×
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

3-inch force main

3-inch force main

3-inch force main

(OP)
Need to use a 3-inch force main, almost 3 miles long.  SDR 21 comes in 3-inch but obviously not common.  SCH 80 is readily available in 3-inch but not sure if the belled end SCH80 is readily available.  

I have two questions:
1) Do you concur with the SDR21?

2) What type of fittings would be used?

Thanks in advance, I'm not overly familiar with the small diameter stuff.
JT

RE: 3-inch force main

Use HDPE

RE: 3-inch force main

I'd look at directional drilling the line in, using HDPE pipe.  

Richard A. Cornelius, P.E.
WWW.amlinereast.com

RE: 3-inch force main

3-inch sdr 21 is fine and is common.  Use ductile iron fittings.  The only problem with HDPE is that some of the utilies do not have the equipment to work on the pipe.

RE: 3-inch force main

This may be a stupid question, but if 3" size pipe is "fine" for such a long forcemain, why do the Ten States Standards for Wastewater accessible e.g. at http://10statesstandards.com/wastewaterstandards.html#49, along with a great many other local and regulatory agency specifications in many other areas, say, "The minimum force main diameter for raw wastewater shall not be less than 4 inches (100 mm)"?
 

RE: 3-inch force main

rconner,
That statement in Ten States is based on a standard pump with a throughlet of 3" minimum.  If a grinder pump is used, sizes less than 4" are acceptable.  Ten States is geared more toward larger public mains, not small projects with low sewage generation.  
If the pump is not a grinder pump, I would agree with you that a 4" force main is required, unless the regulatory body in that state doesn't invoke Ten States (I think there are only a couple, if any, that don't).

RE: 3-inch force main

(OP)
I concur with jgailla, the Ten States rule of a 4" minimum doesn't consider a provision for grinding.  In my area, if grinding is not used, a 4" force main is the smallest allowed and the pump must be capable of passing a three inch solid.

RE: 3-inch force main

The SDR 21 is probably your cheapest.

Being a forcemain, I wouldn't worry too much about having to work on it.  You can call out for the HDPE to be DIPS or IPS in size and therefore can get ductile iron fittings to work on it.  The cost of the pipe will be a lot higher however, and depending on your route, the installation cost could be higher.

RE: 3-inch force main

I didn't happen to see in the original inquiry that this was a grinder pump only design, and while I agree Ten States does require pumps that will pass 3" solids I don't otherwise read the specific gearing nor allowances you refer to in the Ten States Standards document. Nevertheless, I understand the arguments you are making, and I guess as long as the regulators and funders etc. involved are happy that the grinder pumps and very small pipes you recommend are the way to go, I guess you are OK (unless there are problems with the grinder pumps or stoppages/other problems with the very small pipes, or you evntually require increased future capacity -- see also http://books.google.com/books?id=LV_Zxe6R0XsC&pg=PT385&lpg=PT385&dq=minimum+force+main+size&;source=bl&ots=PLORv5uSfk&sig=65lP3XjwfXJDTcuEu7l2NGChN3g&hl=en&ei=cqjTSZKKOojCtwfA3qCfBw&sa=X&oi=book_result&resnum=2&;ct=result#PPT385,M1 ).  

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