- Effluent from the Wastewater Treatment Plant should be discharged to a percolation area subject to satisfactory results from site suitability assessment and in accordance with local authority conditions.

- The treated waste water discharges, by pump or by gravity, into a network of perforated pipes laid in stone filled trenches.

- The objective is to spread the effluent as evenly as possible over the required land area, thus minimising the possibility of the ground becoming over-saturated.

- Bio cleaner discharge has minimal SUSPENDED SOLIDS, NITRATES AND PHOSPHATES and is therefore, much more readily absorbed than septic tank effluent.

- The extent of the irrigation system is determined by the site assessment, taking into account the soil type and percolation test results, as well as the population to be served. These values are given for guidance only and should be discussed in detail with the site surveyor.

-The percolation area or pipe lenght will vary due to “T” values but will be laid to the design shown above (assuming 1 metre wide trenches).

- For pumped discharges (usually where the percolation is higher than the treatment plant) the perforated pipe is 50mm diameter.

- For gravity discharges the perforated pipe is 100mm diameter.

- Trenches are generally 300-4OOmm wide with the pipes laid on 250mm of clean 15-25mm stone and covered with a polythene or geo-textile soil barrier to avoid silting.

- Layout of the trenches will be determined by site topography; the overall fall of the pipes should be not
more than 1 in 200,
- The pipes should be at least 1 metre above the highest water table level or fissured rock strata.