Jet grouting has brought Wickiup dam in line with seismic safety standards and, according to USBR, provided the best possible fix with minimal impact to the reservoir and surrounding areas.

‘This method [jet grouting] eliminated the need for reservoir restrictions and it saved millions over the estimated cost of the removal and replacement alternative,’ said USBR safety of dams programme manager Larry Wolf.

The Association of State Dam Safety Officials chose the work to receive its Rehabilitation Project of the Year award, and presented the prize to contractors during its annual conference on 28 September.

Earlier risk analyses highlighted an ‘unacceptably high’ potential for failure of the earthfill dam and significant loss of life in the event of an earthquake.

Engineers employed a computer programme to evaluate deformation patterns and evaluated 10 earthquake ground motions at five cross sections within the area to determine the geometry of treatment.

Attention to environmental protection around the dam, located on the Deschutes river, also played a part in the project’s award. Measures included the conversion of a large borrow area into an open body of water to provide new habitat space for animals and the construction of perches for bald eagle along the dam crest.