ITRC LNAPL Guidance / Training Workshop

Transcription

1 1 ITRC LNAPL Guidance / Training Workshop 2016 West Virginia Brownfields Conference September 7, 2016 Sponsored by: Interstate Technology and Regulatory Council (

2 2 ITRC - Shaping the Future of Regulatory Acceptance Host organization Network State regulators All 50 states, PR, DC Federal partners Disclaimer Full version in Notes section Partially funded by the U.S. government ITRC nor US government warranty material DOE DOD EPA ITRC Industry Affiliates Program Academia Community stakeholders ITRC nor US government endorse specific products ITRC materials copyrighted Available from Technical and regulatory guidance documents Internet-based and classroom training schedule More

3 3 ITRC LNAPL Team ITRC LNAPL Team formed in July 2007 Collaborative effort involving State and Federal Regulators, Consultants, Industry Representatives, and Stakeholders Industry Representatives 19% Stakeholders 5% State Regulators 35% Consultants 31% Federal Agencies 10%

4 4 Why did ITRC form an LNAPL Team? LNAPL is present at thousands of sites LNAPL perceived as a significant environmental threat LNAPL poses technical and regulatory challenges State regulatory agencies had a backlog of LNAPL sites that were not effectively approaching an endpoint, i.e., No Further Action (NFA) 2008 ITRC LNAPLs Team State Survey States requested training!

5 5 Why Focus on LNAPL? LNAPL policies and regulations frequently are not science-based, feasible, beneficial, or practical Promote holistic consideration of LNAPL in the context of overall site corrective action objectives address the LNAPL disconnect in RBCA states Connect remedial objectives and goals with remedial technology selection Better understanding facilitates better decision making

6 6 Goals & Issues for the Team Help re-evaluate regulatory LNAPL paradigms Promote objective-driven remedial technology selection strategy (begin with end in mind although objectives may or may not be risk-based) Promote LNAPL Conceptual Site Model (LCSM) Address maximum extent practicable and identify metrics to determine when met Conveying science understanding, but maintaining tool-focused purpose

7 7 ITRC LNAPL Team Documents and Training April 2009: Technology Overview document on LNAPL Natural Source Zone Depletion (NSZD) December 2009: LNAPL Technical/Regulatory Guidance document : LNAPL Internet-Based Training: Part 1: LNAPL Behavior in the Subsurface Part 2: LNAPL Characterization & Recoverability Part 3: LNAPL Remedial Technologies : LNAPL Classroom Training New ITRC team: LNAPL Update (starting in 2016)

8 8 ITRC LNAPL Guidance / Training Workshop Material from: 2009 Technical Guidance Parts 1, 2, and 3 of Internet Based Training (IBT) Classroom Training NOT A SUBSTITUTE FOR FULL TRAINING!

9 9 Tech Guidance Process Flow Diagram LNAPL characterization Develop LCSM IBT-1, 2 Identify LNAPL concerns Sections 3 & 4 Section 6 Identify LNAPL objectives, goals, site/lnapl condition to screen technologies (Screening Step 1: Table 6-1) Screen technologies: Geology factors (Screening Step 2: Tables A) Screen technologies: Evaluation factors (Screening Step 3: Tables B) Section 7 Minimum data requirements and critical technology Group (Tables C) Section 8 Establish goals and metrics and implement LNAPL remediation Monitor/assess LNAPL remediation performance Demonstrate goals met ITRC Tech Guidance p. 28

10 10 What Is LNAPL? NAPL = Non-Aqueous Phase Liquid Does not mix with water and remains as a separate phase Petroleum hydrocarbons and chlorinated solvents LNAPL = NAPL that is less dense than water Gasoline, diesel fuel, jet fuel, and crude oil Multi-component mixtures DNAPL = NAPL that is more dense than water Chlorinated solvents PCE, TCE, TCA Single-component products DNAPLs are not discussed in this course See ITRC s website for information on DNAPL s LNAPL Water

11 11 LNAPL Common Mis per ceptions LNAPL enters soil pores just as easily as groundwater You can hydraulically recover all of the LNAPL from the subsurface All soil pores in an LNAPL plume are completely filled with LNAPL LNAPL floats on the water table or capillary fringe like a pancake and doesn t penetrate below the water table LNAPL thicknesses in monitor wells are exaggerated (compared to the formation) by factors of 2, 4, 10, etc.

12 12 LNAPL Common Mis per ceptions LNAPL thicknesses in monitor wells are always equal to the LNAPL thicknesses in the formation LNAPL in a monitor well means it is mobile and migrating LNAPL plumes spread due to groundwater flow LNAPL plumes continue to move long after the release is stopped

13 Basics 13 Basic Concepts Learning Objectives: Refresh on some fundamental concepts to get everyone on the same page Time for a refresher.

14 Basics 14 Basic Concepts LNAPL what we re focused on LNAPL saturation In-well LNAPL thickness Unsaturated and saturated zone Pore sharing Water level responses in different groundwater systems Homogeneous and heterogeneous Head and gradient Hydraulic conductivity and transmissivity Mobile versus migrating LNAPL Conceptual Site Model (LCSM)

15 Basics 15 LNAPL Source Zone Release Source Adsorbed Phase Vapor Phase LNAPL Source Zone LNAPL Dissolved Phase Adsorbed, dissolved, and vapor-phase impacts are consequence of LNAPL source but not the focus here See ITRC documents on PVI (2014) and Mass Flux / Mass Discharge (2010)

16 Basics 16 The Name Game LNAPL LNAPL present, but cannot flow into wells LNAPL can flow into wells Terminology Changes Csat, Residual, Mobile, Migrating Jargon Phase-Separated Hydrocarbons Free Product Separate Phase Free LNAPL Free Phase

17 Basics 17 Saturation Versus Residual Saturation When LNAPL Saturation in the ground exceeds LNAPL Residual Saturation LNAPL Saturation (Sn) Fraction of pore space occupied by LNAPL Sn>Snr Residual LNAPL Saturation (Snr) Fraction of pore space occupied by LNAPL that cannot be mobilized under an applied gradient Sn<Snr

18 Basics 18 In-Well LNAPL Thickness The thickness of LNAPL measured in a well Air/LNAPL Interface Air Monitoring Well Air/LNAPL Interface LNAPL/Water Interface LNAPL Thickness Water LNAPL/Water Interface Key Point: The LNAPL thickness is a neat-separate layer in a glass or a well, but it does not distribute so neatly in the formation.

19 Basics 19 Unsaturated and Saturated Zone Water Table Soil grain Cross section Unsaturated Zone Soil Grain Water Air Saturated Zone Water Unsaturated zone zone between land surface and water table, porosity occupied by air, and water at less than atmospheric pressure (aka: vadose zone) Saturated zone zone below the water table (unconfined), porosity filled with water at pressure above atmospheric

20 Basics 20 LNAPL Shares Pore Space with Air or Water Air Water Unsaturated zone Soil grain Cross section LNAPL LNAPL Water Saturated zone Soil grain Key Point: When LNAPL enters soil pores, it is not the only fluid in the pore. It must push the air and/or water out of the way to enter the pore. This influences the way LNAPL distributes in the subsurface ITRC Tech Guidance Section 3

21 Basics 21 Water Level Responses in Different Groundwater Systems Unconfined the water level in a well is at the same elevation as the top of the water bearing zone (water table) saturated thickness and water level in well rises and falls with recharge and discharge Water Fluid Confined low permeability beds trap (confine) groundwater so that the top of the water bearing zone is below the water level in a well water level in well rises and falls with recharge and discharge, but saturated thickness stays same Perched groundwater is perched atop a low permeability layer that locally blocks downward flow to the underlying regional water table thus perched water level above water table (independent of one another) Confining Water Water Perching layer Key Point: Can have unconfined, confined, and perched groundwater conditions, and can also have analogous LNAPL conditions.

22 Basics 22 Homogeneous and Heterogeneous Vanilla Mint Chocolate Chip Homogeneous Think uniform soil type and characteristics Heterogeneous Think non-uniform or variable mixed soil type and characteristics Key Point: There is always some degree of heterogeneity in the formation that influences LNAPL distribution and behavior, although it may be insignificant to the LCSM

23 Basics 23 Head and Gradient A Duck is a Duck Head Difference or Rise (e.g. A - B) A elevation (ft) LNAPL B elevation (ft) LNAPL Distance or Run Head: A point measure of the pressure in a fluid expressed as the equilibrium elevation of the top of that fluid in a well, e.g., the LNAPL head at point A Gradient: The change in total head divided by the distance over which the change occurs e.g., Rise/Run Key Point: Liquids (water or LNAPL) flow from high head to low head at a rate that is proportional to the gradient.

24 Basics 24 Hydraulic Conductivity (Kw) and Transmissivity (Tw) Coefficients that relate the ability of a fluid to move through a permeable medium (fluid moves more easily through a sand than through a clay, for example) Kw proportionality coefficient describing the ability of a permeable medium to move water [Kw = discharge/area x gradient (length/time)] Tw coefficient describing the ability of a permeable medium to transmit water through a unit aquifer width under unit hydraulic gradient [Tw = Kw x aquifer thickness (length 2 /time)] Estimate from literature or from aquifer test Sand Key Point: LNAPL conductivity (K n ) and LNAPL transmissivity (T n ) exists but may be more complex because LNAPL shares the pore space with the water. Clay

25 Basics 25 Migrating LNAPL is Not Same Meaning as Mobile LNAPL Migrating LNAPL the LNAPL body footprint or extent is spreading Time 1 LNAPL Time 2 LNAPL Key Point: Don t confuse mobile with migrating ITRC Tech Guidance Section 3

26 Basics 26 LNAPL Conceptual Site Model (LCSM) LCSM The understanding of LNAPL site conditions Where? What? Migrating? Recoverable? It s iterative!!!! Key Point: The state of understanding of how things are in order to make a good decision. ITRC Tech Guidance Section 4

27 What We Have Learned 27 Knowledge Check LNAPL is Light Non-Aqueous Phase Liquid (and it s not just the LNAPL you see in the well!) Fluids flow from high head to low head (down the pressure gradient) Mobile LNAPL and migrating LNAPL are NOT the same thing In the ground, LNAPL and water share Pore Space The general framework for understanding LNAPL conditions at a site is a LNAPL Conceptual Site Model (LCSM)

28 Putting It All Together 28 Consider This.. Factors that control subsurface LNAPL distribution and behavior also influence the remediation success. You must have some understanding of the influences to exploit them or to overcome them. Key Point: You need to understand subsurface LNAPL behavior details or you will not apply the Tech Guidance effectively.

