Jump to content

Dam Benchmarks

Recommended Posts

Sometimes things just fall into place and things go so well, you just have to do a little crowing!


Well, this is one of those times! We got access to the Glen Canyon Dam and have posted recovery logs on 8 of the benchmarks there. There are several others still waiting to be recovered, but according to the security guard who accompanied us on our quest, they require special permission and you CANNOT be on foot the entire time it would take to make those recoveries. The tunnel is about 2 miles long and drops about 600 feet in elevation. Someday we might get those.


We had an appointment at 9AM on last Thursday at the Carl Hayden Visitor Center. We arrived a bit early due to screening with metal detectors and having to sign in. Everything went smoothly and we then met our escorts. One was a Security Guard and the other was a Tour Guide who had worked at the dam for 20 some years before retiring so he knew the dam very well


The first stop on the journey was maintenance to get hard hats for everyone. While we were doing that it was mentioned that there was a benchmark right under the visitor center. Our escorts decided that would be a good one to start with. They led us through a couple rooms and through a door that opened directly below the observation area of the visitor center. We walked over near the edge of the canyon and looked to the south of each of the pillars, but saw no benchmark. We then walked along the edge of the canyon rim and within 100 feet saw some old pipes stuck in the sandstone. Right next to the pipe at the edge of the rim was the disk we were looking for. Due to its location, I was sure this one would be off limits. What a way to start the recovery quest! Even if we didn't find any other marks, this one would have been enough to make the trip worth the effort.


GP0101 - W 53


From that mark it was back inside and down an elevator to the top of the dam. As we approached the elevator the security guard said that the elevator was out of order. The tour guide then allowed as how there were stairs that go all the way to the bottom of the dam (about 740 feet). Sure enough there was a sign saying out of order and security tape blocking access to the elevator! We were then treated to the surprise of using the maintenance elevator at the other end of the dam.


We had a map showing the approximate location of each of the benchmarks and used that to determine the order in which we recovered the rest of the benchmarks.


We did 8 recoveries - 6 finds and 2 notes. We posted pictures for all recoveries. For the 2 notes 1 was a possible find, but we could not get close enough to say for sure due to security issues. We believe that if it is approached by boat it should be an easy recovery if one has permission to be there. The other note is for one that is on a ledge and the original picture when enlarged suggest where the disk is most likely located. Since one would need to repel down the canyon wall to access it, I doubt you would get permission for that recovery! The picture we posted has an arrow pointing to where we think the disk is located.


GP0117 - BW 10


GP0116 - BE 16


GP0121 - A 402


GP0115 - Y 405


GP0118 - W 405


GP0119 - X 405


GP0122 - Z 405 (Set vertical in the dam)


2 hours to walk about 2 miles and do 8 recoveries. A great way to spend the morning.


John & Shirley

Link to comment

Since we don't submit reports to the NGS, I wonder if we could get Dave D. to correct an error on the datasheet for Z 405?


Has anyone else notice what this error is?


The error is 9,500,000 + tons in size, just a little error. :lol:




After studying the datasheet it occurred to me that this would be something that could be used as the target for the upcoming contest.


Time to start practicing your sorting for this 'attribute' of the benchmarks in your area.



Link to comment

Would this be another hint?


Tighten up those stretch marks!

Get out and hunt for bench marks!

The sedentary, passive

life leads from light to massive.


Very great finds, by the way. Wonderful to read about.





That indeed would be an excellent hint.





Link to comment

Great trip success and report. Reading your logs, I think it'd be good if you expanded a bit like you've done here. It would add to future viewers' appreciation.


In my log of HR0808 on O'Shaughnessy Dam at Hetch Hetchy, I wrote

"Setting: light structures

Stability: Mark of questionable or unknown stability"

I truly hope not - it's set into a dam that's 900 feet wide and 300+ feet tall.


I know that it will probably be breached in a few millenia (if not torn down); but I generally consider it a stable, heavy structure. Very similar to the situation here.


I notice that Klemmer and Wintertime have also visited this one.

Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...