The storm sewer is a system designed to carry rainfall runoff and other drainage. It is not designed to carry sewage or accept hazardous wastes. The runoff is carried in underground pipes or open ditches and discharges untreated into local streams, rivers and other surface water bodies. Storm drain inlets are typically found in curbs and low-lying outdoor areas. Some older buildings have basement floor drains that connect to the storm sewer system.
This is an O scale (1:48) model of a riser. Each riser locks into either the base or another riser. You stack as many risers as needed. On the very top a grating. This is normally the only part you see in the road (not part of this set).