Direct Push High-Pressure Jet Injection Method for Delivery of in Situ Remediation Agents in Clay Till. Neal Durant, Ph.D. Geosyntec Consultants

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1 Direct Push High-Pressure Jet Injection Method for Delivery of in Situ Remediation Agents in Clay Till Neal Durant, Ph.D. Geosyntec Consultants

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3 Co-Authors and Partners Capital Region of Denmark Mads Terkelsen Lone Tolstrup Karlby Camilla Christiansen FRx Hydraulic Fracturing Experts Bill Slack Torben Jørgensen Lars Nissen Chapman Ross Owen Cadwalader

4 Problem Statement: Develop Method to Treat DNAPL Residual and Solvents Diffused into Clay Till ~40% of Denmark covered in highly fractured clay till ~1,500 chlorinated solvent sites in clay till in Capital Region alone Result: many long term difficult to treat sources

5 High Pressure Jet Injection Mechanisms How it works Up to 690 bar (10,000 psi) water jetting erodes conduits in clay in a chosen orientation to 27.6 bar (150 to 400+ psi) slurry introduced which creates hydraulic fractures extending from the ends and between the conduits. Slurry contains proppant/reactant (sand, ZVI, etc) which holds fracture open and either enhances permeability or reacts with contaminants directly. Conduits Cavity Horizontal Fracture

6 High Pressure Jet Injection Technology Development Chronology Initial DK Pilot Test DPT Proof of Concept Testing DPT Jet Injection Testing Phase I Year Location Denmark US (SC) US (OH) Geology Clay Till Saprolite Clay Till Delivery Method Jetting Fluid Blank PVC Well DPT DPT Water Water w/ Green Dye Water Injectate Amendment Slurry w/ Rhodamine WT Dye none Cross-linked Guar Gel Slurry w/ Rhodamine WT Dye

7 Initial Jet Injection Pilot Test Taastrup, Denmark, November 2011

8 Initial Denmark Pilot Test - Objectives - Taastrup, Denmark, November 2011 Deliver aqueous slurry ZVI via jet injection into PVC wells in fractured basal clay till formation at 3-7 meters below ground surface. Determine whether sub-horizontal, homogeneous distribution of remediation material is possible. Determine whether injection conduits can cut-across natural fractures. Determine how closely conduits can be induced at various depths.

9 Pilot Test #1 Site

10 Excavation Plan

11 Excavated Test Plot

12 Characterization: Measuring Jet Injection Performance Dimensional Sketches Soil Sampling Magnetic Susceptibility

13 Fractures IW-2 IW-1

14 Secondary Fractures (IW-1)

15 Initial DK Pilot Test Methods Jetting through PVC casing and well grout caused many problems including injection short-circuiting

16 Initial DK Pilot Test 3D Visualization of Primary Vertical Fractures

17 Initial DK Pilot Test Summary of Results - Taastrup, Denmark, November 2011 Aqueous slurry containing zero valent iron (ZVI) was distributed into fractured basal clay till. Vertical fractures were observed 6-7 m across. Sub-horizontal, homogeneous distribution of ZVI was not achieved. ZVI was distributed through primary and secondary subvertical and sub-horizontal fractures. Natural vertical fractures were not bypassed. Failure Mode TOO MUCH KINETIC ENERGY LOSS

18 Pilot Test #2 - Jet Injection via DPT Travelers Rest, South Carolina, July 2012

19 SC DPT Proof of Concept Testing - Objectives - Travelers Rest, South Carolina, July 2012 Determine whether DPT Jet Injection: Achieves a more controlled fracturing distribution, relative to injection into PVC wells Is less susceptible to short-circuiting than injection into PVC wells Can emplace conduits/fractures across natural fractures. Determine whether injection into multiple nozzles simultaneously increases conduit length.

20 SC DPT Testing Methods Multi-port DPT Injection Tip Water blaster Probe tip with nozzle inserts Dye mixing tank

21 Path of jet cutting across weathered rock SC DPT Testing Excavation

22 SC DPT Testing Excavation 1.4 m 1.8 m View from either side of the jet (parallel to jet-rod plane)

23 SC DPT Testing 3D Visualization of Sub-Horizontal Fracture Form (Dimensions in meters, Hach Colorimeter results in Pt-Co color units)

24 Conclusions SC DPT Testing Cavity size ranged from m (conduits observed). Horizontal fracture widths ranged from 1.0 to 2.1 m across, often shifted off-center from injection point. Formed fractures that were perpendicular to geologic features. DPT jet injection achieved more controlled fracture/conduit emplacement than jet injection into PVC wells.

25 DPT Jet Injection Development Phase I August to December 2013

26 DPT Jet Injection Phase I Tooling Design Two new tooling designs were developed for field testing, improving on tooling used in the 2012 SC pilot test. Design modifications included: Separate water jetting and slurry injection lines Modification for use with Geoprobe expendable drive tips Design of 4-nozzle and 6-nozzle tips with differing slurry line flow paths.

