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Home My WebLink AboutH-25 MULTI-FAMILY - FDP210008 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORT H-25 Multi Family – Fort Collins, CO Final Drainage Report 19059.02 Harmony 25, LLC 144 North Mason Street, Suite 4 Fort Collins, CO, 80524 Submittal Date: 4/7/2021 April 7, 2021 City of Fort Collins Stormwater Utility 700 Wood Street Fort Collins, Colorado 80521 RE: Final Drainage and Erosion Control Report for H-25 MULTI-FAMILY DEVELOPMENT Dear Staff: Sanderson Stewart is pleased to submit this Final Drainage and Erosion Control Report for your review. This report accompanies the Project Development Plan submittal for the proposed H-25 Multi-Family development. This report has been prepared in accordance to Fort Collins Stormwater Criteria Manual (FCSCM) and serves to document the stormwater impacts associated with the proposed project. We understand that review by the City is to assure general compliance with standardized criteria contained in the FCSCM. If you should have any questions as you review this report, please feel free to contact us. Sincerely, SANDERSON STEWART Charles Sonnier, PE Senior Engineer/Project Manager H-25 Multi-Family April 7, 2021 Page 1 Project No. 19059.02 April 7, 2021 Project No. 19059.02 FINAL (FDP) STORMWATER MANAGEMENT REPORT FOR H-25 MULTI FAMILY A PORTION OF PARCEL NO. 8603000028 FORT COLLINS, COLORADO I. Overview Narrative The proposed project is a multi-family development that will include the construction of 12 new multi- plex buildings, a clubhouse with amenities and supporting infrastructure improvements. The purpose of this report is to identify the required stormwater management and water quality facilities for the developed site. The design standards governing this project are the Fort Collins Stormwater Criteria Manual (FCSCM), Dec 2018 and the Mile High Flood District’s Urban Storm Drainage Criteria Manual (USDCM), Volume 1-3. II. General Project Location The overall Harmony & Strauss Cabin development is a 266-acre site located at the southwest quadrant of Harmony Road and Interstate 25. The project site associated with this report consists of approximately 15.7-acres within Parcel No. 8603000028 (approximately 38 acres) that is located within the overall 266-acre development. More specifically, the project site lies within the southeast corner of Harmony Road and Strauss Cabin Road in the west half of Section 3, Township 6 North, Range 68 West, latitude 40.5228, longitude 104.9983. The site is generally bounded by Strauss Cabin Road on the west, Harmony Road on the north, Harmony Gardens landscape nursery on the east and Weitzel Pond on the south. Surrounding properties include: the Arapaho Bend Natural Area and the Harmony Road Transportation Transfer Center on the north side of Harmony Road, Island Lake Marina and the Eagle View Natural Area on the south side of Kechter Road, the Chandler property (now under Nine Bridges, LLC ownership) west of Strauss Cabin Road, the Mountain Life Church and the Budurus properties located along Strauss Cabin Road further to the south. East of the property is the I-25 interstate and the Town of Timnath. Refer to Appendix A for a Vicinity map. III. Existing Site Information Major Basin Description This property is located within the Cache la Poudre watershed and City of Fort Collins Poudre River drainage basin which is a major tributary to the South Platte River. Sub-Basin Description The site is mostly flat to minimally sloped. Generally, runoff from the site sheet flows to the east and south to the existing floodway channel and travels south through a series of existing large inactive gravel pits that have essentially become retention ponds for stormwater. This drainage way outlets into two culverts under Kechter Road, approximately a mile south from the project site and is assumed to be the historic stormwater release location for this area. Flow then conveys south of Kechter Road and into Island Lake then flows due east under I-25 and then south east approximately a half mile to Fossil Creek Reservoir Outlet and then another half mile onto the Cache La Poudre River. H-25 Multi-Family April 7, 2021 Page 2 Project No. 19059.02 A separate LOMR modeling effort is being performed with the City of Fort Collins’ and FEMA’s guidance that is being completed concurrently with this report. The intent of the modeling effort is to remove the portion of the project area from the existing floodplain that lies outside of the currently approved LOMR-F area and also allow residential buildings to be constructed within this area. Ultimately, it is anticipated that the proposed improvements will be located outside of the half-foot Poudre River floodway, with the exception of a few improvements that will require a No-Rise Certificate. These improvements include a dog park, a nature trail and a water main that will connect to an existing transmission water main located within the floodway. The Fossil Creek Reservoir Inlet Ditch (FCRID) and the Boxelder Ditch are located along the western side of the overall site with the FCRID being further to the west. The Boxelder Ditch crosses Strauss Cabin Road and enters the site approximately 1700’ south of Harmony Road. This project site sits within the FEMA regulated floodway and floodplain, per FEMA FIRM Maps 08069C0994F & 08069C1013F, dated December 19, 2006. According to the NRCS website, the site consists mainly of Caruso clay loam, 0 to 1 percent slope with a classification of Type C soils. This soil type has an erodibility factor of 0.32 which suggests a moderate susceptibility to sheet and rill erosion by runoff. Refer to Appendix A for soil classification information. Refer to Appendix A for soil data and floodplain map. IV. Project Description The proposed project will consist of 12 new multi-family buildings with 290 total units. Proposed utility improvements will consist of storm sewer, sanitary sewer and waterline improvements. Surface improvements will include driveway, parking lot, landscaped areas and concrete sidewalk surrounding the buildings. Off-site improvements will mainly consist of a sidewalk, a driveway connection, and an emergence access connection all along the east side of Strauss Cabin Road. V. Drainage Design Criteria A. Regulations/Development Criteria The design standards governing this project are the Fort Collins Stormwater Criteria Manual (FCSCM), Dec 2018 and the Mile High Flood District’s Urban Storm Drainage Criteria Manual (USDCM), Volume 1-3. B. Four-Step Process The overall stormwater management strategy employed with the proposed project utilizes the “Four Step Process” to minimize adverse impacts of urbanization on receiving waters. The following is a description of how the proposed development has incorporated each step. Step 1 – Employ Runoff Reduction Practices Several techniques have been utilized with the proposed development to facilitate the reduction of runoff peaks, volumes, and pollutant loads as the site is developed from the current use by implementing multiple Low Impact Development (LID) strategies. Proposed techniques include providing landscaped islands and buffer areas throughout the site to reduce the overall impervious area, to minimize directly connected impervious areas (MDCIA) and to H-25 Multi-Family April 7, 2021 Page 3 Project No. 19059.02 grade the site such that runoff is routed over a longer distance to reduce the time of concentration. Step 2 – Implement BMPs That Provide a Water Quality Capture Volume (WQCV) with Slow Release The efforts taken in Step 1 will facilitate the reduction of runoff; however, urban development of this intensity will still generate stormwater runoff that will require additional BMPs and water quality. The majority of stormwater runoff from the site will ultimately be treated by the existing Weitzel gravel pond to the south of the property. This large existing gravel pond will act as a sedimentation basin by allowing for the sediment, fines and pollution suspended in the stormwater to settle out into the existing groundwater fed ponds. Step 3 – Stabilize Streams There are no major wet drainage conveyances within the subject property, however, there is a dog park and some nature trail proposed within the adjacent half-foot Poudre River floodway that is dry year around. Proposed stabilization to this area will mainly be a result of the construction activity and will consist of temporary seeding with mulching and hydro- mulch. Permanent BMP measures will include permanent seeding and plantings, as needed. Step 4 – Implement Site Specific and Other Source Control BMPs The proposed project will improve upon site specific source controls compared to historic conditions: The proposed development will provide water quality treatment; thus, eliminating sources of potential pollution previously left exposed to weathering and runoff processes. C. Hydrological Criteria 1. The City of Fort Collins Rainfall Intensity-Duration-Frequency Curves, as depicted in Figure 3.4-1 of the FCSCM, serve as the source for all hydrologic computations associated with the proposed development. Tabulated data contained in Table 3.4-1 has been utilized for Rational Method runoff calculations. Refer to Appendix B for criteria used. 2. The Rational Method has been employed to compute stormwater runoff utilizing coefficients and calculation methods contained in Chapter 5, Section 3.2 of the FCSCM. 3. Three separate design storms have been utilized to address distinct drainage scenarios. The first design storm event analyzed was the “Minor,” or “Initial” Storm, which has a 2-year recurrence interval. The second event considered is the “Major Storm,” which has a 100-year recurrence interval. The third storm computed, for comparison purposes only, was the 10-year event. 4. No other assumptions or calculation methods have been used with this development that are not referenced by current City of Fort Collins criteria. 5. Per recent meetings with City Stormwater staff and per the approved ODP drainage report, the existing gravel pond adjacent and to the south of the project site will serve as detention, provide standard water quality treatment and will meet LID requirements. This will be the case until such time that future phasing of the 266- acre property is developed and a regional detention pond is constructed. Refer to H-25 Multi-Family April 7, 2021 Page 4 Project No. 19059.02 Appendix A for the ODP plan and Appendix D for excerpts from the associated ODP drainage report. D. Hydraulic Criteria 1. All drainage facilities proposed with the project are designed in accordance with criteria outlined in the FCSCM and/or the USDCM. Refer to Appendix B for Rational Method calculation. 2. The LOMR modeling effort as outlined in Section III above will be completed concurrently with the development plan process and will follow the City of Fort Collins and FEMA requirements. E. Modifications of Criteria 1. The proposed development is not requesting any modifications to criteria at this time. VI. Proposed Drainage Facilities A. General Concept The intent of the proposed design is to safely and adequately convey the minor and major design storm given the site’s existing constraints and off-site flooding concerns by the City that were previously mentioned. 1. Stormwater from the project site will be discharged into the existing Weitzel gravel pond to the south. This will serve as detention, provide standard water quality, and LID treatment until the overall 266- acre property develops further to the south and a regional detention pond is constructed. 2. Reservation of space is provided along Harmony Road for a potential future drainage channel that will accommodate and route the half-foot rise Poudre River floodway flows from the north around the project development site. The future drainage channel will require a hydraulic model through the CLOMR/LOMR process. This work is anticipated in the future to allow for other project sites within the 266-acre property to develop. 