Environmental Engineering Reference
In-Depth Information
Engineers' “2009 Report Card for America's Infrastructure.” The
United States' drinking water systems earned a D- grade from
the industry organization.
7
Good Down the Drain with the Bad
More than half of the “wastewater” that runs off and away via waste-
water infrastructure in many cities actually is potable water that
drains or leaks into the systems and then is carried away forever. In
the Boston metropolitan area, for example, a recent study revealed
that in a typical year with normal rainfall (45 inches), more than 60
percent of the water treated at the Massachusetts Water Resources
Authority's Deer Island wastewater facility was actually potable
water or rainwater that ended up in the system.
8
These statistics
were reported by Robert Zimmerman Jr., who is executive direc-
tor of the nonprofi t Charles River Watershed Association, an advo-
cacy group that serves the greater Boston area. Deer Island, in
the middle of Boston Harbor, collects wastewater from forty-three
communities, and then disposes of it nine and a half miles out in
Massachusetts Bay at a rate of 380 million gallons a day. Of that vol-
ume, 230 million gallons a day of
good
water heads out to sea, rather
than back into the aquifers. “That's about 85 billion gallons of water
a year, which is the equivalent of the entire fl ow of the Charles
River,” says Zimmerman, who advocates decentralized wastewater
treatment facilities as an environmentally sound way to make the
most of freshwater supplies. Boston's water pipes leak, too. Some
of the pipes still in use in Boston date back to the late nineteenth
and early twentieth centuries and are made of brick and mortar.
The mortar has cracked and has “enormous” leaks, Zimmerman
adds, because water, after all, is attracted to where the pressure is
the lowest. To get a better idea of how groundwater fi nds fi ssures
and weak links in the pipes, Zimmerman offers the following sce-
nario: Picture a bathtub with a pipe that comes out of the wall,
goes through the tub, and then exits out again onto the fl oor of
the room. If you fi ll the tub up with water, then punch a hole in the
pipe, where does the water in the tub go? It seeks the point of least
resistance, blows into the hole in the pipe and out onto the fl oor of
the room.
