Loading...
1.01 General Application Materials_PartBTitle:Revision#Dwg No.Job No.Drawn by:Date:File:PE:QC:Date By: Project Milestone:Of :2019-341.002RPFRPFRiflePit-ExhibitsABF6118 West Sixth Street, Suite 200Glenwood Springs, CO 81601970.945.1004 www.sgm-inc.com Graphic ScaleIn U.S. Feet : 1" = 200'0 100 200400IHC-Scott, Inc. dba Scott Contracting, Inc. 13Permit Set (Not For Construction)Mining ProgressionExhibit - 30%Rifle Pit Gravel Pit #104/14/202204/14/2022 Title:Revision#Dwg No.Job No.Drawn by:Date:File:PE:QC:Date By: Project Milestone:Of :2019-341.002RPFRPFRiflePit-ExhibitsABF7118 West Sixth Street, Suite 200Glenwood Springs, CO 81601970.945.1004 www.sgm-inc.com Graphic ScaleIn U.S. Feet : 1" = 200'0 100 200400IHC-Scott, Inc. dba Scott Contracting, Inc. 13Permit Set (Not For Construction)Mining ProgressionExhibit - 60%Rifle Pit Gravel Pit #104/14/202204/14/2022 Title:Revision#Dwg No.Job No.Drawn by:Date:File:PE:QC:Date By: Project Milestone:Of :2019-341.002RPFRPFRiflePit-ExhibitsABF8118 West Sixth Street, Suite 200Glenwood Springs, CO 81601970.945.1004 www.sgm-inc.com Graphic ScaleIn U.S. Feet : 1" = 200'0 100 200400IHC-Scott, Inc. dba Scott Contracting, Inc. 13Permit Set (Not For Construction)Mining ProgressionExhibit - 100%Rifle Pit Gravel Pit #104/14/202204/14/2022 Title:Revision#Dwg No.Job No.Drawn by:Date:File:PE:QC:Date By: Project Milestone:Of :2019-341.002RPFRPFRiflePit-DesignABF9118 West Sixth Street, Suite 200Glenwood Springs, CO 81601970.945.1004 www.sgm-inc.com Graphic ScaleIn U.S. Feet : 1" = 120'0 60 120240IHC-Scott, Inc. dba Scott Contracting, Inc. 13Permit Set (Not For Construction)Erosion Control PlanRifle Pit Gravel Pit #104/14/202204/14/2022 Title:Revision#Dwg No.Job No.Drawn by:Date:File:PE:QC:Date By: Project Milestone:Of :2019-341.002RPF04/14/2022RPFRiflePit-DetailsABF10118 West Sixth Street, Suite 200Glenwood Springs, CO 81601970.945.1004 www.sgm-inc.com IHC-Scott, Inc. dba Scott Contracting, Inc. 13Permit Set (Not For Construction)Erosion Control DetailsRifle Pit Gravel Pit #1 04/14/2022 Title:Revision#Dwg No.Job No.Drawn by:Date:File:PE:QC:Date By: Project Milestone:Of :2019-341.002RPF4.14.2022RPFRiflePit-DetailsABF11118 West Sixth Street, Suite 200Glenwood Springs, CO 81601970.945.1004 www.sgm-inc.com IHC-Scott, Inc. dba Scott Contracting, Inc. 13Permit Set (Not For Construction)Typical Mineral StrataRifle Pit Gravel Pit #104/14/202204/14/2022 Title:Revision#Dwg No.Job No.Drawn by:Date:File:PE:QC:Date By: Project Milestone:Of :2019-341.002RPFRPFRiflePit-DetailsABF12118 West Sixth Street, Suite 200Glenwood Springs, CO 81601970.945.1004 www.sgm-inc.com IHC-Scott, Inc. dba Scott Contracting, Inc. 13Permit Set (Not For Construction)Typical GravelProcessing LayoutRifle Pit Gravel Pit #104/14/202204/14/2022 Title:Revision#Dwg No.Job No.Drawn by:Date:File:PE:QC:Date By: Project Milestone:Of :2019-341.002RPFRPFRiflePit-DetailsABF13118 West Sixth Street, Suite 200Glenwood Springs, CO 81601970.945.1004 www.sgm-inc.com IHC-Scott, Inc. dba Scott Contracting, Inc. 13Permit Set (Not For Construction)Spill Prevention Control& Containment (SPCC)DetailRifle Pit Gravel Pit #104/14/202204/14/2022 IHC Scott – Rifle Gravel Pit #1 August 2022 Garfield County Special Use Permit Application Appendix D Appendix D – Referral Agency Letters IHC Scott – Rifle Gravel Pit #1 May 2022 Garfield County Special Use Permit Application Appendix E Appendix E – Wetland Report Comprehensive Wetland Delineation Report & USACE Boundary Confirmation DEPARTMENT OF THE ARMY U.S. ARMY CORPS OF ENGINEERS, ALBUQUERQUE DISTRICT 400 ROOD AVENUE, ROOM 224 GRAND JUNCTION, CO 81501-2520 July 27, 2022 Regulatory Division (SPK-2020-00172) SUBJECT: Aquatic Resource Boundary Confirmation IHC Scott Attn: Tony Roberts 9200 E Mineral Ave Centennial, CO 80112 troberts@scottcontracting.com Dear Mr. Roberts: We are responding to your request for verification of an aquatic resource delineation for the Rifle Gravel Pit #1 site. The 50.4-acre project site is located approximately 3 miles east of the Town of Rifle, directly north of Interstate 70, within the SW ¼ SE ¼ of Section 8, Township 6 South, Range 92 West, Sixth Principal Meridian, latitude 39.53368°, longitude -107.69272°, Garfield County, Colorado. Based on available information, we concur with your aquatic resource delineation for the site, which consists of approximately 18.28 acres of palustrine emergent wetland and 1.13 acres of non-wetland open water (irrigation tailwater ditch), as depicted on the enclosed February 8, 2022, Delineated Aquatic Resources, prepared by SGM, Incorporated (Enclosure 1). This verification letter does not constitute a determination of jurisdiction (JD). A JD is not required to process an application for a Department of the Army permit. If you do not require a JD for the site, your permit application may be processed sooner . You may request a JD for this site at any time prior to starting work in aquatic resources, including after a permit decision is made. To request a JD for this site, complete the attached Request for Jurisdictional Determination Form (Enclosure 2) and return it to this office at the address listed below. Please refer to identification number SPA-2022-00172 in any correspondence concerning this project. If you have any questions, please contact me at the Northwestern Colorado Branch, 400 Rood Avenue, Room 224, Grand Junction, Colorado 81501, by email at Tyler.R.Adams@usace.army.mil, or telephone at -2- (970) 243-1199, extension 1013. To complete our Customer Service Survey, visit our website at: https://regulatory.ops.usace.army.mil/customer-service-survey/ Sincerely, Tyler R. Adams Project Manager NW Colorado Branch Enclosures cc: Glenn Hartmann, Garfield County, ghartmann@garfield-county.com Lucas West, Division of Reclamation, Mining and Safety, lucas.west@state.co.us Alex Nees, SGM, Inc., alexn@sgm-inc.com SPK# 2020-00172 Prepared for: U.S. Army Corps of Engineers Colorado West Regulatory Office IHC Scott Albuquerque District, Regulatory Division 9200 East Mineral Ave, Suite 400 400 Rood Avenue, Room 224 Centennial, CO 80112 Grand Junction, Colorado 81501-2563 Prepared by: SGM, Inc. 259 Grand Avenue, Suite 200 Grand Junction, CO 81501 2019-341.002 February 28, 2022 www.sgm-inc.com Comprehensive Wetland Delineation Report & Request for Boundary Confirmation Rifle Gravel Pit #1 Garfield County, Colorado Wetland Delineation Report Rifle Gravel Pit #1 February 2022 i Comprehensive Wetland Delineation Report & Request for Boundary Confirmation Rifle Gravel Pit #1 (SPK# 2020-00172) Garfield County, Colorado Prepared for: U.S. Army Corps of Engineers Colorado West Regulatory Office IHC Scott Albuquerque District, Regulatory Division 9200 East Mineral Ave, Suite 400 400 Rood Avenue, Room 224 Centennial, CO 80112 Grand Junction, Colorado 81501-2563 Prepared by: SGM, Inc. 259 Grand Avenue, Suite 200 Grand Junction, CO 81501 Submitted to: Colorado West Regulatory Office U.S. Army Corps of Engineers 400 Rood Avenue, Room 224 Grand Junction, Colorado 81501-2563 Wetland Delineation Report Rifle Gravel Pit #1 February 2022 ii Contents 1. APPLICANT AND SITE INFORMATION ........................................................................................................... 1 Wetland Delineation Report Rifle Gravel Pit #1 February 2022 1 1. APPLICANT AND SITE INFORMATION IHC Scott (formerly Scott Contracting Inc.) requested that SGM delineate all potential wetlands and other Waters of the U.S. for a gravel pit development project in Garfield County, Colorado. The project would be new development, located on the site of an existing cattle pasture which has been irrigated up until 2021. The parcel is divided by an irrigation tailwater ditch that carries agricultural return flows to a discharge point on the Colorado River. IHC Scott is proposing partial development of the parcel, with the intention of confining the pit infrastructure to upland portions of the property and entirely avoiding direct impacts to jurisdictional wetlands and Waters of the U.S. (WoUS) on the property. There are anticipated to be no regulated impacts as a result of the proposed activity. The conceptual outline of the proposed development is discussed in this report, but is not addressed in depth report. This report has been prepared in accordance with regulatory guidance for submittal to the U.S. Army Corps of Engineers (USACE) to request a wetland boundary confirmation without accompanying jurisdictional determination. A No Permit Required letter is not requested at this time. This report has been submitted to assist in planning and communication between IHC Scott and regulatory agencies, primarily the USACE, but also Garfield County. Wetland Delineation Report Rifle Gravel Pit #1 February 2022 2 · The findings of the August 13, 2021 ARDR were rejected, and a resubmittal was requested that would use the transect-based approach and incorporate Problematic Hydric Soils procedure into the boundary determinations. Wetland Delineation Report Rifle Gravel Pit #1 February 2022 3 Wetland Delineation Report Rifle Gravel Pit #1 February 2022 4 2. PROJECT DESCRIPTION IHC Scott is proposing to construct a new gravel pit development project in Garfield County, Colorado. The project would be new development, located on the site of a cattle pasture receiving irrigation return flows; the pastures are not intentionally irrigated at this time but have been in the recent past (Figures 1 and 2). The applicant is proposing partial development of the parcel, with the intention of confining the pit infrastructure only to upland portions of the property (generally the eastern portion), and entirely avoiding direct impacts to jurisdictional wetlands and WoUS (generally on the western portion of the property). The subsurface conditions are typical of gravel pits and aggregate mines in the Colorado River floodplain: the surface layer consists of between one and seven feet of alluvially-deposited fine sediments (primarily silts and clays), overlying 17-22 feet of alluvial gravels. Shallow groundwater, connected to the water table of the Colorado River, saturates the gravels and is generally present throughout the project site at a depth of between one and five feet. These assessments are based on exploratory subsurface drilling work from 2008 (Appendix E). The proposed development would be a wet mining operation. In wet mining operations of the type IHC Scott proposes, the overburden is removed and stockpiled for onsite use or sale as topsoil, and the saturated alluvial gravels are excavated in their saturated state using a long-reach excavator. No dewatering activity or groundwater pumping occurs, and the excavated pit fills with groundwater to become a pond as mining progresses through the site. This is in contrast to a typical aggregate mine operation, where dewatering (generally through pumping) lowers the groundwater and then the pit is excavated with machinery in the bottom of the pit, and after operations are complete the dewatering stops and the pit is allowed to fill with groundwater to become a pond. A very brief conceptual description of the proposed mining plan is included here for reference. Note that permit applications with the Division of Reclamation, Mining, and Safety (DRMS) and Garfield County Community Development are both in process and specific operational details of this project may be subject to change based on feedback from these agencies. · A paved access apron would be constructed to access the project site from the Interstate- 70 frontage road. CDOT has reviewed the plans and issued an access permit to allow for this construction. · A processing and sales facility (scale house) would be constructed at the entrance to the project site. This would include the material stockpiles, loading chute and processor, the scale house, vehicle parking, and the minimal facilities needed onsite staff (portable toilets, water tank, work trailer). · The overburden (1-7 ft of fine sediments) would be removed from the mine area. The overburden would be used to construct a 5-ft tall perimeter berm around the mine area, to control visual and noise impacts in accordance with Garfield County Land Use Code (LUC) standards. The outer edge of the perimeter berm would be located 25 feet from the boundary of any wetland areas, pending approval of a variance from the 35-foot wetland setback in the LUC. The berm surface would be stabilized and re-seeded to control erosion. Any remaining overburden material would be stockpiled at the processing facility for sale as topsoil. Wetland Delineation Report Rifle Gravel Pit #1 February 2022 5 · The working surface of the mine would consist of the exposed alluvial gravel surface. A long- reach excavator stationed on the edge of the pit would excavate material to a depth of approximately 20 feet. The pit would be full of water, forming a pond that expands as the excavator continues to remove material, and which is in direct contact with the water table of the Colorado River via lateral migration through the underlying permeable gravels. Excavated material would be piled on the edge of the pond for approximately 24 hours, to allow drainage of free water from the material and back into the pond. · Sideload dump trucks would travel to the pond edge, and would be loaded with the dried material on a daily basis. The dump trucks would transport the dried material from the active excavation area to the processing facility, where the material would be stockpiled for washing, processing, and subsequent sale. · Any agricultural return flows in the tailwater ditch, which are estimated at less than 2 cfs during peak irrigation season, would be discharged into the pond. The discharge would mix with the alluvial aquifer waters which are exposed in the pond, and the combined waters would migrate laterally through the underlying permeable gravels into the larger Colorado River water table. Given the minimal flows in the ditch, the large size of the pond (estimated at 6 acres within the first year of operation), and the highly-permeable nature of the gravel, the agricultural return flows would have a negligible effect on water levels in the pond. As excavation proceeds, the eastern portions of the tailwater ditch, which is artificially excavated in an upland area, would be subsumed into the expanding pond boundaries, until under final conditions the discharge point would be where the ditch enters the eastern boundary of the property. · Reclamation would proceed in concert with the excavation. A six-foot wide fringe of gentle slopes (e.g., 5:1 slopes) would be left at the inner edge of the perimeter berm, and planted with wetland reclamation species. The intention is for the six-foot wide fringe to be nearly inundated during high-water periods as the water table rises, and then to be progressively exposed as the water table drops during the course of the growing season. Note that this draft reclamation effort is in compliance with Garfield County LUC standards, and is not intended to serve as formal wetland mitigation per USACE standards. · At this time, the proposed mine would operate daily, with excavation and processing occurring eight months of the year (roughly April – May) and with material sales occurring year-round. Total recoverable volume is estimated at approximately 300,000 cubic yards of aggregate, which is expected to support operations for between three and five years. Details of the proposed operation have been provided to both Garfield County and the Colorado Division of Reclamation, Mining, and Safety (DRMS). The final planning for the project is still being developed with a land use development permit currently in review with Garfield County and a mining plan in review with DRMS. However, under no foreseeable circumstances would the operating area of the mine be extended into areas that have been mapped as wetlands. To determine regulatory authority over the proposed project, a delineation of wetlands and Waters of the US was conducted in accordance with the USACE 1987 Wetland Delineation Manual and the Arid West regional supplement. The site assessment included the entire parcel, although the focus Wetland Delineation Report Rifle Gravel Pit #1 February 2022 6 and the Comprehensive Delineation was on the portion of the site where development could potentially occur, and did not extend to the small “panhandle” on the northeast corner of the property. There are a total of 1.13 acres of non-wetland open water within the parcel (all associated with the artificially-excavated tailwater ditch), and a total of 18.28 acres of wetlands were delineated within the parcel. Irrigation waters