This document discusses the use of LNAPL transmissivity (Tn) in remediation design, progress evaluation, and determining endpoints. Tn is presented as an improved metric for quantifying mobile LNAPL impacts that can be determined through various field methods and recovery data analysis. The document outlines how Tn can be applied within the TRRP-32 framework, including using Tn values to select remediation technologies, calibrate models, evaluate operational performance, and determine when technical impracticability of hydraulic recovery has been reached. Threshold values of 0.3-0.8 ft2/day for Tn are presented as potential decision points for changing remediation approaches.

1. LNAPL Transmissivity (Tn)Remediation Design, Progress and Endpoints H2A Environmental, Ltd. J. Michael Hawthorne, P.G. mhawthorne@h2altd.com May 2010

2. Acknowledgements Andrew Kirkman - AECOM Mark Adamski - BP Tim Smith - Chevron Charles Stone - TCEQ Roger Rinas - Valero Dr. Charbeneau - UT Dr. Huntley - SDSU Dr. Sale - CSU Introduction ©2010 by H2A Environmental, Ltd., All Rights Reserved

3. Questions Tn Can Answer Understanding What is the best way to quantify mobile LNAPL impacts? How can I do this cost-effectively? Comparison I have 10 ft of diesel and 2 ft of neat toluene – How can I compare them? Which one is more likely to migrate? How much more likely? Which one will I be able to pump the most LNAPL from? Which one will operate longer? Prediction How many bbls/gals will each well produce? How long will my recovery last? What remediation technology will be most effective/efficient? Management I manage 300 sites with LNAPL – How do I rank and prioritize potential migration risk and recovery potential? I’ve been pumping water and LNAPL for years; Can I quit? When can I quit? Introduction ©2010 by H2A Environmental, Ltd., All Rights Reserved

4. Analogs Hydrogeology Aquifer Testing yields K and T for water movement / production Pumping Tests and Slug Tests Normalizes all sites to one measurement standard to: Analyze – Compare – Predict – Design Multiphase Fluid Mechanics Multiphase Saturation Distributions add Complexity Different Fluid Properties Result in Different Flow Characteristics Relative Permeabilities - Fluids Compete for Pore Space Result: Generally Inhibited LNAPL Flow Petroleum Engineering Production Decline Curve Analysis Rate Transient Analysis (RTA) Expected Ultimate Recovery (EUR) Analysis Introduction ©2010 by H2A Environmental, Ltd., All Rights Reserved

5. Outline LNAPL Metrics for Hydraulic Recovery LNAPL Transmissivity (Tn) Definition Determination Applicability Limitations Tn and TRRP NAPL Mgmt Responses TRRP-32 Endpoints Remediation Design Operational Performance Examples (Not in Handout) Introduction ©2010 by H2A Environmental, Ltd., All Rights Reserved

7. Decision Point - a Metric at which a change is made (e.g., de minimis liquid recovery so convert from MPE to SVE).End Point - a Decision Point at which an activity ceases (e.g., risk-based cleanup levels attained so remediation stops). Metrics, Decision Points and End Points are captured in tables and flow charts in the TRRP-32 NAPL Management guide. ©2010 by H2A Environmental, Ltd., All Rights Reserved

8. Ideal LNAPL Metric Collective Property incorporates physical & chemical properties of the aquifer & LNAPL (e.g., permeability, viscosity) Incorporates LNAPL Type (benzene vs. bunker oil) Incorporates aquifer type (sand vs. clay) Fundamental or Characteristic Property Repeatable for given conditions Saturation / Mass Driven Multiphase saturation distribution Varies directly with LNAPL mass Easily Measured Supported with multiple lines of evidence Obtained prior to or during remediation Metrics for Hydraulic Recovery ©2010 by H2A Environmental, Ltd., All Rights Reserved

10. Same mass exhibits different thicknesses in different soil typesMetrics for Hydraulic Recovery Modified after Kirkman (2009) ©2010 by H2A Environmental, Ltd., All Rights Reserved

