Rider

A shallow collection line that runs along the microtunneled trunk sewer to a drop manhole.

RII

RainfallPrecipitation in the form of water (usage includes snow). Induced Infiltration(1) Penetration of freshwater or groundwater into the sewer system through cracks, defective joints in the pipeline, and holes, or through lateral connections, manholes or inspection chambers. (2) All extraneous waters (storm water and ground water) which enter the wastewater collection system through various sources including, among others, pipe defects, defective service connections, manhole covers, roof leaders, and foundation drains.; is a particular form of infiltration which is similar to stormwater inflow. RIIRainfall Induced Infiltration; is a particular form of infiltration which is similar to stormwater inflow. RII generally occurs during and immediately after rainfall events. generally occurs during and immediately after rainfall events.

Ring Compression

The principal stress in a confined thin circular ring subjected to external pressure.

Rip Rap

Rough stone of various sizes placed compactly or irregularly to prevent scour by water or debris.

Riser

A thin ring located between the frame and cone of a manhole. Used to bring the frame and cover final grade. Commonly, several riser are present in a manhole.