The annoying thing about water in Saskatchewan is that we never seem to have just the right amount. There’s either too little or, more rarely, too much. This time of the year, as the snow melts, it’s usually the latter.
While a lack of water is bad, a surfeit of water is often worse, as anyone who has returned home from a summer vacation to find his barcalounger floating in the basement can tell you. In order to get rid of excess water, we turn to the ancient and honorable art of drainage: “Removal of surface or subsurface water from a given area by natural or artificial means,” as my encyclopedia puts it.
The Aztecs and many other ancient civilizations practiced drainage on a huge scale, cutting networks of ditches to drain wetlands for agricultural use. The ancient Romans were especially big on drainage: some of their storm sewers are still in use. The Romans also began draining the Pontine Marshes, a project Mussolini completed which converted 70,000 hectares of swamp to farmland.
Probably the most famous drainage project of all time began about 1000 A.D.: it gave us an entire country, the Netherlands.
Wetlands form either where surface water collects faster than it can be absorbed, or in places where the water table is almost as high as the land surface. Not all rural drainage is on the scale of the Pontine Marshes: on individual farms, drainage can free up arable land and prevent erosion by removing water before it starts flowing down slopes and cutting gullies. Good drainage can also help prevent the formation of those tell-tale white, barren patches of accumulated salts you often see in Saskatchewan fields.
Drainage works by providing water with an open, readily accessible channel through which to flow. Water will take the path of least resistance, and it’s a lot easier for it to flow down an open channel than to push its way through the soil, so once you can get it into a pipe or ditch and point it downhill, your problem is solved. (Of course, you may be exacerbating someone else’s problem downstream.)
Open ditches are probably the most common form of rural drainage, but they’re not always satisfactory because they can become plugged with dirt or plant growth. In places where excess water is a problem year-round, underground drains are employed. Pipes made of hollow earthenware or concrete tiles are buried a metre or two underground, well below the reach of the plow. Excess water seeps into these pipes through apertures in the tiles.
Most drainage systems depend on gravity, and thus have to be carefully constructed with the understanding that water always flows downhill. In places that are already at the bottom of the hill, so to speak, like most of the Netherlands, gravity becomes a hindrance rather than a help, and water has to be pumped into streams or canals that are actually higher than the land being drained.
In cities, drainage difficulties are somewhat different. Most of the land in a city is covered with concrete or asphalt, which provides no possibility of standing water seeping into the soil. Water has to be drained away very quickly, or your roads might as well be rivers.
Ancient cities had open ditches running down the middle of their streets. Modern cities have ditches too, only they’re called gutters. Roads are made higher in the middle than on the sides–“crowned”–so that water will run into the gutters. Periodically, there are openings in the gutters that allow the water to flow into “catch basins,” and from there into underground pipes, which feed into larger pipes, which eventually empty into a river. Storm sewer systems are huge, complex affairs. For example, in Regina there are 15,000 catch basins, 700 kilometres of storm-sewer piping, 14.5 kilometres of above-ground storm channels, and 217 outlets where storm-sewer water is discharged into the storm channels or directly into Wascana Creek.
When cities like Paris first realized in the 19th century that it was in the public health interest to quickly remove raw sewage from the premises, they used the storm sewers for that purpose. (The labyrinth the Phantom of the Opera traverses in his boat with Christine is part of the Paris sewer system. If Lloyd-Webber’s musical had included smell in its panoply of special effects, it might not have been such a big hit.) Many older cities still have this kind of “combined” system, in which the same system carries both storm-water and domestic sewage. This has obvious environmental problems (although nobody really thought much about them until the beginning of this century). Most cities today have separate storm-water and domestic sewage systems, because the domestic sewage has to be treated before being released into a river or lake, and the amount of water running through the storm-sewer system after a storm is too large for most treatment plants to handle.
Of course, storm sewers have their own environmental costs: oil and salt from the streets and chemicals applied to urban lawns all get washed into the storm sewer system and eventually end up in a river or lake. Fertilizer from lawns is one reason Regina’s Wascana Lake is so thick with weeds and algae in the summer. The decomposition of all that organic matter under winter’s cover of ice accounts for the strong odor associated with the lake’s spring thaw.
Despite all the efforts of all the city engineers of all time, there are still occasions when Mother Nature is able to overwhelm our drainage systems. When that happens, there’s not much you can do but avoid the Winnipeg Street underpass, put on your galoshes, and console yourself with this thought:
Actually, a floating barcalounger sounds rather comfy.