What aspect of pit construction must be ensured regarding the sides of the pit?

The correct choice emphasizes that the sides of the pit must be smooth and free of puncture risks, which is crucial for several reasons in septic system construction. A smooth surface helps to prevent any risk of puncturing or damaging the septic liner or other surrounding materials, which can lead to leaks or contamination of the surrounding environment. Additionally, a smooth surface can promote the proper flow of liquids and mitigate the potential build-up of harmful bacteria or blockages. Ensuring that the pit sides are free from sharp edges or abrasive surfaces is essential for both the longevity of the septic system and the safety of those who may come into contact with the installation.

The focus on smoothness contributes to the overall efficiency and safety of the septic system, emphasizing proper design and functionality over mere appearance or unnecessary reinforcement.