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https://www.rrca.on.ca/_files/file/Septic%2520Smart%5B1%5D.pdf
Agriculture and
Agri-Food Canada
Agriculture et
Agroalimentaire Canada
Septic
Smart!
New Ideas for Household Septic Systems on Difficult Sites
A
lmost all rural residents in single-family homes
depend upon on-site septic systems to treat
household sewage. The traditional septic system
that is used across Ontario has three main components:
septic tank (or other treatment unit), distribution system,
and leaching bed.
The “conventional” leaching bed design relies on
perforated pipes laid in stone-filled trenches 0.5 metres
wide with a 0.9 metre depth in unsaturated soil. The
surrounding soil provides a suitable filter to cleanse the
septic effluent. The second most common design is the
“raised bed.” This option involves importing appropriate
soil onto the site to create a leaching bed which is high
enough above the water table or bedrock to provide
sufficient filtering for the effluent.
With proper and regular maintenance, traditional
septic system designs can perform very well in a variety
of soil types and site situations. However, investigators
currently estimate that 30 per cent of the estimated one
million household septic systems in Ontario, are failing to
adequately protect the environment.
A New Homeowner’s Guide to Septic Systems
is a
recent publication available free of charge from the
Ontario New Home Warranty Program. It is an excellent
r
esource for all rural home owners. The booklet explains
the design and operation of conventional systems,
reviews licensing, approvals and inspection under the
Ontario Building Code
(
OBC
) and pr
ovides tips on
regular maintenance. It is recommended reading to
anyone seriously considering a new or replacement
system — whether it is a traditional design, or one of the
alter
native designs pr
esented in this booklet.
Ther
e will be situations that due to difficult soil
conditions, a shallow water table, shallow soil depth to
bedr
ock, r
emote ar
eas, or small lots, wher
e traditional
septic designs ar
e not suitable or have failed. A failed
system can pr
esent major inconvenience and pose a
serious health thr
eat.
More and more companies are offering new ideas to
improve or replace the conventional septic system design.
The options presented in this booklet are categorized as:
d
Improving Performance of Existing Systems, and
d
New Design Ideas.
The alternative septic system designs described here
are for household systems generating less than 10,000
litres per day of effluent.
Each can be accepted as
“equivalent” systems at the discretion of the
Chief Building Official for your municipality, if
they are satisfied that the level of
performance conforms to the requirements of
the
Ontario Building Code.
Proper approvals
must be
acquired prior to installation.
ONT
ARIO FARM
ENVIRONMENTAL
COALITION
Ontario Soil and
Crop Improvement
Association
AGRICULTURAL
ADAPTATION
COUNCIL
Funding support for this booklet was supplied by Agriculture and Agri-Food Canada’s Canadian Adaptation and
Rural Development Fund (
CARD
), through the National Soil and Water Conservation Program administered by the
Agricultural
Adaptation Council and the Ontario Farm Environmental Coalition. The coordination of this booklet was
done by the Ontario Soil and Crop Improvement Association.
Mention of trade names and individual companies in
this booklet ar
e not intended as endorsements; nor is
criticism intended towards products or systems not
identified. The contributing writers focused on the
presentation of systems they were familiar with, and had
already been successfully used for Ontario households.
Several factors will guide your decision r
egarding septic
system design, including: the physical features of the site,
practicality, level
of performance,
cost,
maintenance,
availability, and
personal
preference.
2
}
Failure of this system was due to the
use of clay as the back-fill material
over the geotextile.
clay back-fill
d
drains slow down
d
toilets back up
d
sewage smell
d
grass over system is unusually green
or spongy
d
bacteria or nitrate contamination showing up
in drinking water tests
d
surface ponding of effluent
d
backing up into the home and/or breaking out
and pooling on the ground surface
d
contamination of surface water and ground
water supplies with nitrates, pathogens,
vir
uses and phosphates
Problem Identification
Symptoms of a Failed Septic System
Consequences of a Failed Septic System
The failed
system
exposed.
