The invention relates generally to the rehabilitation or repair of waste water system components, such as manholes, sewer pipes, lift stations or clarifiers, through the application of a multi-layer liner. More particularly, the invention relates to the rehabilitation of such systems where the multi-layer liner is spray-applied and comprises a primer layer, a first moisture barrier layer, a foam intermediate layer and a second moisture barrier layer. Even more particularly, the invention comprises such a liner where the primer layer is composed of an epoxy, the first and second moisture barrier layers are composed of polyurea and isocyanate polymer blends, and the foam layer is composed of a polyurethane foam.
Deterioration of waste water system components is a severe and growing problem. Originally built of brick, block or concrete construction, these components develop leaks, cracks and holes due to age, erosion, corrosion and ground water intrusion. Leakage from old manholes and sewer lines contaminates the environment and sometimes result in catastrophic damage with respect to clean-up and repair costs.
Since the cost of repairing the components is typically much less than the cost of replacement, many techniques have been developed to repair and rehabilitate waste water system components. For example, it is known to recast manholes and the like through the use of forms and poured concrete, such as shown in U.S. Pat. No. 5,032,197 to Trimble. Because this process is very labor intensive, many techniques are directed toward spray-applied liners. For example, Strong in U.S. Pat. No. 5,002,438 teaches the use of sprayed cement to form a liner inside the deteriorating structure. Spray-applied epoxy, acrylic or polyurethane liners are also known, as is the use of resin impregnated substrates, such as felt, as taught in U.S. Pat. No. 5,017,258 to Brown et al. The current spray-applied systems suffer from moisture, delamination, shrinkage and structural weakness problems resulting from the typical environment encountered in the repair operation.
It is an object of this invention to provide a technique and particular liner structure for repairing waste water system components which is spray-applied and does not suffer from the problems relating to moisture, delamination, shrinkage and structural weakness.
It is a further object to provide such an invention which increases the structural integrity of the repaired component due to the unique composition of the layers within the multi-layer laminate applied to the component.
It is still another object to provide such an invention which can be applied in wet conditions to any shape surface having any number of irregularities and has a rapid cure time.