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Thread: Computer-controlled digging for water main replacement?

  1. #1

    Default Computer-controlled digging for water main replacement?

    I live in a nice old row house in Washington D.C. The plumbing is the original steel (or iron?) piping from about 1933. The water pressure is getting kind of low, and I was told that it was likely because the water main has rusted up inside, between the house and the meter, constricting the flow. I understand the solution to this is to dig up the old water main from where it connects to the meter to where it enters the house and to replace it.

    This would be a huge job, depending on how it was done. The meter is out on the street, and the main passes under a sidewalk, then under a 5' raised front yard with a tree and brick retaining wall, then under the concrete slab in the finished part of the basement, and emerges in a utility area that is in the middle of the house. To dig it up would mean breaking lots of concrete, probably killing the tree, and doing major damage to the finished basement.

    I was complaining about this to my grand dad, and he told me he didn't think that was necessary. When his brother needed the same thing done, the folks who did it came out, dug a hole by the meter and one in the basement. They then carefully measured and had a computer-controlled digger of some kind dig a tunnel that they were able to thread the new main through, disconnecting and abandoning the old one. No trench needed between.

    Is this something that is commonly done? Do you know what this procedure is called? How would I go about finding someone in DC who could do this?

    Thanks,

    Liv

  2. #2

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    I am also seeking advice for this same problem. My incoming water line runs under a large attached ground-level deck plus an addition to the house.

    While I haven't yet determined exactly how much needs to be replaced, my feeling is that all the piping under the house probably needs it due to age and internal rust buildup. Part of it was replaced with copper before I bought the house but much galvanized piping is still in service.

    I'm open to any information about this replacement problem. I will be hiring a professional to do the work but the one I've talked with so far wasn't too happy to hear about having to dig under the house.

  3. #3
    DIY Member cruiser's Avatar
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    Liv,

    IS it not possible that the pipes inside your house(galvanised) are the ones that are causing the trouble?. These guys rust from the inside out,so they may appear to be in good nick but the trouble may lay inside. I'm currently working on my 1930 house and this was my problem

    I'm sure a plumber could check the pressure as it enters the house and then measure it as it leaves a faucet in the kitchen/bathroom,this would isolate where the problem is... out front or inside.

    M

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    DIY Senior Member CHH's Avatar
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    Tunneling under roads for utilities is commonly done. Basically it's a crawler mounted drill rig set up to bore horizontally. I don't know what it is called and it isn't that big of a deal. Probably costs an arm and two legs but I bet they can be in and out in a day.

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    Retired Defense Industry Engineer jadnashua's Avatar
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    You could have great pressure, but only have the aperature of a soda straw, so your volume would be low. Don't confuse volume and pressure. WIth the valves turned off, regardless of the pipe diameter, the pressure should be okay. But, trying to take a shower with only a soda straw for volume wouldn't be very satisfying.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    DIY Member George R's Avatar
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    Hi Liv. I'm not a plumber, but I've seen something similar done to two homes in my neighborhood, although probably not as high-tech as you're describing. It was done by just a local plumbing outfit, not a really high tech type of outfit. I talked to the plumber and asked him about the process. He basically took what he referred to as a "mole", it looked like a torpedo about 4 ft long and 4 inches in diameter hooked to an air compressor (the big kind that you trailer behind a truck) and attached to 1 inch or 1 1/4 inch poly pipe.

    He cut out approx 1/2 of a concrete block in the basement and started the mole there. It went under an approx. 12 ft patio and then proceeded another approx 25 ft into the yard. He then probed with a rod to find the "torpedo", and then dug a ditch to the city line in the conventional way. Nothing really high tech, he said you get a feel when the "mole" is going left or right or up or down because of hitting rocks etc. and he knew generally where to find it.

    I have no idea what it cost, but like CHH said, that part of the re-pipe was done in just a day or two. The same outfit re-piped the whole house.

    This was in a suburban setting with a conventional front lawn, I also have no idea how this would work in a row house environment where you basically have house/concrete sidewalk/concrete street.