3. A more detailed description of the projects sub-basins and drainage patterns is provided below. B. Specific Details The proposed storm drainage system will collect runoff via sheet flow, curb and gutter and drainage pans and convey to proposed area and curb inlets. The storm drain piping will then convey the collected stormwater to the south and east and to existing Weitzel gravel pond adjacent to the south of the subject property. This pond is intended to provide detention, standard water quality and LID treatment for the proposed projects site. 1. There are twenty-two (22) total sub-basins for the project site. Eighteen (18) of these will be collected in the proposed storm system and the other four (4) are located on the fringes of the site and will mainly flow historically. A more detailed description of these sub-basins is described as follows: H-25 Multi-Family April 7, 2021 Page 5 Project No. 19059.02 Basin Nos. 1 through 18: These basins total to approximately 9.8 acres and are proposed to be collected in various storm inlets throughout the site via sheet flow, curb and gutter and drainage pans. The flow will then be piped to the south and discharged into the existing Weitzel gravel pond. These basins generally are comprised of rooftop, driveway and parking lot, sidewalk and landscaping. The percent composite imperviousness for all of these basins is approximately 74%. OS-1 and OS-4: These sub-basins total to approximately 0.7 acres and will collect flows from the back half of two building roof-tops and landscaping and discharge to adjacent Strauss Cabin Road. The flow from OS-1 travels along the east curb and gutter and south to an existing Type R inlet. Runoff from OS-4 travels north along the east curb and gutter to an existing Type R inlet also. Flow from these inlets convey south through a piped system and discharge approximately a half mile to the south of the project site into the existing Weitzel gravel pond. The percent composite imperviousness for both of these basins is approximately 36%. Basin OS-2: This 4-acre sub-basin will collect flows from the back half of two building roof-tops, landscaping, and undisturbed ground and convey to south to existing Weitzel gravel pond via grassed swales and overland flow. This basin has a percent imperviousness of approximately 6%. Basin OS-3: This 3-acre sub-basin will collect flows from Harmony Road runoff, the landscaping and undisturbed ground and convey to the east and then south via existing drainage channels and low-lying areas to existing Weitzel gravel pond. This basin has a percent imperviousness of approximately 2%. Refer to Appendix D for the Drainage Basin Map 2. Rational Method calculations were performed for each sub-basin to calculate inlet and pipe sizing. The Mile High Flood District’s UD Inlet Version 4.06 spreadsheets were used to calculate inlet sizing to accept the 2-year and 100-year design storm events for the combination inlets. Refer to Appendix C for print outs of the UD Inlet spreadsheets. 3. 100-year flow rates within each sub-basin calculated by the Rational Method were assumed to be contributory to the sub-surface storm drain system. Hydraflow Storm Sewers Extension for Autodesk Civil 3D Version 2019.2 was used to determine pipe sizes and slopes that would allow the hydraulic grade lines (HGLs) to remain below proposed finish grade. Refer to Appendix C for plan and profiles of storm drain system 4. Standard water quality and LID treatment will be served by the existing Weitzel gravel pond to which the runoff from the project site will discharge into. 5. Final design details, and construction documentation shall be provided to the City of Fort Collins for review prior to Final Development Plan approval. 6. Stormwater facility Standard Operating Procedures (SOP) will be provided by the City of Fort Collins in the Development Agreement. H-25 Multi-Family April 7, 2021 Page 6 Project No. 19059.02 C. Floodplain Management The project site sits within the FEMA regulated floodway and floodplain, per FEMA FIRM Maps 08069C0994F & 08069C1013F, dated December 19, 2006. More specifically, flood zone designations within this project site are as follows: • Flood Zone AE, FLOODWAY AREA: Flood Zone AE is determined to be a Special Flood Hazard Area subject to inundation by the 1% annual chance flood. The 1% annual chance flood has a 1% chance of being equaled or exceeded in any given year. Zone AE is where base flood elevations have been determined. Floodway areas in zone AE show the location of the channel of the stream plus any adjacent floodplain areas that must be kept free of encroachment so that the 1% annual chance flood can be carried without substantial increases in flood heights. • Flood Zone AE, 100-YEAR FLOODPLAIN: Flood Zone AE is determined to be a Special Flood Hazard Area subject to inundation by the 1% annual chance flood. The 1% annual chance flood has a 1% chance of being equaled or exceeded in any given year. Zone AE is where base flood elevations have been determined. • Flood Zone X, Shaded: Areas of 0.2% annual chance flood. • Flood Zone X, Unshaded: Areas determined to be outside the 0.2% annual chance floodplain. • There exists an approved LOMR-F (Case # 00-08-175A, effective date 12-12-2000) across a portion of the project site. • There exists an approved CLOMR-F (Case # 00-08-182C) across a portion of the project site. Refer to Appendix F for CLOMR-F documents. • There is also an approved LOMR (Case # 14-08-0580P, effective date 12-15-2014) that corrected the floodway and floodplain lines to align with the original floodplain workmap. Information provided in this LOMR was taken into consideration when determining the project limits. • Chapter 10, Flood Prevention and Protection, of the Fort Collins Municipal Code provided guidance and limitations for building and development within the floodway and floodplain. Some of the fundamental flood protection requirements for this project site include: o Designing and constructing buildings with a lowest finished floor (FF) being 24” above the FEMA Base Flood Elevation (BFE) as shown on the FEMA FIRM map for the area; o Building foundation types anticipated for the buildings on this site include slab- on-grade or crawl space. (Basements are not anticipated for buildings at this project site.) If crawl space foundation type is utilized then they must be built in accordance with the requirements of the City of Fort Collins Municipal Code, safety and venting requirements outlined in Section 10-39, and specific standards for crawl spaces outlined in Section 40; H-25 Multi-Family April 7, 2021 Page 7 Project No. 19059.02 o Regulatory Floodproof Elevation (RFPE) being 12” above the BFE; o Structures built within the floodplain (or flood fringe) are required to have an Emergency Preparedness Plan (ERPP); o No floatable materials are allowed unless they are properly anchored. o Floodplain Use Permits will be required to be submitted for any construction located within designated floodplain and/or floodway. o Elevation or floodproofing certificates will be required before Certificate of Occupancy is issued for any building. D. Low Impact Development (LID) The LID requirement for this project is treating at least 75% of the new and/or modified impervious areas which translates to approximately 373,262 square feet of area to be treated. Approximately 396,832 square feet (or 80% of the of the new and/or modified impervious area) will to the outfall that discharges into the existing Weitzel gravel pond to the south where standard water quality and LID level treatments will occur. 1. Existing Weitzel Gravel Pond The Weitzel Pits are simply inactive gravel mine pits that have become ponds due to the water table elevation in the area. The west pit (denoted as Ex. Gravel Pond #1 in the approved ODP), the largest of the Weitzel Pits, will be utilized as a detention and water quality basin for stormwater runoff from the project site. Refer to Appendix E for pages from the approved ODP drainage report. VII. Variance Requests (if necessary) The proposed development is not requesting any variances at this time. VIII. Erosion Control Erosion and sediment control will be achieved through construction control measures to include various BMPs selected from the FCSCM such as silt fencing, vehicle tracking devices, inlet/outlet protection and curb protection, concrete washout, vehicle tracking control and stabilized staging areas. BMP locations are shown in the corresponding Utility Plans associated with this report. A separate Erosion Control Report and Erosion Control Plans have also been prepared and associated with this final drainage report. See Appendix D for Erosion Control Plan. IX. Conclusion The proposed drainage system design will provide safe conveyance of the minor and major storm events while providing increased water quality treatment compared to the existing condition. The City of Fort Collins Stormwater Criteria Manual has been used to establish the criteria for a developed condition runoff plan within the H-25 Multi Family project area. This FDP drainage design report has highlighted the following items: H-25 Multi-Family April 7, 2021 Page 8 Project No. 19059.02 • Project site development is outside of the effective half-foot Poudre River floodway boundary, with the exception of a few improvements that will require a No-Rise Certificate. • Reservation of space is provided along Harmony Road for a potential future drainage channel that will accommodate and route the offsite half-foot rise Poudre River floodway flows from the north around the project development site. • Stormwater detention, standard water quality and LID treatment are provided within the existing Weitzel gravel pond. A. Compliance with Standards 1. The drainage design proposed with the proposed project complies with the City of Fort Collins’ Stormwater Criteria Manual. 2. The drainage design proposed with this project complies with requirements for Cache La Poudre Drainage Basin. 3. The drainage plan and stormwater management measures proposed with the proposed development are compliant with all applicable State and Federal regulations governing stormwater discharge. 4. The erosion control materials submitted with the final plans comply with the requirements set forth by the City of Fort Collins’ Stormwater Criteria Manual and the Urban Storm Drainage Criteria Manual. B. Drainage Concept 1. The drainage design proposed with this project will effectively limit any potential flooding and/or damage associated with runoff quantities while effectively treating runoff through water quality mitigation features. 2. Water quality will be treated through grass buffers, grassed swales and existing gravel pond. H-25 Multi-Family April 7, 2021 Page 9 Project No. 19059.02 REFERENCES 1. City of Fort Collins, December 2018, Fort Collins Stormwater Criteria Manual. 2. Mile High Flood District, 2001 (November 2010 with some sections updated April 2018), Urban Storm Drainage Criteria Manual, Volume 3, Stormwater Quality. 3. United States Department of Agriculture Natural Resources Conservation Service; Web Soil Survey; accessed on-line September 2019. 4. Federal Emergency Management Agency; FEMA Flood Map Service Center; accessed on-line September 2019. APPENDICES 1. Appendix A - Site Information a. Vicinity Map b. ODP Plan c. Site Plan d. NRCS Soils Data e. FEMA Maps 2. Appendix B – Rational Method Calculations a. Storm Criteria b. Rational Method Calculations 3. Appendix C – Storm System Calculations a. Inlet Calculations b. Storm Drain Calculations 4. Appendix D – Drainage Basin Map a. Drainage Basin Map b. Erosion Control Plan 5. Appendix E – ODP Drainage Report a. Pages from the ODP Drainage Report 6. Appendix F –CLOMR-F Documents a. CLOMR-F Case No. Document b. LOMR/CLOMR-F Exhibit APPENDIX A H-25 Multi-Family – Fort Collins, CO 19059.02 Map data ©2019 Google 1000 ftSiteLocation ZONING:HC 138.55 ACRES EXISTING ZONING (CITY OF FORT COLLINS): T EXISTING USE: LANDSCAPE COMPANY EFFECTIVE 1/2 FOOT RISE FLOODWAY EFFECTIVE 500-YEAR FLOODPLAIN EFFECTIVE 100-YEAR FLOODPLAIN EXISTING ZONING (CITY OF FORT COLLINS): EMPLOYMENT/ HARMONY CORRIDOR EXISTING USES: UNIMPROVED AREA B 660' 660' 660' 490' FUTURE LAND USE TO BE DETERMINED EXISTING GRAVEL POND EXISTING GRAVEL POND2-LANE ARTERIAL60' EXISTING ROWSTREETSCAPE, DRAINAGE, AND LANDSCAPE SETBACK 870' RIGHT-IN RIGHT-OUT INTERSECTION FULL MOVEMENT INTERSECTION 3 4 MOVEMENT INTERSECTION FULL MOVEMENT INTERSECTION AREA A +/- 7.10 ACRES (SECONDARY USES) +/- 1.9 ACRES (PRIMARY USE) +/- 6.75 ACRES (SECONDARY USES) AREA C +/- 5.00 ACRES (PRIMARY USES) AREA D +/-12.75 ACRES (PRIMARY USES) AREA E +/-14.50 ACRES (PRIMARY USES) LIMIT OF DEVELOPMENT BOUNDARY BOXELDER IRRIGATION DITCH(NO RECORD EASEMENT)SUNRISE RIDGE FIRST FILING EXISTING GRAVEL POND EXIST ING BOXELDER IRR IGAT ION D ITCH EXISTING GRAVEL POND EXISTING STRUCTURES EXISTING VEGETATION - MIX OF AUSTRIAN AND PONDEROSA PINES COTTONWOODS, WILLOWS, AND RUSSIAN OLIVES EXISTING VEGETATION - MIX OF ELMS AND RUSSIAN OLIVES EXISTING VEGETATION - PREDOMINANTLY RUSSIAN OLIVES AND SOME WILLOWS (TYP) EXISTING COTTONWOOD TREE APPROXIMATE LOCATION OF EXISTING WETLANDS TO BE MAPPED AT TIME OF ECS ASSOCIATED WITH THE PDP AND FDP SUBMITTAL (TYP) APPROXIMATE LOCATION OF EXISTING WETLANDS TO BE MAPPED AT TIME OF ECS ASSOCIATED WITH THE PDP AND FDP SUBMITTAL (TYP) LIMIT OF DEVELOPMENT BOUNDARY 50' NATURAL FEATURE BUFFER FROM EXISTING WETLAND UNDER 1/3 OF AN ACRE IN SIZE (TYP) 50' NATURAL FEATURE BUFFER FROM EXISTING WETLAND UNDER 1/3 OF AN ACRE IN SIZE (TYP) 50' BUFFER FROM IRRIGATION DITCH (TYP) 825' BUFFER FROM HERON ROOKERY(TYP) HERON ROOKERY 150' NATURAL FEATURE BUFFER FROM EXISTING WETLAND OVER 1/3 OF AN ACRE IN SIZE (TYP) ACTUAL BUFFER TO BE DETERMINED IN PDP PROCESS FLOODPLAIN NOTES SCALE: 1"= 150'-0"NORTH 150'0 75'300' SITE DATA TABLEEXISTING CONDITIONS AND NATURAL FEATURES PLAN LIMIT OF DEVELOPMENT PLAN ODP LEGEND NOTES: SYMBOL NOTES EXISTING INTERSECTION PROPOSED FULL MOVEMENT INTERSECTION PROPOSED 3/4 MOVEMENT INTERSECTION PROPOSED RIGHT IN/RIGHT OUT INTERSECTION SYMBOL NOTES PROPOSED STREET ACCESS PEDESTRIAN AND BIKE CONNECTIONS LIMIT OF DEVELOPMENT 1/2 FOOT RISE FLOODWAY 100-YEAR FLOODPLAIN 500-YEAR FLOODPLAIN 1.THIS PROJECT SITE IS LOCATED WITHIN FEMA REGULATED FLOODWAY AND FLOODPLAINS, PER FEMA FIRM MAPS 08069C0994F AND 08069C1013F, DATED DECEMBER 19, 2006. 