Water retention project begun

It's been an exciting weekend around here. I was able to hire a couple of great workers to come dig some big holes for me. We're not done yet but I can start to see it all coming together the way I have been imagining it for the last 18 months. We will run the three downspouts from the back of the house, under the deck and down the slope to the first water basin. Eventually there will be a water feature here but for now I will start with a hole in the ground to hold water. The soil is so dead (not a single worm yet) that I will just pile in the organic matter and nature do its thing.

Then from the first basin there is a channel that I will tweak to resemble more of an ambling stream that sends the overflow down to the next level. Previous owners had a couple of terraces there so it gives us a good start.  Right now they are going to dig just to about where the PVC pipe is sticking up since we have a mountain of wood chips in the way. As they go deeper we are berming up the lower edge with room for overflow down to the next level which is a path along the property line, currently about 4" of wood chips...more to be added. I'll plant trees below the berm to soak up the water give us some screening from the neighbor's house. Last year water raced down both those terraces right out the lower path to the storm drain. This year I hope to keep more of it in the yard.

The first basin doesn't quite have the edge that I want but I don't think it matters much as there will be a wetland before water hits the bigger hole.

I've been trying to figure if I can push any overflow toward the back of the property or not.

The workers are coming back on Wednesday to finish the second basin and then I can have them start to dig deeper on the first hole.

And I love the mound of dirt which will give me more edges to plant and be more visually interesting.

How exciting! Isn't it cool when a dream starts to unfold? I just love that part. Looking forward to watching it all come together.

It really is exciting to see dreams come to life. I think it is a good thing I have all those wood chips in the way so I'm not tempted to dig further. I need to observe what the water does this winter, provided we actually get some rain again.

Question for anyone reading along. I want to let the rainwater run through a wetland before it moves on through the system and I am trying to decide how best to do that. There will be a lot of water coming off the house and down the slope so does the wetland need to be a certain size? I was going to use a stock tank so I could control some of the more vigorous plants like cattails and rush but then if it needs to be huge, that might not be the best approach. If anyone has any thoughts, I'd appreciate hearing them. Thanks.

Still digging here. I have a question in the post above this one about wetlands, if anyone is reading along.

The guys have the second water basin/rain garden/whatever you want to call it, almost dug. I am trying to decide if I want to leave that flat high spot as a spillway or not. It might be easiest to do that and the berm up the smaller hole on the other side of it, while going deeper. I wish we had the money to hook up to the city sewer but that will be a while still so I need to keep a decent distance from the leach field though it is already at the lowest point of the property and has already been getting flooded each year so it might not make a lot of difference. But I will err on the side of caution.

We found another pipe, this one looks to be for drainage of some kind since it has holes in it. We know that over 20 years ago there was a pool in the yard (above ground) and that could have been for pool drainage, perhaps.

I am letting go of trying to keep things on a certain track. Dirt is getting tossed on the thin layer of wood chips but it will all be tamped down for berms so I am letting it go. I can't wait until we run the downspouts from the house down to the upper basin. I think the upper basin should be deeper but hubby is concerned about it being at the end of the slope so maybe it will just become the wetlands that flows lower.

The hardest part of this rainwater project was the digging but I think today it is pretty much all done except for the final tweaking. Tomorrow the workers are coming back to work on spreading all the wood chips.

I need to figure out the spillway to the lower levels and I need to figure out what I am going to fill the pits with...organic matter, yes, but not sure what. I have lots of wood chips but I wonder if I should buy some manure or compost to get things started and bring the worms up.

I am reading all I can about wetlands and trying to figure out how to set one of those up for the water first coming out of the downspouts. Ideally I would like the rainwater to come down the slope, hit the wetlands, and then overflow to the water feature which is going to be installed near the fallen tree.

Onward.

Wow, Susan! This is going to be wonderful! I don't know a darn thing about setting something like this up, but I'm rooting for ya! Can't wait to see it completed, with all the little critters it's going to attract. What a wonderful thing to surround yourself with.

If any of the spillways are steep, you might want to put some small rock dams in there to slow the water.

And what an exciting project, I just can't wait to see it planted and growing!

Here's a thing I found:  http://www.cnps.org/cnps/conservation/wetlands.php

Tracy, thanks for cheering me on. I know the wildlife will flock to the space once things get growing. (Just please let the local mountain lions stay on the other side of the fence.)

Tyler, thanks for sharing in my excitement. And for the link. I think California has an awesome native plant society and so much knowledge. I am on their listserv and soak up all the knowledge I can. It might be a good idea to have one of their wetlands experts come out for a consult.

I agree on the rocks and the spillways. That's the plan. I was reading up on one rock dams and how to build them and I think I can do them on my own. I might go to the rock yard this week and see if I can find some flat rocks that would work for me. Or if my cement connections come through ( a couple of guys are supposed to be bringing me a bunch of used cement this week for our retaining walls) anyway, there should be some leftover pieces I can use for the spillways.

I think I need two wetlands, but I am not sure. One for the grey water system (which might be installed this week) and one for the rainwater.

For the big holes I am thinking it will be time to fill them in. The guys are out there now spreading wood chips around the rest of the yard and as they get to the bottom of the piles that have been sitting for 6 months, there's some good halfway there stuff that I think I will put in the bottom of the holes. I have a huge tub of coffee grinds to add too. Maybe I will just concentrate on building up the top level and work my way down.

A funny aside: the guys who were spreading chips freaked out a little bit at the "white stuff" growing on the chips. They wanted to make sure it wouldn't give them cancer. So I got to give them a little science lesson. LOL

I didn't get outside today until it was pretty hot so I didn't get a lot done. I did start to fill the lower basins and the connecting channel with brush. I also poked around in the dirt a bit in the upper basin, trying to decide if I was going to make it any deeper or not. What I discovered is that we have a lot of chunks of sandstone which, I imagine, gets larger as we go deeper. So I won't do any more digging. On the plus side, it isn't granite like our neighbors higher up the mountain have so that's good. Sandstone is an aquifer so hopefully it will aid in absorbing water.

I also found this video I took of the yard during our rainy week in January. I was happy that most of the water was staying on our property but it was killing me to see it so low on the property. Seeing how the water moved across the yard is what inspired this project.



I am still pondering the placement of the wetlands and how we are going to do the water feature. Trying so hard not to move the same dirt and chips twice but I think in some cases, it will be unavoidable.

So I have started to fill the basins. Brush on the bottom, then in the top basin I tossed all the coffee ground and greens and kitchen waste I could find and topped it with some shredded paper and leaves. I figure if I can get the worms coming up here then the nutrients will drift down. In the channel leading to the two lower basins I have piled a bunch of brush, then I tossed in a layer of the dirt clods that were kicked up in the digging, then another layer of brush. Tomorrow I will top with more shredded paper and dirt clods then a thick layer of partially composted wood chips. I'll let that settle. My goal is to be ready to plant the space in October, which should be good for our native plants. I will probably fill the basin with my starts of Carex Divulsa which I have been propagating like crazy. It's a nice "lawn" look for the dog to roll in. Lots of native plants and trees around the edges.

I'm really looking forward to following this over time.  Keep posting!

Thank you, K. I sure hope we get some rain this year to try it out.

We filled the rain garden basins with brush, paper, cardboard, and some dirt clods then topped them off with about 6" of wood chips. I might have more chips to put on top once we finish spreading what we have. My thought is to let it settle and turn to semi-compost between now and fall when it will be the right time to plant my native plants. By then it should have settled some and I can add soil/compost on top and plant.