SAN FRANCISCO (KPIX 5) — At 20th and Valencia in San Francisco another condo project is rising from the dirt.

It’s one more example of a real estate market that almost defies description.

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“Yeah, it’s unbelievable. Overbids on everything and less and less inventory,” realtor Tim Brown of Brown & Co. Real Estate told us.

But this particular site tells a story that began in 1998 when a gallon of regular unleaded gas cost less than $1.50. That’s when federal law required gas stations to replace old, underground storage tanks with modern, corrosion-resistant models — a move that put a lot of mom ‘n’ pop stations out of business.

From there, a mix of economics and environmental laws turned many San Francisco gas stations into deserted eyesores, like the mess that sits across the street from an operating station on South Van Ness.

The cost and bureaucracy involved with cleaning up these sites kept developers away for years — even decades. Now, that’s changed.

“The uptick of the market, more development going on, and the ease of moving things through the city, more people are picking up gas stations, and other under-utilized sites,” said Tim Brown.

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Brown is turning a handful of old gas stations into condo developments. He says this is about more than just a hot market. He points to a city that is determined to grow.

“Several areas of South of Market and the Mission have been up-zoned so that the density is higher and people can build more than they could have maybe three or four years ago,” Brown said.

That added reward for develpers has the city scrambling to sign off on clean-up jobs like the one at Valencia and 23rd.

“We require that site to be cleaned up to residential standards,” said Stephanie Cushing with the S.F. Department of Public Health.

“Cases that I’d been working on, maybe 3 to 5 years ago, nothing happened on them, suddenly they’re being revived.”

So, if your neighborhood has an abandoned gas station that seems like it’s been there forever, don’t be surprised if it suddenly goes from eyesore to construction site and ultimately ends up looking luxurious.

Tim Brown says “more and more gas stations will be eliminated, more and more warehouses, any industrial-use underutilized site.”

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Welcome to the brave new world of San Francisco real estate.