[PPT] - FRACTURED BEDROCK CHARACTERISATION AND EFFECTIVE REMEDY SELECTION IN PowerPoint Presentation

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FRACTURED BEDROCK CHARACTERISATION AND EFFECTIVE REMEDY SELECTION IN REGION 4 BEN BENTKOWSKI, P.G. EPA REGION 4

11/2/2010 EPA Region 4 Perspective 1

SLIDE 2

Presentation Outline

 Region 4’s area with Fractured Bedrock Aquifers  Examples of three kinds of aquifers

 Fractured Metamorphic  Fractured Igneous  Fractured Sedimentary

 Characterization and Remediation

 Five Federal Facilities  Four Non-Federal Facilities

 Summary and Conclusions

11/2/2010 EPA Region 4 Perspective 2

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11/2/2010 EPA Region 4 Perspective 3

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11/2/2010 EPA Region 4 Perspective 4

Fractured Metamorphic Rock

Lawrenceville, GA

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11/2/2010 EPA Region 4 Perspective 5

Fractured Igneous Rock

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Fractured Sedimentary Rock

West Trenton, NJ Manchester, TN

11/2/2010 EPA Region 4 Perspective 6

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11/2/2010 EPA Region 4 Perspective 7

Air Force Plant No. 6 - Marietta, GA Fractured Metamorphic Rock - Piedmont

Site Map

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Air Force Plant No. 6 - Marietta, GA Fractured Metamorphic Rock - Piedmont

 Airplane Assembly since WWII  Multiple Solvent Releases  Detailed Characterization  Groundwater contamination in saprolite, partially

weathered rock (PWR) (together considered the

verburden aquifer) and bedrock (BR)

 Dissolved Phase and DNAPL

 Most recent report – (third) Annual Corrective Action

Effectiveness Report - RCRA

11/2/2010 EPA Region 4 Perspective 8

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11/2/2010 EPA Region 4 Perspective 9

Air Force Plant No. 6 - Marietta, GA Fractured Metamorphic Rock - Piedmont

Characterization included:

 Bedrock cores and thin section analysis (gneiss v. schist)  Borehole geophysics  PWR aquifer test - one connected anisotropic aquifer

but with differing properties

 Site-wide water level gauging and gradient analysis

suggesting less flow in BR

 Extensive soil and groundwater sampling  Conceptual Site Model development

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10 11/2/2010 EPA Region 4 Perspective

Air Force Plant No. 6 - Marietta, GA Fractured Metamorphic Rock - Piedmont

Hydrogeology Conceptual Site Model DNAPL Conceptual Site Model

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11/2/2010 EPA Region 4 Perspective 11

Air Force Plant No. 6 - Marietta, GA Fractured Metamorphic Rock - Piedmont

Conceptual Site Model

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11/2/2010 EPA Region 4 Perspective 12

Air Force Plant No. 6 - Marietta, GA Fractured Metamorphic Rock - Piedmont

TCE in the Overburden Aquifer

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11/2/2010 EPA Region 4 Perspective 13

Air Force Plant No. 6 - Marietta, GA Fractured Metamorphic Rock - Piedmont

TCE in the Bedrock Aquifer

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11/2/2010 EPA Region 4 Perspective 14

Air Force Plant No. 6 - Marietta, GA Fractured Metamorphic Rock - Piedmont

REMEDIAL TECHNOLOGIES SELECTED

Air Sparge/Soil Vapor Extraction in Overburden Aquifer and Vadose Zone In-Situ Chemical Oxidation in Overburden Aquifer Microbiological Enhancement with Microbes Permeable Reactive Barrier Monitored Natural Attenuation Land Use Controls

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11/2/2010 EPA Region 4 Perspective 15

Air Force Plant No. 6 - Marietta, GA Fractured Metamorphic Rock - Piedmont

GOALS: Reduce Mass Flux and Offsite Migration & Facilitate MNA

This is happening but offsite investigation handled by different contractor

TIMEFRAME: Estimated for Overburden, not for Bedrock aquifer NOTE: No treatment of DNAPL in the fractured bedrock

“It is important to emphasize that the presence of residual DNAPL does not impact the conclusions of the RA (risk assessment) and the recommendations for site risk management.”

Final Corrective Action Plan, p. 2-5

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11/2/2010 EPA Region 4 Perspective 16

Alabama Army Ammunition Plant - Childersburg, AL Fractured Sedimentary Rock

 Located 40 miles southeast of Birmingham, AL  Operated 1941 -1945 manufacturing TNT, DNT  Approximately 5,000 acres  Standby 1946 – 1973 and declared excess  Property no longer owned by Army  CERCLA investigations started in the 1980s  Source Control - 120,000 cubic yard soil incineration

1994-97

 2010 - Final Soils ROD  Groundwater RI completed 2010

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11/2/2010 EPA Region 4 Perspective 17

Alabama Army Ammunition Plant - Childersburg, AL Fractured Sedimentary Rock

Broad expanse of Knox

Formation, carbonates

Thrust sheets evidence

tectonic activity resulting in significant fractures

Adjacent to Coosa River

whose course is fracture controlled

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Alabama Army Ammunition Plant - Childersburg, AL Fractured Sedimentary Rock

MAIN MANUFACTURING AND STORAGE AREA I nvest i gat ed wi t h t r adi t i

nalbi

ased/ hotspotm et hods butdi d notpr

vi

de accept abl e gr

undwat

erchar act er i zat i

n

11/2/2010 EPA Region 4 Perspective 18

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Alabama Army Ammunition Plant - Childersburg, AL Fractured Sedimentary Rock 2003 - 2009 GW Investigation

Bedrock Focus
Fracture Trace Analysis
Resistivity Surveys
Focused Drilling for bedrock wells
n fractures/conduits
18 of 19 drilled on fractures
Central facility v. exit pathway wells
Thermal survey along river confirmed exit points
To complete RI, characterization approach required focus on

the fractured nature bedrock

With source removed, bedrock GW now demonstrated to be

relatively minor problem

11/2/2010 EPA Region 4 Perspective 19

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11/2/2010 EPA Region 4 Perspective 20

Redstone Arsenal - Huntsville, AL Fractured Sedimentary Rock

 38,300 acres just west of Huntsville, AL  1,841 acre Marshall Space Flight Center within

Redstone Arsenal property

 158 active IRP sites, 20 surface media OUs, 13 GW

investigation areas

 Finalized on NPL in 1994  COCs – solvents, metals, pesticides, perchlorate &

chemical weapons material

 Karst hydrogeology with fractured bedrock influence

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11/2/2010 EPA Region 4 Perspective 21

Redstone Arsenal - Huntsville, AL Fractured Sedimentary Rock

 Structural setting –horst

and graben

 Dipping limestones  Thermal imaging of springs  Coring, hydro-physics,

flute wells

 Complicated groundwater

chemistry with salt water and natural oil at depth

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Redstone Arsenal - Huntsville, AL Fractured Sedimentary Rock

Local Conceptual Hydrogeologic Model Ar ea- wi de Concept ualHydr

geol
gi

calM odel

Figures from MSFC reports 11/2/2010 EPA Region 4 Perspective 22

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Redstone Arsenal - Huntsville, AL Fractured Sedimentary Rock

C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! ! C ! ! ! C ! ! ! ! ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! ! ! ! C ! C ! C C C C ! ! C ! C ! C ! C ! C ! C C C C ! C C ! ! C ! C ! C ! C ! C ! C !! C! C ! C ! C ! C C C C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! ! C ! C ! C ! C ! C C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C ! C

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11/2/2010 EPA Region 4 Perspective

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23

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11/2/2010 EPA Region 4 Perspective 24

Oak Ridge Reservation, Oak Ridge, TN Anniston Army Depot, Anniston, AL Fractured Sedimentary Rock

 Very large, very complex sites in Valley and Ridge  Hydrogeology is a blend of fractured due to tectonic

activity and karst due to carbonates

 Both facilities have performed source

control/removals and interim actions for receptor protection

 Neither have final groundwater remedies for their

largest releases

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11/2/2010 EPA Region 4 Perspective 25

J. P. Stevens Facility- Upstate South Carolina

Fractured Metamorphic Rock – Piedmont with Igneous Intrusions Source Area (Tank Farm)

Overall, much smaller scale of release & remedial action BUT uses broad range of characterization techniques COCs – Benzene, Chlorobenzene Cis-1,2-DCE, Vinyl Chloride

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J. P. Stevens Facility- Upstate South Carolina

Fractured Metamorphic Rock – Piedmont with Igneous Intrusions

CHARACTERIZATION and FINDINGS

 Regional recon and outcrop mapping – site at edge of thrust

sheet

 Lineament studies and rose diagrams  Trenching perpendicular to creek and structural dip – detailed

logging

 Found series of intrusive dikes in soil/saprolite  Used structural information to predict anisotropy and

design aquifer characterization

11/2/2010 EPA Region 4 Perspective 26

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11/2/2010 EPA Region 4 Perspective 27

J. P. Stevens Facility- Upstate South Carolina

Fractured Metamorphic Rock – Piedmont with Igneous Intrusions

 Membrane Interface Probe used in Source Areas  Cored bedrock with packer and analytical tests on

fracture features

 Bedrock aquifer test – 60 GPM with minimal drawdown

(14 GPM Steady State P&T)

 Capture zone analysis using simplified three layer model  Ozone sparging source control/treatment  Groundwater recovery system – plume migration

control

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11/2/2010 EPA Region 4 Perspective 28

J. P. Stevens Facility- Upstate South Carolina

Fractured Metamorphic Rock – Piedmont with Igneous Intrusions

GW Flow direction Baseline conditions After 90 and 200 days

Ozone Air Sparge Progress

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J. P. Stevens Facility- Upstate South Carolina

Fractured Metamorphic Rock – Piedmont with Igneous Intrusions

Why was Ozone Sparging Successful at J.P. Stevens?

