Loading...
7302_DukeRoxboro_VegetationMaintenance_DIN27726_201703243191 Pine Hall Road Walnut Cove, North Carolina 27009 336-215-4576 Page 1 of 1 March 24, 2017 North Carolina Department of Environmental Quality Division of Waste Management Solid Waste Section 1646 Mail Service Center Raleigh, North Carolina 27699 Attn: Ms. Shannon Aufman (submitted electronically) Re: Roxboro Vegetation Maintenance Permit No. 7302-INDUS-1988 Roxboro Steam Electric Plant 1700 Dunnaway Road Semora, North Carolina 27343 Dear Ms Aufman, Duke Energy is submitting the attached Vegetation Maintenance and Implementation Plan for Clearing Projects at the Roxboro Steam Electric Plant Landfill (Permit No. 7302-INDUS). This work is to assist with routine visual inspection procedures and is intended to occur predominately on the lower portion of the east slope of the landfill. If you need additional information in regards to this submittal please do not hesitate to call me at 336-215-4576 or email kimberlee.witt@duke-energy.com. Regards, Kimberlee Witt, PE Environmental Services Attachments: Roxboro Vegetation Maintenance and Implementation Plan for Clearing Projects cc: Elizabeth Werner - NCDEQ Ed Mussler - NCDEQ Evan Andrews - Duke Energy Robert Howard – Duke Energy Robert Miller – Duke Energy Ed Sullivan – Duke Energy Vegetation Maintenance and Implementation Plan for Clearing Projects Roxboro Industrial Landfill Duke Energy Progress – Roxboro Steam Station Person County, North Carolina Amec Foster Wheeler Project No. 7810170864 To: Duke Energy Progress Date 03/24/2017 From: Amec Foster Wheeler Vegetation Maintenance and Implementation Plan Duke Energy – Roxboro Steam Station Roxboro Industrial Landfill Person County, North Carolina Amec Foster Wheeler Project No. 7810170864 TOC 03/24/2017 Table of Contents 1 BACKGROUND ..................................................................................................................................... 1 1.1 Facility Description ........................................................................................................................ 1 1.2 Scope of Plan ................................................................................................................................ 1 2 MANAGEMENT OF LANDFILL VEGETATION ..................................................................................... 1 2.1 Existing Conditions ........................................................................................................................ 1 2.2 Chemical Vegetation Control ........................................................................................................ 1 2.3 Brush ............................................................................................................................................. 2 2.4 Trees 2-Inches or Less (DBH) ...................................................................................................... 2 2.5 Trees 2-Inches or Greater (DBH) .................................................................................................. 2 2.6 Phasing of the Clearing Operations .............................................................................................. 3 3 INTERIM COVER MAINTENANCE ....................................................................................................... 3 3.1 Inspection ...................................................................................................................................... 3 3.2 Erosion .......................................................................................................................................... 3 3.3 Earthen Cover ............................................................................................................................... 3 FIGURES Figure 1 Existing Conditions ENGINEER’S STATEMENT The procedures in this plan are consistent with the goal of clearing and maintaining portions of the landfill to facilitate visual inspection and to improve the integrity of the soil cover by removal of woody material as described herein. Vegetation Maintenance and Implementation Plan Duke Energy – Roxboro Steam Station Roxboro Industrial Landfill Person County, North Carolina Amec Foster Wheeler Project No. 781010864 Page 1 of 3 03/24/2017 1 Background 1.1 Facility Description The Roxboro Steam Station is located at 1700 Dunnaway Road in Semora, Person County, North Carolina. The Roxboro Industrial Landfill (referred to as the landfill) is located predominantly within the footprint of the filled East Ash Basin (EAB), which was constructed to receive sluiced ash from the Roxboro plant. When the plant converted to dry fly ash handling, an unlined industrial landfill was permitted in the East Ash Basin area. In 1988 the North Carolina Department of Environment and Natural Resources (now Department of Environmental Quality, NCDEQ) issued Solid Waste Permit No. 7302 for the unlined industrial landfill. The approximate limits of the unlined landfill are shown on Figure 1. In 2001, a plan for a lined industrial landfill was developed. The limits of lined landfill Phases 1 through 6, also permitted under Solid Waste Permit No. 7302, are shown on Figure 1. The exposed portion of the unlined landfill has interim cover consisting of soil with stabilizing vegetation or road surfacing material throughout. The surface of the lower portion of the eastern slope contains some woody vegetation and trees. Duke Energy wishes to facilitate visual inspection of the surface of the interim cover. 