Waterford — George Purple smelled something.

A less keen sniffer than his might have been numbed by the exhaust fumes from the steady rush of cars on Route 85 and the stale odor of trapped air inside the underground tank holes he had just examined. But Purple’s handsome aquiline nose told him something was amiss at the Henny Penny gas station and convenience store he was inspecting Thursday.

“Nothing is more sensitive,” he said, tapping the side of his olfactory organ with his pointer finger.

Purple, wearing a blue polo shirt with the logo “DEEP Purple” — a shorthand version of his title as supervising environmental compliance specialist with the state Department of Energy and Environmental Protection — has been inspecting gas stations around the state since 1997.

But even with the sophisticated electronic monitors, data records and visual inspections he and Moises Torrent, DEEP environmental analyst, had relied on that afternoon to ensure no gasoline was leaking into the earth, it was Purple’s own sensory skills that detected the only problem that day.

The waft of gasoline hit him at the second of the four gas pump islands at the busy station near the I-395 entrance ramp. He and Torrent had just unscrewed the cover of the device to check where the hoses connect to the equipment that draws up the gasoline from the underground tanks.

“It’s not an active leak,” Purple said, shining a flashlight into the chamber. “It’s a little weepage. One of the threads just needs to be tightened. I knew I smelled something.”

The 6-year-old station, with two 20,000-gallon underground gasoline tanks and a third 12,000-gallon tank split with a section for biofuel and another for diesel, is one of about 900 Connecticut locations that store large quantities of gasoline inspected each year by DEEP crews. Statewide, there are 2,328 gas stations and fleet depots with 6,220 underground storage tanks — often referred to as USTs — where inspectors and monitoring equipment guard against the leaks and spills that would threaten groundwater and surface water supplies.

Federal law requires states inspect USTs at least once every three years. That is one of many regulations enacted over the years that has greatly reduced what was once the ubiquitous problem of leaking USTs, referred to by the ironic acronym LUST, resulting in thousands of expensive cleanups of contaminated soils and waters across the country.

“This was a major problem,” said professor Gary Robbins, hydrogeologist in the University of Connecticut’s Department of Natural Resources and the Environment, during a talk Wednesday about aquifers and groundwater to an audience of about 50 people at the East Lyme Public Library. “But now, the probability of releases has been brought to a very low number.”

Over the last two decades, double-walled fiberglass tanks have replaced the old-style bare metal ones prone to corrosion that once commonly were used. Between the walls are electronic sensors that set off alarms and shut off pumps automatically if a leak occurs. Piping is also double-walled, with leak sensors and automatic shut-offs. The underground tanks are equipped with spill buckets and other equipment that prevents overfilling and catches any overflow.

“The vast majority of tanks now are fiberglass, and the systems have a lot of fail-safes,” said Lori Saliby, supervisor of the storage tank and PCB enforcement unit at DEEP. “Most of the release issues we see now are relatively minor.”

During 2015, for example, inspectors found leaks, spills or equipment problems at 105 tanks at 896 facilities they visited that year. Purple said that because of automatic shut-off features, amounts of leaking fuel are usually small. If inspectors find a leak or malfunctioning monitors, he said, they notify station managers the same day and give them a month to fix the problem.

“We don’t fine on the first offense,” he said. “We give them 30 days to come into compliance. If they don’t, we use a consent order.”

On rare occasions, he said, he’ll “red-tag” a station, forcing it to shut down completely until the problem is fixed.

'Aquifers 101' presentation

Locally, perhaps nowhere has the care and equipment used at today’s gas stations received more attention than East Lyme, where construction of a Costco warehouse store with a gas station was approved earlier this month.

The gas station, which would have four islands with eight pumps drawing from three, 10,000-gallon underground tanks, would sit atop the sandy soils of a town aquifer, where groundwater flows just five to six feet below the surface. But the gas station would be about 300 feet from the town’s designated Aquifer Protection Zone. That is the portion of the aquifer feeding the town well, where gas station construction is prohibited.

The town’s Planning and Conservation of Natural Resources commissions both recommended the town maintain protection for the entire aquifer, which flows into the nearby Pattagansett River, rather than just the part that supplies the town well. But Zoning Commission members disagreed, expressing confidence that modern monitoring equipment and double-walled tanks, along with the installation of three monitoring wells around the site where groundwater would be tested annually for contaminants, will provide ample protection.

