Centralia Coal Mine Dam No 6b

Centralia Coal Mine Dam No 6b 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 6b

The primary purpose of Centralia Coal Mine Dam No 6b 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 13 feet tall, creates a reservoir covering 15 acres, has a maximum storage capacity of 74 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. An emergency action plan is in place for this dam. The most recent inspection on record was 07/03/2001. That was over 24 years ago.

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Low Hazard ConditionEmergency Action Plan: Yes

Location

StateWashington
CountyLewis
River/StreamTr-hanaford Creek
Coordinates46.74861, -122.84474

Physical Characteristics

Dam TypeEarth
NID Height13 ft
Year Completed1970 (56 years old)

Storage & Hydraulics

NID Storage74 acre-ft
Max Storage74 acre-ft
Normal Storage62 acre-ft
Surface Area15 acres
Drainage Area0 sq mi
Max Discharge69 cfs

Ownership & Safety

PurposeTailings
OwnerTransAlta Centralia Mining LLC
Owner TypePublic Utility
Hazard ClassificationLow
Last Inspection07/03/2001
Emergency Action PlanYes

Identifiers

NID IDWA00290
Federal IDWA00290
More InfoState Dam Safety Program

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