from the ditch clearly provide some portion of the hydrology supporting the wetland complex. However, shallow groundwater associated with the Colorado River floodplain and water table are also assumed to be partially supporting wetland conditions. No attempt has been made to conclusively determine the extent of agricultural water support of the wetlands on the parcel, and no discussion of jurisdictional status is included in this report. This request is solely for a Boundary Confirmation of the mapped wetland areas, irrespective of potential jurisdictional status, and IHC Scott intends to avoid direct impacts to all wetlands regardless of jurisdictional status. Note that IHC Scott’s proposed development plan does involve impacts to the tailwater ditch (see Appendix A). These impacts would qualify as exempt activities under the Clean Water Act (CWA) Section 404(f)(1)(C) exemptions for the construction and maintenance of jurisdictional ditches. This contention is based on the following points: · The tailwater ditch is a “constructed or excavated channel used to convey water,” in this case one that conveys irrigation waters from their place of use to a discharge point into natural waters (the Colorado River). It therefore qualifies as an irrigation ditch under 85 FR 22250. · The purpose of IHC Scott’s diversion of the ditch waters into their excavated pond is to ensure the continued function of the ditch, which is the discharge of irrigation return flows to receiving waters. There are no downstream users or water right holders on the ditch; IHC Scott’s obligation as owner of the ditch is to ensure that the irrigation return flows reach the Colorado River. · IHC Scott’s revision of the ditch design would not include any areas of the ditch that currently host abutting or adjacent wetlands. This is in recognition of the fact that the wetlands may also be supported by natural hydrology. IHC Scott intends to alter only that portion of the ditch that is clearly an artificial channel excavated in uplands with no adjacent wetlands (see Appendix A). No direct impacts to any wetlands would occur as a result of the ditch work. · Part 1 of the recapture provision (CWA Section 404(f)(2)) would not apply to this work because there is no intention to convert any area of WoUS to a use to which it was not previously subject. There are no impacts to wetlands, no conversions of wetlands to new uses, and no degree of piping the ditch. In fact, the express purpose of the ditch alterations is to avoid impacts to the wetlands while continuing to fulfill the requirement to discharge the irrigation return flows. · In addition, Part 2 of the recapture provision (CWA Section 404(f)(2)) would not apply to this work because there would be no impairment to the flow or circulation of WoUS. The natural hydrology supporting the wetlands on the western portion of the property would not be altered, since the proposed mine would not alter the current conditions under which shallow groundwater passes under the site, through permeable gravels, and proceeds to Wetland Delineation Report Rifle Gravel Pit #1 February 2022 7 downstream waters. In addition, the existing agricultural waters that may be partially supporting the wetlands would continue to be available, given their discharge into the pond and incorporation into the shallow groundwater on the site. This discussion tiers to and relies upon the definitions and procedures jointly laid out by the USACE and the U.S. Environmental Protection Agency concerning the applicability of ditch exemptions (EPA 2020). This report has been prepared in accordance with regulatory guidance for submittal to the USACE to request a wetland boundary confirmation. No nationwide permit is requested at this time. This report has been submitted to assist in planning and communication between IHC Scott and the regulatory agencies, primarily the USACE, but also Garfield County. Wetland Delineation Report Rifle Gravel Pit #1 February 2022 8 3. PROJECT AREA DESCRIPTION The primary vegetation type across the Project area is historically irrigated pasturelands. Historic aerial photography shows the parcel had been flood irrigated for many years. With changes in utilization of the agricultural land, the extent and amount of irrigation has expanded and contracted over the past several decades. There are irrigation ditches and irrigation flows on the parcel that at one time were directed toward supporting pasture vegetation, and they have not been consistently used in the last two seasons since IHC Scott acquired the property. There are also discharges from the irrigation tailwater ditch which terminates on the property, where it discharges agricultural water to flow in a naturalized channel to an eventual confluence with the Colorado River. These surface inputs are contributing to the extent of wetlands on the property. However, the surface of the parcel is also elevationally very close to the Colorado River, and it is assumed that elevated ground waters are contributing to the support of wetlands as well. The pasturelands are dominated by agricultural graminoids and ruderal weeds. There is minimal evidence of recent seeding or other direct management, and some representative dominant species include common timothy (Phleum pratense – FACU), inland saltgrass (Distichlis spicata – FAC), alkali sacaton (Sporobolus airoides – FAC), white goosefoot (Chenopodium album - FACU), and chicory (Cichorium intybus – FACU). Russian olive (Elaeagnus angustifolia – FAC) is a dominant component in portions of the parcel, generally in transition areas between pastures and wetlands. The wetland communities grade generally from east to west, from occasionally saturated areas dominated by arctic rush (Juncus balticus – FACW), timothy, and saltgrass, through seasonally saturated wetland meadows dominated by sedges (Carex spp.) and arrowgrass (Triglochin maritima – OBL), and into perennially flooded marshes dominated by obligate emergent species such as bulrush (Schoenoplectus spp.) and cattail (Typha latifolia). Using data from the nearest weather station (Rifle), recorded temperatures for the reporting period (1910 to 2009) range from an average low of 9 degree Fahrenheit (˚F) in January to an average high of 90˚F in July. Average annual precipitation of 11.6 inches consists primarily of winter snows, and summertime rain precipitation events (Western Regional Climate Center [WRCC] 2021). Typical conditions in the upland part of the property. Bulrush and Juncus wetlands on the property. Wetland Delineation Report Rifle Gravel Pit #1 February 2022 9 Wetland Delineation Report Rifle Gravel Pit #1 February 2022 10 Figure 1: Vicinity Map Wetland Delineation Report Rifle Gravel Pit #1 February 2022 11 Figure 2: Topographic Map Wetland Delineation Report Rifle Gravel Pit #1 February 2022 12 4. WETLAND & WATERS DELINEATION IHC Scott contracted with SGM for the delineation of all potential wetlands and WoUS on the parcel to assist with project planning and development. As summarized in Section 1 and described in more detail below, a comprehensive delineation has been performed at the request of the USACE, incorporating 18 transects spaced at 100-ft intervals, resulting in collection of 188 WDDF data points. All delineations and assessments were completed by SGM’s Senior Ecologist Alex Nees, a certified wetland delineator, with the assistance of SGM’s Eric Petterson, also a certified wetland delineator Wetland Delineation Report Rifle Gravel Pit #1 February 2022 13 NWI. Due to the subtle and variable conditions of surface water conditions, all wetlands were categorized simply as PEM wetland type. In addition to the PEM wetlands, one other WoUS type was delineated on the parcel: · R3UBHx (Riverine, Upper Perennial, Unconsolidated Bottom, Permanently Flooded, Excavated) o This feature is the open water found in the tailwater ditch. The ditch was mapped in NWI as PEM1F, but it appears that ongoing maintenance dredging has continually removed emergent vegetation in the majority of the channel and preserved open- water conditions. See Figure 3: National Wetland Indicator Map, and Figure 6: Delineated Wetlands to compare NWI mapping to the field delineation. SSURGO Soil Review SGM reviewed the Soil Survey Geographic Database (SSURGO, Figure 4) which indicated the presence of four soil types within the parcel. The mapped soil unit boundaries were found to be roughly accurate, although soil texture did vary widely, likely as a result of the combination of past agricultural treatments and historic flood deposition/scouring events. · Halaquepts, nearly level: This soil type dominates the western half of the property. It is a saline soil type that experiences both a seasonal high water table and a period in which evapotranspiration brings salts to the soil surface (USDA 2015). It is classed as moderately to strongly saline, and is a hydric soil type. The halaquepts on the site are likely derived from the local loams and sandy loams, but have been modified by the high water table and evapotranspirative demand. The reported alkalinity of this soil is Moderately to Strongly Alkaline, qualifying it as a problematic hydric soil per the Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Arid West (USACE 2010). · Wann sandy loam, 1-3% slopes: This soil type surrounds the eastern portion of the tailwater ditch on the property. It is a poorly-drained alluvial deposit that is non-saline to slightly saline. It is similar to the halaquepts, but does not experience the seasonal high water table and evapotranspiration necessary to concentrate salts at the soil surface. It is a hydric soil type. · Kim loam, 3-6% slopes: This soil type is limited to the northeast corner of the property. It is also an alluvial deposit, but is well drained and does not have a high water table. Salinity is negligible and it is not a hydric soil type. · Olney loam, 1-3% slopes: This soil type is limited to the southeast corner of the property. It is very similar to Kim loam, being an alluvial deposit that is well drained and does not have a high water table. It may be very slightly saline. It is not a hydric soil type. In summary, the soil review indicated that the project site is entirely dominated by loam deposits overlying the alluvial gravels. The low-lying areas on the west end of the property are moderately to strongly saline due to seasonal saturation/inundation and a strong evapotranspirative pump that brings salts to the surface. Other portions of the site that do not experience Wetland Delineation Report Rifle Gravel Pit #1 February 2022 14 saturation/inundation are not notably saline. These mapping results were generally confirmed by field investigations, and also correspond to the findings of some investigatory sub-surface drilling logs (Appendix E). Wetland Delineation Report Rifle Gravel Pit #1 February 2022 15 b. The pH of the soil was measured at depths of 2-inches, 6-inches, and occasionally 12-inches if more conclusive results were needed. Measurements were taken using a digital pH meter with a resolution of 0.1 pH and automatic temperature calibration (Bluelab Soil pH Pen). The pen was calibrated using reference pH solutions on a weekly basis during the delineation effort, and was stored in pH-neutral storage solution when not in use. pH measurements are recorded on all WDDFs. c. Data points where the soil returned a pH value of 7.9 or higher qualified as “Moderately to Very Strongly Alkaline Soils” per the Arid West Manual. In these settings hydric indicators may not form because the alkalinity reduces the ability of iron and manganese to enter solution and form recognizable indicators. At these data points, the “Other” indicator under Problematic Hydric Soils was marked, and soils were not further evaluated, as they were assumed to be Hydric. d. The procedure for Problematic Hydric Soils determination was followed (USACE 2010). Data points where soil pH was 7.9 or greater were considered to be wetlands if hydrophytic vegetation and wetland hydrology indicators were present, regardless of the observed presence of hydric soil indicators. e. For data points with soil pH of less than 7.9, the standard wetland delineation protocol was followed. The soil column excavated by the auger was evaluated for the presence of hydric indicators. The plant species at the data point were recorded and used to determine whether hydrophytic vegetation was present, and hydrology was evaluated using direct observation of the auger hole, in combination with evaluation of the primary and secondary hydrology indicators. f. In summary, data points that indicated the presence of hydrophytic vegetation, hydric soils OR a pH of 7.9 or greater, and wetland hydrology, were coded as wetlands. 5. Based on the WDDF findings, the data points were coded as Wetland or Non-wetland in the GIS. The delineation team then mapped the wetland boundaries displayed in Figure 6 in the field using a sub-meter accuracy GPS, accounting for the data point findings and the totality of observations from the site. This mapping is presented in Figure 6, and represents the wetland boundaries for which SGM is seeking a Boundary Confirmation, based on compliance with the Comprehensive Determination method as modified per the guidance in the Arid West Regional Supplement. Of note, alpha, alpha-dipyridyl dye was applied to saturated soils on a test basis, on numerous occasions. In no case was the dye found to be a reliable indicator of the presence of reduced iron in the soil, either in high-pH situations or in cases of obvious reducing conditions. Wetland Delineation Report Rifle Gravel Pit #1 February 2022 16 Figure 3: National Wetlands Inventory Wetland Delineation Report Rifle Gravel Pit #1 February 2022 17 Figure 4: SSURGO Soil Type Wetland Delineation Report Rifle Gravel Pit #1 February 2022 18 Wetland Delineation Report Rifle Gravel Pit #1 February 2022 19 were delineated within the parcel, all of which are considered potentially jurisdictional and would be avoided by IHC Scott’s development plan (Figure 6, and Appendix A). 1.13 acres of non-wetland WoUS associated with the open water of the tailwater ditch were also delineated. The tailwater ditch is artificially excavated and carries irrigation waters from their point of entry on the eastern edge of the parcel towards the discharge point along the western edge of the parcel. However the ditch is set within the floodplain of the Colorado River and has a discharge to the Colorado River. Based on these factors the tailwater ditch has a nexus to a WoUS and Traditionally Navigable Waterway (TNW), and is considered to be potentially jurisdictional. A wetland delineation map (Figure 6) depicts the Investigation Area (i.e., the parcel boundaries), the wetland boundaries, and the location of all aquatic resources noted during the survey. 