2.PORTIONS OF THIS SITE ARE LOCATED IN THE FEMA - REGULATORY 100- AND 500-YEAR FLOOD PLAINS, AND THE 1 2 -FOOT RISE FLOODWAY. 3.ALL AREAS IN THE FLOODPLAIN AND FLOODWAY ARE SUBJECT TO THE STANDARDS OF CHAPTER 10 OF THE FORT COLLINS MUNICIPAL CODE. 4.NO WORK MAY COMMENCE IN THE FLOODWAY UNTIL A FLOODPLAIN USE PERMIT AND NO-RISE CERTIFICATION HAVE BEEN APPROVED BY THE CITY OF FORT COLLINS FLOODPLAIN ADMINISTRATION DIVISION. NO-RISE CERTIFICATIONS MUST BE RE-CERTIFIED POST PROJECT. 5.ALL WORK IN THE FLOOD FRINGE MUST BE PRECEDED BY AN APPROVED FLOODPLAIN USE PERMIT. 6.CRITICAL FACILITIES ARE PROHIBITED IN FLOODPLAINS. 7.NO NEW STRUCTURES OR ADDITIONS MAY BE ADDED TO THE FLOODWAY. 8.ALL STRUCTURES IN THE FLOODWAY MUST HAVE AN ERPP. 9.WITHIN THE FLOODWAY, A CONDITIONAL LETTER OF MAP REVISION (CLOMR) MUST BE APPROVED BY FEMA PRIOR TO ISSUANCE OF ANY BUILDING OR GRADING PERMITS. 10.STORMWATER FLOWS THAT OVERTOP HARMONY ROAD AND ONTO THE PROJECT SITE WILL BE REQUIRED TO BE INCLUDED IN A CLOMR ANALYSIS AND APPROVED BY FEMA WHERE DEVELOPED SITE AND CHANNEL DESIGNS OCCUR WITHIN THE FEMA REGULATED FLOODWAY BOUNDARIES. 11.IT IS THE DEVELOPER'S INTENT TO REVISE THE ROUTING OF THE FLOODPLAIN AND FLOODWAY THROUGH THE SITE IN THE FUTURE TO ACCOMMODATE FUTURE DEVELOPMENT WITHIN THE ODP BOUNDARY. ONCE A CLOMR ANALYSIS SHOWING A RECONFIGURATION OF THE FLOODPLAIN AND FLOODWAY THROUGH THE SITE HAS BEEN APPROVED BY THE CITY OF FORT COLLINS AND FEMA, AN AMENDED ODP WILL BE PROVIDED TO SHOW LAND USES, ROADWAY CONNECTIONS TO ADJACENT ARTERIAL ROADWAYS, PER THE CITY OF FORT COLLINS LAND USE CODE SECTIONS 3.6.3 E AND F, AND PEDESTRIAN TRAIL CONNECTIVITY THROUGH THE SITE PER THE FORT COLLINS PARKS & RECREATION POLICY PLAN MASTER PLAN. 1.ALL DEVELOPMENT SHOWN IS CURRENTLY OUT OF THE 1/2 RISE FLOODWAY. 2.PROPOSED USES ARE PER THE HARMONY CORRIDOR DISTRICT (H-C). 3.DEVELOPMENT OF THIS OVERALL DEVELOPMENT PLAN SHALL COMPLY WITH THE HARMONY CORRIDOR (H-C) PLAN REQUIREMENTS AS WELL AS THE HARMONY CORRIDOR STANDARDS AND GUIDELINES. 4.THIS OVERALL DEVELOPMENT PLAN SHOWS THE GENERAL LOCATION AND APPROXIMATE SIZE OF ALL NATURAL AREAS, HABITATS, AND FEATURES WITHIN ITS BOUNDARIES AND THE PROPOSED ROUGH ESTIMATE OF THE NATURAL AREA BUFFER ZONE AS REQUIRED BY LAND USE CODE SECTION 3.4.1(E). DETAILED MAPPING OF A SITE'S NATURAL AREAS, HABITATS, AND FEATURES WILL BE PROVIDED AT THE TIME OF INDIVIDUAL PDP SUBMITTALS. GENERAL BUFFER ZONES SHOWN ON THIS ODP MAY BE REDUCED OR ENLARGED BY THE DECISION MAKER DURING THE PDP PROCESS. 5.AT THE TIME OF EACH PDP, AN ECOLOGICAL CHARACTERIZATION STUDY WILL BE PERFORMED TO MATCH THE SCOPE OF THE PDP. THIS ECS WILL DOCUMENT THE EXISTING SIGNIFICANT ECOLOGICAL VALUE OF THE SITE, AND PROPOSE MITIGATION FOR THE IMPACTS THE DEVELOPMENT WILL HAVE TO THE ECOLOGICAL VALUE ON THE SITE. THE ECS REPORT AND THE PROTECTION AND MITIGATION WILL BE CONSISTENT WITH THE CITY OF FORT COLLINS LUC SECTION 3.4.1. 6.THE DESIGN APPROACH TO THIS DEVELOPMENT WILL BE CONSISTENT WITH THE HARMONY CORRIDOR PLAN GATEWAY AREA CONCEPT. THIS CONCEPT CREATES A UNIQUE GATEWAY THAT EMPHASIZES THE RIVER VALLEY SETTING AND FOCUSES ON RIPARIAN FORESTS AND THICKET PLANTINGS OF NATIVE TREES AND SHRUBS. BUILDINGS, PARKING AND SITE AMENITIES WILL INTEGRATE WITH THESE NATIVE PLANTINGS AND FEATURES IN A WAY THAT IS BOTH SENSITIVE TO THE GOALS OF THE GATEWAY AREA CONCEPT PLAN AND CONSISTENT WITH THE GOALS OF THE DEVELOPMENT. 7.ANY CHANGE IN THE LOCATION OF ACCESS POINTS WITH PDP SUBMITTALS NEEDS TO COMPLY WITH THE CITY OF FORT COLLINS LAND USE CODE AND THE LARIMER COUNTY URBAN AREA STREET STANDARDS. THE FINAL LOCATION OF ACCESS POINTS WILL BE BASED UPON TRAFFIC STUDY REQUIREMENTS FOR INTERSECTION AND LANEAGE FUNCTIONALITY. ACCESS POINTS ARE CONDITIONAL BASED ON INTERSECTION SPACING AND SIGHT DISTANCE. 8.STREET STANDARDS WILL BE SUBJECT TO THE DESIGN STANDARDS IN EFFECT AT THE TIME OF APPLICATION FOR PROJECT DEVELOPMENT PLANS (PDPS). 9.COMMON OPEN SPACE AREAS AND STREETSCAPES WILL BE MAINTAINED BY THE OWNER/DEVELOPER OR A HOMEOWNERS' ASSOCIATION (HOA).THE DEVELOPER/OWNER OR HOA WILL MAINTAIN ALL STREETSCAPES, SIDEWALKS, AND BICYCLE/PEDESTRIAN TRAILS INCLUDING SNOW REMOVAL. 10.OFFSITE IMPROVEMENTS MAY BE REQUIRED AT THE TIME OF PDP IN ORDER TO MEET LEVEL OF SERVICE FOR ALL MODES OF TRANSPORTATION. 11.AUXILIARY LANES AND TRAFFIC SIGNAL CONTROL WILL BE REQUIRED AT THE STRAUSS CABIN AND HARMONY ROAD INTERSECTION. THE TIMING OF THE INSTALLATION OF THESE IMPROVEMENTS WILL BE DETERMINED AT THE TIME OF PDP. 12.SIGHT DISTANCE EASEMENTS MAY BE REQUIRED ALONG THE PUBLIC ROADWAYS AT THE TIME OF PDP REVIEW. 13.ACCESS POINT LOCATIONS ARE SUBJECT TO THE ABILITY TO MEET SIGHT DISTANCE REQUIREMENTS. 14. DEVELOPMENT OF THIS ODP SHALL INCLUDE THE IMPLEMENTATION OF THE REQUIRED LOW IMPACT DEVELOPMENT CAPTURE VOLUME, AS PER THE CITY OF FORT COLLINS CRITERIA, THAT HAS BEEN CALCULATED WITH THE APPROVED FINAL DRAINAGE REPORT FOR HARMONY 23, BUT NOT ESTABLISHED WITHIN THE BOUNDARY OF THAT PROJECT. APPROXIMATE LOCATION OF WETLANDS - TO BE VERIFIED THROUGH ECS REPORT AT THE TIME OF PDP EXISTING TREES ON SITE, MOSTLY RUSSIAN OLIVES WITH SOME COTTONWOODS AND WILLOWS BUFFERS, DIMENSIONS VARY SCALE: 1"= 300'-0"NORTH 150'0 300'600' Project Area BLDG 1 BLDG 2 BLDG 3 BLDG 6 BLDG 12 BLDG 10 BLDG 7 BLDG 9 BLDG 4 BLDG 11 BLDG 5 BLDG 8 CAR CARETRASHENCLOSURE BIKE RACKS HARMONY ROAD STRAUSS CABIN ROADEX FIBER OPTIC VAULT EX 24" RCP INV=4845.5 15" STEEL INV=4845.8 EX ELECTRICAL CABINET EX DRAIN CHASE EX DRAIN CHASE FIBER OPTIC VAULT 0 50 SCALE: 1" = 50' 1002550 PRELIMINARY DEVELOPMENT PLANNORTH NOTE: -EXISTING UNDERGROUND INSTALLATIONS & PRIVATE UTILITIES SHOWN ARE INDICATED ACCORDING TO THE BEST INFORMATION AVAILABLE TO THE ENGINEER. THE ENGINEER DOES NOT GUARANTEE THE ACCURACY OF SUCH INFORMATION. SERVICE LINES (WATER, POWER, GAS, STORM, SEWER, TELEPHONE & TELEVISION) MAY NOT BE STRAIGHT LINES OR AS INDICATED ON THE PLANS. STATE LAW REQUIRES CONTRACTOR TO CALL ALL UTILITY COMPANIES BEFORE EXCAVATION FOR EXACT LOCATIONS. -UNLESS OTHERWISE SPECIFIED, ALL CONSTRUCTION LAYOUT AND STAKING SHALL BE PERFORMED UNDER THE RESPONSIBLE CHARGE OF A LAND SURVEYOR LICENSED IN THE STATE WHERE THE PROJECT IS LOCATED AND BY A PARTY CHIEF OR ENGINEERING TECHNICIAN EXPERIENCED IN CONSTRUCTION LAYOUT AND STAKING TECHNIQUES AS ARE REQUIRED BY THE SPECIFIC TYPE OF WORK BEING PERFORMED.FILE:PROJECT NO:CAD:QUALITY ASSURANCE:DRAWING HISTORYDATE DESCRIPTIONHARMONY & STRAUSS CABIN ROADSITE PLANH-25 MULTI FAMILY DEVELOPMENT FORT COLLINS, COC3.0 CJS19059.02_SITE_PROD.DWGICS2/19/201ST PDP SUBMITTAL7/01/209/30/2010/26/20---2ND PDP SUBMITTAL3RD PDP SUBMITTAL4TH PDP SUBMITTAL-----19059.02 PLAN NOTES 1 NEW ASPHALT PAVING NEW CONCRETE WALK NEW ACCESSIBILITY RAMP NEW 4" PAINTED WHITE STRIPE AT 3' O.C. (TYP.) NEW PAINTED INTERNATIONAL DISABLED SYMBOL (TYP.) NEW 4" PAINTED WHITE PARKING STRIPE (TYP.) NEW CONCRETE DRIVE APPROACH PER LCUASS STANDARDS 12" WHITE STOP BAR STOP SIGN (R1-1) NEW TRASH PAD AND ENCLOSURE (SEE ARCH. FOR DETAILS) 2 3 4 5 6 7 8 9 10 NEW BIKE RACKS11 POOL AND AMENITY AREA12 TRANSFORMER PAD PARK SPACE/PLAYGROUND PEDESTRIAN TRAIL (CRUSHER FINES) DEAD-END BARRICADE 13 14 15 16 SECONDARY EMERGENCY ACCESS WITH FENCING AND ROLL-OVER CURB17 LANDSCAPE WALL FOR TREE PROTECTION18 NEW CURB AND GUTTER (TYP.)19 DOG PARK WITH BREAKAWAY FENCING20 LANDSCAPE BERMS (TYP.)21 DOGHOUSES WITH FIRE RISER (TYP.)22 LIGHT POLES23 PICNIC TABLES AND CORNHOLE24 PEDESTRIAN HANDICAP RAMPS AND CROSSWALK (TYP.)25 SIDEWALK CHASE AND FLUME (TO MATCH EXISTING WIDTH)26 CITY OF FORT COLLINS, COLORADO UTILITY PLAN APPROVAL APPROVED: CHECKED BY: CHECKED BY: CHECKED BY: CHECKED BY: CHECKED BY: CITY ENGINEER DATE WATER & WASTEWATER UTILITY DATE STORMWATER UTILITY DATE PARKS & RECREATION DATE TRAFFIC ENGINEER DATE ENVIRONMENTAL PLANNER DATE STANDARD 90 DEGREE PARKING SPACE WITH 2' OVERHANG (TYP.)27 SIDEWALK ANGLED PARKING SPACE WITH 2' OVERHANG (TYP.)28 STANDARD COMPACT PARKING SPACES (TYP.)29 PARALLEL PARKING SPACES (TYP.)30 CRITICAL ROOT ZONE OF TREES TO REMAIN AND BE PROTECTED31 +\GURORJLF6RLO*URXS²/DULPHU&RXQW\$UHD&RORUDGR 2'3/DQG8VHV$UHD2QO\ 1DWXUDO5HVRXUFHV &RQVHUYDWLRQ6HUYLFH :HE6RLO6XUYH\ 1DWLRQDO&RRSHUDWLYH6RLO6XUYH\ 3DJHRI 1 : 1 : 1 : 1 :1 0DSSURMHFWLRQ:HE0HUFDWRU&RUQHUFRRUGLQDWHV:*6(GJHWLFV870=RQH1:*6 )HHW 0HWHUV 0DS6FDOHLISULQWHGRQ$SRUWUDLW[VKHHW Project Site 0$3/(*(1' 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$JJUHJDWLRQ0HWKRG'RPLQDQW&RQGLWLRQ &RPSRQHQW3HUFHQW&XWRII1RQH6SHFLILHG 7LHEUHDN5XOH+LJKHU +\GURORJLF6RLO*URXS²/DULPHU&RXQW\$UHD&RORUDGR 2'3/DQG8VHV$UHD2QO\ 1DWXUDO5HVRXUFHV &RQVHUYDWLRQ6HUYLFH :HE6RLO6XUYH\ 1DWLRQDO&RRSHUDWLYH6RLO6XUYH\ 3DJHRI Engineering Properties This table gives the engineering classifications and the range of engineering properties for the layers of each soil in the survey area. Hydrologic soil group is a group of soils having similar runoff potential under similar storm and cover conditions. The criteria for determining Hydrologic soil group is found in the National Engineering Handbook, Chapter 7 issued May 2007(http://directives.sc.egov.usda.gov/OpenNonWebContent.aspx? content=17757.wba). Listing HSGs by soil map unit component and not by soil series is a new concept for the engineers. Past engineering references contained lists of HSGs by soil series. Soil series are continually being defined and redefined, and the list of soil series names changes so frequently as to make the task of maintaining a single national list virtually impossible. Therefore, the criteria is now used to calculate the HSG using the component soil properties and no such national series lists will be maintained. All such references are obsolete and their use should be discontinued. Soil properties that influence runoff potential are those that influence the minimum rate of infiltration for a bare soil after prolonged wetting and when not frozen. These properties are depth to a seasonal high water table, saturated hydraulic conductivity after prolonged wetting, and depth to a layer with a very slow water transmission rate. Changes in soil properties caused by land management or climate changes also cause the hydrologic soil group to change. The influence of ground cover is treated independently. There are four hydrologic soil groups, A, B, C, and D, and three dual groups, A/D, B/D, and C/D. In the dual groups, the first letter is for drained areas and the second letter is for undrained areas. The four hydrologic soil groups are described in the following paragraphs: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. Depth to the upper and lower boundaries of each layer is indicated. Engineering Properties---Larimer County Area, Colorado Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 1/14/2020 Page 1 of 5 Texture is given in the standard terms used by the U.S. Department of Agriculture. These terms are defined according to percentages of sand, silt, and clay in the fraction of the soil that is less than 2 millimeters in diameter. "Loam," for example, is soil that is 7 to 27 percent clay, 28 to 50 percent silt, and less than 52 percent sand. If the content of particles coarser than sand is 15 percent or more, an appropriate modifier is added, for example, "gravelly." Classification of the soils is determined according to the Unified soil classification system (ASTM, 2005) and the system adopted by the American Association of State Highway and Transportation Officials (AASHTO, 2004). The Unified system classifies soils according to properties that affect their use as construction material. Soils are classified according to particle-size distribution of the fraction less than 3 inches in diameter and according to plasticity index, liquid limit, and organic matter content. Sandy and gravelly soils are identified as GW, GP, GM, GC, SW, SP, SM, and SC; silty and clayey soils as ML, CL, OL, MH, CH, and OH; and highly organic soils as PT. Soils exhibiting engineering properties of two groups can have a dual classification, for example, CL-ML. The AASHTO system classifies soils according