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Thread: DIY Sewer Mainline Replacement Plan

  1. #16
    Master Plumber Dunbar Plumbing's Avatar
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    I'm very fond of SCH40 applications but ground movement can easily shatter glued connections underground. I've always felt that 20' sections of SCH40 with minimal deflection and the use of 4-band mission no-hub couplings underground are the best way to go.


    Any pipe you can put in your hand and distort the inside diameter of is going to be a problem with the movement of weight created by good ole mother earth.


    Just dig a hole in a ground and fill up a drywall bucket and tell me how heavy that bucket is, when full.
    Read what the end of this sentence means.

  2. #17
    Mechanical Engineer loafer's Avatar
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    SDR 35 pipe will not crush at 4ft, did you mean to say 40ft?

    Even that would not always be right. For most soil compaction densities SDR 35 can be buried 40 – 50ft and still be below the 7.5% vertical deflection threshold allowed per ASTM D3034.

    For the homeowner’s purpose, the 7’ depth with no traffic/road load will not be a problem.



    Quote Originally Posted by hj View Post
    A mini hoe will not have a bucket wide enought to dig the ditch you need for a 6' to 8' deep sewer. Between that, and the shoring, I assume you will be spending most of that $8,000.00 anyway, assuming that is really what it would cost. I would NEVER use SCR pipe at that depth. It crushes at 4' and has to be replaced.

  3. #18
    Illinois Licensed Plumber SewerRatz's Avatar
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    Quote Originally Posted by loafer View Post
    SDR 35 pipe will not crush at 4ft, did you mean to say 40ft?

    Even that would not always be right. For most soil compaction densities SDR 35 can be buried 40 – 50ft and still be below the 7.5% vertical deflection threshold allowed per ASTM D3034.

    For the homeowner’s purpose, the 7’ depth with no traffic/road load will not be a problem.
    SDR 35, its junk, on paper it should do what it is designed for, but in real life applications I seen it go oval at 10 feet deep. Also seen SDR 35 clean out risers get tore up by cable machines. Most villages around here want SDR 26, due to the above concerns I just posted.

    Personally I would never ever install SDR 35, even if it cost me the job in pricing difference.

  4. #19
    Moderator & Master Plumber hj's Avatar
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    No. I have changed many SDR sewers 4' deep because they had become oval due to ground pressure. ANd the deep they go the worse they get. I do not know where all those "fractured" joints are coming from because we have been using sch. 40 pipes for the past 50 years, or more, and I can not think of a single sewer that has been dug up and repaired because of a "fractured" joint.

  5. #20
    I&C Engineer (mostly WWTP) Lakee911's Avatar
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    I cut my clay pipe with a recipricating saw and a long diamond blade. If the clay is fractured, I would think the chain snapper would just crush the pipe. I'm not sure I'd trust it on good pipe though either. You know, sometimes the old joints just come apart easily, and if that's the case you should be left with the bell end of the pipe that you may be able to join to.

    I've only made spot repairs, but I'll tell you it's tough working down in the hole/trench. In a hole it's like bending at the waste and threading shoelaces in your shoes in the dark while wearing them. You definately want to make certain that the walls are shored up well or cut back enough that it won't collapse. You'll probably want at least 2' down there and that will be tight. What kind of soil do you have?

    I think you said 37 feet....that's not too bad. I think mine is 80 feet and I got a rought estimate of like $12K once upon a time.

    As far as being without sewer service, that kind of sucks. When I did my last repair I just left the hole open and I took a shower (couple actually) ... water came in one side and flowed out the other side. It was already wet down there and the clay soil other than being slippery didn't go anywhere. I did check the pipe with a light and a mirror to make sure it wasn't obstructed by dirt before I closed it up.

    You're going to need a transit or at least a good laser level too for checking your elevations. It helps to have someone checking this while you're digging. You don't want to over excavate it for risk of settlement which could cause bellies where it's been filled.

