They are cheating the MC!!!
Even if we take the lightest wood there is, dried to around 20% water content remaining and estimate those blocks as 2m * 2m * 2m each then the result would still be that 1 single block of those tree trucks would weight around 2000 kg.
So with all those blocks he delivered that seems more likely to be around 100,000 kg = 100 tons instead of just 18.5 tons.
Or the author is simply too lazy to look into the weight of wood or maybe he is just bad at math.
Also he definitely NEVER carried any wood himself as he would definitely know that wood is far HEAVIER!