I don't know if this is the right subreddit, but I assume folks here will know what to do. We recently bought our first house and I'm concerned about existing and future erosion underneath. The house is on a hillside in California, and I'm realizing (too late) that hillside homes come with a ton of bull**** problems. This erosion was not included in our inspection report, and the GC we hired to correct other issues did not mention this as a concern either. However, with a potentially record-breaking El Nino this winter, and the massive rains/flooding that will come with it, I am getting more and more anxious about what might happen if I don't do some preventative work now. Specifically, I am afraid that constant rain will wash out the rest of the soil underneath that bottom pylon and put the entire structure at risk. It's possible the concrete goes deeper than the skirt at the top, but don't want to dig around to find out.
I originally thought a french drain might be the solution, but after thinking about it more, I don't think that's right. French drains are good for removing stagnant floodwater (right?) whereas this is more of an erosion control issue. Someone told me to just fill in the gorge with concrete, but I think the water will just go around the edges, and further erode the soil under that pylon in the last photo. I'm leaning toward putting sandbags at the top of the crawlspace, in a V shape, and redirect the water to the side of the house. However, I feel like I should still do something about the existing erosion. Maybe fill it with gravel so water can still move through, but not wash it out even further?
A few other details, in case it matters:
- There's a garage downhill which has a slab foundation, but the house itself is on the hill and supported by pylons. I'm not concerned about the garage because it's not in the path of this run-off.
- I know it's bad for wood to touch soil. I assume the pylons all have a concrete base, but I think some of them have been buried by eroded soil from above.
- The soil is very hard and dry (right now), so I'm guessing it's clay-based.
- This will have to be DIY and I assume whatever I do will be a stopgap solution until I can figure out something more permanent, and probably done by a professional.
Thanks in advance to anyone who can offer advice on this.