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HomeMy WebLinkAbout1.09 StandardsResponses to "Article 7: Standards" are below the applicable sections in blue. ARTICLE 7: STANDARDS The following standards apply to all proposed Land Use Changes, including divisions of land, unless elsewhere in this Code a use is explicitly exempt from one or more standards. 7-101. ZONE DISTRICT USE REGULATIONS. The Land Use Change shall comply with Article 3, Zoning, including any applicable zone district use restrictions and regulations. The proposed apartments are an allowed uses in the Commercial Limited zone district. 7-102. COMPREHENSIVE PLAN AND INTERGOVERNMENTAL AGREEMENTS. The Land Use Change is in general conformance with the Garfield County Comprehensive Plan and complies with any applicable intergovernmental agreement. The proposed apartments are in general conformance to the Comprehensive Plan since they are an allowed use in the Commercial Limited zone district. In meetings with staff, the City of Glenwood Springs has no comments either for or against the project. 7-103. COMPATIBILITY. The nature, scale, and intensity of the proposed use are compatible with adjacent land uses. The proposed apartments are compatible with adjacent land uses. Across the river is the airport, a church is to the north, a mobile home park is to the south with Holy Cross Energy complex past that, and a commercial area of stores and warehouses across Highway 82 to the east. An Adjacent Land Use map is provided in the application materials. 7-104. SOURCE OF WATER. All applications for Land Use Change Permits shall have an adequate, reliable, physical, long-term, and legal water supply to serve the use, except for land uses that do not require water, or that contain Temporary Facilities served by a licensed water hauler. A. BOCC Determination. The BOCC, pursuant to C.R.S. § 29-20-301, et seq., shall not approve an application for a Land Use Change Permit, including divisions of land, unless it determines in its sole discretion, after considering the application and all of the information provided, that the Applicant has satisfactorily demonstrated that the proposed water supply will be adequate. Nothing in this section shall be construed to require that the Applicant own or have acquired the proposed water supply or constructed the related infrastructure at the time of the application. B. Determination of Adequate Water. The BOCC's sole determination as to whether an Applicant has an Adequate Water Supply to meet the water supply requirements of a proposed development shall be based on consideration of the following information: 1. The documentation required by the Water Supply Plan per section 4-203.M.; 2. A letter from the State engineer commenting on the documentation provided in the Water Supply Plan per section 4-203.M.; 3. Whether the Applicant has paid to a Water Supply Entity a fee or charge for the purpose of acquiring water for or expanding or constructing the infrastructure to serve the proposed development; and 4. Any other information deemed relevant by the BOCC to determine, in its sole discretion, whether the water supply for the proposed development is adequate, including without limitation, any information required to be submitted by the Applicant pursuant to this Code or State statutes. The existing site is served by water from the City of Glenwood Springs municipal water system. The City has provided a "Will Serve" letter for the proposed apartments that is included in the application materials. 7-105. CENTRAL WATER DISTRIBUTION AND WASTEWATER SYSTEMS. A. Water Distribution Systems. The land use shall be served by a water distribution system that is adequate to serve the proposed use and density. 1. Where water service through a Water Supply Entity is not physically or economically feasible, a central well and distribution system is preferred over individual wells. 2. A Central Water Distribution System is required if: a. The property is located within 400 feet of a Central Water System, the system is available and adequate to serve the proposed development, and connection is practicable and feasible; or b. The residential development consists of 15 or more dwelling units. The existing site is served by water from the City of Glenwood Springs municipal water system. The City has provided a "Will Serve" letter for the proposed apartments that is included in the application materials. B. Wastewater Systems. The land use shall be served by a wastewater system that is adequate to serve the proposed use and density. 1. Every effort shall be made to secure a public sewer extension. Where connections to an existing public sewer are not physically or economically feasible, a central collection system and treatment plant is preferred. 2. A central wastewater system is required if a. The property is located within 400 feet of a Sewage Treatment Facility, the system is available and adequate to serve the proposed development, and connection is practicable and feasible. b. The property is not suitable for an OWTS. Septic systems are not permitted on parcels less than 1 acre in size. The existing site is served by a force main sanitary sewer by the City of Glenwood Springs. The City has provided a "Will Serve" letter for the proposed apartments that is included in the application materials. 7-106. PUBLIC UTILITIES. A. Adequate Public Utilities. Adequate Public Utilities shall be available to serve the land use. B. Approval of Utility Easement by Utility Company. Utility easements shall be subject to approval by the applicable utility companies and, where required, additional easements shall be provided for main switching stations and substations. The Applicant shall work with the utility companies to provide reasonably- sized easements in appropriate locations. C. Utility Location. Unless otherwise provided in this Code, the following conditions shall apply to the location of utility services. 1. Underground Location. All utilities except major power transmission lines, transformers, switching and terminal boxes, meter cabinets, and other appurtenant facilities shall be located underground throughout the development unless it is demonstrated to the satisfaction of the BOCC that compliance is impractical or not feasible and will result in undue hardship. 2. Easement Location. As applied to Subdivisions and Exemptions, all utility lines, including appurtenances, shall be placed either within roads or public rights-of-way. 3. Dimensional Requirements. a. Easements centered on common Rear Lot Lines shall be at least 16 feet wide. b. Where an easement abuts a Rear Lot Line that is not the Rear Lot Line of another lot, or that is on the perimeter of the development, the easement width shall be a minimum of 10 feet. c. Where inclusion of utilities within the Rear Lot Line is impractical due to topographical or other conditions, perpetual unobstructed easements at least 10 feet in width shall be provided alongside Lots Lines with satisfactory access to the road or Rear Lot Line. d. Where easements are combined with a water course, drainage way, channel, or stream and the use would be in conflict with drainage requirements or Wetlands, an additional utility easement of at least 10 feet in width shall be provided. e. Multiple use of an easement is encouraged to minimize the number of easements. D. Dedication of Easements. All utility easements shall be dedicated to the public. Drainage easement may be dedicated to either the public or to an HOA. E. Construction and Installation of Utilities. Applicants shall make the necessary arrangements with each service utility for the construction and installation of required utilities. Utilities shall be installed in a manner that avoids unnecessary removal of trees or excessive excavations, and shall be reasonably free from physical obstructions. F. Conflicting Encumbrances. Easements shall be free from conflicting legal encumbrances. The existing site is served by gas from SourceGas, power from Xcel Energy, phone from Century Link, and cable television from Comcast. All these services will remain for the proposed apartments. 7-107. ACCESS AND ROADWAYS. All roads shall be designed to provide for adequate and safe access and shall be reviewed by the County Engineer. A. Access to Public Right -of -Way. All lots and parcels shall have legal and physical access to a public right-of-way. B. Safe Access. Access to and from the use shall be safe and in conformance with applicable County, State, and Federal access regulations. Where the Land Use Change causes warrant(s) for improvements to State or Federal highways or County Roads, the developer shall be responsible for paying for those improvements. C. Adequate Capacity. Access serving the proposed use shall have the capacity to efficiently and safely service the additional traffic generated by the use. The use shall not cause traffic congestion or unsafe traffic conditions, impacts to the County, State, and Federal roadway system shall be mitigated through roadway improvements or impact fees, or both. D. Road Dedications. All rights-of-way shall be dedicated to the public and so designated on the Final Plat. They will not, however, be accepted as County roads unless the BOCC specifically designates and accepts them as such. E. Impacts Mitigated. Impacts to County roads associated with hauling, truck traffic, and equipment use shall be mitigated through roadway improvements or impact fees, or both. F. Design Standards. Roadways, surfaces, curbs and gutters, and sidewalks shall be provided as follows: system shall be mitigated through roadway improvements or impact fees, or both. D. Road Dedications. All rights-of-way shall be dedicated to the public and so designated on the Final Plat. They will not, however, be accepted as County roads unless the BOCC specifically designates and accepts them as such. E. Impacts Mitigated. Impacts to County roads associated with hauling, truck traffic, and equipment use shall be mitigated through roadway improvements or impact fees, or both. F. Design Standards. Roadways, surfaces, curbs and gutters, and sidewalks shall be provided as follows: The site has an existing access to South Grand Avenue. The access point will remain but will be improved. The access to the site will be 24' wide with curb and gutter and a 10% maximum grade. Internal circulation allows for emergency vehicle turning movements and internal sidewalks allow for pedestrian access with minimal vehicle conflicts. Drainage structures are designed to be integral with roadways. See Site Plan sheets for driveway profile and typical section that is included in the application materials. 7-108. USE OF LAND SUBJECT TO NATURAL HAZARDS. Land subject to identified Natural and Geologic Hazards, such as falling rock, landslides, snow slides, mud flows, radiation, flooding, or high water tables, shall not be developed unless it has been designed to eliminate or mitigate the potential effects of hazardous site conditions as designed by a qualified professional engineer and as approved by the County. The proposed project has been evaluated for natural hazards. See Hepworth-Pawlak Geotechnical report dated April 30, 2013 titled "Preliminary Geotechnical and Geological Review, Proposed Redevelopment, Buffalo Valley Property, 3637 Highway 82, Glenwood Springs, Colorado" 7-109. FIRE PROTECTION. A. Adequate Fire Protection. Adequate fire protection will be provided for each land use change as required by the appropriate fire protection district. B. Subdivisions. All divisions of land must be reviewed and approved by the appropriate fire protection district for adequate primary and secondary access, fire lanes, water sources for fire protection, fire hydrants, and maintenance provisions. The existing site is served by water from the City of Glenwood Springs municipal water system with an existing fire hydrant at the entrance. The existing hydrant will remain. Internal roads allow for emergency vehicle turning with an additional fire hydrant proposed. The City of Glenwood Springs will maintain the fire hydrants. The following resource protection standards apply to all proposed Land Use Changes, including divisions of land unless elsewhere in this Code a use is explicitly exempt from 1 or more standards. 