29 29 Tech Guidance Process Flow Diagram LNAPL characterization Develop LCSM IBT-1, 2 Identify LNAPL concerns Sections 3 & 4 Section 6 Identify LNAPL objectives, goals, site/lnapl condition to screen technologies (Screening Step 1: Table 6-1) Screen technologies: Geology factors (Screening Step 2: Tables A) Screen technologies: Evaluation factors (Screening Step 3: Tables B) Section 7 Minimum data requirements and critical technology Group (Tables C) Section 8 Establish goals and metrics and implement LNAPL remediation Monitor/assess LNAPL remediation performance Demonstrate goals met ITRC Tech Guidance p. 28

30 30 LNAPL Common Mis per ceptions LNAPL enters the pores just as easily as groundwater You can hydraulically recover all of the LNAPL from the subsurface All the pores in an LNAPL plume are filled with LNAPL LNAPL floats on the water table or capillary fringe like a pancake and doesn t penetrate below the water table Thickness in the well is exaggerated by a factor or 4, 10, 12, etc. LNAPL thickness in a well is always equal to the formation thickness If you see LNAPL in a well it is mobile and migrating LNAPL plumes spread due to groundwater flow LNAPL plumes continue to move over very long time scales

31 31 LNAPL Source Zone Release Source Large h LNAPL LNAPL LNAPL must displace the existing fluids (air, water) filling a soil pore to enter a pore space It is easier for LNAPL to displace air than water

32 32 Resistance to Movement of LNAPL into and out of Water-Filled Soil Pores For water wet media Soil grains Non-wetting fluid (e.g., air or LNAPL) Flow Wetting fluid (e.g., water) preferentially contacting the soil ~1mm Flow LNAPL Water LNAPL will only move into water-wet pores when entry pressure (resistance) is overcome Applies to vertical and lateral migration

33 33 How is a Water-Filled Pore Resistant to LNAPL Entry? Soil grains Wetting fluid (e.g., water) preferentially contacting the soil Non-wetting fluid (e.g., air or LNAPL) ~1mm Displacement head for LNAPL entry into water-filled pores h Nc r( 2 W cos o ) g h Nc = displacement head for LNAPLwater system, the LNAPL head required to displace water from waterfilled pores Parameter Water/LNAPL interfacial tension (σ) Wettability (wetting fluid contact angle) Cos Ф Pore size (r) LNAPL density (ρ o ) Parameter trend h Nc LNAPL potential to enter water-filled pore Key Point: Higher h Nc means its harder for LNAPL to displace water from pores

34 34 Real Site Capillary Pressure (Moisture Retention) Curves Capillary Head, ft H 2 O Easier Water Displacement- Harder 100 In practice, capillary pressure curves are used to determine displacement head Clay holds water more tightly Difficult for LNAPL to enter Sand water-filled pores Clayey Sand Sand Sand holds water less tightly Clay LNAPL more easily displaces water to occupy the pore 10 1 Soil Core Clayey Sand Clay Displacement head for non-wetting fluid = capillary rise in a water-air system = h da 40 in 10 in Water Saturation, % 4 in This graph is for an air-water system, but can be scaled for application to an LNAPLwater system Displacement head (h dn ) refers to LNAPL-water system in subsequent slides Key Point: Hard for LNAPL to displace water from finer-grained pores

35 35 How Displacement Head Affects Lateral Migration and Vertical Distribution Displacement head affects both the vertical distribution and the lateral migration of LNAPL Can explain why LNAPL bodies stabilize over time LNAPL needs to displace existing fluids to enter a pore Easier for LNAPL to displace air (vadose zone) than water (saturated zone)

36 36 LNAPL Common Mis per ceptions LNAPL enters the pores just as easily as groundwater You can recover all LNAPL All the pores in an LNAPL plume are filled with LNAPL LNAPL floats on the water table or capillary fringe like a pancake and doesn t penetrate below the water table Thickness in the well is exaggerated by a factor or 4, 10, 12, etc. LNAPL thickness in a well is always equal to the formation thickness If you see LNAPL in a well it is mobile and migrating LNAPL plumes spread due to groundwater flow LNAPL plumes continue to move over very long time scales

37 37 Vertical LNAPL Distribution No Pancake Model vs. Vertical Equilibrium Model Yes Pancake Model Vertical Equilibrium Assumes LNAPL floats on water table Uniform LNAPL saturation LNAPL Water Grains LNAPL penetrates below water table LNAPL and water coexist in pores

38 Height above water- LNAPL interface (ft) Gasoline 38 Grain Size Effects on LNAPL Saturation Distributions (Vertical Equilibrium Model) Medium Sand, 1.5 gal/ft 2 Silt, 0.7 gal/ft 2 Gravel, 6 gal/ft 2 Pancake, 13 gal/ft LNAPL Saturation Key Point: Volumes based on pancake model (uniform saturations) are over estimated! For a given LNAPL thickness, LNAPL saturations and volumes are different for different soil types (greater for coarser-grained soils)

39 Height Above the LNAPL/Water Interface (ft) 39 Inference from LNAPL Thickness in a Well on Relative Saturation in Silty Sand ft Thickness 5 ft Thickness 2.5 ft Thickness 1 ft Thickness For a given soil type Higher thickness in well Higher capillary pressure Higher LNAPL saturation LNAPL Saturation (%)

40 Ft Above LNAPL/Water Interface 40 Measured and Modeled Equilibrium LNAPL Saturations LNAPL Saturation (%) Beckett and Lundegard (1997), Huntley et al. (1994) # Modeled - Soil Type

41 41 LNAPL Saturations Are Not Uniform LNAPL preferentially enters larger pores (easier to move water out of the pore) 27% 47% 14.8% 2.7% Higher LNAPL saturation in coarser-grained soil Maximum LNAPL saturations typically low (5-30%) in sands (can be higher at new release or constant release) Percent finegrains Percent benzene saturation Lower LNAPL saturation in finergrained soil Saturations even lower for finer-grained sediments Plain light Mark Adamski UV light Fluoresced benzene in soil core

42 Height Above the LNAPL/ Water Interface (ft) 42 Analogy to LNAPL Body More LNAPL mass in the core (greater thickness) Less LNAPL mass at the perimeter (less thickness) ft Thickness ft Thickness 2.5 ft Thickness 2 1 ft Thickness LNAPL Saturation (%) Modified from Schwille, 1988

43 43 Pancake vs. Vertical Equilibrium Model Why important? Pancake concept results in overestimation of LNAPL volumes based on thickness observed in a well LNAPL generally does not occur as a distinct layer floating on the water table at 100% or uniform LNAPL saturation Unrealistic expectations of recovery due to incorrect site conceptual model Uniform saturations Uniform LNAPL distributions

44 44 LNAPL Volume Estimates To understand the scale of the problem May not be necessary at all sites Necessity and rigor of estimate depends on site-specific drivers Total volume includes recoverable LNAPL and residual LNAPL Tend to be order of magnitude estimates

45 45 LNAPL Common Mis per ceptions LNAPL enters the pores just as easily as groundwater You can recover all LNAPL All the pores in an LNAPL plume are filled with LNAPL LNAPL floats on the water table or capillary fringe like a pancake and doesn t penetrate below the water table Thickness in the well is exaggerated by a factor or 4, 10, 12, etc. LNAPL thickness in a well is always equal to the formation thickness If you see LNAPL in a well it is mobile and migrating LNAPL plumes spread due to groundwater flow LNAPL plumes continue to move over very long time scales

46 Elevation Time 46 Why does the LNAPL Thickness in a Well Increase When the Water Table Drops? s n s n s n s n s n residual water low 3-phase residual LNAPL saturation low 3-phase residual LNAPL saturation higher 2-phase residual LNAPL saturation LNAPL immobile higher 2-phase residual LNAPL saturation residual water low 3-phase residual LNAPL saturation after Jackson, s w s w s w s w s w Courtesy Chevron

47 Residual Oil Saturation 47 Residual LNAPL Saturation Higher in Saturated Zone than in Vadose Zone Vadose zone Saturated zone Example ranges from Parker et al., 1989

48 48 LNAPL Thickness in Well Increases with Increase in Water Level? Bottom Filling of Well Clay Clay Clay Gravel LNAPL Gravel LNAPL Water Water Monitoring well is a giant pore!