27 DPT Jet Injection Phase I Tooling Design

28 DPT Jet Injection Tooling Working Prototypes 4 Nozzle Design 6 Nozzle Design

29 Test Site Schillig Farm - Alliance, Ohio Clean test site identified in glacial clay till. Hand auger borings used to confirm presence of clay till. During pilot testing, advancement of geologic borings guided the selection of injection locations and depths. Soil borings identified the redox boundary and facilitated injection testing below this boundary. (Canton Quadrangle)

30 Site Map Schillig Farm - Alliance, Ohio Core 3 JI-A JI-C Core 2 Extent of excavation N JI-B JI-F 10 m Core 4 Core 4 Core 1 4 Geoprobe borings for site characterization 4 injection locations JI-A and JI-F in shallow soil jetting only JI-B and JI-C below redox boundary jetting and slurry injection

31 Site Geology Schillig Farm - Alliance, Ohio Depth Interval Soil Description 0 to 0.4 m Topsoil and brown silty clay 0.4 to 2.2 m Light brown to grey silty clay, some layers silt and fine sand 2.2 to 4.5 m Dense grey silty clay, trace sand and gravel Target depth for injections: m Core 4 Redox Boundary

32 Detailed Operating Parameters Injection No. DPT tooling Nozzle Velocity (m/s) Nozzle Power (kw) Depth (m) Geologic unit Dye Excavation JI-A 6-jet brown sandy clayey silt No No JI-B 4-jet dense grey clay till Yes Yes JI-C 6-jet dense grey clay till Yes Yes JI-F 6-jet brown sandy clayey silt No Yes Injection No. Jet Pressure (bar) Jetting Duration (seconds) Jetting Flow Rate (L/min) Jetting Volume (L) Breakdown Pressure (bar) Slurry Injection Pressure (bar) Slurry Injection Volume (L) JI-A n/a n/a n/a JI-B JI-C JI-F n/a n/a n/a

33 Test Location JI-F: 6-Jet Nozzle Test demonstrated effectiveness of conduit formation: No venting or daylighting of fluids during prolonged jetting (> 2 minutes) at a depth of only 1.1 m bgs No evidence of fracturing activated by jetting alone. 0.9 m 0.3 m Star-shaped cavity with six individual conduits eroded by each jet

34 Test Location JI-B: 4-Jet Nozzle 3.3 m Redox Boundary Gravel Layer Injection in dense, grey clay till below redox boundary

35 Test Location JI-B: 4-Jet Nozzle N 3.2 m Observed Dye 1.4 m 1.4 m Observations during excavation: Largest dimension of cavity measured 1.8 m Largest dimension of horizontal fracture measured 2.0 m Dye observed 3.2 m from injection Horizontal Fracture Cavity 0.4 m 1.0 m 0.7 m

36 Test Location JI-B: 4-Jet Nozzle Collapsed Cavity Conduit eroded to 1.4 m away from jets

37 Test Location JI-B: 4-Jet Nozzle Gravel Layer Horizontal fracture formed in grey clay till between sub-horizontal sand and gravel layers. Fracture achieved despite proximity to highly permeable features.

38 Test Location JI-C: 6-Jet Nozzle Horizontal Fracture 0.9 m N 0.4 m Cavity 2.1 m 0.3 m 0.9 m Observed Dye Observations during excavation: Largest dimension of cavity measured 0.7 m Largest dimension of horizontal fracture measured 1.8 m Dye observed 2.5 m from injection Collapsed Cavity 1.0 m 2.5 m

39 Test Location JI-C: 6-Jet Nozzle Created sub-horizontal fracture in dense glacial clay till. Fractures propagated from edges of cavity.

40 Summary of Findings Successfully demonstrated controlled cutting of conduits with no surface venting with both tooling designs. 4-jet design achieved an X-shaped cavity with four clearly defined conduits; horizontal fractures were formed both between the conduits and extending outward from the conduit tips. Maximum fracture widths in Phase I testing likely limited by moderate slurry injection volumes (95 liters/injection). 6-jet design performed better at preventing slurry line clogs during tooling advancement. Developed procedure for preventing nozzle clogging during advancement. Observed Dye Horizontal Fracture Cavity Controlled Conduit Cutting 6-Jet Design

41 Next Steps Phase II testing of DPT Jet Injection method at a contaminated test site in Capital Region later this year. Refinement of injection procedures to: Increase conduit lengths and uniformity Increase horizontal fracture widths Injection of zero-valent iron slurry into a clay till source zone and performance monitoring to evaluate treatment effectiveness. Evaluation of method performance in fractured clay till.

