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Reports - Drainage - 05/21/2025
OVERALL DEVELOPMENT PLAN AND FINAL DRAINAGE AND EROSION CONTROL REPORT SWC Drake/College Fort Collins, Colorado Prepared for: KRF Drake, LLC 1509 York St, Suite 201 Denver, CO 80206 Prepared by: Kimley-Horn and Associates, Inc. 3325 South Timberline Road - Suite 130 Fort Collins, Colorado 80525 (970) 822-7911 City of Fort Collins Project #: ODP24002 and BDR240018 KH Project #: 096315014 Prepared: May 21, 2025 kimley-horn.com 3325 S Timberline Rd, Suite 130, Fort Collins, CO 80525 970-822-7911 April 9, 2025 City of Fort Collins Stormwater Engineering 281 N. College Ave. Fort Collins, CO 80524 RE: SWC Drake/College Overall Development Plan and Final Drainage and Erosion Control Report Dear Reviewer: Kimley-Horn and Associates, Inc. is pleased to submit this Overall Development Plan and Final Drainage and Erosion Control Report for your review as part of the Overall Development Plan (ODP) and Basic Development Review (BDR) submittal for the above referenced project. This report and attached drainage plans have been prepared in accordance with the Fort Collins Stormwater Criteria Manual (“FCSCM”) and the latest Mile High Flood District Urban Storm Drainage Criteria Manual (“USDCM”). These documents serve to document stormwater impacts associated with the proposed SWC Drake/College Project. We understand the review by the City of Fort Collins is to ensure general compliance with standardized criteria contained in the FCSCM and USDCM. Please contact us with any questions or concerns. Thank You, KIMLEY-HORN AND ASSOCIATES, INC. Bryce Willaby, P.E. Overall Development Plan and Final Drainage and Erosion Control Report SWC Drake/College – Fort Collins, Colorado TABLE OF CONTENTS I. GENERAL LOCATION AND EXISITING SITE INFORMATION ............................... 1 II. MASTER DRAINAGE BASIN DESCRIPTION ...................................................... 2 IV. FLOODPLAIN INFORMATION ............................................................................. 3 V. PROJECT DESCRIPTION .................................................................................... 3 VI. OVERALL DEVELOPMENT PLAN REQUIREMENTS AND ASSUMPTIONS ...... 3 VIII. PROPOSED DRAINAGE FACILITIES ............................................................... 5 IX. DRAINAGE DESIGN CRITERIA ........................................................................... 7 X. VARIANCE REQUESTS ....................................................................................... 8 XI. EROSION CONTROL ........................................................................................... 8 XII. CONCLUSION ...................................................................................................... 8 X. REFERENCES ........................................................................................................... 9 APPENDIX A – REFERENCED CRITERIA ............................................................................ 1 APPENDIX B – HYDROLOGIC CALCULATIONS AND EXHIBITS .............................................. 2 APPENDIX C – HYDRAULIC CALCULATIONS ...................................................................... 3 Overall Development Plan and Final Drainage and Erosion Control Report SWC Drake/College – Fort Collins, Colorado 1 | P a g e I. GENERAL LOCATION AND EXISITING SITE INFORMATION SWC Drake/College (the “Project”) is located in the northeast quarter of Section 26, Township 67 North, Range 69 West, of the Sixth Principal Meridian, City of Fort Collins, Larimer County, State of Colorado. The property is generally bounded by McClelland Drive to the West, West Thunderbird Drive to the South, West Drake Road to the North and South College Avenue to the East. A Vicinity Map is shown below in Figure 1. Figure 1: Vicinity Map Surrounding properties include an existing furniture store to the southeast, offices to the west, and commercial retail developments to the south, east, and north. The King Soopers development to the north is currently under construction. The property currently consists of several buildings and a paved parking lot. The Project site is located within the General Commercial (GC) Zone District. The Project is located within the Foothills Basin, see copy of the City of Fort Collins Drainage Basins image included in Appendix A. The master basin is discussed in more detail below. The existing site drains from the west to the east to storm inlets located along S College Ave. The existing parking lot generally slopes from west to east with slopes ranging from 0 to 4 percent. There are no known existing irrigation facilities within the site. A Natural Resource Conservation Service (NRCS) Web Soil Survey for the project area was obtained to determine the soil characteristics of the site. The results of this study show that the majority of the site consists of hydrologic soil group (HSG) Type C with soil that includes Nunn clay loam. Therefore, HSG Type C soils were assumed for the entirety of the site for hydrologic calculations. A copy of the Custom Soil Resource Report is provided in Appendix A. Overall Development Plan and Final Drainage and Erosion Control Report SWC Drake/College – Fort Collins, Colorado 2 | P a g e A Preliminary Geotechnical Investigation dated July 27, 2018, was prepared by Soilogic, Inc. There are no known significant geologic features at this site. Groundwater was encountered at depths ranging from 11½ to 15 feet below the existing ground surface in the boring test holes. Groundwater levels are not expected to affect planned development at this site. Additional information for the Geotechnical report were included as a part of the submittal package. II. MASTER DRAINAGE BASIN DESCRIPTION As noted above, the project is located in the City of Fort Collins Foothills Master Drainage Basin. This basin has a maximum allowable release rate of the 2-yr historic discharge rate. A map of the Foothills Basin is included in Appendix A. Note that no detention is required since the project is reducing impervious area compared to the existing conditions. The Water Quality and low impact development (LID) requirements for the Foothills Basin follows FCSCM, which are outlined in the Drainage Design Criteria section of the report. No master drainage reports exist for the Project site. The Project proposes the removal of the existing buildings and paved parking lot. There are no known irrigation facilities that are influenced by the local drainage. The BDR Infrastructure Project is designed to provide LID and water quality treatment for the proposed roadway improvements. The drainage is planned to follow historic drainage patterns, where it will connect to a storm sewer located within S. College Avenue. III. EXISTING SITE DRAINAGE Historically, the site drains from west to east, towards an existing public storm inlet along S. College Avenue. The existing sub-basin descriptions are included below. The rational calculations within Appendix B include areas, imperviousness, and other applicable information. Sub-basin EX-A: The northwestern portion of the site, Sub-basin EX-A, slopes east from 1% to 5% and drains along W. Drake Road located north of the Project. The drainage follows the curb and gutter within W. Drake Road until it enters public storm sewer located along S. College Avenue. Basin EX-A is comprised of Type C soils as classified by the NRCS. Sub-basin EX-B: The southwestern portion of the site, Sub-basin EX-B, slopes east from 1% to 5% and drains along W. Thunderbird Road located south of the Project. The drainage follows the curb and gutter within W. Thunderbird Road until it enters public storm sewer located along S. College Avenue. Basin EX-B is comprised of Type C soils as classified by the NRCS. Sub-basin EX-C: The east portion of the site, Sub-basin EX-C, slopes northeast from 1% to 5% and drains to along S. College Avenue located to the east of the Project. The drainage follows the curb and gutter within S. College Avenue until it enters public storm sewer located along S. College Avenue. Basin EX-C is comprised of Type C soils as classified by the NRCS. Overall Development Plan and Final Drainage and Erosion Control Report SWC Drake/College – Fort Collins, Colorado 3 | P a g e IV. FLOODPLAIN INFORMATION The SWC Drake/College site is located on the Federal Emergency Management Agency (FEMA) Flood Insurance Rate Map (FIRM) number 08069C0987G dated May 2, 2012, and lies within Zone X. Zone X is defined as areas of minimal flood hazard and determined to be outside the 0.2% annual chance floodplain. A copy of the FEMA FIRMette is included in Appendix A. Additionally, the Project is not located within any City of Fort Collins floodplains. A copy of the City of Fort Collins Flood Map is included in Appendix A. V. PROJECT DESCRIPTION The Project is proposing to develop the +/- 6.27 acre site to include road and utility improvements that will support four (4) future commercial pad sites. Note that the existing site consists almost entirely of impervious area. The project will provide LID and water quality treatment for the roadway improvements, while each respective future lot is anticipated to provide separate LID and water quality treatment. VI. OVERALL DEVELOPMENT PLAN REQUIREMENTS AND ASSUMPTIONS The SWC project will be approved as an overall development plan. The Overall Development Plan (ODP) includes drainage assumptions and requirements. The drainage considerations for the future lots are listed below: The ODP shows a net reduction in impervious area and therefore no detention is needed for the lots within the ODP area. The future lots within the ODP area will be responsible for providing water quality and low impact development (LID) per City requirements. A private storm sewer trunk line will be designed to convey the 100-yr developed flow rates for future lots within the ODP area Flow rates for future lots within the ODP area are shown in Appendix B. Note that the future lots assume 80% imperviousness as shown within Exhibit D of the report. A time of concentration of 5 minutes was utilized for the future lots within the ODP area to show the worst-case scenario for peak runoff for storm sizing. VII. PROPOSED DRAINAGE BASINS The proposed sub-basin descriptions are included below. Note that the calculations of the future lots assume an imperviousness of 80%. The sub-basin R1 also include the anticipated 12’ future sidewalk along the western side of Private Drive B. The rational calculations within Appendix B include areas, imperviousness, and other applicable information. Sub-basin 1A: Sub-basin 1A is located at the northeastern corner of the site and consists of future commercial lot 1. At full buildout, the drainage is anticipated to flow east where it will be collected and routed to a future storm manhole within the private storm inlet located at design point 1A. The drainage will be conveyed into the proposed private storm line before discharging into the existing public storm sewer within S. College Avenue. Sub-basin 1B: Sub-basin 1B is located at the northeastern corner of the site and consists of future commercial lot 1. At full buildout, the drainage is anticipated to flow northeast where it will Overall Development Plan and Final Drainage and Erosion Control Report SWC Drake/College – Fort Collins, Colorado 4 | P a g e be drain off-site to curb and gutter along W. Drake Road. The drainage is then collected within existing public storm inlets along S. College Ave. Sub-basin 2A: Sub-basin 2A is located at the southeastern corner of the site and consists of future commercial lot 2. At full buildout, the drainage is anticipated