Rock and a Hard Place

Cynthia Barnett | 9/1/2007

Incoming: Multinational cement companies are stepping up their efforts to import supplies. Rinker Materials, which is being taken over by the giant Mexico-based Cemex, is negotiating with the Tampa Port to build on 36 acres there. [Photo: Daniel Portnoy]

All concrete looks alike once it becomes a sidewalk. But there are as many combinations of ingredients for concrete as recipes for cake. The Florida Department of Transportation, for example, chooses from among 1,645 different concrete mixes when it specifies how a road, bridge or sidewalk should be built.

Just as cake depends on flour, the vast majority of those mixes involve an essential ingredient: Limestone.

Tour Florida's rock company mines. Click here.

In Florida, almost half of the high-quality limestone used in building materials, including concrete, comes from pits in northwestern Miami-Dade County. Since the 1950s, building materials firms like Florida Rock Industries, Rinker Materials of Florida, Tarmac America and APAC-Florida have mined limestone there. Over time, as water flowed into the enormous holes left by the draglines and the excavators, the mining created thousands of bodies of water. That’s how the 57,500-acre region got its name: The Lake Belt.

Along with limestone, the rock companies mine sand, limerock and other types of so-called “aggregates” that are key ingredients in building supplies.

Florida’s supply of limestone, along with its insatiable demand for the materials needed to build homes, roads and waterworks, have made the state one of the most important in the nation to the industry. Thomas A. Herbert of Lampl Herbert Consultants in Tallahassee estimates the state consumes 143 million tons of aggregates each year. About 120 million of those are scooped out of Florida mines — 55 million from mines in the Lake Belt.

bigger presence: Vulcan Materials Co., the largest producer of construction aggregates in the United States, imports material into the Port of Tampa. The Birmingham-based company is buying Jacksonville-based Florida Rock Industries for $4.6 billion. [Photo: Michael Heape]

In July, however, a crack opened up in the industry’s foundation. Ruling in a lawsuit filed by the Sierra Club and other environmental groups, U.S. District Court Judge William Hoeveler shut down most rock mining in the Lake Belt. He wrote that the enormous quarries, so close to Miami-Dade’s primary public water supply, raise “grave concern” about chemical and bacterial contamination of a wellfield that supplies more than 1 million people.

Hoeveler’s ruling nullified permits granted by the U.S. Army Corps of Engineers and handed the decision of whether to restore them back to the Corps. He left no doubt about his low opinion of the agency’s stewardship: “In three decades of federal judicial service, this court has never seen a federal agency respond so indifferently to clear evidence of significant environmental risks related to the agency’s proposed action.”

Tags: North Central, Housing/Construction