Building 20' retaining wall adjacent to the property line

[ANgK]

We are working on options for a 20 feet tall retaining wall. The problem is the wall will be 1-5 ft from the property line. Soil nail is an option but the nails will be drilled into adjacent property and it is a headache that we hope to avoid.

What would be other options for this wall? I think soldier pile wall may be an options. I have also heard that there is a way for the near-vertical angle of the soil nails.

 

[oldestguy]

You should provide much more info, such as a cross section, nearby buildings, soil, rock situation, etc. The more complete your description, the sooner something of value may come from us. Too often important things show up later negating all earlier discussions. For sure, what does your geotech engineer say?

 

[ANgK]

There is no close building on the neighbor lot. the neighbor house is 40 ft away. Soil is silty sand with gravel.

 

[oldestguy]

Apparently you are digging a hole, right. Why? No water there I suppose? No geotech? or other posts, so I assume it is desert country and you want to build so
meothing in a hill side, but on leveled land. The wall will hold back the neighbor's land. I'd draw up schematic plans showing a wall with proper reinforcing to hold back that wall of earth but by two or three different options. Then I'd advertise for contractors to bid the three different types and have them use a registered engineer to design it and that they are then responsible for it being properly designed and built. That will get you the prices and you can choose which to use. Doing it yourself and yuo might miss an important item.

 

[dik]

Can you access your neighbour's land during construction? You may be limited to sheet piling. vibration damage, etc.

Dik

 

[oldestguy]

I'd add some warnings. Any wall that is built poses some risk for the property up hill. Thus, any design info you provide, such as test borings, surveying, etc. places some liability on you. All of this should be placed on the contractor if at all possible. No restrictions, such as appearance, material type, fencing on top also tie you to responsibility for the job. All I'd want is a buildable site with reasonable slopes down hill from the wall. A sloping site uphill from the wall adds significant load as compared to a level area up there. Be aware that legal aspects here may even be so severe as to negate doing the job. If my land was up hill you can bet I'd really have a fool proof agreement and be compensated accordingly.

 

[dik]

...and do a preconstruction condition report.

Dik

 

[BridgeSmith]

I assume you are excavating in front of the wall to drop the grade, correct?

If that is the case, a sheet pile wall may be an option if can be driven to sufficient depth. A soldier pile wall is an option, as well. Preboring and grouting the soldier piles may be necessary if the piles cannot be driven to adequate depth. A tangent or secant drilled shaft wall may be an option. The drilled shafts are drilled in a row where they almost touch (in sequence at different times, then the soil is excavated in front of the wall and facing is added.