Inappropriate design, bad construction practices, or poor
maintenance can all lead to system failure. Failure of this
exposed system was due to the use of clay as the back-fill
material over the geotextile covering the leaching bed
tiles. The clay back-fill prohibited oxygen from the
atmospher
e from reaching the tile bed. The resulting lack
of aerobic microbial activity accelerated the formation of a
r
estrictive “biomat” or slime layer
.
3
Description:
Sand and wood chip filters act as an
inter
mediate step to improve effluent quality prior to
disposal into a conventional leaching bed, constructed
wetland or other treatment system.
Intended Use:
d
Environmentally sensitive areas where a higher level of
wastewater treatment is required.
d
To prolong the life of the leaching bed in
impermeable soils.
Details:
Sand Filter:
The overall sand filter dimensions range
from 3 m to 6 m square. Typically, the distribution tile is
installed within a 20 cm layer of 19 mm washed and
crushed stone, underlain with 60 cm layer of sand, over a
8 cm layer of pea gravel, over a 20 cm base layer of
crushed stone. The entire filter is typically below ground
level, and is contained within plastic
PVC
. Effluent from
the septic tank is dosed onto the filter and collected at
the bottom through a single perforated pipe, where it is
then pumped to the final disposal system. The entire
system is located beneath at least 25 cm of topsoil,
separated with a geotextile (see diagram).
W
ood Chip Filter:
The filter is similar to the sand filter
except the sand component is r
eplaced with wood chips.
Estimated Cost:
Adding a sand or wood chip filter can
double the cost of a typical septic system. Wher
e a site
limitation is involved (e.g.,
bedr
ock) the cost is the same.
The conventional leaching bed typically costs $23 – $33
per metre of trench, including materials and installation.
Improving the Performance of Existing Systems
Sand and Wood Chip Filters
Improving Performance
flow from
septic tank
2
5
c
m
o
f
t
o
p
s
o
i
l
10 cm
perforated
PVC pipe
with
ends
capped
20 cm layer of
19 mm washed,
crushed stone
60 cm
filter
sand
8 cm pea gravel
20 cm layer of
crushed stone
line pit with
18 ml PVC
10 cm PVC outlet
to pump chamber
grass cover
3
m
t
o
6
m
s
q
u
a
r
e
There are patented intermittent sand filter
systems that are allowed through the
OBC.
They typically rely on a more sophisticated
effluent distribution system that is pressurized.
Primary treatment is achieved in the septic
tank. The sand filter provides for further
decomposition. Approved suppliers are:
d
Sand Filtration Inc.,
Kitchener, Ontario.
Tel: (519) 743-1780
d
OSI
Onsite Sewage Inc.,
Kitchener, Ontario.
Tel: (519) 578-0969
Commercial Systems
4
Improving Performance
An ef
fluent filter installed at the outlet of the septic tank,
dramatically improves the quality of effluent being
discharged to the leaching bed, effectively extending its
life. The addition of an effluent filter to all systems is
strongly recommended.
Description:
Sewage enters the first chamber of the
septic tank through an inlet baffle or tee. Most of the larger
particles settle out and the effluent enters the second
chamber. The second chamber (much smaller than the
first) further enhances the settling process. If flows are
heavy at times, solids can pass through both
compartments and enter the leaching bed. The effluent
filter minimizes this. Effluent filters have two main purposes:
d
Assist in the settling of both large and small
particles, and
d
Help slow down flow to further enhance particle
settling before damage is done to the leaching bed.
Intended Use:
d
Improves effluent quality.
d
Extends leaching bed life.
Details:
d
Can be used in any septic tank.
d
May be installed in a new system, or
r
etr
ofitted
into
an
existing tank.
d
Cor
rosion proof construction.
d
Relatively simple installation.
d
Simple maintenance.
d
Filters can be equipped with
an
alar
m to war
n that filter
needs cleaning.
d
Custom and standard
sizes available from
many manufacturers.
Estimated Cost:
Generally
$300 (plus installation).
Source:
Available through
most licenced suppliers
and tank manufacturers.
Effluent Filters
A two-compartment tank with an effluent filter.
