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Home My WebLink About1.36 EngDesign-E.SedimentControl E R OSION AND SEDIMENT CONTROL PLAN RIVER EDGE COLORADO GARFIELD COUNTY, COL ORADO O W N E R / A P P L I C A N T : C A R B O N D A L E I N V E S T M E N T S , L L C 7 9 9 9 H W Y 8 2 C A R B O N D A L E C O 8 1 6 2 3 970-456-5 3 2 5 C O N S U L T A N T : 8 1 4 0 P A R T N E R S , L L C P O B O X 0 4 2 6 E A G L E , C O 8 1 6 3 1 J A N U A R Y 1 4 , 2 0 1 1 Erosion and Sediment Control Plan River Edge Colorado, Garfield County, Colorado 2 EROSION AND SEDIMENT CONTROL PLAN RIVER EDGE COLORADO GARFIELD COUNTY, COL ORADO TABLE OF CONTENTS I. INTRODUCTION ........................................................................... 4 A. BASIS .................................................................................................... 4 B. PURPOSE AND SCOPE OF REPORT .......................................................... 4 C. DESIGN STANDARDS .............................................................................. 6 D. FINDINGS .............................................................................................. 7 II. PROJECT LOCATION AND DESCRIPTION .......................................... 8 A. PROJECT LOCATION ............................................................................... 8 B. PROJECT DESCRIPTION .......................................................................... 8 III. PLAN BASIS ................................................................................. 9 A. EXISTING SITE CONDIT IONS ................................................................... 9 1. RIVERS, CREEKS AND FLOODING ............................................................. 10 2. WETLANDS............................................................................................... 10 3. GROUNDWATER....................................................................................... 11 4. TOPOGRAPHY .......................................................................................... 11 B. SPECIA L PLAN CONSIDERATION S .......................................................... 11 1. SOILS ........................................................................................................ 12 2. GEOTECHNICAL CONDITIONS .................................................................. 13 C. HYDROLOGIC AND HYDRA ULIC CRITERIA .............................................. 14 1. RAINFALL SOURCE ................................................................................... 14 D. HYDRAULIC CRITERIA ........................................................................... 16 1. CONVEYANCE CHANNELS ........................................................................ 16 2. STORM SEWERS ....................................................................................... 16 3. ROAD FLOWS ........................................................................................... 16 4. EMERGENCY RUNOFF CONVEYANCE ....................................................... 16 IV. GRADING AND DRAINAGE PLAN .................................................. 17 Erosion and Sediment Control Plan River Edge Colorado, Garfield County, Colorado 3 A. OVERALL CONCEPT .............................................................................. 17 1. GRADING AND DRAINAGE ....................................................................... 17 2. OFF-SITE BASINS ...................................................................................... 18 3. SURROUNDING LAND USES ..................................................................... 18 4. WATER QUANTITY AND QUALITY STORAGE ............................................ 18 B. SPECIFIC DETAILS ................................................................................. 19 1. ONSITE BASINS ........................................................................................ 19 2. MAJOR DRAINAGEWAYS .......................................................................... 20 3. WATER QUANTITY AND QUALITY STORAGE FACILITIES ........................... 21 V. EROSION AND SEDIMENT CONTROL ............................................. 22 A. OVERALL CONCEPT .............................................................................. 22 B. RECLAIMED CONDITIONS ..................................................................... 23 C. PHASED CONDITIONS .......................................................................... 24 D. FINAL CONDITIONS .............................................................................. 25 VI. COST ESTIMATE AND ME THOD OF FINANCING .............................. 26 VII. LIST OF REFERENCES .................................................................. 26 APPENDICES APPENDIX A: VICINITY MAP AND PROJECT SITE DRAWINGS APPENDIX B: RAINFALL INPUT APPENDIX C: IDF CURVE DATA APPENDIX D: BASIN DELINEATION MAP APPENDIX E: PRE- AND POST-DEVELOPMENT WATER STORAGE AND QUALITY DATA APPENDIX F: CDPHE STORMWATER MANAGEMENT PLAN APPLICATION APPENDIX G: WETLANDS DELINEATION REPORT Erosion and Sediment Control Plan River Edge Colorado, Garfield County, Colorado 4 I. INTRODUCTION A. BASIS This Erosion and Sediment Control Plan ("Plan") has been prepared in support of an application for PUD Plan Review ("Rezoning") and Subdivision Review ("Preliminary Plan") for the proposed River Edge Colorado ("Project", "REC", or "REC PUD") in accordance with the requirements of the Garfield County Unified Land Use Resolution of 2008 ("ULUR"), as amended. This Plan specifically addresses the requirements of Section 4-502.C.4 of the ULUR as required under Section 5-501.G.11.e and Sections 6-301.B.5.e and 301.C.8.r(5), meeting the criteria of Sections 7-203, 7-204, 7-205,7-206, 7-207, 7- 303, 7-212.B and 7-701 of the ULUR. This Report is supported by other referenced documents submitted as part of the REC rezoning and preliminary plan applications including the River Edge Colorado PUD (Rezoning) and Subdivision (Preliminary Plan) Drawing Package ("Drawing Package"). B. PURPOSE AND SCOPE OF R EPORT The primary purpose of this Plan is to provide preliminary planning and design information for erosion and sediment control efforts depicted on the engineering plans (See Erosion and Sediment Control Plan, ES01-04 Series in the Drawing Package). This Plan (in combination with the Erosion and Sediment Control Plan, ES01-04 Series in the Drawing Package) documents that the Project meets the requirements of the ULUR in all respects, except as otherwise provided herein. The Plan further serves as the design framework for final design efforts to be completed in association with each Final Plat. For clarity purposes, the following lists the submittal requirements under Section 4- 502.C.4 of the ULUR and the location of the required information within this Plan or the drawings in the Drawing Package:  Site Map: Showing locations of any existing structures, waterbodies, or hydrologic features on the Project Site. (Series ES01, Drawing Package)  Drainage Structures: Showing locations of existing and proposed drainage structures or natural drainage features affecting site drainage on the Project Site and within 100 feet adjacent to the Project Site boundary. (Series ES01 and ES03, Drawing Package)  Drainage Structures: Preliminary engineering design and construction features for drainage structures to be constructed. (Series DR01 and ES04, Drawing Package)  Topography: Existing topography with necessary detail of the Project Site and within 100 feet of the Project Site boundary. (Series ES01, Drawing Package)  Grading Plan: Grading plan showing the proposed topography including elevations, dimensions, location, extent and slope of all proposed Erosion and Sediment Control Plan River Edge Colorado, Garfield County, Colorado 5 clearing and grading including building site and driveway grades. (Series ES03 and ES04, Drawing Package)  Soil Stockpile and Snow Storage Areas: Probable locations of soil stockpiles and snow storage areas. (Series ES03, Drawing Package)  Drainage Plan: Proposed drainage plan. (Section IV of this Plan and ES03, Drawing Package)  Equipment Storage Areas: Location of storage areas designated for equipment, fuel, lubricants, chemical and waste storage with an explanation of spill containment structures. (Series ES03, Drawing Package)  Temporary Roads: Location of temporary roads designed for use during the construction period. (Series ES03, Drawing Package)  Areas of Steep Slope: Areas with slope of twenty (20) percent or greater by location and percentage of slope, both for the existing site conditions and within the developed area. (Series ES01 and ES03, Drawing Package)  Construction Schedule: Construction schedule indicating the anticipated starting and completion time periods of the Project Site grading and/or construction sequence including the installation and removal of erosion and sediment control measures, and the estimated duration of exposure of each area prior to the completion of temporary erosion and sediment control measures. (Section V.C of this Plan and Series ES03-04, Drawing Package)  Permanent Stabilization: A brief description of how the Project Site will be stabilized after construction is completed. (Section V.D of this Plan)  Erosion Control Measures: Plan view drawings of all erosion and sediment control measures showing approximate locations and site drainage patterns for construction phases and final design elements. (Section V of Plan and Series ES02-04, Drawing Package)  Estimated Cost: Estimated total cost (installation and maintenance) of the required temporary soil erosion and sediment control measures. (Section VI of this Plan)  Calculations: Calculations made for determining rainfall, runoff, sizing any sediment basins, diversions, conveyance or detention/retention facilities. (Section III.C and IV.B of this Plan)  Adjacent Land Uses: A description of neighboring areas with regard to land use and existing pertinent features such as lakes, streams, Erosion and Sediment Control Plan River Edge Colorado, Garfield County, Colorado 6 structures, roads, etc. (Section IV.A of this Plan and Series ES01, Drawing Package)  Stormwater Planning Concept: Description of the stormwater management planning concept for the Project Site, including both structural and non-structural Best Management Practices (BMPs). (Sections IV and V of this Plan)  Hydrology and Hydraulics: Hydrologic, hydraulic and all other calculations used to size and design drainage facilities and/or structural BMPs. (Sections IV.B of this Plan)  Maintenance: Requirements for all proposed BMPs discussed including access, schedules, costs, and designation of a responsible party. (Section V of this Plan).  SWMP: Copy of the Stormwater Management Plan application to CDPHE with date of submittal. (Appendix F of this Plan)  Signature Blocks: Signature block for owner or legal agent acknowledging the review and acceptance of responsibility, and a signature and stamped statement by the qualified individual acknowledging responsibility for the preparation of the Erosion and Sediment Control Plan. (Not included, required only as part of Final Plan or when construction is authorized) C. DESIGN STANDARDS The following standards and criteria were used in preparing the drawings, plans and reports:  ULUR;  2009 International Building Code (as amended by Garfield County);  Urban Storm Drainage Criteria Manual ("USDCM") dated June 2001, Urban Drainage and Flood Control District ("UDFCD"), Denver, Colorado; and  Colorado Floodplain and Stormwater Criteria Manual, dated 2006, Colorado Water Conservation Board; In addition, where certain necessary standards and criteria were not included as part of the local standards or where standards were not applicable due to site conditions or the proposed development program, state and federal codes and statewide or nationwide standards were utilized as an alternative. Where such state and federal standards and criteria specifically conflict with an applicable ULUR standard or criteria, modifications have been requested as part of the REC rezoning and preliminary plan application and are included as a part of the Rezoning and Subdivision Justification Report. Erosion and Sediment Control Plan River Edge Colorado, Garfield County, Colorado 7 D. FINDINGS Based on the preliminary information provided with and in support of this Plan, William S. Otero P.E. (Colorado Registration #32163) has determined through his direct involvement in the preparation of the document and the associated plans that the Project has been designed, and may be designed and constructed at the time of Final Plat, in a manner that meets or exceeds the general requirements presented in Sections 7-203, 7-204, 7-205,7-206, 7-207, 7-212.B, 7-303, and 7-701 of the ULUR. The design, as presented, includes two regulatory modifications with respect to storm drainage where in the opinion of the William S. Otero, Project Engineer site conditions and the Project benefit from an alternative standard being applied. The first modification is a request to use the USDCM, as amended, as the criteria for analysis and design of channels and hydraulic structures and primary guidance document for the selection and design of stormwater quality BMPs. This modification is being requested in an effort to clarify standards and specification that will be applied to the Project since the ULUR does not provide detailed criteria for "suburban" or "urban" forms of development and the USDCM is recognized as being one of the most comprehensive drainage criteria manuals available in the State of Colorado and has been used as the basis for the development of local drainage criteria manuals and in drainage design and review process by a wide variety of municipalities in the State from Grand Junction to Denver to Fort Collins. Without these criteria, the ULUR fails to provide adequate guidance and a design basis to address the types of development, conditions and infrastructure proposed. The USDCM is approved and accepted by the Colorado Department of Health Water Quality Control Division (CDPHE-WQCD) as a reasonable basis for design. The second modification is a request that only the Water Quality Capture Volume (WQCV), and not the total stormwater volume (i.e., quantity storage) required by the ULUR, be detained prior to discharge off the Project Site to either Cattle Creek or the Roaring Fork River. The primary reason for this request is that the Project Site is located at the confluences of the two major perennial waterways and detention of surface runoff at historic rates provides little value or could even be detrimental to these waterways since it delays the releases from the Project Site in a manner that could coincide with the peaks flows from larger contributing basins up stream (i.e., adding to the magnitude of the peak flow). If these larger stormwater volumes are not detained, the peak flows generated from the Project Site will be released prior to these other peaks entering the areas. Furthermore, stormwater runoff from the Project Site does not discharge to or impact adjacent properties or downstream drainage structures. Should the County believe that quantity storage in addition to quality storage is required, the storage volumes for both quantity and quality are provided herein and the area necessary to store this increased volume is available within the locations identified on the engineering plans to accommodate the volumes without any impact to lots within the Project. It is the opinion of William S. Otero, Project Engineer that detaining excess quantity volume is unproductive at best and potentially damaging to downstream areas at worst. Erosion and Sediment Control Plan River Edge Colorado, Garfield County, Colorado 8 II. PROJECT LOCATION AND DESCRIPTION A. PROJECT LOCATION The Project is located along State Highway 82 ("SH 82") between the City of Glenwood Springs and Town of Carbondale near the junction of County Road 110/113 ("CR 113") and SH 82. The property is located almost entirely west of the Roaring Fork Transit Authority ("RFTA") right-of-way and east of the Roaring Fork River and the Roaring Fork Conservancy ("RFC") Conservation Easement (i.e., Grant of Conservation Easement dated February 3, 2000, recorded at Reception Number 559036 and survey map, recorded December 24th, 2008, recorded at Reception Number 760571 in the real property records of Garfield County, Colorado). The Project straddles Cattle Creek which is also located within the RFC Conservation Easement. A vicinity map is provided as Exhibit 1 in Appendix A. The Project covers approximately 160 acres ("Project Site") as shown and described on the Project Site drawing [Exhibit 2(a-d), Appendix A]. The Project is proposed by Carbondale Investments, LLC ("CI"). B. PROJECT DESCRIPTION The Project is a proposal to create a walkable clustered-form of residential development with neighborhood amenities including naturalized open space and enhanced wildlife habitat, community recreation, parks, and neighborhood agriculture that is designed to serve the residents and preserve and provide reference to the rural character and agricultural roots of the Roaring Fork Valley. The Project aims to have a strong historic identity back to the days of ‘old Colorado’ when compact neighborhoods formed with a strong sense of community based on the land and surrounding landscape. The REC landscape aesthetic will be simple, informal, and place emphasis in the use of plant and landscape materials local, adaptable and appropriate to the climate and environment of the area. The Project will include approximately 366 residential units of various sizes and types