Report to ENVIRONMENTAL PLANNING & REGULATIONS Committee for decision

Transcription

1 o Title: Section: Prepared by: Western and Coastal Township Closed Landfills Preliminary Site Investigations and RASCL Assessments Shared Science Services James Langford (Land Management Officer) Meeting Date: 14 June 2017 Legal Financial Significance = Medium Report to ENVIRONMENTAL PLANNING & REGULATIONS Committee for decision SUMMARY Purpose The purpose of this report is to advise the Committee of the potential liability and risk to Council associated with a number of small closed landfills located around the western and coastal townships of Tairawhiti. Staff seek a committee decision to further investigate the landfills to determine the most appropriate remediation s that may be required. Problem Preliminary investigations of ten sites across Tairawhiti have been conducted as per the relevant Ministry for the Environment (MfE) guidelines and where available have included: historical aerial photography county/council engineers records consents previous preliminary or detailed site investigations surface water or bore water quality data personal communications with current and ex-county/council employees. This information was used to inform MfE Risk Assessments for Small Closed Landfills (RASCL) for the sites. The results of the RASCL for the sites are included in this report. RASCL assessment results suggest there is some risk to human health and the environment associated with these landfills. Site risk associated with these landfills was found to be medium for sites in Te Araroa, Tikitiki, Te Puia, Tokomaru, Tolaga, Patutahi, Te Karaka, and Whatatutu; risk was found to be low at the Matawai site, and the site at Waipiro Bay has been disestablished by the sea. The decisions or matters in this report are considered to be of Medium significance in accordance with the Council s Significance and Engagement Policy. A Page 1 of 10

2 RECOMMENDATIONS That the Environmental Planning & Regulations Committee: 1. Notes the contents of this report and in particular: a) The initial level of total risk identified by the RASCL assessment criteria and potential liability this risk presents to the GDC associated with the Western and Coastal township landfills that were investigated. 2. Agrees that sites with a medium level of risk are to be prioritised for further investigations. Authorised by: James Langford Land Management Officer Lois Easton Acting Director Environmental Services & Protection Keywords: Contaminated Land, Gisborne District, Possible Council liabilities A Page 2 of 10

3 BACKGROUND 1. Report to the Environment Planning and Regulations Committee titled Investigation into Contaminated Land in Gisborne District Possible Council Liabilities framed the contaminated land issues in Tairawhiti for the Council. The report identified 24 potentially contaminated sites in the Gisborne District for which the Council has some responsibility. 2. From the list of sites provided in Report , and five other landfills (see paragraph 5 below) listed below, 11 work packages were decided on to guide council investigations. The 11 packages are: a. Paokahu landfill; b. Waiapu landfill; c. Waikanae Stream landfills (x5); d. Adventure Playground & Watson Park landfills; e. Derby Street & Grey Street Gasworks; f. Patutahi Quarry; g. Western and Coastal Township landfills (x10); h. Kawatiri Road and Gaddums Hill landfills (x2); i. Sponge Bay and Ormond Township landfills (x2); j. Council & County Depots (x6); k. Gun Clubs (x2). 3. This report provides the findings from preliminary site investigations of the Western and Coastal Township Landfills and the results from the RASCL Assessments. Guidance for the investigation process and the application of RASCL came from the following MfE documents: a. A Guideline for the Management of Closing and Closed Landfills in New Zealand. b. Contaminated Land Management Guidelines No.1 Reporting on Contaminated Sites in New Zealand. c. Risk Screening System Contaminated Land Management Guidelines No.3. d. Risk Assessment for Small Closed Landfills. 4. Council Archives and Land and Soil Resources staff searched the council / county records in effort to retrieve all information available concerning the coastal and township landfills. 5. During the preliminary site investigations Council records were found that referenced five other closed landfill sites that were not listed in Report These sites are: a. Matawai Landfill; b. Kawatiri Road Landfill; c. Gaddums Hill Landfill; d. Sponge Bay Landfill; e. Ormond Landfills. 6. Council GIS record of landfills, contaminated sites, or HAIL sites did not include the location or extent of any Western and Coastal township landfills. A Page 3 of 10

4 7. The closed Western and Coastal Township landfills are located at: a. Te Araroa; b. Tikitiki; c. Te Puia; d. Waipiro Bay; e. Tokomaru Bay; f. Tolaga Bay; g. Patutahi; h. Te Karaka; i. Whatatutu; j. Matawai. Figure 1: Map of district. 8. Land and Soil Resources, Water and Coastal Resources and Environmental Health staff went to each western and coastal township landfill site to confirm locations of landfill. They also made a visual assessment of the site which included mapping the extents of fill, current landuse and adequacy of the landfill cap. 9. Staff have been unable to determine specific types of contaminants disposed at the landfills. It is likely that the dumping of household, agricultural and industrial refuse occurred. Without a detailed investigation we are making initial assumptions based on MfE guidelines that the landfills have: a. Low to moderate gas generation in the larger landfills closed 1960s-1970s, moderate to high gas generation in larger landfills closed 1980s-1990s. Assume high levels of generation in larger landfills closed post-1990s- present; b. Moderate discharges of metals; and c. Trace levels of pesticides, phthalate esters and hydrocarbons. A Page 4 of 10

