Comparing HDD and Open-Cut Methods for Installing Municipal Sewer Lines

Construction methods are compared regularly according to a variety of parameters. Before a contractor decides which way is best for a project, they need to look into the cost, availability of equipment, materials, and experienced workers. The process of comparing construction methods is perhaps quite evident in utility installation. Although the open-cut method is traditionally the tried and tested technique, especially when installing sewer lines, the industry is facing stiff competition from directional drilling companies due to their many benefits.

It is easy to decide when apparent conditions such as the size of the project site or geological conditions dictate that one method is better than the other. But what happens when the project conditions are suitable for both approaches? How does the contractor decide whether to use HDD horizontal directional drilling or open-cut method?

Sewer pipe design

In considering whether HDD is suitable, the following questions need to be answered:

  • Does the municipal council allow directional drilling?
  • Are the soil conditions appropriate?
  • Are there existing utility lines underground that may cause a problem?
  • Will using HDD ensure maintaining the required sewer pipe slope?

Every municipal council determines and sets the requirements and standards for installing sewer lines. If HDD meets the minimum requirements, it is possible to consider HDD as the method for installing utility pipes.

Comparing the cost of both methods

The next step in comparing which method to use is the cost. Contractors will take into account the triple bottom line . When contractors bid for a project to install sewer lines, they need to account for how much it would cost to remove and restore asphalt and concrete. The goal is to choose which method leads to a lower restoration cost.

In general, HDD costs less than open-cut method. Contractors pay less for labour, and it is possible to complete the project in less time. Moreover, the cost of restoration is reduced with HDD.

Issues with construction

Sewer line installation does pose a few challenges for directional drilling contractors. It is possible that existing municipal guidelines and standards are not ideal for conducting HDD. Nonetheless, many municipalities are already making some adjustments to allow for HDD installation.

The open-cut method may appear to be more straightforward and simpler when dealing with sewer lines. But what is most important is to ensure that whichever technique is used, the resulting installation is robust and up to code.


HDD is gaining traction in the construction industry as a beneficial method for utility pipeline installation. Utility companies providing telecommunications, water, and electricity services often prefer HDD over open-cut or trenching.

However, the open-cut method remains a viable solution, especially when ground conditions and the type of pipe does not permit using HDD. Therefore, selecting which method is better for installing sewer lines depends on a variety of factors. Each technique has advantages and disadvantages, and when the conditions seem suitable for both, it all boils down to the cost. It is more prudent for project managers to weigh all the pros and cons of each method in making the best choice.