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Integrated Constructed Wetlands Regulatory Aspects - the EPA’s role. Aoife Loughnane Inspector, Environmental Licensing Programme Environmental Protection Agency 28 th June 2011. Presentation Overview. EPA view on ICWs Discharge authorisations Types Information required Typical content
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Integrated Constructed WetlandsRegulatory Aspects - the EPA’s role Aoife Loughnane Inspector, Environmental Licensing Programme Environmental Protection Agency 28th June 2011
Presentation Overview • EPA view on ICWs • Discharge authorisations • Types • Information required • Typical content • Example • EPA Code of Practice: WWT&D systems serving Single Houses • ICW constraints
EPA view on Integrated Constructed Wetlands • The EPA supports the concept of ICWs as an option for dealing with low-nutrient effluents provided they are: • located in suitable areas following a site suitability assessment; • designed, installed and maintained properly; and • comply with a discharge authorisation to a suitable receiving water.
Types of discharge authorisation • An ICW requires a discharge authorisation prior to construction and operation, either by: (a) Water Pollution Act discharge licence to surface water; (b) Urban Waste Water Discharges; • Licence (agglomerations >500 p.e.) • Certificate of Authorisation (agglomerations <500 p.e.) (c) IPPC Licence; (d) Waste Licence.
Information required in an application for a discharge authorisation 1. Source, quantity and quality of proposed effluent entering ICW 2. Details of site assessment 3. ICW design & layout 4. Quantity & quality of proposed ICW discharge to receiving waters 5. Details of proposed receiving water • Need to demonstrate sufficient assimilative capacity • Need to identify potential impacts & mitigation measures
Typical content of a discharge authorisation 1. Quantity & quality of waste water permitted to enter the ICW. 2. Emission limit values for ICW discharge to receiving water. • Final effluent quality • Discharge rate & volume • Period during which a discharge may or may not be made. 3. Monitoring requirements. 4. Reporting requirements.
Glaslough Waste Water Discharge Licence • Glaslough village, Co. Monaghan • Agglomeration <2,000 p.e. • Waste water infrastructure: gravity sewer network, pumping station & associated rising main, treatment of waste water in ICW • ICW • 5 ponds, combined surface area of approx. 3.4 ha • Low permeability in-situ clays (k < 1 x 10-9 m/s) • Design capacity is 1,750 p.e. • Current loading is approx. 1,400 p.e. • Primary discharge to the Mountain Water River
EPA Code of Practice for Waste Water Treatment and Disposal Systems Serving Single Houses (p.e. ≤ 10) • Single houses • Legal requirement – Building Regulations 2010 • CWs can be used to provide: • Secondary treatment to effluent from septic tanks, or • Tertiary treatment to effluent from packaged WWT systems. • Polishing filter should follow CW when discharge route is to groundwater
EPA Code of Practice...ICW criteria for Single Houses • CWs should be sealed by a clay liner • permeability k ≤ 1.0 x 10-8 m/s. • Design is site specific. • Designer & installer must be a competent person. • Size is dependent on quality of receiving water • Other measures may be added to further enhance treatment • All ICWs require periodic maintenance. • Guidance EN 12566 Small Wastewater Treatment Systems for up to 50PE – Part 5: Pre-Treated Effluent Filtration Systems.
ICW constraints – the EPA’s experience • Unsuitable for wastewaters with high nutrient loading • Not suitable in all locations • Groundwater protection requirements: • Minimum of 1m subsoil beneath ponds, • Upper 0.5m having a maximum permeability of 1.0 x 10-8 m/s • Greater subsoil thickness required above karstified and sand/gravel aquifers. • Phosphorus accumulation in sediments–must be removed periodically • High ammonium concentrations in underlying groundwater – risk to nearby receiving waters • Planning permission & discharge authorisation required prior to construction and operation.
Integrated Constructed WetlandsRegulatory Aspects - the EPA’s role Aoife Loughnane Inspector, Environmental Licensing Programme Environmental Protection Agency 28th June 2011