2016-11-29_REVISION - M1977141 - Laserfiche WebLink

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Lyons Quarry ��` 112d Reclamation Permit Operations Z Technical Revision • Placed in a manner that allows for a moisture content within 3% of optimum based on ASTM D698 Final Grading of all fill slopes, benches, crest areas, and toe areas will ensure that water is not allowed to pond on or adjacent to the fill slopes. Item 6.0 — Fill Slope Scour Protection The toe areas of fill slopes that extend into the low-lying areas and the flood way of South St. Wain Creek will be protected from scour by future flood events by the construction of a riprap scour berm as shown in Section B of the Site Grading Plan, Attachment A. The scour protection will be designed to withstand a minimum 100 year flood event and the size of the riprap to be used will be determined during final design. The riprap gradation assumed for the scour berm in the preliminary design includes a D50 between 36 and 48 inches. This scour berm will also allow minor re-grading of existing slopes to provide for long term slope stability. It is estimated that approximately two- thousand (2000 LF) of scour berm will need to be constructed. Item 7.0— Reclamation Areas and Soil Conditioning Reclamation areas have been differentiated by a site slope analysis as shown on Exhibit F- Reclamation Plan Map, Attachment C. Areas of 1.511:1V slopes will be too steep to effectively apply soil amendments and produce a vegetative cover; therefore the slope will be covered with a 2-foot thick layer of talus riprap (D50 = 12 to 14 inches) and compacted using an excavator bucket. Approximately 4.8 acres will require talus riprap coverage. We anticipate that sufficient talus riprap can be generated from the massive sandstones onsite and will be selectively blasted and screened as needed to produce specified grading. Areas with slopes flatter than 1.5H:1V will be reclaimed in a manner that allows for livestock grazing and movement along the slope face. These areas will be backfilled as described above then covered with a layer of growth medium material (i.e. topsoil, biosolids, compost). The growth medium material will be developed from a blend of any available topsoil stockpiled on site and material available from the excavation and breakdown of the fine grained sedimentary overburden rock, supplemented as needed by imported topsoil, biosolids, or compost, then blended, scarified, seeded and mulched. This material will then be uniformly mixed, via rippers or the teeth of an excavator bucket, in to the top 6 to 12 inches of the on-site subsoil. It is anticipated that the area to receive amendments covers approximately 39 acres. Item 8.0 — Sedimentation Pond Reclamation The sedimentation pond will be backfilled at the end of reclamation to blend with the surrounding topography, unless post-mining use dictates otherwise. Backfill requirements will be the same as those stated in Item 5.0. The pond will be backfilled using approximately 2,200 cubic yards of earthfill at a rate that does not produce any surface water runoff. Item 9.0 - Revegetation The final reclamation topsoil/growth medium, seeding, fertilization, and revegetation will be determined based on the results of Test Plots developed using the soil types and slopes planned for reclamation, to assist in determining the appropriate types and methods for reclamation. Seeding of the affected lands assumes a native seed mix comprised of the species and mixtures recommended by Boulder County Land Use Department. Table 2 shows the native seed mix recommended for 5,500 to 7,000 feet elevation. The listed quantities and application rates are November 2016 1 7