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| Did an install today with average grade of about 0.3. I started out with a minimum grade setting of 0.2 then because of a rock recovery reset, I had to set the minimum at 0.1. It was only at the that minimum grade for part of the run- it went from about 0.3 to 0.1 then up to 0.5 for a short distance before I hit another rock and had to dial it 0.15 before it got steep at the end again. I know we are supposed to figure our drainage coefficients based on the minimum grade, but I'm thinking I should be able to figure more than 0.1 on this run
Additional info- this was a 6" main (most of it non-perforated) put in to drain about 6 acres and I know it is more than enough for that, but there is a possibility of adding another 6 acres sometime in the distant future. At a 3/8 coefficient it comes to just under 10 acres at 0.1, around 14 acres at 0.2, and almost 17 acres at 0.3. I am confident that 12 acres should be fine, but this whole scenario got me to thinking about how we should be figuring drainage ability of our mains- especially when we are often working with old mains that we really are not sure about the what the minimum grade is under all that dirt. | |
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Average Grade vs Min Grade Tiling Drainage C/E
