| Glossary
of terms:
A
B C
D E
F G
H I
L M
N O
P R
S T
U W
A
As-Built Plan: The plan that depicts a septic
system (including dimensions, distances from dwellings,
roads, surface water, wells) as it was built by a licensed
septic installer. A copy of this plan should be on file
with the local board of health and/or building permit
office. It supplies the background information required
by an Inspector to evaluate the design/siting of the system
and subsequent performance.
Average Daily Flow: The average amount
of wastewater that enters a septic system over a 24 hour
period, measured in gallons.
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B
Bacteria: Single-celled microscopic organisms.
Some bacteria are capable of causing human, animal or
plant diseases; others are essential in wastewater treatment
and pollution control because they break-down organic
matter in air and water.
Biochemical Oxygen Demand: The amount
of oxygen organisms in wastewater require to decompose
organic matter (under standard aerobic conditions). Used
as a measure of the amount of organic matter (pollutants)
in wastewater, and hence as an indicator of water quality
and the performance of wastewater treatment systems. Generally
measured in mg/L.
Biological Filter: A bed of sand, gravel,
peat moss, C25or other medium through which wastewater
flows or trickles, which relies on the biological action
of
microorganisms for its effectiveness in treating wastewater.
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C
Cesspool: A lined or partially lined underground
pit into which raw household wastewater is discharged
and from which the liquid seeps into the surrounding soil.
Cesspools were the original type of sewage system, and
are often still in use in older homes
Chlorination: The application or chlorine
or chlorine compounds to water or wastewater, generally
for the purpose of disinfection, but frequently for chemical
oxidation and odor control.
Chlorine Disinfection: Chlorine is the
most widely used wastewater disinfectant in the U.S. It
kills most bacteria, viruses and other microorganisms
that cause disease. Chlorine is introduced to wastewater
in the form of gas, hypochlorites (tablets, solutions
or powder) and other compounds. The different forms of
chlorine used at wastewater treatment plants include gaseous
chlorine, sodium hypochlorite solution, calcium hypochlorite
and bromium chloride
Clean Water Act: Water pollution control
laws based upon the Federal Water Pollution Control Act
of 1972 with amendments passed in 1977, 1981, and 1987.
The main objective of the Clean Water Act is to restore
and maintain the "chemical, physical, and biological
integrity of the Nation's waters."
Cluster System: A wastewater collection
and treatment system that serves two or more dwellings,
but less than an entire community. Individual septic tanks
or aerobic units may pretreat wastewater from several
homes before it is transported through low cost, Alternative
Sewers to a treatment unit that is relatively small compared
to centralized systems
Commercial Septic System: Septic system
serving a commercial establishment (e.g., retail/office,
restaurant or industrial) rather than a residence. Commercial
septic systems require larger capacity septic tanks (e.g.,
up to 5,000 or more) to handle higher daily volumes of
wastewater flows. Commercial systems (particularly those
serving restaurants) may include a grease trap to remove
greases and oils before they enter the septic tank
Constructed Wetlands: In wastewater treatment,
wetlands designed and built to simulate the water purification
ability of natural wetlands. The roots and stems of introduced
wetland plants form a dense mat where biological and physical
processes occur to treat the wastewater. Constructed wetlands
are used to treat domestic,
agricultural, industrial and mining wastewaters
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D
Decentralized System: An onsite or cluster wastewater
system that is used to treat and dispose of relatively
small volumes of wastewater, generally originating from
individual or groups of dwellings and businesses that
are located relatively close together.
Decentralized Wastewater Management:
Active oversight of multiple on-site or cluster wastewater
treatment systems in a state or local area through regulatory
control, licensing, financing assistance and other means,
with the intention of protecting the environment and public
health, and achieving water quality goals.
Dechlorination: The process of removing
the chlorine residue from chlorinated wastewater prior
to discharge into the environment. Dechlorination is required
by most states to minimize the negative effects of chlorine
on aquatic life and the environment.
Distribution Box: Usually a small square
concrete box between the septic tank and leachfield whose
purpose is to disperse effluent evenly across the leachfield.
