Manhole base assembly with internal liner and method of manufacturing same

A manhole structure, comprising:

• a cast manhole including a east base, and a riser extending upwardly from said cast base, the riser including a lower end attached to the cast base and an opposite, upper end;
• and
• a liner cast within the east base of the cast manhole, the liner comprising:
• an entry aperture defining an entry aperture diameter, the entry aperture spaced below the upper end of the riser wherein at least a portion of the riser is exposed and not covered by the liner;
• a first side wall having a first pipe aperture sized and positioned to be aligned with a first side opening of the cast base;
• a second side wall having a second pipe aperture sized and positioned to be aligned with a second side opening of the cast base;
• and
• a liner top wall disposed radially outwardly of said entry aperture diameter and extending between said entry aperture and said first side wall;
• a flow channel extending between said first and second pipe apertures and in fluid communication with the entry aperture;
• and
• a liner lid received in the entry aperture with the cast manhole riser extending upwardly above said liner lid, the liner lid comprising:
• a first lid portion sealingly engaged with a sidewall of the entry aperture;
• and
• a second lid portion coupled to the first lid portion and moveable about an axis which extends across said entry aperture between a closed configuration in which the second lid portion is sealingly engaged with the entry aperture and an open configuration in which the second lid portion is disengaged from the entry aperture.