Characterizing the Contaminant Mass in the Rock Matrix

USEPA-USGS Fractured Rock WorkshopEPA Region 2

14 January 2014

Daniel Goode and Tom Imbrigiotta, USGS

Why Delineate CVOCs in Matrix? Rock Core Sampling for CVOCs

Synthesis with Other Characterization Case study Commercial Vendor

Outline

2Characterizing Contaminant Mass in the Rock Matrix

Phase of CVOC (aqueous, sorbed, DNAPL) can strongly impact remediation

Rock Core sampling shows most CVOC mass in or on rocks, not in flowing water

Monitoring well concentrations are a mixture of flowpaths, only for aqueous phase

Why Delineate CVOCs in Matrix?

3Characterizing Contaminant Mass in the Rock Matrix

Fine-scale CVOC distribution important for optimization of remediation

Bioaugmentation amendments limited to thin permeable strata from injection well

Back-diffusion and de-sorption from rock matrix slows remediation

Why Delineate CVOCs in Matrix?

4Characterizing Contaminant Mass in the Rock Matrix

Characterizing Contaminant Mass in the Rock Matrix 5

Rotary Coring – best method for collecting undisturbed cores; some polymer added to help remove cuttings; minimal chemical effects Triple barrel (inner split barrel) helps reduce core

distrubance Sonic Coring – can be used, but not preferred since it

creates new fractures; high-pressure water introduced to remove cuttings, probable chemical effects

Rock Coring Methods

Characterizing Contaminant Mass in the Rock Matrix 6

Developed from sediment coring and methanol extraction technologies

A “bulk” analysis, includes all CVOC phases in sample Initial applications and refinement by Beth Parker, John

Cherry, and colleagues (e.g. Sterling, et al., 2005) Parker’s Trademarked “COREDFN” approach licensed to

Stone Environmental Stone Environmental and/or Beth Parker’s group (now at

Guelph U., Canada) have worked on many EPA sites USGS began using similar methods in 2001 (e.g. Sloto,

2002)

Analysis of Rock Core for CVOCs

15BR

71BR70BR

73BR

36BR

25BR

56BR

82BR

81BR

Case study example application: NAWC, NJ

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Characterizing Contaminant Mass in the Rock Matrix 8

DNAPL screening during coring – Hydrophobic-Dye Cloth (FLUTe)

Rock Core VOC sampling and analysis (Sterling, Parker, Cherry and others 2005)

Methods

Characterizing Contaminant Mass in the Rock Matrix 9

5-ft core in PVC trough prior to sub-sampling. Sledge hammer, chisels, jars, zip-loc bags on hand. Sampler wearing nitrile gloves.

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Core length is measured.

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Chisel and hammer used to cleave off a section of core ½ to 1 inch thick.

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First sample placed in crusher cup. Crushed immediately.

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Additional samples from same core wrapped in aluminum foil and stored in zip-loc bags until they can be crushed. Septa jars labeled the same as the bags.

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Typical 5-ft core with wooden spacers labeled and placed in the spaces where the core sub-samples were obtained.

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Rock Crusher

Hydraulic ram

Pressure gauge

Crusher cup

Crusher puck

Hand pump

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Rock crusher in use. Extra rock core samples being saved. In background, core being stored in core boxes and field lab vehicle with scale to weigh bottles containing core samples and methanol.

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Adding 50 mLs of methanol to the bottle containing the crushed rock core sample using the dispenser.

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Crusher cup, crusher puck, spatula, chisel cleaning buckets – 1 tap water, 2 tap water rinse, 3 deionized water rinse.

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Rock Core TCE (black, top)

TCE in all but 1 sample < 15 m

Non-detect in most samples > 15 m

Aqueous TCE (blue, bottom) less variable than core

DNAPL detected at 27 m during coring (after >12 years of P&T)

Results70BR

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Optical Televiewer – Color lithology

High-carbon Black fissile strata

Gray laminated strata

Light-gray massive strata

Results 70BR

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Acoustic Caliper

Highly fractured shallow weathered zone

Isolated fractures below 15 m depth in Black, and other, strata

Results 70BR

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Transmissivity from Borehole Flowmeter Johnson & Anderson

Several high-T zones 7-15 m depth

Isolated high-T zones below 15 m

DNAPL detected at 27 m during coring (after >12 years of P&T)

Results 70BR

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TCE & DCE in 3 Coreholes

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Characterizing Contaminant Mass in the Rock Matrix 25

Parker’s Trademarked “COREDFN” approach licensed to Stone Environmental

Stone Environmental and/or Beth Parker’s group (now at Guelph U., Canada) have worked on several sites

Parker and colleagues continue to refine methods E.g. Microwave heated methanol extraction (speeds

analysis) & vacuum-sealed crusher (reduces VOC loss prior to extraction)

Commercial Vendor Available

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CVOCs in Crystalline Rock

Shenandoah Road Groundwater Contamination Superfund Site, East Fishkill, NY

Ref: Feenstra, 2012

Rock Core PCE (ug/kg)

Physical Props. samples

X – Highly fractured on geol. log

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Characterizing Contaminant Mass in the Rock Matrix 28

Aqueous Concentrations in Equilibrium with Sorbed Phase

Back Diffusion AND De-Sorption Control Long-Term Attenuation

Ref: Feenstra, 2012

Long-term CVOCs in groundwater at many fractured-rock sites controlled by gradual release from rocks (diffusion, sorption, etc.)