49 49 Well Thickness versus Formation Thickness Unconfined Water Table Rise Perched Confined Fractured

50 50 LNAPL Behavior and Distribution LNAPL is distributed at varying saturations vertically (always less than 100%) LNAPL saturation depends on soil type and capillary pressure Under unconfined conditions LNAPL thickness in wells can be correlated to its saturation in the formation Under perched, confined or fractured systems well thickness cannot be used to predict LNAPL saturations or impacted thickness in the formation LNAPL thickness and response to water level can be different for different aquifer systems

51 51 LNAPL Common Mis per ceptions LNAPL enters the pores just as easily as groundwater You can recover all LNAPL All the pores in an LNAPL plume are filled with LNAPL LNAPL floats on the water table or capillary fringe like a pancake and doesn t penetrate below the water table Thickness in the well is exaggerated by a factor or 4, 10, 12, etc. LNAPL thickness in a well is always equal to the formation thickness If you see LNAPL in a well it is mobile and migrating LNAPL plumes spread due to groundwater flow LNAPL plumes continue to move over very long time scales

52 52 Potentially Mobile Fraction of the LNAPL Distribution Residual Saturation Typical Reg Focus Source: Garg LNAPL Potentially Mobile and Recoverable LNAPL mobility is the additional consideration due to exceeding residual saturation LNAPL Saturation (% Pore Space) Key Point: LNAPL potentially mobile only if the saturation exceeds residual saturation

53 53 Darcy s Law for LNAPL and LNAPL Conductivity LNAPL and groundwater co-exist (share pores) In an water/lnapl system, not just dealing with a single fluid (groundwater or LNAPL) Darcy s Law governs fluid flow Darcy s Law applicable to each fluid (water/lnapl) independently

54 LNAPL Conductivity / Saturated Hydraulic Conductivity 54 LNAPL Conductivity is also Dependent on Viscosity of the LNAPL 0.3 q o = K o i o K o /K w 0.2 Gasoline K o = k k ro ρ o g/ µ o = k ro K w ρ o μ w / ρ w µ o Terms defined in previous slide LNAPL Saturation Diesel Key Points: For a given LNAPL saturation, higher LNAPL viscosity lower LNAPL conductivity For a given LNAPL viscosity, higher LNAPL saturation higher LNAPL conductivity

55 Relative Permeability 55 Relative Permeability (k r ) Definition: Porous media ability to allow flow of a fluid when other fluid phases are present % Soil Pore Volume NAPL (k ro ) Water Water Saturation NAPL Saturation 100% 0 Consider water/lnapl in soil: Saturation relative permeability Relative permeability of soil for water or LNAPL at 100% saturation = 1 Relative permeability for both LNAPL and water decreases rapidly as saturation declines from 100% Below residual saturation, flow decreases exponentially Relative permeability of LNAPL (k ro ) and relative permeability of water inversely related

56 Relative Permeability 56 Relative Permeability (continued) 1 NAPL (k ro ) Water LNAPL body core (max k r0 ) Higher LNAPL k ro % Soil Pore Volume Water Saturation NAPL Saturation 100% As LNAPL saturation approaches residual saturation, relative permeability for LNAPL approaches zero 0 LNAPL body perimeter (min k r0 ) Lower LNAPL k ro Key Point: Core of LNAPL body - highest saturations highest relative permeability highest flow rate

57 57 Displacement Head and LNAPL Migration There is a minimum LNAPL displacement entry pressure or displacement head (h dn ) that must be overcome for LNAPL to migrate into water-wet pores - this minimum displacement head can be related to the thickness of LNAPL in the formation If LNAPL thickness is less than this minimum thickness, then no LNAPL movement into water-wet pores occurs Field scale observations of LNAPL are consistent with LNAPL bodies that stop spreading laterally due to displacement entry pressure A quantitative understanding of the displacement head and relationship to LNAPL thickness thresholds in monitoring wells is an area of active research and debate Key Point: Water acts as a capillary barrier against continued LNAPL spreading

58 Relative Permeability 58 LNAPL Plumes Conceptual LNAPL saturation conditions after LNAPL plume spreading stops Irreducible water saturation 1 Residual LNAPL Saturation NAPL (k ro ) Stationary LNAPL Plume % Water Water Saturation NAPL Saturation 100% 0 LNAPL head< resistive forces, no LNAPL flow Saturations/relative permeability decreases away from plume core At plume edge LNAPL saturation and thickness in a well is > 0, but stable due to displacement head LNAPL in the plume core can be mobile, but plume footprint (extent) is stable

59 59 LNAPL Mobility Large h LNAPL Time 1 Time 2 h LNAPL dissipated Key Point: Once the LNAPL head dissipates, it is no longer sufficient to overcome LNAPL entry pressure and LNAPL movement ceases

60 60 Think of your own cases Remember that: LNAPL can initially spread at rates higher than the groundwater flow rate due to large LNAPL hydraulic heads at time of release LNAPL can spread opposite to the direction of the groundwater gradient (radial spreading) After LNAPL release is abated, LNAPL bodies come to be stable configuration generally within a short period of time

61 Putting It All Together 61 Consider This..Again Factors that control subsurface LNAPL distribution and behavior also influence the remediation success. You must have some understanding of the influences to exploit them or to overcome them. Key Point: You need to understand subsurface LNAPL behavior details or you will not apply the Tech Guidance effectively.

62 62 ITRC LNAPL Guidance / Training Workshop LNAPL Conceptual Site Model LNAPL Site Characterization LNAPL Composition and Saturation Q&A Hydraulic recovery evaluation and limits LNAPL management objectives and goals Introduction to LNAPL remedial technologies Q&A

63 63 LNAPL Conceptual Site Model (LCSM) Link between Site Characterization and Management Description and interpretation of physical and chemical state of the LNAPL body Facilitates understanding of the LNAPL conditions, site risks, and how best to remediate Scaled to the LNAPL impacts and associated issues that require management Iterative process to increase the understanding of the LNAPL body and site risks Sufficient when additional information not likely to lead to a different decision (i.e., need to know vs like to know)

64 64 LNAPL Understanding is an Iterative Process LNAPL Characterization LNAPL composition LNAPL saturation LNAPL location LNAPL Conceptual Site Model LNAPL Management Maximum extent practicable? Drivers: mobility and future risk Remedial objectives and end points Remedial action selection

65 65 LNAPL Conceptual Site Model (LCSM) LCSM used to understand Delineation (horizontal and vertical) Age and Chemical/Physical Character Volume Mobility (or Stability) Longevity Recoverability Source / Pathway / Receptors LCSM used to help make management decisions

66 Hydrogeologic & Plume Factors Low-degradability/ persistent compounds Geologic/transport complexity Toxicity/Chemical mobility Hydrologic Variability 66 Factors Affecting LCSM Complexity Potential Risk Factors Offsite Plume/Sensitive Receptors Toxicity/Pathway Magnitude/GW use Mobility & mass in place/longevity Business & Community Issues Tier 2 Sites Tier 3 Sites Tier 1 Sites ASTM E2531, 2006 Example factors affecting LCSM Complexity. Note,. this is an example only, the boundary between Tiers is subjective based on user judgment

67 67 ITRC LNAPL Guidance / Training Workshop LNAPL Conceptual Site Model LNAPL Site Characterization LNAPL Composition and Saturation Q&A Hydraulic recovery evaluation and limits LNAPL management objectives and goals Introduction to LNAPL remedial technologies Q&A

68 68 LNAPL Site Characterization Existing data Direct methods/conventional assessment Indirect methods Laboratory methods Database/empirical values Remember: Not all of these data may be necessary

69 69 Example LNAPL Indicators Known LNAPL release Observed LNAPL (e.g. wells or other discharges) Visible LNAPL or other direct indicator in samples Fluorescence response in LNAPL range Near effective solubility or volatility limits in dissolved or vapor phases Dissolved plume persistence and center-of mass stability TPH concentrations in soil or groundwater indicative of LNAPL presence Organic vapor analyzer (OVA) and other field observations Field screening tests positive (for example, paint filter test, dye test, shake test) Modified from: ASTM E2531 Table 1

70 70 Considerations for Assessing LNAPL Presence Based on Observation Estimates of the source area can be based on observations in wells, boring logs, and other visual observations Uncorrected observations should not be used to estimate the volume or recoverability Seasonal fluctuations should be accounted into this assessment Creek River Creek Locations of seeps along banks or other vertical cuts aid in characterizing LNAPL impacts to surface water bodies River

71 71 Existing LNAPL Data LNAPL thickness data over time LNAPL saturation limits and vertical extent Characteristics of the source zone Confined or unconfined conditions Lateral stability of LNAPL body time = months 6 months 9 months 1 year 2 year 3 year

72 72 Existing Groundwater Data Dissolved-phase plume maps Characterize source area shape, size and depth Assess if natural attenuation on-going Shrinking/stable groundwater plume = shrinking/stable LNAPL body Shrinking GW = Shrinking LNAPL Stable GW = Stable/Shrinking LNAPL Expanding GW = Stable/Expanding LNAPL?? Initial time Mid-time Later time Groundwater Iso-Concentrations vs. Time

73 73 Existing Soil Data Soil total petroleum hydrocarbon (TPH) data to approximate LNAPL saturation Information from existing boring logs used to characterize LNAPL source zone geometry Stain, odor, organic vapor meter readings S napl TPH b n n(10 6 S napl = NAPL saturation (unitless) ρ b = soil bulk density (g/cm³) TPH = total petroleum hydrocarbons (mg/kg) ρ n = NAPL density (g/cm³) n = porosity ) (Parker et al, 1994)

74 74 Continuous Core/Field Measurements Detailed soil boring logs through the zone of LNAPL are key includes Lithology, water content, odor, soil structure, organic vapor meter readings Oilphillic dyes and ultraviolet (UV) light can aid assessment for presence of LNAPL Laboratory data used to supplement if necessary White Light LNAPL in Yellow UV Light

75 75 Laboratory Analysis Common laboratory methods Soil, groundwater and vapor concentrations Basic soil properties (e.g., grain size, bulk density, distribution, moisture content) Specialized laboratory analysis packages have been developed to support LNAPL evaluations for more complex LCSM Fluid properties Pore fluid saturations and soil properties Soil capillary properties Residual saturation Fingerprinting Specialized soil sampling and handling procedures Preserving core using liquid nitrogen

76 76 Laser Induced Fluorescence (LIF) Different LNAPL products and different soils fluoresce differently Typically used in conjunction with Cone Penetrometer Testing (CPT) Waveform Indicates General Fuel Type (courtesy Dakota Technologies)

