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On the Road with the Corps Army Experts Brave Hostile Habitat to Detect Water Leaks By Cynthia GreenwoodWhen two experts travel to Fort Hood Army Base to collect data from a new water leak detection system for the Army Corps of Engineers, they brace themselves for a bumpy ride. West Fort Hood is hilly and desolate, and ranchers are even permitted to graze cattle on this Central Texas scrubland where Apache and Kiowa Indian tribes once roamed. Occupying 217,337 acres between Austin and Waco, Fort Hood is the largest American Army base, and once laid claim to being the largest base in the free world before the Soviet Union dissolved. The base is unique, hosting two major divisions that include the 1st Cavalry Division—deployed to Iraq in 2004—and the celebrated 4th Infantry Division that captured Saddam Hussein in 2003. During a June 6 visit physicist John Carlyle and materials engineer Sean Morefield regretted not having a four-wheel drive. Carlyle's rented 2006 Chevrolet Impala was getting severely scratched and gouged by underbrush as he drove Morefield and a DoD reporter across dirt and juniper-covered swaths of west Fort Hood to inspect a series of sensors that monitor water leaks in the base potable water system. At Fort Hood, there are 328 miles of buried water lines that distribute potable water for the base. In 2005 Fort Hood used 2.176 billion gallons of water at a cost of $0.55 per thousand gallons. Carlyle conducted a leak detection survey that year and estimated that the base's water distribution system was fairly tight and leaked approximately 10 percent, explained Gary Goodman, an official in the Fort Hood Department of Public Works (DPW) environmental division. "This equates to approximately $119,720 in water loss annually," he said. Leaks from corrosion are common in these pipes. To repair a leak, it costs the Army $10,000-$50,000, because locating leak sources is time-consuming and the digging required is expensive. To solve the problem, the Corps of Engineers installed a new technology in July 2005 consisting of acoustic sensors that can detect the sounds of water leaks. The Army's Installation Management Agency and the Pentagon-based DoD Corrosion Policy and Oversight Office contributed $250,000 each to fund the project.
On a Journey to Find Data It takes an hour to drive to Fort Hood's north end from its southern tip at Highway 190. White-tailed deer and roadrunners roam parts of this 339 square-mile habitat covered by Ashe Juniper (referred to as ‘cedar' by the locals), mesquite, and live oak trees, as well as coyotes and foxes native to the region's rolling hills. Whenever he is en route to his Crawford ranch near here, President George W. Bush lands on Fort Hood's Robert Gray Army Airfield in Air Force One, preceded by an entourage of screaming C141 Starlifters carrying his motorcade. It was 11 a.m. and the temperature had already reached 97º F. At the journey's start, Carlyle rounded a curve on a dirt road about 50 yards away from an outpost where soldiers routinely conduct live tank-firing exercises. A deer darted across the road a few feet ahead. A Black Hawk circled above. "The deer are everywhere," Carlyle remarked, "And you better watch out for low-flying helicopters. Not to mention the tank shells being fired over the road," he said. Carlyle recalled that on previous visits, he and Morefield often shared the road with trucks carrying ammo. In the same vicinity, dry, yucca-covered pastures hide a network of underground ammunition bunkers dating back to the beginning of the cold war. Scattered amidst these bunkers is the seven-mile pipeline network Carlyle and Morefield are monitoring using permanent sensors. Detecting Water Leaks Acoustically
Because it is not yet feasible to outfit the entire base water pipe system with the sensors, Carlyle, Morefield, and Fort Hood DPW officials managed the installation of 25 permanent sensors to monitor leaks along a limited, 12-mile section of west Fort Hood. During our visit, both men worked to retrieve sensor data remotely using a handheld controller—called a patroller—that displayed acoustic readings (and the presence and severity of possible leaks) as they drove by. One of the patroller's best features, Morefield explained, is that it can pick up a sensor's signal from more than 6,600 feet away. "For the most part, they've worked really well," Carlyle said. Each sensor unit is buried 4 to 5 feet underground, inside a housing that holds a riser pipe connected to the water pipeline. The housing lid sits on the ground's surface. A communication unit sits above the riser pipe, and the leak sensor sits at the bottom of the same pipe. Three of the 25 sensors are equipped with cell phone antennae, enabling them to store 14 days worth of data. The data is automatically downloaded at 8 a.m. every Saturday onto a central computer inside the DPW office. On this particular visit, both engineers drove me around for a close-up view of various sensors while they collected the data. Located roughly 1,500 feet apart, some sensors were easy for us to find; others, though, lay hidden behind overgrown brush or beyond classified areas surrounded by cyclone fences topped by razor wire. "For routine collection, we never have to come into a secure area to read our data," said Carlyle. Morefield explained how the sensors communicate: "They wake up at 2 a.m. every morning. If they hear nothing, they report ‘no leak' and go back to sleep. If they do hear something, they wake up two more times, and if they hear a noise three consecutive times, they report a leak. They hold the data they've stored for 24 hours and repeat the sequence all over again." As they made the rounds, all 25 sensors appeared functional except for sensor #2, which would have to be replaced. In addition to malfunctioning, sensor #2 had also been encroached upon by a huge colony of honey bees that chose to build their hive inside its underground housing.
Morefield and Carlyle spent some time and personal risk ridding the equipment of the pests before continuing their patrol. "With this sensor system, we're saving water in a pretty hostile environment," Carlyle said. After they sprayed the few bees left that swarmed the sensor housing and got back in the car, we passed a distinctive pile of something resembling cat litter. It was the mound of a cow ant, a nearly extinct big black ant whose species is being overtaken by the more aggressive red ant, Carlyle noted. Saving the Army Millions Besides solving its problem with leaks, Fort Hood stands to gain a tremendous time-saving advantage in monitoring its sensors remotely. "We usually complete the whole patrol in 45 minutes using major roads," Carlyle said. There is also the potential to outfit a security vehicle with the patroller and retrieve sensor data at the same time, Morefield added. "Other cities have put the patroller on a city vehicle already driving around to retrieve data on a daily basis," he said. Morefield estimates that the acoustic leak detection system could save Fort Hood as much as $3.2 million over its lifetime. "With this system Fort Hood personnel can get leak sensor data any time they choose," Carlyle said. Editor's Note: Morefield is a research materials engineer with the Construction Engineering Research Lab (CERL) in Champaign, IL, a division of the Corps' Engineer Research and Development Center. Carlyle, of Carlyle Consulting in Yardley, PA, participated in this project under contract with CERL. |
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