to flow east where it will be collected and routed to a future storm manhole within the private storm inlet located at design point 2A. The drainage will be conveyed into the proposed private storm line before discharging into the existing public storm sewer within S. College Avenue. Sub-basin 3A: Sub-basin 3A is located at the northwestern corner of the site and consists of future commercial lot 3. At full buildout, the drainage is anticipated to flow southeast where it will be collected and routed to a proposed storm manhole located at design point 3A. The drainage will be conveyed into the proposed private storm line before discharging into the existing public storm sewer within S. College Avenue. Sub-basin 3B: Sub-basin 3B is located at the northeastern corner of the site and consists of future commercial lot 3. At full buildout, the drainage is anticipated to flow northeast where it will be drain off-site to curb and gutter along W. Drake Road. The drainage is then collected within existing public storm inlets along S. College Ave. Sub-basin 4A: Sub-basin 4A is located at the southwestern corner of the site and consists of future commercial lot 4. At full buildout, the drainage is anticipated to flow northeast where it will be collected and routed to a proposed storm manhole located at design point 4A. The drainage will be conveyed into the proposed private storm line before discharging into the existing public storm sewer within S. College Avenue. Sub-basin 4B: Sub-basin 4B is located at the southwestern corner of the site and consists of future commercial lot 4. At full buildout, the drainage is anticipated to flow southeast where it will drain off-site to existing curb and gutter within W. Thunderbird Drive and then S. College Ave. This drainage is then collected within existing public storm inlets along S. College Ave. Sub-basin R1: Sub-basin R1 is located within the center of the site and consists of Private Drive B and a portion of Private Drive A. The drainage is conveyed via curb and gutter until it is collected at a proposed single combination inlet at design point R1. The drainage is then routed to the isolator rows within the underground system. The Water Quality Storm event will be treated, and the excess drainage will stage within an outlet weir bypass structure where it will flow into the proposed private storm line located north of the chamber system before discharging into the existing public storm sewer within S. College Avenue. Sub-basin R2: Sub-basin R2 is located at the southeastern portion of the site and consists of Private Drive A. The drainage is conveyed via curb and gutter until it is collected at a proposed single combination inlet at design point R2. The drainage is then routed to the isolator Overall Development Plan and Final Drainage and Erosion Control Report SWC Drake/College – Fort Collins, Colorado 5 | P a g e rows within the underground system. The Water Quality Storm event will be treated and runoff from larger storm events will stage within an outlet weir bypass structure where it will flow into the proposed private storm line located north of the chamber system before discharging into the existing public storm sewer within S. College Avenue. Sub-basin OS-1: Sub-basin OS-1 is located at the north central portion of the site and consists of Private Drive A. The drainage is conveyed via curb and gutter within the site until it is routed along existing curb and gutter within W. Drake Road. The drainage is then collected within existing public storm inlets along S. College Ave. Sub-basin OS-2: Sub-basin OS-2 is located at the south-central portion of the site and consists of Private Drive A. The drainage is conveyed via curb and gutter within the site until it is routed along existing curb and gutter within W. Thunderbird Drive and then S. College Ave. This drainage is collected within existing public storm inlets along S. College Ave. Sub-basin OS-3: Sub-basin OS-3 is located at the southeastern corner of the site and consists of Private Drive B. The drainage is conveyed via curb and gutter within the site until it is routed along existing curb and gutter within S. College Ave. This drainage is collected within existing public storm inlets along S. College Ave. Sub-basin OS-4: Sub-basin OS-4 is located at the eastern portion of the site existing landscape area. The drainage sheet flows east towards S. College Avenue until it is routed along existing curb and gutter within S. College Ave. This drainage is collected within existing public storm inlets along S. College Ave. VIII. PROPOSED DRAINAGE FACILITIES Proposed Site Description Site grading is designed to convey the proposed roadway drainage to proposed storm inlets (located at design points R1 and R2) that discharge into the underground storm chamber system (“underground system”) via private storm sewer. The Project proposes using ADS SC-800 Stormtech chambers. The chamber configuration and additional details for the overflow weir are shown within the Subgrade Sheet of the Utility Plans. Proposed Detention Facilities The existing site is predominately impervious, and the final development is planned to see a reduction in overall imperviousness. As a result, no detention is required. Note that the proposed impervious areas assume 80% impervious for the future lots at full-build out. Existing and proposed impervious exhibits were used to calculate the impervious areas for each condition. These exhibits are included within Appendix B. This reduction is summarized in Table 1 below. Overall Development Plan and Final Drainage and Erosion Control Report SWC Drake/College – Fort Collins, Colorado 6 | P a g e Area Summary Project Area 6.27 AC Existing Impervious Area 6.18 AC Proposed Impervious Area 4.84 AC Change in Impervious Area 1.34 AC Reduction Table 1: Impervious Area Summary Proposed LID and Water Quality Treatment This LID system will also provide water quality treatment for the proposed roadway drainage. The underground system outflow discharges to a private storm trunk line that is aligned between the proposed property lines for Lots 1 and 2. A private storm sewer connection conveying the 100-YR developed flow has been provided as a part of the project. The storm drain will convey flows to the existing storm drain within S. College Ave. The private storm drain will connect to the existing facilities at a new triple combination inlet to be constructed by the project. The existing storm sewer system along S. College Ave. uses a series of 15” RCP storm sewer and small curb inlets. These existing facilities are undersized for the 100-YR flows. The City has identified this area for a future capital improvement project that would upsize the existing system. The Project storm system has been designed to connect to the future improvements. In the interim, an inverted syphon condition will exist where flow exceeding the S College Ave. storm drain capacity would surcharge and overtop the proposed triple combination inlet and flow to the north along the curb. Additionally, a conveyance swale is located between Lots 1 and 2 that will convey drainage between the two lots to the private storm line. The swale was sized to provide up to 4.69 cfs. The hydraulic calculations for the swale, along with the storm sewer and inlets are included within Appendix C. Adjacent lots will need to connect to the private storm sewer. Minor flows and major flows within the proposed roadway will be conveyed via the street curb and gutter prior to entering storm inlets located in the roadway. Street conveyance will be minimized wherever possible and will be designed to maintain access for emergency vehicles. Meanwhile, the Minor and Major flows of the proposed future lots will be conveyed via the private storm sewer trunk line. A bypass storm structure is proposed prior to the underground system to provide overflow for the roadway drainage that exceeds the water quality event. LID is required to treat 75% of all newly added or modified impervious area based on FCSCM Section 2.3.7. These impervious areas are depicted within the Proposed Impervious Exhibit as a part of Appendix B. Note that the roadway drainage for sub-basins R1 and R2 will route to an underground system that will serve as a LID treatment and provide water quality treatment. This drainage area of 21,287 square feet exceeds the required LID amount. Overall Development Plan and Final Drainage and Erosion Control Report SWC Drake/College – Fort Collins, Colorado 7 | P a g e The Water Quality Capture Volume (WQCV) for the developed site was calculated using equation 7-1 in the FCSCM. A 12-hour drain time based on Equation 7-1 and Table 5.1-1 was used to determine the minimum required WQCV for the area draining to the underground system. Table 2 shows the required and provided water quality and LID volumes for the proposed roadway improvements. See calculations included in Appendix B. Water Quality and LID Values Impervious Area for Proposed Roadway Improvements 26,476 SF Required LID Impervious Area 19,857 SF Provided LID Impervious Area (Captured Area of Sub-basins R1 and R2) 21,287 SF Required Water Quality Volume 948 CF Provided Water Quality Volume 972 CF Table 2: Water Quality and LID Summary The site consisted of predominately impervious surface that received no detention or water quality prior to leaving the site and entering the existing storm inlets within S. College Avenue. As a result, the drainage runoff for the proposed perimeter sidewalk, outside of the proposed right-of-way will not be attenuated but will receive water quality treatment through the vegetative buffer along the proposed parkway before entering the existing storm inlets within S. College Avenue. The underground system and isolator rows were sized according to the FCSTM and the associated calculations are included within Appendix B. Additionally, isolator rows will be installed where the private storm enters the underground system. A drainage easement encompassing the entire footprint of the underground system and private storm lines will be dedicated to the City of Fort Collins. The proposed underground system is placed in a location such that it is accessible for inspections and maintenance. IX. DRAINAGE DESIGN CRITERIA The Project was designed to conform to the requirements outlined in the Fort Collins Stormwater Criteria Manual (FCSCM) and the latest Mile High Flood District (MHFD) Urban Storm Drainage Criteria Manual (USDCM). A Four Step Process was implemented for the drainage design and protection of receiving water bodies: Step 1 - Runoff Reduction Practices Runoff is routed through vegetated buffers via sheet flow wherever reasonably possible to increase time of concentration and promote infiltration. By Minimizing Directly Connected Impervious Areas (MDCIA), peak runoff volumes and pollutant loads are reduced. Step 2 – Implement Best Management Practices (BMPs) to treat the WQCV A LID underground system is proposed that will provide treatment for the WQCV with slow release and/or infiltration. Overall Development Plan and Final Drainage and Erosion Control Report SWC Drake/College – Fort Collins, Colorado 8 | P a g e Step 3 – Stabilizing Streams Stream stabilization was considered but not implemented due to open channels being minimized for site accessibility. Step 4 – Implementing Site Specific and Other Source Control BMPs Site specific controls that will be implemented include locating material storage away from storm drainage facilities and installing construction fencing around the existing regional pond to protect areas that should not be compacted or disturbed. The Rational Method was used for all subbasins with areas less