Water pressure surges result when there is a sudden change in flow. These events, otherwise known as water hammers, can reduce the longevity of pipes, cause leaks or main breaks and jeopardize water quality. Regularly monitoring pressure can enable utilities to mitigate the frequency of pressure events while reducing operational costs.
1. Preventing Pipe Failure and Major Bursts
High fluctuations in pressure levels can put stress on pipes throughout the distribution system. Many utilities throughout the country deal with aging infrastructure. These events can put more strain on what is already frail.
Pressure variance can also cause leaks, and in more severe cases, main breaks. These events require the system to produce more water, increasing operational costs. Each year, there are an estimated 237,600 breaks in the U.S., amounting to 2.8 billion dollars in lost revenue (American Water Works Association).
2. Preserving Water Quality
Low-pressure surges can allow ground water to seep into pipes located below the water table. The sudden loss in pressure can also allow viruses and chemicals to seep in from soil. A drop in pressure below minimum standards can require utilities to issue “boil water” notices to protect public health.
A 2001 study tested 66 soil and water samples from 6 utilities located in 8 states. The study found 56 percent of the samples tested positive for viruses in either the soil or ground water (EPA). The viruses included enteroviruses, Norwalk and Hepatitis A, “providing clear evidence of fecal contamination immediately exterior to the pipe” (EPA).
3. Reducing Operational Costs
Pressure monitoring can help reduce energy costs, system maintenance and water leakage. The data can improve pump management, helping to reduce power use. Mitigating pressure variants can result in less water loss while lowering the potential for pipe fractures and main breaks. Limiting water loss results in less overall production, easing demands on system infrastructure.
Monitoring pressure can reduce the number of customer or developer complaints. This cuts back on the time and resources required to investigate and potentially fix issues.
4. Reduce the Frequency of Pressure Variants
Continual data collection can identify the impact of infrastructure failures and routine operational practices on pressure variants. System failures like valve closure, pipe fracture or pump stoppage disrupt flow and can result in a high- or low-pressure surge. Other procedures like pump start-up and shut-down and hydrant operations can also contribute to the problem.
Measuring effects of these practices on pressure levels can enable utilities fix the issue at its source, helping ensure positive customer experiences while mitigating all the other consequences tied to pressure variants.
Ongoing pressure monitoring of a distribution system, in December 2000, uncovered a power outage of 24 seconds at a pumping station resulted in a negative 4.4-psi (EPA). Deploying pressure recorders throughout the system allows utilities to study these events and make informed adjustments.
Pressure Monitoring Solutions
Pressure recorders can be placed on system mains, using a service saddle, or on a hydrant. Wireless recorders send data to a web server through cellular communications. Standard pressure loggers require data to be downloaded in the field.
Wireless pressure recoreders like the Trimble Telog PR-32iA (for water mains) and HPR-32iA (for hydrants) have the benefit of providing real-time data and alerts during high- or low-pressure events. The Trimble Telog recorder also store the wave form of pressure transients detected on the network.
Wireless recorders like the Trimble Telog 32-Series can also visualize data on a user-friendly map. Trimble Software uses GIS to display sensor data on a map of the distribution grid. Users can view pressure data at each location on the map, helping them zero-in on problem areas.
Collecting pressure data can be done through the long-term installment of a pressure recorder on a pipe or hydrant or through a short-term study. However the data is collected, it can be vital to preserving water quality, reducing leakage and non-revenue water (NRW) loss and lowering operational costs. The measurements provide insight into what can otherwise be an ambiguous problem for our industry.