There should be keys at the end of the two puzzle levels, these can be accessed from the pipe-like entrances you can also dig up. You should be able to find them with the ping tool also.
I threw in the text last minute,it could do with a lot more explantation. hahaha
Viewing post in Stij Of The Dump jam comments
I also took lots of tries to get over the last rotating block - but again it drove me to keep trying. Unfortunately when I got the key and returned to the dump the game crashed for me as well.
I liked the surprise of discovering a puzzle when I entered the pipe - I wasn't expecting the change and I enjoyed the puzzle level that I found.