Improving drainage

We have an open water drain that runs under the house, and as a result the garage and rumpus room can get quite damp and musty as the ventilation isn't very good. To rectify this, step one was to fix the open drain by replacing the old loose terracotta drain segments with 10cm Ag pipe, then covering the lot with a ton of blue metal. My poor programmers hands suffered, but I felt good about it afterwards.
Pictures!