Obligatory: This is where the second image in the article ("this is not a place of honor") comes from. It's also briefly summarized in the last few paragraphs. Worth a read on its own.
http://www.wipp.energy.gov/picsprog/articles/wipp%20exhibit%...
http://www.wipp.energy.gov/picsprog/articles/wipp%20exhibit%...
We'd be careful but if there was a "I have no mouth and I cannot scream" sort of horror lurking beneath we'd suffer the consequences no matter the warning.
One of the afterthoughts in that document even suggests that the most likely reason people would leave the place alone would be when people die of radiation sickness after breaking into it anyway. It just takes one group of really determined people with a decent amount of time on their hands to destroy the markers and everything else. If asked me how long I would guess until that happens, I'd say less than 100 years. If not then, how about if it's so scary that a religion arises that considers the area to be the home of an Adversary of some kind and destroys it in a holy war?
Yesterday an article on a "paint factory" claimed it to be 45,000 years old, FWIW.
There is a particularly good episode of 99% invisible (podcast) that talks about some of the challenges involved.[1]
[1] http://99percentinvisible.org/episode/ten-thousand-years/
Perverse and contrary monkeys that we are, there is no better way of ensuring that some future person will dig it up than to have all sorts of signs telling them not to do that.
> Of course we'd dig around. That's our human nature. We're curious.
If the WIPP messaging does its job, you will have at a minimum been warned that the contents of the vault are dangerous and will make you sick. If you've got the stuff needed to run a complex digging operation, you'll hopefully make something of the Level III and Level IV warnings. And, yeah, if you read all that stuff and decide to dig anyhow, good luck to you. At least it won't be a total mystery if your workers start to get sick.
If the message is simply: "There is something dangerous here", we'd probably ignore it. If the message is "There is waste from the fission of uranium buried here. It consists primarily of the isotopes I-129, Cs-135, ... Here is how the waste is stored and laid out ...", we'd be much more inclined to listen. That's what the original document proposes as well, that there should be a hierarchy of messages from "There's something dangerous buried here" to detailed descriptions of the nature and composition of the waste.
I think our best bet to actually convince a hypothetical future civilisation not to dig it up is an understated "FYI: This is radioactive waste. It's a pile of worthless stuff that will make you sick." in a few major languages. If we add more ceremony to the message, they may more likely to understand it, but I think they'll be less inclined to believe it. Why would we spend so much effort to protect something worthless?
And ultimately, how much is it worth to prevent a few excavators in the far future getting radiation poisoning? And for that matter how likely is the hypothetical series of events needed for this to happen? I think like many things to do with radiation, we're vastly overweighting the risks involved.
The idea of sending exotic signals with dramatic structures was just a brainstorming exercise that gets a lot of publicity because it seems exciting. But there's a definite risk that the waste would attract rather than repel innocent discoverers: