thanks much for the info, fellas. ugh, i wonder if it's a result of our crappy builder or simply the soft, clay-ey soil. in addition, the inherent drainage situation certainly doesnt help - i'm at the bottom of a street and about 5ft lower than the house next to me so i get all the run off. the yard is graded somewhat around that area but when these monsoons move through, the grading just can't deal with it. and neither can my sump drain with all that water coming down the stairs (as well as spouting through a couple small holes at the bottom of the stairs, which makes me think the void underneath is HUGE).
2 holes visible in pic, on left and right of landing.
