INJECTION HYDRAULICS AND TRACER TEST DESIGNCraig Divine

September 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.

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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.

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Health and Safety

ARCADIS field staff followed instructions in fluorescein MSDS and washed driller’s arms with fresh water and soap. Rash dissipated within 5 minutes. No additional attention was required.

© Arcadis 2016

Outline and TopicsRelevant concepts in injection hydraulics • Injected fluid transport• Definitions

Tracer test design and interpretation concepts• Well selection and generic test layout• Implementing tracer tests• Selecting tracers• Avoiding “Failure” and keys to success

Other examples Eosine tracer

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Learning ObjectivesAfter attending this session, participants should be able to:

Describe fluid transport in the subsurface during and injection

Describe the general information and insight gained from tracer testing

Plan a conceptual tracer test designed to support injected-fluid based IRZ design

Analyze typical tracer response data to calculate mobile porosity and groundwater flow velocity

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Why use tracers?

All hydrogeological systems are heterogeneous and anisotropic

7

10-6 cm/sec10-4 cm/sec

10-2 cm/sec

inches

© Arcadis 2016Hidden Complexity

Groundwater Always Takes the Path of Least Cumulative Resistance

Flow Focusing >80% of flow occurs in <20% of the porespace

• Average hydraulics are poor predictor of transport behavior• Heterogeneity and aquifer structure controls plume behavior

and clean-up times• Flow concentration in most permeable zones

Tracers are the best (only) method for directly mapping transport

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History of Applied Tracers~10 AD: Flavius Josephus reports use of chaff tracer

Late 1800s: Fluorescent dyes used

Early 1900s: Quantitative tests in US

1970-2000: Research applications

Now routinely used to design and optimize remediation systems

ARCADIS has conducted 500+ tests over the past decade

Schlicter (1902)

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“There’s no truth like tracer truth” James Quinlan

Source term is well known

Direct measure of flow

Intuitive

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Why is Tracer Testing Important?

• Average hydraulics are a poor predictor of transport behavior

• Flow concentration in permeable units (mobile porosity)

• Most of the pore space acts as storage (immobile porosity)

• Local scale hydrogeologic conditions vary• Transverse dispersion is inconsequential at

the remedy scale

Tracer testing is the best (only) direct measurement method for understanding local scale variations in hydrogeology that affect remedy design

>90% of relative mass flux in <10% of our plumes

Tracer Testing Concepts

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Design Fundamentals

How many wells?

Where to screen?

How much to inject?

What to inject?

How frequently to monitor?

How to inject safely?2014, Suthersan et al., GWMR

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Definitions &Terms• Radius of Influence• Radial distribution of fluid around an injection

wellROI

• Fraction of the total pore space where the majority of groundwater flow occurs

• Assumes uniform radial distributionMobile

porosity

• Plot of tracer concentrations at a monitoring well versus cumulative time or volume

Tracer Breakthrough Curve (BTC)

• Groundwater Flow Velocity• Based on time to achieve 50% of the peak

concentration

AdvectiveGroundwater Velocity

• Based on mean tracer arrival time• Time take for half the total tracer mass to pass a

given monitoring pointAverage Velocity

Elapsed Time

Nor

mal

ized

Con

cent

ratio

n Tracer Breakthrough Curve

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Overview of an Injection

Injection Well

“Dose-Response” (DR) Well “Drift” Well (MW)

Inject Fluid

Volume

Con

c.

Injection Phase

Mobile Porosity

hrV

m 2πθ =

h

r

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Overview of an Injection

Time

Con

c.

Drift Phase

Average Velocitymean

ave TxV =

xROI

arrivalTROIxV −

=

Flow Velocity

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Conceptual Test and Well Network

Dose-Response Wells

Drift Wells

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Determining Mobile Porosity at a Dose-Response Well

Mobile Porosity

hrV

m 2πθ =

At a minimum, inject until target concentrations achieved at a cross-gradient dose response well and begin to plateau

V max/2

max/2V max

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Nor

mal

ized

Flu

ores

cein

Con

cent

ratio

n

Dose Response Well OW-4D

Tracer Breakthrough at DR wells

Actual breakthrough behavior at dose response wells often deviates from ideal; the calculated mobile porosity should be correlated to the target reagent strength

Mobile porosity varies around a single injection well, can be significant depending on the degree of heterogeneity

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Examples of Tracer-Derived Mobile Porosities

50% of sites had mobile porosity of 0.09 or less80% of sites were less than 0.15

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00.10.20.30.40.50.60.70.80.9

