«Application Details Name and address of activity Irotec Laboratories Ltd., Wallingstown, Little Island Co. Cork. Class of activity: 5.6 Manufacture ...»
The company have carried out several improvements to the WWTP in recent months to improve effluent quality and consistently meet licence limits. A sludge belt press was installed in May and this has reduced MLSS from 8,000mg/l to 4,000-5,000mg/l. This has enhanced plant performance. A new surfacewater drainage system has been constructed in conjunction with a firewater retention pond. In the next few months all non process water will be diverted away from the WWTP. This will reduce greatly the volume of effluent in the WWTP. Irotec had problems in the past with periodic flooding of the WWTP during periods of heavy rainfall. Each waste stream from each process since the summer has been characterised for pH, COD, cyanide, ammonia and volume. Waste streams high in ammonia are held in a holding tank and fed slowly to the WWTP. Streams with very high ammonia concentrations are not discharged to the WWTP, but are disposed of off-site. A pH neutralisation system will be installed on the balance tank within a few weeks. Irotec propose to monitor the performance of the WWTP following the completion of the above works and also monitor the impact of additional effluent from PB2. Irotec propose to submit a report at the end of 1999 outlining any further measures that may be required to ensure continued compliance with licence limits. This has been included as condition 6.14 of the PD.
The volume, BOD, COD and suspended solids limits requested by the company have been included in the PD. A limit for phosphorus of 10mg/l has been included in the PD. A time extension from 1999 to 2000 has been given in the PD to reduce Ammonia limits from 200 mg/l to 50 mg/l. The limit values for Ammonia, sulphate, pH, and flow supplied by the Sanitary Authority have been included.
Impact of Effluent Emissions The design organic load for the IDA outfall to Lough Mahon was 9000 kg/day.
The spare assimilative capacity is 7000 kg/day. The current total BOD emission from the IDA outfall is in the order of 1000-2000 kg/day Irotec are licensed to discharge 200 kg/day. Modelling conducted on the impact of effluent emissions predict an increase in BOD levels of 0.05 mg/l at Blackrock and 0.03 mg/l at Lough Mahon. Background BOD levels for Blackrock vary between 3-5 mg/l while levels at Marino point are in the region of 3 mg/l.
The results of modelling predict that the maximum increase in background COD levels as a result of the licensed discharge of 1000kg/day will be 0.26 mg/l at Blackrock and 0.13 mg/l at Lough Mahon.
In relation to suspended solids, the vast bulk of suspended solids in the final effluent is likely to consist of bacterial biomass. Periodic analysis indicates that 50-75% of the suspended solids consist of organic matter. The discharge of suspended solids will be readily biodegradable.
Irotec are licensed in the PD to discharge 40kg/day ammonia until 2000 and from July 01 2000 Irotec are licensed to discharge 13 kg/day and a concentration limit of 50 mg/l. Ammonia inputs from industrial and domestic sources to Cork harbour have been estimated at 1619 kg/day. The effect of a discharge of 40kg/day of ammonia in the harbour were modelled. The results indicated that the maximum level encountered after 20 days would be
0.013mg/l at Blackrock and 0.007 mg/l at Lough Mahon. Ammonia-N levels tend to fall rapidly towards the mouth of the harbour where concentrations of 0.02-0.04 mg/l were reported by Cork Main Drainage Report in September
1991.2 The deterioration in water quality in the harbour area is clearly attributable to discharges from Cork city’s sewage system.1 The proposed new sewage treatment works for Cork city should improve the overall water quality of the harbour area. (please refer to the Board Memo on the original licence for a more detailed discussion on Ammonia).
The effects of a discharge of 14 kg/day phosphorus were modelled and it was predicted that the levels of total phosphorus would be increased to 0.002 at Lough Mahon. Irotec are licensed to discharge 10mg/l and 3kg/day phosphorus. The most recent results submitted by the company since improvements have been made to the WWTP show that phosphorus levels are below 10mg/l.
Surfacewater Due to incidents of contamination of surfacewater by contaminated cooling water Irotec propose in 1999 to replace the existing once-through cooling water system for PB1 with an indirect system. This system will virtually eliminate the potential for contamination of surfacewater from monoethylene glycol coolant. The new system will also minimise water consumption. The cooling system proposed for PB 2 is a recirculating cooling tower system.
A proposal to construct a firewater retention pond has been agreed with the Agency. Condition 9.2.1 requires the automatic diversion of contaminated firewater to the firewater retention pond. A continuous TOC monitor has been installed on surfacewater discharge. Irotec are nearing completion on a project to collect and isolate run-off from areas which could be potentially contaminated. This is termed the process area surface water drainage system (PASD). This will be collected in a separate tank which will be tested and then either discharged to surfacewater or to the WWTP for treatment. Previously this water drained to the WWTP and caused problems with flooding the WWTP in the past.
