ADVANCES IN MONITORING PETROLEUM CONTAMINATED SITES Federal Remediation Technologies Roundtable November 2, 2016 Reston, Virginia Charles Newell, GSI Environmental Tom Sale, Colorado State John Connor, GSI Environmental Poonam Kulkarni, GSI Environmental 1 Keith Piontek, TRC Consultants
Key Electron Acceptors For MNA (Yellow/Red Is BTEX Plume) (Concentration: mg/L) Dissolved Oxygen “Hole” Nitrate “Hole” Ferrous Iron “Blob” Sulfate “Hole” Dissolved Methane “Plume” 2
MNA Mass Balance in Plumes: Electron-Acceptor-Limited Biodegradation Biodegradation Source Zone Capacity ( Concentration 17 mg/L) (25 mg/L) Observed Source Zone Concentration (8 mg/L) ZAP! Groundwater Flow 3
Monitored Natural Attenuation (MNA) versus Natural Source Zone Depletion (NSZD) Monitored Natural Attenuation (MNA) • Mostly focused on plume (“how far”) • For hydrocarbon plumes, key focus on: Electron Acceptors Electron Donors • Dissolved Oxygen • Benzene • Nitrate • Toluene • Ferric iron (solid) • Ethylbenzene • Sulfate • Xylenes • Methanogenesis 4
WAIT – THERE’S MORE! 5
Groundwater Mass Flux vs. Vapor Phase Mass Flux Original NSZD Conceptual Model 6 Lundegard and Johnson, 2006; ITRC, 2009
Groundwater Mass Flux vs. Vapor Phase Mass Flux Original NSZD Conceptual Model Johnson Lundegard NSZD Conceptual Model: Include vapor pathway 7 Lundegard and Johnson, 2006; ITRC, 2009
Groundwater Mass Flux vs. Vapor Phase Mass Flux 1-10% Surprising Result: Vapor transport flux is 1 to 2 orders of magnitude greater than groundwater flux! 90-99% 8 Lundegard and Johnson, 2006; ITRC, 2009; Suthersan 2015
Monitored Natural Attenuation (MNA) versus Natural Source Zone Depletion (NSZD) Natural Source Zone Depletion (NSZD) Monitored Natural Attenuation (MNA) Focused on source attenuation (“how • Mostly focused on plume long”) • For hydrocarbon plumes, key focus on: For hydrocarbon sites, key focus LNAPL Electron Donors Electron Acceptors Key reactions: • Benzene • Dissolved Oxygen Nitrate • Toluene • LNAPL CO 2 + Methane • Ethylbenzene • Ferric iron (solid) Methane CO 2 • Xylenes • Sulfate • Methanogenesis Sihota and Mayer, 2011 9
Direct Offgassing and Ebullition of Biodegradation Gases 10 Source: CSU
Direct Offgassing and Ebullition of Biodegradation Gases Bubbles with methane and CO 2 ! Occurs in the pore space with LNAPL (Ng et al., 2015) 11 Source: CSU
Direct Offgassing and Ebullition of Biodegradation Gases Ebullition channel! Bubbles with methane and CO 2 ! Occurs in the pore space with LNAPL (Ng et al., 2015) Source: CSU 12 Source: Sleep et al., 2013
Starting Point: Refinery and Terminal Petroleum Spills Generate Methane from Biodegradation Methane Day 100 Day 102 bubbles! Methane channel! Day 113 Day 106 Source: 13 Ye et al., 13 Source: CSU 2009 Water Saturation
NSZD Conceptual Model Ground Surface O 2 Diffusion Down; CO 2 Diffusion Up O 2 CO 2 Methane Oxidation CH 4 + 2O 2 → CO 2 + 2H 2 O CH 4 , CO 2 Outgassing CH 4 CO 2 CH 4 and CO 2 Outgassing, Ebullition CH 4 CO 2 LNAPL Anaerobic Biodegradation of LNAPL C 11 H 25 + 4.75 H 2 O → 2.375 CO 2 + 8.625 CH 4 14
NSZD Conceptual Model Measure CO 2 at surface to get NSZD rate Ground Surface O 2 Diffusion Down; CO 2 Diffusion Up O 2 CO 2 Methane Oxidation CH 4 + 2O 2 → CO 2 + 2H 2 O CH 4 , CO 2 Outgassing CH 4 CO 2 CH 4 and CO 2 Outgassing, Ebullition CH 4 CO 2 LNAPL Anaerobic Biodegradation of LNAPL C 11 H 25 + 4.75 H 2 O → 2.375 CO 2 + 8.625 CH 4 15
NSZD STUDIES: Johnson et al, 2006; Lundegard and Johnson, 2006; Sihota et al., 2011; McCoy et al., 2013 Oxygen CO 2 Methane 16 Lundegard and Johnson, 2006
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What NSZD Rates are Being Observed? Site-wide NSZD Rate NSZD Study (gallons/ acre /year) Six refinery terminal sites 2,100 – 7,700 (McCoy et al., 2012) 1979 Crude Oil Spill 1,600 (Sihota et al., 2011) Refinery/Terminal Sites in 1,100 – 1,700 Los Angeles (LA LNAPL Wkgrp, 2015) Locations across U.S. where carbon traps have been used to measure NSZD Five Fuel/Diesel/Gasoline 300 - 3,100 rates (E-Flux, 2015). Sites (Piontek, 2014) Eleven Sites, 300 – 5,600 550 measurements (Palaia, 2016) KEY Measured NSZD rates in the POINT: 18 100s to 1000s of gallons per acre per year. 18
BEX Toluene Pre-NVDOC Short n-Alkanes Long n-Alkanes 19 19
Alkanes: BTEX: 50,000 3,000 mol C/m mol C/m Short n-Alkanes Long n-Alkanes Pre-NVDOC Toluene BEX 20 20