77 77 Membrane Interface Probe (MIPs) Carrier gas supply (from MIP controller) Gas return tube (to detector) Permeable membrane Volatile organic contaminants in soil (Photo courtesy Geoprobe) Soil conductivity measurement tip (image courtesy Geoprobe)

78 78 Other Field Tests FLUTe Useful in fractured rock and clays to identify location of LNAPL Flexible color reactive liner that changes color in contact with NAPLs Others

79 Retained Wt % Cumulative Wt % Capillary Pressure Height above water table, ft 79 Estimated/Empirical Values Define data needs based on assessment objectives LNAPL parameters may be estimated Published default or average parameters published for soil textural class determined from lithology and grain size distribution (e.g., API Interactive LNAPL Guide) 10 Empirical databases useful through comparison of basic site soil properties (e.g., API Parameter Database) 10 Grv 8 6 crs Sand size medium fine Silt Clay Particle size, mm Water saturation, % pore volume

80 80 Why Not Just Use Estimated Values? Estimated values versus laboratory measurements Consider accuracy versus cost Is reduction in uncertainty likely to impact management decision? Not all information is needed for every site Typical process for characterization Use estimated values and existing data first Conduct sensitivity analysis Site-specific analyses Tiered data collection More useful at complex sites based on geology, composition, risk, receptors

81 81 Summary of LCSM and LNAPL Characterization LCSM helps to understand LNAPL site conditions, risks, if/why a remedy is needed and supports management decisions Site characterization methods and comprehensiveness are a function of the complexity of the LNAPL site conditions LNAPL distribution is not as simple as we thought Not distributed as a pancake Vertical equilibrium LNAPL saturation is not uniform

82 82 ITRC LNAPL Guidance / Training Workshop LNAPL Conceptual Site Model LNAPL Site Characterization LNAPL Composition and Saturation Q&A Hydraulic recovery evaluation and limits LNAPL management objectives and goals Introduction to LNAPL remedial technologies Q&A

83 83 Three Basic LNAPL Site Scenarios LNAPL sat greater residual 1 LNAPL sat at residual 2 Focus of Training Concern: LNAPL in wells, mobile, migrating Driver: LNAPL saturation Concern: LNAPL in wells, mobile, not migrating Driver: LNAPL composition, saturation LNAPL sat < residual Concern: No LNAPL in wells Driver: LNAPL composition 3

84 84 LNAPL Concerns and Drivers LNAPL Concerns: Explosive hazards Dissolved-phase concentration Vapor-phase concentration Direct contact or ingestion Mobility (spreads and creates new or increased risk) Visible aesthetics LNAPL Driver: Composition Saturation Regulatory Driver: recover to maximum extent practicable State s interpretation?

85 85 LNAPL Composition LNAPL composition is modified by increasing rates of volatilization and dissolution from the LNAPL body phase change from liquid to vapor phase or liquid to dissolved phase. Example technology Vapor extraction in combination with: Air sparging Heating Steam injection

86 86 LNAPL Saturation Reduce LNAPL saturation by bulk LNAPL mass removal via excavation or liquid recovery. LNAPL factors to manipulate: LNAPL gradient skimming, hydraulic recovery, water flood, high-vacuum extraction LNAPL viscosity heating, hot water flood Interfacial tension surfactant/co-solvent flushing Wettability surfactant/co-solvent flushing

87 87 LNAPL Saturation Pore Entry Pressure LNAPL must displace water to enter a soil pore Heating technologies reduce the viscosity of the LNAPL, therefore you need less pressure to move the LNAPL through the water-wet pores Hydraulic pumping can also move LNAPL, but some will remain trapped and won t be removed using hydraulic methods Flow For water wet media Flow

88 88 LNAPL Saturation Viscosity LNAPL viscosity is important when evaluating mobility Different petroleum products have different viscosities Also mixtures of different products Weathering can change LNAPL viscosity Heating the LNAPL body reduces its viscosity and enhances LNAPL recovery

89 89 LNAPL Saturation Capillary Pressure Capillary pressure is highest at LNAPL-air interface and zero at Water-LNAPL interface The higher the capillary pressure, the higher the LNAPL saturation Surfactants help break the interfacial tension that is responsible for capillary rise

90 90 ITRC LNAPL Guidance / Training Workshop LNAPL Conceptual Site Model LNAPL Site Characterization LNAPL Composition and Saturation Q&A Hydraulic recovery evaluation and limits LNAPL management objectives and goals Introduction to LNAPL remedial technologies Q&A

91 91 Potentially Recoverable LNAPL 0 0 LNAPL Potentially Mobile and Recoverable Estimate of Residual Saturation 100 Oil Saturation (% Pore Space) Modeled saturation profile Accuracy model poor when complex geology or varying water table Careful assessment versus actual field conditions critical Residual saturation Variable through profile Higher in saturated zone Available tools include: API LNAPL Distribution and Recovery Model (LDRM) (API 4760) and API Interactive LNAPL Guide

92 92 Why Do We Need to Evaluate LNAPL Recoverability Determine site wide recoverability distribution Can interpolate Tn values to generate isopleths Determine if LNAPL can be recovered In meaningful quantities Sustained Determine where LNAPL can be recovered Assist with LNAPL recovery system management Seasonal fluctuation may dictate that you only recover in certain period for example Determine when LNAPL recovery is complete

93 93 LNAPL Saturation / Transmissivity The zone of highest LNAPL saturation has the highest LNAPL conductivity Low LNAPL saturation results in low LNAPL conductivity Vertical equilibrium (VEQ) conditions in a sand tank LNAPL Transmissivity = Sum T o K o b o Hydraulic recovery rate is proportional to transmissivity for a given technology Well thickness does not dictate relative recoverability More information: ASTM Standard Guide for Estimation of LNAPL Transmissivity at Saturation shark fin Residual LNAPL

94 94 LNAPL Transmissivities and Thicknesses (in a Well) Approximate Gauged Thickness Recovery Rate Based on Baildown Test Data 1 GPM - Water Enhanced Recovery (GPD) LNAPL Transmissivity Location (ft) LNAPL Skimming (GPD) (ft 2 /day) AMR/200-D AMR/ AMR/606-D Key Points: LNAPL thickness is a poor indicator of LNAPL recoverability thickness is too dependent on soil type, heterogeneity, water levels, LNAPL occurrence (confined, perched, unconfined), etc. Transmissivity (via baildown tests, pilot test, or existing recovery data) is a more direct measure of LNAPL recoverability that factors in soil type heterogeneity and water levels. (Atlantic Richfield Corporation, 2008)

95 LNAPL Recovery Rate (gallons per day) Cumulative LNAPL Recovery (gallons) 95 Desktop Methods Extrapolate Existing System Performance LNAPL recovery rate and cumulative recovery Cumulative Recovery Recovery Rate 4,000 3,500 3,000 2,500 2,000 1,500 1, Operating Time (days)

96 96 Desktop Methods Predictive (Analytical and Numerical) Models typically are based on vertical equilibrium (VEQ) model and utilize in well LNAPL thicknesses May be appropriate on more complex sites, may be useful as what-if predictor to evaluate different scenarios Additional site specific data generally required as complexity of model increases Uncertainty in vertical equilibrium, hydrogeologic properties, spatial / vertical heterogeneity, texture / capillary properties, fluid properties, residual saturation, radius of capture / influence, ideal versus real wells Key Point: Many of these lead to overestimating volume and recovery rate, and underestimating time of recovery

97 97 LNAPL Recoverability Summary Transmissivity Most universal (site and condition independent) Estimated with recovery data or field testing on monitoring wells Consistent across soil types (the transmissivity accounts for it) Consistent between recovery technologies Consistent between confined, unconfined or perched conditions Transmissivity provides a consistent measure of recoverability and impacts across different LNAPL plumes within one site or across multiple sites If LNAPL transmissivity high, recoverability is high More information: ASTM Standard Guide for Estimation of LNAPL Transmissivity at

98 98 LNAPL Recoverability Summary LNAPL thickness Inconsistent between hydraulic scenarios (unconfined, confined, etc.) Inconsistent between soil types LNAPL recovery rate (presupposes have a recovery system, and a good one) More robust metric than LNAPL thickness Need recovery system or pilot test data Operational variability and technology differences make it difficult to use across technologies and/or sites Decline curve analysis very useful for long term predictions

99 m Ft above water-lnapl interface m Ft above water-lnapl interface 99 Hydraulic Recovery Limitations MW Pre - Hydraulic Recovery LNAPL Saturation MW Post - Hydraulic Recovery Residual Saturation LNAPL Saturation LNAPL Groundwater

100 Ft above water-lnapl interface Relative GW Concentration 100 LNAPL Hydraulic Recovery: or How Much is Left Behind LNAPL Saturation Relative Time LNAPL Amount No Remediation Benzene Concentration History Post hydraulic Recovery

101 101 Will LNAPL Mass Recovery Abate the Concerns? Utility corridor/ drain Drinking water well LNAPL emergency issues when LNAPL in the ground Vapor accumulation in confined spaces causing explosive conditions Not shown - Direct LNAPL migration to surface water Not shown - Direct LNAPL migration to underground spaces 1 2 3a 2 3b 2 LNAPL Composition LNAPL considerations when LNAPL in the ground (evaluated using standard regulations) Groundwater (dissolved phase) LNAPL to vapor Groundwater to vapor Not shown - Direct skin contact Source: Garg Additional LNAPL considerations when LNAPL in wells (not evaluated using standard regulations) LNAPL potential mobility (offsite migration, e.g. to surface water, under houses) LNAPL in well (aesthetic, reputation, regulatory) LNAPL Saturation

102 102 ITRC LNAPL Guidance / Training Workshop LNAPL Conceptual Site Model LNAPL Site Characterization LNAPL Composition and Saturation Q&A Hydraulic recovery evaluation and limits LNAPL management objectives and goals Introduction to LNAPL remedial technologies Q&A

103 103 Objectives, Goals and Performance Metrics Objective: Goal: Performance Metric: A remedial objective to abate each LNAPL concern. A remediation goal for each LNAPL remedial objective. A performance metric for each remediation goal. Examples Scenario 1 Scenario 2 Objective Goal Metric Stop LNAPL migration off site. (Saturation Objective) Remove LNAPL by skimming to reduce LNAPL head and stop LNAPL migration. No LNAPL appearing in monitor wells on property line. Stop dissolved BTEX plume in groundwater from migrating off site. (Composition Objective) Remove BTEX components in the LNAPL using air sparging & vapor extraction. BTEX less than MCLs in monitor wells at downgradient property line.

