Tracking Non-Revenue Water Loss with GIS

Mapping and asset management prove highly beneficial

Credit: BENTLEY SYSTEMS
SITEOPS, a conceptual design application, integrated with Bentley's ContextCapture for modeling helps convey design intent.

The White House Utility District in Southern Tennessee embarked on a water loss reduction program in 2012 in collaboration with Esri, a geographic mapping and software development company. To date, the utility has saved roughly $500,000 through eliminating water loss and reducing manpower hours.

At an Esri Users Group conference in 2015, and recently in a direct phone conversation, Carl Alexander, the GIS director for the White House Utility District, and Pat Herrell, the utility’s district engineer, discussed the work while acknowledging that water loss has traditionally been a problem with all water utilities.

Alexander says the utility adopted an Esri platform in 2012 with geographic information system (GIS) tracking, but it was used by just a few departments to deal with outdated equipment, business processes, software, and integration. There was very little real-time GIS information available on that platform.

Alexander described how the department realized it needed a new approach to how it did business. Therefore, it partnered with Esri and held workshops with them and utility staff. They discussed the needs and wants of the staff and adopted a new GIS platform. Now every employee has access to GIS, says Alexander. Over the 18 months leading up to 2015, 300 maps and apps and dashboards were created in collaboration with Esri. About another 100 maps and apps have been created since then, Alexander says.

At the time, non-revenue water loss was at 32%—meaning 32% of the water being treated and pumped into the distribution system was not being delivered to customers. Herrell says non-revenue water loss is now down to about 27% or 28%, and the utility is continuing to work at reducing the number further.

Herrell, described the White House Utility District as having a 1,500-square kilometer service area with 34,000 meter connections plus one wholesale company with another 3,500 connections.

In collaboration with Esri, the utility broke the service area into district metered areas (DMAs) using low night time flows to focus on specific areas. Submeters were not installed, but instead, Herrell says each DMA was split into sub-DMAs by opening and closing valves.

Herrell says leak loggers—tracking devices that pull out data on water loss from main breaks and leaks—are next used by field crews to identify sounds where ArcGIS indicates there should be a leak. Leak logger results are reported in ArcGIS where they are visible and understandable.

To aid communication rather than using numbers and tables, maps are colored to identify priority areas. Green indicates a trouble-free area, then colors move from yellow, to orange, to red, which represents the most troubled area.

An isolation trace application is now used to identify unplanned water outages (as opposed to non-revenue leaks). The operator specifies the location of a main break in ArcGIS and lets staff know how many valves need to be closed, what hydrants need to be taken out of service, and what customers need to be notified of water shutoffs. It allows customers to open up outage apps on their smart phones, says Harrell.

Alexander says that by using GIS “we modernized the utility.” Knowing what water pressure should be at all locations, GIS gives answers through ArcGIS. It allows staff to identify problems when customers call.

Alexander and Herrin are convinced of the value ArcGIS and GIS mapping has brought to the utility. It had saved $250,000 as of 2015, and saved another $200,000 in 2016. Furthermore, they’ve seen manpower savings of over $100,000. A water bond has been postponed for several years as a result. Still, Herrell says there is much work to be done in identifying non-revenue water loss, and Esri continues as a collaborator.

WHAT OTHER WATER UTILITIES ARE DOING
The Philadelphia Water Department in Pennsylvania was the first utility to employ the American Water Works Association (AWWA) water audit methodology on an annual basis. The utility installed an automatic meter reading system in 1999 and constructed full-scale DMAs with advanced pressure management. The department also uses acoustic leak detection sensors inside of large-diameter transmission pipelines to accurately detect leaks flowing at very low volumes.

As a result of these efforts, the Philadelphia Water Department has cut its non-revenue water loss by one-third since the beginning of the utility’s water loss control efforts.

PHOTOS: BENTLEY SYSTEMS
Visual reports can be created as models to send from offices to the field to improve project coordination.

