# Attn plumbers - Sewer gas problem



## Al33 (Jun 19, 2011)

My home sits on ground a bit higher than a sewer main located in my front yard which services a huge apartment complex nearby as well as my own home. Several years ago I had a new line installed and added a back flow vent to stop the odors which were coming from the manhole up my own pipes and out of the vent pipes on my roof. This helped considerably but did not completely eliminate the odors which are most prevalent on the weekends and late evenings when the tenants are home. Lately it has gotten a lot worse and I am just not sure how to remedy it. The trap has two different access pipes about 2 feet apart both having screw caps for access. I can unscrew them and flush with a water hose but not sure if this will help or if there is a better way.

Any suggestions and all advice MUCH appreciated!!!!! I will supply my phone number in a PM if you would rather talk than type. Thanks!!


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## Jim P (Jun 19, 2011)

check all your P-traps in your home to make sure there is water in them, and if you can check your vents to make sure they are not clogged with leaves etc.


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## shakey gizzard (Jun 19, 2011)

Jim P said:


> check all your P-traps in your home to make sure there is water in them, and if you can check your vents to make sure they are not clogged with leaves etc.



Yepps!


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## Al33 (Jun 20, 2011)

If I am using all fixtures such as sinks, shower, and toilet, wouldn't the P traps automatically fill? How do I check to make sure they are filled with water?

 I recently had my bath and kitchen remodeled replacing all fixtures. I had to install the newer water saving toilet and I suspect it doesn't use enough water to expel the wastes past the gas vent valve without leaving it partially open thus allowing the gases from the main to come back into my pipes. However, it seems to me the water used from showering would be enough to flush the entire system, but then again I'm not a plumber.

I have tried to research the gas prevention valve hoping to find a diagram of one to see just how it works but to no avail. I was hopeful I could figure out a way to flush or wash the valve just in case it is not closing completely. The gas prevention valve the contractors installed is located about 80 feet from the house and about 20 feet from the manhole.

Thanks for the replies!!


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## Lukikus2 (Jun 20, 2011)

Couple of questions
Do you smell it strong in the house or outside the house?
Do you smell it stronger in one room than the other?
The "gas prevention valve, is it an actual valve/fitting?

There are a couple of scenarios which could cause this. The valve they put in is probably a "backwater valve" which opens when your water flushes thru and closes as the stream stops. These are not made for "waste" lines as solids such as paper will hinder them from closing. Flushing from both sides will clear some of this up if in fact it is a valve. Normally we would put a "running trap" in the line with nothing to impede the flow but giving you a whole house trap.
Secondly, look under all your lavatories and sinks and see if you have a "studor vent" installed under them. These are used for under counter venting where tying the vent back into the wall is not possible. These will let gas escape under the counter and still give you good drainage at the fixture. There are better ones on the market today that let air in but keeps the gas at a minimum, they may need to be changed.


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## Hooty Hoot (Jun 20, 2011)

I was going to suggest checking any studor vents. You might also check the seal on that new toilet.


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## Al33 (Jun 20, 2011)

Lukikus2 said:


> Couple of questions
> Do you smell it strong in the house or outside the house?
> Outside
> Do you smell it stronger in one room than the other?
> ...



Thank you all very much for taking the time to reply. This morning I removed the cap from one of the two access pipes (one on my side of the trap) leading to the valve which may indeed only be a back flow valve. I not only used my water hose on jet stream to shoot down the pipe but I also filled a 5 gal. bucket with water and poured the water into the pipe as fast as I could pour it hopefully to clear anything that may be holding the valve open. I will find out this evening if it has helped at all. I did smell gases on my side of the valve when I removed the plug.


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## Lukikus2 (Jun 20, 2011)

Sending PM


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## Jim P (Jun 20, 2011)

I'm a old time plumber and never liked studor vents, even before I retired I would never use one because of the reason stated above. Was a plumbing inspecter for 16 1/2 years and seen problems with the studr vent many a time sewer gas is nothing to play with can be deadly.


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## Al33 (Jun 20, 2011)

Thanks for the PM and help Lukikus2!!!

Looks my only option is to put a carbon filtered pipe vent cover on my existing roof vent pipe. If that will eliminate or significantly decrease the odors it will be well worth the costs and trouble.

Thank you all very much for your time and advice!!!


