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  • sewer tank

    I got a call to cut a trap door on the top of a sewer tank so a vac truck can get in and suck out the crap! I have never worked on a sewer tank before and thought about methane gas as soon as I was done on the phone, I phoned the guy back and asked if there was a chance of build up of methane gas, he didnt really know. So my thoughts are, if I get there and it has sewer in it, it should have methane gas, which could means I could go BANG!! Of course if its a new tank, then no problem. If I am not sure I'll get them to take the top of(if it can) and cut the hatch out out of harms way. So have any of you guys cut a hatch out of a sewer tank and if so what did you to make sure you where safe?? I could have the guy stand on the tank while I cut/weld, that helps when guys arent sure if there is a chance of blowing up, I have done it at gas plants before and it seems to work well anyways what do you guys think?
    DODGE 1 TON 6.7
    PIPEPRO 304
    TO MANY TOOLS
    JUST WELDING IN CIRCLES
    rig welders are like wheelbarrows hard to push around
    and easily upset
    go flames go

  • #2
    are you going to use a torch? i'd go with a chop saw and if you can a water hose with just a little spray to keep the sparks down. (if it had to be done)
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    • #3
      i forgot we use concrete sewer tanks down here. still use chop saw with diamond blade but if its steel a steel blade. hope that gives you some more ideas.
      TB 325
      TB 302
      dynasty 200sd
      spoolmatic 30a/wc24
      suitcase x-treme 12vs
      miller 211
      evolution rage 2

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      • #4
        Almost all the septic (sewer) tanks I have worked on are concrete like vin-man said. We cut openings in them in several ways, Gas powered demo saw with diamond blade with water is the simplest. Hammer drill with multiple holes close together and a sledge is another. The $hit pumper who we work for also has a core drill with 6" and 8" bits for doing exactly what they are trying to do.

        If the tanks are steel they are usually fairly old and rusted. Just be careful that the top doesn't collapse and in you go. Lots are so bad I've cut them open with a shovel. To be honest with most steel tanks we just rip open a hole with the backhoe bucket, Steel tanks are generally to small to be acceptable nowdays and we'll end up replacing it as soon as he gets it pumped down.

        In a steel tank, I'd cut it with the demo saw with an old diamond blade and flood the sucker with water while cutting. If possible I'd try and fill the tank to the top to eliminate as much gas space as possible. That may not be possible if the system still works well. Dry ice would work well to help displace the gas, if you can get it in the tank. If you have a mag drill and a big enough bit that might also work, check with the pumper if he can work thru a small hole or if he needs a man sized access.

        If its steel, and never had a hole to pump it, I'm betting he'll need a new tank. The crap in the bottom will be so solid it just won't pump.

        FYI Keep your mouth shut while cutting. I would wear a set of goggles and a dust mask to be sure nothing falls in and splashes you in the face. It's NOT fun when that happens.
        Last edited by DSW; 02-28-2009, 09:22 PM.

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        • #5
          Thanks guys,I want to say the tank is concrete and the top is made from steel and I'll be using a torch to cut the hatch.
          DODGE 1 TON 6.7
          PIPEPRO 304
          TO MANY TOOLS
          JUST WELDING IN CIRCLES
          rig welders are like wheelbarrows hard to push around
          and easily upset
          go flames go

          Comment


          • #6
            Jeez Dan, shouldn't they sniff that and check for LEL's? If something does go Boom, will your insurance cover you or say adios?

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            • #7
              My Uncle was cutting on a junk car near the outflow of a "not quite working correctly" aeration system and blew the lid into the air. The unit was over a hundred feet away. It's not supposed to allow a flammable mixture of gas and air, but I think this was not "installed to manufacturers specifications."

              You could plug the outflow and drill a breather hole in the top and run water until it floods out. No airspace, no explosion hazard.

