Mudslides

#1
Really not my field of expertise, folks, but a colleague of mine and her fcukwitted husband were dumb enough to ignore the maxim that if it appears to be true, then it probably is.

Accordingly, they bought themselves a fixer-upper property on a slope within a small canyon. Unfortunately for them, like most Southern Californian canyons, a paucity of vegetation leaves the area prone to mudslides- and we have heavy storms forecast for this weekend.

Now, Civ Eng was my dad's gig, not mine, and he'll be getting a call in the morning, but he's used to big, captial projects that are planned years in advance and I figure you lot are much better versed in improvisation. I'm a little bit sceptical about my colleague's plan, which as far as I can tell involves just laying plastic sheeting on the slope and hoping for the best. I'm wondering if any of you might have some better ideas about controlling, or at least minimising the risk and damage. Preferably ideas that don't involve any equipment that can't be begged, borrowed or stolen from friends, neighbours or The Home Depot. Labour is not a problem

I can PM the address if anyone wants to take a look at the topogaphy on Google Earth. Possibly some photos tomorrow afternoon. As regards the geology, I don't have a clue. The soil is bone dry because it hasn't rained properly here since about March and is fairly sandy. I don't know if this means that it's going to be better at retaining water, or whether this means that it's going to be more prone to liquefaction.

Any help you can give me would be most apprecated, both in terms of practical plans or just general things to look out for and consider. If you want to rip the p1ss, go ahead because, quite frankly, I don't like the dappy bint that much anyway and neither does anyone else. We just want to be able to say that we gave it our best shot.

Cheers.
 
#3
CutLunchCommando said:
Why are they so sure there is a significant (ie actionable) risk to their property?

EDIT: Best send the grid mate. I'm not a geotechnical but I know a few.
The place got "yellow-tagged" (minor structural damage) in a slide a year or two ago. Don't ask me why they're still there...

Address for Google Earth purposes on the way to you.
 
#5
A fence should do the trick. V-shaped in plan with the pointy end pointing uphill. Probably 20' high should do it - and 50' deep. And the fence posts next to each other. Fix leaky hoses connected to a high pressure water supply at 1', 3' and 5' above the existing ground level - this will encourage a mudslide to travel along the fence, rather than build up against it.

Or dig away at the canyon walls until the slope is less than the natural angle of repose of the soil. You did say that labour was no problem. You could use a high pressure jet to do this, but be careful or you may trigger a mudslide.

Construct a biodome above the property extending at least a mile beyond the canyon walls and dig a trench around it to divert surface water.

Remove all soil and replace with reinforced concrete.

Get lots of liquid nitrogen and create permafrost in the soil.

Turn to God and pray that it doesn't rain.

Increase the house insurance and have a 7-day break in Australia, starting Thursday.


Hope this has been useful.

PS If the soil is sandy, you're unlikely to have a mudslide. Mudslides require mud. Wetting and rolling (compacting) may help, especially if a bit of cement is rotovated in.
 
#7
putteesinmyhands said:
Get lots of liquid nitrogen and create permafrost in the soil.




If I were them, I woudn't bother with any DIY or gardening this week, I'd be putting all my wordly goods into storage and sleeping in my truck. :)
 
#9
CutLunchCommando said:
Puttees advice is all good.....

It looks like they are on top of the slope and there has been a slump, but then I'm no photo-interpreter.
If they're on top of the slope, you'll also need a D-shaped fence on the downhill side. Use 50' long fenceposts, hammered fully into the ground, side by side.


Incidentally, these fenceposts also go by the name of "driven piles." (But that would make my reply a serious one, and it would be a bit impractical to get it done by the weekend).
 
#11
crabtastic said:
Really not my field of expertise, folks, but a colleague of mine and her fcukwitted husband were dumb enough to ignore the maxim that if it appears to be true, then it probably is.

Accordingly, they bought themselves a fixer-upper property on a slope within a small canyon. Unfortunately for them, like most Southern Californian canyons, a paucity of vegetation leaves the area prone to mudslides- and we have heavy storms forecast for this weekend.

Now, Civ Eng was my dad's gig, not mine, and he'll be getting a call in the morning, but he's used to big, captial projects that are planned years in advance and I figure you lot are much better versed in improvisation. I'm a little bit sceptical about my colleague's plan, which as far as I can tell involves just laying plastic sheeting on the slope and hoping for the best. I'm wondering if any of you might have some better ideas about controlling, or at least minimising the risk and damage. Preferably ideas that don't involve any equipment that can't be begged, borrowed or stolen from friends, neighbours or The Home Depot. Labour is not a problem

I can PM the address if anyone wants to take a look at the topogaphy on Google Earth. Possibly some photos tomorrow afternoon. As regards the geology, I don't have a clue. The soil is bone dry because it hasn't rained properly here since about March and is fairly sandy. I don't know if this means that it's going to be better at retaining water, or whether this means that it's going to be more prone to liquefaction.

Any help you can give me would be most apprecated, both in terms of practical plans or just general things to look out for and consider. If you want to rip the p1ss, go ahead because, quite frankly, I don't like the dappy bint that much anyway and neither does anyone else. We just want to be able to say that we gave it our best shot.

