Case Study: Aquifer Storage & Recovery Assessment

Client: WRIA 31 Planning Unit Location: Kennewick, WA Contact for water resource projects: Tim Flynn

Project Background & Challenges

The City of Kennewick contains about 90 percent of the population in WRIA 31, where water demands are projected to increase 140 percent by the year 2021. Most of water required to meet the City’s peak demand is drawn from the Columbia River system during the summer, when flows are lowest — and potentially most important to instream resources. ASR offers a way to store surplus river water during the off-peak (winter) season so suppliers can withdraw it later to meet peak demands. One important benefit of ASR is a reduced need for additional treatment facilities, which can be very costly for surface water sources. ASR would allow the City to use more of its existing production and treatment capacity during the off-peak season — thereby maximizing its value.

Solution

Aspect Consulting assessed the feasibility of applying ASR within the City’s water service area. This work entailed developing three required elements for an ASR application to Ecology: a hydrogeologic conceptual model, an environmental assessment, and a monitoring plan for ASR pilot testing. Working collaboratively with the City, we identified a target area for ASR using several criteria. We considered not only where future needs for peak capacity would be greatest but also where water system infrastructure was already in place. We also considered hydrogeologic conditions — for example, the distance from potential aquifer boundaries that would limit the reservoir available for storage. Other work for this project included developing a model to predict the recoverability of stored water under a range of groundwater flow conditions — a tool that will help guide a future ASR operation plan. The City intends to move forward with pilot testing in the future.