Trench Strengthening

[erikfinley]

Existing sanitary sewer main with approx. 12 feet of cover. Proposed project will increase cover to approximately 22 feet, which will exceed the pipes recommended maximum cover.

Any recommendations on ways to exceed typical maximum recommended cover on pipes?

 

[GabionGuy]

Suggest you look into a product called ParaLink. It is used to support embankments over voids. Linear Composites may be able to help

 

[dicksewerrat]

Use a different pipe in the deeper areas.Which pipe are you using?

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[jcook14]

What is the pipe's recommended max cover? This may influence options available.

Replacing the existing pipe with a pipe of greater strength is an option, but I assume this is costly to do and is not your preference.

You could use cement-stabilised sand to provide extra support or otherwise modify the embankment to not increase the loading on the pipe. Piles are also a potential solution.

 

[DMcGrath]

Any possibility of using a lighter weight backfill (lightweight concrete or even big foam blocks)? If you can reduce the unit weight by half, you could effectively double the cover depth.

 

[BigH]

I think that DMcGrath has hit the correct chord (a major as versus a minor or diminished!). The other possibility is to construct a cover slab across the trench at some depth down which will permit the above-lying soil from loading below. The geofoam blocks, though, appear to be appropriate (or the use of Elastizell - but this is expensive.

 

[civilperson]

Pipe strength is a function of the surrounding backfill, use 100 psi flowable fill for pipe encasement and maximum depth can be increased.