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Home My WebLink AboutDrainage Reports - 09/30/2021Final Drainage Report Morningstar/Block 23 Fort Collins, Colorado April 29, 2021 Prepared for: Hazeldon/Morningstar Fort Collins, LLC 300 North Mason Street Fort Collins, Colorado 80524 Prepared by: 301 N. Howes Street Suite 100 Fort Collins, Colorado 80521 Phone: 970.221.4158 www.northernengineering.com Project Number: 1024-004 This Drainage Report is consciously provided as a PDF. Please consider the environment before printing this document in its entirety. When a hard copy is necessary, we recommend double-sided printing. City of Fort Collins Approved Plans Approved by: Date: April 29, 2021 City of Fort Collins Stormwater Utility 700 Wood Street Fort Collins, CO 80521 RE: Final Drainage Report for Morningstar/Block 23 Dear Staff: Northern Engineering is pleased to submit this Final Drainage Report for your review. This report accompanies the combined Final Plan submittal for the proposed Morningstar/Block 23. This report has been prepared in accordance with the Fort Collins Stormwater Criteria Manual (FCSCM) and serves to document the stormwater impacts associated with the proposed Morningstar/Block 23 project. We understand that review by the City of Fort Collins 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, Northern Engineering Services, Inc. Frederick S. Wegert, PE Project Engineer 4/29/2021 Final Drainage Report April 29, 2021 Morningstar/Block 23 Table of Contents Table of Contents I. General Location and Description ........................................................................ 1 II. Drainage Basins and Sub-Basins .......................................................................... 4 III. Drainage Design Criteria ..................................................................................... 5 IV. Conclusions ....................................................................................................... 16 V. References ......................................................................................................... 18 Tables and Figures Figure 1: Vicinity Map ...................................................................................... 1 Figure 2: Aerial Photograph ............................................................................ 2 Figure 3: City Floodplains................................................................................ 4 Table 1: Number of Chambers ........................................................................ 9 Table 2: East On-Site Drainage Characteristics ............................................ 14 Table 3: West On-Site Drainage Characteristics ........................................... 14 Table 4: Required Detention & Water Quality Volumes ................................ 15 Table 5: Designed Detention & Water Quality Volumes ................................ 15 Appendices Appendix A Hydrologic Computations Appendix B Hydraulic Computations Appendix C Water Quality/LID Design Computations Appendix D Erosion Control Report Appendix E USDA Soils Report Appendix F FEMA Firmette Map Pocket DR1 Drainage Exhibit Final Drainage Report April 29, 2021 Morningstar/Block 23 Page 1 of 20 I. General Location and Description A. Location 1. Vicinity Map 2. The Morningstar/Block 23 project site is located in the northeast quarter of Section 11, Township 7 North, Range 69 West of the 6th Principal Meridian, City of Fort Collins, County of Larimer, State of Colorado. 3. The project site (refer to Figure 1) is bordered to the north by Cherry Street; to the south by Maple Street; to the east by College Avenue; to the west by the Old Town Flats subdivision; and to the northwest by the Burlington Northern Railroad and the intersection of Cherry and Mason Streets. Figure 1: Vicinity Map Final Drainage Report April 29, 2021 Morningstar/Block 23 Page 2 of 20 4. bisecting the eastern half of the project site. B. Description of Property 1. The Morningstar/Block 23 project site is comprised of ±2.62 acres. 2. A north-south public alley bisects the property into an eastern parcel and a western parcel. The east half of the site is currently occupied by four abandoned commercial buildings as well as various concrete and gravel parking areas. The west half of the site is currently an undeveloped gravel lot. A portion of the gravel lot is used to stockpile material by Burlington Northern Railroad during maintenance activities for the railroad tracks. 1. The existing groundcover consists of weed-infested concrete and gravel parking lots with limited landscaping in the northeast corner. The project site generally drains from west to east across flat grades (e.g., <2.00%). 2. The west half, the alley, and portions of the east half of the existing runoff drains radially inward towards an existing storm inlet located onsite. The outer ring of the project site generally drains into the surrounding curb and gutter for Cherry Street, Maple Street, and College Avenue. The entire site, both the existing storm inlet and the surrounding streets, drain towards an existing Type-R inlet located Figure 2: Aerial Photograph Final Drainage Report April 29, 2021 Morningstar/Block 23 Page 3 of 20 within College Avenue in the northeast corner of the project. Ultimately, the Type-R inlet drains, via the Fort Collins storm sewer system, into the Cache La Poudre River ±1,160 feet to the north. 3. According to the United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) Soil Survey website: (http://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx), the site consists primarily of Paoli fine sandy loam (Hydrologic Soil Group A). 4. bisecting the eastern half of the project site. Old Town Flats, towards the southwest of the project, is the only significant off-site source of stormwater that impacts the project. The -R inlet in College Avenue located at the northeast corner of the project site, and it ultimately drains towards the Cache La Poudre River ±1,160 feet to the north. 5. The proposed development will consist of long-term care facility, commercial units, and a parking structure. The mixed-use building, consisting of long-term facility and commercial units, will be located east of the alley. The parking structure will be located west of the alley. Other proposed improvements include: a new asphalt within the alley, landscaping planters, new sidewalks within the surrounding streets, and storm sewer improvements in the alley, Cherry Street, and Maple Street. 6. The proposed land use is mixed-use. This is a permitted use in the Downtown District (D). Final Drainage Report April 29, 2021 Morningstar/Block 23 Page 4 of 20 C. Floodplain 1. The subject property is not located in a FEMA or City regulatory floodplain. In particular, the project site is not located within a FEMA designated 100-year floodplain per Map Number 08069C0979H (Effective date: May 2, 2012). II. Drainage Basins and Sub-Basins A. Major Basin Description Morningstar/Block 23 is located within the City of Fort Collins Old Town major drainage basin. Specifically, the project site is situated in the north-central portion of this major drainage basin. This basin is in north-central Fort Collins, and it has a drainage area of approximately 2,120 acres, including approximately 400 acres of the Colorado State University Campus. The Old Town major drainage basin generally drains from west to east. It receives some runoff from the Canal Importation basin directly west of Old Town. Most of the runoff form the Old Town major drainage basin drains into the Poudre River. B. Sub-Basin Description 1. The outfall for the project site is an existing Type-R inlet located in the northeast corner of the site within College Avenue. Figure 3: City Floodplains Final Drainage Report April 29, 2021 Morningstar/Block 23 Page 5 of 20 2. The existing site can be defined with fourteen (14) Sub-Basins that encompasses the entire project site. 3. The existing site runoff generally drains from west to east into an existing Type-R inlet in College Avenue. 4. Old Town Flats, towards the southwest of the project, is the only significant off- site source of stormwater that impacts the project. The outfall for Old Town Flats bisects the eastern half of Morningstar/Block 23 storm sewer discharging into a Type-R inlet in College Avenue located at the northeast corner of the project site. The developer will construct a new storm sewer to convey drainage from Morningstar/Block 23 and Old Town Flats along the alley, Cherry Street, and discharging into an existing single combination inlet at the intersection of Cherry Street and College Avenue. The combination inlet in Cherry Street will need to be reconstructed to accommodate the proposed pipe and site improvements. Drainage (the Type-R inlet in College Avenue) for Morningstar/Block 23 and Old Town Flats. 