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AMI system improves leak detection for New York City water utility
The New York City Department of Environmental Protection (DEP) is the largest public water utility in North America, serving more than 800,000 customers and 9 million residents. Receiving more than $3 billion each year from water and sewer customers, the utility’s operations and projects are funded by user fees.
DEP treats 1.3 billion gal of wastewater each day and distributes about 1 billion gal of clean drinking water throughout New York City’s five boroughs.
With such a large population and customer base, DEP has faced some challenges over the years.
“The manual collection of meter readings is inherently difficult in a large city like New York,” said Warren Liebold, director of metering and conservation for DEP.
New York City’s water system developed over many years and serves a varied population of people and buildings. The city faced a high rate of estimated bills and some flat-rate billing, as well as a decrease in the amount of water consumed due to aggressive conservation programs, despite an increasing population.
Before installing an advanced metering infrastructure (AMI) system, 15% to 17% of the city’s water bills were estimated based on past actual use. These circumstances did little to encourage some residents to conserve water, as their quarterly bills were not necessarily based on actual consumption.
Despite a 7% increase in population since 1990, DEP saw a 25% decline in water distribution. The reduction in use was a direct result of a major toilet replacement program in the mid-1990s, more aggressive street leak detection and other conservation programs.
In an initial attempt to measure water end use, the city established a universal metering program in 1987, designed to transition from a flat rate billing system to a metered system for residential customers. Most non-residential customers had been metered for many years. Today, 98% of customers are on this metered system, with the remaining 2% in difficult-to-meter locations, according to DEP.
The estimated read rate resulted in bill challenges and appeals, a large correspondence load, inspections to obtain verified reads and other unproductive costs that did not contribute to good customer service. By 2005 it also was clear that DEP would need to plan for the eventual systematic replacement of many of the residential meters installed in the early years of the universal metering program. DEP saw this as an opportunity to consider whether an AMI system was appropriate.
The city issued a request for proposals in May 2007, and the selection was narrowed down to two finalists by June of that year.
Finding the Solution
In a July-to-September 2007 pilot project, DEP installed the two products in different locations throughout the city to evaluate each one’s performance.
“We placed data receivers from the two finalists on top of two buildings: one in lower Manhattan across from City Hall and one in the northeast section of Brooklyn,” Liebold said. “The Brooklyn location was intended to replicate a typical New York environment, whereas the lower Manhattan location was designed to represent a difficult location from a radio reception perspective.” DEP then installed 200 AMI transmitters from each finalist on meters in each area, for a total of 800.
By September, Aclara’s STAR Network system was deemed the preferred product. While both systems performed similarly in exterior applications and when located within a 1/2-mile from the meters, the Aclara system performed better when the transmitters were mounted indoors or at a greater distance from the receiver. DEP determined that this system would require fewer rooftop receivers and could better accommodate indoor placement.
Installing the System
The contract was awarded to Aclara in May 2008, and installation of the STAR Network data collector units (DCUs) began in August. By March 2012, the system’s installation—including mostly new meters and corresponding meter transmission units (MTUs)—was 95% complete.
MTUs are devices attached to the meters, which remotely transmit meter readings to various DCUs installed around the city. The DCUs then send the information directly to the utility through Ethernet connections to the city’s NYCWiN wireless system.
During installation, the city was divided into 12 contract areas. Queens was divided into four sections, Brooklyn into three, Manhattan and the Bronx into two each, and Staten Island encompassed one. The areas were then divided into zip codes and contractors began installation in one or two zip codes at a time.
As installation progressed, data had to be synchronized with the STAR software to associate each MTU with its corresponding meter and account. New AMI-ready meters also had to be coordinated with DEP’s billing system.
Liebold described the installation process as “surprisingly smooth,” indicating that the contractors completed around 1,500 installations per day.
“We progressed at a healthy pace until we reached the 85% completion mark,” Liebold said. “At that point, friendly postcards had to be replaced with letters reminding customers of their obligation to have their meter replaced and an MTU installed.”
In total, DEP and its contractors successfully installed approximately 820,000 MTUs.
Since implementing the AMI system, DEP has experienced a number of service improvements.
Consumers are now more engaged with their water billing and consumption, with the addition of the My DEP Account service. The online portal allows customers to access their account information and sign up for leak notification e-mails.
Those who sign up for the leak notification service will receive an e-mail when their property uses water that is above their typical consumption pattern. For small properties, DEP defines this as triple the rate of typical consumption for five days. Owners of large properties can customize the percentage increase and period of time by which excessive water use is measured.
The system provides DEP with data that include daily water usage over the course of a month or a week, and hourly consumption patterns.
The utility is able to track system performance, as it receives reports indicating the number of meter readings that were missed or read as zero to detect and correct any AMI problems across the entire system.
DEP staff uses the BCS H2O Stats application to view citywide water consumption in real time. Staff is able to sort the data by borough, building class and zip code, and view daily, weekly or monthly data.
The system also generates reports that help the utility identify backflow or other meter installation issues.
The percentage of estimated billing readings has dropped 71% since 2010. Now only 4.1% of bills are currently determined on an estimated billing system. Most of those customers are not yet on AMI.
As with any new system, there have been some challenges along the way.
“Our primary challenge has been developing a system to identify and track individual MTU problems,” Liebold said. While the problem rate for the system is only around 2%, DEP has developed a field installation tracking system (FITS) to identify problems, indicate actions taken by field staff and report the results. The FITS correlates the problems with the actions, allowing personnel to solve problems more efficiently.
New York City Local Law 84 requires large property owners to monitor and benchmark their electricity, fuel and water use. A bulk data extract application within the AMI system allows DEP to upload and report AMI data to the U.S. Environmental Protection Agency’s Web-based Portfolio Manager benchmarking tool to share consumption data.
The data also are being used in a current DEP metering project.
“We have recently been involved with a major large meter replacement project,” Liebold said. “And the AMI system has been essential in tracking the results of that effort by providing quick comparisons of ‘before’ and ‘after’ water use in a building.”
This average daily flow report enables DEP to quickly identify the progress of the project.
DEP also is using AMI data to identify registration losses by looking for month-to-month reductions in water use over the last two years. This process helps it identify failing large meters, particularly those more than five years old.
During Hurricane Sandy, only 12 of 350 DCUs lost power. Using data provided by the system, DEP was able to notify other New York City agencies of approximate evacuation rates and apartment buildings without water or power and identify large leaks in the system caused by the storm.
According to Liebold, deliberate redundancies helped keep the system functioning during the storm.
“The fact that the DCU design was aimed at almost all MTUs being heard by at least two DCUs resulted in a resilient system that helped us weather the storm,” Liebold said.
Overall, Liebold is pleased with the ways the new system has impacted DEP’s operations.
“Daily and hourly meter readings have dramatically changed our business operation. Customers and CSRs can see daily water use on the same screen. Customers almost always get bills based on actual reads and tens of thousands of them will get an alert if their consumption suddenly increases,” Liebold said. “Customers used to have to wait for at least three months—and sometimes longer—to learn about a leak. Apartment building and commercial building managers for whom water is a cost to be managed can compare buildings’ use and quantify costs in a way they could not in the past. We have better ways of targeting customers and meters with problems to be solved. It’s a game changer.”