Kokomo, Ind.'s wastewater department uses the Schonstedt XT512 locator several times a week, with a sonde, to precisely locate pipe made of vitreous clay and other nonmetallic materials.

Like many cities, , the Kokomo (Ind.) Wastewater Department struggled with maintaining buried infrastructure, mainly because locating utility assets hasn't been an exact science. science

“Typically, we'd do aboveground locates based on the city plat book,” says Sewer Maintenance Supervisor Tim Winchester. “We'd open the nearest manhole and start from there. The plat book wasn't always very accurate, and we couldn't say for sure how deep the line was.”

Though time-consuming, this was the department's preferred method over utility locators. Most locators are designed to read a current induced in metal pipes, cables, or tracer wires, making the technology ill-suited for Kokomo's unique situation. The city's 600 miles of pipeline, ranging from 8 to 18 inches in diameter, is mostly vitreous clay with no tracer wire. There are also 24-inch brick lines.

The department's locator was large and bulky. It required headphones; and even when using a sonde on a pushrod or hose, readings were only within about 2 feet. This slowed down maintenance and repairs even more because backhoe operators had to proceed with extreme caution so as not to hit lines.

Basically, it was just a hassle to use.


Winchester solved the department's challenges by purchasing the XT512 sonde and camera locator from Schonstedt Instrument Co.

Instead of relying on currents emitted in metal pipes or tracer wires, the XT512 reads the 50/60 Hz signal emitted by a 50/60 Hz source such as energized electrical power lines with sufficient load, as well as the 512 Hz signal emitted by sondes used with pushrod and tractor cameras. Since the department uses a sonde attached to a rodder hose that can be pushed up to 900 feet, the XT512 was an ideal choice.

Bulk and inconvenience was one reason the previous locator was rarely used, so ergonomics was a key factor. The XT512 is pistol gripped, fits in a side holster, and weighs 2.5 pounds. It also extends from 15.5 inches to 26 inches, an industry first that makes the locator easier to carry and have on hand when collapsed.

Most importantly, Winchester is impressed by his new locator's accuracy: “If the screen tells us that the pipe is 5 feet deep, we subtract the diameter and that's how deep it is. It's right on.”

His crews perform 25 to 30 locates a week, with only four or five of those done with the XT512. But when it is needed, it's invaluable. Pipes with a lot of flow, for example, call for accurate locating. When flow is high, it tends to obscure the invert depth at uphill and downhill manholes, making it hard to estimate depth or run levels. Uneven ground or sight lines obscured by brush or buildings have the same effect. Using the locator and sonde, crews can get an exact depth and horizontal location right at the area of concern.