1. Barrier Wall Performance 2009 Data
July 2010 Progress Meeting
McCormick & Baxter Superfund Site
Portland, Oregon

2. 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

3. 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

4. Total NAPL Recovery 1989-2010 ~6373gallons

5. 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

6. MW-Ds (outside, FWDA)

7. MW-Gs (outside, FWDA)

8. MW-20i (outside, FWDA)

9. MW-23s (inside, FWDA)

10. EW-15s (inside, FWDA)

11. MW-56 (inside, FWDA)

12. EW-18s (inside, TFA)

13. 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

14. Groundwater Flow Shallow Zone Contour Maps (4 quarters)
Hydrographs from transducer data (historic and annual)
Vertical Gradients (using 2008 transducer data)

15. 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 feet of the river

16. June 2009 Measured during a rising tide
Low tide at 4:30 AM 9.05 feet NAVD88
High tide at 8: 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…..

17. September 2009 Measured across low tide
Low tide at 2 PM feet NAVD88
High tide at 6 AM 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

18. 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.

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

20. 2009 Data MW36/MW37

21. MW-40/MW-41 Inside/Outside

22. MW44s/MW45s inside/outside

23. 2009 Data MW44/MW45

24. 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

25. Shallow to intermediate
Vertical Gradients
Monitoring Well
Shallow to intermediate
Intermediate to deep
Shallow to deep
MW-36 (inside)
-0.191
MW-37 (outside)
0.0022
MW-44 (inside)
0.0165
-0.029
MW-45 (outside)
0.0017

26. 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