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Posted: Tue Aug 19, 2008 9:38 pm
by charleswood
Please excuse what is probably a stupid question from a complete drain-ignoramus, but I would be very grateful if anyone can help me. I am altering paving in my front driveway. About 7 yards from the pavement and 3 yards from my house what appears to be some kind of ancient cast iron venting device is projecting up next to the wall to my neighbour's property. It has a vertical pipe of around 110mm diameter, perhaps 18 inches tall, with an iron box on top the front of which is a grate, and a huge cast iron bracket which was presumably once bolted to the wall. The device is entirely rusted and the box and its grate are broken and various bits of detritus can be seen wedged down in the pipe. My question is simply this: What on earth is it? What is it for? If it is a vent then what is it venting? Do I need it for something? Or can I just cut it off, cap it and pave over it. The reason I ask is that basically it is... well... ugly as hell! It does not appear to connect to my drains - I know these were replaced completely in 1988 and when I hose water into the device the water doesn't appear in the access chambers on my property. The device looks a great deal older than 1988 - I'd guess 1888 might be closer which is when my house was built originally. On the other hand the water seems to go somewhere as I hosed it quite a bit and it showed no signs of filling up with water. I stopped when it occurred to me that perhaps the water was finding its way into my foundations or my neighbours cellar rather than the public sewer! I assume it was once required because something needed venting for some reason, else someone wouldn't have put it there, but while I'm familiar with why vents are needed at the top of domestic soil stacks, etc., I'm not aware of any such external venting device in modern drainage systems and I can't really see why you'd need it in the first place outdoors. Obviously though I'm reluctant to simply block it up and pave over it in case then the drainage for the entire street stops working or something! Any ideas anyone? BTW I could not work out how to attach images to this post but if anyone requires I can send a photo if you contact me at [email]ch@rleswood.com.[/email] Best regards and grateful thanks in advance for any help anyone can give.
Posted: Tue Aug 19, 2008 10:20 pm
by flowjoe
The vent you describe would normally be found adjacent to a manhole or chamber and as you a say they have not been installed for many years. If your system has been replaced it is probably redundant.
HOWEVER i can not guarantee that from where i am sat !
I would excavate at the base and see which way it runs, you could even cap it off below ground level with a bung and see what happens. If the sun doesn`t fall from the sky after a couple of days you will be laughing.
HTH
Posted: Tue Aug 19, 2008 11:03 pm
by Dave_L
flowjoe wrote:If the sun doesn`t fall from the sky after a couple of days you will be laughing.
HTH
hahaha - I love that saying!!!! 
Posted: Wed Aug 20, 2008 3:15 pm
by danensis
As I recall these vents had a mica flap behind the grill, as they were designed to let air in but not let smells out. They were designed to stop water flowing out of an intercept from siphoning all the water out of the trap, and thereby letting smells and rats into the drains. This was, of course, based on the theory that rats can't swim.
Posted: Thu Aug 21, 2008 6:32 pm
by flowjoe
danensis wrote:. This was, of course, based on the theory that rats can't swim.
and that the tea pot lid was still capping the rodding eye, and not lay in the base of the trap 
Posted: Fri Sep 05, 2008 8:30 am
by GB_Groundworks
Dave_L wrote:flowjoe wrote:If the sun doesn`t fall from the sky after a couple of days you will be laughing.
HTH
hahaha - I love that saying!!!!
could someone tell me what this sun thing is? i've heard rumors from the old timers about this big bright ball that used to shine and make us warm and happy haha.
Posted: Fri Sep 05, 2008 1:44 pm
by lutonlagerlout
the dreaded interceptors,i have one on my drive and the rodding eye cover is long gone,same for the metal vent, i thought the vents were to stop a build up of gas in the sewers?
has anyone got a link on the design and thought behind interceptors?
because they make no sense at all to me ???
LLL
Posted: Fri Sep 05, 2008 5:44 pm
by eazybarra man
LLL, My thinking is that the vents are to prevent a build up of gas and also to allow tanks to fill up.
Interseptors are designed in such a way that the outlet pipe is situated towards the bottom of the tank and as oil rises to the top it is retained wiothin the tank.
I will post details of links for you. I dont have the links to hand at the moment
EaZyBarraman
Posted: Fri Sep 05, 2008 6:19 pm
by flowjoe
lutonlagerlout wrote:has anyone got a link on the design and thought behind interceptors?
because they make no sense at all to me ???
LLL
What you are describing easybarra ia a petrol or oil interceptor designed for forcourts, car-parks etc....
LLL, the Bristol Trap or interceptor was installed way back when they believed sewer gases would be the end of us all and to stop rodents. Many authorities woudn`t install them because they actually caused raw sewage to sit in the drainage system local to the property.
I found this excellent website on the subject
http://www.draindomain.com/interceptor%20traps.html ???
Posted: Fri Sep 05, 2008 7:32 pm
by Dave_L
Nice link there Joe, I've learnt something tonight!
Posted: Sat Sep 06, 2008 1:41 am
by lutonlagerlout
a system doomed to failure
LLL
Posted: Sat Sep 06, 2008 6:36 am
by seanandruby
have had to break loads of those out on some jobs, but we are still installing them on some of our projects. complete waste of time in my opinion.