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Introduction A
properly operating septic system is a vital part of many homes located in rural
areas. However, the septic system is often the last thing on the mind of a
homeowner until there is a problem with the system. When a home is purchased,
the big question is, Will I have trouble with the system after I move into the
home? Unfortunately,
there is no absolute way to predict how long a septic system will last or if it
will be able to handle an increased load. A septic inspection, however, can
yield useful information on the condition of the system as it exists when the
system is inspected. While predicting the future with regard to the septic
system is not part of any septic inspection, the inspection often uncovers
defects in the system which can save the purchaser unexpected expense. There
are many different types of septic systems ranging from what are called
conventional in-ground systems to sand mounds and from spray irrigation systems
to stream discharge systems. There are also seepage pits, cesspools, and
homemade systems. This booklet is not intended to cover every situation, but is
intended to give the homeowner an understanding of the concept of how a septic
system works and a better understanding of a septic inspection. Design Let's
see how a typical septic system is designed. In the most basic terms, a typical
septic system usually consists of a means of separating the liquid material from
the solid material and an area where the liquid material can be disposed. The
solid-liquid separation is usually accomplished in what is called a treatment
tank. The treatment tank is a relatively large structure typically made of
concrete. The approximate size for a residence is 1000 to 1500 gallons for newer
tanks. Some older tanks may be
closer to 300 gallons. The
solid material and liquid material enter the treatment tank by means of the
drain pipe from the house. In addition to separating the liquid material from
the solid material, the treatment tank also provides partial treatment of the
septic waste through biological action within the tank. The solid-liquid
separation is accomplished by the use of baffles within the tank. The inlet pipe
is usually located at one end of the treatment tank and the outlet pipe at the
other end. The normal liquid level in the treatment tank is at the level of the
outlet pipe. The solid material that is heavier than water sinks to the bottom
of the tank where biological breakdown occurs. Any solid matter that floats is
prevented from going out the outlet pipe by means of an outlet baffle which
extends just below the surface of the water. In
a standard septic treatment tank the biological action is from anaerobic
bacteria, that is bacteria that multiply under conditions where little or no
oxygen is present. Not all of the solid material in a treatment tank can be
broken down by microbiological action. So over time, these solids build up
inside the treatment tank. Regular pumping of the treatment tank removes these
solids and allows room for additional solids to enter the tank. When a septic
tank is not cleaned frequently enough, the solids from the treatment tank begin
to flow out of the treatment tank and into the area where the liquid is
disposed. Solids in this area have no place to go and cause plugging of the
pores of the absorption area. This lack of proper maintenance can greatly reduce
the capacity of the septic system to dispose of waste and will cause eventual
failure of the system. The
old adage "If it ain't broke don't fix it" DOES NOT apply in this
case. It would be much better to apply the saying "An ounce of prevention
is worth a pound of cure." How
often should a septic tank be cleaned or pumped? The frequency for pumping a
septic system depends on a number of factors; the average frequency is between
two and five years.
You can, in some cases, abuse a septic system and neglect to pump it for 10 or
20 years without any apparent problem. This would be like driving your
automobile for 50,000 miles without changing the oil. You might get away with
it, but you would certainly cause undue wear and tear on the engine. The
same is true with a septic system. You may get away with not pumping the system
for many years, but you will pay for it in the end by having to replace the
absorption area. Absorption
Area Let's
move out of the septic tank and follow the liquid to the absorption area.
While the treatment tank provides some treatment of the septic waste, it
does not get rid of harmful bacteria and viruses, so further treatment of the
waste is necessary. If soil conditions are adequate, this further treatment of
the septic waste can be accomplished in the absorption area by biological action
which takes place in the presence of air. Such microorganisms are known as
aerobic. There
are many types of absorption areas, drain fields, seepage beds, and sand mounds.
As stated earlier, this booklet is not intended to cover every situation, but is
intended to give the homeowner an understanding of the concept of how a basic
septic system works. The
in-ground type of system uses a series of perforated pipes located below the
ground surface. These pipes are placed in a bed of crushed stone or aggregate.
The sewage flows over the crushed stone or aggregate into the underlying
soil. The condition of this soil determines how well your septic
system will operate and how large the absorption area needs to be. If the
absorption area is too small and the soil is too tight as with clay soils, the
liquid cannot soak into the soil fast enough causing the waste to either back up
into the home or emerge at the ground surface. An early sign of waste emerging
at the surface is "lush growth." The saying "that the grass is
always greener over the septic tank" isn't true when it comes to a properly
operating septic system. In areas
where the soil is too loose, the waste will quickly flow through the soil not
allowing time for the complete biological treatment of the septic waste. This
untreated septic waste may eventually contaminate underground water sources. When
the soil conditions are right, an area of active microorganisms is formed where
the waste enters the soil. As the waste slowly percolates through the soil the
microorganisms continue to grow and feed on the harmful bacteria and viruses in
the septic waste. The underlying soil continues to absorb and filter the waste.
Four feet of soil is all that is needed to treat the septic waste in good soil
conditions. What
happens when the soil around a septic system is saturated with water from other
sources? When the septic waste encounters soil saturated with water, the
biological action which destroys the harmful bacteria and viruses is inhibited
and the saturated soil along with the surrounding water becomes contaminated.