188 WDDF points were established during the survey to clarify and support the wetland boundary delineations, and the data forms are included in Appendix B. Tailwater Ditch (R3UBHx) The tailwater ditch in this area supports and abuts a wetland fringe as shown on Figure 6; the wetland fringe generally occurs in the western portions of the property. Where no abutting wetlands are mapped, ongoing dredging/maintenance activities, and steep banks along the irrigation ditch have prevented the establishment of wetland vegetation in the ditch. The banks are clearly defined by the artificial excavation line, transitioning directly from open water to mesic pasture conditions. Therefore, the ordinary high water mark (OHWM) was delineated as the boundary for this non-wetland WoUS feature. Emergent Wetlands (PEM) Areas of emergent wetlands (PEM) within the Investigation Area are associated with irrigation waters and with low-lying areas that may have natural subsurface hydrology (Figure 6). Wetland Delineation Report Rifle Gravel Pit #1 February 2022 20 Vegetation: The wetland communities grade generally from east to west, from mesic and occasionally saturated areas dominated by arctic rush (Juncus balticus – FACW), common timothy (Phleum pratense – FACU), and inland saltgrass (Distichlis spicata – FAC), through seasonally saturated wetland meadows dominated by a number of sedges (Carex spp.) and arrowgrass (Triglochin maritima – OBL). Western portions of the parcel are perennially flooded marshes dominated by obligate emergents such as bulrush (Schoenoplectus spp.) and cattail (Typha latifolia). Soils: The soil conditions have been described in detail in Section 4.1.2 and Section 4.2. In general, the soil pits associated with each data point generally corresponded to the SSURGO mapping. The majority of the mapped wetland areas are within the halaquept zone or adjacent to it. However, the soil pH was not consistently 7.9 or greater within the halaquept zone, and a large portion of the data point determinations rested on typical hydric soil indicator presence. In general, soils pits inside the wetland boundary showed evidence of anaerobic, redox conditions, most commonly with a depleted soil matrix consistent with the Depleted Matrix indicator (Indicator F3). Soil pits outside the wetland boundary generally lacked hydric soil indicators within the upper 12 inches of soil, although redox traces were commonly observed at greater depths. The observed conditions strongly suggest that the mapped wetlands on the property are saturated or have standing water for a significant portion of the growing season. Soils outside the wetland boundaries have seasonally shallow groundwater, but not for a sufficient period to generate redox conditions within the upper 12 inches of the soil. Hydrology: At the boundary of the wetland areas, hydrology indicators were generally secondary indicators only, including visible saturation on imagery, dry-season water table, and a positive FAC- Neutral Test. Hydrology was obvious in areas with soil saturation and standing water. During the course of several visits to the site, surface water and saturation was observed to be relatively stable and constant in extent (aside from where trespass irrigation waters discharged from the property to the north were halted when the ditches were maintained). Some areas that were mapped as wetlands displayed cracked soils and salt crusts consistent with depressional ponding and Indicators B6 and B11. Wetland Delineation Report Rifle Gravel Pit #1 February 2022 21 Table 1. Summary of Waters of the U.S. and Wetlands in Investigation Area Name Jurisdiction Flow Frequency Receiving Water Proximity Size (acres) Last Chance Tailwater Ditch WoUS – R3UBHx Potentially Jurisdictional Perennial Colorado River Tributary 1.13 TOTAL NON-WETLAND WoUS 1.13 Wetland A PEM Potentially Jurisdictional Semipermanent Colorado River Adjacent 2.05 Wetland B PEM Potentially Jurisdictional Seasonal Colorado River Adjacent 0.14 Wetland C PEM Potentially Jurisdictional Seasonal Colorado River Adjacent 0.02 Wetland D PEM Potentially Jurisdictional Seasonal to Semipermanent Colorado River Adjacent 6.00 Wetland E PEM Potentially Jurisdictional Semipermanent Colorado River Adjacent 9.86 Wetland F PEM Potentially Jurisdictional Ephemeral Colorado River Adjacent 0.21 TOTAL WETLANDS 18.28 Wetland Delineation Report Rifle Gravel Pit #1 February 2022 22 Figure 5: Comprehensive Delineation Study Design Wetland Delineation Report Rifle Gravel Pit #1 February 2022 23 Figure 6: Delineated Aquatic Resources Wetland Delineation Report Rifle Gravel Pit #1 February 2022 24 5. FEDERALLY LISTED THREATENED OR ENDANGERED SPECIES At this time, IHC Scott is only requesting a Boundary Confirmation, with the intention of completely avoiding impacts to the wetlands on the property. Based on this avoidance directive from IHC Scott, SGM has not identified any other federal nexus for the project at this time. A brief discussion of federally listed species follows here, to inform the USACE and the planning process. Seven federally listed species and one Candidate species were evaluated for their occurrence on or adjacent to the parcel, per the USFWS Threatened and Endangered species list provided by the IPaC database (USFWS 2022). Based on this analysis, the USFWS identified the Mexican spotted owl (Strix occidentalis lucida), yellow-billed cuckoo (Coccyzus americanus), bonytail chub (Gila elegans), Colorado pikeminnow (Ptychocheilus lucius), humpback chub (Gila cypha), razorback sucker (Xyrauchen texanus), monarch butterfly (Danaus plexippus), and Ute Ladies’-tresses (Spiranthes diluvialis) as potentially occurring in the area. Mexican Spotted Owl – Threatened. This species occurs in closed canopy conifer forests and deeply incised canyons in desert habitats. The project area is outside of the range of this species, and there are no canyons or coniferous habitats in the project area. There is no likelihood that Mexican spotted owls forage in the project area, given a lack of suitable habitat of any type. This project would have no effect on the Mexican spotted owl or their habitats. Yellow-billed Cuckoo - Threatened. This species occurs in dense riparian habitats with cottonwood (Populus deltoides) overstories with dense understory shrubs near rivers. The project area occurs at the edges of the general range of yellow-billed cuckoo but is located outside any mature riparian woodland habitats. The site is dominated by Russian olive and pasture conditions, and is heavily grazed with minimal shrub cover. No mature riparian woodland/shrubland habitat suitable for the species occurs on the parcel. There are no known occupied habitats in the near vicinity and no records of cuckoo occurring in the greater area; it is highly unlikely that cuckoos forage in the project area, given a lack of suitable riparian habitats. This project would have no effect on the cuckoo or their habitats. Colorado River Endangered Fish - Endangered. The USFWS identified the bonytail chub, Colorado pikeminnow, humpback chub and the razorback sucker as potentially occurring or being affected from activities on the parcel. These species occur in lower elevation, larger rivers associated with the Colorado River. The Colorado pikeminnow and razorback sucker have mapped Critical Habitat extending up the Colorado River to the Highway 13 bridge in Rifle. Potential activities on the parcel would not occur in the Colorado River and would not discharge sediments into the river; the parcel is approximately five river miles upstream from designated Critical Habitat. The project would result in minor water depletions as a result of increased evaporative losses from the surface of the dredged pond as compared to current conditions. IHC Scott is required to develop a Supplementary Water Supply Plan (SWSP), which would replace those losses with releases to the Colorado River from other water rights held by IHC Scott. As a result of the SWSP, there would be no indirect loss in in-stream flows as a result of the project. The project would also be required to implement a stormwater management plan, in compliance with DRMS regulations Wetland Delineation Report Rifle Gravel Pit #1 February 2022 25 as well as for Garfield County LUC standards. This would mitigate the risk of significant sedimentation impacts to these fish. Due to the requirement to provide supplementary water to offset evaporative losses, as well as implementation of stormwater controls, it is not anticipated that the project would result in any measurable or meaningful impacts to occupied habitats downstream or would measurably or meaningfully impact the listed fish. Given these factors, activities on the parcel would have no effect for the listed Colorado River endangered fish species and their Critical Habitats. Monarch butterfly – Candidate. Candidate species are not afforded full protection under the ESA; however, the USFWS encourages their consideration in environmental planning, and the USFWS regulatory guidance indicates that Candidate species should be treated similarly to Proposed Species with regard to inter-agency consultation requirements. Informal consultation is requested when a provisional “is likely to jeopardize” determination is reached for a Candidate species (USFWS 1998). Monarch butterfly adults feed (gather nectar) from a variety of flowering plant species. However, the monarch butterfly only lays eggs and larvae only feed on milkweeds (Asclepias spp.). The western population overwinters in various coastal sites in central and southern California, and central populations overwinter in Mexico. Monarchs have multiple generations during their migrations; the second, third and fourth generations return to their northern locations in the United States and Canada in the spring. The project area contains migratory and overwintering habitat for the monarch butterfly. Showy milkweed (Asclepias speciosa) is an abundant component of the vegetation in the transitional zones along the boundaries of the wetland areas. Adult butterflies and several monarch caterpillars were observed feeding on milkweeds at the western edge of the property. Western Colorado is not part of a major monarch migration corridor, but the site is being used by migrating adults and as a potential overwintering site for the dispersed population in the area. Proposed development would mostly occur outside the mesic/wetland meadows where the majority of milkweed is located, therefore direct impacts to host plants and habitats would be mostly avoided. The project would result in the complete loss of vegetation from approximately 20 acres of the property, which would result in potential direct impacts to chrysalis and caterpillars and reduce the foraging vegetation available to adult butterflies. This may result in minor, localized impacts to migrating monarch butterflies, and may reduce the attractiveness of the site as an egg- laying site. Development of the parcel is not likely to jeopardize this Candidate species, as the project may affect individuals but is not expected to alter the species’ overall range and life history patterns. USFWS consultation is not required by ESA for Candidate species where an action is not likely to jeopardize the species’ existence. Ute Ladies’-Tresses - Threatened. The project area occurs outside the known range of the Ute ladies’-tresses orchid, and is a significant distance from the nearest known populations in the Roaring Fork Valley. The parcel does contain wet meadow conditions that are potentially suitable habitat for the species, although similar habitats in the Colorado River valley have been searched Wetland Delineation Report Rifle Gravel Pit #1 February 2022 26 repeatedly and no orchids have ever been located. The potential habitats on the parcel have been incidentally evaluated by a trained and experienced orchid surveyor in the course of wetland assessments, and no orchids have been located. However, no systematic survey meeting USFWS standards has been undertaken on the parcel at this time. Activities on the parcel are not expected to directly impact effective habitats since the wetland areas would be avoided, and as previously discussed the project would not substantially change the existing hydrology that supports these wetlands. Given the location outside of the known range, and the avoidance of impacts to potentially-suitable habitat, activities on the parcel would have no effect on the Ute ladies’-tresses orchid. Wetland Delineation Report Rifle Gravel Pit #1 February 2022 27 6. REFERENCES Colorado Parks and Wildlife (CPW). 2020. Recommended Buffer Zones and Seasonal Restrictions for Colorado Raptors (2020). Available at: https://cpw.state.co.us/Documents/WildlifeSpecies/LivingWithWildlife/Raptor-Buffer- Guidelines.pdf Environmental Protection Agency (EPA). 2020. Joint Memorandum to the Field between the U.S. Department of the Army, Corps of Engineers and the U.S. Environmental Protection Agency concerning exempt construction or maintenance of irrigation ditches and exempt maintenance of drainage ditches under Section 404 of the Clean Water Act. Available at: https://www.epa.gov/sites/default/files/2020- 07/documents/final_ditch_exemption_memo_july_2020_with_epa.pdf Lichvar, R.W., D.L. Banks, W.N. Kirchner, and N.C. Melvin. 2016. The National Wetland Plant List: 2016 wetland ratings. Phytoneuron 2016-30: 1-17. Published 28 April 2016. ISSN 2153 733X Natural Resource Conservation Service. 2017. SSUGO Database. National Resource Conservation Service (NRCS). 2021. Web Soil Survey. Available at: https://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/survey/?cid=nrcs142p2_053627 United States Army Corps of Engineers (USACE), Environmental Laboratory. 1987. Corps of Engineers Wetland Delineation Manual. Wetlands Research Program Technical Report Y-87-1. USACE. 2008. Environmental Laboratory, Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Arid West Region (V.2, ERDC/EL TR-08-28). US Army Engineer Research and Development Center. Vicksburg, MS. USACE. 2005. Regulatory Guidance Letter No. 05-05. Ordinary High Water Mark Identification. December 7, 2005. United States Department of Agriculture (USDA), Soil Survey Staff. 2015. Illustrated guide to soil taxonomy, version 2. U.S. Department of Agriculture, Natural Resources Conservation Service, National Soil Survey Center, Lincoln, Nebraska. USDA. 2021. U.S. Drought Monitor, July 20, 2021. Available at: https://droughtmonitor.unl.edu/Maps/MapArchive.aspx. Accessed August 2021. U.S. Fish and Wildlife Service (USFWS). 1998. Endangered Species Consultation Handbook: procedures for conducting consultation and conference activities under Section 7 of the Endangered Species Act. Washington, D.C. Published March 1998. United States Fish and Wildlife Service (USFWS). 2022. Information for Planning and Consultation (IPaC). Available at: https://ecos.fws.gov/ipac/. Accessed January 2022. Western Regional Climate Center. 2019. Regional Climate Summaries. Available at: http://www.wrcc.dri.edu/. Accessed August 2021. IHC Scott – Rifle Gravel Pit #1 May 2022 Garfield County Special Use Permit Application Appendix F Appendix F – Grading and Drainage & SPCC IHC SCOTT RIFLE PIT #1 GRADING AND DRAINAGE REPORT RIFLE PIT #1 IHC SCOTT (SCOTT CONTRACTING INC.) MAY 2022 Prepared by 118 West Sixth Street, Suite 200 Glenwood Springs, CO 81601 970.945.1004 970.945.5948 fax IHC Scott – Rifle Gravel Pit #1 Grading and Drainage Report May 2022 i TABLE OF CONTENTS 1.0 Project Description 1 2.0 Site Map 1 3.0 Drainage Structures 1 3.1 Locations of Existing Drainage Features 1 3.2 Existing Drainage Features 4 Wetlands 4 Geology 4 Drainage and Stormwater Conveyances 4 Irrigation Infrastructure 4 3.3 Locations of Proposed Drainage Features 10 3.4 Preliminary Engineering Design and Construction Features 10 Floodplain Modeling and Site Drainage 10 Access Road and I-70 N Frontage Road Drainage 10 4.0 Topography 13 5.0 Grading and Drainage Plan 13 6.0 Soil Stockpile and Snow Storage Areas 13 7.0 Equipment Storage Areas 13 8.0 Temporary Roads 14 9.0 Areas of Steep Slope 14 10.0 Construction Schedule 14 11.0 Mining Plan 15 11.1 Site Development and Grading (Phase 1) 15 Access work 15 Surface preparation 16 Facility Construction 16 Water Handling and Dewatering 18 Stormwater Management 18 Irrigation Flow Management 18 Wetland Protection 18 11.2 Mining Preparation (Phase 2) 18 Water Handling 19 Schedule of Operations 19 Explosives 19 IHC Scott – Rifle Gravel Pit #1 Grading and Drainage Report May 2022 ii 11.3 Mining Extraction (Phase 3) 19 Size of Area Worked at 30% 19 Size of Area Worked at 60% 19 Size of Area Worked at 100% 19 Mining Methods and Earthmoving 19 Water Handling 20 11.4 Reclamation (Phase 4) 20 12.0 Permanent Stabilization and Post-Mined Conditions (Reclamation, Revegetation and Soil Plan) 21 12.1 Description and Types of Reclamation, Revegetation, and Soil Plan 21 12.2 Post-Mining Land Use 21 13.0 Implementation of the Reclamation Plan 23 13.1 Topsoil Segregation, Preservation, and Replacement 23 13.2 Final Grading 23 13.3 Seeding 23 Temporary Seed Mix 23 Long-Term/Permanent Seed Mix 23 14.0 Erosion Control Measures 25 15.0 Estimated Cost 25 16.0 Calculations 28 16.1 Floodplain Analyses 28 17.0 Neighboring Areas 28 18.0 Stormwater Management 29 18.1 Stormwater Management Plan (SWMP) 29 19.0 Reclamation, Revegetation, and Soil Plan 29 19.1 Weed Management Plan 29 19.2 Revegetation Security 30 20.0 Hydraulic Calculations 30 21.0 Maintenance Requirements 30 22.0 Spill Prevention Control and Countermeasures Plan (SPCC) 31 23.0 Signature Block 32 IHC Scott – Rifle Gravel Pit #1 Grading and Drainage Report May 2022 iii LIST OF TABLES Table 1. Estimated Areas of Disturbance to Support Gravel Mining for Rifle Pit #1 1 Table 2. Estimated Timetable for Phases 1-4 15 Table 3. Reclamation Costs 25 LIST OF FIGURES Figure 1. Site Map including Existing Water Features within 10 Feet of the Rifle Pit #1 Property Boundary 2 Figure 2. Existing Conditions Site Map 3 Figure 3. Location of Wetlands on the Rifle Pit #1 Property 5 Figure 4. Phase 3 30% Mining Progression and Proximity of Wetlands from the Toe of the Perimeter Berm (minimum 25-foot setback) 6 Figure 5. Phase 3 60% Mining Progression and Proximity of Wetlands from the Toe of the Perimeter Berm (minimum 25-foot setback) 7 Figure 6. 