Drains - a disclaimer of sorts

Draining: the exploration of underground man-made drainage systems.

To write a 'guide to draining' would take way longer than the time I have available at present, so until I do have the time here's something in way of a disclaimer and some common sense bits of information for those who are considering venturing in to drains. Firstly, if you're even slightly contemplating exploring drains and you also value your life then please take the time to thoroughly read Predator's Approach Doc. Digesting all the info therein will not certify you drain savy howere! The .doc is written with Australian drains in mind, though much of the info is transferable, and although it is quite some years old now it is still the most comprehensive guide of it's kind available online.

When it comes to drain exploring there are a couple of facts that are frequently overlooked, the first is particularly obvious you'd think. "Drains are not derelict buildings", drains of any nature are not significantly comparable environments to derelict buildings and so experience of exploring derelict buildings does not equate to experience in drains. The common sense approach that often comes from experience of exploring derelict buildings will serve you well in drains however. The second overlooked item is slightly less obvious and should be equally as heeded, if not more so! "99% of drains are active/operational locations". In an environment that is largely automated and still functioning to fulfil its purpose the presence of explorers is not something that is factored into operational procedures. In short there are many potentially life threatening dangers in drains that are entirely outside of your control and outside an explorers ability to reasonably calculate for, complacency is never an option!

In way of a little education and to keep things n00b friendly let's very briefly break UK draining down into its rudimentary groupings, there are roughly three degrees of seperation when it comes to 'explorable' drains:

1. Culverts/Underground Watercourses.

Where a formerly aboveground watercourse has been channelled underground through a conduit, most often in order to make use of the newly created land above. Quite often surface water draininage from the newly created land above will be connected to the culvert, giving it a secondary function of draining surface water run-off, but primarily it exists to convey the watercourse underground. By its nature a culvert will feature an infall (upstream) and outfall (downstream) structure, depending upon its length it may also feature manhole access shafts along its underground course. It is not uncommon for Combined Sewers(see below) in close proximity to a culvert to have an overflow within the culvert, conveniently out of the gaze of the general public. These Combined Sewer Overflows(CSO) allow an amount of flow from the sewer to discharge into the culverted watercourse during times of excessive rainfall, usually via a screened overflow set-up, to avoid the sewer becoming surcharged. Culverts are often mistakingly considered to be at the more recreational end of the draining spectrum, the risks in culverts are as plentiful as in any other underground drainage system and they should be approached with the exact same caution.

2. Storm Drains / Storm Storage Tanks / Storm Storage Tunnels.

Of course the name proclaims the function of these three common methods used to deal with sudden increases in water volumes due to excessive rainfall. The name should also sound alarm bells to anyone considering exploring such a location, these places exists solely to channel or store huge volumes of water! These three variations on storm flow handling are not exclusive of one another. The term 'storm flow' for the purpose of this post covers overflow from combined sewer systems and the surface water run-off of seperate systems. Storm Drains come in two basic flavours and both exist solely to deal with excessive flow during high rainfall conditions, thus during dry-weather conditions they will have little to no content.

Flavour number one is the Storm Relief Sewer, aka Storm Reliefs and Storm Sewers, in conjunction with a Combined Sewer System(see below) the Storm Relief Sewer provides extra capacity during storm conditions. A Storm Relief Sewer deals with its content by one, or all three, of the following: conveying the flow to a storage tank/tunnel(see below) from where it will be later pumped back into the system; channelling its flow back into the combined system at a point where it has a greater capacity; having an overflow outfall (CSO) on a local watercourse. It's not uncommon for a Storm Relief Sewer to employ all three methods in that order of precedence.

Flavour number two is the Storm Water Drain, sometimes confusingly referred to as just Storm Drains and Storm Sewers, these are essentially a system of underground pipes whos collective function is to take only storm water run-off enabling it to be discharged directly into local watercourses with no adverse effect. Storm Relief Sewers and Storm Water Drains are usually contained systems, only being accessible via manholes or other similar access portals. Of course Storm Water Drains may feature an outfall structure but most are secured to restrict access, effectively maintaining its contained status. A contained system is often considered to bring with it an increased risk of air quality issues due to reduced air flow/ventilation, this can be further compounded in some Storm Drains by the presence of decaying organic matter in standing water deposited during the last storm event. There is a school of thought that suggests a contained system presents an increased risk of drowning in the event of a storm surge event, being as there is no outfall to we washed to. In reality the increased risk is minimal as the chances of being washed any distance to an outfall in an open system without sustaining major injury or loosing your life is slim.

Storm Storage Tanks would normally be used on a Combined Sewer System(see below) to provide increased capacity during higher than average rainfall conditions, to prevent overflows into local watercourses, which would normally be a last resort. They come in all manner of shapes, sizes and configurations both vertical and horizontal. They may exist along the line of a Storm Relief Sewer, but could equally be an isolated storage tank or series of tanks joined to the Combined Sewer System via an overflow weir. Once the combined sewer levels have receeded post-rainfall the storage tank(s) content is pumped back into the system at a regulated rate.

Storm Storage Tunnels are the natural progression from storage tanks where an even greater storage capacity is required and storage tanks of the equivalent capacity would not be financially viable or would be plain unacheivable. As with storage tanks they may be connected to a Storm Relief Sewer or may be connected directly to the Combined Sewer System via an overflow.

3. Combined Sewers.
Considered by many to be a much more inhospitable exploration environment largely due to the increased risks stemming from the greater levels of bacterial contamination and the prescence of decaying organic matter resulting in potential air quality issues. The Combined Sewer System is exactly as its name suggests, a drainage system built to deal with a combined flow comprised of:

Surface Water Run-off - street level rainwater drainage.
Foul Water(Brown/Black Water) - wastewater with a high concentration of biological (fecal matter and urine) or chemical contamination, both domestic and industrial.
Grey Water - wastewater with a low concentration of biological or chemical contamination, generated from processes such as washing up and bathing.

Combined Sewers, like Storm Drains, are contained systems that do not have an infall or outfall. Small conduits feed from households, businesses and street drains into increasingly larger pipes conveying the flow to a treatment works where the contaminants are removed rendering the resulting liquids and solids suitable for discharge to the environment or re-use.

The risks of drain exploration are many and are often entirely outside of an explorers control. Many people who explore drains do so with the assistance of specialised safety kit, from Gas Monitors and Emergency Breathing Apparatus to Intrinsically safe lighting. Sticking on a pair of wellington boots, grabbing your maglite and heading into a drain for the first time is a recipe for disaster. If you're determined to explore drains then find someone local to you with a good grounding in drain/underground exploration to go along with.

Ultimately the decision to explore drains lies firmly with each individual and with that decision comes responsibility for yourself and your actions, only you can make that call and only you are responsible!