7-201. AGRICULTURAL LANDS. A. No Adverse Affect to Agricultural Operations. Land Use Changes on lands adjacent to or directly affecting agricultural operations shall not adversely affect or otherwise limit the viability of existing agricultural operations. Proposed division and development of the land shall minimize the impacts of development on Agricultural Lands and agricultural operations, and maintain the opportunity for agricultural production. B. Domestic Animal Controls. Dogs and other domestic animals that are not being used to assist with the herding or the care of livestock shall not be permitted to interfere with livestock or the care of livestock on Agricultural Lands. The County shall require protective covenants or deed restrictions as necessary to control domestic animals. C. Fences. The County is a Right to Farm County consistent with section 1-301. Fences shall be constructed to separate the development from adjoining Agricultural Lands or stock drives as required to protect Agricultural Lands by any new development and to separate new development from adjoining agricultural operations. All parts of the fencing including such items as gates, cattle guards, boards, posts, and wiring shall be maintained by the owner, HOA, or other responsible entity. D. Roads. Roads shall be located a sufficient distance back from the property boundaries so that normal maintenance of roads, including snow removal, will not damage boundary fences. Dust control shall be required, both during and after construction, to minimize adverse impacts to livestock and crops. E. Irrigation Ditches. 1. Maintenance. Where irrigation ditches cross or adjoin the land proposed to be developed, the developer shall insure that the use of those ditches, including maintenance, can continue uninterrupted. 2. Rights -of -Way. The land use change shall not interfere with the ditch rights-of-way. 3. Maintenance Easement. A maintenance easement of at least 25 feet from the edges of the ditch banks shall be preserved and indicated on any Final Plat for the division of land or for the final development plan for any other land use. When agreed to in writing by the ditch owner(s), that distance may be decreased. Not Applicable. The proposed site is not adjacent to agricultural operations. 7-202. WILDLIFE HABITAT AREAS. The Applicant shall consult with the Colorado Division of Wildlife or a qualified wildlife biologist in determining how best to avoid or mitigate impacts to wildlife habitat areas. Methods may include, but are not limited to, 1 or more of the following: A. Buffers. Visual and sound buffers shall be created through effective use of topography, vegetation, and similar measures to screen structures and activity areas from habitat areas. B. Locational Controls of Land Disturbance. Land disturbance shall be located so that wildlife is not forced to use new migration corridors, and is not exposed to significantly increased predation, interaction with vehicles, intense human activity, or more severe topography or climate. C. Preservation of Native Vegetation. 1. Proposed Land Use Changes are designed to preserve large areas of vegetation utilized by wildlife for food and cover, based upon recommendations by the Colorado Division of Wildlife. 2. When native vegetation must be removed within habitat areas, it shall be replaced with native and/or desirable nonnative vegetation capable of supporting post -disturbance land use. 3. Vegetation removed to control noxious weeds is not required to be replaced unless the site requires revegetation to prevent other noxious weeds from becoming established. D. Habitat Compensation. Where disturbance of critical wildlife habitat cannot be avoided, the developer may be required to acquire and permanently protect existing habitat to compensate for habitat that is lost to development. E. Domestic Animal Controls. The County may require protective covenants or deed restrictions as necessary to control domestic animals by fencing or kenneling. A wavier for evaluation of Wildlife Habitat Areas is requested. The existing site contains motel and restaurant buildings with paved parking. An existing vegetated hillside of native scrub oak and grasses is along the east side. Any proposed disturbance to the site will be in areas that hold existing pavement and buildings. The native vegetation on the hillside is proposed to remain undisturbed. Since any wildlife habitat areas that would exist on site are most likely on the vegetated hillside that is proposed to remain undisturbed, a waiver for consulting the DOW or hiring a consultant is requested. 7-203. PROTECTION OF WATERBODIES. A. Minimum Setback. 1. A setback of 35 feet measured horizontally from the Typical and Ordinary High Water Mark (TOHWM) on each side of a Waterbody is required. 2. In the case of entrenched or incised streams, where the vertical distance from the bank exceeds 25 feet, all activities, except for those referenced in section 7-203.A.3, will adhere to a setback of 2.5 times the distance between the TOHWMs or 35 feet, whichever is less. 3. A minimum setback of 100 feet measured horizontally from the TOHWM shall be required for any storage of hazardous materials and sand and salt for use on roads. B. Structures Permitted In Setback. Irrigation and water diversion facilities, flood control structures, culverts, bridges, pipelines, and other reasonable and necessary structures requiring some disturbance within the 35 foot setback may be permitted. C. Structures and Activity Prohibited in Setback. Unless otherwise permitted or approved, the following activities and development shall be prohibited in the 35 foot setback: 1. Removal of any existing native vegetation or conducting any activity which will cause any loss of riparian area unless it involves the approved removal of noxious weeds, nonnative species, or dead or diseased trees. 2. Disturbance of existing natural surface drainage characteristics, sedimentation patterns, flow patterns, or flood retention characteristics by any means, including without limitation grading and alteration of existing topography. Measures taken to restore existing topography to improve drainage, flow patterns, and flood control must be approved. D. Compliance with State and Federal Laws. Any development impacting a Waterbody shall comply with all applicable state and federal laws, including, but not limited to, CDPHE water quality control division regulations and the Army Corp of Engineers regulations and permitting for waters of the U.S. The proposed site is 250' (+/-) away from the Roaring Fork River and on a bench above the River. No incised steams exist across the project. 7-204 DRAINAGE AND EROSION. A. Erosion and Sedimentation. Excluding Grading activities for agricultural purposes, development disturbing 1 acre or more is subject to the CDPHE National Pollutant Discharge Elimination System Permit, unless otherwise exempted by CDPHE. B. Drainage 1. Site Design to Facilitate Positive Drainage. Lots shall be laid out to provide positive drainage away from all buildings. 2. Coordination With Area Storm Drainage Pattern. Individual lot drainage shall be coordinated with the general storm drainage pattern for the area. a. Drainage ditches shall have a minimum Slope of no less than 0.75%. Energy dissipaters or retention ponds shall be installed in drainage ditches where flows are in excess of 5 feet per second. Ditches adjacent to roads shall have a maximum Slope of 3:1 on the inside and outside edges, except where there is a cut Slope on the outside edge, in which case the edge of the ditch shall be matched to the cut Slope. b. Subdrains shall be required for all foundations where possible and shall divert away from building foundations and daylight to proper drainage channels. c. Avoid Drainage to Adjacent Lots. Drainage shall be designed to avoid concentration of drainage from any lot to an adjacent lot. See the included Drainage report, Drainage Plan, and Stormwater Management Plan (SWMP). Since the proposed will disturb more than 1 acre, an application to the CDPHE for permitting is included in the SWMP. The CDPHE permit application will be completed and submitted prior to construction. C. Stormwater Run -Off. These standards shall apply to any new development within 100 feet of a Waterbody and to any other development creating 10,000 square feet or more of impervious surface area. 1. Avoid Direct Discharge to Streams or Other Waterbodies. Stormwater Runoff from project areas likely to contain pollutants shall be managed in a manner that provides for at least 1 of the following and is sufficient to prevent water quality degradation, disturbance to adjoining property, and degradation of public roads. a. Runoff to Vegetated Areas. Direct run-off to stable, vegetated areas capable of maintaining Sheetflow for infiltration. Vegetated receiving areas should be resistant to erosion from a design storm of 0.5 inches in 24 hours. b. On -Site Treatment. On-site treatment of stormwater prior to discharge to any natural Waterbody by use of best management practices designed to detain or infiltrate the Runoff and approved as part of the stormwater quality control plan prior to discharge to any natural Waterbody. c. Discharge to Stormwater Conveyance Structure. Discharge to a stormwater conveyance structure designed to accommodate the projected additional flows from the proposed project, with treatment by a regional or other stormwater treatment facility. 2. Minimize Directly -Connected Impervious Areas. The site design shall minimize the extent of directly - connected impervious areas by including the following requirements: a. Drainage Through Vegetated Pervious Buffer Strips. Runoff from developed impervious surfaces (rooftops, Parking Lots, sidewalks, etc.) shall drain over stable, vegetated pervious areas before reaching stormwater conveyance systems or discharging to Waterbodies. b. Techniques Used in Conjunction with Buffer Strip. The requirement that all impervious areas drain to vegetated pervious buffer strips may be reduced if the outflow from the vegetated pervious buffer strip is directed to other stormwater treatment methods. Examples of other potential techniques to be used in conjunction with vegetated pervious buffer strip are: infiltration devices, grass depressions, constructed Wetlands, sand filters, dry ponds, etc. c. Grass Buffer Strip Slope Design. When impervious surfaces drain onto grass buffer strips, a Slope of less than 10% is encouraged, unless an alternative design is approved by the County. 3. Detain and Treat Runoff. Permanent stormwater detention facilities are required to be designed to detain flows to historic peak discharge rates and to provide water quality benefits and maintained to ensure function. Design criteria for detention facilities include: a. Detention facilities shall ensure the post -development peak discharge rate does not exceed the pre - development peak discharge rate for the 2 -year and 25 -year return frequency, 24-hour duration storm. In determining Runoff rates, the entire area contributing Runoff shall be considered, including any existing off- site contribution. b. To minimize the threat of major property damage or loss of life, all permanent stormwater detention facilities must demonstrate that there is a safe passage of the 100 -year storm event without causing property damage. c. Channels downstream from the stormwater detention pond discharge shall be protected from increased channel scour, bank instability, and erosion and sedimentation from the 25 -year return frequency, 24-hour design storm. d. Removal of pollutants shall be accomplished by sizing dry detention basins to incorporate a 40 -hour emptying time for a design precipitation event of 0.5 inches in 24 hours, with no more than 50% of the water being released in 12 hours. If retention ponds are used, a 24-hour emptying time is required. For drainage from Parking Lots, vehicle maintenance facilities, or other areas with extensive vehicular use, a sand and oil grease trap or similar measures also may be required. To promote pollutant removal, detention basins length - to -width ratio should be not less than 2, with a ratio of 4 recommended where site constraints allow. A sedimentation "forebay" is recommended to promote long-term functioning of the structure. Access to both the forebay and pond by maintenance equipment is required. e. Culverts, drainage pipes, and bridges shall be designed and constructed in compliance with AASHTO recommendations for a water live load. Site runoff is directed through a system of conveyances to a detention pond. The detention pond is proposed to limit runoff to existing flowrates for the 2 -year and 25 -year storms. The detention pond will remove pollutants and release detained flows into a grass swale. See the included Drainage report, Drainage Plan, and Stormwater Management Plan (SWMP). 7-205. ENVIRONMENTAL QUALITY. A. Air Quality. Any Land Use Change shall not cause air quality to be reduced below acceptable levels established by the Colorado Air Pollution Control Division. B. Water Quality. At a minimum, all hazardous materials shall be stored and used in compliance with applicable State and Federal hazardous materials regulations. The Stormwater Management Plan (SWMP) addresses storage of hazardous materials during construction. The management of the apartments will store materials in compliance with regulations although very little hazardous materials will be stored on site; anticipated small amounts used for property maintenance of weed control, pest control, paints, and/or fuels for maintenance equipment. Air quality will likely only be affected by dust during construction. Dust control will be mitigated by watering and the project will not reach the threshold for an APEN permit. 