100% Mining Progression and Proximity of Wetlands from the Toe of the Perimeter Berm (minimum 25-foot setback) 8 Figure 7. Typical Rifle Pit #1 Strata 9 Figure 8. Existing I-70 N Frontage Road Drainage Features and Proposed Access Road and Drainage Improvements 11 Figure 9. Erosion Control Plan 12 Figure 10. Typical Gravel Processing Layout 17 Figure 11. Seeding and Reclamation Details 22 Figure 12. Reclamation Plan 24 Figure 13. Proposed Best Management Practices for Sediment and Erosion Control 26 Figure 14. Best Management Practices for SPCC 27 1 1.0 Project Description This Grading and Drainage Plan describes the information required in Section 4-203.E of the Garfield County Land Use and Development Code (LUDC) for the IHC Scott, Inc. (dba Scott Contracting, Inc.) (Scott) Rifle Pit #1 Major Impact Land Use Permit application. The proposed gravel mining operation would occur in four phases as follows: • Site development and grading (Phase 1) • Mining preparation (Phase 2) • Mining extraction (limited to non-wetland areas) (Phase 3) • Reclamation (Phase 4) The mining extraction areas associated with Phase 3 has approximately 300,000 cubic yards (CY) of minable material (including sand, gravels, <6-inch diameter material, and other pit run) that will be extracted over three to five years. The sale of these materials is anticipated to provide various construction materials for ongoing and anticipated future private development and projects within and for Garfield County and the Colorado Department of Transportation (CDOT). The estimated area of disturbance during Phase 3 and 4 is 19.00 acres (which includes the main pit, processing/sales areas, and final reclamation areas). Please note that the total acreage encompassed by the Project is 19.63 acres; this discrepancy is because a small 0.63-acre area within the development boundaries will be left undisturbed, as it contains marginal wet meadow characteristics. The total estimated planned excavation area is provided in Table 1 and amounts to 12.39 acres. Appendix C of the Land Use Permit includes the Drawings depicting additional details and information associated with this proposed mining activity. Table 1. Estimated Areas of Disturbance to Support Gravel Mining for Rifle Pit #1 Mining Operation Components Area (acres) Perimeter Berm and Boundary Features 3.90 Excavation Area (Minecut) 12.39 Processing and Sales Area 1.93 Ancillary Surface Working Areas 0.78 Total 19.00 2.0 Site Map Figure 1 depicts the existing site conditions and structures, waterbodies and hydrologic features within 10 feet of the Rifle Pit #1 property boundary. This figure also depicts the Colorado River alluvial floodplain path relative to the Rifle Pit #1 property (Property). Figure 2 provides the existing conditions survey information for the Property. 3.0 Drainage Structures 3.1 Locations of Existing Drainage Features Figure 1 depicts the locations of existing and proposed drainage structures affecting site drainage on the site and within 10 feet adjacent to the site boundary. 2 Figure 1. Site Map including Existing Water Features within 10 Feet of the Rifle Pit #1 Property Boundary 3 Figure 2. Existing Conditions Site Map 4 3.2 Existing Drainage Features Wetlands A Comprehensive Delineation was completed for the entire property, at the request of the U.S. Army Corps of Engineers (USACE) (Figure 3). Scott has submitted this delineation and Aquatic Resource Report to the USACE and requested a Boundary Confirmation (a formal written acceptance of the mapped wetland boundaries). Note that no attempt has been made to distinguish wetlands supported by agricultural water from naturally occurring wetlands: Scott will avoid impacts to any areas with wetland conditions regardless of the supporting hydrology. The project area has been designed to maintain a minimum 25-foot buffer between any wetland areas and the outer boundary of surface disturbance. The wetland boundaries will be flagged in the field during Phase 1 to ensure that no unintentional impacts occur to the wetlands during surface preparation and berm construction. Once the perimeter berms are constructed, they will serve as a physical barrier separating the mining activity from the adjacent wetland areas. Between the 25-foot buffer and the berm width, there will be approximately 50-foot separation between mine activity and the boundary of wetlands on the parcel. Figures 4, 5, and 6 depict the 30%, 60%, and 100% mining conditions (during Phase 3). Geology The Property is underlain by river gravels which are saturated and in direct contact with the water table. The surface soil is generally an alluvial silty clay loam, with areas of heavy clay. Boring logs and direct observation suggest that many areas of wetland vegetation are underlain by a clay aquitard layer at a depth of approximately 3 feet. The boring holes indicate the overburden thickness can vary from 1 to 7 feet. Figure 7 depicts the typical strata for the Rifle Pit #1 property. Drainage and Stormwater Conveyances There are no street gutters nor storm sewers on nor adjacent to the site. There is an existing concrete valley pan that intercepts drainage from the east within the roadway ditch that conveys it to a 30” culvert and carries it under the existing gravel frontage road to the south. There is also a roadway ditch that intercepts drainage from the I-70 N Frontage Road and conveys it to the west (Figure 2). Irrigation Infrastructure In general, surface water reaches the property exclusively via artificially excavated channels off the Last Chance Ditch. This includes the large lateral/tailwater ditch that bisects the property from east to west, and several smaller ditches that discharge underneath the interstate and onto the southern boundary of the property (Figure 1). 5 Figure 3. Location of Wetlands on the Rifle Pit #1 Property 6 Figure 4. Phase 3 30% Mining Progression and Proximity of Wetlands from the Toe of the Perimeter Berm (minimum 25-foot setback) 7 Figure 5. Phase 3 60% Mining Progression and Proximity of Wetlands from the Toe of the Perimeter Berm (minimum 25-foot setback) 8 Figure 6. 100% Mining Progression and Proximity of Wetlands from the Toe of the Perimeter Berm (minimum 25-foot setback) 9 Figure 7. Typical Rifle Pit #1 Strata 10 SGM conducted two phone interviews to better understand the irrigation practices. SGM interviewed Joey Shideler, who is the president and ditch rider for the Rising Sun Ditch and one of the lessees of the Ranch. Joey Shideler and his brother Chris Shideler have been leasing the Ranch for approximately 15 years for cattle grazing. SGM also interviewed Jim Snyder, president of the Loesch & Crann Ditch Company (operates the Last Chance Ditch which is also known as the Loesch & Crann Ditch). During a July 17, 2019 site visit, SGM observed a concrete irrigation system on the property that is fed by two culverts under I-70. The two culverts lead to an open concrete irrigation lateral along the southern edge of the property with turnouts approximately every 100 feet to irrigate the field to the north of the lateral. This infrastructure is shown on Figure 2 and Figure 3. SGM did not follow these culverts to their headgates, but interviews with Mr. Shideler and Mr. Snyder both agree that these culverts are laterals currently diverting from the Last Chance Ditch, not the Rising Sun Ditch. Mr. Snyder understands that there is currently no infrastructure in place to deliver water to the property from the Rising Sun Ditch, though he understands that there was historically a lateral delivering water to the property from the Rising Sun Ditch (which crossed over the Last Chance Ditch, as the Rising Sun Ditch is located above the Last Chance Ditch). 3.3 Locations of Proposed Drainage Features The Frontage Road paving and access construction will maintain the existing drainage along the southern side of the property, adjacent to the frontage road (Figure 8). There are no additional proposed drainage features for this Project. The excavation of the property will result in the presence of a pond, approximately 12.56 acres. 3.4 Preliminary Engineering Design and Construction Features There were two primary preliminary engineering analyses conducted for purposes of the site development and controlling developed drainage conditions: 1) Floodplain and flood control and 2) the access road. Floodplain Modeling and Site Drainage HEC-RAS was used to model the 100-year floodplain for the existing and construction phases of the site, including the height of the perimeter berm. Figures 4, 5, and 6 depict the 30%, 60%, and 100% mining conditions (during Phase 3), including a typical section for the perimeter berm. The perimeter berm will be constructed as mining proceeds across the property, in stages, and serve to retain all stormwater and drainage on-site and any drainage from the access road will be intercepted by the roadway ditch. Access Road and I-70 N Frontage Road Drainage Drainage from the access road will be intercepted by the roadway ditch (Figure 8). 2-18” Corrugated Metal Piping (CMP) culverts will also be installed under the access road to maintain the flowline along the roadside ditch from east to west. 11 Figure 8. Existing I-70 N Frontage Road Drainage Features and Proposed Access Road and Drainage Improvements 12 Figure 9. Erosion Control Plan 13 4.0 Topography Figure 1 depicts the existing topography for the site. Elevations at the site range from 5,530 feet at the southeastern portion of the property to 5,374 feet at the western portion of the site. The existing drainage flows east to west across the length of the property and is generally conveyed to the Colorado River. The slope across the site varies and is generally <5%. 5.0 Grading and Drainage Plan Topsoil and overburden will be stripped from the mining area; the overburden will be used to construct the required berms along the perimeter of the site, and the topsoil will be applied to the berms as a surface layer to support reclamation seeding. These berms will be placed at the inside edge of the proposed 25-foot setback from the property line. These berms will be roughly 5-feet in height and 25-feet wide at the bottom and will also help control noise and visual impacts during operation (see Figures 4, 5, and 6, specifically the berm details, for the mining progression). The existing topsoil and will be stripped and used for the required berms along the perimeter of the site. Note that the thickness of topsoil and overburden across the site vary. The boring holes indicate the overburden thickness can vary from 1 to 7 feet (Figure 7). These berms will serve many purposes but specific to drainage and erosion control they will prevent runoff of stormwater onto the site and protect the operations from the influence and flooding by the Colorado River. Additional erosion and sediment control BMPs will be installed per the Erosion Control Plan (Figure 9) and Stormwater Management Plan and Permit requirements. Surplus topsoil and overburden material remaining after construction of the berms will be stockpiled at the processing facility. Sufficient material will be retained for final reclamation purposes, with the remainder to be sold as topsoil and clean fill material, respectively. 6.0 Soil Stockpile and Snow Storage Areas Figures 4 and 5 depict probable stockpile locations, by percent of mining. The placement of snow storage areas will also be determined by the mining stage of mining activity and most likely on the site, away from the excavation activity, and outside the travel and access on and to the site. 7.0 Equipment Storage Areas Location of storage areas designated for equipment, fuel, lubricants, chemical, and waste storage with an explanation of spill containment structures are identified on Figure 4 and Figure 5. Attention to spill control and containment procedures will be part of the identification of these storage areas during operations. Scott has a Spill Prevention Control and Countermeasure (SPCC) Plan to cover the storage and transport of fuel and other liquids that are regulated by the Environmental Protection Agency (Appendix F of the Land Use Permit). 14 8.0 Temporary Roads There will be no temporary roads constructed for this project. 9.0 Areas of Steep Slope There are no existing areas at the site with greater than 20% slopes. The perimeter berms (depicted in Figures 4, 5, and 6) will be roughly 5-feet in height and 23-feet wide at the bottom built at 2H:1V slope. This berm will also mitigate noise produced during operation. These berms will serve many purposes but for specific to drainage and erosion control they will prevent runoff of stormwater and intercepted groundwater off site and protect the operations from the influence and flooding by the Colorado River. 10.0 Construction Schedule The proposed development would be a wet mining operation where the topsoil and mineral overburden would be removed and stockpiled for onsite use or sale as topsoil and clean fill respectively, and the underlying saturated alluvial gravels would be excavated in a saturated state. Excavation would be accomplished using a long-reach excavator located on the upper rim of the excavated pit. No dewatering nor groundwater pumping would occur with this proposed mining development, and the excavated pit would fill with groundwater to become a pond as mining progresses through the site. The proposed gravel mining operation would occur in four phases as follows: • Site development and grading (Phase 1) • Mining preparation (Phase 2) • Mining extraction (limited to non-wetland areas) (Phase 3) • Reclamation (Phase 4) The mining extraction areas associated with Phase 3 has approximately 300,000 cubic yards (CY) of minable material (including sand, gravels, <6-inch diameter material, and other pit run) that will be extracted over three to five years. The total estimated planned excavation area is provided in Table 1 and amounts to approximately 19.00 acres. Table 2 provides the anticipated construction schedule indicating the anticipated starting and completion time periods of the mining by phase/stage, estimated nature, depth and thickness of the deposit to be mined and type of overburden to be removed. 15 Table 2. Estimated Timetable for Phases 1-4 Phase/Stage Estimated Duration Estimated Depth Type of Overburden Phase 1 Site Development & Grading 1-2 months Approx. 0.5 feet to 1 foot Clay and silt; about 6” to 1-foot of topsoil, medium stiff, slightly moist, brown Phase 2 Mining Preparation 2-6 months N/A No additional overburden will be removed during this phase. Phase 3 Mining Extraction 3 - 5 years 17 – 21 feet Varies 30% 1 – 1.5 years 21 feet (gravel layer thickness) See Boring 4 Remove estimated 6” of clay and silt; gravel layer estimated at 1 foot to 22 feet below surface. 60% 1 – 1.5 years 21 feet (gravel layer thickness) See Boring 3. Remove estimated 5.5 feet to 6 feet of clay and silt overburden; gravel layer estimated at 7 feet to 27 feet below surface. 100% 1 – 1.5 years 21 feet (gravel layer thickness) See Boring 3. Remove estimated 5.5 feet to 6 feet of clay and silt overburden; gravel layer estimated at 7 feet to 27 feet below surface. Phase 4 (Final Reclamation) 6 months NA NA 11.0 Mining Plan Scott will prepare the site for mining, and then mine the affected portion of the property in four phases. Representative diagrams are included in Figure 4, Figure 5, and Figure 6. 