Laois Co Co Text Only - Percolation Tests

Laois Co Co - Percolation Tests

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Pre-testing of Percolation Holes

In the percolation area, the soil and subsoil are used to treat and dispose of effluent arising from septic tanks, in an environmentally safe manner. Trial hole tests and the derived T value (this may be obtained from the Planning Department) indicate as to whether the subsoil percolation rate is high enough to allow the effluent to pass through without ponding but low enough to enable purification.

Septic tank / percolation areas should be located within the site and constructed in accordance with the provisions of S.R. 6 (1991) published by Eolas. Percolation test holes and the water table test hole must be prepared in the proposed percolation areas, not elsewhere on the site.

Requirements for Percolation Tests

Required on site for percolation tests are the following:

Number: 2 percolation holes per site.

Location: To be dug in percolation area.

Size: 300mm square x 400mm deep below invert of pipe (approximately 800mm below ground level).

Sand: Place 150mm of sand or fine gravel in a bucket beside test holes.

Water: Approx. 30 gallons of clean water and a bucket to be provided near the percolation trial holes.

Covers: Each hole is to be provided with an easily removable cover to prevent the ingress of surface or rain water.

Remarks: Percolation trial hole should be approximately 4M from water table trial holes. Holes may be dug by hand or using a mechanical excavator. The bottom and sides of the holes should be scratched with a knife or similar tool to remove any smeared soil surfaces and to provide a natural soil / water interface across which water may percolate.

Requirements for Water Table Tests

Required on site for water table tests are the following:

Number: 1 water table hole per site.

Location: To be dug in percolation area.

Size: 1.0m square x 2.0m deep, or 1.5m deep below invert of pipe, (This is the depth below ground level of the bottom of the percolation pipe in the percolation area).

Shoring: Temporary shoring may be necessary to prevent slippage and any shoring should not extend more than 1.4m below ground level. Shoring should not interfere with the flow of water into the hole.

Covers: Each hole is to be provided with an easily removable cover to prevent the ingress of surface or rain water.

Remarks: The trial hole may be dug by a mechanical excavator but must be at least 2.0m deep of 1.5m deep below the invert level of the pipe. This hole shall be covered when dug and left for not less than 48 hours.

Application Form for Percolation Tests

A completed Application Form for a percolation test (with all questions answered) should be accompanied by:
Two number copies of 6 inch Ordnance Survey maps scale 1: 10560, indicating location of site.
Two number copies of Ordnance Survey maps scale 1:2500 indicating location of maps.
Test Fee: 300 euro per site; 100 euro per re-test.

Site Location Maps :

Site Location Maps should be related to the Ordinance Survey sheet of the area, be to a scale of 1 : 2500, should bear a North Point and indicate the relevant Ordinance Survey sheet number. Sufficient area to allow positive site location both for office and site inspection purposes should be shown. The site should be outlined in red. Obvious existing surrounding features such as buildings, roads and boundaries should be shown, together with exact distance to nearest towns and villages in all directions. The name and address of the person who prepared the location map should be indicated on the map.

Site Layout Plans:

A detailed 1 / 500 scaled drawing of the site which includes the percolation area and reserve percolation area.This drawing shall indicate the design, construction location, proximity to wells, houses and boundaries in accordance with S.R. 6 (1991). The site should be outlined in red and a North Point is to be included on the plan. Access to test holes shall be direct (not through adjoining fields).