The Box typically has a single inlet (from the septic
tank) and several outlets that lead to individual drainfield
trenches; baffles are used to reduce wastewater velocity.
Drainfield: Part of the septic system:
the area of ground and system of subsurface pipes or chambers
into which partially treated wastewater from the septic
tank or alternative system is discharged for final treatment
and absorption by soil. Also called Leachfield or Absorption
Field
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E
Effluent: Wastewater, partially or completely
treated, flowing out of a reservoir, tank, treatment component
or disposal component. Effluent from a septic tank is
the partially treated clearish liquid that flows into
the absorption field for final treatment.
Environmental Protection Agency (EPA):
A Federal agency established in 1970 who's mission is
to protect and safeguard the health of environment (air,
water, and land) in which we live.www.epa.gov
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F
Failure: The inability of a septic system to
accept and adequately treat wastewater, leading to environmental
contamination and health hazards. Signs of septic failure
include system back-ups, soft mushy spots, patches of
lush grass or pooling of wastewater in the homeowner's
backyard, high bacterial counts in well-water and excessive
weed growth/algal blooms in nearby lakes and ponds. Premature
septic failure (i.e., failure at some point before a system's
design life of 20-30 years) can be caused by a variety
of factors, including root damage to the leachfield, saturation
of soil by storm water, improper siting and poor original
design and/or installation. The most common reason for
early septic system failure, however, is improper maintenance.
When a system is poorly maintained and not pumped out
on a regular basis, sludge (solid material) builds up
inside the septic tank, then flows into the leachfield,
clogging it beyond repair.
Fecal Coliform: A sub-group of coliforms,
found almost exclusively in the intestinal wastes of humans
and animals, and seldom found elsewhere in the environment.
If detected in water, good indicator that the water has
been contaminated by sewage or improperly treated wastewater
and therefore may contain disease-causing organisms. Fecal
coliforms measured in colonies/100 mL. Water containing
fecal coliforms is unsafe to drink
Flow Design: The way and the rate in
which wastewater is received by and flows through a wastewater
treatment system. Continuous flow designs simply allow
the wastewater to flow through the unit at the same rate
that it leaves the home. Other designs employ devices
(e.g., pretreatment tanks, surge chambers and baffles)
to control the amount and rate of the incoming flow. Batch
process designs use pumps or siphons to control the amount
of wastewater entering a treatment tank and/or to discharge
the treated wastewater in controlled amounts after a certain
period of time. Controlling the flow of wastewater helps
preserve the quality of treatment
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G
Grease Trap: An in-ground chamber similar to
a septic tank, usually used at restaurants, markets, cafeterias
and institutional kitchens, designed to trap grease from
kitchen wastewater before it reaches the septic tank.
A grease trap is necessary to prevent grease and other
fatty substances from entering into the septic tank and
from there being carried over to the leachfield, potentially
causing clogging and system failure. Grease traps should
be cleaned out frequently (anywhere from once a week to
once every 2-3 months) by a licensed pumper. Grease traps
are unusual to find in residential septic systems
Groundwater: In general usage, fresh
water beneath the ground surface which supplies wells
and springs. In technical usage, the water below the water
table contained in void spaces (e.g., pore spaces between
rock and soil particles, bedrock fractures).
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H
Home Aerobic Wastewater Treatment: Wastewater
treatment method that requires the presence of oxygen,
in contrast to the anaerobic (in the absence of oxygen)
treatment process that occurs in a septic tank. Aerobic
treatment units use a mechanism to inject and circulate
air inside the treatment tank, to aid biological decomposition
of wastewater.
Hydraulic Load: The volume of wastewater
(gallons/day) that enters the septic system through as
a result of household activities. Can also refer to the
volume of water (storm water, roof run-off) that drains
onto the leachfield, typically as a result of improper
siting. Hydraulic load is a critical determinant of a
septic system's longevity and proper functioning; chronic
Hydraulic Overload can result in system failure
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I
Influent:- Wastewater, partially or completely
treated, or in its natural state (raw wastewater) that
flows into a reservoir, tank, treatment component or disposal
component.
