Glossary

This glossary is copied from the Stormwater Manual of Western Australia Chapter 11: Further Information. References are available from this chapter.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

P

Peak discharge rate: The maximum instantaneous rate of flow during a storm, usually in reference to a specific design storm event.

Peak flow: Maximum flow rate in a flood, measured in m3/s (Department of Environment 2003).

Performance indicator: A specific type of indicator that looks at outcomes (see ’outcomes’) to see if they are meeting the project’s objectives (see ’objectives’).

Performance monitoring: Gathering of information to measure the success of strategies implemented when compared to objectives (see ’objectives’).

Permeable soils: Soil materials with sufficiently rapid infiltration rate, therefore reducing or eliminating stormwater runoff. Coarse textured soils tend to have large, well-connected pore spaces and hence high permeability.

Pervious (permeable/porous) pavement: Pavements comprising materials that facilitate stormwater infiltration and transfer to the underlying subsoil (ARMCANZ & ANZECC 2000).

pH: A measure of the hydrogen ion concentration of water or wastewater; expressed as the negative log of the hydrogen ion concentration [H+]. A pH of 7 is neutral, pH less than 7 is acidic and pH greater than 7 is basic.

Point source pollution: Contamination from a localised source, such as leaky storage tanks and drums or sewage discharge.

Pollutant retention: The proportion of pollutant load intercepted and retained by a device, either on an event or annual basis (ARMCANZ & ANZECC 2000).

Pollution prevention procedures: One of the five principal categories of non-structural BMPs for stormwater management. Examples include maintenance practices (e.g. maintenance of the stormwater drainage network) and elements of environmental management systems (e.g. procedures on material storage and staff training on stormwater management at government, commercial and industrial sites).

Porosity: Porosity is calculated as a ratio of pore volume to total volume.

Potable water: Water generally considered suitable for human consumption.

Precautionary principle: If there are threats of serious or irreversible environmental damage, lack of full scientific certainty should not be used as a reason for postponing measures to prevent environmental degradation.

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