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July/August 2009 home page

Three Day Reserves
David Scherer, Public Works Director, and Bertha Leone, Crest

Aerial view of the water tank at 11th Street.
Photos courtesy David Scherer.

The City of Del Mar uses about 407 million gallons of water a year, or about 1.2 million gallons a day. Through the use of four potable water reservoirs, with a total capacity of four million gallons, the City potentially has three days of potable water storage should an unforeseen event impact the water supply from San Diego.

Reservoir at Zuni and 11th Street

The reservoirs, located on 11th Street, Crest Road, Zuni Drive and Pine Needles, are fed from the Miramar Lake water treatment plant, by three gravity-based water supply connections.

The treated water arrives in a closed, protected system. No treatment or added processes occur from the treatment plant at Miramar to your home. The water does not remain in the pipes or the reservoir for more than a few days. Following State Department of Health Regulations, the Public Works department monitors the water at the distribution points throughout the system to ensure safety.

The water from the reservoirs flows by gravity to the homes served downhill from the reservoirs. The only exception is the area along Crest Road that is served directly from San Diego. During a planned outage, these areas can be served via an emergency pump by the 11th Street Reservoir.

Seismic valve

At various points within the system, pressure control valves exist that maintain minimum and maximum pressure. These valves are also part of an automatic process that allows the reservoirs to drain to a minimum point and then to refill to an upper limit within the tank, maintaining minimum levels and preventing overfilling.

In the event a reservoir is unusable, water can be redirected from another reservoir. For example, the Crest and Torrey Pines Reservoirs are at the same elevation and can assist each other, as can the Zuni and 11th Street reservoirs. If necessary, pipes can be adjusted to a direct feed from the City of San Diego, bypassing the water reservoirs.

The four reservoirs are of varying sizes, from 250,000 to 2 million gallons. The Zuni and 11th Street towers were constructed of concrete in the 1930s. The Steel tanks at Crest and Torrey Pines were installed in the 1960s. The steel tanks are routinely monitored both inside and out for corrosion, and the inside of the tank is recoated and outside areas resurfaced when necessary. All reservoirs have been retrofitted for a seismic event.

Ever wonder why the City of Del Mar has such irregular boundaries?
Its boundaries are those of the water district, operated by a private company in 1959 when the City was incorporated. The map above, dated August 14, 1961, shows the water system as well as proposed additions and extensions as they existed 50 years ago.



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