Is leveling this ground and removing plastic by the side of my house a bad idea?

Question

I am transforming the side of my house from an overgrown mess into something practical, and once I cleared out all the mess I could see that there was a channel dug along it and thick black plastic underneath the rocks:

Notice the channel running from top to bottom as you look at the picture.

I think I understand the intent, but practically speaking I don't think this setup was working. The black plastic traps water indefinitely, which encouraged plants to send their roots through it and proliferate around the edges of this setup (already cleared in this photo, but they were finding any little nook and cranny to take hold, supported as it turns out by the abundant supply of water being trapped in the plastic).

Secondly, the channel is ineffective at routing water into the drainage system because the drain cover sits way higher than the bottom of the channel, and in fact sits higher than all but the rocks. So water would just pool in the channel and be held there by the plastic.

My plan, then, is to:

1. Clear the entire area
2. Remove the plastic
3. Break up the soil
4. Level out the soil
5. Put weedmat down
6. Put the rocks back in

Does this sound reasonable? I'm really second-guessing myself because I don't know if I'm overlooking some valid reason for the channel and plastic. As long as the tops of the drains sit below the level of the footpath (which they do), why would a channel be required? The plastic would prevent water seeping into the soil, but is that a bad thing?

UPDATE: Just adding some additional information here based on responses:

• I live in a subtropical climate. There's a lot of rain, particularly over summer, and it's never very cold (certainly not freezing)
• The footpath on the right in my photo is 3 feet wide, then there's my house
• The drain inlet connects to a conduit that runs down the side of the house towards the back, where it must connect up to a large, municipal pipe that runs through the back of my property (I have a grate in a corner of my property that allows me to see into that pipe)

Answer 1

Someone probably built that ditch to get the water away from the building. The drain does nothing, but the ditch might. I encourage you to do something to direct water away from your foundation. Options are another ditch or some type of pipe system.

Answer 2

More information is needed to come to the best solution. Where is you home in relation to the stones and drain? Are there other structures around? How much rain do you get? Are you in a freeze area. What is the rest of the area topography like?

Assuming that having water in the stone drain is the only issue and getting it moved from the area is the sole goal, I would look into getting the collection bin lowered.

If the bin is connected to a drain conduit, a bit of digging could allow you to lower it and a reasonable length of conduit so the top is below the rocks. This would get the water to drain from the area as originally intended. You could place larger rocks on top of the drain and water will still run in. (This was done in a low area around my condo by groundwater control specialists and works well.)

The rocks are moved and the bin cleaned once a year. This is probably less work than removing all the plastic and replacing with weed mat. Adding a little rock salt to the rocks usually prevents weed growth.

Answer 3

I would excavate down to the pipe (just in one spot for now). If you find gravel around the pipe, and the pipe is perforated, someone built a french drain, and the plastic was keeping water from getting into it.

If you don't find gravel, and the pipe isn't perforated, you should build a french drain yourself. I would actually keep the grate drain, if only as an access point.

If you found gravel, but there was no geotextile around it, the gravel is probably clogged with fines and you should rebuild the french drain with geotextile.

Answer 4

The plastic sheet is intended to keep water away from the foundation, but in order to be effective at this, it must have a slope.

The idea is that water dripping off of the eaves hits the rocks, which reduces the amount that splashes against the siding, and then drains through to the plastic, which moves it farther away from the foundation before allowing it to percolate into the soil.

I did this around my house, which is in New England, where we tend not to use gutters along the eaves because they get destroyed by snow and ice anyway. It's quite effective.

Your setup is constrained by the pavement on the right, which is probably why the drain grate is there. But that grate needs to be the lowest point in the system, so that water is not left standing on the plastic.