Wanapum Dam Repair

Wanapum Dam Repair

Con-Tech Systems (CTS®) was very proud to receive the contract from Nicholson Construction to supply the Strand and Bar Anchors used to repair the large crack in the existing Wanapum Dam, located in Washington State. 

The Strand Anchors needed for this project consist of 61 strands per anchor, 0.6”, 270 KSI, ASTM A416 Low Relaxation strand. The largest and longest anchors were pre-fabricated, coiled and shipped by truck directly to the jobsite. CTS® also supplied the 2,200 Ton stressing jack used on site to test and tension the anchors.

Two sizes of high strength Grade 150 DCP Bar Anchors had to be pre-fabricated; 2.5” and 3” in short lengths and spliced together at the job site because of logistic restraints.  Reusable grouting packers supplied by CTS® controlled the stage grout level and spillage of grout into the water.  Most of the Bar Anchors had to be installed and stressed under water by divers.


WANAPUM DAM REPAIR By Nicholson Construction:

The Wanapum Dam is an 8,000 foot long structure that spans across the Columbia River located just a few miles South of Vantage, Washington. In February of 2014 a crack that was 2 inches wide and 65 feet across was discovered along the face of the Dam. The reservoir above Wanapum was immediately lowered in an effort to relieve the pressure on the crack, and after a 26 foot pool elevation drop the crack closed itself. While the change in pool elevation did improve the stability of the dam it also rendered the hydro generator and fish ladders significantly limited or even inoperable.
Nicholson started work at the Wanapum Dam in April of 2014. The scope of work at that time was to drill exploratory core holes from the dam gallery for design input for the future tendons that would eventually be required for the repair. Since that time in April, Nicholson has mobilized over 40 people and 8 drill rigs to the site and worked around the clock on multiple drilling activities in order to complete the repair work required to raise the pool to normal operating level.   

The scope of the repair work for the Wanapum Dam includes: 35 each – 61 strand anchors that range from 230 to 260 feet, 70 each – permanent bar anchors installed and stressed underwater, 2 separate drilling and grouting programs to seal the cracks from within the dam gallery, and additional drilling and installation of instrumentation and monitoring instruments. 


See video link for a very informative and interesting recap: 

Click here to read the informative Foundation Drilling Magazine Article on this project written by Paul Krumm: http://foundationdrillingmagazine.com/jan2016/index.html  on pages 14-19.

Please visit our newsletter link in the main menu of our Home page for further information on other projects like this one explained further here: Februray 2015