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  • Sewage pump - kickback

    We have a sewage pit at work (maybe 500+ gallons) and it has 2 zoeller pumps in it. Both are piped up to above the pit to 3" to a single 4" wye. From the 4" end it goes up maybe 8' and then a few turns till about 40-50' till it exits the building into a 6" pipe. This was just recently changed to this set up, previously it ran maybe 150-200' in the building before joining with our existing sewer pipe. Anyways, since we had this changed over the pipe has a huge amount of kickback after the pump turns off. The pumps turn on, suck everything out and then turn off, a second later there's a loud bang, the pipes rattle and shake. The first week we had this set up the wye broke and we had to have it repaired from this shaking. The plumber added extra bracing on the top, and tightened all previous connections. We added a board on the top of the vertical stack to try and cut it down but it's still loud and shaking violently. Is there anything else that we can do to this set up to cut down on the amount of shaking that's occurring? We need to fix it soon, otherwise something else is gonna crack. I should also mention that the way it was set up before, there wasn't as much shaking, but all the wye's that entered into the old pipe before it was cut off are all cracked because of the force.

  • #2
    Re: Sewage pump - kickback

    The bang is the weight of the water in the vertical discharge line falling back and hitting the check valves when the pump shuts off. There will always be some noise and some shock pressure associated with this. The key is to keep the noise to acceptable levels and keep the pressure within design limits of the system.

    If the piping is cracking, its probably dwv (drain, waste, and vent) piping, which is not rated for pressure. It probably has the words 'not for pressure' printed right on it. This is common practice despite the fact that it is wrong. Gravity drain piping never sees any pressure, and people fail to realize that when the put a pump behind a pipe they are pressurizing it, or at least fail to think about it. Usually it works ok because there is not enough head or shock to overpressure it. In your installation there clearly is.

    You can address it by replacing it with pressure rated pipe and tying it down properly to stop the rattling, or by eliminating/reducing the shock when the pump cuts off, or both. A proper installation would use pressure rated pipe, but I see dwv in this application all the time.

    Changing it from 3" and 4" to 2" will reduce the amount (and therefore the weight) of the water falling back and reduce the shock. You need to make sure the pumps will work with 2"; if they are grinders, it'll be ok. If they are solids passers, it probably will not (at least in the long run). Also this will add to restriction to the system, and therefore add pressure, and will reduce the flow rate of the pumps. Depending how they are sized, that could be a problem.

    You could possibly install a check valve further downstream in the discharge at a higher elevation where the shock will not be so severe. If you do this, you should have weep holes in the discharge to keep the pumps from air locking. The weep holes will spray water when the pump is running so they need to be in the pit. The weep holes will use some of the flow capacity of the pumps so, again, their sizing becomes important. You need to keep the existing checks as well; each pump needs a check or they'll just pump out the bottom of each other instead of pumping it out the discharge.

    These are some ideas; I can't say what will work and what won't without seeing the installation.

    Seems to me you paid someone to install a new system and they messed up it's design. Doesn't seem like you should have to fix it. I'd tell them to come make it right or else give you their liability ins carrier's name and number, because when it blows apart there is going to be a mess.

    If they are fly by night, unwilling to help, unable to help, or whatever, then get someone who knows what they are doing involved, get it put right, send the original people a bill, and call your lawyer for when they won't pay. Give them an opportunity to fix it, document it, and take a lot of photos before changing anything.
    This is my reminder to myself that no good will ever come from discussing politics or religion with anyone, ever.

    Comment


    • #3
      Re: Sewage pump - kickback

      Originally posted by Ace Sewer View Post

      If the piping is cracking, its probably dwv (drain, waste, and vent) piping, which is not rated for pressure. It probably has the words 'not for pressure' printed right on it. This is common practice despite the fact that it is wrong. Gravity drain piping never sees any pressure, and people fail to realize that when the put a pump behind a pipe they are pressurizing it, or at least fail to think about it. Usually it works ok because there is not enough head or shock to overpressure it. In your installation there clearly is.
      You couldn't be more wrong with this paragraph.

      Schedule 40 PVC DWV is allowed for pressurized applications. Here is the Link to charlotte pipe for this section...http://www.charlottepipe.com/Default...type=ABSPVCDWV

      Schedule 40 for pressurized situations only is here...http://www.charlottepipe.com/Default...8&type=PVCCPVC It also states it's for pressurized LIQUIDS ONLY! Solids are going through an ejector pump.

      Foam core (DWV) is NOT intended for any type of pressure applications..http://www.charlottepipe.com/Default...type=ABSPVCDWV

      Piping out an ejector pump is totally different than piping out main water lines.

      Schedule 40 DWV pipe is absolutely acceptable in an ejector pump situation.