14. Varies by technology – not directly comparable

15. Can’t be used to predict performance prior to startup©2010 by H2A Environmental, Ltd., All Rights Reserved

16. Tn – An Improved Metric Can be easily determined prior to, during and after remediation Comparable across soil types Comparable across LNAPL types Comparable across Technologies Comparable across unconfined, confined and perched conditions Must understand LCSM Must calculate drawdown correctly Comparable between sites Varies directly with LNAPL saturation / mass Measures hydraulic recovery Metrics for Hydraulic Recovery ©2010 by H2A Environmental, Ltd., All Rights Reserved

17. Section 2 Section Break LNAPL Transmissivity (Tn) Definition Determination Applicability Limitations ©2010 by H2A Environmental, Ltd., All Rights Reserved

18. Tn Definition Transmissivity (T) for water is the volume of water flowing through a cross-sectional area of an aquifer that is 1 foot wide X the thickness of the aquifer (b), under a hydraulic gradient of 1 ft/ft, in a given amount of time (e.g., 1 day) LNAPL Transmissivity (Tn) is the volume of LNAPL flowing through a cross-sectional area of an aquifer that is 1 foot wide X the thickness of the mobile LNAPL interval in the aquifer (bn), under a hydraulic gradient of 1 ft/ft in a given amount of time (e.g., 1 day) Transmissivity (Tn) ©2010 by H2A Environmental, Ltd., All Rights Reserved

20. Huntley (2000) Groundwater

21. Charbeneau (2007) API

22. Sale et al (2007) Groundwater

23. ASTM (2010) Under Development©2010 by H2A Environmental, Ltd., All Rights Reserved

24. Baildown Testing Transmissivity (Tn) Drawdown Calc (>0.5 feet) Confined / Unconfined Perched Field Methods Remove Borehole Volume Minimize CGWS Disturbance Boundary Conditions Analytical Options Bouwer & Rice Discharge-based Methods 1/Q, s/Q, SSR ©2010 by H2A Environmental, Ltd., All Rights Reserved

25. Manual Skimming Testing Basis – Skimming Recovery Equation Field Methods Remove Borehole Volume Repeatedly Establish Sustainable NAPL Discharge Minimize CGWS Disturbance Applicability <0.5 Feet or Rapid Recharge Minimizes Gauging Errors Equation: Transmissivity (Tn) ©2010 by H2A Environmental, Ltd., All Rights Reserved

26. Recovery Data Analysis Transmissivity (Tn) NAPL only Removal Skimming Vacuum-Enhanced NAPL Removal Vacuum-Enhanced Skimming Water-Enhanced NAPL Removal Total Fluids Pumping (Single or Dual Pump) Water & Vacuum-Enhanced NAPL Removal MPE ©2010 by H2A Environmental, Ltd., All Rights Reserved

27. Skimming (NAPL Only Removal) Considerations Adjust for bn changes ln(Roi / rw) estimated at 4.6 bn(1-ρr) is max drawdown If operating at less than max drawdown, use Qn and operating drawdown Equation (Charbeneau 2007) Transmissivity (Tn) IDEAL PUMP DEPTH NON-IDEAL PUMP DEPTH ©2010 by H2A Environmental, Ltd., All Rights Reserved

28. Vacuum-Enhanced Skimming Considerations If RaI not known, estimate RaI via Charbeneau (2007) equation – be careful in layered stratigraphy 1st equation uses air flow and open screen to calculate vac influence 2nd equation uses vacuum and ln(RaI / rw) to calculate vac influence Equations (Charbeneau 2007) Transmissivity (Tn) ©2010 by H2A Environmental, Ltd., All Rights Reserved

29. Water-Enhanced NAPL Removal Total Fluids Pumping Single or dual pump Considerations Simple Form (1st Equation) assumes swater is much greater than sn If any doubt, use 2nd Equation Equations Charbeneau (2007) Transmissivity (Tn) ©2010 by H2A Environmental, Ltd., All Rights Reserved

30. Water & Vac-Enh NAPL Removal MPE – DPE or TPE Considerations If RaI not known from pilot testing/operation, estimate RaI as in VES Air flow or Vacuum/RaI options similar to VES Equations (derived from Charbeneau 2007) Transmissivity (Tn) Kirkman (2009) Hawthorne (2010) ©2010 by H2A Environmental, Ltd., All Rights Reserved

