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HomeMy WebLinkAbout6204_UwharrieMSWLF_CommentonUnderdrain_cell14B_DIN27511_201703141 Chao, Ming-tai From:Chao, Ming-tai Sent:Tuesday, March 14, 2017 1:17 PM To:'MCheek@HHNT.COM' Cc:Reynolds, Joe; Eric Jackson; Ritter, Christine; Mussler, Ed; Bradford, Teresa Subject:Comments on the underdrain piping plan at Cell 14 B, Uwharrie MSWLF, 62-04 , DIN 27511 Hi Matt: DIN 27511 The Solid Waste Section (SWS) reviews the underdrain piping plan (DIN 27508) at the Uwharrie Regional Landfill – Cell 14B and has several concerns on the proposed underdrain piping plan (the Plan) which are stated below: 1. Please state why the options to construct an underdrain piping which carries seepage to the area on the south or west sides of the Cell 14B are not viable. 2. The Plan is required to provide approaches to determine if the seeps observed at the Cell 14B area are a one-time event but dry-up eventually or an intermittent or a permanent flow. To determine if the underdrain should be placed underneath the landfill in the future, the plan should provide the following info, but not limited to: i. The routine (such as daily or weekly) monitoring, measuring, and documenting flow volume at the exit of the underdrain pipe (inside the future Cell 15) for a specified period prior to construction of Cell 15. The weather conditions (including the precipitation amount for a period) should be recorded for the reference. ii. The personnel conduct the routine task. iii. The conclusions or findings of the status of seeps (including the data collected from the task mentioned in the item i) should be a portion of the permit application for construction and operations of the future Cells 15 or 16. The approaches to manage the seeps in the future must be discussed in the application, such as plug & abandoned the underdrain piping if the seeps are terminated naturally, or the construction and extension of the piping to incorporate the future landfill activities, if the seeps are determined as a permanent flow. 3. Based on the data shown on the cross-section drawing (DIN 27508), the invert depths of the proposed pipe trench range from approximately 2 to 15 feet below the existing grades. The tasks associated with excavation of trench, installation of piping, and backfill the trench must be safely executed according to OSHA Excavation Standards – trenching and shoring which must be provided in the Technical Specification Section 02722. 4. The existing site-wide WQMP for the landfill must be revised to include the sampling and analyzing of the seeps at the end of the underdrain piping. The revised plan should be submitted to the SWS for a review and approval. 2 Please submit a hard copy and an electronic copy of the revised plan which are incorporated the responses to the above-mentioned comments. Should you have any questions of the above-mentioned comments please contact me. Have a wonderful day. Ming Chao Ming-Tai Chao, P.E. Environmental Engineer Permitting Branch, Solid Waste Section NCDEQ, Division of Waste Management (Mailing Address) 1646 Mail Service Center Raleigh, NC 27699-1646 (Street Address) Green Square, 217 West Jones Street Raleigh, NC 27603 Tel. 919-707-8251 ming.chao@ncdenr.gov http://portal.ncdenr.org/web/wm/sw E-mail correspondence to and from this address may be subject to the North Carolina Public Records Law and may be disclosed to third parties.