Per the letter from the Blog reader regarding CONEX containers- Yes they are a great way to store bulk supplies at your retreat. I've been using them for almost eight years now and have noticed several things when using them.
First, try to get one made of "COR-TEN" steel. My father has years of metalworking experience and pointed out one of ours that is made of COR-TEN. It reputedly holds up better. I've seen a noticeable difference in the one COR-TEN we have compared to several others not made of it.
You might want to weigh the difference in cost between finding one locally or buying one closer to the coast and preferably a major seaport where they will be cheaper. Shipping costs being the deciding factor, as well as condition of container. We've never paid more than $1,500 for a 40 foot container and you can find them for around $1,000. if you shop around. Keep in mind most places will just give you a general quote on the phone. You want to go to their yard and check one out for yourself, make sure the doors close and latch properly, climb up on the roof, and inspect closely for holes.
Figure out EXACTLY where you want it dropped, unless you have heavy equipment- and I don't mean a small tractor- you will not be moving it from that position.
Go to the junkyard and get four to six old metal tire rims. Put them down on the corners below the container. It will help air circulate a little bit under it. We've had problems with moisture coming up from the ground in to two of the units. Doing this helped the problem immensely.
Readers should plan to ventilate the containers, as you mentioned, even if it's just for storage. They get very hot. Might not be an issue up North, but it is here in the South.
Re: Use as a bunker or as hardened shelter, etc. Keep in mind that CONEX/SeaLand type containers have most of their strength in the floor and on the corners of the roof (which is probably why they can stack them a dozen high on ships). You absolutely MUST reinforce the insides if you plan on completely burying one. (Such as 6x6s or heavy timbers.)
Here is what [U.S. Army] FM 5-103 "Survivability" says about containers (page 4-31):
"Large metal shipping containers such as CONEX containers, are used to make effective shelters... ...are easily converted into protective command posts, communications shelters, troop shelters, aid stations, and shelters for critical supplies. Because the CONEX container's floor is stronger than it's roof, it is inverted to resist more blast and provide some overhead cover. Although the shelter sometimes constructed above ground, it is easier to construct it below ground by placing the inverted CONEX container in a hole half it's height and then covering the roof with earth."
For our purposes, shipping containers make great storage facilities and can make use as initial entrances into shelter systems, housing for families, etc. They are fairly secure and can be used for pre-positioning of bulk supplies even at the "absentee owner" type retreat. Hope this helps. - Mr. Lima