to those properties that affect roadway construction and maintenance. In this system, the fraction of a mineral soil that is less than 3 inches in diameter is classified in one of seven groups from A-1 through A-7 on the basis of particle-size distribution, liquid limit, and plasticity index. Soils in group A-1 are coarse grained and low in content of fines (silt and clay). At the other extreme, soils in group A-7 are fine grained. Highly organic soils are classified in group A-8 on the basis of visual inspection. If laboratory data are available, the A-1, A-2, and A-7 groups are further classified as A-1-a, A-1-b, A-2-4, A-2-5, A-2-6, A-2-7, A-7-5, or A-7-6. As an additional refinement, the suitability of a soil as subgrade material can be indicated by a group index number. Group index numbers range from 0 for the best subgrade material to 20 or higher for the poorest. Percentage of rock fragments larger than 10 inches in diameter and 3 to 10 inches in diameter are indicated as a percentage of the total soil on a dry-weight basis. The percentages are estimates determined mainly by converting volume percentage in the field to weight percentage. Three values are provided to identify the expected Low (L), Representative Value (R), and High (H). Percentage (of soil particles) passing designated sieves is the percentage of the soil fraction less than 3 inches in diameter based on an ovendry weight. The sieves, numbers 4, 10, 40, and 200 (USA Standard Series), have openings of 4.76, 2.00, 0.420, and 0.074 millimeters, respectively. Estimates are based on laboratory tests of soils sampled in the survey area and in nearby areas and on estimates made in the field. Three values are provided to identify the expected Low (L), Representative Value (R), and High (H). Liquid limit and plasticity index (Atterberg limits) indicate the plasticity characteristics of a soil. The estimates are based on test data from the survey area or from nearby areas and on field examination. Three values are provided to identify the expected Low (L), Representative Value (R), and High (H). References: American Association of State Highway and Transportation Officials (AASHTO). 2004. Standard specifications for transportation materials and methods of sampling and testing. 24th edition. Engineering Properties---Larimer County Area, Colorado Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 1/14/2020 Page 2 of 5 American Society for Testing and Materials (ASTM). 2005. Standard classification of soils for engineering purposes. ASTM Standard D2487-00. Engineering Properties---Larimer County Area, Colorado Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 1/14/2020 Page 3 of 5 Report—Engineering Properties Absence of an entry indicates that the data were not estimated. The asterisk '*' denotes the representative texture; other possible textures follow the dash. The criteria for determining the hydrologic soil group for individual soil components is found in the National Engineering Handbook, Chapter 7 issued May 2007(http://directives.sc.egov.usda.gov/ OpenNonWebContent.aspx?content=17757.wba). Three values are provided to identify the expected Low (L), Representative Value (R), and High (H). Engineering Properties–Larimer County Area, Colorado Map unit symbol and soil name Pct. of map unit Hydrolo gic group Depth USDA texture Classification Pct Fragments Percentage passing sieve number—Liquid limit Plasticit y index Unified AASHTO >10 inches 3-10 inches 4 10 40 200 In L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H 5—Aquepts, loamy Aquepts 80 A/D 0-60 Variable —————————— 22—Caruso clay loam, 0 to 1 percent slope Caruso 85 D 0-35 Clay loam CL A-6 0- 0- 0 0- 0- 0 95-98-1 00 95-98-1 00 90-93- 95 70-75- 80 30-33 -35 10-13-1 5 35-44 Fine sandy loam, sandy loam SC-SM, SM A-2, A-4 0- 3- 5 0- 3- 5 85-90- 95 65-75- 85 40-60- 80 25-40- 55 20-23 -25 NP-3 -5 44-60 Sand, gravelly sand SP-SM, SW-SM A-1 0- 3- 5 0- 5- 10 60-75- 90 55-58- 60 30-38- 45 5-10- 15 —NP 64—Loveland clay loam, 0 to 1 percent slopes Loveland 90 C 0-15 Clay loam CL A-6 0- 3- 5 0- 3- 5 90-95-1 00 85-93-1 00 80-85- 90 60-70- 80 30-35 -40 10-15-2 0 15-32 Clay loam, silty clay loam, loam CL, CL- ML A-4, A-6 0- 3- 5 0- 3- 5 90-95-1 00 85-93-1 00 80-85- 90 50-68- 85 25-30 -35 5-10-15 32-60 Very gravelly sand, gravelly sand, gravelly coarse sand GP, SP A-1 0- 3- 5 0- 5- 10 40-60- 80 30-50- 70 20-30- 40 0- 3- 5 —NP Engineering Properties---Larimer County Area, Colorado Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 1/14/2020 Page 4 of 5 Physical Soil Properties This table shows estimates of some physical characteristics and features that affect soil behavior. These estimates are given for the layers of each soil in the survey area. The estimates are based on field observations and on test data for these and similar soils. Depth to the upper and lower boundaries of each layer is indicated. Particle size is the effective diameter of a soil particle as measured by sedimentation, sieving, or micrometric methods. Particle sizes are expressed as classes with specific effective diameter class limits. The broad classes are sand, silt, and clay, ranging from the larger to the smaller. Sand as a soil separate consists of mineral soil particles that are 0.05 millimeter to 2 millimeters in diameter. In this table, the estimated sand content of each soil layer is given as a percentage, by weight, of the soil material that is less than 2 millimeters in diameter. Silt as a soil separate consists of mineral soil particles that are 0.002 to 0.05 millimeter in diameter. In this table, the estimated silt content of each soil layer is given as a percentage, by weight, of the soil material that is less than 2 millimeters in diameter. Clay as a soil separate consists of mineral soil particles that are less than 0.002 millimeter in diameter. In this table, the estimated clay content of each soil layer is given as a percentage, by weight, of the soil material that is less than 2 millimeters in diameter. The content of sand, silt, and clay affects the physical behavior of a soil. Particle size is important for engineering and agronomic interpretations, for determination of soil hydrologic qualities, and for soil classification. The amount and kind of clay affect the fertility and physical condition of the soil and the ability of the soil to adsorb cations and to retain moisture. They influence shrink-swell potential, saturated hydraulic conductivity (Ksat), plasticity, the ease of soil dispersion, and other soil properties. The amount and kind of clay in a soil also affect tillage and earthmoving operations. Moist bulk density is the weight of soil (ovendry) per unit volume. Volume is measured when the soil is at field moisture capacity, that is, the moisture content at 1/3- or 1/10-bar (33kPa or 10kPa) moisture tension. Weight is determined after the soil is dried at 105 degrees C. In the table, the estimated moist bulk density of each soil horizon is expressed in grams per cubic centimeter of soil material that is less than 2 millimeters in diameter. Bulk density data are used to compute linear extensibility, shrink-swell potential, available water capacity, total pore space, and other soil properties. The moist bulk density of a soil indicates the pore space available for water and roots. Depending on soil texture, a bulk density of more than 1.4 can restrict water storage and root penetration. Moist bulk density is influenced by texture, kind of clay, content of organic matter, and soil structure. Physical Soil Properties---Larimer County Area, Colorado Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 1/14/2020 Page 1 of 6 Saturated hydraulic conductivity (Ksat) refers to the ease with which pores in a saturated soil transmit water. The estimates in the table are expressed in terms of micrometers per second. They are based on soil characteristics observed in the field, particularly structure, porosity, and texture. Saturated hydraulic conductivity (Ksat) is considered in the design of soil drainage systems and septic tank absorption fields. Available water capacity refers to the quantity of water that the soil is capable of storing for use by plants. The capacity for water storage is given in inches of water per inch of soil for each soil layer. The capacity varies, depending on soil properties that affect retention of water. The most important properties are the content of organic matter, soil texture, bulk density, and soil structure. Available water capacity is an important factor in the choice of plants or crops to be grown and in the design and management of irrigation systems. Available water capacity is not an estimate of the quantity of water actually available to plants at any given time. Linear extensibility refers to the change in length of an unconfined clod as moisture content is decreased from a moist to a dry state. It is an expression of the volume change between the water content of the clod at 1/3- or 1/10-bar tension (33kPa or 10kPa tension) and oven dryness. The volume change is reported in the table as percent change for the whole soil. The amount and type of clay minerals in the soil influence volume change. Linear extensibility is used to determine the shrink-swell potential of soils. The shrink-swell potential is low if the soil has a linear extensibility of less than 3 percent; moderate if 3 to 6 percent; high if 6 to 9 percent; and very high if more than 9 percent. If the linear extensibility is more than 3, shrinking and swelling can cause damage to buildings, roads, and other structures and to plant roots. Special design commonly is needed. Organic matter is the plant and animal residue in the soil at various stages of decomposition. In this table, the estimated content of organic matter is expressed as a percentage, by weight, of the soil material that is less than 2 millimeters in diameter. The content of organic matter in a soil can be maintained by returning crop residue to the soil. Organic matter has a positive effect on available water capacity, water infiltration, soil organism activity, and tilth. It is a source of nitrogen and other nutrients for crops and soil organisms. Erosion factors are shown in the table as the K factor (Kw and Kf) and the T factor. Erosion factor K indicates the susceptibility of a soil to sheet and rill erosion by water. Factor K is one of six factors used in the Universal Soil Loss Equation (USLE) and the Revised Universal Soil Loss Equation (RUSLE) to predict the average annual rate of soil loss by sheet and rill erosion in tons per acre per year. The estimates are based primarily on percentage of silt, sand, and organic matter and on soil structure and Ksat. Values of K range from 0.02 to 0.69. Other factors being equal, the higher the value, the more susceptible the soil is to sheet and rill erosion by water. Erosion factor Kw indicates the erodibility of the whole soil. The estimates are modified by the presence of rock fragments. Erosion factor Kf indicates the erodibility of the fine-earth fraction, or the material less than 2 millimeters in size. Physical Soil Properties---Larimer County Area, Colorado Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 1/14/2020 Page 2 of 6 Erosion factor T is an estimate of the maximum average annual rate of soil erosion by wind and/or water that can occur without affecting crop productivity over a sustained period. The rate is in tons per acre per year. Wind erodibility groups are made up of soils that have similar properties affecting their susceptibility to wind erosion in cultivated areas. The soils assigned to group 1 are the most susceptible to wind erosion, and those assigned to group 8 are the least susceptible. The groups are described in the "National Soil Survey Handbook." Wind erodibility index is a numerical value indicating the susceptibility of soil to wind erosion, or the tons per acre per year that can be expected to be lost to wind erosion. There is a close correlation between wind erosion and the texture of the surface layer, the size and durability of surface clods, rock fragments, organic matter, and a calcareous reaction. Soil moisture and frozen soil layers also influence wind erosion. Reference: United States Department of Agriculture, Natural Resources Conservation Service. National soil survey handbook, title 430-VI. (http://soils.usda.gov) Physical Soil Properties---Larimer County Area, Colorado Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 1/14/2020 Page 3 of 6 Report—Physical Soil Properties Three values are provided to identify the expected Low (L), Representative Value (R), and High (H). Physical Soil Properties–Larimer County Area, Colorado Map symbol and soil name Depth Sand Silt Clay Moist bulk density Saturated hydraulic conductivity Available water capacity Linear extensibility Organic matter Erosion factors Wind erodibility group Wind erodibility index Kw Kf T In Pct Pct Pct g/cc micro m/sec In/In Pct Pct 5—Aquepts, loamy Aquepts 0-60 ————4.23-364.61-70 5.00 ———5 22—Caruso clay loam, 0 to 1 percent slope Caruso 0-35 -35--34-27-31- 35 1.25-1.30 -1.35 0.42-0.92-1.41 0.18-0.20-0. 