OPTIONS TO SAFELY MANAGE AND DISPOSE OF ASBESTOS CONTAMINATED SOIL IN CANTERBURY. Rowan Freeman Environment Canterbury Nigel Mather 4Sight Consulting

Transcription

1 OPTIONS TO SAFELY MANAGE AND DISPOSE OF ASBESTOS CONTAMINATED SOIL IN CANTERBURY Rowan Freeman Environment Canterbury Nigel Mather 4Sight Consulting

2 Presentation Outline Canterbury s asbestos challenge The investigation scope Asbestos in Soils The New Zealand context International guidance and practices Asbestos Disposal The outcome Implementation

3 Canterbury s asbestos challenge Post-earthquake Canterbury Uncontrolled/poor demolition practices (ignorant or careless?) No national guidelines for asbestos contaminated soil Industry adopted WA Guidelines Soil with perceived ambient concentrations of asbestos going to cleanfill? Limited disposal options for asbestos contaminated soil Christchurch City Council Cleanfill and Waste Handling Operations Bylaw (2015) Substantial volumes of soil with low level asbestos heading to landfill (high cost/not environmentally sustainable) 3

4 Mounting pressure on council to develop policy Environment Canterbury asked: How relevant are the WA Guidelines to management of asbestos in soil in Canterbury? Does <0.001% w/w asbestos in soil (as per WA Guidelines) mean ambient? Does existing literature (world-wide) point to an ambient concentration of asbestos in soil that can be applied in Canterbury? 4Sight Consulting engaged to undertake literature review. 4

5 The investigation scope Asbestos in soil, and disposal of asbestos contaminated soils Independent scientific literature review Critical assessment of the WA Guidelines Review alternative current international guidelines Intended Outcomes: Sound basis for Environment Canterbury policy decisions

6 Asbestos in Soils - The New Zealand Context Confused and Serious Gaps Limited collaboration regional/territorial/central International guidance may be both conservative (bonded ACM), not adequately protective (friable) Emotive issue understandable, but research does not support increased exposure risk Limitations of risk assessment methodologies Low dose long term exposure uncertainties Exposure-response relationships unknown at low dose long term Complexities of the soil-air relationship

7 Source: Swartjes and Tromp. 2008

8 International Guidance and Practices - WA WA Guidelines Good stuff Interagency interaction between DEC and DOH advice sought Use of practical positions Qualitative approach for small low risk sites (residential) Thorough guidelines on investigation and management approach Conservative approach due to uncertainties Uncertainties Climate and soil type differences Asbestos forms and potency Updates based on new Dutch research

9 International Guidance and Practices - Netherlands Dutch Guidelines Good stuff Threshold levels, based on derived relationship between soil and air Three tier RA approach Broad climatic similarities (specifically rainfall) Alignment with NZ risk thresholds for asbestos in air Uncertainties Updated negligible and maximum permissible risk factors significantly lower Relevant potency overstated due to quality of epidemiological studies Underestimation of risk presented by friable asbestos?

10 International Guidance and Practices - UK UK Approach Good stuff Solely RA approach detailed tools available (SoBRA. CL:AIRE) Multiple lines of evidence approach Exposure-risk models used Uncertainties No guideline values limited understanding of soil-air relationship, no national guidance Unofficial soil levels of 0.001% adopted Exposure-risk models have variable results quality of data imperative RA approach is labour intensive RA approach requires regulators to be knowledgeable and empowered

11 International Guidance and Practices - US US Approach Good stuff Activity based RA approach Science based quantitative assessment, using CSM Uncertainties Labour intensive Interpretation of results requires care

12 International Guidance and Practices Guideline Summary Air (fibre/ml) Soil (% w/w) Jurisdiction 10-6 Excess lifetime Cancer Risk 10-5 Excess lifetime Cancer Risk 10-4 Excess lifetime Cancer Risk Western Australia/NEPM Netherlands United Kingdom United States Assuming a relative potency of 1:10:10 for chrysotile, amosite, crocilodite 2. Air concentrations based on WHO, Unofficial soil concentration, after Otness et al (2003)

13 Other Considerations Laboratory methods Semi-quantitative only Approved method AS practical LOD 0.1% % Alternative methods being investigated in UK (PLM) Mining Datasets Soil and air quality data sets

14 Asbestos Disposal Regulatory framework CCC Cleanfill and Waste Handling Operations Bylaw no asbestos to cleanfill MfE Guide to Managing Cleanfills no asbestos to cleanfill Results = Kate Valley at significant cost, reduced landfill capacity Options Disposal to cleanfills policy change, careful consideration of potential risks Re-classifying cleanfills as managed fills On-site reuse

15 Summary Few direct soil guidelines internationally and site specific approach still recommended RA at source identified as most effective method to control HH risk Scientific debate Soil air relationship complex Exposure-risk models and epidemiological data Disposal often regulated locally, but disposal to cleanfill generally not appropriate

16 Outcomes Threshold based soil guideline Should be conservative due to lack of local empirical data and soil air relationship Dutch Guidelines align with NZ risk threshold and climatic similarities WA Guidelines provide additional level of conservatism» recommended with tiered approach (BRANZ) Ambient Concentration Consensus to provide baseline Useful if applied with caution Disposal Zero tolerance vs threshold guideline Threshold guideline presents risk

17 Managing soil with asbestos on-site Is soil with any asbestos remaining onsite? NO YES Soil removed from site (Follow disposal of soil with asbestos process) Has a DSI been undertaken? NO TA may require DSI YES Option 1: Soil cannot remain onsite SQEP-informed decision about fate of soil is made with approval from council Soil asbestos concentrations <0.001% w/w as per WA guideline and are other soil contaminants, if present, below applicable guidelines? NO NO NO YES Soil can be re-used on site: - with council approval - no additional DSIs Option 2: YES SQEP undertakes site-specific Tier 2 Risk Assessment and Council accept applicable guidelines have not been exceeded? Soil to be re-used on site. Controls to manage: - burial/encapsulation - site management - informed by SQEP & accepted by council - information recorded by regional council and territorial authority (HAIL Register/LIMs, etc.)

18 Disposal of soil with asbestos Reasonable cause to suspect asbestos contaminated soil is present? YES NO Detailed Site Investigation (informed by PSI) reports asbestos at <0.001% w/w as per WA guidelines? NO YES Are other contaminants present in soil above published regional background levels for disposal site? YES NO Dispose to suitably licensed facility (Class 1-3) NO Have criteria specific to the receiving controlled fill been met? Disposal as Cleanfill YES Controlled Fill

19 What now? Publish Environment Canterbury s position on disposal of asbestos contaminated soil Work with territorial authorities The New Zealand Guidelines for Assessing and Managing Asbestos - BRANZ Additional layer of guidance for Canterbury around disposal of asbestos contaminated soil Partly reliant on uptake from Industry Partly reliant on creation of managed/controlled fills Partly reliant on buy-in from territorial authorities

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