Wyoming Administrative Code
Agency 020 - Environmental Quality, Dept. of
Sub-Agency 0011 - Water Quality
Chapter 25 - SEPTIC TANKS, SOIL ABSORPTION SYSTEMS, AND OTHER SMALL WASTEWATER SYSTEMS
Section 25-4 - Definitions

(a) "100 year floodplain" means a tract of land throughout a watershed that has a one-in-one hundred chance or occurrence of flooding in any given year or a return period of once every 100 years , as determined by the United States Geological Survey (USGS), Federal Emergency Management Agency (FEMA) or a local planning and development authority.

(b) "Absorption surface" means the interface where treated effluent infiltrates into native or fill soil.

(c) "Bed" means a soil treatment and dispersal system where the width is greater than three (3) feet.

(d) "Bedrock" means geological layers, of which greater than fifty percent (50%) by volume consist of unweathered in-place consolidated rock or rock fragments. Bedrock also means weathered in-place rock that cannot be hand augered or penetrated with a knife blade.

(e) "Bedroom" means any room that is or may be used for sleeping.

(f) "Blackwater" means water containing fecal matter and/or urine.

(g) "Five day biochemical oxygen demand (BOD5)" means a measurement of the dissolved oxygen used by microorganisms in the biochemical oxidation of organic matter during a five (5) day period.

(h) "Building sewer" means the pipe that carries wastewater from the building.

(i) "Chamber" means a domed open bottom structure that is used in lieu of perforated distribution pipe and gravel media.

(j) "Delegated small wastewater program" means a local governmental entity, delegated by the Administrator, with the authority to administer the provisions of W.S. 35-11-301(a) (iii) for small wastewater systems pursuant to the provisions of W.S. 35-11-304.

(k) "Direct human consumption food crops" are crops consumed directly by humans. These include but are not limited to fruits, vegetables, and grains grown for human consumption.

(l) "Domestic wastewater" means a combination of the liquid or water-carried wastes from residences, business buildings, institutions, and other establishments arising from normal living activities.

(m) "Domestic septage" means liquid or solid material removed from a waste treatment vessel that has received only wastes from residences, business buildings, institutions, and other establishments arising from normal living activities.

(n) "Dosing tank" means a tank equipped with an automatic siphon or pump designed to discharge effluent on an intermittent basis.

(o) "Effluent" means liquid flowing out of a septic tank, other treatment vessel, or system.

(p) "Effluent filter" means a removable, cleanable device inserted into the outlet piping of a septic tank or other treatment vessel designed to trap solids that would otherwise be transported to the soil absorption system or other downstream treatment components.

(q) "Evapotranspiration" means the combined loss of water from soil by evaporation from the soil or water surface and by transpiration from plants.

(r) "Greywater" means untreated wastewater that has not been contaminated by any toilet discharge; that is unaffected by infectious, contaminated, or unhealthy bodily wastes; and does not present a threat from contamination by unhealthful processing, manufacturing, or operating wastes. "Greywater" includes but is not limited to wastewater from bathtubs, showers, washbasins, clothes washing machines (unless soiled diapers are serviced), laundry tubs, and kitchen sinks.

(s) "Grease interceptor" means a device designed to separate fats, oils, and grease from wastewater.

(t) "Groundwater" means subsurface water that fills available openings in rock or soil materials such that they may be considered water saturated under hydrostatic pressure.

(u) "High groundwater" means seasonally or periodically elevated levels of groundwater.

(v) "High strength wastewater" means a wastewater stream with a BOD5 higher than 200 mg/L.

(w) "Holding tank" means a watertight receptacle designed to receive and store wastewater.

(x) "Manifold" means a non-perforated pipe that distributes effluent to individual distribution pipes.

(y) "Mound system" means an onsite wastewater system where any part of the absorption surface is above the elevation of the existing site grade and the absorption surface is contained in a mounded fill body above the grade.

(z) "Mulch basin" means an excavated area that has been refilled with a highly permeable media, organic and inorganic materials intended to distribute greywater to irrigate vegetation.

(aa) "Pathogens" are disease-causing organisms. These include, but are not limited to certain bacteria, protozoa, viruses, and viable helminth ova.

(bb) "Percolation rate" means the time expressed in minutes per inch required for water to seep into saturated soil at a constant rate.

(cc) "Pipe invert" means the bottom of the internal surface of the pipe.

(dd) "Percolation test" means the method used to measure the percolation rate of water into soil as described in Appendix A.

(ee) "Permit by rule" means an authorization included in these rules that does not require either an individual permit or a general permit. A facility that is permitted by rule must meet the requirements found in this chapter, but is not required to apply for and obtain a permit to construct and operate the facility.

(ff) "Pressure distribution" means a network of pipes in which effluent is forced through orifices under pressure.

(gg) "Restrictive layer" means a nearly continuous layer that has one or more physical or chemical properties that significantly impede the movement of water and air through the soil or that restrict roots or otherwise provide unfavorable root conditions. Examples are bedrock, cemented layers, and dense layers.

(hh) "Septage" means liquid or solid material removed from a waste treatment vessel that has received wastes from residences, business buildings, institutions, and other establishments.

(ii) "Septic tank" means a watertight tank designed and constructed to receive and treat raw wastewater

(jj) "Serial distribution" means a group of trenches arranged so that the total effective absorption area of one trench is used before liquid flows into the next trench.

(kk) "Service provider" means a person authorized and trained by a system manufacturer or their vendor to operate and maintain any proprietary system.

(ll) "Soil absorption system" means a shallow, covered, excavation surface, or mound made in unsaturated soil into which wastewater effluent from the septic tank is discharged through distribution piping for application onto absorption surfaces through porous media or manufactured components.

(mm) "Trench" means an absorption surface with a width of three (3) feet or less.