utility maps need new help to work|[01/11/08]

More than $100,000 was spent in 2001 and 2002 modernizing Vicksburg’s maps with a state-of-the-art computer GIS system, but the utility lines they display were based on old water, gas and sewer maps that may not have been updated since 1985.

And with five years of subsequent changes to utility lines throughout the city that have not been entered into the computer system, the GIS utility maps are already antiquated.

City engineers now want to hire a contractor to bring the geographic information system up to date, which will involve locating and cataloging every gas and water meter in the city and identifying sewer and gas lines added in the last 20 years. The City of Vicksburg operates all three utilities and bills customers monthly through the Vicksburg Water & Gas Department.

A request for proposals seeking outside assistance to locate and index water mains, gas lines, meters and main valves will be issued once city supervisors have determined what information is needed.

“We are going to decide … what data needed to be collected, how it would be collected and who would be involved in collecting it accurately,” said engineer Donald Brooks.

Contracting is necessary because city utility workers already have their hands full.

“Our crews are tied up almost every day, if not every day, maintaining the system,” Brooks said.

Aerial photographic mapping of Vicksburg was first purchased in 1995 through Atlantic Aerial Surveys, now Optimal Geomatics. White circles were painted around manhole covers and other system features during that process.

In 2002, that data was used to create an electronic map of the city that incorporates zoning, property information, tax maps and utilities. The city contracted with Graphic Computer Technologies for $127,000 to develop the GIS.

But the utility lines mapping is only marginally useful without key data that was never compiled for input to the system, those familiar with the system said. City crews can use the maps to see where sewer, gas and water lines run, and where many of the main valves are, but this information is limited and mostly came from maps that predated the GIS system.

The intent, said strategic planning director Paul Rogers, was for the system to act as a reference for utilities workers and city crews, helping them to identify underground pipes that run close together and telling them what buildings would be affected by shutting them off.

“Once you get underneath the road, it can be like spaghetti. You know you are looking at a gas line, but you don’t know which one it is or what it connects to,” Rogers said.

New lines added since the GIS was set up have not been entered into the system, said public works director Bubba Rainer.

“You’re supposed to have somebody putting it on the map. That was never done,” Rainer said.

Determining the exact location and purpose of thousands of main valves throughout the city is one priority being discussed. Utility departments and other agencies for whom such information might one day be critical have no indexed reference for which areas are served by particular gas and water lines.

City crews rely on supervisors’ knowledge as to which lines affect which areas, Brooks said. Instead of the system, crews often rely on their own memories.

Pinpointing the exact location of underground pipes, determining their thickness for better identification, and finding each main valve and meter will likely be an expensive undertaking, though no one involved was ready to estimate how much the effort would cost.

Gas lines in Vicksburg will be studied first, because there is less information on them.

Having utilities supervisors collect the data would not be timely, Brooks said. “That’s not effective analysis. It’s not systematic … It’s a very complex program and it takes time to get it thoroughly mapped.”