I think you idea is the only way. That in conjunction with a skidsteer with breaker attachment. Either way you'll have to replace 5' of the neighbors yard anyway.

 

It would appear that the 5' or so that will need to be removed is actually on the HO's side of the property line. Neighbors don't really have a choice in that case. The developer evidently wasn't very good at math and angles. The lots all wrap around a hillside and none of them are square at all. Consequently, surveying the lot is nearly impossible as the developer just threw the houses in as he saw fit. At this point we don't really have any idea where the property line is in relation to the wall. The neighbors need to face the reality though. If that wall comes down during spring runoff, their yard and driveway and possibly some of their garage come with it.

 

I can't see the situation, but have a possible suggestion.

If you work from end to end (front to back) in sections, it moght be good the break/crack the wall into managable lengths (7-8 feet), so what your are removing does not cause an unintentional effect on the rest of the wall. - It might help to keep thing under control with a touchy situation.

Breaking/cracking of the wall could be by sawing partially or by a jackhammer. You want to create a weak line, not really to totally separate into individual sections. For a cantiler wall, the most and heaviest steel is usually vertical and the horizontal steel is less.

Just a suggestion.

 

That's almost the exact conclusion we are coming to. Working front to back and using a concrete saw to seam the wall for a more precise break in about 5-7" sections.

One other detail is my opinion as to why the wall hasn't failed yet. There is something of a slight convex curve to the wall in relation to the HO's home. Or with reference to the hillside, the center of the wall is set deeper into the hillside, with the ends curving/curling slightly around the HO's home to the downhill direction. I think this is adding stability that would otherwise not be there, and if the wall were absolutely straight it would probably have already failed. If we then remove one end of the curve it would reduce the bearing capability of the center of the wall. Our plan is to use lag bolts achored into the driveway and retaining wall to build a series of braces.

 

#1 get a surveyor to locate the property line and stake it (no big deal probably only $500 plus or minus
#2 what are you replacing the wall with? If you are using blocks such as keystone or unilock you will need to put in geogrid which means digging back as far as 8 feet. If you are using concrete you will have a lot of excavating to do i read it as almost 12 feet from high side.... strike that you are in Utah... You have to dig 5 feet deep than another however many feet to go below the frost line.
#3 get an engineer on this job big time
#4 here is something differenet I have had to do this before and it works. dont worry about where your wall height is less than 4 feet. go in with an excavator on the top the way your contractors recommended then where it is greater than about 1 foot behind the wall to depth and place sheeting in there to hold the bank back. you will have to do this anyway.... I wouldnt have a 8' tall sheer face looking over a nieghbors driveway huge liability. you chould have an engineer design your sheeting for this becasuse it all depends upon soil types for you situation etc. I am not sure that you will be able to pull this off for less than 20k honestly

 

1. Survey quoted twice at $1200.
2. Boulders are preferable. That will reduce the cost of the wall significantly. He is also wanting to change to a couple terraces instead of a single 8' wall. Three 2.5' walls should do the trick. So the debate becomes one of boulder size.
3. Architects/Engineers estimating for a poured concrete wall have suggested $20K. Excavators and boulder retaining wall landscapers have all bid around $7K.
4. I can't go in behind the wall. The neighbors don't want their yard torn up. As to your other point. There wouldn't be an 8' sheer wall looming over the neighbors property, it would be looming over the HO's property. I don't think the excavated wall would be in danger of coming down during the 3 days that it will take to construct a new boulder wall. I dig plenty of 8' sheer faces for basement foundations that sit there for weeks with excavators perched on the edge without coming down.

 

Have you confirmed the actual dimensions of the wall? If the 8' is above the HOs grade how deep is the wall below grade (below frost presumably)? Is there a horizontal component to the wall (a cantilever under that 8' deep backfill) that you will be removing? I would be surprised if all there is to the wall is an 8' high, 1 foot thick wall sitting on grade.

 

If the wall was done correctly the footing would be 30" deep to get below the frost line and there would likely be a 3-4' canted footing. Problem is that there is little evidence suggesting that it was done correctly, otherwise it wouldn't be failing. The wall is actually about 7.5' above grade. It could be the appropriate 9' tall with a 3' wide 12" thick canted footing. OTOH, it could simply be an 8' wall with a standard 20" wide footing, as I have no idea if the original installers knew what they were doing.

He doesn't yet own the property so we have no way of determining that info. We have to simply assume that the wall was done correctly and that excavation will require the removal of a canted footing.

