ICW Ahascragh

s Development of an Integrated Constructed Wetland at Ahascragh, Co Galway Appropriate For assessment inspection purposes only. (screening) Consent of copyright owner required for any other use. Report for Galway County Council August 2013 Roger Goodwillie & Associates, Lavistown House, Kilkenny. Ph/Fax 056-7765145 EPA Export 15-08-2013:23:44:26 1. INTRODUCTION The purpose of this report is to supply enough information for the Local Authority to make an appropriate assessment of the proposed development with regard to its potential impacts on the Natura 2000 network of protected areas. In this it fulfils the mandatory requirement under Articles 6(3) and 6(4) of the Habitats Directive. It follows the outline of the NPWS Guidance document (DoEHLG 2009). The report makes use of field information collected in August 2013 and was requested by Damien Mitchell, Water Services, Galway County Council. A site description is given at the outset for background information, using the habitat types of Fossitt (2000). 2. DESCRIPTION OF SITE 2.1 Habitats & Flora The existing treatment works is located south-east of the town and close to the Ahascargh River, a tributary of the Suck. It is surrounded by grassland on a peaty, alluvial soil. The western field has been drained and now supports improved agricultural grassland (GA1 in Fossitt 2000) while the eastern part carries wet grassland (GA4), grazed by sheep in summer. The surface is poached so probably has cattle in winter. The dominant plants are soft rush Juncus effusus, crested dogstail Cynosurus cristatus, tufted hairgrass Deschampsia cespitosa and marsh ragwort Senecio aquaticus but the community is relatively diverse, also including Trifolium repens white clover Carex demissa yellow sedge Potentilla anserina For inspectionsilverweed purposes only. Ranunculus acris Consent of copyright ownermeadow required for buttercup any other use. Hypochaeris radicata catsear Leontodon autumnalis autumn hawkbit Filipendula ulmaria meadowsweet Juncus articulatus jointed rush Cirsium palustre marsh thistle Rumex acetosa sorrel Festuca arundinacea tall fescue Calliergonella cuspidata a moss Ranunculus flammula lesser spearwort Succisa pratensis devilsbit The land rises slightly away from the river so that the proportion of grasses in the vegetation increases to the north. The river itself has a natural profile and has not been deepened recently. It supports an abundance of plant growth on shoals on the gravel and cobble base. The bank is lined by yellow flag Iris pseudacorus, tall fescue Festuca arundinacea, hairgrass Deschampsia 1 EPA Export 15-08-2013:23:44:26 cespitosa, nettle Urtica dioica and hairy sedge Carex hirta giving onto the aquatic species in the water, e.g. Phalaris arundinacea reed canary grass Oenanthe aquatica fine-leaved water dropwort Berula erecta lesser water parsnip Apium nodiflorum fool’s watercress Schoenoplectus lacustris common clubrush Ranunculus cf peltatus water crowfoot Callitriche cf platycarpa water starwort Sparganium erectum branched bur reed Below the existing outflow Berula erecta is largely replaced by Apium nodiflorum while Schoenoplectus lacustris also becomes abundant. Fauna The river has a typical associated birdlife and both moorhen and heron were seen. It is likely to have a good population of otters as the feeding conditions are ideal. Kingfisher would also be expected. The adjacent wet grassland is a habitat for snipe in winter and meadow pipit at all times of the year. It is not extensive enough to be used by wildfowl which, if present, would frequent the opposite side of the river. 2.3 Ecological evaluation The habitat around the existing works For is inspection characteristic purposes only. of the general area having the ‘original’ wet grassland and itsConsent improved of copyright version owner required in the for any two other adjacent use. fields. The wet grassland has the broader range of species though it is rather uniform without rare plants. The Ahascragh River is of considerable interest with a natural profile and vegetation, at least in this limited section. 3. APPROPRIATE ASSESSMENT SCREENING 3.1 Introduction Appropriate assessment was introduced by the EU Habitats Directive as a way of determining during the planning process whether a project is likely to have a significant effect on one of the Natura 2000 sites so far designated (i.e. the candidate SAC’s and SPA’s), or their conservation objectives. In this case the site is the River Suck callows (Site Code 4097). Article 6(3) states 2 EPA Export 15-08-2013:23:44:26 Any plan or project not directly connected with or necessary to the management of the site but likely to have a significant effect thereon, either individually or in combination with other plans or projects, shall be subject to appropriate assessment of its implications for the site in view of the site’s conservation objectives…. In the Irish context this has been interpreted as a four stage process. Firstly a screening exercise (Stage 1, this document) determines if a project could have