10. WATER AND EFFLUENT

Transcription

1 10. WATER AND EFFLUENT 10.1 General This Chapter addresses the issues of water quality and aqueous emissions associated with the proposed development and includes an assessment of their potential impact on the local marine/estuarine environment. It is proposed that all effluent from the facility will be treated on-site and will be discharged via the existing IDA / Cork County Council (CCC) marine outfall pipe in Cork Lower Harbour. Uncontaminated surface water from the site will be discharged to Loughbeg in Cork Lower Harbour (Figure 10.1). Water quality data for Cork Harbour is available to support the assessment of potential water quality impacts, with numerous water quality surveys having been carried out on Cork Harbour since the 1970 s The Receiving Environment Description of Receiving Waters (Marine/Estuarine Environment) Cork Harbour is a natural harbour and is Ireland's largest estuary and second largest Port. The Harbour itself is occupied by a series of large and small islands, the largest of which is Great Island upon which the town of Cobh is situated. It consists of two main sections, the upper harbour which includes Lough Mahon and the outer Lee Estuary and the lower harbour area. The waters of the lower harbour are well mixed with salinities typical of coastal marine waters. The proposed treated effluent discharge will be via the existing IDA marine outfall pipe to Cork Lower Harbour. This outfall terminates in the deepwater channel at Dognose Bank. Uncontaminated surface water is proposed to be discharged to Loughbeg, a tidal inlet on the Ringaskiddy Peninsula in the Cork Lower Harbour area. Figure 10.1 shows the proposed aqueous discharge locations. Loughbeg is designated a proposed Natural Heritage area due to its estuarine habitats and bird interests. It also forms part of the larger Cork Harbour Special Protection Area which is of international importance on account of its wintering waterfowl Sensitive Area / Waters Designation Under the Urban Waste Water Treatment Directive (91/271/EEC), Sensitive Areas with regard to eutrophication are defined as: waters which are found to be eutrophic or may become eutrophic if protective action is not taken. The Environmental Protection Agency Act 1992 (Urban Waste Water Treatment) Regulations, 1994 gave effect to this Directive in Ireland. The waters of Cork Outer Harbour are not classified as sensitive (to eutrophication) under these or subsequent Regulations. Under the more recent Urban Waste Water Treatment (Amendment) Regulations, 2004, two areas in Cork Harbour were designated as sensitive areas, as follows; S:\Projects\190900\ Centocor\EIS\ RP-0001 A.doc 127 EPA Export :18:19:08

2 Lee Estuary/ Lough Mahon from the salmon weir (downstream of waterworks intake) to Monkstown (excluding North Channel at Great Island) Owenacurra Estuary / North Channel from North Channel (Great Island) upstream of Marloag Point including Owennacurra Estuary upstream to Dungourney river confluence While the Lower Harbour Area has not been designated as sensitive, the design of all aspects of the Centocor facility that might affect the marine environment is been progressed on the basis that the water body could be designated as sensitive some time in the future Existing Receiving Water Quality The importance of Cork Harbour in terms of industry, commerce and recreation has resulted in a large number of water quality studies being carried out over the last few decades. The quality of water in the Harbour is also monitored by the EPA and is recorded in their regular reports on Water Quality in Ireland. The most recent information on the water quality in Cork Harbour published by the EPA (in 2002) is based on results of monitoring and analyses undertaken during the period 1998 to The most relevant data in the EPA publication for this EIS relate to the area called Outer Cork Harbour due to the proposal to discharge the treated effluent from the facility via the existing marine outfall from Ringaskiddy which extends to the deepwater channel at Dognose Bank, located at the Harbour mouth. Outer (or Lower) Cork Harbour water quality results for the period are summarised in Table 10.1 below. Table 10.1 Summary Water Quality Statistics for Cork Harbour (Outer Harbour) (EPA, 2002) Summary Statistics ph DO % Saturation B.O.D. mg/l TON mg/l NH 3 /NH 4 mg/l N DIN mg/l N MRP ug/l P DIN:DIP Ratio Minimum Median Maximum Where DO % Saturation = Dissolved oxygen relative to normal for ambient temperature and pressure. BOD 5 = 5-day Biochemical Oxygen Demand TON = Total Oxidised Nitrogen (Sum of nitrate and nitrite) NH 3 /NH 4 = Total Ammonia Nitrogen (sum of un-ionised ammonia and ammonium) DIN = Dissolved Inorganic Nitrogen (sum of TON and NH 3 /NH 4 ) and considered to represent bio-available phosphorus MRP= Molybdate Reactive Phosphorus (considered to represent bio-available dissolved inorganic phosphorus) DIP = Dissolved Inorganic Phosphorus concentration Overall, the EPA report concludes that water quality in the Outer Harbour has remained good although there were indications of an increase in chlorophyll concentrations in these waters since the previous EPA review. Notwithstanding this, the Outer Harbour received a non-eutrophic status. S:\Projects\190900\ Centocor\EIS\ RP-0001 A.doc 128 EPA Export :18:19:08

