How tall is the waterfall of the grand coulee dam

In all instances there was found light-colored, dense granite, suitable, according to the board of consulting engineers, to bear any load that might be put upon it. After uncovering bedrock, additional exploratory work was done with Calyx drills, extracting rock cores 36 inches in diameter, which permits a detailed examination to be made of both the core and the hole from which it was taken.

Eighteen such holes were drilled to depths varying from 29 to 68 feet. Bedrock is quite uniform in character, and in general was prepared for foundations by the removal of weathered surface rock to a depth of 6 to 10 feet. To seal the cracks and crevices in the granite bedrock under the dam, formed millions of years ago when the molten rock solidified and shrunk, grout of cement and water is forced down through holes drilled into the rock.

Of such holes, 30 feet deep and 20 feet apart, five rows were drilled under the upstream edge of the dam and entirely across the river canyon. The rows were spaced 20 feet apart, and the holes in each row are staggered with respect to those in the next row. The foot holes were grouted under pressures up to pounds per square inch before any concrete was placed close to them.

After considerable concrete was in place on bedrock, a row of holes 75 feet deep and spaced 20 feet apart was drilled diagonally downward into the rook under the dam through the curved fillet of concrete which connects the upstream face of the dam with bedrock.

An effectual seal against leakage under the dam will be created by the grouting of these holes and a single row of holes feet to feet deep, to be spaced 10 feet apart and drilled from the drainage gallery in the dam close to bedrock. Grouting pressures in the deep holes may run as high as 1, pounds per square inch. As an added precaution against the uplifting effect of any leakage under the upstream edge of the dam, there will be one row of uplift pressure relief holes spaced 10 feet apart, permanently open into the drainage gallery at the base of the dam.

Section I. Top, left : Activity at the Grand Coulee Dam was at its peak in the summer of with more than 7, men at work. A short distance north of Coulee City the generally horizontal lava flows of the plateau dip sharply to the southeast, forming an immense wrinkle in the plateau surface before they again flatten out at a lower elevation. It is believed that the waters of the glacial Columbia River, flowing down this steep surface, initiated a waterfall which gradually cut its way northward and formed the rock trench known as the Upper Grand Coulee.

Eventually these ancient falls died out as they ate away the last of the rock barrier which separated them from the valley of the Columbia River. As a result the upper coulee intersects the south wall of the valley of the Columbia River about 1 mile south upstream from the site of Grand Coulee Dam. At this point the floor of the coulee hangs about feet above the level of the present river. The lower Grand Coulee was formed in a similar manner by retreating waterfalls which originated in the vicinity of Soap Lake.

Here, from the roadside or from a vista house in the park, one can look at the site of the ancient waterfalls, more than feet high and 3 miles wide, whose northward retreat cut the channel of the lower Grand Coulee. They are two and a half times as high and five times as wide as Niagara Falls, and according to some authorities the torrent of silt-laden water which poured over them is estimated to have had a volume as much as times that at the present Niagara Falls.

Two of the five largest recesses in the 3-mile northern brink of the extinct cataract are within view from the vista house. In the plunge-pools at the foot of the first are Fall Lake and Perch Lake. Cancel Submit. Get Citation. Contact Owner. It sits deep in the Columbia River Gorge of central Washington. It is located about 90 miles west of Spokane, miles South of Canada's boarder, and about miles east of Seattle.

About the collections in Calisphere Learn more about the collections in Calisphere. Copyright, permissions, and use If you're wondering about permissions and what you can do with this item, a good starting point is the "rights information" on this page. The most interesting place by far is Deep Lake, a long and thin lake of turquoise color nestled between high cliffs. A hiking trail begins at the parking lot trailhead, and travels through forest to overlooks of the lake.

The most interesting thing to do here, I was told, is kayaking. The long and narrow lake apparently has lots of fascinating nooks and coves to explore, and the scenery is difficult to beat. There are about 15 miles of hikes at Dry Falls, but I think my favorite route overall would be Umatilla Rock. The 5-mile trek, which is almost entirely flat, features striking desert and canyon views. The hike showcases Umatilla Rock, a gigantic pillar that stands tall while all else around it was eroded away by the floods.

This hike is definitely best in spring or fall — it was as hot as an oven when I visited in July. Zach Urness has been an outdoors writer, photographer and videographer in Oregon and the Northwest for 10 years.