Cheers.
Crab, had a similar house in Scotland outside Dunkeld half way up a steep sided slope, some call it a mountain. Dig a series, depends how much money they have, of 6ft deep trenches and fill with gravel or similar about 20 ft from the direction of any potential water flow. Ditto about 6 ft from house. Ensure said trenches are long enough to carry the water well away from the house either side. Solved my problem :)
 
#12
I'll pass on the suggestions.

I don't think the Biodome will be a starter- I've seen that movie with Pauly Shore and the Baldwin that was in The Usual Suspects and I think it's a scenario not best repeated.

There's a bloke with an ice-cream van a couple of doors down- we'll see if we can get him to crank the juice on that baby up a little bit to try and create a permafrost layer at Latitude N34 and 800ft amsl.

As for the barrier fence, I think it's a capital idea. I don't think they like their next door neighbours or their house, and it'll be an excellent opportunity to extend their garden to the side. If it doesn't rain, the local feral kids can play fortress on it (or get into training for when they get deported and have to jump back over the border fence again).

I think I'll just suggest that they have a word with the local gansters to see if there are any bodies that need disappearing. Throw a couple of Korean shopkeepers who are behind in their payments in the garage, hope to fcuk that there will be a mudslide otherwise they'll just be lumped with a houseful of Asians and then use the backhanders from the cholos to help build a new place in a less fcuking retarded location.

In the mean time, I'll help them lay out the plastic sheet and hope they don't get upset when I get out a hose-pipe and charge the aforementioned urchins a nominal fee to use the biggest "Slip-n-slide" any of them have ever seen. Might as well do what we can to keep morale up, eh?
 
#14
(Quote the source and argue that it's free advertising?)
 
#16
Yeah, we tipped up there today. What she, and Google Earth failed to point out was that there was a 25ft-deep gulley running immediately alongside her house from the last mudslide 3 years ago. I have to admit, I was quite impressed, especially about the bit where it sent 6 cars rolling down the street when it all went. The foundation is exposed on one side.

We laid out the plastic sheeting- was a bit like putting a band-aid on an axe wound. I think a good prayer would work as well as anything else. I left feeling bloody glad I'm not her. She can't move because, since the house is "yellow-tagged" she can't sell up and the city has to approve the repairs/mods to the house, and have yet to do so.

All we have to do now is wait and see- serves her right for being a feminist. (Incidentally, no "wimmin" from work showed up to help, only a handful of blokes.)
 
#17
A 25' deep gulley? From 3 years ago? So she hasn't got round to doing anything permanent about it then?

Fighting Mother Nature doesn't come cheap. It's usually more economical to give in without a fight.

Has she considered emigrating to the Old Country? I'm sure she could find a property with wonderful cliff-top views (and quaint receding garden) for a fraction of the price of a similar property located in a flood plain.

It sounds like she would have been better off putting the money she spent on the polythene towards a nice caravan. At least then, she'd be able to temporarily relocate her home every time that rain is forecast.

Her surname isn't Canute, by any chance?
 
#18
Funny, looking at GoogleEarth/GoogleMaps (same imagery on both btw) the phrase that sprang to my mind was band aid on an exit wound. The plastic will help protect the remaining bit of yard they have but it wont have any effect on the underlying process I think.

Looking at the imagery there are several houses with very distinct and quite expansive backyards delineated by fenclines either side of an area about 60m across where said fenclines obviously absent which I take to be the area of the slump. There is a row of 4 houses starting at the junction with the cul-de-sac half way down the road. I assume the property in question is one of these.

Looking at the terrain feature on GoogleMaps it looks like they live on the edge of a plain which was once the edge of a lake or shallow bit of sea (hence the sand presumably). This plain is being cut into by water channels. The area to the north of the road is the upper end of a reentrant which will be gathering all the water flowing of the plain during rain events and consequently being eroded.

Some sort of culverting or canalising might help slow or arrest the erosion but wont put the slump back in place. Essentially the cost of works acceptable to the authorities is likely to exceed the value of the house at the minute.

Edited to change cost to value.
 
#20
putteesinmyhands said:
A 25' deep gulley? From 3 years ago? So she hasn't got round to doing anything permanent about it then?

Fighting Mother Nature doesn't come cheap. It's usually more economical to give in without a fight.

Has she considered emigrating to the Old Country? I'm sure she could find a property with wonderful cliff-top views (and quaint receding garden) for a fraction of the price of a similar property located in a flood plain.

It sounds like she would have been better off putting the money she spent on the polythene towards a nice caravan. At least then, she'd be able to temporarily relocate her home every time that rain is forecast.

Her surname isn't Canute, by any chance?
Part of the "Yellow Tag" process after fire/flood/mudslide/earthquake is that any repair/mod has to be approved by city engineers. She's in a bit of a bind because most of the gulley actually exists in her neighbour's property and he, by her account, is a bit of a cnut who just wants to turn the gulley into a long driveway.

It's raining now. The sheets are down. I'm just idly wondering what she's planning on doing about the 100ft of slope that's still uncovered above her house. (For the land of the free/home of the brave you'd have no idea how Byzantine local government can be over here.) I'm not going to worry too much about it because I'm off to Vegas tonight to stuff some of my hard-earned wedge into some stripper's arrse crack and hopefully watch Ricky Hatton give that gobby tw@t Floyd Mayweather a right royal pasting.
 

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