When you get up in the morning, you rely on certain necessities to get your day started. One of the most important—in fact, life depends on it—is safe, reliable and clean water being supplied to your home. Unlike much of the critical infrastructure we depend on in our lives today, the system providing that “all-so-critical water” is pretty much “out of sight, out of mind.” That is, at least, until the water stops flowing from the faucet during your morning shower or from the hydrant when firefighters try to extinguish a fire.
So what can be done to assure water systems are being maintained to provide a reliable supply to homes, businesses, institutions and fire protection systems? And are we enlisting adequate planning strategies to assure our systems are reliable?
Our local water systems date back to the 1800s, with multiple system expansions being constructed as the population increased. In most systems, a multitude of tasks have been undertaken over the years to provide reliable water service to customers. Currently, many system operators utilize the latest technologies available to keep quality water flowing from your faucets. The process begins with proper planning.
Planning is paramount for providing quality water to your faucet in a reliable manner. This planning is also an ongoing process and an evolving science. Today, planning involves elaborate computer models and the use of Geographic Information System (GIS) software to properly identify the water distribution system components that require maintenance or replacement on a timely basis and to better predict how to more efficiently operate the system components.
The latest hydraulic modeling software is being used by many water utilities to evaluate all components of the water system, including pumping systems, storage tanks and water mains. The computer model is created and calibrated to accurately duplicate the operating characteristics of the water system. This model provides valuable information on the capacities, pressures and water quality within the system during periods of average water use, as well as periods of maximum use. Scenarios that take the water system to extreme operating conditions are developed in an effort to identify areas of the system that are susceptible to failure. The resulting data is compiled and system improvements are identified to enhance the system’s reliability and quality of water provided to the customers. The computer model is also capable of simulating varying operating conditions within the system, providing data for use in reducing electrical costs for pumping systems.
In conjunction with the hydraulic computer model, GIS software is being used to assemble data that has potential impact on the reliability of the system. Data collected and analyzed includes:
• Water leak information
• Water pipe age
• Water pipe type (material of construction)
• Soil types (corrosivity and shrinkage/expansion characteristics)
• Size of pipe
• Water pressure
• Critical nature of the pipe within the system.
The GIS database is utilized to predict which water main segments are in the greatest need of replacement, at greatest risk of leakage or would result in the greatest loss to the system if pipe failure occurred. System maps are generated to graphically display a prioritization of water main segments for replacement based on the data collected and evaluated.
An added benefit of these technologies is the ability to simulate emergency situations. The computer-generated model allows the operator to provide an effective response when mains break or power fails to critical systems. The model can be used to determine how to best isolate broken mains to keep the maximum amount of the system in operation until the main is repaired. The model can also determine which areas of the system will be impacted first when major power failures do occur, and how to modify the system operation to maximize the use of the available water in system storage facilities.
Water Main Replacement Program
A water main replacement program is based on the hydraulic computer model results, the GIS database prioritization and discussions with distribution system maintenance staff. The typical multi-year program includes replacement of water mains with larger-diameter pipes where appropriate, looping of “dead end” mains to improve water quality and reliability of service, and installation of replacement mains in places where existing pipes are at the end of their useful life or have experienced recurring failures.
Utility operators prepare annual capital budgets that include water main replacement costs. These costs are factored into customer water rates. As infrastructure ages, replacement costs will continue to be incurred. Unless state or federal grant programs are implemented, water rates will continue to fund water main replacement projects. Use of current technology for planning these improvements assures customers that their rates are being used to fund projects in the most efficient manner possible. IBI