Underground drainage facility and operation method therefor

Abstract

A drainage system comprises a drainage passage for a drain water, a pump for pumping up the drain water from the drainage passage to a drain portion which is arranged above the drainage passage, and a storage tank which has an inlet connected to the drainage passage to receive the drain water therethough from the drainage passage into the storage tank, and a height of the inlet is higher than that of the drainage passage and lower than that of the drain portion so that an ascent of upper surface of the drain water from the drainage passage is restrained after the drain water ascends to the inlet from the drainage passage.

Dependencies are inferred from the claim text.