1

10 20 30 40

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0 50 100 150 200 250

(g

)

0

0.1

0.2

0.3

0.4

-50 0 50 10

Other Breakthrough Curve ExamplesExamples of Actual Tracer BTCs at Drift Wells

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Method of Moments

1. Normalize concentration data and plot versus time (BTC)

2. Integrate the area under curves and subtract 1/2 the tracer application time to get Tmean

3. Divide the distance travelled (x) by Tmean to get Vave

)*21(

)(

)(Appmean T

dttC

tdttCT −=

∫∫

meanave T

xV =

ARCADIS has a MoM tool which makes this easy

Treats the BTC as a statistical probability distribution function (PDF)

e

Elapsed Time

Nor

mal

ized

Con

cent

ratio

n Tracer Breakthrough Curve

bginj

bgmeasnorm CC

CCC

−−

=

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Selecting TracersInert • Won’t react, degrade or interact with aquifer or

planned reagents

High signal-to-noise ratio• Low background concentration

Easily analyzed

Cost-effective

Neutral density

Safe and non-toxic

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Common TracersQuantitative • Halides: chloride, bromide, iodide• Fluorescent organic ions (“Dyes”)

– fluorescein, Rhodamine WT, eosine, etc.

• Deuterated water (“Deuterium”)• Dissolved gases: sulfur hexafluoride, helium

Qualitative (real-time)• Electrical conductivity• Visual dyes• Temperature

Rhodamine WT

Rhodamine WT Fluorescein

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Specific Conductivity TracersHigh Specific Conductivity Low Specific Conductivity

(consider density effects)

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Fluorescein: Visual and Quantitative Breakthrough

Arcadis holds an MSA with Ozark Underground Laboratory (OUL)

Nontoxic, conservative

Well known

Inexpensive• $100/1,000 gal• $50/sample

Excellent signal to noise ratio• Applied at: ~50 ppm• Visual DL: ~100 ppb• Laboratory DL: 0.01 ppb

Multiple tracers available• Rhodamine WT, eosine

Some limitations at low pH and high foc

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Dueterated Water TracerStable isotope of hydrogen (2H or D) incorporated in water molecule

Completely nontoxic and perfectly conservative

NOT RADIOACTIVE!

Low natural abundance and reasonable S:N

Relatively inexpensive

• ~$350 per 1,000 gal injectate• ~$17-35 per sample

Good for ISCO applications

Arcadis holds an MSA with IT2 and UCD for analysis

Avoiding “Failure” and Key Steps for Success

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Reasons for “Failure”The most common reason for an inconclusive tracer test is an inadequate or incorrect CSM• Specifically assumptions of GW flow direction or local-

scale preferential pathways

Cutting corners to save money

• Injection volume• Monitoring program

Poor communication and/or failure to adapt in the field

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Five Easy Steps to Success• Inject Large Volumes1.• Do not skimp on the monitoring

network 2. • Sample frequently early, and

adapt3.• Maximize the signal to noise ratio4. • Expect surprises – and plan for

them5.

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Five Easy Steps to Success

• Inject Large Volumes• Stable concentrations at DR wells• Assume a high θm during planning• Add a contingency volume

1.

• Do not skimp on the monitoring network 2. • Sample frequently early, and adapt3.• Maximize the signal to noise ratio4. • Expect surprises – and plan for them5.

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Five Easy Steps to Success• Inject Large Volumes1.

• Do not skimp on the monitoring network • Consider flow direction uncertainty• Account for horizontal AND vertical

preferential pathways• Better to have more wells than risk

missing valuable information• Frame up expectations• Adapt sampling design if needed -

geoprobe, LIF etc

2.

• Sample frequently early, and adapt3.• Maximize the signal to noise ratio4. • Expect surprises – and plan for them5.

© Arcadis 2016

Five Easy Steps to Success• Inject Large Volumes1.• Do not skimp on the monitoring network 2.

• Sample frequently early, and adapt• Helps identify issues early• Informs a more cost effective design

later• Ensures unexpected rapid

breakthrough is not missed

3.

• Maximize the signal to noise ratio4. • Expect surprises – and plan for them5.

© Arcadis 2016

Five Easy Steps to Success• Inject Large Volumes1.• Do not skimp on the monitoring network 2. • Sample frequently early, and adapt3.

• Maximize the signal to noise ratio• Typically at least 1,000x• Look at background and interference

4.

• Expect surprises – and plan for them5.