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## simpleman30 (Jun 20, 2011)

this is an interesting problem.  i have a hard time believing you would be able to smell the odor coming out of your roof vent at ground level.  the amount of odor a sewer system puts out dissipates within a few feet of a vent.  even an open sanitary sewer manhole cannot be smelled unless you're directly downwind and within a few feet of it.  i've been doing plumbing for 10 years and have never heard of excessive amounts of sewer gas from a roof vent causing odor at or near ground level.  i mentioned this to my dad, who has been a plumber for 35 years and this is a new one for him as well.  

this sounds silly, but i would seriously verify 2 things:

1) make sure there actually are p-traps on your bathtubs/showers.  if you have a crawlspace, take a look.  if you have a slab, it will be a bit tougher to verify.  i have seen a few do-it-yourself'ers and who-dunit plumbing companies plumb their own houses and leave out p-traps on the tubs, showers, and even under the sinks.    

2) make sure there isn't an open vent or a vent in the attic that isn't tied in.

a master-trap on the main line would prevent ANY sewer gas from coming up your line.  a master-trap is against code but it would solve your problem.

are you smelling the gas inside the house, outside, or both?

and finally, how close do you live to the sewage treatment plant?


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## Lukikus2 (Jun 20, 2011)

simpleman30 said:


> this is an interesting problem.  i have a hard time believing you would be able to smell the odor coming out of your roof vent at ground level.  the amount of odor a sewer system puts out dissipates within a few feet of a vent.  even an open sanitary sewer manhole cannot be smelled unless you're directly downwind and within a few feet of it.  i've been doing plumbing for 10 years and have never heard of excessive amounts of sewer gas from a roof vent causing odor at or near ground level.  i mentioned this to my dad, who has been a plumber for 35 years and this is a new one for him as well.
> 
> this sounds silly, but i would seriously verify 2 things:
> 
> ...



He only smells it from the outside on the weekends when the complex that is tied into the same manhole is at it's peak usage level. I will agree with you on the fact that it seems odd the odor is so strong at his house. What is happening is when the complex hits peak load they are dumping huge amounts of waste which the manhole can't aereate, in turn pushing the gas thru his vents. We strayed away from the master trap because of blockage problems and maintanence problems. He has also already extended his vents farther above the roof with no relief. These are the vent filters I found that may be the only correction for his problem, although not inexpensive.

http://industrialodorcontrol.com/CTGY/Low-Flow-Passive-and-Residential-Odor-Filters.html


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## simpleman30 (Jun 20, 2011)

i gotcha.  learn something new everyday!


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## Ta-ton-ka chips (Jun 21, 2011)

Lukikus2 said:


> He only smells it from the outside on the weekends when the complex that is tied into the same manhole is at it's peak usage level. I will agree with you on the fact that it seems odd the odor is so strong at his house. What is happening is when the complex hits peak load they are dumping huge amounts of waste which the manhole can't aereate, in turn pushing the gas thru his vents. We strayed away from the master trap because of blockage problems and maintanence problems. He has also already extended his vents farther above the roof with no relief. These are the vent filters I found that may be the only correction for his problem, although not inexpensive.
> 
> http://industrialodorcontrol.com/CTGY/Low-Flow-Passive-and-Residential-Odor-Filters.html



What's the "rule of thumb" for the vent stack?
Could the vent stack be cut inside the attic, run horizontally for 10' and pushed through the roof on the opposite side of the house? Might give the odor more time to dissipate.


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## Al33 (Jun 21, 2011)

simpleman30 said:


> 1) make sure there actually are p-traps on your bathtubs/showers.
> 
> I have an extremely narrow crawl space under the bathroom but can at least crawl close enough to take a look there and at all other plumbing. If I find I am missing a P trap there it will a booger trying to put one in with only about a foot of space between the floor and the ground below.
> 
> ...



Prior to having the trap/valve installed in the yard about 5 years ago I had odors coming through my shower drain. I have also had to have the county come out and seal the lid on the manhole twice because of odors coming from it. The first seal worked on that part of the problem until they removed the lid and replaced it without sealing it thus the reason for the second seal.
The apartment complex is HUGE with 350+ units covering 66 acres so as you can imagine the manhole that services it gets a lot of business (no pun intended) during the evenings and on weekends when I experience the odors.

BTW, my flushing the valve did not solve the problem.


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## Lukikus2 (Jun 22, 2011)

Ta-ton-ka chips said:


> What's the "rule of thumb" for the vent stack?
> Could the vent stack be cut inside the attic, run horizontally for 10' and pushed through the roof on the opposite side of the house? Might give the odor more time to dissipate.



