This was suppose to be a triumpant post about finishing up the drain pipes under the sink. I suppose that's where I should begin...
I only took the one picture, and then the events precluded me from taking any others, and now, there's not much to see - I'll try to paint a picture for your mind's eye.
The morning dawned a bit overcast. The sky looked like cream of mushroom soup, but lacking the mushrooms... The weather bureau suggested that things would clear up slightly around lunch; I felt the same sort of optimism about the skies clearing up as Jeremy Freedman getting his first tube of Clearasil.
Shortly after breakfast, I opted to head outside - as part of my "zone cleaning" routine, the outdoors represented the next zone to be tackled (preceeded by the sauna, followed by the entrance and woodstove). Kenny agreed to come with me and help out. He was in a mood to be of assistance today and I certainly didn't want to deny him.
We started by hauling cardboard and trash to the garage to wait until such time as I could deliver them to the local waste transfer site. Kenny dragged his sleigh to the top of the driveway hill, but he was unable to get it to slide down, the ice on its bottom being rougher than a tramp steamer's barnacle infested hull.
Returning to the cabin, Kenny assisted me in piling the last of this season's burnable wood in the slab shed. I piled, and he used his shovel to pry apart the frozen logs and slabs. They were so tightly joined you couldn't have gotten a ten penny nail between them with a sledge hammer!
I give him credit, he stuck it out and even when I moved on to filling the wood bins and cleaning off the front porch, he didn't retreat inside to the sincere pleasures of his Lego or books.
We came inside where I prepared a lunch of yogurt and jam for him, and nacho chips that were as broken as Steven Harper's dreams for myself. At least I had hummus to help me keep the fragments together. He'd probably be phoning me in to the RCMP for being the kind of person who enjoys hummus.
After lunch dishes were cleared (who am I kidding? They're still on the table beside me...), Kenny headed upstairs to continue building the tallest Lego tower ever, and I proceeded to begin work on the drain under the sinks.
I at first had the rather pedestrian notion to directly connect the two drains together, with a T in between to connect to the overflow drain from the water tank. Then I had the revelation that I could switch up the T in such a fashion as to allow a more direct connection between the overflow drain, and have a bend in the drain from the sink. This would allow me to open up more space in the front of the corner cabinet - never a bad thing.
I cut, checked, rechecked, and did multiple dry fittings. In hindsight, it's better to check, recheck and THEN cut, but at least I only made one or two little errors.
With trepidation, I glued the pipes together, careful to twist each connection to try to ensure ample coverage of the adhesive. At last, all was in readiness.
|Looking good from this angle.|
|Maybe even looks like a real plumber installed this!|
He reported that his finger was both unshocked, and unwet (er, dry).
Then, with great fanfare and excitement, I said I would test the overflow drain.
Kenny climbed into an empty box that once held the sinfully sodium-soaked selection of beef flavoured ramen and said that in light of recent events, it would serve as his life raft.
I punched in five minutes on the timer, knowing full well that this would fill the tank fuller than Papa's plate at an all-you-can-eat buffet.
We watched intently as the line in the hose climber higher. And higher. And higher.
It shot to the foam plug, and then did something different from the previous disaster.
I was slightly bemused and actually took on the demeanour of a fool who thinks he's won just before he realizes that he's already lost.
It retreated some more.
It moved below the level of the top of the tank and continued to drop.
My smile followed the movements of the sight line as it plummeted to the very bottom of the tank in less than a minute.
Good golly I said to myself - it's set up some sort of weird siphon that is actually draining the entire tank if you happen to overpump it! I began to feel like I was sixteen years old again, trying to ride my tricycle down a hill and then realizing that the pedals were turning faster than my feet could keep up!
The sound of the rushing water was like the blood in your ears just as you are about to pass out, only this time, I didn't have the bliss of unconsciousness to relieve me. Horrific gurgling noises groaned from the sink drains, and then slowly, terrifyingly, unable to be comprehended by even the stoutest of minds, the water level in the tank began to rise again.
In my lizard brain - the water leaving the tank had created a powerful enough vacuum within it that it had sucked a new volume all the way from the well and had begun the cycle again.
Kenny, sensing my panic instantly, backed away from the tank.
The tank, creaking and groaning from the immense negative pressure put on it collapsed like the 2013 Toronto Maple Leafs in the playoffs. I rushed up to the landing to see the top of the tank inverting like an upside down version of Cheops masterwork.
I ran downstairs, inadvisable at the best of times on alternating tread stairs, and rushed under the sink.
At first I tried to loosen the P trap, hoping that I could introduce more air into the line - why hadn't the sight hose been enough? Curses it for having a diameter narrower than Hank Hill's urethra!
I couldn't budge the cap on the trap with my bare hands.