including 55 affordable homes and one exclusive executive lot for a custom home. Housing types will range from attached homes to small single family attached and detached garden homes, village homes, and larger estate homes. Smaller garden homes are anticipated to be designed for younger residents that are looking for their first home in the County, while village homes and estate homes will provide move up opportunities for growing families. Densities in the Project are proposed at less than 2½ units per acre. Lot sizes will vary from over 1 acre to approximately 5,000 square feet for single family homes, and 1,700-5000 square feet of lot area for each garden home. Most of the units back to either proposed active parks or reclaimed open space to help enhance the connection to the land. The REC layout and design is depicted in the PUD Plan, PUD01-03 Series and the Preliminary Plan PRPN01-03 Series of the Drawing Package. The architectural theme will be complementary to the traditional architecture of the valley. Generally, exterior materials will include wood, stone, brick, stucco and cement board siding. Varied roof heights and articulation of the front elevations will be used to break up the massing and provide street-level appeal. Front porches and covered stoops are included on homes to emphasize the entry and connection to the sidewalk and street. Roofing will include dimensional shingles, metal, or other materials appropriate to the building style and that roofs will generally be pitched. Gables, wall plane and Erosion and Sediment Control Plan River Edge Colorado, Garfield County, Colorado 9 roofline articulation, bays, balconies, porches, canopies and arcades will be used in the design of various buildings. The selection of materials will minimize the exterior maintenance of the homes to help maintain a quality appearance for the long term. The street pattern and pedestrian network are designed to facilitate community interaction. Streets have detached sidewalks with designated cross walks at major intersections and landscaped areas that create a comfortable environment for walking. On‐street parking in most areas will further buffer vehicular and pedestrian uses. Internal circulation is maximized and dead‐end streets are limited. Alleys are used where appropriate to enhance the streetscape and achieve a mix of housing styles. A soft trail system is used to connect open spaces and other common elements with the sidewalk network. The homes are placed close to the streets to help define the streetscape space and provide visual interest to pedestrians. Street trees and plantings are proposed to enhance the aesthetics of the street. The community is served with a variety of recreational facilities and a neighborhood center that could include meeting room(s), fitness room, offices, kitchen, restrooms, recreational facilities, and limited community service use such as a day care facility, deli/coffee shop, or health club. Parks will provide informal recreational opportunities within the community and will likely include tot lots, playfields, and trail system. The west portion of the property is generally set aside as the naturalized area that buffers the RFC Conservation Easement along the Roaring Fork River. The soft trails around the property allow residents to enjoy the river and wetland areas without disrupting the environment in conformance with the terms of the RFC Conservation Easement. More than the minimum open space requirements will be met by the project. Nearly 50% of the Project Site is in some form of open space, common area or park. Finally, opportunities for productive and edible landscapes, including community gardens and neighborhood orchards are integrated and dispersed in between the residential land uses as gathering and focal places for residents connecting REC to its agricultural heritage. The combination of trails, recreation areas, and open space system with the ability to engage in ‘interactive community agriculture’ on a small scale will make REC a very desirable place to live, filling a unique niche not yet met in Garfield County. This unique combination will help establish a sense of place, foster community, and engage residents with their immediate environment. It is intended this overall outdoor focus will set the tone and become a major driver of the identity of REC. III. PLAN BASIS A. EXISTING SITE CONDITIONS The existing Project Site features/conditions and features/conditions immediately adjacent to the Project Site are shown on the Existing Conditions and Land Suitability Maps, EC01 Series of the Drawing Package. As specifically related to the requirements associated with this Plan as required by the ULUR, existing condition are also shown on the Erosion and Sediment Control Plan - Existing Conditions, ES01 Series of the Drawing Package. Erosion and Sediment Control Plan River Edge Colorado, Garfield County, Colorado 10 The Existing Conditions portion of this Plan (Erosion and Sediment Control Plan - Existing Conditions, ES01 Series of the Drawing Package) presents existing conditions related to erosion and sediment control and drainage on and immediately adjacent to the Project Site. The drawing also represents the basis for the pre-development hydrologic analysis used in development of this Plan. 1. RIVERS, CREEKS AND FLOODING The Roaring Fork River flows from south to north just west of the Project Site through the adjacent RFC Conservation Easement. The Roaring Fork River is a large perennial river with very large contributing basins to the south. The 160 acre Project Site is located mostly on nearly level river terraces that stand between about 50 to 80 feet above the river. No development is planned directly adjacent to the Roaring Fork River or within the required 35 foot setback under Section 7-203.A of the ULUR except as may be required in association with water and sanitary utilities as described in the plans and reports covering the design of such. The Roaring Fork River's relationship to the Project Site and existing floodplain is depicted on Erosion and Sediment Control Plan - Existing Conditions, ES01 Series of the Drawing Package. Cattle Creek crosses through the Project Site from east to west and roughly divides the property in half. Cattle Creek is a moderately sized perennial stream with a large contributing basin to the east. Cattle Creek joins the Roaring Fork River about mid-way along the western edge of the Project Site within the RFC Conservation Easement. No Development is planned directly adjacent to the Cattle Creek or within the 35 foot setback required by Section 7-203.A of the ULUR except a bridge crossing of Cattle Creek whose abutments are within the setback area and associated utilities crossing. Cattle Creek's relationship to the Project and existing floodplain is depicted on Erosion and Sediment Control Plan - Existing Conditions, ES01 Series of the Drawing Package. The Glenwood Ditch currently diverts water from the Roaring Fork River, south of the Aspen Glen development, to be used for land irrigation. The ditch is piped and enters the Project Site along the southeastern edge of the Project Site paralleling the RFTA Right-of-Way until it reaches Cattle Creek. From that point, it traverses the Project Site in a northwesterly direction and exits the Project Site prior to discharging back to the Roaring Fork River (See Existing Ditch alignment on Erosion and Sediment Control Plan - Existing Conditions, ES01 Series of the Drawing Package). The current design capacity of the ditch is approximately 50 cfs, of which the REC owns rights to approximately 12 cfs for land irrigation. A portion of the ditch is planned to be relocated as part of the Reclamation Plan (Phase 0, as presented in Appendix U of Impact Report). 2. WETLANDS The wetlands in the vicinity of the Project do not generally extend off the RFC Conservation Easement onto the Project Site except in very isolated areas at the southern end of the Project Site and along Cattle Creek, as presented in the Wetlands Delineation Report (see Appendix G). Wetlands are present along the Erosion and Sediment Control Plan River Edge Colorado, Garfield County, Colorado 11 entire length of the Roaring Fork River and Cattle Creek, as shown on Erosion and Sediment Control Plan - Existing Conditions, ES01 Series of the Drawing Package. Special consideration must be given to ensure erosion and sediment control BMPs are properly placed and maintained to minimize indirect impacts to wetlands. While temporary impacts are discussed in the Impact Analysis, no permanent impacts to wetlands are anticipated. 3. GROUNDWATER Groundwater is generally tied to the Roaring Fork River in the area. Hepworth- Pawlek Geotechncial ("HP Geotech") measured groundwater at depths of about 39 to 77 feet in various borings onsite (See Geotechnical Engineering Study, Appendix J of the Impact Analysis for additional information). Shallow groundwater can be expected closer to the Roaring Fork River and Cattle Creek in the lower alluvial terraces on the Project Site. HP Geotech also notes that shallow perched groundwater can occur in association with the substrates that occur on the Project Site during heavy rains where clay- lenses exist, although none are currently documented. 4. TOPOGRAPHY The topography in the area is shown by the contour lines on the Erosion and Sediment Control Plan - Existing Conditions, ES01 Series of the Drawing Package. These contours represent the existing contours that resulted from the grading activities conducted by Bair Chase in 2005 in association with the Sanders Ranch PUD. The proposed contours are shown on the Reclaimed Condition and Phased Condition, ES02-03 Series of the Drawing Package. The proposed contours will be put in place as part of pre-development reclamation of the Project Site (Phase 0) (See Reclamation Plan, Appendix U of the Impact Analysis). The proposed 160 acre development area is located mostly on nearly level river terraces that stand between about 50 to 80 feet above the Roaring Fork River. The terraces have an average down-valley slope of less than one percent. Steep escarpments separate the original terrace levels, although some have been removed in association with previous grading activities. These escarpments typically have slopes of up to 60 percent. The current topography is significantly modified due to past grading activities and agricultural activities for nearly 80 years before the most recent development activities. Special considerations must be taken in performing construction activities near steep escarpment areas as described in the Hazard Mitigation Plan. B. SPECIAL PLAN CONSIDE RATIONS The following sections present special considerations associated with preparing this Plan. Soils and geological conditions on the Project Site are two of the most critical components when preparing the development plan, site grading and drainage, and selecting best management practices (BMPs) to control erosion and sediment releases. Erosion and Sediment Control Plan River Edge Colorado, Garfield County, Colorado 12 1. SOILS The soils have been preliminarily evaluated by HP Geotech. The Geotechnical Engineering Study is provided as Appendix J of the Impact Analysis prepared by 8140 Partners, LLC. The following discussion concerning the soil conditions is summarized from the Geotechnical Engineering Study. The main landforms at the Project Site related to the Project Site's surficial materials include (1) post-glacial alluvial terraces along the Roaring Fork River and Cattle Creek, (2) Pinedale glacial outwash terraces along the Roaring Fork River and related alluvial terraces along Cattle Creek, and (3) coalescing alluvial fans. A small part of the Project Site is located on the post-glacial alluvial terraces and the remaining development area, except the Executive Lot at the south end of the Project Site sits on the Pinedale glacial outwash terraces. The Executive Lot and surrounding open space sit on an alluvial fan. The topsoil was stripped from most of the Project Site and stockpiled in 2005 by Bair Chase in association with the Sanders Ranch PUD approved by Garfield County. The areas stripped of topsoil and stockpile sites are shown on the Erosion and Sediment Control Plan - Existing Conditions, ES01 Series of the Drawing Package. The previous grading consists of both cut and fill areas. The fill areas are mostly composed of coarse-grained terrace alluvium. The terrace topsoil and upper fine-grained deposits were separated during grading and were placed in the soil stockpiles. The post-glacial terraces are located as two terraces. The lower terrace stands about 5 feet above the river and the higher terrace stands about 13 feet above the river. The alluvium is described as a clast-supported deposit of silty sand with occasional bouldery, pebble and cobble gravel interbedded and often overlain by sandy silt and silty sand. Shallow groundwater is expected to be present in these areas. The proposed development will be located on the higher Pinedale terraces. However, Roaring Fork River utility and Cattle Creek bridge and utility crossings will encounter these post-glacial terrace deposits. The Pinedale outwash terraces along the Roaring Fork River and the associated Cattle Creek terraces occur in several levels that formed at different periods. Grading in 2005 removed all of the mid level terraces. Essentially all of the proposed development within the REC PUD will be on the graded area (originally the fifth and sixth terraces) and on the third, fourth and seventh terrace levels. The alluvium under the Pinedale terraces associated with the Roaring Fork River and Cattle Creek are a clast-supported deposit of rounded gravel, cobbles and boulders in a silty sand matrix. Pedogenetic soil profiles are well developed in the Pinedale terraces. This indicates these surfaces have been stable with respect to erosion and deposition for over about 5,000 years. Soils are excessively cobbly and will be required to be sorted or screened when backfilling trenches. Imported bedding material may be required. Trenching is likely to be difficult and trench walls will require support or be laid back at 2 or 3:1 slopes to prevent failure during construction. Erosion and Sediment Control Plan River Edge Colorado, Garfield County, Colorado 13 2. GEOTECHNICAL CONDITIONS The geotechnical conditions and geologic hazards have been evaluated by HP Geotech. The Geotechnical Engineering Study is provided as Appendix J of the Impact Analysis prepared by 8140 Partners, LLC. Five primary hazards affecting the Project Site were identified in the Geotechnical Report, three of which are described below and were considered in preparing this Plan. These three hazards include evaporite sinkholes, steep terrace escarpments, and debris flows and floods. Their identified locations are shown the Erosion and Sediment Control Plan - Existing Conditions, ES01 Series of the Drawing Package. The following discussion concerning the geotechnical conditions and geologic hazards is summarized from the Geotechnical Engineering Study. a) Evaporite Si nkholes The entire Project Site is subject to potential sinkhole development as it is underlain by the Eagle Valley Evaporite. The evaporite between Carbondale and about 3 miles south of Glenwood Springs is part of the Roaring Fork diapir which forms the core of the north-trending Cattle Creek anticline. The west limb of the anticline in this part of the Roaring Fork River Valley coincides with the Grand Hogback monocline that marks the western limit of the Carbondale evaporite collapse center. HP Geotech notes that it is uncertain if the regional subsidence and evaporite deformation along the Roaring Fork diapir are still an active geomorphic process or if evaporite deformations have stopped. If still active, present deformations are likely occurring at rates similar to past long-term rates of between 0.5 and 1.6 inches per 100 years. These slow deformation rates should not present a potential risk to buildings and other facilities being considered at the Project Site. b) Steep Terrace Escarpments Steep terrace escarpments that commonly have slopes of about 60 percent and vary from 40 to 80 feet high are present along the Roaring Fork River and the lower reaches of Cattle Creek. These escarpments are potentially unstable and in some cases have been further destabilized due to piping associated with irrigation water from the previous agricultural activities on the Project Site. The escarpments are located along the western most property line and encroach into the RFC Conservation Easement. These areas can contribute to sediment production during rain and flood events or in association with excessive irrigation. c) Debris Flow and Floods With respect to debris flows and floods, HP Geotech notes that coalescing alluvial fans developed at the mouth of the numerous, small drainage basins on the east side of the Roaring Fork River Valley where the ephemeral streams discharge on terrace surfaces. Before construction of SH 82 and development to the east of the highway, the alluvial fan formed a Erosion and Sediment Control Plan River Edge Colorado, Garfield County, Colorado 14 continuous apron at the terrace-valley transition. Most of the upper parts of the fans have been removed by grading for these facilities. With the exception of the southernmost portion of the Project Site, the Project Site is not impacted by debris flows. Pedogenetic soil profiles in the fan deposits are mostly weakly. Swell-consolidation tests show that the deposits do not have a high collapse potential (settlement after wetting under a constant load) and are moderately