i guess my question would be where are you going to get and what material, to raise the
land in the center....and does this include any buildings in this piece of land that will be raised to the spiral?
i suppose if you are putting on a building you could use the excavation from the building site to raise the property..or even a raised drainfield.
we had flat land here with a high
water table..we put in a crawl space and a 4' raised drainfield approx 60' long behind the house..thus, there is a slope away from the house and from the drainfield that was backfilled with good soil
we planted the fruit trees up around the top edges of the slopes and have the smaller plants running down the slope with a
lawn area on top of the drainfield..it works out very well for us..we have other beds on other parts of our property..but this is the area around our drainfield and home
it isn't in a spiral form, as our paths curve lightly down in several areas around the property including steps down in the far north rear, and a path down on the west and 2 paths down on the east and 2 sets of steps down on the south..with large beds all the way around.
we also have some flat and some raised beds in other areas..
we also have dug a
pond , part of our backfill was the topsoil out of the
pond area..the pond is on the lowest area of the property and it all drains toward the pond.