Siloam Springs Design-Build Water Treatment Plant

With an integrated, direct-hire approach, the City of Siloam Springs, Arkansas, undertook a major water system upgrade with confidence that it would be completed within the city’s fixed $31 million budget.

The existing facility was last upgraded three decades ago and had a capacity of 9 million gallons per day (MGD). The city's population has more than doubled since that time and continues to rise by more than 1% each year.

The treatment plant’s pumps, clarifiers and other major equipment were reaching the end of their useful lives, and the reliability of the water supply was threatened by reliance on a single, 65-year-old raw waterline. The city set out to replace or rehabilitate its water treatment facility with the goal of meeting projected water demand for 2040.

Previous engineering assessments had assumed that any improvement project would include an expansion of the city’s treatment capacity and the likely construction of costly new treatment basins. We conducted a comprehensive analysis of those assumptions and found that increased demand created by population growth had been offset by more efficient water use and the loss of some industrial customers.


City of Siloam Springs


Siloam Springs, Arkansas


Design-Build for Water & Wastewater Infrastructure


Government, Military & Municipal


Case Study

Progressive Design-Build Optimizes Water Facility With No Operational Disruptions

The water treatment facility in Siloam Springs, Arkansas, underwent significant improvements to satisfy the needs of a growing population and address ...

Focused on cost optimization.

The plant’s existing capacity of 9 million gallons per day (MGD) would be adequate because while many plant assets would require retrofits or replacement, the concrete structures at the existing plant were generously sized and in good physical condition. New treatment basins would not be necessary, saving the city significant capital costs.

Built-in flexibility for the future.

This allowed the city to recalibrate its expectations for the project’s size and scope. It also revealed an opportunity to build flexibility into the design so that the plant’s capacity could one day be expanded to 12 MGD without major changes to infrastructure.

The project was completed using a progressive design-build approach, the first time in city history. The construction schedule was set to maintain continuous operation of the plant, replacing key equipment during periods of lower demand.