Sonde Housing

This integral unit is the direction drill head which also houses the sonde radio sending unit.

Spacer Block

Device used to extend the distance that the hydraulic rams within a jacking system can propel the pipeline.

Spacers

Mechanical structures used to transfer the jacking force from the jacking thrust ring to the pipe and to accommodate lengths of pipe that are longer than the stroke length of the jacks.

Spalling

(1) A process that describes the flaking, or slitting away of the surface layer. (2) The spontaneous chipping, fragmentation, or separation of a surface or surface coating.

Span

Horizontal distance between supports, or maximum inside distance between the sidewall of culverts.