Abstract: Manhole closure assembly for preventing storm water from entering into manhole opening comprises cover section including downwardly depressed central portion. Circular mounting flange extends outwardly from depressed central portion and flange is adapted to rest upon inwardly directed manhole cover supporting flange of annular manhole frame. Downwardly depressed portion of cover section is depressed amount that exceeds path of spin of manhole cover resting upon supporting flange of annular manhole frame. First valve member is secured to cover section to relieve pressure inside manhole when pressure therein exceeds predetermined amount.