104 104 LNAPL Remedial Objectives Risk-based composition objectives Reduce risk-level or hazard Exposure pathway/lnapl specific Non-risk saturation objectives Reduce LNAPL flux Reduce source longevity Reduce LNAPL mass or well thickness Reduce LNAPL transmissivity Stop LNAPL migration Corporate policy liability/risk tolerance Regulatory driver: recover to maximum extent practicable Different states have different interpretation Different remedial strategy needed to target LNAPL composition versus LNAPL saturation objectives. Evaluate whether remedial objectives are best addressed by changing LNAPL composition or reducing LNAPL saturation.

105 105 Control-based Objectives: Do they have a place in LNAPL Management? Can LNAPL safely be left in place after the selected remedial technology has removed to the maximum extent practicable? May be acceptable under certain site conditions and property uses May be acceptable if there is no effective way to remove more LNAPL and no risks remain Can engineered or institutional controls be used? Have LUST sites received NFA letters at sites with LNAPL left in place?

106 106 Remediation Goals Provide the Measure of Performance Remediation Goals: Restate the remedial objective in terms of an LNAPL remedial technology Establish endpoints at which active remediation systems can be shut down Match remediation goals to performance metrics to measure the progress of the remedial technology Site and project specific

107 107 The Importance of Establishing a Long-Term Vision and Goals Start with the end in mind Get stakeholders on the same page Get stakeholders to agree on what is realistically achievable Discuss remedial objectives and remediation goals Long-term vision may be revised if goals are later found not to be achievable EPA, March 2005, A Decision-Making Framework for Cleanup of Sites Impacted with LNAPL (EPA 542-R )

108 108 Pioneering: Examples of Setting Objectives and Goals ITRC: Evaluating LNAPL Remedial Technologies for Achieving Project Goals (December 2009) ITRC: Evaluating Natural Source Zone Depletion at Sites with LNAPL (April 2009) Risk-Based NAPL Management, TCEQ RG-366/ TRRP-32 (2008) Standard Guide for Development of Conceptual Site Models and Remediation Strategies for Light Nonaqueous-Phase Liquids Release to the Subsurface, ASTM E (2007) A Decision-Making Framework for Cleanup of Sites Impacted with Light Non-Aqueous Phase Liquids (LNAPL), USEPA OSWER 542-R (2005) ASTM American Society for Testing and Materials OSWER Office of Solid Waste and Emergency Response TCEQ Texas Commission on Environmental Quality

109 109 Summary LNAPL behavior in the subsurface is more complex than previously thought Develop an LNAPL CSM LNAPL characterization should be commensurate with the LNAPL site complexity and risks LNAPL recovery addresses mobility potential recovery is limited LNAPL concerns are saturation or composition driven Match LNAPL concerns with remediation objectives

110 110 ITRC LNAPL Guidance / Training Workshop LNAPL Conceptual Site Model LNAPL Site Characterization LNAPL Composition and Saturation Q&A Hydraulic recovery evaluation and limits LNAPL management objectives and goals Introduction to LNAPL remedial technologies Q&A

111 Technology Group Selection 111 Choosing a Remedial Technology You now have an understanding of your site, You know if the LNAPL is migrating You know what is recoverable (hydraulically) You know what LNAPL composition fraction to target You have objectives and goals in mind What physical parameters will a remedial technology manipulate? Mobility Saturation Composition

112 112 LNAPL Remedial Options SOURCE Pathway RECEPTOR Removal/Treatment: remediate source Containment: eliminate pathway Institutional Controls: control exposure activity Natural Source Zone Depletion confirm stable / diminishing condition KEY POINT: May include active or passive technologies, engineering or institutional controls, or a combination

113 113 LNAPL Remediation Technology Groups

114 Technology Groups 114 LNAPL Remediation Technology Groups Learning Objective: Understand: What the LNAPL remediation technology groups are, Why they ve been grouped, and How site objectives influence the selection of a technology group Phase Change?

115 Technology Groups 115 Many Technologies Available (Guidance Table 5-1, p. 29) 17 LNAPL remedial technologies addressed: Excavation Physical containment In-situ soil mixing Natural source zone depletion (NSZD) Air sparging/soil vapor extraction (AS/SVE) LNAPL skimming Bioslurping/EFR Dual pump liquid extraction Multi-phase extraction, dual pump Multi-phase extraction, single pump Water/hot water flooding In situ chemical oxidation Surfactant- enhanced subsurface remediation Cosolvent flushing Steam/hot-air injection Radio frequency heating Three and six-phase electrical resistance heating

116 116 Typical Remedial Objectives (Review) Terminate LNAPL Migration Reduce LNAPL Saturation (MEP) Above residual range Within residual range Abate concentrations of concern Groundwater Soil vapor Abate Aesthetic concern LNAPL Odor

117 Technology Groups 117 Technology Groups Phase Change Mass Control Mass Recovery Phase Change Mass Recovery Mass Control Key Point: Simplify the selection of technology

118 Technology Groups 118 Linkage Between Remediation Objectives and Technology Groups Containment objective LNAPL mass control Stop LNAPL migration by containing LNAPL Saturation objective LNAPL mass recovery Reduce LNAPL saturation by recovering LNAPL Composition objective LNAPL phase change Change LNAPL characteristics by phase change

119 119 The Name Game & General Technology Group Applicability Csat Phase Change Mass Control, Mass Recovery, Phase Change LNAPL LNAPL present, but cannot flow into wells LNAPL can flow into wells S r > S r >S r = Mobile Terminology Changes Csat, Residual, Mobile, Migrating

120 LNAPL Mass Control Concept 120 LNAPL Mass Control - Think Barriers Uncontrolled Vapor Barrier Controlled LNAPL Barrier Groundwater Barrier PC Key Point: Mass control technologies block LNAPL from affecting the surrounding soil, groundwater and/or surface MR MC

121 LNAPL Mass Recovery Concept 121 LNAPL Mass Recovery PC Think removal as bulk liquid MR MC

122 LNAPL Mass Recovery Concept 122 Saturation Objective LNAPL Concern LNAPL Remedial Objective Remediation Goals Migration or Mobility Saturation Objective Reduce LNAPL Mobility Recover LNAPL to Maximum Extent Practicable Key Point: Reduce mobility and potential for migration by changing LNAPL saturation through mass recovery

123 LNAPL Mass Recovery Concept 123 LNAPL Saturation Reduce LNAPL saturation by bulk LNAPL mass removal via fluid flow recovery or excavation LNAPL fluid factors to manipulate: LNAPL gradient (remember Darcy s Law*) skimming, dual pump liquid extraction, water flood, vacuum enhanced fluid recovery LNAPL viscosity (remember LNAPL conductivity*) heating, hot water flood Interfacial tension (remember capillary pressure*) surfactant/cosolvent flushing *Session 3, Parts 1 & 2

124 LNAPL Phase Change 124 LNAPL Phase Change MR MC PC

125 LNAPL Phase Change 125 Composition Objective LNAPL Concern LNAPL Remedial Objective Remediation Goals Risk via Vapors or Dissolved Plume Composition Objective Deplete volatile or soluble constituent concentration in LNAPL Key Point: Reduce soil vapor or groundwater risk by removing risk-driving constituent(s) from LNAPL

126 LNAPL Phase Change 126 LNAPL Composition Modified by increasing rates of volatilization and dissolution from LNAPL body phase change from liquid to vapor phase or liquid to dissolved phase Example technologies Soil vapor extraction, or in combination: Air sparging Heating Steam injection Enhanced aerobic biodegradation Enhanced anaerobic biodegradation In-situ chemical oxidation

127 Saturation vs Composition Benzene Equilibrium Groundwater Concentration Benzene (mg/l) Equilibrium Groundwater Concentration (mg/l) 127 Contrast Between Composition And Saturation Objectives 50 % Reduction Molar % B Reduces Persistence 50 % Reduction in So LNAPL LNAPL Saturation Saturation A Reduces Concentration C A B C Reduced saturation (less LNAPL) Changed composition Tech Reg Figure 3-2 Key Point: Abatement of dissolved or vapor concentration is dependent on change in composition (mole fraction) and not saturation (unless almost all LNAPL is removed)

128 Remediation Technology Group 128 Technology Grouping Overlap Phase Change Mass Recovery Mass Control

129 129 Sequenced Technology Deployment - Treatment Train Csat Phase Change Mass Control, Mass Recovery, Phase Change LNAPL LNAPL present, but cannot flow into wells LNAPL can flow into wells S r > S r >S r = Mobile

130 130 Treatment Trains Good When planned with goals & metrics for transition Orderly implementation Bad Unplanned, lack specific goals & metrics for transition Throwing more technologies at the problem

131 131 Knowledge Check What are the LNAPL technology groups? Mass control, mass recovery, and phase change What general technology groups would you use for the following concerns and objectives? Concern: LNAPL sheen on a surface water body Objective: stop LNAPL migration Mass control or mass recovery Concern: LNAPL causing vapor intrusion risk Objective: reduce or eliminate VI risk Mass control or phase change

