AWWA ACE54516

The Groundwater Replenishment System (GWRS), currently ready to begin final design, is a joint program of the Orange County Water District (OCWD) and the Orange County Sanitation District (OCSD). The GWRS will be one of the largest advanced recycled water treatment plants in the world when all phases are completed, treating over 174 million gallons per day of secondary treated wastewater from OCSD's Plant No. 1. The advanced water treatment facilities (AWTF) will include microfiltration (MF), reverse osmosis (RO), ultraviolet (UV) oxidation, and various other ancillary facilities constructed to replace OCWD's existing Water Factory 21 (WF 21). The product water from the AWTF will be used for groundwater recharge and injection into the local seawater intrusion barrier, rather than discharging the secondary effluent into the Pacific Ocean through the OCSD outfall. The project will provide a new, cost-effective, reliable source of water and eliminate the need to construct an additional outfall pipe. The basic treatment process scheme, as related herein, was determined as during the feasibility/EIR phase. Thirty-one technical memorandums were prepared as part of the Preliminary Design phase to thoroughly define the detailed technical basis for the project. The preliminary design was completed in December 2000. Important AWTF criteria were developed for the water quality and quantity, demolition, and the major treatment processes, including the MF, RO, UV, pump stations and chemical feed systems. A conceptual site plan was prepared to locate each of the AWTF structures. Finally, the distribution system for the treated product water was also defined, including pipeline alignments, discharge facilities and well locations. The estimate of probable construction costs is about $352 million dollars, with operation and maintenance (O&M) costs ranging from $19.7 million to 23.8 million. The project will be constructed in 11 different conventional design/bid/build contracts. The implementation schedule projects the complete treatment and delivery systems to be completed and operational by mid 2005. After much debate as to the cost and necessity of the GWR System, the joint OCWD and OCSD Board of Directors voted on March 28, 2001, to proceed to the design and implementation phases of the project. Includes tables, figures.