11.1 Site Development and Grading (Phase 1) No mining will occur during Phase 1. This phase of the project will include minor site grading and vegetation removal on the 19.00 acres of proposed disturbance, and construction of the Operations Pad and site access/driveway apron. The mine will use conventional earth moving equipment including, but not limited to a bulldozer, track-hoe, and a 35-ton haul truck. Specific activities include the following. Access work A paved access apron will be constructed to access the project site from the CR 346 (Interstate-70 frontage road). CDOT has reviewed the plans and issued an access permit to allow for this construction (Appendix B, Land Use Permit). The tailwater channel bisects the property, isolating the northern portion of the proposed mining footprint from the road access on the parcel’s southern boundary. Scott will not disturb the tailwater channel in its existing location and will implement Best Management 16 Practices (BMPs) to prevent mining operations from discharging into or comingling with these waters. Scott will utilize the single existing crossing of the channel to access the northern portion of the property. The existing crossing includes an adequate culvert, and maintenance will be limited to the replacement of eroded overburden, to restore the crossing to an adequate 12-foot-wide travel surface. Surface preparation Topsoil and overburden will be stripped from the mining area; the overburden will be used to construct the required berms along the perimeter of the site, and the topsoil will be applied to the berms as a surface layer to support reclamation seeding. These berms will be placed at the inside edge of the proposed 25-foot setback from the property line. These berms will be roughly 5-feet in height and 25-feet wide at the bottom and will also help control noise and visual impacts during operation (see Figures 4, 5, and 6, specifically the berm details). The existing topsoil and will be stripped and used for the required berms along the perimeter of the site. Note that the thickness of topsoil and overburden across the site vary. The boring holes indicate the overburden thickness can vary from 1 to 7 feet. Figure 7 depicts the typical stratum at the property. These berms will serve many purposes but specific to drainage and erosion control they will prevent runoff of stormwater onto the site and protect the operations from the influence and flooding by the Colorado River. Additional erosion and sediment control BMPs will be installed per the Erosion Control Plan (Figure 9) and Stormwater Management Plan and Permit requirements. Surplus topsoil and overburden material remaining after construction of the berms will be stockpiled at the processing facility. Sufficient material will be retained for final reclamation purposes, with the remainder to be sold as topsoil and clean fill material, respectively. Facility Construction A processing and sales facility (scale house) will be constructed at the entrance to the project site. This will include the material stockpile locations, loading chute and processor, the scale house, vehicle parking, and the minimal facilities needed for onsite staff (vault- and-haul toilet system, water tank, work trailer) (Figure 10 depicts a typical layout). 17 Figure 10. Typical Gravel Processing Layout 18 Water Handling and Dewatering Stormwater Management Scott will apply for coverage under Permit No. COR400000, CDPS General Permit (for) Stormwater Discharges Associated with Construction Activity at least 10 days prior to the commencement of construction activities disturbing greater than or equal to 1 acre. This permit has several requirements that address water quality and stormwater management, including monitoring and reporting, and the development and implementation of a Stormwater Management Plan (SWMP). Irrigation Flow Management During Phase 1 of the mining development, Scott will not disturb the tailwater channel in its existing location and will implement BMPs to prevent mining operations from discharging into or commingling with these waters. Scott will repair the existing culverted crossing of the tailwater channel to provide vehicle access across the tailwater channel. There will be no changes to the current volumes and locations of irrigation return flows across the property. Wetland Protection A Comprehensive Delineation was completed for the entire property, at the request of the U.S. Army Corps of Engineers (USACE). Scott has submitted this delineation and Aquatic Resource Report to the USACE and requested a Boundary Confirmation (a formal written acceptance of the mapped wetland boundaries). Note that no attempt has been made to distinguish wetlands supported by agricultural water from naturally-occurring wetlands: Scott will avoid impacts to any areas with wetland conditions regardless of the supporting hydrology. The project area has been designed to maintain a minimum 25-foot buffer between any wetland areas and the outer boundary of surface disturbance. The wetland boundaries will be flagged in the field during Phase 1 to ensure that no unintentional impacts occur to the wetlands during surface preparation and berm construction. Once the perimeter berms are constructed, they will serve as a physical barrier separating the mining activity from the adjacent wetland areas. Between the 25-foot buffer and the berm width, there will be approximately 50-foot separation between mine activity and the boundary of wetlands on the parcel. 11.2 Mining Preparation (Phase 2) No mining will occur during Phase 2. This phase of the project will complete any minor components of site grading, vegetation removal, and construction of the site access/driveway initiated during Phase 1, if necessary. Primary activities in this phase include the mobilization and placement of the heavy equipment, a temporary work trailer, screening and wash equipment, temporary vault-and-haul septic trailer, and potable water. This phase will also include the installation of the secondary containment structures associated with the Spill Prevention, Control, and Countermeasure (SPCC) requirements for fueling activities. Equipment for this phase will include, but not be limited to, a bulldozer, track-hoe, and a 35-ton haul truck. 19 Water Handling Phase 1 water management activities will continue throughout this phase. No additional water diversions nor impoundments will be required during this phase. Irrigation return flows will be conveyed across the property without change. Schedule of Operations The Rifle Gravel Pit #1 will operate from 7 a.m. to 7 p.m. Monday through Friday, and weekends, as needed. Excavation operations will occur on an 8-month seasonal schedule, generally April – November as temperatures allow. Due to the nature of the wet mining process, where material is excavated in a saturated state, it is not possible to operate the pit during periods of freezing temperatures. Sales operations may occur year-round if there is commercial demand for the material. Approximately 3 to 5 employees will be on site during the mining operations. No nighttime activities are anticipated. Occasional equipment repair, or maintenance may be conducted at night, but lighting is anticipated to come from temporary, mobile sources; the site will not have ambient lighting. Explosives Explosives will not be used during mining or reclamation of the property. 11.3 Mining Extraction (Phase 3) Phase 3 includes excavating and processing operations for the 12.39 acres of mining area within the 19.00 acres of disturbance. The mine will use conventional mining equipment for this phase, including but not limited to a long-reach excavator, a bulldozer, track-hoe, screening plant, wash plant, crusher, and a 35-ton haul truck. This section describes the mining methods, earthmoving, and size of the areas anticipated to be mined at the 30%, 60%, and 100% mining development of the 12.39 acres over three to five years. Size of Area Worked at 30% The estimated area to be mined at 30% is approximately 3.72 acres (depicted in Figure 4) and amounts to approximately 87,843 CY of mined material. Size of Area Worked at 60% The estimated area to be mined at 60% is approximately 7.43 acres (depicted in Figure 5) and amounts to approximately 175,686 cumulative CY of mined material. Size of Area Worked at 100% The estimated area to be mined at 100% is approximately 12.39 acres (depicted in Figure 6) and amounts to approximately 292,810 cumulative CY of mined material. Mining Methods and Earthmoving This phase of the project will include mining, stockpiling of material for screening, washing and crushing processes. 20 The working surface of the mine will consist of the alluvial gravel surface that is exposed after removal of the overburden. A long-reach excavator stationed on the edge of the pit will excavate material to a depth of approximately 20 feet. The pit will fill with water as excavation proceeds, forming a pond that expands as the excavator continues to remove material. The pond water will be in direct contact with the water table of the Colorado River via lateral migration through the underlying permeable gravels. Excavated material will be piled on the edge of the pond for approximately 24 hours, to allow drainage of free water from the material back into the pond. This will occur through a combination of surface runoff into the pond and infiltration of the free water through the underlying gravels into the pond. Sideload dump trucks will travel to the pond edge and will be loaded with the dried material daily. The dump trucks will transport the dried material from the active excavation area to the processing facility (800 -1,500 feet depending upon the mining location), where the material will be stockpiled for washing, processing, and subsequent sale. Water Handling Any agricultural return flows in the tailwater channel, which are estimated at <2 cubic feet per second (cfs) during peak irrigation season, will be discharged into the pond, where they will mix with the alluvial aquifer and migrate laterally through the permeable gravels into the larger Colorado River water table. Given the minimal flows in the ditch, the large size of the pond (estimated at approximately 6 acres within one year), and the highly permeable nature of the gravel, the agricultural return flows will have a negligible effect on water levels in the pond. As excavation proceeds, the tailwater ditch will be subsumed into the expanding pond boundaries, until under final conditions (Figure 4) the discharge point of the ditch to the pond will be located where the ditch enters the eastern boundary of the property. No other changes to irrigation return flows are proposed, and no additional water handling activities are included. Scott will comply with the State Engineer Office’s (SEO) rules and regulations regarding any water depletions that may also occur during mining operations from water lost due to evaporation and water used for dust suppression. 11.4 Reclamation (Phase 4) The entire extent of the mined area will be restored back to natural conditions upon completion of mining, including the removal of all temporary structures (office, vault and haul toilets, potable water, screen, crusher, equipment). Reclamation will generally proceed in concert with the excavation since the expansion of the pond boundaries will make later access to the perimeter of the mine difficult. A six-foot wide fringe of 5:1 slope will be left at the inner edge of the perimeter berm and planted with wetland reclamation species. The pond surface will be in direct contact with the Colorado River’s water table, and the pond surface elevation will rise and fall in concert with the river level. The intention is for the six- foot wide perimeter fringe to be nearly inundated during high-water periods as the water table rises, and then to be progressively exposed as the water table drops during the growing season. The remainder of the pit slope to the bottom of the pond will be graded at approximately 3:1, not to exceed 2:1. This reclamation design follows County standards for gravel mine reclamation (LUC Section 7-1002.H). This design is not intended to provide formal wetland compensatory mitigation per USACE standards, as no impacts to wetlands are proposed. The perimeter berms and the Operations Area will be resurfaced with topsoil and revegetated with approved seed mixes as the upland reclamation area (totaling 5.83 acres). 21 The wetland slope fringing the pond is approximately 0.79 acres, and under final conditions the surface of the pond is expected to be 12.56 acres. Note that the total acreage reported slightly exceeds 19.00 acres because the median elevation of the pond will inundate a portion of the wetland slope fringe. See Section 12 for additional information regarding reclamation of the property. 12.0 Permanent Stabilization and Post-Mined Conditions (Reclamation, Revegetation and Soil Plan) Figure 6 depicts the stabilized and post-mining conditions of the property. Scott plans to reclaim the property as mining progresses, with only the Operations Pad remaining un-reclaimed, with a stabilized working surface, until all mining extraction is complete. Areas disturbed during development shall be restored with natural-appearing landforms that blend with the adjacent undisturbed topography within 90 days of completion to meet Garfield County standards. Scott will start the reclamation process as soon as mining progresses throughout the site. The excavated pit will fill with water and the pond will expand as mining proceeds; therefore reclamation effort will be focused on the creation of the 5:1 wetland slope fringe around the perimeter of the pit. This wetland slope will be created in concert with the expanding excavation, to avoid the difficulty and disruption of returning heavy equipment to areas of the pond at the conclusion of mining. 12.1 Description and Types of Reclamation, Revegetation, and Soil Plan Scott will achieve the required reclamation of the affected land per the Garfield County Land Use Permitting and seeding regulations using existing and available equipment. The primary reason for this goal is to minimize dust and erosion of the property and restore the site back to its natural conditions to the extent practicable. Figure 11 provides the amount of acreage proposed for each reclamation activity. All reclamation will occur with specified equipment and methods for attaining successful revegetation of the property. It is estimated that a 12.56-acre pond will be present post- mining. 12.2 Post-Mining Land Use The adjacent properties are primarily agricultural, county and interstate roadways, oil and gas well pad and the Colorado River. The post-mining land uses will be like the current land use and not conflict with adjacent land uses, which are currently comprised of agricultural uses. 22 Figure 11. Seeding and Reclamation Details 23 13.0 Implementation of the Reclamation Plan 13.1 Topsoil Segregation, Preservation, and Replacement The topsoil and overburden excavated, stockpiled an/ or used for berm construction during Phase 1 will be used to support the revegetation of the site. Backfilling and recontouring of the excavation area will not occur; the 12.56-acre pond filling the excavation pit will be left in place after the mining and extraction activities finish. Areas outside the boundaries of the pond, including the Operation Pad, will resurfaced with overburden and topsoil. This will be placed with a bulldozer and haul trucks. A roller will be used for compaction and sloping. Recontouring to a rough texture will support the establishment of broadcasted seeds and moisture retention. Stored topsoil and growth medium will be replaced evenly to a depth of 4-6 inches unless site conditions preclude this depth. Topsoil will also be left very rough. Soils will not be worked when wet to avoid mixing, loss of topsoil, and potential erosion issues. 13.2 Final Grading Final grading of the site is depicted on the Reclamation Map (Figure 12). This figure shows the anticipated maximum slope gradient range for reclamation. The pond created by the mining activity is proposed to remain as a permanent feature of the site. The Last Chance Ditch tailwater channel will continue to discharge agricultural return flows into the pond. There are no other existing ephemeral draws and washes that pass through the mine area. 13.3 Seeding There are different types of seed mixes to support temporary and permanent stabilization and reclamation of the site. Figure 11 provides the seeding and reclamation details. Temporary Seed Mix A temporary seed mix is not proposed at this time. Construction is proposed to begin in summer of 2022, and the permanent reclamation seeding would be applied in the fall. Temporary seed mixes may be considered if the site needs additional stabilization, but the completion of reclamation in concert with mining operations should obviate the need for this measure. Long-Term/Permanent Seed Mix Seeding should occur in the late fall to avoid seeds from germinating in the summer or early fall, and then either desiccating or freezing. Figure 11 provides detailed information regarding the various types of seed mixes proposed including form (shrub, bunch, sod, etc.) and application rate. Seeding application is expected to be by drilling exclusively. Broadcast seeding may be employed in areas where drill seeding is not possible (due to steep slopes or constrained access). The wetland reclamation areas will also include hand-planting for the woody vegetation. 24 Figure 12. Reclamation Plan 25 14.0 Erosion Control Measures Figure 9 provides information regarding the erosion and sediment control measures. Figure 13 and Figure 14 depict the Best Management Practices proposed for the project. 