AJAX-HECTOR MINE POND - MN00000-3262

Incident ID MN00000-3262
Dam Name AJAX-HECTOR MINE POND
Downstream Hazard Potential
State MN
Incident Date 04/24/2018
Incident Type Failure
Incident Driver Hydrologic/flooding
Incident Mechanism 1 Animal Activity
Incident Mechanism 2 Debris Clogging
Incident Mechanism 3 Overtopping
Incident Description Tributary stream meandered into abandoned mine pit during spring snowmelt causing partially filled mine pit to completely fill and overtop natural earth embankment. Embankment failed, draining pit into the Embarass River and causing damage to utilities and water quality issues on Embarass Lake.
Named Hydrologic Event
EAP Enacted (Y/N) due to Incident No
Fatalities (Number) 0
Number of People Evacuated 0
Number of Habitable Structures Evacuated 0
Number of Habitable Structures Flooded 0
Other Infrastructure Impacts Other
Economic Damages (in $) $100,000 to $500,000
Volume released at failure (ac-ft) 100 ac-ft
Response Property was abandoned by mining company decades ago and is now owned by state (IRRRB). Rebuild of trail over $1,000,000.
Additional Remarks or Updates The "dam" is a 250 foot section of natural ground between an excavation related to the mine pit and an excavation related to the diversion channel of the Embarrass River. Damage to Utility (power, telephone, water supply and sewer) lines severed. Tailings and raw sewage from severed sewer line entered lake downstream of embankment failure. Paved trail washed out.
Incident Time
Incident Duration 1 day
Incident Report Produced Unknown
Information Sources MNDNR
Owner Type S
Dam Type OT
Primary Purpose(s) O
EAP NR
Year Completed 1945
Year Modified 0
Dam Height 55 ft
Max Storage (ac-ft) 150 ac-ft
Surface Area (acres) 9 acres
River Name OS TRIBUTARY TO THE EMBARRASS RIVER DIVERSION
Latitude 47.541
Longitude -92.3108
Regulatory Agency(ies) MNDNR
NID Number MN00000
Attachments