Asbestos Analysis of Soil and Rock Ed Cahill EMSL Analytical Inc.

Transcription

1 Asbestos Analysis of Soil and Rock Ed Cahill EMSL Analytical Inc

2 Why Look for Asbestos in Soil/Rock? Asbestos Contamination Sloppy or improper Asbestos Removal jobs can leave asbestos contamination in surrounding soil 2

3 Why Look for Asbestos in Soil/Rock? Asbestos Contamination Demolition of Buildings Without the Proper Removal of ACM prior can leave a trail of asbestos contamination all the way to the landfill 3

4 Why Look for Asbestos in Soil/Rock? Asbestos Contamination Contamination from Past Use (or current use!) Sites such as manufacturers of asbestos containing products, auto repair sites, etc. 4

5 Why Look for Asbestos in Soil/Rock? Asbestos Contamination from Events or Disasters such as 9/11 and Katrina 5

6 Why Look for Asbestos in Soil/Rock? Naturally Occurring Asbestos First gained large scale publicity with the Libby Montana Vermiculite Issue 6

7 Naturally Occurring Asbestos Naturally Occurring / Unnaturally Exported Vermiculite was processed in blast furnaces and sent throughout the country and abroad for a multitude of uses. The raw ore was also exported for processing off site 7

8 Naturally Occurring Asbestos El Dorado County, CA Oak Ridge High School soccer field construction disturbs amphibole asbestos. 8

9 Naturally Occurring Asbestos Naturally Occurring Asbestos Serpentine (including Chrysotile asbestos) is the state rock of California. The aggregate used for roadbeds, rail beds, and on construction sites of all types is always a question mark. 9

10 Naturally Occurring Asbestos NOA not just a California problem 10

11 Naturally Occurring Asbestos Naturally Occurring Asbestos (NOA) affects more than 30 square miles of Staten Island 11

12 Why is Soil and Rock Different from Other Samples? The problems with soil: - obtaining a representative sample in the field - obtaining a representative sub-sample in the lab - varying particle sizes prohibit making proper slide mounts ALL of these come down to a problem of lack of Homogeneity 12

13 Scales of Non Homogeneity The Big Picture Obtaining representative samples in the field can be difficult. Samples tend to be very non-homogeneous especially over the large areas that are typical in NOA related cases. How many samples for a baseball field or 100 miles of road or rail bed? 13

14 Scales on Non Homogeneity The Medium Picture How deep to go? What layers to include? 14

15 Scales on Non Homogeneity The Fine Picture Obtaining a representative sub-sample in the lab is important 15

16 Scales on Non Homogeneity The Very Fine Picture Large particle size makes it difficult to get good slide mounts for light microscopy or grid preps for TEM. The presence of rocks, sticks, even sand sized quartz crystals are a problem when analysis is at higher magnifications. Low mag stereoscopic view of play sand 16

17 Soil is Different Soil and Rock are problem matrices for field and lab personnel alike. Without special care asbestos can be overlooked. Careful sampling plans can reduce inconsistencies, and carefully define what is the sample. 17

18 Limitations of Standard PLM EPA PLM Method (EPA/600/R-93/116) Method for the Determination of Asbestos in Bulk Building Materials As the title suggests and the method explains, this is a method for relatively homogenous bulk building materials, not soil. The final version of this method is quite flexible though and matrix modification prior to analysis is described 18

19 Solutions The analytical approach will vary depending on the potential source of asbestos: Fugitive Asbestos from sources such as demo and construction, illegal dumping, bad removal jobs, etc. NOA (Naturally Occurring Asbestos) Special circumstances like Libby, WTC, Katrina in New Orleans 19

20 Scenario 1 Asbestos Contamination in Soil In scenarios with visible pieces of suspect ACM in the soil, sieving is often the best choice. EPA Region 1 Screening Protocol Protocol for Screening Soil and Sediment Samples for Asbestos Content used by the EPA Region 1 Lab - This is a low tech screening method, semiquantitative at best. - Been around since 1994, revised 97 and 99 - Stereoscopic (20X mag) estimate of % Asbestos MA DEP Sieve Method for the Determination of Asbestos Debris in Soil Quantitative Sieving Method, to be promulgated (hopefully Summer 2007) 20

21 Region 1 Screening Protocol The soil is sub-sampled (only particles < 16mm) Wet sieved through a 60 mesh (250 micron) sieve Only the >250 micron fraction is analyzed Stereoscope (20X) used to quantify, and PLM used to identify 21

22 MA DEP Sieve Method 1. Sample is dried at 60 o C 2. Weigh (1Kg dry start weight minimum) 3. Sieve Stack 6.3 mm sieve 4.75 mm sieve 2.0 mm sieve 22

23 MA DEP Sieve Method 4) Wet sieve into 3 fractions 5) Transfer each fraction to its own disposable tray 23

24 MA DEP Sieve Method 6) Dry and weigh all fractions 7) Each fraction undergoes a stereoscopic examination to extract all suspect debris. 8) For each fraction, homogenous suspect material is placed into separate weighing dishes and analyzed separately. 9) If any material contains >1% asbestos by PLM then it is considered ACM. 24

