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

W. M. Lyles Co. celebrates another successful joint venture with AECOM and Veolia on the Rialto S1 WWTP Improvements Projects along with Veolia Water West Operating Services, Inc. The plant’s effluent comprises 100% of the City’s stream flow and this expansion project required maintenance of discharge flows for the existing plant at all times.

To make this feasible, the general strategy was to build the Plant No. 5 expansion, new disc filters and new CCT Disinfection and keep them “off -line” until startup and testing were complete. Then, the new facilities could be brought online. Critical path activities included construction of Plant No. 5 facilities. As such, the timing for construction of the other plant facilities had to be so that all new facilities were ready for performance testing at the same time.

Once the new Plant No. 5 facilities were online, a final live connection/tie-in was completed at the influent pipeline without disruption of flow. The final tie-in was completed successfully, this was completed with the use of Bypass systems installed by WML. The project was completed on budget and three months ahead of schedule.


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