15.0 Estimated Cost Reclamation details are provided in Figures 11 and Figure 12. The pond will not be backfilled but will remain as open water. A 6-foot wide 5:1 wetland slope will be constructed on the inner perimeter of the pond, transitioning to 3:1 slope to full depth. Reclamation costs are also associated with reclamation activities on the perimeter berm, the 25-foot-wide upland buffer on the outside of the perimeter berm, and the reclamation of the Operations Area. Volumes, areas, and seeding mixes are provided in Figure 11. • Backfill of the pond to create the 0.79 acres of wetland reclamation area, utilizing approximately 637 CY of salvaged fill and topsoil, at a cost of $3/CY = $1,911 total. • Seeding and Planting of the 0.79 acres of wetland reclamation area with the Wetland Seeding and Planting Mix, at a cost of $10,000/ac = $7,900 total. • Construction of perimeter berms on 3.90 acres, utilizing approximately 12,163 CY of salvaged fill and 2,390 CY of salvaged topsoil, at a cost of $3/CY = $36,489 total. • Replace 2,390 CY of salvaged topsoil on the perimeter berms at a cost of $3/CY = $7,170 total. • Seeding and erosion control on the 3.90 acres of perimeter berms, using the Upland Seeding and Planting Mix, at a cost of $1000/ac = $3,900 total. • Removal of gravel surface and regrading of Operations Area, placement of topsoil, and seeding with Upland Seeding and Planting Mix on 1.93 acres, at a cost of $5,000/ac = $9,650 total. Based on these costs, and a 28% DRMS cost factor, the total bond for the Rifle Gravel Pit will be $85,785.60 Table 3 provides more costing information, including the DRMS cost factor. Table 3. Reclamation Costs Activity Description Time (Months) Cost ($) Backfill of pond to create wetland fringe .1 1,911 Seeding & Planting of wetland fringe .1 7,900 Construction of perimeter berms .25 36,489 Surfacing of perimeter berms with topsoil .1 7,170 Seeding of berms with upland seed mix .1 3,900 Surface prep and seeding of Operations Area .1 9,650 Sub-Total .75 67,020 DRMS Costs (28% x direct costs) 18,765.60 Total Bond Amount $85,785.60 26 Figure 13. Proposed Best Management Practices for Sediment and Erosion Control 27 Figure 14. Best Management Practices for SPCC 28 16.0 Calculations 16.1 Floodplain Analyses Floodplain modeling analysis was conducted to understand the influence of the proposed project on the 100-year floodplain. The influence on rainfall on the project will be contained by the perimeter berm to support mining. There are no sediment basins nor detention/retention facilities included for the project. See the Floodplain Analysis in Appendix H of the Land Use Permit. 17.0 Neighboring Areas Per Garfield County submittal requirements, a list of landowners and mineral rights owners within 200-feet of the proposed project parcel is included with this submittal. Adjacent landowner addresses were obtained from the Garfield County Assessor’s web-based database. There are four adjoining properties with corresponding surface landowners: • North – Colorado River Ranch, LLC • West – Rex Robinson Ranch, LLC; Swanson Colorado Trust; Ilgen, Carrol Jeanne; Rosa, Linda Jane; Robinson, James Dean • South – Colorado Department of Transportation (CDOT) • East – Shidelerosa LLLP This information was obtained from the Garfield County Colorado Land Explorer (Garfield County, May 2022). North Side: The parcel adjacent to the north is owned by Colorado River Ranch, LLC and is currently zoned Rural. There aren’t any compatibility issues with the proposed project since the current use is agricultural. West Side: The Rex Robinson Ranch, LLC, currently owns the property to the west. This property is zoned Rural. There is currently an oil & gas pad on this property which isn’t currently being used. The current use of this property is compatible to the proposed mine project. South Side: The property to the south is currently owned by CDOT (I-70 N Frontage Road, also referred to as County Road 346) and is parallel to the property. East Side: The property to the east is owned by Shidelerosa LLLP and is zoned Rural. This property is currently used for agricultural purposes and there is one residential driveway approximately 0.45-mile from the proposed mine property. All landowners have been notified of the proposed development. The proposed use is consistent with the predominant existing uses in the surrounding area. Figure 1 depicts the existing use of the adjacent properties within a 600-foot radius of the Rifle Pit #1 property. 29 18.0 Stormwater Management A description of stormwater management planning concept for the site, including both structural and non-structural BMPs is mentioned in the Mining Plan (Section 11) and Reclamation and Post-Mining (Section 12) discussions of this document. 18.1 Stormwater Management Plan (SWMP) A copy of the SWMP application to CDPHE with date of submittal will be sent to Garfield County once the Land Use Permit is approved and there is a better idea for when construction and mining will commence. 19.0 Reclamation, Revegetation, and Soil Plan Section 13.3 addresses the plant material and seed mix lists for both temporary and permanent stabilization. Most of the post-mined condition for the Rifle Pit #1 site will be a pond. The reclamation process will proceed contemporaneously with the development of the mine: • The perimeter berms will receive reclamation seeding as soon as practical after they are constructed. • The wetland slope reclamation area will be constructed around the perimeter of the pond as the pond expands, and the constructed acreage will be seeded/planted on an annual basis during the appropriate planting season (typically late fall). • The operations area will be reclaimed at the conclusion of mining activities. 19.1 Weed Management Plan Noxious weeds identified through the Colorado Noxious Weed Act (C.R.S. 35-5.5) will be controlled per state and county regulation. Control will be achieved by the following measures: • A weed survey of the permit area will be completed every spring. • Infestations will be treated using approved chemicals and will be sprayed by a certified applicator. • After reclamation, weed surveys and treatment will continue until the perennial cover and production of the site have met DRMS requirements and bond release has been obtained. • The Garfield County Vegetation Manager and the NRCS was consulted during the development of the Weed Management Plan (Appendix I of the Land Use Permit). The reclamation plan does not contemplate total weed removal on the property; past experience has shown that some weed infestation is common on the property and in surrounding areas, and complete eradication will not be feasible given limitations in control methods and surrounding infestations. Additional information regarding noxious weed control includes the commitment that Scott will treat all noxious weeds on a biannual basis, with an herbicide application in the spring (late June) and late summer (late August). Gravel storage piles will be treated with a bare ground herbicide if the piles are expected to remain for more than 1 season. Scott will use a Colorado-certified herbicide applicator. All work equipment will be sanitized and have any existing dirt, vegetation, or seeds from landscaping and operational work removed before 30 leaving the work area. Prior to bond release, Scott will conduct a noxious weed inventory and bond release reports developed by third parties for submittal to DRMS and Garfield County. Mr. Steve Anthony, Garfield County Vegetation Manager, provided the following comments regarding the project: “The Weed Management Plan needs to provide more details on noxious weed management during mining activities.” In response to this comment Scott updated the Weed Management Plan to include language that addresses the treatment of all noxious weeds on a biannual basis, treatment of gravel storage piles with bare ground herbicide, and implementation of additional best management practices. 19.2 Revegetation Security Scott understands that a revegetation security may be required if, in the determination of the County Vegetation Manager, the proposed project has: • A potential to facilitate the spread of noxious weeds; • A potential to impact watershed areas; • A potential for visual impacts from public viewing corridors; • Steep Slopes 15% or greater or unstable areas; and/or • Disturbs an area 1 acre or greater where topsoil is exposed for the purposes of site construction, development or grading but does not comprise the long- term functioning of the site (i.e. building footprint, road surface or permanent parking areas). Scott understands that the County Vegetation Manager will determine the security amount and that it will be site specific and based on the amount of disturbance. The security shall be held by the County until vegetation has been successfully reestablished, or for a period approved by the County Vegetation Manager in any specific land use action, according to the Reclamation and Revegetation Standards section in the Garfield County Weed Management Plan. The County Vegetation Manager will evaluate the reclamation and revegetation prior to the release of the security and shall be subject to all provision of Article 13. 20.0 Hydraulic Calculations See the Floodplain Analysis is included as Appendix H of the Land Use Permit document. 21.0 Maintenance Requirements The Scott on-site staff will be responsible for maintaining the integrity of all BMPs including the access road and on-site drainage and stockpiling activities. Maintenance activities will be on-going and an integral part of mining operations to foster safety and compliant operations. 31 22.0 Spill Prevention Control and Countermeasures Plan (SPCC) Scott understands that a SPCC Plan will be required if the Rifle Pit #1 property has the potential to discharge oil of any kind or in any form including, but not limited to, petroleum, fuel oil, sludge, oil refuse and oil mixed with wastes, in quantities that may be harmful to navigable water and adjoining shoreline, per EPA regulations. A copy of the SPCC Plan is included as Appendix F of the Land Use Permit. 32 23.0 Signature Block I acknowledge the review and acceptance of responsibility for preparing this Grading and Drainage Plan based upon the existing and available information regarding the Rifle Pit #1 site development. Angela B. Fowler, P.E. Senior Water Resource Engineer SPILL PREVENTION, CONTROL AND COUNTERMEASURE PLAN Scott Contracting, Inc. has prepared a spill control plan to prevent the contamination of the surrounding environment. Containment structures will be constructed to prevent spills from entering state waterways, lakes, streams and/or storm sewers. On site spill control will be used while refueling the equipment and handling hazardous substances. If a spill occurs, follow the steps below for clean-up procedures and contact information. In Case of Leak or Spill: 1. Contact Project Manager or Supervisor immediately. (Contact information is listed below) 2. Contain spill and start cleanup using the spill control kit located on-site. The kit will contain a sorbent boom, sorbent rags, absorbent litter and an over-pack drum to store the material. 3. If a spill occurs that requires emergency response based on the reportable quantities, use the contact information listed below for clean-up and disposal of hazardous materials. Reportable Quantities: • 25 gallons of engine oil, fuel or hydraulic/brake fluid released to land. • A visible sheen of engine oil, fuel or hydraulic/brake fluid released to water. • 100 lbs (13 gallons) of antifreeze released to land. • 100 lbs of battery acid released to land or water. • 1 lb of refrigerant released to the air. • 100 lbs of gasoline released to the air, land or water. • 100 lbs of engine degreasers released to the air, land or water. Scott Contracting, Inc. Contacts: 1. Tony Roberts (VP - Operations) 720-490-7405 2. Christian Baumgart (Area Manager) 720-692-4035 3. Dan Spahn (Safety Manager) 720-490-7408 Project Engineer: 1. SGM Hazardous Substances Contained On-Site: The following is a list of chemicals we will have on-site, which will be stored in double- wall tanks, with a berm around the tanks and the entire area will be lined with plastic for containment purposes. • 100 Gal Engine oil • 300 Gal Diesel • 50 Gal of gasoline • 30 Gal of Mixed gas • 2 boxes of marking paint • On-site fueling of equipment Equipment Available: All equipment, not limited to the equipment listed below, necessary to contain or mitigate a pollutant spill shall be on site within one hour of when the spill occurs. • Vac Con Combo Jet Truck (2700 gal. Capacity)U This truck can be used to clear a blockage as well as provide 2700 gallons of storage capacity. • 8" Diesel Pump w/ 550' of discharge hose This pump and hose will be on standby and can be delivered and set up quickly to help in the event of primary and redundant pump failures. • Excavator This can be used to remove any hazardous material and also any contaminated soil from the site. • Loader This can be used to remove any hazardous material and also any contaminated soil from the site. Environmentally Sensitive Areas: The following areas have been identified as being environmentally sensitive. These may include spillways, channels, and storm drainage that lead directly or indirectly to the Receiving Waters and/or pose a threat to ground water. Extra care and preventative measures will be taken to minimize the risk of contamination. • Last Chance Ditch • Irrigation/Tailwater Ditch Notification of Regulatory Agencies: In the event of a discharge, spill or overflow of pollutants that has the potential to affect public health or the environment, the following parties shall be notified for non- hazardous materials: 1. Colorado Department of Public Health and Environment Spill Report Line: 1-877- 518-5608 2. CDOT illicit discharge hotline: 303-512-4426 3. Colorado State Patrol if spill is on a State Highway: 303-239-4501 In the event of a discharge, spill or overflow of pollutants that has the potential to affect public health or the environment, the following parties shall be notified for hazardous materials: 1. Local emergency response team: 911 2. Colorado Department of Public Health and Environment Spill Report Line: 1-877- 518-5608 3. CDOT illicit discharge hotline: 303-512-4426 4. Colorado State Patrol if spill is on a State Highway: 303-239-4501 Erosion Control Training: All employees working on this jobsite have attended and successfully completed a 6- hour orientation course through Scott Contracting on Safety Procedures and Erosion Control awareness. Topics covered, among other things, included: BMP identification, Respect for Installed BMPs and Immediate Notification to Superintendent of Damaged BMPs. In addition to the reporting requirements of the paragraph above, Scott Contracting, Inc. shall notify CDOT in the event of any discharge, spill or overflow to the environment: Prepared by: Scott Contracting, Inc. __________________________________ Signature Date Approved by: CDOT __________________________________ Signature Date By authorized signature below, Scott Contracting, Inc., hereinafter referred to as 'the Contractor', hereby certifies that this Spill Prevention, Control and Countermeasures Plan (Plan) complies with and meets applicable Federal, State, and local laws, rules, regulations and guidelines governing safety, health and sanitation, including but not limited to the Occupational Safety and Health Act, 29 CFR 1910, 29 CFR 1926, Mine Safety and Health Administration (MSHA), Title 30 CFR, the "Colorado Work Zone Best Practices Safety Guide'', national consensus standards, the Drug-Free Workplace Act (Public Law 100-690 Title V, subtitle D, 41 USC 701 et seq.) and the Colorado Department of Public Health and Environment. All operations and work practices of the Contractor will comply with this Plan. The Contractor requires that all subcontractors, suppliers and Department personnel comply with this Plan. Signature Erosion Control Supervisor Title Date IHC Scott – Rifle Gravel Pit #1 May 2022 Garfield County Special Use Permit Application Appendix G Appendix G – Impact Analysis IHC SCOTT RIFLE PIT #1 IMPACT ANALYSIS REPORT RIFLE PIT #1 IHC SCOTT (SCOTT CONTRACTING INC.) MAY 2022 Prepared by 118 West Sixth Street, Suite 200 Glenwood Springs, CO 81601 970.945.1004 970.945.5948 fax IHC Scott – Rifle Gravel Pit #1 Impact Analysis Report May 2022 i TABLE OF CONTENTS 1.0 Rifle Pit #1 Impact Analysis 1 1.1 Adjacent Land Use 1 1.2 Site Features 1 1.3 Soil Characteristics 6 1.4 Geology and Hazard 6 1.5 Groundwater and Aquifer Recharge Areas 6 1.6 Environmental Impacts 8 IHC Scott – Rifle Gravel Pit #1 Impact Analysis Report May 2022 1 1.0 Rifle Pit #1 Impact Analysis This report documents the existing conditions and the potential changes created by the Rifle Pit #1 project and describes how IHC Scott (Scott) [formerly Scott Contracting, Inc. (SCI)] will ensure that impacts will be mitigated, and standards will be satisfied. The following sections address the information required in the Land Use Development Code (LUDC) Section 4-203.G. 1.1 Adjacent Land Use Per Garfield County submittal requirements, a list of landowners and mineral rights owners within 200-feet of the proposed project parcel is included with this submittal. Adjacent landowner addresses were obtained from the Garfield County Assessor’s web-based database. There are four adjoining properties with corresponding surface landowners: · North – Colorado River Ranch, LLC · West – Rex Robinson Ranch, LLC; Swanson Colorado Trust; Ilgen, Carrol Jeanne; Rosa, Linda Jane; Robinson, James Dean · South – Colorado Department of Transportation (CDOT) · East – Shidelerosa LLP This information was obtained from the Garfield County Colorado Land Explorer (Garfield County, May 2022). North Side: The parcel adjacent to the north is owned by Colorado River Ranch, LLC and is currently zoned Rural. There aren’t any compatibility issues with the proposed project since the current use is agricultural. West Side: The Rex Robinson Ranch, LLC, currently owns the property to the west. This property is zoned Rural. There is currently an oil & gas pad on this property which isn’t currently being used. The current use of this property is compatible to the proposed mine project.. South Side: The property to the south is currently owned by CDOT (I-70 N Frontage Road, also referred to as County Road 346) and is parallel to the property. East Side: The property to the east is owned by Shidelerosa LLP and is zoned Rural. This property is currently used for agricultural purposes and there is one residential driveway approximately 0.45-mile from the proposed mine property. All landowners have been notified of the proposed development. The proposed use is consistent with the predominant existing uses in the surrounding area. Figure 1 and Figure 2 depict the existing use of the adjacent properties within a 1,500-foot radius of the Rifle Pit #1 property. 