FRACTURED ROCK Characterization and Remediation. Allan Horneman September 30, 2016

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1 FRACTURED ROCK Characterization and Remediation Allan Horneman September 30, 2016

2 Disclaimers and Notices The materials herein are intended to furnish viewers with a summary and overview of general information on matters that they may find to be of interest, and are provided solely for personal, non-commercial, and informational purposes. The materials and information contained herein are subject to continuous change and may not be current, correct, or error free, and should not be construed as professional advice or service. You should consult with an Arcadis or other professional familiar with your particular factual situation for advice concerning specific matters. THE MATERIALS AND INFORMATION HEREIN ARE PROVIDED "AS IS" AND WITH ALL FAULTS AND WITHOUT ANY REPRESENTATION OR WARRANTY, EXPRESS, IMPLIED OR STATUTORY, OF ANY KIND BY ARCADIS, INCLUDING, BUT NOT LIMITED TO, WARRANTIES OF MERCHANTABILITY, NON- INFRINGEMENT, NO ERRORS OR OMISSIONS, COMPLETENESS, ACCURACY, TIMELINESS, OR FITNESS FOR ANY PARTICULAR PURPOSE. ARCADIS DISCLAIMS ALL EQUITABLE INDEMNITIES. ANY RELIANCE ON THE MATERIALS AND INFORMATION HEREIN SHALL BE AT YOUR SOLE RISK. ARCADIS DISCLAIMS ANY DUTY TO UPDATE THE MATERIALS. ARCADIS MAY MAKE ANY OTHER CHANGES TO THE MATERIALS AT ANY TIME WITHOUT NOTICE. The materials are protected under copyright laws and may not be copied, reproduced, transmitted, displayed, performed, distributed, rented, sublicensed, altered, or otherwise used in whole or in part without Arcadis' prior written consent.

3 About the Presenter ALLAN HORNEMAN, PHD Principal Geologist Area Focus Leader: Fractured Rock c e allan.horneman@arcadis.com

4 Learning Objectives After attending this presentation, you should be able to: Identify Appropriate Fractured Rock Investigation Strategies; Assess Key Fate and Transport Themes Based on Rock Type; and Distinguish Between Fractured Rock Source and Plume Remedial Strategies and Goals.

5 Agenda The Fractured Rock Challenge Investigation Tools Know Your Rock Fate and Transport Considerations in different rock types Remedial Approach Focus on the Mass that Matters Case Studies Summary

6 Fractured Rock and the Matrix Diffusion Challenge Overcoming industry-wide pessimism After Beth Parker et al.

7 Fractured Rock Storage vs Transport Advective Zones Pure Advection Mobile Fraction θ m Mass Transfer Immobile Fraction θ i Diffusion Stationary Fraction θ s Highly Fractured zones(mobile Fraction) Hydraulic Conductivity > 10-4 cm/sec Advective / Storage Zones Slow Advection Low Fracture Density/Blind Fractures(Immobile Fraction) 10-6 cm/sec < Hydraulic Conductivity < 10-4 cm/sec Storage Zones Static Water / Storage Rock Matrix/Highly Weathered Rock(Storage Fraction) Hydraulic Conductivity < 10-6 cm/sec

8 The Advances in Site Characterization CSM based on monitoring well data? Complex fracture network Absence/presence of matrix porosity Source mass vs mass that moves Vertical gradients and aquitards CSM based on targeted tools to reduce uncertainty: Geophysical methods FLUTe liner technologies DFN approach CORE TM Rock coring Short screened monitoring wells Tracers Passive flux meters

9 Fractured Rock Investigation Toolbox

10 It All Start With a CSM Publications USGS, maps, publications; Prior site work and reports; Initial site visit Take a good look at the road cuts and topography.

$fractures; Assessment of$ matrix; Physical property

11 Rock Coring & CORE TM Logging of rock and fractures; Assessment of mass in unfractured rock matrix; Physical property estimates: TOC Matrix porosity Tortuosity

12 FLUTe TM Liner & Hydraulic Profiling Tool Identify High K (Advection) and Low K (Aquitards Low Advection/Diffusion) Zones)

13 FACT LINER (FLUTe Activated Carbon Technique) Concentration Profiling; Mass Flux; Refine CSM and Inform Insitu Remedy. 175 ft 164 ft

$- Provide flux and fracture orientation information comparable to combined FACT and hydraulic$

14 Passive Flux Meter Developing technology utilizing tracers. - Provide flux and fracture orientation information comparable to combined FACT and hydraulic profiling tool. Klammler et al., 2016

15 Downhole Geophysics Bulk Conductivity / VAP Data Interval Conductivity (FLUTe) Acoustic Televiewer

16 Other Geophysical Tools

17 Lithology vs Inferred Fate & Transport

18 Volcanic Rock Fate & Transport Rapid cooling, formation of obsidian, highly susceptible to weathering primary porosity and more permeable zone

19 Volcanic Rock Investigation/Remediation Focus Low K High K Low K High K Focus on high K zones Mass That Matters Don t shortcircuit low K zones Low K Mass that Matters Focus in Line with Do No Harm

Sedimentary Rock Fate & Transport Matrix porosity

$fracturing, flow and advective transport Zones of$ contamination.

