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  • Running drain from Weeping Tile

    Hello again folks,

    I need your assistance with a problem encountered with a weeping tile to lateral connection through a floor drain. Here it's referred to as a "running drain or trap", or "foundation drain" as some know it.

    It's a once legal configuration that was utilized in new construction back in the 1970's in my area, London, Ontario, Canada. I understand it is no longer code approved here, but don't know when or why.

    Below the basement floor, an 8' horizontal section of 3" line freely empties itself into a 3" floor drain above the usual standing water of the drain trap.

    The floor drain connects to the 4" lateral in the usual 'Y' manner and continues to the street where it connects with the 8" main at the 3pm position.

    Further back of the 'Y' floor drain connection is the main stack, and inlets from a basement washroom and bathroom and kitchen on the ground floor. Nothing unusual there.

    On two occasions in the past year the floor drain has significantly backed up with storm water into the basement. While the customer has had a few minor back-ups of a few inches over a small area in their 40 years of ownership, these two have resulted in 6" of water throughout the basement.

    Upon being called in last March, I camera inspected the lateral and found it to be running well visually to the main and without any obstructions.

    However, I did observe high water marks along the lateral right back to the house, along with the lateral flow only having a drop of 1"-2" into the fast running main, although that was some some weeks after the back-up itself. This was after a warm period of melting snow and rain had subsided.

    Although there is a separate storm water collection run on the street, given the evidence I suggested there had been a surcharge, blockage or back-up in the main which stopped the lateral and hence the storm water from their weeping tile, from discharging into the main.

    I called in the city to check their mains and whether any problems had been reported in this neighbourhood at the time of the occurrence. They found no evidence of surcharging and found no other occurrences.

    My recommendations at that time were to; utilize a back flow preventer on the floor drain, touch up some minor grade elevations, be aware of evestrough/downspout issues and consider installing a sump pump if the problem arose again. I thought the issue might be an anomaly. How wrong I was!!

    This past New Year's we had considerable rain which melted a lot of a heavy snowfall. Because of the back flow preventer the storm water backed up under pressure into the weeping tile. It then began to come through at the joint between the wall and floor. Another 6" of water entered the entire basement.

    Upon returning to the customer last week, they reported that plunging the floor drain, as recommended by city maintenance, had created flow immediately and the water drained out quickly. That got me wondering why?

    Upon speaking with the individual from the city he makes that recommendation frequently when running drain traps are present. Often that works he says, including for another home around the corner from my customer on the same day. His belief is that there is a blockage of foreign material in the trap, and it's removal by plunging resolves the problem.

    Furthermore, he states that when homeowners bypass the floor drain by rerouting the weeping tile line directly the lateral, they haven't had any further problems.

    I'm not prepared to accept either answer without some investigation. I know I checked my customer's trap last year just as the back flow preventer was installed. I agree that a direct connection is better, but is the trap really the reason for the problem?

    I still think the primary problem is that high flow in the main is eventually causing the extremely large quantity of storm water around the foundation to back up into the weeping tile. It just can't get out to the main from the lateral. And, it wouldn't matter if it was the weeping tile or a toilet flush that eventually filled the lateral before it could drain away.

    I know that shouldn't happen, but the basement is perhaps 12" or more lower than others on the street. That may well have resulted in less than a code slope of the required 2%, or 1/4"/foot. Or, if code was met that it was still inadequate in these particular circumstances. There is no fixing that fault though, only managing the repercussions of that fault.

    I have now recommend to my customer that they:
    - Make a direct connection to their lateral from the weeping tile (likely not legal in this city but practical),
    - Install a sump pump overflow connected to the weeping tile line to handle high volumes whenever they do occur, and
    - Install a Mainline Fullport brand backflow preventer in their lateral to prevent the main from ever reaching back into the house, as shown in the diagram below.

    - Mainline backflow details: http://www.backwatervalve.com/pdf/fullport.pdf (Copy attached)

    - City of Winnipeg brochure, (extracted diagram shown below):
    http://www.winnipeg.ca/waterandwaste...ng.stm#install

    However, I'm suspecting there is a design limitation or flaw with running drains. Hence, I understand they are no longer approved for use here. What is your expert knowledge of these configurations?

    Beyond having occurred some hours after the backup was in process, what may explain the apparent positive and miraculous results obtained solely by plunging the drain? Air lock? Possible obstruction from the house sewer backing up into the trap? Hydrological imbalance? Will a direct connect from the weeping tile to the lateral eliminate that problem or only move it whenever the particular set of founding circumstance reoccur?

    I'd appreciate your expertise in understanding these puzzling circumstances surrounding a running drain.

    Sincerely, Dave Hutchison
    PipeTech Solutions Inc.
    Sewer Inspection & Repair....without Digging!
    www.pipetechsolutions.com

    2011/01/19 Addendum responding to Ace Sewer's questions:
    - Thanks for your response. You recap is correct in all four points. To clarify, the weeping tile drain or foundation empties into the floor drain about 3' above the water seal from the trap.

    I agree with your diagnosis, but puzzled why plunging the drain worked, well after the back-up occurred began? According to the customer, the 6" of water in the basement immediately drained away in minutes.

