| Dam Name | Wanapum |
| Incident Date | 2/25/2014 |
| Country | United States |
| State/Province | Washington |
| Dam Height (m) | 28.3 |
| Uncontrolled Release of the Reservoir | No |
| Dam Type | Concrete; Rockfill; Gravity |
| Detailed Dam Type | |
| Incident Type | |
| Incident Description | Following the discovery of movement at Pier 4 between Gates 3 and 4 on February 25, 2014, an in-depth investigation and evaluation of the spillway was initiated as well as lowering of the reservoir pool. In addition to inspections by Grant County PUD staff, private consultants and OEP staff, an underwater inspection of the concrete monolith which contains Pier 4 was conducted by divers. On February 27th while inspecting the upstream face of the Pier 4 monolith, divers discovered structural damage in the location of an existing construction cold joint across the monolith face located about 75 feet below the water surface. The construction joint was reported to have developed into a crack with a 2 inch vertical opening and a 1-1/2 inch downstream offset. This crack extends across the entire width of the monolith. Although underwater inspections are still underway, preliminary indications are that the crack may extend through the monolith to the downstream face. As a precautionary measure, the PUD lowered the reservoir 3.5 feet beginning on February 25th and is in the process of lowering the reservoir pool further to El. 560 feet with further drawdowns possible. This will result in 11.5 feet of total drawdown. The latest alignment surveys taken over the last two days have not shown any additional movement of the spillway section. Engineers continue to evaluate the damage and appropriate corrective measures. The PUD is working to assemble a Board of Consultants to investigate the crack and movement and recommend repair options. Wanapum Dam is a high hazard potential dam and is located on the Columbia River in Kittitas County, Washington State. Both Wanapum Dam and Priest Rapids Dam are developments of the Priest Rapids Project, FERC No. 2114. |
| High Level Failure Mode | |
| Lessons Learned | |
| Initiating Event | |
| Initiating Event Description | |
| Structures/Components | |
| Failure Mode Description | |
| Emergency Action Plan Implemented | Unknown |
| Consequences | Consequence Data Unavailable |
| Geographic Coordinates - Decimal Degrees | 46.8731, -119.9703 |
| Normal Reservoir Storage (m3): | |
| Crest Elevation (m) |