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Soil Percolation Test
- Thread starter egildea
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dirtsqueezer
Geotechnical
I believe there is an ASTM for this procedure. You could try the ASTM website.
The actual perc test is simple to perform, BUT the City or County where you live has some outline of what they will accept. I have seen this vary from "I need a geotechnical firm to sign it off" to "The manual of XX county has to be followed exactly"
The test in general entails digging a small hole(say 2 feet by 2 foot by 2 foot". The whole is presaturated overnight with no water drop measuements. The next day you measure the volume of water drop and then determine the permeability of the soil in units of gallons/square feet per day. You would be required to meet a minmum percolation. So the more sandier the soils are the higher the rate and thereofre not a concern for septic systems. One note: If your septic field or leach system is close to a slope, you woulkd have to take into account saturating the slopes and therefore reducing the factor of safety of the slope.
Here is a link from Dupage County's percolation procedure as an example.
The test in general entails digging a small hole(say 2 feet by 2 foot by 2 foot". The whole is presaturated overnight with no water drop measuements. The next day you measure the volume of water drop and then determine the permeability of the soil in units of gallons/square feet per day. You would be required to meet a minmum percolation. So the more sandier the soils are the higher the rate and thereofre not a concern for septic systems. One note: If your septic field or leach system is close to a slope, you woulkd have to take into account saturating the slopes and therefore reducing the factor of safety of the slope.
Here is a link from Dupage County's percolation procedure as an example.
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- #4
dicksewerrat
Civil/Environmental
The irish test is done after 4 or 5 of those dark beers.
Richard A. Cornelius, P.E.
Richard A. Cornelius, P.E.
- Thread starter
- #8
yes, the Donegal County Council Planning workshop manual that i have been using for the last 8 years and didnt think to look in has the details of a perc test. 0.3mx0.3mx0.4m hole dug. saturate overnight, then come back next morning and measure time for water to drop from 3/4 height of hole down to 1/4. this gives you your "t" value (time to fall in minutes, divided by 4 to give time to fall 25mm) that then corresponds with a table of pipe lengths required in percolation area. All this information will then be submitted to the council, as per the condition laid out in planning permission. The council will no doubt put it on file, and never look at it. 
Seems the EPA have a manual for wastewater treatment for small communities and hotels. It outlines the official percolation test giving minimum seperation distances from local wells, houses boundaries etc. Most of it can be downloaded from
Some local authorities insist that you have done the Site Suitability Assessment course run by FAS before they'll accept your assessment. Others just require that you are independent and have insurance cover.
I douby half the council staff would know what a percolation test is for. Mmmm .... Isnt it something to do with coffee?
Some local authorities insist that you have done the Site Suitability Assessment course run by FAS before they'll accept your assessment. Others just require that you are independent and have insurance cover.
I douby half the council staff would know what a percolation test is for. Mmmm .... Isnt it something to do with coffee?
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