significant effects on a Natura site. The project should be screened without the inclusion of special mitigation measures unless potential impacts can clearly be avoided through design (or re-design). If impacts are identified or the situation is unclear a Natura Impact Statement (Stage 2) is provided to the planning or regulatory authority which then conducts an Assessment of the information supplied. Examples of significant effects are loss of habitat area, fragmentation of the habitat, disturbance to species using the site and changes in water resources or quality. If such negative effects come to light in the assessment, alternative solutions are investigated by the proponent (Stage 3) and modifications made unless the project is deemed to be driven by ‘imperative reasons of overriding public interest’ in its current form. If this is the case, Stage 4 then deals with compensatory action. 3.2 Project description The proposal is for an integrated constructed wetland to treat the outflow from the present works (which only achieves primary treatment). The wetland would consist of four ponds or lagoons, planted with vegetation and receiving the effluent in sequence. The final pond would discharge to the Ahascragh River with an effluent quality in line with the Urban Wastewater Directive (The EPA have not laid down appropriate discharge parameters for treatment facilities, such as the subject one, that require Certificates of Authorisation.) The Ahascragh River joins the Suck (as the Bunowen) after a course of about 8km. An integrated constructed wetland in Laois (below) gives an example of outflows (Carty, pers.comm.) which are typically in the For rangeinspection ofpurposes BOD only. 5-10mg/l, Suspended solids 5-10mg/l, ammonium <1mg/l and total phosphorusConsent of copyright <1mg/l. owner required for any other use. Clonaslee ICW Discharge mg/l (mean performance values May 2012 - January 2013) Suspended Ammonia Total nitrogen Total phosphorus Parameter BOD mg/l COD mg/ solids mg/l mg/l mg/l mg/l Ortho-phosphate mg/ Discharge/Cell 5 4.3 21l 3.4 0.28 1.24 0.04 0.008l Emission Limit Values 5 15 4 1 3.3 Natura 2000 sites There is only one Natura 2000 site within 15km of the site (see map at end), namely the River Suck Callows SPA. However there are three raised bog NHA’s – Killure Bog (Site Code 1283), Crit Island West bog (0254) and Annaghbeg Bog (2344). 3 EPA Export 15-08-2013:23:44:26 The Suck is a river and floodplain habitat that supports high numbers of wintering birds, especially whooper swan, Greenland white-fronted geese and lapwing (see site synopsis in Appendix 2). Both whooper and mute swans have reached numbers of international importance in the recent past (Crowe et al 2011, 2012) though the white-fronted goose is rarer than formerly. The list of important organisms and habitats for the whole complex is given below in the Conservation Objectives. 3.4 Conservation Objectives Objective: To maintain or restore the favourable conservation condition of the bird species listed as Special Conservation Interests for this SPA, i.e. Cygnus cygnus [wintering] – whooper swan Anas penelope [wintering] – wigeon Pluvialis apricaria [wintering] – golden plover Vanellus vanellus [wintering] – lapwing Anser albifrons flavirostris [wintering] – Greenland white-fronted goose Wetlands The favourable conservation condition of a habitat is achieved when: its natural range, and area it covers within that range, are stable or increasing the specific structure and functions which are necessary for its long-term maintenance exist and are likely to continue to exist for the foreseeable future the conservation status of its typical species is favourable. The favourable conservation status of a species is achieved when: For inspection purposes only. population dynamicsConsent ofdata copyright on owner the requiredspecies for any concerned other use. indicate that it is maintaining itself on a long-term basis as a viable component of its natural habitats the natural range of the species is neither being reduced nor is likely to be reduced for the foreseeable future there is, and will probably continue to be, a sufficiently large habitat to maintain its populations on a long-term basis. 4.5 Likely effects The water quality in the Ahascragh River is good (Q4) for most of its course, except below the town where it falls to Q3 (see Appendix 1). This is most likely caused by the input from the present wastewater works. To add tertiary treatment to the works in the form of a constructed wetland will obviously improve matters considerably in the Ahascragh River and result in excellent habitat conditions along its whole length for pollution-sensitive organisms. 4 EPA Export 15-08-2013:23:44:26 Local impacts on the river from construction works can be prevented by mitigation measures which should be developed in consultation with IFI. The effects of this work on the SPA will be neutral because the organic load has been assimilated by the time the Ahascragh joins the Suck.

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