Transmission lines will be de-energized after earlier outage
By Elaine Williams of the Tribune
April 20, 2011
A test module of Imperial Oil is scheduled to travel tonight.
The Idaho Transportation Department Tuesday lifted the ban it placed on the trip of the megaload from Lewiston to just inside the border of Montana.
That restriction was imposed April 12 after the transport hit an Avista support wire on U.S. Highway 12, triggering an outage that affected about 1,300 residents of the Pierce and Weippe areas for roughly five hours, according to Avista.
This time Imperial Oil indicated a “small number” of customers in the Kamiah area will experience an outage of five to 10 minutes.
The power will be out while two transmission lines are de-energized because of their proximity to the 3-story test module, said Pius Rolheiser, a spokesman for Imperial Oil.
If Imperial Oil gets permission to send other oversized loads on U.S. 12, repositioning the transmission lines could be a possibility, Rolheiser said.
The 24-foot-wide test module is parked at a turnout five miles west of Kamiah. It has been there while ITD waited for recommendations from the oil company and Mammoet, Imperial Oil’s contracted hauler, about how to make the remaining part of the trip go more smoothly.
A power distribution line crossing U.S. 12 at milepost 75, nine miles east of where the test module is now, has been raised, according to an ITD news release.
Additional checking to be sure there’s room for the transport to get underneath other overhead lines between its current location and the Montana border has been done.
More information surfaced about how the support wire got overlooked in two years of planning before the test module’s departure.
A conceptual drawing showed the test module didn’t have clearance for 3 feet on one side between the road’s fog lines where the support wire was hit, according to a report Mammoet submitted to ITD.
But other checks overlooked the potential issue on the section of U.S. 12 that’s three lanes. A height pole truck that drove the entire route missed it because the pole was mounted in the center of the bumper as dictated by industry standard, according to the report.
“East of the incident location the transport was approaching a right hand curve where the right hand lane was about to merge into a two lane configuration,” according to the report. “In anticipation of this, the load was traveling slightly left of center.”
The support line wasn’t the only thing the test module hit on its first outing. It also struck a limb on a tree in the Lewiston rose garden. “Lead escort vehicles will watch for overhanging tree branches in addition to other overhead obstacles,” according to a news release.
Plywood will be placed over metal traffic sign holders in the ground so the tires can go across them without getting hurt. That change will give the shipment more room to avoid tree limbs.
The sign holders sit flush to the ground and enable signs to easily be removed and replaced, Rolheiser said. A number of sign holders have been installed in Idaho to accommodate megaloads, Rolheiser said.
A tree-trimming subcontractor will travel the road and “ensure a clearance envelope of three feet off the fog line each direction and an overall height of 32 feet,” according to the Mammoet report.
The journey is intended to show U.S. 12 is a feasible route for oversized shipments. The test module, which takes up two lanes of traffic, has the same dimensions and weight as the largest of more than 100 rigs Imperial Oil wants to send on U.S. 12 to the Kearl Oil Sands in Alberta, Canada. At 490,000 pounds it is the third heaviest rig to travel U.S. 12.
The loads are accompanied by Idaho State Police officers at the expense of Imperial Oil and are supposed to pull over once every 15 minutes to allow traffic to pass.
Williams may be contacted at [email protected] or (208) 848-2261.