Structural engineer for an underpinning / floor-lowering design in Oakland, CA

I’m looking for a structural engineer for an underpinning / floor-lowering design in Oakland (94611). 366 sq ft studio basement, legalizing as an ADU under an active AB 2533 permit. Need to lower the floor ~10 inches across the whole unit to hit the 7’0” ceiling minimum (currently 6’8”). Footing only goes ~5 inches below the current slab, so underpinning around the perimeter looks necessary. All architectural plans are done and submitted, just need the structural to be added as a revision to the existing permit set. Need stamped underpinning/floor-lowering plans plus construction observation for sign-off. I’ll be doing the work as owner-builder. Space is already opened up with the footing exposed, come see it anytime. Looking for a quote and rough timeline. If you see a cheaper approach than full underpinning (bench footing, etc.), open to it.