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  • Maximum slope of building sewer?

    House on a hill, 400'+ from the street lateral. GC wants to horizontal drill sewer line. His question to me: If minimum slope is 2%, what is the maximum slope? Because of the slope of the hill, some of the grades between clean outs (100') could be as great or greater than 20%. My 2007 CPC does not address the issue. My experience is that it doesn't matter. But, I told him I'd ask for 2nd opinions.

  • #2
    Re: Maximum slope of building sewer?

    3" and smaller1/4" per ft
    4" and larger 1/8" per ft

    Keep it at no more than a 1/4" then step/drop to a vertical 45deg.offset if possible.We've had this discussion before.I've never seen a problem with the of thousands of feet of pipe I've put in with more than 1/4".

    Watch,here come the boys talkin' bout low flow toilets stranding solids.I can see their point in theory.Just haven't seen it in the field.

    In your case and everyone of mine where I came across this I bombed it to whatever it took keeping the pipe 2' or more under grade
    Last edited by drtyhands; 08-11-2008, 05:50 PM.

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    • #3
      Re: Maximum slope of building sewer?

      you neeed to keep the velocity of water within the pipe less than 6 ft/sec because it can erode the bottom of the pipe... I would just keep it as flat as you can and you should be fine... i dont think that you will strand too many solids just do the best you can. this would be under the jurisdiction of the engineering department and it is pretty much up to their discretion. what do the approved plans call for? as long as you match the approved plans you are covered. I would also recommend trenching it vs. trenchless it will be cheaper and since this is probably new construction there shouldnt be any sensitive features to restore such as landscaping. Make sure that the pipe is bedded real well and if it is greater than 20% i would recommend concrete collars to anchor the pipe. your trench is like a conduit and will carry water even after it is backfilled for quite sometim unit your soils settle to 95% compaction, until then the concrete collars will prevent the erosion of bedding under your pipe and ensure a full bearing pipe the whole way though out. I would also reccomend the use of SDR-35 or sch 40 in this application vs. HDPE or CI
      Last edited by wrench spinner; 08-11-2008, 06:49 PM.

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      • #4
        Re: Maximum slope of building sewer?

        You should be okay code wise but you do need to be careful that the 20% is not going to abandoned solids. At a 400' lateral you may consider seeing if you can install a manhole at 300' rather than extra cleanouts. That of course depends on why you are drilling in the first place.

        Mark
        "Somewhere a Village is Missing Twelve Idiots!" - Casey Anthony

        I never lost a cent on the jobs I didn't get!

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        • #5
          Re: Maximum slope of building sewer?

          there is no evidence to support liquids outrunning solids. it is an old wives tale. The codes are just minimums

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          • #6
            Re: Maximum slope of building sewer?

            I am curious as to the opinions of 4" VS 6" Pipe for this instance, considering run and slope. Any thoughts?
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            • #7
              Re: Maximum slope of building sewer?

              Originally posted by Masterplumb View Post
              there is no evidence to support liquids outrunning solids. it is an old wives tale. The codes are just minimums
              Perhaps but I have witness the wives tale at a lab set up with clear PVC waste lines. There is also a sponge on the end of a pool sweep brush to clear the wives tale out of the line.

              Mark
              "Somewhere a Village is Missing Twelve Idiots!" - Casey Anthony

              I never lost a cent on the jobs I didn't get!

              Comment


              • #8
                Re: Maximum slope of building sewer?

                Originally posted by ToUtahNow View Post
                You should be okay code wise but you do need to be careful that the 20% is not going to abandoned solids. At a 400' lateral you may consider seeing if you can install a manhole at 300' rather than extra cleanouts. That of course depends on why you are drilling in the first place.

                Mark
                I've just slapped cleanouts in every hundred.What's the advantage of a
                manhole.Somewhere for a rat to keep his nuts warm in winter?

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                • #9
                  Re: Maximum slope of building sewer?

                  http://www.ridgidforum.com/forum/sho...ighlight=slope
                  Buy cheap, buy twice.

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                  • #10
                    Re: Maximum slope of building sewer?

                    I do my step/drop`s with 22`s not 45`s
                    I`m kinda picky like that
                    http://www.all-clear-sewer.com/

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                    • #11
                      Re: Maximum slope of building sewer?

                      Isn't there something about using PVC that duration causing hydropressure/velocity issues at the end of that line?


                      Years ago I did work at a house that the hillside was so steep that there was a consideration involving what piping was used....or something to the effect that the air movement was pretty strong through the pipe from bottom to top, not involving what ran through it.


                      Any theory to that situation.......or just contractor talk out the ying yang?
                      Northern Kentucky Plumbers Twitter Feed | Plumbing Videos

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                      • #12
                        Re: Maximum slope of building sewer?

                        Originally posted by ToUtahNow View Post
                        Perhaps but I have witness the wives tale at a lab set up with clear PVC waste lines. There is also a sponge on the end of a pool sweep brush to clear the wives tale out of the line.

                        Mark
                        I don't doubt your test but where is the hardcore proof? I have never seen anything to support that theory. Until I see firm evideence I will stick with my thoughts

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                        • #13
                          Re: Maximum slope of building sewer?

                          Originally posted by drtyhands View Post
                          I've just slapped cleanouts in every hundred.What's the advantage of a
                          manhole.Somewhere for a rat to keep his nuts warm in winter?
                          LOL-Like I said it depends on why they are drilling instead of digging. If they are trying to preserve pristine landscape of hardscape a single manhole might be preferred over four cleanouts.

                          Mark
                          "Somewhere a Village is Missing Twelve Idiots!" - Casey Anthony

                          I never lost a cent on the jobs I didn't get!

                          Comment


                          • #14
                            Re: Maximum slope of building sewer?

                            agreed if he uses manholes he can drop the depth of the sewer up to 2' from invert in to invert out thereby flattening the slope if he wants to drop more he technically should use a drop manhole which is not that big of a deal just throw a 4" santee flowing down and a sweep on the bottom of the drop to a smooth poured invert

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                            • #15
                              Re: Maximum slope of building sewer?

                              Originally posted by Masterplumb View Post
                              I don't doubt your test but where is the hardcore proof? I have never seen anything to support that theory. Until I see firm evideence I will stick with my thoughts
                              This is the drain and waste from a second floor men's restroom located in a first floor Union Hall classroom. It is meant to teach the students how the water clings to the outside wall when vertical and the associated hydraulic jump at the bottom when it turns horizontal. The apprentices are responsible for keeping the line clean but they can't use anything which will scratch the pipe.

                              Mark
                              "Somewhere a Village is Missing Twelve Idiots!" - Casey Anthony

                              I never lost a cent on the jobs I didn't get!

                              Comment

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