How is surface grade defined?

Surface grade is defined as the angle of a slope expressed as a percent in feet or inches per 100 feet. This measurement indicates the steepness of a slope, which is particularly important in the context of On-Site Sewage Facilities. Understanding the surface grade is crucial for ensuring proper drainage and runoff management, which can directly impact the effectiveness of sewage systems.

When evaluating site suitability for an OSSF, the surface grade can influence the design and layout of the system, ensuring that it functions as intended without causing environmental issues. Properly assessing the slope helps prevent issues such as flooding or soil erosion that can occur if the grade is too steep or not adequate for managing wastewater flow. Therefore, knowing how to interpret the angle of a slope measured in percentage is essential for the effective installation and maintenance of these facilities.