NEW YORK (Reuters) - On a routine check of a surface coal mining facility in rural Alabama early this month, inspector Randall Aldridge first smelled gasoline. Then he saw dead plants and animals along a man-made pond that helps the region manage heavy rain.
The cause had nothing to do with a mine.
Aldridge happened upon a leak on the main fuel artery to the U.S. East Coast known as the Colonial Pipeline, in what turned out to be the company's largest gasoline spill in nearly 20 years.
Colonial Pipeline Co and its peers in the oil and gasoline transport sector, tout high-tech, complex leak detections systems that measure hydraulic data and count on overhead flights and other measures to ensure their pipelines work efficiently and safely.
But the fact these systems did not flag the Colonial Pipeline spill is not unique.
A Reuters review of U.S. federal records shows that sensitive technology designed to pick up possible spills is about as successful as a random member of the public like Aldridge finding it, despite efforts from pipeline operators.
In the past 20 months, Colonial has had eight pipeline spills across its 5,500-mile (8,851 km) fuel pipeline system. None of them were uncovered by the company's primary leak-detection system, according to federal data.
Colonial did not provide any explanation why the system did not detect any of the most recent leaks.
"Colonial Pipeline has robust system integrity, inspection and maintenance programs that meet or exceed all federal regulatory requirements," the company said in an emailed statement.
The issue stretches beyond Colonial. Over the last six years, there have been 466 incidents where a pipeline carrying crude oil or refined products has leaked. Of those, 105, or 22 percent, were detected by an advanced detection system, according to a Reuters analysis of U.S. Pipeline and Hazardous Materials Safety Administration (PHMSA) data.
The others were discovered in different ways, including 99 leaks found by the public.
Detection is critical because the earlier a leak is found, the less damage to the environment and the pipeline. In the 361 pipeline incidents that went undetected by internal systems since 2010, a total of 141,421 barrels of petroleum products spilled, totalling $1.2 billion in property damage, the data shows.
Pipeline safety is a hot-button issue since demand for new infrastructure picked up to move fuel coming from the U.S. shale boom. But there has been push-back. Most recently, in response to protests, the Obama Administration agreed to delay the completion of Energy Transfer Partners' s crude-oil Dakota Access Pipeline, citing concerns about a leak that could contaminate water supply.
Operators have turned to these detection systems to help ease concerns about leaks becoming big spills, lifting the total market size for these products to about $1.1 billion in 2015. Energy Transfer Partners which, for example, has said that it would use technology on the Dakota pipeline to detect leaks as small as 1 percent of its flow rate, or about 4,700 barrels, according to Reuters calculations.
The top suppliers of the most widely used leak detection system to oil and gasoline markets include Schneider Electric SE, Emerson Process Management, Yokogawa Electric Corp, Honeywell International Inc., and ABB Ltd, according to ARC Advisory Group.
"Pipeline leak detection is not a one dimensional problem and, in all cases, requires a multiple pronged approach for success," Mike Tankersley, director of pipeline simulation for Schneider Electric said.
Computational Pipeline Model (CPM) based technology for leak detection is most successful when combined with good infrastructure, a reliable monitoring system and efforts in the control room, he added.
Honeywell, Yokogawa, Emerson Process Management and ABB did not respond to requests for comment.
U.S. regulators declined to comment on the Colonial Pipeline failure to detect the leak because it is part of the ongoing investigation.
The U.S. Pipeline and Hazardous Materials Safety Administration published a congressionally-mandated report in 2012 that provided no recommendations, but did note that computerized detection of spills is uncommon. Pipeline operators utilize systems with varying degrees of sophistication amid a lack of broad-based regulations, according to the report.
Colonial's detection system, first deployed in the 1970s, has undergone several updates, the latest of which is underway and expected to be complete in 2018.
Pipelines rely on detailed inspections, corrosion prevention and public awareness campaigns. The most common leak detection method for pipeline operators is called the Supervisory Control And Data Acquisition (SCADA) system.
The SCADA system is the brain of the pipeline systems, using a series of sensors to track data such as pressure, flow rates, temperature, and whether valves are open or closed.
The information is then relayed to a control room, where trained operators are often required to distinguish between false alarms and real leaks.
The system's capability to detect drops in pressure and volumes and identify possible spills has driven pipeline companies to use it as their primary leak detection method. Some systems, however, have added the Computational Pipeline Monitoring System (CPM), whose main task is to detect leaks.
Since 2010, there have been 264 pipeline spills where a CPM was functioning at the time of the incident, federal data shows. The leaks were detected by the CPM 19 percent of the time, according to the data.
The section of pipeline involved in the recent Colonial Pipeline spill did not have a CPM.
The environmental assessment of ETP's controversial Dakota Access project notes that CPM will be one of nearly a dozen ways in which leaks will be detected.
Federal data shows the leak detection systems have caught small leaks and missed some of the largest. Six out of the largest 10 pipeline spills in the U.S. since 2010, all of which were as big or bigger than the Colonial spill, went undetected by the system.
Larger pipelines with multiple exit and entry points, such as the Colonial, make leak detection more complicated, experts say. The opposite can be true for shorter pipelines that serve fewer users and are better at detecting spills.
Colonial's September spill caused a near two-week partial shutdown that sent pump prices soaring in the U.S. southeast.
Preliminary reports show that the company's detection system showed no signs of a significant pressure loss, a key sign of a leak. An overhead flight on Sept. 7 - two days before the leak was discovered - also did not raise any red flags.
Additional reporting Liz Hampton in Houston; editing by David Gaffen and Edward Tobin