Focus on Geology to Define Subsurface Migration Pathways Rick - - PowerPoint PPT Presentation

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Focus on Geology to Define Subsurface Migration Pathways Rick Cramer, MS, PG (Orange, CA) Mik Sh lt PhD (C Mike Shultz, PhD (Concord, CA) d CA) December 2, 2015 Outline Outline Introduction Why does geology matter? What is Environmental

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Focus on Geology to Define Subsurface Migration Pathways

Rick Cramer, MS, PG (Orange, CA) Mik Sh lt PhD (C d CA) Mike Shultz, PhD (Concord, CA)

December 2, 2015

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Outline Outline

Introduction Why does geology matter? What is Environmental Sequence Stratigraphy? Proof of concept Proof of concept The technology Case Studies

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Technology Established in the Oil Industry Technology Established in the Oil Industry

In the early days of exploration and production, once oil reservoir was discovered production was limited discovered, production was limited by facilities capacity (engineering focus). As technology improved and fields matured the “easy stuff” had been had been matured, the easy stuff

  • recovered. Problems such as

water production became critical. Understanding the geology and Understanding the geology and predicting reservoir architecture became increasingly critical for economical operations.

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Subsurface Heterogeneity and Groundwater Remediation Subsurface Heterogeneity and Groundwater Remediation

  • Historically, simplifying assumptions of

aquifer homogeneity and isotropy applied to designing and implementing groundwater remediation programs – the “water supply legacy”

  • While heterogeneity was recognized, it

was thought that we could “engineer around g geology” gy

Contaminant plume Groundwater gradient Contaminant plume

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Subsurface Heterogeneity and Groundwater Remediation Subsurface Heterogeneity and Groundwater Remediation

With heterogeneous geology groundwater flow may not match gradient and result in:

  • Off-gradient

contaminant migration

  • Poor

distribution of in situ reagents

  • Production of

byproducts byproducts during in situ injection

  • Poor pump-

and and-treat treat performance

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Why Geology Matters Why Geology Matters

  • At least 126,000 sites across the

U.S. have contaminated groundwater that requires remediation

  • Over 12,000 of these sites are

Over 12,000 of these sites are considered "complex"

  • “There is general agreement among

practicing remediation professionals practicing remediation professionals, however, that there is a substantial population of sites, where, due to inherent geologic complexities inherent geologic complexities, restoration within the next 50-100 years is likely not achievable.”

Alternatives for Managing the Nation's Complex Contaminated Groundwater Sites

National Academy of Sciences Committee on Future Options for Management in the Nation's Subsurface Remediation Effort, 2013

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Environmental Sequence Stratigraphy (ESS) Process Environmental Sequence Stratigraphy (ESS) Process

Borehole Log Borehole Log to to Graphic Grainsize Log Graphic Grainsize Log

Grain-size increasing Clay Gravel

Cross Section Map

100

Uncon

200 Depth (Ft - MSL)

1

300

Determine depositional Determine depositional environment which is the foundation to the ESS evaluation

Uncon

400

2

Leverage existing lithology Leverage existing lithology data to identify vertical grain size trends and correlate between boreholes

3

Map the permeability architecture to predict contaminant migration

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All sites currently have high resolution data… All sites currently have high resolution data…

Boring Logs CPT Logs Geophysical Logs …lithology data that is not being used to its full capacity.

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Environmental Sequence Stratigraphy (ESS) Environmental Sequence Stratigraphy (ESS)

Beauty of this approach is that the data are l d id f d th Oil I d t h already paid for and the Oil Industry has already invested billions in developing the t h l technology.

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Where is Environmental Sequence Stratigraphy applied? Where is Environmental Sequence Stratigraphy applied?

ESS

Fractured rock? Karst limestone? Clastic (sand/silt/clay mixtures) sedimentary deposits?

  • River deposits

River deposits

  • Desert systems
  • Coastal settings
  • Marine deposits
  • Glacial deposits

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Focus on geology improves site characterization throughout the remediation life cycle: the remediation life cycle:

  • Data gaps investigations, high-resolution site characterization

programs

  • Optimizing groundwater monitoring programs
  • Contaminant source identification for comingled plumes
  • Mass flux/mass discharge analysis (contaminant transport vs

contaminant storage zones)

  • In situ remediation (optimize distribution)

In situ remediation (optimize distribution)

  • Optimizing pump and treat programs
  • Alternative endpoint analysis

Alternative endpoint analysis

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Proof of Concept

Have successfully applied this technology to assess groundwater contaminant pathways at several Air Force facilities facilities. Base-Wide Conceptual Site Models

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Proposed EPA Ground Water Issue Paper on ESS Water Issue Paper on ESS

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OK, but what IS IT already? OK, but what IS IT already?

