Definition - What does Open Cut mean?
Open cut, as the name implies, is a method of pipeline installation that requires opening up the surface of the ground to the required depth for installing a pipeline. It is a traditional method that is still popular and is used widely for installation of sewer laterals and also for repair or replacement of main and lateral sewer lines.
Open cut excavations are cumbersome compared to other trenching methods, but in some cases, it becomes essential to open up the ground for repair as in the case of a line belly.
In open cut method of pipeline installation, a trench has to be excavated for installing each piece of pipe. This method can be used for installation as well as rehabilitation of pipeline and requires digging up the ground surface to the required depth in case of installation or digging up to pipeline depth in case of rehabilitation to expose the pipe.
Once the work is complete, the dugout area is backfilled and the surface restored to the original condition as far as possible. However, when the pipeline project is under a road or pavement, open cut method can become a problem because the road will have to be cut open to gain access. This requires closing the road to traffic and pedestrians till the work is complete which can be extremely disruptive.
Trenchless methods of construction such as directional drilling, pipe ramming, auger boring and others, plus trenchless rehabilitation methods such as pipe bursting, thermoformed pipe, and mechanical spot repair do not require excavation except at the entry and exit points. This does not affect traffic and pedestrians because most of the work is carried out underground.
Trenchlesspedia explains Open Cut
Open cut methods of installation and rehabilitation have been popular for a very long time and until some decades ago, open cut was the only method. Now trenchless technology has become popular due to its relative ease of installation and low carbon emissions.
Open cut methods are still preferred in areas that are not paved as they are a cheaper option. The surface can be easily restored by backfilling and planting seeds or sod. In paved areas, open cut method can be very costly as the surface will have to be restored to its original condition once the work is complete.
Advantages of Open Cut Method
· Cheaper option in non-paved areas compared to trenchless methods.
· For pipes that have collapsed or have lost their slope, open cut is the only way to repair the damage as the pipe will have to be removed.
· Best option for pipes heavily blocked by roots and debris as there is no need to extract them from the pipe.
Disadvantages of Open Cut Method
· More excavation required compared to trenchless methods.
· Excavated material has to be safely disposed at an appropriate location, requiring many dumping trips, increasing the cost of the project.
· Carbon footprint is greater due to the use of heavy machinery and dump truck trips compared to trenchless methods.
· Restoration of paved road, sidewalks, landscaped lawns etc. can increase the overall cost.
Why Trenchless Methods are Popular
Trenchless methods have gained popularity over the open cut method as the benefits are found to be much greater than the initial investment costs. Trenchless technologies are more environment friendly, are safe and more productive in lesser time.
The social inconvenience costs associated with open cut method is eliminated in trenchless methods and include vehicle traffic disruption, business and trade loss, site and pedestrian safety, pollution – dust, noise and vibration, etc.