×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Concrete sewer pipe penetrations
3

Concrete sewer pipe penetrations

Concrete sewer pipe penetrations

(OP)
We are planning to add two new 12" SCH 40, CS laterals to an existing 24" RCP. Is there a limitation on the hole size that can be bored in a 24" pipe?
The laterals are dischrge lines from two new oily water separators. We don't have adquate spacing for a box and manhole at the tie-in points because of other underground lines in the area.
We plan to bore the 13.75" holes at 45 degrees and grout them in. Then build a form and pour concrete around the laterals for strength.
Any other suggestions? Thanks.

RE: Concrete sewer pipe penetrations

The short story, without knowing everything about your project, I would say you should not do the connections that way.  Your connections should connect to a new manhole(s) constructed on the 24-inch main and if you don't have the room, you should consider realignment of the main.  Coring and grouting the connections is only asking for trouble.  If we knew more, maybe a saddle could be used.  Try searching for a firm called GENCO.

let us know how you make out...

BobPE

RE: Concrete sewer pipe penetrations

If you can expose the pipe, install the coring machine at an angle and then install the pipe, you have room for the manhole. If it is in and on your pipe, you can get by with a 36 inch manhole.

RE: Concrete sewer pipe penetrations

We have done this on ocassion. It is not the prefered approach. The biggest problem is clearing a clog where the two pipes join.
Generally you would expose the pipe at the pentration and mark and line drill the penetration, making it somewat larger than the new pipe. Set the new pipe in, leaving space all around the between the old pipe and new pipe.
Chink and mortar the joint (not grout, as grouting will blow though into the old pipe). Once the mortar has set, dig below the old pipe, from the sides and top and pour a 4-6" thick collar around the joint. One important point, make sure upstream of both pipes is plugged before starting.
Again unless it is temporary such as to cut in a line,however, if you can avoid it, I would go with the manhole. It is not that significant a cost savings up front and if you have a problem, it could be very expensive.

RE: Concrete sewer pipe penetrations

(OP)
Thanks for your helpful responses.  You convinced me to install a new box.  I appreciate your help.
BH

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources