Question
On the north side of our new house next to the foundation is a maybe 45 degree angle.  We tiered the slope using large tumbled belgian stone every 3 feet down the slope.    We laid weed barrier and rock in between the stones.  The first year on the first 3 feet away from the cement foundation the dirt settled and we reset the stones.  This year we had heavy rains and dirt washed out under the weed barrier and stones and of course the stones sank again.  We are not sure how the solve this problem.  Would shrubs with a good root system stop the erosion?  We thought about putting a section of cement into the ground at the top of the slope to allow the water to cascade over the stones and rock.  Would this work?  Any advise would be appreciated.

Answer
Hello, Dave ?

The 憈umbled?rocks are probably really nice, but they are no match for the power of water and how it can accelerate erosion in a very quick fashion!  IF the erosion is not too extensive, then yes, a deep-rooted tree or shrub may help hold the hillside together.

However, it sounds like you are having water flow on top of, or across the face of the bank ?a HUGE no-no, if you actually want the slope to stay put.  The side that the slope is facing isn抰 as important as keeping water off of it.  Not knowing how the water gets from the top of the slope to the bottom, I can only give you general suggestions.  

If so (lots of water flow), then rain gutters are a must, with minimum 6-inch diameter pipes, leading to the TOE of the slope, and NOT discharging on top of, or across the face of the slope.

Where the drainage pipe, that either catching the water from the ground, or off of the roof, comes out will also need some sort of treatment ?drain rocks or a flared-end.   If it is a large volume of water (as in a 搘ater fall?, I have installed these across slope faces, but only with special rubber/plastic sheets designed for this kind of application.  

We would use recirculation pumps and catchment ponds at the bottom of the slope ?a true water feature and not just a natural "drainage swale".  

You can also 揳rmor?a slope, but a few rocks and weed barrier is not enough.  A minimum depth is going to be 6-inches of rock material all the way down (like a real creek bed).  Better if it is 1 foot thick, with a bed & bank.  Sorry. Not cheap, but if you do end up creating a 揹ry?or wet creek with pumps that could then be allowed to overflow in heavy rain events), it could look mighty handsome.  

http://patrickbertholfhomerepairs.com/photogallery/Job%20photos/DSC01683.JPG

Building a concrete apron might work, depending on how it was constructed.  Shrubs could help the situation, but again, if the water is the problem, then the water needs to be intercepted before it can do any further damage.

And as this article says -- and I concur -- sometimes if the problem is bad enough, you抳e just got to break down and hire a professional!  

http://www.walterreeves.com/landscaping/article.phtml?cat=32&id=723

Hope some of these ideas helped.