than 90 acres. Per the FCSCM, the storm frequencies used to analyze the drainage design were the 2-year and the 100-year storms. The FCSCM Tables 3.2-1, 3.2-2, and 3.2-3 were utilized to determine the stormwater runoff coefficients. Rainfall intensities used for the rational calculations were obtained from Table 3.4-1 in the FCSCM. Rainfall depths are shown in Table 3 below. One-Hour Rainfall Depths 2 YR 0.82 inches 100 YR 2.86 inches Table 3: One-hour Rainfall Depths Summary Hydraulic calculations have been included within Appendix C. These calculations include analysis of the storm sewer analysis, street capacity, inlet sizing, and an interim swale located between Lots 1 and 2. Note that the rational calculations include the assumed “build-out” condition for the future lots so that the proposed private storm sewer may be adequately sized. X. VARIANCE REQUESTS No variances are requested at this time. XI. EROSION CONTROL During construction, temporary erosion and sediment control practices will be used to limit soil erosion and migration of sediment off site. An erosion control report has been provided as a separate document. XII. CONCLUSION The SWC Drake/College site is designed to conform to the criteria in the FCSCM and the USDCM. The proposed underground system provides LID and is designed to treat the water quality for the proposed roadways within the Project. Future lots will be responsible for their own respective LID and water quality treatment. Overall Development Plan and Final Drainage and Erosion Control Report SWC Drake/College – Fort Collins, Colorado 9 | P a g e X. REFERENCES City of Fort Collins Flood Maps, City of Fort Collins GIS, Accessed November 5, 2024, at <https://gisweb.fcgov.com/HTML5Viewer/Index.html?viewer=FCMaps&LayerTheme=flo odplains> Custom Soil Resource Report, Natural Resources Conservation Service, United States Department of Agriculture. Web Soil Survey. November 5, 2024. Fort Collins Stormwater Criteria Manual, City of Fort Collins, December 2018. National Flood Hazard Layer Firmette, Federal Emergency Management Agency; Accessed November 5, 2024. Urban Storm Drainage Criteria Manual, Volumes 1-3, Mile High Flood District, Updated March 2024. Overall Development Plan and Final Drainage and Erosion Control Report SWC Drake/College – Fort Collins, Colorado Appendix A – Referenced Criteria Overall Development Plan and Final Drainage Report Drake and College Mixed-Use – Fort Collins, Colorado Appendix B – Hydrologic Calculations and Exhibits Overall Development Plan and Final Drainage Report Drake and College Mixed-Use – Fort Collins, Colorado Appendix C – Hydraulic Calculations Final Drainage Report Drake and College Mixed-Use – Fort Collins, Colorado Appendix A – Referenced Criteria Date: Included N/A Include name of project, date, name of design engineer Statement of compliance with the manual FP Final copies required to be stamped and signed by Colorado licensed PE Section, Township, Range Vicinity Map Roadways within and adjacent to site Names of surrounding developments Master Drainage Basin where site is located Existing stormwater drainage facilities and drainage patterns Existing irrigation facilities (if applicable) Existing land uses Existing ground cover and/or vegetation type Existing soils info Reference/discussion regarding pertinent Master Drainage Basin and any improvements planned for the area General basin characteristics Existing and planned land uses within the Master Drainage Basin Irrigation facilities that influence or are influenced by the local drainage (if applicable) Refer to Floodplain Checklists for requirements Proposed land uses and/or project summary Site acreage Discussion of proposed drainage plan, specific details that may include drainage issues at specific design points Conveyance of minor and major stormwater systems to an existing stormwater conveyance Detention basin and outlet design; summary table for each detention basin WQCV design LID systems and design Maintenance access to the drainage facilities Easements/tracts for drainage purposes Reference to any previous drainage studies for the area Four‐Step process outlined and discussed Using CoFC rainfall data for 2‐yr and 100‐yr recurrence intervals Using proper design storm recurrences (2‐yr and 100‐yr) Runoff calculation method Detention calculation method FP Street Capacity discussion FP Inlet Capacity discussion PDP and FP Drainage Report Checklist Project Name: General Location & Existing Site Info Master Drainage Basin Info Floodplain Information Cover Letter Project Description Proposed Drainage Facilities Drainage Design Criteria Page 1 of 2 Date: Included N/A PDP and FP Drainage Report Checklist Project Name: FP Pipe network models discussion FP Swale or channel sizing/capacity discussion FP Emergency spillway sizing discussion Included variance request form Statement of compliance with all erosion control materials that are to be provided with final plans FP Separate Erosion Control Report and Plans submitted Statement of compliance with manual, master drainage plans, floodplain regs, other state/federal regs Summary conclusion of drainage concept and effectiveness of design Referenced criteria, master plans, technical info Hydologic calculations: historic and developed runoff Detention basin volume calculations SDI data spreadsheet (meets detention drain time criteria) SWMM models (if applicable) LID exhibit and calculations Floodplain maps Soil survey information FP Street capacity FP Inlet sizing and capacity FP Storm pipe network models FP Erosion protection (i.e. riprap calculations) FP Swale or channel sizing FP Outlet structure design FP Spillway design Drainage map Conclusion References Appendices Variance Requests Erosion Control Page 2 of 2 T r o u t m a nParkPond SpringCreek Dragonfly Pond Heron Pond New Mercer Ditch Warren L a ke Fossil Creek Reservoir Inlet Pleasant Valley and Lake Canal Sprin g C reek LarimerCountyCanal#2 S p r i n g C r e e kParkPond W o o d w a r dGoverno rPond Parkwood L a k e P r o s p e c t P o n d #2North Larimer County Canal#2 O a k R i dg eFederalBld gPond H a r m onyReservoir G o l d e nMeadow sPond Canvasback Pond Foothills Channel R o l l a n dMoorePond F t C o l l i n sGolfCoursePond A v e r yPond Spring Creek SherwoodLateral LakeSherwood Cachela Poudre River Larimer County Canal #2 New Mercer Ditch NewMercer Ditch B i g P o n d W e s t M i l n eP o n d Larimer County Canal #2 O a k R i d g eFederalBld gPond DixonCanyonLateral C o n f l u e n c e a n d W i g e o n Po n d s E a s t M i l n e P o n d FOOTHIL LS BASIN K FOO THILLS BASIN United States Department of Agriculture A product of the National Cooperative Soil Survey, a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local participants Custom Soil Resource Report for Larimer County Area, ColoradoNatural Resources Conservation Service November 5, 2024 Preface Soil surveys contain information that affects land use planning in survey areas. They highlight soil limitations that affect various land uses and provide information about the properties of the soils in the survey areas. Soil surveys are designed for many different users, including farmers, ranchers, foresters, agronomists, urban planners, community officials, engineers, developers, builders, and home buyers. Also, conservationists, teachers, students, and specialists in recreation, waste disposal, and pollution control can use the surveys to help them understand, protect, or enhance the environment. Various land use regulations of Federal, State, and local governments may impose special restrictions on land use or land treatment. Soil surveys identify soil properties that are used in making various land use or land treatment decisions. The information is intended to help the land users identify and reduce the effects of soil limitations on various land uses. The landowner or user is responsible for identifying and complying with existing laws and regulations. Although soil survey information can be used for general farm, local, and wider area planning, onsite investigation is needed to supplement this information in some cases. Examples include soil quality assessments (http://www.nrcs.usda.gov/wps/ portal/nrcs/main/soils/health/) and certain conservation and engineering applications. For more detailed information, contact your local USDA Service Center (https://offices.sc.egov.usda.gov/locator/app?agency=nrcs) or your NRCS State Soil Scientist (http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/contactus/? cid=nrcs142p2_053951). Great differences in soil properties can occur within short distances. Some soils are seasonally wet or subject to flooding. Some are too unstable to be used as a foundation for buildings or roads. Clayey or wet soils are poorly suited to use as septic tank absorption fields. A high water table makes a soil poorly suited to basements or underground installations. The National Cooperative Soil Survey is a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local agencies. The Natural Resources Conservation Service (NRCS) has leadership for the Federal part of the National Cooperative Soil Survey. Information about soils is updated periodically. Updated information is available through the NRCS Web Soil Survey, the site for official soil survey information. The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or a part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require 2 alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer. 3 Contents Preface....................................................................................................................2 How Soil Surveys Are Made..................................................................................5 Soil Map..................................................................................................................8 Soil Map................................................................................................................9 Legend................................................................................................................10 Map Unit Legend................................................................................................11 Map Unit Descriptions.........................................................................................11 Larimer County Area, Colorado......................................................................13 73—Nunn clay loam, 0 to 1 percent slopes.................................................13 References............................................................................................................15 4 How Soil Surveys Are Made Soil surveys are made to provide information about the soils and miscellaneous areas in a specific area. They include a description of the soils and miscellaneous areas and their location on the landscape and tables that show soil properties and limitations affecting various uses. Soil scientists observed the steepness, length, and shape of the slopes; the general pattern of drainage; the kinds of crops and native plants; and the kinds of bedrock. They observed and described many soil profiles. A soil profile is the sequence of natural layers, or horizons, in a soil. The profile extends from the surface down into the unconsolidated material in which the soil formed or from the surface down to bedrock. The unconsolidated material is devoid of roots and other living organisms and has not been changed by other biological activity. Currently, soils are mapped according to the boundaries of major land resource areas (MLRAs). MLRAs are geographically associated land resource units that share common characteristics related to