House, Meet Creek

So, I have a background in residential construction, albeit in another state from which I am currently residing and from which this post is about. So, things, all the things, it seems, are different here... Including what constitutes as a "pass" on a building inspection or for that matter, how on earth it got permitted to begin with...

But this place is slippin' right into the creek. I have to come up with some slope stabilization solutions like... Yesterday. The ground beneath the walkway outside the backdoor has officially begun it's descent into the creek below.

I'm totally lost. I know how to prevent this from happening before it takes place, but I haven't got a clue what to do about it at this point. I'll throw some photos up once daylight permits but... Any ideas on anything I can do to slow this down, at least? The creek flooded monumentally yesterday and the rain is still coming. Talk about a nail biter.

Love & Respect,

Faeryn

No good suggestions for the short term - you'll need to share photos at least.

Longer term, you probably want some kind of vegetation based stabilisation of banks.

There are a couple of good options. Willow stakes can be effective and simple to do. Cut a bunch of simple stakes about 18 inches long from young thin willow. Drive them vertically into the soft bank at the waters edge. They will root over a few months and will slow/stop further erosion at the stream channel.

For the bank itself you might try something like vetiver grass. I think, from my brief googling of your climate, that vetiver will do ok. Vetiver when planted correctly forms dense hedges and has a deep and  very strong root systems that is excellent for bank stabilisation, slowing surface water flows, and trapping sediment. It is used globally in erosion mitigation projects, river channel stablisation etc...  You appear to be on the edge of it's viable growing region, as it doesn't like deep freezing in winter but can tolerate some frosts.

Best of luck, Faeryn.

We are all pulling for you, stay as safe as you can.

I am certainly no expert, but in your shoes...hoping you are size 12 or 13.....I would buy as many 60 pound bags of Quikrete as possible and gently part open some of the packaging before using them as stabilizing blocks. The packaging will keep it in solid form and slowly set up in the rain.  Also using some concrete blocks will help.  After making a shelf, so to speak, you could try using treated 4 by 4 to then prop under at least part of the threatened structure , use some lag bolts to connect everything.  Keep your eye on things and try o work with a pal or two.

It may not work but your actions will forestall that feeling of impending doom.  Good luck and 'vaya con Dios'

Rico

Waiting on the pictures ....

I like the Quikrete retaining wall suggestion.

A world of difference from the Washington Coast to the California high desert.

I also like the quick-create and 4x4 support ideas for a fast stopgap.
It may be ugly, but it might hold things in place.
I suspect your creek will quickly recede as soon as the rain stops.

You are going to need a retaining wall of some sort, but there are a bunch of factors at play and you will want to make sure you are doing it 'right'.

I have seen successful concrete walls made, reinforced with rebar to tie the wall together, that stood for years. I also have seen them where they eventually fail after a few months. Make sure you have adequate drainage and if possible prepare the gravel/soil underneath with proper compaction.

I am an advocate in emergencies to not get decision paralysis waiting for a perfect solution when there are good ones; just remember when the immediate issues are over that the underlying issue might still persist.  

BTW I once aught teenagers near Compton CA, and appreciate your location in WA, cheers

Here are a couple of pictures. Reading through the replies now.

OMG!   Like others have said … retaining wall.  Can the house be moved?  I had an experience protecting a driveway. This was protection from a drainage ditch. I used many loads of concrete.  It only slowed the process. 15 years later the retaining wall washed out even though it had a 4 foot footing.

Great fluffy muffins!  I'm not an expert and wouldn't dare advise how to fix this but I'm definitely concerned for you now.  I'm really sorry you have to deal with that and I really hope you'll keep us updated.  A creek is one of my nonnegotiables for the property I buy but I wouldn't want the house that close to it.

If high water is eroding the bank, you can try to build a temporary dam with sandbags. Then you can build some sort of retaining wall.

It's possible that building terraces with fill dirt and landscape wall blocks, supplemented by plantings later in the season, will do what you need.

That doesn’t look good. I can see why you are worried. I hope you can use one of the solutions, people here have suggested. Hang in there, I am rooting for you, and sending virtual hugs.

I'm no engineer and I don't play one in the movies, but If it were mine, I'd call someone to drive telephone poles in the ground about ten to twenty feet out into the washout, leaving the top of them at the height of the ground at your porch. They probably should be no more than 4 feet apart, but closer will be better.  Then I'd start filling in behind them with large logs, concrete chunks and dirt, packing as I went along with a excavator. After completion, I would build a retaining wall on the creek side of the telephone poles, tying them back into the newly created bank of logs and dirt. It's not gonna be cheap, but neither is losing your house.

Ok, I have one potentially useful observation...

