NEW MEXICO (KRQE) – There are more than 3,000 underground storage tanks — most of which hold petroleum beneath gas stations — scattered throughout New Mexico. Yet because of the pandemic and staffing shortages, only a tiny fraction was fully inspected for leaks in recent months.

Fewer than one percent of facilities were fully inspected in the second quarter of fiscal year 2021, a recent Legislative Finance Committee report reveals. In that quarter, inspection rates were down by 92% compared to the same period in the fiscal year 2020 — only 10 inspections were conducted in this most recent quarter. The report points out that 163 facilities in New Mexico have “outstanding violations that can threaten groundwater.”

“The principal threat from a leaking underground storage tank is that it contaminates shallow groundwater,” says Bruce Thomson, a civil engineering professor at UNM who was on the state’s Petroleum Storage Tank Committee in the 1990s and late 2000s. In the worst case, he says, contaminants can enter the public water supply.

In the past, “A number of sizable communities have had their public water supply wells impacted by leaking underground storage tanks,” Thomson recalls. “Gallup has had some problems. Roswell’s had some problems.” In the early 1990s, Thomson says there were “12,000 to 15,000 underground storage tanks, and that as they inspected these, about a third of them were found to have problems.”

But that was in the 90s. Since then, many of the worst tanks have been removed or replaced. Now new, better tanks means fewer leaks. At least that’s the hope. But the recent drop in inspections means that it’s possible some leaks have gone undetected.

Nationally, New Mexico had the lowest on-site inspection rate from October 2020 through March of 2021, according to data from the United States Environmental Protection Agency (EPA). Dana Bahar, the chief of New Mexico’s Petroleum Storage Tank Bureau, explains that the inability to do on-site inspections means few tanks were inspected to completion, but work was still done during the pandemic.

Nationally, New Mexico ranks last in terms of the percent of tanks inspected. Data from EPA.

To consider an inspection complete, the EPA requires both an inspection of paperwork and an on-site equipment inspection. Because of this, Bahar says the inspection numbers look worse than they actually are. After all, the department was still doing paperwork inspections remotely, even when they couldn’t be in the field checking equipment.

“We did do 407 inspections between July 2020 and April 2021,” she says. These checks included making sure the tank owners had paid their tank fees and that they had their registration in order. Additionally, Bahar points out they did do some field inspections.

“We were at what we considered the priority inspections: tank installations, tank removals, [and] repairs,” she explains. But many other tanks went without actual equipment checks during the pandemic.

So a huge number of tanks went at least partially unchecked. The question is: Have there been undetected leaks?

For the relatively modern double-lined tanks, there are probably few to no major new leaks going undetected. “In the short term, I have a fairly high degree of confidence in the new installations,” Bruce Thomson says. But throughout the state, there are currently 136 tanks that lack spill and leak prevention equipment or have maintenance issues, according to data from the Petroleum Storage Tank Bureau.

But that doesn’t necessarily mean these tanks are actively leaking, nor does it preclude other tanks across the state from leaking. A list of all sites that have ever had a confirmed leak since the 1980s reveals 2,408 sites that have leaked at some point. So far, more than half of the leaks on the list have been cleaned up to the extent required by law.

More recently, since the beginning of 2020, 34 sites have had suspected or confirmed leaks. Of course, not every site generates the same environmental or health impacts.

“Areas that are of special concern,” explains Thomson, “are those where we’ve got a leaking underground storage tank that is located in an area where depth to groundwater is shallow.” The shallower the groundwater, he explains, the faster petroleum pollutants — things like benzene, which the EPA classifies as a carcinogen — can arrive at groundwater.

Of the 2,408 sites that have leaked in the past or are currently leaking, 1,468 are found above shallow aquifers that are less than 100 feet deep, according to a KRQE analysis using data from the New Mexico Environmental Department. Many of these are found just above the saturated soils of the Rio Grande valley, and most of the big leaks come from old tanks that leaked for decades before being caught.

Throughout the state, nearly 200 underground storage tanks in the pre-cleanup stage rest less than 100 feet above an aquifer (red dots). Data from New Mexico Environmental Department.

Back in the “old days,” Bahar says, “there were stories about how people knew they were losing fuel but they kept filling their tanks and selling it.” These leaks could amount to hundreds of thousands of gallons of leaked fuel over several decades, she says.

Several prime examples can be found around the state. One site in Espanola had been a gas station since the 1970s. By the time the site’s three underground tanks were removed in 2012, an estimated 346,500 cubic feet of soil had been contaminated, according to a 2021 report. That’s almost enough gasoline-contaminated soil to fill four Olympic-sized swimming pools.

At another site in Albuquerque, a set of tanks was removed in 1990 — but not before an unknown amount of petroleum made its way into the ground, according to a 2019 report. Now, Los Solecitos Academy Childcare Center sits above the site on Isleta Boulevard, just north of Rio Bravo.

There are several domestic wells nearby and groundwater — connected to the Rio Grande and generally used for irrigation — is only seven to eight feet below the surface, the report shows. More than 29,000 cubic feet of contaminated soil have been removed, and most of the major contaminants have been cleaned up enough to meet water quality standards. But naphthalene levels — the toxic chemical used in moth balls — remains above acceptable levels in a limited area, according to the New Mexico Environment Department.

The good news is that despite the economic downturn during the pandemic, Bahar says the fund used to clean up these sorts of high-priority sites has been fairly stable. As of April 30, 2021, the Petroleum Storage Tank Bureau’s website reported they had $4,707,745.39 in the fund that they can use to start new cleanup projects. Of course, identifying new cleanup sites requires on-the-ground inspections.

“You cannot over emphasize the importance of early detection for any of these types of problems,” Thomson says. “The Environment Department does need to stay on top of this, because if they become too lax, you know, there’s always the risk that someone will take advantage of the lack of oversight, and we’ll have some problems in the future.”