compressible under increased loading after wetting. This indicates that the fans are geologically young landforms and are still potential sites of debris flow and flood deposition. C. HYDROLOGIC AND HYDRAULIC CRITERIA Although Garfield County does not have detailed drainage standards or criteria applicable to urban or suburban development within the ULIUR, UDFCD maintains and distributes the USDCM as a basis for stormwater and drainage design. The USDCM consists of three volumes: (1) Volume 1 and 2 provided guidance for planning and design of drainage channels and hydraulic structures; and (2) Volume 3 provides guidance for the selection and design of stormwater quality best management practices (BMPs). The UDFCD represents one of the most comprehensive drainage criteria manuals available in the State of Colorado and has been used as the basis for the development of local drainage criteria manuals and in drainage design and review processes by a wide variety of municipalities in the State from Grand Junction to Denver to Fort Collins. The USDCM is approved and accepted by the CDPHE-WQCD as a reasonable basis for design. This Plan utilizes the USDCM as the basis for hydraulic design and erosion and sediment control measures to support the design and construction of the REC PUD. The following sections provide the standards and criteria used in preparing this Plan. 1. RAINFALL SOURCE a) Rainfall I nput The rainfall input used in developing the runoff characteristics for the Project Site originated from the methodology in NOAA Atlas 2, Volume III for the 2-year to 100-year return frequency. The rainfall depths for six events are presented in Table 1. These values were developed using the NOAA methodology. Additional details are presented in Appendix B. Table 1: Rainfall Depth by Return Period (inches) Storm Duration (Minutes) Rainfall Depth (inches) by Return Period 2-Year 5-Year 10-Year 25-Year 50-Year 100-Year 5 0.18 0.25 0.30 0.37 0.43 0.49 10 0.27 0.39 0.47 0.57 0.66 0.75 15 0.35 0.50 0.60 0.72 0.84 0.95 30 0.48 0.69 0.83 1.00 1.17 1.32 60 0.61 0.87 1.05 1.27 1.48 1.67 Erosion and Sediment Control Plan River Edge Colorado, Garfield County, Colorado 15 b) Runoff M ethodology For the preliminary sizing of detention basins, culverts, conveyance channels and other drainage structures, the rational method was used. All basins within the Project Site are less than 90 acres. The portions of the developed areas planned for higher densities are more appropriately modeled as small urban watersheds. Therefore the rational method is appropriate for this application as well. Intensity-Duration-Frequency curves for the Project Site have been developed and are shown in Appendix C, Exhibit 1. The initial time of concentration for each basin is determined by the following equation: Ti = 1.8 x [(1.1-C5)L1/2]/S1/3 Where: Ti = the initial time of concentration in minutes C5 = the 5-year runoff coefficient L = the length of the flow path in feet (not to exceed 300 feet for urban and 500 feet for rural) S = the slope of the flow path in percent The channel time of concentration is determined by the velocity method outlined in Figure 7.2 of the CDOT Drainage Design Manual. The velocity is determined by the following equation: V = kS1/2 Where: V = the velocity in feet per second K = the land use/land cover factor S = the slope of the flow path in percent The time of concentration for channel flow is determined by the following equation: Tt = L/(60V) Where: Tt = the channel time of concentration in minutes Erosion and Sediment Control Plan River Edge Colorado, Garfield County, Colorado 16 L = the length of the flow path in feet V = the average velocity in feet per second D. HYDRAULIC CRITERIA 1. CONVEYANCE CHANNELS Conveyance channels are used in the REC PUD to collect and direct concentrated surface water flows towards permanent BMPs (i.e. detention and storm water quality basins). The specific criteria used to plan and preliminarily design these channels, and associated culverts, were obtained from the following:  Open channel conveyance - USDCM, Volume 1, Section 3.0  Grass swales - USDCM, Volume 3, Section 2.0  Culverts - USDCM, Volume 2, Chapter 9 2. STORM SEWERS Storm sewers and inlets will be designed, at a minimum, to convey the 10-year storm, with pipes 80 percent full. The specific criteria used to plan and preliminarily design these structures were obtained from USDCM, Volume 1, Chapter 6. Based on the preliminary information and USDCM criteria, all storm sewers are and may be designed and constructed to meet this standard. 3. ROAD FLOWS Flow in roads should be contained within the right-of-way for the 100-year storm and smaller events must be kept to a coverage area and depth that ensures the roads remain passable during these occurrences. Based on the preliminary information, the drainage and road system is and may be designed to meet this requirement in coordination with the emergency runoff conveyance discussed below. 4. EMERGENCY RUNOFF CONVEYANCE During large storm events (i.e. 100-year), the conveyance systems reach capacity and, in some cases, can become overloaded. During these events, the open space areas and common areas will work in coordination with the constructed systems to safety convey large storm event flows through the Project Site without causing significant damage to structures or potential for loss of life. Adequate space to accommodate conveyance is available and detailed grading can be accommodated. Details will be determined during Final Design. Erosion and Sediment Control Plan River Edge Colorado, Garfield County, Colorado 17 IV. GRADING AND DRAINAGE PLAN A. OVERALL CONCEPT The overall grading concept associated with the Project was developed based on the following primary goals:  Reclaim/restore the overall site from previously uncompleted golf course related grading and topsoil removal activities; and  Facilitate the development of the REC PUD while seeking to create a separation between human activity and adjoining wildlife conservation areas. Concurrently, the drainage concept associated with the Project was developed based on the following primary goals:  Manage surface water by conveying it through the Project Site towards outfalls located on Cattle Creek and the Roaring Fork River with limited ground infiltration; and  Manage surface water quality through the use of natural systems, where appropriate and consistent with geologic and soil conditions. The following sections present further detail about the proposed grading and drainage plan and comparisons of the pre- and post-development conditions based on the subbasins presented on the Erosion and Sediment Control Plan - Existing Conditions, ES01 Series of the Drawing Package. 1. GRADING AND DRAINAGE The northern portion of the Project Site was graded to generally direct surface water via channels, roads, and storm sewers to the southwest, while the southern portion of the Project Site was graded to generally direct surface water via channels, roads and storm sewers to the northwest. Three primary subbasins were identified and used for drainage calculations (see Appendix D, Exhibit 1). Understanding the planned characteristics (i.e. layout, slopes, density, and land use) of each subbasin assists in selecting the specific methodologies to be used for management of stormwater quantity and quality. For purposes of developing preliminary estimates of flow, a brief description of each subbasin is provided below:  North Basin 1 (P1) - Open space areas with passive recreation  North Basin 2 (P2) - Urban "clustered" residential development  South Basin 1 (P3) - Urban "clustered" residential development A runoff coefficient based on USDCM recommendations was selected for each subbasin and is provided in Table 2 as discussed in Section IV.B.1 of this Plan. Erosion and Sediment Control Plan River Edge Colorado, Garfield County, Colorado 18 2. OFF-SITE BASINS Runoff from offsite basins to the Project Site is very limited due to SH 82 running paralleling the east side of the southern end of Project Site and the RFTA Right-of-Way paralleling the east side of the north end of the Project Site. These two regional features intercept much of the offsite flow that would otherwise naturally drain onto the Project Site from the east. Other than very localize drainage captured by inlets and directed west via culverts from near the highway and the 43 acres parcel north and east of the Project Site of which only 50 percent of the area currently outfalls to the Project Site (OS-1), the offsite drainage is generally picked up by Cattle Creek prior to entering the Project Site. Therefore, offsite basins have little impact on the Project Site. The OS-1 basin is assumed to contain 23.6 acres of contributing area, and 50% impervious under post development conditions. No detention on the OS-1 basin is assumed to occur post-development. 3. SURROUNDING LAND USES As shown on Erosion and Sediment Control Plan - Existing Conditions, ES01 Series of the Drawing Package, the surrounding land uses range from vacant to small mixed commercial, a trailer park, and rural residential. None of these developments provide direct runoff to the Project Site nor do they have existing facilities that would be affected by the planned grading and drainage activities. The significant adjoining land uses with respect to drainage are associated with the RFTA Right-of-Way, SH 82, Cross Creek and the Roaring Fork River. 4. WATER QUANTITY AND QUALITY STORAGE There will be an increase in peak runoff rates from the Project Site relative to historic flows, as presented in part B below. However, given the size of the upstream basins (i.e. very small as compared to the basins contributing flows to Cattle Creek and the Roaring Fork River) and proximity of the Project Site to the outfall for Cattle Creek and Roaring Fork basins, it is being proposed that water quantity storage (i.e. runoff detention) not be provided in accordance with Section 7-207.C.1 of the ULUR. This is a modification from the existing County standards, but the planned approach has technical merit based on the particular site conditions present. The primary reason for this request is that the Project Site is located at the confluences of the two major perennial waterways and detention of surface runoff at historic rates provides little value or could even be detrimental to these waterways since it delays the releases from the Project Site in a manner that could coincide with the peaks flows from larger contributing basins up stream (i.e., adding to the magnitude of the peak flow). If these larger stormwater volumes are not detained, the peak flows generated from the Project Site will be released prior to these other peaks entering the areas. Furthermore, stormwater runoff from the Project Site does not discharge to or impact adjacent properties or downstream drainage structures. Should the County believe that quantity storage in addition to quality storage is required, the storage volumes for both quantity and quality are provided herein and the area necessary to store this increased volume is available within the locations Erosion and Sediment Control Plan River Edge Colorado, Garfield County, Colorado 19 identified on the engineering plans to accommodate the volumes without any impact to lots within the Project. B. SPECIFIC DETAILS 1. ONSITE BASINS The overall subbasin characteristics are discussed above. For purposes of developing preliminary estimates of flows, a runoff coefficient based on standard return periods for each subbasin is provided in Table 2 based on USDCM recommendations. Table 2: Runoff Coefficient (C) by Return Period Basin Percent Impervious Return Period 2-Year 5-Year 10-Year 25-Year 50-Year 100-Year P1 25 0.09 0.16 0.23 0.29 0.32 0.35 P2 40 0.19 0.25 0.30 0.35 0.38 0.41 P3 30 0.13 0.19 0.25 0.31 0.34 0.37 Based on the subbasin characteristics presented, the calculated peak flows for pre-development conditions at the outfalls are shown in Table 3. Table 3: Outfall Peak Flows by Return Period - Pre Development Conditions Basin Outfall Peak Flows (cfs) by Return Period 2-Year 5-Year 10-Year 25-Year 50-Year 100-Year P1 0.00 0.00 0.97 2.71 4.08 6.40 P2 0.00 0.00 2.11 5.90 8.91 13.86 P3 0.00 0.00 3.36 9.38 14.13 22.14 OS-1 0.00 0.00 1.10 3.06 4.62 7.17 Based on the subbasin characteristics presented, the calculated peak flows for post-development conditions at the outfalls are shown in Table 4. Detailed routing of smaller subbasins within areas of higher densities will be performed during final design at time of Final Plat. Erosion and Sediment Control Plan River Edge Colorado, Garfield County, Colorado 20 Table 4: Outfall Peak Flows by Return Period - Post Development Conditions Basin Outfall Peak Flows (cfs) by Return Period 2-Year 5-Year 10-Year 25-Year 50-Year 100-Year P1 1.27 3.08 5.29 7.75 9.65 13.23 P2 9.62 17.30 24.78 33.62 41.17 55.69 P3 8.27 16.50 25.88 37.38 46.22 63.05 OS-1 7.15 11.74 16.35 21.71 25.73 34.56 2. MAJOR DRAINAGEWAYS a) Roaring Fork River The Roaring Fork River flows from the south to north along the western edge of the Project Site. The existing floodplain is depicted on Erosion and Sediment Control Plan - Existing Conditions, ES01 Series of the Drawing Package. Flows at various return periods (or recurrence intervals) as shown in Table 5. A single Roaring Fork River crossing location is proposed in association with the Project. The crossing would include the installation of water and sewer utilities. Based on existing floodplain information, negligible permanent impact to the base flood elevations is expected. However, the installation of the utilities across the river will have temporary wetland and water quality impacts during construction. Discussions with the U.S. Army Corp of Engineers ("ACOE") relative to wetland impacts and associated permitting have been initiated and will be furthered as part of final design in association with first Final Plat. Table 5: Roaring Fork Flood Flows (cfs) by Return Period Return Periods (Years) Flows Upstream of Confluence w/ Cattle Creek (cfs) 10 12,000 50 17,000 100 19,200 500 25,000 b) Cattle Creek Cattle Creek bisects the property and runs in a northwesterly direction. The existing floodplain is depicted on Erosion and Sediment Control Plan - Existing Conditions, ES01 Series of the Drawing Package. Flows at various return periods (or recurrence intervals) as shown in Table 6. A single Cattle Creek crossing location is planned as part of the Project. The crossing will include both the construction of a vehicular/pedestrian bridge and installation of water, sewer and dry utilities. Based on existing floodplain information, negligible permanent impact to the base flood elevations is expected. However, the installation of the utilities across the creek will have temporary wetland and water quality impacts during construction. Discussions with the ACOE relative to wetland impacts and associated Erosion and Sediment Control Plan River Edge Colorado, Garfield County, Colorado 21 permitting have been initiated and will be furthered as part of final design in association with first Final Plat. Table 6: Cattle Creek Flood Flows (cfs) by Return Period Return Periods (Years) Flows Upstream of Confluence w/ Roaring Fork River (cfs) 10 2,100 50 2,550 100 2,850 500 4,400 c) Glenwood Ditch The Glenwood Ditch currently diverts water from the Roaring Fork River, south of the Aspen Glen development, to be used for land irrigation. The ditch is piped and enters the Project Site along the southeastern edge of the Project Site paralleling the RFTA Right-of-Way until it reaches Cattle Creek. From that point, it traverses the Project Site in a northwesterly direction until it exits the Project Site. The current design capacity of the ditch is approximately 50 cfs, of which the REC owns rights to approximately 12 cfs for land irrigation. A portion of the ditch is planned to be relocated as part of the Reclamation Plan (Phase 0). 