MIAMI (AP) - Miami-Dade County officials are exploring ways to inject sewage deep into the earth instead of releasing it into the Atlantic Ocean.
Changes in state law will require the county’s water and sewer department over the next nine years to stop pumping most of the 300 million gallons of treated waste generated daily through pipes miles out into the ocean.
Officials tell The Miami Herald (https://hrld.us/1RXIJjB ) that the only inexpensive way to comply with the new law is to send treated waste into cavernous saltwater zones below South Florida’s drinking water supply.
Miami-Dade’s senior professional geologist, Virginia Walsh, says pumping waste into the earth to filter over centuries deep into the ocean is safer and more environmentally friendly than dumping sewage into the ocean.
The method requires extensive waste treatment, partly because effluent from existing wells in southern Miami-Dade County and elsewhere escaped containment and seeped to the surface. Those leaks didn’t contaminate drinking water supplies, but they did push the county into a legal settlement with the federal government and force the state to change its laws regulating Class I injection wells to require a high - and expensive - level of treatment for injected effluent.
The Environmental Protection Agency says Florida is the only state that allows Class I municipal injection wells for such waste water.
Deep caverns have been documented in Florida’s geology. Geologists hope to find another porous subterranean zone capped and effectively sealed by a dense rock called anhydrate.
The county currently has 21 injection wells in north and south Dade. By 2025, they expect to more than double that amount at a cost of $635 million. Drilling of two injection wells planned at Virginia Key off downtown Miami should be completed by the end of this year.
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Information from: The Miami Herald, https://www.herald.com
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