A public water supply is designed to provide water for domestic needs and provide for public fire protection. There are three aspects to public fire protection.
The first and most visible are the fire hydrants along the streets. They are where the fire departments connect to the water supply system. Their location is generally selected by the local fire department. The spacing between the hydrants usually ranges from 500 to 1000 feet. SCWA maintains 34,500 public hydrants and 1,795 private ones. Each one of our hydrants is inspected for mechanical operation every ten months. SCWA has a staff of 7 hydrant mechanics that repair the hydrants when needed.
The ability of a fire hydrant to provide water to fight a fire is measured by a flow test. During the test, the static pressure, the volume of water discharged by the hydrant and the residual pressure are measured. The static pressure is the pressure in the system before the hydrant is opened. The volume of water discharged is the water flowing out of the hydrant in gallons per minute. The residual pressure is the pressure in the system while the water is being discharged from the hydrant. By performing engineering calculations, the volume of water available at different residual pressures can be determined. The industry standard for maximum hydrant performance is the flow available at a residual pressure of 20 psi. This is the minimum water system operating pressure allowed by the Department of Health.
These tests allow us to check on the strength of our fire protection across our system. SCWA routinely performs hundreds of flow tests throughout its system each year. The tests are triggered by extension of water mains to new areas, improvements, such as new mains or pumps, or other changes to the water supply system, as well as requests from customers, fire departments and design consultants.
The underground water mains are the second part of the fire protection system. They connect the fire hydrants to the pumping and booster stations that make up the water supply system. SCWA uses our own engineering staff to determine the appropriate size for the water mains. It allows only highly qualified contractors to install these mains. SCWA does not allow outside personnel to operate or repair our distribution system.
The third part is the water supply. This is the heart of the protection system. It provides the pressure and volume of water that is needed for domestic use and fire protection. Again, SCWA uses its own engineers to design the wells, booster pumps and tanks that make up the water supply system.
Through our Supervisory Control and Data Acquisition (SCADA) system, the pressure, flow and status of each of our 232 pump stations, 43 booster stations and 62 tanks are monitored at our Control Center in Bay Shore. There are personnel in the Control Center as well as on the road throughout our service area 24 hours per day, 7 days per week, 365 days per year. The water supply system is operated and maintained by SCWA's Production Control Department. It has a staff of 100 consisting of engineers, state certified water treatment operators, technicians, electricians and pump mechanics.
SCWA makes sure every fire hydrant operates properly, installs the proper size water mains and controls their use to make sure they are ready for use to fight a fire. However, the most important component is the water supply source. It is monitored and maintained around the clock to make absolutely certain that fire protection water is available at all times.