A pond near Pelham bore a telltale sheen, the odor of diesel hung in the air and a patch of vegetation had withered and died.

Workers who came upon this scene one morning reported it to authorities and later that day an effort began to repair a crack that was leaking diesel fuel from the Shelby County stretch of Colonial Pipeline Company's interstate pipeline into the ground.

The particulars may seem familiar, but only an estimated 127 gallons of fuel were released before the leak was fixed and the date was Feb. 1, 2016, more than seven months prior to Colonial's catastrophic Shelby County break earlier this month.

First discovered Sept. 9, the leak poured hundreds of thousands of gas into the remote William R. Ireland, Sr. Cahaba River Wildlife Management Area near the small community of Maylene, ultimately forcing a shutdown that disrupted gas distribution along much of the Eastern Seaboard for days.

The leak was the most consequential Colonial has sustained in years, but it is by no means the first, or even the worst disaster sustained by the company and its line connecting the oil fields of Houston to the harbors of New York and New Jersey.

In the first five months of this year alone, Colonial reported four separate incidents to the federal government in which the pipeline released a quantity of gasoline, diesel, fuel oil, kerosene and/or jet fuel into the Alabama environment, according to federal records.

Between 2010 and 2015, the company made only six such reports to the U.S. Pipeline and Hazardous Materials Safety Administration (PHMSA.) In other words, the company has gone from reporting an average of one Alabama incident per year over the last six years to at least five in the first nine months of 2016. Nationwide, the company filed 125 incident reports with PHMSA between April 23, 2010 and May 4, 2016, PHMSA records show.

A Colonial spokesman sent AL.com a brief emailed statement in response to questions about the company's history of pipeline incidents.

"Colonial Pipeline has robust system integrity, inspection and maintenance programs that meet or exceed all federal regulatory requirements," the statement read. "We take these matters very seriously, and we strive to achieve zero-spill operating performance, which is why we invest heavily in safety and system integrity measures every year."

Darius Kirkwood, spokesman for PHMSA, says the agency is investigating what caused this month's pipeline break, emphasizing that the investigation is ongoing and that the agency has not yet made a determination about its cause.

Pipeline breaks can happen for any number of reasons, from drilling accidents to a line forming a weak spot over time that eventually turns into a crack.

"Sometimes issues that are discovered in the course of an inspection may be the operators' fault, sometimes it isn't," Kirkwood said.

"If we determine that an operator has potentially committed violations of pipeline safety regulations then we will issue a notice of proposed violation. We can assess civil penalties - of course we've got our limits there."

Colonial is no stranger to regulators. In 2003 it agreed to spend at least $30 million on upgrades to the pipeline's environmental protection measures and pay the U.S. Environmental Protection Agency (EPA) $34 million, breaking the record for the largest civil penalty in the agency's history.

The settlement resolved seven charges that Colonial had violated the Clean Water Act in five states, according to an EPA statement announcing the settlement

"The government maintained that pipeline corrosion, mechanical damage, and operator error in seven recent spills resulted in the release of approximately 1.45 million gallons of oil and other petroleum products into the environment, including numerous rivers, streams, and wetlands," the EPA statement read.

In one 1996 incident, a break in a segment of the pipeline that the company was aware was a weak spot spilled nearly a million gallons of diesel fuel into a South Carolina river, killing thousands of animals and ravaging the nearby environment for years. The company ended up paying out $13 million to area landowners and the state in association with that break, according to The Greenville News.

Following the disaster, Colonial boosted its environmental protection and pipeline integrity programs in moves that still echo to this day, company spokesman Steve Baker told the newspaper in June.

"Even today we still kind of point back to that as the day that things changed," Baker said.

The Colonial statement to AL.com about the most recent Shelby County leak emphasized that the company is dedicated to avoiding spills and committed to being accountable when they do take place.

"When incidents do occur, we investigate and determine the cause alongside government regulators, and take corrective actions based on lessons learned to minimize the likelihood of similar events happening again in the future," the statement said.

Brigham McCown, the first PHMSA administrator and current chairman of the Washington, D.C.-based nonprofit Alliance for Innovation and Infrastructure, told AL.com last week that the company still experiences "small leaks," but that they are largely limited to minor spillage caused in pumping facilities.

"My experience with Colonial is that they generally have been far above average when it comes to other operators," he said. "Small leaks typically occur not in the pipes themselves but in the facilities."

But in Alabama, three of the five Colonial leaks so far this year - including the major one in Shelby County earlier this month - have been caused by cracks in the company's more than 5,000-mile-long pipeline.

The company filed more incident reports each successive year between 2013 and 2015, when Colonial filed 28 such reports, its highest tally since 2009, according to PHMSA records.

And the pipeline operator's environmental protection and integrity management practices were not enough to prevent the break that caused the governors of Alabama and Georgia to declare states of emergency earlier this month.

If it turns out that Colonial again violated EPA regulations in connection with the Shelby County break, it could face another round of harsh penalties, according to Kevin Eichinger, the EPA's on-scene coordinator for the spill.

"A group at EPA will do the investigation to determine if any additional penalties are warranted," he said. "That penalty component is not going to happen within the next month or so. The investigation takes some time."