7-206. WILDFIRE HAZARDS. The following standards apply to areas subject to wildfire hazards as identified on the County Wildfire Susceptibility Index Map as indicated in the County's Community Wildfire Protection Plan. A. Location Restrictions. Development associated with the land use change shall not be located in any area designated as a severe wildfire Hazard Area with Slopes greater than 30% or within a fire chimney as identified by the Colorado State Forest Service. B. Development Does Not Increase Potential Hazard. The proposed Land Use Change shall be developed in a manner that does not increase the potential intensity or duration of a wildfire, or adversely affect wildfire behavior or fuel composition. C. Roof Materials and Design. Roof materials shall be made of noncombustible materials or other materials as recommended by the local fire agency. The project is in an area of low Wildfire Hazard. A map showing Wildfire Hazard is included. 7-207. NATURAL AND GEOLOGIC HAZARDS. A. Utilities. Above -ground utility facilities located in Hazard Areas shall be protected by barriers or diversion techniques approved by a qualified professional engineer. The determination to locate utility facilities above ground shall be based upon the recommendation and requirements of the utility service provider and approved by the County. The proposed project has been evaluated for natural hazards. See Hepworth-Pawlak Geotechnical report dated April 30, 2013 titled "Preliminary Geotechnical and Geological Review, Proposed Redevelopment, Buffalo Valley Property, 3637 Highway 82, Glenwood Springs, Colorado". Utilities will not be affected. B. Development in Avalanche Hazard Areas. Development may be permitted to occur in Avalanche Hazard Areas if the development complies with the following minimum requirements and standards, as certified by a qualified professional engineer, or qualified professional geologist, and the plan approved by the County. 1. Building construction shall be certified to withstand avalanche impact and static loads and otherwise protected by external avalanche -defense structures that have been similarly certified. 2. Driveways and Subdivision roads shall avoid areas where avalanches have return periods of fewer than 10 years. 3. Clear -cutting or other large-scale removal of vegetation is prohibited in avalanche path starting zones, or in other locations that can increase the potential avalanche hazard on the property. 4. Extractive operations in Avalanche Hazard Areas are prohibited when snow is on the ground unless a program of avalanche control and defense measures has been approved by the County to protect the operation. The proposed project has been evaluated for natural hazards. See Hepworth-Pawlak Geotechnical report dated April 30, 2013 titled "Preliminary Geotechnical and Geological Review, Proposed Redevelopment, Buffalo Valley Property, 3637 Highway 82, Glenwood Springs, Colorado" C. Development in Landslide Hazard Areas. Development may be permitted to occur in Landslide Hazard Areas only if the development complies with the following minimum requirements and standards, as certified by a qualified professional engineer, or qualified professional geologist, and as approved by the County. 1. Development shall comply with recommended construction practices to artificially stabilize, support, buttress, or retain the potential slide area and to control surface and subsurface drainage that affects the slide area. 2. The following development activities shall be prohibited in Landslide Hazard Areas: a. Activities that add water or weight to the top of the Slope, or along the length of the Slope, or otherwise decrease the stability of the Hazard Area. Measures and structural improvements to permanently control surface and subsurface drainage from the development shall be required. b. Activities that remove vegetation or other natural support material that contributes to its stability. c. Activities that increase the steepness of a potentially unstable Slope. d. Activities that remove the toe of the landslide, unless adequate mechanical support is provided. The proposed project has been evaluated for natural hazards. See Hepworth-Pawlak Geotechnical report dated April 30, 2013 titled "Preliminary Geotechnical and Geological Review, Proposed Redevelopment, Buffalo Valley Property, 3637 Highway 82, Glenwood Springs, Colorado" D. Development in Rockfall Hazard Areas. Development shall be permitted to occur in rockfall Hazard Areas only if the Applicant demonstrates that the development cannot avoid such areas and the development complies with the following minimum requirements and standards, as certified by a qualified professional engineer, or a qualified professional geologist, and as approved by the County. 1. Development shall comply with recommended construction practices to minimize the degree of hazard. Construction practices may include: a. Stabilizing rocks by bolting, gunite application (cementing), removal of unstable rocks (scaling), cribbing, or installation of retaining walls. b. Slowing or diverting moving rocks with rock fences, screening, channeling, damming, or constructing concrete barriers or covered galleries. c. Installation of structural barriers around vulnerable structures to prevent rock impact. 2. The following development activities shall be prohibited in rockfall Hazard Areas: a. Activities that add water or weight to, or otherwise decrease the stability of, cliffs or overhanging strata. b. Activities that will reduce stability, including activities that remove vegetation or other natural support material, or that require excavation, or cause erosion that will remove underlying support to a rockfall Hazard Area. The proposed project has been evaluated for natural hazards. See Hepworth-Pawlak Geotechnical report dated April 30, 2013 titled "Preliminary Geotechnical and Geological Review, Proposed Redevelopment, Buffalo Valley Property, 3637 Highway 82, Glenwood Springs, Colorado" E. Development in Alluvial Fan Hazard Area. Development shall only be permitted to occur in an alluvial fan if the Applicant demonstrates that the development cannot avoid such areas, and the development complies with the following minimum requirements and standards, as certified by a qualified professional engineer, or qualified professional geologist, and as approved by the County: 1. Development shall be protected using structures or other measures on the uphill side that channel, dam, or divert the potential mud or debris flow. 2. Disturbance shall be prohibited in the drainage basin above an alluvial fan, unless an evaluation of the effect on Runoff and stability of the fan and on the ground water recharge area shows that disturbance is not substantial or can be successfully mitigated. The proposed project has been evaluated for natural hazards. See Hepworth-Pawlak Geotechnical report dated April 30, 2013 titled "Preliminary Geotechnical and Geological Review, Proposed Redevelopment, Buffalo Valley Property, 3637 Highway 82, Glenwood Springs, Colorado" F. Slope Development. Development on Slopes 20% or greater shall only be permitted to occur if the Applicant demonstrates that the development complies with the following minimum requirements and standards, as certified by a qualified professional engineer, or qualified professional geologist, and as approved by the County: 1. Building lots with 20% or greater Slope shall require a special engineering study to establish the feasibility of development proposed for the site. The study shall address feasibility of construction required for the use and describe the mitigation measures to be used to overcome excessive Slope problems. 2. Development shall be permitted to occur on Slopes greater than 30% only if the Applicant demonstrates that the development cannot avoid such areas and the development complies with the following minimum requirements: a. Cutting, filling, and other Grading activities shall be confined to the minimum area necessary for construction. b. Development shall be located and designed to follow natural grade, rather than adjusting the site to fit the structure. Roads and driveways built to serve the development shall follow the contours of the natural terrain and, if feasible, shall be located behind existing landforms. 3. Development on Unstable or Potentially Unstable Slopes. If a site is identified as having moderate or extremely unstable Slopes, then development shall be permitted only if the Applicant demonstrates that the development cannot avoid such areas and the development complies with certified geotechnical design and construction stabilization and maintenance measures. a. Cutting into the Slope is prohibited without provision of adequate mechanical support. b. Adding water or weight to the top of the Slope, or along the length of the Slope, is prohibited. c. Vegetation shall not be removed from the Slope unless the integrity of the Slope can be adequately maintained. 4. Development on Talus Slopes. Development shall be permitted to occur on a Talus Slope only if the Applicant demonstrates that the development cannot avoid such areas, and the development complies with the following minimum requirements and standards, as certified by a qualified professional engineer, or a qualified professional geologist, and as approved by the County: a. The development shall be designed to withstand down Slope movement. b. The design shall include buried foundations and utilities below the active Talus Slope surface. c. Site disturbance shall be minimized to avoid inducing slope instability. d. The toe of a Talus Slope shall not be removed unless adequate mechanical support is provided. The proposed project has been evaluated for natural hazards. See Hepworth-Pawlak Geotechnical report dated April 30, 2013 titled "Preliminary Geotechnical and Geological Review, Proposed Redevelopment, Buffalo Valley Property, 3637 Highway 82, Glenwood Springs, Colorado". No development is proposed on slopes 20% or steeper. G. Development on Corrosive or Expansive Soils and Rock. Development in areas with corrosive or expansive soils and rock shall be designed based upon an evaluation of the development's effect on Slope stability and shrink -swell characteristics. Development shall be permitted only if the Applicant demonstrates that the development cannot avoid such areas and the development complies with design, construction stabilization, and maintenance measures certified by a qualified professional engineer, or qualified professional geologist, and is approved by the County. 1. Surface drainage shall be directed away from foundations. 2. Runoff from impervious surfaces shall be directed into natural drainages or otherwise on-site in a manner that does not create or increase adverse impacts to the development site or to adjacent or other property. The proposed project has been evaluated for natural hazards. See Hepworth-Pawlak Geotechnical report dated April 30, 2013 titled "Preliminary Geotechnical and Geological Review, Proposed Redevelopment, Buffalo Valley Property, 3637 Highway 82, Glenwood Springs, Colorado" H. Development in Mudflow Areas. Development shall be permitted in a mudflow area only if the Applicant demonstrates that the development cannot avoid such areas, and the development adequately employs, construction stabilization, and mitigation and maintenance measures as designed by a qualified professional engineer, or qualified professional geologist, and as approved by the County. The proposed project has been evaluated for natural hazards. See Hepworth-Pawlak Geotechnical report dated April 30, 2013 titled "Preliminary Geotechnical and Geological Review, Proposed Redevelopment, Buffalo Valley Property, 3637 Highway 82, Glenwood Springs, Colorado" 1. Development Over Faults. Development shall be permitted over faults only if the Applicant demonstrates that such areas cannot be avoided and the development complies with mitigation measures based on geotechnical analysis and recommendations, as certified by a qualified professional engineer, or qualified professional geologist, and approved by the County. The proposed project has been evaluated for natural hazards. See Hepworth-Pawlak Geotechnical report dated April 30, 2013 titled "Preliminary Geotechnical and Geological Review, Proposed Redevelopment, Buffalo Valley Property, 3637 Highway 82, Glenwood Springs, Colorado" 7-208. RECLAMATION. A. Applicability. These standards shall apply to any development that requires a Land Use Change Permit, including divisions of land, as well as to the following activities: 1. Installation of ISDS. Installation of a new or replacement ISDS. 2. Driveway Construction. Any driveway construction that requires a Garfield County Access Permit or a CDOT Access Permit. 