integrated constructed wetlands regulatory aspects - the epa’s role aoife loughnane inspector,...
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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
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 - continuouslyBOD, 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)
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
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