    I don't know about the official backfilling procedure when done, but I've used water to help it settle. Fill some, water it down, walk on it, fill some more, add water, etc. I still always end up with more dirt left over than when I started and I still have no appreciable settling at the surface.

    Make sure you get someone to locate the actual pipe for you. The last thing you want is to dig up your yard all over because you can't find the dang pipe!

    Good luck.

  6. #21
    Illinois Licensed Plumber SewerRatz's Avatar
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    I been doing sewer repairs for well over 20 years, my father well over 50 years, and we always used snap chain cutters to cut the clay sewer tile as well as cast iron. Age of the pipe has nothing to do with how well the cutters work, its how well maintained the cutters are. Also putting plastic pipe into a bell of a clay pipe will not work well. Its best to snap the bell off and use a non-shear coupling as I posted in a previous post.

    Man I need to raise my prices, I have done whole sewer line replacements for under 10k on a 100' sewer. Only time I would charge more is if there is special circumstances, like going under a driveway or digging in the village right of way and defiantly more if I have to open a street. But if its all in the soil on the home owners property I would charge anywhere from 4k to 8 k depending on the length of the sewer.

    As to needing a transit or a laser level, that is over kill, just a good old torpedo level will work fine. just make sure you are breaking the bubble in the right direction. Another simple way to ensure you have the right pitch is to run a string line with a string level along the length of the trench and just measure every 8 feet that you dropped the pipe 1" or more from the level string. The 1" per 8 feet will get you the minimum required 1/8" per foot pitch. As to digging to the proper depth just dig till you hit the top of the existing sewer line. If you over dig its not a big issue, code around here wants a minimum of 6" of compacted stone under the pipe So if you dig a little deeper than needed you will just need more stone. Be sure it is well compacted be fore putting the pipe in the trench. Then there should be stone packed on the sides of the pipe, and 6" above the pipe. Then you can backfill your hole with out fear of the backfill material causing your pipe to deflect or getting damaged.

    If this is an open area not under a driveway you can just allow natural compaction which will be adequate. Just fill it in and pile all the spoils on top of the trench. It should look like a grave mound. To help speed settling of the soils you can water it down as you backfill and or even after its done being filled. If it is under a driveway or sidewalk, then you would want to dispose of the spoils you dug out and back fill with stone all the way to the top. The proper way to backfill with stone is to put in no more than 12" of stone at a time, then use a tamper to pack it down.



    Quote Originally Posted by Lakee911 View Post
    I cut my clay pipe with a recipricating saw and a long diamond blade. If the clay is fractured, I would think the chain snapper would just crush the pipe. I'm not sure I'd trust it on good pipe though either. You know, sometimes the old joints just come apart easily, and if that's the case you should be left with the bell end of the pipe that you may be able to join to.

    I've only made spot repairs, but I'll tell you it's tough working down in the hole/trench. In a hole it's like bending at the waste and threading shoelaces in your shoes in the dark while wearing them. You definately want to make certain that the walls are shored up well or cut back enough that it won't collapse. You'll probably want at least 2' down there and that will be tight. What kind of soil do you have?

    I think you said 37 feet....that's not too bad. I think mine is 80 feet and I got a rought estimate of like $12K once upon a time.

    As far as being without sewer service, that kind of sucks. When I did my last repair I just left the hole open and I took a shower (couple actually) ... water came in one side and flowed out the other side. It was already wet down there and the clay soil other than being slippery didn't go anywhere. I did check the pipe with a light and a mirror to make sure it wasn't obstructed by dirt before I closed it up.

    You're going to need a transit or at least a good laser level too for checking your elevations. It helps to have someone checking this while you're digging. You don't want to over excavate it for risk of settlement which could cause bellies where it's been filled.

    I don't know about the official backfilling procedure when done, but I've used water to help it settle. Fill some, water it down, walk on it, fill some more, add water, etc. I still always end up with more dirt left over than when I started and I still have no appreciable settling at the surface.

