After Dog attacks the dropship and it drives off, go to the bent down fence and jump over it. Walk down a few steps and on your right will be an open door. Go in it and to your left you will see a stairwell blocked by a couch and debris that cannot be moved. Crouch jump over the couch and go up the stairwell. Bring a box with you so that you can put it on the ground in front of you, then jump on top of it and make longer jumps.