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CD Application Technical Comments #1 September 9, 2011 <br />Western Gravel Disposal Facility Page 2 <br />2. 3.1 Waste Characteristics and 3.9.4 and 3.9.5 — It must be very clear what wastes will and will not be <br />accepted at this facility. The Division understands that petroleum contaminated soil (PCS) will be accepted, <br />following waste characterization and that E &P drill mud will not be accepted. If waste will be amended on <br />site the details of this operation must be described including materials /chemicals to be utilized and material <br />management. Note that oil/gas companies may amend the drill cuttings with wood chips or other organic <br />matter that may decompose or settle and must be accounted for in the D &O plan. For suspicious waste <br />consider setting it aside, within the cell, for additional testing rather than loading it back into the truck where <br />it may be illegally disposed elsewhere. <br />3. 3.3 and other sections — Consider developing the landfill in 2 phases; Cells associated with Pond 1 and cells <br />associated with Pond 2. Phase 2 for mining is outside the proposed CD boundary to the southeast so <br />discussion of that future operation should be minimal. <br />4. 3.4.2 — Blasting of the bedrock will not be approved because it may further enhance any existing joints or <br />fractures beneath the cells. <br />5. 3.4.2 and 3.4.4 — Liner System — Consider revising the grading plan for the cells such that the sub -grade <br />slopes away from the steep slope to the north and moving the leachate collection sump and the leak detection <br />to the south side of each cell. Also consider using a fine grained fill material beneath the secondary liner to <br />"fill" any large joints or fractures in the bedrock and thereby constructing a composite liner as the secondary <br />liner. <br />6. 3.4.5.1 — P1 last sentence - Replace "leachate collection" with "leak detection" <br />7. 3.4.5.2 — Consider adding chlorides for testing any liquid in the leak detection system because sodium <br />chloride may be a common constituent in drill cuttings and should be present in any leak in the primary liner <br />and can be used to distinguish fluid from surface precipitation. <br />8. 3.4.6.1and Figures5B and 6B — The one -sided geonet for the leachate collection system may be exposed to <br />surface precipitation along the top of the perimeter berm and in the anchor trench. Also one common path for <br />fluid entrance into a leak detection system is in the anchor trench. Consider having 2 anchor trenches. ' The <br />"inside" trench would hold the secondary liner and LDS geonet. The "outside" trench would hold the <br />primary liner and would better protect the LDS geonet from surface precipitation. <br />9. 3.4.6.1 and 3.4.7 — Twelve inches (12 ") of soil may not be adequate to protect the primary liner from damage <br />from some heavy equipment. Provide a listing of smaller equipment that can be utilized during the early <br />filling stages of the cell and the corresponding soil thickness(es). Provide the soil thickness necessary for <br />unrestricted equipment use within the cell. The manufacturers provide operational weight specifications for <br />specific liner materials. <br />10. 3.4.6.2— Monitoring of the leachate collection sump should be more frequent than monthly. At a minimum <br />conduct weekly monitoring during the spring and in the initial stage of cell filling. <br />11. 3.4.7 - LCRS sump design — Consider placing a piece of 60 mil HDPE beneath the leachate pipe for damage <br />protection rather than 4 inches of protective soil. A geotextile is preferred over the 4 inches of protective soil <br />so that the leachate pipe can remove as much fluid head as possible. <br />12. 3.4.9.1 — A potential problem with using geocomposite clay (GCL) in a final cover system is burrowing <br />animals and root penetration. Provide additional justification for the cover design, including the seed <br />mixture, that the 3.5 feet is capable of supporting a root system and of sufficient thickness to protect the <br />barrier layer in accordance with Section 3.5.3B(6). Biotic barrier protection may be achieved with a layer of <br />sand/gravel, a geosynthetic product, chemicals or a composite cover system that includes a flexible <br />membrane component (GSE Gundseal or Bentomat CLT). Additional evaluations are warranted for cover <br />design involving GCL including a drainage layer above the GCL, anchor trenches, component specific slope <br />stability analysis and chemical compatibility testing with the cover soil. Consider a water balance cover as <br />discussed in comment #32 below which could be designed at the time of closure. <br />13. 3.4.9.2 — Revise text because leachate is "generated" with any storm event where fluid collects on the waste <br />and/or enters the LCRS. HELP model results provide the estimated seepage through the barrier layers and <br />flow into drainage layers. <br />14. 3.5.2 — The run -on control structures should protect the closed cells in perpetuity and therefore should be <br />designed for the 100 year, 24 hour storm event. The long -term plan for the access road (retained or reclaimed <br />