21 0.0- 1.5- 2.9 1.0- 1.5- 2.0 .32 .32 4 6 48 35-44 -64--27-5- 9- 13 1.35-1.43 -1.50 14.11-28.22-42. 34 0.06-0.10-0. 13 0.0- 1.5- 2.9 0.5- 0.8- 1.0 .32 .32 44-60 -97-- 2-0- 2- 3 1.45-1.53 -1.60 141.14-423.07- 705.00 0.02-0.03-0. 04 0.0- 1.5- 2.9 0.0- 0.3- 0.5 .02 .05 64—Loveland clay loam, 0 to 1 percent slopes Loveland 0-15 -33--32-30-35- 40 1.20-1.23 -1.25 1.41-2.82-4.23 0.18-0.19-0. 20 3.0- 4.5- 5.9 1.0- 2.0- 3.0 .20 .20 3 6 48 15-32 -35--38-18-27- 35 1.35-1.40 -1.45 4.23-9.17-14.11 0.18-0.19-0. 20 0.0- 1.5- 2.9 1.0- 1.5- 2.0 .32 .32 32-60 -96-- 2-0- 3- 5 1.55-1.60 -1.65 141.14-423.07- 705.00 0.03-0.05-0. 06 0.0- 1.5- 2.9 0.0- 0.3- 0.5 .02 .05 Physical Soil Properties---Larimer County Area, Colorado Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 1/14/2020 Page 4 of 6 Data Source Information Soil Survey Area: Larimer County Area, Colorado Survey Area Data: Version 14, Sep 13, 2019 Physical Soil Properties---Larimer County Area, Colorado Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 1/14/2020 Page 6 of 6 RUSLE2 Related Attributes This report summarizes those soil attributes used by the Revised Universal Soil Loss Equation Version 2 (RUSLE2) for the map units in the selected area. The report includes the map unit symbol, the component name, and the percent of the component in the map unit. Soil property data for each map unit component include the hydrologic soil group, erosion factor Kf for the surface horizon, erosion factor T, and the representative percentage of sand, silt, and clay in the mineral surface horizon. Missing surface data may indicate the presence of an organic layer. Report—RUSLE2 Related Attributes Soil properties and interpretations for erosion runoff calculations. The surface mineral horizon properties are displayed or the first mineral horizon below an organic surface horizon. Organic horizons are not displayed. RUSLE2 Related Attributes–Larimer County Area, Colorado Map symbol and soil name Pct. of map unit Slope length (ft) Hydrologic group Kf T factor Representative value % Sand % Silt % Clay 22—Caruso clay loam, 0 to 1 percent slope Caruso 85 —D .32 4 35.4 33.6 31.0 64—Loveland clay loam, 0 to 1 percent slopes Loveland 90 —C .20 3 33.3 31.7 35.0 81—Paoli fine sandy loam, 0 to 1 percent slopes Paoli 85 —A .15 5 65.4 19.6 15.0 103—Stoneham loam, 5 to 9 percent slopes Stoneham 85 —B .28 5 41.6 37.4 21.0 105—Table Mountain loam, 0 to 1 percent slopes Table Mountain 85 —B .37 5 44.3 40.7 15.0 Data Source Information Soil Survey Area: Larimer County Area, Colorado Survey Area Data: Version 14, Sep 13, 2019 RUSLE2 Related Attributes---Larimer County Area, Colorado Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 1/14/2020 Page 1 of 1 PROJECT SITE PROJECT SITE APPENDIX B H-25 Multi-Family – Fort Collins, CO 19059.02 FORT COLLINS STORMWATER CRITERIA MANUAL Hydrology Standards (Ch. 5) 2.0 Runoff Methodologies 3.1 Rational Formula Page 3 2.0 Runoff Methodologies There are two runoff analysis methodologies that are approved by the City: the Rational Method and the Stormwater Management Model (SWMM). In general, the chosen methodology should follow the basin size limitations listed in Table 2.0-1 below. SWMM must also be used to assess the performance of multiple detention basins in parallel or in series in a particular watershed. The City is the determining authority with respect to the appropriate methodology to use under uncertain circumstances. Please note that the Colorado Urban Hydrograph Procedure (CUHP) is not allowed to be utilized for hydrology analysis for Fort Collins area projects because this procedure is calibrated using Denver/Boulder rainfall data. Table 2.0-1: Runoff Calculation Method Project Size Runoff Calculation Method < 5 acres Rational Method Required 5-20 acres Rational Method or SWMM Accepted ≥ 20 acres SWMM Required Reference: Drainage Report submittal requirements must be prepared in accordance with the criteria set forth in Chapter 2: Development Submittal Requirements. 3.0 Rational Method 3.1 Rational Formula The methodology and theory behind the Rational Method is not covered in this Manual as this subject is well described in many hydrology reference books. However, the Rational Method procedure is generally provided in the following sections. Runoff coefficient calculations, rainfall data, and the time of concentration formula are specific to the City and are included below. The Rational Formula is represented by the following equation: 𝐐𝐐=𝐂𝐂𝐂𝐂𝐂𝐂 Equation 5-1 Where: Q = Peak Rate of Runoff, cfs C = Runoff Coefficient, dimensionless I = Rainfall Intensity, in/hr A = Area of the Basin or Sub-basin, acres FORT COLLINS STORMWATER CRITERIA MANUAL Hydrology Standards (Ch. 5) 3.0 Rational Method 3.2 Runoff Coefficients Page 4 3.2 Runoff Coefficients Runoff coefficients used for the Rational Method are determined based on either overall land use or surface type across the drainage area. For Overall Drainage Plan (ODP) submittals, when surface types may not yet be known, land use shall be used to estimate flow rates and volumes. Table 3.2-1 lists the runoff coefficients for common types of land uses in the City. Table 3.2-1. Zoning Classification - Runoff Coefficients Land Use Runoff Coefficient (C) Residential Urban Estate 0.30 Low Density 0.55 Medium Density 0.65 High Density 0.85 Commercial Commercial 0.85 Industrial 0.95 Undeveloped Open Lands, Transition 0.20 Greenbelts, Agriculture 0.20 Reference: For further guidance regarding zoning classifications, refer to the Land Use Code, Article 4. For a Project Development Plan (PDP) or Final Plan (FP) submittals, runoff coefficients must be based on the proposed land surface types. Since the actual runoff coefficients may be different from those specified in Table 3.2-1, Table 3.2-2 lists coefficients for the specific types of land surfaces. FORT COLLINS STORMWATER CRITERIA MANUAL Hydrology Standards (Ch. 5) 3.0 Rational Method 3.2 Runoff Coefficients Page 5 Table 3.2-2. Surface Type - Runoff Coefficients Surface Type Runoff Coefficients Hardscape or Hard Surface Asphalt, Concrete 0.95 Rooftop 0.95 Recycled Asphalt 0.80 Gravel 0.50 Pavers 0.50 Landscape or Pervious Surface Lawns, Sandy Soil, Flat Slope < 2% 0.10 Lawns, Sandy Soil, Avg Slope 2-7% 0.15 Lawns, Sandy Soil, Steep Slope >7% 0.20 Lawns, Clayey Soil, Flat Slope < 2% 0.20 Lawns, Clayey Soil, Avg Slope 2-7% 0.25 Lawns, Clayey Soil, Steep Slope >7% 0.35 3.2.1 Composite Runoff Coefficients Drainage sub-basins are frequently composed of land that has multiple surface types or zoning classifications. In such cases a composite runoff coefficient must be calculated for any given drainage sub-basin. The composite runoff coefficient is obtained using the following formula: ( ) t n i ii A xAC C ∑ ==1 Equation 5-2 Where: C = Composite Runoff Coefficient Ci = Runoff Coefficient for Specific Area (Ai), dimensionless Ai = Area of Surface with Runoff Coefficient of Ci, acres or square feet n = Number of different surfaces to be considered At = Total Area over which C is applicable, acres or square feet 3.2.2 Runoff Coefficient Frequency Adjustment Factor The runoff coefficients provided in Table 3.2-1 and Table 3.2-2 are appropriate for use with the 2-year storm event. For any analysis of storms with higher intensities, an adjustment of the runoff coefficient is required due to the lessening amount of infiltration, depression retention, evapotranspiration and other losses that have a proportionally smaller effect on high-intensity storm runoff. This adjustment is FORT COLLINS STORMWATER CRITERIA MANUAL Hydrology Standards (Ch. 5) 3.0 Rational Method 3.3 Time of Concentration Page 6 applied to the composite runoff coefficient. These frequency adjustment factors, Cf, are found in Table 3.2-3. Table 3.2-3. Frequency Adjustment Factors Storm Return Period (years) Frequency Adjustment Factor (Cf) 2, 5, 10 1.00 25 1.10 50 1.20 100 1.25 3.3 Time of Concentration 3.3.1 Overall Equation The next step to approximate runoff using the Rational Method is to estimate the Time of Concentration, Tc, or the time for water to flow from the most remote part of the drainage sub-basin to the design point under consideration. The Time of Concentration is represented by the following equation: 𝐓𝐓𝐜𝐜=𝐓𝐓𝐢𝐢+𝐓𝐓𝐭𝐭 Equation 5-3 Where: Tc = Total Time of Concentration, minutes Ti = Initial or Overland Flow Time of Concentration, minutes Tt = Channelized Flow in Swale, Gutter or Pipe, minutes 3.3.2 Overland Flow Time Overland flow, Ti, can be determined by the following equation: 𝐓𝐓𝐢𝐢=𝟏𝟏.𝟖𝟖𝟖𝟖(𝟏𝟏.𝟏𝟏−𝐂𝐂𝐂𝐂𝐂𝐂𝐟𝐟)√𝐋𝐋√𝐒𝐒𝟑𝟑 Equation 3.3-2 Where: C = Runoff Coefficient, dimensionless Cf = Frequency Adjustment Factor, dimensionless L = Length of Overland Flow, feet S = Slope, percent CXCF PRODUCT OF CXCF CANNOT EXCEED THE VALUE OF 1 OVERLAND FLOW LENGTH L=200’ MAX IN DEVELOPED AREAS L=500’ MAX IN UNDEVELOPED AREAS FORT COLLINS STORMWATER CRITERIA MANUAL Hydrology Standards (Ch. 5) 3.0 Rational Method 3.4 Intensity-Duration-Frequency Curves for Rational Method Page 7 3.3.3 Channelized Flow Time Travel time in a swale, gutter or storm pipe is considered “channelized” or “concentrated” flow and can be estimated using the Manning’s Equation: 𝐕𝐕= 𝟏𝟏.𝟒𝟒𝟒𝟒𝐧𝐧 𝐑𝐑𝟐𝟐/𝟑𝟑𝐒𝐒𝟏𝟏/𝟐𝟐 Equation 5-4 Where: V = Velocity, feet/second n = Roughness Coefficient, dimensionless R = Hydraulic Radius, feet (Hydraulic Radius = area / wetted perimeter, feet) S = Longitudinal Slope, feet/feet And: 𝐓𝐓𝐭𝐭=𝐋𝐋𝐕𝐕𝐂𝐂𝐕𝐕𝐕𝐕 Equation 5-5 3.3.4 Total Time of Concentration A minimum Tc of 5 minutes is required. The maximum Tc allowed for the most upstream design point shall be calculated using the following equation: 𝐓𝐓𝐜𝐜=𝐋𝐋𝟏𝟏𝟖𝟖𝐕𝐕+𝟏𝟏𝐕𝐕 Equation 3.3-5 The Total Time of Concentration, Tc, is the lesser of the values of Tc calculated using Tc = Ti + Tt or the equation listed above. 3.4 Intensity-Duration-Frequency Curves for Rational Method The two-hour rainfall Intensity-Duration-Frequency curves for use with the Rational Method is provided in Table 3.4-1 and Figure 3.4-1. TC • A MINIMUM TC OF 5 MINUTES IS REQUIRED IN ALL CASES. • A MAXIMUM TC OF 5 MINUTES IS TYPICAL FOR SMALLER, URBAN PROJECTS. FORT COLLINS STORMWATER CRITERIA MANUAL Hydrology Standards (Ch. 5) 3.0 Rational Method 3.4 Intensity-Duration-Frequency Curves for Rational Method Page 8 Table 3.4-1. IDF Table for Rational Method Duration (min) Intensity 2-year (in/hr) Intensity 10-year (in/hr) Intensity 100-year (in/hr) Duration (min) Intensity 2-year (in/hr) Intensity 10-year (in/hr) Intensity 100-year (in/hr) 5 2.85 4.87 9.95 39 1.09 1.86 3.8 6 2.67 4.56 9.31 40 1.07 1.83 3.74 7 2.52 4.31 8.80 41 1.05 1.80 3.68 8 2.40 4.10 8.38 42 1.04 1.77 3.62 9 2.30 3.93 8.03 43 1.02 1.74 3.56 10 2.21 3.78 7.72 44 1.01 1.72 3.51 11 2.13 3.63 7.42 45 0.99 1.69 3.46 12 2.05 3.50 7.16 46 0.98 1.67 3.41 13 1.98 3.39 6.92 47 0.96 1.64 3.36 14 1.92 3.29 6.71 48 0.95 1.62 3.31 15 1.87 3.19 6.52 49 0.94 1.6 3.27 16 1.81 3.08 6.30 50 0.92 1.58 3.23 17 1.75 2.99 6.10 51 0.91 1.56 3.18 18 1.70 2.90 5.92 52 0.9 1.54 3.14 19 1.65 2.82 5.75 53 0.89 1.52 3.10 20 1.61 2.74 5.60 54 0.88 1.50 3.07 21 1.56 2.67 5.46 55 0.87 1.48 3.03 22 1.53 2.61 5.32 56 0.86 1.47 2.99 23 1.49 2.55 5.20 57 0.85 1.45 2.96 24 1.46 2.49 5.09 58 0.84 1.43 2.92 25 1.43 2.44 4.98 59 0.83 1.42 2.89 26 1.4 2.39 4.87 60 0.82 1.4 2.86 27 1.37 2.34 4.78 65 0.78 1.32 2.71 28 1.34 2.29 4.69 70 0.73 1.25 2.59 29 1.32 2.25 4.60 75 0.70 1.19 2.48 30 1.30 2.21 4.52 80 0.66 1.14 2.38 31 1.27 2.16 4.42 85 0.64 1.09 2.29 32 1.24 2.12 4.33 90 0.61 1.05 2.21 33 1.22 2.08 4.24 95 0.58 1.01 2.13 34 1.19 2.04 4.16 100 0.56 0.97 2.06 35 1.17 2.00 4.08 105 0.54 0.94 2.00 36 1.15 1.96 4.01 110 0.52 0.91 1.94 37 1.16 1.93 3.93 115 0.51 0.88 1.88 38 1.11 1.89 3.87 120 0.49 0.86 1.84 FORT COLLINS STORMWATER CRITERIA MANUAL Hydrology Standards (Ch. 5) 3.0 Rational Method 3.4 Intensity-Duration-Frequency Curves for Rational Method Page 9 Figure 3.4-1. Rainfall IDF Curve – Fort Collins H-25 Multi FamilyFort Collins, ColoradoLAND USE AND IMPERVIOUSNESS4/6/202119059.02Surface TypeRunoff Coefficients% ImperviousAsphalt0.95100%2-Year Cf1.00Concrete 0.95 90%10-Year Cf1.00Rooftop0.9590%100-Year Cf1.25Gravel0.5040%Landscape < 2%0.102%Landscape 2-7%0.152%BASIN IMPERVIOUS CALCSBasins Conveying to On-Site Detention Basin to NorthTotal Area, A Total Area, A2-Year 10-Year 100-Year %Basin Description sf Acres Asphalt Rooftop Concrete Landscape Composite Composite Composite CompositeDesign PointArea (sf) Area (sf) Area (sf) Area (sf) Runoff Coefficient Runoff Coefficient Runoff Coefficient Impervious, I1 B-1 15,6820.366,344 3,886 1,510 3,851 