 

are you really willing to risk installing an un engineered 8 foot high wall made of boulders? your subs arent responsible for this you are! I would run from this one and not get involved let someone else takethe liability in NY anything over 4' needs a licensed engineer to sign off on it. Here is an idea... can you leave the wall be, build a new one in front of it and just groute the void with say k-crete?

 

That is a good idea, and I really wish I could simply build a new wall in front of it, but the walkway between the wall and garage is already too cramped.

An 8' boulder wall would require engineering here too, but not three 2.5' boulder walls. He is thinking he'll do the first 2.5' wall three feet from the garage wall, then cut a terrace back about 2 feet. Then another 2.5' wall and again a 2' terrace, followed by a final 2.5' wall that should end up right on the property line. Anyway, I'm not taking on any liability on this one. I'm not being hired for the job. A family member is trying to figure out the best way to do this.

 

oh and as for your comment about having 8' sheer faces when you dig foundations that is on a construction site.... this is a home if the bank collapses with a foundation you redig it if this bank collapses what will happen. will it have any adverse effect on the neighbors property or the HO's property? and most importantly how good is your insurance?

 

The 2.5' wall with only 2' set backs and then another .... adjacent to another home? That will not fly unless you have a dumb engineer and an even dumber permitter/plan approver or inspector. Even with mafia blocks, you would have a hard time. The short set-back "ruse" solution is a classic and is well know to most people.

Just make sure you let your family member the predicted challenges and the possible probelms that can occur when digging close to another home and on the property line.

Jobs like this can appear to be too simple, especially if you have preconceived ideas and solutions. If you have basements, the possiblity of problems go way up, but underpinning a slab on grade that has lost some support is not cheap either.

The $20,000 cost figure may not be practical for both removal and replacement. If you have a good engineered wall of segmental retaining wall block, your family members could do the replacement portion of the wall if they have time and are willing to work and rent some equipment. With a good design, the construction is just a lot of work until you are up a few feet. A contractor probably not be able to do both removal and construction for the suggested price.

 

If I'm not mistaken, the neighbor's house is about 20' from the property line, not sure if that would change things. The segmental block is just a ton more expensive than boulders. I've seen the "terraced' short boulder walls many times and wasn't aware that it wasn't kosher.

 

Ok all you excavation pros. How would you go about removing this wall?

Situation:

Older home: mid 1960s
Retaining wall: 55' long X 8' high X 12" thick
Material: poured concrete
​

Mini ex with rubber tracks equipped with a hammer, and a skid loader to remove and load the debris onto a truck, or dumpster can, if no truck is available.

I won't even try to address some of the other problems you are dealing with there. With the exception that the neighbor may have no choice in the matter, but to allow access onto his property in order for the wall to be replaced.​

 

I like the idea of scoring the wall into sections so it breaks where you want it for removal. You can be reasonably precise that way.

As for the wall itself, have you considered some of the landscaping block products? I've done HUGE, tall, long walls and terraces with them. Each course steps back a little and the slope gives the finished wall a "safe" feel. I would recommend added a reverse curve or serpentine to the design as this will help strengthen it. I've seen massive commercial and DOT walls done like this. Price is probably more than 20K though...

 

have you seen these walls? http://www.hilfiker.com/www/index.html I was quoted about $10.00 for a face sq ft of wall i want to build. My walls will start from nothing and and go 50' out to a corner hight of 14'. so an average of 7' for figuring. $7000.00 for the materials. no labor ,no shipping
Just a thought. they look great covered in vegatation

 

have you seen these walls? http://www.hilfiker.com/www/index.html I was quoted about $10.00 for a face sq ft of wall i want to build. My walls will start from nothing and and go 50' out to a corner hight of 14'. so an average of 7' for figuring. $7000.00 for the materials. no labor ,no shipping
Just a thought. they look great covered in vegatation

That would really be nice covered in some climbing roses with a continuous bloom. Definitely something I could suggest to him.

 

For this job i think your best bet would be to get steel sheeting driven in on the property line. then dig out the old wall from the back. pour a new wall in its place but tie it into the front of the sheets. as more support. then cut the top of the sheets off about 5 feet below grade and back fill the whole thing with crushed stone for drainage. then you will have a pretty good product at the end. but it would be costly your looking at buying 28 sheets to do the job and paying someone to drive them in.

 

For this job i think your best bet would be to get steel sheeting driven in on the property line. then dig out the old wall from the back. pour a new wall in its place but tie it into the front of the sheets. as more support. then cut the top of the sheets off about 5 feet below grade and back fill the whole thing with crushed stone for drainage. then you will have a pretty good product at the end. but it would be costly your looking at buying 28 sheets to do the job and paying someone to drive them in.

