Modeling to Support Risk Assessment MILWAUKIE, OREGON

Types of Service
• Groundwater Modeling
• Solute Transport Modeling
• Particle Tracking

Media
• Groundwater

Contaminants
• PCE
• TCE
• DCE

Project Highlights
• Provided modeling services for groundwater beneath a former hand tool manufacturing plant in the Portland Basin, Milwaukie, Oregon.  Flow and transport modeling was conducted as part of the voluntary cleanup program activities.
• Evaluated existing site and regional data for development of conceptual model and selection of groundwater model input parameters.
• Groundwater models were used to examine the local and regional flow directions beneath the former facility.
• Solute transport modeling was conducted to estimate concentrations for constituents of concern at a municipal supply well.  The estimated concentrations were used in developing exposure point concentrations for a baseline risk assessment.
• Model output was compared to output from the publicly available Aquifer Simulation Model flow and transport code.
• Site consisted of a complex flow system resulting from erratic pumping schedules of several municipal supply wells.  The highly variable flow direction created from erratic pumping rates and schedules differed significantly from groundwater flow directions depicted in the regional Portland Basin Model.
• Time weighted average concentrations were determined from the concentration breakthrough curves predicted by the flow and transport models.  The time weighted average concentrations were used in developing exposure point concentrations for a baseline risk assessment.