Environmental Engineering Reference
In-Depth Information
Chapter 3, including creating vegetated swales instead of concrete
ditches along roads and highways, urban landscaping, rain gardens,
and riparian buffers.
Another creative approach to solving the pavement problem
is the use of pervious rather than impervious pavement. Whether
concrete or asphalt, pervious paving material allows water to seep
through back into the ground instead of draining off and away (see
Figure 8.3). Use of pervious materials boosts the cost of a paving
project—10 to 20 percent, according to the National Ready Mix
Concrete Association. As yet, that's a big consideration with today's
recession-weary, budget-strapped cities and states.
The success of such surfaces also depends on the type of soil
involved, says Katherine Austin, AIA, a Sonoma County, California-
based architect and former mayor of and planning commission
member for Sebastopol, California. Pervious surfaces are not effec-
tive with nonporous soil like adobe, she adds. The level of the water
table in the area also is a consideration, because nothing will soak
into the ground if it's already saturated.
Nonetheless, pervious pavement is one more effective option
that can make a difference when it comes to our dwindling water
supplies.
WATER TALES
The Stormwater Research and Demonstration Park at
Villanova University in Villanova, Pennsylvania, uses per-
vious concrete and infi ltration beds as a solution to the
area's fl ooding and erosion problems. See Figures 8.2 and
8.3 to see how it was accomplished.*
The 1.3-acre drainage area between two dormitories
used to be paved with standard asphalt and utilized a conventional
storm sewer system that sent the water runoff directly to the head-
waters of Mill Creek. That contributed to fl ooding problems that
led to stream bank erosion and sedimentation.
*Villanova University Pervious Concrete Site, Executive Summary (June 19, 2007), http://
egrfaculty.villanova.edu/public/Civil_Environmental/WREE/VUSP_Web_Folder/PC_web_
folder/PC_main.html.
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