Work to move heaps of decades-old garbage and prevent methane gas drift to homes begins this fall.
Back in the day, a trip to the city dump meant heaving whatever was in the back of a pickup truck onto a rotting, stinking, rusting pile of refuse as gulls hovered over the pile, looking for tidbits.
Anything and everything -- broken refrigerators, construction debris, sagging mattresses and plain old garbage -- was tossed into those pits. Much of that refuse is still there, cooking up a poisonous stew under lids of scrubby grass and trees.
It's the job of the Minnesota Pollution Control Agency (MPCA) to manage closed landfills, and the site that is the state's top priority for remediation is in Hopkins. In October, the 26-acre Hopkins landfill will be opened up.
The waste will be pushed into a new pile and the landfill will get an updated cover and new systems to handle water and methane gas. By late next spring the job should be done, at a cost of about $3 million. Such projects are paid for out of a special MPCA fund and through sales of state bonds.
Minnesota has a ranked list of 112 closed landfills that need remediation. The Hopkins landfill tops this year's list because it produces methane gas that could drift toward nearby houses, said MPCA project engineer Peter Tiffany.
"There's no imminent danger that something's going to blow up tomorrow," he said. "It's because of the amount of waste there, the proximity to people living nearby, and the potential that gas that contains methane could migrate to those structures. That's a risk we want to avert."
Methane is burned
The landfill, which looks like a grassy field, has 25 pairs of gas extraction pipes that protrude from the ground to disperse methane produced by the rotting garbage. Each pair of pipes includes one that acts as a vacuum and another that draws gas out, with an invisible flame burning the gas inside the pipe.
While those pipes have been doing their job of burning off methane, the two feet of soil used to cap the landfill when it closed in 1980 does not meet today's standards, Tiffany said. The site was an open dump from 1964 to 1971 and a state-permitted site for municipal waste disposal from 1971 to 1980.
After the closure, the landfill became a place for residents to walk. Kids biked there, too. After some adventuresome bikers dug in soil to build bike ramps, exposing some of the old refuse, the site was fenced. Since then, the narrow gate has allowed only walkers on the site.
When the landfill is opened in October, dump trucks will move waste north on the site to shift it away from homes. The landfill will be scraped clean to its bottom, said Doug Day, who supervises the closed landfill program for the MPCA. When waste is consolidated, the landfill should occupy about 14.4 acres instead of 26.
The work is being done in the fall and winter to minimize any smell, and the site will be capped with a thick plastic cover topped by two feet of soil. The plastic will prevent water from getting to the waste and should hasten decomposition, Tiffany said. It also will aid the gas collection system, which on the smaller site will have 17 pairs of pipes.
When the work is done, the site will be totally fenced to prevent trespass.
New city green space
The reshaping of the landfill means Hopkins will gain about 10 acres of reclaimed land, a big deal in a fully developed suburb.
"MPCA will plant clusters of trees there, so we will have more open green space for people," said Steve Sadler, Hopkins' director of public works. "We can start thinking about what use we have for the land."
No one knows how long it will be before the rest of the land can be used as something other than a landfill.
"That's the million-dollar question," Day said. In most cases, he said, former landfills are used as things like athletic fields that don't disturb the site.
Later this year, residents who live nearby will get a mailing explaining the project. Colleen Engelmann, who has lived on the south side of the landfill at Raspberry Woods Townhomes for more than three years, said she didn't even know the landfill was there.
"It's very wooded," she said. "I have never smelled anything."
Despite the landfill's state ranking as the top target for remediation, Engelmann said it's been a good neighbor.
She said that she lived in California near an open landfill. Once, employees in the building she worked in were told to go home because of worries about drifting gas from the landfill.
"I have never known what [the Hopkins landfill] was," she said. "I know what [landfills] look like and smell like, and that's not it."
Day and Tiffany said they never know what will be exposed when a landfill is opened up. Things don't degrade as fast as people think, Tiffany said.
"At some sites, we've dug up newspapers that are still readable and are 30 years old," he said.
He doesn't save them.
"Naw, it's kind of ripe," he said.
Mary Jane Smetanka 612-673-7380 Twitter: @smetan