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The limestone layer above the dolomite is not nearly as effective a barrier as county officials seem to believe it to be, argues McNeill. In fact McNeill has a poor view of the county's geological assessments in general and says evidence of its mistakes can be found in its own information. For instance the county didn't recognize the dolomite was the key to keeping the sewage down below. While drilling, the county's contractor Alsay, Inc., punctured the dolomite and a stream of water shot up about 25 feet. The county concluded the dolomite was porous. McNeill believes the pressure from trapped water underneath the dolomite caused the stream to spurt.
“They have made some fundamental faulty geologic estimations,” he says. “It's surprising they don't look closer at their own data.”
Part of the reason may be that the county no longer has possession of it. McNeill says when he asked for logs that would give more precise detail of the geology at the South Miami-Dade deep well injection facility, he was told the county had lost the information during Hurricane Andrew. Luckily the United States Geological Survey had a copy of the logs.
The sewage the county is injecting is less salty than the water in either the boulder zone or the Floridian aquifer. The fresher water has a natural inclination to form a bubble and rise. After McNeill studied the logs, he concluded the lower confining layer sloped upward to the west. He surmised that, as the water rose it would move west, following the slope, not east. This theory jibes with where the county has found contamination at the site.
County officials and their consultants sold the public the idea that the wastewater would slowly make its way to the east and out into the ocean. They told the state environmental regulatory agency that after twenty years of injecting sewage at an average of 50 million gallons per day, the lake of waste would stretch out 8.6 miles underground, heading toward the sea. Now everybody from the county to the federal government admits they have no idea how far it has spread and in what direction. There are no monitoring wells outside the South Miami-Dade facility site, so it's impossible to know the true extent of the sewage plume.
The county has its deep injection wells divided between two facilities. The one in the north of the county only has four wells, none of which are currently operating. Down at the South Miami-Dade facility, there are seventeen wells, of which all but four are being used. By the county's own admission, it has detected contamination of the drinking water in at least seven of the wells. The Miami-Dade County Water and Sewer Department can't explain why.
What is known is that signs of wastewater took 11 years to reach the aquifer -- 332 years earlier than predicted. “It seems to be traveling 180 degrees different from what they projected,” McNeill notes.
He believes the water and sewer department could have avoided both its misplaced overconfidence about the impermeability of the lower confining layer and its ignorance of the geological landscape if the department had conducted more studies prior to risking the county's drinking water. It also could have invited other scientists to analyze the data in a formal peer review. Although geologists from the federal U.S. Geological Survey sit on an advisory committee for the county, they don't generally have the time to do a thorough investigation like a proper and impartial scientific peer review would.
More disturbing perhaps than the erroneous assumptions the county made is McNeill's assertion that the water and sewer department failed to follow even its own guidelines for digging the wells. It appears the department didn't even get underneath the confining layer, because county geologists failed to recognize where it was.
Recognizing that they could have a public-relations disaster on their hands, Florida's utilities have endeavored to explain how the deep well process works. The utilities have become reliant on deep well injection technology and are fighting like hell to avoid being forced to stop. They have hired expensive PR firms, such as Wragg & Casas, the group that helps to sell corporate welfare on a mammoth scale for Big Sugar. The utilities, in conjunction with the main company that builds deep injection wells, Youngquist Brothers out of Fort Myers, have written countless editorials and distributed fact sheets on how they dig the wells.
They begin with a big hole, which gets narrower the deeper it goes. The first opening is typically 58.5 inches in diameter, drilled down to the base of the Biscayne aquifer, usually a depth of about 260 feet. Next, a steel pipe, one-half-inch thick and 50 inches in diameter, is lowered into the cavity. Sulfate-resistant cement is pumped down to encase the entire length of the pipe, and then to seal it to the surrounding rock. Concrete is used in this manner for all the stages. The pipes get smaller in three successive stages, dropping first to 1000 feet, then 2300, and finally into the boulder zone. After that no more pipes are used, and the well becomes an open hole where the sewage pours into the cavernous formation.