Unimin Quarry Dam is an earth dam located in Jefferson County, Missouri. It carries a Significant hazard potential classification.
Dam profile
NID height · 25 ft25 ft tall, taller than 50% of U.S. dams with a recorded height. Height is drawn to scale against a two-story house, about 25 ft; the profile is a generic embankment section and the water level is illustrative.
About Unimin Quarry Dam
The primary purpose of Unimin Quarry Dam 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 Unimin Corporation (private). It impounds the Tributary to Sandy Creek near Herculaneum.
The dam stands 25 feet tall, creates a reservoir covering 4 acres, and has a maximum storage capacity of 40 acre-feet.
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.
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Location
| State | Missouri |
| County | Jefferson |
| Nearest City | Herculaneum |
| River/Stream | Tributary to Sandy Creek |
| Coordinates | 38.26426, -90.46160 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 25 ft |
| Dam Height | 25 ft |
Storage & Hydraulics
| NID Storage | 40 acre-ft |
| Max Storage | 40 acre-ft |
| Normal Storage | 33 acre-ft |
| Surface Area | 4 acres |
Ownership & Safety
| Purpose | Tailings |
| Owner | Unimin Corporation |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Not assessed |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | MO31987 |
| Federal ID | MO31987 |
| More Info | State Dam Safety Program |