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