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Cut Fill "After" Surface

Question asked by andy.aston on Mar 14, 2019

I'm not positive this is the best-fit spot for my post.  I'm seeking feedback on a repeatable methodology for generating the "after" surface for input into the Cut Fill geoprocessing tool.  The big picture is we're a utility-scale solar developer and need a meaningful, in-house way to compare wildly different EPC contractor's cost-estimates for grading of our pre-construction "greenfield" sites.  In a relative way, the useable areas (i.e. ground-mounted "tracker" PV module array locations) of these projects are flat-ish, with minor terrain variation.  Typically, the aspect of these sites trend S to SW.  The "before" surface is derived from LiDAR.  Is there an industry standard methodology (or hack) to estimate the graded "after" surface based on the existing "before" surface, without oversimplifying it on a single plane and at a fixed average elevation or average slope across the project boundary? Or split them into "zonal areas" using the module array footprints?  Is there a formula expression to use in the Raster Calculator or a Raster Function that will estimate the grading based off the "before" surface?  Optionally, with parameter constraints to match the "tracker" PV module arrays' operational specs? Remember, at this point these sites are not fully surveyed and we're simply using the Cut Fill output to hopefully compare apples to apples from EPC contractor offers.  Thanks a million for your ideas and feedback!