Computing Pond Capacity Lines

This one comes up from time to time - how do I determine where my pond capacity line is for e.g. 20% and 80% full.

• The key is to create your Full Capacity line and create a surface from it - call it Pond Top

• Then determine your volumes at e.g. 0.05’ intervals using the Earthwork Report

• Copy the report values into excel and create a cumulative column and sum up the band volumes to each elevation interval

• Now take the cumulative total and determine what 20% of the volume represents

• Now take the cumulative volume and determine what 80% of the volume represents.

• Now look down the cumulative volume column to find the 20% and 80% volume numbers (or the closest number to those percentage points. These will be your two contours that you need to create

• Now use the Create Contour at elevation, and enter the specific values that you determined from the list. Name the first contour 80% and the second one 20%. These contours are your capacity lines.

• If you need to check the numbers, explode the contours to make them 3D lines. Once they are 3D lines you can create a surface for each one - call the surfaces 80% and 20%.

• Now you can see those surfaces in the Surface Slicer and 3D Views.

• Now you can run the Earthwork Report between each of these surfaces and the Finished Grade and the results should match the initial volume report.

• If everything jives, these are the lines you need for the staking operation in the field.

Video shows you how

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