Erosion during flood events happens due to water velocity. You can - and probably should - be looking into hard landscaping to protect that bank, like a concrete retaining wall. BUT you can also mitigate velocity by directing flows such that your house and the bank area sits in an area of lower velocity water. I'd need to see much more of the landscape upstream, downstream, and around the house to suggest how - and have a much better sense of how the stream floods.

Looking at the picture it looks like it's not just the bank eroding, but also sheeting floodwater over the upper bank level.

If you can slow the water downstream of you, such that the water depth actually increases a little where you are, then the water velocity could be much slower. I've see a layout for a property on stilts on a floodplain. They realised they had no control over water entering their land, and that the water velocity was what would damage their house. They build a retaining bank in a horseshoe shape. Horseshoe was open to the direction of flow and the house was located within the horseshoe. The water depth increases in the horseshoe - slightly - but the water moves much more slowly than on the surrounding floodplane, so the actual damage around the house was reduced. The counterintuitive aspect was that the wall was downstream of the house, not upstream. The bank was planted with shrubs and other plants that had root systems able to anchor the bank effectively and the ends were protected from erosion with large rocks to make a rockery.

Elsewhere on the property, within the area, they had rows of food crops - berry bushes etc...- planted in dense hedges across the flow of water, again, aiming to slow the flow around the vulnerable areas of the property.

Michael Cox wrote:Erosion during flood events happens due to water velocity.

I was thinking something along this line, also. It may not help during this emergency, but longer term, "think like a beaver". Beavers live to slow the water, and provide lots of flat meadows for floodwater to fill, reducing the flows in the entire watershed.

I don't know how much you're allowed to impact the creek. Downstream will help directly with the current flood, but upstream "beaver dam analogies" may help with future rain events.

It would help to know about how large the house in question is, and about how much height there is from the normal creek level to the foundation. My other crazier idea was to get a bunch of chains and anchors to at least stop the whole house from sliding, long enough to do other repairs.

One good option for stabilizing a bank in some climates is bamboo. However, it doesn't work in all climates, so more research would be needed.

I had a similar problem at my place last year.
I am a Civil Engineer so I am creating some water diversion walls to keep the moving water away from where is is going now.
Part of the system is an earthen levy system 3M wide and 1.2M high to obstruct the initial flow
then I am building a sheet metal fence with 6 inch posts set 600mm into the soil at 1M intervals to guide the water
past my buildings for 150 ft.
I have use it before elsewhere effectively.

Water can leak through the metal wall, but it is stationary water and will not erode.
I would not use concrete since it can be undermined.
Some better photos to show things more clearly will help me see exactly what is happening.
A few questions;
- was the water actually moving past the slab edge?
- how deep was the water?
- Has a tree fallen and pushed the water towards the house?
- how high is the small embankment?
- the vegetation looks old, has any erosion actually taken place?

Dude, after 3 days some of us were scanning headlines for news, I was worried about a plaintive obit even... my query: have you tried anything yet? Has water abated in the past few days? Do you have sandbags to fill and place strategically as a first step?  Immense outpouring of concern, please don't leave us all hanging

Can you assemble a friend or three to help out, I hope so
Rico

John F Dean wrote:OMG!   Like others have said … retaining wall.  Can the house be moved?  I had an experience protecting a driveway. This was protection from a drainage ditch. I used many loads of concrete.  It only slowed the process. 15 years later the retaining wall washed out even though it had a 4 foot footing.

The house cannot be moved. The massive granite was blasted to put the house where it sits. It was a... unique choice of.... well, everything, if you ask me. But what do I know? I got in touch with the guy who built the house (thank goodness for small towns) and he told me that he filled a cylinder shaped hole with concrete below the area I pictured. For the life of me I can't locate it, but I tried with only very, very basic tools. I haven't heard of this particular method before, but I've also never worked this close to a creek with such a great slope.

I think it might be helpful if I posted pictures of the rest of the property for reference. I think some kind of retaining wall is essential. But I also have to keep the laws in mind regarding the distance from the creek. What a knot to untangle, huh?

Emmett Ray wrote:Great fluffy muffins!  I'm not an expert and wouldn't dare advise how to fix this but I'm definitely concerned for you now.  I'm really sorry you have to deal with that and I really hope you'll keep us updated.  A creek is one of my nonnegotiables for the property I buy but I wouldn't want the house that close to it.

Thank you for your reply. The funny thing is that the homeowner is the one who specifically laid out and designed the site, from horn to hoof. This was intentional. Which has me scratching not just my own head but other peoples' as well. I don't understand. But, what's done is done, and I get to strengthen my knowledge and abilities by helping to overcome what's before me. How cool is that? Learning and growing is never a bad thing, at least not yet in my experiences.

I'll keep updating. It sounds like this is going to be a knot worth untangling with friends!

Jeremy VanGelder wrote:If high water is eroding the bank, you can try to build a temporary dam with sandbags. Then you can build some sort of retaining wall.