ESS is “Pattern Recognition”

  • Patterns in grain size are

the language of heterogeneity

  • Sequence Stratig

p raphers are the translators

  • Can correlate/predict

heterogeneity at all scales

  • There are grain size

There are grain size patterns buried within existing boring logs of every site

  • Experience and

d background of the practitioner is a prerequisite

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A lluvial Fan

... "'""

7

Meandering

Fluv ial

)

Braided

~

Fluvial

  • ffshore )

Near-

7

shore, deltaic Proximal fan channels, mid-fan sheet sands, distal fringe sands X: 102 m - 10' m Y : 101 m -

1 ~ m

Z: 10"1 m - 11Ysm Channel axial fill, point

bar, crevaeee e-playe-

X:1 m - 11Ys m

Y: 10' m- 10' m

Z:10"1 m - 10 m Channel axial fill, bar forms X:1 m - 11Ys m Y: 10 m - 102 m Z: 10"1 m - 1's m

Offshore bar,

transgressive sand X: 11Ys m - 102 m

Y: 10' m- 10' m

Z:10"1 m - 10 m Shoreface (beach}, or bayhead delta in upper part, shelf in low er parts

X: 10's m - 10' m

Y: 102 m -

1 ~ m

Z: 10"1 m - 10 m

Playa lake deposH s or paleosol formations commonly vertically separate fans. Debris-flow deposH s also commonly clay-rich

X: 10' m - 10' m Y: 10' m - 10' m

Z: 10"1 m - 11Ysm Floodplain deposH s, levee

depoe-ite, clay drapee- on

lateral accretion su

r fac

~ plugs filling abandoned channels

X: 10' m- 10' m Y: 10' m- 10' m

Z: 10"1 m - 11Ysm Floodplain deposH s, silt and clay plugs filling abandoned channels

X: 10' m - 10' m

Y : 1o· s m - 102 m Z: 10"1 m - 1's m

High-frequency

transgressive flooding shales X: 11Ys m - 102 m

Y: 10' m- 10' m

Z:10"1 m - 10 m High-frequency transgressive flooding shales

X: 10's m - 10' m

Y: 102 m -

1 ~ m

Z: 10"1 m - 10 m

Laterally extensive playa lake deposH s can missed by tradH ional sampling methods due to their thin nature, but can vertically compartmentalize aquifers. Fans have a primary stratigraphic dip basin w ard at 1-6 degrees, and are

laterally offset slacked (' shingled").

Due to w ell-sorted sand and gravel at bases

  • f channels, permeability can be
  • rdere o f magnitude higher in thie
  • zone. High riek of off e-ite contaminant

transport due to groundw ater flow controlled by channel orientation and not groundw ater gradient. Local groundwater flow up to 270 degrees from regional gradient. Channel-fills highly asymmetric w H h cutbank characterized by sharp erosional edge and point bar characterized by interfingering w H h floodplain fines impacting potential for contaminant mass storage. Lateral accretion drapes can separate point bar deposH s that w ould appear to be connected

  • laterally. Clay plugs filling abandoned oxbow lakes common.

" S tr

ea

~ groundwater flow wH h isolated high-permeability

  • zones. Overall high

permeability and porosity w H h amalgamated channel deposH

  • s. Local

groundw ater flow up to 90 degrees from gradient, but typically w H hin 45 degrees

  • f gradient

Laterally extensive, sand-rich deposH

  • s. lnterbedded storm deposH

s (coarser

grained} w H h fair-weather deposH s l(finer-grained} lead to high degrees

  • f

vertic al heterogeneity, and low to very low Kv/Kh ratio. Laterally extensive, sand-rich near-shore unH s in upper parts of sequences. High d egree of interbedding of coarse and fine-grained unH s in low er parts. Silt and clay beds capping sequences dip basinw ard, may lead to erroneous correlations at distances

  • f hundreds
  • f meters to kilometers.

