Pump Station 6 Design

Built in the 1930s, Pump Station EPS-1 had served the Delaware County Regional Water Quality Control Authority (DELCORA) beyond its intended design life. It struggled to manage today’s wastewater flows from the City of Chester and trucked-in waste. As well, wet weather flows often caused combined sewer overflows, which discharged untreated water into the nearby Delaware River. To resolve these concerns, DELCORA reimagined a replacement facility that would raise the bar for innovation, add value to the community, and improve the environment.

Gannett Fleming served as engineer of record for Pump Station 6 (PS-6), a 28 mgd, cutting-edge wastewater collections facility that demonstrates how the forward-thinking design of sanitary infrastructure can benefit a community. Delivered four months ahead of schedule and $4 million under the estimate of probable construction cost, PS-6 helps ensure the safe, efficient collection and treatment of wastewater and a healthy community for generations to come.

What We Did

PS-6 features a self-cleaning trench wet well—just the second of its kind in Pennsylvania—that allows for easy wet well cleaning, prevents problematic grit accumulation, and enhances operator safety by reducing the need to enter the wet well. The capacity of the new facility is more than double that of the prior facility, which improves reliability and prevents millions of gallons of untreated water from discharging into the Delaware River during rain events.

The facility features an advanced odor control system that couples ionization with high-velocity dispersion. The system dramatically decreases peak hydrogen sulfide levels from approximately 1,000 milligrams per liter to 50, reducing odor detection by neighboring communities. To ensure the structural integrity of PS-6, our firm designed a deep foundations program, requiring driven piles to support every component of the project. Also, a new private access road to the facility diverts traffic away from surrounding neighborhoods.

Key Features

  • Wet well parapet wall allows operators to observe cleaning operations without the risk of falling into the well, enhancing worker safety.
  • Concrete slab adjustments and rebar additions during design eliminated the need for 40 steel piles, reducing costs by $180,000 and shortening the project schedule by five weeks.
  • Overhead electrical feeder and duct bank replacements enhanced electrical redundancy to minimize the risk of power outage.
  • Careful construction sequencing allowed existing electrical and data service to be maintained during construction with minimal disruption.

Awards & Recognition

  • Grand Conceptor, 2020, American Council of Engineering Companies of Pennsylvania, Diamond Awards for Engineering Excellence.
  • National Recognition Award, 2020, American Council of Engineering Companies, Engineering Excellence Awards.
  • Award of Merit, Water/Environment, 2019, Engineering News-Record Mid-Atlantic, Regional Best Projects.


  • Flow capacity at headworks pump station increased by more than 100%.
  • Significant reduction of untreated water discharge into the Delaware River.
  • Self-cleaning trench wet well design in accordance with Hydraulic Institute standards.
  • Dramatically reduced peak hydrogen sulfide levels to mitigate odor.


Delaware County Regional Water Quality Control Authority


Chester, Pa.


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