3 IDA/CCC Sewer Centocor Site Centocor Treated Effluent Discharge to IDA/CCC Sewer Cork Harbour (lower) Centocor Surface Water Discharge Loughbeg IDA/CCC outfall to Dognose Bank Figure Routes of Treated Effluent & Surface Water to Cork Harbour Centocor Biologics - Environmental Impact Statement - Chapter 10 Project No: Document No: RP-0001 Date: April 2005 EPA Export :18:19:08

4 The dissolved oxygen concentration in the water in this area was within the normal range expected in natural waters at a median concentration of 95% DO saturation recorded. BOD, ammonium and orthophosphate concentrations in the Outer Harbour were generally low with occasional high values in the Ringaskiddy/Cobh area resulting from the outflow of enriched waters from Lough Mahon. Phosphorus in natural waters is usually found in the form of phosphates (PO 4-3 ) which can be in inorganic form (including orthophosphates and polyphosphates), or organic form (organically-bound phosphates). Orthophosphate is regarded as the predominant, most biologically available and most stable form of phosphorus (and phosphates) in natural waters. Nitrogen availability was lower relative to that of phosphate in the Lower Harbour waters with nitrogen regarded as being the limiting nutrient though approximately a quarter of samples indicated P to be the limiting nutrient. In comparison to the good water quality of Cork Outer Harbour, the water quality data for the Inner Harbour ( ) indicated poor water quality and resulted in a corresponding eutrophic classification for these waters. Water quality in the Harbour is expected to improve in the long-term with the recent commissioning of the Cork City municipal waste water treatment plant at Carrigrennan and the plants to construct a new municipal WWTP to serve the population centres of the Lower Harbour area (Carrigaline, Cobh, Ringaskiddy, Monkstown, Passage and Crosshaven) Receiving Water Assimilative Capacity The assimilative capacity of a waterbody can be defined as: The amount of pollution a water body can receive without noticeable degradation, as a result of the natural ability of the water and its associated chemical and biological systems to dilute or transform contaminants Commonly, the assimilative capacity is measured in terms of the receiving waters capacity to assimilate BOD 5. A report by MC O Sullivan (1978) on Cork Harbour examined assimilative capacities and reported assimilative capacities for BOD 5 at a number of locations in Cork Harbour as follows: Ram s Head Bank (near IDA Ireland long sea outfall) approx. 300,000 kg/d Marino Point (Passage West) approx. 30,000 kg/d Cork County Council currently limits the total permissible BOD 5 emission from the marine outfall at Ringaskiddy to 90,000 kg/d. It is proposed that any surface water produced on site will be discharged to Loughbeg. The assimilative capacity of the outer sections of Loughbeg has been estimated at 2,700 kg BOD/day. S:\Projects\190900\ Centocor\EIS\ RP-0001 A.doc 129