The handling of hazardous and non hazardous wastes is carried out in accordance with the existing IPC licence. The proposed expansion to the site will not alter these practices, but the quantities of waste generated will increase in line with increased production. Its anticipated that waste produced per tonne of product will be less for the new production building than the existing building because of improved production efficiency and solvent recovery systems in the new production building.
The most recent report submitted to the Agency on groundwater quality underneath the Irotec site makes the following conclusions; Analytical results indicate that the groundwater quality beneath the Irotec site has deteriorated since April 1998. There appears to be a continued upgradient source of contamination based on elevated temperature, electrical conductivity and groundwater mound upgradient of the site. A detailed site inspection in August 1998 indicated that no evidence of on-site sources of groundwater contamination have been identified. Until the upgradient source(s) of contamination have been isolated and removed, an assessment of potential onsite impacts on groundwater quality cannot be made. The Local Authority and IDA Ireland have been made aware of the groundwater contamination problem on Little Island and have conducted their own investigations. The company propose to continue the groundwater monitoring programme. Condition 9.3.4 requires that where on-site contamination is identified it is isolated and any remediation deemed necessary carried out.
There has been no change in limits from the existing licence. A new noise source has been included. The company exceeded noise limits for two noise sources and a work programme was put in place to bring emissions into compliance. No complaints have been received in relation to noise from this activity.
There were no submissions received on this application.
There were no complaints received in relation to this activity.
Summary of enforcement.
Irotec have been in non-compliance for emissions to sewer for various parameters such as flow, suspended solids, BOD, ammonia and cyanide. There was one toxicity exceedance of 18.1 versus a limit of 10. The company propose, in the near future, to conduct further toxicity testing and simultaneously carry out a complete characterisation of the effluent stream to identify any potential sources of toxicity in the effluent. The requirement for toxicity testing is included in the PD. The flow exceedance was due to very heavy rainfall. A new drainage system has been constructed for the site as detailed above and this should eliminate flow exceedance problems. There were interference problems with the method of analysis for cyanide. The USEPA distillation method has been validated and is now used for measurement of cyanide on site. A third neutralisation tank has recently become operational for the treatment of cyanide waste prior to discharge to the WWTP. Details of work carried out on the effluent treatment system, to improve the quality of effluent discharged, are included in the section on emissions to sewer above. The company had an ongoing work programme in place while they were in non-compliance, to bring them into compliance again.
Its expected that the proposed works carried out on the WWTP and any further measures identified as part of the study on the performance of the existing WWTP should eliminate non compliances in emissions to sewer. There were thirteen bursting disc ruptures. The company are in the process of installing bursting disc detectors with alarms on all reactors. This will give immediate notification of bursting discs. All operators have received training on the correct procedure for addition of pressure to reactors to avoid bursting disc failures. The new production building will contain a dump tank to contain emissions from bursting discs. The licensee is required to address in the EMP the minimisation of potential emissions to air. There were five exceedances for emissions to air. These are due to the inability of the current scrubber system to treat water immiscible solvents. The installation of the proposed thermal oxidiser should ensure compliance with licence limits.
There was one incidence of contamination of ground. During replacement of the clay effluent pipe with a polypropylene pipe a leak occurred in a 4m section of the pipe. It was presumed that the pipe was empty at the time but there was a fall away from the outlet to the WWTP which resulted in some effluent being retained in the pipe. Its estimated that 3-4 m3 of soil was contaminated. This was removed for treatment off site. Groundwater quality while impacted by upgradient off-site contamination dose not appear to be contaminated as a result of the leakage from the pipe. However there is a monitoring well down gradient of the spill area and this will continue to be monitored to determine if there is any impact.
There were three spills of the coolant monoethylene glycol to surfacewater.
Irotec propose in 1999 to replace the existing once-through cooling water system for PB1 with an indirect system cooled by horizontal fan units. This system will virtually eliminate the potential for contamination of surfacewater from ethylene glycol coolant. As part of the fire water retention project surfacewater will be continuously monitored and contaminated surfacewater will be automatically diverted to the fire water retention pond.
That the proposed determination as submitted be approved by the Board.
Signed Annette Prendergast References;
1 ERU Cork Harbour water Quality, A Summary and Assessment of the Present Position, 1989.
2. Forbairt, Synthesis of Existing Information on the Environment of Cork