Successful On Site Bioremediation of Fuel-Contaminated Soil at CFS-Alert

Transcription

1 Successful On Site Bioremediation of Fuel-Contaminated Soil at CFS-Alert David Juck 1, Danielle Beaumier 1, Sylvie Sanschagrin 1, Etienne Yergeau 1, Andrew Tam 2, Chris McRae 2, Don Kovanen 2, Drew Craig 2, and Charles W. Greer 1 1 National Research Council Canada, Energy, Mining and Environment 2 National Defence, 8 Wing/CFB Trenton Environmental Management April 26, RPIC Federal Contaminated Sites National Workshop

2 Presentation Outline Site description of CFS-Alert Challenges in the Arctic Feasibility study Ex situ biopile implementation Opening the Black Box Conclusions 2

3 3 CFS-Alert

4 CFS-Alert Built in 1950 as a weather station, Alert became a Canadian Military Communications Research Facility in At its peak of activity in the 1970 s, 200 military staff were stationed year around at CFS-Alert. Currently about staff, mostly civilian contractors Our work there Started in 2006 Site characterization and delineation In situ and ex situ bioremediation 4

5 5 CFS-Alert

6 Late August at CFS-Alert 6

7 10 Challenges in the Arctic Temperature Very short treatment window February April June Average temperatures in June, July and August of -0.8 C, 3.3 C and 0.8 C, respectively. August October December 7

8 Challenges in the Arctic cont. Desert conditions Total average annual precipitation is mm (mostly in July, August and September) Approximately the same as one month in Montreal Permafrost Impermeable barrier - can be a benefit or problem Contain the contamination to upper 1m of soil Horizontal movement of contamination during spring freshet Stability of infrastructure is based on the stability of the permafrost 8

9 Challenges in the Arctic cont. Logistics Limited infrastructure Limited heavy equipment access and operator time Limited experience with remediation work All materials have to come in by airplane Can take 2 years to move material to site Site history Continual rotation of staff means little to no corporate memory of previous activities or installations 9

10 CFS-Alert during heyday 10

11 11 Biodegradation Feasibility Study

12 Feasibility Study Worm Farm Soil Diesel contaminated soil Alternate treatments previously tried Nutrient amendments (N-P-K) MAP (monoammonium phosphate) MAP most effective 12

13 13 Ex Situ Biopile

14 2006 Diesel Pipeline Spill 14

15 Biopile Construction Biopile treatment area built in 2007 to treat a diesel spill 40 x 100 m Sand foundation, geotextile, impermeable membrane and sand base, berm approximately 2.0 m. 15

16 16

17 Contaminated Soils 2006 Diesel Pipeline Spill Breach in diesel pipeline late September 2006 Small amount of soil excavated at far end of spill Majority of soil excavated during 2007 field season Approximately 2,000 m 3 of soil in total Auxiliary Power Plant Spill 2007 Spill during re-filling of fuel tank Excavation within 24 hours of spill event Approximately 500 m 3 of soil excavated Cat House Managed soils Contaminated soils from 3 areas excavated and combined (2011) Approximately 100 m 3 of soil Contamination at least 12 years old 17

18 Biopile Treatment Soil windrowed T=0 samples collected MAP treatment started in 2007 ca. 250 kg MAP/year, turning once per year < 50 mg MAP/kg soil over total treatment Control pile no MAP 18

19 PHC Mineralization Activity A A 50 Mineralization (%) LO-1 LO-2 LN-1 LN-2 LC-1 SO-1 SN-1 SN-2 sterile control B Mineralization (%) LO-1 LO-2 LN-1 LN-2 LC S-1 S-2 S-3 S-4 HF sterile control B Time (days) Time (days)

20 F2 Concentrations 2006 and 2007 Spills F2 Concentrations (mg/kg) F F2 average for all biopile samples collected was 112 mg/kg (guideline of 260 mg/kg) No hotspots within biopile No significant changes in control pile concentrations Biopile Control 20

21 Cat House Managed Biopile F2 Concentrations (mg/kg) F2 Soils excavated from 3 different areas at Alert All spills over 15 years old F2 Starting average ca. 2,000 mg/kg Average F2 concentration in August was 200 mg/kg One hotspot at guideline concentration (414 mg/kg) Aged soil responding very rapidly to treatment 21

22 22 Opening the Black Box

23 Who s there? What are they doing? We know that the PHCs are being degraded due to the treatment system What are the population dynamics at play? What biodegradation pathways are being stimulated? Is the treatment targeting the organisms we want? Molecular biological methods are now available to answer these questions Targeting the DNA and RNA of the organisms present in the system 23

24 Metagenomic Analysis Population Changes Decrease in diversity upon contamination High initial numbers of Gammaproteobacteria, decreased over time increase over time in Actinobacteria Main Gammaproteobacteria are Pseudomonas species Low numbers of Pseudomonas in pristine soil Increased dramatically following contamination Dynamic system 24

25 Quantitative PCR Gene Copy Number (copies/ng DNA) Year alkb (PspEu5&Pp) alkb1 (Q15) Following the gene copy number for alkane monooxygenase Important first step in alkane biodegradation Significant initial increase in Pseudomonas version Delayed increase in Rhodococcus version Similar trend when gene expression followed Similar trend observed with ndob (for aromatics biodegradation) 25

26 26 Conclusions

27 Conclusions Bioremediation of PHCs is a viable option under Arctic conditions Simple passive biopile system effective on new and aged contamination More is not necessarily better when it comes to treatment application More frequent application of low concentration nutrients keeps the degraders happy Inhibition of activity with high concentrations of nutrients Cost effective solution Estimated at $45/m 3 Very active and dynamic indigenous microbial community 27

28 Thank you David Juck, Ph.D. Research Officer Tel: