More Than One Foot Deep - Retaining Wall - Pizza Oven Project - March 2025

I've excavated the landing in front of the pizza oven a little bit at a time over the past week-or-so.  I've managed to remove about seven(ish) feet x eight(ish) feet in area.  I'd like to get back to (at least) 8x8.  But, I've also begun to figure out what I'm facing in terms of earth that needs to be held back.  Below, is a photo showing the rear edge of the site - showing about eleven-inches of height at seven-feet-back.  The grade isn't too steep in this spot, so if I take out another foot, I'm guessing this might raise up to one-foot-tall.    Here's the initial excavation post from last week.

My plan is to get all of the earth removed so I can start to use the eight-foot timber as guide to find level.  Underneath the wall area, I'll excavate a bit to fill with gravel + paver base.  

At 12" tall, I'm dealing with a timber with a 5.5" true height.  Thinking two 6x6's (11 inches) might be enough.  But, that all depends on where the true 'floor' is level-wise.  Research indicates that it is best practice to bury PART of the wall under the floor level.  The 'floor' in this case is going to be pretty close to the top of timber - 5" or so from the bottom.