Birmingham Water Works in Alabama has had a non-revenue water management program for over a decade according to the AWWA. It has over 4,000 miles of water mains that traverse many hills and valleys. This requires that the system be divided into many pressure zones with very high water pressure in much of the system. The utility has sectored the system into DMAs to monitor flows, manage system pressures, and identify leakage with portable acoustic noise loggers and location-pinpointing via correlating equipment. It also uses its SCADA system to compare with metered consumption to determine water loss in each pressure zone.

The Birmingham utility also uses a variety of production flow meters to measure bulk supply and flows into the DMAs and other zones. Customer meters are tested on an ongoing basis by in-house staff with bench test equipment and truck-mounted testing equipment. This effort has resulted in a relatively high overall customer meter accuracy.

St. Johns County Water Utilities in coastal northeast Florida has been using Azteca Systems’ Cityworks Asset Management tool along with Esri’s ArcGIS map services to manage its assets and streamline capital and development projects. This work is described in a September 2016 Water Efficiency project profile, written by Tom Tibbitts, the utility’s information systems coordinator.

WaterGEMS, WaterCAD, and HAMMER Advance modeling improves handling and display of customer service laterals and meters.

GIS TRACKING
A GIS creates maps of the physical world that allow users to visualize, analyze, and interpret data to understand relationships, patterns, and trends. Organizations of all sizes in almost all industries use it. Utilities are using it for asset management and, in particular, to search for non-revenue water leaks.

GIS mapping has been around since the 1980s and two companies dominate the field. Esri, headquartered in Redlands, CA, has been in business since 1969. A leader in GIS mapping, Esri developed ArcGIS, an analytic platform that provides tools for mapping and spatial analytics software to allow utilities to maintain comprehensive water, sewer, and stormwater records. It allows utilities to coordinate and plan capital projects and improve the operations of their networks. ArcGIS helps utilities to respond to leaks, reduce water loss, optimize fieldwork, and communicate with customers, according to Esri.

Azteca Systems, Inc. headquartered in Sandy, UT, began as a consulting firm that delivered GIS mapping support to US Federal agencies. Building on that work, it has been helping public works agencies to understand and implement GIS in their organizations since 1986.

Azteca expanded its services when it created Cityworks in 1996. Cityworks is a GIS-centric asset management system integrated with Esri’s GIS technology. Further, Azteca says it is focused on the development of GIS-centric software applications and can provide complete implementation, integration, data conversion, and process review as well as re-engineering, education, and ongoing maintenance for Cityworks customers.

In an interview about water conservation, Mark Nelson, a consultant with Jones Edmunds & Associates who works with Azteca, says Cityworks can track the costs associated with labor, material, and equipment used to respond to service requests. For example, on the non-revenue water side, meters can start to wear out, produce inaccurate readings over time, and eventually stop operating. The solution is to include the meters, with their ages, in the Cityworks software. If the meter is trending lower in an older house, that suggests that it needs to be serviced or replaced.

Leak detection service provided by contractors or a utility’s own resources can feed the results—the number of leaks found—into the software, a service request can be dispatched to the appropriate staff or investigation and prioritized. “This reduces time and increases accountability,” says Nelson.

As water demand goes down, leaks become a higher percentage of the water service. Brent Wilson, sales manager at Azteca, says detection becomes critical at this point. “Local governments and utilities have to do more work with fewer resources and the Cityworks software has given us better tools to find the leaks,” he says. “Our goal is to mitigate the losses and manage the repairs,” adds Nelson.

ASSET MANAGEMENT PLATFORMS
There are a number of companies integrating GIS tracking into their asset management platforms and two are profiled here.

Geospatial Corporation, headquartered in Sarver, PA, was founded in 2007 to serve all pipeline sectors. It specializes in underground infrastructure location, infrastructure mapping, and GIS data collection and management. Its GeoUnderground is a proprietary, cloud-based, 3-D mobile GIS mapping platform developed on the Google Maps Engine and Google Maps API. It collects the infrastructure data, processes it, and digitally stores and maintains the data for easy access by authorized users. The buried pipelines and geo-referenced photos and videos can be viewed from a laptop, phone,
or tablet.

Credit: HARRELL; PAT A.; WHITE HOUSE UTILITY DISTRICT
On this district metered area dashboard, red indicates excessive leaking requiring field response. By displaying asset information on interactive maps, decision makers prioritize projects based on data-driven interpretations of the spatially enabled data.

