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Client:
City of Auburn |
Background
Auburn, Washington, is a rapidly growing community that has required increasing
amounts of groundwater to meet its needs. Although the city sits on a
highly prolific glacial aquifer system, the process for obtaining water
rights is complicated by stream closures along the nearby White and Green
Rivers, which are hydraulically connected to aquifers in some places.
Challenges
This project posed many challenges because of its large area, lack of
reliable data, complex glacial hydrostratigraphy, and high level of public
scrutiny. The stream closures required us to quantify the complex relationships
between groundwater and surface water—a difficult task even with
a comprehensive flow model.
Approach
Our characterization work for this project spanned a 5-year period. In addition to conducting extensive research on the area’s hydrogeology, we designed and implemented a major field exploration program that entailed:
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Installing over 30 wells |
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Running many regional aquifer tests |
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Surveying water levels throughout the Auburn-Kent Valley and Lake Tapps Upland |
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Collecting water samples for the analysis of geochemical parameters and isotopes |
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Designing and implementing an extensive monitoring network that includes wells and stream gauges along the Green and White Rivers |
Using data from driller’s and geologic logs, we developed over 30 cross sections to characterize the hydrostratigraphy of the upland and valley regions. We also analyzed water-level data to assess groundwater flow patterns and stream-gauge data to assess trends in surface water flow. The results of these analyses, along with information from published reports, were integrated into a conceptual hydrogeologic model that described the area’s hydrostratigraphy, groundwater flow patterns, and stream–aquifer relationships.
Outcome
Our conceptual hydrogeologic model formed the basis for developing a comprehensive
groundwater flow model. A valuable tool for water-resource planning, the
flow model simulates the effects of various pumping scenarios on the region’s
groundwater and surface-water systems.
Related Projects
Wellhead Protection / City of Auburn: Wellhead Protection Studies
Groundwater Modeling / City of Auburn: Hydrogeologic Characterization & Groundwater Modeling