1 Session 5 LNAPL Remediation Technology Overview Part

1 Session 5 – LNAPL Remediation Technology Overview Part 1: Technology Groups, NSZD, Mass Control, and Mass Recovery Technologies

2 Introduction ITRC LNAPL Management Strategy LNAPL Assessment LCSM What do you have? Identify LNAPL Concerns and Set LNAPL Remedial Objectives What needs to be done? Select Remediation Technology to Achieve Remedial Objectives How to do it? Install Remedial Technology and Monitor Performance

3 Tech Reg Process Flow Diagram (Figure 5 -1) LNAPL characterization Develop LCSM IBT-1, 2 Section 3 Identify LNAPL concerns Section 6 Introduction 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) You are here 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

4 Learning Objectives for the LNAPL Remediation Technology Overview Session u Understand what LNAPL Remediation Technologies are appropriate for your case and how to measure their effectiveness

5 LNAPL Remediation Technology Groups

6 LNAPL Remediation Technology Groups u Learning Objective: Understand: Technology Groups • 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?

7 Many Technologies Available (Tech Reg Table 5 -1, p. 29) 17 LNAPL remedial technologies addressed: u u Technology Groups u u u u Excavation u Physical containment u In-situ soil mixing u Natural source zone depletion (NSZD) u Air sparging/soil vapor extraction u (AS/SVE) u LNAPL skimming u 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 Key Point: Who ya gonna call?

8 Tech Reg Technology Series Tables Tech Reg Appendix A (p. A-1 to A-64) u A table series (Tables A, B and C) for each of the 17 LNAPL remediation technologies u • A-series – general technology information • B-series – evaluation factors • C-series – technical implementation considerations For a technology, the A, B and C table are presented on consecutive pages u Key literature references presented in the tables u 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 than what is presented.

9 Technology Groups u. Mass Control u. Mass Recovery u. Phase Change Mass Recovery Key Point: Simplify the selection of technology Mass Control

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

11 Linkage Between Remediation Objectives and Technology Groups u “Containment objective” – LNAPL mass control Technology Groups • Stop LNAPL migration by containing LNAPL u “Saturation objective” – LNAPL mass recovery • Reduce LNAPL saturation by recovering LNAPL u “Composition objective” – LNAPL phase change • Change LNAPL characteristics by phase change

The Name Game & General Technology Group Applicability Mass Control, Mass Recovery, Phase Change LNAPL present, but cannot flow into wells LNAPL can flow into wells Sr > Sr LNAPL Csat 12 Terminology Changes Csat, Residual, Mobile, Migrating >Sr= Mobile

13 Choosing a Remedial Technology Group Selection u You now have an understanding of your site, • • u 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

Sequenced Technology Deployment “Treatment Train” Mass Control, Mass Recovery, Phase Change LNAPL present, but cannot flow into wells LNAPL can flow into wells Sr > Sr LNAPL Csat 14 4. Natural Source Zone Depletion 3. Phase Change 2. Mass Recovery >Sr= Mobile 1. Mass Control

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

16 LNAPL Mass Control Concept Dam the LNAPL! PC MR MC

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

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

19 Saturation Objective LNAPL Mass Recovery Concept LNAPL Concern Migration or Mobility LNAPL Remedial Objective Remediation Goals 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

20 LNAPL Saturation LNAPL Mass Recovery Concept u u 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

21 LNAPL Phase Change PC MR MC

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

23 LNAPL Composition LNAPL Phase Change u u 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

24 Contrast Between Composition And Saturation Objectives Reduces Persistence Benzene Equilibrium Groundwater Concentration (mg/L) Saturation vs Composition 12 Reduced saturation (less LNAPL) Reduces Concentration 8 4 Changed composition 0 0 0. 2 LNAPL Saturation 0. 4 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)

25 Remediation Technology Grouping Overlap Phase Change Mass Recovery Mass Control

26 Knowledge Check What are the LNAPL technology groups? What general technology groups would you use for the following concerns and objectives? u Concern: LNAPL sheen on a surface water body Objective: stop LNAPL migration u Concern: LNAPL causing vapor intrusion risk Objective: reduce or eliminate VI risk

27 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? u Concern: LNAPL sheen on a surface water body Objective: stop LNAPL migration Mass control or mass recovery u Concern: LNAPL causing vapor intrusion risk Objective: reduce or eliminate VI risk Mass control or phase change

28 Natural Source Zone Depletion • Mass Control • Mass Recovery • Phase Change • NSZD

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

30 Natural Source Zone Depletion (NSZD) NSZD (Table A-4 Series, p. A-10 – A-12) PC MR MC

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

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

33 How Is NSZD Evaluated? NSZD - Demonstration NSZD DEMONSTRATIONS u Qualitative Evaluation Quantitative Analysis u Predictive Modeling u www. itrcweb. org/Documents/LNAPL-1. pdf

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

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

36 NSZD - Demonstration Submerged Source Zone Case Study Submerged Zone NSZD Rate ≈ 2. 2 gallons/acre/year

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

38 Exposed Source Zone Case Study NSZD - Demonstration u Nested soil vapor probes u Assumed soil diffusivity 450 feet NSZD Rate ≈ 1, 800 gallons/acre/year