    Make sure you get someone to locate the actual pipe for you. The last thing you want is to dig up your yard all over because you can't find the dang pipe!

    Good luck.

  7. #22
    I&C Engineer (mostly WWTP) Lakee911's Avatar
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    Hey now, I never said anything about putting plastic into the bell of a clay pipe. I only said that perhaps he can join to it. You'll still need to use an appropriate coupling.

    And again, I never said anything about the age of the clay pipe. I simply said that I wouldn't trust them. I have had plenty of luck using a recipricating saw. In fact, if I had neather I'd want to buy the saw over the snap cutter because it's more of a multi-tasker. Anyhow, I still doubt that fractured pipe would snap off cleanly.

    Personally, I wouldn't trust using a spirit level on 37-some feet of pipe. For the ease of setting up a $40 laser level, I'd rather just measure down periodically knowing I have a good reference point. I think it would be much more reliable because he has fixed inverts for input and output. If he doesn't get them right he may to need to go back and adjust all of the pipe lengths.

    Your method of backfill will work, if you like that "grave" yard look.

    In hindsight, my 12K had to do with digging up my sidewalk on the side of the house, front walk, and front sidewalk and working in very tight areas w/ no room for the spoils. It would be a very high price and isn't indicitive of a true cost....but then again, what is?

    Jason

  8. #23
    DIY Member sctclimbs's Avatar
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    Nothing like a good controversy with choice of pipe.

    I'm having a little trouble even finding the sdr-26. I'll see if I can talk the inspector into allowing me to use sch. 40 with the 4-band mission no-hub couplings as suggested above. I like that idea. Doubt he will go for it though and then I might be stuck using the sdr-35 unless I can find someone who will sell me the 26.

    I think I can get a backhoe with a 3 ft. bucket, that should make life easier. Again I plan to shore it up real tight!!!!!

    Planned on 6 inches of pea gravel underneath. Will also do that around the pipe and for the initial backfill as suggested above.

    Plan on using my laser level to get the pitch right. Will add/subtract gravel to adjust as needed. Talking to the contractor that did my neighbor's line last week, he said they dont feel like they have to compact the soil beneath the stone. Still i was planning on doing this as best I can, tamping it with the backhoe bucket prior to laying the gravel in there. Sound OK?

    I'll rent the snap cutter as well, hopefully no pipe shattering.

    If all goes well hopefully can have her up and running in a day but knowing how most things go with me, it will likely take 2 or even 3. Sending the wife and kid away for the weekend though and I can use the neighbors pot when nature calls.

    Muchas gracias for all the tips.
    Last edited by sctclimbs; 08-26-2009 at 12:51 AM.

  9. #24
    I&C Engineer (mostly WWTP) Lakee911's Avatar
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    Post some pics ... let us know how it goes.

    Jason

  10. #25
    Mechanical Engineer loafer's Avatar
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    SDR is commonly used for small sewer and storm water drains here in Maine. It is also commonly used for many larger storm water drains w/o problem. The crushed pipes you replaced must have been the result of improper installation, such as running large compactors or excavators over it with very little backfill on top. 4’ of soil weight alone is no where near enough to crush that pipe. If this were the case, you would be able to completely crush the pipe just by standing on it.

    Quote Originally Posted by hj View Post
    No. I have changed many SDR sewers 4' deep because they had become oval due to ground pressure. ANd the deep they go the worse they get. I do not know where all those "fractured" joints are coming from because we have been using sch. 40 pipes for the past 50 years, or more, and I can not think of a single sewer that has been dug up and repaired because of a "fractured" joint.

  11. #26
    Geologist sjsmithjr's Avatar
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    Just an observation - using water to assist with compaction works great if you live in a big sand box; not so good if you have clay soil.
    -Sam Smith
    Licensed Professional Geologist - AL, TN, KY

  12. #27
    Geologist sjsmithjr's Avatar
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    Missed a couple things...