physiography, geology, climate, water resources, soils, biological resources, and land uses (USDA, 2006). Soil survey areas typically consist of parts of one or more MLRA. The soils and miscellaneous areas in a survey area occur in an orderly pattern that is related to the geology, landforms, relief, climate, and natural vegetation of the area. Each kind of soil and miscellaneous area is associated with a particular kind of landform or with a segment of the landform. By observing the soils and miscellaneous areas in the survey area and relating their position to specific segments of the landform, a soil scientist develops a concept, or model, of how they were formed. Thus, during mapping, this model enables the soil scientist to predict with a considerable degree of accuracy the kind of soil or miscellaneous area at a specific location on the landscape. Commonly, individual soils on the landscape merge into one another as their characteristics gradually change. To construct an accurate soil map, however, soil scientists must determine the boundaries between the soils. They can observe only a limited number of soil profiles. Nevertheless, these observations, supplemented by an understanding of the soil-vegetation-landscape relationship, are sufficient to verify predictions of the kinds of soil in an area and to determine the boundaries. Soil scientists recorded the characteristics of the soil profiles that they studied. They noted soil color, texture, size and shape of soil aggregates, kind and amount of rock fragments, distribution of plant roots, reaction, and other features that enable them to identify soils. After describing the soils in the survey area and determining their properties, the soil scientists assigned the soils to taxonomic classes (units). Taxonomic classes are concepts. Each taxonomic class has a set of soil characteristics with precisely defined limits. The classes are used as a basis for comparison to classify soils systematically. Soil taxonomy, the system of taxonomic classification used in the United States, is based mainly on the kind and character of soil properties and the arrangement of horizons within the profile. After the soil 5 scientists classified and named the soils in the survey area, they compared the individual soils with similar soils in the same taxonomic class in other areas so that they could confirm data and assemble additional data based on experience and research. The objective of soil mapping is not to delineate pure map unit components; the objective is to separate the landscape into landforms or landform segments that have similar use and management requirements. Each map unit is defined by a unique combination of soil components and/or miscellaneous areas in predictable proportions. Some components may be highly contrasting to the other components of the map unit. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The delineation of such landforms and landform segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, onsite investigation is needed to define and locate the soils and miscellaneous areas. Soil scientists make many field observations in the process of producing a soil map. The frequency of observation is dependent upon several factors, including scale of mapping, intensity of mapping, design of map units, complexity of the landscape, and experience of the soil scientist. Observations are made to test and refine the soil-landscape model and predictions and to verify the classification of the soils at specific locations. Once the soil-landscape model is refined, a significantly smaller number of measurements of individual soil properties are made and recorded. These measurements may include field measurements, such as those for color, depth to bedrock, and texture, and laboratory measurements, such as those for content of sand, silt, clay, salt, and other components. Properties of each soil typically vary from one point to another across the landscape. Observations for map unit components are aggregated to develop ranges of characteristics for the components. The aggregated values are presented. Direct measurements do not exist for every property presented for every map unit component. Values for some properties are estimated from combinations of other properties. While a soil survey is in progress, samples of some of the soils in the area generally are collected for laboratory analyses and for engineering tests. Soil scientists interpret the data from these analyses and tests as well as the field-observed characteristics and the soil properties to determine the expected behavior of the soils under different uses. Interpretations for all of the soils are field tested through observation of the soils in different uses and under different levels of management. Some interpretations are modified to fit local conditions, and some new interpretations are developed to meet local needs. Data are assembled from other sources, such as research information, production records, and field experience of specialists. For example, data on crop yields under defined levels of management are assembled from farm records and from field or plot experiments on the same kinds of soil. Predictions about soil behavior are based not only on soil properties but also on such variables as climate and biological activity. Soil conditions are predictable over long periods of time, but they are not predictable from year to year. For example, soil scientists can predict with a fairly high degree of accuracy that a given soil will have a high water table within certain depths in most years, but they cannot predict that a high water table will always be at a specific level in the soil on a specific date. After soil scientists located and identified the significant natural bodies of soil in the survey area, they drew the boundaries of these bodies on aerial photographs and Custom Soil Resource Report 6 identified each as a specific map unit. Aerial photographs show trees, buildings, fields, roads, and rivers, all of which help in locating boundaries accurately. Custom Soil Resource Report 7 Soil Map The soil map section includes the soil map for the defined area of interest, a list of soil map units on the map and extent of each map unit, and cartographic symbols displayed on the map. Also presented are various metadata about data used to produce the map, and a description of each soil map unit. 8 9 Custom Soil Resource Report Soil Map 44 8 8 9 1 0 44 8 8 9 4 0 44 8 8 9 7 0 44 8 9 0 0 0 44 8 9 0 3 0 44 8 9 0 6 0 44 8 9 0 9 0 44 8 8 9 1 0 44 8 8 9 4 0 44 8 8 9 7 0 44 8 9 0 0 0 44 8 9 0 3 0 44 8 9 0 6 0 44 8 9 0 9 0 493200 493230 493260 493290 493320 493350 493380 493410 493440 493470 493500 493200 493230 493260 493290 493320 493350 493380 493410 493440 493470 493500 40° 33' 9'' N 10 5 ° 4 ' 4 9 ' ' W 40° 33' 9'' N 10 5 ° 4 ' 3 6 ' ' W 40° 33' 2'' N 10 5 ° 4 ' 4 9 ' ' W 40° 33' 2'' N 10 5 ° 4 ' 3 6 ' ' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 0 50 100 200 300 Feet 0 20 40 80 120 Meters Map Scale: 1:1,410 if printed on A landscape (11" x 8.5") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Larimer County Area, Colorado Survey Area Data: Version 19, Aug 29, 2024 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Jul 2, 2021—Aug 25, 2021 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Custom Soil Resource Report 10 Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 73 Nunn clay loam, 0 to 1 percent slopes 6.7 100.0% Totals for Area of Interest 6.7 100.0% Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils. Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, however, onsite investigation is needed to define and locate the soils and miscellaneous areas. Custom Soil Resource Report 11 An identifying symbol precedes the map unit name in the map unit descriptions. Each description includes general facts about the unit and gives important soil properties and qualities. Soils that have profiles that are almost alike make up a soil series. Except for differences in texture of the surface layer, all the soils of a series have major horizons that are similar in composition, thickness, and arrangement. Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity, degree of erosion, and other characteristics that affect their use. On the basis of such differences, a soil series is divided into soil phases. Most of the areas shown on the detailed soil maps are phases of soil series. The name of a soil phase commonly indicates a feature that affects use or management. For example, Alpha silt loam, 0 to 2 percent slopes, is a phase of the Alpha series. Some map units are made up of two or more major soils or miscellaneous areas. These map units are complexes, associations, or undifferentiated groups. A complex consists of two or more soils or miscellaneous areas in such an intricate pattern or in such small areas that they cannot be shown separately on the maps. The pattern and proportion of the soils or miscellaneous areas are somewhat similar in all areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example. An association is made up of two or more geographically associated soils or miscellaneous areas that are shown as one unit on the maps. Because of present or anticipated uses of the map units in the survey area, it was not considered practical or necessary to map the soils or miscellaneous areas separately. The pattern and relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha-Beta association, 0 to 2 percent slopes, is an example. An undifferentiated group is made up of two or more soils or miscellaneous areas that could be mapped individually but are mapped as one unit because similar interpretations can be made for use and management. The pattern and proportion of the soils or miscellaneous areas in a mapped area are not uniform. An area can be made up of only one of the major soils or miscellaneous areas, or it can be made up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example. Some surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example. Custom Soil Resource Report 12 Larimer County Area, Colorado 73—Nunn clay loam, 0 to 1 percent slopes Map Unit Setting National map unit symbol: 2tlng Elevation: 4,100 to 5,700 feet Mean annual precipitation: 14 to 15 inches Mean annual air temperature: 48 to 52 degrees F Frost-free period: 135 to 152 days Farmland classification: Prime farmland if irrigated Map Unit Composition Nunn and similar soils:85 percent Minor components:15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Nunn Setting Landform:Terraces Landform position (three-dimensional):Tread Down-slope shape:Linear Across-slope shape:Linear Parent material:Pleistocene aged alluvium and/or eolian deposits Typical profile Ap - 0 to 6 inches: clay loam Bt1 - 6 to 10 inches: clay loam Bt2 - 10 to 26 inches: clay loam Btk - 26 to 31 inches: clay loam Bk1 - 31 to 47 inches: loam Bk2 - 47 to 80 inches: loam Properties and qualities Slope:0 to 1 percent Depth to restrictive feature:More than 80 inches Drainage class:Well drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat):Moderately low to moderately high (0.06 to 0.20 in/hr) Depth to water table:More than 80 inches Frequency of flooding:None Frequency of ponding:None Calcium carbonate, maximum content:7 percent Maximum salinity:Nonsaline (0.1 to 1.0 mmhos/cm) Sodium adsorption ratio, maximum:0.5 Available water supply, 0 to 60 inches: High (about 9.1 inches) Interpretive groups Land capability classification (irrigated): 3e Land capability classification (nonirrigated): 4e Hydrologic Soil Group: C Ecological site: R067BY042CO - Clayey Plains Hydric soil rating: No Custom Soil Resource Report 13 Minor Components Heldt Percent of map unit:10 percent Landform:Terraces Landform position (three-dimensional):Tread Down-slope shape:Linear Across-slope shape:Linear Ecological site:R067BY042CO - Clayey Plains Hydric soil rating: No Wages Percent of map unit:5 percent Landform:Terraces Landform position (three-dimensional):Tread Down-slope shape:Linear Across-slope shape:Linear Ecological site:R067BY002CO - Loamy Plains Hydric soil rating: No Custom Soil Resource Report 14 References American Association of State Highway and Transportation Officials (AASHTO). 