I'm here Los Angeles and there are alot of houses in the surrounding neighborhood that are built on slopes. In addition to retaining walls (many built from "recyled" concrete), houses here use ivy as ground cover/erosion control.

Here's a link to the concrete wall approach http://www.sbbg.org/index.cfm?fuseaction=enews.article&article_id=192

Perhaps a combination of the two?

Good luck.

Grading across a property line is illegal unless you own the other land or have an easement. You are also talking about encroaching on a conservation area.

A wall over 4' high requires a structural engineer's design in almost every state. You have a huge surcharge (pool filled with water) and a wall that already failed. This is very serious. If you don't have the money to remedy the situation correctly. you might need to demo the pool and re-grade the back yard so that it does not require a wall.

It was people taking shortcuts that got you into this mess. You can continue down that path if you want, but the results won't get any better in my opinion. Look for advice from qualified people. Right now you are asking a group made up of mostly home gardeners for engineering advice - does that make sense?

It seems to me there must be a regulatory environment in the form of your building codes and the terms of the conservation area that will give you some guidelines to determine whether the option you are considering is in fact legal. Can you tell us what the constraints and requirements are?

Do you know anything about the history of how the neighbours came to have slopes and your house came to have a wall? Do any of the others have pools and if so, how's that working out? In our town a couple of years ago, a pool installed at the top of a steep slope apparently generated failure of the slope, causing a mudslide that destroyed houses below and caused loss of life. Even if you only have a conservation area there, you might be required to pay for the cost of clean-up, and if there is something like a fish stream involved, lawsuits can ensue. Do the conservation authorities know about your wall failure yet?

If you do a new wall, it should indeed be done properly if at all. I shudder to think of the liability issues should it fail, for example under a future owner causing injury.

Or of growing ivy - a noxious weed - into a conservation area.

KarinL
(home gardener :-))

Thanks for the replies. To be honest I really don't know much about the history of our place and our neighbors' places, looks like I have some research to do. And I honestly didn't know grading across a property line was illegal. Looks like I'll contact SFWMD and see if they can be of assistance. Thanks.

Can you see where your wall went? What was it made of? if cement blocks they could be cleaned up with chisel & hammer, I did mine after Northridge earthquake, much cheaper than hiring someone to come & haul them away & get a new wall. Of course I mixed cement in wheelbarrow & dad set the blocks. used rebar both in the blocks & across to strengthen it. In your case because it is a retaining wall you have to have a cement base. But if you could retrieve all your blocks you could cut the expense greatly. Might have retaining wall put in with chain link fence on top of it or wood as that would cut cost by probably 2/3 but you need to find out why earth is moving. I know of some swimming pools that have poorly built fences or no fences,just hedge & ground isn't moving just because of the pool. If the fill in your backyard is mostly sand that could cause problems. We have some areas out here in Ca. that are extremely unstable- guess you saw the beachside community that buried number of people few years back. People love a hillside house & every couple of yrs some slide down on top of other houses but they just fill it in & rebuild. Good Luck!