Barrier Wall Performance

2009 Data

July 2010 Progress Meeting

McCormick & Baxter Superfund Site

Portland, Oregon

Barrier Wall Performance

• NAPL Recovery– Where and how much

• NAPL Thicknesses– Tracking thicknesses inside and outside wall

• Groundwater and River Elevations– Shallow contour maps– Hydrographs– Gradients

NAPL Recovery

• ROD RA Objectives: contain NAPL, prevent ongoing discharges of NAPL to Willamette River, and minimize further contamination of intermediate and deep aquifers

• Tasks:– Weekly recovery from wells outside barrier wall that

have sufficient NAPL• MW-Ds, MW-Gs, MW-20i (DNAPL only)• EW-1s (inside barrier wall)

– Quarterly gauging for NAPL in remaining wells

Total NAPL Recovery1989-2010 ~6373gallons

Wells with NAPL

Outside Barrier WallMW-20i MW-Gs MW-Ds MW-10s

Inside Barrier WallEW-8s MW-56sEW-18s MW-10rEW-1s EW-15sEW-23s

MW-Ds (outside, FWDA)

MW-Gs (outside, FWDA)

MW-20i (outside, FWDA)

MW-23s (inside, FWDA)

EW-15s (inside, FWDA)

MW-56 (inside, FWDA)

EW-18s (inside, TFA)

NAPL Recovery SummaryOutside Barrier Wall• 2008: 57 gallons of DNAPL from 3 wells (primarily MW-20i);

no LNAPL • 2009: 92 gallons DNAPL (MW-20i, MW-Gs, MW-Ds); no

LNAPL • 2010: 66 gallons DNAPL to date (including EW-1)• NAPL levels remain stable

Inside Barrier Wall – • monitored for NAPL quarterly; • Stable thicknesses • 2009: 21 gallons of DNAPL from EW-1s

Automated NAPL Recovery System - 2011

Groundwater Flow

• Shallow Zone Contour Maps (4 quarters)

• Hydrographs from transducer data (historic and annual)

• Vertical Gradients (using 2008 transducer data)

March 2009

June 2009

September 2009

December 2009 (with Triangle Park)

MW-36s/MW-37sinside/outside

2009 Data MW36/MW37

MW-40/MW-41Inside/Outside

MW44s/MW45sinside/outside

2009 Data MW44/MW45

MW-52s/MW53sinside/outside

Historically, MW-52s gw elevation was ~18.5 NAVD88 (May 2003). The level has gradually dropped since installation of the barrier wall. Rate of decline increased with installation of the impermeable soil cap. Approaching equilibrium with the River

Vertical Gradients

Monitoring WellShallow to

intermediateIntermediate to

deepShallow to

deep

MW-36 (inside) -0.0434 -0.0020 -0.191

MW-37 (outside) -0.0070 0.0022 -0.0015

MW-44 (inside) -0.0841 0.0165 -0.029

MW-45 (outside) -0.0066 0.0017 -0.0018

Main Points• Shallow groundwater within Barrier Wall will equilibrate with the River

(dropped 5 feet – 1-2 more)

• Shallow groundwater outside and inside the barrier wall are not hydraulically connected (i.e., barrier wall is performing as expected)

• GW inside barrier wall is hydraulically connected to the river from the “drain” in corner at base of wall

• Intermediate and deep zones inside and outside the barrier wall continue to mimic river with very low vertical gradients (primarily downward)

• Gradients low and primarily downward: conditions are not conducive to NAPL migrating from inside barrier wall or from MW-20i to River

Barrier wall is performing as designed to prevent NAPL (from within the wall) from migrating to the River; also, significantly reduces the flux of contaminated groundwater to river