2004. Standard specifications for transportation materials and methods of sampling and testing. 24th edition. American Society for Testing and Materials (ASTM). 2005. Standard classification of soils for engineering purposes. ASTM Standard D2487-00. Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of wetlands and deep-water habitats of the United States. U.S. Fish and Wildlife Service FWS/OBS-79/31. Federal Register. July 13, 1994. Changes in hydric soils of the United States. Federal Register. September 18, 2002. Hydric soils of the United States. Hurt, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric soils in the United States. National Research Council. 1995. Wetlands: Characteristics and boundaries. Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service. U.S. Department of Agriculture Handbook 18. http://www.nrcs.usda.gov/wps/portal/ nrcs/detail/national/soils/?cid=nrcs142p2_054262 Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for making and interpreting soil surveys. 2nd edition. Natural Resources Conservation Service, U.S. Department of Agriculture Handbook 436. http:// www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053577 Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department of Agriculture, Natural Resources Conservation Service. http:// www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053580 Tiner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and Delaware Department of Natural Resources and Environmental Control, Wetlands Section. United States Army Corps of Engineers, Environmental Laboratory. 1987. Corps of Engineers wetlands delineation manual. Waterways Experiment Station Technical Report Y-87-1. United States Department of Agriculture, Natural Resources Conservation Service. National forestry manual. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/ home/?cid=nrcs142p2_053374 United States Department of Agriculture, Natural Resources Conservation Service. National range and pasture handbook. http://www.nrcs.usda.gov/wps/portal/nrcs/ detail/national/landuse/rangepasture/?cid=stelprdb1043084 15 United States Department of Agriculture, Natural Resources Conservation Service. National soil survey handbook, title 430-VI. http://www.nrcs.usda.gov/wps/portal/ nrcs/detail/soils/scientists/?cid=nrcs142p2_054242 United States Department of Agriculture, Natural Resources Conservation Service. 2006. Land resource regions and major land resource areas of the United States, the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook 296. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/? cid=nrcs142p2_053624 United States Department of Agriculture, Soil Conservation Service. 1961. Land capability classification. U.S. Department of Agriculture Handbook 210. http:// www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052290.pdf Custom Soil Resource Report 16 National Flood Hazard Layer FIRMette 0 500 1,000 1,500 2,000250 Feet Ü SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT SPECIAL FLOOD HAZARD AREAS Without Base Flood Elevation (BFE) Zone A, V, A99 With BFE or Depth Zone AE, AO, AH, VE, AR Regulatory Floodway 0.2% Annual Chance Flood Hazard, Areas of 1% annual chance flood with average depth less than one foot or with drainage areas of less than one square mile Zone X Future Conditions 1% Annual Chance Flood Hazard Zone X Area with Reduced Flood Risk due to Levee. See Notes.Zone X Area with Flood Risk due to Levee Zone D NO SCREEN Area of Minimal Flood Hazard Zone X Area of Undetermined Flood Hazard Zone D Channel, Culvert, or Storm Sewer Levee, Dike, or Floodwall Cross Sections with 1% Annual Chance 17.5 Water Surface Elevation Coastal Transect Coastal Transect Baseline Profile Baseline Hydrographic Feature Base Flood Elevation Line (BFE) Effective LOMRs Limit of Study Jurisdiction Boundary Digital Data Available No Digital Data Available Unmapped This map complies with FEMA's standards for the use of digital flood maps if it is not void as described below. The basemap shown complies with FEMA's basemap accuracy standards The flood hazard information is derived directly from the authoritative NFHL web services provided by FEMA. This map was exported on 11/5/2024 at 11:44 PM and does not reflect changes or amendments subsequent to this date and time. The NFHL and effective information may change or become superseded by new data over time. This map image is void if the one or more of the following map elements do not appear: basemap imagery, flood zone labels, legend, scale bar, map creation date, community identifiers, FIRM panel number, and FIRM effective date. Map images for unmapped and unmodernized areas cannot be used for regulatory purposes. Legend OTHER AREAS OF FLOOD HAZARD OTHER AREAS GENERAL STRUCTURES OTHER FEATURES MAP PANELS 8 B 20.2 The pin displayed on the map is an approximate point selected by the user and does not represent an authoritative property location. 1:6,000 105°5'1"W 40°33'21"N 105°4'23"W 40°32'54"N Basemap Imagery Source: USGS National Map 2023 2,257 376.2 City of Fort Collins Flood Map This map is a user generated static output from the City of Fort Collins FCMaps Internet mapping site and is for reference only. Data layers that appear on this map may or may not be accurate, current, or otherwise reliable. City of Fort Collins - GIS 286.0 1: WGS_1984_Web_Mercator_Auxiliary_Sphere Feet286.00143.00 Notes Legend 1,715 Street Names FEMA Floodplain FEMA High Risk - Floodway FEMA High Risk - 100 Year FEMA Moderate Risk - 100 / 500 Year City Floodplains City High Risk - Floodway City High Risk - 100 Year City Moderate Risk - 100 Year City Limits Final Drainage Report Drake and College Mixed-Use – Fort Collins, Colorado Appendix B – Hydrologic Calculations and Exhibits TIME 2 YR 10 YR 100 YR 5 2.85 4.87 9.95 6 2.67 4.56 9.31 7 2.52 4.31 8.80 8 2.40 4.10 8.38 9 2.30 3.93 8.03 10 2.21 3.78 7.72 11 2.13 3.63 7.42 12 2.05 3.50 7.16 13 1.98 3.39 6.92 14 1.92 3.29 6.71 15 1.87 3.19 6.52 20 1.61 2.74 5.60 25 1.43 2.44 4.98 30 1.30 2.21 4.52 40 1.07 1.83 3.74 50 0.92 1.58 3.23 60 0.82 1.40 2.86 120 0.49 0.86 1.84 Note: Time Intensity Frequency Tabulation Intensity values from the City of Fort Collins Intensity-Duration-Frequency Tables; Chapter 5, Section 3.4 of the Fort Collins Stormwater Criteria Manual, 2018 Edition. RAINFALL INTENSITY K:\NCO_Civil\096315014_Kentro Drake-College\Project Files\Eng\Drainage\EX CIA Calcs.xlsx PROJECT NAME: Drake and College Mixed Use 4/7/2025 PROJECT NUMBER: 96315014 CALCULATED BY: BAW CHECKED BY:AGR SOIL: GROUP C Lawns, Clayey Soil Rooftop Asphalt, Concrete Gravel/Pavers LAND USE:AREA AREA AREA AREA 2-YEAR COEFF. 0.20 0.95 0.95 0.50 100-YEAR COEFF. 0.25 1.00 1.00 0.63 IMPERVIOUS %2%90%100%40% Lawns, Clayey Soil Rooftop Asphalt, Concrete Gravel/Pavers TOTAL DESIGN DESIGN AREA AREA AREA AREA AREA BASIN POINT (AC)(AC)(AC)(AC)(AC)C(2)C(100)Imp % EX-A EX-A 0.00 0.40 2.72 0.00 3.13 0.95 1.00 99% EX-B EX-B 0.00 0.00 1.45 0.00 1.45 0.95 1.00 100% EX-C EX-C 0.03 0.24 1.43 0.00 1.69 0.94 0.99 97% 0.03 0.64 5.60 0.00 6.27 0.95 1.00 99% 0%10%89%0%BASIN SUBTOTAL On-Site Basins Flowing On-site RUNOFF COEFFICIENTS - EX. IMPERVIOUS CALCULATION K:\NCO_Civil\096315014_Kentro Drake-College\Project Files\Eng\Drainage\EX CIA Calcs.xlsx Drake and College Mixed Use DATE:4/7/2025 96315014 BAW AGR FINAL Tc DESIGN AREA C2 LENGTH SLOPE Ti LENGTH SLOPE R VEL Tt COMP. TOTAL TOTAL TOTAL Tc BASIN Ac Ft %Min.Ft.%fps Min.tc LENGTH SLOPE IMP.Min.Min. EX-A 3.13 0.95 200 1.5% 3.5 240 1.5% 0.195 1.8 2.3 5.7 440 1.5% 99% 12.4 5.7 EX-B 1.45 0.95 200 1.5% 3.5 165 1.5% 0.195 1.8 1.6 5.0 365 1.5% 100% 12.0 5.0 EX-C 1.69 0.94 200 1.5% 3.7 90 1.5% 0.195 1.8 0.9 4.6 290 1.5% 97% 11.6 5.0 CHECKED BY: On-Site Basins 2-Year Time of Concentration Tc CHECK (URBANIZED BASINS) PROJECT NAME: PROJECT NUMBER: DATA INITIAL TIME (Ti) TRAVEL TIME (Tt) SUB-BASIN CALCULATED BY: K:\NCO_Civil\096315014_Kentro Drake-College\Project Files\Eng\Drainage\EX CIA Calcs.xlsx Drake and College Mixed Use DATE:4/7/2025 96315014 BAW AGR FINAL Tc DESIGN AREA C100 LENGTH SLOPE Ti LENGTH SLOPE R VEL Tt COMP. TOTAL TOTAL TOTAL Tc BASIN Ac Ft %Min.Ft.%fps Min.tc LENGTH SLOPE IMP.Min.Min. EX-A 3.13 1.00 200 1.5% 2.3 240 1.5% 0.195 1.8 2.3 4.6 440 1.5% 99% 12.4 5.0 EX-B 1.45 1.00 200 1.5% 2.3 165 1.5% 0.195 1.8 1.6 3.9 365 1.5% 100% 12.0 5.0 EX-C 1.69 0.99 200 1.5% 2.6 90 1.5% 0.195 1.8 0.9 3.4 290 1.5% 97% 11.6 5.0 CHECKED BY: 100-Year Time of Concentration PROJECT NAME: PROJECT NUMBER: CALCULATED BY: On-Site Basins SUB-BASIN INITIAL TRAVEL TIME Tc CHECK DATA TIME (Ti) (Tt) (URBANIZED BASINS) K:\NCO_Civil\096315014_Kentro Drake-College\Project Files\Eng\Drainage\EX CIA Calcs.xlsx DATE: 4/7/2025 Drake and College Mixed Use 96315014 BAW P1 (1-Hour Rainfall) =0.82 AGR REMARKS DE S I G N PO I N T AR E A (A C ) RU N O F F CO E F F tc (m i n ) C* A ( a c ) I (i n / h r ) Q (c f s ) EX-A 3.13 0.95 5.75 2.97 2.85 8.46 Existing Drainage Flows EX-B 1.45 0.95 5.03 1.38 2.85 3.93 Existing Drainage Flows EX-C 1.69 0.94 5.00 1.59 2.85 4.52 Existing Drainage Flows On-Site Basins EX-C EX-A EX-B STORM DRAINAGE DESIGN - RATIONAL METHOD 2 YEAR EVENT PROJECT NAME: PROJECT NUMBER: CALCULATED BY: CHECKED BY: DE S G I N BA S I N K:\NCO_Civil\096315014_Kentro Drake-College\Project Files\Eng\Drainage\EX CIA Calcs.xlsx DATE: 4/7/2025 Drake and College Mixed Use 96315014 BAW P1 (1-Hour Rainfall) =2.86 AGR REMARKS DE S I G N PO I N T AR E A (A C ) RU N O F F CO E F F tc (m i n ) C* A ( a c ) I (i n / h r ) Q (c f s ) EX-A 3.13 1.00 5.75 3.13 9.95 31.10 Existing Drainage Flows EX-B 1.45 1.00 5.03 1.45 9.95 14.43 Existing Drainage Flows EX-C 1.69 0.99 5.00 1.67 9.95 16.64 Existing Drainage Flows CHECKED BY: CALCULATED BY: STORM DRAINAGE DESIGN - RATIONAL METHOD 100 YEAR EVENT PROJECT NAME: PROJECT NUMBER: DE S I G N BA S I N On-Site Basins EX-A EX-B EX-C K:\NCO_Civil\096315014_Kentro Drake-College\Project Files\Eng\Drainage\EX CIA Calcs.xlsx PROJECT NAME: Drake and College Mixed Use DATE: 4/7/2025 PROJECT NUMBER: 96315014 CALCULATED BY: BAW CHECKED BY: AGR IMPERVIOUSNESS % Q2 Q100 EX-A EX-A 3.13 99%8.46 31.10 EX-B EX-B 1.45 100%3.93 14.43 EX-C EX-C 1.69 97% 4.52 16.64 6.27 99%16.91 62.17 On-Site Basins Flowing On-Site DESIGN POINT RATIONAL CALCULATIONS SUMMARY TRIBUTARY BASINS TRIBUTARY AREA (AC) PEAK FLOWS (CFS) TOTAL K:\NCO_Civil\096315014_Kentro Drake-College\Project Files\Eng\Drainage\EX CIA Calcs.xlsx TIME 2 YR 10 YR 100 YR 5 2.85 4.87 9.95 6 2.67 4.56 9.31 7 2.52 4.31 8.80 8 2.40 4.10 8.38 9 2.30 3.93 8.03 10 2.21 3.78 7.72 11 2.13 3.63 7.42 12 2.05 3.50 7.16 13 1.98 3.39 6.92 14 1.92 3.29 6.71 15 1.87 3.19 6.52 20 1.61 2.74 5.60 25 1.43 2.44 4.98 30 1.30 2.21 4.52 40 1.07 1.83 3.74 50 0.92 1.58 3.23 60 0.82 1.40 2.86 120 0.49 0.86 1.84 Note: Time Intensity Frequency Tabulation Intensity values from the City of Fort Collins Intensity-Duration-Frequency Tables; Chapter 5, Section 3.4 of the Fort Collins Stormwater Criteria Manual, 2018 Edition. RAINFALL INTENSITY K:\NCO_Civil\096315014_Kentro Drake-College\Project Files\Eng\Drainage\PR CIA Calcs.xlsx PROJECT NAME:Drake and College Mixed Use 4/7/2025 PROJECT NUMBER:96315014 CALCULATED BY:BAW CHECKED BY:AGR SOIL: GROUP C Lawns, Clayey Soil Rooftop