132 Technology Groups 132 Many Technologies Available (Guidance Table 5-1, p. 29) 17 LNAPL remedial technologies addressed: Excavation Physical containment In-situ soil mixing Natural source zone depletion (NSZD) Air sparging/soil vapor extraction (AS/SVE) LNAPL skimming Bioslurping/EFR Dual pump liquid extraction Multi-phase extraction, dual pump Multi-phase extraction, single pump Water/hot water flooding In situ chemical oxidation Surfactant- enhanced subsurface remediation Cosolvent flushing Steam/hot-air injection Radio frequency heating Three and six-phase electrical resistance heating

133 133 LNAPL technology description and primary mechanism for remediation LNAPL mass control Physical containment (barrier wall, drain) Stabilization (in situ soil mixing) LNAPL mass recovery Excavation LNAPL skimming Dual pump liquid extraction Multi-phase extraction (MPE) Water flooding (inc. hot water flooding) ITRC Tech Guidance Section 5

134 134 LNAPL technology description and primary mechanism for remediation LNAPL phase change remediation Natural source zone depletion (NSZD) - See ITRC LNAPL-1 Air sparging/soil vapor extraction (AS/SVE) Bioslurping/enhanced fluid recovery In-situ chemical oxidation LNAPL phase change remediation and mass recovery Surfactant-enhanced subsurface remediation Co-solvent flushing Steam/hot-air injection Radio frequency, 3- & 6-phase electrical resistance heating ITRC Tech Guidance Section 5

135 135 LNAPL Mass Control Technologies Mass Control Mass Recovery Phase Change

136 LNAPL Mass Control 136 LNAPL Mass Control Learning Objectives: Understand the differences between individual mass control technologies and how to measure (demonstrate) their success How to Stop LNAPL Migration?

137 LNAPL Mass Control 137 Mass Control Technologies Physical containment Hydraulic containment Soil stabilization

138 LNAPL Mass Control 138 Physical Containment (Table A-2 Series, p. A-4 A-6) Barrier wall; Vapor barrier/cap Advantages Short time frame to implement Disadvantages Long time frame to maintain Large carbon footprint (wall) MR PC MC Engineering Grain size distribution Depth below grade, access Unsaturated vs. saturated zone Depth to water table Chemical compatibility with LNAPL

139 139 Barrier Wall Key site conditions Grain size distribution Depth below grade, access Unsaturated vs. saturated zone Depth to water table Advantages controls LNAPL and dissolved plume mobility Disadvantages long time frame monitoring, potentially costly remedial approach

140 LNAPL Mass Control 140 Hydraulic Containment (Table A-2 Series, p. A-4 A-6) Isolates LNAPL as a source to vapor or groundwater Approaches Groundwater pump and treat Venting/subslab depressurization (SVE to intercept vapor) Advantages Short time frame to implement Disadvantages Long time frame of maintenance Engineering Radius of capture Overcome building depressurization MR PC MC

141 LNAPL Mass Control 141 In-Situ Soil Mixing And Stabilization (Table A-3 Series, p. A-7 A-9) Isolates LNAPL as a source to vapor or groundwater Additives to stabilize LNAPL Advantages Short time frame to implement LNAPL left in place Disadvantages High energy requirements (carbon footprint) Disruptive to other site activities Engineering Soil type Additive compatibility with LNAPL MR PC MC

142 LNAPL Mass Control 142 Metrics For Mass Control Performance No first LNAPL occurrence downgradient Absence of new accumulations in wells Absence of sheens on adjacent surface water No first constituent occurrence at unacceptable levels downgradient (groundwater or soil vapor) Dissolved-phase regulatory concentration standard met at compliance point Reduced dissolved-phase concentrations downgradient of barrier

143 143 Knowledge Check In general, what is a major advantage of LNAPL mass control technologies? Short time frame to implement Disadvantage? Long maintenance timeframe and large carbon footprint (wall), site disruption

144 144 Knowledge Check Is mass control measurable? How? Yes. Various ways, direct - no first occurrence of LNAPL, indirect LNAPL volatile or dissolved constituent monitoring. Why use mass control if an LNAPL body isn t migrating? Typically wouldn t, but can be proactive insurance against future changed conditions; as an exposure barrier.

145 145 LNAPL Mass Recovery Technologies Mass Control Mass Recovery Phase Change

146 LNAPL Mass Recovery 146 Mass Recovery Technologies Learning Objectives: Know the differences between mass recovery technologies Know the differences between the various simple hydraulic recovery methods Dual-Pump Liquid Extraction?

147 LNAPL Mass Recovery 147 Mass Recovery Technologies (Simple) Hydraulic Recovery Skimming Dual-pump liquid extraction (DPLE) Bioslurping / enhanced fluid recovery (EFR) Multiphase extraction (MPE) single pump Multiphase extraction (MPE) dual pump Enhanced Hydraulic Recovery (Hot) Water flooding Surfactant-enhanced subsurface remediation (SESR) Cosolvent flushing Excavation

148 LNAPL Mass Recovery Modified from USACE 1999 MR MC 148 Skimming (Table A-6 Series, p. A-17 A-19) Recover only LNAPL (incidental water) Induce LNAPL flow to well by creating gradient in LNAPL only Applicable to broad range of geologic conditions Applicable to broad range of LNAPL types LNAPL Discharge Line LNAPL Oil (LNAPL)/ Water Separator LNAPL PC

149 LNAPL Mass Recovery 149 Dual-Pump Liquid Extraction (DPLE) (Table A-8 Series, p. A-24 A-27) Extract LNAPL and groundwater Induce LNAPL flow into extraction well by creating gradients in LNAPL and groundwater Expose Submerged LNAPL Control water table fluctuations Applicable to range of geologic conditions Applicable to broad range of LNAPL types Not applicable to perched LNAPL Water Discharge Water Pump Modified from USACE 1999 LNAPL Discharge LNAPL Pump Groundwater PC MR MC

150 LNAPL Mass Recovery 150 Bioslurping / Enhanced Fluid Recovery (EFR) (Table A-7 Series, p. A-20 A-23) Extract LNAPL and vapor (vapor enhanced fluid recovery) Induce LNAPL flow into extraction well by creating gradients in LNAPL and soil vapor Increase aerobic biodegradation Better suited to higher conductivity soils LNAPL Not suited to confined or submerged LNAPL Bioventing LNAPL Vacuum Pump Gas Discharge/ Treatment Slurp Tube Air Gas/Liquid Separator MR LNAPL/ Water Separator PC MC Modified from USACE 1999

151 LNAPL Mass Recovery MR MC 151 MPE Single Pump (Table A-10 Series, p. A-33 A-36) Extract LNAPL, groundwater, and vapor Total Fluids Discharge Induce LNAPL flow into extraction well by creating gradients in LNAPL, groundwater, and soil vapor Soil Vapor Soil Vapor Discharge Typically Higher Vacuum LNAPL Better suited to lower conductivity soils LNAPL PC Groundwater Total Fluids Extraction Pump

152 LNAPL Mass Recovery MR MC 152 MPE Dual Pump (Table A-9 Series, p. A-28 A-32) Extract LNAPL, groundwater, and vapor Induce LNAPL flow into extraction well by creating gradients in LNAPL, groundwater, and soil vapor Better suited to higher conductivity soils LNAPL LNAPL Discharge Soil Vapor LNAPL PC Soil Vapor Discharge Groundwater Discharge LNAPL Pump Groundwater Groundwater Extraction Pump

153 LNAPL Mass Recovery 153 Hydraulic Recovery Technology Pros Technology Advantage Skimming DPLE EFR/Bioslurp MPE (Single Pump) MPE (Dual Pump) LNAPL-only waste stream Lowest per-well cost Increased radius of capture (ROC) Shorter time frame than skimming In-situ biodegradation Low per-well cost Largest ROC Shortest time frame Largest ROC / Shortest time frame Separate waste streams simplifies treatment

154 LNAPL Mass Recovery 154 Hydraulic Recovery Technology Cons Technology Disadvantage Skimming DPLE EFR/Bioslurp MPE (Single Pump) MPE (Dual Pump) Smallest radius of capture Longest time frame Waste water or combined water/lnapl disposal Single LNAPL/vapor/water waste stream Long time frame Treatment of single fluid waste stream Highest per-well cost

155 LNAPL Mass Recovery 155 Hydraulic Recovery Technology Engineering Technology Skimming DPLE EFR/Bioslurp MPE (Single Pump) MPE (Dual Pump) Parameters for Design LNAPL radius of capture (ROC) Groundwater flow vs. drawdown and ROI Vacuum ROI, aeration and pore volume exchange Vacuum ROI Groundwater flow vs. drawdown and ROI Vacuum ROI Groundwater flow vs. drawdown and ROI Note: ROI means the distribution of vacuum or drawdown with radius, not just the radius at which 0.1 H2O vacuum or 0.01 drawdown is observed or predicted

156 LNAPL Mass Recovery 156 Hydraulic Recovery Methods Groundwater Extraction Vacuum Enhancement

157 LNAPL Mass Recovery 157 Hydraulic Recovery Remedial Time Frame LNAPL Removed Comparing remedial time frame for a single well system R y T MPE T DPLE Time T Skim

158 LNAPL Mass Recovery 158 LNAPL Transmissivity and Hydraulic Recovery Technologies Well Density Comparing well density to achieve comparable recovery LNAPL Transmissivity (ft 2 /day)

159 159 Excavation LNAPL Mass Recovery Key site conditions Depth below grade, depth to water table, access Unsaturated vs. saturated zone Advantages include very short timeframe, complete mass removal where accessible Disadvantages include access restrictions, cost and de-watering below water table Sustainability may also be an issue (safety, carbon footprint)

160 160 Six Phase Heating LNAPL Mass Recovery and Phase Change Elev. (m) Elev. (m) Key LNAPL conditions Saturation Composition Volatility LNAPL interfacial tensions are reduced resulting in Solubility increased LNAPL mass recovery, LNAPL constituents volatilized and removed through vapor extraction Viscosity A Interfacial tension Section B-B B B A Section A-A Advantage enhanced LNAPL mass y-distance (m) recovery and potentially faster remediation Disadvantages are greater complexity, increased residuals and higher energy cost overall sustainability? x-distance (m) CompFlow Simulation Extraction with heating, 130 days Source I. Hers, Golder o C

161 161 Knowledge Check What simple mass recovery technology would you select and why for this LNAPL situation?

