I-90 rock blasting

by guest blogger Amanda Sullivan

The first rock blast on I-90 Snoqualmie Pass happened on June 15, 2010 at approximately 8 p.m. Crews are using standard, conventional and proven blasting techniques with waterproof explosives. Crews drilled holes in the rock slopes to establish a pre-split line. This pre-split line serves as a guide to where the “finish line” of the rock cuts are to end, which is why the blast appears to occur so far back on the slope. After drilling holes and establishing the finish line, crews  placed 500 pounds of explosives in the holes. They then detonated the explosives and set off the controlled blast. The explosives fractured and cracked the rock of an area about 120’ by 120’ by 24’ deep, or about 12,800 cubic yards. Crews kept the blast small and manageable to better control the amount of material being removed. After the blast, crews used large equipment to safely remove the rock from the slopes and haul it away. The material will be recycled to construct the new lanes on I-90. But enough about the details, here's the video of the blast:

From now until October, crews will blast and excavate one million tons of rock from the slopes adjacent to I-90 near the Lake Keechelus Snowshed (milepost 58) in order to widen the highway from four to six lanes. Blasts are currently schedule to occur every Monday and Thursday evenings around 8 p.m. Crews may also blast on Tuesdays and Wednesdays. Since construction schedules and activities can change day to day, WSDOT urges motorists to plan for up to one hour delays on blast nights from 7:30 p.m. to 9:30 p.m. For more information about blasting closures and the I-90 Snoqualmie Pass East Project, please visit: www.wsdot.wa.gov/projects/i90/whatshappening