1.2 Site Features Figure 2, Figure 3, and Figure 4 depict the existing conditions of the waterbodies, topography, and vegetation cover of the property. IHC Scott – Rifle Gravel Pit #1 Impact Analysis Report May 2022 2 Figure 1. Properties within 1,500 feet of Rifle Pit #1 IHC Scott – Rifle Gravel Pit #1 Impact Analysis Report May 2022 3 Figure 2. Property Ownership Adjacent to the Rifle Pit Property and Waterbodies IHC Scott – Rifle Gravel Pit #1 Impact Analysis Report May 2022 4 Figure 3. Topography and Existing Conditions of the Rifle Pit #1 Property IHC Scott – Rifle Gravel Pit #1 Impact Analysis Report May 2022 5 Figure 4. Topography and Waterbodies near the Rifle Pit #1 Property IHC Scott – Rifle Gravel Pit #1 Impact Analysis Report May 2022 6 1.3 Soil Characteristics According to the USDA NRCS Web Soil Survey, most of the soil map units in the permit area are ranked as fair gravel sources and one soil unit (Olney loam) is ranged a poor. All the soils except the Kim loam is rated as fair condition for sand sources. Approximately 50% of the permit area has soil units that are rated as fair to good for reclamation material. Where/when applicable, the top 4 - 6 inches of topsoil will be salvaged and stored for later reclamation uses. The soils within the subject parcel are mapped by the NRCS as soil units: · Halaquepts, nearly level · Kim loam, 3 to 6% slopes · Olney loam, 1 to 3% slopes · Wann sandy loam, 1 to 3% slopes Note this property is being considered for gravel extraction as a result of the presence of these soils. Reclamation activity will proceed in concert with the excavation. A six-foot wide fringe of 5:1 slope will be left at the inner edge of the perimeter berm and planted with wetland reclamation species. The intention is for the six-foot wide fringe to be nearly inundated during high-water periods as the water table rises, and then to be progressively exposed as the water table drops during the growing season. The remainder of the pit slope to the bottom of the pond will be approximately 3:1, not to exceed 2:1. Note that this reclamation effort follows local Garfield County guidelines and standards (LUC Section 7-1002.H). Formal wetland mitigation per USACE standards is not required, as no impacts to wetlands are proposed. See Figure 5 for the post-mining site conditions. 1.4 Geology and Hazard No natural geologic nor manmade hazards exist on the property that would influence the proposed use of the site. 1.5 Groundwater and Aquifer Recharge Areas The Colorado River borders the property to the north. A berm will be constructed to minimize the influence of the Colorado River on the proposed land use and operations. The height of the berm will be 5 feet and was determined by conducting floodplain modeling. See Land Use Permit for additional information on the floodplain modeling and floodplain analysis. The principal aquifer properties at the site are: · Saturated thickness (b) – the thickness of the saturated porous medium measured as the difference between the static water level and the base of the aquifer, measured in feet. Average saturated thickness of 18 feet at the site. · Hydraulic conductivity (K) – a measure of the capacity of a porous medium to transmit a volume of water through a unit cross-sectional area, typically expressed in units of feet per day. The aquifer at the site is assumed to have a uniform hydraulic conductivity of 1,000 feet per day. · Storage coefficient or specific yield (Sy) – the volume of water released from a unit volume of saturated aquifer per unit decline in head, expressed as a fraction. The aquifer at the site is assumed to have a uniform value of 0.2 for specific yield. IHC Scott – Rifle Gravel Pit #1 Impact Analysis Report May 2022 7 Figure 5. Reclamation Plan Rifle Gravel Pit #1 April 2022 8 · Transmissivity (T) – a measure of the capacity of a porous medium to transmit a volume of water through the entire saturated thickness, expressed in units of feet2 per day. Transmissivity is obtained by multiplying the hydraulic conductivity by the saturated thickness (T = K x b). Transmissivity is approximately 18,000 feet2 per day. The Land Use Permit document includes a Wetlands report that outlines the existing conditions of the site. 1.6 Environmental Impacts The determination of the existing environmental conditions on the parcel to be developed and the effects of development on those conditions specific to flora and fauna, wildlife and domestic animals, and radiation hazards are described in the following sections. Rifle Gravel Pit #1 April 2022 9 Riparian Woodland/Shrubland Russian olive (Elaeagnus angustifolia) Big sagebrush (Artemisia tridentata) Greasewood (Sarcobatus vermiculatus) Rubber rabbitbrush (Ericameria nauseosa) Alkali sacaton (Sporobolus airoides) Inland saltgrass (Distichlis spicata) The entire extent of the site will be restored back to natural conditions upon completion of mining, including the removal of all temporary structures (office, vault and haul toilets, potable water, screen, crusher, equipment). The site will be graded to compliment the surrounding topography and a shallow 5:1 slope fringe around the pond boundary addresses concerns voiced by USFWS and CPW regarding animal entrapment danger, while also meeting Garfield County gravel pit reclamation standards. Areas disturbed by grading will be contoured so they can be revegetated and will be revegetated to stabilize the surface from erosion. Reclamation will proceed in concert with the excavation. A six-foot wide fringe of 5:1 slope will be left at the inner edge of the perimeter berm and planted with wetland reclamation species. The intention is for the six-foot wide fringe to be nearly inundated during high-water periods as the water table rises, and then to be progressively exposed as the water table drops during the growing season. The remainder of the pit slope to the bottom of the pond will be approximately 3:1, not to exceed 2:1. Note that this reclamation effort follows Garfield County LUC standards (LUC Section 7-1002.H) and is not intended to serve as formal wetland mitigation per US Army Corps of Engineer’s standards, which do not apply to this project. Determination of the Effect on Designated Environmental Resources, including Critical Wildlife Habitat Mining will remove vegetation in phases allowing incidental use of the site by wildlife, if needed. Wildlife will likely avoid the parcel entirely once mining development commences, and the existing level of casual use will be displaced to adjacent unimpacted habitats along the southern bank of the Colorado River. It is expected that the itinerant species will continue to utilize surrounding habitats given the small area of the mine. However, the existing mosaic of meadows and riparian woodland will not be recovered, and the property will support a much less complex environment dominated by agricultural cultivars. This could continue to provide winter grazing habitat for elk and mule deer, although the habitat quality would be low due to a lack of woody cover vegetation. Wild Turkey would likely abandon the parcel. Bald eagle foraging is concentrated along the Colorado River, and would be minimally impacted by the proposed development. Most small mammal and passerine bird species will be able to resume use of the area once reclamation is complete; the longest- term potential habitat detractor will be persistence by noxious weeds. The area is seasonally used by the following species (based on CPW & COGCC RSO/SWH habitat data): Rifle Gravel Pit #1 April 2022 10 · Bald Eagle (Winter Forage, Winter Range) · Elk (Severe Winter Range, Overall Range) · Mule Deer (Resident Population Area, Severe Winter Range, Winter Concentration Area, Winter Range, Overall Range) · Wild Turkey (Winter Concentration Area, Winter Range, Overall Range) Wildlife and Domestic Animals There are no significant wildlife resources on the property. The site supports seasonal, low- level big game use, and typical use patterns of mesic shrublands and pasturelands. The impact to area wildlife should be minimal as a result of this project. A 5-foot tall berm will be constructed around the perimeter of the site therefore some wildlife may experience a slight change in traveled corridors to maneuver around the mine area. See the Land Use Application for more detailed discussions regarding Wildlife Habitat Areas. IHC Scott – Rifle Gravel Pit #1 May 2022 Garfield County Special Use Permit Application Appendix H Appendix H – Floodplain Analysis IHC -Scott R evised Floodplain Development Permit Narrative for Rifle Pit #1 August 2022 Prepared by 118 West Sixth Street, Suite 200 Glenwood Springs, CO 81601 970.945.1004 Revised Floodplain Development Permit Narrative for Rifle Pit #1 August 2022 R evised Floodplain Development Permit Narrative for Rifle Pit #1 IHC-SCOTT Prepared By Richard (Chip) Fisher, P.E. QC Reviewed By Angela B. Fowler, P.E. SGM Project 2019-341.002 Revised Floodplain Development Permit Narrative for Rifle Pit #1 August 2022 1 Table of Contents 1.0 Project Description ........................................................................................................ 1 2.0 Engineering and Floodplain Analysis ........................................................................... 1 3.0 Proof of Ownership and Statement of Authority ........................................................ 1 4.0 Analysis of LUDC Article 3 ............................................................................................. 2 4.1 Section 3-301.A Use Restrictions in the Floodplain Overlay .................................... 2 4.2 Section 3-301.B General Standards .......................................................................... 2 4.3 Section 3-301.C Specific Standards ......................................................................... 2 4.4 Section 3-301.D Floodway ........................................................................................ 2 4.5 Section 3-301.E Standards for Areas of Shallow Flooding ...................................... 3 4.6 Section 3-301.F Properties Removed from the Floodplain by Fill ........................... 3 4.7 Section 3-301.G Alteration of a Watercourse ......................................................... 3 4.8 Section 3-301.H Standards for Critical Facilities ....................................................... 3 5.0 Analysis of LUDC Article 4 ............................................................................................. 3 5.1 Section 4-102 Applicability of Common Review Procedures ................................ 3 5.2 Section 4-109.C Review Criteria of Development in the 100-year Floodplain ..... 3 Analysis of Section 4-109.C.1 ............................................................................. 3 Analysis of Section 4-109.C.2 ............................................................................. 3 Analysis of Section 4-109.C.3 ............................................................................. 3 Analysis of Section 4-109.C.4 ............................................................................. 4 Analysis of Section 4-109.C.5 ............................................................................. 4 Analysis of Section 4-109.C.6 ............................................................................. 4 Analysis of Section 4-109.C.7 ............................................................................. 4 Analysis of Section 4-109.C.8 ............................................................................. 4 Analysis of Section 4-109.C.9 ............................................................................. 4 Analysis of Section 4-109.C.10 ........................................................................... 4 5.3 Section 4-201 Application Materials ........................................................................ 5 5.4 Section 4-203.O Floodplain Analysis ......................................................................... 5 6.0 Analysis of LUDC Article 7 ............................................................................................. 5 6.1 Section 7-203.A Minimum Setback .......................................................................... 5 6.2 Section 7-203.B Structures Permitted in Setback ..................................................... 5 6.3 Section 7-203.C Structures and Activity Prohibited in Setback .............................. 6 6.4 Section 7-203.D Compliance with State and Federal Laws ................................... 6 7.0 Engineer’s Contact Information .................................................................................. 6 Revised Floodplain Development Permit Narrative for Rifle Pit #1 August 2022 2 Attachment A .......................................................................................................................... A Attachment B ........................................................................................................................... B Attachment C .......................................................................................................................... C Attachment D .......................................................................................................................... D Attachment E ............................................................................................................................ E Revised Floodplain Development Permit Narrative for Rifle Pit #1 August 2022 1 1.0 Project Description IHC Scott (Scott, the “Applicant”) is seeking a Floodplain Development Permit for a commercial gravel pit (Rifle Gravel Pit #1; “Project”) to be located on a 58.7-acre parcel immediately north of Interstate 70 between the Towns of Rifle and Silt. The parcel is located off County Road (CR) 346, accessed from the Mamm Creek I-70 interchange. The entire project would be located on one parcel (Parcel ID #217908300103), owned by Scott. The parcel is currently vacant, with no structures or active land management activity. The parcel has been historically used as irrigated pasture for cattle grazing for several years and receives irrigation water via a tailwater ditch but has not received intentional irrigation water application since Scott acquired the parcel in 2019. The parcel continues to be used on an occasional and incidental basis for cattle grazing while Scott develops the plans for the commercial gravel pit. The proposed development would be a wet mining operation where the topsoil and mineral overburden would be removed and stockpiled for onsite use or sale as topsoil and clean fill respectively, and the underlying saturated alluvial gravels would be excavated in a saturated state. Excavation would be accomplished using a long-reach excavator located on the upper rim of the excavated pit. No dewatering nor groundwater pumping would occur with this proposed mining development, and the excavated pit would fill with groundwater to become a pond as mining progresses through the site. IHC-Scott retained SGM to prepare a Floodplain Development Permit and this narrative, along with the listed attachments, addresses all technical and engineering requirements from the pertinent sections of the Garfield County Land Use Development Code (LUDC). 