162 162 Knowledge Check What simple mass recovery technology would you select and why for this LNAPL situation? DPLE LNAPL is distributed below the water table. By pulling down the water table, water saturations will reduce in the formation across the LNAPL distribution, easing LNAPL flow out of the formation toward the recovery well

163 163 Knowledge Check For a recent gasoline release that has impacted the water table in fine sand, what simple mass recovery technology would you select and why?

164 164 Knowledge Check For a recent gasoline release that has impacted the water table in fine sand, what simple mass recovery technology would you select and why? LNAPL skimming since recent smearing minimal, saturations high can induce LNAPL gradient and minimize smearing

165 165 Natural Source Zone Depletion Mass Control Mass Recovery Phase Change NSZD

166 NSZD 166 Natural Source Zone Depletion (NSZD) Learning Objective: Know what Natural Source Zone Depletion is Know how it can be demonstrated to reduce LNAPL mass Know whether it is really a technology NSZD??? Hunh? It just went away..

167 167 Natural Source Zone Depletion (NSZD) Loss of mass from the LNAPL body due to natural processes in the subsurface The two primary natural LNAPL mass loss processes in the subsurface are volatilization/dissolution and biodegradation This occurs whether applying a technology or not Recharge Mobile or Residual LNAPL Oxygen Transport Volatilization & Biodegradation Evaluating Natural Source Zone Depletion at Sites with LNAPL (LNAPL-1, 2009) Groundwater Flow Dissolution & Biodegradation

168 NSZD MR MC 168 In Groundwater Dissolution and biodegradation of LNAPL in groundwater Submerged Source Zone PC

169 NSZD MR MC 169 In The Vadose Zone Volatilization and Biodegradation of LNAPL in Vadose Zone Exposed Source Zone Methanogenesis PC

170 NSZD - Demonstration 170 How Is NSZD Evaluated? NSZD DEMONSTRATIONS Qualitative Evaluation Quantitative Analysis Predictive Modeling

171 NSZD - Demonstration 171 Evaluating LNAPL Dissolution NSZD Evaluations Observe TPH Concentrations Upgradient Downgradient TPH TPH SOURCE ZONE TPH

172 NSZD - Demonstration 172 Evaluating LNAPL Biodegradation In Groundwater NSZD Evaluations Observe Groundwater Chemistry Upgradient TPH O 2 NO 3 SO 4 Fe 2+ Mn 2+ CH 4 SOURCE ZONE Downgradient TPH O 2 NO 3 SO 4 Fe 2+ Mn 2+ CH 4

173 NSZD - Demonstration 173 Submerged Source Zone Case Study Submerged Zone NSZD Rate 2.2 gallons/acre/year

174 NSZD - Demonstration 174 Evaluating LNAPL Volatilization & Biodegradation In Vadose Zone NSZD Evaluations Soil Vapor Profile Lines of Evidence TPHv

175 NSZD - Demonstration 175 Exposed Source Zone Case Study Nested soil vapor probes Assumed soil diffusivity NSZD Rate 1,800 gallons/acre/year

176 NSZD - Demonstration 176 Exposed Source Zone Case Study Nested soil vapor probes Push-pull tracer test to determine soil diffusivity (Johnson et al., 1998) NSZD gallons/acre/yr NSZD gallons/acre/yr NSZD gallons/acre/yr NSZD gallons/acre/yr NSZD gallons/acre/yr NSZD gallons/acre/yr NSZD Rate 600 gallons/acre/year

177 NSZD - Demonstration 177 Recent Advances Vadose Zone CO 2 Flux UBC LI-COR CO 2 flux chamber CSU passive CO 2 traps Multi-level probes & pressure xducers

178 NSZD - Demonstration 178 Recent Advances Temperature Profiles C 8 H O 2 8 CO H 2 O + HEAT 28.7 kcal/gallon Gasoline (1 m 3 from ice water to pool water)

179 NSZD - Demonstration 179 Case Study LI-COR CO 2 Flux (µmol/m 2 /sec) Groundwater Temperature ( C vs ft below water table)

180 NSZD - Demonstration 180 Metrics of NSZD Groundwater geochemistry Soil gas profiles CO 2 flux Temperature profile Composition change Soil vapor Groundwater LNAPL (soil) Rate of LNAPL depletion and composition change

181 181 Knowledge Check What technology group does NSZD fit into and why? Phase change because it relies on LNAPL volatilization and dissolution. Where does the LNAPL go (what happens to deplete the LNAPL)? LNAPL constituents volatilize and dissolve from the LNAPL, and then may be biodegraded from the vapor or dissolved phases Is this really a technology? It s a natural phenomenon that, like an active technology, can be measured and evaluated to assess effectiveness

182 182 Natural Source Zone Depletion (NSZD) LNAPL Phase Change Key LNAPL conditions Composition Volatility Solubility Biodegradation Electron Acceptor Flux Biodegradation Oxygen Transport Volatilization Mobile or Residual LNAPL Dissolution and Biodegradation Groundwater Flow Electron Acceptor Depletion Low intensity remedial solution Advantages include no disruption, low carbon footprint Disadvantages include very long time frame, may not meet saturation (mobility) or composition objective ITRC s Evaluating Natural Source Zone Depletion at Sites with LNAPL (LNAPL-1, 2009)

183 183 LNAPL Remediation Technology Selection

184 Introduction 184 ITRC LNAPL Management Strategy LNAPL Assessment / LCSM What do you have? Set LNAPL Remediation Objectives What needs to be done? Select Remediation Technology to Achieve Objectives How to address it? Deploy Remedial Technology and Monitor Performance

185 Basics 185 Tech Guidance Process Flow Diagram Sections 3, 4, and 6.1 LNAPL characterization Develop LCSM IBT-1, 2 Identify LNAPL concerns Sections 3 & 4 Section 6 Identify LNAPL objectives, goals, site/lnapl condition to screen technologies (Screening Step 1: Table 6-1) Covered Screen technologies: Geology factors (Screening Step 2: Tables A) Screen technologies: Evaluation factors (Screening Step 3: Tables B) Section 7 Minimum data requirements and critical technology Group (Tables C) Section 8 Establish goals and metrics and implement LNAPL remediation Monitor/assess LNAPL remediation performance Demonstrate goals met ITRC Tech Guidance p. 28

186 Basics 186 Tech Guidance Process Flow Diagram Sections 6.2, 7, and 8 LNAPL characterization Develop LCSM IBT-1, 2 Identify LNAPL concerns Sections 3 & 4 Section 6 Identify LNAPL objectives, goals, site/lnapl condition to screen technologies (Screening Step 1: Table 6-1) Screen technologies: Geology factors (Screening Step 2: Tables A) Screen technologies: Evaluation factors (Screening Step 3: Tables B) Section 7 You are here Minimum data requirements and critical technology Group (Tables C) Section 8 Establish goals and metrics and implement LNAPL remediation Monitor/assess LNAPL remediation performance Demonstrate goals met ITRC Tech Guidance p. 28

187 Basics 187 Process Flow You May Loop Back LNAPL characterization Develop LCSM IBT-1, 2 Identify LNAPL concerns Sections 3 & 4 Passive LNAPL Management Section 6 Identify LNAPL objectives, goals, versus site/lnapl condition to screen technologies Active Technology (Screening Step Selection? 1: Table 6-1) Screen technologies: Geology factors (Screening Step 2: Tables A) Screen technologies: Evaluation factors (Screening Step 3: Tables B) You are here You may have to collect additional data or further Section 7 evaluate objectives, goals, or Minimum data requirements and critical technology Group (Tables C) technologies as needed. Make sure the data will be used. Section 8 Establish goals and metrics and implement LNAPL remediation Monitor/assess LNAPL remediation performance Demonstrate goals met ITRC Tech Guidance p. 28

188 Introduction 188 LNAPL Remediation Technology Selection Learning Objectives: How to use the Guidance Doc Screening Tool How the Guidance Doc can be applied to a real site Let s test drive the Guidance Doc!

189 189 Reminder: Guidance Doc Technology Series Tables Guidance Doc Appendix A (pp. A-1 to A-64) A group of tables (Tables A, B, C) for each of the 17 LNAPL remediation technologies A-series general technology information B-series evaluation factors C-series technical implementation considerations For a technology, the A, B and C tables are presented on consecutive pages Key literature references presented in the tables Key Point: Appendix A presents typical technology applicability to site conditions as concluded by the LNAPL Team. This doesn t mean you can t apply the technology in a setting different.

190 Stepped Process 190 Section 6 Preliminary LNAPL Remedial Technology Screening The preliminary screening process has two-steps: Step 1 Starting at the first column on Table 6-1 (p. 36): Select the applicable LNAPL Remedial Objectives Select the preferred LNAPL Remediation Goals Select the Technology Group(s) Identify the Performance Metrics This Step identifies a subset of possible LNAPL technologies Step 2 - Screen the technologies using the Geologic factors portion of the A-series technologies tables provided in Appendix A (e.g., soil type) This Step may eliminate technologies that rely on critical geologic factors that are not present at the site.

