Concrete sanitary sewer pipes and manholes featuring a protective plastic liner

A concrete sewer system comprising at least two prefabricated composite concrete elements assembled end to end at a joint, each of said at least two prefabricated composite concrete elements comprising:

• an outer reinforced cast concrete portion;
• at least one connection detail at one or both ends of said composite concrete element;
• and
• a continuous inner plastic liner defining a corrosion resistant throughbore for transporting wastewater;
• wherein each said continuous plastic liner lines an interior of said outer reinforced cast concrete portion and conforms to said connection details to permit said assembled concrete elements to form an annular liner to liner contact face in said joint;
• and
• wherein said liner to liner contact face permits said joint to be sealed to contain corrosive elements within said throughbore;
• each continuous plastic liner including a first top step and a top face, wherein the top step and the top face cover a top end of the concrete portion and the first top step covers a top notch of the concrete portion;
• each continuous plastic liner including a side wall which fully covers an inside face of the concrete portion;
• each continuous plastic liner including a second lower step to cover a bottom notch of the concrete portion;
• and
• each continuous plastic liner covering all surfaces of the concrete portion except for an outer face and an open bottom face adjacent to the bottom notch, wherein the liner portion is formed as a single continuous part.

A method of prefabricating a composite concrete element for a wastewater system, said method comprising the steps of:

• positioning an outer mold element to define an outer concrete surface of said composite concrete element;
• positioning a preformed inner plastic liner to define an interior surface of said composite concrete element, said preformed inner plastic liner at least partially further defining end connection details of said composite concrete element, and creating a casting void between said outer mold element and said preformed inner plastic liner;
• providing at least one inner mold element to support said preformed inner plastic liner in position during concrete casting;
• filling said casting void with concrete and allowing said concrete to set to form a cast composite concrete element;
• removing said at least one inner mold element, and then removing said cast composite concrete element from said outer mold element;
• and
• curing said cast composite concrete element to form said cured composite concrete element;
• the inner plastic liner including a first top step and a top face, wherein the top step and the top face cover a top end of a concrete portion of the composite concrete element, and the first top step covers a top notch of the concrete portion;
• the inner plastic liner including a side wall which fully covers the inside face of the concrete portion;
• the inner plastic liner including a second lower step to cover a bottom notch of the concrete portion;
• and
• the inner plastic liner covering all surfaces of the concrete portion except for an outer face and an open bottom face adjacent to the bottom notch, wherein the inner plastic liner is formed as a single continuous part.