Bog filter failure - has this ever happened to anyone else?

[Lisak1]

Good thought @poconojoe - too much heat while sawing could have melted the PVC a bit, causing a weak spot maybe? And then the pressure built up and blew a hole in it. That's a weird one for sure! @mtravigne how many GPH are you pumping through the bog?

I'm also curious about the nature of the dirt in the pond... it almost looks milky. I'd expect it to be cloudy for a bit but then settle out.

 

[Ronfire]

Looks like there was movement on the pipe with gravel to wear through it.

 

[poconojoe]

Good question by Lisak1 about the size of your pump. How many GPH is the pump?
I still can't fathom how the PVC around that hole looks so thin and blown out. It looks like it was melted from the inside out. Could that just be wear from the water pushing through? But it's funny since none of the other slits have wear like that at all. Could it be so many of the other slits were clogged and the force of the pump blew out that hole? I'm leaning more towards a manufacturer defect.

 

[Mmathis]

I, too, am baffled. Please post some pics of your set-up, including the bog.

 

[mtravigne]

Some thoughts...
Both legs of your manifold should have clean-out stacks, not just the right as one shown in the first picture. Maybe the left one filled up with muck and put more pressure on the remaining slits. Were any portion of the pipes clogged? I'm guessing no, since you didn't mention that.

Not that there are any specific rules, but I spaced my slits 1-1/2" apart and cut 1/3 through the pipe. Just throwing that out there, I'm no expert, but maybe more slits are better?

As far as the blow-out...that's very strange...the walls of schedule 40 are pretty darn thick.
Maybe the pipe was defective and the wall was thin in that area.
Not trying to blame, just trying to get to the root of the problem...
It almost looks melted. Maybe when you cut the slits there was a lot of heat generated? What did you cut with? Could the blade have been dull? That might create a lot of heat.

Maybe that particular slit was cut too deep and weakened the pipe?

Do they make schedule 80 in smaller sizes? I've seen it in big sizes. If they do, maybe that's the answer.

Hope you get it all worked out and it's good you posted the problem. This discussion will help future bog builds.

I used a hacksaw (!) to make the slits so I’m sure they were irregular. I also cut halfway through the pipe (and maybe a smidge more). So for the replacement filter, my husband used the chop saw to make even cuts 1/3 of the way through the pipe every 2 inches. Hopefully the consistency of the slits will prevent that from happening again. The pipes themselves were pretty clean, there were no clots or debris in the pipes.

 

[mtravigne]

Good thought @poconojoe - too much heat while sawing could have melted the PVC a bit, causing a weak spot maybe? And then the pressure built up and blew a hole in it. That's a weird one for sure! @mtravigne how many GPH are you pumping through the bog?

I'm also curious about the nature of the dirt in the pond... it almost looks milky. I'd expect it to be cloudy for a bit but then settle out.

Yes the water does look milky. I’ve never had water like this before. Since nothing is unchanged I just attributed it to the combination of hot summer days and a failing bog filter.

 

[combatwombat]

Lots of great theories here! Could a piece of solids (pea stone?) have been pumped into the system and, not being able to escape through your slits, got lodged at that one spot and eventually built enough pressure to rupture?

What's feeding your bog? Where is the water being pulled from? Do you have pea stone in your pond?

Just another theory Honestly, seems unlikely given that sch 40 pvc is rated for, I think, 450 psi and most pond systems operate at a psi less than normal house pressure, which is usually under 80. But I wanted to contribute something!

You don't happen to pump 150ºF water through your system do you? Haha.

 

[JRS]

I see your close up has dwv which means Drain Waste Vent which is the thinner type. My local store carries both types, DWV and the pressure rated with the thicker walls.

What is DWV Pipe?

What is DWV PVC? Is it Different From Schedule 40? If you\'ve been in the market for PVC pipe and fittings you may have come across something called DWV. DWV parts look very similar to standard white schedule 40 PVC pipe and fittings. The only real difference is that DWV PVC is not made to...

www.pvcfittingsonline.com

 

[Lisak1]

I see your close up has dwv which means Drain Waste Vent which is the thinner type. My local store carries both types, DWV and the pressure rated with the thicker walls.

What is DWV Pipe?

What is DWV PVC? Is it Different From Schedule 40? If you\'ve been in the market for PVC pipe and fittings you may have come across something called DWV. DWV parts look very similar to standard white schedule 40 PVC pipe and fittings. The only real difference is that DWV PVC is not made to...

www.pvcfittingsonline.com

OK. Now we might be getting somewhere!

I think all of us who have used Schedule 40 PVC know how thick and tough that stuff is... I wasn't aware there were two kinds that could both be labeled Schedule 40.

 

[poconojoe]

OK. Now we might be getting somewhere!

I think all of us who have used Schedule 40 PVC know how thick and tough that stuff is... I wasn't aware there were two kinds that could both be labeled Schedule 40.

So the mystery is solved?

So now anyone building a bog beware... stay away from DWV PVC!

When I go to Lowe's they have those two types separated on different sides of the isle. I'm guessing you found the culprit. So, I'm assuming the DWV has a thinner wall since it's not meat to be used for anything with pressure behind it.

Good catch!

 

[poconojoe]

Ok, so I read that link for DWV pipe. Geeze, the schedule 40 stuff is inexpensive enough. Do they really need to manufacture something even less expensive?
I get the specialized fittings for p-traps and such. I guess if your a contractor installing miles of PVC, it might help a bit to have a less expensive variety for waste and vent lines. You would think it would be a hassle having to stock all those different fittings though.
I can just imagine the plumber telling the apprentice " go get me a PVC street ell, but make sure it's schedule 40, not DWV!"...dumb kid!

 

[JRS]

Asked a plumber I know about the nuances. He said schedule 40 pipe should have the same wall thickness. I'll have to check my local store to see how the thinner pipe is actually labeled, perhaps just DWV. He then mentioned this light weight foam core PVC which I had not heard of which is Sch.40 and DWV, which would explain the label and lack of durability:

JM eagle 4 in. x 10 ft. Foamcore PVC Schedule 40 DWV Plain-End Pipe-10165 - The Home Depot

PVC Schedule 40 Foam Core pipe is for drain, waste and vent purposes only. It is used in gravity fed waste elimination systems. It is for non-pressure systems where temperatures will not exceed 140°

www.homedepot.com

.

 

[poconojoe]

So, what's the story? Was the ruptured pipe of the DWV variety or normal schedule40?

 

[GBBUDD]

Schedule 40 is not designed for pressure HOWEVER. Swimming pools and such generally work under low pressure and is rarely a problem. Your failed spot definately looks like a blow out you can see how it the inside opening is smaller then the outside of the pipe much like anything as I t passes through it starts off small and blows out more on the way out. I would have to say you have more pressure then you have cuts to alow water to escape. I see you used 1 1/2 pipe at 330 psi . Jumping up to 2 inch will help some but not drastically id cut some more slots in NEW pipe it wouldn't be the f I rst time I saw weak pipe. I dont know where you got yours but I do prefer HD over lowes. And if you really want to avoid future issues use scedule 80 the grey stuff. Its a bit over kill but it is much stronger . And I would use 2 inch slots facing down so rock doesn't clog the pipe.

 

[GBBUDD]

dwv technicaly is generally the very thin weak pipe you see under the sink. Or piping in a camper or boat