In this chapter, the following term has the meaning indicated. Overflow. “Overflow” means any loss of wastewater or discharge from a sanitary sewer system, combined sewer system, or wastewater treatment plant bypass which results in the direct or potential discharge of raw, partially treated or diluted sewage into waters of the State as defined in Environment Article, §9-101(l), Annotated Code of Maryland. “Overflow” includes, but is not limited to, any overflow or discharge of raw or diluted sewage onto the surface of the ground, into waterways, storm drains, ditches or other manmade or natural drainage conveyances to surface or ground waters. “Overflow” does not include: An overflow or discharge of 50 gallons or less to the ground that are cleaned up within 1 hour of its occurrence; and An overflow or discharge to impervious surfaces that are effectively contained and cleaned up so that there is no direct or potential pollution of waters of the State as a result of the overflow or discharge.