Eagle Mountain Wastewater Treatment Plant Expansion, Eagle Mountain, Utah

Eagle Mountain’s sewer plant ran out of room before the city ran out of growth. The Utah County city broke ground Oct. 23, 2026, on an expansion of its wastewater treatment plant that the 2025 wastewater master plan prices at about $120 million in 2025 dollars, a figure that covers labor, materials, engineering, contingency and added electrical capacity.

The existing plant is rated for 2.4 MGD hydraulically, but its treatment processes hit their loading limit at roughly 1.5 MGD. That gap is the whole story. The city’s population went from 43,623 in the 2020 Census to an estimated 66,557 by July 2025, and Eagle Mountain says it has since passed 80,000. The master plan assumes 175,000 residents by 2060.

Project Scope

The work runs in two tracks. First, interim upgrades to the existing oxidation ditches (new pumps, piping and SCADA equipment) push treatment capacity to about 2 MGD to buy time. Then a new 6 MGD membrane bioreactor train comes online, which AE2S engineer Russell Sprague told the city council in August is scheduled for 2029. The city expects three to four years of construction overall.

The new process train includes a headworks building with screening and grit removal, biological nutrient removal basins, a membrane treatment building, sludge storage tanks, dewatering equipment, electrical systems, and administration and support buildings. Effluent from the MBR is meant for irrigation and other nonpotable uses rather than straight discharge.

AE2S is designing the expansion and MGC Contractors is serving as construction manager/general contractor. The city split the job into six guaranteed maximum price packages so procurement and early work can move while design finishes. The first package bought membrane filtration equipment. The second, awarded to MGC in August for about $4 million, covers the oxidation ditch work and roughly $1 million in excavation. Sprague described the interim phase as “squeezing every drop we can get out of the existing facility.”

Why It Matters

Fast-growing suburbs along the Wasatch Front keep running into the same wall: houses get permitted faster than treatment capacity gets built. Eagle Mountain is tripling its plant’s capacity while it’s still operating near the limit, which is why the interim ditch upgrades matter as much as the headline MBR train.

The reuse angle is the other half. Mayor Jared Gray framed the project around “protecting our culinary water,” and in a dry state, treated effluent sent to irrigation lines is water that doesn’t have to come out of the drinking supply. For contractors, the GMP-package model is worth watching. It lets the city lock long-lead membrane equipment early, but it also means the final price won’t be known until the last package is signed. The $120 million figure is a planning estimate, not a contract.

Project Team & Details