PLANT CITY – Each time the region experiences heavy rain, settling ponds at one of the county’s oldest phosphate processing plants release arsenic and other toxins into a nearby stream.
Coronet Industries, at 4082 Coronet Road on the east side of Plant City, is under orders from the state to make sure the spills don’t continue.
When the discharges occur, the toxic water flows into English Creek, which eventually drains into the Alafia River.
Coronet Environmental Manager Jim Baker said the company is working on a plan to increase the size of the settling ponds at the plant, which will, in effect, eliminate all surface water discharges.
The state Department of Environmental Protection will have to approve the final improvement plan before it lifts a consent order against the Japanese-owned company.
If DEP approves the plan, Coronet intends to start work to increase the size of its ponds in February, Baker said.
DEP officials say the discharges, which occur sometimes twice a year, don’t pose an immediate health threat. But the amounts of arsenic and other metals in the discharges far exceed the state’s allowable levels, said Tim Parker, program administrator with DEP’s water facilities section, which oversees industrial waste water in the region.
Leslie Williams, a DEP toxicologist based in Tallahassee, said a level of 50 milligrams of arsenic per liter of surface water is considered safe for humans. Coronet is releasing about 100 milligrams of arsenic per liter of water.
Still, Williams said, arsenic does not accumulate in fish or other aquatic organisms, so it should not pose a hazard to anyone fishing or swimming downstream.
A far greater threat comes from fishing or swimming in phosphate mine pits, according to the federal Agency for Toxic Substances and Disease Registry, an arm of the Centers for Disease Control and Prevention in Atlanta. Those ponds tend to contain fish with high levels of mercury and arsenic in their systems.
“From an ecological perspective, … [the spills are] not a concern,” Williams said. “We don’t note an effect [on aquatic life] until 200 milligrams per liter.”
Since the discharges occur only about twice a year, she said, much of the arsenic, which occurs naturally in phosphate rock, is greatly diluted as it moves downstream. “There would be a much greater concern if this were a continuous discharge.”
But the discharges cause enough of a concern that the state agency issued a consent order in August 2001 requiring Coronet to eliminate the toxic releases.
The company is trying to renew its discharge permit with DEP but can’t until it can prove this problem won’t persist, Parker said.
Coronet Industries, which is nearly a century old, produces an animal feed supplement called tricalcium phosphate. Built in 1903, the plant derives the supplements from phosphate rock.
The arsenic and other metals are a byproduct of making the supplements, Baker said.
The majority of water used in the plant’s process is cycled back through the facility and used in stacks to scrub the steam released into the air, Baker said. The remainder is run through a series of nine ponds to allow metals and chemicals to settle out.
The plan Coronet is developing would increase the size of the ponds so there would be virtually no surface water discharges, he said.
The discharges that led to the DEP consent order occurred in 1997 and 1998 when the region was experiencing an El Nino winter with unusually heavy rains.
The last spill – and the largest – occurred during Tropical Storm Gabrielle. The site released 178 million gallons of toxic water in September 2001, which flowed into English Creek and Alafia River.
In addition to arsenic, a natural component of phosphate rock, silica, calcium, phosphorous and various trace minerals and metals are released into the ponds, Baker said.
Besides increasing the size of the holding ponds, Coronet is working on a deal to sell the metals and chemicals collected in the settling ponds for reuse.
“We could either dredge the material out of the ponds, suck up the sediment or drain the ponds and scrape the surface,” Baker said. Coronet hasn’t found a buyer.
Air Emissions Problems
Coronet also is rying to avoid a shutdown by the Hillsborough County Environmental Protection Commission for air emissions violations.
The plant has a lengthy history of emissions violations, and EPC has required the owners to bring the plant up to standards to eliminate toxic emissions by 2005.
The company has 180 days from when it signed the EPC consent order in October to produce an environmental audit outlining the plant’s shortcomings and proposing ways to correct the problems.
The process Coronet uses to make its animal food supplements produces dust particles and a noxious gas called hydrofluoric acid gas, which, if released untreated, can kill plants and rust metal, EPC officials say.
Sterlin Woodard, assistant director of the EPC’s air management division, said the agency still can shut the plant down if the owners fail to live up to their part of the consent order.