The Issue: The Yakima Training Center (YTC)—spanning Yakima and Kittitas counties in south-central Washington—is a satellite installation of Joint Base Lewis-McChord and is used for military training (fig. 1). Past activities at the YTC have resulted in releases of hazardous waste and contaminants to the environment, and the most recent chemical of concern is per- and polyfluoroalkyl substances (PFAS). PFAS are a broad class of anthropogenic chemicals used in industrial and consumer products for their stain- and water-resistant properties. One of the most common sources of PFAS at military installations, including at the YTC, is aqueous film-forming foam (AFFF) used as a fire suppressant. PFAS degrade very slowly in the environment and PFAS exposure has been linked to adverse health effects in humans.
How USGS will help: The USGS is helping water-resource managers by developing a detailed conceptual model and hydrogeologic framework for the groundwater-flow system from the PFAS source areas on the YTC to the groundwater-discharge area at the Yakima River.
Problem: The current understanding of the groundwater system in the vicinity of the YTC is insufficient for the accurate identification and efficient remediation of groundwater contaminants, including PFAS. Previous investigations of the groundwater system were either focused on localized soil contamination near the Fire Training Center at the YTC or on large, regional areas such as the Yakima River Basin or Columbia Plateau. An improved understanding of the local hydrogeology and groundwater quality is needed to provide actionable information and ensure remediation efforts are targeted efficiently.
Objectives: The objective of this study is to develop a detailed conceptual model and hydrogeologic framework for the groundwater-flow system from the PFAS source areas on the YTC to the groundwater-discharge area at the Yakima River. Hydrologic and geologic information from existing studies will be synthesized with new information from driller’s well logs, groundwater-level measurements (hereafter, water-level measurements), and water-quality data collected from wells.
Relevance and Benefits: This study will provide foundational information to the U.S. Army that will inform and direct current and future subsurface-remediation efforts near the YTC. The efficient remediation of current and future subsurface contaminants helps to ensure that on- and off-base drinking-water supplies remain potable for all water users. The data and hydrogeologic model produced by this study can also be used to develop numerical groundwater-flow and contaminant-fate and -transport models capable of predicting flow paths and travel times of contaminants in the subsurface—a potential subsequent phase of the remedial investigation at the YTC.
Approach:
To meet the objective of this study, the approach will be split into three primary tasks: (1) groundwater-level data collection, (2) water-quality sampling and analysis, and (3) development of the hydrogeologic framework.
For Task 1, well logs will be reviewed to develop a well database that includes wells that can be used for groundwater-level measurements and in the development of the hydrogeologic framework. Discrete groundwater levels from about 50–75 selected wells will be measured quarterly for a complete year to capture the seasonal variation in groundwater conditions.
For Task 2, discrete water-quality samples will be collected from a subset of groundwater wells and used to evaluate groundwater flow paths and the influence of surface-water irrigation in the off-base area.
For Task 3, a hydrogeologic framework and three-dimensional hydrogeologic model will be developed that describe the physical, lithologic, and hydrologic characteristics of the hydrogeologic units in the study area.
- Overview
The Issue: The Yakima Training Center (YTC)—spanning Yakima and Kittitas counties in south-central Washington—is a satellite installation of Joint Base Lewis-McChord and is used for military training (fig. 1). Past activities at the YTC have resulted in releases of hazardous waste and contaminants to the environment, and the most recent chemical of concern is per- and polyfluoroalkyl substances (PFAS). PFAS are a broad class of anthropogenic chemicals used in industrial and consumer products for their stain- and water-resistant properties. One of the most common sources of PFAS at military installations, including at the YTC, is aqueous film-forming foam (AFFF) used as a fire suppressant. PFAS degrade very slowly in the environment and PFAS exposure has been linked to adverse health effects in humans.
How USGS will help: The USGS is helping water-resource managers by developing a detailed conceptual model and hydrogeologic framework for the groundwater-flow system from the PFAS source areas on the YTC to the groundwater-discharge area at the Yakima River.
Sources/Usage: Public Domain.Hydrogeologic framework near the Yakima Training Center, Washington Problem: The current understanding of the groundwater system in the vicinity of the YTC is insufficient for the accurate identification and efficient remediation of groundwater contaminants, including PFAS. Previous investigations of the groundwater system were either focused on localized soil contamination near the Fire Training Center at the YTC or on large, regional areas such as the Yakima River Basin or Columbia Plateau. An improved understanding of the local hydrogeology and groundwater quality is needed to provide actionable information and ensure remediation efforts are targeted efficiently.
Objectives: The objective of this study is to develop a detailed conceptual model and hydrogeologic framework for the groundwater-flow system from the PFAS source areas on the YTC to the groundwater-discharge area at the Yakima River. Hydrologic and geologic information from existing studies will be synthesized with new information from driller’s well logs, groundwater-level measurements (hereafter, water-level measurements), and water-quality data collected from wells.
Relevance and Benefits: This study will provide foundational information to the U.S. Army that will inform and direct current and future subsurface-remediation efforts near the YTC. The efficient remediation of current and future subsurface contaminants helps to ensure that on- and off-base drinking-water supplies remain potable for all water users. The data and hydrogeologic model produced by this study can also be used to develop numerical groundwater-flow and contaminant-fate and -transport models capable of predicting flow paths and travel times of contaminants in the subsurface—a potential subsequent phase of the remedial investigation at the YTC.
Approach:
To meet the objective of this study, the approach will be split into three primary tasks: (1) groundwater-level data collection, (2) water-quality sampling and analysis, and (3) development of the hydrogeologic framework.
For Task 1, well logs will be reviewed to develop a well database that includes wells that can be used for groundwater-level measurements and in the development of the hydrogeologic framework. Discrete groundwater levels from about 50–75 selected wells will be measured quarterly for a complete year to capture the seasonal variation in groundwater conditions.
For Task 2, discrete water-quality samples will be collected from a subset of groundwater wells and used to evaluate groundwater flow paths and the influence of surface-water irrigation in the off-base area.
For Task 3, a hydrogeologic framework and three-dimensional hydrogeologic model will be developed that describe the physical, lithologic, and hydrologic characteristics of the hydrogeologic units in the study area.
- Partners