Percolation Testing Limerick

O.S.C is the most successful percolation testing company. Percolation Testing Limerick O’Sullivan Consulting & Testing


Percolation Testing in Limerick O’Sullivan Consulting Percolation for planning permissions in the South West of Ireland.

The testing is done by a fully qualified site assessors here in Limerick.

There is engineering insurance in place to cover up to amounts of €1,000,000 in value.

We also have public liability insurance in place to give our clients peace of mind while we are working on their properties.


Our reports are very detailed and include full E.P.A.C.O.P Site Assessment report, desk study, maps,

O.S map showing local features, B.S 5930 soil test report, timed and dated digital photographs of

the test in progress and top quality sewer system construction drawings consisting of plan, two

cross sections and a long section. These drawings are level related and will be easy to follow for

individuals involved in the construction of the effluent system during civil works. While the majority

of our testing is undertaken for clients seeking planning permission for either new builds or home

extensions, this is also a valuable service available to people who are interested in upgrading an

existing septic tank system that is not up to correct standards. We offer a excellent top quality

service at a fair price.

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What is a Percolation Test in Limerick?

A percolation test is a test to determine the absorption rate of soil for a septic drain field or

“leach field”. The results of a percolation test are required to properly design a septic

system. In its broadest terms, percolation testing is a simply observing how quickly a known

volume of water dissipates into the subsoil of a drilled hole of known surface area. While

every local authority will have its own laws regarding the exact calculations for the length of

line, depth of pit, etc the testing procedures are generally the same.

In general, sandy sol will absorb more water than soil with a high concentration of clay or

where the water table is close to the surface.

Testing method for Limerick

A percolation test consists of digging holes in the soil of the proposed drainage area to a

specified depth, pre-soaking the holes by maintaining a high water level in the holes, then

running the test by filling the holes to a specific level and timing the drop of the water level

as the water percolates into the surrounding soil. There are various empirical formulae for

determining the required size of a leach field based on the size of facility, the percolation

test results, and other parameters. The drainage or percolation area is designed based on

these test results.

For leach line testing, test holes are drilled, most commonly twelve inches in diameter,

Ideally, these should be drilled to depths matching your trench invert level. For better, more

conclusive results, holes are used in a pattern of one hole at each corner of the proposed

leach field and one test hole in the centre. Testing of these holes will result in a value with

units of minutes per inch. This value is then correlated to a predetermined county health

code to establish the exact size of the leach field.

After the test is completed the results are used to design a suitable polishing filter or

percolation area for the site, though the end result is a different type of septic system,

established through a different calculation if needs be.


Finally, for leach line systems and horizontal seepage pits, a “deep hole” (TRIAL-HOLE) is

drilled to find the water table or the approximately twelve feet (dry). Exact depths will again

depend on local health codes. In the case of a vertical seepage pit, local groundwater data

may be used, or if the drill hole reaches groundwater, the pit will be backfilled again

according to county health codes.

In Ireland there is a requirement for an area to be mapped around the site, photographic

recording of the test, BS5930 soil analysis, detailed test reporting as well as level related

detailed sewer system construction drawings to be included in the full site assessment


Tim O’Sullivan, O’Sullivan Consulting, Rossaneen, Currow, Killarney, Co. Kerry
Tel/Fax 066 9793931 087 2390040 email:
We are in Approved On Site Assssors in Limerick City and County Council.
On-site Treatment Systems for Single Houses. List of Site Assessors


OSC provide all of the above and expert drawing to support your submission for Planning to Limerick Council.

O.S.C Environmental Engineering and Percolation Testing