The first step was to remove the existing French drain. It was improperly installed and didn't have a filter sock. As a result, the pipe had collapsed, and--much to the pleasure of Lula & visiting Abby--there was a dog toy stuck in the pipe. [i would be lying if Abby + i didn't take a little fetch break while cricket dug away at the trench. but it was a short break. i promise. the old girl needs her kicks!]
Deepen the trench to at least 12", so that it slopes away from the house. We extended the length of the drain so it would empty near a future flower bed instead of the middle of the lawn.
Fill the bottom of the trench with drainage rock:
Lay the perforated pipe into the trench:
We also tied in the downspout to the trench, to move that water away from the house, too. This was done by cutting a length of perforated pipe to the length where the downspout would join the trench. Both the downspout pipe and the perforated pipe were fed into the top of the "Y" and placed into the trench. Then, a piece of perforated drainpipe was inserted into the opposite end of the "Y" and laid into the remaining length of the trench.
The end of the perforated pipe should come to the surface of the ground, following a slight incline if necessary for the slope.
Once the drainpipe is in the trench, cover with drainage rock.
The hardest part is the digging. And the digging. Did I mention the digging? Since this was part of a larger patio makeover, we rented a tiller--which definitely helped the process along. Removing the existing trench's gravel was painful. I felt like we spent 5 hours moving dirt from one pile to another. But, so far, despite the crazy tornadoes and thunderstorms of the past week, we haven't seen much water in the crawlspace. It's definitely an improvement. SUCCESS!!
25 foot flex perforated drainpipe with filter sock: $20
5 bags of sand: $16
7 bags of drainage rock: $24
tiller (though rented for another project too): $34
this was also a great excuse to purchase:
a wheelbarrow (for hauling the sand + rock)