As part of the national Imagine a Day Without Water education and awareness day on October 21, 2020, OCWA—Central New York’s Water Authority—is highlighting some of its ongoing efforts to keep potable water flowing throughout our expansive distribution system.
OCWA’s water distribution system is spread over five counties (Onondaga, Oswego, Madison, Oneida and Cayuga) and consists of over 2,150 miles of water main, 13,500 hydrants, tens of thousands of valves, and over 103,000 meters. It is one of the 125 largest publicly owned water systems in the United States. Keeping this system running both safely and reliably, and in turn making sure our customers never have to Imagine a Day Without Water, is the #1 priority of our 175+ employees.
Given the size of our system and the extreme temperature fluctuations we experience in Central New York, it’s not surprising that we routinely experience water main breaks. The good news is that OCWA has a highly experienced and dedicated group of employees who monitor and maintain our water mains. We also reinvest heavily in upgrading our distribution system with new and refurbished mains each year.
In the event of a suspected leak, the first job of our maintenance crews is to identify the precise location of the leak. That may sound easy when water is visibly gushing out of the ground at the exact location of the break. But that’s rarely the case. Leaking water often travels underground and surfaces some distance from the main break. That’s when our leak detection crew rolls into action using their acoustical listening devices to pinpoint the location of the leak.
OCWA also proactively looks for leaks that haven’t yet surfaced. Our leak detection crew does this through a variety of methods, including performing leak detection “surveys” throughout our system on a regular basis. This entails methodically combing through neighborhood after neighborhood listening for leaks during early morning hours when traffic and outside noise is limited. They also “listen on” many of our hydrants every year to ensure they’re not leaking.
Our operations department also helps to detect leaks. Using OCWA’s automated Supervisory Control and Data Acquisition (SCADA) system, they can monitor for pressure and flow fluctuations which indicate leaks. They also periodically perform “loss of head” tests on our transmission mains. A device called a pito rod is inserted into the main to measure the differential between the upstream and downstream pressure. That information is then used to calibrate our venturi meters and evaluate the “carrying” capacity of the main. By understanding the degree of deterioration of a pipe based on age, scaling, etc., we can decide whether to clean and/or reline our mains to restore them to their original capacity.
A hydrant is a valved connection to a water main that extends above the ground surface. Water can be discharged at a high rate for the purpose of extinguishing fires, washing streets or flushing water mains (see Dead Ends section below). To avoid freezing, OCWA uses “dry barrel” hydrants which locate the control valve at the bottom of the hydrant below the frost line. OCWA hydrants require special tools to access/operate them.
In order to ensure that we have adequate water pressure and flow available to fight fires, OCWA routinely conducts “fire flow” testing throughout our system. The testing is conducted upon the request of customers, fire departments, schools or municipalities, or in areas considered at higher risk for fires. We also perform testing after we experience a single large (or multiple smaller) water main breaks in a particular area.
Fire flow testing involves opening hydrants and discharging between 600 to 1200 gallons of water per minute to simulate firefighting demand, all while keeping water pressure at a minimum of 20 psi to maintain service to our customers. The goal of the testing is to confirm that we are able to deliver water in sufficient quantity to permit fire departments to continue their critical job of protecting our community.
In addition to fire flow testing, we also have a dedicated hydrant maintenance program designed to ensure that our 13,500+ hydrants remain in good working order and available for fire protection. This entails having our distribution maintenance department inspect each hydrant annually, including removing the nozzles and operating the valves. We also have our summer crews systematically paint all our hydrants on a rotating three-year basis.
Valves are an often overlooked, but critically important, component of the OCWA distribution system. They are movable parts which control the volume, pressure and/or direction of flow of water through a pipe. In short, they hold back and release water as necessary.
There are many different types of valves used in the OCWA distribution system, including gate valves (used to isolate areas during repair work), butterfly valves (used to isolate flows), globe valves (normally used as on/off valves on smaller lines), ball valves (normally used for controlling or throttling flows), pressure regulating valves (reduce water pressure by cutting down the flow), check valves (backflow prevention device which permits flow in only one direction), air relief valves (remove air that collects at high spots in water lines), and vacuum relief valves.
The way a valve is opened and closed is very important to the distribution system. If the valve is opened too quickly, the high increase in pressure could result in stirring up of sediment in the line. On the other hand, if the valve is closed too rapidly, it can cause water hammer.
Valves in the OCWA system are operated either manually or electronically. Manual operations require the use of a “valve key.” The majority of valves in OCWA’s water distribution system are used to isolate areas for repair (gate or butterfly valves). Most valves are not operated frequently, which can cause failures when they are needed. As such, OCWA has a program of proactively exercising its valves on a routine basis.
In addition, OCWA maintains a detailed inventory of our valves, to include their precise locations. The data is maintained on our Geographic Information System (GIS), a computer system which allows us to capture, store, check, and overlay numerous data points at any given location in our system.
Water metering is the practice of measuring water use. Water meters measure the volume of water used by residential, commercial, industrial and wholesale customers that are supplied by OCWA. They are also used to determine flow through a particular portion of the system.
OCWA requires that individual meters be installed for each premise we serve and for each separate service connection to a premise. We have a meter change program in place to ensure both the customer and OCWA are receiving the most accurate registration of the water usage. Water meters can stop working as they age, which typically requires us to replace them every 15 years (or after 1 million gallons of consumption for commercial accounts). Industrial meters can be replaced as frequently as every year.
To ensure that our meters are reading accurately before they are distributed and used in our system, we have a dedicated meter repair/calibration department which uses the latest technology to rebuild, test and calibrate all our meters.
Given that OCWA’s distribution system is spread over five counties, 38 towns and 13 villages, we have a number of dead ends and areas of low water consumption. Because of this, and because some of our older cast iron pipes are more prone to scaling, it is necessary to take extra steps to ensure the water we supply to our customers is fresh, clear and free of any odors/ contaminants. Our robust flushing program is designed to take care of these issues.
Flushing is accomplished by fully opening a hydrant located near a dead end or in a low usage area. The hydrant is allowed to run for as long as it takes to refresh the water in the area. OCWA’s flushing program includes both automated flushers and manual operations. Each day our operations staff conducts flushing throughout our system. In addition, our night crew systematically flushes older areas of the distribution system by using high velocity water surges to scour the mains. The result is fewer customer complaints, meter repairs and service line blockages.