    I did camera the floor drain trap to the lateral last year as mentioned, in addition to the lateral itself. It was clear, with no obvious obstructions. The drain back flow preventer was then installed and in place immediately prior to being taken out to plunge the drain, as recommended by the city. I did not observe toilet flow at that 'Y' from the drain line angle. I will do so on a revisit.

    No conclusive evidence that the 4" lateral was blocked this time, nor last. Just my assumption as the clear storm water from the weeping tiles was not draining away. I don't know if the toilets worked at the time. It was never mentioned by the customer, nor asked by me.

    This neighbourhood did have significant problems with flooded basements in the 1980's. That was corrected through major municipal work that included diverting sanitary into storm at times and a huge holding tank by way of a long 54" pipe that stores excess until the municipal system can catch up.

    The city's recent response was there was no problem with their mains surcharging, overflowing or backing up etc. (Of course!) However, the main lines may have reached their full 8" capacity which causes this particular home to have a problem, but not many others. I.E. Because its basement is lower leading to the possibility of inadequate fall for this one house.

    Only 3 houses in the area reported problems to the city, plus one neighbour across the street who didn't. As mentioned, my customer and another house on an adjoining street connected upstream to the same main line, had their problem resolved by the plunging of the floor drain recommendation from the city. As mentioned this is the standard response from the city, with some apparent success.

    A sump can't be connected to the city storm line. It only drains from the roadway catch basins. I've recommended discharging the sump onto the sloped back yard and essentially using it only for the excess volume of the weeping tile. My thinking is to still let the weeping tile drain into the house lateral to remove as much storm/ground water as possible from around the foundation. That provides the best of two options.

    So, I'm back to understanding why plunging these running drains seems to solve the back-up problems? As alluded to, is there a real blockage that occurs, either from the main or the house backing up and depositing debris into the floor drain line? Or, is there some unusual situation being created by the presence of the running drain configuration?

    Surely, if the lateral was no longer blocked at the street it should continue flowing from the weeping tile, down the trap and into the lateral and out to the main when it could....shouldn't it? Is there anything but a blockage of tissue and solids that would prevent that resumption? And, is it reasonable to expect that a blockage would occur anyways from tissue and solids?

    Again, thanks for your contribution to unraveling this puzzle!

    ...Dave
    Attached Files
    Last edited by PTS; 01-20-2011, 10:13 AM.

  • #2
    Re: Running drain from Weeping Tile

    Nice post. Chock full of information. I'd have done much as you did and am equally confused by it's behavior.

    Let me recap to make sure I understand correctly.

    - the 4" exiting the house is a normal san sewer line with no issues.
    - it connects to a sanitary main with no issues
    - it has a floor drain tied to it
    - there is a 3" drain, which you call a weeping tile drain and would here be called a foundation drain, which empties into the floor drain or onto the floor near it. the weeping tile drain brings groundwater from outside the house to the floor drain.
    - the problem occurs and only occurs during periods of high melt and or heavy rainfall, when there is a lot of groundwater

    It seems to me, if I understand the situation correctly, that one of a few things is happening;

    - the sanitary main is being overwhelmed and backing up into the house
    - the trap on the floor drain is restricting flow and the weeping tile drain is overwhelming it (possibly the weeping tile has more than it can handle and groudwater is coming in through the walls as well)
    - the 4" service has more than it can handle with all the groudwater the weeping tile is making at those times

    If plunging the floor drain fixed the problem at it's last occurance, then the floor drain trap or line was the issue. That brings up the question of how it got blocked. You are certain the trap and the line leading from it to the 4" service were both clear before the latest problem, and that plunging the floor drain cured the latest problem? If so, then something blocked the trap or it's line, and it wasn't groundwater. May have been debris kicked into the floor drain since you were there. May be a situation where paper and solids from the house wash up into the line serving the floor drain and settle there. May be the main backing up and depositing debris.

    If the main is being overwhelmed and backing up, then the backflow preventer will stop that, but your customer still has to get rid of his groundwater, and if the san main is backed up, rerouting the weeping tile to the 4" san service will not help with that. A sump pump would help only if it's discharge went somewhere other than the 4" service.

    I'd suggest putting a camera through the trap on the floor drain to it's junction with the 4" service and verifying no issues there. Then flushing paper in the toilets while watching to see that it does not get deposited in the line serving the floor drain.

    Was there any conclusive evidence one way or the other that the 4" was backed up at the time of the problem? did their toilets work at that time? was the backup in the basement clear groundwater or was it obviously sewage? Can you rule out the main backing up? If the main is backing up, isn't the the city's problem if you can prove it?

    It seems suspicious that there is another house in that area with the same issue. Do they both sit low relative to the main and other houses? Has the city video inspected the main? Do they have groundwater infiltration issues with it? Is there a manhole you can pop open and see if it is filling up during the next rain?

    The nuclear solution would be to tie the weeping tile to the storm sewer, install a sump pump also discharging to storm sewer, and install a backflow preventer on the san service line.
    This is my reminder to myself that no good will ever come from discussing politics or religion with anyone, ever.

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