintaining biological phosphorus removal. The BNR capacity of the plant was set at an average daily flow rate of 18 MGD, which it is not expected to exceed within the next 20 years.

In 2009, the implementation of the Ostara Pearl® process was integrated to treat liquid remaining from sludge dewatering (centrate) by removing ammonia and phosphorus and converting it into a high-quality, environmentally safe fertilizer. The process reduces the ammonia and phosphorus load in the centrate returned to the BNR treatment process. At this same time, the plant-wide computer control and monitoring system was updated with more modern software and hardware.


The existing 1,500 kW cogeneration system was replaced in 2010 with newer technology consisting on Capstone Microturbines with a rated capacity of 1,600 kW. The new facility replaced the internal combustion-engine-driven generators with three microturbines using methane gas and five natural gas units to generate electricity. The microturbines are essentially jet engines. The three digester gas microturbines generate 2.5 million kWh of electricity saving the York City Sewer Authority more than $277,000 in energy costs annually. A heat-recovery unit also harvests waste heat from the digester gas turbines, which is used to heat the digesters and on-site buildings. This project won the Diamond Honor Award for Energy Projects at the American Council of Engineering Companies of Pennsylvania’s Diamond Awards for Engineering Excellence.

The plant has received a number of awards in addition to the Diamond Honor Award including:

  • Chesapeake Bay Local Government Advisory Committee Award for Community Innovation (1996)
  • National Finalist Statue in the Engineering Excellence Awards Competition for the York WWTP Upgrade (1993)
  • Consulting Engineers Council of PA Honor Award for Engineering Excellence (1993)
  • US EPA Wastewater Management Excellence Award (1993)
  • US EPA Operations and Maintenance Excellence Award (1995)
  • PWEA Operations and Maintenance Excellence Award (1995)
  • CPWQA Plant Excellence Award (1994)
  • Governor’s Award for Environmental Excellence (1997 and 1999)
  • US EPA National Wastewater Operations and Maintenance Excellence Award (1999)