Bringing you the next episode in the series “Patrik laying pipe”!

In the last house post, I talked about the mysterious pool of water on the makai side of the house. Back in December, I wrote about the gutter replacement on the garage. Now it’s time for the (hopefully) final installation of major drainage hardware.

As part of the gutter replacement, I added a pipe through the wall of the planter box where the water had earlier just pooled into the box. However, the pipe just dumped the water outside the box, and I wanted to bring it further away from the structure. For this reason, I’ve been meaning to run a drainage pipe from the lower end of the yard up to catch the water coming off the gutters. I provisionally put that pipe in a couple of months ago.

Here’s the lower part of the drainage. The pipe exits out the lava wall at the bottom of the picture, does a loop around the fruit tree, and goes to the catch basin under the white 90-degree coming through the planter box. Then it continues up along the garage to the driveway.

That’s only half the story, though. Catching the gutter runoff is good, but a more major problem is that rain falling on the driveway currently drains off to the southeast side, where it runs through the yard and then flows into the yard of our neighbor Charlie. This direction is “down the street”, so his yard is about a meter lower than ours, and the water runs through the stone wall at the property line, undermining the wall and flooding his yard. (His yard really floods during heavy rains, but most of that isn’t our fault. Because the street has no gutters and his yard is so low, most of the water running down the street ends up in his yard. But every little bit less water would help him.)

The pipe could then continue along the garage to the driveway, with a drainage basin so the driveway water drains in there rather than into Charlie’s yard. This is pretty far, though, so I’ve been putting it off. But over the month, that pipe was finally put in, too.

This is where the upper part of the pipe runs. The catch basin from the gutters are at the bottom, then it runs up along the wall past the fig tree, through the lava wall in the middle of the picture, and up to the driveway. Charlie’s yard, quite a bit lower than ours, is just to the left of the picture.

This is the driveway, looking toward Charlie’s house. The cutout between the planter boxes is where the water used to drain off the driveway down into his yard. Now, there’s a catch basin there. (Why is there a hole in the driveway, you might ask? More about that below.)

The digging wasn’t too bad. There were no large rocks like I encountered while digging the french drain. When I got up next to the driveway, however, I hit solid rock just under the surface. After another 4h rental of the Home Depot demolition hammer, there was enough space for the catch basin.

The catch basin by the driveway. There was solid rock all the way up where the catch basin is located, so a fair amount of demolition was needed to get it to fit.

However, the fact that there was solid rock there makes me suspicious. As you can see on the picture above, our driveway is in pretty bad shape. There are lots of large cracks, and where there is now a hole, the pavement had sunk enough to make a depression where water would pool. When it rains hard, there’s enough water to flow off to the side, but a lot of water clearly just sinks through the pavement.

I hadn’t reflected on this before, since I had assumed that it would all sort of flow towards Charlie’s yard either way, but if there’s solid rock just under the surface off the driveway, the water sinking into the driveway can’t go in that direction. It has to go either in under the garage or towards the house.

I have noticed before that when we’ve gotten a lot of rain, the concrete floor of the back of the garage, towards the house, has gotten seriously wet. My first suspicion was that this was water from the gutters that used to pool in the planter box, but now I’m wondering if it’s also water sinking through the driveway, then running under the garage until it hits the concrete wall at the back of the garage. Maybe it would pay off to fix the cracks and depression in the driveway so it drains better into the now-installed drainage? The crack patches and the hole in the driveway are part of that effort, which will have to wait until the next post.

To funnel the water into the catch basin so it doesn’t just sink into the ground before getting to it, I added a concrete “chute” between the pavement and the catch basin.

Once all the pipe was installed, the precision work is done. All that remains is to fill back in, which isn’t really as easy as it sounds. The dirt is so full of rocks that it’s hard to make sure it’s packed under and around the pipe so it’s completely supported. (Leaving pipe without solidly packed fill around it is the best way to ensure that it gets crushed from the weight on top of it…)

As shown in the picture above, I also made a concrete drainage chute connecting the pavement to the catch basin. It wouldn’t do to have dirt or gravel here, since the water would just sink in before making it to the catch basin, thus negating the whole point.

We haven’t had any huge rains since this was put in, so I haven’t had a chance to see how well it works in action. Although with the current hole in the driveway, little water will probably make it into the drainage. Better fix that soon!