PBO Strainmeter Crews Ready for First Installation – Take Two!

Overview

June 14, 2005

PBO Strainmeter Engineers Bob Mueller, Mike Hasting, and Wade Johnson have been anxiously waiting for this week to arrive. After detecting unwanted noise while testing the first PBO borehole strainmeter during the first scheduled installation in March 2005, crews had to delay installation for “Unit 0” until the problem was identified and repaired. Once the unit was returned to the manufacturer’s labs in Australia, a small amount of condensation was detected in the instrument and was the culprit causing the extra noise. Since then, the problem has been repaired and the strainmeter sent back to the United States for this second installation attempt.

On Sunday, June 12, the strainmeter engineers met UNAVCO’s Equipment Manager, Chuck Kurnik, and the strainmeter vendor, Mick Gladwin, in Port Angeles, WA, to prepare for deployment to the Hoko Falls borehole site, located about 70 miles northwest of Port Angeles in a small town called Sekiu. Early Monday morning, crews loaded thousands of pounds of equipment and materials into four large trucks and headed back along the familiar route to Sekiu.

Having gone through the steps for the attempted installation back in March, the engineers were well organized and quickly became immersed in their work, each knowing what needed to be done and by whom. First, the derrick truck was strategically positioned and evenly leveled over the borehole, ensuring precise alignment of the truck’s cable with the opening of the hole. Meanwhile, a 500-gallon tank was flushed out and filled up with water that will be used to mix the many bags of grout and concrete. With the exception of a clogged line in the hydraulic motor used for the capstan, the set up and unloading of equipment went smoothly. Before wrapping up the workday, crews lowered a heavy weight attached to marked cable into the borehole to find depth of the hole. Often, sediment or other residue can build up in the bottom of the hole, shortening the total depth. Amazingly, the hole measured at 546’ 8” (166.7 meters) – just about at the exact depth that crews drilled the hole back in December 2004. Crews left the site just after 7 PM, ready to begin some major construction work the next day. If all goes smoothly and the testing of the strainmeter is positive, the first PBO strainmeter could be lowered into the borehole as early as Tuesday, June 14, 2005.