© Arcadis 2016

Five Easy Steps to Success• Inject Large Volumes1.• Do not skimp on the monitoring network 2. • Sample frequently early, and adapt3.• Maximize the signal to noise ratio4.

• Expect surprises – and plan for them• Plan to be flexible• Leave contingency time and budget• Educate field staff

5.

Other Applications

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Tracer Applications

Applied Tracers

Drilling

3D Mapping

AS/SVE

LNAPL Mobility

Single Well Tracer Testing

Recirculation Systems

Capture Zone

Karst

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Drilling with Dye • With rotary drilling, cuttings removed

using water• Drilling water lost to formation

because of positive head• Conventional approach is to remove

an arbitrary volume of purge water prior to sampling

• Tracer can provide a basis based on field observations then to terminate purging

• Contaminant concentrations can be corrected due to dilution

2016, McCaughey et al., GWMR

FW = 1-(TGW/TDW)

FW – Formation WaterTGW – Tracer concentration in groundwaterTDW – Tracer concentration in drilling water

CC = CM/FW

CC – Corrected contaminant concentrationCM – Measured contaminant concentration

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y = 2.2879x1.6523

R² = 0.9464

y = 10.673x2.3403

R² = 0.8709

0.1

1

10

100

1000

10000

100000

1000000

0.1 1 10 100 1000 10000

RW

T C

once

ntra

tion

(ppb

)

Total Fluorescence Response (%)

Groundwater Samples on Clean Sand

Groundwater Sample on Site Soil

Maximum In-Situ Response vs. Grab GroundwaterSample Concentration

3D Mapping of Rhodamine WT with LIF

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Single-Well Tracer Testing to Measure Groundwater FluxAdd tracer to wells via recirculation –simple setup

Measure concentration in well over time• Rate of washout related to flow into well bore• Washout occurs in a few hours to a few days

Direct measure of flux

SOP and training webinar available

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Single-Well Tracer TestFractured Bedrock and Partially-Weathered Bedrock

PWR

Wel

ls

Bedr

ock

Wel

ls

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qa: 0.25-0.80 ft/yr

Estimated contaminant flux:1.0-3.2 g ft-2yr-1

Apparent qa: <0.02-0.07 ft/yr

Maximum potential contaminant flux0.003-0.02 g ft-2 yr-1

Single-Well Tracer TestFractured Bedrock and Partially-Weathered Bedrock

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LNAPL Mobility Assessment

Actual LNAPL Flux = 0.17 feet per year

• NAPL-soluble fluorescent tracer added to LNAPL in well

• Tracer decline related to LNAPL flux/mobility

• Measured LNAPL flux at 5 sites < 1 ft/yr

2016, Pennington et al., GWMR

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Capture Zone ConfirmationConversion from P&T to ERD (2003-2011)

Recurring source-zone ERD injections at ~15 injection wells

Rhodamine WT added (10 ppm) to injectate solution (molasses and water)

Tracer plume mapped through time and compared to hydraulic capture interpretation

20072003

20102009

2008

2011

Capture Zone

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Recirculation Tracer Tests Can provide data to: • Determine appropriate well spacing• Design extraction and injection wells• Determine sustainable recirculation rates • Measure hydraulic capture • Frequency of reagent dosing• Reagent concentrations

Upfront modeling to determine injection/extraction well spacing and likely breakthrough times is helpful

Establish steady state recirculation conditions

Dose injection line with tracer

Monitor breakthrough in extraction well

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Tracer Testing in Karst Settings

• Dye added to swallets and other karst features• Monitored with carbon “bugs”• Example: Karst Study in Tennessee

• Rapid movement through karst system (~4,000’ within 24 hours)• Positive traces for all 4 dyes• Flow across topographic watershed boundaries • Two separate conduit networks (Meades/No Name); not connected• GW flow SW to NE along strike within these networks

Karst Settings

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Learning ObjectivesAfter attending this session, participants should be able to:

Describe fluid transport in the subsurface during and injection

Describe the general information and insight gained from tracer testing

Plan a conceptual tracer test designed to support injected-fluid based IRZ design

Analyze typical tracer response data to calculate mobile porosity and groundwater flow velocity

Close and Contacts

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Who to Contact

Elizabeth Cohen Novi, MI

Aaron KempfHighlands Ranch, CO

Kim Heinze Highlands Ranch, CO

Jeff McDonoughNewtown, PA

Craig DivineWashington

DC

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About the Presenter

c 720 308 5367e craig.divine@arcadis.com

CRAIG DIVINE, PHD, PGSite Evaluation and Restoration, Leader – North America

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Arcadis.Improving quality of life.