5 Current Discharges to Receiving Waters There are numerous industrial facilities located in the Outer Harbour area particularly in the Ringaskiddy Peninsula. These licensed facilities discharge their treated wastewater (under IPPC or County Council discharge licence) to the Outer Harbour waters at various outfall locations, but primarily through the IDA / Cork County Council marine outfall to Dog Nose Bank (Ref. Figure 10.1). In terms of municipal wastewater, significant quantities are currently being discharged untreated at various outfall locations into the Outer Harbour area. These wastewater discharges originate from the population centres of Passage West, Monkstown, Ringaskiddy, Crosshaven and Cobh. The marine outfall at Ringaskiddy currently discharges untreated municipal wastewater from Carrigaline and Shanbally into the deepwater channel of the Harbour at Dognose Bank. However, Cork County Council plans to construct a municipal wastewater treatment plant (60,400 population equivalent) which would treat the raw urban wastewater from the population centres of the Lower Harbour area and discharge via this outfall. In terms of BOD 5 it is estimated that the following loads are currently discharged through the Ringaskiddy marine outfall: Treated Industrial Effluent (based on licensed limits) Untreated Municipal Wastewater (based on populations) ~20,000 kg/day ~1,500 kg/day As such, the current BOD 5 load discharged to Dog Nose Bank is in the order of 7% of the calculated assimilative capacity, and 24% of the limit being applied by Cork County Council Freshwater Environment There are no watercourses or drainage ditches within or adjacent to the proposed site with the exception of a small artificial pond in the eastern portion of the site (Figure Habitats Map). As discussed in Chapter 8, Flora & Fauna, the pond is of apparent poor water quality, absent of wetland vegetation and consequently has low conservation value. As part of an ecological assessment carried out by BES the removal of the pond was determined not to be significant and as such, in the context of the proposed development, impacts on the freshwater environment are not considered further Effluent Management Construction Phase Sewage The construction phase of the project will see a maximum of 700 workers on the site over a period of up to 27 months. To accommodate this work force, and to ensure clean and effective sanitary services during the construction period, it is proposed to install a temporary biological wastewater treatment plant as part of the early site development work. The plant will be a fully contained package type system that will include its own balance tank, biological secondary treatment system and clarifier. The plant will be capable of achieving a consistent effluent quality standard of 25mg/l BOD and 35 mg/l suspended solids i.e., a standard comparable with the levels specified in the EU Urban Wastewater Treatment Directive. While not required, this is a positive and proactive approach to the management of sewage arising at the Centocor construction site. The treated S:\Projects\190900\ Centocor\EIS\ RP-0001 A.doc 130

6 effluent from the construction stage treatment plant will discharge to the local public sewer which connects to the marine outfall. The package plant will remain in operation until such time as the proposed permanent on-site wastewater treatment is commissioned and available. At this time all sewage arising on site will be connected to the permanent plant for treatment with the other (process) wastewaters from the facility (see section 10.4 below) Surface Water Run-Off Sediment deposition can be a potential pollutant in surface waters where excessive sediment and debris that settle at the bottom of surface waters can affect animal and plant habitats. There is the potential for surface water run-off to occur during construction activities at the Centocor site. Significant regrading of the site development area over 6 hectares has the potential to alter the surface water run-off profile of the site. Currently, the undeveloped site exhibits very good natural permeability and drainage with no evidence of ponding or adverse run-off patterns during intense or prolonged rainfall events. While the permeability of the site will remain high after the initial site development works, the laying of hardcore over the cut area will potentially decrease the permeability over this portion and lead to an increase in run-off quantity. There is also potential for the formation of new spring lines where the excavation cut intercepts the water table. It is planned that the construction site will be established so as to channel any excess surface water from the development area towards the south east corner of the site, to the proposed location of the Retention Pond (see section below) which is the lowest part of the site. The intention is to carry out the excavation for the Retention Pond as part of the early site development works so that this basin can be use to collect excess surface run-off. The basin will be designed to work as a sedimentation pond that will allow sediments within the surface water to settle out under gravity. The sedimentation pond will be connected to the new large diameter surface water sewer which has recently be laid from this point down to the final discharge point at Loughbeg. The invert level of the surface water sewer will be maintained a level well above the base of the pond to ensure an adequate settlement volume within the pond. The connection from the pond to the surface water sewer will be baffled, which will further help to prevent the carry over of sediments into the sewer Effluent Management - Operating Facility General The biotechnology processes to be used at the Centocor facility will generate a range of aqueous waste streams containing biodegradable organic components and nutrients. The utility equipment that will be provided at the facility to support the production process will also generate aqueous streams containing low levels of biodegradable organics. Sanitary wastewater (sewage) will also arise due to approximately 330 full-time staff at the facility. As outlined in section 10.1, the location of the proposed facility at Barnahely dictates that the route for final disposal of wastewater from the site will be via the existing long sea outfall to Dog Nose Bank (Figure 10.1). Because there is no off-site treatment available for industries located on the Ringaskiddy Peninsula, S:\Projects\190900\ Centocor\EIS\ RP-0001 A.doc 131

