MIL-HDBK-1138
Section 7:
EXTREME CLIMATE OPERATION
7.
7.1
Effects of Extreme Cold Climates. Cold weather
can have significant and often severe adverse effects on the
maintenance, operations, and performance of WWTPs. Temperature-
dependent effects include physical, chemical, and biological
responses. Often performance efficiency will be affected by
extreme cold weather, which can cause treatment processes to
suffer. The structures and buildings will also be affected by
excessive snow loads, snow drifting, ice formation, and related
freezing of system components. These factors will affect the O&M
of the facility. Major cold weather operational problems can be
divided into four specific categories:
a)
Changes in the viscosity of the wastewater and
equipment lubricants
b)
Reaction rate changes in physical, chemical and
biological processes
c)
Ice formation and freezing in process components
d)
Snow and ice accumulation on structures, control
equipment, roads and walkways, and walls and berms
The potential for winter and cold weather problems is
not limited to a particular type of treatment process nor to any
particular size of treatment plant. Table 6 lists areas within a
plant where cold weather may affect plant performance,
operations, or maintenance.
Additional information about cold weather problems can
be found in U.S. Army Cold Regions Research and Engineering
Laboratory (CRREL) Special Report 85-11, Prevention of Freezing
and Other Cold Weather Problems at Wastewater Treatment
Facilities.
7.2
Preliminary Treatment Processes. As wastewater
enters the treatment plant, the preliminary processes will be
affected by the cold water and freezing weather. These processes
are intended to remove large solids and abrasive material. The
failure of any of these units will affect downstream processes.
Therefore, it is important to keep these units working as
effectively as possible. This discussion is also applicable to
collection system pumping stations that may be equipped with
similar equipment. Table 7 suggests solutions to these cold
weather problems.
55
Previous Page
