Using uncountable amounts of sprites isn't really a good option..
Haha, my tablet just froze typing that reaction, because I was trying to play your game through debugger..
I've seen some examples on this forum of digging games, all using different techniques..
One started with bigger sprites only made smaller on collison when needed, which was pretty nifty..
I think that was before the tilemap-object was added to Construct..
I would suggest using that instead of the huge amount of sprites if one of the earlier examples don't suit your needs..