Engineer Offers Tips to Prevent
Frozen Septic Systems
By Tom Scherer,
Irrigation and Water Resources Specialist
NDSU Extension
Service
Little snow cover, dry soil conditions
and very cold temperatures can lead to freezing problems in septic
systems, but an agricultural engineer at North Dakota
State University says problems can be
prevented by taking some precautions now.
"Last winter many people had problems
with frozen septic systems. In addition, many shallow water and sewer
pipes also experienced freezing problems," says Tom Scherer of the NDSU
Extension Service. "The lack of snow cover, dry soil conditions and very
cold air temperatures over an extended period of time caused these
problems. This winter we could see similar weather conditions."
Fresh snow is an excellent insulator,
Scherer notes. "Ten inches of fresh fluffy snow containing about 7 percent
water is approximately equal to a six-inch-layer of fiberglass insulation
with an R-value of R-18. Of course, the insulating capacity of snow will
decrease as it becomes compacted but any accumulation over 12 inches will
provide significant frost protection."
However, problems can occur when there
is very little snow to cover bare soil or mown areas. Under those
conditions, frost will penetrate deep into the
ground.
"Frozen septic system problems can be
avoided by making some preparations before the cold weather and snow
arrive," Scherer says.
A typical septic system has four main
parts where freezing problems can occur:
- The pipe from the house to the septic tank.
- The septic tank and for some systems, a pump
lift station.
- The pipe from the septic tank to the soil
treatment system.
- The soil treatment system.
"A common problem area is the pipe
from the house to the septic system where it exits the basement wall.
Often the wind keeps snow from accumulating right next to the house on the
north and west sides of buildings, allowing frost to penetrate deeper in
that area," Scherer says. "Low flow from dripping faucets, high efficiency
furnaces and leaking toilets will slowly freeze where the pipe leaves the
basement wall until it blocks the pipe."
If you have experienced this problem,
first fix any leaky fixtures in the house. Next, place some type of mulch
(hay, straw, bags of leaves, etc) at least a foot thick and at least 5
feet wide over the exit point, shovel snow over the area or place a snow
fence in the area to trap snow.
Scherer notes that water holds a great
deal of heat and with daily use septic tanks rarely freeze, even in the
coldest weather. However, when the house is vacant for a week or more,
water does not enter the tank to keep it warm and it may
freeze.
"If you have a septic system that is
used infrequently during the winter, protect the system from freezing by
placing a layer of mulch at least a foot deep over the tank and extend it
at least 5 feet past the edges of the tank. Using a snow fence to trap
snow over the tank will also help," he says.
The pipe from the septic tank to the
soil treatment area is subject to the same problems as the pipe from the
house to the septic tank. If problems have occurred in the past, fix leaky
fixtures and place mulch above the pipe to prevent them from occurring
again.
Improper slope and/or slumping of the
pipe due to soil settling or vehicle traffic may also cause problems.
Often, the pipe slumps right next to the septic tank due to soil settling
around the tank after construction.
The soil treatment system (often
called the drainfield) is subject to freezing if
the area above it is always wet and soggy, Scherer says. This condition
indicates that the effluent is not infiltrating properly and there may be
other problems with the drainfield. If your
drainfield is soggy or wet, now is the time to
bring in a septic system installer for a professional examination. "The
solution may be simple and inexpensive or it could be complicated and
require extensive renovation of the drainfield,"
he says.
A new drainfield without a grass cover is subject to
freezing and should be mulched. It is especially important to mulch around
exposed inspection pipes, risers and the manhole. Distribution boxes are
also subject to freezing and should be mulched.
The drainfield should never be used as a traffic area for
people, vehicles or animals, Scherer says. During winter months, place a
snow fence or other suitable barrier around the drainfield to discourage any traffic on the area and
help maintain a thicker layer of snow insulation.
"A frozen septic system can be a real
headache in the middle of the winter," he says. "With a little effort now,
many potential freezing problems can be eliminated. Take the time to
examine your system. This winter, don’t drive any vehicles such as ATV’s,
snowmobiles or automobiles over any part of the septic system. Compacted
snow will not insulate nearly as well as undisturbed snow. If we do happen
to get a good layer of snow, don’t get carried away while plowing and
remove the snow cover from any part of the septic
system."
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