Benzene at core of mining case

A serious chemical plume has largely dissipated but raises new questions in a federal court hearing on the future of rock-mining around Miami-Dade County's largest well field.

BY CURTIS MORGAN cmorgan@MiamiHerald.com

After 20 months and a $1 million investigation, Miami-Dade officials have been unable to identify the source of a cancer-causing chemical that forced the shutdown of a third of the pumps that tap the county's largest and most pristine source of drinking water.

No water tainted with benzene, a solvent and petroleum compound, has ever reached any faucets. Concentrations now have dropped so low, below detection for the most part, that the county expects to reopen four closed wells at the Northwest well field within weeks.

''There is absolutely nothing wrong with that water,'' Joe Ruiz, deputy director of the Water and Sewer Department, said. ``It's perfectly safe.''

But the contamination could have ripple effects in an ongoing federal court hearing that has major implications for the limerock industry, which hopes to excavate a chain of quarries around a well field that supplies more than 1 million people.

The investigation sparked a dispute between two county agencies, with senior water managers urging environmental regulators to look harder at rock-mining, the only major industry near the isolated wells.

Though the subject of months of internal memoes and meetings, the mystery plume did not come to public light until the hearing, which resumes in late August.

As former water director Bill Brant put it, the department's ''chief suspect'' was a diesel-fueled explosive used by the company, White Rock Quarries, to blast rock at a nearby pit.

Environmental regulators and miners insist the theory doesn't hold up. They argue: Why has an explosive commonly used for years never before tripped pollution alarms at the wells?

''We could never connect it to some culprit,'' said John Renfrow, who led the Department of Environmental Resource Management before taking over the water department after Brant was forced out over other issues.

The hearing, which began in June, was called by Senior U.S. District Judge William Hoeveler after he ordered federal agencies to reassess permits allowing mining to expand into 5,400 acres of wetlands -- the first phase of a planned ``lake belt.''

The judge, in a lawsuit brought by three environmental groups in 2002, found federal agencies had done a poor job analyzing potential harm to the Everglades, the endangered wood stork and the well field.

NEW MINING REVIEW

But he left open the critical decision of what, if anything, to do about mining operations during a new review expected to take 18 months or longer.

Environmentalists have urged the judge to restrict digging in undisturbed wetlands. The industry, which supplies half of the state's cement and fill, has countered that environmental damage would be outweighed by the economic impact of limiting work, warning of thousands of lost jobs, construction delays and price hikes.

Hoeveler ordered the review in March, before environmental attorneys found the benzene probe in county documents.

Paul Schwiep, an attorney representing the environmental groups, said the chemical added to concerns in the initial lawsuit, raising contamination threats from risk to reality.

''This incident proves what we have been saying from day one, that excavating 80-foot deep mining pits from an area where we draw our drinking water is a dangerous idea,'' he said. ``We know about benzene today. We don't know what it will be tomorrow.''

The county already has acknowledged that federal studies of groundwater flow suggest that existing protection zones, which prevent mining within a half-mile of the wells, may be too small to kill hardy parasites such as cryptosporidium.

Mining attorneys said it would be inappropriate to discuss the issue before presenting their case next month.

But in cross-examinations and depositions, they've painted the blasting link as unsupported speculation that could unfairly taint miners.

Douglas Halsey, an attorney for 10 companies in the Miami-Dade Limestone Products Association, has hammered at the expertise of the water department -- pointing out that engineers never knew fuel was used in explosives until a bomb squad cop told them.

Halsey and Mark Brown, an assistant U.S. attorney representing the federal agencies, initially urged Hoeveler to bar the benzene information, arguing it was outside the scope of the lawsuit and would ''open a can of worms'' likely to extend the hearing for weeks.

INDUSTRY CONTENTIONS

The industry has long contended its pits pose no health or environmental threat and actually protect wells by providing a development buffer.

Though mining has gone on for decades, the well field, several miles west of Florida's Turnpike and north of Tamiami Trail, has been considered the county's cleanest.

Kerri Barsh, an attorney for White Rock, said the company cooperated in the probe, temporarily halting blasting and voluntarily shifting to a mineral oil-based explosive ``just to eliminate any concerns that its ongoing operations would be the source of benzene.''

None of the companies operating in the lake belt uses the fuel-based material anymore, said Tom MacVicar, a mining consultant. He suspects a probable source was gasoline, which contains far more benzene than diesel, perhaps spilled by off-road racers or illegal dumpers.

Miners dismiss contamination threats as overblown, arguing filtering systems can eliminate both pathogens and high levels of chemicals.

The peak benzene level detected in the drinkin- water wells -- 15 times higher than allowable -- could be extracted by existing treatment systems at the two water plants the well field feeds, said Wilbur Mayorga, DERM's pollution remediation chief.

The plants' ''air strippers'' can evaporate an array of volatile organic compounds such as benzene at much higher concentrations, he said.

But the strippers were never put to the test.

Eleven other wells at the site pumped enough water to meet county needs, Mayorga said, and over the last five months the benzene has nearly disappeared, decaying underground without any special treatment.

''We feel comfortable we can restart the system,'' he said.

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