This document is the third revision of the 'Monitoring Well Inspection and Maintenance Plan' for groundwater wells associated with the US Department of Energy (DOE) Y-12 National Security Complex (Y-12) in Oak Ridge, Tennessee. This plan describes the systematic approach for: (1) inspecting the physical condition of monitoring wells at Y-12; (2) identifying maintenance needs that extend the life of the well and assure well-head protection is in place, and (3) identifying wells that no longer meet acceptable monitoring-well design or well construction standards and require plugging and abandonment. The inspection and maintenance of groundwater monitoring wells is one of the primary management strategies of the Y-12 Groundwater Protection Program (GWPP) Management Plan, 'proactive stewardship of the extensive monitoring well network at Y-12' (BWXT 2004a). Effective stewardship, and a program of routine inspections of the physical condition of each monitoring well, ensures that representative water-quality monitoring and hydrologic data are able to be obtained from the well network. In accordance with the Y-12 GWPP Monitoring Optimization Plan (MOP) for Groundwater Monitoring Wells at the Y-12 National Security Complex, Oak Ridge, Tennessee (BWXT 2006b), the status designation (active or inactive) for each well determines the scope and extent of well inspections …