5 o DISCUSSION 10. The results from the RASCL assessments as presented below suggest that there is some risk to human health and to the environment associated with these landfills. 11. Risk assessments for the landfills are complicated by many of them presently operating as municipal waste transfer stations. The RASCL assessments are related only to risk associated with the closed landfill yet the total risk of these sites should include an assessment of the potential and actual effects of the transfer station activities to human health and the surrounding environment. 12. Findings from the preliminary site investigations were used to inform a RASCL assessment. As Table 1 displays the RASCL assessment overall site risks for the Western and Coastal township landfills. Below is a table of results summarising the findings from the preliminary investigations and RASCL/RSS Assessments for the landfills. Table 1: RASCL Assessment results, landuse, soil types/drainage and area for Coastal and Western Township Landfills. Path Landfill Current Land Use Soil Types and Drainage Area (Ha) Total Site Risk (RASCL) Moana Parade, Te Araroa (before bridge to East Cape) Recreational Reserve / playground Loamy sand. Well drained Medium Contamination of Groundwater Rubbish Dump Road, Tikitiki Waiapu Rd SH35, Te Puia Springs Agriculture / Horticulture / Road Reserve / River Reserve Municipal Waste Transfer Station Loamy sand. Well drained. Loamy sand. Well drained Medium Direct Surface Exposure 0.80 Medium Gas Accumulation McIlroy Rd, Waipiro Bay No longer exists, washed away by coastal processes N/A N/A N/A N/A Paikea Street, Tokomaru Bay Solander Street, Tolaga Bay Kirkpatrick Road, Patutahi (before bridge over Whakaahu Stream) Kanakanaia Road, Te Karaka Municipal Waste Transfer Station / Agriculture / Horticulture / River Reserve Agriculture / Horticulture / Road Reserve / Recreational Reserve Agriculture / Horticulture / Road Reserve Municipal Waste Transfer Station Clay loam. Poorly drained. Majority clay loam, small areas of sandy loam. Poorly drained. Silt loam + recent alluvial deposits, moderately well drained. Silt loam + recent alluvial deposits, moderately well drained Medium Direct Surface Exposure 1.09 Medium Direct Surface Exposure 0.78 Medium Contamination of Groundwater & Direct Surface Exposure 0.44 Medium Gas Accumulation A Page 5 of 10

6 Tip Road, Whatatutu 209 Motu Road, Matawai Municipal Waste Transfer Station Municipal Waste Transfer Station Silt loam + recent alluvial deposits, imperfectly drained. Silt loam + recent alluvial deposits, well drained Medium Gas Accumulation 1.55 Low Contamination of Groundwater, Contamination of Surfacewater, Gas Accumulation & Direct Surface Exposure High Priority Investigations Medium Level Risk 13. A medium level of risk via direct contact pathway is associated with the Tikitiki, Tokomaru, Tolaga, and Patutahi Landfills. Low levels of direct contact risk have been identified at all the other sites. Possible risks associated with direct contact are: a. Ingestion of contaminated material; b. Physical harm from sharp protruding objects. Figure 2: Left Tikitiki Landfill. Right Tokomaru Landfill 14. Medium level direct contact risk is not acceptable as the land use is now agricultural and grazing animals were observed at, or in the vicinity of all sites while undertaking the preliminary site investigations; further investigation is required at these sites to inform remediation options. A Page 6 of 10

7 Figure 3: Patutahi Landfill. The depression in the centre of the image is associated with landfill activity 15. A medium level of risk due to landfill gas accumulation is associated with the Te Puia, Whatatutu, and Kanakanaia landfills. Possible risks associated with gas accumulation are: a. Odour; b. Explosion if gas is able to build up in confined spaces 16. We recommend to further investigate the level of risk associated with gas accumulation at all landfills with medium level of risk. Low risk sites are thought to be low priority for further investigations. 17. The RASCL assessment criteria identified medium groundwater contamination risk at the Te Araroa, and Patutahi landfills. Possible risks associated with groundwater contamination are: a. Contaminants entering groundwater; b. Contaminants entering surfacewater bodies, possible effects on natural heritage values; c. Stock watering from contaminated water; d. Contamination of land outside the landfill from contaminated surfacewater; e. Further degradation of cultural heritage values. Low Priority Investigations Low Level Risk 18. Low gas accumulation risk sites are thought to be low priority for further investigations. 19. Low risk of contamination to groundwater was identified at Tikitiki, Te Puia, Tokomaru, Tolaga, Kanakanaia, Whatatutu, and Matawai landfills and is thought to be low priority for further investigations. 20. The RASCL assessment criteria identified low surface water contamination risk at all sites. Possible risks associated with surface water contamination are: A Page 7 of 10