42 Questions?

43 Now on to Some Exercises!

44 Zero Valent Iron (ZVI or Fe 0 ) Corrosion Chemistry e - e - e - e - e - Fe 0 (s) Fe 0 Fe e - Fe 0 + H 2 O Fe OH - + H 2 e - e e - - e - e - e - e - e - e - e - e - e - e -

45 ZVI - Example Treatment Capabilities PCB C 2 HCl 3 TCE e - Biphenyl e - e - e - e - C 2 H 4 Ethene CCl 4 CTET e - CH 4 Methane e - e - Fe 0 (s) e - Cr 6+ e - e - Cr 3+ (OH) 3 (s) Pb 2+ e - Pb 0 (s) e - e - NO 3 - e e - - e - e - NH 4+, N 2 As 5+ As 3+ sorbed

46 Dechlorination Pathways by ZVI

47 PCE PCE Dechlorination Pathways by ZVI β - Elimination dominates abiotic Pathway (Tratnyek and Sarathy, 2008)

48 TCE Dechlorination Pathways by ZVI TCE β - Elimination dominates abiotic Pathway (Tratnyek and Sarathy, 2008)

49 cis-1,2-dce Dechlorination Pathways by ZVI cdce β - Elimination dominates abiotic Pathway (Tratnyek and Sarathy, 2008)

50 ZVI Treatment Rates Depend on Surface Area (.and Scale!) dc dt = k a ρ C kobs = ksaas ρm SA S m dc dt = k OBS C For batch reactor systems Where C = concentration of constituent subject to treatment (mg/l) k SA = surface area-normalized rate coefficient (L/hr/m 2 ) a S = specific surface area of metal (m 2 /g) ρ m = mass concentration of metal (g/l) k OBS = pseudo first-order decay coefficient (hr -1 )

51 Exercise Problem 1 ZVI Treatment Rates dc/dt = k SA a s ρ m C 0 k OBS = k SA ρ a a s C=C 0 *exp(-k OBS *t) t = (LN(C/C 0 ))/-k OBS t 1/2 = (LN2)/k OBS Nanoscale Microscale Microscale Lehigh Peerless Fisher Surface area normalized rate coefficient k SA (L m -2 hr -1 ) Mass conc. Of metal ρ m (g/l) Specific surface area a s (m 2 /g) TCE Concentration C (mg/l) Psuedo first order decay rate? k OBS (hr -1 ) Half life? t 1/2 (d) Concentration at 100 days? Days to reach drinking standard?

52 Exercise Problem 1 ZVI Treatment Rates dc/dt = k SA a s ρ m C 0 k OBS = k SA ρ a a s C=C 0 *exp(-k OBS *t) t = (LN(C/C 0 ))/-k OBS t 1/2 = (LN2)/k OBS Nanoscale Microscale Microscale Lehigh Peerless Fisher Surface area normalized rate coefficient k SA (L m -2 hr -1 ) Mass conc. Of metal ρ m (g/l) Specific surface area a s (m 2 /g) TCE Concentration C (mg/l) k OBS (hr -1 ) t 1/2 (d) Concentration at 100 days? Days to reach drinking standard (2 ug/l)?

53 Exercise Problem 2 ZVI Degradation Stoichiometry At a chlorinated solvent site you are working on, an estimated 270 Kg of tetrachloroethene (PCE, C 2 Cl 4 ) remains in the source area. Using the stoichiometric relationship below (and ignoring mass transfer limitations!), estimate the mass of zero valent iron (Fe 0 ) needed dechlorinate the PCE to ethene. C 2 Cl 4 + 4Fe 0 + 4H + => C 2 H 4 + 4Fe Cl - PCE molecular weight: g/mol Fe 0 molecular weight: g/mol

54 Exercise Problem 3 DPT Jet Injection Layout Number of Injection points with 4 m ROI to treat 50 mg/kg area?

55 Exercise Problem 3 DPT Jet Injection Layout 4 m ROI, ~ 13 Injection points

56 Exercise Problem 4 What Mass of ZVI Is Required? Assumptions Density ZVI 6.7 g/cm3 Slurry ZVI loading 600 kg Fe0/m3 slurry # Injection locations 13 Design ROI 4 m Average fracture thickness 1.5 cm Depths per location (1 meter spacing) 5 depths Each fracture slurry volume m3 ZVI mass in slurry kg ZVI volume in slurry m3 ZVI % of slurry by volume Each location ZVI mass in slurry kg Site (13 Locations) ZVI mass in slurry Tonne

57 Exercise Problem 4 What Mass of ZVI Is Required? Assumptions Density ZVI 6.7 g/cm3 Slurry ZVI loading 600 kg Fe0/m3 slurry # Injection locations 13 Design ROI 4 m Average fracture thickness 1.5 cm Depths per location (1 meter spacing) 5 depths Each fracture slurry volume 0.75 m3 ZVI mass in slurry 452 kg ZVI volume in slurry m3 ZVI % of slurry by volume 9.0% Each location ZVI mass in slurry 2262 kg Site (13 Locations) ZVI mass in slurry 29 Tonne