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 Recovery 1989-2010 ~6373gallons

Wells with NAPL Outside Barrier Wall MW-20i MW-Gs MW-Ds MW-10s Inside Barrier Wall EW-8s MW-56s EW-18s MW-10r EW-1s EW-15s EW-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 Summary Outside 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 5 foot difference at back of wall River is low (8.16’ NAVD88 low tide at 8:30 AM and 10.22’ NAVD88 high tide at 13:30 PM) Low gradient inside wall to “drain”; gradient to river outside wall Elevation in shallow wells outside barrier wall towards river - within .1-.6 feet of the river

June 2009 Measured during a rising tide Low tide at 4:30 AM 9.05 feet NAVD88 High tide at 8:30 11.21 feet NAVD88 Measurements made after 8:30AM Water levels dropped about a foot outside wall and remained similar inside the wall. Contour lines should not cross the river…..

September 2009 Measured across low tide Low tide at 2 PM 5.25 feet NAVD88 High tide at 6 AM 8.96 feet NAVD88 River has dropped – causing a larger gradient inside barrier wall as wells near “drain” lower in groundwater elevation (flat away from drain) Flow outside wall maintains same pattern. Groundwater elevations outside wall have dropped aabout 3 feet. Maintaining a large difference between inside and outside the barrier wall

December 2009 (with Triangle Park) Water levels measured during high tide Clear how wells near the “drain” inside the wall react to river level while interior remains near static in water elevation. Groundwater pattern outside remains consistent with previous months. River is up 4 feet from last quarter – upland elevations also increased by about 2 feet.

MW-36s/MW-37s inside/outside

2009 Data MW36/MW37

MW-40/MW-41 Inside/Outside

MW44s/MW45s inside/outside

2009 Data MW44/MW45

MW-52s/MW53s inside/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

Shallow to intermediate Vertical Gradients Monitoring Well Shallow to intermediate Intermediate to deep Shallow 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