Groundwater in the Great Lakes Basin

INTRODUCTION
Leaking underground storage tanks (LUSTs) are a
serious concern regarding groundwater quality, and
also of Great Lakes water quality in the Basin (Figure
1). The Great Lakes receive recharge not only via
surface water runoff and precipitation but also through
regional groundwater flow. If this groundwater is
contaminated by LUSTs, significant amounts of pollution
will be discharged into the Great Lakes. Although
an accurate tally of total USTs in the U.S. and Canada
is currently unknown, since not all underground
tanks are mandated to be registered and many older
tanks were installed before registrations came into
effect, estimates place this number, for both countries
combined, in the millions (CESD, 2002; Sierra Club,
2005).
NUMBER OF UNDERGROUND STORAGE
TANKS
70
USTs frequently contain potentially dangerous and
toxic substances including, but not limited to, oil,
gasoline, diesel fuel, aviation fuel, other petroleum
products, radionuclides, solvents and waste/spent
fluids (Sierra Club, 2005). These stored materials
often contain carcinogenic compounds (e.g., benzene,
toluene, ethylbenzene and xylene or BTEX). Many
USTs are known to be currently leaking or have leaked
at some point in their past (Figure 2). A pinhole
leak can release 400 gallons (1,514 litres) in a year,
having the potential to contaminate vast quantities of
groundwater with a contamination ratio of one to one
million (Environment Canada, 1999; Sierra Club, 2005).
LUST and refinery spills like that at Exxon Mobil’s
property in Brooklyn, New York, with a volume of 17
to 30 million gallons (77-136 million litres) (Leising,
2007), result in extensive groundwater contamination,
and adjacent surface waters are also adversely
affected. Hazards arising from LUSTs include acute
and chronic drinking water health issues as well as the
accumulation of volatile and flammable gases, which
have resulted in spectacular and often fatal sewer and
basement explosions (e.g., St. John, New Brunswick,
and Guadalajara, Mexico). In Utah a leak from a local
gas station released 20,000 gallons of gasoline. Fumes
from the gasoline caused significant damage to local
homes and businesses (Fahys, 2008).
In the United States, as of March 2008, 478,457 releases
had been confirmed from the more than 2,302,287
registered USTs, both active and closed, which are
subject to federal regulations (U.S. EPA, 2008a; U.S.
EPA, 2007c). Other sources indicate that this figure,
however, may be more than 551,000 (Environmental
Data Resources Inc., 2008).
Figure 1.
Figure 2.
Leaking underground storage tanks.
Source: U.S. EPA & USGS.
Exhumed leaking underground storage
tanks. Photo by: D.W. Alley