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HomeMy WebLinkAbout2660122 - F.I. Received Doc. - Existing Domestic Septic Tank AssessmentGRAY CONSTRUCTION & DESIGN LTD Cornacreeve Dunraymond Co. Monaghan T : 047 85081 M: 086 0298424 E: grayconstructionanddesign@gmail .com EXISTING DOMESTIC SEPTIC TANK ASSESSMENT Proposed Replacement Dwelling @ Doagheys, Glaslough, Co. Monaghan Prepared in support of Planning Application Ref. 26/60122 Applicant: Michael & Margaret Wallace Prepared by: Christopher Gray 1. Introduction This report has been prepared in response to the Further Information request issued by Monaghan County Council in respect of the proposed replacement dwelling at Doagheys, Glaslough, Co. Monaghan. Appended to this report are reference pictures taken on site showing the existing septic tank. The purpose of this report is to assess the existing domestic septic tank and associated percolation area currently serving the existing dwelling and to determine whether the system is suitable for continued use. The existing dwelling was unoccupied for a period in excess of 10 years at the time of inspection. A site inspection of the wastewater treatment system was undertaken by the undersigned following removal of the septic tank cover slabs. 2. Existing Wastewater Treatment System The existing domestic wastewater treatment system comprises: • Conventional block-built septic tank. • Cement rendered internal finish. • Four precast reinforced concrete cover slabs. • Vitrified clay (crockery) inlet and outlet pipework. • Existing percolation area. The system has historically served the dwelling for many decades. 3. Inspection Findings The four precast concrete cover slabs were removed to facilitate inspection of the internal chambers. The inspection was carried out following a prolonged period of dry weather. 3.1 Tank Structure The septic tank is of conventional masonry construction. The blockwork walls were found to be structurally sound with no evidence of settlement, displacement, cracking or deterioration of the masonry. The internal cement render remains substantially intact. No evidence of structural failure was observed. 3.2 Cover Slabs The four precast reinforced concrete cover slabs were inspected following removal. The slabs remain in good structural condition with no evidence of cracking, excessive deflection or deterioration and are conside red suitable for continued use. 3.3 Water Level At the time of inspection, the liquid level within the tank was observed to be marginally below the outlet invert level. RECEIVED: 12/08/2026 GRAY CONSTRUCTION & DESIGN LTD Cornacreeve Dunraymond Co. Monaghan T : 047 85081 M: 086 0298424 E: grayconstructionanddesign@gmail .com This represents the normal operating level of a septic tank. The inspection was undertaken following an extended period of dry weather and after the dwelling had remained unoccupied for approximately ten years. The retained liquid level indicates there is no obvious evidence of leakage through the tank walls or base and no indication of significant groundwater infiltration into the tank. 3.4 Outlet Arrangement The outlet sanitary tee (dip pipe) remains in place and was found to be intact. The outlet arrangement is functioning correctly and continues to provide separation of floating sludge from the discharge to the percolation area. 3.5 Inlet Arrangement The inlet sanitary tee (dip pipe) is missing. Although wastewater can continue to enter the tank, the absence of the inlet sanitary tee reduces hydraulic efficiency by increasing turbul ence within the primary chamber. Replacement of the inlet sanitary tee is therefore recommended prior to the system being returned to service. 3.6 Pipework The visible inlet and outlet pipework comprises vitrified clay (crockery) pipework. No evidence of displacement, collapse or structural deterioration was observed during the inspection. 4. Historical Performance and Percolation Area The applicant has advised that the existing septic tank served the family dwelling throughout his childhood and adult life and that the system consistently operated satisfactorily during this period. The dwelling remained continuously occupied until approximately ten years ago. The applicant has confirmed that throughout this period no operational difficulties, surface ponding or wastewater breakout were experienced. Whilst this historical account is anecdotal, it is consistent with the findings of the present inspection. As part of the current assessment, the undersigned inspected the surrounding lands, including the adjacent field drains and the area surrounding the existing percolation area. No evidence was observed of: • wastewater breakout; • ponding; • sewage odours; • contaminated runoff; • unusually lush vegetation indicative of effluent discharge; • discharge of effluent to adjacent field drains or watercourses. These observations indicate that the existing percolation area continues to function satisfactorily and that there is no visible evidence of pollution associated with the wastewater treatment system. 