7 Centocor will be providing full treatment of their wastewater streams within the site prior to discharge to the local sewer and outfall. This will be in compliance with conditions as will be imposed by Centocor s IPPC licence and the guidance given in the relevant industry sector BATNEEC notes for discharge to waters. For the nature of the wastewater associated with the Centocor facility, biological secondary treatment is the accepted technology defined in the BREF and BATNEEC guidance documents for the industry sector Characteristics of the Site Wastewater Wastewater for treatment will arise from all four building within the site, but primarily from the Production and Central Utilities Plant (CUP) blocks. The basic characteristics of the streams from the buildings are as follows: Production Building Inactivated pre-culture, cell culture and harvest waste streams Waste streams from recovery, purification and formulation Clean in Place (CIP) wash waters medium strength BOD/COD, high nitrogen, high phosphorus, low solids. Centralised Utilities Plant Reverse Osmosis (RO) reject Water softener brine Boiler / cooling tower blowdown low BOD/COD, medium TDS. Laboratories minor flows. sanitary wastewater normal sewage from all four buildings. The potential presence of cells in the effluent stream does not pose a risk to the environment, as evidenced by the fact that the site is classified as the lowest possible risk category under the Contained Use Regulations (S.I. No. 73 of 2001). Further, the waste streams potentially containing residual cells are heat inactivated prior to being sent to the WWTP. The volume of wastewater requiring on-site treatment and disposal is currently estimated to be in the order of 400 m 3 /day. Medium to long term plans to expand the production and associated utility capacity of the facility would see this volume increase to 800m 3 /day. A summary of the anticipated average raw process effluent concentrations (excluding sewage) in provided in the Table S:\Projects\190900\ Centocor\EIS\ RP-0001 A.doc 132

8 Table 10.2 Anticipated Raw Wastewater Characteristics Effluent Parameter Average Concentration (mg/l) COD 1,700 BOD 600 TKN 250 NH 4 -N < 75 NO 3 < 10 NO 2 < 1 Total P 140 SO 4 60 TSS 40 TDS 2,200 Parameters such as heavy metals and chlorinated solvents are not a feature of Centocor s activities and as such will not arise in meaningful quantities in the effluent stream Wastewater Discharge Standards The licensing and control of the treated effluent discharge from the Centocor facility will be defined under the terms of the IPPC Licence to be issued by the EPA. It can be anticipated that the minimum requirements for effluent quality from the plant will be to meet the emission limit values (ELVs) currently set out in the BATNEEC Guidance Notes for the Chemical Sector, for discharge to waters. As such, the minimum standards as applicable to the Centocor discharge will be: Table 10.3 Minimum Wastewater Discharge Standards (BATNEEC) Parameter Units Minimum Standard ph ph units 6-9 COD mg/l COD removal >75%, thus < 425 mg/l BOD mg/l BOD removal >91%, thus < 54 mg/l Total Ammonia (as N) mg/l <10 mg/l Oils, Fats & Grease mg/l <10 mg/l Toxicity Units mg/l 10 Genetically Modified Micro-organisms Inactivated in accordance with 98/81/EC and SI 73 of 2001 In addition to the above minimum BATNEEC standards, the design of the wastewater treatment plant will achieve significant reductions in the other pollutant parameters, most notably Nitrogen and Phosphorus. As previously outlined, the waters of Lower Cork Harbour are not designated as sensitive under the Irish Regulations which transpose the EU Directive S:\Projects\190900\ Centocor\EIS\ RP-0001 A.doc 133

9 concerning Urban Wastewater Treatment. Consequently, reductions in Nitrogen and/or Phosphorus prescribed in BATNEEC for discharge to sensitive waters do not apply. Despite this, the design of the Centocor WWTP in accordance with the principles of BAT is such that significant reductions in Nitrogen and Phosphorus will be achieved. The expected minimum discharge standards for these parameters from the plant are set out below. Table 10.4 Minimum Wastewater Discharge Standards (TSS & Nutrients) Parameter Units Minimum Standard TSS mg/l 30 Total-N mg/l 150 Total-P mg/l Description of the WWTP The following section describes the various unit operations and elements proposed to be included in the on-site WWTP at the Centocor Biologics facility. The plant will be designed to effectively and consistently achieve the emission limit values that will be prescribed in the site IPPC licence and as may presently be anticipated through the BATNEEC guidance notes for the industry sector. The proposed plant is discussed under the following headings: Wastewater Collection Preliminary Treatment Secondary Biological Treatment Sludge Treatment Odour Management WWTP Buildings Monitoring The plant is being designed to provide full secondary biological treatment to all process and sanitary wastewater arising from the facility. The plant will meet the specific principles of BATNEEC and BAT (best available techniques) for industrial wastewater treatment. Figure 10.2 is a schematic representation of the way in which the various wastewater streams from the site will be collected, treated and discharged. Figure 10.3 shows a preliminary layout of the proposed WWTP. Wastewater Collection Process effluent from the manufacturing building, lab/admin building, warehouse and CUP will drain by gravity to the external site underground process effluent drainage system. Process effluent from the manufacturing building that potentially contains cells from the process (pre-culture, cell culture and harvest) will be collected S:\Projects\190900\ Centocor\EIS\ RP-0001 A.doc 134

