I've been on uer for a while now but this is a rookie worthy question so i'll post in the rookie forum.

In my town I've explored a few drains but haven't been able to find an outflow to get in that seems worthy of the whole downtown. This has been bugging me all summer and into the school year. I'll look through grills on the sidewalk and see rather large rooms underneath that seem to be for storm drains but there is no way to get to them. I've searched for maps of the storm drain systems but have not had much success in finding anything. What I'm wondering is how big or small does the outflow have to be to know its a decent system. Also what do sewer outflows look like so I can avoid going in them without proper equipment. Also if any experienced drainers have any helpful advice they'd be willing to share it would be greatly appreciated.
cheers, mullet

Posted by mulletcat I've been on uer for a while now but this is a rookie worthy question so i'll post in the rookie forum. In my town I've explored a few drains but haven't been able to find an outflow to get in that seems worthy of the whole downtown. This has been bugging me all summer and into the school year. I'll look through grills on the sidewalk and see rather large rooms underneath that seem to be for storm drains but there is no way to get to them. I've searched for maps of the storm drain systems but have not had much success in finding anything. What I'm wondering is how big or small does the outflow have to be to know its a decent system. Also what do sewer outflows look like so I can avoid going in them without proper equipment. Also if any experienced drainers have any helpful advice they'd be willing to share it would be greatly appreciated. cheers, mullet

I don't know your systems well enough to answer all of your questions with accuracy. But sometimes it does take just popping manholes. Remember...we're explorers.

As far as sewer outfalls go...most of them don't go into any major bodies of water because that's illegal in the civilized world due to pollution. As far as the manhole popping goes it would likely tell you on the cover.

Knowing if the system is worth going in...simply requires checking it out...

Now, I don't have much draining experience compared to some people on this site, but I can give you some tips that might help.

First off, outflows, as stated above, rarely drain into large bodies of water. Not that it's unheard of- just rare. Try looking in ditches or on hill sides. If it is on a hill side, there will usually by a large quantity of rocks below the outflow to prevent erosion. These are not uncommon near highways.

The outflow may be small, and widen out as it goes deeper. This is not uncommon, in my admittedly limited experience. These outflows may be tucked out of the way. Marshy areas tend to be an indicator of their presence, though mud, quicksand, and flooding are all dangers in a marshy area.

Lastly, your city should have a map of the storm drain system for maintenance, land surveying, and regulation purposes. This may be available online, but odds are it's not due to security issues. However, you may be able to request a copy from your local government. This map will show you everything you want to know.

Best of luck.

I think there may have been some misinterpretation above, but typically stormwater outfalls DO drain into existing bodies of water like rivers. It is sewer ones that you will rarely find dumping out into public but rather flowing into a treatment plant.

The easiest way to find an outfall is going to be along a river's bank adjacent or slightly downstream of a populated area. Simply walk along the bank or take a small boat and look.

All this information could vary slightly depending on your city's infrastructure but outfalls generally consist of a concrete or corrugated pipe just sticking out of the side of a riverbank. A lot of times they will be recessed in a small ravine with large chunks of rock to slow the water before entering a river. The larger the diameter of the pipe, the larger the volume of water it was designed to transport. Larger pipes will be more worthwhile to explore (as well as easier) because they probably have a more expansive series of tunnels behind them.

The outfall pipe will almost always be the largest diameter pipe in the system so if you start there, be prepared to only encounter smaller and smaller pipes as you travel "upstream" in the system. Especially if you are new to draining, I would suggest ONLY starting at the outfall and working your way in so you know which way is out and can judge the safety of the definitive exit. Safety can be as simple as whether or not there is a 5m drop at the outfall or if it has a constant or dangerous flow of water.

Pipes that have running water during dry weather indicate that they are actually holding a urbanized stream or creek. Alternatively it could be sewage. You should notice pretty quick what the case is.

Your profile says you are in the UK and wanting to get into "downtown". I would be extra careful with older and larger cities. Their drain systems can be old and convoluted. In addition older cities have more "mixed"/"combined sewer overflow" where sewage can mix into regular stormwater pipes. Even in dry weather it is possible to encounter sewage in these pipes.

This only scratches the surface of beginners draining. It is all pretty intuitive but can be fairly dangerous if something goes wrong. Best of luck.

With a few notable exceptions, the outfall of a storm sewer is most always going to be it's largest area - what you see at the end is probably as good / big as it's going to get. I have seen drains change profile and get larger midway, but it's rare and usually just for short stretches before shrinking back down. It's always the result of a repair / retrofit, as changing diameter midway is poor design and likely to encourage a decrease in velocity and turbulence which will induce premature localized wear. They're the exception, not the rule.

I'm not familiar with any drains in Peterborough, but it's a smaller town, and not likely to have the same scope of infrastructure as a larger city like Toronto, Montreal, etc... It's also a new city, so you're likely to encounter concrete, not brick.

Anything with an outfall is going to be 100% stormwater, or possibly CSO, although in a modern city like Peterborough I'm almost entirely certain that storm and sewage are separate systems.

I do recall someone (maybe even you?) posting a photo of a storage tank in peterborough...chances are good it's an overflow tank with a connection to an active sewer somewhere along its perimeter. It could be a small pipe, or it could be large enough to walk in. That could be an interesting thing to explore, although be *extremely* cautious around an active sewer as they're usually fast-flowing, deep and quite slippery. A fall in a sewer could be your last.

Sorry if that's kind of a rambling list of different shit...hopefully it answers some of your questions but shoot me a PM if it didn't and I'll be happy to discuss further