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Home My WebLink About2621 - Other AssessmentsNOEL Mc GAHON Architectural Design & Planning Services ESSEXFORD, DUNDALK, CO.LOUTH. Mobile: 087 2359 206 Email: noelmcg123@gmail.com VAT Reg. No: IE 6674891F PLANNING DEPARTMENT WWTS Inspection Repo tvONAG ��N CQ. COUNCIL Pauric & Amanda Dowdall Property at Kednaminsha, Inniskeen, Co. Monaghan. MON. CO. CO. PLANNNG SECTION 10 March 2026 v 1.0 Z 5 MAR 2026 A detailed survey was carried out on the existing waste water treatment system at Kednaminsha, Inniskeen, Co. Monaghan. The overall volume of the existing septic tank was found to be 3.51m3. The holding capacity of the tank was found to be 2.93m3 (sketch of existing septic tank attached in Appendix A). Based on the no. of bedrooms in the existing dwelling a design PE of 6 is required. The resultant minimum capacity is therefore (150 x 6 + 2000) = 2900 litres = 2.90m3. The existing septic tank capacity exceeds the current standards required. The existing tank is a single chamber tank and it is recommended to install a concrete baffle wall to create 2 chambers. This will allow the solids to settle and digest within the first chamber while the liquid enters the second chamber and onto the percolation area for further treatment. The existing tank shall be made water tight prior to the construction of the baffle wall. In addition 'T— pieces' shall be included on the inlet and outlet pipes and the concrete lids and air vents shall be replaced were necessary. An effluent screen on the outlet pipe is recommended. The existing manhole covers shall also be replaced were deemed necessary. (see attached photo's of the existing on -site system in Appendix B) It is proposed to install a new percolation area with 108m of percolation trench length as per Table 7.2 in the EPA CODE OF PRACTICE 2021. (see Appendix C) The trench width should be 500mm wide and no individual trench length should be longer than 18m. The Percolation trenches shall be constructed as per Table 7.3 & Figure 7.3 in the EPA CODE OF PRACTICE — (see Appendix D). Refer to the site layout for the position of the new percolation area. In addition, I can confirm that the septic tank was constructed and installed when the original dwelling and garage were built in the late 1980s. In my opinion the existing septic tank is operating satisfactorily and with the additional recommendations as stated above the system will meet current standards. It is further recommended that the existing septic tank is emptied by a licensed contractor every 12-18 months. If you have any queries in relation to the above, please do not hesitate to contact me. Yours Sincerely Noel Mc Gahon (Building Surveyor.) Appendix A — Sketch of existing septic tank. t4 -)—t E7T ZSM,\ ELOCi Mj4G[S PL,9s TE# E . O uC . L -LOS v F S v r vEI\tf U Tt T 25 A,— SINGE CMABC/ rs-T�Ali� . Appendix B of Photographs ■ Fig 1-5 Images of the existing septic tank on -site. Fig I Fig 2 Fig 3 Fig 4 Fig 5 Appendix C Table 7.2: Minimum percolation trench length Appendix D Geoteotile Surface GraveMembrane Percolation Ground Level Ground Level Test Hole Subsurface ,»:: „� „ „� ercolation ��If:; ';�\c, �a>\�t\ . �a��,\\ ��\� \\\�\\ �,\a. �. . �•`�\\�,: 0 150mm i4ho, • a' 85omm R�n�� Test Hole Proposed Invert Percolation ° ° = IOOmm of Percolation Pipe 300mm Pipe $oae'�a ----- 300mm Water o`. ba level I4o0mm Base of the ;�q d¢4 fii.----------- Percolation Trench a 5oomm _ t 100mm 30omm 1,200mm or 2,000mm minimum Unsaturated above water table and/or bedrock Undisturbed depending on the groundwater Subsoil protection response (see Table 6.3) Figure 7.3: Section of a typical percolation trench following a conventional septic tank Table 7.3: Requirements of a percolation trench (gravity fed) Slope of pipe from tank to 1 in 40 for earthenware or concrete, distribution device 1 in 60 for uPVC Slope of percolation trench from 1 in 200 distribution device Length of percolation pipe in each 18 m maximum trench Minimum separation distance 2 m (2.5 m centre to centre) between percolation trenches Diameter of pipe from septic tank 100-110 mm to distribution device Percolation pipes' 100 mm bore, perforated (typically at 4, 6 and 8 o'clock) smooth wall PVC drainage pipes with perforations of 8 mm diameter at about 75 mm centres along the pipe or pipes with similar hydraulic properties. Maximum of six pipes per distribution device Width of percolation trench 500 mm Depth of percolation trench Ideally, about 850mm° below ground surface depending on site (as per Figures 7.1 and 7.3) Depth of unsaturated soil and/or Minimum 1.2 m for GWPRs of R1 or R2'. Minimum. subsoil beneath percolation trench 2.0 m for GWPRs of R2?, R23, R2°, R3' or R32 and above the bedrock and the water table Backfilling of percolation trench 300 mm of 12-32 mm washed gravel or broken (see Figure 7.1) stone aggregate on invert; pipe laid at a 1 in 200 slope surrounded by 12-32 mm clean washed gravel or broken stone aggregate and with 150 mm of similar aggregate over pipe; geotextile layer followed by topsoil to ground surface Geotextile Geotextile should be in accordance with EN ISO 10319 Access/inspection points and vents These are recommended for the ends of the percolation pipes. The covers should be visible and installed to prevent entry of water. They may also be used for rodding or scouring purposes a Before installation the holes in the percolation pipe should be inspected to check that they are the correct size and free from debris. b The percolation pipes may be located at a shallower depth, provided that a minimum, of 450 mm of material is placed above the pipes to provide the required protection against damage from above.