Septic Systems: Introduction, Definitions - New York State Septic System Design Regulations 75-A.1 -
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Section 1 of the septic design regulations includes definitions of common septic system terms.
This document uses the New York State wastewater treatment standard for individual household septic systems
(Appendix 75-A) to provide an example of state regulated design and installation of both conventional
tank and leach field septic systems and alternative septic system
designs, including raised septic systems, septic mound systems, intermittent sand filter septic systems,
and evaportion-transpiration septic systems.
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For a more complete list of septic system
terms and definitions than that provided immediately below by the State, see our
Dictionary of Septic System and Onsite Wastewater Terms. What follows below are specific definitions used in the
Appendix 75-A.1 by New York State's regulation. These definitions are a subset of our larger septic dictionary.
Title: Appendix 75-A.1 - Introduction - Effective Date: 12/01/90
Section 75-A.1 Introduction. Septic System Terms and Definitions
(a) This appendix applies to on-site wastewater treatment systems
serving residential properties and receiving sewage without the
admixture of industrial wastes or other wastes, as defined in
Environmental Conservation Law, Section 17-0701, in quantities of less
than 1,000 gallons per day (gpd).
(b) Definitions - As used in this Appendix, the following words and
terms shall have the indicated meaning:
(1) Absorption Area - an area to which wastewater is distributed for
infiltration to the soil.
(2) Absorption Field - the area to which sewage is distributed for
infiltration to the soil by means of a network of pipes.
(3) Absorption Trench - a long narrow area which includes a pipe for the
distribution of septic tank effluent.
(4) Aerobic Treatment Unit - a system that provides for the biological
decomposition of the organic portion of the wastewater by mechanical
aeration of the wastewater.
(5) Aggregate - washed gravel or crushed stone 3/4 - 1 1/2 inches in
diameter.
(6) Application Rate - the rate at which septic tank effluent is applied
to a subsurface absorption area, for design purposes, expressed in
gallons per day per square foot (gpd/sq. ft.).
(7) Baffle - a flow deflecting device used in septic tanks and
distribution boxes to inhibit the discharge of floating solids, reduce
the amount of settleable solids that exit, and reduce the exit velocity
of the wastewater.
(8) Building Sewer - that part of the drainage system which extends from
the end of the building drain and conveys wastewater to the sewage
system or sewer.
(9) Cleanout - an opening providing access to part of the sewage system.
(10) Commissioner - the State Commissioner of Health.
(11) Curtain Drain - a subsurface drain designed and constructed to
control groundwater and surface water intrusion into the area of the
sewage system.
(12) Design Professional - a person licensed or registered in the State
of New York and authorized by the State Education Law to design the
systems described in the standards.
(13) Distribution Device - a device used to uniformly distribute sewage
to the absorption area.
(14) Distribution Line - the perforated pipe used to distribute
wastewater to the absorption area.
(15) Drinking Water - water whose physical, chemical and biological
quality is or is intended to be satisfactory for human consumption, food
preparation or culinary purposes.
(16) Effective Grain Size - a measure of the diameter of soil particles,
when compared to a theoretical material having an equal transmission
constant. It is the dimensions of that mesh screen which will permit 10
percent of the sample to pass and will retain 90 percent.
(17) Gas Baffle - a device on the outlet of a septic tank which deflects
gas bubbles away from the outlet and reduces the carry over of solid
particles from the septic tank.
(18) Groundwater - subsurface water occupying the saturation zone from
which wells and springs are fed.
(19) Heavy Equipment - all equipment which would result in the
compaction of the design absorption area at a depth equivalent to the
design depth of the distribution lines.
(20) Infiltration - the flow or movement of water into the interstices
or pores of a soil through the soil interface.
(21) Invert - the floor, bottom, or lowest point of the inside cross
section of a pipe.
(22) Local Health Department - a city, county, or part-county department
of health or a State Department of Health District Office.
(23) Percolation - the movement of water through the pores of a soil or
other porous medium following infiltration through the soil interface.
(24) Permeability - a measure of the rate of movement of liquid through
soil.
(25) Scum - the wastewater material which is less dense than water and
floats on top of the water.
(26) Sewage - the combination of human and household waste with water
which is discharged to the home plumbing system including the waste from
a flush toilet, bath, sink, lavatory, dishwashing or laundry machine, or
the water-carried waste from any other fixture, equipment or machine.
(27) Stabilized Rate of Percolation - the rate corresponding to two
consecutive equal or near equal percolation test results.
(28) Useable Soil - unless otherwise stated a soil with a percolation
rate of faster than 60 min/in with a compatible soil classification.
(29) Wastewater - any water discharged from a house through a plumbing
fixture to include, but not limited to, sewage and any water or waste
from a device (e.g., water softener brine) which is produced in the
house or property.
(30) Watercourse - a visible path through which surface water travels on
a regular basis. Drainage areas which contain water only during and
immediately after a rainstorm shall not be considered a watercourse.
(31) Watershed - an area of drainage for a body of water that serves as
a source of drinking water and for which watershed rules and regulations
have been adopted by the commissioner.
(32) Well head area - the area surrounding a well which includes the
cone of influence (where the drawdown of groundwater causes groundwater
flow).
(33) Wetland - an area(s) of marshes or swamps which have been
designated as such by the State Department of Environmental Conservation
or other agency having jurisdiction. Marshes or swamps that have not
been classified by an agency as a wetland shall not be treated for
design purposes as a wetland.
For a more complete list of septic system
terms and definitions than that provided above by the State, see our Dictionary of Septic System and Onsite Wastewater Terms
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