This contaminated water keeps moving and spreading until it comes into contact
with the underground, water bearing aquifers that may be used for drinking water
supplies. Contaminated water eventually results. Soils
that drain too fast or have evidence of seasonally high water table can be
helped in their treatment of septic waste by the construction of elevated sand
mounds. In an elevated sand mound the waste is treated inside of a constructed
bed of sand and stone prior to contacting the natural ground surface. Pump tanks
or dosing tanks are usually used with sand mounds to control the flow of liquid
waste into the sand mound. In many cases the sand mound is also uphill so the
use of a pump becomes mandatory. Can
septic waste ever be discharged into a stream? Some recent advances in household
septic systems employ additional filtration and chemical treatment of the septic
waste. These systems then are able to dispose of the septic waste above ground
or into a stream since the harmful bacteria and viruses are destroyed by
chemical means. Special permits are generally required for such systems. What
about cesspools? Older systems often employ a variety of approaches to dispose
of septic waste, some more effective than others. Cesspools, seepage pits, and
leach pits are just a few of these types of systems. Most of these older systems
were installed prior to permits being required. They generally consist of some
kind of masonry structure located beneath the ground. The masonry is often
concrete blocks or bricks that have been assembled with spaces between them, the
bottom of the pit is generally soil. Crushed stone absorption areas are
sometimes added to these systems but are not always included with the system. Since
these older systems were installed before septic regulations were in place, they
were often constructed without regard to soil conditions or percolation rate.
When they were installed in suitable soil they may work effectively for a long
time. On the other hand, systems that were installed in unsuitable soils may
contaminate ground water or fail in other ways. When such systems require
renovation, they usually will need to be replaced with a properly permitted
system, due to local regulations. Inspection From
this brief description you can see that most of the components and working parts
of a septic system are underground and are not naturally visible.
Inspecting a typical septic system then presents a challenge.
A choice needs to be made as to how far one wants to go to investigate a
system. In
nearly all cases it is impossible to check all of the septic system components
as this would require unearthing the tank, absorption area, distribution system,
etc. If this is done, there is a risk of damaging the system and ruining the
landscaping of the property. In addition, the soil conditions change over time
due to both natural and man made alterations. Soil suitability testing which is
discussed later could be performed, but is usually impractical in a typical real
estate transaction. Considering
the past history of a septic system is useful, but it should be noted that a
system which has worked fine for years may over time fail with little or no
warning. All septic systems have a finite life span, and inmost cases it is
impossible to predict if the system will last 3 or 300 years.
A non-invasive inspection of a septic system is often a good starting
point for helping to determine the condition of an existing septic system. The
following procedure is used by Suburban Property Inspections. Other companies
may or may not follow this same procedure, and since there are many variations
in septic system design and function, each inspection is likely to be unique in
its own way. Non-invasive inspections leave the soil virtually undisturbed and
do not alter the system in any appreciable way. Any available, readily
accessible access caps are removed and the liquid level inside is observed. The
water inside the home is run for a minimum of thirty minutes. During this time
the liquid levels in the access pipes (if any) are observed and the absorption
area is examined for seepage or lush growth. The technician relies on visual
signs for detecting any defects in the system. Since the soil is undisturbed
this kind of inspection can be performed without damaging the lawn or risking
the damage caused by digging up parts of the system. Some relocation companies
require that a non-invasive inspection be performed. While
the water is running inside the home the toilets are each flushed and are
observed for proper operation. The drain lines that are visible inside the home
are followed to determine if there is more than one system at the property. Some
older systems separate the gray water drains from the black water drains. The
gray water drains may at times discharge to daylight. This is likely a violation
of local ordinances. In some localities, gray water daylight drains are so
common they are largely ignored; other areas may not be so lenient. Septic waste
by most definitions includes waste water that may contain any kind of bodily
fluid or waste; this would include wash water, bath water, or toilet water. On
the other hand, water that enters the basement due to naturally saturated soils
is not considered septic waste. Such water can be piped to daylight or pumped to
the surface by means of a sump pump. Bear in mind each locality is able to set
their own standards. Therefore, to be sure what is allowed in your area, you
will need to check with your township, city, or county authorities.
If the absorption area is located and if the soil conditions merit it, a
probe bar is used to check the amount of moisture in the soil and absorption
area. Saturated soil in or around the absorption area usually indicates a
problem. Such wetness may be
accompanied by a distinct septic smell or lush growth; however, this is not
always the case. A
liquid level that is above the stone is generally considered a defect in a
system, though it should be realized that such systems may "work" for
the current owner. Why
the dilemma? There are several reasons why an absorption area may have liquid
above the stone. One is that the absorption area has served its useful life span
and is no longer able to allow waste to enter the surrounding soil.
This may be due to organic material plugging the soil pores which
underlie and surround the stone of the absorption area. In such cases, liquid
above the stone in the absorption area is an early sign of system failure and
breakthrough to the surface will eventually follow. A second reason can be
overload of the system. This may be due to leaks in the plumbing of the home, an
excessive amount of water usage in the home, or an undersized system. Since
on-site septic is often accompanied by on-site water with no means of metering
the water, it is often difficult to determine if overload is the reason for the
flooded condition of the absorption area. A third reason is high water table.
