Two Letters Re: Constructing a Permanent Underground Cache
I want to thank JIR for his article and the efforts he went through showing us how to construct and supply underground caches. I just wanted to suggest an alternative to the custom made containers by using a 300 gallon spherical below ground septic tank. They are made of watertight plastic with a o-ring sealed lid and weigh around 110 pounds. (See the Tank Depot web site.) The rough size of the tank is 54″ in diameter and 51 inches tall with a 20 inch manhole cover. You would also only dig 118 cubic feet for a 5 foot diameter …