The Hedgesville water district in the eastern panhandle of West Virginia recently suffered a major water leak that drained away approximately 100 gallons a minute during one of the worst droughts the area had seen in years.
Hedgesville is approximately 100 miles west of Baltimore, MD, and was included in an officially designated drought area last summer. The district, with 1,300 customers, has its own production facility but also purchases water from the nearby Opequon Public Service District (OPSD).
Late in July, staff became aware of a developing problem. Over the course of a seven-day period they noted that their production plant pumps were running longer than normal, yet the districts two water storage tanks were unable to reach their operating limits. Simultaneously, they recorded an increase in purchased water.
Coincidentally, the district had to isolate a section of the distribution line between the two water towers to allow for an unrelated construction project. During this process, staff noticed that the pumps and the primary water tank level immediately returned to normal operating conditions.
By continuing to isolate along the distribution line, the staff was able to establish normal operating conditions with the second water tank level. They concluded that there was a significant leak somewhere between the districts source of purchased water and approximately 3,000 feet of distribution main. By isolating the line, they determined the line was losing about 100 gallons a minute, or nearly 150,000 gallons a day.
The district had a 10-inch diameter asbestos concrete pipe with joints every 13 feet in the affected area. The only method the staff had was using a ground microphone. They began listening at the obvious access points and surveying at 13-foot intervals.
Taylor J. Whittington, General Manager, contacted Schonstedt Instrument Company to provide a leak survey of the area. On Aug. 10, 1999, Mike Curtis and Bill Wright from Schonstedt met with Whittington at the suspect area.
They established where the access points of valves were located on the pipes in question and individually performed leak detection on each successive length of pipe. They at first used a Water Hound leak noise correlator in survey mode to get a basic idea of where the leak was. The first three survey correlations indicated there was leak noise in one consistent direction.
As the team continued to move the sensors in that direction, they were faced with the longest distance between the available access points of 1,080 feet. After the sensors were in place the correlator indicated a strong point of leak location. Staff used a ground microphone to listen at the indicated position and heard faint noises. The Schonstedt people moved one of the sensors to a newly exposed pipe section, inputted the necessary data, revised the distance and produced a result that was 25 feet away from the original indication.
Staff listened to the ground microphone at the new position and could not distinguish the loudest source of noise. They decided to excavate at the position indicated by the Water Hound and were at first discouraged by a lack of wet soil. They did not encounter any moisture until the top of the pipe was exposed. As the crew began to uncover the pipe water filled the excavation site as fast as their 200 gpm pump could operate. They isolated the section of pipe, allowed the pipe to drain and found the leak was a complete radial break of the pipe. The damage was a result of the pipe settling atop a very large rock (fulcrum point) and the weight of the pipe on each side of the rock causing the pipe to break.
An adjacent utility, the Berkley County PSD, helped repair the leak.
"Since this occurrence, OPSD made arrangements with Schonstedt to lease a Water Hound over a period of several years, avoiding the financial impact on a single years budget," Whittington said. "OPSD will provide our local communities with leak detection services and we all will benefit by working together."
