Robert B. Diemer Treatment Plant
Briefing Paper
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Overview R
 The Robert B. Diemer Treatment Plant is one of five treatment plants in the Metropolitan Water
District (MWD) system.
 Located in Yorba Linda, the plant’s hilltop location is well suited for gravity-flow distribution of
water to homes and businesses throughout Los Angeles and Orange counties.
 The Diemer Plant delivers up to 520 million gallons of treated water per day - enough to fill up
the Rose Bowl every 4 hours.
 Most water brought to the Diemer Plant for treatment comes from the Colorado River via the
242-mile Colorado River Aqueduct. To a lesser degree, the plant also receives water from
Northern California through the State Water Project.
 The Diemer facility is the only treatment plant in the MWD system that has an on-site
hydroelectric power generator. The 5.1 megawatt Yorba Linda Hydroelectric Power Plant uses
the water rushing through the pipelines leading to Diemer to supplement MWD’s energy needs.
Current Treatment Process
The Diemer Plant currently uses a conventional filtration system to treat water supplies. This
process begins before water even reaches the Plant using upstream gates and screens to catch
large debris and plants floating in the water as it travels through the pipelines leading to Diemer.
Once at the treatment plant, a process called ‘coagulation’ is used to remove particles in the
water that made its way through the upstream filter screens. Coagulation means to
thicken, or solidify. This involves using aluminum sulfate and other chemicals
that cling to the particle matter in the water creating larger, removable particles
called floc.
The water and floc are then moved to large sedimentation tanks. The floc settles
to the bottom of the tanks and the water is put in basins where it filters through
coal and sand to remove any remaining particle matter. Once filtration is
completed, chlorine and ammonia are added to the water to disinfect and kill any
remaining microorganisms living in it.
This multi-step, costly procedure of treating water is necessary to remove harmful
microorganisms such as bacteria, viruses and protozoa that are present in
natural water sources and can make you very sick if ingested.
Continued…
Street Address: 18700 Ward Street, Fountain Valley CA 92708
Phone Number: (714) 963-3058 Website: www.mwdoc.com
Oxidation Retrofit Program
In 2008, MWD began a major construction project at the Diemer Plant to upgrade its water treatment
process. This upgrade will replace the traditional conventional filtration process with an ozone water
treatment system that doesn’t require the use of chemicals. The ozone water treatment process relies on
oxidation, which is the addition of oxygen molecules (ozone) to the water. Oxidation changes the
chemical composition of contaminates in the water by breaking down its cell walls and disinfecting it.
The implementation of this new treatment
system has made it necessary to vastly expand
the Diemer Plant’s facilities. This expansion
includes the construction of a new two-story
ozone building and lobby and control room,
an ozone generator room and support
spaces, a switchgear building, a liquid oxygen
and solids handling building, and the
installation of a new emergency power
generator with housing. The oxidation retrofit
is scheduled for completion in 2012. This new
treatment system will ensure the plant meets
all future federal regulations.
The Plant’s Namesake
The Diemer Plant is named after former MWD general manager and chief engineer Robert B. Diemer
(1951-62), who successfully directed an expansion program that brought the Colorado River Aqueduct up
to its full delivery capacity of 1 billion gallons a day. Later, he also served on the MWD Board of Directors
representing the City of Pasadena.
Summary
The Robert B. Diemer Treatment Plant opened in 1963 and is only one of 3 treatment plants in the MWD
system that blend Colorado River and State Water Project water together. At 212-acres, it’s one of the
largest water treatment plants in the United States, treating up to 520 million gallons of water per day –
enough to serve 3 million people. It provides nearly half of Orange County’s total water supply, and is
especially critical to South County communities that can’t rely on well water. Diemer is transitioning to
using an ozone water treatment system that will not require the use of chemicals. The new ozone system
will help the plant meet future federal regulations and is scheduled for completion in 2012.
For more information, please contact:
Darcy M. Burke, M.B.A.
Director of Public Affairs
Municipal Water District
of Orange County
Phone: (714) 593-5014
E-mail: [email protected]
Tiffany Baca
Public Affairs/Government Affairs
Municipal Water District
of Orange County
Phone: (714) 593-5013
E-mail: [email protected]
Street Address: 18700 Ward Street, Fountain Valley CA 92708
Phone Number: (714) 963-3058 Website: www.mwdoc.com