Polyethylene

A ductile, durable, virtually inert thermoplastic composed by polymers of ethylene. It is normally a translucent, tough solid. In pipe grade resins, ethylene-hexene copolymers are usually specified with carbon black pigment for weatherability.

Polyolefin

A family of plastic material used to make pipes.

Polypropylene

A type of plastic pipe from the polyolefin family. (abbrev. PP)

Ponding

Jetting or the use of water to hasten the settlement of an embankment – requires the judgment of a soils engineer. In hydraulics, pending refers to water backed up in a channel or ditch as the result of a culvert of inadequate capacity or design to permit the water to flow unrestricted.

Pore Water Pressure

The pressure of the groundwater held within a soil or rock: in gaps (pores) between particles.