Installation: In onsite wastewater management,
the construction of a septic system by a licensed septic
installer, following an Approved Plan of the system's
design. Property owners (e.g., homeowners or builders)
need to secure a Septic Permit from the local board of
health before installation can begin
Installer:In onsite wastewater management, the person
licensed to install or construct, repair or extend septic
systems. The installer ensures that all installation work
is done in accordance with the design prepared by a licensed
Designer/Engineer and that the required inspection(s)
are performed. The Installer maintains As-Built records
of installation work provided.
Intermittent Sand Filter: Wastewater
treatment system in which effluent receives primary treatment
from the septic tank or aerobic treatment unit, then is
pumped from the septic tank or a separate dosing tank
and distributed evenly over a sand filter bed. As wastewater
passes through the sand filter, microorganisms attached
to the filter media provide treatment. The treated wastewater
is then transported to a line for further treatment or
disposal.
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L
Leachfield: Part of the septic system: the area
of ground and system of subsurface pipes or chambers into
which partially treated wastewater from the septic tank
or alternative system is discharged for final treatment
and absorption by soil. Also called Drainfield or Absorption
Field.
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M
Maintenance Contract: A contract between the
homeowner/commercial septic owner and a licensed septic
operator for the purpose of providing regular inspections
and pumpings. Required in many states/localities for alternative
systems; to-date frequently optional (but a good idea)
for conventional systems.
Mound System: Pressure-dosed sand filters
placed above, and discharging directly to, the natural
soil. Their main purpose is to provide additional treatment
to the wastewater before it enters the natural environment.
Mound systems are designed to overcome site restrictions
such as slow or fast permeability soils, shallow soil
cover over creviced or porous bedrock and a high water
table. Mound systems consist of 1. a pretreatment unit
(usually a septic tank) that removes solids from wastewater,
2. a dosing chamber that contains a pressure pump used
to evenly distribute wastewater over the infiltration
surface of the mound and 3. the mound itself, over which
effluent is distributed, then through which it trickles
down to the sand media and from there into the natural
soil below. Treatment occurs through physical, biological,
and chemical means as the wastewater filters down through
the sand and the natural soil.
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N
Nitrate: The soluble form of nitrogen which acts
as a fertilizer to plants and is a mild toxin to humans
Nitrification: An aerobic process in
which bacteria change the ammonia and organic nitrogen
in wastewater into oxidized nitrogen (usually nitrate).
This is one step in a process that serves to convert nitrogen
into a form which enables its removal.
Nitrogen: An essential nutrient that
is often present in wastewater as ammonia, nitrate/nitrite
or organic nitrogen.
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O
Offsite Disposal: Disposal of wastewater away
from the home or commercial site, for example, at a municipal
treatment plant.
Onsite Disposal: Disposal of wastewater
in close proximity to the home or commercial site, for
example, by a septic system.
Onsite System: A natural system or mechanical
device used to collect, treat and discharge or reclaim
wastewater from an individual dwelling, business establishment
or small community without the use of community-wide sewers
or a centralized treatment facility. A conventional onsite
system includes a septic tank and a leachfield. Alternative
onsite systems include mound systems, sand filters and
low-pressure pipe systems
Operation and Maintenance: A schedule
for septic system maintenance which follows recommended
inspection and pumping frequencies. An schedule is important
for the proper functioning and longevity of all septic
systems, and even more so for alternative systems such
as fine bubble aerators that have greater
maintenance requirements.
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P
Permeability: The relative ease (or lack thereof)
with which water moves downward through soil. Permeability
is measured in inches per hour. The permeability of soil
is a critical factor in the suitability/sizing of a leachfield
for a particular site.
Pretreatment: The first stage of wastewater
treatment in which solid materials (e.g., greases, oils,
toilet paper, organic matter) are allowed to settle out.
