Comparing Discrete Sampling and Incremental Sampling Methodology with Petroleum Hydrocarbon Contaminated Soils in Canada Kathlyne Hyde, Lisa Moelhman, Terry Obal, Steven Mamet, Trevor Carlson, Steven D. Siciliano Presenting Members Integrity Excellence Responsibility
Background The Interstate Technology & Regulatory Council defines incremental sampling methodology (ISM) as a structured composite sampling and processing protocol. Finalized guidelines released February 2012. Advantages • Estimates of the mean concentration of soil contamination • Representative samples for a specific decision unit (DU) • Reduced data variability
Objectives 1. Develop a protocol for performing incremental sampling from push cores to analyze BTEX & F1-F4 hydrocarbons. 2. Compare ISM hydrocarbon results to the typical Phase II results used in site assessments. 3. Evaluate ISM protocol for the use of remediation plans.
Methods 1) Choose decision units (DU) 2) Choose sampling points within DU 3) Drill push cores to 6 meters depth 4) Phase II assessment 5) Incremental sampling methodology
Site 1: Saskatoon, Saskatchewan
Site 2: Raymore, Saskatchewan DU1: Estimated impacted area DU3 DU2 DU4
Methods 1) Choose decision units (DU) 2) Choose sampling points within DU 3) Drill push cores to 6 meters depth and collect for storage until laboratory sampling can be done 4) Phase II assessment 5) Incremental sampling methodology
Drilling and collecting cores
Storage at -20 ͦͦ C
Methods 1) Choose decision units (DU) 2) Choose sampling points within DU 3) Drill push cores to 6 meters depth and collect for storage until laboratory sampling can be done 4) Phase II assessment 5) Incremental sampling methodology
Phase II assessment In field: • Core drilled • Length of core scanned with photoionization detector • Area with highest reading is sampled into methanol and jars for laboratory analysis of BTEX & F1-F4 • Samples taken at increments of 0.5 m or 0.75 m • Visual ID of contamination and subsequent sampling • Details of soil profile are recorded
Methods 1) Choose decision units (DU) 2) Choose sampling points within DU 3) Drill push cores to 6 meters depth and collect for storage until laboratory sampling can be done 4) Phase II assessment 5) Incremental sampling methodology
ISM Protocol All samples analyzed by Vertical DU’s 0 m Capillary • Deciding what vertical soil portions to combine Laboratory sampling 1.5 m • Plug • Every 5 cm for 1.5 m DU and every 10 cm for 3.0m DU Contaminated • Large for 2-D slabcake • Small into methanol • Wedge • Along entire core • Every 10 cm, a portion into methanol, 20 cm for 3.0 m DU • Remainder of soil into 2-D slabcake 4.5 m • Discrete • Hotspot Deep • Terra-core into methanol • Soil sample unhomogenized into jar 6.0 m
ISM Protocol: Preparing the core
ISM Protocol: Sampling Plug sampling Wedge sampling
ISM Protocol: Homogenizing
ISM Protocol: Volatile extractions
Soil mass: Phase II vs. ISM Plug Wedge Discrete Phase II Methanol 54 g 13 g 5 g 5 g Slabcake 220 g 120 g - - Sample Jar 20 g 20 g Packed Packed Fundamental error is due to compositional heterogeneity . Fundamental error is unavoidable due to our inability to randomly select soil particles to represent the DU, however, collecting sufficient mass can significantly reduce the error.
Phase II False Negatives – What did Phase II miss that ISM captured? 60 Plug Rate of false negatives (%) 50 Wedge Discrete 40 30 20 10 0 Benzene F1-BTEX 1) Our discrete sample detected contamination that Phase II did not 2) Wedge sampling protocol needs modification
CCME F1 Hydrocarbon Concentration 3000 2500 Concentration (ug/g) 2000 1500 1000 500 0 Plug Wedge Discrete Phase II Approximately 2000 ppm difference in concentration between plug and discrete sample Approximately 1200 ppm difference in concentration between plug and Phase II sample
How much soil is contaminated?
Plume example: Saskatoon, SK Phase II Protocol ISM Plug Protocol Courtesy of Steve Mamet
Conclusions The ISM plug protocol is much more effective than the wedge protocol. Phase II will provide worst-case scenario data and is suitable for identifying risk and making further site management decisions. ISM is useful for implementing in-situ remediation techniques to efficiently target contamination.
When should you use ISM? • Not useful for ex-situ remediation • Useful for in-situ remediation • Replace a second Phase II assessment • Plug protocol in the field • Samples sent in for analysis do not increase • Carefully place biostimulation/bioaugmentation delivery systems • Fertilize according to soil mass contaminated for optimal C:N:P ratios
Supervisor: Steven Siciliano Maxxam Director of Scientific Services & Development: Terry Obal Environmental Soil Toxicology Lab Group + the undergrads Special thanks to Richard Nhan , who without, this might have not been possible. Integrity Excellence Responsibility
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