1.2 Scope of Plan The intent of this Vegetation Maintenance and Implementation Plan (referred to as the Plan) is to outline requirements for clearing and maintaining portions of the landfill to facilitate visual inspection of the area and to improve the integrity of the soil cover by removal of woody material. Specifically, Duke Energy intends to remove trees and woody vegetation from approximately 6 acres on the lower portion of the east slope of the Landfill (referred to as “this project”). This project and any subsequent clearing projects will involve the removal of all woody material. Trees 2-inches or less in diameter will be removed without disturbing the subsoil and leaving roots and root balls in place. Trees 2-inches or greater in diameter will be removed along with roots and root balls. Trees and debris from vegetation removal will be disposed of at an offsite Land Clearing and Inert Debris (LCID) landfill, except as follows. For root balls containing ash, the Owner will identify handling and disposal methods in accordance with station permits and waste management regulations. This Plan provides guidance on vegetation removal from brush to large trees with the intent of maintaining the function of the landfill interim cover.Removal of trees will be completed under the direction of the System Owner. Approved erosion and sedimentation control measures (which are not described in this plan) will be implemented. 2 Management of Landfill Vegetation 2.1 Existing Conditions The existing vegetation on the landfill is predominantly non-woody vegetation, but includes heavy brush and trees on the lower portion of the east slope. It is the intent of Duke Energy to remove woody vegetation to facilitate inspection of the east slope of the unlined landfill. The procedures used to remove the existing woody vegetation will be different than the methods for routine upkeep. After the initial woody vegetation removal, the need for any additional woody vegetation removal will be established by Duke Energy personnel. 2.2 Chemical Vegetation Control If there are areas of dense woody vegetation where access by mowers is limited, these areas may be managed using herbicides. It is critical that chemical treatments be applied by qualified personnel in accordance with manufacturer's directions, Duke Energy safety practices and the Roxboro Steam Station NPDES and groundwater subject management expert. This document is not intended to serve as a guide to chemical vegetation management. Refer to literature provided by Duke Energy, State of North Carolina and Person County for guidance regarding chemical vegetation control, including the proper methods, application rates, frequency and season of the year for applications. Vegetation Maintenance and Implementation Plan Duke Energy – Roxboro Steam Station Roxboro Industrial Landfill Person County, North Carolina Amec Foster Wheeler Project No. 781010864 Page 2 of 3 03/24/2017 2.3 Brush The lower portion of the east slope of the landfill is covered with dense brush. This obscures visual inspection of the area and prevents walking or vehicle access. Where accessible, brush can be managed using mechanical methods, such as mowers and hand held trimmers. For large areas, or areas where access for conventional mowers or bush hogs is not available, specialized forestry management equipment can be used to clear brush and trees. Such equipment must be operated by qualified personnel subject to Duke Energy safety requirements. Reconnaissance of ground surface conditions should be conducted prior to introduction of mowing equipment. Brush covered areas adjacent to monitoring wells, culverts, and waste markers should be managed using hand equipment. Brush from this project be ground or chipped on site and used as appropriate temporary erosion control measure on this project. 2.4 Trees 2-Inches or Less (DBH) Trees with a diameter of 2-inches or less (as measured at breast height, or "DBH") should be removed and not allowed to be re-established on the landfill surface.This is best accomplished by routine mowing. Potential for impact to the interim cover is low. In general, trees of this size should be managed the same as brush as described above. 