Shannon Odours Investigation- Status Update 2 13.12.13

Date released: Dec 13 2013

Shannon Odours Investigation: Status Update Number 2

Date released: 13 12 2013

Joint Statement by the Environmental Protection Agency (EPA) and Clare County Council on the Current Status of the Shannon Odours Investigation.

Previous Status Updates in relation to the odour problem in Shannon, 16 October 2013
This is the second Status Update on the Shannon Odours Investigation, following the statement of 16 October 2013.

Since late September of this year, both the EPA and Clare County Council have received complaints about odours, described as “sewage”, “rotten eggs” or “sulphuric” in nature, from the residents of Shannon Town and surrounding areas. The majority of these were received in the period up to the middle of October. A period of four weeks followed without any odour complaints, though a number have been received in the past two weeks.
Following the earliest reports, EPA and Clare County Council personnel began to investigate the source of the odours, and verified the occurrence of sulphurous odours on a number of occasions and at several locations around the town. They also verified sulphurous odours in the Bunratty and Cloverhill areas to the east of Shannon Town.
Shannon has a population of 9,673 (CSO, 2011) and is the location of a substantial amount of industrial activity based in two major industrial estates. All facilities are regulated by either Clare County Council or the EPA. There is a total of 9 EPA licensed industrial operations and two EPA licensed waste management installations in Shannon. The municipal waste water treatment plant at Tradaree Point, which serves both the municipal and industrial needs of Shannon Town and its environs, is also licensed by the EPA. The details of all licenses issued by the EPA are available on the EPA website.

The EPA and Clare County Council, assisted by the HSE's Environmental Health Service and the Midwest Department of Public Health, sought to identify the source of the odours and to identify why they are being released, so that steps to address the issue quickly and prevent any further releases could be taken.

Work undertaken has included:

  • A database of all odour complaints was compiled;
  • Surveillance of health effects requiring medical attention and monitoring of reported effects in a selection of local schools was undertaken by HSE;
  • Odour assessments were carried out by Clare County Council and EPA staff;
  • The EPA deployed a full time odour inspector in Shannon for a period of three weeks in October 2013;
  • Monitoring of hydrogen sulphide and other relevant gases was initiated to address concerns expressed by members of the public about possible health impacts of the odour;
  • Inspections and monitoring were undertaken at EPA-licensed facilities in the Shannon area;
  • An audit of the Tradaree Waste Water Treatment Plant was carried out by the EPA in conjunction with Clare County Council;
  • Investigations of the sewerage network in Shannon Town were undertaken by Clare County Council engineers.

Findings to date
Continuous monitoring for hydrogen sulphide carried out in October and November in 10 locations around Shannon has shown that average levels of hydrogen sulphide were below detectable levels except in the vicinity of Tradaree WWTP. Because of the nature of this monitoring, these values represented the average over a four week period, so it is not impossible that occasional peaks may have occurred during this period at times when odours were experienced in different locations around the general area. It is, however, extremely unlikely that there has been any risk to public health, because results of similar monitoring carried out by EPA personnel in the presence of significant odour has not detected quantifiable levels of hydrogen sulphide outside the immediate vicinity of the Tradaree WWTP; even in these locations, the levels of hydrogen sulphide have been well below World Health Organisation Guideline Limits.

Despite initial concerns expressed by complainants that the odours were from companies operating in one or other of the industrial estates in Shannon, the investigations have conclusively demonstrated that the primary source of these odours is the Tradaree Waste Water Treatment Plant. The sewer collection network has not been identified as a significant ongoing source of  odours. Much of the network is considered to be in generally good condition, though a number of sections are in need of major remedial works.

An audit of the Tradaree WWTP was carried out on 16 October 2013 by the EPA in conjunction with Clare County Council. The audit confirmed that the plant was generating significant hydrogen sulphide odours as a result of operating in a septic or anoxic condition. The audit identified a series of necessary measures to deal with the problem: the audit required the immediate installation of additional aeration capacity in the plant to prevent the generation of hydrogen sulphide. Further upgrading works are specified for implementation in the medium and longer term, including redesign of the treatment process at the plant to achieve greater performance commensurate with the sewage load generated in the Shannon Town agglomeration.
The audit of the Tradaree WWTP also determined that a review should be conducted to identify any industrial discharges into the sewer that contain substances with the potential to cause inhibition of the plant’s operation.

Monitoring and inspection of the licensed facilities in Shannon determined that they were operating at a high level of compliance with their EPA licences, though several non-compliances with emission limit values (ELVs) were detected in relation to emissions from three facilities, including the Tradaree WWTP itself.

Since the audit of the Tradaree Plant, Clare County Council have been engaged in planning and resourcing the immediate and longer-term measures necessary to improve the operation of the plant in order to eliminate the odour problem and to bring it into compliance with its EPA licence. The works are planned in four phases:

  • Phase 1 – Emergency works: Desludging of tanks and clarifiers and installing emergency aeration; Timescale 4-6 weeks;
  • Phase 2  –  Short term works: Inlet screen and Diffused aeration system; Timescale 2-4 months, subject to approval by the Department of the Environment, Community and Local Government and/or by Irish Water;
  • Phase 3 – Interim improvements: A programme of works based on the recommendations in the EPA audit report, subject to approval by Irish Water, who are due to take over legal responsibility for wastewater treatment from 2014;
  • Phase 4 –  Long term upgrade: The major works outlined in the Preliminary Report submitted under the 2010-2013 Water Services Investment Programme by Clare Co Council to the Department of Environment, Community and Local Government will be reviewed by Clare County Council and by Irish Water, with a view to designing further longer-term works following on from the Phase 3 interim improvements  above.

The Phase 1 emergency remediation works will commence over the weekend of 13-15 December 2013 and are expected to be completed over the next four to six weeks. During the period of the emergency works, it is likely that further and possibly more concentrated odours may be generated as a result of the sludge removal process. Depending on the wind direction, this may lead to odour being experienced in Shannon Town and surrounding areas.

Odour surveillance by Clare County Council is continuing and will do so until the issue has been resolved. Likewise, the database of complaints will continue to be maintained to provide ongoing intelligence on the occurrence and nature of odours in the Shannon Area, particularly during the period of the emergency works at Tradaree WWTP. Monitoring of hydrogen sulphide and other relevant gases will also be continued.

On-going assessment is being carried out by the EPA and Clare County Council of the industrial operations in the Shannon area and their environmental performance. Clare County Council may seek reviews by EPA of certain industrial and waste management licences which provide for discharge to the Shannon Town sewerage network.

Clare County Council is continuing to carry out investigation, cleaning and CCTV surveying of the sewerage network.

Communications with complainants and public representatives
Clare County Council and the EPA are continuing to respond to complaints as they are received.
Clare County Council and EPA will continue to liaise with public representatives until the situation is remedied.
Any concerns may be directed to Clare County Council, the EPA or the HSE.

Media Briefings
A report will be published on conclusion of the investigation into the Shannon odour issue. The report will outline the assessments that have been carried out, the findings obtained and the actions that have been taken.
In the interim, further Status Updates will be published as the matter is progressed towards a satisfactory conclusion.
Clare County Council and EPA will continue to provide further information to the media on request.