Asphalt, Concrete Gravel/Pavers Commercial LAND USE:AREA AREA AREA AREA AREA 2-YEAR COEFF.0.20 0.95 0.95 0.50 0.85 100-YEAR COEFF.0.25 1.00 1.00 0.63 1.00 IMPERVIOUS %2%90%100%40%80% Lawns, Clayey Soil Rooftop Asphalt, Concrete Gravel/Pavers Commercial TOTAL DESIGN DESIGN AREA AREA AREA AREA AREA AREA BASIN POINT (AC)(AC)(AC)(AC)(AC)(AC)C(2)C(100)Imp % 1A 1A 0.00 0.00 0.00 0.00 0.98 0.98 0.85 1.00 80% 2B 2B 0.00 0.00 0.00 0.00 0.55 0.55 0.85 1.00 80% 3A 3A 0.00 0.00 0.00 0.00 1.25 1.25 0.85 1.00 80% 4A 4A 0.00 0.00 0.00 0.00 1.99 1.99 0.85 1.00 80% R1 R1 0.03 0.00 0.39 0.00 0.10 0.52 0.89 0.96 91% R2 R2 0.02 0.00 0.10 0.00 0.06 0.18 0.83 0.92 82% 0.05 0.00 0.49 0.00 4.93 5.47 0.85 0.99 81% 1%0%9%0%90% 1B 1B 0.00 0.00 0.00 0.00 0.16 0.16 0.85 1.00 80% 3B 3B 0.00 0.00 0.00 0.00 0.17 0.17 0.85 1.00 80% 4B 4B 0.00 0.00 0.00 0.00 0.15 0.15 0.85 1.00 80% OS1 OS1 0.00 0.00 0.05 0.00 0.02 0.06 0.69 0.91 95% OS2 OS2 0.01 0.00 0.03 0.00 0.00 0.04 0.73 0.98 72% OS3 OS3 0.01 0.00 0.04 0.00 0.03 0.08 0.55 0.73 82% OS4 OS4 0.13 0.00 0.00 0.00 0.00 0.13 0.20 0.31 2% 0.15 0.00 0.12 0.00 0.53 0.80 0.74 0.86 68% 19%0%15%0%66% R1 & R2 R1 & R2 0.05 0.00 0.49 0.00 0.16 0.69 0.68 0.90 89% 7%0%71%0%23% Notes: 1. Imperviousness, I, values per UDFCD Criteria Manual Volume 1, Table 6-3 2. Runoff Coefficient values are from the City of Fort Collins Runoff Coefficient Tables 3.2-2 and 3.2-3; Chapter 5, Section 3.2 of the Fort Collins Stormwater Criteria Manual, 2018 Edition. Frequency adjustment factor has been applied to composite C values per Table 3.2-3. BASIN SUBTOTAL On-Site Basins Flowing On-site RUNOFF COEFFICIENTS - IMPERVIOUS CALCULATION On-Site Basins Flowing Off-site BASIN SUBTOTAL On-Site Roadway Basins Flowing to Underground Chamber System K:\NCO_Civil\096315014_Kentro Drake-College\Project Files\Eng\Drainage\PR CIA Calcs_Drake & College.xlsx Drake and College Mixed Use DATE:4/7/2025 96315014 BAW AGR FINAL Tc DESIGN AREA C2 LENGTH SLOPE Ti LENGTH SLOPE R VEL Tt COMP. TOTAL TOTAL TOTAL Tc BASIN Ac Ft %Min.Ft.%fps Min.tc LENGTH SLOPE IMP.Min.Min. 1A 0.98 0.85 0.0 0.195 0.0 0.0 0.0 0 #DIV/0!80%10.0 5.0 2B 0.55 0.85 0.0 0.195 0.0 0.0 0.0 0 #DIV/0!80%10.0 5.0 3A 1.25 0.85 0.0 0.195 0.0 0.0 0.0 0 #DIV/0!80%10.0 5.0 4A 1.99 0.85 0.0 0.195 0.0 0.0 0.0 0 #DIV/0!80%10.0 5.0 R1 0.52 0.89 60 2.0%2.4 200 0.6%0.195 3.0 1.1 3.5 260 0.9%91%11.4 5.0 R2 0.18 0.83 60 2.0%3.1 200 0.6%0.195 3.0 1.1 4.2 260 0.9%82%11.4 5.0 1B 0.16 0.85 0.0 0.195 0.0 0.0 0.0 0 #DIV/0!80%10.0 5.0 3B 0.17 0.85 0.0 0.195 0.0 0.0 0.0 0 #DIV/0!80%10.0 5.0 4B 0.15 0.85 0.0 0.195 0.0 0.0 0.0 0 #DIV/0!80%10.0 5.0 OS1 0.06 0.69 75 2.0%5.2 15 0.6%0.195 3.0 0.1 5.3 90 1.8%95%10.5 5.3 OS2 0.04 0.73 40 2.0%3.4 55 3.5%0.195 7.2 0.1 3.6 95 2.9%72%10.5 5.0 OS3 0.08 0.55 40 2.0%5.2 55 3.5%0.195 7.2 0.1 5.3 95 2.9%82%10.5 5.3 OS4 0.13 0.20 40 2.0%8.4 55 3.5%0.195 7.2 0.1 8.6 95 2.9%2%10.5 8.6 R1 & R2 0.69 0.68 35 2.0% 3.6 100 0.6% 0.195 3.0 0.6 4.2 135 1.0% 89% 10.8 5.0 On-Site Roadway Basins Flowing to Underground Chamber System On-Site Basins Flowing Off-Site CHECKED BY: On-Site Basins 2-Year Time of Concentration Tc CHECK (URBANIZED BASINS) PROJECT NAME: PROJECT NUMBER: DATA INITIAL TIME (Ti) TRAVEL TIME (Tt) SUB-BASIN CALCULATED BY: K:\NCO_Civil\096315014_Kentro Drake-College\Project Files\Eng\Drainage\PR CIA Calcs_Drake & College.xlsx Drake and College Mixed Use DATE:4/7/2025 96315014 BAW AGR FINAL Tc DESIGN AREA C100 LENGTH SLOPE Ti LENGTH SLOPE R VEL Tt COMP. TOTAL TOTAL TOTAL Tc BASIN Ac Ft %Min.Ft.%fps Min.tc LENGTH SLOPE IMP.Min.Min. 1A 0.98 1.00 0 0 0.0 0 0 0.195 0.0 0.0 0.0 0 #DIV/0! 80% 10.0 5.0 2B 0.55 1.00 0 0 0.0 0 0 0.195 0.0 0.0 0.0 0 #DIV/0! 80% 10.0 5.0 3A 1.25 1.00 0 0 0.0 0 0 0.195 0.0 0.0 0.0 0 #DIV/0! 80% 10.0 5.0 4A 1.99 1.00 0 0 0.0 0 0 0.195 0.0 0.0 0.0 0 #DIV/0! 80% 10.0 5.0 R1 0.52 0.96 60 0 1.6 200 0 0.195 3.0 1.1 2.7 260 0.9% 91% 11.4 5.0 R2 0.18 0.92 60 0 2.1 200 0 0.195 3.0 1.1 3.2 260 0.9% 82% 11.4 5.0 1B 0.16 1.00 0 0.0%0.0 0 0.0%0.195 0.0 0.0 0.0 0 #DIV/0!80%10.0 5.0 3B 0.17 1.00 0 0.0%0.0 0 0.0%0.195 0.0 0.0 0.0 0 #DIV/0!80%10.0 5.0 4B 0.15 1.00 0 0.0%0.0 0 0.0%0.195 0.0 0.0 0.0 0 #DIV/0!95%10.0 5.0 OS1 0.06 0.91 75 2.0%2.4 15 0.6%0.195 3.0 0.1 2.5 90 1.8%0%10.5 5.0 OS2 0.04 0.98 40 2.0%1.1 55 3.5%0.195 7.2 0.1 1.3 95 2.9%82%10.5 5.0 OS3 0.08 0.73 40 2.0%3.5 55 3.5%0.195 7.2 0.1 3.6 95 2.9%2%10.5 5.0 OS4 0.13 0.31 40 2.0%7.4 55 3.5%0.195 7.2 0.1 7.5 95 2.9%0%10.5 7.5 R1 & R2 0.69 0.90 35 2.0% 1.7 100 0.6% 0.195 3.0 0.6 2.3 135 1.0% 79% 10.8 5.0 On-Site Basins Flowing Off-Site On-Site Roadway Basins Flowing to Underground Chamber System On-Site Basins CHECKED BY: SUB-BASIN INITIAL TRAVEL TIME Tc CHECK DATA TIME (Ti) (Tt) (URBANIZED BASINS) 100-Year Time of Concentration PROJECT NAME: PROJECT NUMBER: CALCULATED BY: K:\NCO_Civil\096315014_Kentro Drake-College\Project Files\Eng\Drainage\PR CIA Calcs_Drake & College.xlsx DATE: 4/7/2025 Drake and College Mixed Use 96315014 BAW P1 (1-Hour Rainfall) =0.82 AGR REMARKS DE S I G N PO I N T AR E A (A C ) RU N O F F CO E F F tc (m i n ) C* A ( a c ) I (i n / h r ) Q (c f s ) 1A 0.98 0.85 5.00 0.83 2.85 2.38 Future Lot 1 drainage flows to connect via storm sewer at Design point 1A 2B 0.55 0.85 5.00 0.47 2.85 1.34 Future Lot 2 drainage flows to connect via storm sewer at Design point 2A 3A 1.25 0.85 5.00 1.06 2.85 3.02 Future Lot 3 drainage flows to connect via storm sewer at Design point 3A 4A 1.99 0.85 5.00 1.69 2.85 4.83 Future Lot 4 drainage flows to connect via storm sewer at Design point 4A R1 0.52 0.89 5.00 0.46 2.85 1.31 Flows to proposed inlet within roadway to underground storm system at R1 R2 0.18 0.83 5.00 0.15 2.85 0.42 Flows to proposed inlet within roadway to underground storm system at R2 1B 0.16 0.85 5.00 0.13 2.85 0.38 Future Lot 1 drainage flows off-site towards W. Drake Road at Design point 1B 3B 0.17 0.85 5.00 0.15 2.85 0.42 Future Lot 3 drainage flows off-site towards W. Drake Road at Design point 3B 4B 0.15 0.85 5.00 0.13 2.85 0.37 Future Lot 4 drainage flows off-site towards W. Thunderbird Drive at Design point 4B OS1 0.06 0.69 5.30 0.04 2.85 0.13 Flows North to W. Drake Street OS2 0.04 0.73 5.00 0.03 2.85 0.08 Flows South to W. Thunderbird Rd OS3 0.08 0.55 5.28 0.04 2.85 0.12 Flows East within roadway to S College Avenue OS4 0.13 0.20 8.58 0.03 2.40 0.06 Flows East along landscaping to S College Avenue R1 & R2 0.69 0.68 5.00 0.47 2.85 1.35 Flows to Underground Chamber System OS2 OS4 3B 4B On-Site Basins On-Site Roadway Basins Flowing to Underground Chamber System OS3 1A 2B R2 3A 4A R1 1B R1 & R2 On-Site Basins Flowing Off-Site OS1 DE S G I N BA S I N STORM DRAINAGE DESIGN - RATIONAL METHOD 2 YEAR EVENT PROJECT NAME: PROJECT NUMBER: CALCULATED BY: CHECKED BY: K:\NCO_Civil\096315014_Kentro Drake-College\Project Files\Eng\Drainage\PR CIA Calcs_Drake & College.xlsx DATE: 4/7/2025 Drake and College Mixed Use 96315014 BAW P1 (1-Hour Rainfall) =2.86 AGR REMARKS DE S I G N PO I N T AR E A (A C ) RU N O F F CO E F F tc (m i n ) C* A ( a c ) I (i n / h r ) Q (c f s ) 1A 0.98 1.00 5.00 0.98 9.95 9.76 Future Lot 1 drainage flows to connect via storm sewer at Design point 1A 2B 0.55 1.00 5.00 0.55 9.95 5.51 Future Lot 2 drainage flows to connect via storm sewer at Design point 2A 3A 1.25 1.00 5.00 1.25 9.95 12.41 Future Lot 3 drainage flows to connect via storm sewer at Design point 3A 4A 1.99 1.00 5.00 1.99 9.95 19.82 Future Lot 4 drainage flows to connect via storm sewer at Design point 4A R1 0.52 0.96 5.00 0.49 9.95 4.92 Flows to proposed inlet within roadway to underground storm system at R1 R2 0.18 0.92 5.00 0.16 9.95 1.61 Flows to proposed inlet within roadway to underground storm system at R2 1B 0.16 1.00 5.00 0.16 9.95 1.58 Future Lot 1 drainage flows off-site towards W. Drake Road at Design point 1B 3B 0.17 1.00 5.00 0.17 9.95 1.73 Future Lot 3 drainage flows off-site towards W. Drake Road at Design point 3B 4B 0.15 1.00 5.00 0.15 9.95 1.52 Future Lot 4 drainage flows off-site towards W. Thunderbird Drive at Design point 4B OS1 0.06 0.91 5.30 0.06 9.95 0.58 Flows North to W. Drake Street OS2 0.04 0.98 5.00 0.04 9.95 0.39 Flows South to W. Thunderbird Rd OS3 0.08 0.73 5.28 0.06 9.95 0.57 Flows East within roadway to S College Avenue OS4 0.13 0.31 8.58 0.04 8.38 0.34 Flows East along landscaping to S College Avenue R1 & R2 0.69 0.90 5.00 0.63 9.95 6.23 Flows to Underground Chamber System 4B 3B OS2 OS4 R1 & R2 On-Site Roadway Basins Flowing to Underground Chamber System CHECKED BY: 2B 3A 1B CALCULATED BY: STORM DRAINAGE DESIGN - RATIONAL METHOD 100 YEAR EVENT PROJECT NAME: PROJECT NUMBER: OS3 On-Site Basins Flowing Off-Site OS1 DE S I G N BA S I N On-Site Basins 1A 4A R1 R2 K:\NCO_Civil\096315014_Kentro Drake-College\Project Files\Eng\Drainage\PR CIA Calcs_Drake & College.xlsx PROJECT NAME: Drake and College Mixed Use DATE: 4/7/2025 PROJECT NUMBER: 96315014 CALCULATED BY: BAW CHECKED BY: AGR IMPERVIOUSNESS % Q2 Q100 1A 1A 0.98 80%2.38 9.76 2B 2B 0.55 80%1.34 5.51 3A 3A 1.25 80%3.02 12.41 4A 4A 1.99 80%4.83 19.82 R1 R1 0.52 91%1.31 4.92 R2 R2 0.18 82% 0.42 1.61 5.47 81%13.29 54.03 1B 1B 0.16 80% 0.38 1.58 3B 3B 0.17 80% 0.42 1.73 4B 4B 0.15 80% 0.37 1.52 OS1 OS1 0.06 95% 0.13 0.58 OS2 OS2 0.04 72% 0.08 0.39 OS3 OS3 0.08 82% 0.12 0.57 OS4 OS4 0.13 2% 0.06 0.34 0.80 68%1.57 6.71 R1 & R2 R1 & R2 0.69 89% 1.35 6.23 On-Site Roadway Basins Flowing to Underground Chamber System On-Site Basins Flowing On-Site DESIGN POINT On-Site Basins Flowing Off-Site TOTAL RATIONAL CALCULATIONS SUMMARY TRIBUTARY BASINS TRIBUTARY AREA (AC) PEAK FLOWS (CFS) TOTAL K:\NCO_Civil\096315014_Kentro Drake-College\Project Files\Eng\Drainage\PR CIA Calcs_Drake & College.xlsx PROJECT NAME: Drake & College Mixed-Use DATE: 4/7/2025 PROJECT NUMBER: 96315014 CALCULATED BY: BAW CHECKED BY: AGR Total Site Area: 6.27 acres Road Improvement Area to LID (Sub-basin R1 & R2):0.69 acres 0.8 Imperviousness 89% 0.314 Total Site Impervious Area: 0.49 acres 947.7 CF Added/Modified Impervious Area: 0.49 acres 972 CFTotal WQCV Provided a: (12 hours draintime) PROJECT INFORMATION WQCV Calculations WQCV Total WQCV Req. (CF) Fort Collins Duration (min.) Intensity WQ (in/hr) Intensity 2-year (in/hr) Intensity 10-year (in/hr) Intensity 100-year (in/hr) 5 1.43 2.85 4.87 9.95 6 1.34 2.67 4.56 9.31 7 1.26 2.52 4.31 8.80 8 1.20 2.40 4.10 8.38 9 1.15 2.30 3.93 8.03 10 1.11 2.21 3.78 7.72 11 1.07 2.13 3.63 7.42 12 1.03 2.05 3.50 7.16 13 0.99 1.98 3.39 6.92 14 0.96 1.92 3.29 6.71 15 0.94 1.87 3.19 6.52 16 0.91 1.81 3.08 6.30 17 0.88 1.75 2.99 6.10 18 0.85 1.70 2.90 5.92 19 0.83 1.65 2.82 5.75 20 0.81 1.61 2.74 5.60 21 0.78 1.56 2.67 5.46 22 0.77 1.53 2.61 5.32 23 0.75 1.49 2.55 5.20 24 0.73 1.46 2.49 5.09 25 0.72 1.43 2.44 4.98 26 0.70 1.40 2.39 4.87 27 0.69 1.37 2.34 4.78 28 0.67 1.34 2.29 4.69 29 0.66 1.32 2.25 4.60 30 0.65 1.30 2.21 4.52 31 0.64 1.27 2.16 4.42 32 0.62 1.24 2.12 4.33 33 0.61 1.22 2.08 4.24 34 0.60 1.19 2.04 4.16 35 0.59 1.17 2.00 4.08 36 0.58 1.15 1.96 4.01 37 0.58 1.16 1.93 3.93 38 0.56 1.11 1.89 3.87 39 0.55 1.09 1.86 3.80 40 0.54 1.07 1.83 3.74 41 0.53 1.05 1.80 3.68 42 0.52 1.04 1.77 3.62 43 0.51 1.02 1.74 6.56 44 0.51 1.01 1.72 3.51 45 0.50 0.99 1.69 3.46 46 0.49 0.98 1.67 3.41 47 0.48 0.96 1.64 3.36 48 0.48 0.95 1.62 3.31 49 0.47 0.94 1.60 3.27 50 0.46 0.92 1.58 3.23 51 0.46 0.91 1.56 3.18 52 0.45 0.90 1.54 3.14 53 0.45 0.89 1.52 3.10 54 0.44 0.88 1.50 3.07 55 0.44 0.87 1.48 3.06 56 0.43 0.86 1.47 2.99 57 0.43 0.85 1.45 2.96 58 0.42 0.84 1.43 2.92 59 0.42 0.83 1.42 2.89 60 0.41 0.82 1.40 2.86 65 0.39 0.78 1.32 2.71 70 0.37 0.73 1.25 2.59 75 0.35 0.70 1.19 2.47 80 0.33 0.66 1.14 2.38 85 0.32 0.64 1.09 2.29 90 0.31 0.61 1.05 2.21 95 0.29 0.58 1.01 2.13 100 0.28 0.56 0.97 2.06 105 0.27 0.54 0.94 2.00 110 0.26 0.52 0.91 1.94 115 0.26 0.51 0.88 1.88 120 0.25 0.49 0.86 1.84 