Pretreatment methods include the septic tank, grease trap
and other settling units. Pretreatment must always be
followed by additional biological and/or chemical treatment
to remove additional solids, nutrients and pathogens,
and render wastewater safe for release into the environment
Primary Treatment: The fist stage of
wastewater treatment, consisting of the removal of a substantial
amount of suspended matter (but little or no dissolved
matter) via sedimentation/settling. This is the process
that occurs inside the septic tank, during which wastewater
settles out into three layers: heavier solids (sludge),
partially treated, clearish liquid wastewater (effluent)
and lighter solids (scum). Primary treatment must be followed
by further treatment to achieve acceptable levels of water
quality
Private Well: A groundwater source serving
a single residence.
Pump Tank: A watertight container, usually
(but not always) separate from the septic tank, into which
effluent flows by gravity and is then ejected by a submersible
electric pump through a pressure line to the leachfield.
Pump tanks often are hooked to an alarm to warn of pump
failure.
Pumping: In onsite wastewater management,
the periodic (e.g., every 3-5 years) cleaning-out of a
septic tank by a licensed septic pumper/solid waste hauler.
Pumping is performed by a vacuum device that removes solid
wastes from the tank and deposits them into the pumper's
truck for hauling to an authorized disposal site. Regular
pumping is required to prevent the excessive accumulation
of sludge and scum and to ensure the proper functioning
of the septic tank in pretreating wastewater
Pumping Frequency: The frequency with
which septic tanks require removal of sludge and scum
to prevent excessive build-up and to ensure the proper
functioning of the septic tank in pretreating wastewater.
The septic industry has developed guidelines for pumping
frequency based on the size of the septic tank, household
occupancy and certain household practices (e.g., use of
a garbage disposal). Generally speaking, septic tanks
should be pumped out at least every 3-5 years in normal
operation. The use of commercially available septic tank
additives does not eliminate the need for pumping, and
may in fact harm the septic system.
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R
Raw Sewage: Household or commercial wastewater
that has not yet received any treatment. Raw sewage is
what flows into wastewater treatment systems, e.g., the
septic tank in an onsite wastewater treatment system.
Recirculating Sand Filter: A modified
version of the old-fashioned, single-pass open sand filter
designed to alleviate the odor problems associated with
dosing partially treated wastewater over a sand filter.
The noxious odors are eliminated through recirculation,
which increases the oxygen content in the treated wastewater
that is sprayed over the filter bed. They require less
land area than intermittent (single-pass) sand filters
and do not require highly trained operators; they are
often used to treat wastewater collected from clustered
residences and small communities.
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S
Sand Filter: Constructed beds of sand or other
suitable granular material usually two to three feet deep.
The filter materials (called media) are sometimes contained
in a liner made of concrete, plastic or other impermeable
material. Depending on the design, the filter may be situated
above ground, partially above ground or below ground,
and the filter surface may be open or covered. Partially
treated wastewater (e.g., from a septic tank) is applied
to the filter surface and receives treatment as it slowly
trickles through the media. In most sand filters, the
wastewater then collects in an underdrain and flows to
further treatment and/or disposal, e.g., to a leachfield
Secondary Treatment: The wastewater treatment
that follows settling in a septic tank or treatment by
an aeration system that removes biodegradable organic
materials and suspended solids. Leachfield absorption
is an example of secondary treatment
Septic Permit: Permit issued by the state
environmental bureau or by the local health department
authorizing construction or modification of a septic system
on a particular site in line with the design developed
by a sanitarian, plumber or engineer, following a site
evaluation and pit/percolation tests of the soil.
Septic System: A system for treating
wastewater from an individual home or business, or a group
of homes or businesses that relies on natural anaerobic
and aerobic bacterial decomposition processes to treat
wastewater and return it to the environment. A conventional
onsite septic system consists of a gravity-fed septic
tank designed to separate solid matter from liquid effluent,
and a gravity-fed leachfield whose soils absorb and further
treat effluent. Properly designed and maintained, a septic
system can effectively and naturally treat wastewater
for 20-30 years
Septic Tank: Typically the first component
of an onsite wastewater treatment system, used by 25%
of new homes in the USA, providing wastewater treatment
via settling and anaerobic processes. The septic tank
is a watertight rectangular structure generally composed
of fiberglass or cast concrete and buried underground
10-15 feet behind or to the side of the dwelling it serves.
