|
Incident ID |
AK00320-3593 |
|
Dam Name |
Lower Slate Lake Back Dam |
|
Downstream Hazard Potential |
S |
|
State |
AK |
|
Incident Date |
09/18/2023 |
|
Incident Type |
Non-failure |
|
Incident Driver |
Hydrologic/flooding |
|
Incident Mechanism 1 |
Overtopping |
|
Incident Mechanism 2 |
Spillway Deficiency |
|
Incident Mechanism 3 |
Other |
|
Incident Description |
9/18 a cofferdam protecting AK00320 embankment construction work was overtopped and an partially eroded allowing water to flow freely into the tailings reservoir. Water eroded portions fo the AK00320 construction works. On 10/8 A temporary diversion line failed due to high flows and pressure allowing water to flow freely into the tailings reservoir. |
|
Named Hydrologic Event |
|
|
EAP Enacted (Y/N) due to Incident |
Yes |
|
Fatalities (Number) |
|
|
Number of People Evacuated |
|
|
Number of Habitable Structures Evacuated |
|
|
Number of Habitable Structures Flooded |
|
|
Other Infrastructure Impacts |
|
|
Economic Damages (in $) |
|
|
Volume released at failure (ac-ft) |
|
|
Response |
|
|
Additional Remarks or Updates |
incident did not involve an uncontrolled release of contact water, but did have impact on the overall site water balance that took about a year to resolve. |
|
Incident Time |
7:00 AM |
|
Incident Duration |
approx 1 month |
|
Incident Report Produced |
Unknown |
|
Information Sources |
AK DNR |
|
Owner Type |
P |
|
Dam Type |
ER |
|
Primary Purpose(s) |
T |
|
EAP |
Y |
|
Year Completed |
2024 |
|
Year Modified |
0 |
|
Dam Height |
44 ft |
|
Max Storage (ac-ft) |
910 ac-ft |
|
Surface Area (acres) |
75 acres |
|
River Name |
East Fork Slate Creek |
|
Latitude |
58.8136 |
|
Longitude |
-135.04 |
|
Regulatory Agency(ies) |
AK DNR |
|
NID Number |
AK00320 |
|
Attachments |
|
