Hi all. We just moved into this house 2 yrs ago, and the previous owner had created a high (3 ft. above ground on 2 sides and butting up against terraces on the other sides) patio with pavers. This patio is filled with sand (hopefully there's gravel underneath, but I don't know). On the free-standing sides, one side has 2 x 4 treated timber (like for terraces) and the other side has retaining wall bricks.

The problem area, you might imagine, is where the timber and the bricks meet. We could see the timbers bowing out a little when we first bought the house and I thought it could be a problem, but nothing much happened after that.

Now, in the 5 days of rain that we've had here in the Twin Cities MN, the timbers have bowed out about 6-8 inches and big piles of sand have poured out, leaving the pavers in the corner completely sunken.

Any advice on how to fix this problem? I'm a bit desperate and hope that the whole patio won't erode out if this rain keeps up.