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Newsletter - Building Community
Awards & Recognition
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When it rains, High Point drains. Naturally.
SEATTLE—December
12, 2005—If you drive
through High Point, you might not notice the feature that is most
unusual about this neighborhood. But if you walk through the
redeveloped neighborhood – you’ll probably start wondering, why are
the planting strips so wide? Why are there sections that look
like ditches and why are they landscaped with so many plants? Why do
sidewalks look different? And what about those gravel parking areas?
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Rainwater from High Point drains into
Longfellow Creek, supplying the creek with roughly 10 percent of its
water. The old drainage system, after collecting dirt and toxic
materials from rooftops, streets, sidewalks, and parking areas,
channeled the water into pipes that drained directly into Longfellow
Creek. While the water quickly disappeared from the site, the
contaminated and wildly fluctuating run-off polluted and eroded the
creek, and harmed its ecosystem. |
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With High Point’s redevelopment,
Seattle Housing and the City of Seattle saw an opportunity to
demonstrate, on a large, densely populated tract of land, that
polluted storm water run-off in urban areas is not inevitable. These
agencies wanted to show that with thoughtful design, the trend can
be reversed and the environment protected. The system they designed
uses the attributes of the soil to ensure that High Point’s runoff,
when it reaches Longfellow Creek, is nearly free of contaminants. |
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Rainwater and stormwater run-off are channeled
in to this stormwater detention pond at the northeast corner of the
site. The pond holds, cleanses and slowly releases the water. |
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The soil is an excellent water
purifier. As water enters the ground, plant roots and microorganisms
break down and consume most of the harmful chemicals and waste. Once
through the soil surface, water moves slowly, sometimes as little as
one inch per day. When this water finally reaches the creek below
the hillside, it is very clean, and is the same temperature as the
creek water.
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In a built-out urban environment, it
takes a complex plan and a great deal of construction work to let
nature act naturally. Natural processes alone may not be sufficient
to handle large amounts of rainwater in storms that occur perhaps
only once in a hundred years. So, to accommodate these rare events,
a system of perforated conveyance piping has been installed deep
below the surface. Through these pipes, excess water is channeled
into a storm water detention pond at the northeast corner of the
site. This pond holds, cleanses, and later slowly releases the
water. |
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Wildlife is attracted to the site's natural
components. This bald eagle takes a drink from the stormwater detention pond. |
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The planting
strips are landscaped and shaped to serve as the key collection and
absorption points for rainwater. Gravel parking areas and porous
pavement sidewalks allow rain water from smaller storms to flow
through unimpeded. Those sidewalks are actually made from porous
pavement – porous because water runs through countless tiny holes
directly into the ground below.
In many ways, the
new system is expected to function like a forest meadow.
Environmental benefits for the creek will be substantial, and
residents will benefit as well. The wide planting strips create an
unusually pleasant streetscape and help make High Point a beautiful
and healthy neighborhood. A neighborhood perfect for a walk.
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