39 Exposed Source Zone Case Study NSZD - Demonstration u Nested soil vapor probes u Push-pull tracer test to determine soil diffusivity (Johnson et al. , 1998) NSZD-1 200 gallons/acre/yr NSZD-5 NSZD-4 700 gallons/acre/yr 200 gallons/acre/yr NSZD-2 800 gallons/acre/yr NSZD-6 700 gallons/acre/yr NSZD-3 600 gallons/acre/yr NSZD Rate ≈ 600 gallons/acre/year

NSZD - Demonstration 40 Recent Advances – Vadose Zone CO 2 Flux UBC LI-COR CO 2 flux chamber CSU passive CO 2 traps Multi-level probes & pressure xducers

41 Recent Advances – Temperature Profiles u C 8 H 18 + 12. 5 O 2 → 8 CO 2 + 9 H 2 O + HEAT • 28. 7 k. Cal/gallon Gasoline NSZD - Demonstration (1 m 3 from ice water to pool water)

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

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

44 Knowledge Check u What technology group does NSZD fit into and why? u Where does the LNAPL go (what happens to deplete the LNAPL)? u Is this really a “technology”?

45 Knowledge Check u What technology group does NSZD fit into and why? Phase change because it relies on LNAPL volatilization and dissolution. u 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 u Is this really a “technology”? It’s a natural phenomenon that, like an active technology, can be measured and evaluated to assess effectiveness

46 LNAPL Mass Control Technologies • Mass Control • Mass Recovery • Phase Change

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

48 Mass Control Technologies Physical containment u Hydraulic containment u Soil stabilization LNAPL Mass Control u

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

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

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

52 Metrics For Mass Control Performance u No first LNAPL occurrence downgradient LNAPL Mass Control • 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) u Dissolved-phase regulatory concentration standard met at compliance point u Reduced dissolved-phase concentrations downgradient of barrier u

53 Knowledge Check u In general, what is a major advantage of LNAPL mass control technologies? u Disadvantage? u Is mass control measurable? How? u Why use mass control if an LNAPL body isn’t migrating?

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

55 Knowledge Check u Is mass control measurable? How? Yes. Various ways, direct - no first occurrence of LNAPL, indirect – LNAPL volatile or dissolved constituent monitoring. u 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.

56 LNAPL Mass Recovery Technologies • Mass Control • Mass Recovery • Phase Change

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

58 Mass Recovery Technologies LNAPL Mass Recovery u (Simple) Hydraulic Recovery • • • u 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 u Excavation

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

60 Dual-Pump Liquid Extraction (DPLE) (Table A-8 Series, p. A-24 – A-27) u LNAPL Mass Recovery u u u 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 LNAPL Pump LNAPL Groundwater PC Water Pump Modified from USACE 1999 MR MC

61 Bioslurping / Enhanced Fluid Recovery (EFR) (Table A-7 Series, p. A-20 – A-23) u LNAPL Mass Recovery u u 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 Gas Discharge/ Treatment Gas/Liquid Separator Vacuum Pump LNAPL/ Water Separator Slurp Tube Bioventing PC Air MR MC LNAPL Modified from USACE 1999

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

63 MPE – Dual Pump (Table A-9 Series, p. A-28 – A-32) LNAPL Mass Recovery u u u LNAPL Discharge 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 Soil Vapor Discharge . . . . . . . . . . . . . . . Soil Vapor LNAPL PC MR MC Groundwater Discharge LNAPL Pump Groundwater Extraction Pump

64 LNAPL Mass Recovery Hydraulic Recovery Technology Pros Technology Advantage Skimming • LNAPL-only waste stream • Lowest per-well cost • • EFR/Bioslurp • • MPE • (Single Pump) • MPE • • (Dual Pump) DPLE 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

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

LNAPL Mass Recovery 66 Hydraulic Recovery Technology Engineering Technology Parameters for Design Skimming • LNAPL radius of capture (ROC) DPLE • Groundwater flow vs. drawdown and ROI • Vacuum ROI, aeration and pore volume exchange MPE • Vacuum ROI (Single Pump) • Groundwater flow vs. drawdown and ROI MPE • Vacuum ROI (Dual Pump) • Groundwater flow vs. drawdown and ROI EFR/Bioslurp Note: ROI means the distribution of vacuum or drawdown with radius, not just the radius at which 0. 1” H 2 O vacuum or 0. 01’ drawdown is observed or predicted

67 Groundwater Extraction LNAPL Mass Recovery Hydraulic Recovery Methods Vacuum Enhancement

68 Hydraulic Recovery Remedial Time Frame u Comparing remedial time frame for a single well system LNAPL Removed LNAPL Mass Recovery E P M FR E / g rpin lu s o i B Ry E L DP g n i m m i k S TMPE TDPLE Time TSkim

69 LNAPL Transmissivity and Hydraulic Recovery Technologies Comparing well density to achieve comparable recovery Soc k Bai s ling Well Density LNAPL Mass Recovery u Ski mm ing DPL E, B iosl urp ing MP /EF E R 0. 1 1. 0 10 LNAPL Transmissivity (ft 2/day)

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

71 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

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

73 Knowledge Check u 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