[Cob] Rubble Trench

[jacques marmen]

Hello everyone!
here I am, on my property, three cob builders digging test pits checking for
water depth.
we dig in multiple places, finding a fairly consistent pooling of water
after a while, at a depth of three feet ( one meter )
This is a somewhat marshy area, aside from the slightly raised field which
is my 5 acre property.
I am assuming the water is the water table, and is relatively consistent-
probably somewhat higher than the rest of the year as this is the spring
(snow melts here in NB) and we've just had a few weeks of rain.
The rubble trench we are planning on using for our house was planned to be
at least 4 feet deep- the frost line in the area.
We are assuming our trench should not have standing water, and at 3 feet,
the 'supposed water table' would keep the trench full of at least one foot
of water.
Or, would this water flow out in this sloped trench?
does any one have experience with this type of situation; IE supposed water
table higher than frost line.
The earth has generally good drainage, sandy soil.
Would the water table drop in the winter, when frozen water in the trench
would be a problem?
Thank you for reading, and hopefully someone has some experience with this
situation.