92 0.74 0.74 0.9272%2 B-2 22,6510.527,053 5,501 1,024 9,073 0 0.61 0.61 0.7658%3 B-3 22,6800.5215,382 5,604 495 1,516 90 0.91 0.91 1.0092%4 B-4 40,0750.9223,671 5,081 8,198 1,419 1,706 0.90 0.88 1.0089%5 B-5 12,6320.298,200 2,500 1,200 642 90 0.90 0.90 1.0091%6 B-6 32,2340.7425,790 3,500 367 2,331 246 0.89 0.88 1.0091%7 B-7 22,4750.5212,356 3,208 635 6,276 0 0.71 0.71 0.8971%8 B-8 65,3401.5042,097 7,536 2,790 12,827 90 0.78 0.78 0.9879%9 B-9 35,4780.8116,985 10,483 5,042 2,968 0 0.88 0.88 1.0087%10 B-10 38,0390.876,406 6,856 4,062 20,715 0 0.49 0.49 0.6144%11 B-11 34,8480.8018,567 4,706 1,825 9,622 128 0.71 0.71 0.8971%12 B-12 9,5830.227,380 500 1,419 284 0 0.92 0.92 1.0095%13 B-13 3,9200.093,000 0 300 620 0 0.82 0.82 1.0084%14 B-14 18,2950.420 7,067 1,615 9,435 178 0.51 0.50 0.6344%15 B-15 19,6020.450 6,527 1,980 10,465 630 0.48 0.47 0.5840%16 B-16 15,9750.376,592 5,951 1,431 2,002 0 0.84 0.84 1.0083%17 B-17 3,3430.080 256 1,119 1,968 0 0.45 0.45 0.5638%18 B-18 13,9770.327,782 2,927 1,859 1,409 0 0.86 0.86 1.0087%O1 OS-1 16,5530.38697 3,113 804 11,939 0 0.34 0.34 0.4227%O2 OS-2 175,9824.040 7,500 1,500 165,275 1,707 0.15 0.14 0.186%O3 OS-3 128,5022.950 0 56 126,888 1,558 0.11 0.10 0.122%O4 OS-4 13,0680.300 5,240 1,392 4,731 1,705 0.58 0.52 0.6546%Gravel Area (sf)Fort Collins Rational Calculations_2-10-100-Yr.xlsx H-25 Multi FamilyFort Collins, Colorado4/6/202119059.02Note:Assumed C-value for flow over grassy surfaces is 0.25 (0.31 for 100-yr)Assumed C-value for flow over hard surfaces is 0.95 (1.00 for 100-yr)TIME OF CONCENTRATION CALCULATIONS INITIAL FLOW - TiCHANNELIZED FLOW - TtC*Cf C*Cf C*Cf INIT. INIT. Trvl 1 Trvl 1 Trvl 12-Yr Tc = 10-Yr Tc = 100-Yr Tc =BASIN Is Length 2-yr Cf= 10-yr Cf= 100-yr Cf= L1 S1 Ti 2-yr Ti 10-yr Ti 100-yr L 2 V T2 (2yr Ti +Tt) (10yr Ti +Tt) (100yr Ti +Tt)Design Point >200' ?Flow path material 1 1 1.25(ft) (%) (min) (min) (min) (ft) (f/s) (min) (min) (min) (min)1NO Hard Surface 2 0.95 0.95 1.00 114.00 2.1% 2.34 2.34 1.56 0 0 05.0 5.0 5.02NO Hard Surface 2 0.95 0.95 1.00 172.00 1.1% 3.55 3.55 2.36 0 0 05.0 5.0 5.03NO Hard Surface 2 0.95 0.95 1.00 175.00 1.9% 2.98 2.98 1.98 0 0 05.0 5.0 5.04NO Hard Surface 2 0.95 0.95 1.00 164.00 1.4% 3.23 3.23 2.15 0 0 05.0 5.0 5.05NO Landscape 1 0.25 0.25 0.31 200.00 0.8% 23.73 23.73 21.98 47.0 5.0 0.223.9 23.9 22.16NO Hard Surface 2 0.95 0.95 1.00 153.00 2.2% 2.68 2.68 1.78 0.0 0.0 0.05.0 5.0 5.07NO Hard Surface 2 0.95 0.95 1.00 200.00 1.5% 3.44 3.44 2.30 0.0 0.0 0.05.0 5.0 5.08NO Hard Surface 0.95 0.95 1.00 200.00 1.4% 3.54 3.54 2.36 0.0 0.0 0.05.0 5.0 5.09NO Hard Surface 0.95 0.95 1.00 138.00 1.4% 2.92 2.92 1.94 0.0 0.0 0.05.0 5.0 5.010NO Hard Surface 0.95 0.95 1.00 150.00 1.5% 2.97 2.97 1.98 0.0 0.0 0.05.0 5.0 5.011NO Hard Surface 0.95 0.95 1.00 88.00 3.2% 1.78 1.78 1.19 0.0 0.0 0.05.0 5.0 5.012NO Hard Surface 0.95 0.95 1.00 145.00 2.3% 2.57 2.57 1.71 0.0 0.0 0.05.0 5.0 5.013NO Hard Surface 0.95 0.95 1.00 200.00 1.5% 3.47 3.47 2.31 0.0 0.0 0.05.0 5.0 5.014NO Hard Surface 0.95 0.95 1.00 200.00 1.5% 3.49 3.49 2.33 0.0 0.0 0.05.0 5.0 5.015NO Hard Surface 0.95 0.95 1.00 127.00 1.5% 2.76 2.76 1.84 0.0 0.0 0.05.0 5.0 5.016NO Hard Surface 0.95 0.95 1.00 95.00 1.4% 2.47 2.47 1.65 0.0 0.0 0.05.0 5.0 5.017NO Hard Surface 0.95 0.95 1.00 60.00 0.8% 2.32 2.32 1.55 0.0 0.0 0.05.0 5.0 5.018NO Hard Surface 0.95 0.95 1.00 95.00 1.6% 2.32 2.32 1.55 0.0 0.0 0.05.0 5.0 5.0O1NO Hard Surface 0.95 0.95 1.00 94.00 2.8% 1.93 1.93 1.29 0.0 0.0 0.05.0 5.0 5.0O2NO Hard Surface 0.95 0.95 1.00 139.00 8.0% 1.65 1.65 1.10 0.0 0.0 0.05.0 5.0 5.0O3NO Landscape 0.25 0.25 0.31 200.00 0.5% 28.13 28.13 26.14 1246.0 3.9 5.433.5 33.5 31.5O4NOHard Surface0.950.951.0078.002.4%1.841.841.230.00.00.05.05.05.0TRVL 2Fort Collins Rational Calculations_2-10-100-Yr.xlsx H-25 Multi FamilyFort Collins, Colorado4/6/202119059.02PEAK FLOW CALCULATIONTypeAREA C2 C10 C100 2-Yr Tc* 10-Yr Tc* 100-Yr Tc* I 2 I 10 I 100 Q Q QBASIN2-yr 10-yr 100-yrDesign Point(acres) (min) (min) (min) (in/hr) (in/hr) (in/hr) (cfs) (cfs) (cfs)1B-10.360.740.740.925.05.05.02.854.879.950.761.303.312B-20.520.610.610.765.05.05.02.854.879.950.901.543.943B-30.520.910.911.005.05.05.02.854.879.951.352.305.184B-40.920.900.881.005.05.05.02.854.879.952.363.949.155B-50.290.900.901.0023.923.922.11.492.555.320.390.671.546B-60.740.890.881.005.05.05.02.854.879.951.873.187.367B-70.520.710.710.895.05.05.02.854.879.951.051.794.578B-81.500.780.780.985.05.05.02.854.879.953.355.7114.599B-90.810.880.881.005.05.05.02.854.879.952.043.498.1010B-100.870.490.490.615.05.05.02.854.879.951.212.075.2911B-110.800.710.710.895.05.05.02.854.879.951.632.777.0812B-120.220.920.921.005.05.05.02.854.879.950.580.992.1913B-130.090.820.821.005.05.05.02.854.879.950.210.360.9014B-140.420.510.500.635.05.05.02.854.879.950.611.032.6215B-150.450.480.470.585.05.05.02.854.879.950.621.022.6116B-160.370.840.841.005.05.05.02.854.879.950.881.513.6517B-170.080.450.450.565.05.05.02.854.879.950.100.170.4318B-180.320.860.861.005.05.05.02.854.879.950.791.353.19O1OS-10.380.340.340.425.05.05.02.854.879.950.360.621.59O2OS-24.040.150.140.185.05.05.02.854.879.951.702.807.16O3OS-32.950.110.100.1233.533.531.51.222.084.420.380.611.62O4OS-40.300.580.520.655.05.05.02.854.879.950.500.761.93* If time of concentration was less than 5 minutes, 5 minutes was used.Sub-basinIntensitiesBasin CharacteristicsFort Collins Rational Calculations_2-10-100-Yr.xlsx APPENDIX C H-25 Multi-Family – Fort Collins, CO 19059.02 Project: Inlet ID: Gutter Geometry (Enter data in the blue cells) Maximum Allowable Width for Spread Behind Curb TBACK =6.0 ft Side Slope Behind Curb (leave blank for no conveyance credit behind curb)SBACK =0.020 ft/ft Manning's Roughness Behind Curb (typically between 0.012 and 0.020)nBACK =0.015 Height of Curb at Gutter Flow Line HCURB =6.00 inches Distance from Curb Face to Street Crown TCROWN =27.0 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 =11.0 27.0 ft Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX =6.0 9.0 inches Check boxes are not applicable in SUMP conditions MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major Storm MAJOR STORM Allowable Capacity is based on Depth Criterion Qallow =SUMP SUMP cfs 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 = 4.2 8.0 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 Area Opening 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 (see USDCM Figure ST-5)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 = 0.369 0.689 ft Depth for Curb Opening Weir Equation dCurb = 0.18 0.50 ft Combination Inlet Performance Reduction Factor for Long Inlets RFCombination = 0.65 1.00 Curb Opening Performance Reduction Factor for Long Inlets RFCurb = 1.00 1.00 Grated Inlet Performance Reduction Factor for Long Inlets RFGrate = 0.65 1.00 MINOR MAJOR Total Inlet Interception Capacity (assumes clogged condition)Qa =1.3 6.1 cfs Inlet Capacity IS GOOD for Minor and Major Storms(>Q PEAK)Q PEAK REQUIRED =0.8 3.3 cfs Version 4.06 Released August 2018 ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm) (Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread) H25 Inlet 1 CDOT/Denver 13 Combination INLET IN A SUMP OR SAG LOCATION Version 4.06 Released August 2018 H-VertH-Curb W Lo (C) Lo (G) Wo W P CDOT/Denver 13 Combination Override Depths UD-Inlet_v4.06 (1).xlsm, Inlet 1 4/6/2021, 1:02 PM Project: Inlet ID: Gutter Geometry (Enter data in the blue cells) Maximum Allowable Width for Spread Behind Curb TBACK =6.0 ft Side Slope Behind Curb (leave blank for no conveyance credit behind curb)SBACK =0.020 ft/ft Manning's Roughness Behind Curb (typically between 0.012 and 0.020)nBACK =0.015 Height of Curb at Gutter Flow Line HCURB =6.00 inches Distance from Curb Face to Street Crown TCROWN =70.0 ft Gutter Width W =2.00 ft Street Transverse Slope SX =0.011 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 =35.0 70.0 ft Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX =6.0 9.0 inches Check boxes are not applicable in SUMP conditions MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major Storm MAJOR STORM Allowable Capacity is based on Depth Criterion Qallow =SUMP SUMP cfs 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 = 6.0 9.0 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 Area Opening 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 (see USDCM Figure ST-5)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 = 0.523 0.773 ft Depth for Curb Opening Weir Equation dCurb = 0.33 0.58 ft Combination Inlet Performance Reduction Factor for Long Inlets RFCombination = 0.94 1.00 Curb Opening Performance Reduction Factor for Long Inlets RFCurb = 1.00 1.00 Grated Inlet Performance Reduction Factor for Long Inlets RFGrate = 0.94 1.00 MINOR MAJOR Total Inlet Interception Capacity (assumes clogged condition)Qa =3.6 7.2 cfs Inlet Capacity IS GOOD for Minor and Major Storms(>Q PEAK)Q PEAK REQUIRED =0.9 3.9 cfs CDOT/Denver 13 Combination INLET IN A SUMP OR SAG LOCATION Version 4.06 Released August 2018 Version 4.06 Released August 2018 ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm) (Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread) H25 Inlet 2 H-VertH-Curb W Lo (C) Lo (G) Wo W P CDOT/Denver 13 Combination Override Depths UD-Inlet_v4.06 (1).xlsm, Inlet 2 4/6/2021, 1:02 PM Project: Inlet ID: Gutter Geometry (Enter data in the blue cells) Maximum Allowable Width for Spread Behind Curb TBACK =6.0 ft Side Slope Behind Curb (leave blank for no conveyance credit behind curb)SBACK =0.020 ft/ft Manning's Roughness Behind Curb (typically between 0.012 and 0.020)nBACK =0.015 Height of Curb at Gutter Flow Line HCURB =6.00 inches Distance from Curb Face to Street Crown TCROWN =40.0 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 =20.0 40.0 ft Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX =6.0 9.0 inches Check boxes are not applicable in SUMP conditions MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major Storm MAJOR STORM Allowable Capacity is based on Depth Criterion Qallow =SUMP SUMP cfs 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 = 6.0 9.0 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 Area Opening 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 (see USDCM Figure ST-5)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 = 0.523 0.773 ft Depth for Curb Opening Weir Equation dCurb = 0.33 0.58 ft Combination Inlet Performance Reduction Factor for Long Inlets RFCombination = 0.94 1.00 Curb Opening Performance Reduction Factor for Long Inlets RFCurb = 1.00 1.00 Grated Inlet Performance Reduction Factor for Long Inlets RFGrate = 0.94 1.00 MINOR MAJOR Total Inlet Interception Capacity (assumes clogged condition)Qa =3.6 7.2 cfs Inlet Capacity IS GOOD for Minor and Major Storms(>Q PEAK)Q PEAK REQUIRED =1.4 5.3 cfs CDOT/Denver 13 Combination INLET IN A SUMP OR SAG LOCATION Version 4.06 Released August 2018 Version 4.06 Released August 2018 ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm) (Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread) H25 Inlet 3 H-VertH-Curb W Lo (C) Lo (G) Wo W P CDOT/Denver 13 Combination Override Depths UD-Inlet_v4.06 (1).xlsm, Inlet 3 4/6/2021, 1:02 PM Project: Inlet ID: Gutter Geometry (Enter data in the blue cells) Maximum Allowable Width for Spread Behind Curb TBACK =6.0 ft Side Slope Behind Curb (leave blank for no conveyance credit behind curb)SBACK =0.020 ft/ft Manning's Roughness Behind Curb (typically between 0.012 and 0.020)nBACK =0.015 Height of Curb at Gutter Flow Line HCURB =6.00 inches Distance from Curb Face to Street Crown TCROWN =26.0 ft Warning 1 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 26.0 ft Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX =6.0 9.0 inches Check boxes are not applicable in SUMP conditions MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major Storm MAJOR STORM Allowable Capacity is based on Depth Criterion Qallow =SUMP SUMP cfs 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 = 2 2 Water Depth at Flowline (outside of local depression)Ponding Depth = 4.6 7.8 inches Grate Information MINOR MAJOR Length of a Unit Grate Lo (G) =6.00 6.00 feet Width of a Unit Grate Wo =1.73 1.73 feet Area Opening 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 (see USDCM Figure ST-5)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 = 0.409 0.669 ft Depth for Curb Opening Weir Equation dCurb = 0.22 0.48 ft Combination Inlet Performance Reduction Factor for Long Inlets RFCombination = 0.54 0.91 Curb Opening Performance Reduction Factor for Long Inlets RFCurb = 1.00 1.00 Grated Inlet Performance Reduction Factor for Long Inlets RFGrate = 0.44 0.73 MINOR MAJOR Total Inlet Interception Capacity (assumes clogged condition)Qa =3.1 12.5 cfs Inlet Capacity IS GOOD for Minor and Major Storms(>Q PEAK)Q PEAK REQUIRED =2.4 9.2 cfs CDOT/Denver 13 Combination INLET IN A SUMP OR SAG LOCATION Version 4.06 Released August 2018 Version 4.06 Released