What should be done if surface water is not diverted toward lateral lines during grading?

When surface water is not diverted away from lateral lines during grading, it can significantly impact the effectiveness and longevity of a septic system. Specifically, surface water may saturate the soil surrounding the lateral lines, which can lead to system failure by overpowering the drainage capacity of the soil and causing backups or contamination of the system.

Additionally, excessive moisture from surface water can lead to anaerobic conditions in the soil, inhibiting the natural biological processes that are critical for treating effluent. Therefore, proper grading and management of surface water are essential to ensure that the septic system operates efficiently and remains functional.

Ensuring surface water is directed away from the lateral lines is a preventative measure that safeguards the integrity of the septic system, making option B the most appropriate response to the question.