Rock Core Sampling for CVOCs Represents pre-drilling distribution (mediates open-

hole effects) Synthesis with Other Characterization !!

Commercial Vendor available Becoming more widely applied as part of

Superfund program

Take Home

29Characterizing Contaminant Mass in the Rock Matrix

Characterizing Contaminant Mass in the Rock Matrix 30

Stop here.

Following slides included in handouts

Thank YouPierre Lacombe

Allen ShapiroClaire Tiedeman

Alex FioreSteven Walker

Matt Miller& others . .

Toxic Substances Hydrology ProgramNew Jersey Water Science CenterHydrologic Research & Development ProgramOffice of Ground WaterNational Assoc. Geoscience Teachers/USGS Intern Program

Office of Superfund Remediation and Technology Innovation

Naval Facilities

Engineering Command

nj.usgs.gov/nawc

Rock Core sampling shows most CVOC mass in or on rocks, not in flowing water

TCE > DCE in nearly all rock core samples CVOCs below detection in most samples below

weathered zone (15 m) Very high CVOCs in deep rock core at isolated

permeable features, often in Black (organic carbon) strata

DNAPL detected at depth of Black strata during coring

Rock Core Sampling Results

32Characterizing Contaminant Mass in the Rock Matrix

Dilution of aqueous concs. by fresh recharge DCE > TCE in many wells: Natural

biodegradation ongoing TCE > DCE in nearly all rock core Back diffusion and de-sorption from CVOCs

throughout the rock matrix Gradual decline in CVOCs in time But, high CVOCs remain near residual sources

Depth- & Strata-Dependent DelineationShallow Weathered & Highly Fractured Strata

33Characterizing Contaminant Mass in the Rock Matrix

High CVOCs (TCE > DCE) associated with permeable strata, many in high-carbon “Black” strata

Most rock core samples below detection: Limited diffusion into rock matrix

Probable sorption to rock organic carbon TCE > DCE in most deeper wells: Less natural

degradation or residual TCE source DNAPL detected during coring @ 27 m more than

12 years after P&T began

Depth- & Strata-Dependent DelineationDeeper Un-Weathered Strata

34Characterizing Contaminant Mass in the Rock Matrix

MNA and P&T are likely to continue to decrease CVOC concentrations in shallow monitoring wells, but only gradually

Deep contamination is isolated near permeable fractures, dominated by TCE

Little matrix diffusion in deeper unfractured strata, sorption may be more important

Treatment may be optimized to treat near-fracture rocks Existing DNAPL likely to persist without aggressive

treatment

Implications for Remediation

35Characterizing Contaminant Mass in the Rock Matrix

Feenstra, Stanley, 2012, Matrix diffusion studies at the Shenandoah Road Groundwater Contamination Superfund site: Applied Groundwater Research Ltd. DRAFT Report provided by EPA, 178 p.

Goode, D.J., Imbrigiotta, T.E., Lacombe, P.J., Tiedeman, C.R., Walker, Steven, and Miller, M.A., 2011, Changes in distribution of trichloroethene and other contaminants in fractures and the rock matrix during bioaugmentation at NAWC: (abs.) SERDP/ESTCP Proc. Partners In Environmental Technology Technical Symposium and Workshop, Washington, D.C., Nov. 30 – Dec. 2. (2011 Program Guide PDF at serdp.org)

Goode, D.J., Imbrigiotta, T.E., and Lacombe, P.J., 2014 (in review), High-resolution delineation of chlorinated volatile organic compounds in a dipping, fractured mudstone: Depth- and strata-dependent spatial variability from rock-core sampling: in review.

Sterling, S. N., Parker, B. L., Cherry, J. A., Williams, J. H., Lane, J. W., Jr., Haeni, P. F., 2005, Vertical cross contamination of Trichloroethylene in a borehole in fractured sandstone, Ground Water, vol. 43, no. 4, p. 557-573.

Sloto, R. A., 2002, Hydrogeological Investigation at Site 5, Willow Grove Naval Air Station/Joint Reserve Base, Horsham Township, Montgomery County, Pa., USGS WRIR Report 01-4263, 37 p.

References

36Characterizing Contaminant Mass in the Rock Matrix