IDF Table for Rational Method (FCSCM Table 3.4.1) Chamber ID Total Required WQ Volume (cf)a WQ Inflowb (cfs) Chamber Type Chamber Unit Release Ratec (cfs) Chamber Unit Volumed (cf) Installed Chamber Unit Volume, inc. Aggregatee (cf) Mimimum No. of Chambers for WQCVf Minimum WQ Release Rateg (cfs) Minimum Required Isolator Row Volume by FAA Methodh (cf) Design Controli No. of Chambers Provided Provided WQ Release Ratej (cfs) Provided Isolator Row Volumek (cf) Total Installed System Volumel (cf) 1 948 0.71 SC-800 0.024 50.60 81.00 12 0.28 297 WQCV 12 0.28 607 972 SC-740 a. Total required WQCV calculated per 12-hr drain time. b. WQ inflow is approximated as one-half the 2-yr peak runoff rate. c. Release rate per chamber, limited by flow through geotextile with accumulated sediment. d. Volume within chamber only, not accounting for void spaces in surrounding aggregate. The Isolator Row(s) are sized per this unit volume. e. Volume includes chamber and void spaces (40%) in surrounding aggregate, per chamber unit. The total system WQCV is sized per this unit volume. f. Number of chambers required to provide full WQCV within total installed system, including aggregate. g. Release rate per chamber times number of chambers. This is used at the 'outlet control' for the FAA calculations. h. Minimum 'chamber-only' volume to ensure dirty water is fully contained within Isolator Row. i. Is design controlled by Isolator Row volume or WQCV. j. Release rate per chamber times number of chambers provided. This is the approximate controlled discharge from the WQ event. k. Volume provided in chambers only (no aggregate storage). This number must meet or exceed the required FAA storage volume. l. System volume includes total number of chambers, plus surrounding aggregate. This number must meet or exceed the required 12-hr WQCV. Chamber Configuration Summary Project Number: Project Location: Calcs By: Design Point:1 Design Storm: WQ Isolator Volume 297 ft3 Developed "C":0.99 Area (A):0.69 acres Max. Release (QOUT):0.31 cfs Time Time WQ Intensity QWQ Inflow (Runoff) Volume Outflow (Release) Volume Storage Detention Volume (Minutes) (Seconds) (in/hr) (cfs)(ft3)(ft3)(ft3) 5 300 1.43 0.98 293 93 200 10 600 1.11 0.76 454 186 268 15 900 0.94 0.64 576 279 297 20 1200 0.81 0.55 662 372 290 25 1500 0.72 0.49 734 465 269 30 1800 0.65 0.45 801 558 243 35 2100 0.59 0.40 841 651 190 40 2400 0.54 0.37 879 744 135 45 2700 0.50 0.34 915 837 78 50 3000 0.46 0.32 945 930 15 55 3300 0.44 0.30 983 1023 -40 60 3600 0.41 0.28 1011 1116 -105 65 3900 0.39 0.27 1042 1209 -167 70 4200 0.37 0.25 1050 1302 -252 75 4500 0.35 0.24 1079 1395 -316 80 4800 0.33 0.23 1085 1488 -403 85 5100 0.32 0.22 1118 1581 -463 90 5400 0.31 0.21 1128 1674 -546 95 5700 0.29 0.20 1132 1767 -635 100 6000 0.28 0.19 1151 1860 -709 105 6300 0.27 0.18 1165 1953 -788 110 6600 0.26 0.18 1175 2046 -871 115 6900 0.26 0.17 1205 2139 -934 120 7200 0.25 0.17 1208 2232 -1024 Isolator Row Volume Calculation (FAA Method) Chamber 1 Inputs Results Drake-College 96315014 College and Drake BAW ELEC T ELECT ELEC G H2O ELEC G CS C.O. H2O CS G ELEC G AC S H2O ELECT X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X E E E E E E E E E E E E E E E E W W W W W W W W E E E E E E E E E E E E E EEE E E E E E E E T T T T T T T T T T W OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU X S EEEE EEEE E E E E E E E E E E E E E E E E E E E E E E EEEE VAULT ELEC E ELEC G G G G G G G G G G G G G G G G G G W W W W W W W D D D D D 50 3 0 50 2 7 50 2 8 50 2 9 5026 502 7 5027 50 2 7 5027 5028 5028 50 2 5 50 2 2 50 2 3 50 2 4 502 7 50 2 8 50 2 9 502 9 5029 50 2 8 5028 5028 5028 50 2 5 50 2 4 5026 5025 5026 5027 50 2 9 50 2 9 50 3 0 PROPOSED ROW PROPOSED ROW PROPOSED ROW PROPOSED ROW DRAKE ROAD (ROW VARIES) CO L L E G E A V E N U E (R O W V A R I E S ) THUNDERBIRD DRIVE (60' ROW) TH I S D O C U M E N T , T O G E T H E R W I T H T H E C O N C E P T S A N D D E S I G N S P R E S E N T E D H E R E I N , A S A N I N S T R U M E N T O F S E R V I C E , I S I N T E N D E D O N L Y F O R T H E S P E C I F I C P U R P O S E A N D C L I E N T F O R W H I C H I T W A S P R E P A R E D . R E U S E O F A N D I M P R O P E R R E L I A N C E O N T H I S D O C U M E N T W I T H O U T W R I T T E N A U T H O R I Z A T I O N A N D A D A P T A T I O N B Y K I M L E Y - H O R N A N D A S S O C I A T E S , I N C . S H A L L B E W I T H O U T L I A B I L I T Y T O K I M L E Y - H O R N A N D A S S O C I A T E S , I N C . R Know what's below. Call before you dig. DESIGNED BY: DRAWN BY: CHECKED BY: DATE: NO . RE V I S I O N BY DA T E © 2 0 2 4 K I M L E Y - H O R N A N D A S S O C I A T E S , I N C . 33 2 5 S O U T H T I M B E R L I N E R O A D , S U I T E 1 3 0 FO R T C O L L I N S , C O L O R A D O 8 0 5 2 5 ( 9 7 0 ) 8 2 2 - 7 9 1 1 K: \ N C O _ C i v i l \ 0 9 6 3 1 5 0 1 4 _ K e n t r o D r a k e - C o l l e g e \ C A D D \ P l a n S h e e t s \ 0 9 6 3 1 5 0 1 4 _ V - D R N G . d w g PROJECT NO. SHEET KE N T R O - D R A K E & C O L L E G E 12/4/24 BAW MKL AGR 096315014 FOR REVIEW ONLY NOT FOR Kimley-Horn and Associates, Inc. CONSTRUCTION PROPERTY LINE LEGEND: NORTH X 12 " W 12 " W 12 " W 12 " W 12 " W 12 " W 12 " W 12 " W 12 " W 12 " W 12 " W 12 " W 12 " W 12 " W D D D D D 50 2 5 50 2 5 50 3 0 50 3 0 50 2 3 50 2 3 50 2 4 50 2 4 50 2 6 50 2 6 50 2 6 50 2 6 50 2 6 50 2 6 502 7 50 2 7 5028 50 2 8 5029 50 2 9 50 3 1 50 3 1 50 3 0 5027 5028 50 2 9 50 3 1 50 3 1 5025 50 3 0 50 2 7 50 2 8 50 2 9 5026 5027 5027 5028 5028 50 2 5 50 2 2 50 2 3 50 2 4 502 7 50 2 8 50 2 9 502 9 5028 5028 5028 50 2 5 50 2 4 5026 5025 5026 5027 50 2 9 50 2 9 50 3 0 503 0 502750 2 8 50 2 9 50 2 3 50 2 3 50 2 4 50 2 2 5025 503 0 50 2 3 50 2 4 5026 502 7 502 8 502 9 50 3 1 DRAKE ROAD CO L L E G E A V E N U E THUNDERBIRD DRIVE PROPOSED STORM LINEPROPOSED ADS SC-800 STORM TECH OR APPROVED EQUAL PROPOSED RIGHT-OF-WAY PROPOSED RIGHT-OF-WAY PROPOSED RIGHT-OF-WAY EXISTING RIGHT-OF-WAY EXISTING RIGHT-OF-WAY EXISTING RIGHT-OF-WAY PROPOSED RIGHT-OF-WAY MC C L E L L A N D D R I V E EXISTING STORM INLETS STRM INLET B1 SINGLE COMBO INLET STRM INLET A3-2 SINGLE COMBO INLET STRM INLET A TRIPLE COMBO INLET STORM DRAIN A SEE SHEET C4.8 STORM DRAIN B SEE SHEET C4.9 EX . 1 5 " C M P S T O R M EX . 1 5 " R C P S T O R M EX . 1 5 " R C P S T O R M EX . 1 5 " R C P S T O R M EX . 2 2 " R C P S T O R M 12' FUTURE SIDEWALK TH I S D O C U M E N T , T O G E T H E R W I T H T H E C O N C E P T S A N D D E S I G N S P R E S E N T E D H E R E I N , A S A N I N S T R U M E N T O F S E R V I C E , I S I N T E N D E D O N L Y F O R T H E S P E C I F I C P U R P O S E A N D C L I E N T F O R W H I C H I T W A S P R E P A R E D . R E U S E O F A N D I M P R O P E R R E L I A N C E O N T H I S D O C U M E N T W I T H O U T W R I T T E N A U T H O R I Z A T I O N A N D A D A P T A T I O N B Y K I M L E Y - H O R N A N D A S S O C I A T E S , I N C . S H A L L B E W I T H O U T L I A B I L I T Y T O K I M L E Y - H O R N A N D A S S O C I A T E S , I N C . R Know what's below. Call before you dig. DESIGNED BY: DRAWN BY: CHECKED BY: DATE: NO . RE V I S I O N BY DA T E © 2 0 2 4 K I M L E Y - H O R N A N D A S S O C I A T E S , I N C . 33 2 5 S O U T H T I M B E R L I N E R O A D , S U I T E 1 3 0 FO R T C O L L I N S , C O L O R A D O 8 0 5 2 5 ( 9 7 0 ) 8 2 2 - 7 9 1 1 K: \ N C O _ C i v i l \ 0 9 6 3 1 5 0 1 4 _ K e n t r o D r a k e - C o l l e g e \ C A D D \ P l a n S h e e t s \ 0 9 6 3 1 5 0 1 4 _ C - D R N G . d w g PROJECT NO. SHEET SW C D R A K E / C O L L E G E 2/19/2025 BAW MKL AGR 096315014 FOR REVIEW ONLY NOT FOR Kimley-Horn and Associates, Inc. CONSTRUCTION PROPERTY LINE LEGEND: PROPOSED CATCH CURB AND GUTTER PROPOSED STORM LINE C7.0 DR A I N A G E E X H I B I T 34 OF 34 # = BASIN DESIGNATION AC = AREA IN ACRES I = % IMPERVIOUSNESS # = DESIGN POINT PROPOSED BASIN BOUNDARY PROPOSED FLOW ARROW EXISTING FLOW ARROW NORTH W W W SS S S IR W W W SS S S IR F.O. ELEC C F.O. ELEC T S VAULTCABLE ELEC ELEC VAULTF.O.ELEC VAULT F.O. ELEC VAULT F.O. VAULT F.O. TRAFFICVAULT T S OHU OHU OHU OHU OHU OHU OHU CSCS HYD ELEC H2O S S C S S S S VAULTELEC H2O HYD 12 " W 12 " W 12 " W 12 " W 12 " W CTV CTV CTV CTV CTV D D D D D S 50 2 5 50 2 5 50 3 0 50 3 0 50 2 3 50 2 3 50 2 4 50 2 4 50 2 6 50 2 6 50 2 6 50 2 6 50 2 6 50 2 6 502 7 50 2 7 5028 50 2 8 5029 50 2 9 50 3 1 50 3 1 50 3 0 5027 5028 50 2 9 50 3 1 50 3 1 5025 50 3 0 50 2 7 50 2 8 50 2 9 5026 5027 5027 5028 5028 50 2 5 50 2 2 50 2 3 50 2 4 502 7 50 2 8 50 2 9 502 9 5028 5028 5028 50 2 5 50 2 4 5026 5025 5026 5027 50 2 9 50 2 9 50 3 0 503 0 502750 2 8 50 2 9 50 2 3 50 2 3 50 2 3 50 2 3 50 2 3 50 2 4 50 2 3 50 2 4 50 2 2 5025 503 0 50 2 3 50 2 4 5026 502 7 502 8502 9 5031 50 3 1 50 3 1 WEST DRAKE ROAD Mc C L E L L A N D D R I V E THUNDERBIRD DRIVE CO L L E G E A V E N U E UNDERGROUND SYSTEM 1 TREATMENT AREA: 0.49 AC REQUIRED VOLUME: 948 CF PROVIDED VOLUME: 972 CF 12' FUTURE SIDEWALK © 2024 KIMLEY-HORN AND ASSOCIATES, INC. 3325 S. TIMBERLINE RD, SUITE 130, FORT COLLINS, CO, 80525 PHONE: (970) 822-7911 K:\NCO_CIVIL\096315014_KENTRO DRAKE-COLLEGE\CADD\EXHIBITS\DRAKE & COLLEGE_LID EXHIBIT.DWG PROJECT NUMBER:DATE: LID EXHIBIT SWC COLLEGE/DRAKE 096315014A 7, 2025 NORTH LEGEND PROPERTY LINE RIGHT-OF-WAY LINE EASEMENT LINE EXISTING MAJOR CONTOUR EXISTING MINOR CONTOUR CENTERLINE UNDERGROUND CHAMBER TREATMENT AREA (CURRENT IMPROVEMENTS) UNDERGROUND CHAMBER SYSTEM AREA TO BE TREATED BY INDIVIDUAL LOT UNTREATED AREA PROPOSED MAJOR CONTOUR PROPOSED MINOR CONTOUR UNDERGROUND CHAMBER TREATMENT AREA (FUTURE IMPROVEMENTS) UNTREATED AREA (ASSUMED 80% IMPERVIOUS) PROJECT LID SUMMARY TOTAL IMPERVIOUS AREA FOR IMPROVEMENTS 33,381 SF MINIMUM AREA TO BE TREATED BY LID MEASURES TOTAL REQUIRED TREATED IMPERVIOUS AREAS BY UNDERGROUND SYSTEM 25,036 SF 75.0% TOTAL PROPOSED TREATED IMPERVIOUS AREAS BY UNDERGROUND SYSTEM 26,717 SF 80.0% ELEC T ELECT ELEC G H2O ELEC G CS C.O. H2O CS G ELEC G AC S H2O ELECT X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X E E E E E E E E E E E E E E E E W W W W W W W W E E E E E E E E E E E E E EEE E E E E E E E T T T T T T T T T T W OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU X S E E E E E E E E E E E E E E E E E E E E E E EEEE VAULT ELEC E ELEC G G G G G G G G G G G G G G G G G G W W W W W W W D D D D D 50 3 0 50 2 7 50 2 8 50 2 9 5026 5027 50 2 7 5027 502 8 5028 50 2 5 50 2 2 50 2 3 50 2 4 502 7 502 8 50 2 9 502 9 5029 50 2 8 5028 5028 5028 50 2 5 50 2 4 5026 5025 5026 5027 50 2 9 50 2 9 50 3 0 DRAKE ROAD CO L L E G E A V E N U E THUNDERBIRD DRIVE TH I S D O C U M E N T , T O G E T H E R W I T H T H E C O N C E P T S A N D D E S I G N S P R E S E N T E D H E R E I N , A S A N I N S T R U M E N T O F S E R V I C E , I S I N T E N D E D O N L Y F O R T H E S P E C I F I C P U R P O S E A N D C L I E N T F O R W H I C H I T W A S P R E P A R E D . R E U S E O F A N D I M P R O P E R R E L I A N C E O N T H I S D O C U M E N T W I T H O U T W R I T T E N A U T H O R I Z A T I O N A N D A D A P T A T I O N B Y K I M L E Y - H O R N A N D A S S O C I A T E S , I N C . S H A L L B E W I T H O U T L I A B I L I T Y T O K I M L E Y - H O R N A N D A S S O C I A T E S , I N C . R Know what's below. Call before you dig. DESIGNED BY: DRAWN BY: CHECKED BY: DATE: NO . RE V I S I O N BY DA T E © 2 0 2 4 K I M L E Y - H O R N A N D A S S O C I A T E S , I N C . 