31. Physical Properties / Modeling Laboratory Analyses NAPL Saturation Grain-Size Analysis Capillary Pressure Curves Core Photography and others Modeling LDRM Input/Calibration Points Kw / Tw / Tn / vG parameters Saturation Recovery Data Outputs Daily and Cumulative Recovery Saturation Profiles Specific / Recoverable Volumes Tn thru Time Transmissivity (Tn) Capillary Pressure Curve ©2010 by H2A Environmental, Ltd., All Rights Reserved

32. Tracer Testing Transmissivity (Tn) Developmental Stage Concerns Localized Qf but large scale NAPL gradient Uncertain Well Convergence Factor Initially Capital Intensive (Sale et al 2007) ©2010 by H2A Environmental, Ltd., All Rights Reserved

33. Tracer Testing (Tim Smith, Chevron, 2010) Transmissivity (Tn) Field Test Tracer Concentrations(UV/VIS spectrometer ) Gradient LNAPL Thickness Well Construction Analytical Options Calculate LNAPL flux through well Calculate LNAPL flux through formation Calculate Tn Where: Ct = Tracer concentration at time Dt (M/L3) Co = Initial Tracer concentration (M/L3) qwL = LNAPL flux through well (L/T) Dt = change in time between measurements (T) D = diameter of well (L) bL = continuous thickness of LNAPL in the formation (L) iL = LNAPL gradient (L/L) a = flow convergence factor (L/L) qfL = LNAPL flux in the formation (L/T) TL = LNAPL Transmissivity (L2/T) ©2010 by H2A Environmental, Ltd., All Rights Reserved

34. Applicability – Uses for Tn Inexpensive, numeric alternative to laboratory NAPL saturations Calibration Parameter for multiphase model API / Dr. Charbeneau – LNAPL Distribution and Recovery Model (LDRM) Calibrate to initial pre-remediation Tn values (and other site data) Calibrated Model Provides Predicted Values for: Tn and specific/recoverable volumes over recovery time Technology-specific recovery curves for LNAPL – rate and total volume estimates LNAPL/water saturations through time versus residual/irreducible saturations LNAPL thickness profile over time Drawdown profile Remediation Design Parameter Operational Progress Metric End or Decision Point for Hydraulic Recoverability – 0.3 to 0.8 ft2/day Technical Impracticability Threshold for Hydraulic Recovery Transmissivity (Tn) - Design ©2010 by H2A Environmental, Ltd., All Rights Reserved

35. Applicability - Scale Individual Wells Increased Precision Reduced Area of Relevance Collective Recovery Data Decreased Precision Travel Time Considerations Interlocked Network Interception / Capture Barrier Increased Area of Relevance Scale of Measurement Match to Scale of Recovery Transmissivity (Tn) t3 t2 t1 ©2010 by H2A Environmental, Ltd., All Rights Reserved

37. Regulatory Acceptance

38. Threshold Values Evolving

39. Tn applies only to hydraulic removal of LNAPL to the extent practical

40. Tn does NOT address dissolved or vapor phase risk-based drivers

41. Tn measures recoverable, not residual or total LNAPL, and therefore measures progress towards soilresTransmissivity (Tn) ©2010 by H2A Environmental, Ltd., All Rights Reserved

42. Section 3 Section Break Tn and TRRP NAPL Mgmt Responses TRRP-32 Applicability Decision Points Remediation Design Operational Performance ©2010 by H2A Environmental, Ltd., All Rights Reserved

43. TRRP-32 NAPL Management Tn and TRRP Five (5) Step Process TRRP-12A Trigger Identification Response Objectives / Endpoints Design Phase (SIN / RAP) Implementation / Evaluation ©2010 by H2A Environmental, Ltd., All Rights Reserved

44. TRRP-32 NAPL ManagementTn Application ©2010 by H2A Environmental, Ltd., All Rights Reserved Tn and TRRP

45. NAPL Response Endpoint Types ©2010 by H2A Environmental, Ltd., All Rights Reserved Tn and TRRP – STEP 3 NAPL Response Endpoint Types Recovery Control Recovery Only Control via TI

46. NAPL Response Endpoint Matrix(Migrating NAPL Zone Trigger) ©2010 by H2A Environmental, Ltd., All Rights Reserved Tn and TRRP – STEP 3 Nat. Control -NSZD

47. NAPL Response Endpoint Matrix(NAPL Contact with GW Trigger) ©2010 by H2A Environmental, Ltd., All Rights Reserved Tn and TRRP – STEP 3 Alt. Tech – NSZD?

