After a crawler excavator has dug a 6' x 10' x 20' deep hole, the excavator will lower a prefab retaining wall into the whole and be back filled with gravel.
I need a structural engineer to design a custom retaining wall that can be installed at the lowest possible cost. Two criteria:
1) if the retaining wall is not waterproof,a sump pump will be required to remove surface water from the contained area
2) most importantly, it must be able to, of course, withstand the pressure of the back-fill gravel and surrounding earth.
I need the materials and installation cost to be as low as possible.
There will be multiple such installations, therefore, economics of scale will likely play a part. is there any thing cheaper than poured reinforced concrete? Steel, fiberglass, reinforced wire mesh, etc.?
I would prefer that workers not have to enter the hole Until after the retaining wall or the forms are in place. You will need to be creative.