New Retaining Wall close to Septic, Help
I need some suggestions from people with more expertise than I about replacement of several retaining walls that are located close to a septic tank.
The wall in the attached pics is about 16 years old and needs to be replaced. This is at the family lake house at The Lake of the Ozarks so no access from below and not a lot of room for heavy equipment above but this is nothing new for most of the area contractors. Because of the limited space the septic tank is located 12″ behind the topmost wall and cannot be relocated. The field though is not behind the wall as it is about 40′ away on the side of the house. The current wall out of creosote treated timbers was poorly designed and constructed(not enough sleepers, lack of weep holes, NO footing) and thus is starting to rot out and tip over. I think the wall needs to be replaced with a masonry wall of some type, but with my utter lack of masonry knowledge I don’t want to jerk around some contractor at the lake by not knowing what I want or need. I need a plan going into this. What is my best option? A formed and poured in place concrete wall, a block wall(are these strong enough with the amount of earth behind it), precast wall slabs, other options?
The walls are 75′ long and 2′, 3′ and 5′ tall respectively going up the hill.
I need a plan because there is no building code in place that governs this in the county and it is hard to find a contractor in this area that is not a dumb good ol’ boy because all the decent ones are tied up doing commercial projects and won’t even bid residential.
Yeah, I’m a contractor but this is way out of my league. I remodel, flip, work alone and the only concrete I do is really little stuff.
Thanks
Day
Edited 3/27/2007 9:22 pm ET by restorationday
Replies
Dry stack block. Lots of brands.
They generally set on a compacted gravel/crusher base. The have a built in step back molde into the tops and bottoms.
As often as you like or needed, you may extend a plastic grid that is wedged between courses into the gravel/sand/earthen fill behind the wall.
Done correctly it should last a looooong time.
Eric
yourcontractor@aol.com
Give Techo Blok a try. They have a nice selection, great quality and they offer an inhouse engineering service to help you or your contractor design the wall correctly. The service is free. Walls like that, you want to make sure everything is done correctly. Last thing you want is a retaining wall failure.
My first reaction to that is that the septic tank is in no immediate danger of going anywhere. You have three walls with a total combined height of 10 feet. That can be easily done with a single wall, if you want it; or a couple of shorter walls. I'd consult with one of the manufacturers of dry-stack modular retaining walls (Versa-Lok is one that comes to mind) as they tend to have engineering staff that will design the wall for you if you buy their products. I'd move the upper one away from the septic tank and maybe extend the wall a bit above grade on each level so that you don't tend to fall off the top.
Someone with a small mini-excavator should be able to get in there and remove the ties, dig the base and put stone, and set the blocks.
As Eric said, Keystone block. Only thing is that if a wall is over 4' than it needs to be engineered, which basically means geo-grid tieing back into the slope which is gonna be pretty hard with a septic tank in the way. OTOH, there shouldn't be hardly any lateral pressure where the septic tank is (just so the tank is solid. Installed, a starting point for a budget might be $12 a sq foot of wall face.
Each wall needs at least 1 row of block below grade, and again as Eric said, the footing is just gravel, plus you put at least 8" or so of gravel backfill behind the wall.
You could actually DIY with a laser and some laborers.
BTW - I think one of the problems with the existing wall is that it was not installed with batter. Batter means that each successive row is set back a little bit. That, and probably the lack of or inadequate deadmen, or sleepers as you call 'em.
I'd do what everyone has said and use blocks. Because using blocks it is easy to curve the walls, I'd also take the opportunity to create some interesting spaces on the terraces, rather than just using the walls to retain the dirt.
Bulge it out and create an outside room, or plant a tree there. Have a bit of fun with it. Whoever built the first wall didn't look like he was enjoying himself at all. He was just fighting gravity.
yes the dry stack would work but i see you will need a little machine and a good operator, looks like it would be easy to flip it, I dont know how to post the pics yet i just finished my block wall with river rock, Boy i would love to build you a wall if i had time, It was a real lotta fun. My buddy was a stone mason and i learned from him, Dont know what kinda rock you have there or how much you can do, I did not want the stack stuff as everyone has it
Very nicely done wall. In this area we have porous sandstone and limestone. In one of the pics you can see the house and it has a chimney and patio wall made out of the rock you find in the area. There is also a seawall built out of the stuff at the bottom of the terraces. I helped with the seawall when I was about 14, we had to work in the winter when the lake was down and build a chute to slide the materials and mortar down the terraces. People have gone away from using the stuff as a building material in recent years because it is a PITA to work with. As for heavy equipment, you could get a small crane or backhoe onto the area between the top terrace and the house but that is it, no access for anything that can't be lifted or carried to the terraces.