5. The onsite imperviousness, with tabulated historic versus proposed impervious areas, is documented within Appendix A. III. Drainage Design Criteria A. Optional Provisions There are no optional provisions outside of the FCSCM proposed with Morningstar/ Block 23. B. Stormwater Management Strategy The overall stormwater management strategy employed with Morningstar/Block 23 anization on receiving waters. The following is a description of how the proposed development has incorporated each step. Step 1 Employ Runoff Reduction Practices. The first consideration taken in trying to reduce the stormwater impacts of this development is the site selection itself. By choosing an already developed site with public storm sewer currently in place, the burden is significantly less than developing a vacant parcel absent of any infrastructure. Final Drainage Report April 29, 2021 Morningstar/Block 23 Page 6 of 20 The Morningstar/Block 23 aims to reduce runoff peaks, volumes and pollutant loads from frequently occurring storm events (i.e., water quality (i.e., 80th percentile) and 2-year storm events) by implementing Low Impact Development (LID) strategies. Wherever practical, runoff will be routed across landscaped areas, within rain gardens, or through an infiltration gallery. These LID practices reduce the overall amount of impervious area, while at the same time Minimizing Directly Connected Impervious Areas (MDCIA). The combined LID/MDCIA techniques will be implemented, where practical, throughout the development, thereby slowing runoff and increasing opportunities for infiltration. Step 2 Implement BMPs that Provide a Water Quality Capture Volume (WQCV) with Slow Release. The efforts taken in Step 1 will help to minimize excess runoff from frequently occurring storm events; however, urban development of this intensity will still have stormwater runoff leaving the site. The primary water quality treatment will occur in the underground vaults located along the alley. The underground vaults are located on private property per City of Fort Collins regulations. Step 3 Stabilize Drainageways. While this step may not seem applicable to Morningstar/Block 23, the proposed project indirectly helps achieve stabilized drainageways, nonetheless. Once again, site selection has a positive effect on stream stabilization. By developing an infill site with existing stormwater infrastructure, combined with LID and MDCIA strategies, the likelihood of bed and bank erosion is reduced. Furthermore, this project will pay one-time stormwater development fees, as well as ongoing monthly stormwater utility fees, both of which help achieve Citywide drainageway stability. Step 4 Implement Site Specific and Other Source Control BMPs. This step typically applies to industrial and commercial developments. C. Development Criteria Reference and Constraints 1. The subject property is not part of any Overall Development Plan (ODP) development 2. The site plan is constrained on all sides by either a public street, a railroad, or existing development. The northeast corner of the project site is the intersection of College Avenue and Cherry Street. This intersection includes a level railway junction between the Burlington Northern Railroad, Great Western Railroad, and US Highway 287. The southeast corner of the project is the junction of US Highway 287 and Colorado State Highway 14. 3. The existing inlets in College Avenue (a combination and a Type-R inlet) will function as the ultimate outfall for the project site. Final Drainage Report April 29, 2021 Morningstar/Block 23 Page 7 of 20 D. 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 Morningstar/Block 23 development. Tabulated data contained in Table 3.4-1 has been utilized for Rational Method runoff calculations. 2. The Rational Method has been employed to compute stormwater runoff utilizing coefficients contained in Tables 3.2.1 and 3.2.2 of the FCSCM. 3. The Rational Formula-based Federal Aviation Administration (FAA) procedure was utilized for detention storage calculations. 4. Two separate design storms have been utilized to address distinct drainage scenarios. a 2-year recurrence interval. The second which has a 100-year recurrence interval. E. Hydraulic Criteria 1. The drainage facilities proposed with Morningstar/Block 23 project are designed in accordance with criteria outlined in the FCSCM and/or the Urban Drainage Urban Drainage Flood Control District recently changed their name to Mile High Flood District (MHFD). 2. As stated in Section I.C.1, above, the subject property is not located within a FEMA or City floodplain limits. F. Floodplain Regulations Compliance 1. The project is located outside of a FEMA or City floodplain, and as such, it will not be subject to any floodplain regulations. 2. Despite the project not being located within the floodplain, consideration has been given to the floodplain elevations as they relate to the proposed buildings and the finished floors have been elevated accordingly. G. Modifications of Criteria No formal modifications are requested at this time. Final Drainage Report April 29, 2021 Morningstar/Block 23 Page 8 of 20 H. Conformance with Water Quality Treatment Criteria City Code requires that 100% of runoff from a project site receive some sort of water quality treatment. This project proposes to provide water quality treatment through the use of an underground infiltration gallery (aka underground chambers) located midway on the east side of the alley, a sand filter and detention vault within the parking structure, and planter boxes constructed to provide the City of Fort Collins biomedia soil section. The chambers, sand filter vault, and biomedia planter boxes are considered a LID treatment method. Due to the physical constraints associated with an infill project of this nature and the prohibition of providing water quality facilities within the public right-of-way, there are some small, narrow areas around the perimeter of the project that cannot be captured. The uncaptured areas tend to be narrow strips of concrete flatwork that link the building entrances to the public sidewalks and small planter beds between the building and public sidewalks or property lines. I. Conformance with Low Impact Development (LID) The project site will conform with the requirement to treat a minimum of 75% of the project site using a LID technique. Please see Appendix C for LID design information, table, and exhibit(s). As shown in the LID table provided in the appendix, 89.0% of the proposed site impervious area will receive LID treatment, which exceeds the minimum required. J. Sizing of LID Facilities Infiltration Gallery & Planter Boxes 1. The infiltration gallery was sized by first determining the required water quality capture volume (WQCV) for Basins E1 - E5. A 12-hour drain time was used in this calculation. 2. The WQCV for the infiltration gallery was then reduced by the available volume in the planter boxes. The WQCV was calculated to be 2,035 cubic feet for the east side improvements. Per FCSM requirements for rain gardens, the planter boxes will be capable of treating a WQCV of 690 cubic feet to a depth of 1 foot. Therefore, the minimum required WQCV within the infiltration gallery is 1,345 cubic feet (2,035 ft3 690 ft3 = 1,345 ft3). 3. Once the WQCV was identified, the minimum number of vaults needed to achieve the minimum WQCV was calculated. This volume includes the adjacent aggregates 4. The total release rate for the underground vaults wrapped in geofabric, with the potential to constrict flows and resulting in sedimentation, was calculated to be Final Drainage Report April 29, 2021 Morningstar/Block 23 Page 9 of 20 0.42 cfs. This rate was determined by multiplying the vault bottom square footage x 0.35 gpm. 5. After completing the volume calculated utilizing the WQ flow rate into the chamber and the calculated release rate through the fabric, the number of chambers was increased as needed to confirm the resulting WQCV is provided within the empty volume of the underground chambers. This is intended to ensure the chambers do not become overwhelmed in the water quality storm gregates. 6. Finally, additional chambers, without fabric, were added to provide the required detention volume for the east side of the project. Number of Chambers Type of Chamber # of Chambers Volume (ft3) Infiltrator Row SC-740 18 1,348 Detention SC-740 12 899 Total 30 2,247 Required Chamber Volume 2,067 Table 1: Number of Chambers Sand Filter Vault 1. The sand filter vault was sized by first determining the required water quality capture volume (WQCV) for the parking garage footprint (Basin W2) assuming 100% imperviousness. A 12-hour drain time was used in this calculation. K. General Concept 1. The main objective of Morningstar/Block 23 drainage design is to maintain existing drainage patterns, while not adversely impacting adjacent properties. 2. The outfall for Old Town Flats passes through the project site. This outfall will be re-routed, along with stormwater from Morningstar/Block 23, into a new storm sewer within the alley and Cherry Street, and it will discharge into an existing single combination inlet at the intersection of Cherry Street and College historic outfall (the Type-R inlet in College Avenue) for Morningstar/Block 23 and Old Town Flats. The combination inlet at the intersection of Cherry Street and College Avenue, and the existing storm sewer, will be replaced to accommodate the increased flows. Final Drainage Report April 29, 2021 Morningstar/Block 23 Page 10 of 20 3. A list of tables and figures used within this report can be found in the Table of Contents at the front of the document. The tables and figures are located within the sections to which the content best applies. 