Friday, January 4, 2013

Deep in Dworshak (Part I)

This photo is of one of the many tunnels in Dworshak Dam’s interior. With pumped in air to breathe, maintenance workers walk on a narrow concrete pavement. Sometimes one has to step over stalagmites on the flooring and above one’s head stalactites hang. The mossy granite walls display holes that were drilled for explosives. Many of the plugs taken from the holes are now in a pit at Dworkshak Fish Hatchery below.

By Alannah Allbrett

A huge lichen-covered boulder guards the entrance; moss and ferns grow beside the mysterious portal. Granite surrounds us as we step into the dank tunnel with a noticeable aroma somewhat like a fishy/earthen basement. A string of dim lights, like dusty pearls, precedes us as we descend along a narrow concrete walk with water on either side of it trickling along the granite facing. I reach out at one spot to touch the wall and pull my hand back quickly from the squishy, wet surface. I guess I wasn’t expecting my fingers to sink into the green ooze.

I am reminded to ‘watch my step’ as we gingerly step over the occasional green slick area. Periodically, a cold droplet of water smacks me on top the head just to keep me humble. I, with my guide, Lead Park Ranger Deb Norton, am being lead to what looks like Gollum’s [of Lord of the Rings fame] cave.

We walk for what seems like a quarter of a mile, to where the pathway takes a sharp turn right, and we proceed, ever downward. I hear water dripping, echoes from my own questions, and the sound of a blower Deb turned on that provides air to would-be travelers to the nether regions. I am on a mission to view what only a handful of people ever see – the diversion tunnel of mighty Dworshak Dam, the highest straight axis, concrete gravity dam in the U.S. and the states’ third tallest dam (as opposed to Hoover Dam which is curved or arch gravity dam).  

The diversion tunnel was built before the dam, by blasting through solid granite, to make a passage for the clear, pure waters of the North Fork of the Clearwater River, known to locals merely as the North Fork. The headwaters of this magnificent river begin in the Bitterroot Mountains, along north central Idaho’s Montana border, and flow 135 miles and are captured behind Dworshak.

I am using the handrail, mainly because I don’t want to make an idiot of myself by tripping. Deb is used to this kind of thing and marches confidently before me. We keep going downward, and I make a mental note to myself to try to keep up on the return to daylight and outside air – I know it’s going to be like being on an inclined treadmill machine. She assures me that her knees are younger than mine – how does she know that? I wonder as I puff along.

As we get to the bottom, I look upward and all around me as I stand at a guardrail, over what appears to be water. I’m not quite sure. The water is so clear I think I’m looking at the ground floor of this immense cavern in which one could put an airplane or two.

This is it! I am officially in Gollum’s cave. Look there’s his boat – a little two Hobbit craft tied up at the dock. Though we have an electric light above us, the light gets lost in here – it fades off into the distance and gets swallowed by the walls which know it doesn’t belong. The light and we are intruders in the belly of some huge beast.

I strain my eyes to try to see into the far reaches of blackness. Deb points out the water below and says that with no current, it stays crystal clear. This is the place where engineers rerouted a whole river so that they could construct the dam; the water had to go somewhere. They keep the boat there so they can inspect the tunnel and follow it end-to-end for any maintenance that might be needed.

It’s time to leave, and Deb turns to go back up the passageway the way we came in; I take one last look knowing I will probably never return here again.

Over my shoulder, it turns black inside the cavern. “I didn’t do it” says my guide. The lights are obviously on some kind of timer or motion detector – who knows? But it’s black in that hole, that much I can say for sure. We have, of course, the lights along the walkway which show the pathway back to the entrance. Gollum’s sanctuary and secrets are safe once more from intruders into this quiet place that time has forgotten – the place where men sweated, set dynamite caps, removed acre feet of rock, risked their lives – all so that a dam could be built.

The building of Dworshak, would also build-up the little logging town of Orofino that hosted hundreds of workers with their families, taught their children in school each day, the town that expanded in every way to encompass the construction of this massive structure which was dedicated in 1973 to Henry Dworshak (1894-1962), an Idaho State Senator who was very helpful in finding funds for the project.