3. WATER QUANTITY AND QUALITY STORAGE FACILITIES Based on the subbasin characteristics presented, calculated peak flows for pre- and post-development conditions at the outfalls were developed. Table 7 shows a comparison of these peak flows for each subbasin, the increase created by the post-development conditions, and the structure used to mitigate increased flows (if deemed necessary) and provide storage for the WQCV. Water quantity and quality storage facilities are designed based on the Rational Method for calculating runoff, the FAA methodology for calculating detention volumes, and Urban Drainage and Flood Control District's Storm Drainage Criteria Manual for calculating water quality capture volume. These calculations are shown in Appendix E. The drainage areas, historic 100-year inflow, and developed 100-year inflow for the ponds are shown in Table 7. Storage sizes are based on the developed and historic flows shown in Table 7. The rainfall intensities used in the calculations are from the NOAA method, and are based on the historic and developed time of concentrations. The runoff coefficients were estimated at 0.05 (10-yr) and 0.2 (100-yr) for pre-development conditions and 0.23 (10-yr P1), 0.30 (10-yr P2), 0.25 (10-yr P3), 0.35 (100-yr P1), 0.41 (100- yr P2) and 0.37 (100-yr P3) for post-development conditions, respectively. Inputs for calculating the historic and developed flows are shown in Appendix E. Erosion and Sediment Control Plan River Edge Colorado, Garfield County, Colorado 22 Table 7: Comparison of Pre- and Post-Development Outfalls Basin Outfalls (cfs) by Return Period Mitigation Pre-Development Post-Development Increase 10-Year 100-Year 10-Year 100-Year 10-Year 100-Year P1 0.97 6.40 5.29 13.23 4.32 6.83 NP1 P2 2.11 13.86 24.78 55.69 22.67 41.83 NP2 P3 3.36 22.14 25.88 63.05 22.52 40.91 SP1 OS-1 1.10 7.17 13.65 34.56 12.55 27.39 NP2/NP1 As stated above, this Plan does not include water storage for the purposes of runoff detention. However, Table 8 presents storage estimations developed for both water quantity (i.e. increased runoff) and quality (i.e. WQCV) should the County deem the combined storage as being required. To address the total combined storage, NP1 would be slightly enlarged to accommodate additional flow redirected from NP2, therefore, lessening the depth of NP1 to approximately 6 feet and increasing the depth of NP1 to approximately 6 feet. The planned approach of allowing the post-development runoff to outfall without detention is being proposed for the reasons stated above (Section IV.A.4) and not because it could not be accommodated. Rather, from the information available, it appears more technically appropriate to allow the peak flows from this Project Site to enter the Roaring Fork River prior to other peak flows generated higher in the contributing basin, thereby reducing the overall magnitude of the runoff peak experienced by the Roaring Fork River. Table 8: Estimated Storage Facility Volumes Storage Facility Total Required Combined Storage (cf) WQCV Only Required Storage (cf) Total Combined Storage Area (sf) Total Combined Storage Depth (ft) WQCV Only Storage Depth (ft) NP1 29,295 4,817 10,548 2.78 0.46 NP2 200,628 28,836 21,248 9.44 1.36 SP1 253,447 34,708 66,404 3.82 0.52 V. EROSION AND SEDIMENT CONTROL A. OVERALL CONCEPT Managing surface water quality requires a two pronged approach to ensure the release of surface water from the Project Site meets County requirements. The first prong requires the management of the Water Quality Capture Volume (WQCV) from impervious areas. The WQCV or "first flush" as it is sometimes referred to, contains the majority of the pollutants that accumulate between rain events. Managing the WQCV enhances stormwater quality prior to discharge to the receiving water (i.e. Cattle Creek and the Roaring Fork River). This Plan proposes the use of standard methodologies for Erosion and Sediment Control Plan River Edge Colorado, Garfield County, Colorado 23 management of the WQCV, which includes the use of permanent BMPs such as water quality storage facilities and conveyance channels. The second prong requires erosion and sediment control before, during, and after site development occurs. Controlling the release of sediment and reducing surface erosion requires the implementation of temporary and permanent, as well as structural and non-structural BMPs. The implementation of BMPs target either minimizing the release before it happens (i.e. vegetating of steep slopes) or capturing the release before discharge (i.e. sediment basin). This Plan proposes an aggressive approach to controlling erosion and sediment release during construction efforts through the installation and maintenance of USDCM recommended BMPs (i.e. silt fence, straw waddles, vehicle tracking controls, and culvert inlet and outlet controls). For purposes of clarity and coordination, the engineering drawings supporting this Plan (Series ES01-04 of the Drawing Package) have been broken up into four conditions, presenting the following information:  Existing Conditions: existing topography, areas of slopes greater than 20 percent, location of existing structures, waterbodies, hydrologic features, and drainage structures (Series ES01)  Reclaimed Conditions: interim topography, areas of slopes greater than 20 percent, and areas of revegetation (Series ES02)  Phased Conditions: probable locations of soil stockpiles and processing areas, equipment and materials storage areas, temporary roads, phased erosion control measures (temporary), and construction schedule (Series ES03)  Final Conditions: final topography, extent and grades of building sites, driveway grades, probable snow storage areas, and final erosion control measures (permanent) (Series ES 04) Each of the conditions is further explained in the following sections, except for the Existing Conditions which was previously discussed. The Reclaimed and Phased Conditions portions of this Plan are the basis for the required Stormwater Management Plan (SWMP) application to be submitted to the CDPHE as part of subsequent design efforts and prior to construction activities. See Appendix F for a draft copy of the application to be provided prior to the pre-development reclamation (Phase 0) and initiation of development construction. B. RECLAIMED CONDITIONS Although the Reclamation Plan (Appendix U of the Impact Analysis) includes relocating the RFTA trail and Glenwood Ditch, interim grading, and water storage facility construction, the primary focus of the Reclaimed Conditions portion of this Plan is to present the preliminary requirements for vegetation of disturbed areas with either permanent or temporary vegetation (See Erosion and Sediment Control Plan - Erosion and Sediment Control Plan River Edge Colorado, Garfield County, Colorado 24 Reclaimed Conditions, ES02 Series of the Drawing Package), as appropriate. The four primary approaches/schedules for vegetation activities include:  Open Space Areas: Permanent vegetation of the western portion of the Project Site, nearest the RFC Conservation Easement (see planting schedule in the Revegetation Plan, Appendix B of the Reclamation Plan and Open Space Plan, OS01 Series of the Drawing Package)  Common Areas: Temporary and permanent vegetation of the outer perimeter of the Project Site and temporary vegetation of the edges of the RFC Conservation Easement along Cattle Creek where community orchards and gardens are planned (see planting schedule in the Landscape Plan, LA01-05 Series of the Drawing Package)  RFTA Open Space Easement: Permanent vegetation within 50 foot open space easement as required by RFTA based on requirements of the current agreement (see planting schedule in the Landscape Plan, LA01- 05 Series of the Drawing Package)  Development Areas: Temporary vegetation (including a possible onsite nursery) in areas planned for future development (see planting schedule in the Revegetation Plan, Appendix B of the Reclamation Plan) As presented on the Reclaimed Conditions portion of this Plan (Erosion and Sediment Control Plan - Reclaimed Conditions, ES02 Series of the Drawing Package) and further presented on the Reclamation Plan (Reclamation Plan, RP01 Series of the Drawing Package), temporary erosion and sediment control BMPs (structural and non-structural) will also be installed and maintained throughout this Reclaimed Condition process. As required by the County, special considerations will be given to soil stockpile and processing areas and equipment and materials storage areas ensuring further protection is provided and sediment releases (including dust) are controlled. Specific procedures for spill control will be further detailed during the final design process. However, at a minimum, all chemical stored onsite will be properly containerized and secondary containment provided as necessary. C. PHASED CONDITIONS As shown on the schedule provided, the Phased Conditions will occur over a 7 year period (Erosion and Sediment Control Plan - Phased Conditions, ES03 Series of the Drawing Package). During that time, up to eleven different filings, consisting of an average of 50 units, will be final designed and submitted for Final Plat approvals. As shown, the construction activities will remain "liquid" and the erosion and sediment control measures will be modified, as necessary, to support the actions being performed at that time. In addition, until the disturbed areas are fully reclaimed (i.e. the vegetation is matured as specified) or the installed structure (i.e. culverts or storm sewers) is performing as specified, the BMPs installed with that particular phase of construction will continue to be maintained. As required by the County, special considerations will be given to soil stockpile and processing areas and equipment and materials storage areas ensuring further protection is provided and releases are controlled. Erosion and Sediment Control Plan River Edge Colorado, Garfield County, Colorado 25 As presented on the Erosion and Sediment Control Plan - Phased Conditions, ES03 Series of the Drawing Package, temporary erosion and sediment control BMPs (structural and non-structural) will be installed and maintained throughout this Phased Conditions process. As required by the County, special considerations will be given to soil stockpile areas and equipment and materials storage areas ensuring further protection is provided and sediment releases (including dust) are controlled. Specific procedures for spill control will be further detailed during the final design process. However, at a minimum, all chemical stored onsite will be properly containerized and secondary containment provided as necessary. D. FINAL CONDITIONS As the Project Site reaches development completion, the Final Conditions portion of this Plan will be implemented (See Erosion and Sediment Control Plan - Final Conditions, ES04 Series of the Drawing Package). The buildout conditions include final grading of building sites and driveways and the implementation of any remaining permanent erosion and sediment control BMPs and the removal of all temporary BMPs associated with development construction. As presented above, the primary permanent BMP is the construction of the three storage facilities during the reclamation phase (Phase 0). Other permanent BMPs such as channel vegetation and structures inlet and outlet protection will also be installed and maintained as part of overall community maintenance. Maintenance of the permanent structures has been planned for and easements provided to allow for continued access (See PUD Plan, PUD01-03 Series of the Drawing Package). In addition, an overall snow storage management program will be put into place to protect against the release of salt or sands used for traction from stored snow into drainage outfalls (i.e. Cattle Creek and the Roaring Fork River). As in all developments, the Project Site will continue to change to meet the ever changing needs of the community. As these changes occur and should land disturbance be required, general temporary erosion and sediment control BMPs should be installed to continue the protection of the surrounding surface water quality. At a minimum, the following BMPs should be installed, but specific BMPs for particular situations may also be required:  Install silt fence along the perimeter of disturbance area.  Install vehicle traction control measures where off-road vehicles enter paved areas.  Make water available for dust control and the removal of mud from equipment.  Cover all stockpiles soils materials. As indicated above, specific BMPs particular to a situation may be required. In addition, proper management of equipment and notifications to the community are also recommended. Erosion and Sediment Control Plan River Edge Colorado, Garfield County, Colorado 26 VI. COST ESTIMATE AND ME THOD OF FINANCING A cost analysis and estimate will be provided for erosion and sediment control under separate cover in conformance with Section 6-301C.8.r.(3) of the ULUR at the time of and in association with each Subdivision Application for Final Plat. The cost estimate shall include estimates for detailed erosion and sediment control as necessary to support the development of the lots being proposed for creation within the boundaries of the Final Plat being submitted for review. Based on the preliminary design submitted for review in association with the current rezoning and preliminary plan application supported by this Plan, preliminary costs have been developed and reviewed by 8140 Partners, LLC. These costs have been determined to be reasonable and support the feasibility of implementing the above proposed erosion and sediment control as part of the Project. Preliminary cost estimates are viewed by Carbondale Investments, LLC ("CI") as proprietary information and of limited or no value to the rezoning and preliminary plan review and approval process since no construction is specifically allowed nor is any construction security required by any such approval granted by Garfield County. VII. LIST OF REFERENCES Colorado Water Conservation Board, "Colorado Floodplain and Stormwater Criteria Manual," 2006. Federal Emergency Management Agency (FEMA), "Flood Insurance Study - Garfield County, Colorado" 1986. (Panel 1465 of 1900-No. 080205 1465B) U.S. Army Corps of Engineers, "Flood Frequency Analysis Program" (FFA version 3.1). U.S. Department of Commerce, National Oceanic and Atmospheric Administration, "NOAA Atlas 2, Precipitation-Frequency Atlas of the Western United States, Volume III", 1973. Urban Drainage and Flood Control District, "Urban Storm Drainage Criteria Manual Volumes 1-3." Erosion and Sediment Control Plan River Edge Colorado, Garfield County, Colorado APPENDIX A: VICINITY MAP AND PROJECT SITE DRAWINGS App. A-1 12/01/10VICINITY MAPExhibit:Date:8140 Partners, LLCTitle:Prepared by:Owner/Developer: Carbondale Investments, LLC7999 HWY 82Carbondale, CO 81623Phone No:970.456.5325App. A-2 Exhibit:Date:8140 Partners, LLCTitle:Prepared by:Owner/Developer: Carbondale Investments, LLC7999 HWY 82Carbondale, CO 81623Phone No:970.456.532512/01/10App. A-3 Exhibit:Date:8140 Partners, LLCTitle:Prepared by:Owner/Developer: Carbondale Investments, LLC7999 HWY 82Carbondale, CO 81623Phone No:970.456.532512/01/10App. A-4 Exhibit:Date:8140 Partners, LLCTitle:Prepared by:Owner/Developer: Carbondale Investments, LLC7999 HWY 82Carbondale, CO 81623Phone No:970.456.532512/01/10App. A-5 Exhibit:Date:8140 Partners, LLCTitle:Prepared by:Owner/Developer: Carbondale Investments, LLC7999 HWY 82Carbondale, CO 81623Phone No:970.456.532512/01/10App. A-6 Erosion and Sediment Control Plan River Edge Colorado, Garfield County, Colorado APPENDIX B: RAINFALL INPUT App. B-1 Project: Enter the elevation at the center of the watershed: Elev = 6,020 (input) 1. Rainfall Depth-Duration-Frequency Table Enter the 6-hour and 24-hour rainfall depths from the NOAA Atlas 2 Volume III in rightmost blue columns Return Period 5-min 10-min 15-min 30-min 1-hr 2-hr 3-hr 6-hr 24-hr (1)(2) (3) (4) (5) (6) (7) (8) (9) (10) output output output output output output output input input 2-yr 0.18 0.27 0.35 0.48 0.61 0.70 0.76 0.88 1.18 5-yr 0.25 0.39 0.50 0.69 0.87 0.98 1.05 1.18 1.50 10-yr 0.30 0.47 0.60 0.83 1.05 1.15 1.22 1.35 1.75 25-yr 0.37 0.57 0.72 1.00 1.27 1.38 1.46 1.60 2.10 50-yr 0.43 0.66 0.84 1.17 1.48 1.59 1.66 1.80 2.35 100-yr 0.49 0.75 0.95 1.32 1.67 1.78 1.86 2.00 2.56 Note:Refer to NOAA Atlas 2 Volume III isopluvial maps for 6-hr and 24-hr rainfall depths. 2. Rainfall Intensity-Duration-Frequency Table Return Period 5-min 10-min 15-min 30-min 1-hr 2-hr 3-hr 6-hr 24-hr (1)(2) (3) (4) (5) (6) (7) (8) (9) (10) output output output output output output output output output 2-yr 2.11 1.64 1.38 0.96 0.61 0.35 0.25 0.15 0.05 5-yr 3.04 2.36 1.99 1.38 0.87 0.49 0.35 0.20 0.06 10-yr 3.65 2.83 2.39 1.66 1.05 0.58 0.41 0.23 0.07 25-yr 4.42 3.43 2.90 2.01 1.27 0.69 0.49 0.27 0.09 50-yr 5.14 3.99 3.37 2.33 1.48 0.79 0.55 0.30 0.10 Rainfall Intensity in Inches Per Hour at Time Duration River Edge Colorado IDF Calculation IDF TABLE FOR ZONE TWO IN THE STATE OF COLORADO Zone 2: San Juan, Upper Rio Grande, Upper Colorado, and Gunnison River Basins, and Green River Basin below Confluence with the Yampa River Rainfall Depth in Inches at Time Duration 50 yr 5.14 3.99 3.37 2.33 1.48 0.79 0.55 0.30 0.10 100-yr 5.82 4.52 3.82 2.64 1.67 0.89 0.62 0.33 0.11 River Edge Colorado IDF Calculations 12/26/2010 1 of 2 Zone 2 App. B-2 2-yr 0 0 5-yr 2.42 0 10-yr 4.01 0 25-yr 6.02 0 50-yr 7.91 0 100-yr 9.69 0 0.61 0.87 1.05 1.27 1.48 1.67 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 Rainfall Depth in InchesOne-Hour Rainfall Depth Design Chart 0.61 0.87 1.05 1.27 1.48 1.67 2-yr 5-yr 10-yr 25-yr 50-yr 100-yr 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 Rainfall Depth in InchesReturn Period One-Hour Rainfall Depth Design Chart River Edge Colorado IDF Calculations 12/26/2010 2 of 2 Zone 2 App. B-3 Erosion and Sediment Control Plan River Edge Colorado, Garfield County, Colorado APPENDIX C: IDF CURVE DATA App. C-1 3.00 4.00 5.00 6.00 NTENSITY (in/hr)Figure INTENSITY-DURATION-FREQUENCY CURVES RIVER EDGE COLORADO Derived using NOAA Maps and Methodology 2-Year 5-Year 10-Year 25-Year 50-Year 0.00 1.00 2.00 3.00 4.00 5.00 6.00 0 20406080100120INTENSITY (in/hr)DURATION (min) Figure INTENSITY-DURATION-FREQUENCY CURVES RIVER EDGE COLORADO Derived using NOAA Maps and Methodology 2-Year 5-Year 10-Year 25-Year 50-Year 100-Year App. C-2 Erosion and Sediment Control Plan River Edge Colorado, Garfield County, Colorado APPENDIX D: BASIN DELINEATION MAP App. D-1 Figure: Date: 8140 Partners, LLC Title: Prepared by: Basin Boundary Map 01/14/2011 1 Owner/Developer: Carbondale Investments, LLC 7999 HWY 82 Carbondale, CO 81623 Phone No: 970.456.5325 App. D-2 Erosion and Sediment Control Plan River Edge Colorado, Garfield County, Colorado APPENDIX E: PRE- AND POST-DEVELOPMENT WATER STORAGE AND QUALITY DATA App. E-1 P1P2P3Roads and Alleys19,611 300,084 303,429 Average Lot Impervious Percentage 45.0%Sidewalk5,407 63,228 72,017 Neighborhood Center Impervious % 70.0%Open Space249,088 667,537 1,076,576Lots214,267 567,991 933,845Garden Homes0258,451 267,087Neighborhood CenterN/A 100,109 N/ATotal (sf)488,373 1,957,400 2,652,955Total (ac)11.2144.9460.90Total Impervious121,438 765,935 846,478% Impervious24.87%39.13%31.91%BASIN IDApp. E-2 % Impervious 2‐YR 5‐YR 10‐YR 25‐YR 50‐YR 100‐YR 0% 0 0 0.05 