It shall be the duty and responsibility of the person, firm, partnership or corporation engaged in making a connection of a private side sewer to a main sewer extension, at or near the property line, to determine that the invert at the property line is of sufficient depth to ensure proper grade to house or building drain to permit gravity flow from the house to the main side sewer connection. It shall further be the duty and responsibility of such person, firm, partnership or corporation engaged in making a connection of a private side sewer to a main side sewer extension at or near a property line to determine that the main side sewer extension from the main side sewer pipe to the property line is open, free and in good working order before making the connection. (Ord. 1506-88 § 7, 1988; prior code § 2.02.082.)