10 MANUFACTURING Wastewater Containing Cells HEAT INACTIVATION Steam Domestic (Foul) Wastewater From All Four Buildings Screening SLUDGE TREATMENT (DEWATERING) Dewatered Sludge For Off Site Disposal LABS/ADMIN WAREHOUSE CUP Process Wastewater (CIP s etc.) From All Four Buildings PRELIMINARY TREATMENT (BALANCING/ NEUTRALIZATION/ COOLING ) Emergency Return Only SECONDARY BIOLOGICAL TREATMENT (AERATION/ DENITRIFICATION) Surface Water Run Off From Site RETENTION POND CLARIFICATION (MEMBRANE OR SETTLEMENT) MONITORING FLOW MONITORING & SAMPLING Final Discharge To IDA/CCC Sewer & Outfall To Dog Nose Bank Discharge Of Clean Surface Water To IDA/CCC Sewer To Lough Beg Figure Waste Stream Collection & Treatment Schematic Centocor Biologics - Environmental Impact Statement - Chapter 10 Project No: Document No: RP-0001 Date: April 2005

11 N FOUL FOUL SEWER SEWER PROCESS PROCESS SEWER SEWER ENTRANCE TO FACILITY 300ø STORM SEWER PETROL INTERCEPTION (FROM CAR PARK) CONNECTION TO IDA/MCC FOUL SEWER & OUTFALL RETENTION POND 600ø 600ø STORM STORM SEWER SEWER OFF-SPEC TANK SLUDGE TREATMENT / LAB / OFFICE / MCC BUILDING COOLING TOWERS PUMPS EQUALISATION TANKS BLOWERS MEMBRANES PIPE RACK SLUDGE TANK INLET TANKS PUMPS CHEMICAL AERATION DENITRIFICATION FANS PEAT BED FILTER PIPE RACK PUMPS INLET EQUIPMENT IN ENCLOSED ABOVE DENIT. TANK CONNECT TO IDA/MCC SURFACE WATER SEWER SITE VALVE CHAMBER ENTRANCE TO WASTEWATER TREATMENT AREA TREATED EFFLUENT FLOW MONITORING & SAMPLING CHAMBER 0 10m 20m Figure Priliminary Wastewater Treatment Plant Layout Centocor Biologics - Environmental Impact Statement - Chapter 10 Project No: Document No: RP-0001 Date: April 2005

12 separately and drained to a sump external to the manufacturing building. From this sump, the cell-contented stream will be pumped to a heat inactivation system located in the CUP building. The heat inactivation system contains an enclosed tank which is fed with steam. The purpose of this system is to raise the temperature of the contents to a prescribed level for a period of time that effectively kills the cells in the waste steam. The inactivated waste steam then combines with the general process wastewater stream before being directed by underground gravity drainage to the inlet of the WWTP. All external underground process drainage will be double contained high resistant Fibre Reinforced Plastic (FRP) pipework. Domestic wastewater (sewage) will arise from all four buildings and will be collected externally in a dedicated underground drainage system. Domestic wastewater will be collected in a separate balance tank at the WWTP area. Preliminary Treatment At the WWTP, preliminary treatment consisting of the following elements, will be provided for the process wastewater stream: Flow and loads balancing - Equalisation Tank Process and WW cooling - Heat Exchanger Neutralisation - 2 stage neutralisation tanks with acid & caustic dosing Separate preliminary treatment of the domestic wastewater (sewage) in the form of balancing, maceration and fine screening will also be provided. The screened domestic wastewater will combine with the process effluent prior to entering the 2-stage neutralisation tanks. The purpose of the screening and maceration is to remove gross solids from the wastewater that could affect the downstream secondary treatment process. The front-end part of the WWTP will also include an off-spec tank. This tank will be provided in the event that wastewater that exceeds the basic parameters that can safely be treated in the WWTP arrive at the plant. In this even, the off-spec wastewater will be diverted to the off-spec tank for temporary storage. Subsequently, the off-spec contents can be fed in small quantities back into the WWTP for treatment under controlled conditions. Secondary Biological Treatment The proposed WWTP will include secondary biological treatment consisting of the following elements: Pre-denitrification tanks designed for the reduction of the total nitrogen-n load. This tank is located upstream of the aeration tank. Aeration tanks designed for the removal of carbonaceous BOD and COD. The aeration system will also include a nitrification step for the conversion of NH4-N to NO3-N. Solids separation designed to remove suspended solids following the aeration stage. It is proposed that solids separation in the Centocor plant will be achieved using Membrane Technology. This will be a state-of-the-art system that has the advantages of providing a superior quality of effluent S:\Projects\190900\ Centocor\EIS\ RP-0001 A.doc 135