Wastewater from the dwelling flows into the septic tank
and settles out into heavier solids (sludge), lighter
solids (scum) and a middle layer of partially clarified
effluent. Effluent exits the septic tank to a line which
transports it to a secondary treatment system, typically
a leachfield, where it is distributed underground and
absorbed and treated by microorganisms in the soil. Held-over
solids accumulate in the tank, where they are partially
decomposed by bacteria, but require periodic (e.g., every
3-5 years) pumpings to prevent excessive build-up and
diminished septic tank performance. Proper septic tank
sizing is one key factor in the proper functioning of
a septic system. Septic tanks are sized according to the
number of bedrooms in a house (a proxy for the number
of occupants) in addition to other factors such as the
presence of a garbage disposal. Industry standards exist:
for example, septic tanks serving houses with 1-3 bedrooms
are mandated to be at least 1,000 gallons in capacity
Site Evaluation: Examination of the soils,
landscape features, topography and past surveys of a given
site being considered for installation of an onsite wastewater
treatment system. Carried out by a sanitarian, soil scientist,
engineer and/or other wastewater professional. In most
communities, this site evaluation must take place before
a homeowner or developer can apply for and obtain a permit
to install a septic system or other alternative wastewater
treatment system on a particular piece of property
Soil Aeration: The exchange of air in
soil with air from the atmosphere. The air in well aerated
soil is similar to that in the atmosphere; the air in
poorly aerated soil is considerably higher in carbon dioxide
and lower in oxygen
Surface Water: All water naturally open
to the atmosphere (rivers, lakes, reservoirs, ponds, streams,
seas, estuaries) and all springs, wells or other collectors
directly influenced by surface water.
Suspended Solids: Small particles of
solid material (pollutants) suspended or dispersed in
wastewater. Septic tank outlets are often fitted with
filters to minimize the amount of suspended solids that
enter the drainfield. Total Suspended Solids is one important
measure of water quality/pollution level and hence treatment
system performance.
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T
Total Suspended Solids: Measure of the small
particles of solid material (pollutants) suspended or
dispersed in wastewater. Used as one index of water quality/pollution
level and hence treatment system performance, often in
conjunction with Biochemical Oxygen Demand (BOD). Usually
measured in mg/L
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U
Ultraviolet Disinfection: A final treatment method
in which partially treated effluent is exposed to ultraviolet
light to kill pathogens and microorganisms
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W
Wastewater: The spent or used water from an individual
household, a community or commercial establishment which
contains dissolved and suspended matter that is harmful
to human health and the environment. Wastewater requires
treatment to remove bacteria and pathogens, either through
an onsite decentralized wastewater treatment system or
a centralized municipal sewage system, before it can safely
be released into the environment. Household wastewater
includes liquid-solid mixtures from toilets, sinks, showers,
bathtubs, washing machines, dishwashers and other drains.
Wastewater Reclamation: Processing of
wastewater for reuse, such as through a graywater system.
Water Conservation: Practices designed
to reduce the demand for water, improve efficiency in
water usage and reduce losses and waste of water
Water Quality: The physical, biological
and chemical properties of the water that determine its
suitability for human use and/or for its role in the Biosphere.
In wastewater treatment, water quality measures indicate
the performance of the treatment system. The measures
that are most important for this purpose including Biochemical
Oxygen Demand (BOD) and Total Suspended Solids (TSS).
High values for either measure indicate poorly treated
wastewater which can degrade the quality of receiving
waters
Watershed: Geographic area in which all
sources of water, including lakes, rivers, estuaries,
wetlands and streams, as well as ground water, drain to
a common surface water body. Watersheds can be a few square
miles to millions of square miles, and include agricultural,
suburban, urban and coastal areas/land uses
Wetlands: Naturally occurring areas that
are regularly wet or flooded and have a water table that
stands at or above the land surface for at least part
of the year. Coastal wetlands extend back from estuaries
and include salt marshes, tidal basins, marshes and mangrove
swamps. Inland freshwater wetlands consist of swamps,
marshes and bogs. Constructed Wetlands are water treatment
systems that recreate the conditions of natural wetlands
for the purpose of purifying wastewater.
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