Yes, as long as it is ran at a slight incline horizontally. 1/8" per foot minimal. (The bubble touching the line)


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## Lukikus2 (Jun 22, 2011)

Al33 said:


> Prior to having the trap/valve installed in the yard about 5 years ago I had odors coming through my shower drain. I have also had to have the county come out and seal the lid on the manhole twice because of odors coming from it. The first seal worked on that part of the problem until they removed the lid and replaced it without sealing it thus the reason for the second seal.
> The apartment complex is HUGE with 350+ units covering 66 acres so as you can imagine the manhole that services it gets a lot of business (no pun intended) during the evenings and on weekends when I experience the odors.
> 
> BTW, my flushing the valve did not solve the problem.



The valve is for clearwater waste only, it only stops water from backing into your line, not sewer gases. I've been pondering your problem all weekend.



> 350+ units


 Wow. They should have been on a dedicated manhole. The only "real" fix for the problem I can think of is to have your sewer line tied in downstream of the manhole. Engineers don't think of these things sometimes. Your house is actually acting as a vent for the manhole.
The shower drain has a p-trap, correct? Pour some bleach down it every so often when you smell it. Other than that depending on how much gas is pushing thru your lines you could get a little "burp" in it. 

Are you going to buy the vent filters?

 What do you think Simpleman?


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## simpleman30 (Jun 22, 2011)

regarding the backwater valve, you are correct.  it is designed to keep backups from occurring but not keeping sewer gases out.  we've got about 30 of them on a job we're doing at Jekyll Island right now for the floor drains at each entry door to the new convention center. 

i agree that his house may be venting the manhole.  after talking with my dad, he said that this is sometimes a problem with apartment complexes.  i've asked around our office and no one else has had firsthand experience with this problem, though a few folks here have heard of it occurring in multi-family housing.  most of the projects i deal with are new commercial buildings that tie in to new manholes or lift stations that then run to a city main.  

i think tying into the main downstream of the manhole would be a first step in trying to alleviate this problem.  if you can do it yourself over a weekend, that's what i'd do.  but then again, if the city sees you messing with a main, they may want to see a permit.  the vent filters are probably going to be the least amount of trouble, but i'm sure periodic maintenance or replacement will be required.


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## Lukikus2 (Jun 22, 2011)

Simpleman30,
   I don't think you want him tying in to a "live" main on the weekend. Me or you wouldn't want to do that
 He could put a test ball in the complex main in the manhole BUT who would he get to pull it out? Not me!

I'm mostly commercial also but with a little too much residential experience if you know what I mean.

Thanks for your input. This is certainly new for me also.


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## Ta-ton-ka chips (Jun 22, 2011)

Lukikus2 said:


> Simpleman30,
> I don't think you want him tying in to a "live" main on the weekend. Me or you wouldn't want to do that
> He could put a test ball in the complex main in the manhole BUT who would he get to pull it out? Not me!
> 
> ...



Sounds like a nightime job for someone sneaky. Backhoes are a lot of fun 

Be a couple of weeks before anyone I know could get to it.


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## injun joe (Jun 23, 2011)

Al, how far is your house from the offending manhole? Would it be possible to install a relief vent between the manhole and your house?
If you have a 4" building sewer and installed a full size (4") vent, it might be possible to relieve the vent gases from the manhole without them getting to your house.


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## Jim P (Jun 24, 2011)

This is a health problem, get in touch with the health dept. they might recommend to the city or county to fix the proplem


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## Ta-ton-ka chips (Jun 28, 2011)

injun joe said:


> Al, how far is your house from the offending manhole? Would it be possible to install a relief vent between the manhole and your house?
> If you have a 4" building sewer and installed a full size (4") vent, it might be possible to relieve the vent gases from the manhole without them getting to your house.



He's about 30 yds. I believe he had relief vents installed adjacent to the manhole about 2 years ago.
This problem is serious but ya'll know how Govt works.


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## Wild Turkey (Jun 28, 2011)

I have a stinking suspicion that the manhole is loading up during peak flow due to either a pipe restriction or inadequate size. When it finally drains down the suction splurps your pipe dry and possibly sucks your underhouse traps dry. Could also be standing sewage in the manhole gone septic and stinking up the place. 
The city needs to get involved via the health dept and figure it out.
Complain to both health dept and public works.


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