The City of Pasco required improvements and modifications to its Wastewater Treatment Facility consisting of numerous structural components. Modification designs incorporated a CMU blower building, a headworks building, aeration basin baffle walls and influent/effluent channels. Desired expansions included structural design of two new below-grade reinforced concrete aeration basins, a reinforced concrete below-grade vault, a primary clarifier effluent box and new pipe support structures. PSE provided various structural designs detailing both the new construction and existing structure modifications. In close coordination with multiple engineering disciplines, we provided an efficient design for the complex wastewater treatment system and plant.