Clay Hollow Slurry Impoundment Reservoir Report

Last Updated: December 5, 2025

Clay Hollow Slurry Impoundment, also known as Sapphire Slurry Impoundment, is a private-owned structure located in Polly, Letcher County, Kentucky.


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Summary

This tailings dam, primarily designed for storing mining waste, stands at an impressive height of 375 feet and spans a length of 1400 feet. With a storage capacity of 10,590 acre-feet, this earth dam poses a high hazard potential due to its sheer size and location.

Despite being under the jurisdiction of the Mine Safety and Health Administration, Clay Hollow Slurry Impoundment is not regulated by the state of Kentucky. This lack of state oversight raises concerns about the safety and maintenance of the structure, especially given its high hazard potential. With no available condition assessment or inspection data, the current state of the impoundment remains unknown, highlighting the need for increased monitoring and regulatory enforcement to prevent any potential environmental disasters.

For water resource and climate enthusiasts, the Clay Hollow Slurry Impoundment serves as a stark reminder of the importance of proper regulation and maintenance of industrial structures. As a privately-owned facility with no state permitting or inspection requirements, this massive tailings dam presents a significant risk to the surrounding area. With its high hazard potential and unknown condition assessment, there is a pressing need for increased oversight and accountability to ensure the safety and integrity of Clay Hollow Slurry Impoundment for both the local community and the environment.

Dam Length

1400

Dam Height

375

Primary Dam Type

Earth

Nid Storage

10590

Hazard Potential

High

Nid Height

375
       
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Dam Data Reference

Condition Assessment

Satisfactory
No existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
Fair
No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action. Note: Rare or extreme event is defined by the regulatory agency based on their minimum
Poor A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency. Investigations and studies are necessary.
Unsatisfactory
A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
Not Rated
The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Not Available
Dams for which the condition assessment is restricted to approved government users.

Hazard Potential Classification

High
Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
Significant
Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environment damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
Low
Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
Undetermined
Dams for which a downstream hazard potential has not been designated or is not provided.
Not Available
Dams for which the downstream hazard potential is restricted to approved government users.