In which scenario is professional design required for OSSF?

Professional design is required for on-site sewage facilities (OSSF) in scenarios where systems need variances from established rules. This situation arises because obtaining a variance implies that the system will not meet the standard regulations as set by the Texas Commission on Environmental Quality (TCEQ). A professional designer is necessary to ensure that the proposed system will adequately address health, environmental, and operational concerns while still complying with regulatory intent, albeit in a modified way.

Variances can occur for various reasons, such as specific site features, unique soil conditions, or other factors that might prevent the use of standard designs. Professional designers bring expertise to analyze these unusual conditions and develop tailored solutions that maintain public health and environmental protection standards. Their involvement is critical because without expert oversight, using a non-compliant system could lead to failures and potential risks.

In contrast, standard systems, local soil use, and systems on large lots generally do not require the same level of scrutiny or specialized design. These scenarios often adhere to the established guidelines and do not present the same complexities that necessitate professional intervention.