8 a. Contaminants entering nearby waterbodies, possible effects on natural heritage values; b. Stock watering from contaminated water; c. Contamination of land outside the landfill from contaminated surfacewaters; d. Further degradation of cultural heritage values. Update Council GIS Record 21. Council GIS record of landfills needs to be updated to include the location and extents of the Western and Coastal township landfills. OPTIONS 22. Do nothing. Council accept level of risk and any liabilities associated with the landfills in their current condition. 23. Do something. Council seek to lower all medium levels of risk as indicated in the RASCL assessments presented above to low. This to be achieved by conducting more detailed site investigations to further define the risk associated with the landfills and inform appropriate remediation options. Further Investigations High Priority 24. Further investigation of all landfills required to develop remediation plans to reduce the direct contact risk is recommended. These investigations will be completed by council staff and must include: a. Detailed mapping of the site to identify where fill material is extending outside the footprint of transfer stations; b. Landfill cap assessment (i.e. capping material and depth of cover). 25. Further investigation of Te Puia, Kanakanaia, and Whatatutu landfills is required to assess the risk to human health and the surrounding environment from gas accumulation. Investigations will include a rapid landfill gas assessment this may require engagement of a contaminated land consultant with specialist equipment. 26. Further investigation of the Te Araroa, and Patutahi landfills to assess the risk to groundwater from contaminants is recommended. Investigations can be completed by council staff and will include: a. Assessment and modelling of the hydrogeology and receiving environments at each of the landfills. b. Groundwater sampling to determine if there is concentration of contaminants found. 27. Further investigation of the Tikitiki and Patutahi landfills to assess the risk to surfacewater from contaminants is recommended. Investigations can be completed by council staff and will include: a. Assessment and modelling of the surfacewater hydrology and receiving environments at each of the landfills. b. Surfacewater and sediment sampling to determine if there is concentration of contaminants found. A Page 8 of 10

9 ASSESSMENT OF SIGNIFICANCE Criteria This Report The Process Overall The effects on all or a large part of the Gisborne district Low Low The effects on individuals or specific communities Medium Low The level or history of public interest in the matter or issue Medium Low Inconsistency with Council s current strategy and policy Low Low Impacts on Council s delivery of its Financial Strategy and Long Term Plan. Low Medium 28. The decisions or matters in this report are considered to be of medium significance in accordance with Council s Significance and Engagement Policy. 29. This report is part of a process to arrive at a decision that will/may be of medium level in accordance with the Council s Significance and Engagement Policy. COMMUNITY ENGAGEMENT 30. To date there has been no community engagement on this issue. 31. As the RASCL assessments for the landfills resulted in high overall risk any communication community should emphasise council s efforts to investigate these landfills and intention to remediate where required. CONSIDERATIONS Financial/Budget 32. Internal staff time on the project is provided for within current budgets. 33. Landfill cap remediations. 34. Assistance from the Contaminated Sites Remediation Fund (MFE) and Envirolink will be sought to assist the costs to investigate gas accumulation risk and surface and groundwater risks. 35. If discharges from the landfills are occurring then resource consents may be required. These will place remediation requirements on the Council which will need to be considered as part of the Long Term Plan. Legal 36. If discharges from the landfills are occurring then resource consents are required under the Resource Management Act. These will need to outline how the effects of the discharges will be avoided, remedied or mitigated. POLICY AND PLANNING IMPLICATIONS 37. This investigation into Council s contaminated sites is consistent with the Freshwater Plan and Regional Policy Statement which seek to manage the impacts of land use activities on the environment. RISKS 38. RASCL assessment criteria has identified high risk to human health associated with these landfills. 39. The high level of risk identified via direct contact is acceptable to sites that continue to be utilised as municipal waste transfer stations and should be managed through the site s standard operating procedures. A Page 9 of 10

10 40. The high level of assessed risk identified via direct contact, gas accumulation, contamination of surfacewater or contamination of groundwater is unacceptable where the land use is now agricultural or recreational. Detailed investigations need to be undertaken to confirm if these sites need to be remediated to reduce this level of risk and possible human and livestock health and safety liabilities. NEXT STEPS Date Action/Milestone Comments August 2017 September 2017 By September 2017 Landfill cap assessments at Tikitiki, Tokomaru, Tolaga, and Patutahi completed. Remediation options investigated and reported to Environment Planning & Regulations Committee. Investigate internal and external resourcing requirements for gas, and groundwater investigations required for GDC budgeting purposes for the Long Term Plan. To be completed by GDC Land and Soil / Water and Coastal Resources staff. To be completed by GDC Land and Soil / Water and Coastal Resources staff. A Page 10 of 10