3. Preparation Area. All areas disturbed during development that do not comprise the longer-term functional areas of the site but are those areas used for the short-term preparation of the site. B. Reclamation of Disturbed Areas. Areas disturbed during development shall be restored as natural -appearing landforms that blend in with adjacent undisturbed topography. 1. Contouring and Revegetation. Abrupt angular transitions and linear placement on visible Slopes shall be avoided. Areas disturbed by Grading shall be contoured so they can be revegetated, and shall be planted and have vegetation established and growing based on 70% coverage as compared with the original on-site vegetation within 2 growing seasons, using species with a diversity of native and/or desirable nonnative vegetation capable of supporting the post -disturbance land use. To the maximum extent feasible, disturbed areas shall be revegetated to a desired plant community with composition of weed -free species and plant cover typical to that site. 2. Application of Top Soil. Top soil shall be stockpiled and placed on disturbed areas. 3. Retaining Walls. Retaining walls made of wood, stone, vegetation, or other materials that blend with the natural landscape shall be used to reduce the steepness of cut Slopes and to provide planting pockets conducive to revegetation. 4. Slash Around Homes. To avoid insects, diseases, and wildfire hazards, all vegetative residue, branches, limbs, stumps, roots, or other such flammable lot -clearing debris shall be removed from all areas of the lot in which such materials are generated or deposited, prior to final building inspection approval. 5. Removal of Debris. Within 6 months of substantial completion of soil disturbance, all brush, stumps, and other debris shall be removed from the site. 6. Time Line Plan. Every area disturbed shall have a time line approved for the reclamation of the site. The proposed project will be graded per the Grading Plan and will be revegetated per the Landscape plan that is included in the application materials. These standards apply to all residential uses, excluding single-family, commercial and industrial uses, and divisions of land unless elsewhere in this Code a use is explicitly exempt from 1 or more standards. 7-301. COMPATIBLE DESIGN. The design of development associated with the land use change shall be compatible with the existing character of adjacent uses. A. Site Organization. The site shall be organized in a way that considers the relationship to streets and lots, solar access, parking, pedestrian access, and access to common areas. B. Operational Characteristics. The operations of activities on the site shall be managed to avoid nuisances to adjacent uses relating to hours of operations, parking, service delivery, and location of service areas and docks. 1. Dust, odors, gas, fumes, and glare shall not be emitted at levels that are reasonably objectionable to adjacent property. 2. Noise shall not exceed State noise standards pursuant to C.R.S., Article 12 of Title 25, unless the use is regulated by the COGCC. In this case, the use shall be subject to COGCC Rules regarding noise abatement. 3. Hours of operation shall be established to minimize impacts to adjacent land uses. C. Buffering. Buffering shall be installed to mitigate visual, noise, or similar impacts to adjacent property whenever adjacent uses are in a different zone district. D. Materials. Exterior facades shall be constructed with materials that do not detract from adjacent buildings or uses. The proposed project will be compatible with adjacent land uses. The organization provides logical circulation for vehicles and pedestrians. No noises, odors, or hours of operation are applicable with apartments so buffering is not necessary, although landscaping is proposed per the attached landscape plan. Building materials are architecturally selected and renderings of anticipated exterior finishes are attached. 7-302. OFF-STREET PARKING AND LOADING STANDARDS. A. Off -Street Parking Required. All land uses shall be required to provide the number of off-street parking spaces set forth in Table 7-302.A. Any use not specifically listed in Table 7-302.A. shall be determined by the Director. 1. A parking or loading space that is required by this Code shall not be a required parking or loading space for another use unless it can be shown that the shared use will not result in a shortage of parking at any time. Use of approved shared parking or loading spaces, based upon the following conditions, may reduce the number of off-street parking spaces by up to 20% of the total required for all uses. a. The peak use periods for the required parking or loading space will not overlap with one another. b. The shared use arrangement for parking or loading spaces shall be for 2 or more uses located on the same site or adjoining sites. 2. When any calculation of the number of required off-street parking spaces results in a fractional space being required, such fraction shall be rounded up to the next higher number of spaces. B. Off -Street Loading Required. Buildings or structures that are designed or that are substantially altered so as to receive and distribute materials and merchandise by truck shall provide and maintain off-street loading spaces in sufficient number to meet their need. Where the property or use is served or designed to be served by tractor -trailer delivery vehicles, the standards in Table 7-302.B. shall be used in establishing the minimum number of off-street loading berths required. C. Continuing Obligation. The provision and maintenance of off-street parking and loading spaces that comply with this Code shall be a continuing obligation of the property owner. D. Location of Required Parking Spaces. Required off-street parking spaces shall be located on the same lot or the adjacent lot proximate to the business they are intended to serve. E. Loading and Unloading. Loading and unloading of vehicles serving commercial and industrial uses shall be conducted in a manner that does not interfere with the proper flow of traffic. F. Parking and Loading Area Surface. 1. Surface Materials. Off-street parking areas, loading areas, aisles, and access drives shall have a durable, all-weather surface made of materials that are suitable for the uses to which the parking area will be put. 2. Grading and Drainage. Parking and loading surfaces shall be design by an engineer to ensure proper drainage off surface and stormwater. 3. Striping. Paved surfaces shall be striped to demarcate the parking spaces for all commercial lots and for residential lots containing over 4 contiguous spaces. G. Minimum Dimensions of Parking Areas. The minimum dimensions of parking spaces, aisles, and back-up areas are specified in Figure 7-302. The length of a parking space may be reduced to 18 feet, including wheel stop, if an additional area of 2 feet in length is provided for the front overhang of the car, provided that the overhang shall not reduce the width of the adjacent walkway to less than 4 feet. H. Compact Car Spaces. In parking areas containing more than 10 spaces, up to 20% of the number of spaces over the first 10 spaces may be designed and designated for compact cars. 1. Minimum Dimensions. A compact car space shall have minimum dimensions of 8 feet in width by 16 feet in length. 2. Signage. Compact car spaces shall be designated for exclusive use by compact cars and identified by stencil signage or a raised identification sign not to exceed dimensions. I. Minimum Dimensions of Loading Berths. The minimum dimension of any loading berth shall be 10 feet wide by 35 feet long, with a vertical clearance of 14 feet. If the typical size of vehicles used in connection with the proposed use exceeds these standards, the dimensions of these berths shall be increased. J. Handicapped or Accessible Parking. Accessible parking shall comply with the County's construction codes and the adopted or most recent edition of CABO/ICC ANSI A 117.1. K. Unobstructed Access. Each required parking space shall have unobstructed access from a road or Alley, or from an aisle or drive connecting with a road or Alley, except for approved residential tandem parking. L. Tandem Parking. Tandem parking (a vehicle parking directly behind another) that meets the following conditions may be applied to meet the off-street parking standards of this Code: 1. The space does not impede the movement of other vehicles on the site; 2. Tandem spaces serving multi -family dwelling units are assigned to the same dwelling unit; and 3. Valet parking shall be provided for tandem spaces serving commercial uses. M. Backing Onto Public Streets Prohibited. All parking areas shall be located and designed in conjunction with a driveway so that vehicles exiting from a parking space shall not be required to back onto a public road. Vehicles exiting from a parking space for a single-family or duplex dwelling unit may back onto a residential street. Vehicles exiting from a parking space for any use may back onto the right-of-way of an Alley adjacent to the property. N. Access Driveways. Access driveways for required off-street parking areas shall be designed and constructed to facilitate the flow of traffic, provide maximum safety of traffic access and egress, and the maximum safety of pedestrian and vehicular traffic on the site. 1. Minimum Width. a. The minimum width of the access driveway for a commercial or industrial use shall be 12 feet for a 1 -way drive and 24 feet for a 2 -way drive. b. The access driveway for a residential use shall be 10 feet for a 1 -way drive and 20 feet for a 2 -way drive. 2. Clear Vision Area. Access driveways shall have a minimum clear vision area as described and illustrated in section 7-303.1. O. Parking and Loading Area Landscaping and Illumination. Off-street parking and loading areas for nonresidential uses located adjacent to residential uses or Residential Zoning Districts shall be landscaped to minimize disturbance to residents, including installation of perimeter landscaping, proper screening of loading areas with opaque materials, and control of illumination. The parking lot is designed to have 26' for two-way traffic in parking areas with an access driveway of 24'. 100 total parking stalls are provided: 91 regular stalls 18' by 9' and 9 compact stalls 16'x8'. All stalls have 2' of overhang available with any adjacent sidewalk proposed as 6' in width. A waiver is requested from the number of parking stalls. See the attached letter. 7-303. LANDSCAPING STANDARDS. These standards apply to all residential uses, excluding single-family and ADUs, public/institutional uses, commercials uses, as well as residential or commercial Subdivisions and PUDs, and Rural Land Development Exemptions. A. General Standards. 1. All portions of the site where existing vegetative cover is damaged or removed, that are not otherwise covered with new improvements, shall be successfully revegetated with a mix of native, adaptive, and drought -tolerant grasses, ground covers, trees and shrubs. The density of the re-established vegetation must be adequate to prevent soil erosion and invasion of weeds after 1 growing season. 2. Landscaping shall not obstruct fire hydrants or utility boxes and shall be installed so it will not grow into any overhead utility lines. Trees and shrubs shall not be planted within 4 feet of existing overhead or underground lines B. Multi -Family Development. Lots in a Residential Zone District that contain multi -family dwellings shall be landscaped in the areas not covered by impervious materials. C. Subdivision, PUD, and Rural Land Development Exemption. Landscaping in a residential Subdivision, Planned Unit Development, or Rural Land Development Exemption shall be consistent with the character of the development, the unique ecosystem, and specific environment in which the development is located. D. Plants Compatible with Local Conditions. All plants used for landscaping shall be compatible with the local climate and the soils, drainage, and water conditions of the site. When planting occurs on hillsides, Slopes, drainage ways, or similar natural areas, plant material should duplicate adjacent plant communities both in species composition and special distribution patterns. Whenever possible, drought -resistant varieties of plant materials shall be utilized. Xeriscape design principles and the use of native plant species shall be used when appropriate. E. Existing Vegetation. Healthy trees, native vegetation, natural or significant rock outcroppings, and other valuable features shall be preserved and integrated within planting areas. F. Minimum Size. To ensure healthy plant materials are installed in new development, trees and shrubs shall comply with the quality standards of the Colorado Nursery Act, 1973 C.R.S. Title 35, Article 26. 