How Can NSZD Rates Be Used? • To confirm that LNAPL is biodegrading and quantify the rate • More accurate estimation of remediation timeframe by NSZD • Evaluate and/or replace an active remediation system 21
Optimizing Active LNAPL Remediation Compare to NSZD NSZD Active Remediation Maximum Rate of Remediation (gal/acre/yr) Maximum 7,700 10,200 gal/ac/yr gal/ac/yr Minimum 300 gal/ac/yr Median = 1,400 gal/ac/yr Median = 1,800 gal/ac/yr Minimum 1.25 gal/ac/yr Avg. Site-Wide NSZD Rates (n=19) Active Systems (n=29) 22 22 Source (active systems): Palia, 2016 Multiple Sources
Active Remediation vs. NSZD Rates Palaia, 2016 NSZD Active Remediation Maximum 7,700 Rate of Remediation (gal/acre/yr) Maximum gal/ac/yr 10,200 gal/ac/yr Minimum 300 gal/ac/yr Median = 1,400 Median = 1,800 gal/ac/yr gal/ac/yr Minimum 1.25 gal/ac/yr Avg. Site-Wide NSZD Rates (n=19) Active Systems (n=29) 23 Source (active systems): Palia, 2016 Multiple Sources
NSZD Site Closure: 3 Case Studies Kansas Tank Farm Active system with negligible LNAPL recovery rates • NSZD measurements from 2012-2014 (Carbon traps + • thermal monitoring) • KDHE approved system shutdown in 2015 California Pipeline Terminal Active system with LNAPL recovery rates ~20 gal/yr • NSZD rates measured at >3,000 gal/ac/yr • State Water Board ruling: “Can’t dictate technology” • • NSZD identified as viable remediation technology Oregon Railyard • Active systems: skimming, vacuum enhanced fluid recovery, total fluids recovery • NSZD rates were an order of magnitude higher than current methods 24 • ODEQ approved conditional NFA for the site 24
NSZD Rates in Gallons Per Acre Per Year Measured by Carbon Traps Source: Keith Piontek, TRC Consultants 25 25
Can We Optimize How We Measure NSZD? Source: SB Johnny 26
“Turning a Hot Compost Pile” Source: SB Johnny 27
NSZD Conceptual Model Measure Heat Generation in Subsurface to get NSZD Rates Ground Surface O 2 Diffusion Down; CO 2 Diffusion Up O 2 CO 2 Methane Oxidation Heat CH 4 + 2O 2 → CO 2 + 2H 2 O + HEAT CH 4 , CO 2 Outgassing CH 4 CO 2 CH 4 and CO 2 Outgassing, Ebullition CH 4 CO 2 LNAPL Anaerobic Biodegradation of LNAPL C 10 H 22 + H 2 O → CO 2 + CH 4 *Note: size of arrows indicate degree of release 28
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Temperature Method: 30 mol/m 2 /year 30
Temperature Method: 0.95 um/m2/sec 600 gal/acre/yr Sihota et al., 2016: LI-COR 1.1 um/m2/sec 690 gal/acre/yr 31
CSU/GSI/TRC Thermal NSZD Technology Rollout 2012 - 2016 416 Thermo- couples 38 Wireless Modems ~8 million temperature values In Place Sale et al., Feb. 2014 Provisional Patent Source: CSU Planned 32
Calculating LNAPL Mass Loss by NSZD First Law of Thermodynamics E in - E out + E rxn = dE/dt E in E out E out E rxn E in E out dE/dt E in E out 33
Calculating LNAPL Mass Loss by NSZD First Law of • Lateral energy loss Thermodynamics negligible E in - E out + E rxn = dE/dt E in E out E out E rxn E in E out dE/dt E in E out 34
Calculating LNAPL Mass Loss by NSZD First Law of • Lateral energy loss Thermodynamics negligible E in - E out + E rxn = dE/dt • Background location corrects for solar E in E out energy input E out E rx E in E out n dE/dt E in E out 35
Calculating LNAPL Mass Loss by NSZD First Law of • Lateral energy loss Thermodynamics negligible E in - E out + E rxn = dE/dt • Background location corrects for solar E in E out energy input E out • Steady-state; no change in storage E rxn E in E out dE/dt E in E out 36
Calculating LNAPL Mass Loss by NSZD First Law of • Lateral energy loss Thermodynamics negligible E out = E rxn • Background location corrects for solar E out energy input • Steady-state; no change in storage E rxn E out 37
NSZD Conceptual Model Net Temperature Heat O 2 CO 2 Methane Oxidation CH 4 + 2O 2 → CO 2 + 2H 2 O + Heat Heat Depth CO 2 CH 4 Mobile or Residual LNAPL Anaerobic Biodegradation CO 2 CH 4 of LNAPL C 10 H 22 + H 2 O → CO 2 + CH 4 Dissolved Phase Plume Groundwater 38
NSZD Conceptual Model CO2 flux at Ground Surface Net Temperature Fourier’s Law: E out = K T dT/dz Heat O 2 CO 2 Heat flux: Methane Oxidation (watts/m 2 ) CH 4 + 2O 2 → CO 2 + 2H 2 O + Heat Depth Heat CO 2 CH 4 Where: Mobile or Residual LNAPL K T thermal conductivity (W/m ° C) Anaerobic Biodegradation CO 2 CH 4 Z depth interval of heat flux (m) of LNAPL T change in net temperature ( ° C) C 10 H 22 + H 2 O → CO 2 + CH 4 Dissolved Phase Plume Groundwater 39 Adapted from: ITRC, 2009
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