 Sparge and multi-level injection points enhance shape

f area of influence

 Monitoring of indicator parameters (ORP, DO)

substantiated ozone was impacting groundwater

 Good interconnection between saprolite and bedrock  Multiple depths of injection and monitoring  Well-designed pilot study

 Length of monitoring before, during, and after  Spacing of monitoring points

11/2/2010 EPA Region 4 Perspective 29

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11/2/2010 EPA Region 4 Perspective 30

Hitachai - Greenville, SC Fractured Metamorphic Rock

 Release of 12,000+ lbs of TCE  This remedial action employed

In-Situ Thermal Desorption in soils and shallow bedrock

 14 Heater wells (~90’ bls)  10 Heater vacuum points (~95’

bls)

 2 Recovery wells (~45-76’ bls)

 recovered 72,000 gallons of

water during operation before water became steam

Ther m alTr eat m entAr ea 33’ x76’ x90’deep PW R at55’

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11/2/2010 EPA Region 4 Perspective 31

Hitachai Greenville, SC Fractured Metamorphic Rock

BEFORE AFTER Note: treatment zone only 2,500 ft2

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Hitachai Greenville, SC Fractured Metamorphic Rock

11/2/2010 EPA Region 4 Perspective 32

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Hitachai Greenville, SC Fractured Metamorphic Rock

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11/2/2010 EPA Region 4 Perspective 34

Hitachai Greenville, SC Fractured Metamorphic Rock

 Removed about 12,000 lbs TCE (~5 months operation)  Met treatment goals for vadose zone soil

 Goal was 60 ug/kg TCE  Attained 13.41 ug/kg TCE (UCL)  Overall soil (vadose and subaqueous) 17.05 ug/kg TCE

 Initial reductions of 75% to 99% of TCE in groundwater  Rebound noted (DNAPL; Fractures, Relic Fractures, Back-

Diffusion)

 Longer treatment period required for more bedrock

improvement

 Progress towards but not the Final Remedy

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Fractured Metamorphic Bedrock

 Historical solvent release managed with shallow SVE

and ozone treatment in nearby springs – interim remedy

 Ongoing investigation focused on facility and

generally shallower portions of bedrock aquifer

 Private deep bedrock drinking water supply wells

contaminated up to 1 mile away

 Detailed geological mapping by State Geologic Survey  Detailed hydrogeological characterization by USGS

11/2/2010 EPA Region 4 Perspective 35

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11/2/2010 EPA Region 4 Perspective 36

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Fractured Metamorphic Bedrock

 Historical site understanding focused investigation

topographically downgradient and shallower

 Employed sophisticated characterization techniques to

understand possible connections between solvent releases and contaminated private drinking wells

 Deepest contaminated well discovered to date - 700’

deep

 Recent characterization work will guide future work

with a much improved conceptual site model. However, it does not represent an easy path forward.

11/2/2010 EPA Region 4 Perspective 37

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11/2/2010 EPA Region 4 Perspective 38

Actual Example of Poor Characterization Fractured Rock – North Carolina Piedmont

 One well with 50’ open hole completion in bedrock with DNAPL

solvents

 Two analytical data points -1 set of three diffusion bag samplers and 1

sample collected 6 months later by low flow purge

 Proposed one well pilot study - Enhanced Reductive Dechlorination

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11/2/2010 EPA Region 4 Perspective 39

Actual Example of Poor Characterization Fractured Rock – North Carolina Piedmont

Just a Few of the Problems with This Approach

 Contamination not delineated  No surveys to identify fractured zones  No other proposed monitoring wells  Pilot Study would invalidate the use of this one well as a

monitoring location

 No demonstration of how this well relates to the rest of

the site or how this test would benefit the rest of the site

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11/2/2010 EPA Region 4 Perspective 40

SUMMARY EPA Region 4 Perspective

FEDERAL FACILITIES

 Large facilities, Large number of releases, Large volume of

releases

 Applying a wide range of increasingly sophisticated

characterization technologies

 Performing source removal, source control and receptor

protection

 Final groundwater remedies - uncommon  Deep fractured bedrock remediation - no final answer YET

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11/2/2010 EPA Region 4 Perspective 41

SUMMARY EPA Region 4 Perspective

Non-Federal Facilities

 Smaller facilities and smaller releases  Also applying a wide range of increasingly sophisticated

characterization technologies

 Appear to have made more progress

 Smaller problems, smaller solutions  different motivation - Industry v. Federal

 Deep fractured bedrock remediation – no final answer YET

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11/2/2010 EPA Region 4 Perspective 42

CONCLUSIONS This Hydrogeologist’s Perspective

Last 20 years have made great advances in types and sophistication of characterization.

 Focus on flow zones and geophysics/sensors

Biggest number of unresolved sites have dissolved or DNAPL solvents in fractured bedrock. At a basic level, it still a question of really understanding the nature and extent of the contamination and how that affects the selection of an effective remedy.

SLIDE 43

CONCLUSIONS This Hydrogeologist’s Perspective

 Good progress on remediating saprolite and partially

weathered bedrock

 Fractured Bedrock and Solvents

 No cure for this problem yet  Difficult and expensive to characterize flow pathways at depth  Back diffusion and time (cost) to remediate – biggest

impediments

Ultimate Goal The MCL CONCENTRATION

∞

11/2/2010 EPA Region 4 Perspective 43