ST. PETERSBURG — The ad for the sprawling piece of vacant land in the heart of Pinellas County reads like a developer's dream.
The 240-acre, county-owned parcel near I-275 and Roosevelt Boulevard has easy access to Tampa, and some 650,000 residents live within 10 miles. The site is already zoned to allow for up to 2 million square feet of office space and 1.5 million square feet of retail, housing and hotel space.
But lurking beneath the grassy surface is a construction engineer's nightmare: a layer of garbage, perhaps as thick as 60 feet in some places, emitting methane gas and creating an unstable building surface. Though the location of the former Toytown landfill is prime, the roughly 25 years worth of buried household trash, construction debris, yard waste and sludge takes the sheen off a site the county has been trying for years to sell or lease.
"Some of the developers contacting us now are well aware that they'd have to build on garbage and are okay with doing that," said Mike Meidel, the county's economic development director. "The tradeoff is they're expecting to get the land for practically nothing."
Now the county plans to go digging to find out how much it would cost to unearth and remove much of the trash to make the site more valuable and buildable for a mixed-used development, corporate headquarters or even a baseball stadium.
The solid waste department is preparing to seek bids from companies that would take core samples from throughout the site, an archaeological dig of sorts. Once they have the estimate, the county can decide if the increase in the site's value would be worth the investment to dig up and haul the trash away to recycling facilities or to the county's waste-to-energy plant or active landfill, both on the other side of the interstate.
"We're going in to quantify how deep the waste is, the extent of the waste and how decomposed it is or isn't so we can really understand what we've got to work with," said Kelsi Oswald, director of the county's solid waste department.
Operated by the city of St. Petersburg, Toytown opened in the early 1960s and was the primary landfill for south county until it stopped taking trash in mid 1980s. The county now owns the site and pays about $750,000 in annual maintenance costs.
Detailed records are scarce, but county officials believe the trash was placed in trenches as deep as 20 feet covering about 200 of the 240 acres. The existing mound, covered with a cap of dirt about 2 to 4 feet deep, is some 40 feet high.
The site likely contains a lot of metal, wood and concrete because there wasn't much recycling happening in that era. Officials also expect to find some well-preserved refuse. The tighter the trash is compacted, the slower it decomposes, and the more decomposed the better because it's less material to dig up and move, Oswald said. Crews who have been on site digging for unrelated drainage work are bringing up garbage that looks "fresh," she said.
Building on a landfill is problematic and more costly for a couple of reasons. The garbage makes the soil unstable, which means builders must spend extra money to pin foundations to solid earth underneath. But roads, parking lots and other paved surfaces can't be pinned, so they remain vulnerable to settling. And the decomposing garbage is emitting low levels of methane gas that could pose health risks by seeping into and collecting in any structures built there.
Developers who proposed an $870 million venture with homes, offices and retail space pulled out in 2011, falling victim to the recession, financial troubles of a partner and the environmental hurdles. Soil boring to test the site's suitability was never done.
If the county decides to move forward, crews would use a large rotating screen called a trommel to separate larger materials from the soil. Recyclable materials would be hauled away to be processed. Burnable garbage would be trucked to the county's plant on 114th Ave. N, where garbage is incinerated to form steam for turbines that create electricity purchased by Duke Energy. The rest would be dumped in the adjacent active county landfill called, somewhat incongruously, Bridgeway Acres.
The county has researched other so-called garbage "mining" projects that have been successful, though the size of this one would be rare and could take three years to complete, Oswald said. She hopes to have a consultant hired by the end of the summer and a final report by the end of the year.
So how much might the mining project cost, and how much is too costly to make it worthwhile?
"The $10 million to $20 million range would probably be feasible to do," Oswald said. "If you get up to $40 million to $50 million it's probably something we couldn't do. In the middle, we'd sit down and say, 'Let's look at the numbers.' "
That means weighing the revenue from a lease or sale — Meidel estimates the site could be worth $24 million if the garbage is removed — along with the property tax revenue from potential development, among other factors. The County Commission would have the final say.
"If it's successful," Meidel said, "it puts us back in the driver's seat."
Contact Tony Marrero at firstname.lastname@example.org or (727) 893-8779. Follow @tmarrerotimes.