      Comment


      • #4
        Re: Sewage pump - kickback

        I think he was referring to foam core, that's what I gathered from the "not for pressure" label he mentioned


        Originally posted by Flux View Post
        You couldn't be more wrong with this paragraph.

        Schedule 40 PVC DWV is allowed for pressurized applications. Here is the Link to charlotte pipe for this section...http://www.charlottepipe.com/Default...type=ABSPVCDWV

        Schedule 40 for pressurized situations only is here...http://www.charlottepipe.com/Default...8&type=PVCCPVC It also states it's for pressurized LIQUIDS ONLY! Solids are going through an ejector pump.

        Foam core (DWV) is NOT intended for any type of pressure applications..http://www.charlottepipe.com/Default...type=ABSPVCDWV

        Piping out an ejector pump is totally different than piping out main water lines.

        Schedule 40 DWV pipe is absolutely acceptable in an ejector pump situation.
        No, it's not rocket science, it's plumbing and unlike rocket science it requires a license.

        Comment


        • #5
          Re: Sewage pump - kickback

          Originally posted by Flux View Post
          You couldn't be more wrong with this paragraph.

          Schedule 40 PVC DWV is allowed for pressurized applications. Here is the Link to charlotte pipe for this section...http://www.charlottepipe.com/Default...type=ABSPVCDWV

          Schedule 40 for pressurized situations only is here...http://www.charlottepipe.com/Default...8&type=PVCCPVC It also states it's for pressurized LIQUIDS ONLY! Solids are going through an ejector pump.

          Foam core (DWV) is NOT intended for any type of pressure applications..http://www.charlottepipe.com/Default...type=ABSPVCDWV

          Piping out an ejector pump is totally different than piping out main water lines.

          Schedule 40 DWV pipe is absolutely acceptable in an ejector pump situation.
          how I under stand what he is saiying because both of you are right pvc can be used for presure but with the right fitgs. Clearly marked DWV OR PRESURE. Just my in this
          SMELLS LIKE $$$$$$ TO ME

          Comment


          • #6
            Re: Sewage pump - kickback

            this is a very common issue when it comes to high head high flow pumps.

            as alex/ ace has mentioned correctly i would go back to the installer and have them make it right.

            3'' minimum is required here for commercial installation

            is it correct that the total lift is the pit depth 3' plus the 8' lift? the 40-50' is all gravity?

            since the pit is 500 gallons, move the 2 check valve to the horizontal line just beyond the vertical lift.

            the bigger issue is the material they used. if it's breaking, there's a serious issue with the material of choice or the installation.

            we have to use a pressure rated material for the installation that's not gravity. gal pipe with screw threads or victaulic, copper dwv. as far as i know, abs plastic is not approved out here, although i see it quite often. pvc is not common dwv out here.

            please post a few photos of the install along with the specs of the pumps and vertical lift. it might be nothing more than moving the check valve to a better location. there's also suppose to be a shut off valve after each check valve.

            rick.
            phoebe it is

            Comment


            • #7
              Re: Sewage pump - kickback

              I wonder if they replaced the check valves, or used the old ones? They make silent check valves for sewer ejector pumps, 2" anyway, is the only size that I have used, & they work great, & totally eliminate the kick back.

              Comment


              • #8
                Re: Sewage pump - kickback

                Flux,

                Originally posted by Flux View Post
                You couldn't be more wrong with this paragraph.

                Schedule 40 PVC DWV is allowed for pressurized applications. Here is the Link to charlotte pipe for this section...http://www.charlottepipe.com/Default...type=ABSPVCDWV

                - I think this refers to the pipe only. I should have used the word 'fittings' instead of 'piping'; appropriate fittings must be used for pressure applications. Obviously sch 40 solid core pipe is going to be fine, but if you glue it together with dwv fittings and it works, you got lucky.

                Schedule 40 for pressurized situations only is here...http://www.charlottepipe.com/Default...8&type=PVCCPVC It also states it's for pressurized LIQUIDS ONLY! Solids are going through an ejector pump.

                - It doesn't care about solids if the pipe is big enough for them, unless we're talking about an abrasive slurry, which we're not. I suspect the concern here is gasses, not solids.

                Foam core (DWV) is NOT intended for any type of pressure applications..http://www.charlottepipe.com/Default...type=ABSPVCDWV

                - My point exactly

                Piping out an ejector pump is totally different than piping out main water lines.

                - I'm sure it is, though I wouldn't know as I don't do water lines. My point is that piping out an ejector pump discharge SHOULD be totally different than installing a gravity drain line, though it often, as installed, isn't.

                Schedule 40 DWV pipe is absolutely acceptable in an ejector pump situation.

                - But the standard fittings are not, and are commonly used, and typically work fine because it's a low head application and a lot of the shock gets cushioned when the ferncos at the checks bulge in that alarming and scary way when the pump shuts off. I don't have any links to specs to show this (I doubt pressure ratings for dwv fittings even exist as they are not intended for that application), but I know what blows up and what holds up.
                Last edited by Ace Sewer; 09-01-2010, 07:51 PM.
                This is my reminder to myself that no good will ever come from discussing politics or religion with anyone, ever.

