An electromechanical device that provides audible and visual indication
that the water level in a pump or holding tank is above recommended levels.
Alternating leach field
One of two or more leach fields designed to be used while the other(s)
rest. They are generally fed via a manually operated diverter valve located
in the line from the septic tank.
Pipe tees or partitions within a septic tank which reduce turbulence at
the inlet and prevent floating grease and scum from escaping into the
leaching system at the outlet. (They are usually the first part of a steel
tank to rust away, leaving the leach field or drywell unprotected from
excessive solids overloading.)
The original type of sewage system, often still in use in older homes.
They were simply a single hole in the ground loosely blocked up with locally
available materials - stone, brick, block, or railroad ties - and capped
either with ties covered with a layer of old steel roofing or a
cast-in-place concrete lid with a cleanout hole near the center. All
household wastewater entered and the liquid portion was absorbed into the
ground. When the soil plugged, a new cesspool was added. Wiser installers
placed an elbow, or better still, a tee in the outlet pipe from the first
cesspool, creating a baffle to hold back floating grease and scum.
In a sense, this created the first type of septic system, because the
first cesspool in the line, sealed by its own demise, served as a septic
tank and the subsequent tank provided a greater degree of settling and
separation of soil-plugging solids and some absorption. (Owners often have
the first tank pumped out to maintain system operation.)
Open-bottomed pre-cast concrete or plastic structures placed next to each
other in an excavation to take the place of crushed stone in a leach field.
Unlike leach fields, heavy-duty chambers can be driven over.
A removable plug in a "wye," or a "tee" in a sewer line where a snake can
be inserted to clear a blockage.
Distribution box or D-box
Usually a small square concrete box within a leach field from which all
pipes lead to disperse effluent within the field. Newer boxes should be
marked at the surface to protect from vehicle traffic.
Constructed identically to a cesspool and differs only in that the
clarified effluent from a septic tank or the wastewater from a washing
machine or other grey water may enter. Modern drywells are often pre-cast
perforated rings surrounded by crushed stone to increase the absorption
area. Drywells can also be used to return storm water to the ground or to
relocate basement drainage water to another location above the water table.
Drywells are not commonly installed today because of laws requiring the
bottom of a leaching system to be 4 feet above the seasonal high-water
A water supply well that is simply a hole in the ground lined with stone,
brick, concrete, plastic or steel to hold its shape. The lower portion of
the lining is perforated, or pierced, to let in water from the Aquifer or
ground water table. The upper portion of the lining is water tight to keep
surface water from entering and contaminating the well. Dug wells are often
called shallow wells to differentiate them from drilled or driven wells that
extend much deeper into the ground. Dug wells in our area are often a
minimum of ten feet or so into the ground and a maximum of 20 to 25 feet, a
practical and safe limit for machines to dig.
Shallow wells for water supply are very similar in concept to dry wells
which return wastewater or rain water back to the ground. Both are designed
to exchange water between the structure and the soil. The major difference
is that water wells are purposely built into the ground water table and dry
wells are built above the water table to keep wastewater from entering
The clearish liquid that flows out of the septic tank after the tank has
"taken out the big pieces."
Filter Fabric: Synthetic cloth-like material that is used for several
different types of construction-related applications such as erosion
control, road stabilization and soil separation. Can consist of either woven
or non-woven fibers of varying thickness and weight. Available in 12 to 15
foot wide rolls, several hundred feet in length. Woven fabrics (usually
black) resemble the modern day grain bags while non-woven fabrics can
resemble a range of materials from soft felts to the stiff shiny house wrap
(to which they are closely related) usually seen enveloping homes under
An in-ground chamber similar to a septic tank, usually used at
restaurants, markets and inns to trap grease from the kitchen wastewater
before it reaches the septic tank. Unusual to find in private homes.
All liquid wastewater except for the toilet wastes (sink, shower, washer,
The part of a septic system that returns water to the ground for
re-absorption. Could be a drywell, leach field, trench, chamber, etc.
A leaching system consisting of a continuous layer of crushed stone about
a foot deep -- usually in a rectangular layout -- with perforated pipes laid
level throughout to disperse effluent as evenly as possible over the entire
Term often used to describe either a leach bed or leach trenches.
Built essentially like beds, except that each pipe is in its own
stone-filled level trench, usually 3 feet wide. Each trench can be at a
different level than the other trenches. Well suited to sloping ground.
Mound (or raised) system
A leach bed built on a mound of fine to medium-grained sand to elevate it
above the seasonal high water table and/or to accommodate a system on a
A shallow, hand-dug hole saturated with water, performed as a part of a
septic design to determine the soils permeability - the rate at which water
is absorbed by the soil - which dictates the system size.
Pump station, 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
leaching system. Pump tanks often are hooked to an alarm to warn of pump
Seasonal high water table
The highest elevation that groundwater reaches within the year (usually
in the spring). Many states require the bottom of a leaching system to be at
least 4 feet above this point.
Usually consists of a topographic survey, test pit, and percolation test
plus information about the water supply and subdivision and a filing fee to
the state prepared by either a licensed designer or the owner.
A watertight chamber, which all household wastewater enters for settling
and anaerobic digestion of greases and solids. Original tanks were made of
asphalt-coated steel. Modern tanks are made of concrete, fiberglass, or
plastic. All tanks should have a set of baffles, which are critical to their
Most tanks have and inspection hatch ot both the inlet and the outlet and
some have a third hatch in between for pumping access. Locations of each of
these should be recorded and/or marked. Steel tanks often have one round lid
that covers the entire tank.
Septic tanks should be pumped every three years or so in normal
operation. They should not be treated with any additives and should be
protected from receiving any of the harmful chemicals used in many homes and
commercial workshops. This includes disinfectants or bleaches, which can
kill bacteria in the tank, and solvents, darkroom chemicals, or other
materials that could pollute the water supply.
A hole dug to determine soil type, seasonal high water table, and depth
to ledge. Some states require a test pit of specific depth (to determine
that ledge is a minimum number of feet below bed bottom) while others
require only a shallow pit to determine depth to hardpan soils.