Street Sweepers – sucking soon on a street near you?

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Posted by Angie Hong | Posted in Keeping water clean | Posted on 01-11-2010

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My husband likes to tell a story about a time he was visiting his grandmother in China when he was young. His grandmother did not speak English and Gary spoke only a little Chinese. One day he begged her for a piece of candy and with a smile she went to the kitchen and started heating up a can of soup. “Candy, candy,” he implored, but she only nodded and turned the heat up a little higher on the stove. It turns out candy and soup sound an awful lot alike in Chinese.

When communicating with others, it is important to use proper grammar, enunciate, and most importantly, select the right words. Unfortunately, many of the words we use in day-to-day conversation have confusing or contradictory meanings. During this week’s Minnesota hurricane, for example, a friend posted on Facebook, “This weather sucks!” “Actually,” corrected another, “It blows. Big time!” The problem isn’t just slang; it’s the English language. Have you ever wondered why you drive on a parkway but park on a driveway?

Around this time of fall, many local cities post signs to close streets for sweeping. The phrase “street sweeping” conjures up an image of a person with a broom, industriously sweeping the roadways and scooping up all the litter and debris into a giant dustpan. When we see a street sweeper rumble by, many people assume that its only function is to blow and wash all the debris off the street so that the roads look nice. It’s true that cities use street sweepers to maintain a tidy appearance, especially in their central business districts. The city of Stillwater, for example, sweeps downtown streets twice a week on Tuesdays and Fridays in the early morning. Most people don’t realize, however, that street sweeping is actually one of the best management practices a city can use to prevent water pollution. They also don’t realize that most street sweepers don’t blow, they suck.

There are three main types of street sweepers. Mechanical broom sweepers are the most common and they operate pretty much like a giant broom and dustpan. A broom spins around and brushes debris off the street and onto a giant conveyor belt that carries the debris into a hopper inside the truck. The mechanical sweepers are good at picking up litter, wet, matted leaves and dirt packed onto the road. Regenerative air sweepers and vacuum sweepers, on the other hand, function like giant vacuum cleaners, sucking dirt and sand off the streets. They are not as good at picking up the big stuff like soggy leaves and fallen branches, but are much better at removing fine sand and silt, which often contains heavy metals, nutrients and hydrocarbons.

Dirt and leaves on city streets are eventually washed into storm drains during fall rainstorms and spring snowmelt. Since the first flush from the snowmelt often happens before stormwater ponds thaw, most of the gunk goes straight to local lakes and rivers without any treatment. Decaying leaves and sediment are high in phosphorus, which causes algal growth in lakes and can decrease oxygen levels in the water, leading to fish kills. Hence, dirty roads today often mean smelly lakes next summer. To combat this problem, many east metro communities like Woodbury sweep their streets twice a year, once in the fall to keep leaves from clogging the storm sewers and once in the spring to remove leftover winter sand.

Unfortunately, there is a limit to how much, and how often, street sweepers suck. The machines are expensive and driving every city street at five miles an hour is a time consuming process. Says Nick Chaves, Assistance Public Works Superintendent for Stillwater, “We try to keep it as clean as we can. But any help we can get from residents or shop owners would be very helpful by picking up any trash they might see in the gutters!” The same is true for leaves in the fall. Even if you live on a street that gets swept each fall, you should still rake the leaves out of the street in front of your own house so that the sweeper is better able to suck up the dirt and sand under the leaves. If you live in a smaller community or township that doesn’t use street sweepers, this is even more important because if you don’t sweep the leaves out of the street, no one else will.

To help keep Minnesota lakes and rivers clean, Freshwater Society is urging citizens to organize community clean-ups in the fall and early spring to clean leaves, branches and trash from their curbs, gutters, boulevards and storm drain grates. You can learn more about this initiative at www.freshwater.org. Meanwhile, to help you keep your vocabulary straight, remember that windstorms blow, street sweepers suck, and polluted lakes and rivers really do stink.

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