We want to provide septic tank outlets at a church children's camp for RV's that park on site. We have laid out a trench that will allow 7 outlets at 25 foot intervals, connecting to an existing inlet pipe to the tank. We will be working with 4 inch pipes.
?? What type of pipe should be used underground (from 12 inches to about 4 feet) to do this project? Thanks, the olddude

You can use ABS or PVC pipe to do your project. Install Clean Out at each branch as well as at the end of the run.

As far as the Sewer Pipe Load goes, you should be fine with 4" pipe for 7 RV connections.

If you going to be driving heavy RVs over the shallow end than I recommend that you start with 4" Cast Iron pipe. Once you get couple of feet deep, continue with ABS / PVC.

Hope that helps... Good luck with your project... Milo

Thanks for the prompt reply. I forgot to ask if we should use the normal cement or a flexible rubber connector on the long pipes. We live in the northern part of the country and have a pretty deep frost in the winter.
Thanks again, the olddude

There is dedicated glue for each type of plastic pipe. ABS pipe takes ABS glue. PVC pipe has its own glue... etc.

Just to make sure: ABS glue will not glue PVC pipe... and vice versa

You should check with manufacturer if it is OK to use the type of glue you want to use in your area. I assume it is - but still, I recommend you call their customer service number.

You don't have to use Flexible Connector. They are mostly used for remodeling and in hard-to-get-to places. As far as Shielded Couplings go, they are used with No-Hub Cast Iron pipe.

Milo