Main Stack is an earth dam located in Hillsborough, Florida, built in 1989. It carries a Significant hazard potential classification.
Dam profile
NID height · 103 ft103 ft tall and 12,968 ft long, taller than 98% of U.S. dams with a recorded height. Height is drawn to scale against a ten-story building, about 100 ft; the profile is a generic embankment section and the water level is illustrative.
About Main Stack
The primary purpose of Main Stack 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 Archie Creek near Gibsonton.
The dam stands 103 feet tall and stretches 12,968 feet across, creates a reservoir covering 251 acres, has a maximum storage capacity of 16,000 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1989, the structure is 37 years old.
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 09/07/2005. That was over 21 years ago.
At 103 feet, this dam is taller than 98% of all dams in the United States.
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Location
| State | Florida |
| County | Hillsborough |
| Nearest City | Gibsonton |
| River/Stream | Archie Creek |
| Coordinates | 27.87990, -82.38540 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 103 ft |
| Dam Height | 103 ft |
| Dam Length | 12,968 ft |
| Year Completed | 1989 (37 years old) |
Storage & Hydraulics
| NID Storage | 16,000 acre-ft |
| Max Storage | 16,000 acre-ft |
| Normal Storage | 15,000 acre-ft |
| Surface Area | 251 acres |
| Drainage Area | 0 sq mi |
| Spillway Type | None |
Ownership & Safety
| Purpose | Tailings |
| Owner | The Mosaic Company |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Not assessed |
| Last Inspection | 09/07/2005 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | FL10030 |
| Federal ID | FL10030 |
| More Info | State Dam Safety Program |