Volume Quandary

I have been using Civil 3D and am very comfortable with volumes, but this one has me a little stumped. I am having a hard time trying to figure where to start my surface building. We do not want it to take a week to build, plus we need to be able to verify the resulting volumes.

We are currently working on a remediation project at a former Manufactured Gas Plant (MGP) site using insitu stabilization (ISS) to create a monolith of vertical soil-cement columns. The initial plan was to solidify the soil from the surface to bedrock using overlapping auger columns. However, the augers could not reach bedrock and be overlapped as planned, leaving untreated soil between and under the auger columns. To address the remaining untreated soil between and under the auger columns, 4.9’ diameter jet grout columns are being used.

We are trying to estimate the total volume of soil treated via augers versus jet grouting. The calculation is tricky because:

The auger columns vary in diameter (from 4 to 8’), depth and amount of overlap with each other;

Jet grout columns are eclipsed by auger columns within the 4.9’ jet grout diameter and do not reach full diameter until deeper than the auger column(s).

The bedrock depth varies from 12 to 65 feet below ground surface.

The total volumes treated are to be without overlap (e.g. if 2 columns overlap, the overlap volume is counted only once).

Any thoughts as to how the volumes can be calculated using CAD?

I'm tempted to say you might get better results by using vanilla Autocad solids, instead of C3D surfaces, and try to create a solid for each of your columns. Solids can be subtracted from each other, and don't have problems with vertical faces.

How did you get your data? In other words, how do you know the diameter of each column along its entire depth? Depending on the type of data you have, it might even be easier to forget Autocad, and use simple geometry to estimate the volumes of each column.

It seems we may have to go "manual" on this calculation. We were just trying to see with all this technology we have, if there was an easier way. We just do not want to spend a week setting up the surfaces, etc. when the manual calculation can be done in a much shorter time frame. Time is money!

Thanks.