Dug up two of my caches today and results not so good

[bacpacker]

Threads are likely, but condensation...I don't know, even if it was 100% humidity, how would you get 3" in there. That's quite a lot of water.

[helomech]

They where there for about 3 years. I still have two more to dig up.

[bacpacker]

That's a head scratcher for sure. I'll talk to the electricians at work and see if they figured out what caused their problems.

[Stormfeather]

Ive had this issue before myself, and its usually the threads is where the weak point is. As for the bags, Ive used the vacuum sealer on them, and then double bagged them with both bags being vacu-sealed, make sure you use desiccant in both layers. Its what I had to do to finally make it work.
Very interested to see the rest of your analysis as well!

- - - Updated - - -

That's a head scratcher for sure. I'll talk to the electricians at work and see if they figured out what caused their problems.

I ended up just sealing them and then coating the seam with waterproof caulking, all I had to do after it was said and done was cut the caulking away and didnt have an issue after that.

[Illini Warrior]

not a bit surprised - hydrostatic ground pressure is a bitch ... makes me laugh like hell when guys talk about 5 gallon bucket caches in high water table areas - you think 3" is bad - how'd you like 3 gallons ....

either cap both ends with regular pipe caps and expect to saw an end open .... or .... cap one or both ends with test caps - just knock out the centers with a knife or gun butt .... pipe cement binds the plastic together - pipe thread dope isn't an effective sealer - that's not it's purpose ....

forget about using rice as your desiccant - get a pound of silica crystals ...

[Kesephist]

Illini's got it, I think, as re: two cemented caps. My own self, if it were possible, one cap with a fitting to draw a vacuum in the entire tube, with a rubber flap on the underside, or the fitting filled with a solid rubber plug and the vacuum drawn via some large bore needle. Coat the whole cap with PVC cement once the vacuum is drawn and jam on the next sized larger cap. A really sticky silicone sealer around the cap's seam with the pipe would fill the bill. Opening day, cut away the sealer and what ever form of cement solvent, or a chunk of hacksaw to cut off the cap. Inelegant but workable.

[Gunfixr]

A good friend of mine buried a cache about a dozen years ago.
Out of curiosity, it was dug up about 2yrs ago.
In it, was a mosin Nagant, about 400rds of ammo, a cleaning kit, a knife, and I think a couple other small items. The rifle was covered with cosmoline, and wrapped, but I don't think any other particular precautions were taken.
The container was one of those burial tubes you find online at the survival type websites, with one solid end, and one threaded end.
All items were placed inside, a small lit candle was placed inside, and the cap threaded on. Caulk sealant was packed into the threads prior to threading the cap on, and a bead was added around the end seam to the cap. It was then wrapped with usgi duct tape over the bead.
10yrs later, it was unearthed. My friends brother had wanted a mosin, so he had told him where it was buried, and that he could have it, as he was curious about how it had fared anyway. His brother took it to the shop where he works, where he and several of his friends/coworkers proceeded to open it. The tape was removed, cut off, and then they tried to get the cap off. So much sealant, couldn't be unscrewed, so it had to be cut off. As my friend told me, his brother had quite a job getting into the tube.
The rifle was perfect, just as packed. The ammo was also perfect. The knife had just a bit of darkness in some spots, or maybe small amount of surface rust, IIRC. The cleaning kit was fine. There was a spoonful or two of water down in the bottom.
I do not know it's relative depth to water table when buried, but my friend is pretty particular, I do not think he would have put it down into the water table.

Sent from my SGP612 using Tapatalk

[helomech]

I really want to have the top be able to unscrew. I might try silicone next time.

[jamesneuen]

Or, the caches I stowed I put about a foot of rocks in the bottom of the hole I dug to try and remove any standing water from when it rained. Maybe you should just allow for 3+ inches of water at the bottom of each and put a spacer of some kind in place to raise the content height

[helomech]

Had a wing chun and kali seminar today so I just got home. Ran out and dug up another cache and it was perfect. No moisture at all. Here are some pics.