Wachs Water Service specializes in providing water distribution system solutions that improve the efficiency and effectiveness of water networks. By using advanced geospatial positioning tools, such as Trimble handheld GPS units and GIS software, the company can assess the information and physical conditions of valves and hydrants, upload the digital information to a GIS database and computerized maintenance management software work order system. This makes maintenance and management efficient and cost effective.

By knowing the exact location and condition of all valves, a utility then has an accurate picture of its distribution system assets assuring that valves are accessible for utility crews, faster shutdown is enabled during a water main break, damage to buried infrastructure is limited, and the area and number of residents affected by main breaks is reduced.

According to Ryan McKeon, vice president of operations at Wachs Water Service, the company “utilize[s] traditional ultrasonic listening equipment for surveying, off-the-shelf correlating equipment for pinpointing and Esri’s ArcGIS Collector tool for streamlined comprehensive and real-time data capture. We also use a business intelligence (BI) tool on the back end for quality control and performance management.”

DMAS AND PRESSURE MANAGEMENT
Bentley Corporation, headquartered in Exton, PA, has an international staff of 3,000 in over 50 countries. Founded in 1984, Bentley describes itself as “a software development company that supports professionals who are responsible for creating and managing the world’s infrastructure, including roadways, bridges, airports, skyscrapers, industrial, and power plants as well as utility networks.”

In the water distribution area, Bentley has developed WaterGEMs, a hydraulic modeling software that covers all aspects of design and operation of a water system. It can be integrated with the utility’s GIS to facilitate the construction of the model and display the hydraulic model results according to Dr. Thomas Walski, senior product manager at Bentley

Greg Herrin, director of project management, says a GIS is sometimes referred to as a model of a distribution system, but its function is different than a hydraulic model. “A GIS model is concerned with the location and attributes of system components such as pipes, pumps, and tanks. However, a GIS cannot perform hydraulic calculations.”

Walski says leaks are just one aspect of non-revenue water loss. “When water pressure in your water system drops as water moves through a pipe, pressure is reduced as it goes downstream. We know where the pressure should drop at certain points in the system based on the hydraulic model and this is a sign that something is happening that is not expected. Several things could cause that. It could be leaks, or partially throttled valves, or unusual demand that day.”

An algorithm for each junction box tries to identify the place where potential leaks are located that matches the model of the real world, explains Walski. “We have optimization software in WaterGEMS that can move hypothetical leaks around the hydraulic model until the pressures in the model match those in the real data. This can indicate areas where leakage is likely and enables the utility to focus its leak and pinpoint efforts on areas that are the most likely to be fruitful. You then send a crew out there and they will look for closed valves” or follow up with a leak detection device.

With GIS you draw a map that shows 16-inch pipes with 1,200 gallons per minute running through it, Herrin says. A 4-inch pipe has 800 gallons per minute flowing through it. At the first location, the pressure is 47 psi, the second location has 56 psi. In addition to running the equations, you can also map those attributes and see it visually.” By overlaying that information with a GIS map, the location can be spotted. Coming together you produce a picture of the system, Walski says.

Walski says there are other aspects of this problem. A lot of leaks are too small to detect and utilities often turn to pressure management. This technique reduces the amount of water that leaks from the system. A potential caveat is that if pressure management is overdone, it can impact pressures and fire flow, reducing them to unacceptable levels.

To prevent this from occurring, WaterGEMS can be used to simulate the effects of pressure management before it is undertaken. Walski, says, “The alternative to testing a pressure management plan before it is implemented is to reduce pressure and wait for customer complaints. Responsible water utilities do not operate this way.”

DISTRICT METERED AREAS
One way that utilities manage their water usage is by creating DMAs. “With DMAs you break the water system into smaller pieces and you meter the water with submeters, explains Walski. Establishing DMAs enables the utility to monitor consumption in a controlled area. If consumption suddenly increases without a known cause or if it doesn’t drop to expected levels during off-peak hours, a new leak is often suspected.