0.12 0.16 0.2 5% 0 0.02 0.1 0.16 0.2 0.24 10% 0 0.06 0.14 0.2 0.24 0.28 15% 0.02 0.1 0.17 0.23 0.27 0.3 20% 0.06 0.13 0.2 0.26 0.3 0.33 25% 0.09 0.16 0.23 0.29 0.32 0.35 30% 0.13 0.19 0.25 0.31 0.34 0.37 35% 0.16 0.22 0.28 0.33 0.36 0.39 40% 0.19 0.25 0.3 0.35 0.38 0.41 45% 0.22 0.27 0.33 0.37 0.4 0.43 50% 0.25 0.3 0.35 0.4 0.42 0.45 55% 0.29 0.33 0.38 0.42 0.45 0.47 60% 0.33 0.37 0.41 0.45 0.47 0.5 65% 0.37 0.41 0.45 0.49 0.51 0.53 70% 0.42 0.45 0.49 0.53 0.54 0.56 75% 0.47 0.5 0.54 0.57 0.59 0.61 80% 0.54 0.56 0.6 0.63 0.64 0.66 85% 0.61 0.63 0.66 0.69 0.7 0.72 90% 0.69 0.71 0.73 0.76 0.77 0.79 95% 0.78 0.8 0.82 0.84 0.85 0.86 100% 0.89 0.9 0.92 0.94 0.95 0.96 From UDFCD Criteria Manual Vol. I, Table RO‐5 River Edge Colorado Runoff Coefficients 12/26/2010 UDFCD Criteria ManualApp. E-3 River Edge ColoradoPut an X in the box for type of area.Pre-development ConditionsUrbanRural xTYPE RURALTotal Area Total Area Total AreaSurface Type 1Average Average Average Average Average AverageBasin sf acres sq mi C2 C5 C10 C25 C50 C100Area C2 C5 C10 C25 C50 C100P1 428,079 9.83 0.0154 0.00 0.00 0.05 0.12 0.16 0.20 428,079 0.00 0.00 0.05 0.12 0.16 0.20P2 1,955,161 44.88 0.070 0.00 0.00 0.05 0.12 0.16 0.20 1,955,161 0.00 0.00 0.05 0.12 0.16 0.20P3 2,652,955 60.90 0.0952 0.00 0.00 0.05 0.12 0.16 0.20 2,652,955 0.00 0.00 0.05 0.12 0.16 0.20OS-FUT-1 1,028,020 23.60 0.0369 0.00 0.00 0.05 0.12 0.16 0.20 1,028,020 0.00 0.00 0.05 0.12 0.16 0.20Average Channel Velocity 1.4 ft/sAverage Slope 0.02 ft/ft(If Elevations are used, this will be ignored)Notes:Q25, Q50 & Q100 are based on C1001) Velocity is from CDOT DDM Figure 7.2 (V = kS0.5)2) CDOT DDM Section 7.3.3 (pg 7-9) Ti = 0.395 (1.1-C5)D0.5/(S0.33)3) CDOT DDM Section 7.3.3 (pg 7-9) Tt = L / (60 V)4)k0.250.500.700.901.001.502.00 Paved area (sheet flow) & shallow gutter flow.Fallow or minimum tillage cultivationShort grass pasture and lawnsCultivated straight rowLand Use/Flow RegimeForest with heavy ground litter and meadowNearly bare groundGrassed waterwayRiver Edge ColoradoPre-Development Runoff Calculations1/13/20111 of 3Rational MethodApp. E-4 River Edge ColoradoPre-development ConditionsTotal Area Total Area Total AreaBasin sf acres sq miP1 428,079 9.83 0.0154P2 1,955,161 44.88 0.070P3 2,652,955 60.90 0.0952OS-FUT-1 1,028,020 23.60 0.0369Note: Rural areas have a maximum distance of 500 ft for overland flow and a minimum tc of 10 min.Urban areas have a maximum distance of 300 ft for overland flow and a minimum tc of 5 min.Also in urban area the tc shall not exceed the total length/180+10 min.Initial Length High Point Low Point Average Channel flow High Point Low Point AverageLand Cover4Velocity1Initial Tc2Channel Tc3Total Tcft Elevation Elevation Slope Length ft Elevation Elevation Slope Factor (k) fps min min min300.00 6016.00 6013.00 0.010 1161.00 6013.00 5986.00 0.023 0.90 1.37 7.53 14.10 21.62300.00 6018.00 6016.00 0.007 2307.00 6016.00 6004.00 0.005 0.90 0.65 8.61 59.24 67.85300.00 6031.50 6028.00 0.012 2925.00 6028.00 5989.50 0.013 0.90 1.03 7.15 47.21 54.36150.00 6034.00 6032.00 0.013 1948.00 6032.00 6026.00 0.003 0.90 0.50 4.83 65.00 69.84River Edge ColoradoPre-Development Runoff Calculations1/13/20112 of 3Rational MethodApp. E-5 River Edge ColoradoPre-development ConditionsTotal Area Total Area Total AreaBasin sf acres sq miP1 428,079 9.83 0.0154P2 1,955,161 44.88 0.070P3 2,652,955 60.90 0.0952OS-FUT-1 1,028,020 23.60 0.0369Calculation by J. Adams/W. Oteroi2 Q2 i5 Q5 i10 Q10 i25 Q25 i50 Q50 i100 Q100in/hr cfs in/hr cfs in/hr cfs in/hr cfs in/hr cfs in/hr cfs1.210.001.660.001.980.972.302.712.604.083.256.400.580.000.790.000.942.111.105.901.248.911.5413.860.680.000.930.001.103.361.289.381.4514.131.8222.140.570.000.780.000.931.101.083.061.224.621.527.1720-Nov-10River Edge ColoradoPre-Development Runoff Calculations1/13/20113 of 3Rational MethodApp. E-6 River Edge ColoradoPut an X in the box for type of area.Post-development ConditionsUrbanxRuralTYPE URBANTotal Area Total Area Total Area Surface Type 1 Average Average Average Average Average AverageBasin sf acres sq mi C2 C5 C10 C25 C50 C100Area C2 C5 C10 C25 C50 C100P1 428,079 9.83 0.0154 0.09 0.16 0.23 0.29 0.32 0.35 428,079 0.09 0.16 0.23 0.29 0.32 0.35P2 1,955,161 44.88 0.070 0.19 0.25 0.3 0.35 0.38 0.41 1,955,161 0.19 0.25 0.30 0.35 0.38 0.41P3 2,652,955 60.90 0.0952 0.13 0.19 0.25 0.31 0.34 0.37 2,652,955 0.13 0.19 0.25 0.31 0.34 0.37OS-FUT-1 1,028,020 23.60 0.0369 0.25 0.30 0.35 0.40 0.42 0.45 1,028,020 0.25 0.30 0.35 0.40 0.42 0.45N-SUB-1 337,038 7.74 0.012 0.25 0.30 0.35 0.40 0.42 0.45 337,038 0.25 0.30 0.35 0.40 0.42 0.45N-SUB-2 98,668 2.27 0.004 0.25 0.30 0.35 0.40 0.42 0.45 98,668 0.25 0.30 0.35 0.40 0.42 0.45S-SUB-1 187,306 4.30 0.007 0.25 0.30 0.35 0.40 0.42 0.45 187,306 0.25 0.30 0.35 0.40 0.42 0.45S-SUB-2 325,754 7.48 0.012 0.25 0.30 0.35 0.40 0.42 0.45 325,754 0.25 0.30 0.35 0.40 0.42 0.45Average Channel Velocity 1.4 ft/sAverage Slope 0.02 ft/ft(If Elevations are used, this will be ignored)Notes:Q25, Q50 & Q100 are based on C1001) Velocity is from CDOT DDM Figure 7.2 (V = kS0.5)2) CDOT DDM Section 7.3.3 (pg 7-9) Ti = 0.395 (1.1-C5)D0.5/(S0.33)3) CDOT DDM Section 7.3.3 (pg 7-9) Tt = L / (60 V)4)k0.250.500.700.901.001.502.00 Paved area (sheet flow) & shallow gutter flow.Fallow or minimum tillage cultivationShort grass pasture and lawnsCultivated straight rowLand Use/Flow RegimeForest with heavy ground litter and meadowNearly bare groundGrassed waterwayRiver Edge ColoradoPost-Development Runoff Calculations1/13/20111 of 3Rational MethodApp. E-7 River Edge ColoradoPost-development ConditionsTotal Area Total Area Total AreaBasin sf acres sq miP1 428,079 9.83 0.0154P2 1,955,161 44.88 0.070P3 2,652,955 60.90 0.0952OS-FUT-1 1,028,020 23.60 0.0369N-SUB-1 337,038 7.74 0.012N-SUB-2 98,668 2.27 0.004S-SUB-1 187,306 4.30 0.007S-SUB-2 325,754 7.48 0.012Note: Rural areas have a maximum distance of 500 ft for overland flow and a minimum tc of 10 min.Urban areas have a maximum distance of 300 ft for overland flow and a minimum tc of 5 min.Also in urban area the tc shall not exceed the total length/180+10 min.Initial Length High Point Low Point Average Channel flow High Point Low Point AverageLand Cover4Velocity1Initial Tc2Channel Tc3Total Tcft Elevation Elevation Slope Length ft Elevation Elevation Slope Factor (k) fps min min min300.00 6016.00 6013.00 0.010 1161.00 6013.00 5986.00 0.023 1.50 2.29 6.43 8.46 14.89300.00 6018.00 6016.00 0.007 2307.00 6016.00 6004.00 0.005 1.50 1.08 6.66 35.54 24.48300.00 6031.50 6028.00 0.012 2925.00 6028.00 5989.50 0.013 1.50 1.72 5.91 28.33 27.92150.00 6034.00 6032.00 0.013 1948.00 6032.00 6026.00 0.003 2.00 1.11 3.52 29.25 21.660.020 0.00 0.00 0.00 5.000.020 0.00 0.00 0.00 5.000.020 0.00 0.00 0.00 5.000.020 0.00 0.00 0.00 5.00River Edge ColoradoPost-Development Runoff Calculations1/13/20112 of 3Rational MethodApp. E-8 River Edge ColoradoPost-development ConditionsTotal Area Total Area Total AreaBasin sf acres sq miP1 428,079 9.83 0.0154P2 1,955,161 44.88 0.070P3 2,652,955 60.90 0.0952OS-FUT-1 1,028,020 23.60 0.0369N-SUB-1 337,038 7.74 0.012N-SUB-2 98,668 2.27 0.004S-SUB-1 187,306 4.30 0.007S-SUB-2 325,754 7.48 0.012Calculation by J. Adams/W. Oteroi2 Q2 i5 Q5 i10 Q10 i25 Q25 i50 Q50 i100 Q100in/hr cfs in/hr cfs in/hr cfs in/hr cfs in/hr cfs in/hr cfs1.431.271.963.082.345.292.727.753.079.653.8513.231.139.621.5417.301.8424.782.1433.622.4141.173.0355.691.048.271.4316.501.7025.881.9837.382.2346.222.8063.051.217.151.6611.741.9816.352.3021.712.6025.733.2534.562.114.082.896.713.459.344.0012.384.5214.695.6619.712.111.192.891.643.451.954.003.624.524.305.665.772.112.272.893.113.453.714.006.884.528.165.6610.952.113.942.895.403.456.454.0011.974.5214.205.6619.0520-Nov-10River Edge ColoradoPost-Development Runoff Calculations1/13/20113 of 3Rational MethodApp. E-9 Existing CIAQ in/hr acres cfs 0.20 3.25 9.8 6 Proposed input CIAQ constant in/hr acres cfs calculated 0.35 3.85 9.8 13 from other cell C values from typical tables for Rational Method coefficients I values from NOAA River Edge Colorado Water Quality and Quantity Storage Calculations 12/26/2010 1 of 5 Rat Method NP1 App. E-10 Based on FAA method in Handbook of Hydrology, p. 28.27 Qout = 6.39 cfs (historic)Impervious Ratio 0.25 Qin = 13.25 cfs (developed)Drain Time (hr)40 Qout/Qin = 0.48 WQCV (in)0.135 From UDFCD Manual Vol. 3 Figure EDB-2 k = 1.50 (from graph)storage factor (sf)1 Runoff coeff % Impervious Area storm duration Rainfall intensity Runoff Volume Outflow Volume Storage Volume WQ Volume Total input C I A T I CIAT k(Qout)T runoff minus outflow (WQCV/12)*A*sf constant acres min in/hr cu ft cu ft cu ft cu ft cu ft calculated 0.93 90 9.8 5 5.39 14,906 2,875 12,030 4,817 16,848 from other cell 0.93 90 9.8 6 5.15 17,090 3,450 13,640 4,817 18,457 0.93 90 9.8 7 4.91 19,010 4,025 14,984 4,817 19,801 0.93 90 9.8 8 4.67 20,663 4,600 16,063 4,817 20,880 0.93 90 9.8 9 4.43 22,051 5,175 16,876 4,817 21,693 0.93 90 9.8 10 4.19 23,174 5,751 17,424 4,817 22,241 0.93 90 9.8 11 4.06 24,689 6,326 18,363 4,817 23,180 0.93 90 9.8 12 3.93 26,057 6,901 19,156 4,817 23,973 0.93 90 9.8 13 3.79 27,279 7,476 19,804 4,817 24,621 0.93 90 9.8 14 3.66 28,356 8,051 20,305 4,817 25,122 0.93 90 9.8 15 3.53 29,286 8,626 20,660 4,817 25,477 0.93 90 9.8 16 3.46 30,601 9,201 21,400 4,817 26,217 0.93 90 9.8 17 3.39 31,837 9,776 22,061 4,817 26,878 0.93 90 9.8 18 3.31 32,993 10,351 22,642 4,817 27,459 0.93 90 9.8 19 3.24 34,069 10,926 23,143 4,817 27,960 0.93 90 9.8 20 3.17 35,066 11,501 23,564 4,817 28,382 0.93 90 9.8 21 3.10 35,983 12,076 23,906 4,817 28,724 0.93 90 9.8 22 3.03 36,820 12,651 24,169 4,817 28,986 0.93 90 9.8 23 2.95 37,578 13,226 24,351 4,817 29,169 0.93 90 9.8 24 2.88 38,256 13,801 24,454 4,817 29,272 0.93 90 9.8 25 2.81 38,854 14,376 24,478 4,817 29,295 0.93 90 9.8 26 2.74 39,373 14,951 24,422 4,817 29,239 0.93 90 9.8 27 2.67 39,812 15,526 24,286 4,817 29,103 River Edge Colorado Water Quality and Quantity Storage Calculations 12/26/2010 2 of 5 FAA detentn NP1 App. E-11 0.93 90 9.8 28 2.59 40,172 16,102 24,070 4,817 28,887 0.93 90 9.8 29 2.52 40,452 16,677 23,775 4,817 28,592 0.93 90 9.8 30 2.45 40,652 17,252 23,400 4,817 28,217 0.93 90 9.8 31 2.42 41,492 17,827 23,666 4,817 28,483 0.93 90 9.8 32 2.39 42,300 18,402 23,898 4,817 28,715 0.93 90 9.8 33 2.36 43,074 18,977 24,097 4,817 28,915 0.93 90 9.8 34 2.33 43,815 19,552 24,264 4,817 29,081 0.93 90 9.8 35 2.30 44,523 20,127 24,396 4,817 29,214 0.93 90 9.8 36 2.27 45,198 20,702 24,496 4,817 29,313 0.93 90 9.8 37 2.24 45,840 21,277 24,563 4,817 29,380 0.93 90 9.8 38 2.21 46,448 21,852 24,596 4,817 29,413 0.93 90 9.8 39 2.18 47,023 22,427 24,596 4,817 29,413 0.93 90 9.8 40 2.15 47,565 23,002 24,563 4,817 29,380 0.93 90 9.8 41 2.12 48,074 23,577 24,497 4,817 29,314 0.93 90 9.8 42 2.09 48,550 24,152 24,397 4,817 29,215 0.93 90 9.8 43 2.06 48,992 24,727 24,265 4,817 29,082 0.93 90 9.8 44 2.03 49,402 25,302 24,099 4,817 28,916 0.93 90 9.8 45 2.00 49,778 25,877 23,900 4,817 28,717 0.93 90 9.8 46 1.97 50,121 26,453 23,668 4,817 28,485 0.93 90 9.8 47 1.94 50,430 27,028 23,403 4,817 28,220 0.93 90 9.8 48 1.91 50,707 27,603 23,104 4,817 27,921 0.93 90 9.8 49 1.88 50,950 28,178 22,772 4,817 27,590 0.93 90 9.8 50 1.85 51,160 28,753 22,408 4,817 27,225 0.93 90 9.8 51 1.82 51,337 29,328 22,010 4,817 26,827 0.93 90 9.8 52 1.79 51,481 29,903 21,578 4,817 26,395 0.93 90 9.8 53 1.76 51,592 30,478 21,114 4,817 25,931 0.93 90 9.8 54 1.73 51,669 31,053 20,616 4,817 25,433 0.93 90 9.8 55 1.70 51,713 31,628 20,085 4,817 24,903 0.93 90 9.8 56 1.67 51,725 32,203 19,521 4,817 24,339 0.93 90 9.8 57 1.64 51,702 32,778 18,924 4,817 23,741 0.93 90 9.8 58 1.61 51,647 33,353 18,294 4,817 23,111 River Edge Colorado Water Quality and Quantity Storage Calculations 12/26/2010 3 of 5 FAA detentn NP1 App. E-12 0.93 90 9.8 59 1.58 51,559 33,928 17,630 4,817 22,448 0.93 90 9.8 60 1.55 51,437 34,503 16,934 4,817 21,751 0.93 90 9.8 61 1.54 51,917 35,078 16,839 4,817 21,656 0.93 90 9.8 62 1.53 52,386 35,653 16,732 4,817 21,549 0.93 90 9.8 63 1.52 52,841 36,228 16,613 4,817 21,430 0.93 90 9.8 64 1.51 53,285 36,804 16,481 4,817 21,299 0.93 90 9.8 65 1.49 53,716 37,379 16,337 4,817 21,155 0.93 90 9.8 66 1.48 54,135 37,954 16,181 4,817 20,998 0.93 90 9.8 67 1.47 54,541 38,529 16,013 4,817 20,830 0.93 90 9.8 68 1.46 54,935 39,104 15,832 4,817 20,649 0.93 90 9.8 69 1.45 55,317 39,679 15,638 4,817 20,455 0.93 90 9.8 70 1.44 55,686 40,254 15,433 4,817 20,250 0.93 90 9.8 71 1.43 56,043 40,829 15,215 4,817 20,032 0.93 90 9.8 72 1.42 56,388 41,404 14,984 4,817 19,801 0.93 90 9.8 73 1.40 56,720 41,979 14,741 4,817 19,559 0.93 90 9.8 74 1.39 57,040 42,554 14,486 4,817 19,304 0.93 90 9.8 75 1.38 57,348 43,129 14,219 4,817 19,036 0.93 90 9.8 76 1.37 57,643 43,704 13,939 4,817 18,756 0.93 90 9.8 77 1.36 57,926 44,279 13,647 4,817 18,464 0.93 90 9.8 78 1.35 58,197 44,854 13,342 4,817 18,160 0.93 90 9.8 79 1.34 58,455 45,429 13,026 4,817 17,843 0.93 90 9.8 80 1.33 58,701 46,004 12,696 4,817 17,514 0.93 90 9.8 81 1.32 58,934 46,579 12,355 4,817 17,172 0.93 90 9.8 82 1.30 59,155 47,155 12,001 4,817 16,818 0.93 90 9.8 83 1.29 59,364 47,730 11,635 4,817 16,452 0.93 90 9.8 84 1.28 59,561 48,305 11,256 4,817 16,073 0.93 90 9.8 85 1.27 59,745 48,880 10,865 4,817 15,682 0.93 90 9.8 86 1.26 59,916 49,455 10,462 4,817 15,279 0.93 90 9.8 87 1.25 60,076 50,030 10,046 4,817 14,863 0.93 90 9.8 88 1.24 60,223 50,605 9,618 4,817 14,435 0.93 90 9.8 89 1.23 60,358 51,180 9,178 4,817 13,995 River Edge Colorado Water Quality and Quantity Storage Calculations 12/26/2010 4 of 5 FAA detentn NP1 App. E-13 0.93 90 9.8 90 1.22 60,480 51,755 8,725 4,817 13,542 0.93 90 9.8 91 1.20 60,590 52,330 8,260 4,817 13,077 0.93 90 9.8 92 1.19 60,687 52,905 7,782 4,817 12,600 0.93 90 9.8 93 1.18 60,773 53,480 7,293 4,817 12,110 0.93 90 9.8 94 1.17 60,846 54,055 6,790 4,817 11,608 0.93 90 9.8 95 1.16 60,906 54,630 6,276 4,817 11,093 0.93 90 9.8 96 1.15 60,954 55,205 5,749 4,817 10,566 0.93 90 9.8 97 1.14 60,990 55,780 5,210 4,817 10,027 0.93 90 9.8 98 1.13 61,014 56,355 4,658 4,817 9,476 0.93 90 9.8 99 1.11 61,025 56,930 4,094 4,817 8,912 0.93 90 9.8 100 1.10 61,024 57,506 3,518 4,817 8,335 0.93 90 9.8 101 1.09 61,010 58,081 2,930 4,817 7,747 0.93 90 9.8 102 1.08 60,984 58,656 2,329 4,817 7,146 0.93 90 9.8 103 1.07 60,946 59,231 1,715 4,817 6,533 0.93 90 9.8 104 1.06 60,895 59,806 1,090 4,817 5,907 0.93 90 9.8 105 1.05 60,832 60,381 452 4,817 5,269 0.93 90 9.8 106 1.04 60,757 60,956 -199 4,817 4,618 0.93 90 9.8 107 1.03 60,669 61,531 -861 4,817 3,956 0.93 90 9.8 108 1.01 60,569 62,106 -1,537 4,817 3,281 0.93 90 9.8 109 1.00 60,457 62,681 -2,224 4,817 2,593 0.93 90 9.8 110 0.99 60,332 63,256 -2,924 4,817 1,893 0.93 90 9.8 111 0.98 60,195 63,831 -3,636 4,817 1,181 0.93 90 9.8 112 0.97 60,046 64,406 -4,360 4,817 457 0.93 90 9.8 113 0.96 59,884 64,981 -5,097 4,817 -280 0.93 90 9.8 114 0.95 59,710 65,556 -5,846 4,817 -1,029 0.93 90 9.8 115 0.94 59,523 66,131 -6,608 4,817 -1,791 0.93 90 9.8 116 0.92 59,325 66,706 -7,382 4,817 -2,565 0.93 90 9.8 117 0.91 59,113 67,281 -8,168 4,817 -3,351 0.93 90 9.8 118 0.90 58,890 67,856 -8,967 4,817 -4,149 0.93 90 9.8 119 0.89 58,654 68,432 -9,778 4,817 -4,960 0.93 90 9.8 120 0.88 58,406 69,007 -10,601 4,817 -5,784 River Edge Colorado Water Quality and Quantity Storage Calculations 12/26/2010 5 of 5 FAA detentn NP1 App. E-14 Existing CIAQ in/hr acres cfs 0.20 1.54 44.9 14 Proposed input CIAQ constant in/hr acres cfs calculated 0.41 3.03 44.9 56 from other cell C values from typical tables for Rational Method coefficients I values from NOAA River Edge Colorado Water Quality and Quantity Storage Calculations 12/26/2010 1 of 5 Rat Method NP2 App. E-15 Based on FAA method in Handbook of Hydrology, p. 28.27 Qout = 13.82 cfs (historic)Impervious Ratio 0.39 Qin = 55.75 cfs (developed)Drain Time (hr)40 Qout/Qin = 0.25 WQCV (in)0.177 From UDFCD Manual Vol. 3 Figure EDB-2 k = 1.50 (from graph)storage factor (sf)1 Runoff coeff % Impervious Area storm duration Rainfall intensity Runoff Volume Outflow Volume Storage Volume WQ Volume Total input C I A T I CIAT k(Qout)T runoff minus outflow (WQCV/12)*A*sf constant acres min in/hr cu ft cu ft cu ft cu ft cu ft calculated 0.93 90 44.9 5 5.39 68,053 6,220 61,833 28,836 90,669 from other cell 0.93 90 44.9 6 5.15 78,028 7,464 70,563 28,836 99,399 0.93 90 44.9 7 4.91 86,790 8,709 78,082 28,836 106,918 0.93 90 44.9 8 4.67 94,340 9,953 84,388 28,836 113,224 0.93 90 44.9 9 4.43 100,679 11,197 89,482 28,836 118,318 0.93 90 44.9 10 4.19 105,805 12,441 93,364 28,836 122,200 0.93 90 44.9 11 4.06 112,719 13,685 99,034 28,836 127,870 0.93 90 44.9 12 3.93 118,966 14,929 104,037 28,836 132,873 0.93 90 44.9 13 3.79 124,547 16,173 108,374 28,836 137,209 0.93 90 44.9 14 3.66 129,461 17,417 112,044 28,836 140,879 0.93 90 44.9 15 3.53 133,708 18,661 115,047 28,836 143,883 0.93 90 44.9 16 3.46 139,713 19,905 119,808 28,836 148,643 0.93 90 44.9 17 3.39 145,354 21,149 124,205 28,836 153,041 0.93 90 44.9 18 3.31 150,632 22,393 128,238 28,836 157,074 0.93 90 44.9 19 3.24 155,546 23,637 131,908 28,836 160,744 0.93 90 44.9 20 3.17 160,096 24,881 135,215 28,836 164,050 0.93 90 44.9 21 3.10 164,283 26,126 138,157 28,836 166,993 0.93 90 44.9 22 3.03 168,106 27,370 140,736 28,836 169,572 0.93 90 44.9 23 2.95 171,565 28,614 142,952 28,836 171,787 0.93 90 44.9 24 2.88 174,661 29,858 144,803 28,836 173,639 0.93 90 44.9 25 2.81 177,393 31,102 146,292 28,836 175,127 0.93 90 44.9 26 2.74 179,762 32,346 147,416 28,836 176,252 0.93 90 44.9 27 2.67 181,767 33,590 148,177 28,836 177,013 River Edge Colorado Water Quality and Quantity Storage Calculations 12/26/2010 2 of 5 FAA detentn NP2 App. E-16 0.93 90 44.9 28 2.59 183,408 34,834 148,574 28,836 177,410 0.93 90 44.9 29 2.52 184,686 36,078 148,608 28,836 177,444 0.93 90 44.9 30 2.45 185,600 37,322 