4. Drainage for the project site has been analyzed using fourteen (16) drainage Sub- Basins, designated as Sub-Basins A1, A2, A3, B1, B2, C1, C2, E1 E5, and W1 W4. The drainage patterns anticipated for the basins are further described below. Sub-Basin A1 Sub-Basin A1 consists the right-of-way improvements along Cherry Street and at the intersection of Cherry Street and College Avenue. This sub-basin is comprised primarily of concrete flatwork and limited landscaped areas. The sub- basin will drain into the curb and gutter along Cherry Street and be captured by existing inlets at the intersection of Cherry Street and College Avenue. Flows will then proceed to Cache La Poudre River via Fort Collins storm sewer system. This basin is contained entirely within the Cherry Street and College Avenue rights-of-way. Sub-Basin A2 Sub-Basin A2 consists the right-of-way improvements along College Avenue. This sub-basin is comprised primarily of concrete flatwork and limited landscaped areas. The sub-basin will drain into the curb and gutter along College Avenue and be captured by existing inlets at the intersection of Maple Street and College Avenue. Flows will then proceed to Cache La Poudre River via Fort Collins storm sewer system. This basin is contained entirely within the College Avenue right-of-way. Sub-Basin A3 Sub-Basin A3 consists the right-of-way improvements along Maple Street. This sub-basin is comprised primarily of concrete flatwork and limited landscaped areas. The sub-basin will drain into the curb and gutter along Maple Street and be captured by a proposed inlet at the intersection of Maple Street and College Avenue. Flows will then proceed to Cache La Poudre River via Fort Collins storm sewer system. This basin is contained entirely within the College Avenue right-of-way. Sub-Basin B1 Sub-Basin B1 consists the right-of-way improvements along Cherry Street north of the parking garage and the north entrance to the alley. This sub-basin is comprised primarily of concrete flatwork and limited landscaped areas. The sub-basin will drain into the curb and gutter along Cherry Street. Flows will be captured by the existing inlets at intersection of Cherry Street and College Avenue. Flows will then proceed to Cache La Poudre River via Fort Collins Final Drainage Report April 29, 2021 Morningstar/Block 23 Page 11 of 20 storm sewer system. This basin is contained entirely within the College Avenue right-of-way. Sub-Basin B2 Sub-Basin B2 consists of the alley. This sub-basin is comprised primarily of asphalt roadway and concrete sidewalks. Flows from the sub-basin will flow north to be captured by a proposed inlet midway along the east side of the alley. It will then be conveyed into the nearby underground chambers. The flows will then be directed within storm sewer pipes to the existing inlets at the intersection of Cherry Street and College Avenue. Flows will then proceed to Cache La Poudre River via Fort Collins storm sewer system. Sub-Basin C1 Sub-Basin C1 consists of the north courtyard. This sub-basin is comprised primarily of concrete sidewalks. Flows from the sub-basin will flow towards the underground chambers in Sub-Basin E4 via plumbing through the building. It will then be conveyed into the nearby underground chambers. The flows will then be directed via storm sewer to the intersection of Cherry Street and College Avenue. Flows will then proceed to Cache La Poudre River via Fort Collins storm sewer system. Sub-Basin C2 Sub-Basin C2 consists of the north courtyard. This sub-basin is comprised primarily of concrete sidewalks. Flows from the sub-basin will flow towards the underground chambers in Sub-Basin E4 via plumbing through the building. It will then be conveyed into the nearby underground chambers. The flows will then be directed via storm sewer to the intersection of Cherry Street and College Avenue. Flows will then proceed to Cache La Poudre River via Fort Collins storm sewer system. Sub-Basin E1 Sub-Basin E1 consists of the northeast corner of the project site. This sub-basin is comprised primarily of roof area and adjacent sidewalk within the project boundary. Some minor flows from the sidewalk will drain into Sub-Basin A1. Larger flows will be conveyed via roof downspouts and the building storm sewer system to a landscaping planters and underground chambers located midway on the east side of the alley. Major flows will then be directed within storm sewer pipes to the existing inlets at the intersection of Cherry Street and College Avenue. Flows will then proceed to Cache La Poudre River via Fort Collins storm sewer system. This basin is contained entirely within the project boundaries. Final Drainage Report April 29, 2021 Morningstar/Block 23 Page 12 of 20 Sub-Basin E2 Sub-Basin E2 consists of the eastern area of the east building. This sub-basin is comprised primarily of roof area and adjacent sidewalk within the project boundary. Some minor flows from the sidewalk will drain into Sub-Basin A2. Larger flows will be conveyed via roof downspouts and the building storm sewer system to a landscaping planters and underground chambers located midway on the east side of the alley. Major flows will then be directed within storm sewer pipes to the existing inlets at the intersection of Cherry Street and College Avenue. Flows will then proceed to Cache La Poudre River via Fort Collins storm sewer system. This basin is contained entirely within the project boundaries. Sub-Basin E3 Sub-Basin E3 consists of the southern area of the east building. This sub-basin is comprised primarily of roof area and adjacent sidewalk within the project boundary. Some minor flows from the sidewalk will drain into Sub-Basin A3. Larger flows will be conveyed via roof downspouts and the building storm sewer system to a landscaping planters and underground chambers located midway on the east side of the alley. Major flows will then be directed within storm sewer pipes to the existing inlets at the intersection of Cherry Street and College Avenue. Flows will then proceed to Cache La Poudre River via Fort Collins storm sewer system. This basin is contained entirely within the project boundaries. Sub-Basin E4 Sub-Basin E4 consists of the western area of the east building. This sub-basin is comprised primarily of roof area and adjacent sidewalk within the project boundary. Some minor flows from the sidewalk will drain into Sub-Basin B2. Larger flows will be conveyed via roof downspouts and the building storm sewer system to a landscaping planters and underground chambers located midway on the east side of the alley. Major flows will then be directed within storm sewer pipes to the existing inlets at the intersection of Cherry Street and College Avenue. Flows will then proceed to Cache La Poudre River via Fort Collins storm sewer system. This basin is contained entirely within the project boundaries. Sub-Basin E5 Sub-Basin E5 consists of the northwest corner of the east parcel. This sub-basin is comprised primarily of concrete flatwork and limited landscaping within the project boundary. The sub-basin will drain into the curb and gutter along Cherry Street via Sub-Basin B1. Flows will be captured by the existing inlets at intersection of Cherry Street and College Avenue. Flows will then proceed to Cache La Poudre River via Fort Collins storm sewer system. This basin in contained entirely within the College Avenue right-of-way. Final Drainage Report April 29, 2021 Morningstar/Block 23 Page 13 of 20 Sub-Basin OS1 Sub-Basin OS1 consists of Cherry Street between the Union Pacific Railroad tracks and Great Western Railway. This sub-basin is comprised primarily of concrete flatwork and asphalt. The sub-basin will drain into the curb and gutter along the north side of Cherry Street. Flows will be captured by the existing inlets at intersection of Cherry Street and College Avenue. Flows will then proceed to Cache La Poudre River via Fort Collins storm sewer system. This basin in contained entirely within the College Avenue right-of-way. Sub-Basin OS1 is provided to assist in sizing Storm Sewer A. Sub-Basin W1 Sub-Basin W1 consists of the landscaping and sidewalk northeast of the parking garage. This sub-basin is comprised primarily of concrete flatwork and limited landscaped areas. The sub-basin will drain into the curb and gutter along Cherry Street via Sub-Basin B1. Flows will be captured by the existing inlets at intersection of Cherry Street and College Avenue. Flows will then proceed to Cache La Poudre River via Fort Collins storm sewer system. This basin in contained entirely within the College Avenue right-of-way. Sub-Basin W2 Sub-Basin W2 consists of the parking garage. This sub-basin is comprised primarily of roof area and adjacent sidewalk within the project boundary. Some minor flows from the sidewalk will drain into Sub-Basin B2. Drainage will be conveyed via roof downspouts and the building storm sewer system to a sand filter and detention vault located on the west side of the parking garage (Basin W4). Drainage will then be directed within storm sewer pipes to the proposed storm sewer in the alley. The storm sewer will convey drainage north to Cherry Street, along Cherry Street, and to the existing inlets at the intersection of Cherry Street and College Avenue. Flows will then proceed to the Cache La Poudre River via Fort Collins storm sewer system. Sub-Basin W3 Sub-Basin W3 consists of landscaping and asphalt south and east of the parking garage. This Sub-Basin is comprised primarily of landscaping and asphalt within the project boundary. Flows will be conveyed surface drainage to the alley (Sub- Basin B1), and it will be collected by the storm sewer system in Sub-Basin B2. The storm sewer will convey drainage north to Cherry Street, along Cherry Street, and to the existing inlets at the intersection of Cherry Street and College Avenue. Flows will then proceed to the Cache La Poudre River via Fort Collins storm sewer system. Sub-Basin W4 Sub-Basin W4 consist of landscaped areas along the west edge of the parking garage. This Sub-Basin is comprised primarily of landscaping, a sand filter vault, Final Drainage Report April 29, 2021 Morningstar/Block 23 Page 14 of 20 and a detention vault for Sub-Basins W1, W3, and W4. Flows from the sand and detention vault the parking garage and towards the storm system in the alley. Flows will then proceed to Cache La Poudre River via Fort Collins storm sewer system. Some minor flows from the Sub-Basin will follow historic drainage patterns into the Burlington Northern Railroad; thence into the existing curb and gutter along Cherry Street; and finally captured by the existing inlets at the intersection of Cherry Street and College Avenue. All drainage basins maintain their historic outfall at the intersection of Cherry Street and College Avenue. A full-size copy of the Drainage Exhibit can be found in the Map Pocket at the end of this report. East On-Site Drainage Characteristics Existing Proposed Basin Area (ft2) 76,011 76,011 Impervious Area (ft2) 66,085 74,443 Percent Impervious 84% 90% 2-Year Flowrate (cfs) 3.57 2.32 10-Year Flowrate (cfs) 6.10 7.90 100-Year Flowrate (cfs) 14.62 17.40 Table 2: East On-Site Drainage Characteristics West On-Site Drainage Characteristics Existing Proposed Basin Area (ft2) 38,085 38,085 Impervious Area (ft2) 15,234 26,662 Percent Impervious 40% 76% 2-Year Flowrate (cfs) 0.79 0.86 10-Year Flowrate (cfs) 1.34 2.90 100-Year Flowrate (cfs) 3.42 7.30 Table 3: West On-Site Drainage Characteristics L. Specific Details 1. The developer will construct two onsite detention facilities for the project. An underground chamber system and planters will be used to provide the required detention storage, water quality, and LID treatment for the east half of the site. The planters will utilize the City of Fort Collins biomedia specifications for a rain garden to provide LID and water quality treatment. An isolator row, an underground chamber row wrapped in filter fabric, will provide additional water quality and LID treatment. The remaining underground chambers will provide the required detention volume. Final Drainage Report April 29, 2021 Morningstar/Block 23 Page 15 of 20 A chamber detention system will provide 1,348 ft3 of water quality treatment and 8299 ft3 of detention with a release rate of 14.64 cfs. The rain gardens will provide an additional 690 ft3 of water quality treatment. This results in a total of 2,937 ft3 of water quality and detention for the east half of the site. The required detention and water quality volume is 2,852 ft3. See sections IV.B.3 and IV.B.4, below, for further discussion on the release rate used to determine the required detention volumes. 