                Comment


                • #9
                  Re: Sewage pump - kickback

                  Originally posted by Don the plumber View Post
                  I wonder if they replaced the check valves, or used the old ones? They make silent check valves for sewer ejector pumps, 2" anyway, is the only size that I have used, & they work great, & totally eliminate the kick back.
                  Who makes them?
                  How do they work?
                  I probably want some.
                  This is my reminder to myself that no good will ever come from discussing politics or religion with anyone, ever.

                  Comment


                  • #10
                    Re: Sewage pump - kickback

                    Originally posted by Ace Sewer View Post
                    Who makes them?
                    How do they work?
                    I probably want some.
                    Its a spring check valve. not sure who makes them but my supply has them in stock.

                    Ron Hasil Lic #058-160417
                    A-Archer Sewer & Plumbing specializing in:
                    Tankless Water Heaters | Drain and Sewer Cleaning
                    Sump and Ejector Pumps | Backflow RPZ Testing

                    Comment


                    • #11
                      Re: Sewage pump - kickback

                      ABS is more brittle than schedule 40 DWV. ABS is a long the lines of Foam core as far as "brittle" goes.

                      Connecticut follows the I.P.C. (2003 version I think)

                      To say DWV is NOT ALLOWED in sewer ejection applications..is simply not true, and completely false, unless your state adopted something saying otherwise.

                      Someone said DWV is NOT RATED for pressure..and that's simply not correct, and I provided links from the manufacture to say otherwise.

                      Whatever "cracked" wasn't due to the type of material as the moving and shaking of the line is what's at fault. The placement of the check valve caused this, as well as not enough proper bracing/hangers. People need to re-read the original post again.

                      3" pipe using an 8' lift with the placement of the check valve at the bottom and the lack of proper hangers and bracing caused the pipe to break. Pressure had nothing to do with as much as FORCE and the lack of bracing did.

                      The Plumber should come back to move the check valve and use proper bracing....not re-do the piping cause someone doesn't like the material being used even though it goes against what the manufacture says is correct.

                      Comment


                      • #12
                        Re: Sewage pump - kickback

                        There are 3 or 4 manufacturers of silent checks,try Little Giant,Pasco or Campbell.I think they are only available up to 2",they claim that fouling isn't really a problem because the spring mechanism is not directly in the flow.
                        Steve in the trade since 73 doing new residential/Commercial work

                        Comment


                        • #13
                          Re: Sewage pump - kickback

                          Originally posted by Flux View Post
                          ABS is more brittle than schedule 40 DWV. ABS is a long the lines of Foam core as far as "brittle" goes.

                          Connecticut follows the I.P.C. (2003 version I think)

                          To say DWV is NOT ALLOWED in sewer ejection applications..is simply not true, and completely false, unless your state adopted something saying otherwise.

                          Someone said DWV is NOT RATED for pressure..and that's simply not correct, and I provided links from the manufacture to say otherwise.

                          Whatever "cracked" wasn't due to the type of material as the moving and shaking of the line is what's at fault. The placement of the check valve caused this, as well as not enough proper bracing/hangers. People need to re-read the original post again.

                          3" pipe using an 8' lift with the placement of the check valve at the bottom and the lack of proper hangers and bracing caused the pipe to break. Pressure had nothing to do with as much as FORCE and the lack of bracing did.

                          The Plumber should come back to move the check valve and use proper bracing....not re-do the piping cause someone doesn't like the material being used even though it goes against what the manufacture says is correct.
                          We have some forced sewer mains here. The building sewer holds pressure 24/7. I wouldn't advise using foamcore in that sewage ejector application.


                          ADD> I didn't quote an earlier post...I quoted the one i quoted. hey you can quote me on that.
                          Last edited by TheMaster; 09-01-2010, 09:50 PM.

                          Comment


                          • #14
                            Re: Sewage pump - kickback

                            Originally posted by TheMaster View Post
                            We have some forced sewer mains here. The building sewer holds pressure 24/7. I wouldn't advise using foamcore in that sewage ejector application.
                            Never said foamcore was an acceptable material to use, and stated that in an early post.

                            We don't know if foamcore was used or schedule 40 PVC DWV in this situation. By the responses I'm seeing..some people must not realize there is a difference between foamcore DWV and schedule 40 PVC DWV.

                            A building sewer might be under constant pressure..but not the type of pressure a water main would give, and people are losing sight of that.
                            Last edited by Flux; 09-01-2010, 09:53 PM.

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                            • #15
                              Re: Sewage pump - kickback

                              I'll take some pics of the setup tomorrow along with the pump information. Thanks for your help so far!

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