5. Assessment Based upon the inspection undertaken, the existing septic tank is considered to be structurally sound. There was no evidence observed of: • structural cracking; • wall movement; • collapse; • deterioration of masonry; • groundwater infiltration; • abnormal loss of stored liquid; • failure of the outlet arrangement. RECEIVED: 12/08/2026 GRAY CONSTRUCTION & DESIGN LTD Cornacreeve Dunraymond Co. Monaghan T : 047 85081 M: 086 0298424 E: grayconstructionanddesign@gmail .com The retained water level following a prolonged period of vacancy provides a good indication that the tank remains substantially watertight. The satisfactory historical performance of the system over many years of occupation, together with the absence of any visible evidence of pollution or effluent breakout during the present inspection, provides further confidence that both the septic tank and associated percolation area continue to function effectively. The only defect identified during inspection was the absence of the inlet sanitary tee, which represents a minor maintenance item and can readily be replaced before the dwelling is reoccupied. Subject to the recommendations contained within this report, the existing septic tank and associated percolation area are considered fit for continued service in connection with the proposed replacement dwelling. 6. Planning and Legislative Context The proposed development comprises a replacement dwelling on an existing serviced site. The proposal represents the continuation of an established residential use and does not introduce wastewater disposal to a previously undeveloped site. The EPA Code of Practice – Domestic Waste Water Treatment Systems (Population Equivalent ≤10), 2021 provides guidance for the design and installation of new domestic wastewater treatment systems and replacement systems where new wastewater infrastructure is proposed. The Code does not require the automatic replacement of an existing septic tank solely due to its age where the existing installation can be demonstrated to be structurally sound, functioning satisfactorily and not giving rise to pollution. Similarly, the Water Services (Amendment) Act 2012 and the Water Services (Domestic Waste Water Treatment Systems) Regulations require domestic wastewater treatment systems to be maintained so that they do not present a risk to human health or the environment. The legislation does not require replacement solely because a planning application relates to a replacement dwelling. The inspection undertaken demonstrates that: • the existing septic tank remains structurally sound; • there is no evidence of significant leakage; • the surrounding lands show no evidence of wastewater breakout or pollution; • only minor remedial works are required before the system is returned to service. Retention of the existing septic tank therefore represents the sustainable reuse of existing infrastructure while avoiding unnecessary demolition and replacement works, provided that the recommendations contained within this report are implemented. 7. Recommendations Prior to occupation of the replacement dwelling, the following works are recommended: 1. Install a new uPVC inlet sanitary tee extending below the liquid level in accordance with current good practice. 2. Completely desludge the septic tank using an authorised waste contractor before the system is recommissioned. 3. Following desludging, undertake a further visual inspection of the tank to confirm no hidden defects become apparent once accumulated sludge has been removed. 4. Protect the existing percolation area throughout construction. The area should be clearly identified and fenced before construction commences. No construction traffic, excavation, storage of materials, spoil deposition or heavy plant should be permitted within the percolation area to avoid soil compaction. 5. Reinstate the existing concrete cover slabs securely following inspection. 6. Until construction is complete, securely fence off the septic tank and all associated manholes to prevent accidental access by site personnel and members of the public. 7. Inspect the septic tank periodically during its service life and desludge thereafter at intervals appropriate to occupancy, typically every 12–24 months, or as otherwise required to maintain efficient operation. RECEIVED: 12/08/2026 GRAY CONSTRUCTION & DESIGN LTD Cornacreeve Dunraymond Co. Monaghan T : 047 85081 M: 086 0298424 E: grayconstructionanddesign@gmail .com 8. Conclusion The inspection confirmed that the tank remains structurally sound with no evidence of cracking, settlement, deterioration or leakage. The retained liquid level following approximately ten years of vacancy further indicates that the tank remains substantially watertight. The applicant has confirmed that the system served the family home satisfactorily throughout many decades of occupation without any known operational difficulties. Inspection of the surrounding lands and adjacent field drains found no evidence of effluent breakout, surface ponding, contaminated runoff or any indication that the existing percolation area has failed. The only defect identified during inspection was the absence of the inlet sanitary tee, which is a minor maintenance item that can be readily replaced. Having regard to the physical condition of the septic tank, its satisfactory historical performance, the absence of any observable environmental impact and the recommendations contained within this report, it is my professional opinion that the existing septic tank and associated percolation area are fit for continued service and are capable of serving the proposed replacement dwelling without giving rise to unacceptable impacts on public health or the environment. ___________________________ Christopher Gray B.Sc (Hons) Const. Eng & Management. Dip. Ind.on RECEIVED: 12/08/2026