Root Cellar/Storm Shelter on Bedrock

So it's starting to look like I might get the raw land I've been praying for. My biggest concern while living on my skoolie and getting basics built up is having a storm shelter as there are tornadoes in the area. Most wells are through deep bedrock and most houses don't have basements unless the land is built up around it. So that is what I want to do to make a root cellar that will eventually be the basement of my cabin. I'm looking for ideas to build a earth berm root cellar with cinderblocks and then hauling wheel barrows of soil from where I can get a dump truck to dump it. I think the cellar will be about 500 too 600 square feet and cinder block and rebar construction, I'm just not sure how much dirt will be needed to build a mound around it that would not erode away over time. Would mostly clay soil be best? What kind of ground cover should be used to keep the soil covering the storm shelter from eroding and making it no longer be underground? I am sure this is not an original idea so if anyone can tell me about some previous builds or youtube channels to watch, that would be helpful.

I wonder what the dimensions for your cabin/basement is.
I am going to just visualize it as a 2room by 2room square for a total of 4room.  Bedroom and livingroom on one side and kitchen+bathroom on the other side. see attached image

So lets tackle the amount mound on just one of the 4 side.
Height = 8ft
Length = 24ft
Width = 16ft (2x the Height, we don't want a slope that is too steep, we could make the angle 45 and just do 8ft, too)
Volume of fill = L*W*H divided by half because it's a slope.
Volume = 8*24*16/2=1536 cubic feet
We need another 25% so that each of the berm side meet so 1920 ft3 or 71 cubic yard or 6 truckload of dirt (12cubic yard each at $450)
If you only berm 3 side it would be 3x71 for 213 cubic yard or 18 truckload, this works for lose dry sand, but with wet sand/soil/clay you could cut that in half by making a steeper side with a 45 degree angle.

Would this be a good opportunity for hugel mounds? No idea how the hugels would affect the moisture inside the cellar, or if the walls were waterproofed, how the performance of the hugels would be affected. If you're in a situation to obtain cheap or free wood, this would save you money on soil right now, though you'd have to buy or build more soil in the future as the wood breaks down.

Could this be an opportunity to divert any lost or wasted heat into whatever mound you build? Probably not great for summer time cold storage, but probably great for winter time season extension. Do you have (and use) a dryer?

Burying wood next to a house, may cause termite issues.
I can say that 45 degree slopes for soil will be too steep, erosion will occur.
The steepness of soil whereby it will sit there is called he Angle of repose, here are some details;
The angle of repose or the critical angle of repose, of a granular material is the steepest angle relative to the horizontal
plane which a material can be piled without slumping or the surface material sliding.
Angle of repose for soils

So talking about your land, is bedrock exposed at the surface?
Is there any chance of going down a bit, with out turning the basement into a sump ?
Do you have any top soil?
If the site is so difficult to build on, where is the magic?

John C Daley wrote:Burying wood next to a house, may cause termite issues.

I agree. I was assuming the hugel would be against a concrete block wall. If the wall has wood in it, then I don't recommend putting a hugel against it, unless you know how to make an effective termite barier. (I don't.)

John C Daley wrote:So talking about your land, is bedrock exposed at the surface?
Is there any chance of going down a bit, with out turning the basement into a sump ?
Do you have any top soil?
If the site is so difficult to build on, where is the magic?

I'm in the process of working out a land contract to buy the land, it is fairly hilly and has some exposed bedrock. It is not a permaculture paradise but it has potential and I might be able to afford it. There are lots of trees and top soil, just not deep enough for a basement. I could probably dig down two too three feet to put in a cellar but would like to have the entire basement underground. I plan to use the topsoil from digging to fill in around the edge of the basement. There was an old homesteaders cabin on the property at one point so there is a small clearing to build on.

T Melville wrote:

John C Daley wrote:Burying wood next to a house, may cause termite issues.

I agree. I was assuming the hugel would be against a concrete block wall. If the wall has wood in it, then I don't recommend putting a hugel against it, unless you know how to make an effective termite barier. (I don't.)

Yes, I think I will be using concrete block for the foundation. Either that or a five gallon bucket of cement at a time. I do however plan to timber frame the rest of the house and probably use cordwood for the bulk of the building. I need something that I can do on my own so cinder blocks and cordwood are many small piece of the puzzle I can pick up and move around on my own.

Max slope of the berms, for different soil type, under different moisture levels.