Biomedical Engineering Reference
In-Depth Information
of releases at smaller distribution facilities and from totes and
drums (Alliance Consulting International, 2008). As discussed
further in Section 2.2, methanol is a commonly used carbon source
for denitrification at wastewater treatment plants throughout the
United States.
At distribution facilities, methanol underground storage tank (UST)
systems are generally similar to gasoline systems, although some differ-
ences in materials used may exist (SWRCB, 1999a). New, upgraded UST
systems are double-walled and typically have an interstitial leak detection
device or other leak detection mechanism. Leak detection depends upon a
number of factors, such as the location, volume, and velocity of the leak.
Most commonly, leaks occur at the joints or at the dispenser; if a leak occurs
at the dispenser it may not be detected. Leak detection systems can be
subject to human error because alarms can typically be just turned off
without action being taken. Studies have found that while newer USTs are
less likely than older, single-walled tanks to leak, even upgraded USTs
experienced leaks (SWRCB, 1999b). Whether leaked material enters the
environment also depends on the presence of a catch or drip pan. Because
of all the potential leak scenarios from a UST, there are large differences in
the amount of fluid that may enter environment in this scenario. It is
conceivable that methanol releases may occur at methanol fueling facilities
at a rate similar to gasoline UST releases. If methanol USTs are located at
or near a gasoline dispensing location, subsurface methanol releases may
encounter existing gasoline contaminant plumes. Similarly, methanol
releases may also encounter chlorinated solvent plumes or other subsurface
contamination. In any case, this third scenario represents another important
potential route of methanol release to soil and/or groundwater.
2.1.2 Fate in the Environment
Methanol occurs naturally in the environment because of various
biological processes in vegetation, microorganisms, and other living
species (ENVIRON, 1996). Nevertheless, a large release of methanol to
the surface water, soil, or groundwater has the potential to adversely
impact the surrounding environment.
