A-1 Septic
Septic Tank Cleaning and Repairs
Background
The most common wastewater treatment system used
in rural areas is the septic tank-soil
absorption system. The septic tank removes solids
from the wastewater, and the soil absorption
field (drainfield) filters, treats and disposes
of the septic tank effluent.
Removing the solids from the wastewater protects
the drainfield from clogging and early failure.
The septic tank also stores the settled solids
and allows biological digestion of some of these
solids.
How Does A Septic Tank Work?
The septic tank removes solids by holding wastewater
in the tank, which allows the solids to
settle and scum to rise to the top. Incoming
water should be held in the tank for at least 24
hours in order to improve settling. Up to 50
percent of the solids will decompose into liquids and
gases. The remaining solids accumulate in the
tank.
Biological and chemical additives are not needed
to aid or accelerate settling or decomposition.
As a general rule, no solids other than human
wastes and white toilet paper should be flushed.
As the septic system is used, sludge continues
to accumulate in the bottom of the septic tank.
Properly designed tanks have enough capacity
for three to eight years use before needing
service.
The tank should be checked each year starting
with the third year to determine how
much sludge is there. It is important to understand
that septic tanks always appear full because
both the inlet and the outlet are at the top
of the tank. The homeowner needs to determine how
much of the tankþs volume is being
taken up by solids, scum and sludge. When sludge and
scum take up more than 35 percent of the
tank volume, these solids need to be removed by
pumping.
Servicing A Septic Tank
When too much sludge and scum are allowed
to accumulate, the incoming sewage will not have
enough time in the septic tank for solids to
settle. Solids may flow to the drainfield and clog the
drainfield, causing the sewage to overflow to
the ground surface, where it exposes humans and
animals to the disease-causing organisms
in sewage. To prevent this from happening, it is very
important to check the tank and have it
serviced when needed.
The drainfield may not fail immediately when a
full tank is not pumped. However, the septic tank
is no longer protectingthe drainfield from solids.
This creates inefficiencies in the drainfield and
may allow contamination of the groundwater. Continued
neglect will result in failure of the
drainfield, and it may need to be replaced.
The frequency of pumping depends on the size of
the tank and what and how much goes down
your drains. Use of a garbage disposal and excessive
water use can increase pumping
frequency.
A 1,000 gallon septic tank is used for homes with
up to four bedrooms. If four people
live in a four-bedroom house, a 1,000 gallon
tank may need to be pumped approximately every
three years. If the same system serves a family
of two, the tank would be ready for pumping
every six years. Systems installed before the
current rules and regulations may have smaller
septic tanks and may need to be pumped more often.
Cleaning The Tank
A septic tank pumper licensed by the Department
of Environmental Quality (DEQ) can pump
and clean your tank. It is a good idea to supervise
the cleaning to ensure that is done properly.
The material pumped out is known as “septage.”
To get all of the material from the tank,
the scum layer must be broken up and the sludge layers
stirred up into the liquid portion of the tank.
This is usually done by pumping liquid from the tank
and reinjecting it into the bottom of the tank.
The septic tank should be pumped out through the
large central service hole, not the sanitary
tee or baffle inspection ports. Pumping out a tank
through
the inspection ports can cause damage.
Before closing the tank, check the condition of
the tees or baffles. If they are missing or
deteriorated, replace them with sanitary tees.
Never enter a septic tank. Any work to replace the
baffles or repair the tank should be made from
the outside. The septic tank produces toxic
gases which can kill a person in a matter of
minutes. When working on a tank from the outside,
make sure the area is well ventilated and someone
is standing by. Never go into a septic tank to
retrieve someone who was overcome by toxic gases
or the lack of oxygen without a
self-contained breathing apparatus. In
the event someone falls into a septic tank the best thing
to do is call for emergency service and put a
fan at the top of the tank to blow in fresh air.
To facilitate cleaning and inspection, install
a watertight riser and a gasketed cover from the
central service hole at least one inch above
the surface before burying the tank. Do not bury the
riser cover.