148,278 28,836 177,114 0.93 90 44.9 31 2.42 189,438 38,566 150,872 28,836 179,708 0.93 90 44.9 32 2.39 193,125 39,810 153,315 28,836 182,151 0.93 90 44.9 33 2.36 196,660 41,054 155,606 28,836 184,442 0.93 90 44.9 34 2.33 200,044 42,299 157,746 28,836 186,582 0.93 90 44.9 35 2.30 203,276 43,543 159,734 28,836 188,570 0.93 90 44.9 36 2.27 206,357 44,787 161,571 28,836 190,406 0.93 90 44.9 37 2.24 209,286 46,031 163,256 28,836 192,091 0.93 90 44.9 38 2.21 212,064 47,275 164,789 28,836 193,625 0.93 90 44.9 39 2.18 214,690 48,519 166,171 28,836 195,007 0.93 90 44.9 40 2.15 217,165 49,763 167,402 28,836 196,238 0.93 90 44.9 41 2.12 219,488 51,007 168,481 28,836 197,317 0.93 90 44.9 42 2.09 221,660 52,251 169,409 28,836 198,244 0.93 90 44.9 43 2.06 223,680 53,495 170,185 28,836 199,021 0.93 90 44.9 44 2.03 225,548 54,739 170,809 28,836 199,645 0.93 90 44.9 45 2.00 227,266 55,983 171,282 28,836 200,118 0.93 90 44.9 46 1.97 228,831 57,227 171,604 28,836 200,440 0.93 90 44.9 47 1.94 230,245 58,471 171,774 28,836 200,610 0.93 90 44.9 48 1.91 231,508 59,716 171,792 28,836 200,628 0.93 90 44.9 49 1.88 232,619 60,960 171,659 28,836 200,495 0.93 90 44.9 50 1.85 233,579 62,204 171,375 28,836 200,211 0.93 90 44.9 51 1.82 234,387 63,448 170,939 28,836 199,775 0.93 90 44.9 52 1.79 235,043 64,692 170,351 28,836 199,187 0.93 90 44.9 53 1.76 235,548 65,936 169,612 28,836 198,448 0.93 90 44.9 54 1.73 235,902 67,180 168,722 28,836 197,558 0.93 90 44.9 55 1.70 236,104 68,424 167,680 28,836 196,515 0.93 90 44.9 56 1.67 236,154 69,668 166,486 28,836 195,322 0.93 90 44.9 57 1.64 236,053 70,912 165,141 28,836 193,977 0.93 90 44.9 58 1.61 235,801 72,156 163,644 28,836 192,480 River Edge Colorado Water Quality and Quantity Storage Calculations 12/26/2010 3 of 5 FAA detentn NP2 App. E-17 0.93 90 44.9 59 1.58 235,397 73,400 161,996 28,836 190,832 0.93 90 44.9 60 1.55 234,841 74,644 160,197 28,836 189,033 0.93 90 44.9 61 1.54 237,035 75,888 161,147 28,836 189,982 0.93 90 44.9 62 1.53 239,173 77,133 162,040 28,836 190,876 0.93 90 44.9 63 1.52 241,254 78,377 162,877 28,836 191,713 0.93 90 44.9 64 1.51 243,279 79,621 163,658 28,836 192,494 0.93 90 44.9 65 1.49 245,247 80,865 164,382 28,836 193,218 0.93 90 44.9 66 1.48 247,159 82,109 165,050 28,836 193,886 0.93 90 44.9 67 1.47 249,014 83,353 165,662 28,836 194,497 0.93 90 44.9 68 1.46 250,814 84,597 166,217 28,836 195,053 0.93 90 44.9 69 1.45 252,556 85,841 166,715 28,836 195,551 0.93 90 44.9 70 1.44 254,243 87,085 167,158 28,836 195,994 0.93 90 44.9 71 1.43 255,873 88,329 167,544 28,836 196,379 0.93 90 44.9 72 1.42 257,446 89,573 167,873 28,836 196,709 0.93 90 44.9 73 1.40 258,964 90,817 168,146 28,836 196,982 0.93 90 44.9 74 1.39 260,424 92,061 168,363 28,836 197,199 0.93 90 44.9 75 1.38 261,829 93,306 168,523 28,836 197,359 0.93 90 44.9 76 1.37 263,177 94,550 168,627 28,836 197,463 0.93 90 44.9 77 1.36 264,469 95,794 168,675 28,836 197,511 0.93 90 44.9 78 1.35 265,704 97,038 168,666 28,836 197,502 0.93 90 44.9 79 1.34 266,883 98,282 168,601 28,836 197,437 0.93 90 44.9 80 1.33 268,005 99,526 168,479 28,836 197,315 0.93 90 44.9 81 1.32 269,071 100,770 168,301 28,836 197,137 0.93 90 44.9 82 1.30 270,081 102,014 168,067 28,836 196,903 0.93 90 44.9 83 1.29 271,034 103,258 167,776 28,836 196,612 0.93 90 44.9 84 1.28 271,931 104,502 167,429 28,836 196,265 0.93 90 44.9 85 1.27 272,771 105,746 167,025 28,836 195,861 0.93 90 44.9 86 1.26 273,555 106,990 166,565 28,836 195,401 0.93 90 44.9 87 1.25 274,283 108,234 166,049 28,836 194,884 0.93 90 44.9 88 1.24 274,954 109,478 165,476 28,836 194,312 0.93 90 44.9 89 1.23 275,569 110,723 164,847 28,836 193,683 River Edge Colorado Water Quality and Quantity Storage Calculations 12/26/2010 4 of 5 FAA detentn NP2 App. E-18 0.93 90 44.9 90 1.22 276,128 111,967 164,161 28,836 192,997 0.93 90 44.9 91 1.20 276,630 113,211 163,419 28,836 192,255 0.93 90 44.9 92 1.19 277,075 114,455 162,621 28,836 191,457 0.93 90 44.9 93 1.18 277,465 115,699 161,766 28,836 190,602 0.93 90 44.9 94 1.17 277,798 116,943 160,855 28,836 189,691 0.93 90 44.9 95 1.16 278,074 118,187 159,887 28,836 188,723 0.93 90 44.9 96 1.15 278,294 119,431 158,863 28,836 187,699 0.93 90 44.9 97 1.14 278,458 120,675 157,783 28,836 186,619 0.93 90 44.9 98 1.13 278,565 121,919 156,646 28,836 185,482 0.93 90 44.9 99 1.11 278,616 123,163 155,453 28,836 184,289 0.93 90 44.9 100 1.10 278,611 124,407 154,203 28,836 183,039 0.93 90 44.9 101 1.09 278,549 125,651 152,897 28,836 181,733 0.93 90 44.9 102 1.08 278,431 126,896 151,535 28,836 180,371 0.93 90 44.9 103 1.07 278,256 128,140 150,116 28,836 178,952 0.93 90 44.9 104 1.06 278,025 129,384 148,641 28,836 177,477 0.93 90 44.9 105 1.05 277,737 130,628 147,110 28,836 175,946 0.93 90 44.9 106 1.04 277,394 131,872 145,522 28,836 174,358 0.93 90 44.9 107 1.03 276,993 133,116 143,878 28,836 172,713 0.93 90 44.9 108 1.01 276,537 134,360 142,177 28,836 171,013 0.93 90 44.9 109 1.00 276,024 135,604 140,420 28,836 169,256 0.93 90 44.9 110 0.99 275,454 136,848 138,606 28,836 167,442 0.93 90 44.9 111 0.98 274,828 138,092 136,736 28,836 165,572 0.93 90 44.9 112 0.97 274,146 139,336 134,810 28,836 163,646 0.93 90 44.9 113 0.96 273,408 140,580 132,827 28,836 161,663 0.93 90 44.9 114 0.95 272,613 141,824 130,788 28,836 159,624 0.93 90 44.9 115 0.94 271,761 143,068 128,693 28,836 157,529 0.93 90 44.9 116 0.92 270,853 144,313 126,541 28,836 155,377 0.93 90 44.9 117 0.91 269,889 145,557 124,333 28,836 153,168 0.93 90 44.9 118 0.90 268,869 146,801 122,068 28,836 150,904 0.93 90 44.9 119 0.89 267,792 148,045 119,747 28,836 148,583 0.93 90 44.9 120 0.88 266,658 149,289 117,369 28,836 146,205 River Edge Colorado Water Quality and Quantity Storage Calculations 12/26/2010 5 of 5 FAA detentn NP2 App. E-19 Existing CIAQ in/hr acres cfs 0.20 1.82 60.9 22 Proposed input CIAQ constant in/hr acres cfs calculated 0.37 2.80 60.9 63 from other cell C values from typical tables for Rational Method coefficients I values from NOAA River Edge Colorado Water Quality and Quantity Storage Calculations 12/26/2010 1 of 5 Rat Method SP1 App. E-20 Based on FAA method in Handbook of Hydrology, p. 28.27 Qout = 22.17 cfs (historic)Impervious Ratio 0.32 Qin = 63.09 cfs (developed)Drain Time (hr)40 Qout/Qin = 0.35 WQCV (in)0.157 From UDFCD Manual Vol. 3 Figure EDB-2 k = 1.50 (from graph)storage factor (sf)1 Runoff coeff % Impervious Area storm duration Rainfall intensity Runoff Volume Outflow Volume Storage Volume WQ Volume Total input C I A T I CIAT k(Qout)T runoff minus outflow (WQCV/12)*A*sf constant acres min in/hr cu ft cu ft cu ft cu ft cu ft calculated 0.93 90 60.9 5 5.39 92,345 9,975 82,370 34,708 117,077 from other cell 0.93 90 60.9 6 5.15 105,880 11,971 93,910 34,708 128,617 0.93 90 60.9 7 4.91 117,770 13,966 103,805 34,708 138,512 0.93 90 60.9 8 4.67 128,015 15,961 112,055 34,708 146,762 0.93 90 60.9 9 4.43 136,616 17,956 118,660 34,708 153,368 0.93 90 60.9 10 4.19 143,572 19,951 123,621 34,708 158,329 0.93 90 60.9 11 4.06 152,954 21,946 131,008 34,708 165,715 0.93 90 60.9 12 3.93 161,431 23,941 137,490 34,708 172,198 0.93 90 60.9 13 3.79 169,004 25,936 143,068 34,708 177,775 0.93 90 60.9 14 3.66 175,672 27,931 147,741 34,708 182,448 0.93 90 60.9 15 3.53 181,435 29,926 151,509 34,708 186,216 0.93 90 60.9 16 3.46 189,584 31,921 157,662 34,708 192,370 0.93 90 60.9 17 3.39 197,238 33,916 163,322 34,708 198,030 0.93 90 60.9 18 3.31 204,400 35,912 168,488 34,708 203,196 0.93 90 60.9 19 3.24 211,068 37,907 173,161 34,708 207,869 0.93 90 60.9 20 3.17 217,243 39,902 177,341 34,708 212,048 0.93 90 60.9 21 3.10 222,924 41,897 181,027 34,708 215,734 0.93 90 60.9 22 3.03 228,112 43,892 184,220 34,708 218,927 0.93 90 60.9 23 2.95 232,806 45,887 186,919 34,708 221,626 0.93 90 60.9 24 2.88 237,007 47,882 189,125 34,708 223,832 0.93 90 60.9 25 2.81 240,714 49,877 190,837 34,708 225,545 0.93 90 60.9 26 2.74 243,928 51,872 192,056 34,708 226,764 0.93 90 60.9 27 2.67 246,649 53,867 192,782 34,708 227,489 River Edge Colorado Water Quality and Quantity Storage Calculations 12/26/2010 2 of 5 FAA detentn SP1 App. E-21 0.93 90 60.9 28 2.59 248,876 55,862 193,014 34,708 227,722 0.93 90 60.9 29 2.52 250,610 57,857 192,753 34,708 227,460 0.93 90 60.9 30 2.45 251,851 59,853 191,998 34,708 226,706 0.93 90 60.9 31 2.42 257,059 61,848 195,211 34,708 229,919 0.93 90 60.9 32 2.39 262,062 63,843 198,219 34,708 232,926 0.93 90 60.9 33 2.36 266,859 65,838 201,021 34,708 235,729 0.93 90 60.9 34 2.33 271,450 67,833 203,618 34,708 238,325 0.93 90 60.9 35 2.30 275,836 69,828 206,008 34,708 240,716 0.93 90 60.9 36 2.27 280,017 71,823 208,194 34,708 242,901 0.93 90 60.9 37 2.24 283,992 73,818 210,173 34,708 244,881 0.93 90 60.9 38 2.21 287,761 75,813 211,948 34,708 246,655 0.93 90 60.9 39 2.18 291,324 77,808 213,516 34,708 248,224 0.93 90 60.9 40 2.15 294,682 79,803 214,879 34,708 249,586 0.93 90 60.9 41 2.12 297,835 81,798 216,036 34,708 250,744 0.93 90 60.9 42 2.09 300,782 83,794 216,988 34,708 251,696 0.93 90 60.9 43 2.06 303,523 85,789 217,734 34,708 252,442 0.93 90 60.9 44 2.03 306,058 87,784 218,275 34,708 252,982 0.93 90 60.9 45 2.00 308,388 89,779 218,610 34,708 253,317 0.93 90 60.9 46 1.97 310,513 91,774 218,739 34,708 253,447 0.93 90 60.9 47 1.94 312,432 93,769 218,663 34,708 253,370 0.93 90 60.9 48 1.91 314,145 95,764 218,381 34,708 253,089 0.93 90 60.9 49 1.88 315,653 97,759 217,894 34,708 252,601 0.93 90 60.9 50 1.85 316,955 99,754 217,201 34,708 251,908 0.93 90 60.9 51 1.82 318,051 101,749 216,302 34,708 251,010 0.93 90 60.9 52 1.79 318,942 103,744 215,198 34,708 249,905 0.93 90 60.9 53 1.76 319,628 105,739 213,888 34,708 248,596 0.93 90 60.9 54 1.73 320,107 107,735 212,373 34,708 247,080 0.93 90 60.9 55 1.70 320,381 109,730 210,652 34,708 245,359 0.93 90 60.9 56 1.67 320,450 111,725 208,725 34,708 243,433 0.93 90 60.9 57 1.64 320,313 113,720 206,593 34,708 241,301 0.93 90 60.9 58 1.61 319,970 115,715 204,255 34,708 238,963 River Edge Colorado Water Quality and Quantity Storage Calculations 12/26/2010 3 of 5 FAA detentn SP1 App. E-22 0.93 90 60.9 59 1.58 319,422 117,710 201,712 34,708 236,419 0.93 90 60.9 60 1.55 318,668 119,705 198,963 34,708 233,671 0.93 90 60.9 61 1.54 321,645 121,700 199,945 34,708 234,653 0.93 90 60.9 62 1.53 324,546 123,695 200,851 34,708 235,558 0.93 90 60.9 63 1.52 327,370 125,690 201,679 34,708 236,387 0.93 90 60.9 64 1.51 330,117 127,685 202,432 34,708 237,139 0.93 90 60.9 65 1.49 332,788 129,680 203,108 34,708 237,815 0.93 90 60.9 66 1.48 335,383 131,676 203,707 34,708 238,415 0.93 90 60.9 67 1.47 337,901 133,671 204,230 34,708 238,938 0.93 90 60.9 68 1.46 340,342 135,666 204,676 34,708 239,384 0.93 90 60.9 69 1.45 342,707 137,661 205,046 34,708 239,754 0.93 90 60.9 70 1.44 344,995 139,656 205,339 34,708 240,047 0.93 90 60.9 71 1.43 347,207 141,651 205,556 34,708 240,264 0.93 90 60.9 72 1.42 349,342 143,646 205,696 34,708 240,404 0.93 90 60.9 73 1.40 351,401 145,641 205,760 34,708 240,468 0.93 90 60.9 74 1.39 353,383 147,636 205,747 34,708 240,455 0.93 90 60.9 75 1.38 355,289 149,631 205,658 34,708 240,365 0.93 90 60.9 76 1.37 357,118 151,626 205,492 34,708 240,200 0.93 90 60.9 77 1.36 358,871 153,621 205,250 34,708 239,957 0.93 90 60.9 78 1.35 360,547 155,617 204,931 34,708 239,638 0.93 90 60.9 79 1.34 362,147 157,612 204,535 34,708 239,243 0.93 90 60.9 80 1.33 363,670 159,607 204,063 34,708 238,771 0.93 90 60.9 81 1.32 365,117 161,602 203,515 34,708 238,222 0.93 90 60.9 82 1.30 366,487 163,597 202,890 34,708 237,597 0.93 90 60.9 83 1.29 367,780 165,592 202,188 34,708 236,896 0.93 90 60.9 84 1.28 368,997 167,587 201,410 34,708 236,118 0.93 90 60.9 85 1.27 370,138 169,582 200,555 34,708 235,263 0.93 90 60.9 86 1.26 371,201 171,577 199,624 34,708 234,332 0.93 90 60.9 87 1.25 372,189 173,572 198,617 34,708 233,324 0.93 90 60.9 88 1.24 373,100 175,567 197,532 34,708 232,240 0.93 90 60.9 89 1.23 373,934 177,562 196,372 34,708 231,079 River Edge Colorado Water Quality and Quantity Storage Calculations 12/26/2010 4 of 5 FAA detentn SP1 App. E-23 0.93 90 60.9 90 1.22 374,692 179,558 195,134 34,708 229,842 0.93 90 60.9 91 1.20 375,373 181,553 193,821 34,708 228,528 0.93 90 60.9 92 1.19 375,978 183,548 192,430 34,708 227,138 0.93 90 60.9 93 1.18 376,506 185,543 190,964 34,708 225,671 0.93 90 60.9 94 1.17 376,958 187,538 189,420 34,708 224,128 0.93 90 60.9 95 1.16 377,333 189,533 187,800 34,708 222,508 0.93 90 60.9 96 1.15 377,632 191,528 186,104 34,708 220,811 0.93 90 60.9 97 1.14 377,854 193,523 184,331 34,708 219,038 0.93 90 60.9 98 1.13 378,000 195,518 182,482 34,708 217,189 0.93 90 60.9 99 1.11 378,069 197,513 180,556 34,708 215,263 0.93 90 60.9 100 1.10 378,061 199,508 178,553 34,708 213,261 0.93 90 60.9 101 1.09 377,977 201,503 176,474 34,708 211,181 0.93 90 60.9 102 1.08 377,817 203,499 174,318 34,708 209,026 0.93 90 60.9 103 1.07 377,580 205,494 172,086 34,708 206,794 0.93 90 60.9 104 1.06 377,266 207,489 169,778 34,708 204,485 0.93 90 60.9 105 1.05 376,876 209,484 167,393 34,708 202,100 0.93 90 60.9 106 1.04 376,410 211,479 164,931 34,708 199,638 0.93 90 60.9 107 1.03 375,867 213,474 162,393 34,708 197,100 0.93 90 60.9 108 1.01 375,247 215,469 159,778 34,708 194,486 0.93 90 60.9 109 1.00 374,551 217,464 157,087 34,708 191,794 0.93 90 60.9 110 0.99 373,778 219,459 154,319 34,708 189,027 0.93 90 60.9 111 0.98 372,929 221,454 151,475 34,708 186,182 0.93 90 60.9 112 0.97 372,003 223,449 148,554 34,708 183,261 0.93 90 60.9 113 0.96 371,001 225,444 145,557 34,708 180,264 0.93 90 60.9 114 0.95 369,922 227,440 142,483 34,708 177,190 0.93 90 60.9 115 0.94 368,767 229,435 139,332 34,708 174,040 0.93 90 60.9 116 0.92 367,535 231,430 136,105 34,708 170,813 0.93 90 60.9 117 0.91 366,227 233,425 132,802 34,708 167,509 0.93 90 60.9 118 0.90 364,842 235,420 129,422 34,708 164,129 0.93 90 60.9 119 0.89 363,380 237,415 125,965 34,708 160,673 0.93 90 60.9 120 0.88 361,842 239,410 122,432 34,708 157,140 River Edge Colorado Water Quality and Quantity Storage Calculations 12/26/2010 5 of 5 FAA detentn SP1 App. E-24 Erosion and Sediment Control Plan River Edge Colorado, Garfield County, Colorado APPENDIX F: CDPHE STORMWATER MANAGEMENT PLAN APPLICATION App. F-1 Page 1 of 3 Revised 12/2010 For Agency Use Only Permit Number Assigned COR03-______________ Date Received ____/____/____ Month Day Year STORMWATER DISCHARGE ASSOCIATED WITH CONSTRUCTION ACTIVITIES APPLICATION PHOTO COPIES, FAXED COPIES, PDF COPIES OR EMAILS WILL NOT BE ACCEPTED. Please print or type.Original signatures are required. This application must be considered complete by the Division before it will initiate permit processing. The Division will notify the applicant if additional information is needed to complete the application. If more space is required to answer any question, please attach additional sheets to the application form. Applications must be mailed or delivered to: Colorado Department of Public Health and Environment Water Quality Control Division 4300 Cherry Creek Drive South WQCD-P-B2 Denver, Colorado 80246-1530 PERMIT INFORMATION Applicant is: □ Property Owner □ Contractor/Operator 1. CONTACT INFORMATION Permit Applicant Company Name: Legally Responsible Person:First Name:Last Name: Title: See description of legal contact item 9, page 3 Mailing Address: City, State and Zip Code: Phone: Email Address: Local Facility Contact Same as Applicant Local Contact Person:First Name:Last Name: Title: Phone: Email Address: Billing Contact Same as Applicant Company Name: Billing Contact Person:First Name:Last Name: Title: Mailing Address: City, State and Zip Code: Phone: Email Address: App. F-2 Carbondale Investments, LLC Project Executive 5121 Park Lane Dallas, TX 75220 Project Executive (970) 945-2113 rshepard@westpacinv.com Carbondale Investments, LLC Project Executive 7999 Hwy. 82 Carbondale, CO 81623 (970) 945-2113 Rockwood Shepard Rockwood Shepard Rockwood Shepard Page 2 of 3 Revised 12/2010 1. CONTACT INFORMATION - CONTINUED Assignment Of Authorized Agent(S)—Regulation 61 [61.4(1)] NOT REQUIRED In accordance with Regulation 61, all reports required by permits and other information requested by the Division shall be signed by a person described in section 61.4(1)(e) or by a duly authorized representative of that person. A person is a duly authorized representative only if: i. The authorization is made in writing by a person described in paragraph 61.4(1)(e); ii.The authorization specifies either an individual or a position having responsibility for the overall operation of the regulated facility or activity such as the position of plant manager, operator of a well or a well field, superintendent, position of equivalent responsibility, or an individual or position having overall responsibility for environmental matters for the company. (A duly authorized representative may thus be either a named individual or any individual occupying a named position); and, iii. The written authorization is submitted to the Division. Duly Authorized Representative information provided below?□ NO □ YES Authorized individual:Email address: Title:Telephone No: Authorized position:Email address: Position currently held by:Telephone No: 2. PERMITTED FACILITY INFORMATION Name of Plan, Project or Development: Location of construction site: Street Address (or cross streets): City (if unincorporated, so indicate):County: State and Zip Code: Latitude and Longitude (approximate center of site to nearest 15 seconds using one of following formats): Latitude:Longitude:(e.g., 39°42’11’’, 104°55’57’’) degrees /minutes/ seconds OR degrees/ minutes/ seconds Latitude:Longitude: (e.g., 39.703°, 104.933’) degrees (to 3 decimal places)degrees (to 3 decimal places) 3. MAP (Attachment) Map:Attach a map that indicates the site location and that CLEARLY shows the boundaries of the area that will be disturbed. Maps must be no larger than 11x17 inches. 