While high water table with no septic breakthrough at the surface might seem to
be acceptable at first, such is not the case. When the septic waste does not
have the four feet of arable soil for renovation of the waste, ground water
contamination usually occurs. Once the bacteria and viruses are in the water
table they can survive with little renovation occurring in the soil. Such
contamination can travel a considerable distance to water supplies or streams.
When one portion of an absorption area is flooded while the rest is dry,
the problem may be less severe and may be a matter of re-leveling the
distribution box. In other cases, such as what is known as a serial distribution
system, the design is intended to cause the first portion of an absorption area
to flood prior to going into the next portion. Such designs are not common in
most areas of the country. Weather How
does weather affect a septic system? Since homes are sold in all seasons of the
year, septic inspections need to be performed in all kinds of weather.
Frozen ground and snow cover may considerably limit the amount of
information obtained by a septic inspection. Heavy rainfall contributes to water
in the soil and, depending on the grading around the absorption area, can cause
additional water in the absorption area. Ideally, the grading should be such
that rain water is diverted away from the absorption area. Inspections performed
in less than ideal weather will provide less useful information than those done
under ideal conditions. The septic inspection is limited to visual observations
made the day of the inspection. Inspections performed on other days may yield
different results. The septic system, however, should be able to work properly
under all normal weather conditions. Severe weather conditions such as flooding
may make a system temporarily unusable and can cause damage to the system.
Inspections performed at such times would not represent the normal condition of
the system. The inspector, however, is limited to what he can observe while he
is at the property and is not there to attempt to predict how the system will
perform at other times. Soil How
is the soil tested for suitability? Soil suitability is rarely a part of an
on-site septic inspection. However, should the system be failing, the soil
suitability testing would need to be done in order to install a replacement
system. Each area has their own standards for testing soil suitability; most
areas employ a procedure similarity the following. Usually a "deep
probe" is performed by digging a seven foot deep trench with a backhoe. A
soil specialist then looks at the soil layers for telltale signs of seasonally
high water table as well as to assess the visual suitability of the soil for
drainage characteristics. Fractured rock may allow drainage that is too fast for
proper renovation of the waste, while a seasonally high water table that is too
close to the surface may indicate that ground water contamination will result
from a septic system being placed below the surface of the ground in that area.
Obviously it may be necessary to dig and examine many "deep probes"
prior to finding suitable soil. Once
a suitable "deep probe" has been performed the next step is to have a
"perc test" done. Here a series of holes are dug and after proper
conditioning of the soil the holes are filled with water and the rate of
drainage into the soil is measured. Soils that drain too slow may not be able to
handle the needed quantity of liquid waste, while soils that drain too fast may
not allow enough time for the waste to be renovated and ground water
contamination will result. The data
obtained from the "deep probe" and "perc test" are compared
to state or local regulations. These regulations usually dictate what type of
system if any can be installed at a property. Can
a property have totally unsuitable soil? Yes, in some cases there may be no
place to install a system on a property. Where this is the case and a house
already exists on the property, connection to public sewer or the installation
of holding tanks may be the only option short of vacating the home.
What are holding tanks? Holding tanks are, as the name implies, used to
hold the waste until it can be removed from the site. Removal is typically done
by pumping the waste into a truck and hauling it to a disposal facility. The
cost of using a holding tank system can be excessive. The
Buyer's Point of View As
a buyer where might you run into a problem even after a satisfactory septic
inspection? All septic systems have a limited capacity to handle waste. Problems
with septic systems that show no defects during an inspection most often occur
when an increased load is put on a septic system by the new owner. For instance,
an older person may occupy a large home for many years with no septic problems.
A family of three or four may purchase the home and use three or four
times the amount of water. The septic system may not be able to handle this
increased load and subsequent failure of the system occurs.
Find out when the system was last pumped/cleaned out.
If it has been more than 4 years, request it get pumped.
Always ask for a septic certification prior to settlement. The
age of the system should also be considered. If the system has been in use for
20 years or more without major renovations, such renovations should be
anticipated. Questions you might consider: Is public sewer available if I need
to connect to it? Do I have sufficient, suitable land to put a replacement
system if it is needed? Can
you have a more thorough inspection beyond the standard non-invasive inspection?
Yes, for an additional fee and with the permission of the property owner, you
can unearth various parts of the septic system and or install absorption area
inspection pipes. Dye testing is available as well as testing of soils for fecal
matter. Various forms of hydraulic loading tests are also available. Owning
your own septic system has advantages and disadvantages. Public systems, of
course, have fees associated with their use; private systems avoid these fees
but are not without operating cost. When a public system needs renovation, the
cost often is divided among a large number of people. When a private system
fails, it's usually the owner's problem alone. If
you are buying or selling a home, a septic inspection is a good investment.
While a favorable inspection does not guarantee that you will not have
trouble with the septic system, it can often detect defects that would go
unnoticed to the untrained eye. It could save the buyer a major expense. |
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