13 than traditional plants, as well as significantly minimising the foot print required for the overall WWTP. Sludge Treatment As previously discussed, the Centocor WWTP will give rise to a sludge following separation of the solids from the clarified effluent. An on-site sludge treatment system will be provided to reduce the bulk quantity of sludge required to be removed from site. Sludge treatment facilities will include: Wet sludge storage tank - for pre-treatment storage of sludge from the solids separation system Sludge dewatering system consisting of a centrifuge, plate and frame press or a belt press. The purpose of the dewatering system will be to increase the dry solids content of the sludge to between 12% and 35% w/w depending on the technology employed. The selection of the preferred technology will be determined during the detailed design phase and will be influenced by the routes for off-site sludge reuse and/or disposal that will be available following commissioning of the WWTP (see chapter 12). Covered skip storage for the temporary storage and easy removal of dewatered sludge from the WWTP. Chemical dosing system (polyelectrolyte) to enhance the dewatering process. If it is a requirement to achieve the higher dry solids content for sludge (i.e. up to 35%) then a lime make-up and dosing system may also be required. Odour Management As with any wastewater treatment system potential for odours exists. At the Centocor WWTP, the primary odour source is likely to be the aeration basin. Other sources will include the equalisation tank, the sludge tank and the sludge handling building. It is proposed that the Centocor WWTP will be fully enclosed i.e. all tanks will be covered, and will be vented to a dedicated odour abatement package. The preferred odour treatment option will be to use a biofilter (peat based or similar). WWTP Buildings The WWTP will include a main building which will accommodate the following elements of the WWTP: Sludge dewatering system and associated chemical dosing systems and skip storage Control room and MCC room for WWTP management Laboratory for WWTP monitoring Office A separate enclosure will be provided to house the following elements of preliminary treatment: S:\Projects\190900\ Centocor\EIS\ RP-0001 A.doc 136

14 Neutralisation tanks Heat exchanger Sewage macerator and screen Monitoring Monitoring will be provided on both the treated effluent and surface water emission points in accordance with what will be prescribed in Centocor s IPPC licence. The monitoring points will be located close to the point of connection to the external IDA/CCC foul and surface water sewers. At a minimum, the treated effluent monitoring station will include continuous flow, ph and temperature monitoring and recording. A continuous flow proportionate sampler will also be installed to facilitate the collection of composite samples to be analysed for all other licensed parameters Storm Water / Firewater Run-Off A risk assessment has been carried out for the Centocor site to establish the technical requirement or otherwise for on-site emergency firewater retention i.e., for the prevention of potentially contaminated firewater run-off (or storm water run-off) from reaching the environment. The risk assessment methodology is based on the inventory of potentially polluting materials within the site and the risk of that material being released to the environment in an emergency event such as a fire. Because the manufacturing process at Centocor is an aqueous based activity, the inventory of chemical material potentially stored on site is small and does not exceed any of the guideline thresholds for firewater retention. Consequently, the risk assessment concludes that on-site emergency retention is not technically required. Despite this conclusion, Centocor propose to provide on-site emergency retention as part of the development. This decision is based on the Corporate Credo (see Appendix A) to protect the environment, even in the context of what might be determined to be of low risk. The retention will be in the form of an impermeable lined pond located in the south east corner, and lowest part of the site. The pond will be designed in accordance with the EPA Guidance Note to Industry on the Requirement for Firewater Retention Facilities Impacts on the Receiving Environment Impacts on the receiving environment are discussed in relation to potential impacts on the receiving waters of Cork Harbour, and possible impacts on the external infrastructure required to convey the Centocor effluent to the point of discharge Impacts on the Receiving Sewer and Outfall The rated hydraulic capacity of the Ringaskiddy marine outfall is in the order of 136,000 m 3 /day. The hydraulic load currently being discharged to the outfall is about 26,000 m 3 /day (comprising 20,000m 3 /day industrial and 6,000m 3 /day domestic effluent from Carrigaline and Shanbally). Thus, less than 20% of the hydraulic capacity of the pipeline is currently being used. As such, the additional S:\Projects\190900\ Centocor\EIS\ RP-0001 A.doc 137