High in vertical sense, medium to low in horizontal sense High both laterally and

vertically if e-ite e-ize ie

greater than channel w idths High, but dependent on degree of amalgamation

  • f channels

determined by fines content (greater fines content results in less channel connectivity}

Low in lateral sense, high

in vertical Low in lateral sense, high in vertical

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The Problem of Aquifer Heterogeneity The Problem of Aquifer Heterogeneity

  • Outcrop analog of meandering fluvial

deposits

  • At aquifer remediation site scale
  • Ability to explicitly map sand body

architecture in 3 dimensions

  • Facies Models provide predictive tool for

characterization based on depositional environments

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The Problem of Aquifer Heterogeneity The Problem of Aquifer Heterogeneity

10 m 250 m

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The Problem of Aquifer Heterogeneity The Problem of Aquifer Heterogeneity

10 m 250 m

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The Problem of Aquifer Heterogeneity The Problem of Aquifer Heterogeneity

10 m 250 m

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The Problem of Aquifer Heterogeneity The Problem of Aquifer Heterogeneity

1 2

10 m

3

m 250 m

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“Hidden” Stratigraphic Data Hidden Stratigraphic Data

  • “All we have are these lousy

USCS boring logs”

  • USCS is not a geologic

description of the lithology

  • Diff

l Different geologi ists

  • Different drilling methods
  • Different sampling intervals

Different sampling intervals

  • Etc…

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“Hidden” Stratigraphic Data Hidden Stratigraphic Data

  • Existing data is formatted for

stratigraphic interpretation

  • Reveals the “hidden”

stratigraphic information that is available with existing lithology available with existing lithology data

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“Hidden” Stratigraphic Data Hidden Stratigraphic Data

This SM interval is a fine to medium grained Silty Sand

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“Hidden” Stratigraphic Data Hidden Stratigraphic Data

This SM interval is a fine to coarse grained Silty Sand with gravel, representative of a channel deposit.

Both were logged as SM, but the details show that they have significantly different depositional they have significantly different depositional characteristics.

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The ESS Workflow in a Nutshell: The ESS Workflow in a Nutshell:

  • 1. Reformatting existing data to identify sequences, and
  • 2. Applying facies models, stratigraphic “rules of thumb” to correlate and

pp y g , g p map the subsurface, predict character of heterogeneity present

Fining-upward cycles indicative of channel-fills

Permeable streaks Permeable streaks commonly at bases

  • f channel complex

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Example from GW site in S. CA, USA

500 feet

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Mapped Sand Channels Mapped Sand Channels

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Mapped Sand Channels Mapped Sand Channels

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Case Study #1: In situ Bioremediation Case Study #1: In situ Bioremediation

Industrial Facility: Ethanol injection to reduce hexavalent chromium plume Scale: Hundred acres, ~60’ depth of investigation Lithology Data: CPT logs, borehole logs Approach: Apply ESS to explain Mn by-product Takeaway: Even with “high-resolution” lithology data, a depositional model is needed for successful remediation model is needed for successful remediation

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C i d

Case Study #1: In situ Bioremediation

Desert Systems: Alluvial Fans and Playa Lakes

  • Alluvial fan depositional

Case Study #1: In situ Bioremediation

Alluvial fan depositional model

  • Sand-rich, sheet-like

deposits deposits

  • Coarser at proximal reaches,

fining down fan

  • Coarsening upward

stratigraphic sequence as fans build out

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Surface dips of 2-6 degrees, steeper at proximal fan and decreasing down fan

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Case Study #1: In situ Bioremediation Case Study #1: In situ Bioremediation

Grain Size Trends in CPT Data

  • Site CPT data
  • Coarsening upward vertical

grain si e pattern grain-size pattern

  • Stacked alluvial fan

deposits bounded by clays deposits bounded by clays

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Case Study #1: In situ Bioremediation Case Study #1: In situ Bioremediation

Cross Section of Hydrostratigraphic Units (HSUs)

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Case Study #1: In situ Bioremediation Case Study #1: In situ Bioremediation

Kriging of CPT Data to Correlate Lithology

(Same cross section) Miscorrelates thin cla y beds g giving g appearance of pp randomness in stratigraphic architecture

West East

Brown = silt/clay White = sand/gravel

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Case Study #1: In situ Bioremediation Case Study #1: In situ Bioremediation

Conclusions

  • Saturated zone consists of

Saturated zone consists of discrete HSUs (sand-rich alluvial fans)

  • Stratigraphic dip of alluvial fan

units is responsible for preferential pathways, channelization is not the primary mechanism

  • Kriging correlations are not

representative of the stratigraphy

  • Not all fan units impacted;

injection into clean zones responsible for Mn byproducts

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Case Study #2: Plume Containment Strategy Case Study #2: Plume Containment Strategy

Munitions Manufacturing Site: Perchlorate plume impacting municipal wells Scale: Thousand acres, ~700’ depth of investigation Lithology Data: Geophysical logs, borehole logs Approach: Apply ESS on existing data to improve CSM and Design Plume Management Program Takeaway: Takeaway: Detailed stratigraphy has significant impact on remediation Detailed stratigraphy has significant impact on remediation design, project cost.

