# Slope of excavation trench



## theconsult (May 8, 2011)

My question is why sometimes people (because I don't know if people usually do that) make a trench with a slopes, the wide slopes to lay the pipe? What happen if we try to use vertical wall or narrow trench?

I think that it would take more time to dig a trench then make the slopes on either sides or is there something that I cannot see?


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## Builderbob 72 (Dec 15, 2010)

OSHA requirement. It reduces the chance for collapse and cave in. I'd have to check my manuals, for the ratio.


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## theconsult (May 8, 2011)

But when people do the same with electrical duct bank, I see the trench is there without slope. Of I have been in two different projects with different requirements?


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## Sar-Con (Jun 23, 2010)

Sloped excavations are required for safe working conditions. There is a different ratio for different soils (and moisture content). On a large project, the geotechnical consultant will provide advise on this matter. 

Generally, 1:1 ratio is pretty safe.

You may have seen duct banks installed without sloped excavation as the bottom of the trench was only 3' or 4' and the earth was firm. Usually, in decent earth, the requirement to slope or shore is for excavations deeper than 4'.

Around our neck of the woods we need a designated safety watch for any excavation deeper than 4'


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## theconsult (May 8, 2011)

Sorry, I got a mistake. Basically I understood the concept.


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## tgeb (Feb 9, 2006)

Here is a little safety course you can review.

http://www.cdc.gov/niosh/docs/2006-133D/flash/index.html


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## rino1494 (Jan 31, 2006)

Some contractors will slope the trenches back instead of using trench boxes. Personally, I would rather use a box. Less dirt to excavated, backfill and compact. The more you slope the trench, the more stress is applied to the pipe.


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