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Discussion Starter · #1 ·
This job is a partial new retaining wall tieing into an older block wall. The new wall will be reinforced concrete this is not really the issue. The existing block wall is not that old, probably less than 5yrs, 8"x8"x16" block, and is in pretty good condition. The wall hieght is 4 to 5ft. The block wall is currently hollow and we were planning on grouting the cells and adding rebar. The problem that just came up is that when we peeked underneath the cap on top of the wall we found it is filled with broken bricks and soil:eek: We drilled some prob holes a the base of the wall too and found the same thing. I have some ideas, but does anyone have a proven meathod for cleaning out the cells?
 

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How long it the old wall and how long is the new wall?

You may be better off getting rid of the old wall and building everything new and properly with a segmental retaining wall system. Like Allan Block, Anchor Wall Systems, Keystone and Versalok who are the major licensors that have great websites and design/construction details.

These systems eliminate the need of footings below frost. They cannot be built on concrete footings (all designs and guarantees are voided if a footing is involved). Depending on your local codes and standards the 4' is not a problem and standard designs and details can be used without engineering.

These walls can be built as high as 40' without footings using engineered designs. Most local municipalities have standard design plates for low walls that are routinely used by county and municipal for grade changes and slopes as a result of road widening and new sidewalks.

If you try to build a new wall connected to the old sloppy construction, you could be required to rebuild the entire wall complete with the footings and depths that are required (big - $$$$s). A rigid. reinforced retaining wall on a proper footing is very costly.
 

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Discussion Starter · #4 ·
I wish the wall could be ripped out and a proprietary wall installed, but I don't have final say. My job is to engineer the solution to the situation we have. The wall will finally get a red brick facade to match an existing building and some other nearby walls. The section of block wall is 1/3 the total length and is the only part of the wall right on the property line. The neighbor has some fairly new hardscaping directly behind the wall that is not to be distrubed. The existing section of wall actually has a reasonably deep footing that looks like it was part of some older construction.
 

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Once you engineer a solution, you own the old crappy wall. Sometimes the only choice is to say, "What you want to do is not possible, here is how it will have to be done". You are the engineer of record.
 

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Discussion Starter · #6 ·
I'm fully aware of my responsibilities as the engineer. Remediation work is of coarse more risky than new work, but the price tag reflects the risk. This wall is going to be encapsulated in grouted soil by drilling through, in front of, and beneath the wall. This will make the wall into a gravity wall as opposed to a ridged wall, bring it below frost, and take the load off of the old block. I want to clean out the cells and grout them to prevent freeze/thaw inside the wall. I'm putting in the rebar just to make me feel better, because there isn't really any tension in a gravity wall.
 

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If the old wall is basically sound and cannot be ripped out, go with a steel plate on the back side. Instead of cleaning the old debris out, drill 3 holes through wall, insert rod, on the back side weld a flat plate, this will give you a solid union between the walls. G
 
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