Nasty drain smell

[Jocelyn]

A while ago I posted about a revolting smell wafting into our house from the back yard. We have found it to be getting worse.

I phoned the water board this morning and two chaps called around mid-day. No smell of course ! At first they said it was our drains, then they said the vent pipe was blocked( which it was with a piece of plastic bag stuck underneath the cover at the top which we had not noticed), then they poured disinfectant down our drains and prepared to leave.

After mentioning to them that there has to be something wrong since the smell and sound of running water under one of our manholes is at regular intervals during the day, they suddenly woke up and showed me a tracking device on the computer in their van. This revealed an active pumping station from a nearby local tourist attraction. Apparently the pumping station pumps away foul water at intervals and the sound of running water that I hear is an echo, and the smell, they then admitted, was because the foul water in that area is not treated the smell is wafting its way along our property as it passes by to the collecting point.

I am prepared to believe that our now unblocked vent pipe might blow the smell away when the weather conditions are right, and I also think they maybe right when they said our vent pipe should be much higher to clear the closed in areas and windows opposite and around us, but I am not convinced that is the end of the matter.

Giving them the benefit of doubt I shall wait a while and see what happens,

but: how come foul water from a heavily used tourist attraction can be pumped around the village untreated in this day and age?

Do I just wait or are they messing me about because it will be too difficult to treat the water in that particular area?

Presumably I have to get building regs and LBC to raise the height of the vent pipe.

Needless to say 10 minutes after they left there was a really strong blast of pong.

Jocelyn

 

[Lime]

Well all the advice is good sound guesswork but guesswork it still is.
You need to find out exactly where the smell is coming from.
Only then will you be sure of what the problem is so that a solution can be found (hopefully).

The plastic over the pipe suggests that others have tried to stop the smell but until you know exactly where the smell comes from you are only guessing.
The advice to extend the vent pipe above the level of windows etc is correct. The higher the pipe is from the house openings the better. However the logic of the plastic on the pipe causing the pipe to smell doesn't make sense. If the pipe was blocked the smell would not come from it, would it?

 

[GK]

How much are you going to raise the vent pipe by? Don't think you would need any consents to raise it,really. The "official" height I think is 900mm above any opening windows within a certain distance.

Here's a thought: If the niff is coming from the main sewer further down the line, and the previous occupier tried to stop it with a plastic bag, why not fit a durgo valve instead of an open vent? I don't think they're meant to be used outside, I think they can freeze up and stop working, but the theory is they allow your drains to draw air in but won't allow it to escape.

Then change your outside manhole cover for an airtight one -maybe that's where the smell is coming in, around the lid. Hence plastic bag didn't work.

 

[Nemesis]

With regard to untreated sewage being pumped around... presumably it's being pumped to the sewage works? I assume that there is mains drainage for the village. In that case everyone's sewage will surely be flowing around until it reaches the treatment works?

I assume the visitor attraction collects it in a holding tank and it has to be pumped as maybe the geogrpahy of the place doesn't allow for gravity flow.

 

[Lime]

To follow on from my last post, the smell may be coming from anywhere.
During the 70s many roadside drains were installed without U-bends so air from the sewer blows straight out into the street.
Similarly at about this time household manhole intercepter traps were discontinued so air from the sewer can enter your own pipes and escape out of any fault or opening. That can happen in a neighbouring houses too.
Unless you find out for certain from where the smell is escaping you will be wasting time and money repairing "faults" that aren't actually causing any problem.



Sewage pumping stations cause problems because they pump sewage about intermittently so that any air trapped over the sewage or in the pump receptacle is pushed out while the sewage fills the holding sewers.
Similarly when downstream of a pumping station (as you say you are) when the pumps start the outgoing sewage pushes air out of the receiving sewer.

 

[Penners]

Jocelyn

I like GK's idea of a durgo valve to replace the vent (otherwise known as an air admittance valve). As he says, this will allow air to be drawn into the sewer, but won't allow it out. The freezing risk could probably be solved by boxing it in with lots of insulation (provided this doesn't stifle the air flow to the valve).

If you want to see whether an airtight manhole cover would help (and it probably would) you could experiment by generously greasing the groove in the rim that your current manhole cover sits in. Provided (a) the rim is well sealed in with cement, and (b) there are no holes in the cover itself, this should give a fair idea of whether an airtight cover will hold in the pong.

Good luck!
David

 

[Jocelyn]

Thank you all for your help. I will look into a durgo device.
All the comments about the sewerage are applicable to this area, so, as you rightly point out it is difficult to pinpoint the culprit, although the Water Board did specifically mention the tourist attraction area.

Two manholes, near our roadside gate are firmly closed down with earth and they did advise me not to disturb those, so I will check the other three.

The smell was evident this morning, but it did not seem to linger so long and neither was it quite so pungent, so opening up the top of the vent pipe must have helped a bit.

I'll 'keep truckin' and keep you posted.

Jocelyn