2. A sand filter and detention vault system, located west of the parking garage, will provide the water quality and detention storage for the west half of the site. It will provide 1,215 ft3 of water quality treatment and 2,037 ft3 of detention with a release rate of 3.39 cfs. This results in a total of 3,252 ft3 of water quality and detention for the west half of the site. The required detention and water volume is 2,450 ft3. See sections IV.B.3 and IV.B.4, below, for further discussion on the release rate used to determine the required detention volumes. Required Detention and Water Quality Volumes Release Rate (cfs) Required Detention Volume (ft3) Required Water Quality Volume (ft3) East Parcel 14.64 817 2,035 West Parcel 3.42 1,384 1,066 Table 4: Required Detention & Water Quality Volumes Designed Detention and Water Quality Volumes Design Detention Volume (ft3) Design Water Quality Volume (ft3) East Rain Gardens 0 690 East Stormtech Chambers 899 1,348 Total East Side 899 2,038 West Detention Vault 2,037 0 West Sand Filter Vault 0 1,215 Total West Side 2,037 1,215 Table 5: Designed Detention & Water Quality Volumes 3. A total combined release rate of 14.64 cfs was determined for the proposed detention facilities on the east parcel. This release rate was determined based on the methodology utilized for previous projects in Fort Collins with a high historic impervious area (approved Final Drainage Reports for Scott Plaza and Union on Elizabeth ). The methodology accounts for impervious area allowed Final Drainage Report April 29, 2021 Morningstar/Block 23 Page 16 of 20 1.52 acres (66,085 ft2) of impervious area within the east half of the development site that drains towards the intersection of Cherry Street and College Avenue. A 100-year discharge from this impervious area was calculated to 14.62 cfs. There is 0.04 acres (1,863 ft2) of pervious area within the eastern half of the development site which also drains to the intersection of Cherry Street and College Avenue. A 2-year discharge from the pervious area of 0.02 cfs was calculated area discharge and the 2-year pervious area discharge is 14.64 cfs for the east half of the project site. The 14.64 cfs is considered as the allowable peak release rate for the eastern half of the site. 4. A similar methodology, as described above, was used for the west half (parking garage) side of the site. Because the west half of the site consists entirely of a gravel lot, there was no 2-year historic pervious area to calculate. There is 0.35 acres (15,234 ft2) of impervious area within the west half of the development site that drains towards the alley. A 100-year discharge from this impervious area was calculated to 3.42 cfs. The 3.42 cfs is considered as the allowable peak release rate for the western half of the site. Due to grading constraints along existing streets, portions of the west side are released undetained. Therefore, the release rate for the detention vault on the west side was throttled back to 3.39 cfs. 5. The FAA method was used to size the on-site detention volume. M. Sizing of LID Facilities Infiltration Gallery & Planter Boxes 6. The infiltration gallery was sized by first determining the required water quality capture volume (WQCV) for Basins E1 - E5. A 12-hour drain time was used in this calculation. 7. The WQCV for the infiltration gallery was then reduced by the available volume in the planter boxes. The WQCV was calculated to be 2,035 cubic feet for the east side improvements. Per FCSM requirements for rain gardens, the planter boxes will be capable of treating a WQCV of 690 cubic feet to a depth of 1 foot. Therefore, the minimum required WQCV within the infiltration gallery is 1,345 cubic feet (2,035 ft3 690 ft3 = 1,345 ft3). 8. Once the WQCV was identified, the minimum number of vaults needed to achieve the minimum WQCV was calculated. This volume includes the adjacent aggregates 9. The total release rate for the underground vaults wrapped in geofabric, with the potential to constrict flows and resulting in sedimentation, was calculated to be Final Drainage Report April 29, 2021 Morningstar/Block 23 Page 17 of 20 0.42 cfs. This rate was determined by multiplying the vault bottom square footage x 0.35 gpm. 10. After completing the volume calculated utilizing the WQ flow rate into the chamber and the calculated release rate through the fabric, the number of chambers was increased as needed to confirm the resulting WQCV is provided within the empty volume of the underground chambers. This is intended to ensure the chambers do not become overwhelmed in the water quality storm 11. Finally, additional chambers, without fabric, were added to provide the required detention volume for the east side of the project. Sand Filter Vault 12. The sand filter vault was sized by first determining the required water quality capture volume (WQCV) for the parking garage footprint (Basin W2) assuming 100% imperviousness. A 12-hour drain time was used in this calculation. IV. Conclusions A. Compliance with Standards 1. The design elements comply without variation and meet all LID requirements. 2. The drainage design proposed with Morningstar/Block 23 complies with the City of Fort Collins Master Drainage Plan for the Old Town Basin. 3. There are no FEMA regulatory floodplains associated with Morningstar/Block 23 development. 4. The drainage plan and stormwater management measures proposed with Morningstar/Block 23 project are compliant with all applicable State and Federal regulations governing stormwater discharge. B. Drainage Concept 1. The drainage design proposed with this project will effectively limit potential damage associated with its stormwater runoff. Morningstar/Block 23 will detain for existing pervious area converted to impervious areas at the 2-year existing release rate. Final Drainage Report April 29, 2021 Morningstar/Block 23 Page 18 of 20 V.References City of Fort Collins Landscape Design Guidelines for Stormwater and Detention Facilities, November 5, 2009, BHA Design, Inc. with City of Fort Collins Utility Services. Fort Collins Stormwater Criteria Manual, City of Fort Collins, Colorado, as adopted by Ordinance No. 159, 2018, and referenced in Section 26-500 of the City of Fort Collins Municipal Code. Soils Resource Report for Larimer County Area, Colorado, Natural Resources Conservation Service, United States Department of Agriculture. Urban Storm Drainage Criteria Manual, Volumes 1-3, Urban Drainage and Flood Control District, Wright-McLaughlin Engineers, Denver, Colorado, Revised April 2008. Appendix A Hydrologic Computations Project: Calc. By: Location: Date: Surface Area (SF)% Imperv.Imperv. Area (SF) Surface Area (SF)% Imperv.Imperv. Area (SF) Rooftop 19,291 100%19,291 Rooftop 0 100%0 Concrete 14,886 100%14,886 Concrete 0 100%0 Asphalt 26,532 100%26,532 Asphalt 0 100%0 Gravel 13,439 40%5,376 Gravel 38,085 40%15,234 Landscaping 1,863 0%0 Landscaping 0 0%0 Total 76,011 66,085 Total 38,085 15,234 Surface Area (SF)% Imperv.Imperv. Area (SF) Surface Area (SF)% Imperv.Imperv. Area (SF) Rooftop 56,647 100%56,647 Rooftop 26,308 100%26,308 Concrete 15,025 100%15,025 Concrete 1,283 100%1,283 Asphalt 2,356 100%2,356 Asphalt 0 100%0 Gravel 0 40% 0 Gravel 5,949 40% 2,380 Landscaping 1,983 0%0 Landscaping 4,545 0%0 Total 76,011 74,028 Total 38,085 29,971 7,943 14,737 Surface Area (SF)% Imperv.Imperv. Area (SF) Surface Area (SF)% Imperv.Imperv. Area (SF) Rooftop 19,291 100% 19,291 Rooftop 82,955 100% 82,955 Concrete 14,886 100% 14,886 Concrete 16,308 100% 16,308 Asphalt 26,532 100% 26,532 Asphalt 2,356 100% 2,356 Gravel 51,524 40% 20,610 Gravel 5,949 40% 2,380 Landscaping 1,863 0%0 Landscaping 6,528 0%0 Total 114,096 81,319 Total 114,096 103,999 22,680Additional Impervious Area (SF) Existing Developed Onsite Impervious Areas by Location to Alley Total Onsite Impervious Area Additional Impervious Area (SF) Additional Impervious Area (SF) Proposed Proposed Onsite Impervious Areas Impervious Area for East Side of Alley Impervious Area for West Side of Alley Impervious Area for West Side of AlleyImpervious Area for East Side of Alley Existing Existing Morningstar/Block 23 Fort Collins, Colorado F. Wegert 02/10/21 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 C2 C10 C100 I2 I10 I100 Q2 Q10 Q100 h-a1 H-A1 0.317 0.71 0.71 0.88 2.60 4.44 9.06 0.58 0.99 2.54 h-a2 H-A2 0.167 0.92 0.92 1.00 2.85 4.87 9.95 0.44 0.75 1.66 h-a3 H-A3 0.113 0.78 0.78 0.97 2.85 4.87 9.95 0.25 0.43 1.10 h-b4 H-B2 0.160 0.95 0.95 1.00 2.85 4.87 9.95 0.43 0.74 1.59 h-a1 H-E1 0.390 0.86 0.86 1.00 2.40 4.10 8.38 0.81 1.38 3.27 h-a3 H-E2 0.424 0.95 0.95 1.00 2.67 4.56 9.31 1.08 1.84 3.95 h-a5 H-E3 0.092 0.86 0.86 1.00 2.85 4.87 9.95 0.23 0.39 0.92 h-e4 H-E4 0.838 0.80 0.80 0.99 2.35 4.02 8.21 1.57 2.68 6.84 h-a1 H-W1 0.028 0.50 0.50 0.63 2.05 3.50 7.16 0.03 0.05 0.13 h-w2 H-W2 0.709 0.50 0.50 0.63 2.13 3.63 7.42 0.76 1.29 3.29 os1 OS1 0.698 0.95 0.95 