              80% of failures are from 20% of causes
              Never compromise your principles today in the name of furthering them in the future.
              "All I ever wanted was an honest week's pay for an honest day's work." -Sgt. Bilko
              "We are generally better persuaded by reasons we discover ourselves than by those given to us by others." -Pascal
              "Since we cannot know all that there is to be known about anything, we ought to know a little about everything." -Pascal

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              • #8
                Originally posted by DSW View Post
                FYI Keep your mouth shut while cutting. I would wear a set of goggles and a dust mask to be sure nothing falls in and splashes you in the face. It's NOT fun when that happens.
                Experience is a great teacher huh lol

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                • #9
                  Didn't happen to me, that was what I was told on my 1st septic job. But I saw an operator slam the bucket thru a lid and spray crap all thru the cab. Didn't know a tank was there. You could see the outline of his body on the front winshield where the crap didn't make it. Oh and it was late fall and every house we checked in the neighborhood had the outdoor water turned off!

                  $hit pumper had a new guy work for him PT. Guy got done loading the truck but had to leave work before he could get to the sewer plant and unload. Boss took the truck and when he uncapped the discharge pipe had 5000 gal of sewage dump on him. PT'er left the valves open because it was "faster". Sewer plant guys just told the boss to go around back and strip, they'd be out in a few minutes. Came out with a bar of soap and a fire hose to wash him down. Boss drove back to the shop in the buff. I'd have loved to see the cops face if he had gotten pulled over.

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                  • #10
                    lol

                    oh god i would have passed out thats funny $hit no pun intended

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                    • #11
                      awww man, I was craving a late night snack, so much for that thought. Funny story though.

                      Dan, I think Cornerstone is right, check those LELs, it would be a real sh!tty way to go
                      hre

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                      • #12
                        This post brings back bad memory's.
                        A buds son was cutting storage tanks with a sawsall, got to the last tank.
                        Now all had been checked, they were safe, well the last was not safe.
                        Had to ID the man (25) by dental records.
                        Pete was a good man, loved fishing and was good to His kids.
                        If you aint checked for methane, then it has the stuff in it.
                        My tank is 30 years old and has a hatch, dig the top clean and lift off the steel plate.
                        Be safe
                        Jeff

                        Give more than you get and
                        you will get more than ya need.
                        This is true for the good and bad
                        that life puts out.

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                        • #13
                          The Sewer guy should have a air tester.Check LEL and check for hydrogen sulfide,it dulls your sense of smell and will put to to sleep [forever] before you realize something is wrong.
                          Lots of jokes made about this type of work,and I am guilty of it also,but it can be a diaster waiting to happen.

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                          • #14
                            Ah yes the stories about septic....

                            Not to Hijack the thread but heres 2 interesting ones.

                            Last year we had to go and discontinue an old tank. Young couple had bought the house and had just finnished remodeling the 3 season porch into a new top end kitchen on their own. Only minor issue was that when they built the 3 seaon porch they built it over the septic tank and left the access in the floor of the room. Now that tank is in the middle of their new kitchen and in order to pump the tank the $hit pumper has to drag his hoses thru the living room, since they closed off the exterior door to the porch when they did the remodel.


                            This is one more. I showed up form another job to find this.
                            Click image for larger version

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                            Another burried tank. They built the new patio over the tank. Home owner absolutly would not dammage the patio. Old field died, but the health inspector ixnayed a new system unless there was access to the existing tank or a new tank was installed and the old one discontinued. Boss is 6' 7" so he doesn't do tight places. New guy is 5'4. Hmmm..... wonder who gets to tunnel under the slab. He's laying facing us on top of the tank. so they had tunneled at least 8' to 10' to reach the lid and then remove it. Pumped the tank, then I got to go in with the air mask and repipe the drain thru before we filled the tank solid with grout. I don't have the best pict of him with the WTF face, as I called him and snapped 2-3 fast shots. Gave the best pict to his mom for christmas. Hey what are friends for?

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                            • #15
                              So I thnk I'll remove the lid and cut it with the torch(If I can) I'll for sure take a sniffer with me, and I guess I'll tie it to a piece of rope and lower it down??? Its a very odd feeling if and when stuff like this happens, its funny because if and when I use a mud pack inside a pipe that I am going to weld/cut up I always close my eyes before I strike an arc which is real helpful when stuff goes BANG!!! I'll take some pics for you boys
                              DODGE 1 TON 6.7
                              PIPEPRO 304
                              TO MANY TOOLS
                              JUST WELDING IN CIRCLES
                              rig welders are like wheelbarrows hard to push around
                              and easily upset
                              go flames go

                              Comment

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