Brownfields: The Next Generation 7 th Annual Canadian Brownfields Network Conference Toronto, ON. 15 June Todd McAlary

Transcription

1 Self-Sustaining Active Remediation (STAR) for Contaminated Soils or Liquid Waste Advances in Quantitative Passive Sampling for Vapour Intrusion Assessments Brownfields: The Next Generation 7 th Annual Canadian Brownfields Network Conference Toronto, ON 15 June 2017 Todd McAlary

2 Smoldering Combustion STAR and STARx are based on the process of smoldering combustion: Exothermic reaction converting carbon compounds to CO 2 + H 2 O Fuel Contaminated Soil or Waste Product Heater Element (for ignition only) Combustion Injected Air Heat Oxidant smoldering possible due to large surface area of organic liquids (e.g., NAPL) within the presence of a porous matrix (e.g., aquifer) 2

3 Modes of Application In situ (below water table) Applied via wells in portable in-well heaters Range of contaminants: Petroleum Hydrocarbons Coal tar Creosote High volatility compounds require fuel surrogate Ex situ (above ground) Soil piles placed on Hottpad system Highly effective and controlled applications Ideal for: Excavated contaminated soils and sediments Waste oils / tank bottom residuals Lagoon sludge 3

4 STAR In Situ Systems 4

5 STARx Hottpad Systems 5

6 Case Study - Site Overview 37-acre former manufacturing facility in Newark, New Jersey PSE&G Coal tar associated with former waste lagoons (now in-filled) 55,000 CY impacted soils: Shallow fill (0-10 ft bgs) Deep Sand (~10-40 ft bgs) Ashland Chemical Co Passaic River Site Diamond Alkali 6

7 STAR Case Study Node (max distance to Treatment Point power source) Cell (Group of Treatment Points treated at the same time) Two target layers: Shallow Fill Deep Sand Shallow Fill: 1700 wells 20-well Cells 10 separation Deep Sand: 300 wells 6-well Cells 20 separation Operation organized by: Well Cell (groups of Wells operated simultaneously) Node (groups of Cells serviced by single system deployment) 7

8 Full-scale System Recuperative Thermal Oxidizer Extracted Vapors to RTO Well head connection Vacuum Extraction Air Injection for Well Points In well Heater Treatment Trailer

9 Full-scale Results Example Cell: 3-D-03 ~10,000kg of coal tar destroyed (via 6 wells) in approximately 10 Before days 100,000 Safe Working Hours After

10 Full-scale Hottpad Field Deployment 10

11 Background Designed for 3,500 m 3 of API separator sludge Petroleum hydrocarbon-impacted soils 11

12 Full-scale Hottpad - Results Before After 12

13 Conventional Active Soil Gas Sampling

14 Passive Sampling C 0 = M UR t The mass (M) and time (t) are measured accurately. The key is to know the uptake rate (UR). UR has units of ml/min

15 Starvation In soil and under building slabs, air flow is low, and may produce the starvation effect when collecting passive samples, leading to negative bias. Starvation occurs when the uptake rate of the sampler is higher than the delivery rate of analytes to the sampler; the sampler will scrub its environment, causing a low concentration bias.

16 Mathematical Modeling What would we expect for the diffusive delivery rate (DDR)?

17 Steady-State Model Total Porosity 37.5% (note scale is semi-logarithmic)

18 Lower the Uptake Rate Decrease area of sampling surface Increase membrane thickness

19 Concentration in Waterlooo Membrane Sampler (µg/m 3 ) 100,000,000 10,000,000 1,000, ,000 10,000 Uptake rate about 1 ml/min Uptake rate about 0.2 ml/min 1,000 1,000 10, ,000 1,000,000 10,000, ,000,000 Concentration in Active Sampler (µg/m 3 )

20 Another Use for Passive Samplers: Long-term Indoor Air Sampling

21 Results 1:1 line % RPD 21

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23 Summary Passive sampling for soil gas sampling has many advantages over active sampling ease of use reproducibility (simple protocols, less inter-operator error) time-weighted average smooths temporal variability Starvation can be mathematically described, and passive samplers designed to minimize the starvation effect This innovation was awarded a US patent (# ) in 2016 Waterloo Membrane Samplers can be used for quantitative passive soil vapour sampling long-term indoor air sampling Passive sampling is accepted in the MOECC vapour intrusion guidance

24 More Information Geosyntec, Demonstration of Improved Assessment Strategies for Vapor Intrusion - Passive Samplers. SPAWAR Systems Center Pacific. Geosyntec, Development of More Cost-Effective Methods for Long-term Monitoring of Soil Vapor Intrusion to Indoor Air Using Quantitative Passive Diffusive-Adsorptive Sampling. ESTCP Project ER , June McAlary, T., X. Wang, A. Unger, H. Groenevelt, T. Gorecki, Quantitative passive soil vapor sampling for VOCs - part 1: theory. Environ. Sci.: Processes Impacts, 2014, 16, 482. DOI: /c3em00652b. McAlary, T., H. Groenevelt, S. Seethapathy, P. Sacco, D. Crump, M. Tuday, B. Schumacher, H. Hayes, P. Johnson, T. Gorecki, Quantitative passive soil vapor sampling for VOCs - part 2: laboratory experiments. Environ. Sci.: Processes Impacts, 2014, 16, 491. DOI: /c3em00128h. McAlary, T., H. Groenevelt, P. Nicholson, S. Seethapathy, P. Sacco, D. Crump, M. Tuday, H. Hayes, B. Schumacher, P. Johnson, T. Gorecki, I. Rivera- Duarte, Quantitative passive soil vapor sampling for VOCs - part 3: field experiments. Environ. Sci.: Processes Impacts, 2014, 16, 501. DOI: /c3em00653k. McAlary, T., H. Groenevelt, S. Seethapathy, P. Sacco, D. Crump, M. Tuday, B. Schumacher, H. Hayes, P. Johnson, L. Parker, T. Gorecki, Quantitative passive soil vapor sampling for VOCs - part 4: flow-through cell. Environ. Sci.: Processes Impacts, 2014, 16, DOI: /c4em00098f. McAlary, T., H. Groenevelt, S. Disher, J. Arnold, S. Seethapathy, P. Sacco, D. Crump, B. Schumacher, H. Hayes, P. Johnson, T. Gorecki, Passive sampling for volatile organic compounds in indoor air-controlled laboratory comparison of four sampler types. Environ. Sci.: Processes Impacts, 2015, 17, 896. DOI: /c4em00560k. Seethapathy, S. and T. Gorecki, Polydimethylsiloxane-based permeation passive air sampler. Part II: Effect of temperature and humidity on the calibration constants. J. Chromatog. A, 2010, 1217, Issue 50, Seethapathy, S. and T. Gorecki, Polydimethylsiloxane-based permeation passive air sampler. Part I: Calibration constants and their relation to retention indices of the analytes. J. Chromatog. A, 2011, 1218, Issue 1,