UPDATE 2: My new tool completely obsoletes this process.. Stage storage basin tool is available in my free tools package here. But read on if you want to be a dinosaur..
https://ceethreedee.com/ceethreedee-tools

UPDATE: Feeling Lazy. Watch the Video.

This deals with basic “basin” stage storage calculations. For more complex stockpiles etc. Read this post here

Download lisp file from this link download COT

UPDATE: instead of using COT.lsp. Try the free “Table Exporter” App from the autodesk exchange from here. Only works in 2015 unfortunately 🙁

It will dump what ever table you select straight to excel though..

I see a lot of people still using this outdated tool in Civil 3D for calculating stage storage! For those who calculate stage storages read below!

Please stop using it! Although it is possible to get a relatively accurate result from it. There are a number of problems that I will merely bullet point below.

• Can only have one contour at each level to get stage storage curve. (although you can sum them together in excel)
• If contours are not closed this can create errors in the calculation.
• Multiple islands and “flat areas” (i.e benching) can be easily miscalculated. Who has benching in their designs! :p
• Higher Intervals reduces accuracy!
• Not to mention it is cumbersome!

Civil 3D has always had the ability to do accurate stage storages, I will demonstrate below. (*with the assistance of a lisp!)

Download lisp file from this link download COT

1. Create a Volume Surface comparing Water Level or Final Tailings level etc. and your completed design. (Yes you can calculate tailings stages as well!)

2. Drop down elevations in the analysis tab at the intervals you wish to calculate your volumes at. (use Range Interval with Datum)

3. Create a surface legend table that includes “Surface Range volume” and Surface Range 2d area)

4. Copy table to left or right and explode twice, then use the attached lisp routine to convert to an autocad table.

5. Export Table to CSV as shown above and then open in excel. You will need to sum the areas and volumes from the bottom up to get the correct results.

Finished Result, sum up the volumes from the lowest elevation, (so the bottom up). or reverse the order and sum them from the top down..

Elevation (m)	Plan Area (m²)	Cum. Area (m²)	Volume (m³)	Cum. Volume (m³)
102	5,872	143,202	280,514	1,432,735
100	5,751	137,330	268,936	1,152,221
98	5,969	131,578	257,244	883,285
96	13,903	125,609	240,933	626,041
94	26,862	111,706	200,242	385,108
92	42,463	84,845	126,689	184,866
90	31,232	42,382	51,424	58,177
88	11,149	11,150	6,752	6,753
86	1	1	1	1

You will notice that unlike the old stage storage tool that can vary in accuracy especially with larger intervals. This method is exactly right down to the triangle.

Comment below if you want to know more