It's possible that building terraces with fill dirt and landscape wall blocks, supplemented by plantings later in the season, will do what you need.

Luckily, I'm not in the desert and not really in the mountains, I'm in this strange spot in between. The creek, I'm told, will all but disappear in a few weeks and it will be gone again until the fall or winter. I will confirm or deny this allegation after I've sat in my sit spot for a full rotation of seasons. Not calling anyone a big fat liar face, but I saw that creek flood to shocking level and I'd only been here a week. Haha. I guess the silver lining there is that the water level is not, to my best estimation, going to be a problem I'll need to contend with again. From what I gather, the level the water reached was something of a record. Thank goodness. (I do have a REALLY cool time lapse of the creek filling up and then another of it receding, I it took many hours both directions but I managed to squish it down to seventeen seconds for one and twenty seconds for the other. Maybe I can figure out how to post them here.)

Anyway, as far as long-term options, my initial thought was trees, having roots in the grade would help to stabilize the slope, unless I'm totally understanding that concept incorrectly. But when I went into planning mode for that, I got met with fire code. Because the slope is so close to the structure, I can't plant trees. Then I was also met with not being able to plant anything within "x" feet of the creek bed. (What constitutes 'the creek bed'? How do you determine that, when it changes, quite literally, every day?)

Then the idea of the terrace came, but I am of the impression that doing that is also not lawful or up to code because of the creek but also, I'm not sure that I have the ability to do so regardless, partially because of inexperience doing so but also because when I walk the slope and surrounding banks, it goes something like, [SOLID STEP - SOLID STEP - SINK TO MY ANKLE - SOLID STEP - SINK TO MID CALF - SOLID STEP - SOLID STEP - HEY, MACARANA!] But up above the creek, the ground is SO HARD I have to use a spade to break up the gravel on the surface.... California is so foreign to me. (I miss Washington terribly.)

So, on goes the search! :)  

Ulla Bisgaard wrote:That doesn’t look good. I can see why you are worried. I hope you can use one of the solutions, people here have suggested. Hang in there, I am rooting for you, and sending virtual hugs.

Virtual hug well received, needed and reciprocated, my greatest thanks!

It's funny, nobody else seems to think it's too great of a deal and my sleep is often disturbed because of it. Interesting how different people can be. Haha!

I'm sure a solution that works for the site, works for the people and keeps the creek happy is right under my nose and I just have to find it.

Thanks again, much love and respect!

F

Rusty Ford wrote:I'm no engineer and I don't play one in the movies, but If it were mine, I'd call someone to drive telephone poles in the ground about ten to twenty feet out into the washout, leaving the top of them at the height of the ground at your porch. They probably should be no more than 4 feet apart, but closer will be better.  Then I'd start filling in behind them with large logs, concrete chunks and dirt, packing as I went along with a excavator. After completion, I would build a retaining wall on the creek side of the telephone poles, tying them back into the newly created bank of logs and dirt. It's not gonna be cheap, but neither is losing your house.

I think I ought to take a few more photos so that there's good reference points. I like your method of thinking and I'm with you as far as your.... process? But execution sounds impossible, because of the site challenges. Maybe I can post photos and pick your brain some more when there's a better idea of what the terrain involves?

Thank you. I appreciate the heck out of your reply.

Michael Cox wrote:Ok, I have one potentially useful observation...

Erosion during flood events happens due to water velocity. You can - and probably should - be looking into hard landscaping to protect that bank, like a concrete retaining wall. BUT you can also mitigate velocity by directing flows such that your house and the bank area sits in an area of lower velocity water. I'd need to see much more of the landscape upstream, downstream, and around the house to suggest how - and have a much better sense of how the stream floods.

Looking at the picture it looks like it's not just the bank eroding, but also sheeting floodwater over the upper bank level.

If you can slow the water downstream of you, such that the water depth actually increases a little where you are, then the water velocity could be much slower. I've see a layout for a property on stilts on a floodplain. They realised they had no control over water entering their land, and that the water velocity was what would damage their house. They build a retaining bank in a horseshoe shape. Horseshoe was open to the direction of flow and the house was located within the horseshoe. The water depth increases in the horseshoe - slightly - but the water moves much more slowly than on the surrounding floodplane, so the actual damage around the house was reduced. The counterintuitive aspect was that the wall was downstream of the house, not upstream. The bank was planted with shrubs and other plants that had root systems able to anchor the bank effectively and the ends were protected from erosion with large rocks to make a rockery.

Elsewhere on the property, within the area, they had rows of food crops - berry bushes etc...- planted in dense hedges across the flow of water, again, aiming to slow the flow around the vulnerable areas of the property.

Thank you for this amazing response. I'm going to go to the creek now for a better vantage point. It also conveniently happens to be where my sit spot is. Two birds, one.... You know the rest. :) Can't wait to post the pictures and see what your amazing mind produces.