3. Deciduous Trees. Deciduous trees shall be a minimum of 1-1/2 inches in caliper, measured at a point 4 inches above the ground. 4. Coniferous Trees. Coniferous trees shall be a minimum of 4 feet in height, measured from the top of the root ball to the top of the tree. 5. Ornamental Trees. Ornamental trees shall be a minimum of 1-1/2 inches in caliper, measured at a point 4 inches above the ground. 6. Shrubs and Vines. Shrubs shall be a minimum of 1 foot in height at time of planting. Vines shall be in a minimum 1 gallon container. G. Minimum Number of Trees and Shrubs. Trees and shrubs must be grouped in strategic areas and not spread thinly around the site. Where screening is required, plant materials must be sufficient to create a semi-opaque wall of plant material between the property and the adjoining area to be screened. H. Parking and Storage Prohibited. Areas required as landscaping shall not be used for parking, outdoor storage, and similar uses, but may be used for snow storage if designed in compliance with section 7-305, Snow Storage Standards. I. Clear Vision Area. A Clear Vision Area is the area formed by the intersection of the driveway centerline road right-of-way, the other road right-of-way line, and a straight line joining said lines through points 20 feet from their intersection as illustrated in Figure 7-303.A. Within a Clear Vision Area, plant materials shall be limited to 30 inches in height to avoid visibility obstructions or blind corners at intersections as illustrated in Figure 7-303.B. J. Landscaping Within Off -Street Parking Areas. 1. All off-street parking areas containing 15 or more spaces shall provide landscape buffers when adjacent to a public road. Landscape buffers may be achieved through the use of earthen berms, shrubs, trees, or other appropriate materials to effectively screen the parking area from the right-of-way. 2. Interior Parking Areas. Planting shall be established to break up the interior of all parking areas. Landscape planting islands shall be a minimum of 8 feet in width, as shown in Figure 7-303.C, to ensure adequate room for planting. The proposed project will be landscaped per the included Landscape plan. 7-304. LIGHTING STANDARDS. Any exterior lighting shall meet the following conditions: A. Downcast Lighting. Exterior lighting shall be designed so that light is directed inward, towards the interior of the Subdivision or site. B. Shielded Lighting. Exterior lighting shall be fully shielded or arranged in a manner so that concentrated rays of light will not shine directly onto other properties. C. Hazardous Lighting. The direct or reflected light from any light source shall not create a traffic hazard. Colored lights shall not be used in such a way as to be confused or construed as traffic control devices. D. Flashing Lights. Blinking, flashing, or fluttering lights, or other illuminated device that has a changing light intensity, brightness, or color, shall be prohibited in all zone districts. E. Height Limitations. Light sources which exceed 40 feet in height shall not be permitted except for temporary holiday displays or as required by local, State or Federal regulations. Lighting will comply with the above standards. 7-305. SNOW STORAGE STANDARDS. The following standards apply on any property that contains commercial or industrial uses, multi -family residential, or that have a common outdoor parking area: A. Minimum Area. A designated area sufficient to store snow from the entire parking area shall be provided. As a general guideline, and considering the varying elevations and snowfall amounts throughout the County, it is anticipated that a minimum area equivalent to 2.5% of the total area of the required off-street parking and loading area, including access drives, shall be designated to serve as a snow storage area. B. Storage in Parking Spaces Prohibited. Required off-street parking and loading areas shall not be used for snow storage. C. Storage in Yards and Open Space Permitted. Snow stored in a yard or Open Space shall not be located in a manner that restricts access or circulation, or obstructs the view of motorists. D. Storage on Public Roadways Prohibited. Public roads shall not be used for snow storage. E. Drainage. Adequate drainage shall be provided for the snow storage area to accommodate snowmelt and to ensure it does not drain onto adjacent property. Snow storage is provided between the eastern parking area and the east property line. Additional snow storage areas are available throughout the parking areas in various islands and yard areas. 7-306. TRAIL AND WALKWAY STANDARDS. A. Recreational and Community Facility Access. A multi -modal connection, such as a trail or sidewalk, shall be provided in a development where links to schools, shopping areas, parks, trails, greenbelts, and other public facilities are feasible. 1. Trail Dedication Standards. Trail rights-of-way for dedicated park lands and Open Space shall conform to the following criteria: a. The land required for trails or walkways shall be set aside as an easement or separate fee interest. b. All easements for trails and walkways will be dedicated to the public. c. The width of the easement shall be adequate to handle the proposed use based on the particular reasonable needs of the trail, its location, the surrounding terrain, and the anticipated usage. The minimum width for the trail easement shall be 8 feet. d. Public access to the trail shall be provided within the subject property. e. Any easement may overlap and include property previously included in other easements, such as ditch, canal, utility and Conservation Easements, and public or private open space. However, the trail easement shall not compromise the functional use of any other easement. B. Safety. Special structures and/or traffic control devices may be required at road crossings to avoid unsafe road crossings. C. Maintenance. Suitable provisions for maintenance of trail and walkway systems shall be established through a perpetual association, corporation, or other means acceptable to the County. No connections to offsite trails or sidewalks are proposed. Drainage Report for: Buffalo Valley, GARFIELD COUNTY, CO Prepared for: Partners III, LLC 353 Goose Lane Carbondale, CO 81623 Prepared by: Date: July, 2013 MOUNTAIN CROSS ENGINEERING, INC. Civil and Environmental Consulting and Design 826 1/2 Grand Avenue Glenwood Springs, CO 81601 ph 970.945.5544 fx 970.945.5558 www.mountaincross-eng.com MOUNTAIN CROSS ENGINEERING, INC. Civil and Environmental Consulting and Design 826 '/2 Grand Avenue, Glenwood Springs, CO 81601 P: 970.945.5544 F: 970.945.5558 www.mountaincross-eng.com TABLE OF CONTENTS Drainage Report Page 1-5 Aerial Image & Vicinity Map. Figure 1 Existing Basins & Time of Concentration Figure 2 Proposed Basins & Time of Concentration . Figure 3 Offsite Basin & Time of Concentration Figure 4 Sheet 3 - Drainage & Grading Plan 24"x36" . Under Separate Cover Sheet 5 - Details 24"x36" Under Separate Cover Report Calculations Appendix Drainage Report Buffalo Valley July, 2013 Purpose and Scope of Report This study evaluates Buffalo Valley from a storm water management perspective. It supplies data, calculations, and design criteria that will be used to mitigate the site concerning storm runoff and erosion control. Runoff from snowmelt is typically very large in volume but because it happens over a much longer time period, the peak flows are generally much less than a rainfall event. Therefore storm water is defined in this study to be surface water that is a direct result from a rainfall event. Storm water management in this study is concerned with managing the quantity of water expected from the site in accordance with typical engineering and hydrologic practices as well as protecting site discharge by means of best management practices for erosion control. All flows are listed in units of cubic feet per second (cfs) unless otherwise noted. This study will provide a project overview, a brief description of the methodology, a discussion of the analysis performed, a description of the erosion control anticipated for the site, and the results of the analysis. Project Overview The project is a redevelopment of the Buffalo Valley site in Garfield County, Colorado. The existing site has a restaurant and motel with parking and infrastructure and is located at 3637 Highway 82. Proposed plans are the construction of site construction to contain two buildings that have a total of 56 apartments. The project elevation is approximately 5880 feet above sea level and located at Latitude 39°30'19.1" North and Longitude 107°18'24.1" West. The property area is approximately 2.204± acres and the approximate area of disturbance due to construction activities is approximately 2.01± acres. Storm water will drain into the Roaring Fork River through a series of ditches and culverts approximately 250' to the east. It is the intent of this Drainage Plan to: 1) Convey the captured runoff flows through the project site, 2) Provide detention sufficient enough that runoff from the proposed site does not exceed the calculated flows for the existing condition, and 3) Reduce the pollutants in stormwater discharges from erosion associated with construction activity. Methodology The design of a storm water management plan begins with a calculation of the volume of water that will be produced from a rainfall event. The SCS TR -55 method was used for estimating the amount of runoff that will occur from larger basins. This method calculates runoff from SCS curve number, basin area, precipitation, and time of concentration. MOUNTAIN CROSS ENGINEERING, INC. Civil and Environmental Consulting and Design 826 % Grand Avenue, Glenwood Springs, CO 81601 P: 970.945.5544 F: 970.945.5558 www.mountaincross-eng.com 1 Drainage Report Buffalo Valley July, 2013 SCS Curve Number A curve number is assigned to a basin that gives a relationship between the amount of precipitation that becomes surface water and the amount of water that is lost to infiltration, evaporation, or transpiration. The SCS curve number is a function of soil type, vegetative-cover/land-use, and antecedent moisture conditions. Because the land -use and the soil types vary through the drainage basin, a composite curve number is assigned based on the weight of the area and its respective curve number. Basin Area Drainage basins have the characteristic that any precipitation falling within that area will drain to the same point of discharge. Basins were delineated from project topographic maps. Precipitation Extreme runoff events from urban areas in western Colorado are caused by cloudburst type storms that are characterized by short periods of high intensity rainfall. The SCS Type II 24-hour distribution reflects this and was used for this study. Estimating rainfall for engineering applications is based on the probability of the magnitude of a storm occurring within a return period. Volume III of the NOAA Atlas 2 maps for Colorado was used for defining design storm rainfall depths. The NOAA Atlas Maps are attached in the Appendix. Time of Concentration Manning's kinematic flow equation was used to estimate flow velocity. Length and velocity of flow are used to calculate time. Three flow elements are used: overland - flow, collector -channel flow, and main -channel flow. The parameters needed to determine the flow elements include length, slope, Manning's "n" value, and channel shape. These parameters were determined from topography. For smaller basins, the Rational Method was used to estimate the amount of runoff that will occur. This method calculates runoff (Q) in cubic feet per second (cfs) from basin area (A) in acres, runoff coefficient (C), and rainfall intensity (I) in inches per hour: Q=C*I*A When acres and inches per hour are used as the units, the conversion into cubic feet per second is 1.008 but is usually ignored and it has been in this report. The runoff coefficient is a dimensionless coefficient. Basin Area Drainage basins have the characteristic that any precipitation falling within that area will drain to the same point of discharge. The project basins were delineated from project topography, project site plan, and building architecture. MOUNTAIN CROSS ENGINEERING, INC. Civil and Environmental Consulting and Design 826 % Grand Avenue, Glenwood Springs, CO 81601 P: 970.945.5544 F: 970.945.5558 www.mountaincross-eng.com 2 Drainage Report Buffalo Valley