2017 Annual Landfill Inspection

Transcription

1 2017 Annual Landfill Inspection Cell 2 Prepared for Minnkota Power Cooperative, Inc. Milton R. Young Station January 2018

2 2017 Annual Landfill Inspection Cell 2 Prepared for Minnkota Power Cooperative, Inc. Milton R. Young Station January 2018 Minneapolis, MN, Bismarck, ND

3 2017 Annual Landfill Inspection January 2018 Contents 1.0 Introduction Review of Existing Information Results of Weekly Inspections Results of Previous Annual Inspections Structural Integrity and Operational Review Volume of CCR Contained... 4 List of Tables Table 3-1 Summary of Visual Inspection... 3 Table 4-1 Volume of CCR Contained in Landfill... 4 i

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5 1.0 Introduction Minnkota Power Cooperative, Inc. (MPC) operates the Milton R. Young Station (MRY), near Center, North Dakota. MRY operates two lignite-fired cyclone boilers, resulting in production of coal combustion residuals (CCR). CCR management is subject to Federal Standards for Disposal of Coal Combustion Residuals in Landfills and Surface Impoundments per 40 CFR 257 Subpart D (CCR Rule). MPC currently hauls dry CCR material to Cell 2 which is considered a CCR landfill. Under 40 CFR CCR landfills are subject to annual inspections by a qualified professional engineer (QPE). This report documents the third landfill annual inspection performed by Seth W. Hueckman, P.E. on September 29, 2017, as required by the CCR Rule. Other annual inspection duties, including a review of the available information regarding the status and condition of the CCR unit and storage capacity evaluations, were performed prior and following the on-site inspection. 1

6 2.0 Review of Existing Information A review of existing information was performed to confirm that the design, construction, operation and maintenance of the landfill is consistent with recognized and generally accepted good engineering standards. The existing information reviewed is described in the following subsections. 2.1 Results of Weekly Inspections Weekly inspection reports from November 23, 2015 through December 30, 2016 were reviewed as part of the 2016 annual inspection. Weekly inspection reports from January 6, 2017 through December 25, 2017 were reviewed as part of this annual inspection. The weekly inspection reports documented that the dewatering pump was inoperable from about April 20, 2017 thru September 25, MPC ordered a replacement pump; however, delivery was delayed due to the manufacturer. 2.2 Results of Previous Annual Inspections The annual inspection performed in September 2016 documented that the leachate collection discharge pump was not working; MPC replaced the pump in October

7 3.0 Structural Integrity and Operational Review An on-site inspection was performed to visually identify signs of distress or malfunction of the landfill. Inspection consisted of on-foot inspection of perimeter embankments, the active landfill face, and final covered areas. Visual inspection items and results are summarized in the following table: Table 3-1 Summary of Visual Inspection Item Visual Inspection Description Visibly Observed (/No) Notes 1 Proper placement of waste Waste properly contained within cell Adequate slope stability and erosion control Run-on and Run-off controls properly functioning Surface water percolation minimized Liner systems properly operated and maintained Leachate collection systems properly operated and maintained Water quality monitoring systems maintained and operating Except as noted Except as noted No significant erosion identified. Some internal slope erosion visible on the north temporary slope adjacent to Cell 1 and on the west slope near the perimeter ditch; MPC to continue to monitor and repair as necessary. Surface water controls appeared adequate No significant surface water ponding or excessive leachate generation observed; shallow pool of surface water observed on southeast corner within liner limits No significant liner systems issues; some erosion present on upper bottom ash protection layer covering the interior side slope on east side Leachate collection discharge pipe was operating Existing monitoring wells were accessible and appeared to be in good condition. One well casing on the west embankment did not have a cap; MPC added a cap to the well following the inspection. 8 Dust adequately controlled No dust issues present at time of inspection Landfill geometry consistent with facility plan Animal burrows absent or of no significance Adequate vegetation density and vegetation maintenance No geometry changes observed No burrows of significance identified Vegetation appeared well established and well maintained 12 Debris controlled or absent Waste debris was properly contained in landfill No changes to the landfill design, maintenance, or operations were observed that could affect the stability or operation of the landfill. 3

8 4.0 Volume of CCR Contained A topographic survey of the landfill was performed on November 15, 2017 which was used to calculate volumes of CCR contained in the CCR unit and capacity remaining. The following table summarizes the volume of CCR contained in the landfill. Table 4-1 Volume of CCR Contained in Landfill Slot/Cell Approximate Permitted Design CCR Capacity (cy) Current CCR Capacity Consumed (cy) Approximate Remaining CCR Capacity (cy) Status of Cell Cell M 2.56M 1.04M Active 4