Glossary

Infiltrative surface area, in m², receiving effluent from the distribution system. This is considered to be the bottom area of a trench in a trench-type gravity system.

Applied Science Technologists and Technicians of British Columbia

A registered onsite wastewater practitioner or professional.

For sand mounds, sand-lined trenches, bottomless sand filters, Alberta At Grade systems and CTDS, this is the native soil that the sand will be placed on.

A layer of clean coarse sand or mound sand that is installed between the infiltration surface (bottom of aggregate, base of chamber, etc.) and the native soil, and which is up to 10 cm (4 inches) thick.

5-day biochemical oxygen demand

Attribute of soil expressed in degree of cohesion and adhesion, or in resistance to deformation or rupture.

daily design flow

An area used to receive effluent discharged from a wastewater treatment method.

Rounded or subrounded rock fragment that is between 0.1 inches (2 millimetres) and 3 inches (76 millimetres) in diameter. Often called “drain rock.”

hydraulic application rate

hydraulic loading rate

A large cement or plastic tank into which household wastewater flows and is stored until it is pumped out.

horizontal separation

A measure of the volume of effluent, in litres, applied each day, per unit area (m²) of infiltrative surface.

In drainfields, the drain rock-to-original soil interface at the bottom of the trench; in mound systems, the gravel-to-mound sand and the sand-to-original soil interfaces; in sand-lined trenches/beds (sand filter), the gravel-to-sand interface and the sand-to-original soil interface at the bottom of the trench or bed.

A measurement of the saturated hydraulic conductivity of soil. In theoretical terms, hydraulic conductivity is a measure of how easily water can pass through soil or rock. High values indicate permeable material through which water can pass easily, such as sand or gravel; low values indicate that the material, such as clay, is less permeable.

The shallowest of a restrictive layer, water table, seasonal high-water table or extremely permeable material (e.g., fractured rock, gravel).

linear loading rate

percolation rate

percolation rate

Laminated or flaky soil aggregate developed predominantly along the horizontal axis.

point of application

A small building having a bench with a hole or holes through which human excretion may be evacuated into a waterproof vault or an excavated pit. Also known as an outhouse.

A person who is qualified to act as a registered onsite wastewater practitioner under section 7 (1) or (2) of the Sewerage System Regulation.

A layer of soil or rock that impedes the vertical movement of water, air, and the growth of plant roots. This may include hardpan, some compacted soils, bedrock, glacial till and unstructured clay soils.

A system of pipes, pumps, tanks, and other equipment used for the collection, transport, and disposal of residential wastewater (sewage). Also known as a sewage disposal system, septic system, or sewerage system.

seasonal high water table

Layers of soil or soil material approximately parallel to the land surface and different from adjacent layers in physical, chemical, and biological properties or characteristics such as colour, structure, texture, consistence, and pH.

The combination or arrangement of individual soil particles into definable aggregates, or peds, which are characterized and classified based on size, shape, and degree of grade (distinctness).

The relative proportions of the various soil separates (e.g., silt, clay, sand) in a soil.

Sewerage System Standard Practice Manual, Version 3. Access a PDF version of the SPM online.

Sewerage System Regulation within the Public Health Act

total suspended solids

The depth of unsaturated, original, undisturbed permeable soil below the infiltrative surface and above any limiting layer. This is the vertical depth of soil that the dispersal system is expected to be discharged into.

vertical separation