Image: trueStatement: There used to be an unidentified petroleum-based build up underneath San Diego called “the blob,” readers said in response to our call to Fact Check local urban legends.

Determination: True

Analysis: This tale sounds like the beginning of a spooky campfire story that parents tell their children to nudge them toward good behavior. Remember little Johnny Hanson down the street? When he didn’t eat his vegetables, the blob swallowed him up, sneakers and all.

Well, maybe that’s the story in some households, but this actually refers to one of San Diego’s largest environmental problems, which stalled downtown development, spurred lawsuits and cost millions to clean up. It was dubbed “the blob”: A massive underground plume of gasoline and diesel.

In the years following its discovery, city officials feared the blob might either cause an explosion downtown or pollute the bay. Neither ended up happening, but nonetheless, the blob became a mysterious story lurking beneath the city’s commercial core.

By the 1980s, San Diego was beginning to reap the rewards of a new downtown redevelopment agency, the Centre City Development Corp. With an infusion of tax revenue, the city set out to help build the staples of its future downtown landscape, including the Convention Center and a transformed Gaslamp Quarter.

To pave the way for this renaissance, CCDC bought up blighted land, including, to the point of this tale, one plot south of Horton Plaza that had been occupied by an industrial company, Super Plating Works. There, in June 1986, the city found soil soaked with gasoline and other hazardous waste.

Investigators later deduced that a leaking underground storage tank had been the culprit. Three more contaminated industrial properties nearby had also contributed pollution. In each case, enough gasoline or diesel fuel leached through the soil to form floating plumes above the underground water table.

Initial tests estimated at least 460,000 gallons of petroleum floating beneath a nine-block area near the intersection of Market Street and 2nd Avenue. In the news and among city officials, the problem simply became known as “the blob.”

“After several years of good press and we’re-building-as-fast-as- we-can development, the city of San Diego’s ambitious urban renewal program faces a new nemesis,” the San Diego Union reported in 1989. “Officials, taking a note from one of the cheesiest horror films of the late 1950s, call it The Blob.”

David Allsbrook, now a vice president at CCDC, claims credit for starting the name. It stuck, he said, because it resembled some kind of underground amoeba and continued to frustrate developers.

The discovery delayed construction of a proposed hotel and a nearby apartment complex. At the time, a CCDC executive called it possibly one of the most dangerous liabilities facing the city.

Authorities said the plumes weren’t harmful to people because the contamination had been contained deep beneath the surface and didn’t affect the city’s water supply. But they acknowledged a much larger concern — the blob appeared to be moving toward the bay and also risked exploding.

As city officials continued to study the plumes, construction began on a new Convention Center several blocks away. In order to prevent flooding, the city pumped water out of the ground and into the bay. That pumping process kept the Convention Center dry, but it also appeared to be drawing the blob closer to the bay.

“It was a fairly big deal,” Allsbrook said. “But over time, we were able to prove that there wasn’t very much of the product left and it wasn’t going anywhere.”

With immediate concerns about bay pollution put down, the bigger problem became how to clean up the mess. CCDC and the companies settled on a cleanup plan with state regulators that removed contaminated soil at the four sites and the floating gasoline and diesel fuel above the water table. The final costs, Allsbrook recalled, were around $5 million.

In 2005, the San Diego Regional Water Quality Control Board deemed the last of the four sites to be meeting the state’s cleanup requirements. “I didn’t know it was an urban legend,” said Susan Pease, an environmental scientist who oversaw cleanup for the state water board. “I worked on it just like any other case.”

More recently, a passing reference to the blob appeared in the draft of a once-secret study commissioned by CCDC to examine potential reasons for its continued existence.

As for the original blob itself, “we’re done,” Allsbrook emphasized. “There’s nothing more required of us.”

Since a petroleum-based pool once existed beneath the city, and it was widely regarded as the blob, we’ve called this statement true.

It’s worth noting that while the original blob has fallen out of the public limelight, there are still others to talk about these days. Similar underground contamination has been discovered elsewhere downtown and in Mission Valley around Qualcomm Stadium. The costs of removing both plumes have become issues in the Chargers stadium search.

Who knows? Maybe those plumes too will become part of urban legend some day — the blobs that devour children who don’t eat their vegetables.

Please contact Keegan Kyle directly at or 619.550.5668 and follow him on Twitter:

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