Best Water/Environment Project: Robert B. Diemer Oxidation Retrofit Project, Yorba Linda

As one of the largest sewage treatment plants in the U.S., the Robert B. Diemer facility delivers 520 million gallons of water per day to Orange and Los Angeles counties, or enough water to fill the Rose Bowl every four hours. This $205-million project is an upgrade and modification of the existing plant to treat potable water with ozone in lieu of chlorine to better meet water quality standards.

Without affecting the existing plant's operations, the team built facilities for liquid oxygen storage, chemical tank farms, ozone generation and more. Plant upgrades included high voltage switchgear and an emergency power generation system. Work also included a new electric substation and new fire and potable water service.

Best Projects judges were impressed by the quantities of materials used and the construction means and methods applied to overcome an extremely challenging site.

Crews installed more than 2 million ft of wire and cable, more than 3,500 valves, 67 pumps, 30,000 linear ft of stainless steel piping and 27,000 linear ft of carbon steel piping, often in confined spaces.

Mass concrete placements of between 2,000 cu yd and 5,000 cu yd were challenging due to the hillside site's 30° to 45° slopes. Shoring reached 40 ft deep in some areas.

Key Players

Contractor Shimmick/Obayashi JV

Owner Metropolitan Water District

Lead Design Firm CDM Smith Inc.