The Rural Voice, 2002-12, Page 41households using septic tanks is the
equivalent of one day's treatment at
the county's sewage treatment
facilities. The concentrated nature of
the waste and the amount of organic
materials to be treated is the problem,
he said.
Costs of the renovations. plus costs
of eventual upgrading of the capacity
of the Wingham and Exeter plants to
replace the capacity used by
treatment of septage, would be borne
through a tipping fee charged to
waste haulers.
The tipping fee for a typical septic
tank cleanout would be $230 but with
the pumping and transportation costs
of the hauler, it would come close to
$400, Burns said. If someone gets
their tank pumped out every three
years, as recommended. that works
out to about $130 a year, or about
$11 a month, less than someone
would pay for sewage charges in an
urban area but considerably more
than people are used to paying, Burns
said.
What's more. haulers are worried
that they would be the ones to pay
the tipping feed, but might not be
able to collect it from their
customers.
On the other hand. Burns said.
there's a limited incentive for
municipalities to accept the
waste. There are up front costs for
modifications that are only recovered
later through the tipping fees.
Eagles notes the same problem.
"The impact is not just biological."
he says. First of all there are the
expensive alterations that must be
made to a treatment facility. Then
accepting the septage for treatment
will decrease the capacity of the
treatment plant for future growth in
the ktrban areas they serve. Who pays
for replacing that capacity. he
wonders, the people who have
already paid for building that
treatment system or the people whose
septic tanks are being cleaned out''
Huron County officials worried
that the $400 cost of pumping a
septic tank might mean homeowners
will try to avoid the cost by not
properly maintaining their tanks.
Goderich Mayor Deb Shewfelt
praised Burns's report saying he felt
there were real problems with the
heavy cottage population along the
Lake Huron shoreline that use septic
tanks but he worried that the
municipalities receiving septage
would get the volume needed to pay
for their costs. People won't pump
their tanks if it costs more, he
predicted and provincial legislation is
going to be required to force people
A quick primer on septic tank history and operation
The University of California at Davis provides the
following background on the history and operation of the
septic tank.
Alittle historical perspective is always useful.
Apparently the French were the first to use an
underground septic tank system, back in the
1870s. By the mid 1880s, two -chamber, automatic
siphoning septic tank systems, similar in concept to those
used today, were being installed in the United States.
Even now, a century plus later, septic tank systems
represent a major household wastewater treatment option.
Fully one quarter to one-third of the homes in the U.S.
utilize such a system.
JUST WHAT IS A SEPTIC TANK SYSTEM?
A septic tank system includes an underground tank and
leach field. A well designed and maintained concrete,
fiberglass or plastic tank should last about 50 years.
Because of corrosion problems, steel tanks may only last
a decade or less. Most typical is a two-compartment septic
tank. The size of the tank will vary depending upon local
codes, but a typical tank for a family of four would have a
liquid capacity of 1,500 gallons (more usually 800 gallons
in Ontario). On the left is the input pipe from the
dwelling, on the far right is the output pipe to the leach
field. The tank itself is water tight and divided into two
semi -compartments. This division allows for improved
digestion of the waste materials. When the waste flows
into the tank, the heavy solids (primarily feces) sink to the
bottom to form a layer of "sludge". Lighter materials
(grease, fats, small food particles, etc.) float on the
surface forming a layer of "scum". Between these two
layers is a soup of suspended materials and water soluble
chemicals (urea from urine and many household
chemicals). The division into two chambers increases the
efficiency of the system at removing suspended solids.
The second compartment receives its "load", or liquid
mixture, already substantially clarified (much of the solid
material has settled out of the liquid). There is little
turbulence in the second chamber either, because the load
enters more slowly. Both of these factors allow settling of
finer suspended solids than can occur in the first chamber
where incoming material acts to churn up the chamber
contents.
HOW IS THE LOAD DECOMPOSED?
The process of digestion in the tank is carried out
primarily by microbes excreted from our gastrointestinal
tracts (E. coli, for instance).
Digestion is an anaerobic process, meaning that
oxygen is not required. Gases (hydrogen sulfide and
methane) are produced and must be vented. Basically, the
same thing that happens in a septic tank also occurs in our
guts and in centralized waste water treatment plants,
however a properly operating septic system probably is
the most efficient of the three. In the septic system, the
gases help to stir the sludge, scum and liquid layers which
promotes further digestion of the solids. A properly
functioning tank will convert the bulk of solids into liquid
waste through the processes of digestion and hence,
decomposition.
PROBLEMS LEADING TO CONTAMINATION
A septic system is well suited to break down human
excrement, and a well designed, properly used and
maintained system is one of the best choices for waste
disposal. However, there are many potential problems
with septic tanks. One of which is that people put a lot
more than human waste down their drains. Even simple
food items such as too much grease, cooking oil or fat
may greatly reduce the efficiency of the system.
Household cleaners, paints and other toxics are also toxic
to the bacteria which make the system operate properly.
Excesses of these chemicals may cause a severe
disruption in the system.0
DECEMBER 2002 37