Thanks for the help guys.
I was unsure if a block wall would work or not but it sounds like it will. I have noticed that people are starting to use a lot of the stuff in the are now. I think I will go with whatever product whatever contractor I find can get and is experienced with. There should be quite a selection available in the area because almost everything that gets built around there has to have some sort of retaining wall system. The tie wall is not going to get repaired but just torn out, many of the timbers are rotting and you can't get them like that anymore. They were produced by Mennonites nearby but since then even they have stopped making them. I am defiantly not going to do this myself. I would lose more money in lost time at home and on the job here than I would save by DIYing it. The site sucks to work on, bad access including getting heavy trucks actually to the site, and bad work space. The only blessing about the site is that it is at the end of the lake road so there is lots of stagging space on the road side of the house. When I eyeballed the thing I swag'ed at $10k so $12 a face sqft is about right on but I am guessing it is going to be more with the funky access.Such is the joy of owning a lake house I guess,
Day
Look for Landscaping Contractors.They are the ones that would typically built the walls..
.
A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
pics
Im more proud of posting the pics then building the wall ;)
pic of wall
if you can lay block you could use the fake stone and it would look something like this, this is real stone or you could lay block and plaster it
Anchor Block. They are made thru manufacturers about the country via a licencsing agreement.
Here's an incomplete pic of what I'm doing at the kid's house. Properly built, you can see these along highways up to 30 to 40' high.
View Image
View Image
As the others say, there is a lip on the back edge - about 1" wide and hangs down to be keyed in place by the others laid on top.
These blocks we used are in 3 different sizes - 6", 12", and 18." The caps are another piece about 3" thick. Those are turfstones on the bottom - used for a turf covered driveway for his lawn euipment being stored down under.
Edited 3/28/2007 9:45 am ET by peteshlagor
Edited 3/28/2007 9:46 am ET by peteshlagor
Edited 3/28/2007 9:49 am ET by peteshlagor
Dont' listen to anyone that suggest a specific brand of block unless they are willing to haul them from Boston or Oregon or ? for FREE.
Seriously the designs are licensed to local companies and thus the brands and selections will vary.
In don't know if there are any local producers or if the blocks will come from KC, St Lousi, Columbia/Jeff City, Springfield?
There are several producers in the KC area.
Here is a link to an association of manufactures.
http://ncma.org/use/srw.html
They are simple to install or anyone that can follow simple instructions and know how to use a level and a tamper.
.
A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Dry stacks look really nice & provide opportunity for texturing the face with curves etc; but they are also expensive for a remote location in the Ozarks.
There are many tie walls in this part of the country over 30 yrs and they are till standing tall and rot free.
From the pix it looks like 2 problems; 1) they don't look like RR ties but sawed up 6x6s that were not treated as well as RR ties would have been. 2) the dead men into the wall are insufficient in spacing and if you dug them up they are probably just stubs that don't go well into the embankment and have no crossing dead men at their back end.
If cost is an issue you could probably tear down the tie wall and rebuild it but I would cut several ties to see how well they have been treated first.
If that area isn't used much for recreating, ie-you just walk by it instead of using it, I would get an excavator with a thumb and remove existing ties. Re-grade without retaining walls. Put in some larger rocks and some plants to prevent erosion and save mucho time on labor. Thats just my .02 worth. Without having walked the site it is hard to get a true feel for it, but thought I would just throw that one out on the table.
<<<<Re-grade without retaining walls. Put in some larger rocks and <some plants to prevent erosion and save mucho time on labor. I agree,, it looks like they are not needed.The soil looks pretty rocky, like its not gonna slide down the hill...And you can't play croquet there anyway..Bud