Quandary talks rocks | SummitDaily.com

Quandary talks rocks

Where did the rock for the dam come from ?

Concerned our dam isn’t locally grown? Well, you are in luck my friend. I’m not saying I can account for every stone that’s been thrown in that water, but construction of the dam was done primarily with local rocks. Yep, I sat high in these hills and watched people tinker away with rocks for that giant sand pit for many a year. The Dillon Dam is an earth dam, and sits on rocks that have been faulted, fractured and organized to create a boundary. This means the majority of the dam is made up of the dirt and debris that’s been kicking around this county for generations.

That’s a good thing, because it gave the folks at Denver Water plenty of resources to tap into. The Dillon Reservoir is the largest of Denver Water’s reservoirs and was so big it required federal negotiations when being built. Initially, the dam was planned as only a small holding, but once Denver Water went to all the trouble of purchasing and moving the town of Dillon, they decided to go a little bit bigger. Makes sense right? You never see made-for-TV movies where a whole town is bought up for some insignificant little reason. If you’re going to move a town, you’d better have something big to replace it with.

Once Denver Water decided to create such a large reservoir (3,233 surface acres to be exact) it was clear the federally regulated Green Mountain Reservoir would be impacted. Stories from the time tell of Dwight Eisenhower discussing the dam with his financial advisor while fishing in Colorado, but this old goat is a little skeptical of that idea. I mean, isn’t the point of fishing to avoid thinking on such serious subjects?

Regardless, the big old reservoir was given the go-ahead and construction took place over several years, finally finishing in December 1963. The majority of the dam is constructed from sedimentary rock, specifically sandstone and quartzites. However, these types of rock presented their own problems for the crew. The rocks were extremely brittle and tended to be prone to micro-fractures. This meant that all of these old rocks had to be grouted to create a water seal.

Now, there was a significant amount of concrete work that went into creating the Roberts Tunnel. The tunnel is what moves water from the Dillon Reservoir to the South Platte for consumption by those thirsty Denverites. The tunnel is really a 23.3-mile aqueduct which you can imagine took more than one trip with a cement truck to create. Again, a majority of the materials were harvested locally with workers digging out gravel for years as they mixed the concoction into cement, and then laid the tunnel down to Denver. So while everyone is on this new fandangled craze about ‘shop local’ and ‘go green,’ the big boys at Denver Water paved that path a half-century ago. They just had to get rid of the town in this particular sustainability model. I suppose there are worse ways to go about it.

Who knows, maybe some of those rocks are even organic. That’s a thing, right?

Have a question for Quandary? Send an email to quandary@summitdaily.com

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