    With respect to the observations that in the "real world" SDR26 and 35 fail at less than their rated burial depths I can believe that. When installing the pipe, your backfill would need to achieve 95% proctor density to meet spec and to achieve that you need good soil, optimal moisture at the time you place the material, proper "lifts", and compaction equipment. Not just for the bedding material either - sides and top as well. If you overdig consider using No. 57 stone for fill as it takes minimal effort to fully compact.

    Also, a cautionary note when using laser levels. Be careful to hold the rod plumb when taking measurements. If you hold the rod off plumb when using a laser level the error can be greater than the drop required. For short runs I too use a spirit level; less chance for error.

    Finally, although I understand that you will be using hydraulic shoring, be sure to stage your spoils well away from the excavation and do not stage or "park" the excavator, vehicles, or materials near the excavation. Make sure you use a ladder for entering and exiting the excavation.

    Good luck!
    -Sam Smith
    Licensed Professional Geologist - AL, TN, KY

  13. #28
    DIY Member sctclimbs's Avatar
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    Default Insurance Bond

    Even though I will only be working on my own property and not going into the right of way, my water district is requiring a 25,000 bond. Seems a bit odd to me, is that typical?

  14. #29
    DIY Member sctclimbs's Avatar
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    Default All done and passed inspection!!!

    Well I went and did it.

    Rented a backhoe and dug my trench. Took this rookie about 4 hrs. to dig the trench which was just short of 40 ft. long, 2 ft wide and 7-8 ft. deep. No utilities in the way thankfully, I called in advance. Rented Safe-t-Shore hydraulic shores from the same outfit that I got the backhoe. They were nice enough to give me a nice tutorial on how to use the machine and shores. Some good videos on Youtube for shoring were helpful as well. They also provided the tabulated data on proper placement and spacing for the given the soil type. Friend of mine is a soils engineer so that was helpful.

    I was pretty slow and cautious on the machine at first but got the hang of it somewhat after a while. Had a bunch of old paneling that I spread on the yard to place the mound of dirt to protect the grass. Made sure the mound was at least 3 ft from trench for safety.

    Got a bit lucky in that I snapped the clay pipe right at the sidewalk with the backhoe bucket, didnt mean to and that could have been a disaster if it had affected the pipe under the street. Not a clean cut but i cleaned it up with my grinder. Had to hand dig to expose each end of the pipe. That was work, ground was bullet proof. At the cast iron pipe coming from the house I just hit the clay pipe with a hammer and chisel to free it from the cast iron. Fernco fittings on each end with stainless steel bands to attach the new pipe to. Couldnt find sdr-26 anywhere so had to go with the sdr-35, gasketed joints. They wouldnt let me use sch. 40. Outdoor cleanouts installed. Pipe was bedded in 6 inches of squeegee. The run from the house to the sidewalk was about an inch drop per ft. Backfill was another 6 in. of squeegee first. Then lifts of about 2 ft. of dirt. Compacted the dirt with a jumping jack. Left the graveyard mound on top for future settling, it is almost halloween anyway.

    All in all it took me 2 1/2 days. Was out of sewer serve for most of that but the neighbors and a couple bushes sufficed. Lots of hand shoveling and moving the shoring around which was quite exhausting. Snowed a bit on day 2 which made for a muddy mess around the dirt mound. Not nearly enough to effect the integrity of the trench though, stayed warm and dry down there.
    Final cost:
    backhoe for 2 days $400, jumping jack $120, 3 shores $120, pipe and fittings $160, 5 tons squeegee $120. Total 920 bones + beer for my helpful friends.

    Many thanks for the advice here, invaluable!

    Any others thinking of doing this, safety first! Know how to properly shore the trench and keep the dirt pile well away from the edge. Call before you dig!
    Get ready for a ton of work.
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    Last edited by sctclimbs; 10-28-2009 at 10:15 PM.

  15. #30
    I&C Engineer (mostly WWTP) Lakee911's Avatar
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    Thanks for the update. I'm glad that everything went well for you.

    Jason

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