Caveda explored the area by swamp buggy and by foot. She combed the lonely woods, finding ancient paths and following endless miles of ATV tracks into the remote, swampy muck. She found the remains of old fires, abandoned scrap heaps, and even a half-submerged fuel storage tank and a car that had been dumped in a nearby lake. All were quickly ruled out.
Brant's team had begun exploring the possibility that the benzene was originating from a deeper and more distant source. The chemical, according to Bill Pitt, a professional civil engineer and hydrologist on Brant's team, was being drawn into the wells; it couldn't possibly be coming from nearby, for it would have to flow against the current created by the pumps.
But if it wasn't a spill, what was the cause? There is only one industrial presence in the area: rock mining. The wellfield is bordered by rock mines owned by White Rock Quarries and Florida Rock. As Brant's team followed the path of ever-higher concentrations of benzene, it led them south and east — right to the rock mines.
Anyone considering moving to Mars might want to have a look at the White Rock quarry to get a feel for the view. Situated directly between the communities of western Miami-Dade County and the wellfield that supplies their water, the quarry is a vast, blinding expanse of white — the color of crushed limestone — set against a backdrop of scraggly, grayish-green vegetation.
The quarry sits at the very end of NW 58th Street, past the seemingly endless strip malls, big-box stores, and cookie-cutter subdivisions — all built with Florida limestone — where the road abruptly narrows and appears to end in the bushes. It doesn't end, though; behind the brush, it opens onto another world.
Massive earth movers, caked in a gray crust of mud and dust, rumble along the road, hauling piles of crushed limestone. Near the quarry entrance stands a shack, a small cafeteria for the workers, its plastic tables outside turned gray with a coat of limestone powder. To the south is the mining pit — a vast, almost perfectly square lake, its water an unnatural, almost turquoise hue, stretching far into the distance.
It just so happens limestone, the same material that contains and naturally filters all of South Florida's drinking water, makes great concrete. It has been mined in this area since the Fifties. In the late Nineties, the Florida Legislature set aside for mining companies the so-called Lake Belt region, of which the Northwest Wellfield is a part. The "lakes" are the result of blasting and are large enough to be seen from space.
Florida produces and consumes more rock — crushed limestone in particular — than any other state except California. Without the cheap rock coming out of the Everglades, the building of South Florida as we know it today would not have been possible.
Florida's development boom gave the rock miners unprecedented wealth to invest. They bought political influence, hiring high-profile lobbyists such as Ron Book, Kerri Barsh, former County Manager Sergio Pereira, and Miami megalawyer Miguel De Grandy. In 2004, De Grandy successfully lobbied the county commission to do away with requiring rock miners to hold public hearings in order to obtain permits.
Among the sponsors of that ordinance was Commissioner Natacha Seijas, one of the miners' most loyal allies. In her 2004 re-election campaign, she received at least $2,500 from 13 donors connected to the mining industry, including Barsh and De Grandy. In addition, in 2006, White Rock Quarries and Barsh's law firm contributed a combined $10,000 to a committee fighting Seijas's recall.
Brant's team had begun to suspect the benzene was coming from the rock mines. For one thing, in an area otherwise devoid of development or industry, it was impossible not to notice the proximity of the mines, whose operations had expanded right up to the edge of the wellfield. Getting to the pumps required a drive through a rock mine.
Early in her investigation, Caveda passed through property leased by Florida Rock to get to a monitoring well. She asked her escort, the environmental manager for the site, how the mining process worked. She learned that as many as 40 four-inch-wide holes were drilled into the ground, filled with explosives, and blown up. The holes, Caveda noted with special interest, were drilled 60 feet deep — the same depth at which the highest levels of benzene were being found. She began inquiring about the nature of the fuel the company used and learned that most of the mining firms were using ANFO — ammonium nitrate fuel oil — of which a small constituent is benzene.