Begging Kenny for the recently purchased jar lid opener, I scrambled through our kitchen utensils to find it, but in my panic, I couldn't get a grip on the incoming filter - I would have gladly accepted a gush of water from it, compared to the visions of the entire well having to pass through my tank and into our grey water system.
*** Intermission ***
Our well is 4' wide. It also usually contains in excess of 6' of water. This gives us a volume calculation of 75.6 cubic feet, or 565.5 gallons. Our tank is 31 gallons. We can fill 18.5 tanks before running the well dry. Also, the well will be recharging in the meantime.
*** End of Intermission ***
18.5 repetitions of this horror? I couldn't imagine the greywater system handling 565.5 gallons without backing up completely. 565.5 gallons of water being pumped back into our cabin with no way to stop it.
I redoubled my efforts on the P trap and managed to get it off and a little water drained out into a bucket placed with absolutely no care. I hit the pump button to try to relieve some of the pressure on the water tank by replacing some of the water that was being sucked out.
At last, the water stopped gurgling, but not before Kenny had abandoned me without reservation.
|Kenny's new shelter.|
|He thinks he'd rather live here than in the stressful cabin.|
*** 16 Hours Later ***
After a rather poor and interrupted sleep, I still find myself unable to think properly about the situation. But I feel like maybe I have some new insights.
|Diagramme added for clarity.|
It is inconceivable that the suction created by the water running out of the tank had enough power to pull water from the well. The grey water pit is at least a few feet above the level of the well, so it is a physical impossibility that the water could come from there.
Additionally the hoses on the top of the tank do not extend into the tank any distance - so unless the tank completely and totally collapsed, water couldn't continue to reach the outflow pipe.
What I think must have been happening is that the water filled the overflow pipe completely, all the way down to the P trap under the sink. When the pressure from the pump stopped, that water still was being pulled down by the force of gravity. That water needed to be replaced by air in order for the pressure inside the tank to be equal to that outside the tank.
Unfortunately, there are only three ways for air to get back into the tank. The first is through the incoming line from the well - and that's a dead end right off the bat. The end of that pipe is seventy five feet away and five or six feet under water.
The second path is from the overflow pipe. From the top of the tank to where it drained into my sink drain is probably a good ten feet, with three ninety degree bends, followed by a coupler that probably reduces the diameter of the hose from 1" down to 3/4". That's quite a bit of water falling down for air to come back up through. I don't think the sink drain plugs were in place, but if they were, then the air would have had to have been sucked up through the P trap too. In fact, if the drain plugs were in place, the nearest air would have been a further twenty feet under the cabin at the Y junction coming from the bathroom sink (where there is never a drain plug installed, although I suspect that we have one we could use if we wished).
The third and final path is the sight hose. This is only a 1/2" hose, at the bottom of the tank, going through a coupler that probably reduces the diameter down to about 3/8". It would have about seven feet of water in it when the pump was shut off. It would have taken a tremendous amount of suction to pull that water back into the tank.
Now that I've typed it out, I think I may understand it a bit better. So it seems that what I was witnessing was not the water draining completely from the tank, just the force of the water draining out due to gravity pulling the water out of the sight hose. The vacuum in the tank caused by that water running out caused it to buckle and creak. There just wasn't an easy way for air to get back into the tank. I had thought that air would come up quickly through the sink drain, but obviously not as quickly as required to relieve the pressure on the system.
And for the solution?
I'm honestly not completely sure. During the night I lay awake with visions of one way valves and just allowing the pump to pump against pressure in the tank. I'm not sure how much pressure the pump generates at that height (not a whole lot I'd expect, it must be near its working limit) - but I don't know if I'd want to have it pumping into a suddenly sealed tank. I'll follow up with Dave at Maier and see what he thinks of that idea. I'd also have to put a valve on the sight hose to prevent it from being an outlet for the excess water.
The other option that seems to make some sense is to return to the system as it was when I first tested the overflow - simply have the overflow hose "dangle" into a 1 1/2" ABS pipe. Exactly as the washing machine is currently working to drain. The only reason it failed the first time was because I hadn't put a junction on the drainpipe further along to keep the water in the system.
This would remove one ninety degree bend, one coupling, about a foot of pipe and the very real possibility of the end of the pipe being under water from the equation. It would provide lots more air introduction into the hose as soon as the pressure is released. There wouldn't be a seal around the drainage pipe and the overflow pipe. As soon as the pump shuts off, air would only have to head directly up the pipe and into the top of the tank, without being sucked through any other obstacles. I could still hopefully install this completely under the sink.
There must have been a similar pressure on the tank during the first dramatic test, but it couldn't have been as bad because we didn't notice it (then again, maybe the water on the floor distracted us).
Well, time to purchase more ABS fittings (and maybe pipe) and head under the sink to try another plan. I can't express how frightened I will likely be to test this once again.