Mississippi city used geospatial information to improve water and sewer operations
Located in northwestern Mississippi, just across the border from Memphis, Tennessee, the city of Southaven is a suburban community that has experienced explosive growth. In the 10 years from 2000 to 2010, suburban expansion and the strong Memphis economy helped Southaven to grow from 29,000 to 49,000 residents. It is now Mississippi’s third largest city. Along with the growth came new and expanded infrastructure including roads, utilities, and recreational amenities.
As director of the Southaven Utilities Division, Humphrey oversees the operation and maintenance of the water and sewer system that serves roughly 45,000 people in the city’s 34 square miles. Humphrey has worked at the utilities division for more than 25 years and his long experience has given him intimate knowledge of the division’s assets and operations.
Water and sewer systems serving the new subdivisions connect to facilities and equipment that date back to the city’s incorporation in the 1980s. Humphrey knows the challenges of tracking decades of development and raised the idea of using geographic information systems (GIS) to help manage the information.
Humphrey knew that GIS could assist the city in two ways. First, Southaven would continue to ensure accurate, up-to-date data on its water and sewer facilities. Second, the information would be immediately available to people who need it, within and outside of the utilities division.
Once the mayor and the City Board of Alderman became aware of the benefits and decided to move forward with the project to develop the GIS platform, Southaven teamed with the U.S. Army Corps of Engineers (USACE) Memphis District. The two organizations defined a joint effort to produce a comprehensive study of the city’s water and sewer systems. In addition to helping to identify and mitigate any problems, data from the mapping work would be shared to develop hydraulic modeling of the water system. Along the way, it would transform the way in which Humphrey’s team worked.
The utilities division contracts much of the data collection to Civil-Link, a Southaven consulting engineering and surveying firm. Civil-Link deployed data collection teams equipped with Trimble R10 and Trimble R6 GNSS receivers to collect 3D positions on thousands of individual components of the water and sanitary sewer systems. Using feature libraries on their Trimble TSC3 controllers, the teams captured data on valves, meters, hydrants, manholes and pump stations.
In addition to locations, the field data includes information about the various components such as manhole depths, pipe sizes and open-left or open-right directions for valves. According to Civil-Link Managing Principal Dan Cordell, when the data collection is complete they will have collected more than 25,000 individual items. “The project is on schedule,” Cordell said. “Our field crews are happy with the Trimble equipment and can move very quickly.”
Using Trimble Access Services, Civil-Link crews send field data directly to the office for processing, quality control and transfer into Esri ArcMAP software. Civil-Link then developed a custom website for Southaven. Using smartphones or tablets, Southaven Utilities Division staff can log into the website to view maps and access information in the field at any time. “The guys absolutely love it,” Humphrey said. “Knowing all the valve locations lets us make sense of what is underground.”
Civil-Link uses RTK and Trimble VRSNow to measure the locations of most assets to 1-3 inches, and Humphrey wanted to utilize that precision. With the simple GPS receiver in a smartphone, a utilities maintenance crew can navigate to within a few feet of a water meter or manhole. But locating a valve buried by landscaping or in a flooded intersection needs better precision. To make it easier to find the mapped assets and keep the system information up-to-date, Humphrey invested in a Trimble GeoXH GNSS handheld and Trimble TerraSync software The Trimble GeoXH produces centimeter precision using corrections from a Trimble NetR8 GNSS Reference Station operating in the nearby town of Nesbit.
Owning the Trimble GeoXH has produced a quick payoff. In addition to quickly navigating to the already-mapped field assets, Humphrey’s technicians can gather new data for the GIS. They can also collect and check information to update features already in the database. To ensure consistency, Southaven crews collect information using feature library forms defined by Civil-Link. The standardized data streamlines the processes for quality control and transfer into the GIS.
The Trimble system has improved Southaven’s in-house productivity. Humphrey’s technicians are familiar with the territory and can collect information on difficult-to-find assets. “Rather than sending a technician with the Civil-Link crew, we can find assets ourselves and collect new data for the GIS in a single visit,” Humphreys said. “That provides efficiency by keeping Civil-Link busy in other parts of the city.”
Southaven’s Utilities Division is planning to share the benefits of its GIS and Trimble equipment. According to Civil-Link’s Dan Cordell, the final database will include roughly 2,200 manholes, 4,500 water valves and 18,000 water meters. That information has a variety of uses. The city’s fire department can utilize the information to direct crews to fire hydrants and provide information on the hydrant’s valves and flow rates. System analysts can use the comprehensive data to identify areas of inflow and infiltration into the sewers. The city’s operations and maintenance program requires all valves in the system to be operated on a regular basis, and the GIS allows the utilities team to identify the status of each valve. And the accurate position information is invaluable for the utility technicians who respond to 10 to 15 requests for utility field locations each day.
Humphrey expects rapid payback and long-term benefits from Southaven’s investment. “Knowing what you have and where it is in real time is invaluable,” he said. “We can easily share accurate information across departments and throughout the city.”