The drain is done! Hallelujah. Total cost DIY plus some labor of about $1800. Had to rent a jackhammer to deepen the drain and the water pipe channel in the back yard by 4-6″. Once the ditch was dug, we ran a garden hose to it and filled it with water to check the level, making sure it drained. Once confirmed, we lined it with landscape cloth, put in the plastic french drain pipe withe perforations, then the gravel, then a layer of landscape cloth over it. Then 3″ of gravel again and the paving stones over it. This all leaves the 8″ before you reach floor level in the house.
Under best practices I would have used a white perforated pipe for the French drain pipe, to make it easier to clean-out in 10-20 years. But the previous contractor already had the corrugated black one, so it was reused. Plus, the ideal gravel is supposed to be 3/4″ diameter, and I had 2-3″ gravel which could be used for a French drain without the pipe itself. So basically I have two drains in play.
The paving stones we laid on top were about $1.50/sq ft which is more than I pay for tile, but the wife had a good point, we needed to roll wheelbarrows along it. The 2-3″ gravel is an ankle twister to walk over, a wheelbarrow is worse.
The connection from a 4″ French drain pipe to a 2″ PVC pipe was done using a drain grate box of 4″ to 4″ then a 4×3″ adapter and a 3×2″ adapter as you see in the picture.
I leveled out the runoff line to drain the French drain, and realized that once I put in the PVC pipe, if I fill in the ditch with 2″ gravel, I can drain the yard there as well. The space between the outside of the pipe and the ditch is the annulus and so I call it the annulus drain. So the pipe takes water away from the side of the house, and the annulus gravel drain takes it from the low part of the yard.
Update June 3, 2016 – hit with 3″ rain in 2 hours. 2″ diverter pipe at 1/2 capacity and working like a champ.