48. TI Demonstration ©2010 by H2A Environmental, Ltd., All Rights Reserved RECOVERY ONLY If Conventional & Alternative Technologies Cannot Achieve Endpoint. RECOVERY If Inability to File an Institutional Control Forces Site into Recovery and Conventional and Alternative Technologies Cannot Achieve Endpoint. Requirements Tool B - Qualitative Screen for TI of Individual Conventional Technologies Based on Site Characteristics Such as K – Should Not Take the Place of Site-Specific Pilot Testing, Analysis, Engineering and/or Design. TI Requires Technically Rigorous Analysis of Time-Series Data from Operation of Alternative Technology Recovery System OR of Data from an Appropriate On-Site Pilot Test and Modeling Study. Tn May be Incorporated into Site-Specific Pilot Testing, Analysis, Engineering and/or Design as a Direct Recoverability Threshold Metric and/or as a Calibration Parameter for a TI Modeling Study. Tn and TRRP – STEP 4

49. Conventional vs. Alt. Technologies ©2010 by H2A Environmental, Ltd., All Rights Reserved Tn and TRRP – STEP 4

50. Conventional vs. Alt. Technologies ©2010 by H2A Environmental, Ltd., All Rights Reserved Tn and TRRP – STEP 4 Decision Pt. for Change from Hydraulic Recovery Technology Based on Tn

51. Design Uses for Tn Estimate upper boundary for specific discharge and seepage velocity – ignores entry pressure head. Valid for plume interior, not margins. Calculate Average NAPL Conductivity from Tn and bn Specific Discharge (Darcy Velocity or Flux) Equation Yields Volumetric Flow Divide Specific Discharge by NAPL Filled Porosity to Get Seepage Velocity for NAPL - Yields Movement (distance per unit time) Tn and TRRP – STEP 4 ©2010 by H2A Environmental, Ltd., All Rights Reserved

52. Remediation Design and Tn Direct Measure of Hydraulic Recoverability Hydraulic vs. Pneumatic vs. Alternative Technology Selection Modeled LNAPL Recovery Technologies Calibrated to Readily Obtained Site Wide Tn Values Technology-Specific Production Curves Sustainability Predicted Decline Curve Analysis for Rate and Total Volume Data Relative Technology Performance Data – Technology Selection Design Cost-Benefit Analysis Projected Operational Lifetime Capital vs. Mobile Infrastructure Design Considerations Equipment Sizing Waste Mgmt / Recycling Volumes ©2010 by H2A Environmental, Ltd., All Rights Reserved Tn and TRRP – STEP 4

53. Implement & Evaluate Implement NAPL Management Strategy Use Appropriate Monitoring Methods Collect NAPL Response Action Performance Data Conduct Evaluations after each Monitoring Event Evaluations (all supported by Tn) Ability of Response Action to Achieve Endpoints NAPL Endpoints Achieved? Should the Technology Change? Is TI Supported by the Data? ©2010 by H2A Environmental, Ltd., All Rights Reserved Tn and TRRP – STEP 5

54. Operational Performance Metric Single Well Recovery Data Analysis During System Operation to Monitor Tn Progress Combine with EUR and Rate-Transient Decline Curve Analysis to Evaluate Progress Towards Hydraulic Recovery Endpoint Tn and TRRP – STEP 5 ©2010 by H2A Environmental, Ltd., All Rights Reserved

55. Summary Tn is an improved metric for hydraulic recoverability Five calculation methods: Baildown Testing Manual Skimming Testing Recovery Data Analysis Physical Properties Analysis Tracer Testing Tn use as a metric Indirect – model calibration parameter Direct – recoverability (0.3-0.8 ft^2/day) TRRP-32 and Tn Design Parameter Technology Selection Production Rate Production Lifetime Model Calibration Response Endpoints Migrating NAPL Zone Contact with GW Decision Point Conventional vs. Alt. Technologies Augment Tool B for Technical Impracticability ©2010 by H2A Environmental, Ltd., All Rights Reserved Tn and TRRP

56. Section 4 Section Break Tn Examples Not in Handout ©2010 by H2A Environmental, Ltd., All Rights Reserved