Centralia Coal Mine Dam No 20c is an earth dam located in Thurston County, Washington, built in 1981. It carries a Low hazard potential classification.
Dam profile
NID height · 10 ft10 ft tall. 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 Centralia Coal Mine Dam No 20c
The primary purpose of Centralia Coal Mine Dam No 20c 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 Transalta Centralia Mining LLC (public utility). It impounds the Tr-hanaford Creek near Centralia.
The dam stands 10 feet tall, creates a reservoir covering 16 acres, has a maximum storage capacity of 60 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1981, the structure is 45 years old.
This dam has a low hazard potential classification, meaning that failure would cause minimal damage, limited primarily to the dam owner's property, with no expected loss of life.
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Location
| State | Washington |
| County | Thurston |
| Nearest City | Centralia |
| River/Stream | Tr-hanaford Creek |
| Coordinates | 46.76884, -122.86374 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 10 ft |
| Year Completed | 1981 (45 years old) |
Storage & Hydraulics
| NID Storage | 60 acre-ft |
| Max Storage | 60 acre-ft |
| Normal Storage | 50 acre-ft |
| Surface Area | 16 acres |
| Drainage Area | 0 sq mi |
| Max Discharge | 218 cfs |
Ownership & Safety
| Purpose | Tailings |
| Owner | Transalta Centralia Mining LLC |
| Owner Type | Public Utility |
| Hazard Classification | Low |
| Condition Assessment | Not assessed |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | WA00534 |
| Federal ID | WA00534 |
| More Info | State Dam Safety Program |