LITHIA — At first, all you notice is a really big hole.
Then the smell hits. Like the sour stench that puffs up when you tie up a kitchen trash bag.
That stink could indicate a problem even larger than the hole: a leak.
A 45-foot-deep sinkhole opened up at Hillsborough County's Southeast County Landfill, utilities officials said Wednesday. With it surfaced fears of damaging environmental effects: wastewater seeping into the ground or gases polluting the air.
"There has never been in the history of this landfill any activity like this," said Patricia Berry, landfill and environmental services group manager.
So far, she said, there isn't enough information to say if the sinkhole has caused any environmental harm or why it formed.
County officials alerted the state Department of Environmental Protection, the county Environmental Protection Commission, Tampa Bay Water and the Southwest Florida Water Management District.
Tuesday afternoon, the landfill manager noticed a 5-foot depression on the west side of the property, an area last used in February. By Wednesday, the sinkhole had grown to an estimated 75 feet wide and 45 feet deep.
It's "very unusual" for sinkholes to appear in landfills, Berry said, because waste is more likely to spread outward.
In January, dozens of sinkholes formed in eastern Hillsborough after farmers drained aquifers to protect plants during a streak of below-freezing days.
With this week's freezes, farmers sprayed their fields Tuesday and Wednesday mornings. But the Southeast County Landfill on County Road 672 lies about 20 miles from that troubled zone around Dover and Plant City.
On Wednesday, landfill surveyors weren't pointing fingers at farmers. But they weren't ready to rule anything out.
Engineers will evaluate wave readings, similar to radar, to see how far the damage goes underground. Groundwater testing and gas monitoring will check for cracks in the inches-thick layer of clay that contains the waste.
The landfill, the only one in the county to manage municipal waste, is not upstream from any residential wells, Berry said.
Stephanie Wang can be reached at email@example.com or (813) 661-2443.