City of Modesto, Calif., Phase 2 BNR/Tertiary WWTP

Dec. 9, 2015

Cost: $132 million
Location: Modesto, Calif.
Year: 2015-12-09
Size: 12.6 mgd
Owner: City of Modesto, Calif.
Designers: Carollo Engineers Inc.
Contractor: GSE Construction Co. Inc., J.R. Filanc Construction Co. Inc., San Joaquin Electric Inc.

The city of Modesto, Calif., currently employs oxidation ponds for secondary wastewater treatment. Due to more stringent limits on the city’s discharge permit, the effluent had to be treated to a higher level in order to discharge into the San Joaquin River. Knowing that modifications would need to be made, the city chose to treat the effluent to Title 22 reclaimed water standards.

As a result of the project, the city can provide this reclaimed water to a local irrigation district, which has received no allocation for irrigation water because of the California drought. Membrane technology provides a high-quality effluent for the farmers. The plant’s size also will allow the city to expand and welcome additional industry due to the added capacity. 

Collaboration by team members mitigated the most significant challenges in the project. Two pre-purchase agreements—one with the membrane supplier and one with the in-channel ultraviolet supplier—were signed before the job bidding. This helped alleviate any issues with different manufacturers requiring different piping configurations or structural or electrical modifications.

The three-year construction phase was completed in September 2015. 

“The Phase 2 project has been a very successful project for the city of Modesto. It is the largest capital improvement project that the city has ever constructed to date,” said Will Wong, P.E., engineering division manager for the city of Modesto’s utility department. “This project will result in a regional solution to California’s water crisis. The recycled water produced by the facility will provide long-term, reliable water supplies to mitigate ongoing and severe contractual water supply shortages for agricultural irrigation and potentially wildlife refuges.“ 

Project Year: 2015-12-09Contractor: GSE Construction Co. Inc., J.R. Filanc Construction Co. Inc., San Joaquin Electric Inc.Designers: Carollo Engineers Inc.Owner: City of Modesto, Calif.Location: Modesto, Calif.Cost: $132 millionSize: 12.6 mgd