33 2 5 S O U T H T I M B E R L I N E R O A D , S U I T E 1 3 0 FO R T C O L L I N S , C O L O R A D O 8 0 5 2 5 ( 9 7 0 ) 8 2 2 - 7 9 1 1 K: \ N C O _ C i v i l \ 0 9 6 3 1 5 0 1 4 _ K e n t r o D r a k e - C o l l e g e \ C A D D \ E x h i b i t s \ 2 0 2 4 - 1 1 2 7 D r a i n a g e E x h i b i t s \ 0 9 6 3 1 5 0 1 4 _ E X I m p e r v i o u s . d w g PROJECT NO. SHEET KE N T R O - D R A K E & C O L L E G E 12/4/24 BAW MKL AGR 096315014 FOR REVIEW ONLY NOT FOR Kimley-Horn and Associates, Inc. CONSTRUCTION EX-C EX I S T I N G I M P E R V I O U S E X H I B I T 1 OF 1 NORTH PROPERTY LINE LEGEND: EASEMENT LINE PERVIOUS AREA IMPERVIOUS AREA IMPERVIOUS AREA SUMMARY CALCULATIONS PROJECT AREA 6.27 AC EXISTING IMPERVIOUS AREA 6.18 AC PROPOSED IMPERVIOUS AREA 4.84 AC REDUCTION IN IMPERVIOUS AREA 1.34 AC 50 2 5 50 2 5 50 3 0 50 3 0 50 2 3 50 2 3 50 2 4 50 2 4 50 2 6 50 2 6 50 2 6 50 2 6 50 2 6 50 2 6 502 7 50 2 7 5028 50 2 8 5029 50 2 9 50 3 1 50 3 1 50 3 0 5027 5028 50 2 9 50 3 1 50 3 1 5025 LOT 3 LOT 1 LOT 2 LOT 4 ELEC X OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU OHU CT V 12 " W 12 " W 12 " W 12 " W 12 " W 12 " W 12 " W 12 " W 12 " W 12 " W 12 " W 12 " W 12 " W 12 " W CT V CTV CTV CTV CTV CTV CTV CTV CTV CTV CTV CTV CTV CTV CTV D D D D D 50 3 0 50 2 7 50 2 8 50 2 9 5026 5027 5027 5028 5028 50 2 5 50 2 2 50 2 3 50 2 4 502 7 50 2 8 50 2 9 502 9 5028 5028 5028 50 2 5 50 2 4 5026 5025 5026 5027 50 2 9 50 2 9 50 3 0 503 0 502750 2 8 50 2 9 50 2 3 50 2 3 50 2 4 50 2 2 5025 503 0 50 2 3 50 2 4 5026 502 7 502 8 502 9 50 3 1 DRAKE ROAD CO L L E G E A V E N U E THUNDERBIRD DRIVE 12' FUTURE SIDEWALK TH I S D O C U M E N T , T O G E T H E R W I T H T H E C O N C E P T S A N D D E S I G N S P R E S E N T E D H E R E I N , A S A N I N S T R U M E N T O F S E R V I C E , I S I N T E N D E D O N L Y F O R T H E S P E C I F I C P U R P O S E A N D C L I E N T F O R W H I C H I T W A S P R E P A R E D . R E U S E O F A N D I M P R O P E R R E L I A N C E O N T H I S D O C U M E N T W I T H O U T W R I T T E N A U T H O R I Z A T I O N A N D A D A P T A T I O N B Y K I M L E Y - H O R N A N D A S S O C I A T E S , I N C . S H A L L B E W I T H O U T L I A B I L I T Y T O K I M L E Y - H O R N A N D A S S O C I A T E S , I N C . R Know what's below. Call before you dig. DESIGNED BY: DRAWN BY: CHECKED BY: DATE: NO . RE V I S I O N BY DA T E © 2 0 2 4 K I M L E Y - H O R N A N D A S S O C I A T E S , I N C . 33 2 5 S O U T H T I M B E R L I N E R O A D , S U I T E 1 3 0 FO R T C O L L I N S , C O L O R A D O 8 0 5 2 5 ( 9 7 0 ) 8 2 2 - 7 9 1 1 K: \ N C O _ C i v i l \ 0 9 6 3 1 5 0 1 4 _ K e n t r o D r a k e - C o l l e g e \ C A D D \ E x h i b i t s \ 2 0 2 4 - 1 1 2 7 D r a i n a g e E x h i b i t s \ 0 9 6 3 1 5 0 1 4 _ P r o p o s e d I m p e r v i o u s . d w g PROJECT NO. SHEET SW C D R A K E / C O L L E G E 2/19/2025 BAW MKL AGR 096315014 FOR REVIEW ONLY NOT FOR Kimley-Horn and Associates, Inc. CONSTRUCTION PROPERTY LINE LEGEND: EX-D PR O P O S E D I M P E R V I O U S E X H I B I T 1 OF 1 NORTH EASEMENT LINE PROPOSED CURB AND GUTTER PERVIOUS AREA IMPERVIOUS AREA PROPOSED IMPERVIOUS AREA (ASSUMES 80% IMPERVIOUSNESS) IMPERVIOUS AREA SUMMARY CALCULATIONS PROJECT AREA 6.27 AC EXISTING IMPERVIOUS AREA 6.18 AC PROPOSED IMPERVIOUS AREA 4.84 AC REDUCTION IN IMPERVIOUS AREA 1.34 AC Final Drainage Report Drake and College Mixed-Use – Fort Collins, Colorado Appendix C – Hydraulic Calculations (to be included with next submittal) MHFD-Inlet, Version 5.03 (August 2023) Worksheet Protected INLET NAME Inlet A3-2 (R1)Inlet B1 (R2)User-Defined Site Type (Urban or Rural)URBAN URBAN Inlet Application (Street or Area)STREET STREET Hydraulic Condition In Sump In Sump Inlet Type CDOT/Denver 13 Combination CDOT/Denver 13 Combination USER-DEFINED INPUT User-Defined Design Flows Minor QKnown (cfs)1.3 0.4 Major QKnown (cfs)4.9 1.6 Bypass (Carry-Over) Flow from Upstream Inlets must be organized from upstream (left) to downstream (right) in order for bypass flows to be linked. Receive Bypass Flow from:No Bypass Flow Received No Bypass Flow Received Minor Bypass Flow Received, Qb (cfs)0.0 0.0 Major Bypass Flow Received, Qb (cfs)0.0 0.0 Watershed Characteristics Subcatchment Area (acres) Percent Impervious NRCS Soil Type Watershed Profile Overland Slope (ft/ft) Overland Length (ft) Channel Slope (ft/ft) Channel Length (ft) Minor Storm Rainfall Input Design Storm Return Period, Tr (years) One-Hour Precipitation, P1 (inches) Major Storm Rainfall Input Design Storm Return Period, Tr (years) One-Hour Precipitation, P1 (inches) CALCULATED OUTPUT Minor Total Design Peak Flow, Q (cfs)1.3 0.4 Major Total Design Peak Flow, Q (cfs)4.9 1.6 Minor Flow Bypassed Downstream, Qb (cfs)N/A N/A Major Flow Bypassed Downstream, Qb (cfs)N/A N/A INLET MANAGEMENT Project: Inlet ID: Gutter Geometry: Maximum Allowable Width for Spread Behind Curb TBACK =2.0 ft Side Slope Behind Curb (leave blank for no conveyance credit behind curb)SBACK =ft/ft Manning's Roughness Behind Curb (typically between 0.012 and 0.020)nBACK =0.012 Height of Curb at Gutter Flow Line HCURB =6.00 inches Distance from Curb Face to Street Crown TCROWN =26.0 ft Gutter Width W =2.00 ft Street Transverse Slope SX =0.020 ft/ft Gutter Cross Slope (typically 2 inches over 24 inches or 0.083 ft/ft)SW =0.083 ft/ft Street Longitudinal Slope - Enter 0 for sump condition SO =0.000 ft/ft Manning's Roughness for Street Section (typically between 0.012 and 0.020)nSTREET =0.013 Minor Storm Major Storm Max. Allowable Spread for Minor & Major Storm TMAX =13.0 13.0 ft Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX =4.9 6.0 inches Check boxes are not applicable in SUMP conditions MINOR STORM Allowable Capacity is not applicable to Sump Condition Minor Storm Major Storm MAJOR STORM Allowable Capacity is not applicable to Sump Condition Qallow =SUMP SUMP cfs MHFD-Inlet, Version 5.03 (August 2023) ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm) (Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread) SWC Drake-College Inlet A3-2 (R1) MHFD-Inlet_v5.03.xlsm, Inlet A3-2 (R1) 4/7/2025, 12:38 PM Design Information (Input)MINOR MAJOR Type of Inlet Type = Local Depression (additional to continuous gutter depression 'a' from above)alocal =2.00 2.00 inches Number of Unit Inlets (Grate or Curb Opening)No =1 1 Water Depth at Flowline (outside of local depression)Ponding Depth =4.9 6.0 inches Grate Information MINOR MAJOR Length of a Unit Grate Lo (G) =3.00 3.00 feet Width of a Unit Grate Wo =1.73 1.73 feet Open Area Ratio for a Grate (typical values 0.15-0.90)Aratio =0.43 0.43 Clogging Factor for a Single Grate (typical value 0.50 - 0.70)Cf (G) =0.50 0.50 Grate Weir Coefficient (typical value 2.15 - 3.60)Cw (G) =3.30 3.30 Grate Orifice Coefficient (typical value 0.60 - 0.80)Co (G) =0.60 0.60 Curb Opening Information MINOR MAJOR Length of a Unit Curb Opening Lo (C) =3.00 3.00 feet Height of Vertical Curb Opening in Inches Hvert =6.50 6.50 inches Height of Curb Orifice Throat in Inches Hthroat =5.25 5.25 inches Angle of Throat Theta =0.00 0.00 degrees Side Width for Depression Pan (typically the gutter width of 2 feet)Wp =2.00 2.00 feet Clogging Factor for a Single Curb Opening (typical value 0.10)Cf (C) =0.10 0.10 Curb Opening Weir Coefficient (typical value 2.3-3.7)Cw (C) =3.70 3.70 Curb Opening Orifice Coefficient (typical value 0.60 - 0.70)Co (C) =0.66 0.66 Low Head Performance Reduction (Calculated)MINOR MAJOR Depth for Grate Midwidth dGrate =0.43 0.52 ft Depth for Curb Opening Weir Equation dCurb =0.24 0.33 ft Grated Inlet Performance Reduction Factor for Long Inlets RFGrate =0.76 0.94 Curb Opening Performance Reduction Factor for Long Inlets RFCurb =N/A N/A Combination Inlet Performance Reduction Factor for Long Inlets RFCombination =0.76 0.94 MINOR MAJOR Total Inlet Interception Capacity (assumes clogged condition)Qa =2.8 5.1 cfs Inlet Capacity IS GOOD for Minor and Major Storms (>Q Peak)Q PEAK REQUIRED =1.3 4.9 cfs CDOT/Denver 13 Combination INLET IN A SUMP OR SAG LOCATION MHFD-Inlet, Version 5.03 (August 2023) H-VertH-Curb W Lo (C) Lo (G) Wo WP CDOT/Denver 13 Combination Override Depths MHFD-Inlet_v5.03.xlsm, Inlet A3-2 (R1) 4/7/2025, 12:38 PM Project: Inlet ID: Gutter Geometry: Maximum Allowable Width for Spread Behind Curb TBACK =2.0 ft Side Slope Behind Curb (leave blank for no conveyance credit behind curb)SBACK =ft/ft Manning's Roughness Behind Curb (typically between 0.012 and 0.020)nBACK =0.012 Height of Curb at Gutter Flow Line HCURB =6.00 inches Distance from Curb Face to Street Crown TCROWN =24.0 ft Gutter Width W =2.00 ft Street Transverse Slope SX =0.020 ft/ft Gutter Cross Slope (typically 2 inches over 24 inches or 0.083 ft/ft)SW =0.083 ft/ft Street Longitudinal Slope - Enter 0 for sump condition SO =0.000 ft/ft Manning's Roughness for Street Section (typically between 0.012 and 0.020)nSTREET =0.013 Minor Storm Major Storm Max. Allowable Spread for Minor & Major Storm TMAX =12.0 12.0 ft Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX =4.6 4.6 inches Check boxes are not applicable in SUMP conditions MINOR STORM Allowable Capacity is not applicable to Sump Condition Minor Storm Major Storm MAJOR STORM Allowable Capacity is not applicable to Sump Condition Qallow =SUMP SUMP cfs MHFD-Inlet, Version 5.03 (August 2023) ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm) (Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread) SWC Drake-College Inlet B1 (R2) MHFD-Inlet_v5.03.xlsm, Inlet B1 (R2) 4/7/2025, 12:38 PM Design Information (Input)MINOR MAJOR Type of Inlet Type = Local Depression (additional to continuous gutter depression 'a' from above)alocal =2.00 2.00 inches Number of Unit Inlets (Grate or Curb Opening)No =1 1 Water Depth at Flowline (outside of local depression)Ponding Depth =4.6 4.6 inches Grate Information MINOR MAJOR Length of a Unit Grate Lo (G) =3.00 3.00 feet Width of a Unit Grate Wo =1.73 1.73 feet Open Area Ratio for a Grate (typical values 0.15-0.90)Aratio =0.43 0.43 Clogging Factor for a Single Grate (typical value 0.50 - 0.70)Cf (G) =0.50 0.50 Grate Weir Coefficient (typical value 2.15 - 3.60)Cw (G) =3.30 3.30 Grate Orifice Coefficient (typical value 0.60 - 0.80)Co (G) =0.60 0.60 Curb Opening Information MINOR MAJOR Length of a Unit Curb Opening Lo (C) =3.00 3.00 feet Height of Vertical Curb Opening in Inches Hvert =6.50 6.50 inches Height of Curb Orifice Throat in Inches Hthroat =5.25 5.25 inches Angle of Throat Theta =0.00 0.00 degrees Side Width for Depression Pan (typically the gutter width of 2 feet)Wp =2.00 2.00 feet Clogging Factor for a Single Curb Opening (typical value 0.10)Cf (C) =0.10 0.10 Curb Opening Weir Coefficient (typical value 2.3-3.7)Cw (C) =3.70 3.70 Curb Opening Orifice Coefficient (typical value 0.60 - 0.70)Co (C) =0.66 0.66 Low Head Performance Reduction (Calculated)MINOR MAJOR Depth for Grate Midwidth dGrate =0.41 0.41 ft Depth for Curb Opening Weir Equation dCurb =0.22 0.22 ft Grated Inlet Performance Reduction Factor for Long Inlets RFGrate =0.72 0.72 Curb Opening Performance Reduction Factor for Long Inlets RFCurb =N/A N/A Combination Inlet Performance Reduction Factor for Long Inlets RFCombination =0.72 0.72 MINOR MAJOR Total Inlet Interception Capacity (assumes clogged condition)Qa =2.3 2.3 cfs Inlet Capacity IS GOOD for Minor and Major Storms (>Q Peak)Q PEAK REQUIRED =0.4 1.6 cfs CDOT/Denver 13 Combination INLET IN A SUMP OR SAG LOCATION MHFD-Inlet, Version 5.03 (August 2023) H-VertH-Curb W Lo (C) Lo (G) Wo WP CDOT/Denver 13 Combination Override Depths MHFD-Inlet_v5.03.xlsm, Inlet B1 (R2) 4/7/2025, 12:38 PM Channel Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Tuesday, Feb 18 2025 <Name> Triangular Side Slopes (z:1) = 8.00, 8.00 Total Depth (ft) = 0.50 Invert Elev (ft) = 100.00 Slope (%) = 1.00 N-Value = 0.025 Calculations Compute by: Known Depth Known Depth (ft) = 0.50 Highlighted Depth (ft) = 0.50 Q (cfs) = 4.691 Area (sqft) = 2.00 Velocity (ft/s) = 2.35 Wetted Perim (ft) = 8.06 Crit Depth, Yc (ft) = 0.47 Top Width (ft) = 8.00 EGL (ft) = 0.59 0 1 2 3 4 5 6 7 8 9 10 Elev (ft) Depth (ft)Section 99.75 -0.25 100.00 0.00 100.25 0.25 100.50 0.50 100.75 0.75 101.00 1.00 Reach (ft)