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Case Study #2: Plume Containment Strategy Case Study #2: Plume Containment Strategy

Site Overview

125’ t ti i t l 125’ extraction interval

Pre-Existing 3-Layer CSM

  • 996-acre (403-hectare) site

Santa Clarita, CA

  • Complex geology, over 600’ of

stratigraphy, dipping beds stratigraphy, dipping beds

  • Impacted mainly with

perchlorate (ClO4-), but locally CVOCs including TCE CVOCs, including TCE

  • AECOM awarded contract to

implement containment pilot study

  • Geologic setting, AECOM

expertise p promp pted CSM review

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Case Study #2: Plume Containment Strategy Case Study #2: Plume Containment Strategy

3-D ESS Cross Section Network Site-wide analysis for design of containment system Site wide analysis for design of containment system

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Case Study #2: Plume Containment Strategy Case Study #2: Plume Containment Strategy

ESS Process: Datum (flatten) Logs on Well-Defined Floodplain Unit

Major site-wide flood plain Major site wide flood plain deposit (low resistivity)

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Case Study #2: Plume Containment Strategy Case Study #2: Plume Containment Strategy

ESS Process: Correlate Floodplain Surfaces

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Case Study #2: Plume Containment Strategy Case Study #2: Plume Containment Strategy

ESS Process: Define Aquifer/Permeability Architecture Based on Stratigraphic Rules

Aquifer (Sands and Gravels) Aquitard (Clays and Silts) Transitional (Silty Sands, Sandy Silts)

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Case Study #2: Plume Containment Strategy Case Study #2: Plume Containment Strategy

ESS Process: Aquifer Architecture in Structural and Groundwater Flow Context

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Case Study #2: Plume Containment Strategy Case Study #2: Plume Containment Strategy

ESS Process: Identification of Breach of Floodplain Aquitard, Map Likely “Hot Zones”

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Case Study #2: Plume Containment Strategy Case Study #2: Plume Containment Strategy

ESS Process: Create 3-D ESS Stratigraphic Framework

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Case Study #2: Plume Containment Strategy Case Study #2: Plume Containment Strategy

ESS Process: Testing and Validating the CSM – Pathways and Communication

  • Aquifer tests were

performed sequentially, instead

  • f concurrently, to
  • f concurrently, to

avoid interference from different pumping wells

  • HSU designations

HSU designations, groundwater flow paths verified

Extraction in this zone

3.5’ drawdown, 2000 ppb

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30 $ 5

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Case Study #2: Plume Containment Strategy Case Study #2: Plume Containment Strategy

ESS Outcome: Overhauled CSM, verified CSM, gained regulatory and stakeholder approval for wholesale modification of containment system design = $55MM savings

Before ESS Before ESS After ESS

125’ extraction interval; includes non-impacted strata 35’ extraction interval; impacted strata only

Remediation System Cost (Before ESS)

  • 12 extraction wells
  • ~200 gpm per well

1 261 illi l

  • 1,261 million gal per year

Capital cost = $7 MM Treatment cost = $2.5MM/yr; 30 yr = $75 MM y Total cost = $82 MM Remediation System Cost (After ESS) 13 t ti ll

  • 13 extraction wells
  • 46 gpm per well
  • 314 million gal per year

Capital cost = $2.5MM p Treatment cost = $800K/yr; 30 yr = $24MM Total cost = $26.5 MM

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Takeaways Regarding ESS Takeaways Regarding ESS

Addresses Aquifer Heterogeneity with Existing Data

  • Existing data contain

important information and recognizable patterns

  • Low cost, very high

Return on Investment

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Questions & Answers Questions & Answers

Rick Cramer, M.S., P.G. Mike Shultz, PhD rick.cramer@aecom.com rick.cramer@aecom.com mike.shultz@aecom.com @ (714) 689-7264 (925) 446-3841

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