July, 2013 Runoff Coefficient A runoff coefficient is assigned to each basin that gives a relationship between the amount of precipitation that becomes surface water and the amount of water that is lost to infiltration, evaporation, or transpiration. The runoff coefficient is a function of surface and/or land -use. Because the land -use and the surface cover often vary through the project and from the pre -project and post -project conditions, a composite coefficient is assigned to each drainage basin, based on the weight of the areas and their respective coefficients. Rainfall Intensity Rainfall intensity is determined from intensity duration frequency curves, or IDF curves. IDF curves are graphs of, more or less parallel, frequency curves that yield rainfall intensities based on storm durations. Frequency: The return frequency of a rainfall storm is the statistical probability that a given storm event will occur on average in a given period. For instance a 100 -year storm has the statistical probability of occurring once in a 100 year span or it has a 1% chance of occurring in any given year. It is important to emphasize that it is based on probability statistics and therefore does not reflect actual storm frequency. Storms of a 100 -year magnitude can occur in sequential years, even in the same year. The return frequency of design is chosen and then referred to as the design storm. Duration: The duration of a storm is chosen to coincide with the time of concentration. Length of flow path and velocity of flow are used to calculate time. Two flow elements are used: overland -flow and channel flow. The parameters needed to determine the flow elements include length, slope, a channel roughness coefficient, and channel shape. The theory states that if the duration is equal to the time of concentration, the length of time will be adequate for the entire basin to contribute flow. Analysis Basin areas were determined based on architectural design, proposed grading, and project topography. A site visit helped delineate areas where topographic detail was not sufficient. The project has a relatively large basin directly above it that drains into a culvert that daylights into a ditch on the north property line. The offsite basin has poor vegetative cover and steep slopes. There are three onsite basins: Basin 1 is the largest and contains most of the impervious areas in the buildings and the hardscape. Any landscape in this area is primarily grasses. Basin 1 drains into an existing drywell with questionable integrity and infiltration capacity. Basin 2 is the basin that sheet flows into the ditch along the northern property line. Basin 3 drains to the east and sheet flows onto the steep hillside heavily vegetated with oak brush and grasses. A small amount of roof area drains to the hillside also. MOUNTAIN CROSS ENGINEERING, INC. Civil and Environmental Consulting and Design 826 % Grand Avenue, Glenwood Springs, CO 81601 P: 970.945.5544 F: 970.945.5558 www.mountaincross-eng.com 3 Drainage Report Buffalo Valley July, 2013 Runoff coefficients and SCS Curve numbers were determined from descriptions of land use and/or ground cover for the basin. The vegetation is a mix of Scrub Oak, Pinyon, Sage brush, grass, and brush understory. Composite numbers were calculated by weighting the respective soil cover over the basin area. Based on the SCS study, the site soils are hydrologic group B and the offsite soils belong to hydrologic groups B and C. The parameters for calculating the time of concentration were determined from the site topography. The flows for the basins were calculated using the SCS and Rational methods described above. All calculations are attached for review in the Appendix. Minimum pipe sizes to convey the runoff flows were determined using the Manning's equation for open channel flow. Minimum pipe slope of 0.5%, 18" diameters, smooth pipe material, and project flows were used to compute pipe sizes. Pipe sizing calculations are attached in the Appendix. The channel shape is a "V" type ditch with 2:1 horizontal to vertical side slopes, with minimum slope of 1%, and with a depth of 12". The erosive flow velocity for vegetated, earth channels is between 5 and 6 feet per second (fps). Slopes greater than 4% generate erosive velocities and will need to be armored. Riprap is usually the preferred armor due to its natural appearance and availability. In flatter areas (<4%) of turf or landscaping, a more gradual swale can be used. Calculations are provided in the Appendix. Existing flows were compared to the proposed project flows. If proposed exceeds existing levels detention is necessary. The detention volume was estimated using the FAA method and is only necessary for Area 1 with a 2 -Year volume of 302 cubic feet and a 25 -year volume of 569 cubic feet. Areas 2 and 3 have less contributory area and/or less impervious areas. Runoff flows are proposed to be less than the existing. Therefore detention is not warranted and sheet flow per historic paths are to be maintained. Erosion Control Construction activities can be expected to increase the potential for storm runoff to erode the site. Temporary structures have been designed to contain sediment on the site and to mitigate erosion from construction activities. Straw bale check dams are placed in drainage swales and ditches. Inlets are protected with straw bales. Riprap is placed on the outlet sides of culverts. Silt fencing is shown downhill of construction activities. The permanent structures will be riprap protection at outlets and on ditch thalwegs for slopes where velocities are erosive. Also, revegetation and landscaping is planned with turf, landscape plants, and/or native grasses per a native grass seed mix. Currently the existing vegetative cover is mature native materials. The proposed revegetation is expected to match the coverage percentage and therefore the quality of the storm water discharge from the site is expected to meet existing levels. The project disturbs greater than 1.0 acre and will therefore require a permit from CDPHE. Refer to the Stormwater Management Plan associated with that permit for greater detail concerning erosion control. MOUNTAIN CROSS ENGINEERING, INC. Civil and Environmental Consulting and Design 826 % Grand Avenue, Glenwood Springs, CO 81601 P: 970.945.5544 F: 970.945.5558 www.mountaincross-eng.com 4 1)..inage RehoI I I II liils, Valley 2013 Results An inlet and culvert are sized to accommodate flows from the impervious areas of the site to the detention pond. Swales, valley pans and curb and gutter convey runoff through the site. The culvert has a diameter of 18" and flows the 100 -yr storm. Point discharges of concentrated flows from the site have been avoided by means of riprap aprons to spread flows and reduce velocities. Calculations show erosive velocities at swale slopes of4% or greater. Proposed improvements slightly increase the anticipated flows into Area 1. Detention for Area 1 will be provided by means of a detention pond on the north property line that will drain into the drainage ditch. An outlet release structure will be designed to restrict flows to 5.45 cfs for the 25 -year storm and to 2.53 cfs for the 2 -year storm. These outlets will limit the flows from all the basins to less than or equivalent to the existing levels. Calculations are attached in the Appendix. Because the construction on the site is anticipated to disturb more than one acre, a permit for stormwater discharge is required from the State. A Stormwater Management Plan has been prepared to meet these requirements and is under a separate cover. Recommendations of the geotechnical engineer are to be used in conjunction with the drainage plan and if a conflict arises should be brought to our attention to revise the recornmendations accordingly. Although this study refers to a 100 -year storm, it is speaking from a statistical standpoint that the flood has a 1% chance of occurring within any given year. Il does not actually relate to the frequency of flood occurrence. Also the 100 year flood can be exceeded in any given year, and it cln occur more than once in any year, and can happen in sequential years. Thank you for the opportunity to provide this report. Feel free to call if you have any questions, concerns, or comments. Sincerely, Mounta n Cross Eng1n err Inc. t Chris Hale, PE MOUNTAIN CROSS ENGINEERING, INC. Civil and Environmental Consulting and Design 826 "/, Grand Avenue, Glenwood Springs. co FS 1601 P:970.945„5544 T: 970945.5558 www.nsuunluincross-eng,cons 5 NEW ,. _,OW Mk Wu els Ili w " R x....-.. ear Y 2D13,Gtp�vgle y " i,00(1le lL .Gar t Irnallgery date P9122:2011 39°30'19.06" N 10118'24.14" 'vas elev 5895 ft eye alt 13454 ft'_ FIGURE 1 Aerial Image & Vicinity Map Buffalo Valley MOUNTAIN CROSS ENGINEERING, INC. CMI and Environmental Consulting and Design 626 in Grand Avenue Glenwood Springs, CO S1601 ph g79.1145.5544 fir Yi0.Q43.5556 w 'w.mouri .inp.eom EXISTING DMZ 07/10/13 SCALE 1' _ 100' mow awls Ws DUI ras lufralaaNsylk. JCS 064-001 FIGURE 2 Existin Basins & Time of Concentration Buffalo Valley MOUNTAIN CROSS ENGINEERING, INC. Civil and Environmental Consulting and Design 826112 Grand Avenue Glenwood Springs, CO 81601 ph 970.945.5544 fx 970.945.5558 www.mountaincross.eng.com PROPOSED DMZ 07/10/13 SCALE 1' _ 100' mow awls Ws DUI ras lufralaaNsylk. JCS 064-001 FIGURE 3 Proposed Basins & Time of Concentration Buffalo Valley MOUNTAIN CROSS ENGINEERING, INC. Civil and Environmental Consulting and Design 826112 Grand Avenue Glenwood Springs, CO 81601 ph 970.945.5544 fx 970.945.5558 www.mountaincross.eng.com OFFSITE DAX SCALE 07/10/13 1' _ 300' awls Ws DUI ras lufralaaNsylk. JCS 064-001 FIGURE 4 Offsite Basin & Time of Concentration Buffalo Valley MOUNTAIN CROSS ENGINEERING, INC. 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MAW l. ia3111511 Y 16 Waft Mir sM&.113 OPE IIwSMI 4 SEES PILLI1RYMII1I "lam °wiL'''M iA6 iA RB SOIL RETENTION BLANKETS NOT TO SCALE ceizryf � m w ®8: clog l z—E Cw�og4 Emi lLO a€ =3811 90 ZwEs 10 6 DATE 07/16/13 SCALE: Varies ENGINEER C. HALE DWG FILE BuffValleySite JOB 554-001 SHEET 5 Appendix Report Calculations 39° 30' 29" 39° 30' 14" 107° 18' 22' 301750 301820 301890 Hydrologic Soil Group—Rifle Area, Colorado, Parts of Garfield and Mesa Counties 301960 302030 302100 302170 302240 302310 302380 107° 17' 53" 39° 30' 30" oo d .� ,F m 0 m co moN 0 L0 u-� O m 0 N� co 301750 A 301820 301890 3011960 Map Scale: 1:3,330 if printed on A size (8.5" x 11") sheet. 302030 0 45 90 180 0 DA Natural Resources man Conservation Service 150 300 Meters 270 Feet 600 900 302100 Web Soil Survey National Cooperative Soil Survey 302170 302240 302310 302380 0 N O O 39° 30' 15" 7/9/2013 Page 1 of 4 Hydrologic Soil Group—Rifle Area, Colorado, Parts of Garfield and Mesa Counties MAP LEGEND MAP INFORMATION Area of Interest (A01) Map Scale: 1:3,330 if printed on A size (8.5" x 11") sheet. Area of Interest (AOI) Soils Soil Map Units Soil Ratings 0 A 0 ND 0 0 B/D 0 0 C/D 0 Not rated or not available Political Features 0 Cities Water Features Streams and Canals The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for accurate map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: http://websoilsurvey.nrcs.usda.gov Coordinate System: UTM Zone 13N NAD83 This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Rifle Area, Colorado, Parts of Garfield and Mesa Counties Survey Area Data: Version 6, Mar 25, 2008 Date(s) aerial images were photographed: 8/6/2005 Transportation The orthophoto or other base map on which the soil lines were +++ Rails compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting rY Interstate Highways of map unit boundaries may be evident. US Routes Major Roads r - Local Roads USDA Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 7/9/2013 Page 2 of 4 Hydrologic Soil Group -Rifle Area, Colorado, Parts of Garfield and Mesa Counties Hydrologic Soil Group Hydrologic Soil Group— Summary by Map Unit — Rifle Area, Colorado, Parts of Garfield and Mesa Counties (C0683) Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 2 Arle-Ansari-Rock outcrop complex, 12 to 65 percent slopes D 0.0 0.1% 8 Atencio-Azeltine complex, 1 to 3 percent slopes B 5.4 4.6 54.2% 45.7% 67 Torriorthents-Rock outcrop complex, steep D Totals for Area of Interest 10.0 100.0% Description Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long -duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink -swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. Rating Options Aggregation Method: Dominant Condition USDA Natural Resources raja Conservation Service Web Soil Survey National Cooperative Soil Survey 7/9/2013 Page 3 of 4 Hydrologic Soil Group—Rifle Area, Colorado, Parts of Garfield and Mesa Counties Component Percent Cutoff: None Specified Tie-break Rule: Higher L' DA Natural Resources Web Soil Survey Conservation Service National Cooperative Soil Survey 7/9/2013 Page 4 of 4 N1■■■NNA■N■MN_N-NMI■NIN■■■N■N1i1=NN NNE N1N MUM WW1= ■■ N1■■1Nli11■■■ Emma mum ■■ MEM MEM NNf■1r11N.1■MEIN ■N1■N'N■EMI■ EM=NOME IMO ■■■1.1■MEN ■■■111■■■1NNf'MEM ■■N1i■■NN■ ■■■■1■.