True or False: A minimum of 3 feet of soil must exist between the trench bottom and seasonal groundwater or bedrock.

The statement is true because proper septic system design and installation require adequate soil separation to ensure effective treatment of wastewater. A minimum of 3 feet of soil between the bottom of the trench and seasonal groundwater or bedrock is necessary to provide a filtering medium that allows effluent to be treated naturally before it reaches these layers.

This distance is crucial because it reduces the risk of contamination to groundwater sources and ensures that the septic system functions effectively. If the trench bottom were closer to groundwater or bedrock, the effluent might not have sufficient time to be purified as it moves through the soil, potentially leading to environmental and health hazards.

In contrast, the other options imply differing conditions or interpretations that don't align with standard septic system regulations. Options suggesting that the requirement is false, conditional, or dependent on soil type would overlook the fundamental principles of soil filtration and groundwater protection that underpin septic system design. Thus, the necessity for a minimum of 3 feet stands as a fundamental requirement in West Virginia’s septic installation guidelines.