5
Description:
Aer
obic treatment units can be installed
either ahead of, or after the septic tank. By pumping air
into the sewage, aerobic microbes can improve effluent
quality and may offer some relief to the leaching bed.
There are several different designs on the market.
Each may have unique featur
es. A typical design
involves a single, precast concrete tank divided into four
compartments. The first two are: an anaerobic
pretreatment chamber, and an aerobic chamber. The
final two are clarification chambers that further filter the
wastewater, with options for disinfection and chlorination.
Wastewater flows from one chamber to the next, with
oxygen being added and the solids forced to settle out.
A mechanical pump is required for aeration.
Intended Use:
d
Prolongs the life of the leaching bed.
d
May be installed in a new system, or existing system.
Details:
Air is stirred or bubbled into the wastes,
br
eaking down the material, resulting in a reasonably
clear liquid and sludge. The liquid is discharged to the
leaching bed. The sludge must be periodically pumped
fr
om the tank.
Estimated Cost:
Typically up to $10,000.
Sour
ces:
d
Canadian Biocycle Ltd., British Columbia.
T
el: (250) 558-5566
d
Clearstr
eam Sewage T
r
eatment Systems
c/o Nor
thern Purification Systems, Ontario.
T
el: (905) 729-3212
d
C&M
Envir
onmental T
echnologies, Ontario.
Tel: (905) 850-3904
d
CMS
Rotordisk Inc., Ontario.
Tel: (416) 447-4964
d
Klargester Rotopack, Ontario.
Tel: (905) 850-7234
d
Nayadic, Inc., Pennsylvania.
Tel: (570) 784-1653
d
Northern Purification Systems, Ontario.
Tel: (905) 729-3212
d
Norweco Equipment Company, Ohio.
Tel: (419) 668-4471
d
Whitewater Sewage Treatment Systems,
British Columbia.
T
el: (604) 596-0608
d
Similar designs may also be available through local
concrete septic tank suppliers.
(For further information refer to SG-5, 1997
Ontario Building Code.
)
Aerobic Treatment Units
Aeration blower on an aer
obic unit.
A typical aerobic treatment unit
alongside
the septic tank.
Improving Performance
6
A patented system used to r
ejuvenate leaching beds
without costly excavation.
Description:
Terralift uses a long, narrow probe and
built-in pneumatic hammer to penetrate the soil or fill.
Compr
essed air is injected to fracture the soil. Dry
polystyrene pellets are injected into the cracks
created, in order to maintain the passages for the
percolation of liquids away from the leaching
trenches. This process is best suited to soils that
allow cracks (i.e., heavy clays).
Intended Use:
d
To prolong the life of an existing leaching bed.
Details:
d
The cracks created by the compressed air can
extend to depths of 90 cm.
d
The system causes no damage to lawns.
d
A site evaluation by a licensed sewage
installer
with experience using the Terralift
system is required.
Estimated Cost:
$3,500 for a thr
ee-year
guaranteed system.
Sour
ce:
T
er
ralift, Inc. Stockbridge, Massachusetts.
T
el: (413) 298-4272
Leaching Bed Remediation
Photo: Terralift Inc.
Improving Performance
The Ontario Building Code
(
OBC
)
regulates design, construction, operation
and maintenance of on-site septic
systems for most single-family homes. In
most areas, the local municipality’s
Building Department examines plans,
issues permits, and does inspections for
systems regulated under the
OBC.
In
some areas, this approval responsibility
has been delegated to local
Conservation Authorities or Health Units.
The Municipal Building Department will
be able to r
edirect inquiries.
Proper approvals under the
OBC
must
be obtained by the homeowner before
installing any of the suggestions for
improving system performance, or the new
design ideas presented in this booklet.
Where To Go For Approvals
Anyone in the business of installing,
repairing, emptying, cleaning or servicing
septic systems must be licensed by the
Ontario Ministry of Municipal Affairs and
Housing. Licensed installers must have
qualified personnel supervising all projects.
Pumpers are licensed in Ontario by the
Ministr
y of the Environment.
Ask To See The License
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