Strategic Wastewater Infrastructure

In 1981, GBA laid the groundwork for O’Fallon, Missouri’s growth with a wastewater system expansion that set the city up for decades of success.

To support the City of O’Fallon’s rapid expansion, GBA provided preliminary planning and design for a critical addition to the City’s wastewater treatment system. The project expanded the facility’s treatment capacity to 5.25 million gallons per day, accommodating increasing demand across nearly 40 square miles of St. Charles County.

Working in close collaboration with City leadership, including the mayor, GBA helped develop a strategic plan that aligned with the region’s accelerated growth. A key component of the project included the construction of approximately 30 miles of interceptor sewers, with pipe sizes reaching up to 42 inches in diameter. The system upgrade positioned O’Fallon to manage both current needs and anticipated future development effectively.

Project at a Glance:

5.25 Million Gallons per Day (MGD) – Increased treatment capacity

40 Square Miles – Service area covered by the expanded system

30 Miles of Interceptor Sewers – Installed as part of system upgrades

42-Inch Diameter Pipes – Largest sewer pipe size used in construction