Autopsy of a Small UST Site in Bedrock: Autopsy of a Small UST Site - - PowerPoint PPT Presentation

▶
autopsy of a small ust site in bedrock autopsy of a small
SMART_READER_LITE
LIVE PREVIEW

Autopsy of a Small UST Site in Bedrock: Autopsy of a Small UST Site - - PowerPoint PPT Presentation

Jul 15, 2023 317 likes •1.01k views

Autopsy of a Small UST Site in Bedrock: Autopsy of a Small UST Site in Bedrock: Implications for Remedial Effectiveness Implications for Remedial Effectiveness Case Study, Devens, MA Case Study, Devens, MA William C. Brandon, Hydrogeologist,

slide-1
SLIDE 1

Autopsy of a Small UST Site in Bedrock: Implications for Remedial Effectiveness

Case Study, Devens, MA

Autopsy of a Small UST Site in Bedrock: Implications for Remedial Effectiveness

Case Study, Devens, MA

Federal Remediation Technology Roundtable Meeting Characterization and Remediation

  • f Sites with Fractured Bedrock

Washington, DC November 9, 2010 Federal Remediation Technology Roundtable Meeting Characterization and Remediation

  • f Sites with Fractured Bedrock

Washington, DC November 9, 2010 William C. Brandon, Hydrogeologist, US EPA Region 1 William C. Brandon, Hydrogeologist, US EPA Region 1

slide-2
SLIDE 2

Acknowledgements

  • Gannet Fleming Inc.
  • Army BRAC Office
  • HGL Inc.
  • EPA Region 1 Federal Facilities
  • EPA Region 1 OEME
  • Mass Development
slide-3
SLIDE 3

Geologic Setting

SITE

slide-4
SLIDE 4

Site Location

SITE

slide-5
SLIDE 5

Site Geology

Modified from Kopera, 2008 SITE

slide-6
SLIDE 6

Geologic History

  • Silurian metasediments
  • Intrusion of Ayer Granodiorite (Devonian)
  • Intrusion of Chelmsford Granite (later

Devonian)

  • Deformation, faulting, metamorphism
  • Quaternary glaciation and de-glaciation

– Unloading, development of sheeting fractures – Deposition of outwash sand, gravel

slide-7
SLIDE 7

DRMO Site Plan

Source Area MW (Shallow Bedrock)

slide-8
SLIDE 8

POL Site Plan

slide-9
SLIDE 9

DRMO Site History

  • Defense Reutilization and Marketing Office (DRMO)

– Equipment Recycling ~ 1964-1995 – 5000 gal Waste Oil UST

  • UST removed 1992
  • Limited soil removal (tank grave partially in BR)
  • COCs: TCE, DCB, VPH, As, Mn
  • 1998-1999; LTMP (V_1.0) Initiated
slide-10
SLIDE 10

DRMO LTM Network Pre-2000

32M-92-06X

slide-11
SLIDE 11

COC Trends (Pre-2000)

3 2 M - 9 2 -0 6 X

2 00 4 00 6 00 8 00 1 0 00 1 2 00 1 4 00 1 6 00 N

  • v
  • 9

2 F e b

  • 9

3 M a y

  • 9

3 A u g

  • 9

3 N

  • v
  • 9

3 F e b

  • 9

4 M a y

  • 9

4 A u g

  • 9

4 N

  • v
  • 9

4 F e b

  • 9

5 M a y

  • 9

5 A u g

  • 9

5 N

  • v
  • 9

5 F e b

  • 9

6 M a y

  • 9

6 A u g

  • 9

6 N

  • v
  • 9

6 F e b

  • 9

7 M a y

  • 9

7 A u g

  • 9

7 N

  • v
  • 9

7 F e b

  • 9

8 M a y

  • 9

8 A u g

  • 9

8 N

  • v
  • 9

8 D a te Concentration (ug/l) 1 ,2- D C B 1 ,4- D C B 1 ,3- D C B T C E 3 2 M - 9 2 - 0 6 X

2 4 3 2 4 4 2 4 5 2 4 6 2 4 7 2 4 8 2 4 9 2 5 0 N

  • v
  • 9

2 F e b

  • 9

3 M a y

  • 9

3 A u g

  • 9

3 N

  • v
  • 9

3 F e b

  • 9

4 M a y

  • 9

4 A u g

  • 9

4 N

  • v
  • 9

4 F e b

  • 9

5 M a y

  • 9

5 A u g

  • 9

5 N

  • v
  • 9

5 F e b

  • 9

6 M a y

  • 9

6 A u g

  • 9

6 N

  • v
  • 9

6 F e b

  • 9

7 M a y

  • 9

7 A u g

  • 9

7 N

  • v
  • 9

7 F e b

  • 9

8 M a y

  • 9

8 A u g

  • 9

8 N

  • v
  • 9

8 GW Elevaton (famsl) W L

No Data No Data

slide-12
SLIDE 12

Site History (Part II)

