Reflections on the Colorado Flood of 2013

by Dominique Gettliffe

One of the first things we consider when locating and designing a new structure in the front range of the Rocky Mountains is the flood map showing a theoretical 100 year flood line, and a second theoretical line for the 500 year flood.  After careful scrutiny of the contour map, we establish positive drainage all around the building by creating swales, french drains and underground drain pipes, conscientiously daylighting those pipes downhill, or using a sump pit and pump for water evacuation. We also study the roof gutters, downspouts, scuppers to ensure they all drain away from the foundations. We are then ready for anything, right?

Until a 1000 year flood comes along, and the unpredictable force of nature takes over,  with furious masses of water rolling down the canyons and reinventing the topography in a matter of hours in complete indifference to all of the human predictions, precautions, and preventive measures which came before. The falling water rips millions of tons of rocks, gravel and sand off the face of the mountains and discharges all this digested debris at the bottom of the slope. Without distinction, that same water buries houses, trees, cars, bridges, and roads under these millions of tons of minerals (in some places more than a full story in thickness). In those drainages the landscape has been transformed by unimaginable forces, and any human resistance seems futile and entirely out of scale.

There are other locations, and milder circumstances, where the course of the water (or mud) is altered by seemingly minute obstacles.  The tires of a car where tree  branches accumulate, a few sand bags, a quickly dug trench or a plugged-up culvert can make the difference between a dry basement or an awful mess in a living room. This is the defensible realm in which we, as designers, also make a difference: the small, attentive precautions we take affect the more benign situations.  But what a welcome difference those precautions make for those whose homes remain dry.

Meanwhile, chastened and humbled, we continue to do our best to avoid those fluctuating and capricious multi-century flood lines, wherever they may be.

[From top to bottom: a camper on top of a Ford pickup, buried in 7+ feet of flood debris; a condemned Boulder home during the flood; camper and truck buried in debris]