Wiring up a shop with underground conduit
NM in conduit under a deck (or a slab) is NFG

You cannot legally run NM cable in a wet location, and the inside of a conduit in a wet location (such as under your deck, or buried beneath a slab) is still a wet location.  Don't believe me? Well, we start with NEC 300.5(B) for what's going on sub-slab:


  (B) Wet Locations. The interior of enclosures or raceways
  installed underground shall be considered to be a wet location.
  Insulated conductors and cables installed in these enclosures
  or raceways in underground installations shall comply with
  310.10(C)


and 300.9 for the under-the-deck case:


  300.9 Raceways in Wet Locations Abovegrade. Where race‐
  ways are installed in wet locations abovegrade, the interior of
  these raceways shall be considered to be a wet location. Insulated conductors and cables installed in raceways in wet locations
  abovegrade shall comply with 310.10(C).


then move onto the fact that 334.12(B) point 4 prohibits the use of NM in wet or damp locations, as NM has a paper separator in it that will wick moisture up the cable, leading to failures.

What you should do instead

While you could use UF cable instead of the NM inside your conduits, that's not a good idea because cables:


Gobble up astronomical amounts of conduit fill compared to individual wires -- the fill calculation for a cable in a conduit is run by treating the cable as a round cable with a diameter equal to the major axis dimension of the cable's cross section, as per Chapter 9 Note 9 in the NEC.
Are quite stiff and hard to pull down a conduit compared to individual wires -- you'd rather not call an electrician in to bail you out of your conduit pulling now, would you?


What's done instead is to use individual wires (THHN/THWN-2) inside the conduit.  Since you're using PVC, you'll need 12AWG and 6AWG THHN in black and white (twice as much black as white for the 6AWG, even), as well as 10AWG bare copper for ground wires (as table 250.122 lets you use 10AWG copper for grounds on circuits up to 60A).

The good news is that conservatively assuming your PVC is schedule 80, you have 178mm2 of fill available in the existing 1" PVC under the deck and 320mm2 of fill available in the 1.25" PVC you are putting in sub-slab.  The three 6AWG THHNs for the 60A circuit use up just under 100mm2 of that fill, and the 10AWG EGC adds just over 5mm2 of fill, leaving just under 75mm2 of fill spare in the 1" conduit.  In the 1.25" conduits, we add just over 17mm2 of fill for the 12AWG wires to this, leaving just under 200mm2 of fill spare, which should be plenty.

Furthermore, since we have a maximum of 4 current-carrying conductors in the 1.25" conduits (the neutral in the 3-wire 6AWG branch circuit does not count for this, as per 310.15(B)(5)(a)), and since THWN-2 wire (what most THHN is dual-rated at these days) is rated for 90&deg;C in wet locations, we can use that as our starting point when applying the 80% ampacity derate from Table 310.15(B)(3)(a), yielding a derated ampacity of 60A, which is still in excess of the 55A that the 60&deg;C rating on most receptacles limits us to.  The 12AWG wires do not suffer either, as their derated ampacity is 24A, which is again above the 60&deg;C ampacity limit for 12AWG (aka 20A), as well as the 240.4(D) small-conductor limit on 12AWG wire (again, 20A).

While you are pulling all this wire, I would replace the existing NM cable inside the 1" conduit under the deck with individual THHNs + bare ground of the appropriate size, by the way.  That NM will only be fit for the scrapper, for that matter, since it will have suffered internal damage from the water exposure, which is why it shouldn't have been installed there in the first place.