SITE OBSERVATIONS SUMMARY (January through December 2010) McCormick and Baxter Superfund Site Portland, Oregon

Observations from Site Activities Sediment Cap Monitoring Upland Soil Cap Monitoring Infiltration Pond Assessment

Sediment Cap Monitoring In general, the overall condition of the sediment cap is comparable to when it was constructed in 2004/2005. Sheen Similar to previous observations General Maintenance ACB Repair ACB Investigation Bathymetric Survey, Porewater Sampling, Coring

General Maintenance Gap observed between ACB. TFA area. (September ’10). Gap between ACB filled with grout. TFA area. (September ’10).

ACB Investigation During low river levels uneven ACB was observed in Willamette Cove (September ’09). Uneven ACB observed in Willamette Cove (September ’09).

ACB Investigation Conclusions Sediment cap performance monitoring from 2005 – 2010 indicates the sediment cap is functioning as designed. Porewater sampling in March 2010 did not indicate elevated levels of PAHs or metals. Cores through unconformities showed 4” to over 1’ of sand cap and contained no visual signs of contamination. Samples reflected PAH concentrations less than the sediment clean-up goals in the 1996 ROD. Bathymetry images and diver inspections did not identify any areas of concern.

Overall, the upland soil cap inspections revealed few changes from The degree of upland soil cap subsidence has decreased since 2008 and The impermeable cap stormwater drainage system appears to be unaffected. Upland Soil Cap Monitoring Soil cap subsidence area. July ‘10.

Upland Soil Cap Monitoring Typical ground squirrel burrow within soil cap July Vegetation growth on soil cap. July 2010.

Infiltration Pond Monitoring Conclusions Chromium, copper, and zinc decreasing. Arsenic levels stable since Only trace amounts of and PCP and PAHs recorded. There does not appear to be contaminant mobilization by the infiltration pond.

Site Observations Summary In general, the sediment and upland soil caps are performing as designed.