Construction Methods

The Inflow & Infiltration Reduction Program is using various types of construction methods to complete the rehabilitation work. These methods include the following:

Cured-In-Place Pipe (CIPP) Lining

CIPP Lining is a type of in-situ (in the same place) rehabilitation in which a flexible liner (a felt or fiber sleeve) is impregnated with thermosetting resins and is inserted into an existing pipe. The flexible liner can be installed via winch or in several different inverted methods depending on the application. Once in place, the liner is inflated until it fits snugly into the host pipe. The thermosetting resin in the liner is then activated by thermal methods (hot water, steam) or UV light. After which, it is allowed to cure and fully harden before the pipe is put back into service. Holes are cut in the hardened liner at each sewer lateral tie-in location. Services can be rehabilitated using specialized “T-Liners” or replaced using standard trench installation methods. 

Learn about this method here:

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Pipe Bursting

Pipe bursting fractures the existing, deteriorating pipe and drives its pieces into the ground around it by using internal, mechanical force, while pulling the replacement pipe into place. There’s no need to remove the existing pipe; therefore, making it possible for this to be a “trenchless” means of replacing pipe. The process is not entirely trenchless as there is a need to excavate a launching pit and a receiving pit. An expander head is inserted from one side and either driven (pneumatic burst) or pulled (static burst) through the existing pipe until reaching the other pit. If laterals are present, the lateral connections will require excavations for reconnection of the laterals to the existing main line. 

Learn about this method here:

Pipe Bursting - 1

Open Trench Replacement

Open-Trench Replacement is the most traditional and widely used method of sewer pipe repair. This method requires excavating and backfilling a trench to remove and replace each individual stick of pipe. Unlike trenchless methods, open trenching can be implemented to remove defects such as offsets, bends, and sags, and to modify the slope of the pipe. In non-paved areas, where there is little to no impact to structures or utilities, open trenching is typically the most cost-effective method. Alternatively, trenching in paved areas requires saw cutting, pavement removal, excavation, backfilling, compacting new base rock, and repaving. 

Learn about this method here:

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Directional Drilling

Directional Drilling is a way to bore a pipe in an existing area where the goal is to not disturb the existing infrastructure like streets, buildings, and utilities. The bore is first created, and a pipe (usually HDPE) is pulled through the bore that was created by the drill. If laterals need to connect to the bored mainline, the lateral connections will require excavations for connection of the laterals to the main line. 

Learn about this method here:

Direction Drilling - 1