2.5 Trees 2-Inches or Greater (DBH) Individual trees greater than 2-inches in diameter DBH that are identified for removal should be marked in the field using surveyor ribbon or similar material. Removal of trees greater than 2-inches in diameter shall be performed by cutting the trunk flush at the ground surface, removing the stump and root ball, cleaning the root ball cavity, backfilling with compacted soil, installing erosion control matting, and stabilizing with permanent vegetation. If practical, segregate and stockpile available topsoil for later reuse. The entire stump and root ball should be removed, including roots in excess of 2-inches in diameter.This may require excavation into CCR. If CCR is exposed and excavated, it should be managed separately from cover soil and vegetation. At the discretion of the Duke Energy personnel, CCR removed from excavations as part of interim cover maintenance can be placed back into the excavation providing the original interim cover surface elevations are generally maintained. All such areas must be covered by a minimum 2-foot thickness of interim cover soil. Alternately, CCR can be removed from the area and disposed in the active area of the landfill. Excavations through the interim cover should be prepared for interim cover placement by stepping or benching the sides of the excavation to allow effective blending of the new and in-place interim cover soils. Loose materials at the base of the excavation,including CCR should be graded and compacted as needed before placement of the cover soil. Cover soil should be placed in thin lifts. Lift thickness is dependent of the size of the repair area, the type of soil used for cover and the type of grading and compaction equipment used. As a guideline, a maximum loose lift thickness of 8-inches is suitable for lightweight compaction equipment. Lift thickness can be increased or decreased depending on the equipment available and the geometry of the repair area. Monitoring of the repair by a qualified engineer or technician is recommended.The following activities are recommended: x Documentation of the location of the repair, and the nature of the repair, x Size and depth of the excavation, x The presence of CCR in the excavation and the fate of any CCR removed from the excavation as part of the repair, x The conditions of the base and sides of the excavation prior to backfill (i.e., loose materials, preparation of slopes by benching, etc.), x Source and classification of interim cover soils used in the repair (include available field or laboratory Proctor data, etc.), Vegetation Maintenance and Implementation Plan Duke Energy – Roxboro Steam Station Roxboro Industrial Landfill Person County, North Carolina Amec Foster Wheeler Project No. 781010864 Page 3 of 3 03/24/2017 x Lift thickness, compaction methods and equipment, number of passes, x Density testing (if completed), x Surface restoration, including topsoil, mulching, seeding, x The total thickness of the interim cover soil should be measured and recorded to document compliance with regulatory criteria, x Follow-up inspections to monitor establishment of vegetation, erosion, etc. It is recommended that filling of excavations associated with root ball removal and other repair areas where CCR is exposed be completed as quickly as possible after excavation. Grade the surface of the repair into the adjacent interim cover areas in a way that does not result in erosion or trapped surface water runoff. This may require placement of interim cover soils in areas outside of the original repair area. If this is the case, it is recommended that the vegetation and topsoil be removed before placement of the interim cover soil. Once repairs are completed, place topsoil (if available) and erosion control matting. Establish vegetation in accordance with the solid waste permit requirements. Monitor repair areas and correct any deficiencies noted in the interim cover. 2.6 Phasing of the Clearing Operations During any required clearing operations, removal of large trees and their stumps could be delayed until safe effective access is established by removal of brush, etc. These operations could also be delayed until a more favorable season of the year.It is not the intent of this document that all trees and brush must be removed in a single operation. Duke Energy staff should phase the work as needed to most effectively and safely manage the vegetation removal process. 3 Interim Cover Maintenance 3.1 Inspection Inspections will be performed at a frequency in accordance with the solid waste permit for the landfill. Inspection and maintenance of the interim cover are to be completed only when conditions are deemed safe for personnel and for the operation of equipment. It is recommended that annual inspections be conducted at the same time each year to best document changed conditions between inspections, and to plan and monitor maintenance, etc. Inspection during the winter months provides the best visibility of the cover surface since vegetation is generally dormant. Inspection of vegetation should be completed during the summer months. 3.2 Erosion Areas of erosion noted during inspections will be repaired as needed by methods including filling, regrading, vegetating, and installing erosion control matting. 3.3 Earthen Cover Maintenance of vegetation, repairs to or installation of ditches,or repairs to eroded areas require placement of a minimum of a 2-foot thickness of compacted soil over the top of the CCR. For purposes of this document, soils used for repairs of the unlined landfill should meet the following requirements: x Soils consisting of clean natural soil classified as SM, SC, ML, or CL-ML, MH, CH using the Unified Soil Classification System (USCS) containing no topsoil or other deleterious material, x No particles exceeding 4 inches in size, and x Compaction to at least 93% of the maximum dry density determined by test method ASTM D698.