191 Section 6, Step Section 6 Step 1 Table 6-1: Identify Objectives, Goals, Technology Group And Metrics To Address LNAPL Concerns

192 Section 6, Step Section 6 Step 2 Table 6-1. Preliminary Screening Matrix LNAPL Remedial Objective Reduce LNAPL when LNAPL is within residual saturation range LNAPL Remedial Goal Technology Group Further abate LNAPL beyond LNAPL mass hydraulic or recovery pneumatic recovery Example Performance Metrics Limits of technology Asymptotic mass removal Cost of mass removal Soil concentration at regulatory standard LNAPL Technology and LNAPL / Site Conditions Cosolvent flushing SESR C, S, LV, LS, HV, HS AS/SVE C, U, S, HV, HS ISCO C, U**, S, HV, HS RFH F, U, S, LV, LS, HV, HS 3- and 6-phase heating Steam/hot-air injection NSZD F, C, U, S, HV, HS C, S, LV, LS, HV, HS F, U, S, LV, LS, HV, HS C, U, S, LV, LS, HV, HS A grouping of technologies can be further reduced based on LNAPL type LV- low Volatility, HV-High Volatility, HS-High Solubility, LS-Low Solubility Geologic indicators F-Fine grained soils, C-Coarse grained soils, U-unsaturated zone, S-Saturated zone

193 Case Study 193 Case Study Example: Introduction Service Station Gasoline with some diesel LNAPL body ~700 by 200 Water table ~30 bgs Medium sands Overlying bedrock at ~40 bgs LNAPL in monitoring wells (generally <1ft) BTEX and MTBE groundwater plumes Possible vapor intrusion/explosive vapor concerns

194 Case Study 194 Case Study Example: Map LNAPL

195 Case Study 195 Case Study Example: Cross Section LNAPL High Water Table

196 Case Study 196 Case Study Example: LNAPL Concern Migration Possible seeps from soil through cracks into storm drain LNAPL near neighbors buildings Dissolved and vapor plume Dissolved plume (but no expansion) Vapor plume near neighboring property

197 Case Study, Step Case Study Example: Guidance Doc Table 6-1 (Step 1) Table 6-1. Preliminary Screening Matrix LNAPL Remedial Objective LNAPL Remedial Goal Further abate Reduce LNAPL LNAPL beyond when LNAPL is hydraulic or within residual pneumatic saturation range recovery Technology Group LNAPL mass recovery Example Performance Metrics Limits of technology Asymptotic mass removal Cost of mass removal Soil concentration at regulatory standard LNAPL Technology and LNAPL/Site Conditions Cosolvent flushing SESR C, S, LV, LS, HV, HS AS/SVE C, U, S, HV, HS ISCO C, U**, S, HV, HS RFH F, U, S, LV, LS, HV, HS 3- and 6-phase heating Steam/hot-air injection NSZD F, C, U, S, HV, HS C, S, LV, LS, HV, HS F, U, S, LV, LS, HV, HS C, U, S, LV, LS, HV, HS Screen out RFH and Three- and Six-phase heating Geologic indicators F-Fine grained soils

198 Basics 198 Starting with Section 6: Step 2 LNAPL characterization Develop LCSM IBT-1, 2 Identify LNAPL concerns Sections 3 & 4 Section 6 Identify LNAPL objectives, goals, site/lnapl condition to screen technologies (Screening Step 1: Table 6-1) Screen technologies: Geology factors (Screening Step 2: Tables A) Now This Screen technologies: Evaluation factors (Screening Step 3: Tables B) Section 7 Minimum data requirements and critical technology Group (Tables C) Section 8 Establish goals and metrics and implement LNAPL remediation Monitor/assess LNAPL remediation performance Demonstrate goals met ITRC Tech Guidance p. 28

199 Case Study, Step Case Study Example: A-Series Tables Table A-15A Geologic Factors

200 Case Study, Step Case Study Example: A-Series Tables Site Geologic factors Moderate permeability Unsaturated and saturated zone impacts (typical smear zone) Generally homogeneous soil profile Geologic factors Saturated zone Excerpt from Table A-15.A. Steam/hot-air injection Permeability Steam injection is effective only in relatively permeable materials where there is less resistance to flow; also, more effective in confined LNAPL settings where a lowpermeability layer can help to control steam distribution.

201 Case Study, Step Case Study Example: Technology Screening Cosolvent flushing SESR AS/SVE ISCO RFH C, S, LV, LS, HV, HS C, U, S, HV, HS C, U**, S, HV, HS F, U, S, LV, LS, HV, HS 3- and 6-phase heating Steam/hot-air injection NSZD F, C, U, S, HV, HS C, S, LV, LS, HV, HS F, U, S, LV, LS, HV, HS C, U, S, LV, LS, HV, HS

202 Basics 202 Section 7 In The Process LNAPL characterization Develop LCSM IBT-1, 2 Identify LNAPL concerns Sections 3 & 4 Section 6 Identify LNAPL objectives, goals, site/lnapl condition to screen technologies (Screening Step 1: Table 6-1) Screen technologies: Geology factors (Screening Step 2: Tables A) Screen technologies: Evaluation factors (Screening Step 3: Tables B) Section 7 Now This Minimum data requirements and critical technology Group (Tables C) Section 8 Establish goals and metrics and implement LNAPL remediation Monitor/assess LNAPL remediation performance Demonstrate goals met ITRC Tech Guidance p. 28

203 203 Reminder: Guidance Doc Technology Series Tables Guidance Doc Appendix A (pp. A-1 to A-64) A group of tables (Tables A, B, C) for each of the 17 LNAPL remediation technologies A-series general technology information B-series evaluation factors C-series technical implementation considerations For a technology, the A, B and C tables are presented on consecutive pages Key literature references presented in the tables Key Point: Appendix A presents typical technology applicability to site conditions as concluded by the LNAPL Team. This doesn t mean you can t apply the technology in a setting different.

204 Section 7, Step Section 7 LNAPL Technology Evaluation for the Short List Further evaluate technologies from Section 6 if more than one technology or reevaluate goals Review Table 7-1 to understand evaluation factors (p. 42) Select and rank top 5 factors in importance for site considerations Review B-series tables in Appendix A

205 Section 7, Step Section 7 Guidance Doc Table 7-1 Evaluation Factors (p. 42)

206 Section 7, Step Section 7 Guidance Doc Table 7-1 Evaluation Factors (p. 42) Remedial time frame Safety Waste stream generation and management Community concerns Carbon footprint/energy requirements Site restrictions LNAPL body size Cost Other Each factor is Defined and its Impact is listed

207 Case Study, Section 7 Application 207 Case Study Example: Evaluation Factors Safety Site is adjacent to freeway and a freeway entrance ramp Waste Stream Management Cannot handle large waste water volume Remedial Time Frame Not critical but must show progress LNAPL body size Treating moderate sized area ~200 by 200

208 Case Study, Section 7 Application 208 Case Study Example: Evaluation Factors Cosolvent (A-14.B) SESR (A-13.B) AS/SVE (A-5.B) ISCO (A-12.B) NSZD (A-4.B) Safety Moderate Moderate Low Moderate to High Low Waste Management (Water) High High Low Low Low Remedial Time Frame Very Low to Low Very Low to Low Low to Moderate Very Low to Low High to Very High LNAPL Body Size Moderate Moderate Moderate Moderate High

209 Section Case Study Example: Technology Screening Cosolvent flushing SESR AS/SVE ISCO RFH C, S, LV, LS, HV, HS C, U, S, HV, HS C, U**, S, HV, HS F, U, S, LV, LS, HV, HS 3- and 6-phase heating Steam/hot-air injection NSZD F, C, U, S, HV, HS C, S, LV, LS, HV, HS F, U, S, LV, LS, HV, HS C, U, S, LV, LS, HV, HS

210 Basics 210 Section 8 In The Process LNAPL characterization Develop LCSM IBT-1, 2 Identify LNAPL concerns Sections 3 & 4 Section 6 Identify LNAPL objectives, goals, site/lnapl condition to screen technologies (Screening Step 1: Table 6-1) Screen technologies: Geology factors (Screening Step 2: Tables A) Screen technologies: Evaluation factors (Screening Step 3: Tables B) Section 7 Minimum data requirements and critical technology Group (Tables C) Now This Section 8 Establish goals and metrics and implement LNAPL remediation Monitor/assess LNAPL remediation performance Demonstrate goals met ITRC Tech Guidance p. 28

211 Section Section 8 Minimum Data Requirements and Critical Considerations For Technology Evaluation Table 8-1 is a summary table of the critical information (p ) Further evaluate considering bench or pilot test or field deployment information Use the C-series tables in Appendix A for the technologies remaining from Section 7 (e.g., A-5.C, p. A-15) If no technology can be determined, reevaluate the objectives or goals

212 Section 7, Step Section 8 Critical Criteria Guidance Doc Table 8-1 (p )

213 213 Case Study Example: C- Series Tables

214 214 Section 8 Critical Criteria Guidance Doc Table 8-1 (p ) LNAPL Technology (Appendix A Table with further details) Site Specific Data for Technology Evaluation Minimum data requirements Bench Scale Testing Pilot Testing Full-Scale Design ISCO (A-12.C) K gw, LNAPL c, homogeneity Soil cores for column test, COCs, LNAPL c ROI ROI, soil oxidant demand, homogeneity Photos: ARCADIS

215 Case Study Section 8 Application 215 Case Study Example: Technology Screening Cosolvent flushing SESR AS/SVE ISCO RFH C, S, LV, LS, HV, HS C, U, S, HV, HS C, U**, S, HV, HS F, U, S, LV, LS, HV, HS 3- and 6-phase heating Steam/hot-air injection NSZD F, C, U, S, HV, HS C, S, LV, LS, HV, HS F, U, S, LV, LS, HV, HS C, U, S, LV, LS, HV, HS

216 Case Study Section 8 Application 216 Case Study Example: AS/SVE Selected