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Underground Utilities - Stand Off Distances?

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JoelTXCive

Civil/Environmental
Jul 24, 2016
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We are providing extensive aesthetic improvements to an existing bridge & roadway crossing.

The improvements include cantilever retaining walls ranging from 4ft tall to 20ft tall, along with 20ft tall planter boxes supported by drilled shafts.

We have received the utility layouts from the various utilities crossing through the intersection and it looks like spaghetti underground. There are multiple gas lines, water lines, sewer lines, fiber etc..

Many of the lines are 30+ years old and the survey data is poor. All of these utilities are in the client's right of way, so there are no defined easements.

I recommended that we needed a Level A SUE; and that our proposed improvement follow the following guidelines:
[ul]
[li]Minimum 5ft horizontal stand-off distance from any utility unless we have precise surveyed location of the utility in the horizontal and vertical planes.[/li]
[li]Minimum 5ft of fill between any shallow footing and utility. If this cannot be achieved, then we need to span our retaining wall footings over the utility with void forms etc..[/li]
[li]No drilled shafts directly above utilities, even if the utility is super deep.[/li]
[/ul]

My recommendations went over like a turd in a punch bowl with the landscape architects and the client.

Is there any guidance out there with recommended stand-off distances from utilities? Maybe an AASHTO document? Or, is it just engineering judgement?

 
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SUE??

Some sort of survey?

As said above, I don't think it's up to you. The utilities generally have rights and powers to prevent damage and I can't see any of them allowing any footings over them. Hence why I doubt you'll find anything other than ask the utility owner.

Even as built underground drawings are just a general guide until you either dig them up or have done a ground radar survey. Even then deep sewer lines might not show on those scans.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
 
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