<http://schema.org/articleBody>
" The flood that hit my hometown of Montpelier, Vt., 14 years ago this March, had a sneaky feel to it. The water didn&amp;#039;t come from up the Winooski River, which skirts our downtown; it backpooled quietly into the streets. Spring snowmelt and steady rain had swollen the river to near its banks, breaking its thick ice cover into truck-size chunks that formed a clog in a bend just below town. Within minutes, shopkeepers noticed water sliding across their floors. Eventually, ice cakes floated along the streets. Basement windows imploded. Propane tanks tore loose and drifted around, spewing gas. In basements throughout the business district, inventory ranging from bicycles to electric guitars sat immersed in slush. A crane and excavators broke up the jam that night, but when the water finally receded it took 650 dump-truck runs to clean up the mess. Sixty-two New England towns suffered from ice jams that week, but none more than ours. &amp;quot;Not,&amp;quot; one store owner told me, &amp;quot;something I&amp;#039;d want to do again.&amp;quot; Unfortunately, ice jams are a chronic problem. In the past 25 years, they have caused serious destruction in a half-dozen U.S. cities, from Montpelier to Salmon, Idaho, and have sent smaller floods backing into towns in 36 states--resulting in $125 million in damage annually. This may seem minor compared to the $5 billion in damage a single hurricane can inflict, but for the tiny northern towns that ice jams most often affect, it can be calamitous. Along with trashing businesses and homes, the flooding damages hydropower plants and in 1996 even forced a nuclear power plant to temporarily shut down. Some high-value facilities protect themselves with dams or boom systems, but such structures are often too pricey for small municipalities--leaving residents with no real defense. WALTON, NY/1996 DELAWARE RIVER $700 MILLION CANTON, ME/2003 ANDROSCOGGIN RIVER $2.9 MILLION HERKIMER, NY/1996 MOHAWK RIVER $2.8 MILLION LITTLE FALLS, NY/1996 MOHAWK RIVER $1.25 MILLION MCKEESPORT, PA/2001 YOUGHIOGHENY RIVER $1 MILLION SIMPLE FIX This winter, West Seneca, a suburb of Buffalo, N.Y., installed a new type of ice-control structure on Cazenovia Creek. This tributary of the Buffalo River jams every few years, causing about $1 million of damage each time. &amp;quot;These jams have been a nasty little problem,&amp;quot; says town supervisor Paul T. Clark. At $2.1 million, the standard solution--a dam with piers designed by the Army Corps of Engineers--just wasn&amp;#039;t feasible when the town considered it back in 1987. Recently, the Corps&amp;#039; Cold Regions Research and Engineering Laboratory (CRREL) in Hanover, N.H., came up with another design. The new pier structure consists of a line of nine concrete columns--each 10 ft. tall and 5 ft. in diameter--set across the creekbed at 12-ft. intervals. Like a dam with piers, this rakelike configuration catches and holds the biggest slabs of ice, forming a jam upstream of town where it will do no harm. By the time the ice melts enough to pass between the columns, it is too small to form significant jams. But the pier-only design differs in one significant way: The base of each column is flush with the creekbed--embedded in a concrete substructure as opposed to set in a low dam--allowing fish, stream flow and warmer-weather boat traffic to remain essentially unaltered. On Cazenovia Creek, the structure also makes use of a wooded floodplain that helps trap ice while letting water escape downstream. &amp;quot;It&amp;#039;s part dam and part valve,&amp;quot; says CRREL&amp;#039;s Kate White, who has been designing ice-control structures for 18 years. &amp;quot;This is the new breed. Older models have weirs and gates and cost many millions. This one goes in more easily, requires very little maintenance and is much cheaper than the previous design.&amp;quot; The Corps of Engineers is not renowned for doing things simply and cheaply. &amp;quot;This is a new way of thinking,&amp;quot; White says. &amp;quot;We realized we don&amp;#039;t have to completely subjugate the river. If we just hold back most of the ice, we get the same protection more economically.&amp;quot; The key, White says, lies in using the correct number of columns. Build too few and the ice escapes; build too many and the cost climbs. To find this magic number, CRREL engineers use a computer program to create a virtual version of a particular river and model the various alternatives. They test the most promising designs on a 1:15-scale physical model in a refrigerated room at their laboratory--a reshapeable &amp;quot;riverbed&amp;quot; complete with chunks of floating ice. STRONG SELL At Cazenovia Creek, the full-scale pier structure took several months to install, primarily because heavy fall rains kept washing out the access road. The crew tackled half the job at a time, building temporary dams to channel the water to one side of the creekbed while working on the other, replacing the shale bottom with a heavily reinforced concrete slab and pouring concrete into steel forms to create the row of columns. Once set, the piers made a sturdy-looking line of soldiers. Yet, I&amp;#039;d seen what ice did in Montpelier. It tore a steel railroad bridge off its abutments and turned it 90 degrees. &amp;quot;An ice jam backed by a river generates a lot of force,&amp;quot; Corps civil engineer Dustin Tellinghuisen says. CRREL designed the piers to withstand up to 450,000 pounds--a force equal to the static thrust of two 747s at full throttle, and a lot more than would be exerted by the biggest ice jams at record flows. Arm-thick, post-tensioned braided cables run integrally through each pier, anchoring them 38 ft. into the bedrock. &amp;quot;So what do you suppose could move these things?&amp;quot; I asked. He considered my question for a moment. &amp;quot;I&amp;#039;m glad to say I can&amp;#039;t think of anything.&amp;quot; Business owners in West Seneca look forward to seeing for themselves that the engineering project was money well spent. Adjusted for inflation, its construction cost amounted to slightly more than half that of the older design. With federal and state cost-sharing programs, the town ended up spending less than $500,000. &amp;quot;That was a pretty easy sell,&amp;quot; Clark says of the pier structure. &amp;quot;We&amp;#039;ve been stung enough.&amp;quot; "^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.popularmechanics.com/science/environment/a473/2272511/>