■NX1■111N N ■N.■ ■■■ 1■1■■N■ NNN11■N■ 1■111 ■N■.1!■1■ ■NN■N ■■ ■N 1■ N■N ri■1■■■■■■■N11r■1N■■■!!1■■■IEN1■1s•■1�■■■■■■■N■■N■■■rw■N ■■■■■ ItN■1■■■f■1.■■1N■■1■■■■■■11■1■1■■111■NI�1t■■■i1NMN= \i11 1iiN friifill■ ■��. ■ i i { r y i 1 w I { 1111■ i .\!1■'E1O11.N►-REMEE■itiON Nitilt/� P■■N1■1■1N■■■■■Ni■i ii illI"11!! � L I ._ lam:- !Ih ti■ .Jh..x,1. _ : i N■1mLli mNN■1'F!*ri■■ N1■s■u7.:211NEna mom Non mom '\1N1■N■.mr'"V ■N■1."JI■■In1w.�r-ni1sQN1■miAgs.111 :: :11111I11zVW11HHli:: H11MORM n:l:�#H1a ■■1■■ M ■11 ■■llE�ii�AI1 iH111�1NIH11 , r 1:1�11.�.1 a■■■ — ■�__ c ■NNAi■■11■■■■11■■N■■■■■■■■.1#:.�INNEAN www 111N m■11■■■NN■NNf1a■1 ■f■■1■■1 MOIIN �,���1111■NfA■■N■■■■� ME.■r■■NN iMN 1■■■N1■i1■lNN1NN N N N=id�!■■1 1 MHN I HlHH11H1H111 E111i1Hill'unniHI lHH N11f RaIMIMiaM0 GLENWOOD SPRINGS, COLORADO 41 109 108 107 106 105 104 103 102 LU_1L«. 1 1 i°l jam+' 1 t 1 10 10 \REaEY 1 1ft • / V Fr 1A L Lam: AKkON 39 Ikro 12 121 110 J $ 11 FC ,a1 14 16 6 61 12, - .1— ro 10 1'2 COLORADO 39 12 12 111 0 10 20 30 40 MB. 108 1d 107 14 11 121416 1 20 n24 NOAA ATLAS 2, Volume III Prepared by U.S. Department of amerce NitionalOceanic a.ndAtMoapfierleAdmirfl6Oration National VIleather tee off Hydrology ,.,C Prepared for U.S. Department cif Agriculture-, Solt Conservation Service, Engirneering DivI.alon 106 24 22 105 104 21 Figure 25 ISOPLUVIALS of 2 -YR 24 -HR PRECIPITATION IN TENTHS OF AN INCH 103 102 38 37 109 41 15 l 1 40 39 8 37 108 ■ 07 106 11 14 3 16 1 a 105 104 u 24 _ _22 z, 103 26 21 102 36 I 41 STEM, lei • 14 3 14 14 AKRON r5 of 15 14 T 1INI,;1'} 4 16 1a I r CtiENENtr • 1041111.5 �1 _J I — I VAAR I. A 116 • STEIN lE0 i 4 1114 Is I$ !b 1 COLORADO 11 1M` 1611.12 2424X 30 10 0 10 20 i— MILE Y ROAA ATLAS 2, Wham 111 Preogrod by U.S. Department of Bort/norm fialliorgel Citibank INSd Atotioarttiode Acirdehittalfor Hitiorial Weather Straka, Office ! Hydrolot r Prd for 1.13. Dopoeurnant of ri=ultLr�a SCS Ovrierwatuaro Soricios, ri •rR riI.,is crL 3q 30 34 109 108 107 106 Figur 27 I Q;PLUVI&L OF 5 -YR 24,11R PRECIPITATION IN TENTHS OF AN INCH 105 104 103 102 38 7 1c9 108 107 106 105 104 103 21118 t MI 22 r 22.E 20 11 182024262821301 5r 38 NOAA ATLAS 2, Volume III Prepared by Li.. DePartrnent of Comrnerce National Oceanie and AtmosphericAdrr'inistratlion National Weather Service, Office of Hydrology Prepared for U.S. Department of Agriculture, Soll Conservation $ervioe, Engineering Division 109 108 106 Figure 28 ISOPLUVIAL OF 10 -YR 4 -HIS PRECIPITATION IN TENTHS OE AN INCH 103 102 109 108 107 106 105 104 103 102 41 22L 20 34_. 31 HI 40 39 3 8 37 0 20 !kJ! lit 1 ',.._ lib_ j. .----- Pr'',., -A t - , () 2r r 1.2 kL—_lj 20 0.7,,da1 ANION 26 22 22 COLORADO 10 0 10 20 3D 4fl 21 109 108 21 24 2 26 70 22242E3O 343438 14 46 46 44 ISIOAA ATLAS 2, Volume II3 Prepared by U.S. Department of Commerce National Oceanic and Atrrrogpliario Adrmirrietre#Kinn Malone! Weather Service, Office of I-11ydre1o0 Prepared for U.S. Department cif Agriculture,. Soil Conservation Service., Englneerir,g C�ivF tln 107 44 1 S r 37 52.5 41 1 38 Figure 29 ISOPLUVIALS OF 25 -YR 24 -HR PRECIPITATION IN TENTHS OF AN INCH 105 104 1 103 102 41 109 108 107 106 105 24 104 103 02. 40 39 38 ` .—. y2�9���h M ERLI 1 � 'CRAIG 2 EELEY T AKRON 1 26 COLORADO' 4g-4. p I -3 PLJIBLO 1 L-- I j 41 3 4 HASW L 4 1 rp N 37 109 24 COLORADO 10 0 10 20 30 40 MISS_ 1 108 28 107 28 Th 1 11 24 24 2 301838 384248 NOM ATLAS 2, Vo1iunieIII Prepared by LIZ, Dipatimant t C rnrli I X& fiviortalOceanic indA to ninptFlaRic AMrrilinistratkir N.,: i:! l Sankt Orr i .£ f �9 1rc1i Coriservabon tIGs Eng n E'e • °rg Division 106 105 104 Figure 30 I ORLUVIALS OF 50 -YR 24 -HR PRECIPITATION IN TENTHS OF AN INCH 103 109 41 16. 4 39 38 37 jd 21 107 30 2Sn 14 106 I05 104 103 102 X12 a IRE 1I 3 J I. 24 24 1 11, I AKRON r..C1 LE'Yr --— ANTO J L e+ ^ d'4 _t• 42 V'U41.11RUT4i14 t 26 1 a. a COLORADO 1 SPRINGS 50 _ PUEBLO 44-4 Am.I'P. U I 5F1R1N4 I LELbt r • g COLORADO TO 0 10 20 30 40 MILES. 30 21 It 211134 12 4246 50 NO404 ASS 2. VOlurivii Hi. prepored by 'J Dimerhinentof Commons rieironei oc,- e r�i,d,,At w1phe*dar1 t ' Ne 6o 11 Weather $iwvk.4 Hoirology Prtpared f e r U S. Der Ertmtirit of A Icultur 0 anstirvati r S Biel Eng-nreffrieDiviSFOA 109 108 107 106 55 sa 55 Figure 31 IS IPLUV1AL OF I -TR 24.14R PHE IFITATIGN IN TENTHS OF AN INCH 105 104 103 4 140 11J 2, 9I 38 37 MOUNTAIN CROSS ENGINEERING, INC. Civil and Environmental Consulting and Design 826 112 Grand Avenue Glenwood Springs, CO 81601 --- -_ kph 970.945.5544 fx 970.945.5558 www.mounfaincrosscng.com DRAINAGE CALCULATIONS for Buffalo Valley, Garfield County, CO 7/12/2013 Drainage Area : El Surface description: Existing restaurant, motel buildings, and parking w/ grass open space PROPERTY GENERAL SURFACE DATA Total Drainage Area: 72,312 sq. ft. 1.66 ac. RUNOFF COEFFICIENT sq. ft. or C Land Use est. % acres factors Building Roof 11655 0.27 0.95 Scrub oak grass understory 0 0.00 0.2 Hardscape and Paving 39843 0.91 0.95 Landscaped turf and planters 20,814 0.48 0.3 Pine and Aspen 0% 0.00 0.2 Sage and Grasses 0% 0.00 0.4 TOTAL BASIN ACERAGE 1.66 Weighted C: 0.763 TIME OF CONCENTRATION Overland Flow Time Length Slope Upstream Elevation 5889.0 250 0.07 Dnstream Elevation 5872.0 Channel Flow Time Length Slope Upstream Elevation 5872.0 0.0 1.00 Dnstream Elevation 5872.0 Total C 0.76 K 7.000 5.11 min Tc 5.11 Tc 0.00 RUNOFF Intensity (in/hr) 2 -yr Storm 2.0 10 -yr Storm 3.4 25 -yr Storm 4.3 100 -yr Storm 5.5 Flowrate (cfs) 2.53 4.31 5.45 6.97 NOTES: - Soils are hydrologic soil group B - Conveyance coefficient K is based on "lawn" or vegetation lined channel MOUNTAIN CROSS ENGINEERING, INC. Civil and Environmental Consulting and Design 826 112 Grand Avenue Glenwood Springs, CO 81601 --- -_ kph 970.945.5544 fx 970.945.5558 www.mounfaincrosscng.com DRAINAGE CALCULATIONS for Buffalo Valley, Garfield County, CO 7/12/2013 Drainage Area : E2 Surface description: Existing grass open space flowing into drainage ditch. PROPERTY GENERAL SURFACE DATA Total Drainage Area: 7,680 sq. ft. 0.18 ac. RUNOFF COEFFICIENT sq. ft. or C Land Use est. % acres factors Building Roof 0 0.00 0.95 Scrub oak grass understory 0 0.00 0.2 Hardscape and Paving 0 0.00 0.95 Landscaped turf and planters 7,680 0.18 0.3 Pine and Aspen 0% 0.00 0.2 Sage and Grasses 0% 0.00 0.4 TOTAL BASIN ACERAGE 0.18 Weighted C: 0.300 TIME OF CONCENTRATION Overland Flow Time Length Slope Upstream Elevation 5894.0 200 0.10 Dnstream Elevation 5874.0 Channel Flow Time Length Slope Upstream Elevation 5874.0 0.0 1.00 Dnstream Elevation 5874.0 Total C 0.30 K 7.000 9.55 min Tc 9.55 Tc 0.00 RUNOFF Intensity (in/hr) 2 -yr Storm 1.6 10 -yr Storm 2.8 25 -yr Storm 3.4 100 -yr Storm 4.5 Flowrate (cfs) 0.08 0.15 0.18 0.24 NOTES: - Soils are hydrologic soil group B - Conveyance coefficient K is based on "lawn" or vegetation lined channel MOUNTAIN CROSS ENGINEERING, INC. Civil and Environmental Consulting and Design 826 112 Grand Avenue Glenwood Springs, CO 81601 --- -_ kph 970.945.5544 fx 970.945.5558 www.mounfaincrosscng.com DRAINAGE CALCULATIONS for Buffalo Valley, Garfield County, CO 7/12/2013 Drainage Area : E3 Surface description: Existing restaurant and motel buildings w/ scrub oak hillside PROPERTY GENERAL SURFACE DATA Total Drainage Area: 24,606 sq. ft. 0.56 ac. RUNOFF COEFFICIENT sq. ft. or C Land Use est. % acres factors Building Roof 5410 0.12 0.95 Scrub oak grass understory 13,301 0.31 0.2 Hardscape and Paving 2,435 0.06 0.95 Landscaped turf and planters 3,460 0.08 0.3 Scrub oak grass understory 0% 0.00 0.2 Sage and Grasses 0% 0.00 0.4 TOTAL BASIN ACERAGE 0.56 Weighted C: 0.453 TIME OF CONCENTRATION Overland Flow Time Length Slope Upstream Elevation 5872.0 70 0.39 Dnstream Elevation 5845.0 Channel Flow Time Length Slope Upstream Elevation 5845.0 0.0 1.00 Dnstream Elevation 5845.0 Total C 0.45 K 7.000 2.93 min **use 5 min Tc Tc 2.93 Tc 0.00 RUNOFF Intensity (in/hr) 2 -yr Storm 2.0 10 -yr Storm 3.4 25 -yr Storm 4.3 100 -yr Storm 5.5 Flowrate (cfs) 0.51 0.87 1.10 1.41 NOTES: - Soils are hydrologic soil group B - Conveyance coefficient K is based on "lawn" or vegetation lined channel MOUNTAIN CROSS ENGINEERING, INC. Civil and Environmental Consulting and Design 826 112 Grand Avenue Glenwood Springs, CO 81601 --- -_ kph 970.945.5544 fx 970.945.5558 www.mounfaincrosscng.com DRAINAGE CALCULATIONS for Buffalo Valley, Garfield County, CO 7/12/2013 Drainage Area : P1 Surface description: Proposed improvements with apartment buildings, parking, and landscaping PROPERTY GENERAL SURFACE DATA Total Drainage Area: 76,880 sq. ft. 1.76 ac. RUNOFF COEFFICIENT sq. ft. or C Proposed Land Use est. % acres factors Building Roof 18400 0.42 0.95 Scrub oak grass understory 0 0.00 0.2 Hardscape and Paving 49329 1.13 0.95 Landscaped turf and planters 9,151 0.21 0.3 Pine and Aspen 0% 0.00 0.2 Sage and Grasses 0% 0.00 0.4 TOTAL BASIN ACERAGE 1.76 Weighted C: 0.873 TIME OF CONCENTRATION Overland Flow Time Length Upstream Elevation 5892.00 200 Dnstream Elevation 5876.50 Channel Flow Time Length Upstream Elevation 5876.50 155 Dnstream Elevation 5874.00 Slope 0.08 Slope 0.02 Total C 0.87 K 20.000 3.97 min **use 5 min Tc Tc 2.95 Tc 1.02 RUNOFF 2 -yr Storm 10 -yr Storm 25 -yr Storm 100 -yr Storm Intensity (in/hr) 2.0 3.4 4.3 5.5 Flowrate (cfs) 3.08 5.24 6.62 8.47 NOTES: - Soils are hydrologic soil group B - Conveyance coefficient K is based on paved channel MOUNTAIN CROSS ENGINEERING, INC. Civil and Environmental Consulting and Design 826 112 Grand Avenue Glenwood Springs, CO 81601 --- -_ kph 970.945.5544 fx 970.945.5558 www.mounfaincrosscng.com DRAINAGE CALCULATIONS for Buffalo Valley, Garfield County, CO 7/12/2013 Drainage Area : P2 Surface description: Proposed grass open space flowing into drainage ditch. PROPERTY GENERAL SURFACE DATA Total Drainage Area: 5,165 sq. ft. 0.12 ac. RUNOFF COEFFICIENT sq. ft. or C Proposed Land Use est. % acres factors Building Roof 0 0.00 0.95 Scrub oak grass understory 0 0.00 0.2 Hardscape and Paving 0 0.00 0.95 Landscaped turf and planters 5,165 0.12 0.3 Pine and Aspen 0% 0.00 0.2 Sage and Grasses 0% 0.00 0.4 TOTAL BASIN ACERAGE 0.12 Weighted C: 0.300 TIME OF CONCENTRATION Overland Flow Time Length Slope C Upstream Elevation 5888.00 35 0.11 0.30 Dnstream Elevation 5884.00 Channel Flow Time Length Slope K Upstream Elevation 5884.00 0.0 1.00 7.000 Dnstream Elevation 5883.99 Total 3.82 min **use 5 min Tc Tc 3.82 Tc 0.00 RUNOFF Intensity Flowrate (in/hr) (cfs) 2 -yr Storm 2.0 0.07 10 -yr Storm 3.4 0.12 25 -yr Storm 4.3 0.15 100 -yr Storm 5.5 0.20 NOTES: - Soils are approximately 75% hydrologic soil group B and 25% group C - Satellite image was used for offsight delineation of land use areas - If land use percentages are used, they have been estimated from satellite image - Conveyance coefficient K is based on "lawn" or vegetation lined channel MOUNTAIN CROSS ENGINEERING, INC. Civil and Environmental Consulting and Design 826 112 Grand Avenue Glenwood Springs, CO 81601 --- -_ kph 970.945.5544 fx 970.945.5558 www.mounfaincrosscng.com DRAINAGE CALCULATIONS for Buffalo Valley, Garfield County, CO 7/12/2013 Drainage Area : P3 Surface description: Proposed building and landscaping w/ scrub oak hillside PROPERTY GENERAL SURFACE DATA Total Drainage Area: 22,390 sq. ft. 0.51 ac. RUNOFF COEFFICIENT sq. ft. or C Proposed Land Use est. % acres factors Building Roof 5060 0.12 0.95 Scrub oak grass understory 12,430 0.29 0.2 Hardscape and Paving 0 0.00 0.95 Landscaped turf and planters 4,900 0.11 0.3 Pine and Aspen 0% 0.00 0.2 Sage and Grasses 0% 0.00 0.4 TOTAL BASIN ACERAGE 0.51 Weighted C: 0.391 TIME OF CONCENTRATION Overland Flow Time Length Slope C Upstream Elevation 5873.00 115 0.37 0.39 Dnstream Elevation 5831.00 Channel Flow Time Length Slope K Upstream Elevation 5831.00 0.0 1.00 7.000 Dnstream Elevation 5830.99 Total 4.19 min **use 5 min Tc Tc 4.19 Tc 0.00 RUNOFF Intensity Flowrate (in/hr) (cfs) 2 -yr Storm 2.0 0.40 10 -yr Storm 3.4 0.68 25 -yr Storm 4.3 0.87 100 -yr Storm 5.5 1.11 NOTES: - Soils are approximately 75% hydrologic soil group B and 25% group C - Satellite image was used for offsight delineation of land use areas - If land use percentages are used, they have been estimated from satellite image - Conveyance coefficient K is based on "lawn" or vegetation lined channel MOUNT/Mt" CROSS ENGINEERING, INC. Civil and Environmental Consulting and Design 826 1/2 Grand Avenue Glenwood Springs, CO 81601 ph 970.945.5544 fx 970.945.5558 www.mountaincross-eng.com CALCULATIONS for Buffalo Valley, Garfield County, CO 7/11/2013 Drainage Area : 01 Surface description: Off -sight basin into culvert w/ mostly native vegetation PROPERTY GENERAL SURFACE DATA Total Drainage