Environmental Health
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Hazardous Waste Definitions  l  Septic System Definitions


Closed Record Appeal
An administrative appeal to the Board of Health following an open record hearing. This appeal is on the record and no new evidence can be submitted.
Open Record Hearing
A hearing conducted by the Hearing Officer that creates the record through testimony and submission of evidence and information.

Drinking / Surface Water Definitions

Fecal coliform
Bacteria found in the digestive systems of warm-blooded animals; their presence in water tests indicate potential contamination from sewage. For information on water testing, see Water Quality Lab.
A subsurface water occupying the zone of saturated soil, permanently, seasonally, or as the result of the tides.
Surface water
Any body of water, whether fresh or marine, flowing or contained in natural or artificial unlined depressions continuously for at least four consecutive months, including natural and artificial lakes, ponds, springs, rivers, streams, swamps, marshes, and tidal waters.

Gardening Definitions

Common Sense Gardening
Encourages gardeners to conserve water, to use alternatives to pesticides, and to choose less-toxic pesticides when necessary. By taking action to reduce the use of pesticides and synthetic fertilizers and conserve water, Common Sense Gardeners protect our lakes, streams, rivers, and Puget Sound. For additional information, see Common Sense Gardening.
Integrated Pest Management (IPM)
The IPM approach emphasizes physical, mechanical, cultural, and biological tactics to keep pest and vegetation problems low enough to limit or eliminate the reliance on chemical control.

Hazardous Waste Definitions

Toxicity Categories I, II, and III
Pesticides are classified by the US. Environmental Protection Agency (EPA) into categories according to their toxicity. These categories are based on tests that determine acute health effects. A prominently displayed "signal word" is required on pesticide labels which reflects the toxicity category of the product. The following categories, with their signal words, are listed in order from most toxic to least toxic:
  • Category I (highly toxic) signal words: DANGER or DANGER/POISON
  • Category II (moderately toxic) signal word: WARNING
  • Category III (slightly toxic) signal word: CAUTION
  • Category IV (relatively nontoxic) signal word: CAUTION
For additional pesticide info, see Pesticides.
Nonpoint Pollution
Refers to pollution that enters any waters from any land-based or water-based activities including, but not limited to, atmospheric discharges; surface water runoff from agricultural lands, urban areas, or forest lands; subsurface or underground sources or discharges from boats or marine vessels. See the Nonpoint Source Pollution Ordinance for more information.
Secondary Containment
A liquid-tight barrier that will adequately contain hazardous materials released from a storage container, such as placing a 5-gallon drum (primary containment) inside a 55-gallon drum (secondary containment). For additional information, see Secondary Containment [PDF].
Small Quantity Generator (SQG)
A business that produces less than 220 pounds of hazardous waste per month. For additional information, see Small Quantity Generator Program.

Septic System Definitions

A commercial product added to a septic system intended to affect the performance or aesthetics of the septic system. To find out why additives are not necessary, see Septic System Additives.
Alternative system
A septic system other than a conventional gravity system or pressure distribution system.
(see Record Drawing)
An engineer, a registered sanitarian, or a person who is certified by the county to perform site and soils evaluations and to develop and submit designs by matching site and soil characteristics with appropriate technology. For a list of septic system designers, see Septic System Professionals.
Dye Trace
A dye trace can detect septic system leaks. The dye testing involves flushing a non-toxic tracer dye down a toilet and placing charcoal packets downhill of the septic system to collect any dye that may be leaking (with the sewage) from the system.
The liquid discharged from a septic tank or other on-site sewage system component.
Failure (failing system)
A condition of a septic system that threatens the public health by inadequately treating sewage or by creating a potential for direct or indirect contact between sewage and the public. For additional information on failing systems, see What Can Go Wrong?
A person approved by the County to install septic systems or components. For a list of septic system installers, see Septic System Professionals.
Periodic checking of a septic system and is performed by observations and measurements to determine if the system is functioning or needs maintenance; monitoring also includes accurate records that document monitoring activities. For additional information, see Septic System Operation and Maintenance.
Monitoring specialist
A person certified by the county to operate, maintain, and/or monitor a septic
system. For a list of septic system monitoring specialists, see Septic System Professionals.
On-site sewage system
Another name for a septic system. For more information about septic systems, see Septic System Program.
Abbreviation for on-site sewage system.
Operational Certificate
A certificate issued for a specified period by the County to a person for the operation and/or use of an on-site sewage system. The operational certificate shall contain conditions for the operation, maintenance and monitoring of the subject on-site sewage system. For additional information, see Operational Certificate.
A permit issued by the County after reviewing and concluding an application for an On-site Sewage System meets all county regulations.
Pressure distribution
A type of septic system that uses pressure to distribute effluent uniformly over the drainfield and is used when shallow placement of the drainfield is necessary. For additional information, see Understanding and Caring for Your Pressure Distribution System [PDF].
Professional Engineer
A person licensed as an engineer and is qualified to evaluate soil suitability and subsequently design an appropriate septic system. For a list of septic system designers, see Septic System Professionals.
A person meeting County requirements to remove and transport sewage or septage from a septic system. For a list of septic system pumpers, see Septic System Professionals.
Record drawing
A diagram showing where your septic system components are located; previously known as an "as-built". Depending on when your septic system was installed, the quality and detail of record drawings vary greatly. An older diagram (prior to 1980) may be a very rough, simple sketch showing the layout of your system. A newer diagram will show the tank, drainfield, replacement area (for future use if a replacement field is needed), and any other components of your system.

You can request a copy of the record drawing [PDF] from the Thurston County Building Development Center (BDC), 360-786-5490. The BDC is located at 2000 Lakeridge Dr. SW, Olympia, on the second floor of Building 1. When you call or visit, please have your eleven-digit tax parcel number ready. This is the number that appears on your county tax statements. (If you do not have your tax parcel number, contact the County Assessor's office at 360-786-5410.)
Restoration, by reconstruction, addition to, or modification or replacement of an existing septic system or component of the system due to failure.
Reserve area
An area of land approved for the installation of an OSS and dedicated for replacement of the OSS upon its failure. For additional information, see Drainfield.
Risers give easy access to a septic system without disturbing the soil above the tank. To eliminate the time and nuisance of digging down to access the covers, risers can be installed. The riser(s) should be secure to prevent accidental entry into the tank, and should also be watertight to prevent groundwater from entering the riser cavity, which may cause the tank to flood.
Grease, fats, and material that floats to the top of the septic tank.
The mixture of solid wastes, scum, sludge, and liquids pumped from within septic tanks, pump chambers, holding tanks, and other OSS components.
Septic tank
A watertight pretreatment receptacle receiving the discharge of sewage from a building sewer or sewers, designed and constructed to permit separation of settling and floating solids from the liquid, detention and anaerobic digestion of the organic matter, prior to discharge of the liquid. For additional information, see Septic System Basics.
Any urine, feces, and the water carrying human wastes, including kitchen, bath, and laundry wastes from residences, buildings, industrial establishments, or other places. Sewage is generally synonymous with wastewater.
Heavy solids, grit and sand which falls to the bottom of the septic tank.
Popular Pages & Links
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This page last updated: 03/31/22