Groundwater in the Great Lakes Basin

INTRODUCTION
Leaking underground municipal water mains and
sewer lines are of significant concern to groundwater
and surface water quality in the Great Lakes region. In
the “Report on the State of Municipal Infrastructure in
Canada” a key finding was that sewage systems, water
distribution systems and water supply installations
are among the oldest infrastructure facilities in Canada
(FCM, 1996). It has been estimated that between 1997-
2012 $88.4 billion will be needed for new and upgraded
water and wastewater infrastructure in Canada
(Canadian Water and Wastewater Association, 1997).
In the United States the situation is similar with the
majority of the water infrastructure “near the end of its
expected life span” (AWWA, 2001). Within the United
States 55,000 public water systems process more than
40 billion gallons of water a day (Village of Sugar
Grove Publics Work Department, 2006). However,
many older pipes may be losing upward of 50% of the
transported water (Gallagher, 2006). Each day 6 billion
gallons, or 15%, of processed water is lost. The greatest
source of the loss is often leaks in customer pipes off
the main piping system (Village of Sugar Grove Publics
Work Department, 2006). In Detroit alone an estimated
35 billion gallons of water leak out of the system
each year resulting in residents paying $23 million for
lost water (Gallagher, 2006). The American Water
Works Association (AWWA) (2001) estimates that
over the next 30 years $250 billion (not including the
wastewater infrastructure) will be needed to replace
drinking water pipes.
Currently, about 10 % of U.S. municipal water systems
are operated by private companies; however, it has been
estimated that this number will increase to 65 % or
more by 2020 (Melosi, 2008). There are more than 1.2
million miles of sewers underground across the United
States (Wheeler and Smith, 2008). By the year 2020,
85 % of U.S. water infrastructure will have reached the
end of its useful/designed life (Liquid Assets, 2008),
and about 45% of the sewer pipes in the U.S. will
be categorized as being in poor or worse condition
(Insituform, 2007).
Municipal Sewer Lines
Leaking sewer lines are a major concern regarding
water quality in the Great Lakes Basin. “It’s one of
the greatest problems localities face these days. The
systems are old. They’re outdated. They need updating,”
stated New York’s Senator Charles Schumer (Meyer,
2007). Leaks in sewer lines can happen for numerous
reasons, including blockage from tree roots, soil
slippage, washout resulting in loss of foundation,
sewage backup, faulty material, improperly constructed
pipelines, lack of corrosion protection, age, traffic and
ground subsidence (Adams, 2009).
Leakage from a sewer line consists of raw sewage
mixed with varying amounts of industrial waste
chemicals, along with pharmaceuticals, personal care
products and a myriad of other compounds (Pendersen,
1997). Although sewer line leaks can be the main
source of sulphate, chloride and nitrogen compounds
in urban groundwater (Eiswirth and Hötzl, 1997), in
some areas not enough effort is being put forward to
fix the problem. In Toronto, Ontario, only 0.35% of
the wastewater network is being replaced per year.
Since more than 50% of the city’s sewer infrastructure
is already over 50 years old, at this rate the last sewer
pipe will not be replaced until it is over 300 years old
(Levy, 2004). Recently, a 50-year-old, 40-metre-deep,
2.4-metre-diameter trunk sewer serving 750,000 people
was found, during a routine robotic camera inspection,
to be cracked and shattered and in imminent risk of
collapse, which would lead to a catastrophic event
and unimaginable environmental damage. The City of
Toronto quickly recommended a $30 million emergency
repair, but the bypass work will take 12-18 months to
complete and neighbouring residents are being warned
about a potential disaster by city officials (Weese,
2009a; Weese, 2009b). A study in the U.K. found that
13% of the nitrogen load in groundwater was due to
sewer leakage (Wakida and Lerner, 2005).
Sewer lines are generally constructed in a manner
that allows them to operate using gravity flow. These
gravity fed systems are much more cost efficient than
those requiring pumping. This is often accomplished by
placing pipes in topographical lows such as wetlands
and streambeds (beside or within the channel) (U.S.
EPA, 2006). Unfortunately, due to their placement,
when a leak occurs it is all the more likely to result in
contamination of surface or groundwaters. If the sewer
line is installed deep within the ground then it also
may be below the biologically active portion of the soil
and often below the water table. Because the released
sewage is already well below grade it does not have to
pass through the intense biodegradation and filtration
that it would normally undergo as it passed through
the soil. This allows contaminants, including pharmaceuticals,
microorganisms, pathogens (such as E. Coli),
organic matter, trace metals and toxic chemicals, to
directly enter groundwater (Pendersen, 1997). This can
be extremely dangerous if private or community wells
are nearby (Borchardt, Bradbury, Gotkowitz, Cherry
and Parker, 2007). Contaminated groundwater eventually
discharges into surface water bodies where it can
contaminate streams and lakes making them unsuitable
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