Quantification of Asbestos in Soils

Transcription

1 Quantification of Asbestos in Soils Analysis of New Zealand soils using UK methodology WasteMINZ 2015

2 Rhodri Williams Section Manager: Asbestos for Hill Laboratories, Christchurch BSc (Hons) in Chemistry, University of Wales College, Cardiff Asbestos Analyst since 2002, working mainly with soils Section Manager: Asbestos for Hill Laboratories, Christchurch Worked at Alcontrol Laboratories, UK as the Team Leader Asbestos from 2005 to early Developed and validated an accredited Quantification of Asbestos in soil method. Participated in a committee initiated by the Environmental Industries Commission: Standing Committee of Analysts, looking into standardising the methodology for the UK.

3 Recap Asbestos Workshops June 2015 Discussed how quantification of asbestos in soil was performed in the UK Decided to investigate some NZ soils

4 Purpose Labs accredited to AS 4964:2004 LOR is 0.01% for free, respirable fibres Consultants working to WA guidelines require <0.001% Is trace analysis adequate? Will the UK method have any benefit?

5 27 soils deliberately selected for analysis. 22 positive samples were mainly <0.001% (gravimetric) and were exclusively Asbestos Fines Several were close to the limit Two were over the limit Five blank (No Asbestos Detected) samples were analysed Study into NZ soils Sample Dry wt. Total wt. of asb (grav) % asb in soil (grav) A % B % C % D % E % F % G % H % I % J % K % L % M % N % O % P % Q % R % S % T % U % V %

6 Procedure 1g of material taken from homogenised <2mm sieved fraction Suspension created using 200ml water. Filters prepared, dried & cleared Filters evaluated using counting rules described in CRR 83/1996 Data used to calculate weight of fibres All weight data used to calculate final asbestos content

7 Key Assumptions Even distribution of fine fibres in the soil Even distribution of fibres in the suspension All asbestos fibres have a cylindrical cross section

8 All Results Sample % asb in soil (grav) % asb in soil (FC) Total A % % % B % % % C % % % D % % % E % % % F % % % G % % % H % % % I % % % J % % % K % % % L % % % M % % % N % % % O % % % P % % % Q % % % R % % % S % % % T % % % U % % % V % % %

9 Comparing Results Correlation of AS4964 vs UK Methodology % UK Methodology Result % % % % % % % % AS4964 only Result Total 1 to 1 Threshold

10 Results still <0.001% Sample % asb in soil (grav) % asb in soil (FC) Total D % % % F % % % I % % % E % % % J % % % B % % % K % % % L % % % M % % % P % % % Eleven of the samples were still <0.001% One came very close and would have been rounded up to 0.001% Q % % %

11 Results- now >0.001% Sample % asb in soil (grav) % asb in soil (FC) Total O % % % N % % % R % % % C % % % T % % % A % % % H % % % S % % % G % % % Nine samples that were <0.001% after the gravimetric analysis, were >0.001% after the fibre evaluation. Several with significant increase One was >>0.001%

12 Samples containing ACM debris Sample % asb in soil (grav) % asb in soil (FC) Total Form E % % % ACM & loose fibre P % % % ACM & loose fibre L % % % ACM & loose fibre In one sample, 40% of asbestos from fibre evaluation In other two, no significant increase All still <0.001%

13 Fibre count result > Gravimetric result Sample % asb in soil (grav) % asb in soil (FC) Total B % % % C % % % A % % % H % % % G % % % Five samples had free fibre results that were greater than the gravimetric result Only one remained below 0.001%

14 There s always an outlier! There was one quite large fibre on the slide Sample % asb in soil (grav) % asb in soil (FC) Total G % % % 75µm long, 3µm wide The fine fibre analysis accounts for 95% of the asbestos present.

15 How fibre diameter affects the results Amphibole fibres Result >0.001% 0.5µm x 330µm 1µm x 80µm 1.5µm x 35µm 2µm x 20µm 3µm x 10µm Chrysotile fibres Result >0.001% 0.5µm x 425µm 1µm x 110µm 1.5µm x 50µm 2µm x 30µm 3µm x 15µm

16 No Asbestos Detected Five samples were analysed that had originally been reported as Asbestos Not Detected Is the trace analysis giving a result that matched the quoted reporting limit in the Australian Standard (<0.01%)

17 No Asbestos Detected? Sample % asb in soil (grav) % asb in soil (FC) Total Bl % % % Bl % % % Bl % % % Bl % % % Bl % % % In four samples, the result remained <0.001% Three samples had fibres detected One sample >0.001% All below 0.01% (AS4964 LOR)

18 Asbestos Not Detected? Sample Bl 5 Fibres detected Field Ends Length (µm) Width (µm) Type a a a a a a a

19 Conclusion In some cases AS4964:2004 will give an adequate result However, over 45% of samples evaluated showed increase to over the WA limit, no confidence in result of <0.001% for AF AS4964:2004, even with additional soil volume is not able to accurately report to <0.001% for AF Trace analysis procedure from AS 4964; good enough to report as <0.01% but may not always be good enough to report as <0.001%

20 Any Questions? Thank you.