Rialto Water Treatment 2
Rialto Water Treatment 2

City of Rialto, S1 Wastewater Treatment Plant Improvements Project

Wastewater Treatment

Contract Amount: $26,257,399

Project Completion: July 2020

Rialto Water Treatment 11
Rialto Water Treatment 13
Rialto Water Treatment 14

City of Rialto, S1 Wastewater Treatment Plant Improvements Project

Rialto, California

The Wastewater Treatment Plant (WWTP), constructed in 1955 and eventually expanded in later years, was in need of upgrades in order to continue providing reliable service to the community. There are five plants that make up the overall WWTP. Plant 1 is currently not in use and Plants 2, 3, 4 and 5 are in operation.  The Rialto S1 WWTP Improvements Projects is a Joint Venture Project between W.M. Lyles Co. (WML)/AECOM and consists on the following approach and strategy: To build the Plant 5 expansion, new disc filters and new CCT Disinfection “off-line” and after appropriate startup and testing bring the new facilities into service. Construction of Plant 5 facilities is the critical path and accordingly construction timing of other plant facilities will be adjusted so that all new facilities are ready for performance testing at the same time. Once new Plant 5 facilities are online, commissioned and successfully complete a 30-day performance test, we will next take the existing Plant 5 Aeration Basins off-line for effluent gate replacement and the anoxic zone baffle wall modifications. After first Aeration Basin work startup and testing is complete, the second existing Aeration Basin will be taken off-line and the needed improvements conducted. The project is currently on time and on budget.


City of Rialto (Public Works)

437 N. Riverside Ave.

Rialto, CA 92376

Owner Contact:

Thomas Crowley

Design Engineer:


401 West A Street # 1200

San Diego, CA 92101

Engineer Contact:

Jim Mitchell

W.M. Lyles Co. PM

Grant Gourley