Who is considered qualified to conduct a soil investigation?

A soil investigation is a critical step in assessing a site's suitability for a private sewage system, as it informs decisions related to system design and installation. Each group mentioned in the options brings specific expertise necessary for conducting thorough soil investigations.

A soil classifier specializes in identifying and categorizing soil types based on their physical and chemical properties. This expertise is essential, as different soil classifications can affect how waste is absorbed and how water flows, which are crucial factors in ensuring the functionality of a sewage system.

A licensed professional engineer possesses a comprehensive understanding of engineering principles, including those related to soil behavior and wastewater management. Their training allows them to evaluate soil investigations not just from a geological standpoint, but also from an engineering perspective, thereby ensuring safety and effectiveness in system design.

Employees of the local health department with at least 6 hours of soils coursework are also qualified, as they often have direct experience with local soil conditions and health regulations that govern sewage management in specific areas. Their training helps to ensure that public health concerns are adequately addressed.

Given that all these professionals have relevant qualifications and training that complement each other, they can conduct soil investigations effectively. This is why the answer includes all of the above options, highlighting the collaborative nature of expertise needed for these tasks in the context