My tour includes standing atop the dam, looking out across the huge reservoir, looking down the face of the structure, and on down the canyon ravine where the river is the delight of fishermen who come to the “steelhead capital of the world.” Speaking of fisherman, Deb points toward the base of the dam and tells me ‘x’ number of people are fishing down there on “Fisherman’s Wall.” I don’t see any – not a one, until she points out what appear to me to be fence posts. The height of the dam, at 717’ high, is deceiving. It really doesn’t seem like that far down until one mistakes human beings fishing as fence posts, then one realizes that this is one BIG puppy of a dam.

As a child, my father was a dam keeper in Oregon, where I spent an enterprising summer selling grasshoppers as bait to the fishermen there. Each morning, at 4:30 a.m., my dad radioed the water measurements to the dam below us. He would be told the amount to lower or raise the dam gates – which he did by hand, cranking them manually. This ain’t that!

Dworshak can hold 3 ½ million acre feet of water at “full pool” when the reservoir is at its highest. Each acre foot is similar to a football field filled with one foot of water. And, if you aren’t impressed by that, there is enough concrete in this concrete gravity dam to build a sidewalk 5” thick and 36” wide around the world at its fattest part – the equator.

As my guide and I drive across the top of the dam to what’s known as the North Tower, the way ahead is blocked by workers’ vehicles. Apparently there is some kind of problem with a pipe that supplies water to Clearwater Fish Hatchery below which – gets the water – to grow the fish – that fill the waters – that bring the fishermen/women – to take home the fish – for smoking, or trophies – that hang on their walls – that come from the house that the Corps built. So, Deb stops her vehicle and proceeds to make a five point turn – it’s on top of a dam after all – it takes a little maneuvering.

Deb takes me inside the tower that houses an interesting exhibit. It is nearly a floor-to-ceiling glass-fronted display case (8’ x 15” diorama) with a mock-up miniature display of the dam site under construction. Someone had the smarts to construct this instructional replica which I wish everyone could view. In order to supply the concrete, an onsite quarry had to be built first. After rock was blasted free, it was loaded into dump trucks and hauled to a hole called the “Glory Hole” where it was put into a rock crusher.

The rock crusher was able to reduce four foot boulders into six inch fragments at the rate of 2,000 tons per hour. Without going into a lot of statistics, the crushed rock went into Dworshak’s own concrete plant. The first bucket of concrete was poured on June 22, 1968, and the last on January 26, 1973. The dam is the largest one ever constructed by the U.S. Army Corps of Engineers, which maintains it today.

Come back next week, as Paul Harvey used to say for, “the rest of the story,” wherein we continue my tour, include the Visitors’ Center, and hit you with more fun facts about one of the most amazing structures in North America – Dworshak Dam.

A lichen covered boulder stands sentry duty at the entrance to Dworshak’s Diversion Tunnel which was built prior to the dam to divert the waters of the Northfork of the Clearwater River.

Just inside the entrance to the Diversion Tunnel, one meets with a biosphere of live ferns growing in the cave like interior.

The “Glory Hole,” as it was called, was constructed to drop broken rocks into the rock crusher below. The rock crusher was capable of reducing four foot boulders into six inch fragments at the rate of 2,000 tons per hour.

In a picture, dated June 22, 1968, dignitaries drop the first official bucket of concrete, beginning the construction of Dworshak Dam in north central Idaho. The dam was completed in January of 1973. It took four one-half years of pouring concrete continuously 24 hours a day, seven days a week, averaging 10,000 cubic yards per day to complete this massive project.

A look upward at Dworshak’s spillway. The dam’s height at 717’ is deceptive. People at the bottom look like tiny little twigs. The width of the dam across the base is 550’ and houses an elevator, and many hallways and tunnels.

This photograph shows the Diversion Tunnel under construction. Air lines went in to operate the jack hammers.

No comments:

Post a Comment