  • Warehouse Construction Results in large-scale site alterations

(2000-2001) – Bedrock Blasting/Cut-and-fill – Engineered Drainage (Storm sewers, Detention Basin) – Extensive area of impervious surface (Building, Parking lots)

  • Site Hydrology Profoundly Altered
  • 2001-2002; LTMP Revised (v.2),

– Numerous new monitoring wells installed. – New baseline – Ongoing LTM and data evaluation (2002-2006)

slide-13
SLIDE 13

Site: Pre-construction (March 2000)

slide-14
SLIDE 14

Pre-Blast Bedrock Exposures at SE Corner of Building Area

slide-15
SLIDE 15
slide-16
SLIDE 16

Fill Emplacement SW of Building Footprint

slide-17
SLIDE 17

Storm Drain Installation

slide-18
SLIDE 18

Subsurface Utilities

slide-19
SLIDE 19

LTM/CSM Issues (2002-2006)

  • “Moving Target” - Site Hydrology Slowly Evolving Post-

Construction

  • Few COCs identified at POL after 2002, but
  • “Down-gradient” directions uncertain
  • Persistent Contamination in UST-13 Area
  • Bedrock Affected, but Fracture Network not evaluated
  • Adequacy of LTM network called into question
slide-20
SLIDE 20

Near-Term Objectives

  • Detailed evaluation of bedrock structural data from
  • utcrop mapping
  • Update CSM (Consensus)

– Bedrock Surface Map – Bedrock Fracture Data – Ground Water Flow Gradients

  • Lateral/vertical
  • Source Areas/Downgradient of Source Areas
  • Long-term water level trends

– Configuration of Subsurface Hydrostratigraphic Units (2D/3D) – Detailed cross sections through each source area normal and parallel to hydraulic gradient

  • Identify Data Gaps
  • Recommend Adjustments to GW Monitoring Network
slide-21
SLIDE 21

Longer-term Objectives

  • Install New Monitoring Wells
  • Decommission Unnecessary Wells
  • New Baseline; Re-initiate Long-term

Monitoring

  • Evaluate time-series contaminant trends
  • Determine whether additional remedial

measures are needed

  • Site Closeout
slide-22
SLIDE 22

Site Plan with Existing Monitoring Well Locations

Source: MACTEC, 2006

slide-23
SLIDE 23

Elements of Bedrock Evaluation

  • Configuration of top-of-bedrock surface
  • Geologic Mapping
  • Rock Type Identification
  • Foliation orientation Data
  • Joint Orientation Data
  • Structural Analysis

– Stereo-net analysis – Joint/Fracture Mapping

slide-24
SLIDE 24

Bedrock Elevation (Pre-Blast)

slide-25
SLIDE 25

Elevation of Bedrock Surface (Post-Blast)

Source: MACTEC, 2006

slide-26
SLIDE 26

Major Rock Types

  • Berwick Formation (S-O)

– Thick-bedded to massive Metaconglomerates, cg conglomeratic quartzite, fg feldspathic biotitic quartzite – Thinly bedded to massive dark gray to brown calcareous and phyllitic siltstones and mg feldspar-qz-biotite schist

  • Ayer Granite

– Devens Long-Pond Facies – Massive gneissic equigranular to porphyroblastic biotite granite and granodiorite

slide-27
SLIDE 27

Site Geology

Modified from Kopera, 2008

slide-28
SLIDE 28

Bedrock Geologic Map of the Shepley’s Hill Landfill Area

Source Harding ESE, 2003

slide-29
SLIDE 29

Blasting Presents Fresh Exposures

slide-30
SLIDE 30

Overview of Locations Where Structural Data Was Collected

slide-31
SLIDE 31

Foliation

  • Primary layering in metamorphic rocks
  • Generally follows compositional layering
  • Consistent orientation at site-scale
  • Local evidence of minor folding
slide-32
SLIDE 32

Stereoplot of Foliation Orientations

N=49 Strike ~ N3 Dip ~ 52 W

slide-33
SLIDE 33

Plan View of Foliation Data NE Corner of Building

slide-34
SLIDE 34

Plan View of Foliation Data SE Corner of Building

slide-35
SLIDE 35

Stereoplot of Foliation indicating Fold Axis

Azimuth ~ N21E Plunge ~ 40

slide-36
SLIDE 36

Joints

  • Generic Term for Planar discontinuity in

Rock Mass (e.g., crack)

  • Open joints may transmit water (oxidation)
  • Greater Variability than Foliation
slide-37
SLIDE 37

Intersecting Joint Sets

slide-38
SLIDE 38

Stereo-plot of Joint Orientations

N=156 66 stations

slide-39
SLIDE 39

Major and Minor Joint Sets

– N3E +/-, 50-60 W (parallel to foliation) – N45E +/-, 65-85 SE – Near-surface sheeting joints at various

  • rientations, Sub-parallel to former

topography – ~ N70W, Subvertical (weak) – ~ N30W, > 70-80 SE or SW Dips (weak)

slide-40
SLIDE 40

Interpretive Overburden Groundwater Surface Map, October 7, 2004

Source: MACTEC, 2006

slide-41
SLIDE 41

Interpretive Bedrock Groundwater Surface Map, October 7, 2004

Source: MACTEC, 2006 BR GW Divide Down-Dip Smear Zone?