4. LEGAL DESCRIPTION Legal description:If subdivided, provide the legal description below, or indicate that it is not applicable (do not supply Township/Range/Section or metes and bounds description of site) Subdivision(s): Lot(s): Block(s): OR □ Not applicable (site has not been subdivided) 5. AREA OF CONSTRUCTION SITE Total area of project site (acres): Area of project site to undergo disturbance (acres): Total disturbed area of Larger Common Plan of Development or Sale, if applicable: (i.e., total, including all phases, filings, lots, and infrastructure not covered by this application) App. F-3 ■ River Edge Colorado 7999 Hwy. 82 Colorado, 81623 159.16 159.16 159.16 Rockwood Shepard rahepard@westpacinv.com Project Executive (970) 945-2113 Carbondale Garfield Page 3 of 3 Revised 12/2010 6. NATURE OF CONSTRUCTION ACTIVITY Check the appropriate box(s) or provide a brief description that indicates the general n ature of the construction activities. (The full description of activities must be included in the Stormwater Management Plan.) □ Single Family Residential Development □ Multi-Family Residential Development □ Commercial Development □ Oil and Gas Production and/or Exploration (including pad sites and associated infrastructure) □ Highway/Road Development (not including roadways associated with commercial or residential development) □ Other, Describe: 7. ANTICIPATED CONSTRUCTION SCHEDULE Construction Start Date: Final Stabilization Date: 8. RECEIVING WATERS (If discharge is to a ditch or storm sewer, include the name of the ultimate receiving waters) Immediate Receiving Water(s): Ultimate Receiving Water(s): 9. REQUIRED SIGNATURES (Both parts i. and ii. must be signed) Signature of Applicant: The applicant must be either the owner and/or operator of the construction site. Refer to Part B of the instructions for additional information. The application must be signed by the applicant to be considered complete. In all cases, it shall be signed as follows: (Regulation 61.4 (1ei) a) In the case of corporations, by the responsible corporate officer is responsible for the overall operation of the facility from which the discharge described in the form originates b) In the case of a partnership, by a general partner. c) In the case of a sole proprietorship, by the proprietor. d) In the case of a municipal, state, or other public facility, by either a principal executive officer, ranking elected official, (a principal executive officer has responsibility for the overall operation of the facility from which the discharge originates). STOP!: A Stormwater Management Plan must be completed prior to signing the following certifications! i. Stormwater Management Plan Certification “I certify under penalty of law that a complete Stormwater Management P lan, as described in Appendix A of this application, has been prepared for my activity. Based on my inquiry of the person or persons who manage the system, or those persons directly responsible for gathering the information, the Stormwater Management Plan is, to the best of my knowledge and belief, true, accurate, and complete. I am aware that there are significant penalties for falsely certifying the completion of said SWMP, including the possibility of fine and imprisonment for knowing violations.” Signature of Legally Responsible Person or Authorized Agent (submission must include original signature) Date Signed Name (printed) Title ii. Signature of Permit Legal Contact “I certify under penalty of law that I have personally examined and am familiar with the information submitted in this applic ation and all attachments and that, based on my inquiry of those individuals immediately responsible for obtaining the information, I believe that the information is true, accurate and complete. I am aware that there are significant penalties for submitting false information, including the possibility of fine or imprisonment. “I understand that submittal of this application is for coverage under the State of Colorado General Permit for Stormwater Discharges Associated with Construction Activity for the entirety of the construction site/project described and applied for, until such time as the application is amended or the certification is transferred, inactivated, or expired .” Signature of Legally Responsible Person (submission must include original signature) Date Signed Name (printed Title DO NOT INCLUDE A COPY OF THE STORMWATER MANAGEMENT PLAN DO NOT INCLUDE PAYMENT – AN INVOICE WILL BE SENT AFTER THE CERTIFICATION IS ISSUED. App. F-4 Roaring Fork River Colorado River Erosion and Sediment Control Plan River Edge Colorado, Garfield County, Colorado APPENDIX G: WETLANDS DELINEATION REPORT App. G-1 App. G-2 River Edge Colorado Wetland Determination Report September 7, 2010 2 2 Wetland Delineation Report for River Edge Colorado Garfield County, Colorado TABLE OF CONTENTS 1. INTRODUCTION ......................................................................................................................... 3 1.1. Contact Information ............................................................................................................... 3 1.2. Project Location ..................................................................................................................... 3 1.3. Figure 1: River Edge Colorado Property Location ................................................................. 4 1.4. Figure 2: Topographic Map of Project Area .......................................................................... 5 1.5. Background Information ........................................................................................................ 6 2. METHODS ..................................................................................................................................... 7 2.1. Wetland Determinations ........................................................................................................ 7 3. RESULTS AND DISCUSSION ...................................................................................................... 9 3.1. Upland Disturbed Area Communities (Non Wetlands) ........................................................ 9 3.2. Lower Bench Riparian Areas (Non-Wetlands) ..................................................................... 10 3.3. Cattle Creek Wetlands (Jurisdictional Wetlands) .................................................................. 11 3.4. Riparian Shrublands (Jurisdictional Wetlands) .................................................................... 11 3.5. West Bank Emergent Wetlands (Jurisdictional Wetlands) ................................................... 12 4. WETLAND FUNCTIONS, VALUES, AND JURISDICTIONAL EXTENT ............................. 13 4.1. Figure 3: Map of Jurisdictional Wetlands along Cattle Creek .............................................. 14 4.2. Figure 4: Map of Jurisdictional Wetlands along Roaring Fork River ................................... 15 5. SELECTED REFERENCES ........................................................................................................ 16 6. APPENDIX A- DATA POINT PHOTOGRAPHS ....................................................................... 17 7. APPENDIX B- FIELD DATA FORMS ........................................................................................ 21 8. APPENDIX C: JURISDICTIONAL DETERMINATION- CATTLE CREEK ......................... 60 9. APPENDIX D: JURISDICTIONAL DETERMINATION- ROARING FORK RIVER ............ 68 App. G-3 River Edge Colorado Wetland Determination Report September 7, 2010 3 3 1. Introduction Carbondale Investments, LLC is proposing to develop the property known as River Edge Colorado as a residential community, which precipitated the need for a wetland delineation to assist with their planning efforts. The current proposal includes ~975 units, with associated roads and infrastructure. Additional amenities include an elementary school, neighborhood parks and athletic fields, and a community center. The Roaring Fork Trails Association (RFTA) has an existing recreation path that traverses the property from north to south; this path will remain and be enhanced with this proposal. Mr. Sam Otero of 8,140 Partners requested that PENDO Solutions, Inc. (Pendo) delineate a wetland boundary on the property in order to facilitate their planning process, and in anticipation of submitting a permit application for compliance with Section 404 of the Clean Water Act. Pendo will be preparing the 404 application for ACOE review after the Jurisdictional Determination is approved by the ACOE. Portions of Cattle Creek and the Roaring Fork River were targeted for wetland delineations where the project may impinge upon wetlands. Not all wetlands across the property were delineated due to avoidance of large potential wetland areas by the project. 1.1. Contact Information Applicant Authorized Agent Rockwood Shepard Eric Petterson WestPac Investments PENDO Solutions, Inc. 7999 Hwy. 82 PO Box 833 Carbondale CO 81623 Glenwood Springs, CO 81602 970-456-5325 970-945-9558 970-945-2113 epetterson@pendosolutions.com rshepard@westpacinv.com Project Planner/Engineer W. Sam Otero 8140 Partners, LLC PO Box 0426 Eagle, CO 81631 970-445-8810 sam.otero@8140partners.com 1.2. Project Location River Edge Colorado 7999 Hwy. 82 Carbondale, CO 81623 The property is located at an elevation of 6,350 feet between Glenwood Springs and Carbondale in Garfield County, Colorado (Sections 7 & 18, Township 7 South, Range 88 West; and Sections 1, 12 and 13, Township 7 South, Range 89 West, 6th Principal Meridian), west of Highway 82 along Cattle Creek and the Roaring Fork River. The area is within the Cattle Creek USGS Topographic Quadrangle (Figures 1-2). App. G-4 App. G-5 App. G-6 River Edge Colorado Wetland Determination Report September 7, 2010 6 1.5. Background Information The 282.7 acre project area is bisected by Cattle Creek which flows into the Roaring Fork River. Wetlands were delineated along portions of Cattle Creek and along the Roaring Fork River as requested by the Applicant. The property owners and their representatives are proposing the development of a 945-unit residential subdivision on the property. As part of this project, utility lines (wastewater and electrical) would likely bisect jurisdictional wetlands and various components of the project may impinge upon some wetland areas. Therefore a wetland delineation was requested for planning purposes, with any needed 404 permitting to follow later in 2010 or 2011. The property is currently vacant land. Historically the property was part of a cow/calf operation with widespread irrigated pasturelands and wintertime grazing. During the summer of 2005, a previous owner began grading of the site for the development of a golf-course and residential community. Midway through grading, the project was terminated, which left the majority of the property with a cobbly surface. Topsoil was salvaged by this early grading process, and stored in large piles. Upland areas are now dominated by ruderal weeds and opportunistic plants including yellow sweetclover (Melilotus officinale), prickly lettuce (Lactuca serriola), and alfalfa (Medigaco sativa). On steeper slopes, and where topsoil salvage operations did not occur, remnant native species occur, including Gambel’s oak (Quercus gambelii), sagebrush (Artemisia tridentata ssp. pauciflora), smooth brome (Bromus inermis), timothy (Phleum pratense) and weeds such as plumeless thistle (Carduus acanthoides), and Canada thistle (Cirsium arvense). Older narrowleaf cottonwood trees (Populus angustifolia) which likely established during the long-term irrigation of the meadows are rapidly declining in the absence of irrigation waters. Cattle Creek itself was significantly impacted by historic grazing practices (as interpreted from historical aerial photos). Subsequently the non-native reed canary grass (Phalaroides arundinacea) has become entrenched along this creek. The Roaring Fork Conservancy holds a conservation easement on portions of the property along Cattle Creek and along the Roaring Fork River. While this easement prohibits development, it does allow for the installation of linear utility lines. On the western side of the Roaring Fork River the property is owned by the Homeowners Association of Aspen Glen, and the Roaring Fork Water and Sanitation District. The Roaring Fork Water and Sanitation waste water treatment plant is located here, and River Edge Colorado’s plans include a proposed tie-in to this facility for the treatment of wastewater. In anticipation of this, 8140 Partners requested Pendo to delineate wetlands in this area. The wide and well established wetlands in this area appeared to be supported by waters discharged from a pipe, as well as a number of seeps and springs. A total of approximately 6.52 acres of Jurisdictional Wetlands were identified within the targeted areas of the property, and as previously mentioned there are additional wetlands on the property that were not delineated as the project would not be in proximity to these other wetlands. The Federal Clean Water Act, Section 404, authorizes the Corps, specifically the Chief of Engineers, to issue permits for the discharge of dredged or fill materials into navigable Waters of the U.S. This permitting process is overseen by the Environmental Protection Agency and is reviewed by the Fish and Wildlife Service and the National Marine Fisheries Service. This permit requires that the limits of wetlands be identified and delineated. The resulting wetlands are referred to as jurisdictional wetlands and are regulated under Section 404 of the Federal Clean Water Act. The determination of navigability is left entirely to the Corps. App. G-7 River Edge Colorado Wetland Determination Report September 7, 2010 7 2. Methods The wetlands delineation described in this document was conducted following technical guidelines set forth in the U.S. Army Corps of Engineers (Corps) 2008 Interim Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Arid West Region and the guidance document “Information Needed for Jurisdictional Determinations.” Prior to and during field work, PENDO Solutions’ (Pendo) staff reviewed various resources to assist in identifying Waters of the U.S., beyond wetland areas located on the property. These resources included aerial photographs, topographic and soils maps, and other environmental resources. Upon completion of the pre-field work, the project area was traversed in August 2010. A total of six data points were used along Cattle Creek (three points in uplands and three points in wetlands). Six sample points were used along the Roaring Fork River and associated wetlands. Wetland sample points revealed the boundary between sites which exhibited all three wetland parameters and sites which were lacking one or more wetland parameters. Based on the presence or absence of parameters, wetland boundaries were designated. Ecosystem parameters (vegetation, soils, and hydrology) were characterized and recorded on field data forms (Appendix B) at each of the twelve sample points. Based on observations of all three wetland parameters, wetland boundaries were designated with pink wetland delineation flagging. Wetland boundaries were then logged with a Trimble GeoXT GPS unit (sub-meter accuracy), differentially corrected, and then exported as ArcGIS shapefiles. Wetland boundaries are depicted on Figures 3 & 4. 