Table of Contents: Part One

1 Environmental Protection AgencyTable of Contents: part OneList of Figures xiList of Tables xiiPART ONE: CODE OF PRACTICE 11 Scope 12 References 23 Definitions 34 wastewater Characteristics 65 On-Site wastewater Treatment System Performance Performance Standards

2 86 Site Characterisation Desk Study On-Site Assessment Discharge Route Selecting an Appropriate On-Site Domestic wastewater Treatment and Disposal System Site Improvement Works Recommendations 187 Septic Tank Systems Septic Tanks Percolation Areas 218 Secondary Treatment.

3 Systems Constructed On-Site Soil Filter Systems Sand Filter Systems Drainage and Sealing of Filter Systems Mounded Intermittent Filter Systems Application of wastewater to Filter Systems Constructed Wetlands 339 Secondary Treatment: Packaged wastewater Systems Location of Packaged wastewater Systems 38 Environmental Protection Aerated Filter (BAF) Biological Contactor (RBC) Batch Reactor System (SBR) Filtration Filter Treatment Systems4110 Tertiary Treatment Polishing Constructed Packaged Tertiary Treatment Systems4511 Construction and Installation Septic Tanks and Secondary Treatment.

4 Package wastewater Infiltration Installation4812 Operation and Maintenance of wastewater Treatment Record Keeping 52 Environmental Protection AgencyxiList of FiguresFigure of wastewater treatment in line with EN 125667 Figure of source pathway target model10 Figure general guide to the selection of an on-site wastewater treatment system discharging to ground12 Figure and section of layout of septic tank system20 Figure section of a typical septic tank (all dimensions in mm)21 Figure of a percolation trench22 Figure percolation area23 Figure of a pumped distribution system26 Figure of intermittent filter system or constructed wetland system27 Figure diagram of an intermittent soil filter27 Figure sand filter system with underlying sand/subsoil polishing filter29 Figure cross section of stratified sand filter31 Figure sand filter overlying impervious subsoil/bedrock with offset polishing filter32 Figure soil filter (above ground)32 Figure subsurface flow reed bed34 Figure subsurface flow reed bed35 Figure of a biological aerated filter system (BAF)38 Figure of a rotating biological contactor (RBC) system39 Figure of a sequencing batch reactor (SBR)

5 System39 Figure layout of a membrane filtration system40 Figure of a packaged peat filter system41 Figure of a package system and polishing filter system42 Figure Infiltration trenches layout examples49 Environmental Protection Agencyxii List of TablesTable of raw domestic wastewater influent characteristics ( EN 12566-3:2005)6 Table domestic wastewater treatment minimum performance standards9 Table separation distances in metres14 Table requirements on-site for on-site systems discharging to ground14 Table of percolation test results16 Table septic tank capacity for various design populations21 Table trench length21 Table of a percolation trench (gravity fed)23 Table filter requirements28 Table filter requirements30 Table for constructed wetland systems receiving septic tank effluent35 Table soil polishing filter areas and percolation trench lengths required for a five-person house44 Table for sand-polishing filter45 Table for tertiary treatment45 Table for drain to septic tank47 Table , inspection and monitoring schedule52 Environmental Protection Agency1 part ONE.

6 CODE OF PRACTICE1 ScopeThis Code of Practice (CoP) is published underSection 76 of the Environmental ProtectionAgency Act, 1992 (as amended). part One setsout requirements for new on-site wastewatersystems used to treat and dispose of domesticwastewater from single houses with apopulation equivalent ( ) less than or equalto 10. It sets out a methodology that should befollowed to allow site conditions to beassessed, and an appropriate wastewatertreatment system to be selected, installed andmaintained, and it should be implemented infull. Guidance on good practice is included inPart Two; it should be considered as generalguidance as site conditions determineparticular site requirements. The guidanceinforms the implementation of the requirementsof part One. The code s requirements shouldbe supplemented as required by technicalskilled advice based on knowledge of sewageworks practice and local A provides the policy and legislationbackground to the development of this code replaces previous guidance issuedby the Agency in 2000 and incorporates therequirements of the Comit Europ en deNormalisation (European Committee forStandardisation) (CEN) European standardsprepared by CEN TC 165 and called the EN12566 series of standards: Small WastewaterTreatment Systems for up to 50 PT, researchfindings and feedback on previous guidancedocuments.

7 Following the guidance containedwithin the code does not remove yourobligation to comply with relevant legislationand to prevent pollution from your products and technologies, notspecifically covered by national or Europeanharmonised standards, should be certified(certification may include a EuropeanTechnical Approval, an Agr ment Certificate orequivalent), be fit for the purpose for which theyare intended, the conditions in which they areused, and meet the performance requirementsof this CoP. Where reference in the document is made toproprietary equipment, this is intended toindicate equipment type and is not to beinterpreted as endorsing or excluding anyparticular manufacturer or CoP also provides guidance to localauthorities where an existing system isproposed to be upgraded.

8 For dwellings withgreater than 10 people ( guest houses orcluster developments), the reader is referred toBS 6297:2007+A1:2008 Code of practice forthe design and installation of drainage fields foruse in wastewater treatment and EN 12255series wastewater Treatment Plants, theEnvironmental Protection Agency (EPA)manual wastewater Treatment Systems forSmall Communities, Leisure Centres andHotels (1999) and any further guidancedeveloped by the EPA including guidance inrelation to Section 4 discharges to surfacewaters or groundwater. To protect the environment and, in particular,water quality, houses in un-sewered areas mustbe on suitable sites and must have anappropriate wastewater treatment system thatis correctly installed and and builders who propose to buildhouses in un-sewered areas are required toundergo site assessments to ensure that thesite is suitable for an off-mains system.

9 Theyare responsible for their wastewater treatmentsystems and should follow all planningrequirements and guidance provided in thiscode of practice. The primary responsibility forprotecting waters against pollution rests withany person who is carrying on an activity thatpresents a threat to water of Practice: wastewater Treatment and Disposal Systems Serving Single Houses ( 10)Environmental Protection Agency22 ReferencesThe titles of the publications referred to in thiscode are listed in Annex I. The followingreferenced documents are required for theapplication of this document. For undatedreferences the latest edition of the referenceddocument applies. EN 12566-1:2000/A1:2004 SmallWastewater Treatment Systems for up to 50PT part 1: Prefabricated Septic Tanks(published by the NSAI1 as an IrishStandard).

10 CEN/TR 12566-2:2005 SmallWastewater Treatment Systems for up to 50PT part 2: Soil Infiltration Systems(published by the NSAI as a Code ofPractice). EN 12566-3:2005 Small WastewaterTreatment Systems for up to 50 PT part 3:Packaged and/or Site Assembled DomesticWastewater Treatment Plants (published bythe NSAI as an Irish Standard). EN 12566-4:2007 Small WastewaterTreatment Systems for up to 50 PT part 4:Septic Tanks Assembled in situ fromPrefabricated Kits (published by CEN). CEN/TR 12566-5:2008 Small Waste-water Treatment Systems for up to 50 PT part 5: Pre-treated Effluent FiltrationSystems (published by CEN as a technicalreport). prEN 12566-6 Small wastewater TreatmentSystems for up to 50 PT part 6:Prefabricated Treatment Units for SepticTank Effluent (in preparation).