Case Study: y: View-Ma Master er Site, e, Bea eavert erton, Or - - PowerPoint PPT Presentation

Case Study: y: View-Ma Master er Site, e, Bea eavert erton, Or Oregon

Henning Larsen, RG

Fractured Rock Training - Seattle, WA -September 2019 1

View-Master Site, Beaverton Oregon

Site

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Site

View-Master Campus Circa 1960s

• TCE released via waste disposal, drain fields, vapor degreaser
• 1,200-1,500 ug/L TCE - Industrial Supply Well
• Up to 25,000 Workers Exposed; 1,000 for >5yrs
• Epi Study identified increased incidence of cancer

TCE Releases at the View-Master Site

Water Tower Demolition Factory Work

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28,000 21,000 9,000 65,000 2,800

2/ND/6 7/3/16 86/524/50 62/215/100 1/6/9 TCE Source Areas TCE (ug/L) Facility Boundary TCE/cis-DCE/Total Cyanide (ug/L)

28,000 86/524/50

View-Master Site, Beaverton Oregon

Fractured Rock Training - Seattle, WA -September 2019 4

Fractured Rock Training - Seattle, WA -September 2019 5

Regional Structural Geology

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A Tualatin Mtns A’

800 ft

Portland Basin

380 ft 275 ft

Fanno Creek

160 ft Anticline 600 ft

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East-West Cross-Section

Columbia River Basalt Flows Identified at the Site

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Palouse Canyon, the Sentinel Bluffs flows of the Grand Ronde Formation are seen on the bottom, covered by the Ginkgo Flow of the Wanapum Basalt.

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Columbia River Basalts in their Native Habitat

U U U D D D

Block “B” Block “c” Block “E” Block “D”

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Hydrogeologic Blocks of Columbia River Basalt Group: View-Master Site

C’ C D’

D

E’ E

Discharge of saline groundwater

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Willamette Silt CRB Flow Top

East-West Site Cross-Section

TCE Plume

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Willamette Silt CRB Flow Top

North-South Cross-Section

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Northwest-Southeast Cross-Section

Willamette Silt CRB Flow Top

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Basalt Well Spinner Logs Distribution of Flow in CRB Sheet Flow Basalts

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1.5 ft drawdown contour within Block E

No Response In Block C

No Response in Block D

Extraction Well

4 ft drawdown

Estimated 120 gpm groundwater inflow based on average gain of Fanno Creek

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High lateral and Vertical conductivity and hydraulic connection within Blocks

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130 ft vertical separation between DMW-2A and DMW-2C

Strong Vertical Hydraulic Connection

• Head similarities
• Deep contaminant

migration

NS 6,740/190 29/66 ND/ND 4/81 4,070/NA

TCE Plumes in CRBG-A

Highest concentration of last four events: 29/66 - TCE (ug/L)/ Total Cyanide (ug/L),

Estimated Capture Zone - 2001 FS Extraction Wells Average Flow – Initial/Current (gpm)

376/63 ND/8 ND ND 4,510 3,100 ND 12,000 1,280 1,540 6.5

Fractured Rock Training - Seattle, WA -September 2019 18 10/5 5/0 100/54 90/62 5/0

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Deeper Aquifer TCE Concentrations Block E

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Interflow zones have high lateral conductivity and transmissivity, but offset by faults can disconnect zones in adjacent blocks Faults Act as Flow Barriers

• No hydraulic response across inferred faults
• Steep seasonal gradients

Faults Convey Water

• Deep groundwater discharge to wetland and Fanno Creek
• Discharge of contaminated groundwater to Koll Center Wetlands

Flow Within Blocks – Interflow zones are highly conductive within fault blocks and are inter- connected vertically (water tank) Pump and Treat Alone has limited success in remediating groundwater in this geologic setting

Conclusions