A stormwater treatment system includes water treatment media that defines a helical flow path within a conduit. The stiffened region can include a first array of individual, stiffening elements, and at least a second array of individual, stiffening elements. Then, the pixel portion displays an image in accordance with the data of the video signal and the drive current at the time is measured for all of OLEDs in the pixel portion. Further a second body having metallic pads facing the respective terminals. The steering apparatus comprises a detection unit for detecting a force applied to the support yoke to which a force acting on the meshing portion being transmitted from the rack shaft and a calculation unit for calculating a steering torque applied to the steering member based on the force detected by the detection unit, wherein the pinion and the rack are formed in helical gears.