“I don’t anticipate any issues from this facility, because it’ll be brand new,” said William Mulholland, the town’s Zoning Enforcement Officer, who also oversees the requirements of the Aquifer Protection Zone. No construction start date for the project has been announced yet. But once it is, Mulholland said, he and the town engineer will meet with the project designers and engineers to add additional safeguards at the gas station.

“Two years down the road, when this is being built, the technology will be even more advanced, and we can continue to upgrade,” Mulholland said.

Plans show nine catch basins around the station to catch runoff that could contain spilled gasoline or oil that would connect to equipment that would filter out the petroleum products and send runoff into town sewers.

Concern about the town’s aquifer, which is traversed by Interstate 95 and beneath a busy commercial area along Route 161, was one of the reasons Robbins, the UConn professor, was asked by conservation commission members to give his two-hour “Aquifers 101” lesson. During a portion of the talk about gas stations and groundwater, Robbins recounted how underground tanks became the norm for gasoline storage in this country.

A century ago, he said, when the cars were first becoming available commercially, gasoline was kept in above-ground tanks and sold in five-gallon cans. But because gasoline is so explosive and flammable, there were many fires at stores that sold the fuel. The solution was to store it underground, first in single-walled metal tanks.

“Historically, gas stations were terrible,” Robbins said. “Putting gasoline underground was very good for fire protection.”

But a secondary problem occurred as tanks sat in the ground for decades and began corroding, with little or no oversight.

Beginning in the 1980s, the Environmental Protection Agency and Connecticut regulators steadily have been ramping up the requirements for gas stations, meaning that the newer the gas station, the better the chances it is not polluting the environment.

The most recent EPA data shows a steady decline in confirmed releases of gasoline from underground tanks across the country over the last 10 years, from 7,421 in 2005 to 2,591 a decade later.

“The problems have been minimized a lot,” Purple said.

Among the latest additions made by the EPA in 2015 include requirements that three operators at every station be trained in how to check monitors and respond when alarms sound. Monitoring equipment must be tested regularly and recalibrated annually to ensure it is operating properly. Records must be kept showing that amounts of gasoline in the tanks has been reconciled with the amount sold, and data and equipment must be readily accessible to state inspectors at any time.

“We never release the time we’re going to do an inspection,” Purple said. “We’re supposed to see the normal operating procedures.”

'Nice and dry'

During the Henny Penny inspection, the first in two years, Purple and Torrent started in the small room behind the checkout counter. While customers purchased bottles of soda and snacks, the inspectors leafed through large binders of monitoring records, then printed out reports on each of the tanks from the computerized Veeder-Root system attached to the walls.

The fiberglass tanks are permitted for 30 years, then must be removed unless the owner applies for a 10-year extension and agrees to additional inspections and monitoring requirements. Torrent said a fiberglass tank could show no signs of wear even after 30 years underground, but the permit expiration was put in place as an added safety measure.

“It’s just erring on the side of caution,” he said.

Fiberglass tanks can degrade, Purple noted, if the amount of ethanol in the gasoline is too high. Gasoline sold at Henny Penny and at Costco stores contains up to 10 percent ethanol, but if the amount is 15 percent or higher, he said, “it attacks the resin.”

After checking the equipment in the store, the inspectors moved outside to the area where the tanks and three fill spigots are located. After erecting cones and temporary fencing around the area, the two removed the heavy metal covers to reveal the underground machinery.

“This one’s nice and dry,” said Purple, peering into one of the tank holes. “If there is a leak, everything’s designed for it to flow back to the sump.”

Throughout the inspection, Purple put in data and photos of the equipment on his Panasonic Toughpad computer, which allows him to email the inspection report to the store manager immediately after he’s finished. The Henny Penny station was found to be in “significant operational compliance,” but with a notification that the equipment in the one pump island where Purple found the “weepage” should be tightened.

“Now, before I leave, they know what I found,” he said.

j.benson@theday.com

By the numbers

USTs nationally by the numbers, Oct. 2015 - March 2016:

• Number of underground storage tank cleanups completed: 4,597

• USTs inspected and found in significant operational compliance: 73 percent

• Confirmed releases: 2,591

• Percent of cofirmed releases still needing cleanup: 13.6

• Confirmed released in Connecticut: 55

Source: Environmental Protection Agency