Raised patio / retaining wall construction

[attritioner]

Hello,

I have looking to construct a raised patio to the rear of my property.

Currently around the rear there is a 1m wide path, edged with kerbs. On the other side of the kerbs the ground slopes down to a 70cm high retaining wall at the bottom. The height difference between the two levels is 1.1m and the slope length is 2.5m.
The length of the existing wall is 10m.

I am looking to build a retaining wall to construct a raised patio.
I plan on using 7.5m width for the raised patio, and 2.5m for some steps to the lower level.

I have dug my footings in a u-shape for the retaining wall, 44cm wide, 60cm deep on the other side of existing retaining wall. I have a good solid base and plan on filling with a 30cm depth of concrete.

1.) I have had a few quotes for constructing the wall. One bricklayer suggested using concrete blocks on-the-flat giving a 6in thickness wall. Will this be thick enough to suport the patio?

2.)Will I need piers in a wall of this length?

3.) The patio will then be leveled off and either topped with concrete or paving slabs. Will the retaining wall require drainage in this situation?

Thank you

[Tony McC]

Sorry, but this is yet another project where only onsite advice should be followed. However a 6" wide ret wall doesn't sound strong enough to me, and the value of the proposed piers can only be calculated by a structural engineer.