[IUsedToBeATightEnd]

I have one of those 300 gallons buried propane tanks.
All valves and pipings and gauges etc are under the lid, in the upper part which is not buried.
The thing is safe and if you ever need to replace something no need to dig it out.
It's galvanized and coated so it will probably last more than the house.
Must be grounded for some reason.

I never filled it up though, because I have no use for such quantity as I only use propane for cooking and hot water.
Last winter I couldn't plow open the road to my house when the truck of the company was in the area so I ended up for 10 days or so without warm water and no cooking in January...
Although the wife was happy about the non-cooking part of the matter, she was quite pissed about the freezing cold water, so I called on the plumber and had him install a bypass so I can use a 90lbs external tank "just in case".
Since I realized the portable tank lasts me 3-4 months, costs about half as much per gallon (no delivery charges), and I can replace it at my wish, I am no longer using the buried tank.
Wife is happy and so is my wallet.

Moral of the story, put in writing all the terms regarding the time and conditions regarding refills etc, and make sure your consumptions are worthy of installing a buried tank, before you make same mistake.