August 2018 ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm) (Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread) H25 Inlet 4 H-VertH-Curb W Lo (C) Lo (G) Wo W P CDOT/Denver 13 Combination Override Depths UD-Inlet_v4.06 (1).xlsm, Inlet 4 4/6/2021, 1:02 PM Project: Inlet ID: Gutter Geometry (Enter data in the blue cells) Maximum Allowable Width for Spread Behind Curb TBACK =6.0 ft Side Slope Behind Curb (leave blank for no conveyance credit behind curb)SBACK =0.020 ft/ft Manning's Roughness Behind Curb (typically between 0.012 and 0.020)nBACK =0.015 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 =0.050 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 24.0 ft Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX =6.0 9.0 inches Check boxes are not applicable in SUMP conditions MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major Storm MAJOR STORM Allowable Capacity is based on Depth Criterion Qallow =SUMP SUMP cfs 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 = 6.0 9.0 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 Area Opening 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 (see USDCM Figure ST-5)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 = 0.523 0.773 ft Depth for Curb Opening Weir Equation dCurb = 0.33 0.58 ft Combination Inlet Performance Reduction Factor for Long Inlets RFCombination = 0.94 1.00 Curb Opening Performance Reduction Factor for Long Inlets RFCurb = 1.00 1.00 Grated Inlet Performance Reduction Factor for Long Inlets RFGrate = 0.94 1.00 MINOR MAJOR Total Inlet Interception Capacity (assumes clogged condition)Qa =3.6 7.2 cfs Inlet Capacity IS GOOD for Minor and Major Storms(>Q PEAK)Q PEAK REQUIRED =0.4 1.5 cfs CDOT/Denver 13 Combination INLET IN A SUMP OR SAG LOCATION Version 4.06 Released August 2018 Version 4.06 Released August 2018 ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm) (Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread) H25 Inlet 5 H-VertH-Curb W Lo (C) Lo (G) Wo W P CDOT/Denver 13 Combination Override Depths UD-Inlet_v4.06 (1).xlsm, Inlet 5 4/6/2021, 1:02 PM Project: Inlet ID: Gutter Geometry (Enter data in the blue cells) Maximum Allowable Width for Spread Behind Curb TBACK =6.0 ft Side Slope Behind Curb (leave blank for no conveyance credit behind curb)SBACK =0.020 ft/ft Manning's Roughness Behind Curb (typically between 0.012 and 0.020)nBACK =0.015 Height of Curb at Gutter Flow Line HCURB =6.00 inches Distance from Curb Face to Street Crown TCROWN =30.0 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 =15.0 30.0 ft Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX =6.0 9.0 inches Check boxes are not applicable in SUMP conditions MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major Storm MAJOR STORM Allowable Capacity is based on Depth Criterion Qallow =SUMP SUMP cfs 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 = 2 2 Water Depth at Flowline (outside of local depression)Ponding Depth = 5.1 8.7 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 Area Opening 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 (see USDCM Figure ST-5)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 = 0.449 0.749 ft Depth for Curb Opening Weir Equation dCurb = 0.26 0.56 ft Combination Inlet Performance Reduction Factor for Long Inlets RFCombination = 0.60 1.00 Curb Opening Performance Reduction Factor for Long Inlets RFCurb = 1.00 1.00 Grated Inlet Performance Reduction Factor for Long Inlets RFGrate = 0.60 1.00 MINOR MAJOR Total Inlet Interception Capacity (assumes clogged condition)Qa =3.4 14.3 cfs Inlet Capacity IS GOOD for Minor and Major Storms(>Q PEAK)Q PEAK REQUIRED =1.9 7.4 cfs CDOT/Denver 13 Combination INLET IN A SUMP OR SAG LOCATION Version 4.06 Released August 2018 Version 4.06 Released August 2018 ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm) (Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread) H25 Inlet 6 H-VertH-Curb W Lo (C) Lo (G) Wo W P CDOT/Denver 13 Combination Override Depths UD-Inlet_v4.06 (1).xlsm, Inlet 6 4/6/2021, 1:02 PM Project: Inlet ID: Gutter Geometry (Enter data in the blue cells) Maximum Allowable Width for Spread Behind Curb TBACK =6.0 ft Side Slope Behind Curb (leave blank for no conveyance credit behind curb)SBACK =0.020 ft/ft Manning's Roughness Behind Curb (typically between 0.012 and 0.020)nBACK =0.015 Height of Curb at Gutter Flow Line HCURB =6.00 inches Distance from Curb Face to Street Crown TCROWN =50.0 ft Gutter Width W =2.00 ft Street Transverse Slope SX =0.024 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 =25.0 50.0 ft Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX =6.0 9.0 inches Check boxes are not applicable in SUMP conditions MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major Storm MAJOR STORM Allowable Capacity is based on Depth Criterion Qallow =SUMP SUMP cfs 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 = 6.0 9.0 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 Area Opening 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 (see USDCM Figure ST-5)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 = 0.523 0.773 ft Depth for Curb Opening Weir Equation dCurb = 0.33 0.58 ft Combination Inlet Performance Reduction Factor for Long Inlets RFCombination = 0.94 1.00 Curb Opening Performance Reduction Factor for Long Inlets RFCurb = 1.00 1.00 Grated Inlet Performance Reduction Factor for Long Inlets RFGrate = 0.94 1.00 MINOR MAJOR Total Inlet Interception Capacity (assumes clogged condition)Qa =3.6 7.2 cfs Inlet Capacity IS GOOD for Minor and Major Storms(>Q PEAK)Q PEAK REQUIRED =1.1 4.6 cfs CDOT/Denver 13 Combination INLET IN A SUMP OR SAG LOCATION Version 4.06 Released August 2018 Version 4.06 Released August 2018 ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm) (Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread) H25 Inlet 7 H-VertH-Curb W Lo (C) Lo (G) Wo W P CDOT/Denver 13 Combination Override Depths UD-Inlet_v4.06 (1).xlsm, Inlet 7 4/6/2021, 1:02 PM Project: Inlet ID: Gutter Geometry (Enter data in the blue cells) Maximum Allowable Width for Spread Behind Curb TBACK =12.0 ft Side Slope Behind Curb (leave blank for no conveyance credit behind curb)SBACK =0.020 ft/ft Manning's Roughness Behind Curb (typically between 0.012 and 0.020)nBACK =0.015 Height of Curb at Gutter Flow Line HCURB =6.00 inches Distance from Curb Face to Street Crown TCROWN =50.0 ft Gutter Width W =2.00 ft Street Transverse Slope SX =0.050 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 =25.0 50.0 ft Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX =6.0 9.0 inches Check boxes are not applicable in SUMP conditions MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major Storm MAJOR STORM Allowable Capacity is based on Depth Criterion Qallow =SUMP SUMP cfs 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 = 2 2 Water Depth at Flowline (outside of local depression)Ponding Depth = 6.0 9.0 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 Area Opening 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 (see USDCM Figure ST-5)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 = 0.523 0.773 ft Depth for Curb Opening Weir Equation dCurb = 0.33 0.58 ft Combination Inlet Performance Reduction Factor for Long Inlets RFCombination = 0.71 1.00 Curb Opening Performance Reduction Factor for Long Inlets RFCurb = 1.00 1.00 Grated Inlet Performance Reduction Factor for Long Inlets RFGrate = 0.71 1.00 MINOR MAJOR Total Inlet Interception Capacity (assumes clogged condition)Qa =5.3 15.1 cfs Inlet Capacity IS GOOD for Minor and Major Storms(>Q PEAK)Q PEAK REQUIRED =3.4 14.6 cfs CDOT/Denver 13 Combination INLET IN A SUMP OR SAG LOCATION Version 4.06 Released August 2018 Version 4.06 Released August 2018 ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm) (Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread) H25 Inlet 8 H-VertH-Curb W Lo (C) Lo (G) Wo W P CDOT/Denver 13 Combination Override Depths UD-Inlet_v4.06 (1).xlsm, Inlet 8 4/6/2021, 1:02 PM Project: Inlet ID: Gutter Geometry (Enter data in the blue cells) Maximum Allowable Width for Spread Behind Curb TBACK =9.0 ft Side Slope Behind Curb (leave blank for no conveyance credit behind curb)SBACK =0.020 ft/ft Manning's Roughness Behind Curb (typically between 0.012 and 0.020)nBACK =0.015 Height of Curb at Gutter Flow Line HCURB =6.00 inches Distance from Curb Face to Street Crown TCROWN =45.0 ft Gutter Width W =2.00 ft Street Transverse Slope SX =0.014 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 =20.0 45.0 ft Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX =6.0 9.0 inches Check boxes are not applicable in SUMP conditions MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major Storm MAJOR STORM Allowable Capacity is based on Depth Criterion Qallow =SUMP SUMP cfs 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 = 2 2 Water Depth at Flowline (outside of local depression)Ponding Depth = 5.0 9.0 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 Area Opening 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 (see USDCM Figure ST-5)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 = 0.441 0.773 ft Depth for Curb Opening Weir Equation dCurb = 0.25 0.58 ft Combination Inlet Performance Reduction Factor for Long Inlets RFCombination = 0.59 1.00 Curb Opening Performance Reduction Factor for Long Inlets RFCurb = 1.00 1.00 Grated Inlet Performance Reduction Factor for Long Inlets RFGrate = 0.59 1.00 MINOR MAJOR Total Inlet Interception Capacity (assumes clogged condition)Qa =3.2 15.1 cfs Inlet Capacity IS GOOD for Minor and Major Storms(>Q PEAK)Q PEAK REQUIRED =2.0 8.1 cfs Version 4.06 Released August 2018 ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm) (Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread) H25 Inlet 9 CDOT/Denver 13 Combination INLET IN A SUMP OR SAG LOCATION Version 4.06 Released August 2018 H-VertH-Curb W Lo (C) Lo (G) Wo W P CDOT/Denver 13 Combination Override Depths UD-Inlet_v4.06 (1).xlsm, Inlet 9 4/6/2021, 1:02 PM Project: Inlet ID: Gutter Geometry (Enter data in the blue cells) Maximum Allowable Width for Spread Behind Curb TBACK =6.0 ft Side Slope Behind Curb (leave blank for no conveyance credit behind curb)SBACK =0.020 ft/ft Manning's Roughness Behind Curb (typically between 0.012 and 0.020)nBACK =0.015 Height of Curb at Gutter Flow Line HCURB =6.00 inches Distance from Curb Face to Street Crown TCROWN =30.0 ft Gutter Width W =2.00 ft Street Transverse Slope SX =0.045 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 =15.0 30.0 ft Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX =6.0 9.0 inches Check boxes are not applicable in SUMP conditions MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major Storm MAJOR STORM Allowable Capacity is based on Depth Criterion Qallow =SUMP SUMP cfs 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 = 6.0 9.0 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 Area Opening 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 (see USDCM Figure ST-5)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 = 0.523 0.773 ft Depth for Curb Opening Weir Equation dCurb = 0.33 0.58 ft Combination Inlet Performance Reduction Factor for Long Inlets RFCombination = 0.94 1.00 Curb Opening Performance Reduction Factor for Long Inlets RFCurb = 1.00 1.00 Grated Inlet Performance Reduction Factor for Long Inlets RFGrate = 0.94 1.00 MINOR MAJOR Total Inlet Interception Capacity (assumes clogged condition)Qa =3.6 7.2 cfs Inlet Capacity IS GOOD for Minor and Major Storms(>Q PEAK)Q PEAK REQUIRED =1.2 5.3 cfs Version 4.06 Released August 2018 ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm) (Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread) H25 Inlet 10 CDOT/Denver 13 Combination INLET IN A SUMP OR SAG LOCATION Version 4.06 Released August 2018 H-VertH-Curb W Lo (C) Lo (G) Wo W P CDOT/Denver 13 Combination Override Depths UD-Inlet_v4.06 (1).xlsm, Inlet 10 4/6/2021, 1:02 PM Project: Inlet ID: Gutter Geometry (Enter data in the blue cells) Maximum Allowable Width for Spread Behind Curb TBACK =12.0 ft Side Slope Behind Curb (leave blank for no conveyance credit behind curb)SBACK =0.020 ft/ft Manning's Roughness Behind Curb (typically between 0.012 and 0.020)nBACK =0.015 Height of Curb at Gutter Flow Line HCURB =6.00 inches Distance from Curb Face to Street Crown TCROWN =40.0 ft Gutter Width W =2.00 ft Street Transverse Slope SX =0.050 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 =20.0 40.0 ft Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX =6.0 9.0 inches Check boxes are not applicable in SUMP conditions MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major Storm MAJOR STORM Allowable Capacity is based on Depth Criterion Qallow =SUMP SUMP cfs 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 = 6.0 9.0 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 