GROUNDWATER DEVELOPMENT

PROPERTY TRANSFER
REMEDIAL INVESTIGATION & CLEANUP
EXPERT WITNESS
WELLHEAD PROTECTION
SOLID WASTE COMPLIANCE
WATER RIGHTS SUPPORT
DATA MANAGEMENT
GROUNDWATER MODELING
• City of Auburn
• Clark Public Utilities
WATERSHED ASSESSMENT
AQUIFER STORAGE & RECOVERY
WASTEWATER & STORMWATER RECHARGE
 

Client: Clark Public Utilities
Project: Remedial Investigation & Groundwater Flow Model
Location: Vancouver, Washington

Background
In an effort to supply water to the rapidly growing population of Clark County, Washington, Clark Public Utilities (CPU) has explored many possible new groundwater sources. Unfortunately, the availability of suitable development sites continues to decrease. One possible water source is a highly productive aquifer system along the Columbia River near Vancouver Lake. This system, however, not only supports local wetlands but it also includes areas where historic industrial uses have contaminated the aquifer with chlorinated solvents.

Challenges
Although the contaminant plume is currently contained, operating a high-capacity wellfield could mobilize it. Before developing such a wellfield, CPU needed to understand how pumping will affect plume migration. A complicating factor is the area’s complex groundwater conditions; water level gradients are very low (and therefore difficult to measure) and groundwater levels are strongly influenced by flow variations in local surface water features. For instance, Columbia River levels vary daily in response to tidal influences but vary seasonally according to upstream dam operations.

Approach
Typically, we assess groundwater flow patterns using measurements of water levels obtained in the field. In this case, however, such a traditional approach was infeasible. Instead, we constructed a groundwater flow model that incorporates known hydrogeologic information and surface water variation. This model was also designed to evaluate the significance of unknown information by running an uncertainty analysis.

Outcome
The contaminant distribution predicted by our model was a good match to observed conditions, indicating that our design and calibration were successful. We used the model to evaluate the how pumping at the proposed wellfield site would alter the spreading of contamination from the source areas.

Related Projects

Groundwater Development / Clark Public Utilities: Water Supply Development

Watershed Assessments / Clark Public Utilities: Salmon Creek Basin Management Plan

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