Transcript EPA presentation on ICWs 28th June 2011.

Integrated Constructed Wetlands
Regulatory Aspects - the EPA’s role
Aoife Loughnane
Inspector, Environmental Licensing Programme
Environmental Protection Agency
28th June 2011
Presentation Overview
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EPA view on ICWs
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Discharge authorisations
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Types
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Information required
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Typical content
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Example
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EPA Code of Practice: WWT&D systems serving Single Houses
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ICW constraints
EPA view on Integrated Constructed Wetlands
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The EPA supports the concept of ICWs as an option for
dealing with low-nutrient effluents provided they are:
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located in suitable areas following a site suitability
assessment;
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designed, installed and maintained properly; and
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comply with a discharge authorisation to a suitable
receiving water.
Types of discharge authorisation
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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;
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Licence (agglomerations >500 p.e.)
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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
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Need to demonstrate sufficient assimilative capacity
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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.
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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
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Glaslough village, Co. Monaghan
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Agglomeration <2,000 p.e.
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Waste water infrastructure: gravity sewer
network, pumping station & associated rising
main, treatment of waste water in ICW
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ICW
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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
Glaslough: Emission limits & monitoring requirements
Parameter
Emission Limit Value (mg/l)
BOD
10
COD
50
Suspended Solids
15
Ammonia (as N)
1
Orthophosphate (as P)
0.5
Monitoring
Frequency
Primary discharge
Flow - continuously
BOD, COD, SS, conductivity - monthly
Nitrates, Ammonia, Total & ortho-P – quarterly
Receiving water (up & downstream)
pH, DO, BOD, Ortho-P, Total N, Ammonia quarterly
Lysimeters (effluent percolating through
liner)
As required by the Agency
Ambient groundwater
Biannually
EPA Code of Practice for Waste Water Treatment and
Disposal Systems Serving Single Houses (p.e. ≤ 10)
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Single houses
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Legal requirement – Building Regulations 2010
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CWs can be used to provide:
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Secondary treatment to effluent from septic tanks, or
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Tertiary treatment to effluent from packaged WWT
systems.
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Polishing filter should follow CW when discharge
route is to groundwater
EPA Code of Practice...ICW criteria for Single Houses
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CWs should be sealed by a clay liner
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permeability k ≤ 1.0 x 10-8 m/s.
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Design is site specific.
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Designer & installer must be a competent person.
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Size is dependent on quality of receiving water
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Other measures may be added to further enhance treatment
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All ICWs require periodic maintenance.
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Guidance EN 12566 Small Wastewater Treatment Systems for up to
50PE – Part 5: Pre-Treated Effluent Filtration Systems.
ICW constraints – the EPA’s experience
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Unsuitable for wastewaters with high nutrient loading
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Not suitable in all locations
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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.
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Phosphorus accumulation in sediments–must be removed periodically
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High ammonium concentrations in underlying groundwater – risk to
nearby receiving waters
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Planning permission & discharge authorisation required prior to
construction and operation.
Integrated Constructed Wetlands
Regulatory Aspects - the EPA’s role
Aoife Loughnane
Inspector, Environmental Licensing Programme
Environmental Protection Agency
28th June 2011