Even if the existing culvert is determined to be structurally deficient, culvert rehabilitation methods are not necessarily eliminated from consideration. Suitable repairs can be made to restore the culvert to an acceptable level of performance and integrity. Rehabilitation costs and the time associated with such repairs are often significantly less than what is required for the full replacement. Rehabilitation is also much safer to construction crews and the traveling public. Extending the service life of these culvert structures is a worthwhile and desirable goal in many instances.

Sliplining

Sliplining involves inserting a flexible, usually thermoplastic, liner of a smaller diameter directly into the deteriorated culvert. Liners are inserted into the host pipe by either pulling or pushing the liner into place with mechanized equipment. After insertion, the annular space between the liner and host pipe is pressure grouted to provide a watertight seal. Although the diameter of the pipe is decreased, the pipe will have a greater flow capacity due to the composition of the new liner.

Cured in place pipe (CIPP)

Cured in place pipe, better known as a "pipe within a pipe" involves the insertion of a flexible fiber tube that has been impregnated with a thermosetting resin into an existing culvert by hydrostatic air, or hydraulic head pressure. Once installed, the resin is cured by applying heat provided by circulating steam or hot water throughout the liner tube. The new liner conforms tightly to the host pipe and provides structural support to the host pipe. There is a very minimal loss to the diameter of the pipe and also increases the flow capibilities throughout the structure.

Invert Paving

There are situations where the damage or deterioration to the culvert is limited to the invert. The remainder of the culvert is in good shape and in satisfactory structural condition. The culvert may be salvaged by adding a new invert through installation of a reinforced concrete invert pavement section. A layer of steel reinforcement or wire mesh is then placed in the invert and secured to the original culvert bottom. Concrete is then placed in the invert to a thickness typically ranging from 2 inches to 4 inches over the corrugation crests. The surface of the concrete is troweled smooth to provide a new invert approximately matching the geometry of the original culvert invert.