F3a Four Corners Mine

F3a Four Corners Mine is an earth dam located in Manatee County, Florida, built in 2001. It carries a Significant hazard potential classification.

About F3a Four Corners Mine

The primary purpose of F3a Four Corners Mine is tailings. Tailings dams contain waste material from mining operations — typically a slurry of finely ground rock left over after valuable minerals have been extracted. These structures require ongoing monitoring because tailings can contain heavy metals and other contaminants. The dam is owned by The Mosaic Company (private). It impounds the Myakka River near Duette.

The dam stands 68 feet tall and stretches 19,866 feet across, creates a reservoir covering 571 acres, has a maximum storage capacity of 37,500 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 2001, the structure is relatively new.

This dam has a significant hazard potential classification, meaning that a failure could cause significant economic damage — flooding roads, bridges, or property downstream — but is not expected to result in loss of life. An emergency action plan is in place for this dam. The most recent inspection on record was 01/23/2006. That was over 20 years ago.

At 68 feet, this dam is taller than 96% of all dams in the United States.

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Significant HazardNot Rated ConditionEmergency Action Plan: Yes

Location

StateFlorida
CountyManatee
Nearest CityDuette
River/StreamMyakka River
Coordinates27.63030, -82.07820

Physical Characteristics

Dam TypeEarth
NID Height68 ft
Dam Height65 ft
Dam Length19,866 ft
Year Completed2001 (25 years old)

Storage & Hydraulics

NID Storage37,500 acre-ft
Max Storage37,500 acre-ft
Normal Storage34,260 acre-ft
Surface Area571 acres
Drainage Area0 sq mi
Max Discharge80 cfs
Spillway TypeControlled

Ownership & Safety

PurposeTailings
OwnerTHE MOSAIC COMPANY
Owner TypePrivate
Hazard ClassificationSignificant
Condition AssessmentNot Rated
Last Inspection01/23/2006
Emergency Action PlanYes

Identifiers

NID IDFL11050
Federal IDFL11050
More InfoState Dam Safety Program

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