Bulletin Board

Preparing for Summer Water Demand

April 17, 2000

During the spring the trees bud, tulips poke their sprouts through the ground and Public Utilities employees prepare the water distribution system for the upcoming high water demand season.  With warming temperatures, summer is not far away.

During the winter months, deep wells are taken out of service and winterized. April is the month to prepare them to be placed back into service.  Twenty-eight wells have to be taken out of mothballs each spring and prepared for service.  In addition to the wells, maintenance is performed on the system pump stations. There are over 80 different pumps located within the distribution system. Both the pumps and electrical motor control centers are checked and exercised.   Elevation change within the water distribution system requires booster pumps to lift water to the higher elevations of the system. The elevation change is from 4,200 feet at the valley floor to 5,800 feet above sea level at the high benches. Dependable water service to the higher zones requires well-operated and maintained pumping facilities. 

Typical Pump Station

Because of Salt Lake City’s climate and local watering customs, a large volume of water is consumed for lawn and garden irrigation. Approximately 50 percent of the annual water delivered into the water distribution system is used for this purpose. The Salt Lake valley receives about 16-inches of precipitation at the valley floor with very little of this during the summer months when tempatures can be expected to reach 100 degrees. This places a large demand on the system during the summer months. The maximum daily demand is over 200 million gallons per day. Salt Lake City’s maximum day to average day flow ratio is 2.5, nearly 183 percent higher than most eastern cities within the United States.  In order to meet this wide variation in demand, large conduits convey treated water from various treatment plants. Wells strategically located within the distribution system provide pressure and volume to meet localized water supply demand. 

Operator Scott Blanton turns a valve to flush a well in preparation for operation.

Bob Wallin, Water Distribution System Manager, has gone through the spring ritual for 20 years.  According to Wallin, the spring startup period is important to successfully provide good service during the high demand period. He notes, “Thoroughly checking out the equipment is key to dependable water service when the summer heat turns on.” He adds, “Preventative maintenance goes a long way towards keeping the equipment going under stress.” The electricians check the current and voltage under operating conditions and the pump repair crew checks the mechanical equipment for noises or vibrations.  About 15 employees are assigned to this task during the spring months.

Kim Keller, laboratory microbiologist conducts bacteria tests to determine if water meets drinking water standards.

The process of getting the wells ready for operation includes testing the equipment, flushing the well for 24 hours and taking bacteriological samples to make sure the water meets drinking water standards.  Once the work is completed and the bacteriological results have cleared, the well is ready for use. The distribution operations personnel put the source on the “ready list” indicating that as demand on the system increases, the well is ready for service.

Depending on the year, wells provide between 10 and 15  percent of the annual water supply.  

With improving weather conditions, Public Utilities employees start flushing the distribution system through over 8,000 fire hydrants connected to the 135 square mile water distribution system within Salt Lake County.  Flushing the system accomplishes two important water utility functions. First it exercises the fire hydrants, and second it keeps the water system clean.  Flushing dead end mains through flush valves avoids water quality problems in areas that are not totally gridded.

System flushing ensures that water quality is maintained in the water distribution system to the customers tap.

Salt Lake City, located adjacent to the Wasatch Mountains experiences four distinct seasons. Spring brings us out of the cold winter months and prepares us for the hot summer months. Fall completes the seasonal cycle.  Public Utilities operates and maintains its water system according to the seasons. The hot weather is on its way, and the water system will be ready to serve our customers.  

Questions regarding this can be e-mailed to: bob.wallin@ci.slc.ut.us