15 hydraulic load from the Centocor development ( m 3 /day) will have no significant impact on the outfall capacity. Consideration has also been given to Cork County Council s proposal to treated domestic wastewater from the various agglomerations of the Lower Harbour in a central treatment plant and discharge through the Ringaskiddy marine outfall. However, this proposal will only add an additional 5,500 m 3 /day to the hydraulic load on the outfall. Thus, there is more than adequate capacity in the pipeline to accommodate both the Centocor development and the Lower Harbour WWTP. The ph, temperature and residual chemical constituents of the treated effluent from Centocor are such that they will not cause any problems in the operation, structural integrity or ease of maintenance of the off-site Cork County Council sewerage system and marine outfall Impacts on Cork Harbour Receiving Waters The anticipated impact of the emission from the Centocor WWTP can be discussed in terms of the main environmental water quality indicators in Cork Harbour. BOD / Dissolved Oxygen The assimilative capacity of the Ringaskiddy Marine outfall has been determined to be in the order of 300,000 kg/day, conservatively reduced to 90,000 kg/day for Cork County Council permitting considerations. On the basis of 800m 3 /day, the maximum BOD load associated with the Centocor discharge will be <45 kg/day. This represents 0.05% of the reduced assimilative capacity and about 0.25% of the estimated total BOD load currently being discharged to the outfall. On this basis, no measurable change in the BOD or dissolved oxygen concentrations in the receiving water will arise due to the proposed Centocor development. Nutrients The nitrogen load to the Centocor WWTP is principally in the form of TKN, which includes NH 4 -N but is mostly Organic Nitrogen. This Organic Nitrogen is highly biodegradable. The biological process in the Centocor WWTP will be designed to provide nitrification and denitrification in order to reduce the Total Nitrogen load in the effluent. Ultimately, the Total Nitrogen load due to the Centocor discharge will represent <2.5% of the Total-N load from all industrial discharges to the outfall. This impact can be seen as insignificant in so far as the total existing industrial and domestic nitrogen burden does not significantly impact on the nutrient and eutrophic status of the outer harbour. A comparatively high inlet phosphorus concentration will be significantly reduced by means of chemical precipitation within the treatment process. A target outlet concentration of 40 mg/l will represent a P load equivalent to <3.5% of the total phosphorus load from all current industrial discharges to the outfall. Phosphorus is not the limiting nutrient in the estuarine environment, none the less, the Total P load associated with the Centocor emission can be seen as extremely small and will result in no measurable change in nutrient water quality in the vicinity of the outfall. S:\Projects\190900\ Centocor\EIS\ RP-0001 A.doc 138

16 10.6 Mitigation Measures The following is a summary of the measures that will be implemented as part of the construction and operation of the Centocor project, to mitigate potential impacts on the environment due to aqueous discharges from the site. Construction Phase Provision and maintenance of a temporary package-type secondary wastewater treatment system to treat all sewage arising during the construction period. Provision and maintenance of a dedicated sedimentation pond for the management of sediment release due to excess surface water run-off arising during the construction period. Operating Facility Design, construction and operation of a state-of-the-art on-site wastewater treatment system to meet and exceed all relevant regulatory emission limit values. Provision of an emergency firewater / storm water retention pond to retain all aqueous releases within the site in the event of an emergency situation such as a fire. Implementation of an Environmental Management System which will focus on: The safe and efficient operation and maintenance of the on-site WWTP facilities to ensure compliance with all regulatory requirements. Developing a programme of continuous improvement including the continuous reduction of the waste stream loads arising from the production S:\Projects\190900\ Centocor\EIS\ RP-0001 A.doc 139