AGREED.... I really wish you took some of our advice seriously cache this could develop to a VERY dangerous situation if you arent careful

 

Segmental retaining walls (SRWs) are not required to be below the frost level. Because of this, the old spread portion of the footings can remain. Segmental walls cannot be place directly on concrete.

The footings can remain as long as you can get at least a foot or so of compacted base over the the concrete and the toe of the wall a foot or so deep (depending on the wall height).

Both inside and outside curves can easily be built with SRWs and the tops can be stepped up or down.

 

Everyone is saying this is mini excavator work. i would attempt it. For this the smallest i would use is our cat 325c. but i would still look into steel sheeting or soldierbeam and lagging. I know your trying to keep the budget low but you say its an 8' high wall which is not the case its at least a 13' high wall. saying 5' is burried also being so close to the garage you need to work from the back side of the wall. you may want to look into digging out the section by the garage and having a crane there to lift that section out in one piece so that you don't chance dropping that piece of the wall on the garage. no matter how you look at it this job is more like a $100,000 dollar job. I would not run from this job but i have the rescources for it this is not a job for amateurs

 

I'm positive that this would work, but it isn't even within the realms of reality. Brother is planning to spend $50K in renovations + whatever the retaining wall costs. I could tear down the house, fix the wall, and build a similar house for $150K. I live in northern Utah. Median home price is $190K including the 1/4acre of land it sits on.

 

damn john- 100k, you trying to scare the hell out of the man! In his first post 20k was an exageration. Cranes, driving sheet pile, cutting off 5' below grade- how deep did you drive it? Then what throw all that cut of steel away? Your way will no dought work but this man is not a rich developer building a condo on the beach. For 100k he could tear down the garage build the wall the easy way then rebuild the garage. I think tear it down carfully like most have suggested then rebuild with segmental block like concretemasonry said or the living reenforced earth wire wall like i mentioned. I think it could be done for arround 10k or less than 20k anyway.

 

LOL are you people serious driving sheets

Put some pictures up what kind of ground are you in are you in the nothern hemisphere all that other bs. Talk to the nieghbor if you have to do some reconstruction are you talkin rare redwoods or some crappy bushes and top soil the hes gonna lose anyway when the wall fails? Maybe this new wall will increase the value of his home also. Be slow methodical is this somthing you can handle and still make a profit maybe time + masterial would be better for the stabilization and a solid price on the wall and do you want to get involved with bs in the first place? BTW is there any chance of shifting the driveway

 

Put some pictures up what kind of ground are you in are you in the nothern hemisphere all that other bs. Talk to the nieghbor if you have to do some reconstruction are you talkin rare redwoods or some crappy bushes and top soil the hes gonna lose anyway when the wall fails? Maybe this new wall will increase the value of his home also. Be slow methodical is this somthing you can handle and still make a profit maybe time + masterial would be better for the stabilization and a solid price on the wall and do you want to get involved with bs in the first place? BTW is there any chance of shifting the driveway

Yes, we are talking crappy bushes that would need to be replaced. the wall will probably greatly increase the curb appeal of the neighbor's property if done right.

I'm a builder, not an excavator. I'm not trying to make a profit on this. I'm just helping out a family member for free.

I'll try to snap a picture of it. I'm almost positive they are sitting on hard pack clay and river rock.

 

So I got responses back from the inspectors about doing a boulder wall in terraces. Essentially, they said that we would be fine doing one 4' wall and then stepping back at least 4' for the terrace and doing another 4' wall. During the discussion they mentioned certain qualifiers for this.

• There can be no slope from the top of the upper wall. Once we reach the top of the second wall, the grade on the neighbor's lot must be flat.
• The terrace should be at least as deep as the height of the supporting wall.
• Some type of geomesh with gravel for drainage should be used behind the boulders to prevent the wall from washing out during runoff.

The proposed wall will follow those guidelines, so the inspectors won't have a problem with it. Still need to talk to the neighbors to determine how everyone feels about the property line. The survey has been quoted at $1200-$1400 from a couple different people, because essentially the surveyor will have to re-establish boundaries for a good portion of the neighborhood in order to have any reliable reference point.

 

$600 each sounds reasonable for the
peace of mind and enhanced safety
for both property owners.
Your brother needs to have the neighbor
over for some brews and a heart to heart.
The new wall is a mutually beneficial
project, and he's getting the best end of the deal.