GL and IL are common abbreviations in engineering and construction, representing key elevation references. GL refers to Ground Level, while IL refers to Invert Level.
Here's a breakdown:
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GL (Ground Level): This is the elevation of the existing ground surface at a particular location. It's a crucial reference point for many construction and engineering calculations. Ground Level can vary significantly across a site.
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IL (Invert Level): This is the elevation of the bottom (invert) of a pipe, channel, or other similar structure. It's a critical measurement for ensuring proper flow and drainage in systems like sewers, culverts, and irrigation channels. The invert level determines the lowest point at which liquid can flow through the structure.
In essence, while GL describes the surface, IL describes the bottom of a subsurface structure. Understanding both is crucial for planning and executing projects involving underground utilities and infrastructure.
For example, when designing a sewer line, engineers need to know both the ground level (GL) to determine the depth of excavation and the invert level (IL) to ensure proper gravity flow of wastewater.