Perk Test - Minutes Per Inch (MPI)

[BayPointArchitect]

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

 

[cda]

Only thing I perc is coffee, and than sometimes I press it.

Here looks like good rules, if the city does not have any


https://fremontcountywy.org/wp-content/uploads/2009/11/Perc_test.pdf

 

[BayPointArchitect]

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.

 

[cda]

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

 

[TheCommish]

Massachusset regulations linked here for reference, dig 2 test hole to 10 feet see soil composition, water level, , dig a perk hole, soak for the required time, then fill hole with H20 and measure absorption rate, calculate leaching area based on rate tome 110 gpd per bedroom

http://www.mass.gov/eea/agencies/massdep/water/regulations/310-cmr-15-00-septic-systems-title-5.html