Surface Water, Inter-Armor and Sub-Armor Sampling Program and Results Oregon DEQ, Hart Crowser, Inc., and GSI Water Solutions 2010 McCormick & Baxter Annual Report

Sampling Program  Goals:  Monitor sediment cap (and groundwater) remedy to understand performance related to minimizing releases of contaminants from sediments that might result in contamination of the Willamette River in excess of federal and state ambient water quality criteria  Fluvial system characteristics (semi-annual monitoring)  Lower Willamette tidally-influenced  Transition-zone water may reflect variations in:  Discharge (Q, cubic feet per second)  River stage (stream elevation)  Stream velocity (feet per second)

Sampling Program 2010  Spring 2010 – Conventional Sampling  Overlying Cap:  Surface water  Within Cap:  Inter-armor  Sub armor  Fall 2010 – SPME

Spring 2010 Sampling Locations  22 locations within sediment cap footprint  Upgradient and downgradient

Seasonality of the River – Stage Fall Event Spring Event

Seasonality of the River – Discharge Fall Event Spring Event

Sampling Results – SW cPAHs

Sampling Results – IA cPAHs

Sampling Results – SA cPAHs

Sampling Results – SW Napthalene

Sampling Results – IA Napthalene

Sampling Results – SA Napthalene

Sampling Results - trends  Mean Total cPAH Concentrations Mean cPAH Concentration ( μ g/L, log scale)

Sampling Results - trends  Mean Total PAH Concentrations Mean PAH Concentration ( μ g/L, log scale)

Conclusions  COC concentrations in surface water, inter-armoring and sub- armoring samples are generally below comparison criteria with the exception of arsenic (MDL)  Detections frequencies and concentrations increase with depth (highest in SA)  Concentrations are generally lower in spring events  cPAHs declined immediately after remedy was implemented  Typically cPAHs have been below detection limits; therefore, trends cannot be identified Sediment cap functioning as designed is protective of surface water