CCA retaining wall and deck giving me nightmares!

[mrbstephens]

We bought our house a year and a half ago with the dreams of growing food for ourselves on our new property. A couple of weeks ago we cut trees down on top of a hill that is held up by a retaining wall and is also next to our deck. A few days ago, it occurred to me that probably, the retaining wall is made of CCA and quite possibly the posts for the deck as well. This is really upsetting to me as I've been planing to plant tons of veggies, fruits and berries on top of this hill, next to the retaining wall, and up against the deck. Please tell me, what to do!

Here's a couple of pictures to help you see what I'm talking about..

 

[mrbstephens]

 

[Joel_BC]

I'm assuming that CCA is creosote-soaked dimensional timbers (?) - no doubt they're some kind of treated timbers. That's what your pictures look like to me. CCA is probably an American or East Coast term.

If the bank is fairly stablized into position, I'd wait until the rains and/or groundwater flush of spring is past, and then start to remove the stacks of timber (the current cribbing) and replace with poured reinforced concrete, before the bank can shift. Section by section.

I'd probably want to take some soil samples from near the timbers, for analysis to see how much the soil near them may be contaminated with toxic chemicals. If that is more than you can afford (in addition to changing your retaining-wall system), I'd just avoid planting edible plants very near where the existing cribbing has been. You could instead plant some decorative leafy and/or flowering plants along where the wall has been.

Just some thoughts from looking at your pics, but not knowing much about the situation there.

 

[DeniseCharleson]

....A few days ago, it occurred to me that probably, the retaining wall is made of CCA and quite possibly the posts for the deck as well....

Chromated Copper Arsenate?

 

[mrbstephens]

I'm assuming it's CCA (Chromated copper arsenate). The arsenate is arsenic. Yes, I'm planning on having the soil tested and would like to replace the wall with something else eventually.

 

[mrbstephens]

But not sure about the deck......I don't know for sure what it's made of. They say that if it's greenish, that's CCA, but where I live every kind of wood turns green eventually. I'm near the water and algae grows everywhere here. I wanted to plant fig trees near the deck, but don't know if that's such a good idea.

 

[Justme]

If it were me I would wait for results of a soil test before doing anything. CCA treated wood for residential areas was phased out by 2003 with a few exceptions. That wall doesnt look very old so it may may not be except that those are large timbers and being a wall like they may have made the exception. Same thing with the deck- depends on when it was built and if rules were followed. It is really hard to tell by looking after they are a few years old especially if you are only looking at the outsides. When fresh cca treated wood does have an olive green color but that fades somewhat after a couple of years. Sometimes you can make a fresh cut and still see the color on on the cut..
The area on the hill would not concern me since it s uphill. But I would still have it tested nutrient purposes.
You could consider planting things near the wall in pots or planter boxes. would be less expensive that rebuilding that wall. Also if it does turn out to be CCA you would have to replace soil in addition to the wall. I am not sure if it is possible but if you find much the soil results are positive for cca you might have the amounts still present in the wood checked. It may be that most is leached from the wood by now and all you really have to worry about is the soil.

I would also reconsider putting a fig tree near the deck. This is experience talking here. Unless you are very good at picking the figs some are going to fall off and create a mess on the deck. Not to mention the ones that the squirls and birds drop when they are thieving. Also the half eaten ones that the thieves leave on the tree and ones that may get over ripe will attract flies,nats and wasps. Not critters you want to encourage near your deck. My fig tree came with the house and was huge already when we bought the house. I have hated it there ever since. It is now close to 30 years old and showing its age. I have rooted several cuttings from it and one day I will actually plant one somewhere else in the yard instead of selling them and will remove the origional.

Good luck.
It appears in the pic that the hill is fairly steep so you might find that on that you need a series of new walls the combat erosion. Since you just removed those trees and I assume are planning tilling and disturbing the soil to plant garden don't be surprised to find all your garden washed up next to the wall after a heavy rain. Even just a few sand bags could help.

 

[~gd]

I'm assuming that CCA is creosote-soaked dimensional timbers (?) - no doubt they're some kind of treated timbers. That's what your pictures look like to me. CCA is probably an American or East Coast term.

If the bank is fairly stablized into position, I'd wait until the rains and/or groundwater flush of spring is past, and then start to remove the stacks of timber (the current cribbing) and replace with poured reinforced concrete, before the bank can shift. Section by section.

I'd probably want to take some soil samples from near the timbers, for analysis to see how much the soil near them may be contaminated with toxic chemicals. If that is more than you can afford (in addition to changing your retaining-wall system), I'd just avoid planting edible plants very near where the existing cribbing has been. You could instead plant some decorative leafy and/or flowering plants along where the wall has been.

Just some thoughts from looking at your pics, but not knowing much about the situation there.

`Joel here in the USA you can usually get soil samples tested very reasonally by the Coopative Extension Service, they send them off to the Land Grant Colleges for testing/ The whole system was finanaced by sale of lands in the western states. many colleges were started with these funds but everyCounty has a Coop Ext office. In many counties they mostly aid farmers but even the 5 counties that maje up NYC have offices.
I don't know if they will test for toxiins but 1 phone call will get you the info you need about sample containers and methods to use. If they don't do the tests they can direct you where to look. I directed this to Joel because I have no ldea if Canada has a system like it.

 

[mrbstephens]

Here is a link for soil testing:
http://soilhealth.cals.cornell.edu/extension/test.htm#storage

I would have the soil tested for heavy metals to find the levels of arsenic. I'll be planting on the top of the hill this year where the trees were cut down. Next year, we'll be replacing the retaining wall and add tiers to the front of the slope to make it more user friendly. If the soil tests high for arsenic, I'll be planting flowers in those areas. Down below the retaining wall we'll be putting in high, raised beds and will line them with something. Essentially, super large planters. I've found out that the deck is cedar, but the posts holding it up is CCA. I won't be planting anything but flowering shrubs around it, and I'll plant the fig trees somewhere else. Thanks for your help everyone!

 

[ThrottleJockey]

I built retaining walls of every sort for about 15 years. It's hard to tell from the pics but that one doesn't appear to be built properly in the first place. It also appears like it may be suffering from early stage premature failure. Again, without actually being there I can't tell but it looks like you could just take it out without much concern and as long as you keep some sort of ground cover, there shouldn't be much erosion to worry about. At least not short term. A way you might save tons of money would be to replace it eventually with a series of short boulder walls terraced into as many steps as you wish. Boulder walls are the big thing right now and have been for about 10 years or so, this is primarily because they look good, last forever, are really really really easy to build and boulders are frigging cheap or free! If you live anywhere near farmland you may be able to get farmers to even PAY YOU to haul them away. If you go that route, after you finish the build, pressure wash the stone and spray it with concrete sealer (I like Sparkle). The sealer will give them a "wet" look and bring out the color as well as any other features the stone may have naturally but only show when wet. If you use any sort of timber, expect a short lifespan and regular repair. If you choose engineered block, expect ridiculous expense in materials and to be done properly, massive amounts of labor or cost. I do not recommend building with engineered block yourself if you've never done it before. Block really is labor intense, tedious work with many steps no one will tell you about because most just don't know. Also with block even the slightest error will cause failure or a very bad looking wall. You cannot cut corners when building block walls. I typically would warranty most of my walls for 60 years knowing they would last more than 100, or for the same length of time the engineered block was warranted for in the case of block walls. If you ever need any input about a wall, don't hesitate to ask!