FRACTURED ROCKCharacterization and RemediationAllan HornemanSeptember 30, 2016

© Arcadis 2016

Disclaimers and NoticesThe 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.

© Arcadis 2016

About the Presenter

c 207 553 0072

e allan.horneman@arcadis.com

ALLAN HORNEMAN, PHDPrincipal Geologist | Area Focus Leader: Fractured Rock

© Arcadis 2016

Learning ObjectivesAfter 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.

© Arcadis 2016

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

© Arcadis 2016

Fractured Rock and the Matrix Diffusion Challenge

Overcoming industry-wide pessimism

After Beth Parker et al.

© Arcadis 2016

Fractured Rock Storage vs Transport

Advective Zones – Pure Advection

Advective / Storage Zones – Slow Advection

Storage Zones – Static Water / Storage

Highly Fractured zones(Mobile Fraction)

Low Fracture Density/Blind Fractures(Immobile Fraction)

Rock Matrix/Highly Weathered Rock(Storage Fraction)

Hydraulic Conductivity > 10-4 cm/sec

10-6 cm/sec < Hydraulic Conductivity < 10-4 cm/sec

Hydraulic Conductivity < 10-6 cm/sec

Mobile Fraction θm

Immobile Fraction θi

Stationary Fraction θs

Mass Transfer

Diffusion

© Arcadis 2016

The Advances in Site Characterization

• Complex fracture network• Absence/presence of matrix porosity• Source mass vs mass that moves• Vertical gradients and aquitards

CSM based on monitoring well data?

CSM based on targeted tools to reduce uncertainty:Geophysical methodsFLUTe liner technologiesDFN approachCORETM

Rock coring Short screened monitoring wellsTracersPassive flux meters

Fractured Rock Investigation Toolbox

© Arcadis 2016

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.

© Arcadis 2016

Rock Coring & CORETM

• Logging of rock and fractures;

• Assessment of mass in unfracturedrock matrix;

• Physical property estimates:– TOC– Matrix porosity– Tortuosity

© Arcadis 2016

FLUTeTM Liner & Hydraulic Profiling Tool

Identify High K (Advection) and Low K (Aquitards – Low Advection/Diffusion) Zones)

© Arcadis 2016

FACT LINER – (FLUTe Activated Carbon Technique)• Concentration Profiling;• Mass Flux;• Refine CSM and Inform In-

situ Remedy.

164 ft

175 ft

© Arcadis 2016

Passive Flux MeterDeveloping technology utilizing tracers.

- Provide flux and fracture orientation information comparable to combined FACT and hydraulic profiling tool.

Klammler et al., 2016

© Arcadis 2016

Bulk Conductivity / VAP Data Interval Conductivity (FLUTe)

Acoustic Televiewer

Downhole Geophysics

© Arcadis 2016

Other Geophysical Tools

Lithology vs Inferred Fate & Transport

© Arcadis 2016

Volcanic Rock Fate & TransportRapid cooling, formation of obsidian, highly susceptible to weathering – primary porosity and more permeable zone

© Arcadis 2016

Volcanic Rock Investigation/Remediation Focus

“Mass that Matters” Focus in Line with “Do No Harm”

Low K

High K

Low K

High K

Low K

Focus on high K zones

Don’t short-circuit low K zones

MassThat

Matters

© Arcadis 2016

Sedimentary Rock Fate & Transport

> 99% of mass present within the unfractured rock matrix

• Matrix porosity (up to 20%) – Significant Storage;

• Bedding important – fracturing, flow and advective transport

• Zones of reduced fracture density control vertical extent of contamination.

DiffusionHalo

Extremely Fracture Zone

© Arcadis 2016

µg VOC / g rock

Sedimentary Rock: Sourcing, Aquitards & PartitioningD

epth

(ftb

gs)

Source rock porewater: 100,000s µg/L

Groundwater: 1,000s µg/L

Groundwater: 1µg/L

Aquitard

Sorbed93%

Primary Pore Water

7%

Fracture Water0.1%

PartitioningMass Partitioning

© Arcadis 2016

Metamorphic rock

SlateCleavage and foliationComplex jointingMatrix porosity low

Fate & transport Complex – some similarities to sedimentary rock

Biotite gneissMineral foliationComplex jointingMatrix porosity very low

Fate & transport Complex – some similarities to e.g. granite.

