|
Incident ID |
AZ00059-3492 |
|
Dam Name |
MILLET SWALE |
|
Downstream Hazard Potential |
H |
|
State |
AZ |
|
Incident Date |
07/24/2021 |
|
Incident Type |
Failure |
|
Incident Driver |
Malfunction Of Equipment/gate |
|
Incident Mechanism 1 |
High Reservoir Level |
|
Incident Mechanism 2 |
Piping |
|
Incident Mechanism 3 |
Animal Activity |
|
Incident Description |
Heavy, localized monsoon activity resulted in rapid inflow to the reservoir. Continuous leak erosion/piping possbly along a defect in the embankment such as a crack or animal burrow. No corrective actions were taken at the dam when the leak was first detected. The gate was not completely open and is believed to have malfunctioned. A leak was observed from the lower portion of the downstream slope which eventually developed into a full breach, approximately 50-60 feet wide. |
|
Named Hydrologic Event |
|
|
EAP Enacted (Y/N) due to Incident |
No |
|
Fatalities (Number) |
0 |
|
Number of People Evacuated |
Unknown |
|
Number of Habitable Structures Evacuated |
Unknown |
|
Number of Habitable Structures Flooded |
Unknown |
|
Other Infrastructure Impacts |
Unknown |
|
Economic Damages (in $) |
Unknown |
|
Volume released at failure (ac-ft) |
990 ac-ft |
|
Response |
Dam owner did not notify the State agency of the leak at the downstream face. State employee from the area heard about the incident and the State contacted the owner who confirmed the leak from the dam. State agency was notified in the evening of July 25, 2021 of full breach of the dam. |
|
Additional Remarks or Updates |
Site visit on July 26, 2021 with representatives from state agency, the owner, and Navajo County Flood Control. A plan of action was developed where it was agreed the next steps would be to stabilize the breach with riprap and install ALERT gages both at the breach and upstream. |
|
Incident Time |
7:00 PM |
|
Incident Duration |
Hours |
|
Incident Report Produced |
No |
|
Information Sources |
ADWR |
|
Owner Type |
P |
|
Dam Type |
RE |
|
Primary Purpose(s) |
CI |
|
EAP |
N |
|
Year Completed |
1958 |
|
Year Modified |
0 |
|
Dam Height |
35 ft |
|
Max Storage (ac-ft) |
2800 ac-ft |
|
Surface Area (acres) |
125 acres |
|
River Name |
MILLET SWALE |
|
Latitude |
34.4306 |
|
Longitude |
-110.041 |
|
Regulatory Agency(ies) |
ADWR |
|
NID Number |
AZ00059 |
|
Attachments |
|
