Centralia Coal Mine Dam No 3a
Centralia Coal Mine Dam No 3a is an earth dam located in Lewis County, Washington, built in 1970. It carries a Low hazard potential classification.
About Centralia Coal Mine Dam No 3a
The primary purpose of Centralia Coal Mine Dam No 3a 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.
The dam stands 18 feet tall, creates a reservoir covering 30 acres, has a maximum storage capacity of 79 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1970, the structure is well into its service life at over 50 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. The most recent inspection on record was 07/03/2001. That was over 24 years ago.
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Location
| State | Washington |
| County | Lewis |
| River/Stream | Tr-hanaford Creek |
| Coordinates | 46.74649, -122.84457 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 18 ft |
| Year Completed | 1970 (56 years old) |
Storage & Hydraulics
| NID Storage | 79 acre-ft |
| Max Storage | 79 acre-ft |
| Normal Storage | 60 acre-ft |
| Surface Area | 30 acres |
| Drainage Area | 0 sq mi |
| Max Discharge | 98 cfs |
Ownership & Safety
| Purpose | Tailings |
| Owner | TransAlta Centralia Mining LLC |
| Owner Type | Public Utility |
| Hazard Classification | Low |
| Last Inspection | 07/03/2001 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | WA00289 |
| Federal ID | WA00289 |
| More Info | State Dam Safety Program |