I am greatly and magnificently appreciative!!!

John C Daley wrote:I had a similar problem at my place last year.
I am a Civil Engineer so I am creating some water diversion walls to keep the moving water away from where is is going now.
Part of the system is an earthen levy system 3M wide and 1.2M high to obstruct the initial flow
then I am building a sheet metal fence with 6 inch posts set 600mm into the soil at 1M intervals to guide the water
past my buildings for 150 ft.
I have use it before elsewhere effectively.

Water can leak through the metal wall, but it is stationary water and will not erode.
I would not use concrete since it can be undermined.
Some better photos to show things more clearly will help me see exactly what is happening.
A few questions;
- was the water actually moving past the slab edge?
- how deep was the water?
- Has a tree fallen and pushed the water towards the house?
- how high is the small embankment?
- the vegetation looks old, has any erosion actually taken place?

I am appreciative of your response. I am going to take more photos to give a better idea of what's going on. The water has receded to normal flow, which is great, but that's actually not the biggest problem. I think the biggest problem will be obvious from my next photos.

Some of your questions I can't answer well, I've only been here a short time, but I think the photos will take care of the ones I can answer well.

Very appreciative and with love and respect,

F

If you can find a topographic map with enough detail (our Municipal Hall has electronic ones), that would be helpful to post.

It would give us a better idea of the slopes, the high and low water levels, which may give us ideas of how to slow the water down.

They say no planting - but consider what nature plants, and consider if it's possible to "help that along". Definitely California seems to have a wet/dry boom/bust cycle, but that's what Beaver analogue dams are supposed to help. But fire risk is a serious concern and one that needs a lot of thought - the greatest risk is when water is in the shortest supply. I'd be tempted to splurge on a *really* big rainwater tank!

If you can slow the water downstream of you, such that the water depth actually increases a little where you are, then the water velocity could be much slower.

I dont believe this is correct.
Deepening the river bed may speed up the water velocity, but widening the area through which it flows will reduce the velocity of the water.

Jay Angler wrote:If you can find a topographic map with enough detail (our Municipal Hall has electronic ones), that would be helpful to post.

It would give us a better idea of the slopes, the high and low water levels, which may give us ideas of how to slow the water down.

They say no planting - but consider what nature plants, and consider if it's possible to "help that along". Definitely California seems to have a wet/dry boom/bust cycle, but that's what Beaver analogue dams are supposed to help. But fire risk is a serious concern and one that needs a lot of thought - the greatest risk is when water is in the shortest supply. I'd be tempted to splurge on a *really* big rainwater tank!

Of course, when I first come to this site, my eyes get a thousand times too big for my head seeing all the potential and all the things that could be things, but aren't things... Yet. I, unfortunately am not the proud owner of this bizarre piece of property. The dwelling is used as an AirBnB because of it's distance from the southern gate to Yosemite. I live in the caretaker's apartment. The homeowners do reside here but travel frequently. And they are... What's a good term here... Mature folks with a love of marijuana, Volkswagens and tie dye? So they're pretty open-minded, or have been thus far, but aesthetics are really important to them. Like, very important.

The GIS data I've found is hard to interpret, but maybe it's a 'me' issue, I'll go grab them right now and see what we can make of them. I did take a picture that I think demonstrates the terrain difference pretty well, I'll upload it next.

Thank you very much for taking the time to respond. I appreciate you.

This picture has a yellow arrow pointing at the corner that I showed in the photos previously.

An image showing that slab and those rocks would help.
I dont think there is much of a problem there.
Apart from perhaps clearing some dead wood downstream of the house, in the creek bed to prevent water back up, I believe erosion will not be an issue.
Those large rocks will protect this.

I'm with John on the risk assessment. That is granite bedrock and the stream won't be moving it around, just carving downward at a slow pace. As long as you can figure out a way to deflect any extreme flows, the house should be safe.

Relieved to know house did not meet creek, and to know future conjugal relations will be limited to the next flood next year.  

House is intact and, more importantly,  so is your sense of humor.  That's what truly matters in this struggle for survival

Wow! What a place! Those huge rocks are amazing! But it must have been scary watching that creek fill up. So glad all stayed safe.

If there really are concrete support pillars going down to the granite bedrock and if the house base is reinforced properly, it seems less likely the house will slide into the creek. Phew! Some sort of low-growing but tightly matting plant with a strong root network at the edge of the deck to stop the soil sliding down the hill would be reassuring and prevent the house ending up on concrete stilts with no soil under it.

Indeed, Jane is spot on.  Flora will stabilize the soil.  If your idyllic spot was in the granite hills of Georgia I'd suggest mountain laurel and rhododendrons. Keeping them watered and cool over your first year, especially during NoCal hot spells , could ensure successful root structures,  best of luck