Lewiston WTP Retrofit

2023 | Water/Wastewater | National Award of Merit
Lewiston, ID

Design-Build Team Summary

IMCO and Stantec partnered with the city of Lewiston to upgrade their 100-year-old plant that was at risk of catastrophic failure. Faced with a tight project site hemmed in by the Snake River, a railroad and U.S. Army Corps of Engineers-owned land, the team came up with the unique idea to demolish the existing plant and build a new one on that site.

The project approach hinged on demolishing the primary source of water for more than 15,000 customers. The community is dependent on having accessible water for irrigation during the region’s drier summer months and it was essential to continue providing a reliable water source during construction. The project team scheduled demolition for the fall when water demand was lower, and the city’s well system could meet the community’s needs.

A series of four temporary trailers were commissioned to complement the well system and increase water supply over the summer. The trailers were intended to mirror the same system as the permanent equipment, which gave the operators the added benefit of learning the system early and getting six months of experience prior to the new plant being operational.

Progressive Design-Build Critical to Project’s Success

Leveraging the benefits of Progressive Design-Build (PDB), the team executed more than $10 million in early works packages to hedge against rising costs and material delays caused by the COVID-19 pandemic. Portions of the design were accelerated to make critical decisions for equipment selection and material types.

The PDB process facilitated the completion of this project approximately three years sooner than other project delivery methods. BIM modeling was used to create a 3-D visualization of the project. The use of 3-D technology for structures and civil works avoided pipe conflicts and provided a path for construction on the very limited project site. In addition, because the team was able to sequence the project using 3-D technology, they were able to meet the city’s water needs throughout construction, saving significant additional land and pumping costs.

The ability to control the budget and scope resulted in the project being completed within 2.5% of the budget and two years ahead of the city’s initial schedule.

Design-Build Team

Client/Owner:City of Lewiston
Design-Build Firm:IMCO General Construction, Inc.
Specialty Contractors:Control Systems Technologies, GeoProfessional Innovation, Pall Water Corporation
Owner Advisor:Brown & Caldwell
Project Cost:$29.3 Million
Construction Duration:21 Months