2.1. Wetland Determinations Wetland Determinations were performed as outlined in the 2006 Interim Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Arid West Region. The wetlands on the site are hydrologically connected to Cattle Creek and the Roaring Fork River, both of which are perennially flowing streams immediately upstream of the Colorado River. The wetlands associated with the bottomlands along the Roaring Fork River are hydrogeomorphically classed as Riverine Wetlands, with Riverine Subclass designations of 3 and 4 (middle-elevation reaches of small and mid-order streams, dominated by tall shrubs and trees). • Vegetation: Vegetation was sampled throughout the site and in vicinity of the sample points. An attempt was made to identify all dominant species, and species were listed in order of dominance. A wetland indicator status for each species was determined using the National List of Plant Species that Occur in Wetlands: Intermountain (Region 8) (USFWS, 1988), and if the species was not addressed in that report, then the National Hydric Plant List was referenced. Cover for each species was estimated to the nearest percent to determine dominance. • Soils: Soil pits were dug in wetlands and non-wetlands at each site and inspected for hydric characteristics. Hydric characteristics included saturated soils and standing water in soil pits among other indicators. Mottling and sulphidic odors were observed. Soils in the wetland areas are described as (Soil Conservation Service 1981): o Jodero Loam, 1–12% slopes. This deep, well drained soil is found on alluvial valley floors at elevations ranging from 5,700 to 7,500 feet and on slopes of 1 to 12 percent. It is derived from alluvium composed of andesite, sandstone, and shale. App. G-8 River Edge Colorado Wetland Determination Report September 7, 2010 8 Surface runoff for this soil is slow to medium and the water erosion hazard is slight to severe. o Redrob loam, 1–6% slopes. These are deep, somewhat poorly drained soils on alluvial valley floors, low terraces, and floodplains, formed in mixed alluvium derived dominantly from sandstone and shale. Typically the surface layer is dark grayish- brown loam about 14 inches thick, the next layer is stratified stony loam about six inches thick, and the substratum to a depth of 60 inches is stony and very cobbly loamy sand and sand. The high water table is at a depth of 18–48 inches. This soil type is found on the lower bench, occupying the southwest corner of the property. • Hydrology: The site was traversed making observations for hydrologic characteristics. Cattle Creek flows into the Roaring Fork River and then the Colorado River, and are therefore Waters of the U.S. Wetland and upland communities were classified based on dominant vegetation characteristics. A field copy of the Arid Land Wetland Determination Data Form was completed for each sample point. This form recorded the vegetation, soil, and hydrologic measurements and observations. Latin plant names were used throughout. Based on the information recorded in the Data Forms, each community that met all three wetland criteria was established as a wetland. App. G-9 River Edge Colorado Wetland Determination Report September 7, 2010 9 3. Results and Discussion 3.1. Upland Disturbed Area Communities (Non Wetlands) Vegetation: The majority of the property lies on an old river terrace that lies about 75 feet above the Roaring Fork River. The type of species that are present on the disturbed upper areas of the property depends upon the underlying soil texture. The finer soils and topsoil stockpiles on the property are dominated by cheatgrass (Bromus tectorum -NI), stork’s bill (Erodium cicutarium- NI), and Jim Hill mustard (Sisymbrium altissimum- FACU). The noxious weeds such as Scotch thistle (Onopordum acanthium-NI), plumeless thistle (Carduus acanthoides-NI), common burdock (Arctium minus- NI), and common tansy (Tanacetum vulgare- FACW) are widespread, but occur in relatively sparse densities and the current landowners have been spraying weeds. Field bindweed (Convolvulus arvensis- NI) is very common within this area. The more coarse textured soils on the upper bench of the property are dominated by patchy, sparse stands of narrow leaf cottonwood (Populus angustifolia- FACW), yellow sweet clover (Melilotus officinalis-FACU), and common mullein (Verbascum Thapsus- NI). Soils: The soils in this area were typed by the National Resource Conservation Service (NRCS) as Jodero Loams, but much of the broader tablelands are dominated by Atencio-Azeltine complex soils, but given the topsoil salvage, much of soils have been significantly disturbed outside of the wetland areas. No concretions were detected, nor did the soils have any sulphidic odors. It is likely that if a soil pit was dug in some of the depressions, mottling would be detected. Hydrology: We did not detect hydrological indicators outside of wetland areas. The main feature absent in uplands, which was present in wetlands was soil saturation. Determination: The Upland Disturbed Area Communities failed to support hydric soil indicators and hydrology, while some extension of hydric vegetation occurred near Cattle Creek. Upland areas did not meet the criteria as a wetland. App. G-10 River Edge Colorado Wetland Determination Report September 7, 2010 10 3.2. Lower Bench Riparian Areas (Non-Wetlands) Vegetation: The lower bench of the property is directly adjacent to the Roaring Fork River. In most regions of the property the slope down to the river is exceedingly steep and is dense with woody vegetation such as ponderosa pine (Pinus ponderosa- FACU), Rocky Mountain juniper (Juniperus scopulorum- UPL), and oakbrush (Quercus gambelii-NI). In some regions of the property, these steep slopes are directly adjacent to the river. In other places, river bottom/ riparian vegetation communities are present in areas of prolonged sediment deposition as a result of river configuration and water flow dynamics. Noxious weeds are both dense and abundant in the riparian areas. Species include Scotch thistle, houndstongue (Cynoglossum officinale- FACU), oxeye daisy (Chrysanthemum leucanthemum-NI), plumeless thistle, common burdock (Arctium minus-FACU), Canada thistle (Cirsium arvense-FACU), common tansy (FACU), and St. John’s wort (Hypericum perfoliatum). These areas are held under a Conservation Easement by the Roaring Fork Conservancy. Soils: The soils in this area were typed by the NRCS as Atencio/Azeltine complex, but seemed to trend more towards Redrob cobbly loams. There was no mottling, sulphidic odor or other attributes of wetland soils. Hydrology: These areas failed to exhibit wetland indicators such as saturation, drift lines or free water, which were common in wetland areas. Determination: The Lower Bench Riparian areas, while having some narrowleaf cottonwood and extensions of coyote willow failed to have sufficient dominance by hydric vegetation, and did not support hydric soils or wetland hydrology, leading to a determination that the site is not a jurisdictional wetland. App. G-11 River Edge Colorado Wetland Determination Report September 7, 2010 11 3.3. Cattle Creek Wetlands (Jurisdictional Wetlands) Vegetation: The site was dominated (>95% cover) by reed canarygrass (Phalaroides arundinaceae- OBL), with insignificant amounts of common tansy (Tanacetum vulgare- FACU), Canada thistle (Cirsium arvense-FACU), and horsemint (Mentha arvensis- FACW). The site was dominated by hydrophitic vegetation. Soils: The soils in this area were typed by the NRCS as Jodero Loams complex. Within these areas saturation was detected within 12 inches of the surface. Mottling was light but nevertheless present and sulphidic odors were very limited. Hydric soil indicators were present in these areas Hydrology: Hydrology for the site was apparent through saturation, drift (wrack) lines, and sometimes free water. Determination: The Cattle Creek Wetlands were primarily determined by the dominance of reed canary grass (OBL) hydrology and hydric soils. Cattle Creek’s observed consistent and steady flows have created a fairly constrained channel, with surface waters often a foot or more below the adjacent riparian (wetland) community types. Nevertheless the creek does support a narrow band of wetlands along either side of the creek. 3.4. Riparian Shrublands (Jurisdictional Wetlands) Vegetation: Along the banks of the Roaring Fork River riparian shrublands dominated by silver buffaloberry (Shepherdia argentea-FACU), hawthorne (Cratagus saligna- FACW), coyote willow (Salix exigua- FACW), and understory vegetation including mannagrass (Glyceria grandis-OBL) and Baltic rush (Juncus balticus-FACW). Another species of note was Ute ladies-tresses orchid (Spiranthes diluvialis) which is listed by the U.S. Fish and Wildlife Service as Threatened. The site had an abundance of hydrophitic vegetation. Soils: The soils in this area were typed by the NRCS and confirmed as Jodero loams. Within these wetlands, soils were generally saturated and surface waters were patchy. Along the wetland gradient, saturation and standing water gradually dropped out of the bottom of test pits. Mottling was light. The site supported hydric soil indicators. Hydrology: Hydrology for the site is generally assumed to be from the Roaring Fork however, App. G-12 River Edge Colorado Wetland Determination Report September 7, 2010 12 some subsurface hydrology from irrigation return flows near the water treatment facilities are likely. The site had an abundance of wetland hydrologic indicators. Determination: The Riparian Shrublands had hydrophitic vegetation, hydric soils, and wetland hydrology, leading to a determination that the site was a jurisdictional wetland. The combination of seasonal high flows from the Roaring Fork River supported this community type along both the east and west banks of the river. On the west bank additional hydrology supported a wider and more diverse stand type, which graded into the Bench Wetlands area (see below). 3.5. West Bank Emergent Wetlands (Jurisdictional Wetlands) Between the Roaring Fork Water & Sanitation District’s water treatment plant on the west side of the Roaring Fork and the Roaring Fork itself, there is a broad, shallow depression on a riverside terrace that is fed by assumed irrigation return flows, or discharged treated waters from the wastewater treatment site. Additionally there are a number of springs and seeps feeding this area. Wetlands in this area were located on property owned by the Homeowners Association at Aspen Glen and Roaring Fork Water and Sanitation District. Vegetation: Cattails (Typha latifolia-FACW), reed canarygrass (Phalaroides arundinacea- OBL), and wooly sedge (Carex lanuginose-OBL), redtop (Agrostis alba- FACW), and Nebraska sedge (Carex nebraskensis- OBL). The site was dominated by hydrophitic vegetation. Soils: The soils in this area were typed by the NRCS and confirmed as Jodero loams. Within this area, soils were generally moist and with saturation within 12 inches of the surface and had low chromas. Some light mottling and sulphidic odors were also detected. Hydrology: The site was fed by a large pipe discharging water from near the water treatment plant. It is unknown if this water is from the plant, or if there was also irrigation return flows. Around the western perimeter of the wetlands there was also many springs and seeps. Saturation and inundation was common. Determination: The emergent wetlands on the west bank showed surface water connectivity directly to the Roaring Fork River and supported the three parameters for jurisdictional wetlands. This site was very extensive and supported emergent wetlands which graded into a more shrub-dominated wetland type along the banks of the Roaring Fork River. App. G-13 River Edge Colorado Wetland Determination Report September 7, 2010 13 4. Wetland Functions, Values, and Jurisdictional Extent The ecological functions of wetlands on the project site were assessed preliminarily using an approach based on the hydrogeomorphic methodology (HGM), which assesses the potential for a wetland to perform ecological functions. These functions include dynamic water storage, flood flow attenuation, production export, nutrient and pollutant removal/sediment retention, shoreline stabilization/ sediment control and wildlife habitat. The ability and the extent to which each wetland is able to perform these functions yield an overall impression of wetland functions and its value. The results of this analysis within the project area revealed that wetlands delineated in the Cattle Creek area are likely valued as low functioning wetlands. The dominance of reed canary grass and lack of vegetation diversity significantly limits the wildlife habitat value of the site. However, the extremely thick stand of reed canary grass is definitely providing bank stability and flood attenuation capacity. Along the banks of the Roaring Fork the combination of both emergent wetlands and riparian shrub-dominated wetlands provides for more diverse wildlife and plant habitat, and indeed the site contains the Federally listed Ute ladies-tresses orchid (Spiranthes diluvialis). Along this area there is also a great blue heron heronry, and osprey and bald eagle are frequently observed in this area. Wetlands are providing important bank stability and wildlife habitat values, as well as flood attenuation. However, during the spring of 2010 very high spring flows eroded a portion of the bank and dislodged a large ponderosa pine which further unraveled western banks along the Roaring Fork, so long-term bank stability in this area is concerning. In summary the vegetation, soil, and hydrologic data gathered in this survey determined that wetlands occurred on the River Edge Colorado property, and that hydrological surface connectivity to Waters of the U.S. was present. Cattle Creek is considered to be a Water of the US (ACOE 2007), as well as the Roaring Fork River. Wetlands identified on the property were adjacent and abutting to these rivers. Final authority in determining the actuality of a wetland and the allowance of wetland alterations rests with the various interested government agencies. Eroding banks and large ponderosa pine tree that fell in spring high-flows in 2010. App. G-14 App. G-15 App. G-16 River Edge Colorado Wetland Determination Report September 7, 2010 16 5. Selected References Cooper, D.J. 1989. A Handbook of Wetland Plants of the Rocky Mountain Region. EPA Region VIII. Dorn, R.D. 1997. Rocky Mountain region willow identification field guide. Renewable Resources R2-RR-97-01. Denver, CO: USDA, Forest Service, Rocky Mountain Region. 107p. Environmental Laboratory. 1987. Corps of Engineers Wetlands Delineation Manual,. Technical Report Y- 87-1, US Army Engineers Waterways Experiment Station, Vicksburg, Miss. Environmental Laboratory. 2006. Interim Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Arid West Region. ERDC/EL TR-06-16. US Army Engineer Research and Development Center. Vicksburg, MS. Federal Interagency Committee for Wetland Delineation. 1989. Federal Manual for Identifying and Delineating Jurisdictional Wetlands. U.S. Army Corps of Engineers, U.S. Environmental Protection Agency, U.S. Fish and Wildlife Service, and U.S.D.A. Soil Conservation Service, Washington, D.C. Cooperative technical publication. 76 pp. Plus appendices. Kartesz, J.T. 1996. National List of Plant Species That Occur in Wetlands: Region 8. Ecology Section, National Wetlands Inventory, U.S. Fish and Wildlife Service, Biological Report, Washington, DC. Northwest Colorado Council of Governments. 2006. Transitions in Mountain Communities: Resort Economies and their Secondary Effects. http://www.nwc.cog.co.us/Second%20Home%20Study/Second%20phase/2Final%20TMC %20Binder%20May%2007.pdf Spackman, S., B. Jennings, J. Coles, C. Dawson, M. Minton, A. Kratz, and C. Spurrier. 1997. Colorado Rare Plant Field Guide. Prepared for the BLM, USFS, and the USFWS by the Colorado Natural Heritage Program. Weber, W.A. and R.C. Wittmann. 2001. Colorado Flora: Western Slope, Third Edition. University Press of Colorado. Boulder, CO. App. G-17 River Edge Colorado Wetland Determination Report September 7, 2010 17 6. Appendix A- Data Point Photographs DP-1 Soil Pit (Wetland) DP-1 Area DP-2 Soil Pit (Upland) DP-2 Area DP-3 Soil Pit (Wetland) DP-3 Area App. G-18 River Edge Colorado Wetland Determination Report September 7, 2010 18 DP-4 Soil Pit (Upland) DP-4 Area DP-5 Soil Pit (Wetland) DP-5 Area DP-6 Soil Pit (Upland) DP-6 Area App. G-19 River Edge Colorado Wetland Determination Report September 7, 2010 19 DP-7 Soil Pit (Upland) DP-7 Area DP-8 Soil Pit (Wetland) DP-8 Area DP-9 Soil Pit (Upland) DP-9 Area App. G-20 River Edge Colorado Wetland Determination Report September 7, 2010 20 DP-10 Soil Pit (Wetland) DP-10 Area DP-11 Soil Pit (Upland) DP-12 Soil Pit (Wetland) DP-12 Area App. G-21 River Edge Colorado Wetland Determination Report September 7, 2010 21 7. Appendix B- Field Data Forms App. G-22 River Edge Colorado Wetland Determination Report September 7, 2010 37 App. G-23 River Edge Colorado Wetland Determination Report September 7, 2010 38 App. G-24 River Edge Colorado Wetland Determination Report September 7, 2010 39 App. G-25 River Edge Colorado Wetland Determination Report September 7, 2010 40 App. G-26 River Edge Colorado Wetland Determination Report September 7, 2010 41 App. G-27 River Edge Colorado Wetland Determination Report September 7, 2010 42 App. G-28 River Edge Colorado Wetland Determination Report September 7, 2010 43 App. G-29 River Edge Colorado Wetland Determination Report September 7, 2010 44 App. G-30 River Edge Colorado Wetland Determination Report September 7, 2010 45 App. G-31 River Edge Colorado Wetland Determination Report September 7, 2010 46 App. G-32 River Edge Colorado Wetland Determination Report September 7, 2010 47 App. G-33 River Edge Colorado Wetland Determination Report September 7, 2010 48 App. G-34 River Edge Colorado Wetland Determination Report September 7, 2010 49 App. G-35 River Edge Colorado Wetland Determination Report September 7, 2010 50 App. G-36 River Edge Colorado Wetland Determination Report September 7, 2010 51 App. G-37 River Edge Colorado Wetland Determination Report September 7, 2010 52 App. G-38 River Edge Colorado Wetland Determination Report September 7, 2010 53 App. G-39 River Edge Colorado Wetland Determination Report September 7, 2010 54 App. G-40 River Edge Colorado Wetland Determination Report September 7, 2010 55 App. G-41 River Edge Colorado Wetland Determination Report September 7, 2010 56 App. G-42 River Edge Colorado Wetland Determination Report September 7, 2010 57 App. G-43 River Edge Colorado Wetland Determination Report September 7, 2010 58 App. G-44 River Edge Colorado Wetland Determination Report September 7, 2010 59 App. G-45 River Edge Colorado Wetland Determination Report September 7, 2010 60 8. Appendix C: Jurisdictional Determination- Cattle Creek App. G-46 River Edge Colorado Wetland Determination Report September 7, 2010 61 App. G-47 River Edge Colorado Wetland Determination Report September 7, 2010 62 App. G-48 River Edge Colorado Wetland Determination Report September 7, 2010 63 App. G-49 River Edge Colorado Wetland Determination Report September 7, 2010 64 App. G-50 River Edge Colorado Wetland Determination Report September 7, 2010 65 App. G-51 River Edge Colorado Wetland Determination Report September 7, 2010 66 9. Appendix D: Jurisdictional Determination- Roaring Fork River App. G-52 River Edge Colorado Wetland Determination Report September 7, 2010 67 App. G-53 River Edge Colorado Wetland Determination Report September 7, 2010 68 App. G-54 River Edge Colorado Wetland Determination Report September 7, 2010 69 App. G-55 River Edge Colorado Wetland Determination Report September 7, 2010 70 App. G-56 River Edge Colorado Wetland Determination Report September 7, 2010 71 App. G-57 River Edge Colorado Wetland Determination Report September 7, 2010 72 App. G-58