Area: 195,223 sq. ft. 4.48 ac. SCS Cn COEFFICIENT sq. ft. or Cn Proposed Land Use est. % acres factors Roof and Paving 620 0.01 98 Gravel Roads 3870 0.09 85 Hardscape & Paving 5910 0.14 98 Landscaped turf and planters 0 0.00 69 Pinyon and Juniper C Soils, Poor 64% 2.89 85 Pinyon and Juniper B Soils, Fair 13% 0.00 58 Sage and Grasses B Soils, Fair 30% 1.35 51 TOTAL BASIN ACERAGE 4.48 Weighted C: 75.1 rai MOUNTAIN CROSS ENGINEERING, INC. Civil and Environmental Consulting and Design 826 1/2 Grand Avenue Glenwood Springs, CO 81601 ph 970.945.5544 fx 970.945.5558 www.mountaincrosseng.com DRAINAGE CALCULATIONS for Buffalo Valley, Garfield County, CO 7/11/2013 Drainage Area : P1 Surface description: Proposed improvements with apartments, parking and landscaping PROPERTY GENERAL SURFACE DATA Total Drainage Area: 76,880 sq. ft. 1.76 ac. SCS Cn COEFFICIENT sq. ft. or Cn Proposed Land Use est. % acres factors Roof and Paving 18400 0.42 98 Gravel Roads 0 0.00 98 Hardscape & Paving 49329 1.13 98 Landscaped turf and planters 9,151 0.21 69 Pinyon and Juniper B Soils, Poor 0% 0.00 51 Sage and Grasses B Soils, Fair 0% 0.00 58 TOTAL BASIN ACERAGE 1.76 Weighted C: 94.5 MOUNT/Mt" CROSS ENGINEERING, INC. Civil and Environmental Consulting and Design 826 1/2 Grand Avenue Glenwood Springs, CO 81601 ph 970.945.5544 fx 970.945.5558 www.mountainci Desan9.45m DRAINAGE CALCULATIONS for 800 CLUNY ROAD, PITKIN COUNTY, CO 3/20/2012 Drainage Area : El Surface description: Existing restaurant, motel buildings, and parking w/ grass open space PROPERTY GENERAL SURFACE DATA Total Drainage Area: 72,312 sq. ft. 1.66 ac. SCS Cn COEFFICIENT sq. ft. or Cn Proposed Land Use est. % acres factors Roof and Paving 11655 0.27 98 Gravel Roads 0 0.00 98 Hardscape & Paving 39843 0.91 98 Landscaped turf and planters 20,814 0.48 69 Pinyon and Juniper B Soils, Poor 0% 0.00 51 Sage and Grasses B Soils, Fair 0% 0.00 58 TOTAL BASIN ACERAGE 1.66 Weighted C: 89.7 Hydrology Report Hydraflow Express Extension for AutoCAD® Civil 3D® 2013 by Autodesk, Inc. 25 -year Culvert Hydrograph type Storm frequency (yrs) Drainage area (ac) Basin Slope (%) Tc method Total precip. (in) Storm duration (hrs) = SCS = 25 = 4.480 = See Worksheet = TR55 = 2.20 = 24 Peak discharge (cfs) Time interval (min) Curve number (CN) Hydraulic length (ft) Time of conc. (min) Storm Distribution Shape factor Thursday, Jul 11 2013 = 2.727 = 1 = 75 = See Worksheet = 13 = Type II = 484 Q (cfs) 3.00 2.00 1.00 0.00 Hydrograph Volume = 7,734 (cuft); 0.178 (acft) Runoff Hydrograph 25 -yr frequency 0.0 2.0 4.0 6.0 8.0 Runoff Hyd - Qp = 2.73 (cfs) i Q (cfs) 3.00 2.00 1.00 0.00 10.0 12.0 14.0 16.0 18.0 20.0 22.0 24.0 26.0 Time (hrs) TR55 Tc Worksheet SCS 25 -year Culvert Description Sheet Flow Manning's n -value Flow length (ft) Two-year 24 -hr precip. ((in)) Land slope (%) Travel Time (min) Shallow Concentrated Flow Flow length (ft) Watercourse slope (%) Surface description Average velocity (ft/s) Travel Time (min) Channel Flow X sectional flow area ((sqft)) Wetted perimeter ((ft)) Channel slope (%) Manning's n -value Velocity (ft/s) Flow length (ft) Travel Time (min) A B C = 0.240 0.011 0.011 = 200.0 0.0 0.0 = 1.20 0.00 0.00 = 50.00 0.00 0.00 Hydraflow Express by Intelisolve Totals = 11.20 + 0.00 + 0.00 = 11.20 = 865.00 = 36.00 = Unpaved = 9.68 0.00 0.00 Paved 0.00 0.00 0.00 Paved 0.00 = 1.49 + 0.00 + 0.00 = 1.49 = 0.00 0.00 0.00 = 0.00 0.00 0.00 = 0.00 0.00 0.00 = 0.015 0.015 0.015 = 0.00 0.00 0.00 = 0.0 0.0 0.0 = 0 + 0 + 0 = 0.00 Total Travel Time, Tc 13.00 min Hydrology Report Hydraflow Express Extension for AutoCAD® Civil 3D® 2013 by Autodesk, Inc. 100 -year Culvert Hydrograph type Storm frequency (yrs) Drainage area (ac) Basin Slope (%) Tc method Total precip. (in) Storm duration (hrs) = SCS = 100 = 4.480 = See Worksheet = TR55 = 2.60 = 24 Peak discharge (cfs) Time interval (min) Curve number (CN) Hydraulic length (ft) Time of conc. (min) Storm Distribution Shape factor Thursday, Jul 11 2013 = 4.241 = 1 = 75 = See Worksheet = 13 = Type II = 484 Q (cfs) 5.00 4.00 3.00 2.00 1.00 0.00 Hydrograph Volume = 11,361 (cuft); 0.261 (acft) Runoff Hydrograph 100 -yr frequency 0.0 2.0 4.0 Q (cfs) 5.00 4.00 3.00 2.00 1.00 0.00 6.0 8.0 10.0 12.0 14.0 16.0 18.0 20.0 22.0 24.0 26.0 Time (hrs) Runoff Hyd - Qp = 4.24 (cfs) TR55 Tc Worksheet SCS 100 -year Culvert Description Sheet Flow Manning's n -value Flow length (ft) Two-year 24 -hr precip. ((in)) Land slope (%) Travel Time (min) Shallow Concentrated Flow Flow length (ft) Watercourse slope (%) Surface description Average velocity (ft/s) Travel Time (min) Channel Flow X sectional flow area ((sqft)) Wetted perimeter ((ft)) Channel slope (%) Manning's n -value Velocity (ft/s) Flow length (ft) Travel Time (min) A B C = 0.240 0.011 0.011 = 200.0 0.0 0.0 = 1.20 0.00 0.00 = 50.00 0.00 0.00 Hydraflow Express by Intelisolve Totals = 11.20 + 0.00 + 0.00 = 11.20 = 865.00 = 36.00 = Unpaved = 9.68 0.00 0.00 Paved 0.00 0.00 0.00 Paved 0.00 = 1.49 + 0.00 + 0.00 = 1.49 = 0.00 0.00 0.00 = 0.00 0.00 0.00 = 0.00 0.00 0.00 = 0.015 0.015 0.015 = 0.00 0.00 0.00 = 0.0 0.0 0.0 = 0 + 0 + 0 = 0.00 Total Travel Time, Tc 13.00 min MOUNTf'1IN CROSS ENGINEERING, INC. Civil and Environmental Consulting and Design 8261/2 Grand Avenue Glenwood Springs, CO 81601 ph 970.945.5594 fx 970.995.5558 www.moumaincross-eng. tom Area = Tc = Release rate = C= 0.873 DETENTION CALCULATIONS for Area 1 Buffalo Valley, Garfield County, CO 7/10/2013 1.76 acres 5 minutes 5.45 cfs 25 -yr Detention Duration I Release Volume Inflow Volume Volume Difference (min.) (in./hr.) (ft3) (ft3) (ft3) 5 4.40 1635 2045 410 10 3.25 2453 3021 569 15 2.75 3270 3834 564 20 2.40 4088 4462 374 25 2.15 4905 4996 91 30 1.95 5723 5438 -285 35 1.75 6540 5694 -846 40 1.60 7358 5949 -1408 45 1.45 8175 6065 -2110 50 1.35 8993 6275 -2718 55 1.30 9810 6646 -3164 60 1.25 10628 6972 -3656 Maximum Volume Difference = Required Detention = Release rate = C= 0.873 2.53 cfs 569 Cubic Feet 2 -yr Detention Duration (min.) I (in./hr.) Release Volume (ft3) Inflow Volume (ft3) Volume Difference (ft3) 5 2.00 759 930 171 10 1.55 1139 1441 302 15 1.30 1518 1813 295 20 1.15 1898 2138 241 25 1.00 2277 2324 47 30 0.90 2657 2510 -147 35 0.80 3036 2603 -433 40 0.75 3416 2789 -627 45 0.70 3795 2928 -867 50 0.65 4175 3021 -1153 55 0.60 4554 3068 -1486 60 0.55 4934 3068 -1866 Maximum Volume Difference = 302 Cubic Feet 439.00 37.70 238.35 2.5 595.875 Cubic Feet Orifice Calculations = ' 2 year Q = 2.447 cfs C = 0.600 A = 0.379 sq. ft. H = 1.800 ft Orifice Calculations = ' 25 year Q = 3.159 cfs C = 0.600 A = 0.379 sq. ft. H = 3.000 ft Plus Q = 2.203 cfs C = 0.600 A = 0.418 sq. ft. H = 1.200 ft < 2.53 cfs <5.45cfs 8.333 diameter 2.291 cfs 8.333 diameter 8.75 diameter Channel Report Hydraflow Express Extension for AutoCAD® Civil 3D® 2013 by Autodesk, Inc. Thursday, Jul 11 2013 25 -Year P1 Swale Triangular Highlighted Side Slopes (z:1) = 2.00, 2.00 Depth (ft) Total Depth (ft) = 1.00 Q (cfs) Area (sqft) Invert Elev (ft) = 1.00 Velocity (ft/s) Slope (%) = 1.00 Wetted Perim (ft) N -Value = 0.022 Crit Depth, Yc (ft) Top Width (ft) EGL (ft) Calculations Compute by: Known Q (cfs) Known Q = 6.62 = 0.94 = 6.620 = 1.77 = 3.75 = 4.20 = 0.93 = 3.76 = 1.16 Elev (ft) Section Depth (ft) 3.00 2.50 2.00 1.50 1.00 0.50 0 .5 1 1.5 2 2.5 Reach (ft) 3 3.5 4 4.5 2.00 1.50 1.00 0.50 0.00 -0.50 5 HGI 213.00 Lf of18(in)@0.47% Embankment Hw Culvert Report Hydraflow Express Extension for AutoCAD® Civil 3D® 2013 by Autodesk, Inc. Thursday, Jul 11 2013 2 -yr to 100 -year P1 Pipe Invert Elev Dn (ft) = 71.00 Calculations Pipe Length (ft) = 213.00 Qmin (cfs) Slope (%) = 0.47 Qmax (cfs) Invert Elev Up (ft) = 72.00 Tailwater Elev (ft) Rise (in) = 18.0 Shape = Circular Highlighted Span (in) = 18.0 Qtotal (cfs) No. Barrels = 1 Qpipe (cfs) n -Value = 0.012 Qovertop (cfs) Culvert Type = Circular Concrete Veloc Dn (ft/s) Culvert Entrance = Groove end projecting (C) Veloc Up (ft/s) Coeff. K,M,c,Y,k = 0.0045, 2, 0.0317, 0.69, 0.2 HGL Dn (ft) Embankment Top Elevation (ft) Top Width (ft) Crest Width (ft) Elev (ft) 75.00 74.00 73.00 = 74.00 = 200.00 = 10.00 Profile HGL Up (ft) Hw Elev (ft) Hw/D (ft) Flow Regime = 3.00 = 8.50 = (dc+D)/2 = 6.70 = 6.70 = 0.00 = 4.26 = 5.19 = 72.25 = 73.03 = 73.51 = 1.00 = Inlet Control Hw Depth (ft) 72.00 - 71.00 70.00 0.0 50.0 100.0 150.0 200.0 250.0 300.0 350.0 400.0 450.0 Reach (ft) 3.00 2.00 1.00 0.00 -1.00 -2.00 Culvert Report Hydraflow Express Extension for AutoCAD® Civil 3D® 2013 by Autodesk, Inc. Thursday, Jul 11 2013 2 -yr to 100 -year P1 Pipe Invert Elev Dn (ft) = 71.00 Calculations Pipe Length (ft) = 213.00 Qmin (cfs) Slope (%) = 0.47 Qmax (cfs) Invert Elev Up (ft) = 72.00 Tailwater Elev (ft) Rise (in) = 18.0 Shape = Circular Highlighted Span (in) = 18.0 Qtotal (cfs) No. Barrels = 1 Qpipe (cfs) n -Value = 0.012 Qovertop (cfs) Culvert Type = Circular Concrete Veloc Dn (ft/s) Culvert Entrance = Groove end projecting (C) Veloc Up (ft/s) Coeff. K,M,c,Y,k = 0.0045, 2, 0.0317, 0.69, 0.2 HGL Dn (ft) Embankment Top Elevation (ft) Top Width (ft) Crest Width (ft) Elev (ft) 75.00 74.00 73.00 = 74.00 = 200.00 = 10.00 Profile HGL Up (ft) Hw Elev (ft) Hw/D (ft) Flow Regime = 3.00 = 8.50 = (dc+D)/2 = 8.50 = 8.50 = 0.00 = 5.18 = 4.95 = 72.31 = 73.40 = 73.78 = 1.19 = Inlet Control Hw Depth (ft) HGL 213.00 Lf of18(in)@0.47% Hw 72.00 - 71.00 70.00 0.0 50.0 100.0 150.0 200.0 250.0 300.0 350.0 400.0 450.0 Reach (ft) 3.00 2.00 1.00 0.00 -1.00 -2.00 Relative Wildfire Hazard Negl Low irrfakiviskrals Aioxde ate Extwvne Orta 07/11/13 1I N. Serle Chi Nds a■ PIE 9slldeVeMpSle de 564-001 Wildfire Hazard Garfield County GIS MOUNTAIN CROSS ENGINEERING, INC. CIvII and Environmental Consultlng and Design 826 112 Grand Avenue Glenwood Springs, CO 81601 ph 170.945.5544 fx 970.945.5558 www.mountalncrossung.com I ji7LFI r A Min MEI • sir , mi A • Tor, architects t- r r BUFFALO VALLEY APARTMENTS X11' arch 1te cts BOFFALO VALLEY APARTMENTS architects BUFFALO \YALLEY APAFTMENTS ••*'..1•1 GR41 t r arch its cts BUFFALO VALLEY APARTMENT 11 0 u Ini 00 BUILDING 1 -TYPICAL UPPER LEVEL PLAN 0' 10' 20* 30' 40' 50' 0 u MIL MINI arc it•cr• BUFFALO VALLEY APARTMENTS 8 row—eire— Joku. SCHEMATIC FLOOR PLANS AI.I V 0 11 BUILDING 2 -TYPICAL UPPER LEVEL PLAN 0' 10' 20' 30' 40' 50' arunri o 31 SICRAOE UNITS 0 BUILDING 1—LOWER LEVEL PLAN a' 10* 20* aa' 40* 50* GROUP 8 1 8 m i g IDYL rarrasm— Axil -SCHEMATIC FLOOR PLANS &II 00 ou �auu Iu[ 2 STORAGE UNITS + 2 UNDER LANDING J0 g BUILDING 2— _OWER LEVEL PLAN 10' 20' 30' 40' 50' 111.1.11.25 EFL sae GROUP BUFFALO VALLEY APARTMENTS 8 Obit DE ®E, 104 111.1413 SCHEMATIC FLOOR PLANS A1.4 IMO architects Buffalo Valley Apartments - Parking The site for the proposed Buffalo Valley Apartments will accommodate two Building Footprints each with eight Units per typical floor level. To develop an economically feasible project, these buildings each must be three floors; and due to the topography of the site, each building would step down so as to accommodate a fourth level of four Units at the lowest level. Thus, the plan proposes two buildings with three floors of eight units each and one (lowest level) floor of four units, resulting in a total Unit count of fifty-six (twenty -eight Units per building). As a result of a 12'-0" building design modules and allowing two modules per building for stairways, the proposed distribution of Units is six 2 -Bedroom & one 1 -Bedroom Unit per typical floor plus three 2 -Bedroom & one 1 -Bedroom for each lowest level. Therefore, the proposed total Unit count is forty-two 2;Bedroom Units and fourteen 1 -Bedroom Units for a total of Fifty-six Units Our research indicates that a three to one ratio of 2 -Bedroom to 1 -Bedroom Units is appropriate for this type of project in this location. And, fifty-six units is the necessary unit count to make an economically viable project. The quantity and size of the units is in balance with the size of the site and the FAR and site -coverage are compliant with Garfield County standards. Studies that we have reviewed, as well as our own research indicate that the proposed parking plan is appropriate for this project. The site layout has 100 parking spaces properly distributed for efficient access to the buildings. The parking calculation which has been utilized is one space per bedroom - thus requiring 98 spaces. While this formula varies from the Garfield County standard, it is consistent with similar projects and meets standards for other communities such as Aspen, Snowmass, & Denver. While additional parking can be accommodated on-site, the proposed balance of Unit -Count, FAR and Land Coverage allows for an appropriate amount of Landscape and Green -Space. Additional, unnecessary, parking spaces would result in fewer planting areas and overall a less attractive housing complex. ■. �� Z -Group Architects, P.C. • 411 East Main Street, Aspen, CO. 81611 • Telephone: 970-925-1832 • Fax: 970-925-1371