Strikes me more as HDR, perhaps, than grunge, but I think some would argue HDR *is* grunge! I like the shot - this place has definitely seen better days!
You chose a nice shooting angle for this but I think the composition suffers a bit form lack of a more defined foreground. You only have the two layers which is the subject in the foreground and the sky/treeline in the background. It does seem a little dark and grey overall which is probably what you were going for in this challenge. The scene is lacking in contrast which is due to the overcast sky and the lack of shadow.