“Laying out the DMAs is not a trivial task,” says Walski. It often involves closing isolation valves to force flow through meters. If too many valves are closed, pressures and fire flows can be adversely affected. This is where a hydraulic model is valuable. Before making any changes to the system, the behavior of the system before and after DMA creation can be simulated with the model, and problems can be prevented, rather than causing headaches after the DMA is implemented, he explains. “With a hydraulic model, the engineers and operators can break the system into DMAs that are ideally sized and not have adverse side effects.”

Herrin cautions, “You don’t want to limit your system so that it has a negative impact on the service you provide. The water utility wants to provide enough water at adequate pressures with good water quality to their customers. Managing the DMAs helps make sure you do those things and that you’re still achieving your goals but doing it in a way that you’re controlling the pressures to not spill more water than you need to through those hundreds of tiny leaks that you’d never find. The system should produce enough water at adequate pressure and DMAs can manage that.”

Credit: BENTLEY SYSTEMS
Each district metered area has its own color. The yellow links are the pipes in which a flow meter would be installed.

DMAs originated in Europe, says Walski, where they are very popular. Herrin explains these applications have been widely used outside North America where there are more serious non-revenue water problems. Water systems in Europe are a lot older and have historically had bigger leakage problems and they were more aggressive about pursuing DMAs. In India, water loss may be as much as 60% and in most US systems, non-revenue water loss is about 10% to 20% of system production. It is a concern everywhere he says.

“DMAs are now being implemented by more and more US utilities and our tools are used to help plan them,” says Walski. They were first used for water audits and secondarily used for pressure management, but that trend is being reversed.

AWWA ARGUES FOR WATER AUDITS
There are as many ways to detect water loss as there are detection technologies, some old and well proven. In the case of non-revenue water loss, which can overwhelm utilities with its commonness, technologies such as GIS mapping and asset management software strategies can prove to be a financial lifesaver.

Credit: HARRELL; PAT A.; WHITE HOUSE UTILITY DISTRICT
Leak loggers provide the final key to pinpointing underground leak locations. They allow the utility to plan the placement of leak listening devices, manage information reported by the devices, and be notified when a leak is reported.

The AWWA released a white paper in 2016 on “The State of Water Loss Control in Drinking Water Utilities.” In it, the organization makes the point that “all drinking water utilities have water losses [but] that the extent varies from system to system.” If utilities fail to account for or audit their supplies to quantify the losses, paying customers ultimately bear the financial burden of the utility’s inefficiencies.

AWWA reported in the white paper that an assessment of validated water audit data from 2013 for 246 water utilities found that the utilities collectively incurred losses totaling $151 million in uncaptured revenue for the year. In addition, system leakage produced over $77 million of excessive treatment and pumping expenses.

Leakage represents a waste of water and energy resources when it is treated but not delivered to a customer, and could ultimately result in limits being placed on new commercial or residential development in water-short regions if supplies are constrained, says the AWWA.

We think of non-revenue water (NRW) as water that disappears in the distribution system and is never delivered to customers. The AWWA defines it as “the volume utilities lose from their water supply infrastructure.” This includes “the sum of unbilled authorized consumption, apparent losses, and real losses through all types of leaks, breaks, and overflows of mains, distribution reservoirs, and service connections up to customer metering. The value can also be derived by calculating the difference between System Input Volume and Billed Authorized Consumption.”

Tracking water leaks should always begin with a water audit. AWWA recommends that all utilities complete water audits annually, measuring water supplied to customers but also water lost. The water audit involves reviewing records and data “that traces the flow of water from its source, through the treatment process, into the water distribution system and delivered to customer properties.” It also tracks costs “and calculates a variety of performance indicators to assess the efficiency of the water utility.”

AWWA has created a water audit methodology and is embodied in the AWWA guidance manual, M36, “Water Audits and Loss Control Programs (4th Ed, 2016)” available on the organization’s website, www.awwa.org. It also offers a spreadsheet that utilities can use to compile a standardized water audit. AWWA also recommends that water utilities should have an effective asset management program that provides for water distribution system renewal and rehabilitation at appropriate time periods. WE_bug_web

Comments

Leave a Reply

Enter Your Log In Credentials
×