20 Sedimentary Rock Fate & Transport Matrix porosity (up to 20%) Significant Storage; Bedding important fracturing, flow and advective transport Zones of reduced fracture density control vertical extent of contamination. Extremely Fracture Zone Diffusion Halo > 99% of mass present within the unfractured rock matrix

21 Depth (ft bgs) Sedimentary Rock: Sourcing, Aquitards & Partitioning µg VOC / g rock Source rock porewater: 100,000s µg/l Groundwater: 1,000s µg/l Aquitard Groundwater: 1µg/L Primary Pore Water 7% Mass Partitioning Partitioning Sorbed 93% Fracture Water 0.1%

sedimentary rock Biotite gneiss Mineral foliation Complex jointing

22 Metamorphic rock Slate Cleavage and foliation Complex jointing Matrix porosity low Fate & transport Complex some similarities to sedimentary rock Biotite gneiss Mineral foliation Complex jointing Matrix porosity very low Fate & transport Complex some similarities to e.g. granite.

$Metamorphic Rock Fate and Transport Schist/Schisty Gneiss Mass bleeds into discrete fracture/fracture sets Moves within fracture system here primarily$

23 Metamorphic Rock Fate and Transport Schist/Schisty Gneiss Mass bleeds into discrete fracture/fracture sets Moves within fracture system here primarily oriented NE-SW. Primary transport may be un-related to apparent hydraulic gradient. Alternating fine & pegmatitic granofels NW MW-302 Hall Rd MW-301 S E Overburden

24 Karst and now things get tricky Unique aquifer structure Water and contaminants often move fast and far Traditional characterization approaches alone will often be misleading

25 Karst Porosity Matrix (Primary) Fracture/joints (secondary) Chemical dissolution (channels) (tertiary) joints major channels open bedding plane with channels shown

26 First Do No Harm

27 First Do No Harm Concept 1,380 1,360 Monitoring Port Elevation (ft relative to mean sea level) 1,340 1,320 1,300 1,280 1,260 1,240 1,220 1,200 1,180 1,300 1,320 1,340 1,360 1,380 Total Head (ft relative to mean sea level) Typically strong vertical hydraulic gradient; Historic long open borings allows for significant vertical transport of mass over time; Long open borings + Large hydraulic gradient = Injecting contaminant at depth

28 Remediation of Fractured Rock

29 General Investigation/Remediation Trends Pre-2000s: Remedial Strategy: P&T and limited excavation Post 2005: Risk driven goals 2001: Revised remedial remedies 2000 Approaches - Early adaptors 2010 In-situ bio in source zones. 2010s: In-situ plume 2014: Closure of U.S. large plume fractured rock site. Pre-2005: Investigation: Monitoring wells 2005 and onwards: Next Gen supplemental investigations. Source zone vs. plume goals, targeted source zone remedies. Revised source zone remedial goals.

30 Drivers for Fractured Rock Remediation Source Zone Plume Risk Drivers VI Mass Discharge VI Mass Discharge to surface water Protection of Water supplies

31 Fractured Rock Site Closures Large Plume (2,000 ft) Fractured Sandstone. Cost Savings $8M Large Plume 5,000 ft) Fractured Chalk. Cost Savings $6M Risk Based Remedial Goals Focus on High Concentration / Mass Flux Adaptive Approach SITE Closure

32 Remediation Case Studies

33 Example 1: Source Reduction and Plume Closure

34 Example 1: Overcoming Matrix Diffusion Post Remediation After Remediation

35 Example 1: Adaptive Approach Site Closure Reflecting: Regulatory/Risk Based Goals Focus on Mass Recovery/Destruction Adaptive Approach

36 Example 2: Karst Site - Risk Based Site Closure

37 Limited Bedrock data Bedrock Well Only 1 bedrock well at site exhibits increasing 1,1 DCE trend 40 1,1 DCE Concentration (µg/l) 2. RM-2 Guidance requires estimation of POE concentration (hypothetical offsite domestic well): 20 MCL For sites in unique geologic environments not suited for the Domenico Model (such as karst ), another, more appropriate, model should be applied. No such model exists for karst!

38 Assessment of Risk Based Standards

39 No Further Action - Site Closure L POE Distance (ft) Q POE Flow (gal/d) Void Space M 1,1-DCE Source Concentration in Bedrock (µg/l) % % % % % % 149 Range of computed acceptable values 1,1 DCE

40 Summary The challenge of fractured rock remediation can be overcome by: Appropriate risk based remedial goals; Focus on high concentrations and flux zones; and Adaptive remedial approach. An appropriate and targeted remedial approach based on sufficient site understanding is the key to cost and risk uncertainty reduction.

Principal Geologist Portland, Maine michael.cobb@arcadis.

41 Contacts Allan Horneman, PhD Principal Geologist Portland, Maine Michael Cobb, P.G. Principal Geologist Portland, Maine Keith White, P.G. Principal Geologist Syracuse, New York

42 Q&A

44 Arcadis. Improving quality of life.

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