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Perk Test - Minutes Per Inch (MPI)

Joined
Oct 19, 2009
Messages
515
Location
Lincoln
While attempting to determine the rate of absorption, I dug nine holes and filled them with water. I am told that a value greater than 60 MPI is cause for concern. If my MPI is based on the four hour measurements, I have 10 MPI - which is good. Obviously the absorption rate slows after the soil surrounding the hole becomes saturated after 24 hours. So what length of time should I be using?

https://www.dropbox.com/s/qiqeogrikw2bp66/PercolationTest.pdf?dl=0

Thanks again!

ICC Certified Plan Reviewer
NFPA Certified Fire Plan Examiner
 
Thanks CDA. Somehow I found that same reference before I started and I could recall some of the information.
My results are dubious. If the first four hours are considered pre-soaking the holes and the last twenty hours are divided by the drop in water level, then I am stuck with 203 minutes per inch. The results would suggest that my soil is non-absorbent and I am reluctant to expect that any length / size of drainage field will be adequate.
 
Maybe talk to a septic company in that area to see what they think or normally encounter

Especially if new systems are set all the time
 
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