An important part of the installation of an LPD system is?

The correct answer emphasizes the importance of checking and adjusting pressure on lines during the installation of a low-pressure distribution (LPD) system. This step is crucial because maintaining the appropriate pressure ensures that effluent is distributed evenly across the distribution lines. Proper pressure management prevents issues such as backups or uneven flow, which could lead to ineffective treatment of wastewater and potential system failures. Monitoring and adjusting the pressure allows for optimal operation and enhances the longevity and reliability of the system.

In contrast, while other aspects mentioned are significant in their own right, they do not directly address the core functionality and operational integrity of the LPD system in the same way. For example, stabilizing distribution lines during gravel placement is important, but it is more about the foundation of the installation rather than the immediate function of the system. Similarly, while having inspection ports is beneficial for maintenance and monitoring, and ensuring a precise grade on the dosing pipe is essential for drainage, neither of these focuses as directly on the operational aspect of ensuring the system functions properly under its designed pressures. Thus, ensuring correct pressure within the lines stands out as the most critical aspect for successful installation and operation of the LPD system.