1.00 2.85 4.87 9.95 1.89 3.23 6.95 h-b5 HW-Site 0.738 0.50 0.50 0.63 2.13 3.63 7.42 0.79 1.34 3.42 h-b5 HW-Imp 0.738 0.50 0.50 0.63 2.13 3.63 7.42 0.79 1.34 3.42 h-a1 HE-Site 1.745 0.85 0.85 1.00 2.40 4.10 8.38 3.57 6.10 14.62 h-a1 HE-Imp 1.702 0.87 0.87 1.00 2.46 4.21 8.59 3.64 6.22 14.62 h-a1 HE-Per 0.043 0.20 0.20 0.25 2.05 3.50 7.16 0.02 0.03 0.08 h-a1 Total 3.240 0.76 0.76 0.95 1.98 3.39 6.92 4.85 8.31 21.21 Intensity, I from Fig. 3.4.1 Fort Collins Stormwater Manual HISTORIC DIRECT RUNOFF COMPUTATIONS Intensity (in/hr) Flow (cfs) Morningstar/Block 23 F. Wegert December 16, 2020 Overland Flow, Time of Concentration: Project: Gutter/Swale Flow, Time of Concentration:Calculations By: Date:Tt = L / 60V (Equation 6-4 per MHFD) Tc = Ti + Tt (Equation 6-2 per MHFD) Combined Basins & Routed Basins Velocity (Swale Flow), V = 15·S Velocity (Gutter Flow), V = 20·S Rational Equation: Q = CiA (Equation 6-1 per MHFD) Design Point Basin Area (ac.) Runoff C (Equation 6-4 per (Equation 6-3 per Fort Collins Page 3 of 3 Tc2 Tc10 Tc100 C2 C10 C100 I2 (in/hr) I10 (in/hr) I100 (in/hr) QWQ (cfs) Q2 (cfs) Q10 (cfs) Q100 (cfs) a1 A1 0.229 6.34 6.34 5.51 0.62 0.62 0.77 2.67 4.56 9.31 0.19 0.4 0.6 1.6 a2 A2 0.285 5.00 5.00 5.00 0.81 0.81 1.00 2.85 4.87 9.95 0.33 0.7 1.1 2.8 a3 A3 0.287 5.00 5.00 5.00 0.88 0.88 1.00 2.85 4.87 9.95 0.36 0.7 1.2 2.9 b1 B1 0.088 5.00 5.00 5.00 0.64 0.64 0.80 2.85 4.87 9.95 0.08 0.2 0.3 0.7 b2 B2 0.161 5.00 5.00 5.00 0.93 0.93 1.00 2.85 4.87 9.95 0.21 0.4 0.7 1.6 c1 C1 0.085 5.00 5.00 5.00 0.95 0.95 1.00 2.85 4.87 9.95 0.11 0.2 0.4 0.8 c2 C2 0.113 5.00 5.00 5.00 0.95 0.95 1.00 2.85 4.87 9.95 0.15 0.3 0.5 1.1 e1 E1 0.398 5.48 5.48 5.00 0.91 0.91 1.00 2.85 4.87 9.95 0.51 1.0 1.8 4.0 e2 E2 0.309 5.37 5.37 5.00 0.95 0.95 1.00 2.85 4.87 9.95 0.42 0.8 1.4 3.1 e3 E3 0.213 5.00 5.00 5.00 0.95 0.95 1.00 2.85 4.87 9.95 0.29 0.6 1.0 2.1 e4 E4 0.615 7.82 7.82 5.51 0.93 0.93 1.00 2.46 4.21 8.59 0.70 1.4 2.4 5.3 e5 E5 0.012 5.00 5.00 5.00 0.95 0.95 1.00 2.85 4.87 9.95 0.02 0.0 0.1 0.1 w1 W1 0.010 7.47 7.47 7.22 0.15 0.15 0.18 2.52 4.31 8.80 0.00 0.0 0.0 0.0 w2 W2 0.612 5.00 5.00 5.00 0.95 0.95 1.00 2.85 4.87 9.95 0.83 1.7 2.8 6.1 w3 W3 0.048 5.00 5.00 5.00 0.27 0.27 0.34 2.85 4.87 9.95 0.02 0.0 0.1 0.2 w4 W4 0.068 7.26 7.26 7.12 0.10 0.10 0.13 2.52 4.31 8.80 0.01 0.0 0.0 0.1 os1 OS1 0.698 5.00 5.00 5.00 0.95 0.95 1.00 2.85 4.87 9.95 0.95 1.9 3.2 6.9 a1 Cherry 0.327 7.79 7.79 6.73 0.61 0.61 0.76 2.46 4.21 8.59 0.24 0.5 0.8 2.1 a2 College 0.285 5.00 5.00 5.00 0.81 0.81 1.00 2.85 4.87 9.95 0.33 0.7 1.1 2.8 a3 Maple 0.287 5.00 5.00 5.00 0.88 0.88 1.00 2.85 4.87 9.95 0.36 0.7 1.2 2.9 b2 Alley 0.823 5.00 5.00 5.00 0.89 0.89 1.00 2.85 4.87 9.95 1.04 2.1 3.6 8.2 a1 East 1.745 5.00 5.00 5.00 0.93 0.93 1.00 2.85 4.87 9.95 2.32 4.6 7.9 17.4 w2 West 0.738 5.26 5.26 5.00 0.82 0.82 1.00 2.85 4.87 9.95 0.86 1.7 2.9 7.3 a1 Total 3.532 5.00 5.00 5.00 0.87 0.87 1.00 2.85 4.87 9.95 4.35 8.7 14.9 35.1 Flow Combined Basins & Routed Basins DEVELOPED DIRECT RUNOFF COMPUTATIONS Intensity Morningstar/Block 23 F. Wegert December 16, 2020 Project: Calculations By: Overland Flow, Time of Concentration: Gutter/Swale Flow, Time of Concentration: Date: Rational Equation: Q = CiA (Equation 6-1 per MHFD) Design Point Basin Area (acres) Runoff CTc (Min) Velocity (Gutter Flow), V = 20·S ½ Velocity (Swale Flow), V = 15·S ½ Tt = L / 60V (Equation 6-4 per MHFD) Tc = Ti + Tt (Equation 6-2 per MHFD) Intensity, I from Fig. 3.4.1 Fort Collins Stormwater Manual (Equation 6-4 per MHFD) (Equation 6-3 per Fort Collins Stormwater Manual) } Page 3 of 3 Appendix B Hydraulic Calculations Area Inlet Performance Curve: Inlet A7-1 Governing Equations: At low flow depths, the inlet will act like a weir governed by the following equation: * where P = 2(L + W) * where H corresponds to the depth of water above the flowline At higher flow depths, the inlet will act like an orifice governed by the following equation: * where A equals the open area of the inlet grate * where H corresponds to the depth of water above the centroid of the cross-sectional area (A) The exact depth at which the inlet ceases to act like a weir, and begins to act like an orifice is unknown. However, what is known, is that the stage-discharge curves of the weir equation and the orifice equation will cross at a certain flow depth. The two curves can be found below: If H > 1.792 (A/P), then the grate operates like an orifice; otherwise it operates like a weir. Input Parameters: Type of Grate: FC Area Inlet Length of Grate (ft): 1.98 Width of Grate (ft): 1.35 Open Area of Grate (ft2):2.28 Flowline Elevation (ft): 4978.73 Allowable Capacity: 0.50 Depth vs. Flow: Depth Above Inlet (ft) Elevation (ft) Shallow Weir Flow (cfs) Orifice Flow (cfs) Actual Flow (cfs) 0.00 4978.73 0.00 0.00 0.00 0.10 4978.83 0.32 1.94 0.32 0.18 4978.91 0.76 2.60 0.76 <-10-Year 0.20 4978.93 0.89 2.74 0.89 0.30 4979.03 1.64 3.35 1.64 0.37 4979.10 2.25 3.72 2.25 <-100-Year 0.40 4979.13 2.53 3.87 2.53 0.50 4979.23 3.54 4.33 3.54 0.53 4979.26 3.86 4.46 3.86 <-Overflow 0.60 4979.33 4.65 4.74 4.65 0.80 4979.53 7.16 5.48 5.48 100-Year Design Flow = 2.24 cfs 10-Year Design Flow = 0.70 cfs 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 Di s c h a r g e ( c f s ) Stage (ft) Stage - Discharge Curves Weir Flow Orifice Flow 5.10.3 HPQ 5.0)2(67.0 gHAQ Will receive 100-year overflow from Inlet A10-1. Area Inlet Performance Curve: Inlet A10-1 Governing Equations: At low flow depths, the inlet will act like a weir governed by the following equation: * where P = 2(L + W) * where H corresponds to the depth of water above the flowline At higher flow depths, the inlet will act like an orifice governed by the following equation: * where A equals the open area of the inlet grate * where H corresponds to the depth of water above the centroid of the cross-sectional area (A) The exact depth at which the inlet ceases to act like a weir, and begins to act like an orifice is unknown. However, what is known, is that the stage-discharge curves of the weir equation and the orifice equation will cross at a certain flow depth. The two curves can be found below: If H > 1.792 (A/P), then the grate operates like an orifice; otherwise it operates like a weir. Input Parameters: Type of Grate: FC Area Inlet Length of Grate (ft): 1.98 Width of Grate (ft): 1.35 Open Area of Grate (ft2):2.28 Flowline Elevation (ft): 4979.07 Allowable Capacity: 0.50 Depth vs. Flow: Depth Above Inlet (ft) Elevation (ft) Shallow Weir Flow (cfs) Orifice Flow (cfs) Actual Flow (cfs) 0.00 4979.07 0.00 0.00 0.00 0.10 4979.17 0.32 1.94 0.32 0.18 4979.25 0.76 2.60 0.76 <-10-Year 0.20 4979.27 0.89 2.74 0.89 <-Overflow 0.29 4979.36 1.56 3.30 1.56 <-100-Year 0.30 4979.37 1.64 3.35 1.64 0.40 4979.47 2.53 3.87 2.53 0.50 4979.57 3.54 4.33 3.54 0.53 4979.60 3.86 4.46 3.86 0.60 4979.67 4.65 4.74 4.65 0.80 4979.87 7.16 5.48 5.48 100-Year Design Flow = 1.56 cfs 10-Year Design Flow = 0.70 cfs 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 Di s c h a r g e ( c f s ) Stage (ft) Stage - Discharge Curves Weir Flow Orifice Flow 5.10.3 HPQ 5.0)2(67.0 gHAQ 100-year will overflow into Inlet A7-1. Area Inlet Performance Curve: North Rain Garden Inlets (Basin A10-8) Governing Equations: At low flow depths, the inlet will act like a weir governed by the following equation: * where P = 3.1416*Dia.of grate * where H corresponds to the depth of water above the flowline At higher flow depths, the inlet will act like an orifice governed by the following equation: * where A equals the open area of the inlet grate * where H corresponds to the depth of water above the centroid of the cross-sectional area (A) The exact depth at which the inlet ceases to act like a weir, and begins to act like an orifice is unknown. However, what is known, is that the stage-discharge curves of the weir equation and the orifice equation will cross at a certain flow depth. The two curves can be found below: If H > 1.792 (A/P), then the grate operates like an orifice; otherwise it operates like a weir. Input Parameters: Type of Grate: Nyloplast 24" Dome Diameter of Grate (ft): 2 Open Area of Grate (ft2):1.88 Rim Elevation (ft): 4981.320 Reduction Factor: 50% Depth vs. Flow: Depth Above Inlet (ft) Elevation (ft) Shallow Weir Flow (cfs) Orifice Flow (cfs) Actual Flow (cfs) 0.00 4981.32 0.00 0.00 0.00 0.20 4981.52 0.84 2.27 0.84 0.28 4981.60 1.40 2.68 1.40 <-10-Year 0.30 4981.62 1.55 2.77 1.55 0.40 4981.72 2.38 3.20 2.38 0.47 4981.79 3.04 3.47 3.04 <-100-Year 0.60 4981.92 4.38 3.92 3.92 0.80 4982.12 6.74 4.53 4.53 1.00 4982.32 9.42 5.07 5.07 <-Overflow 1.20 4982.52 12.39 5.55 5.55 1.40 4982.72 15.61 5.99 5.99 100-Year Design Flow = 3.05 cfs 10-Year Design Flow = 1.35 cfs 5.10.3 HPQ 5.0)2(67.0 gHAQ 0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 Di s c h a r g e ( c f s ) Stage (ft) Stage - Discharge Curves Weir Flow Orifice Flow Two (2) inlets will be required for north rain garden. Calculations are for one inlet. Area Inlet Performance Curve: North Rain Garden Inlet (Basin A10-9) Governing Equations: At low flow depths, the inlet will act like a weir governed by the following equation: * where P = 3.1416*Dia.of grate * where H corresponds to the depth of water above the flowline At higher flow depths, the inlet will act like an orifice governed by the following equation: * where A equals the open area of the inlet grate * where H corresponds to the depth of water above the centroid of the cross-sectional area (A) The exact depth at which the inlet ceases to act like a weir, and begins to act like an orifice is unknown. However, what is known, is that the stage-discharge curves of the weir equation and the orifice equation will cross at a certain flow depth. The two curves can be found below: If H > 1.792 (A/P), then the grate operates like an orifice; otherwise it operates like a weir. Input Parameters: Type of Grate: Nyloplast 24" Dome Diameter of Grate (ft): 2 Open Area of Grate (ft2):1.88 Rim Elevation (ft): 4981.320 Reduction Factor: 50% Depth vs. Flow: Depth Above Inlet (ft) Elevation (ft) Shallow Weir Flow (cfs) Orifice Flow (cfs) Actual Flow (cfs) 0.00 4981.32 0.00 0.00 0.00 0.20 4981.52 0.84 2.27 0.84 0.28 4981.60 1.40 2.68 1.40 <-10-Year 0.30 4981.62 1.55 2.77 1.55 0.40 4981.72 2.38 3.20 2.38 0.47 4981.79 3.04 3.47 3.04 <-100-Year 0.60 4981.92 4.38 3.92 3.92 0.80 4982.12 6.74 4.53 4.53 1.00 4982.32 9.42 5.07 5.07 <-Overflow 1.20 4982.52 12.39 5.55 5.55 1.40 4982.72 15.61 5.99 5.99 100-Year Design Flow = 3.05 cfs 10-Year Design Flow = 1.35 cfs 5.10.3 HPQ 5.0)2(67.0 gHAQ 0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 Di s c h a r g e ( c f s ) Stage (ft) Stage - Discharge Curves Weir Flow Orifice Flow Two (2) inlets will be required for north rain garden. Calculations are for one inlet. Area Inlet Performance Curve: North Middle Rain Garden Inlet (Basin A10-6B) Governing Equations: At low flow depths, the inlet will act like a weir governed by the following equation: * where P = 3.1416*Dia.of grate * where H corresponds to the depth of water above the flowline At higher flow depths, the inlet will act like an orifice governed by the following equation: * where A equals the open area of the inlet grate * where H corresponds to the depth of water above the centroid of the cross-sectional area (A) The exact depth at which the inlet ceases to act like a weir, and begins to act like an orifice is unknown. However, what is known, is that the stage-discharge curves of the weir equation and the orifice equation will cross at a certain flow depth. The two curves can be found below: If H > 1.792 (A/P), then the grate operates like an orifice; otherwise it operates like a weir. Input Parameters: Type of Grate: Nyloplast 24" Dome Diameter of Grate (ft): 2 Open Area of Grate (ft2):1.88 Rim Elevation (ft): 4981.320 Reduction Factor: 50% Depth vs. Flow: Depth Above Inlet (ft) Elevation (ft) Shallow Weir Flow (cfs) Orifice Flow (cfs) Actual Flow (cfs) 0.00 4981.32 0.00 0.00 0.00 0.20 4981.52 0.84 2.27 0.84 0.30 4981.62 1.55 2.77 1.55 <-10-Year 0.40 4981.72 2.38 3.20 2.38 0.50 4981.82 3.33 3.58 3.33 <-100-Year 0.60 4981.92 4.38 3.92 3.92 0.80 4982.12 6.74 4.53 4.53 1.00 4982.32 9.42 5.07 5.07 <-Overflow 1.20 4982.52 12.39 5.55 5.55 1.40 4982.72 15.61 5.99 5.99 1.60 4982.92 19.07 6.41 6.41 100-Year Design Flow = 3.30 cfs 10-Year Design Flow = 1.50 cfs 5.10.3 HPQ 5.0)2(67.0 gHAQ 0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Di s c h a r g e ( c f s ) Stage (ft) Stage - Discharge Curves Weir Flow Orifice Flow Area Inlet Performance Curve: South Middle Rain Garden Inlet (Basin A10-3A-1) Governing Equations: At low flow depths, the inlet will act like a weir governed by the following equation: * where P = 3.1416*Dia.of grate * where H corresponds to the depth of water above the flowline At higher flow depths, the inlet will act like an orifice governed by the following equation: * where A equals the open area of the inlet grate * where H corresponds to the depth of water above the centroid of the cross-sectional area (A) The exact depth at which the inlet ceases to act like a weir, and begins to act like an orifice is unknown. However, what is known, is that the stage-discharge curves of the weir equation and the orifice equation will cross at a certain flow depth. The two curves can be found below: If H > 1.792 (A/P), then the grate operates like an orifice; otherwise it operates like a weir. Input Parameters: Type of Grate: Nyloplast 18" Dome Diameter of Grate (ft): 1.5 Open Area of Grate (ft2):1.06 Rim Elevation (ft): 4981.320 Reduction Factor: 50% Depth vs. Flow: Depth Above Inlet (ft) Elevation (ft) Shallow Weir Flow (cfs) Orifice Flow (cfs) Actual Flow (cfs) 0.00 4981.32 0.00 0.00 0.00 0.20 4981.52 0.63 1.27 0.63 0.22 4981.54 0.73 1.34 0.73 <-10-Year 0.30 4981.62 1.16 1.56 1.16 0.37 4981.69 1.59 1.73 1.59 <-100-Year 0.40 4981.72 1.79 1.80 1.79 0.60 4981.92 3.29 2.21 2.21 0.80 4982.12 5.06 2.55 2.55 1.00 4982.32 7.07 2.85 2.85 <-Overflow 1.20 4982.52 9.29 3.12 3.12 1.40 4982.72 11.71 3.37 3.37 100-Year Design Flow = 1.60 cfs 10-Year Design Flow =0.70 cfs 5.10.3 HPQ 5.0)2(67.0 gHAQ 0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 Di s c h a r g e ( c f s ) Stage (ft) Stage - Discharge Curves Weir Flow Orifice Flow Area Inlet Performance Curve: South Rain Garden Inlet (Basin A10-7A) Governing Equations: At low flow depths, the inlet will act like a weir governed by the following equation: * where P = 3.1416*Dia.of grate * where H corresponds to the depth of water above the flowline At higher flow depths, the inlet will act like an orifice governed by the following equation: * where A equals the open area of the inlet grate * where H corresponds to the depth of water above the centroid of the cross-sectional area (A) The exact depth at which the inlet ceases to act like a weir, and begins to act like an orifice is unknown. However, what is known, is that the stage-discharge curves of the weir equation and the orifice equation will cross at a certain flow depth. The two curves can be found below: If H > 1.792 (A/P), then the grate operates like an orifice; otherwise it operates like a weir. Input Parameters: Type of Grate: Nyloplast 24" Dome Diameter of Grate (ft): 2 Open Area of Grate (ft2):1.88 Rim Elevation (ft): 4981.320 Reduction Factor: 50% Depth vs. Flow: Depth Above Inlet (ft) Elevation (ft) Shallow Weir Flow (cfs) Orifice Flow (cfs) Actual Flow (cfs) 0.00 4981.32 0.00 0.00 0.00 0.20 4981.52 0.84 2.27 0.84 0.26 4981.58 1.25 2.58 1.25 <-10-Year 0.30 4981.62 1.55 2.77 1.55 0.40 4981.72 2.38 3.20 2.38 0.60 4981.92 4.38 3.92 3.92 0.80 4982.12 6.74 4.53 4.53 <-100-Year 1.00 4982.32 9.42 5.07 5.07 <-Overflow 1.20 4982.52 12.39 5.55 5.55 1.60 4982.92 19.07 6.41 6.41 2.00 4983.32 26.66 7.16 7.16 100-Year Design Flow = 4.5 cfs 10-Year Design Flow = 1.20 cfs 5.10.3 HPQ 5.0)2(67.0 gHAQ 0.00 5.00 10.00 15.00 20.00 25.00 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 Di s c h a r g e ( c f s ) Stage (ft) Stage - Discharge Curves Weir Flow Orifice Flow Project: Inlet ID: Gutter Geometry (Enter data in the blue cells) Maximum Allowable Width for Spread Behind Curb TBACK =0.0 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 =0.013 Height of Curb at Gutter Flow Line HCURB =6.00 inches Distance from Curb Face to Street Crown TCROWN =60.0 ft Gutter Width W =2.00 ft Street Transverse Slope SX =0.025 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 =26.0 26.0 ft Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX =6.0 18.0 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 Version 4.05 Released March 2017 ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm) (Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread) Enter Your Project Name Here Inlet B3 UD-Inlet_v4.05.xlsm, Inlet B3 10/29/2020, 9:53 PM Design Information (Input)MINOR MAJOR Type of Inlet Type = Local Depression (additional to continuous gutter depression 'a' from above)alocal =2.00 2.00 inches Number of Unit Inlets (Grate or Curb Opening) No = 2 2 Water Depth at Flowline (outside of local depression) Ponding Depth = 6.0 9.2 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 0.789 ft Depth for Curb Opening Weir Equation dCurb =0.33 0.60 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 15.5 cfs Inlet Capacity IS GOOD for Minor and Major Storms(>Q PEAK)Q PEAK REQUIRED =2.4 5.8 cfs CDOT/Denver 13 Combination INLET IN A SUMP OR SAG LOCATION Version 4.05 Released March 2017 H-VertH-Curb W Lo (C) Lo (G) Wo WP CDOT/Denver 13 Combination Override Depths UD-Inlet_v4.05.xlsm, Inlet B3 10/29/2020, 9:53 PM Appendix C Water Quality/LID Design Computations Morningstar/Block 23 Calc. By: Fort Collins, Colorado Date: 74,028 sf 29,971 sf 103,999 sf 75% 77,999 sf 54,057 sf 12,023 sf 26,306 sf 92,386 sf 88.8% 2,035 cf 817 cf 2,852 cf 2,035 cf 785 cf 1,250 cf 18 1,348 cf 12 899 cf 2,247 cf 785 cf 3,032 cf 1,066 cf 1,384 cf 2,450 cf 1,215 cf 2,037 cf 3,252 cf Design Detention Volume Project: Location: Isolator Row Chambers (WQ) Volume Standard Chambers (Storage) Volume Design Water Quality Volume Volume in Rain Gardens Total Available Volume West Side 04/29/21 Onsite LID Treatment F. Wegert Rain Garden Planters Other Treatement Impervious Area (West Side) Total Impervious Area Project Summary Impervious Area (East Side) Target Treatment Percentage Minimum Area to be Treated by LID measures StormTech Chambers StormTech Treatment Area (Onsite) Detention Pond Volume Storage and Water Quality Volume East Side Sand Filter Treatment Area Total Treatment Area Percent Total Project Area Treated Required Water Quality Volume Required Detention Volume Total Required Volume Volume of Planters/Rain Gardens Required WQ volume in Chambers Required Detention Volume Total Required Volume Volume in Chambers Required Water Quality Volume Required Water Quality Volume Pr o j e c t N u m b e r : Pr o j e c t N a m e : Pr o j e c t L o c a t i o n : Un d e v e l o p e d B a s i n s De s i g n Po i n t N o t e s Ea s t S i d e Im p e r v i o u s A r e a 3 . 6 4 c f s 1 4 . 6 2 c f s h - a 1 Fl o w r a t e f r o m i m p e r v i o u s a r e a s . Pe r v i o u s A r e a 0 . 0 2 c f s 0 . 0 8 c f s h - a 1 Fl o w r a t e f r o m p e r v i o u s a r e a s . We s t S i d e Im p e r v i o u s A r e a 0 . 7 9 c f s 3 . 4 2 c f s h - b 5 Fl o w r a t e f r o m i m p e r v i o u s a r e a s . Pe r v i o u s A r e a 0 . 0 0 c f s 0 . 0 0 c f s h - b 5 Th e e n t i r e w e s t s i d e i s g r a v e l . T h e r e f o r e , n o p e r v i o u s a r e a s . De v e l o p e d B a s i n s De s i g n Po i n t N o t e s Ea s t S i d e To t a l F l o w r a t e 2 . 3 2 c f s 1 7 . 4 0 c f s a 1 To t a l f l o w r a t e f r o m e a s t s i d e . We s t S i d e To t a l F l o w r a t e 0 . 8 6 c f s 7 . 3 0 c f s w 2 To t a l f l o w r a t e f r o m w e s t s i d e . Ea s t S i d e Im p e r v i o u s 1 0 0 - Y e a r 1 4 . 6 2 c f s Hi s t o r i c Q 10 0 f r o m i m p e r v i o u s a r e a s . Pe r v i o u s 2 - Y e a r 0 . 0 2 c f s Hi s t o r i c Q 2 f r o m p e r v i o u s a r e a s . Al l o w a b l e R e l e a s e R a t e 1 4 . 6 4 c f s To t a l o f 1 0 0 - y e a r r e l e a s e r a t e f o r e n t i r e e a s t s i d e . We s t S i d e Im p e r v i o u s 1 0 0 - Y e a r 3 . 