Environmental activist concerned about toxins from landfill sinkhole getting into aquifer

12/16/10 Seán Kinane
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On Tuesday, a large sinkhole opened in a southeast Hillsborough County landfill. Some environmentalists are concerned the toxins from the landfill could contaminate the aquifer.

The 25-year-old landfill is operated by Waste Management and according to the county's website, the facility receives non-processable solid waste, shredded tires and demolition debris. I only has a clay lining.

Vivian Bacca is a board member of United Citizens Action Network and is active in community and environmental issues in Hillsborough County.

"It is in south county, it's kind of between Balm and Lithia, and it seems like it's kind of on the southeastern edge of the landfill so it's hard to tell looking at the map. But it's probably primarily on a 'karst' type of geology that is predominant in Hillsborough County and most of Central Florida.

What is karst?

"It's basically almost like limestone honeycomb. In other words a lot of the country and geologists, when they go to school, they learn about hydrology, how water drains down to the aquifer and in most cases it pretty much goes straight down in a straight line, but in karst, it's almost like there's a beehive of limestone and pockets so that the aquifer doesn't necessarily percolate down straight, it goes in these little channels so it doesn't have the same level of stability as, say, the clay areas of north Georgia."

And so, of course, the stability is in jeopardy here with this sinkhole. How do you think that this sinkhole underneath the landfill could affect the aquifer?

"There's some kind of a liner that they put in the landfill before they put the trash on top of it. But what's not clear, looking at the sinkhole, particularly because it almost looks like, it's starting to look like a mine shaft instead of just this giant depression. It's getting a center which seems to be much deeper so the question really is, is the liner that protects the aquifer and keeps the waste from seeping into the groundwater, has that been penetrated because of the sinkhole?"

If it has been, what are some dangers there? What types of materials would be in this landfill that you wouldn't want to get in the aquifer. And if they did get in what would the effect be?

"I'm not sure what's in that landfill and I think that's a big question because I believe that the only one in the county that's a Class 1 landfill and I think that means that they accept everything. So I don't know ... for example like batteries. Are batteries buried in there? What was buried in there? When was that particular section utilized because the environmental rules and what we understand about the degradation of chemicals has evolved. So is that an older part of the landfill where, maybe, just anything was dumped in there?

"For example, over in Dover, we have the old phosphate mines, the city mine which was used as a dump. It's now a Superfund site and subject to all sorts of cleanup. I think it's pretty much been allegedly remediated. But, I don't know, it could be battery acid. It could be who knows what. Some of the chemicals that we're using today have been in existence probably less than 50 or 100 years. So we don't even know what kinds of things may eventually happen when they break down."

And finally, Vivian Bacca, this in a section of the county that has a lot of phosphate mines, do you know anything about the history of phosphate mining where this landfill is?

"Not specifically on that landfill, but we do know that phosphate changes the composition of the ground and stirs up radon and changes the way the ground percolates. I would be concerned because you don't know how much, you know, where was the old gypsum stacks, things like that. One thing I would be curious to find out, because I couldn't really tell from the map but, as the crow flies, it looks to me like this is 2 to 3 miles from the reservoir, the C.W. Bill Young reservoir, which I believe is the largest reservoir in, certainly the state of Florida, if not the entire country. And we're talking about, as part of the fix to the crack, raising the height of that reservoir. So is the fact that we've got a sinkhole under the landfill an anomaly, or does it really indicate that there could be possibly a chain of karst caves that maybe go underground through our county all the way from the Dover/Plant City area, which was the major focus of the sink holes last year, down past the reservoir to the landfill. The last time I asked a question they said that they had done tests when they did the reservoir. You have to say to yourself that our entire, for the most part, most of our county is on an area that's geologically sensitive, so I think we need to be aware of that when we locate facilities."

Previous WMNf coverage of landfills

The county's page on the sinkhole

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