The first thing that I noticed on the new photos is that the puddle of standing water has apparently drained off. How long did that take? The drainage time will give you a clue as to what you are dealing with. I was also poking around on some Canadian governmental websites and found some, what I thought were interesting, at least to me, facts. -The depression in your yard is probably a filled in "Kettle". -Your area is classified as part of the St. Lawrence watershed. -There is quite a large area North of you that looks to be an old St. Lawrence tributary. It is definitely a large wetlands area. -Found the Topo map below. You are the blue dot. This is your GPS location within 300 feet. There is an area of higher elevation Northeast of you which drains to your general location. Judging from the new photos, the location that I suggested for the addition appears to be workable. Maybe running longer (parallel to the driveway) than wider (perpendicular to the driveway) and irregular in shape (for visual interest).