4 2 c f s Hi s t o r i c Q 10 0 f r o m i m p e r v i o u s a r e a s . Pe r v i o u s 2 - Y e a r 0 . 0 0 c f s Hi s t o r i c Q 2 f r o m p e r v i o u s a r e a s . Al l o w a b l e R e l e a s e R a t e 3 . 4 2 c f s T o t a l o f 1 0 0 - y e a r r e l e a s e r a t e f o r e n t i r e w e s t s i d e . Hi s t o r i c F l o w r a t e s HI S T O R I C V S . D E V E L O P E D F L O W R A T E S 12 0 4 - 0 0 4 Mo r n i n g s t a r / B l o c k 2 3 Fo r t C o l l i n s , C o l o r a d o Ca l c u l a t i o n o f R e l e a s e R a t e Q2 Q10 0 Q10 0 Q2 De v e l o p e d F l o w r a t e s Date:11/04/20 Pond No.: A1 100-yr WQCV Required 2,035 ft3 1.00 Planter Volume 690 ft3 1.75 acres WQCV-Planters 1,345 ft3 14.64 cfs Quantity Detention 817 ft3 Volume Less Planters 2162 ft3 Volume Less Planters 0.050 ac-ft Time Time Ft.Collins 100-yr Intensity Q100 Inflow (Runoff) Volume Outflow (Release) Volume Storage Detention Volume (mins) (secs) (in/hr) (cfs) (ft3)(ft3)(ft3) 5 300 9.95 17.4 5209 4392 817 10 600 7.72 13.5 8083 8784 -701 15 900 6.52 11.4 10240 13176 -2936 20 1200 5.60 9.8 11726 17568 -5842 25 1500 4.98 8.7 13035 21960 -8925 30 1800 4.52 7.9 14197 26352 -12155 35 2100 4.08 7.1 14951 30744 -15793 40 2400 3.74 6.5 15663 35136 -19473 45 2700 3.46 6.0 16302 39528 -23226 50 3000 3.23 5.6 16909 43920 -27011 55 3300 3.03 5.3 17448 48312 -30864 60 3600 2.86 5.0 17967 52704 -34737 65 3900 2.72 4.7 18511 57096 -38585 70 4200 2.59 4.5 18982 61488 -42506 75 4500 2.48 4.3 19474 65880 -46406 80 4800 2.38 4.2 19935 70272 -50337 85 5100 2.29 4.0 20380 74664 -54284 90 5400 2.21 3.9 20825 79056 -58231 95 5700 2.13 3.7 21186 83448 -62262 100 6000 2.06 3.6 21568 87840 -66272 105 6300 2.00 3.5 21987 92232 -70245 110 6600 1.94 3.4 22343 96624 -74281 115 6900 1.89 3.3 22757 101016 -78259 120 7200 1.84 3.2 23118 105408 -82290 Detention Pond Calculation | FAA Method Project: Project Location: Calculations By: Morningstar/Block 23 Fort Collins, Colorado F. Wegert East Vault (Stormtech Chambers) Area (A)= Max Release Rate = Developed "C" = Input Variables Results Design Point Required Detention Volume Design Storm P:\1204-004\Drainage\Detention\1204-004_Detention_East.xlsm\ Project: Chamber Model - SC-740 Units -Imperial Number of chambers -30 Voids in the stone (porosity) - 30 % Base of STONE Elevation -100.00 ft Amount of Stone Above Chambers - 12 in Amount of Stone Below Chambers -9 in Area of system -1208 sf Min. Area - Height of System Incremental Single Chamber Incremental Total Chamber Incremental Stone Incremental Ch & St Cumulative Chamber Elevation (inches)(cubic feet)(cubic feet)(cubic feet)(cubic feet)(cubic feet)(feet) 51 0.00 0.00 30.20 30.20 2505.17 104.25 50 0.00 0.00 30.20 30.20 2474.97 104.17 49 0.00 0.00 30.20 30.20 2444.77 104.08 48 0.00 0.00 30.20 30.20 2414.57 104.00 47 0.00 0.00 30.20 30.20 2384.37 103.92 46 0.00 0.00 30.20 30.20 2354.17 103.83 45 0.00 0.00 30.20 30.20 2323.97 103.75 44 0.00 0.00 30.20 30.20 2293.77 103.67 43 0.00 0.00 30.20 30.20 2263.57 103.58 42 0.00 0.00 30.20 30.20 2233.37 103.50 41 0.00 0.00 30.20 30.20 2203.17 103.42 40 0.00 0.00 30.20 30.20 2172.97 103.33 39 0.05 1.65 29.71 31.35 2142.77 103.25 38 0.16 4.89 28.73 33.62 2111.41 103.17 37 0.28 8.46 27.66 36.12 2077.79 103.08 36 0.60 18.12 24.76 42.88 2041.67 103.00 35 0.80 24.05 22.98 47.04 1998.79 102.92 34 0.95 28.52 21.64 50.16 1951.75 102.83 33 1.07 32.24 20.53 52.76 1901.59 102.75 32 1.18 35.41 19.58 54.99 1848.82 102.67 31 1.27 37.97 18.81 56.78 1793.83 102.58 30 1.36 40.65 18.00 58.66 1737.05 102.50 29 1.45 43.62 17.11 60.74 1678.40 102.42 28 1.52 45.74 16.48 62.22 1617.66 102.33 27 1.58 47.47 15.96 63.43 1555.44 102.25 26 1.64 49.27 15.42 64.69 1492.01 102.17 25 1.70 50.99 14.90 65.89 1427.33 102.08 24 1.75 52.59 14.42 67.01 1361.44 102.00 23 1.80 54.08 13.97 68.06 1294.42 101.92 22 1.85 55.65 13.51 69.15 1226.37 101.83 21 1.89 56.79 13.16 69.95 1157.21 101.75 20 1.93 58.02 12.79 70.81 1087.26 101.67 19 1.97 59.25 12.43 71.67 1016.44 101.58 18 2.01 60.30 12.11 72.41 944.77 101.50 17 2.04 61.35 11.80 73.14 872.36 101.42 16 2.07 62.25 11.53 73.77 799.21 101.33 15 2.10 63.15 11.26 74.40 725.44 101.25 14 2.13 63.95 11.01 74.97 651.04 101.17 13 2.15 64.62 10.82 75.43 576.07 101.08 12 2.18 65.31 10.61 75.92 500.64 101.00 11 2.20 65.95 10.41 76.37 424.72 100.92 10 2.21 66.22 10.33 76.55 348.35 100.83 9 0.00 0.00 30.20 30.20 271.80 100.75 8 0.00 0.00 30.20 30.20 241.60 100.67 7 0.00 0.00 30.20 30.20 211.40 100.58 6 0.00 0.00 30.20 30.20 181.20 100.50 5 0.00 0.00 30.20 30.20 151.00 100.42 4 0.00 0.00 30.20 30.20 120.80 100.33 3 0.00 0.00 30.20 30.20 90.60 100.25 2 0.00 0.00 30.20 30.20 60.40 100.17 1 0.00 0.00 30.20 30.20 30.20 100.08 StormTech SC-740 Cumulative Storage Volumes 1014 sf min. area Include Perimeter Stone in Calculations Click Here for Metric Date:11/04/20 Pond No.: A1 100-yr WQCV 0 ft3 1.00 Quantity Detention 1384 ft3 0.74 acres Total Volume 1384 ft3 3.39 cfs Total Volume 0.032 ac-ft Time Time Ft.Collins 100-yr Intensity Q100 Inflow (Runoff) Volume Outflow (Release) Volume Storage Detention Volume (mins) (secs) (in/hr) (cfs) (ft3)(ft3)(ft3) 5 300 9.95 7.3 2203 1017 1186 10 600 7.72 5.7 3418 2034 1384 15 900 6.52 4.8 4331 3051 1280 20 1200 5.60 4.1 4959 4068 891 25 1500 4.98 3.7 5513 5085 428 30 1800 4.52 3.3 6004 6102 -98 35 2100 4.08 3.0 6323 7119 -796 40 2400 3.74 2.8 6624 8136 -1512 45 2700 3.46 2.6 6894 9153 -2259 50 3000 3.23 2.4 7151 10170 -3019 55 3300 3.03 2.2 7379 11187 -3808 60 3600 2.86 2.1 7598 12204 -4606 65 3900 2.72 2.0 7829 13221 -5392 70 4200 2.59 1.9 8028 14238 -6210 75 4500 2.48 1.8 8236 15255 -7019 80 4800 2.38 1.8 8431 16272 -7841 85 5100 2.29 1.7 8619 17289 -8670 90 5400 2.21 1.6 8807 18306 -9499 95 5700 2.13 1.6 8960 19323 -10363 100 6000 2.06 1.5 9122 20340 -11218 105 6300 2.00 1.5 9299 21357 -12058 110 6600 1.94 1.4 9449 22374 -12925 115 6900 1.89 1.4 9624 23391 -13767 120 7200 1.84 1.4 9777 24408 -14631 Input Variables Results Design Point Required Detention Volume Design Storm Detention Pond Calculation | FAA Method Project: Project Location: Calculations By: Morningstar/Block 23 Fort Collins, Colorado F. Wegert West Detention Vault Developed "C" = Area (A)= Max Release Rate = P:\1204-004\Drainage\Detention\1204-004_Detention_West.xlsm\ Project: Date: 4975.19 1,384 ft 3 4977.30 1,163 ft 3 4978.75 2,037 ft 3 1.08 ft 4977.67 Maximum Elevation Minimum Elevation cu. ft. acre ft cu. ft. acre ft 4975.19 N/A 0.0 0 0.0 0.00 0.0 0.00 4975.25 4975.19 68.6 0.1 2.1 0.00 2.1 0.00 4975.50 4975.25 596.2 0.3 83.1 0.00 85.2 0.00 4975.75 4975.50 596.9 0.3 149.1 0.00 234.3 0.01 4976.00 4975.75 597.6 0.3 149.3 0.00 383.6 0.01 4976.25 4976.00 598.2 0.3 149.5 0.00 533.1 0.01 4976.50 4976.25 598.9 0.3 149.6 0.00 682.7 0.02 4976.75 4976.50 599.6 0.3 149.8 0.00 832.5 0.02 4977.00 4976.75 600.3 0.3 150.0 0.00 982.5 0.02 4977.25 4977.00 601.0 0.3 150.2 0.00 1,132.7 0.03 4977.50 4977.25 601.7 0.3 150.3 0.00 1,283.0 0.03 4977.75 4977.50 602.4 0.3 150.5 0.00 1,433.5 0.03 4978.00 4977.75 603.1 0.3 150.7 0.00 1,584.2 0.04 4978.25 4978.00 603.7 0.3 150.8 0.00 1,735.1 0.04 4978.50 4978.25 604.4 0.3 151.0 0.00 1,886.1 0.04 4978.75 4978.50 604.9 0.3 151.2 0.00 2,037.2 0.05 Freeboard: Design Volume: Volume at Grate: Project Number: Project Location: Calculations By: Pond No.: Outlet Elevation: Grate Elevation: Volume at Crest: West Detention Vault Stage Storage Curve Contour Contour Surface Area (ft2) Depth Incremental Volume Cummalitive Volume Pond Stage Storage Curve 1204-004 Fort Collins F. Wegert Detention Vault (West) Elev at Design Volume: Morningstar/Block 23 11/4/2020 Pond Outlet and Volume Data Crest of Pond Elev.: 11/2/2020 4:45 PM P:\1204-004\Drainage\Detention\Stage Storage\ 1204-004_West Pond_Stage-Storage.xlsx\Pond Project Number : Project Name : Project Location : Pond No :Calc. By:F. Wegert Orifice Dia (in):8 11/16 Orifice Area (sf):0.4116 Orifice invert (ft):4975.19 Orifice Coefficient:0.65 Elevation Stage (ft)Velocity (ft/s)Flow Rate (cfs)Comments 4975.19 0.00 0.00 0.00 4975.25 0.06 1.28 0.53 4975.50 0.31 2.90 1.19 4975.75 0.56 3.90 1.61 4976.00 0.81 4.69 1.93 4976.25 1.06 5.37 2.21 4976.50 1.31 5.97 2.46 4976.75 1.56 6.51 2.68 4977.00 1.81 7.01 2.89 4977.25 2.06 7.48 3.08 4977.50 2.31 7.92 3.26 4977.67 2.48 8.21 3.38 <-100 Year Elev. 4977.75 2.56 8.34 3.43 4978.00 2.81 8.74 3.60 4978.25 3.06 9.12 3.75 4978.50 3.31 9.49 3.90 4978.75 3.56 9.84 4.05 4979.00 3.81 10.18 4.19 4979.25 4.06 10.51 4.32 4979.50 4.31 10.82 4.46 4979.75 4.56 11.13 4.58 4980.00 4.81 11.43 4.71 4980.25 5.06 11.73 4.83 ORIFICE RATING CURVE Orifice Rating Curve 1204-004 Morningstar / Block 23 Fort Collins, Colorado West Detention Vault Orifice Design Data Da t e : 04 / 2 9 / 2 1 To t a l Re q u i r e d WQ V o l . In F l o w , WQ In d i v i d u a l Ch a m b e r Re l e a s e Ra t e a In d i v i d u a l Ch a m b e r Vo l u m e b In d i v i d u a l In s t a l l e d Ch a m b e r Vo l u m e c Mi n . Re l e a s e Ra t e e Re q u i r e d Ch a m b e r Vo l u m e b y FA A Me t h o d Pr o v i d e d Re l e a s e Ra t e e Pr o v i d e d Ch a m b e r Vo l u m e f To t a l In s t a l l e d Ch a m b e r Vo l u m e g (c f ) ( c f s ) ( c f s ) ( c f s ) ( c f s ) ( c f s ) ( c f ) ( c f s ) ( c f ) ( c f ) 1 12 5 0 2. 3 SC - 7 4 0 0. 0 2 4 45 . 9 0 74 . 9 0 17 0. 4 0 94 1 13 18 0. 