REGARDING: Revised Protective Concentration Limits (PCLs) for Tetrachloroethene (PCE) and Trichloroethene (TCE) in Groundwater Used for Kiddie Pools and Other

The human health risk assessment (HHRA) for the Eugene Railyard evaluated possible exposures to groundwater used outdoors for washing, swimming, and other direct contact scenarios for off-site residents. Pathways of exposure considered in the HHRA were ingestion, dermal contact, and inhalation of chemicals volatilizing from water. Protective Concentration Levels (PCLs) were calculated for the chemicals of concern for off-site groundwater uses. This memorandum discusses the basis for revised groundwater PCLs for PCE and TCE that reflect volatilization losses due to outdoor groundwater use. After accounting for volatilization losses, the revised groundwater irrigation PCLs that are considered protective (1 x 10-6 lifetime cancer risk based) are 0.005 mg/L for PCE and 0.012 mg/L for TCE. The basis for revision of the PCLs is described in this memorandum. The HHRA used exposure assumptions which indicate that a child may be exposed to groundwater as a result of using groundwater to fill a “kiddie ” pool. In keeping with the HHRA for the Eugene Rail Yard, a child and an adult are assumed to drink groundwater directly from a garden hose. A child swimmer is also assumed to have whole body skin exposure to PCE and TCE in pool water and inhale PCE and TCE volatilizing from the water during a two hour swim