slide-42
SLIDE 42

N-S Hydrogeologic Cross Section – UST 13

slide-43
SLIDE 43

W-E Hydrogeologic Cross-Section UST 13 Area

slide-44
SLIDE 44

True-Scale Cross Section of UST- 13 Area Normal to Foliation, Illustrating Monitoring Gap

slide-45
SLIDE 45

Plan View of Site 32-43A Indicating Proposed Locations for New Monitoring Wells

slide-46
SLIDE 46

DPT Program - 2007

slide-47
SLIDE 47

UST-13

slide-48
SLIDE 48

UST-13

slide-49
SLIDE 49

Summary and Conclusions

  • Basic Geologic Analysis points to numerous
  • pportunities for LTM Improvements
  • Many existing MWs are no longer useful and should be

eliminated from the program

  • UST-13 Area Requires several new MWs

– Source area – True down-gradient directions – Water-table (BR/OB)

  • Joints parallel to foliation may play a significant role in

contaminant migration

– Down-dip migration of NAPL (W/SW) – Dissolved COC migration along strike (S)

slide-50
SLIDE 50

Summary and Conclusions (Cont.)

  • Systematic water table rise in the POL

area

  • Many existing MWs no longer screened
  • ptimally for water table monitoring
  • Source area MWs needed
  • Several MWs needed to SW of source

area along primary flow pathways (SOB/DOB)

  • Target SW-striking Bedrock Structure
slide-51
SLIDE 51

Recommendations and Outstanding Issues

  • CSM Consensus
  • Install New Monitoring Wells
  • Decommission Unnecessary Wells
  • New Baseline; Re-initiate Long-term Monitoring
  • Evaluate time-series contaminant trends
  • Evaluate Perchlorate (Blasting)
  • Install Transducers to evaluate long-term water

level trends

  • Determine whether additional remedial

measures are needed

slide-52
SLIDE 52

2009 Persulfate Injection

slide-53
SLIDE 53

2009 Persulfate Injection

slide-54
SLIDE 54

2009 Persulfate Injection

  • Focus on “hotspot” near 32M-01-18XBR
  • 3 shallow bedrock injection wells installed

around 32M-01-18XBR

  • Overburden injection well installed on Top-
  • f-bedrock in former tank grave
  • 1800 gallons of water/sodium persulfate

solution injected February 2009

  • sodium hydroxide used as catalyst
slide-55
SLIDE 55

Injection Pressure Response Far Field

Data Corrupted

slide-56
SLIDE 56

Injection Pressure Response Near Field

Transducer Malfunction

slide-57
SLIDE 57

Injection Conductivity Response Near Field

Discernable Conductivity Increase

slide-58
SLIDE 58

May 2010 300 ug/l Cleanup goal = 600 ug/l

slide-59
SLIDE 59

May 2010 59 ug/l Cleanup goal = 40 ug/l

slide-60
SLIDE 60

Cleanup goal = 200 ug/l May 2010 300 ug/l

slide-61
SLIDE 61

Vertical LNAPL Distribution

  • LNAPL

penetrates below water table

  • LNAPL and

water coexist in pores

  • Assumes

LNAPL floats on water table

  • Uniform

LNAPL saturation LNAPL Water Grains Vertical Equilibrium Pancake Model

No Yes

Pancake Model vs. Vertical Equilibrium Model

slide-62
SLIDE 62

Water Levels - 32M-01-18XBR

234 236 238 240 242 244 246 248 J a n

  • 2

M a r

  • 2

M a y

  • 2

J u l

  • 2

S e p

  • 2

N

  • v
  • 2

J a n

  • 3

M a r

  • 3

M a y

  • 3

J u l

  • 3

S e p

  • 3

N

  • v
  • 3

J a n

  • 4

M a r

  • 4

M a y

  • 4

J u l

  • 4

S e p

  • 4

Date WL Elevation - msl Series1

slide-63
SLIDE 63

True-Scale Cross Section of UST- 13 Area Normal to Foliation, Illustrating Monitoring Gap

slide-64
SLIDE 64

Questions for Ongoing LTM

  • Is the apparent COC attenuation real?
  • Or will the Oscillatory longer-term trends resume
  • Does the site behave as a typical “drowned

smear zone”?

  • Delivery: Will future remedial efforts need to

more carefully consider the bedrock fracture system?

  • Deliverance: How might one increase the
  • xidant contact with residual contaminants?
slide-65
SLIDE 65

Next Steps

  • Install
  • Install Transducers to evaluate long-term water level

trends

  • Determine whether additional remedial measures are

needed

  • Consider Injecting in down-dip directions
  • Monitor in down gradient areas in consideration of

bedrock ground water gradients and bedrock fabric

slide-66
SLIDE 66

2009 Persulfate Injection

INJECT HERE MONITOR HERE

slide-67
SLIDE 67
  • THANKS
  • Question ??