Area Opening 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 (see USDCM Figure ST-5)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 = 0.523 0.773 ft Depth for Curb Opening Weir Equation dCurb = 0.33 0.58 ft Combination Inlet Performance Reduction Factor for Long Inlets RFCombination = 0.94 1.00 Curb Opening Performance Reduction Factor for Long Inlets RFCurb = 1.00 1.00 Grated Inlet Performance Reduction Factor for Long Inlets RFGrate = 0.94 1.00 MINOR MAJOR Total Inlet Interception Capacity (assumes clogged condition)Qa =3.6 7.2 cfs Inlet Capacity IS GOOD for Minor and Major Storms(>Q PEAK)Q PEAK REQUIRED =1.6 7.1 cfs Version 4.06 Released August 2018 ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm) (Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread) H25 Inlet 11 CDOT/Denver 13 Combination INLET IN A SUMP OR SAG LOCATION Version 4.06 Released August 2018 H-VertH-Curb W Lo (C) Lo (G) Wo W P CDOT/Denver 13 Combination Override Depths UD-Inlet_v4.06 (1).xlsm, Inlet 11 4/6/2021, 1:02 PM Project: Inlet ID: Gutter Geometry (Enter data in the blue cells) Maximum Allowable Width for Spread Behind Curb TBACK =6.0 ft Side Slope Behind Curb (leave blank for no conveyance credit behind curb)SBACK =0.020 ft/ft Manning's Roughness Behind Curb (typically between 0.012 and 0.020)nBACK =0.015 Height of Curb at Gutter Flow Line HCURB =6.00 inches Distance from Curb Face to Street Crown TCROWN =25.0 ft Gutter Width W =2.00 ft Street Transverse Slope SX =0.046 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 =11.0 20.0 ft Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX =6.0 9.0 inches Check boxes are not applicable in SUMP conditions MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major Storm MAJOR STORM Allowable Capacity is based on Depth Criterion Qallow =SUMP SUMP cfs 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 = 6.0 9.0 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 Area Opening 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 (see USDCM Figure ST-5)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 = 0.523 0.773 ft Depth for Curb Opening Weir Equation dCurb = 0.33 0.58 ft Combination Inlet Performance Reduction Factor for Long Inlets RFCombination = 0.94 1.00 Curb Opening Performance Reduction Factor for Long Inlets RFCurb = 1.00 1.00 Grated Inlet Performance Reduction Factor for Long Inlets RFGrate = 0.94 1.00 MINOR MAJOR Total Inlet Interception Capacity (assumes clogged condition)Qa =3.6 7.2 cfs Inlet Capacity IS GOOD for Minor and Major Storms(>Q PEAK)Q PEAK REQUIRED =0.6 2.2 cfs Version 4.06 Released August 2018 ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm) (Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread) H25 Inlet 12 CDOT/Denver 13 Combination INLET IN A SUMP OR SAG LOCATION Version 4.06 Released August 2018 H-VertH-Curb W Lo (C) Lo (G) Wo W P CDOT/Denver 13 Combination Override Depths UD-Inlet_v4.06 (1).xlsm, Inlet 12 4/6/2021, 1:02 PM Project: Inlet ID: Gutter Geometry (Enter data in the blue cells) Maximum Allowable Width for Spread Behind Curb TBACK =6.0 ft Side Slope Behind Curb (leave blank for no conveyance credit behind curb)SBACK =0.020 ft/ft Manning's Roughness Behind Curb (typically between 0.012 and 0.020)nBACK =0.015 Height of Curb at Gutter Flow Line HCURB =6.00 inches Distance from Curb Face to Street Crown TCROWN =30.0 ft Gutter Width W =2.00 ft Street Transverse Slope SX =0.040 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 =15.0 30.0 ft Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX =6.0 9.0 inches Check boxes are not applicable in SUMP conditions MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major Storm MAJOR STORM Allowable Capacity is based on Depth Criterion Qallow =SUMP SUMP cfs 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 = 6.0 9.0 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 Area Opening 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 (see USDCM Figure ST-5)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 = 0.523 0.773 ft Depth for Curb Opening Weir Equation dCurb = 0.33 0.58 ft Combination Inlet Performance Reduction Factor for Long Inlets RFCombination = 0.94 1.00 Curb Opening Performance Reduction Factor for Long Inlets RFCurb = 1.00 1.00 Grated Inlet Performance Reduction Factor for Long Inlets RFGrate = 0.94 1.00 MINOR MAJOR Total Inlet Interception Capacity (assumes clogged condition)Qa =3.6 7.2 cfs Inlet Capacity IS GOOD for Minor and Major Storms(>Q PEAK)Q PEAK REQUIRED =0.2 0.9 cfs Version 4.06 Released August 2018 ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm) (Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread) H25 Inlet 13 CDOT/Denver 13 Combination INLET IN A SUMP OR SAG LOCATION Version 4.06 Released August 2018 H-VertH-Curb W Lo (C) Lo (G) Wo W P CDOT/Denver 13 Combination Override Depths UD-Inlet_v4.06 (1).xlsm, Inlet 13 4/6/2021, 1:02 PM Project: Inlet ID: Gutter Geometry (Enter data in the blue cells) Maximum Allowable Width for Spread Behind Curb TBACK =6.0 ft Side Slope Behind Curb (leave blank for no conveyance credit behind curb)SBACK =0.020 ft/ft Manning's Roughness Behind Curb (typically between 0.012 and 0.020)nBACK =0.015 Height of Curb at Gutter Flow Line HCURB =6.00 inches Distance from Curb Face to Street Crown TCROWN =25.0 ft Gutter Width W =2.00 ft Street Transverse Slope SX =0.045 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 =11.0 20.0 ft Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX =6.0 9.0 inches Check boxes are not applicable in SUMP conditions MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major Storm MAJOR STORM Allowable Capacity is based on Depth Criterion Qallow =SUMP SUMP cfs 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 = 6.0 9.0 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 Area Opening 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) =N/A N/A feet Height of Vertical Curb Opening in Inches Hvert =N/A N/A inches Height of Curb Orifice Throat in Inches Hthroat =N/A N/A inches Angle of Throat (see USDCM Figure ST-5)Theta = N/A N/A degrees Side Width for Depression Pan (typically the gutter width of 2 feet)Wp =N/A N/A feet Clogging Factor for a Single Curb Opening (typical value 0.10)Cf (C) =N/A N/A Curb Opening Weir Coefficient (typical value 2.3-3.7)Cw (C) =N/A N/A Curb Opening Orifice Coefficient (typical value 0.60 - 0.70)Co (C) =N/A N/A Low Head Performance Reduction (Calculated)MINOR MAJOR Depth for Grate Midwidth dGrate = 0.523 0.773 ft Depth for Curb Opening Weir Equation dCurb = N/A N/A ft Combination Inlet Performance Reduction Factor for Long Inlets RFCombination = N/A N/A Curb Opening Performance Reduction Factor for Long Inlets RFCurb = N/A N/A Grated Inlet Performance Reduction Factor for Long Inlets RFGrate = 0.94 1.00 MINOR MAJOR Total Inlet Interception Capacity (assumes clogged condition)Qa =2.6 4.6 cfs Inlet Capacity IS GOOD for Minor and Major Storms(>Q PEAK)Q PEAK REQUIRED =0.9 3.7 cfs Version 4.06 Released August 2018 ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm) (Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread) H25 Inlet 17 CDOT/Denver 13 Valley Grate INLET IN A SUMP OR SAG LOCATION Version 4.06 Released August 2018 H-VertH-Curb W Lo (C) Lo (G) Wo W P CDOT/Denver 13 Valley Grate Override Depths UD-Inlet_v4.06 (1).xlsm, Inlet 17 4/6/2021, 1:02 PM Project: Inlet ID: Gutter Geometry (Enter data in the blue cells) Maximum Allowable Width for Spread Behind Curb TBACK =6.0 ft Side Slope Behind Curb (leave blank for no conveyance credit behind curb)SBACK =0.020 ft/ft Manning's Roughness Behind Curb (typically between 0.012 and 0.020)nBACK =0.015 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 =0.030 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 26.0 ft Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX =6.0 9.0 inches Check boxes are not applicable in SUMP conditions MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major Storm MAJOR STORM Allowable Capacity is based on Depth Criterion Qallow =SUMP SUMP cfs 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 = 6.0 9.0 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 Area Opening 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 (see USDCM Figure ST-5)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 = 0.519 0.773 ft Depth for Curb Opening Weir Equation dCurb = 0.33 0.58 ft Combination Inlet Performance Reduction Factor for Long Inlets RFCombination = 0.93 1.00 Curb Opening Performance Reduction Factor for Long Inlets RFCurb = 1.00 1.00 Grated Inlet Performance Reduction Factor for Long Inlets RFGrate = 0.93 1.00 MINOR MAJOR Total Inlet Interception Capacity (assumes clogged condition)Qa =3.5 7.2 cfs Inlet Capacity IS GOOD for Minor and Major Storms(>Q PEAK)Q PEAK REQUIRED =0.8 3.2 cfs Version 4.06 Released August 2018 ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm) (Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread) H25 Inlet 19 CDOT/Denver 13 Combination INLET IN A SUMP OR SAG LOCATION Version 4.06 Released August 2018 H-VertH-Curb W Lo (C) Lo (G) Wo W P CDOT/Denver 13 Combination Override Depths UD-Inlet_v4.06 (1).xlsm, Inlet 19 4/6/2021, 1:02 PM APPENDIX D H-25 Multi-Family – Fort Collins, CO 19059.02 APPENDIX E H-25 Multi-Family – Fort Collins, CO 19059.02 Harmony and I-25 ODP Drainage Report Page 4 Figure 2. Gravel Pit Information Harmony and I-25 ODP Drainage Report Page 6 Figure 3. Outfall to the Poudre River Historic stormwater runoff rates from this site have been calculated based upon the site as it was prior to mining activities. Harmony and I-25 ODP Drainage Report Page 7 3.0 Developed Conditions Plan 3.1 Design Criteria The overall drainage plan presented in this report has been developed in accordance with the City of Fort Collins Stormwater Criteria Manual and the City of Fort Collins submittal requirements for an ODP. The drainage plan presented is based upon the allowable developed stormwater release rates prescribed for the Poudre River drainage basin, that being the 2-year historic rate; and an integrated stormwater management program that will incorporate “Low Impact Development” (LID) principals into the design. The purpose of this developed condition analysis is basically to establish the maximum runoff rates from the “Limits of Development” within the ODP and to determine the 100-year detention volume required. The existing Weitzel Pits, now groundwater fed ponds, will be utilized as detention and water quality basins for stormwater runoff from this site. Specifically, the ponds shown as Ponds #1 and #2 in Figure 2, or as the area shown as the detention basin on the Grading and Drainage Plan, is the planned area for detention. Developed runoff analysis for the ODP is based on runoff coefficients for zoning classifications. For this project, the zoning classification is H-C (Harmony Corridor), and the minor storm runoff coefficient is 0.95, and 1.0 for the major storm. The allowable release from the ODP site is 9.8 cfs (2-yr historic release rate). The 100-year release from the undeveloped areas adjacent to the ODP site (east of the Limits of Development) is 57.2 cfs. This amount will be treated as a pass-through flow. The resulting amount of stormwater passing from the detention basin will be approximately 67 cfs (9.8 + 57.2). Stormwater release from the detention basin will need to be provided through a controlled release structure, likely to be a spillway that would need to be built below the historic ground surface so as not to fill in or affect the floodway. In addition, there is an offsite basin to the west of Strauss Cabin Road that currently drains via the Boxelder Ditch. A conveyance will be provided to this property to convey at least the 2-yr historic flows (allowed release after development) thru the ODP site. (100-year conveyance of this flow will be provided if development on that parcel does not occur first.) This flow will be considered a pass through flow and will be added to the allowed release from the detention pond. The required amount of stormwater detention for the full development of the land use parcels in the “Limits of Development” area is 16.2 ac-ft plus an additional 20% (City criteria), resulting in 19.4 ac-ft. The area of the Weitzel Pond #1 that is outside of the “Limits of Development” and Weitzel Pond #2 will constitute the detention basin for this project. The approximate water surface area for these two ponds combined is approximately 18 acres, resulting in approximately 1.1’ of stormwater storage depth above the groundwater elevation. The detention water surface elevation is still below the Base Flood Elevations as published on the current FEMA maps. APPENDIX F H-25 Multi-Family – Fort Collins, CO 19059.02 "New Filled Area"Blue area isapproved LOMR(Case #00-08-175B)Approved CLOMR-F(Case #00-08-182C)