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SinkHole

Terminal month, a 300-human foot deep sinkhole opened up at a phosphate institute in Mulberry, Florida. The sinkhole, which measures some 45 feet in diameter, poured 215 million gallons of wastewater directly into a major Florida aquifer. Just homeowners and nearby residents who draw drinking water from that aquifer weren't notified of the breach for more than three weeks.

The reason? Current laws don't require notification until there is evidence that the water migrated off-site. The manufacturer, Mosaic, told the Florida Section of Environmental Protection, the EPA, and Polk County officials, only wasn't required to postal service anything publicly about the incident.

"Should at that place be any indication of offsite migration of contaminated groundwater, rules crave the notification of afflicted parties," the DEP'southward Dee Ann Miller said in an e-mail to the Tampa Bay Times. "Still, to date in that location is no evidence of offsite motion or threat to offsite groundwater supplies."

That'due south quite unlike than what happened in 1994, as the Tampa Bay Times notes, when a similar sinkhole opened at a dissimilar phosphate plant. The Florida legislature inverse the law in 2005, giving plant owners ten days to notify the Florida Section of Ecology Protection, and DEP 30 days to notify consumers. Said notification period kicks in simply after contamination has been establish outside the initial surface area, which means Florida residents who depict water from the aquifer legally nonetheless weren't entitled to know their drinking h2o might take been compromised.

A chip of background may be helpful here. According to the US Geological Survey (PDF), Polk County'southward hydrology is equanimous of iii layers — a surficial aquifer provides most of the groundwater for the county, with a confining layer and a lower aquifer system below that. The upper, surficial layer of the aquifer system ranges profoundly in thickness, from several feet in some areas of the county to more than 200 feet thick in others. The image below, from Wikipedia, shows a typical aquifer with a similar distribution of layers.

Aquifer

The terrain in this part of Florida, known equally Bone Valley, is a unique mix of sand, phosphate pebbles, and clay. These substantial phosphate deposits are considered a major distinguishing feature of the area and have been mined for commercial fertilizer production for decades. The problem in Polk County is the expanse also contains large amounts of limestone, dolomite, and gypsum — all materials that are soluble in water. This makes the entire region prone to sinkholes, caves, and other similar rock formations. Combine sinkhole-friendly strata with extensive mining, and you've got a recipe for h2o pollution.

The radioactivity comes into play considering the phosphate deposits we mine for fertilizer are weakly radioactive to starting time with, at roughly 100 ppm. The phosphate ore is treated with sulfuric acrid, creating a byproduct known as phosphogypsum. Phosphogypsum is somewhat more radioactive than the raw ore, since the treatment process concentrates the radioactivity that was present initially. Phosphogypsum is stored in huge "stacks," but since it emits radon initially, the stacks are covered in water. Over time, as the water evaporates, the stack forms a thick crust that seals at least some of the radon gas and prevents the phosphogypsum from blowing in the current of air and creating dust storms. The sinkhole that opened in Tampa brusk-circuited this process by draining the water directly into the water supply.

For now, Mosaic is offer free water testing to concerned residents and has already set a recovery well pumping iii,500 gallons of water per minute out of the afflicted area, to try and recapture some of the contaminated material. But this item stack will proceed to leak into the aquifer until the hole is physically plugged, which could yet accept months. Bone Valley currently contains roughly one billion tons of phosphogypsum in these various stacks. No current program exists for repurposing the material, though in that location have been various proposals to use it for road pavement, a landfill cover, or for artificial reefs.