Vacant Land and Perk

[Jamane Y.]

What does "land does not perk mean" on a piece of vacant land?

[Adam Johnson]

I don't know if this is true everywhere, but in NY, the County Health Department works with you to do a perc. test. I should note that in NY, a total of 4 holes are required, 3 of them can be dug with post hole diggers and are roughly 18" deep. These are filled with water and it is timed how long it takes for the water level to drop one inch. This is repeated until you get 2 tests in a row with similar results, this is also referred to as a stabilized test. The first couple runs will result in faster absorption due to the soil being drier. The 4th hole is called a deep hole and is generally dug with a backhoe or mini-excavator (or somebody with a lot of energy!). The deep hole is to expose mineral deposits that indicate the seasonal high ground water level. A minimum separation is required between the mineral deposit layer and the leach line elevation. It is therefore possible to have soil that passes the perc. test but still requires sand fill (more money) in order to attain this minimum separation. Contact your County Health Department for more information. They may or may not have jurisdiction in your area, some areas are requiring a licensed engineer to design the system.

@Dustin B. gave bad information. The perc. test has nothing to do with the septic tank, it is related to the leach field which is where the liquid effluent is discharged into the soil. The septic tank is a collection point for sewage solids and the liquid effluent flows out of the tank into the leach field. A failing perc. test does NOT have to mean that you can't build there, it MAY mean that you just have to spend more money on an engineered system and/or raised sand bed.

Finding a local person that is familiar with soils in your area (on a street by street basis) could be a good way to get a quick rough idea what you MIGHT expect, but soils can vary greatly even on the same site. You might find sandy loam on one corner of a one acre lot and silty loam 100' away. They will have wildly different perc. rates.

Having a perc. test done is not extremely expensive. Contact a local excavation contractor to get an idea on cost. I would recommend that you do the perc AND deep hole test if they are required in your area for system design. Cutting a corner and only doing the perc. test (because it is cheaper and you can do it yourself) is dangerous. I have worked on many sites that have great perc. rates but high mineral deposits, so they still require trucking in sand fill.

Hope that helps.