2.0 Engineering and Floodplain Analysis SGM developed engineering drawings (Attachment A) to quantify the extents and quantities of disturbance and extracted materials from the Project area. An estimated 100- year floodplain and floodway delineation with base flood elevation (BFE1) were determined by SGM to address the pertinent sections of the LUDC. The effective FEMA study area (Panel 0802051360B dated 12/15/1977) covering the project area shows a Zone A floodplain, which is an unstudied approximate floodplain delineation. The 100-year flood event of the Colorado River was modeled to determine a base flood elevation and floodplain delineation. The Floodplain Engineering Report (Attachment B) discusses the methodology used to determine the base flood elevation in the vicinity of the Project area as well as the floodplain and floodway delineations. The modeled floodplain and floodway delineations determined by SGM are clearly defined and labeled in the engineering drawings (Attachment A). 3.0 Proof of Ownership and Statement of Authority Attachment C contains the statement of authority, title commitment dated 9/8/2020, and the certification of mineral rights owner research form. 1 Base flood elevation (BFE) is the water surface elevation during the 100-year flood event. Revised Floodplain Development Permit Narrative for Rifle Pit #1 August 2022 2 4.0 Analysis of LUDC Article 3 4.1 Section 3-301.A Use Restrictions in the Floodplain Overlay Per Table 3-301 in the LUDC, a gravel mine is permitted in the 100-year floodplain but not permitted in the floodway. Sheet 3 of Attachment A shows that the 100-year floodplain covers a portion of the Scott parcel and the Project area. The floodway does not cover any portion of the parcel. 4.2 Section 3-301.B General Standards A proposed mobile or prefabricated office/scale-house building is to be placed outside of the floodplain, within the designated “Operations Area” shown on Sheets 6 & 7 of Attachment A. As a precaution against the unlikely case of shallow inundation, SGM recommends that any structures be anchored to reinforced concrete caissons and built with a lowest finished floor elevation (FFE) of 5385.14’, or 1-foot above the BFE, in the vicinity of the operations pad area. No permanent structures or hazardous material storage areas will be placed within the actively mined gravel pit area, the floodplain, or the floodway. No new or replacement water supply or sanitary sewer systems are proposed to be installed at the gravel pit area. Drinking water will be delivered to the site. Scott will contract with a vault-and-haul vendor to provide wastewater (and hand-washing water) services. Scott will have a trailer outfitted with two restrooms for staff. This trailer will have one 2,000-gallon tank to capture waste from the toilet and handwashing facilities. A high-level float alarm will also be installed and notify Scott when the tank needs to be pumped. The handwashing facilities will be designed to receive potable water (treated). An on-site waste disposal system is not feasible due to the constrained available site area for gravel mining and operations because of the presence of protected Water of the United States2 on the parcel. 4.3 Section 3-301.C Specific Standards There are no defined BFE’s in the vicinity of the parcel; the effective FEMA panel covering the project area shows a Zone A floodplain, which is an unstudied approximate floodplain delineation. The 100-year flood event of the Colorado River was modeled to determine a base flood elevation and floodplain delineation. There are no proposed structures to be constructed or placed inside the modeled floodplain or floodway. 4.4 Section 3-301.D Floodway This section of the LUDC does not apply as neither the parcel nor the Project is located within the estimated extents of the floodway, Sheet 3 of Attachment A shows the floodway delineation is approximately 0.2-miles away from the northern parcel boundary at its closest approach. 2 https://www.epa.gov/wotus/about-waters-united-states Revised Floodplain Development Permit Narrative for Rifle Pit #1 August 2022 3 4.5 Section 3-301.E Standards for Areas of Shallow Flooding The parcel is partially covered Special Flood Hazard Area (SFHA), designated as Zone A, which is an unstudied approximate floodplain boundary. See the analysis in Section 4.2 of this narrative for SGM’s recommendation for protection against shallow inundation. 4.6 Section 3-301.F Properties Removed from the Floodplain by Fill The proposed berm and other modifications of the site have been modeled to show a no- rise of the BFE, which is detailed in the Floodplain Engineering Report (Attachment B). 4.7 Section 3-301.G Alteration of a Watercourse This section does not apply, no watercourse shall be changed with the proposed Project. 4.8 Section 3-301.H Standards for Critical Facilities This section does not apply because the proposed Project does not meet the definition of a critical facility. 5.0 Analysis of LUDC Article 4 5.1 Section 4-102 Applicability of Common Review Procedures SGM has engaged the County staff throughout the permitting process and held a specific pre-application conference meeting to address the Land Use Change and Floodplain Development Permit application. Mailed notice will be sent to neighbors (see the mailing list in Attachment C) following submittal of this application to the County. 5.2 Section 4-109.C Review Criteria of Development in the 100-year Floodplain Analysis of Section 4-109.C.1 Danger to life and property from flooding or erosion damage will be mitigated by use of the perimeter berm. Safe access to the parcel will be provided with improved paving on approximately 3,252 linear feet of County Rd 346 and a paved driveway from the county road to enter the Project site, per CDOT Access Permit #320024 (Attachment D). Analysis of Section 4-109.C.2 The perimeter berm will mitigate flooding risk and minimize danger to life and property damage inside the Project area. The berm shall be constructed at least 5-feet high with 2:1 revegetated side-slopes along the parcel’s boundary and have a footprint of at least 25-feet in width. The top-of-berm elevation is therefore no less than 1-foot above the BFE. The berm is designed to sustain the hydrodynamic forces and shear stresses exerted by the 100-year flood event and prevent inundation inside the parcel. In addition, there is no predicted significant increase in the BFE because of the Project; therefore, no adverse flooding impacts to adjacent properties will result from the proposed development (see Attachment B). Analysis of Section 4-109.C.3 The parcel is susceptible to inundation, but that risk will be mitigated with the perimeter berm (discussed above and detailed in Attachment A). Hydrodynamic parameters in the Revised Floodplain Development Permit Narrative for Rifle Pit #1 August 2022 4 vicinity of the Project during the 100-year storm event (100-year flood) have been modeled and are summarized in Table 2 in Attachment B. Velocities and shear stresses are expected to be less than 3 feet per second (fps) and 1 pound per square foot (psf), respectively. Under those conditions, the hydrodynamic and hydrostatic forces are considered insufficient to breach or erode the perimeter berm as designed. Predicted velocities during the 100-year flood will not be sufficient to carry materials from the parcel to neighboring and/or downstream properties. The perimeter berm is designed to withstand the hydrodynamic and hydrostatic forces of the 100-year flood and will further prevent material from being carried off-site onto other properties. Analysis of Section 4-109.C.4 The proposed use of the parcel as a gravel mining and extraction site is pending approval of a Land Use Change application by Garfield County and the adequacy of proposed uses are addressed in that application. Adjacent properties have similar uses that seem to be compatible with this development. Future development of adjacent properties with more restrictive uses is unlikely due to floodplain inundation in the vicinity. Analysis of Section 4-109.C.5 Access to the parcel from County Road 346 (CR-346) is to be developed according to CDOT Access Permit #320024, included as Attachment D. The proposed access point from CR 346 is outside of the modeled floodplain. Analysis of Section 4-109.C.6 Neither the existing nor proposed condition of the parcel will have public utilities, paved streets, bridges, or any other government services that will require repair after a flood event. On-site drinking water will be delivered, and sewerage will be collected in a vault- and-haul type of system and pumped regularly by a contracted service. Analysis of Section 4-109.C.7 The average water velocity at the site during the 100-year flood is expected to be 2.7-fps with a depth of 3.2-feet and shear stress of 0.6-psf (see Table 2 in Attachment B). Analysis of Section 4-109.C.8 Does not apply as the Parcel is not a waterfront location. Analysis of Section 4-109.C.9 There is no alternative location for mining and gravel extraction on the Parcel. The operations pad and scale-house/office are shown to be located outside of the floodplain. Analysis of Section 4-109.C.10 The parcel is located within a Residential Medium High (Res MH) area and adjacent to the Urban Growth Area for Silt, CO, according to the Garfield County 2030 Comprehensive Plan. The Res MH areas in the county are expected to be developed at a density of between 1 dwelling unit (du) per 6 acres and 1 du per 2 acres; however, due to the area around the project site being within the designated 100 -year floodplain (as shown on the future land use map) it is unlikely to be developed with residential uses. The proposed development of the parcel does not include any housing or dwelling units as the parcel will be used for gravel mining and extraction. Pending approval of the Land Use Change Revised Floodplain Development Permit Narrative for Rifle Pit #1 August 2022 5 application by Garfield County, the proposed development and use of the parcel will be coherent with the County’s zoning designation. 5.3 Section 4-201 Application Materials Scott has developed all required materials of a Floodplain Development Permit submittal for the proposed Rifle Pit #1 Project as Attachments A-E. 5.4 Section 4-203.O Floodplain Analysis The extent of the 100-year floodplain and floodway are clearly labeled in Attachment A. The area designated for a potential office/scale-house site, fuel storage, and other operational appurtenances labeled “Operations Area” is outside of the modeled 100-year floodplain. Watercourses and natural drainage on the Parcel will be altered by placement of the perimeter berm to prevent floodwaters from entering the Project area, as well as to prevent any material or sediment from leaving the site with storm runoff. An engineering report is included as Attachment B which certifies that the perimeter berm or any other proposed activity associated with the Project will not raise the BFE. The changes to drainage on the parcel will not negatively impact neighboring properties because the perimeter berm will prevent stormwater runoff from leaving the parcel. The wet-mining process will minimally impact the equilibrium of the water table due to evaporation and pumping water for dust suppression on-site. The Project will not result in any direct impacts to wetlands or Waters of the US as proposed (see Attachment A for extents and quantities of disturbance). 6.0 Analysis of LUDC Article 7 6.1 Section 7-203.A Minimum Setback This code section identifies the datum for the 35-foot setback to be the Typical and Ordinary High-Water Mark (TOWHM), which is not readily identifiable for wetland areas, so the proposed Project was developed assuming the extent of wetlands as being the setback datum. The wetlands on the Parcel were exhaustively studied and a detailed wetland boundary was determined by SGM though vegetation surveys and soil studies and documented in a USACE Aquatic Resource Delineation Report and Boundary Confirmation Request (Attachment E; note this report has been submitted to the US Army Corps of Engineers and is currently under review). Scott is requesting a variance from the 35-foot setback requirement for protection of water bodies and instead proposes a setback of 25-feet from the extent of wetlands. The perimeter berm, detailed in Attachment A, will be constructed outside of this 25-foot boundary and will provide a physical barrier to any wetland disturbance, given that the proposed berm has an overall width of at least 25-feet. Any mining activities associated with the Project will be effectively no less than 50 feet from any wetland areas on the parcel. 6.2 Section 7-203.B Structures Permitted in Setback The perimeter berm is a flood control structure that will be placed inside the 35-foot setback. See Attachment A for detail drawings of the proposed perimeter berm. Revised Floodplain Development Permit Narrative for Rifle Pit #1 August 2022 6 6.3 Section 7-203.C Structures and Activity Prohibited in Setback No disturbance, other than construction of the perimeter berm (which is a flood control structure), is proposed within the 35-foot setback. 6.4 Section 7-203.D Compliance with State and Federal Laws The Project was developed to comply with all applicable state and federal laws and avoids all disturbance and direct impacts to wetland areas and Waters of the US. The US Army Corps of Engineers has been consulted as part of the planning phase of the Project. A permit application was submitted to the Colorado Division of Reclamation and Mine Safety (DRMS) on 04/18/22. Evaporation water losses resulting from the exposure of groundwater during gravel mining will be augmented in a Substitute Water Supply Plan approved by the Colorado Division of Water Resources (DWR) State Engineer’s Office (SEO) and can be provided to the County at their request. 7.0 Engineer’s Contact Information If you have any questions regarding the materials submitted with the Floodplain Development Permit Application for the Rifle Pit #1 project, contact Chip Fisher at (303) 746-2549 and chipf@sgm-inc.com. Sincerely, Richard (Chip) Fisher, P.E. Revised Floodplain Development Permit Narrative for Rifle Pit #1 August 2022 A Attachment A Engineering Drawings © 2022 Microsoft Corporation © 2022 Maxar ©CNES (2022) Distribution Airbus DS © 2022 TomTom Revision#Dwg No.Job No.Drawn by:Date:File:PE:QC:Date By: Project Milestone:Of :2019-341.002RPF08/11/2022RPFRiflePit-AdminABF1118 West Sixth Street, Suite 200Glenwood Springs, CO 81601970.945.1004 www.sgm-inc.com Scope of Work 118 West Sixth Street, Suite 200Glenwood Springs, CO 81601970.945.1004 www.sgm-inc.com Project SiteProject ContactsChris HurleyIHC-Scott, Inc. dba Scott Contracting, Inc.Chris Hurley (Legal Counsel)Permit Set (Not For Construction)August 20229200 East Mineral AveSuite #400Centennial, CO 80112Sheet IndexVicinity MapProject Engineerchurley@ihcscott.com (720) 889-4402Richard (Chip) Fisher, P.E. 57906IHC-Scott, Inc. dba Scott Contracting, Inc. 13Permit Set (Not For Construction)Rifle Pit Gravel Pit #1Title:IHC-Scott, Inc. dba Scott Contracting, Inc.Cover SheetRifle Pit Gravel Pit #1Tony Robertstroberts@ihcscott.com(303) 790-9100Richard Fisher, P.E chipf@sgm-inc.com (970) 384-9098Angie Fowler, P.E.angief@sgm-inc.com(970) 384-9027N.T.S.Alex Neesalexn@sgm-inc.com (970) 384-9004Town of SiltI-70I-70US-608/11/2022 Title:Revision#Dwg No.Job No.Drawn by:Date:File:PE:QC:Date By: Project Milestone:Of :2019-341.002RPFRPFRiflePit-NotesABF2118 West Sixth Street, Suite 200Glenwood Springs, CO 81601970.945.1004 www.sgm-inc.com IHC-Scott, Inc. dba Scott Contracting, Inc. 13Permit Set (Not For Construction)Notes & EarthworkQuantity EstimatesRifle Pit Gravel Pit #108/11/202208/11/2022