2024-01-31_REVISION - M1977344 - Laserfiche WebLink

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4/12 Response: The fence will be constructed on both sides of the conveyor. Exhibit L is revised accordingly. 16. Salvaged Growth Material: The second paragraph on p. 47 states plant growth material will be salvaged and stockpiled in the bottom lift of a two-lift stockpile, and that overburden will be stockpiled on top of the growth media. Rule 3.1.9 requires growth media be segregated for other spoil. Placing overburden on top of growth media will make it difficult to distinguish between the two over a period of time. Please commit to stockpiling the two materials separately (side-by-side would be acceptable if the growth media is labeled with signage). Response: Section 2.4.5 is revised to clarify that all salvaged topsoil will be used to construct the perimeter 10-ft berm. During initial development the temporary stockpile will only contain limestone and overburden. 6.4.5 Exhibit E- Reclamation Plan 17. Bear Creek Quarry and Plant Area: No information was provided for the current reclamation plan related to the Bear Creek Quarry or the Plant Area. Pursuant to Rule 1.10.1(2) the Applicant may avoid the requirement to submit all site-wide reclamation plan information if it is clearly described in the amendment application where in the original application and supporting documents the information not included in the amendment may be found. Response: The BCQ and Plant Area reclamation plan is included by reference in paragraph two of the introduction to Section 2.5. 18. Overburden use: The fourth paragraph under Section 2.5 states “An abundance of overburden exists to the extent that benches will be sloped with ample overburden to raise the mine floor elevation.” Please explain how sloping the benches will raise the mine floor elevation. Response: The referenced statement is restated as follows: An abundance of overburden exists to the extent that the lowest two benches will be completely backfilled thus raising the elevation of the mine floor. 19. Appropriate grading: Rule 3.1.5(1) requires the final grading be evaluated as appropriate for the post mine land use. The Exhibit F grading plan shows the smaller pit on the north side of Red Creek and the much larger pit on the south side have no drainage outlets. By contrast the Bear Creek Quarry has a reclamation plan allowing stormwater to drain to the Arkansas River. The DRMS is concerned that significant precipitation events may lead to ponded stormwater in the lowest portions of the pits that will not infiltrate within the 72 hours required by the Colorado Division of Water Resources. Please describe how the 72-hour drain down requirement will be met after reclamation is completed. Response: The potential precipitation from a 5-year, 24-hour storm event was calculated to determine the volume of precipitation that would infiltrate within 72-hours as a result of the storm. Section 2.4.8 in Exhibit D is revised to include construction of infiltration galleries in the quarry floor where stormwater is likely to migrate and where enhancement of infiltration may be necessary. The infiltration galleries will be constructed by excavating into the sandstone to increase the permeability and backfilling the excavation with coarse rock. Exhibit F Reclamation Plan Map is also revised to show the potential locations of the infiltration galleries.