Federal Reports

TVA OIG retained Marshall Miller & Associates, Inc. (Marshall Miller) to conduct a peer review of the Stantec Consulting Services, Inc. (Stantec) report on geotechnical exploration and slope stability for the gypsum stack at the Widows Creek Fossil Plant. Marshall Miller believes that Stantec's evaluations of the Widows Creek gypsum stack provide a reasonable assessment of the margin of safety associated with the evaluated conditions, which indicates that the facility is not in danger of imminent failure.Marshall Miller did find that additional analyses and corresponding documentation was needed in order to assess the overall factor of safety of the stack in the midterm and longterm. Marshall Miller also found that Stantec used a model that was 20 feet lower than the final height of the stack which does not reflect the final conditions of the pile. Additionally, Marshall Miller found that Stantec did not (1) perform adequate testing to support reliance on historical data and shear strength characterization of some materials, (2) calculate and document the exit gradient and factors of safety against piping for the 5-year build-out configuration, and (3) perform sufficient investigation of the clay foundation soils.To address this report, TVA management had Stantec review and respond to the findings of this report. Marshall Miller reviewed Stantec's response and concluded that the additional information provided adequately addressed the concerns and recommendations identified in the report.

TVA OIG retained Marshall Miller & Associates, Inc. (Marshall Miller) to conduct a peer review of the Stantec Consulting Services, Inc. (Stantec) documents for proposed improvements to the stability of the Northeast Dike of the Ash Disposal Area No. 2 of the Johnsonville Fossil Plant. Based on Marshall Miller's technical review, Stantec used generally accepted methods and practices to design the stability improvements. Based on the Stantec Calculation Package, Stantec also designed a slope configuration that provides acceptable factors of safety for slope stability under long-term, steady-state seepage conditions.Marshall Miller found the plans for construction prepared by Stantec provide suitable guidance for construction, however, they found the details of the graded filter portion of the stabilization berm do not conform closely with current standards of practice and present constructability issues at locations where the installation condition are more challenging.To address this report, TVA management had Stantec review and respond to the findings of this report. Marshall Miller reviewed Stantec's response and concluded that the additional information provided adequately addressed the concerns and recommendations identified in the report.

This review was initiated because of questions raised during congressional testimony following the Kingston Ash Spill in December 2008. The objectives of this review were to determine whether the Tennessee Valley Authority (TVA) has (1) performed groundwater monitoring as prescribed by the permits and (2) found levels of constituents monitored that exceeded regulatory limits and, if so, implemented any required corrective actions.During our review, we found that in some instances TVA was not performing monitoring as prescribed by the permits. For calendar years 2008 and 2009, TVA was monitoring for the required constituents and testing within the required time frames at ten coal combustion product (CCP) areas at seven fossil plants. However, TVA was not monitoring for all permit-required constituents at Cumberland and Johnsonville Fossil Plants. TVA has submitted letters to the Tennessee Department of Environment and Conservation (TDEC) requesting removal of all constituents that were not being tested from the permit and TDEC stated this would be approved.Additionally, exceedances were found at eight of the nine fossil plants where monitoring is being conducted. TVA has two plants in Tennessee, Cumberland and Gallatin Fossil Plants, that have constituents that exceeded health-based limits and are working through the corrective action process described in Tennessee Rule 1200-1-7. Finally, TVA installed 29 monitoring wells at nine sites in 2010 and has committed to conducting at least one sampling event at each site by the end of fiscal year 2011.We recommended the Senior Vice President, Environment & Technology, continue (1) plans to implement monitoring at all active CCP disposal areas, and (2) with the assessment plans and initiate corrective actions for Cumberland and Gallatin Fossil Plants. TVA management agreed with the recommendations.