August 5, 2022
Friday was a short day. We were all packed up and ready to go by 8 am. We could have hung out up there for an additional while, but, frankly, I was looking forward to a shower. Sweat, sunscreen, and bug spray would make a terrible cologne. And did I mention the mosquitoes?
I was a bit amused by questions from many of the hikers we encountered on our way out. At least three times I was asked if we camped. I think it’s pretty obvious that we camped: if you’re not camping, why would you be carrying a big backpack?
My other favorite type of question is along the lines of “Did you make it all the way?” or “Did you make it to the lake?” All the way to where? To which lake? There are a number of destinations on this trail: Calypso Cascade, Ouzel Falls, Ouzel Lake, Bluebird Lake, and some more beyond the trail’s end. I guess people get focused on where they’re going and assume everybody is going to the same place.
Because I keep track of when I get to each navigation point, I always have a pretty good idea of how long it’ll take me to get back to the trailhead. Sometimes, the last half hour of the hike out can be a mental struggle. Time seems to stretch. Particularly on the third day of hiking, I’m pretty fatigued. I just keep telling myself to put one foot in front of the other. This time, thinking I’d just about gotten back to the parking lot, a large group of young kids was hiking in. They were singing 99 Bottles of Beer. I’ve hated that song since junior high school, but it cheered me up. They were on 71, so I knew I only had 29 bottles of beer to go before I was finished!
I didn’t take any pictures on the hike out. So here are a couple more slideshows. The first is some of the flowers I came across over the three days.
More flowers, but with pollinators!
Readers who have been paying attention may be wondering if there’s a missing timelapse video. It’s not missing, I’m just spreading them out. This is the second angle I shot sitting at Bluebird Lake the first afternoon.
As I said in an earlier entry, the dam at Bluebird Lake was removed in 1989-90 when they airlifted out five million pounds of concrete and reinforcing steel. I couldn’t help but wonder how they got the five million pounds in there. (Yes, I know they didn’t bring that much in. They’d have sourced the water, sand, and aggregate on-site.)
Concrete is cement, water, sand, and aggregate. What machines do you need to build a concrete dam there? How many men were on the crew? How do get all the men and materiel up there without a road? For Sandbeach Lake, they built a road and there are stretches of trail today where you could easily drive a two-wheel drive SUV. There’s nothing road-like on the hike to Bluebird.
Back in 1922, the lead engineer on the project wrote a small article for an engineering magazine – just a few paragraphs – about transporting materials to the dam site. The dam had a structural height of 58 feet and a hydraulic height of 55 feet. It was nearly 150 feet long.
The engineer tells us that they can only work between July 14 and September 10 and that it took three years. He also mentions that everything had to be transported six miles, which tells me the trucks were being unloaded at the current trailhead, or the old cabin or thereabouts.
There was no sand on site, so they needed a rock crusher and an automobile engine to run it. They took these machines apart and hauled them up on burros. Each season they had to transport two thousand bags of cement, on burros. And they needed the rebar. This was tied in bundles and a bundle was attached to a wagon axle, the other end dragging on the ground. The axle was drawn by a team of four horses and the driver balanced on the axle.
Each burro carries two bags of cement. The season is 56 days, which means an average of 36 bags a day, or 18 burros. (Presumably, these are 50-lb bags. They probably didn’t carry more than a hundred pounds each.) The rock crusher engine needs fuel, so more burros carry cans of gasoline.
We don’t know how big the crew was, or where they stayed. Did the crew commute the twelve-mile round-trip every day, or did they have a camp on-site? If they camped, the tents and field kitchens needed to go up each season, and food and other supplies for the duration. And they’d have needed to have a latrine on-site.
In any event, every day for fifty-six days a year, give or take, you’d have round-trips for a four-horse team, twenty or twenty-five burros and their muleskinners (or whatever the proper term is for burros), and an unknown number of men.
I don’t know anything about burros, but I imagine they can go where I can go. But I’m doubtful about that four-horse team dragging a wagon axle. At least not above where our campsite is, not where the trail is today.
The dam (originally named Arbuckle #2) was built as an element of Longmont’s irrigation system, as were the several other dams that used to be in the Park. They were all removed in the aftermath of the Lawn Lake flood. Parts of the berms are still standing at Lawn Lake and Sandbeach Lake. Those lakes, as well as Pear Lake, all still have obvious bathtub stains.
At Bluebird, when you stand a short distance from the inlet on the north side and look back to where the trail dumps hikers onto the shore of the lake, you can see where the dam used to be. It’s been gone 32 years. Why isn’t there a more noticeable bathtub ring?
The Bluebird Lake dam was inspected a week after Lawn Lake failed. The water level was forty-two feet below the top of the dam, or just under fourteen feet deep at the lower outlet. The dam’s lower outlet was six feet below the lake’s original outlet. That may or may not be where the current outlet is, but it can’t be far. The upper outlet was larger, near the center of the dam, twenty-five feet below the crest. So, in 1982, the lake was only eight feet above its level before the dam was built. It must have been that empty for a long time before 1982.
Which evidently was a good thing. The inspection report stated that the thin mortar on the faces and crest was spalled off over extensive areas. “Lift lines” are the horizontal lines between the layers that occur between concrete placing cycles. There was significant erosion on the downstream face along the lift lines and the lift lines were probably unbonded.
As well, the concrete in the structure was poor compared to other similarly constructed dams of the same time. A pocket was found on the upstream face that was twenty-one inches deep. Several places tested with a geologist’s pick showed very little cementitious material. In places, the plum stones (those up to nearly a foot in diameter) were too numerous and placed closer to the face than allowed by the specifications.
The city of Longmont sent men out every year to clean the outlet, which had a tendency to collect a buildup of material. The city said the lower outlet had been inoperable in 1974. At the time of the inspection, the upper outlet had been dismantled: missing the drive gear, shaft, and crank assembly.
If the dam was in such sad shape in 1982, why wasn’t it taken out before? Today, concrete dams must be inspected every 3-5 years. I don’t know if it was different fifty years ago, or if, because of the low water level, it was considered out of commission and didn’t require inspections. I can only surmise that, with the water level not much higher than it was originally, it was felt that the danger of failure was minimal and that Button Rock Reservoir could handle it. But I find it hard to believe its general condition was not well known.
It’s unfortunate I never hiked there when the dam was still standing. I’d been as far as Ouzel Falls in the 80s, but at the time, I considered a twelve-mile roundtrip hike out of my range. Ah, my “misspent youth”.