    BTW I used to live in Springfield, VA. I loved some of the old DC rowhouses.
    Last edited by George R; 08-02-2007 at 07:42 PM.

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    Commercial Plumber markts30's Avatar
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    Check into "directional drilling"...

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    In the Trades Gary Swart's Avatar
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    There is little doubt in my mind that the water main is corroded nearly shut. It would surprise me if it wasn't leaking as well. Your house pipes are probably just as corroded. Some areas have water that is less corrosive than others, can't say about yours, but 75 years is well past life expectancy for steel pipes. It will be expensive to run a new line anyway you do it, but far less invasive and with repairing the damage done by trenching, it will be less if you get the new line tunneled in. I'm sure there are companies in the D.C. area that do it. You should also consider redoing the house lines as well. As noted, don't confuse pressure with flow volume.

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    DIY Senior Member Mr_Pike's Avatar
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    The Moles or "Bullet" as we call it are a very very neat machine. We charge 3 times as much per foot to use the bullet as opposed to the back hoe or trencher, but it is worth it in most cases to not disturb concrete, decks etc.

    They are a basically a torpedo shaped tube with an internal hammer mechanism. The internal hammer pounds the bullet forward in the ground, basically in the direction you point it. You try to make sure it is level and pointed in the right direction to start with, cause thats what you get!!

    There is a reversing mechanism inside the unit, we punch out a block like stated above, and aim for a hole dug outside, past all the landscaping and deck. Works great until you hit a rock or tree root which will deflect the unit to a new heading.

  10. #10
    DIY scratch-pad engineer leejosepho's Avatar
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    Quote Originally Posted by Liv
    ... a computer-controlled digger of some kind ... to thread the new main through, disconnecting and abandoning the old one. No trench needed between.

    Is this something that is commonly done? Do you know what this procedure is called? How would I go about finding someone in DC who could do this?
    I am not absolutely certain here, but I believe this company can do that kind of thing:

    http://www.henkels.com/corporate/brochures.asp
    Henkels & McCoy, Inc.
    8534 V Terminal Road
    Lorton, VA 22079
    Tel: 703-550-0450

    2300 Anniston Street
    Richmond, VA 23223
    Tel: 804-782-1913

    1515 Wilson Blvd.
    Suite 300
    Arlington, VA 22209
    Tel: 703-248-3951


    If I recall correctly, that is the company I once saw use a remote-controlled and hydro-forced device of some type to direct a flexible tube/pipe beneath a parking lot and under a small creek as well as around the major roots of a nearby tree to run a communications conduit between two buildings about 150 yards apart ... and they only had to dig about a 4' diameter hole at each end.

  11. #11
    Plumbing Designer FloridaOrange's Avatar
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    Quote Originally Posted by Mr_Pike
    The Moles or "Bullet" as we call it are a very very neat machine. We charge 3 times as much per foot to use the bullet as opposed to the back hoe or trencher, but it is worth it in most cases to not disturb concrete, decks etc.

    They are a basically a torpedo shaped tube with an internal hammer mechanism. The internal hammer pounds the bullet forward in the ground, basically in the direction you point it. You try to make sure it is level and pointed in the right direction to start with, cause thats what you get!!

    There is a reversing mechanism inside the unit, we punch out a block like stated above, and aim for a hole dug outside, past all the landscaping and deck. Works great until you hit a rock or tree root which will deflect the unit to a new heading.
    I've seen that done for running fiber cable on a site. Pretty cool!
    Matt
    Semi-professional plumbing designer
    Enjoying life in SW Florida

  12. #12

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    Thanks for all of your answers. I agree that it is the water volume, and not the pressure like I mentioned. I will try that company and see if they can do it for me.

    I also know that the interior plumbing is due for replacement, but we only plan to live here 2-3 more year, and if we can get by without redoing it in the meantime, we will be happy.

    I am really glad I found this message board.

    Thanks!

    Liv

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