Waste Management Area U (WMA U), located in the 200 West Area of the Hanford Site, includes the U Tank Farm, which contains 16 single-shell tanks and their ancillary equipment and waste systems. Groundwater monitoring has been under an interim-status indicator evaluation program. This plan presents the approach to be used for the groundwater quality assessment program. Based on the results of this investigation, if WMA U is not the source of groundwater contamination, the site will revert to detection monitoring. If WMA U is the source, then a second part of the groundwater quality assessment plan will be prepared to define the rate and extent of migration of contaminants in the groundwater and their concentrations. Information gathered will enhance the understanding of subsurface conditions and processes to support tank waste remediation and cleanup decisions and/or complement near-term corrective actions to protect groundwater and the Columbia River.