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Newberg's water quality? City says it's good |
By Laurent
Bonczijk,
Newberg Graphic reporter
E-mail Laurent at lbonczijk@eaglenewspapers.com
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Newberg’s water has been
measured, it has been weighed, and it has been found clean.
Every year the city has to provide each customer in Newberg with
the results of Environmental Protection Agency and Department of
Environmental Quality mandated tests, said Howard Hamilton,
operations superintendent for the water and wastewater treatment
plants.
The city measures simple things like turbidity as well as the
complex, such as total trihalomethanes.
Turbidity, or the cloudiness of the water, doesn’t affect its
purity, but it can affect taste and murky water isn’t appealing to
some when it comes out of the tap.
Too much turbidity can become a problem because “bacteria can hide
between the dirt,” said Public Works Director Dan Danicic.
Trihalomethanes, on the other hand, are byproducts created by the
reaction of the chlorine used to sanitize the water and organic
compounds in the water.
The vast majority of the city’s water, 95 percent, comes from a
well field on the south side of the Willamette River. The wells are
drilled to a depth of 80 to 100 feet and draw water from a pocket of
sand and gravel.
Once the hole is drilled a casing ranging from 12 to 20 inches in
diameter is installed. It is topped with a pump to withdraw the
water from the aquifer.
Water emanating from the well field has a high concentration of
iron, so the first thing the city does is add chlorine to
precipitate out the iron. “We only have to treat because of the iron
content,” said Danicic, even though it is not regulated.
The water is then gravity fed through a settling basin and a filter
of anthracite coal and silica sand, at which point a polymer is
added as a filter aide and the remaining iron is removed.
The city then adds sodium hydroxide, a base, to achieve a ph of
7.4. (The water from the wells comes out naturally as a ph of 6.6).
The reason the city adds the base, Hamilton said, is that acidic
water will corrode the older copper and lead pipes found in some
homes. To prevent this leeching the city pumps the slightly basic
water.
The 5 percent of residents who receive well water do so because
they live in the hills and “because the city can’t pump water that
high,” Danicic said. |
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From
June 23, 2007, Newberg Graphic
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