© Arcadis 2016

Metamorphic Rock Fate and Transport• 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.

MW-301

MW-302

Overburden

SE

NW Hall

Rd

Alternating fine &

pegmatitic granofels

Schist/SchistyGneiss

© Arcadis 2016

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

© Arcadis 2016

Karst Porosity• Matrix (Primary)

• Fracture/joints (secondary)

• Chemical dissolution (channels) (tertiary) joints

major channels

open bedding planewith channels shown

“First Do No Harm”

© Arcadis 2016

“First Do No Harm” Concept

Long open borings + Large hydraulic gradient = Injecting contaminant at depth

Typically strong vertical hydraulic gradient;

Historic long open borings allows for significant vertical transport of mass over time;

1,180

1,200

1,220

1,240

1,260

1,280

1,300

1,320

1,340

1,360

1,380

1,300 1,320 1,340 1,360 1,380

Mon

itorin

g Po

rt E

leva

tion

(ft re

lativ

e to

mea

n se

a le

vel)

Total Head (ft relative to mean sea level)

Remediation of Fractured Rock

© Arcadis 2016

General Investigation/Remediation Trends

2000 2010

Pre-2005:Investigation: Monitoring wells

2001: Revised remedial Approaches - Early adaptors In-situ bio in source zones.

2005 and onwards: Next Gen supplemental investigations. Source zone vs. plume goals, targeted source zone remedies. Revised source zone remedial goals.

2010s: In-situ plume remedies

2014: Closure of U.S. large plume fractured rocksite.

Pre-2000s: Remedial Strategy: P&T and limited excavation

Post 2005: Risk driven goals

© Arcadis 2016

Drivers for Fractured Rock Remediation

Source Zone

VI Mass Discharge

Plume – Risk Drivers

VIMass

Discharge to surface water

Protection of Water

supplies

© Arcadis 2016

Fractured Rock Site Closures

Large Plume (2,000 ft) –Fractured

Sandstone. Cost Savings

$8MRisk Based Remedial

Goals

Focus on High Concentration / Mass

FluxAdaptive Approach

Large Plume 5,000 ft) –Fractured

Chalk. Cost Savings $6M

SITE Closure

Remediation – Case Studies

© Arcadis 2016

Example 1: Source Reduction and Plume Closure

© Arcadis 2016

Example 1: Overcoming Matrix Diffusion

Post Remediation After Remediation

© Arcadis 2016

Example 1: Adaptive Approach

Site Closure Reflecting:• Regulatory/Risk Based Goals

• Focus on Mass Recovery/Destruction

• Adaptive Approach

© Arcadis 2016

Example 2: Karst Site - Risk Based Site Closure

© Arcadis 2016

Limited Bedrock data

Bedrock Well

1,1 DCE Concentration (µg/L)

MCL

20

40

60 1. Only 1 bedrock well at site – exhibits increasing 1,1 DCE trend

2. RM-2 Guidance requires estimation of POE concentration (hypothetical offsite domestic well):

− “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!

© Arcadis 2016

Assessment of Risk Based Standards

© Arcadis 2016

No Further Action - Site Closure

LPOE

Distance (ft)

QPOE Flow

(gal/d)Void Space

M1,1-DCE Source Concentration in Bedrock (µg/L)

1850 150 0.10% 1091850 150 0.24% 461850 300 0.10% 1701850 300 0.24% 701500 150 0.10% 963000 150 0.10% 149

Range of computed “acceptable” 1,1 DCE values

© Arcadis 2016

SummaryThe 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.

© Arcadis 2016

ContactsAllan Horneman, PhDPrincipal GeologistPortland, Maineallan.horneman@arcadis.com

Michael Cobb, P.G.Principal GeologistPortland, Mainemichael.cobb@arcadis.com

Keith White, P.G.Principal GeologistSyracuse, New YorkKeith.white@arcadis.com

© Arcadis 2016

Q&A

© Arcadis 2016

© Arcadis 2016

Arcadis.Improving quality of life.