25 MA DEP Sieve Method The total weight of all the ACM found in all layers is divided by the total starting weight to determine the final percent. This method determines the % of ACM (not the % asbestos) in the soil sample. The proposed standard for Massachusetts is 150mg ACM /KG soil 25

26 MA DEP Sieve Method Performance Pilot Study Results Samples above proposed action limit 26

27 MA DEP Sieve Method Performance Split Samples demonstrate the problems associated with a non homogenous matrix 27

28 MA DEP Sieve Method Pros Relatively quick and easy Summing Up Finds obvious asbestos common sensically, by hand picking it out at low mag Cons Relies on stereoscope (20X) to find suspect ACM Fine material (<2mm) is typically not analyzed Therefore unconsolidated asbestos goes undetected 28

29 Scenario 2: Naturally Occurring Asbestos (NOA) In scenarios where there is no visible evidence of ACM contamination or if it is suspected that there may be NOA in the soil or rock. California Air Resource Board (CARB) Method 435 Determination of Asbestos Content of Serpentine Aggregate The sample is milled and then analyzed by PLM using a 400 or 1000 point count (0.25% or 0.1%). 29

30 CARB Method 435 The sample is: dried in a drying oven and material >3/8 is removed by sieving Milled at liquid nitrogen temperature at minus 200 degrees C (-300 o F) for approximately 4-8 minutes (depending on the sample make up) in order to reduce the nominal particle size to 75 microns. 30

31 CARB Method 435 After milling the sample is analyzed by a PLM 400 or 1000 point count (0.25% or 0.1%). The CARB Method has an abbreviated PLM method in it but the more comprehensive EPA 600 method is recommended after the milling. 31

32 CARB Method 435 One of the main advantages of the CARB Method over the sieving methods is that it enables detection of unconsolidated (loose and unbound from matrix) asbestos fibers. Unfortunately the resolution of the light microscope is only about 0.25 microns. Asbestos fibers/bundles with widths less than this are not detected. 32

33 CARB Method 435 Plus TEM CARB Method for Soil CARB Milling followed by TEM Mass Analysis by EPA 600 Section 2.5 Milled sample is put into suspension, filtered and analyzed. Analysis is performed at up to 20,000X Identification of asbestos using X-Ray Analysis and SAED (selected area electron diffraction) Results are given in percent asbestos by mass Varying levels of analytical sensitivities are offered. 33

34 TEM CARB Method A known mass of sample is weighed out and brought into solution Following the standard milling, 34

35 TEM CARB Method After sonication,the sample is filtered through a 0.4 micron filter 35

36 TEM CARB Method Analyzed by TEM at 20,000X 36

37 TEM CARB Method By carefully measuring the lengths and widths of any asbestos fibers/bundles detected, the individual fiber masses are calculated. The individual weights are then totaled and a mass percent is determined 37

38 TEM CARB Method Performance at 0.1% Round Robin Analysis by TEM to 0.1% Sensitivity Spiked Sample 1 Chrysotile 0.1% Lab 1 Lab 2 Lab 3 Lab 4 Lab 5 Lab 6 38

39 TEM CARB Method Performance at 0.1% 0.4 Round Robin Analysis by TEM to 0.1% Sensitivity Spiked Sample 2 Actinolite 0.1% Lab 1 Lab 2 Lab 3 Lab 4 Lab 5 Lab 6 39

40 Blind Test with Spiked Samples PLM and TEM Chrysotile Actinolite 40

41 Blind Test with Spiked Samples PLM and TEM Chrysotile Actinolite 41

42 One Final Approach The Elutriator Method - Superfund EPA 540-R With this method a soil sample is gravimetrically tracked through sieving into course and fine fractions The fine fraction is then tumbled in a closed chamber and any respirable dust generated is collected on air cassettes Analysis is performed by ISO counting rules This method is peer reviewed and acceptable for risk assessment studies 42

43 Elutriator Method Tumbler apparatus filled with soil 43

44 Elutriator Method Tumbler inside enclosed humidity chamber 44

45 Elutriator Method Air Cassettes on top of the elutriator stack. Isokinetic sampling to catch only the respirable fraction of fibers released from the soil 45

46 Summing Up: The right answer depends on the question. I see building material debris in the soil. Does it have asbestos and if so how much? Do I need to dispose of it as hazardous waste? PLM by MA DEP Sieving Method to give % ACM in soil PLM by modified MA DEP Sieving Method to give % Asbestos in Soil I don t necessarily see suspect asbestos but I think it might be there either from contamination (ex brake shops) or from NOA. PLM CARB 435 (down to 0.25% or 0.1%) TEM CARB 435 (EPA 600 Mass Analysis) Does the Soil Contain Respirable Fibers? EPA 540-R Superfund Method (Elutriator) 46

47 Asbestos Analysis of Soil and Rock Ed Cahill EMSL Analytical Inc