Nicholson’s work will be focused on reconditioning foundation drains by core drilling 3.375-inch diameter holes on both dams that may be experiencing reduced flows or blocking by unknown materials or foreign objects including calcium carbonate deposits.
Priest Rapids Dam’s scope includes 128 drain holes located in the upstream gallery at the dam’s powerhouse and left bank fish facilities. Wanapum Dam will have 290 drain holes drilled in the upstream gallery.
Other work scopes for the project included flow and pressure measurements on all drain holes and video inspection on selected holes.
Previous projects with Grant County PUD include post-tensioned anchor installation to repair a crack in Wanapum Dam’s spillway and several projects, including investigative coring, for Priest Rapids Dam.
Nicholson’s portion of the work on Priest Rapids Dam will be completed by December 31 and at Wanapum Dam in May of 2020.