De or het puinhelling?

The correct Dutch article is:

de puinhelling

Rule Words ending in -ing: almost always de. See the rule

How to use puinhelling

the puinhellingde puinhelling
this puinhellingdeze puinhelling
that puinhellingdie puinhelling
our puinhellingonze puinhelling
your puinhellingjouw puinhelling
every puinhellingelke puinhelling
which puinhelling?welke puinhelling?
a big puinhelling / the big puinhellingeen grote puinhelling, de grote puinhelling