2024-01-31_REVISION - M1977344 (21)

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Portland Limestone Quarries (M-1977-344) Permit Amendment-02 Holcim US Inc, 3500 Highway 120, Florence, CO 81226 Revised pursuant to preliminary adequacy review November 20, 2023 Phone (719) 288-1443 www.holcim.us 91 areas on the site are grasslands with gentle slopes, few outcrops, and sparse shrubs and trees compared to the Red Creek drainage. Another feature on the Site is the Minnequa canal, owned by Rocky Mountain Steel Mills. The canal flows across the RCQ property along the northeast corner, diverting water from the Arkansas River at Florence for irrigation purposes and municipal/domestic use. The canal is fully fenced and is siphoned under Red Creek, just north of the Site property boundary. 2.7.2 U.S. Army Corp of Engineers Holcim engaged BC to begin the preliminary jurisdictional determination (PJD) for the Red Creek Quarry parcel in Fall 2019. BC personnel conducted a field reconnaissance at the Site on May 28, 2019 to observe and document conditions of the property, specifically related to the surface water drainages on the Site. The location of the sites visited are shown in Figure 2.7.2 -1. A second field visit was conducted on October 1, 2019, with Joshua Carpenter, regulatory staff with the United States Army Corps of Engineers (USACE), Albuquerque District, Pueblo Regulatory office to review the site conditions and discuss potential jurisdictional resources. Based on these two field visits, BC submitted a preliminary jurisdictional determination (PJD) request to the USACE; on May 21, 202 0, the USACE issued the initial PJD letter stating they concurred with the BC assessment. The USACE-approved PJD provided Holcim with the information necessary to start planning for mining operations and the disturbance footprint given the locations of jurisdictional resources. Based on the need for better defining the limits of ephemeral tributaries to Red Creek on the site, a second field reconnaissance was conducted by BC on December 3, 2020. Initially, the first limits between upland non-jurisdictional drainages and ephemeral tributaries were delineated using the dirt road that runs east-west across the property as the basis for the distinction between jurisdictional and non-jurisdictional resources. As such, a second, initial PJD form was submitted to U.S. Army Corps of Engineers (USACE) on January 8, 2021, with the revised stream field review. The revised USACE PJD approval from the USACE was received on November 10, 2022 (BC 2021, Appendix 4.2). A figure of the delineated stream and wetland resources are provided in Appendix 4.2 (BC 2021). A desktop evaluation of the aquatic resources along the MTAC began in September of 2023 for a PJD associated with this footprint. The corridor evaluation identified drainages within the MTAC that could be jurisdictional based on the observations made with aerial photos, topographic maps, and other readily available desktop data. The MTAC PJD form will be submitted to the USACE upon application completion. USACE correspondences and BC field documents are provided in Appendix 4.2.