4 2 82 6 13 4 8 b. V o l u m e w i t h i n c h a m b e r o n l y , n o t a c c o u n t i n g f o r v o i d s p a c e s i n s u r r o u n d i n g a g g r e g a t e . a. R e l e a s e r a t e p e r c h a m b e r , l i m i t e d b y f l o w t h r o u g h g e o t e x t i l e w i t h a c c u m u l a t e d s e d i m e n t . Va u l t ID Ch a m b e r Ty p e Mi n . N o . o f Ch a m b e r s d Nu m b e r o f Ch a m b e r s pe r F A A Pr o v i d e d Nu m b e r o f Ch a m b e r s No t e : " C h a m b e r V o l u m e " r e f e r s t o t h e o p e n v o l u m e w i t h i n t h e v a u l t s . " I n s t a l l e d C h a m b e r V o l u m e " r e f e r s t o t h e t o t a l v o l u m e p r o v i d e d , i n c l u d i n g t h e s u r r o u n d i n g a g g r e g a t e s . g. S y s t e m v o l u m e i n c l u d e s t o t a l n u m b e r o f c h a m b e r s , p l u s s u r r o u n d i n g a g g r e g a t e . T h i s n u m b e r m u s t m e e t o r e x c e e d t h e r e q u i r e d W Q C V . f. V o l u m e p r o v i d e d i n c h a m b e r s o n l y ( n o a g g r e g a t e s t o r a g e ) . T h i s n u m b e r m u s t m e e t o r e x c e e d t h e r e q u i r e d F A A s t o r a g e v o l u m e . e. R e l e a s e r a t e p e r c h a m b e r t i m e s n u m b e r o f c h a m b e r s . d. N u m b e r o f c h a m b e r s r e q u i r e d t o p r o v i d e f u l l W Q C V w i t h i n t o t a l i n s t a l l e d s y s t e m , i n c l u d i n g a g g r e g a t e . c. V o l u m e i n c l u d e s c h a m b e r a n d v o i d s p a c e s ( 4 0 % ) i n s u r r o u n d i n g a g g r e g a t e , p e r c h a m b e r u n i t . Mo r n i n g s t a r / B l o c k 2 3 Fo r t C o l l i n s , C o l o r a d o F. W e g e r t St o r m t e c h C h a m b e r s ( E a s t S i d e ) Ch a m b e r C o n f i g u r a t i o n W a t e r Q u a l i t y S u m m a r y Pr o j e c t : Pr o j e c t L o c a t i o n : Ca l c u l a t i o n s B y : De s c r i p t i o n . : 4/ 2 9 / 2 0 2 1 P: \ 1 2 0 4 - 0 0 4 \ D r a i n a g e \ L I D \ 1 2 0 4 - 0 0 4 _ C h a m b e r S u m m a r y . x l s x Ch a m b e r D i m e n s i o n s SC - 1 6 0 L P SC - 3 1 0 S C - 7 4 0 3 5 0 0 Wi d t h ( i n ) 2 5 34 . 0 0 5 1 . 0 0 7 7 . 0 0 Le n g t h ( i n ) 8 5 . 4 8 5 . 4 0 8 5 . 4 0 4 5 . 0 0 He i g h t ( i n ) 1 2 1 6 . 0 0 3 0 . 0 0 9 0 . 0 0 Fl o o r A r e a ( s f ) 1 4 . 8 3 2 0 . 1 6 3 0 . 2 5 2 4 . 0 6 Ch a m b e r V o l u m e ( c f ) 6 . 8 5 1 4 . 7 0 4 5 . 9 0 1 0 9 . 9 0 Ch a m b e r / A g g r e g a t e V o l u m e ( c f ) ( 9 " s t o n e b a s e ) 1 5 . 0 0 3 1 . 0 0 7 4 . 9 0 1 7 8 . 9 0 Ch a m b e r F l o w R a t e C o n v e r s i o n ( g p m / s f t o c f s ) 0. 3 5 g p m / s f 7. 4 8 0 5 2 g a l 0. 1 3 3 6 8 0 5 c f 0. 0 0 2 2 2 8 c f s ** F l o w r a t e b a s e d o n 1 / 2 o f N o v 0 7 Q MA X i n F i g u r e 1 7 o f U N H T e s t i n g R e p o r t SC - 1 6 0 L P S C - 3 1 0 S C - 7 4 0 3 5 0 0 Fl o w R a t e / c h a m b e r ( c f s ) 0 . 0 1 1 5 6 1 7 0 . 0 1 5 7 2 3 9 0 . 0 2 3 5 8 6 0 . 0 1 8 7 6 4 Ch a m b e r F l o w R a t e St o r m T e c h C h a m b e r D a t a Fl o w R a t e * * 1 c f = 1 g a l l o n = 1 G P M = P: \ 1 2 0 4 - 0 0 4 \ D r a i n a g e \ L I D \ 1 2 0 4 - 0 0 4 _ C h a m b e r S u m m a r y . x l s x Date:11/04/20 Pond No.: A1 WQ 1.00 1.45 acres Quantity Detention 941 ft3 0.42 cfs Time Time Ft.Collins WQ Intensity QWQ Inflow (Runoff) Volume Outflow (Release) Volume Storage Detention Volume (mins) (secs) (in/hr) (cfs) (ft3)(ft3)(ft3) 5 300 1.43 2.1 620 126 494 10 600 1.11 1.6 961 252 709 15 900 0.94 1.4 1220 378 842 20 1200 0.81 1.2 1401 504 897 25 1500 0.72 1.0 1555 630 925 30 1800 0.65 0.9 1697 756 941 35 2100 0.59 0.8 1781 882 899 40 2400 0.54 0.8 1862 1008 854 45 2700 0.50 0.7 1938 1134 804 50 3000 0.46 0.7 2001 1260 741 55 3300 0.44 0.6 2081 1386 695 60 3600 0.41 0.6 2140 1512 628 65 3900 0.39 0.6 2177 1638 539 70 4200 0.37 0.5 2223 1764 459 75 4500 0.35 0.5 2251 1890 361 80 4800 0.33 0.5 2297 2016 281 85 5100 0.32 0.5 2329 2142 187 90 5400 0.31 0.4 2388 2268 120 95 5700 0.29 0.4 2397 2394 3 100 6000 0.28 0.4 2436 2520 -84 105 6300 0.27 0.4 2466 2646 -180 110 6600 0.26 0.4 2488 2772 -284 115 6900 0.26 0.4 2551 2898 -347 120 7200 0.25 0.4 2558 3024 -466 Input Variables Results Design Point Required Detention Volume Design Storm Detention Pond Calculation | FAA Method Project: Project Location: Calculations By: Morningstar/Block 23 Fort Collins, Colorado F. Wegert Stormtech Chambers Infiltration Rate Area (A)= Max Release Rate = Developed "C" = P:\1204-004\Drainage\LID\1204-004_FAA_Chambers.xlsx\ Project: Calc. By: Date: 1.745 <-- INPUT from impervious calcs 90.00 <-- INPUT from impervious calcs 0.9000 <-- CALCULATED 12 hours <-- from UDFCD Vol. 3 Table 3-2 0.8 <-- from UDFCD Vol. 3 Table 3-2 0.321 <-- UDFCD Vol. 3 Equation 3-1 0.047 <-- UDFCD Vol. 3 Equation 3-3 2,035 <-- UDFCD Vol. 3 Equation 3-3 Morningstar/Block 23 F. Wegert November 4, 2020 WATER QUALITY DESIGN CALCULATIONS East Parcel Required Storage & Outlet Works Basin Area = Basin Percent Imperviousness = Basin Imperviousness Ratio = WQCV (watershed inches) = WQCV (ac-ft) = WQCV (ft3) = Drain Time Coefficient = Drain Time = Sheet 1 of 2 Designer: Company: Date: Project: Location: 1. Basin Storage Volume A) Effective Imperviousness of Tributary Area, Ia Ia =90.0 % (100% if all paved and roofed areas upstream of rain garden) B) Tributary Area's Imperviousness Ratio (i = Ia/100)i = 0.900 C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.32 watershed inches (WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i) D) Contributing Watershed Area (including rain garden area) Area = 76,011 sq ft E) Water Quality Capture Volume (WQCV) Design Volume VWQCV =2,035 cu ft Vol = (WQCV / 12) * Area F) For Watersheds Outside of the Denver Region, Depth of d6 = in Average Runoff Producing Storm G) For Watersheds Outside of the Denver Region, VWQCV OTHER =cu ft Water Quality Capture Volume (WQCV) Design Volume H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER =cu ft (Only if a different WQCV Design Volume is desired) 2. Basin Geometry A) WQCV Depth (12-inch maximum)DWQCV =12 in B) Rain Garden Side Slopes (Z = 4 min., horiz. dist per unit vertical) Z = 0.00 ft / ft (Use "0" if rain garden has vertical walls) C) Mimimum Flat Surface Area AMin =1368 sq ft D) Actual Flat Surface Area AActual =785 sq ft ACTUAL FLAT AREA < MINIMUM FLAT AREA E) Area at Design Depth (Top Surface Area)ATop =785 sq ft F) Rain Garden Total Volume VT=785 cu ft TOTAL VOLUME < DESIGN VOLUME (VT= ((ATop + AActual) / 2) * Depth) 3. Growing Media 18" thick layer of bioretention sand media over 4" thick layer of pea gravel over 8" thick layer of CDOT No. 4 aggregate 4. Underdrain System A) Are underdrains provided?1 B) Underdrain system orifice diameter for 12 hour drain time i) Distance From Lowest Elevation of the Storage y =1.8 ft Volume to the Center of the Orifice ii) Volume to Drain in 12 Hours Vol12 =2,035 cu ft iii) Orifice Diameter, 3/8" Minimum DO =1 1/16 in Design Procedure Form: Rain Garden (RG) Frederick Wegert Northern Engineering February 10, 2021 Morningstar/Block 23 Courtyard Planters - East Building UD-BMP (Version 3.07, March 2018) Choose One Choose One 18" Rain Garden Growing Media Other (Explain): YES NO UD-BMP_v3.03_Planters-East.xlsm, RG 2/10/2021, 8:58 AM Sheet 2 of 2 Designer: Company: Date: Project: Location: 5. Impermeable Geomembrane Liner and Geotextile Separator Fabric A) Is an impermeable liner provided due to proximity of structures or groundwater contamination? PROVIDE A 30 MIL (MIN) PVC LINER WITH CDOT CLASS B GEOTEXTILE ABOVE IT. USE THE SAME GEOTEXTILE BELOW THE LINER IF THE SUBGRADE IS ANGULAR 6. Inlet / Outlet Control A) Inlet Control 7. Vegetation 8. Irrigation A) Will the rain garden be irrigated? Notes: Design Procedure Form: Rain Garden (RG) Frederick Wegert Northern Engineering February 10, 2021 Morningstar/Block 23 Courtyard Planters - East Building Choose One Choose One Choose One Sheet Flow- No Energy Dissipation Required Concentrated Flow- Energy Dissipation Provided Plantings Seed (Plan for frequent weed control) Sand Grown or Other High Infiltration Sod Choose One YES NO YES NO UD-BMP_v3.03_Planters-East.xlsm, RG 2/10/2021, 8:58 AM Project: Calc. By: Date: 0.612 <-- INPUT from impervious calcs 100.00 <-- INPUT from impervious calcs 1.0000 <-- CALCULATED 12 hours <-- from UDFCD Vol. 3 Table 3-2 0.8 <-- from UDFCD Vol. 3 Table 3-2 0.400 <-- UDFCD Vol. 3 Equation 3-1 0.024 <-- UDFCD Vol. 3 Equation 3-3 1,066 <-- UDFCD Vol. 3 Equation 3-3 Morningstar/Block 23 F. Wegert November 4, 2020 WATER QUALITY DESIGN CALCULATIONS West Parcel Required Storage & Outlet Works Basin Area = Basin Percent Imperviousness = Basin Imperviousness Ratio = WQCV (watershed inches) = WQCV (ac-ft) = WQCV (ft3) = Drain Time Coefficient = Drain Time = Sheet 1 of 2 Designer: Company: Date: Project: Location: 1. Basin Storage Volume A) Effective Imperviousness of Tributary Area, Ia Ia =100.0 % (100% if all paved and roofed areas upstream of sand filter) B) Tributary Area's Imperviousness Ratio (i = Ia/100)i = 1.000 C) Water Quality Capture Volume (WQCV) Based on 12-hour Drain Time WQCV = 0.40 watershed inches WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i) D) Contributing Watershed Area (including sand filter area) Area = 26,662 sq ft E) Water Quality Capture Volume (WQCV) Design Volume VWQCV =cu ft VWQCV = WQCV / 12 * Area F) For Watersheds Outside of the Denver Region, Depth of d6 = in Average Runoff Producing Storm G) For Watersheds Outside of the Denver Region, VWQCV OTHER =cu ft Water Quality Capture Volume (WQCV) Design Volume H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER =1,066 cu ft (Only if a different WQCV Design Volume is desired) 2. Basin Geometry A) WQCV Depth DWQCV =2.0 ft B) Sand Filter Side Slopes (Horizontal distance per unit vertical, Z = 0.00 ft / ft 4:1 or flatter preferred). Use "0" if sand filter has vertical walls. C) Minimum Filter Area (Flat Surface Area)AMin =333 sq ft D) Actual Filter Area AActual =566 sq ft E) Volume Provided VT =1215 cu ft 3. Filter Material 4. Underdrain System A) Are underdrains provided?1 B) Underdrain system orifice diameter for 12 hour drain time i) Distance From Lowest Elevation of the Storage y=1.8 ft Volume to the Center of the Orifice ii) Volume to Drain in 12 Hours Vol12 =1,066 cu ft iii) Orifice Diameter, 3/8" Minimum DO =3/4 in Morningstar/Block 23 Sand Filter Vault - West Building/Parking Garage Design Procedure Form: Sand Filter (SF) Frederick S. Wegert Northern Engineering December 15, 2020 UD-BMP (Version 3.07, March 2018) Choose One Choose One 18" CDOT Class B or C Filter Material Other (Explain): YES NO UD-BMP_v3.03_Sand Filter_West.xlsm, SF 12/15/2020, 8:34 AM Sheet 2 of 2 Designer: Company: Date: Project: Location: 5. Impermeable Geomembrane Liner and Geotextile Separator Fabric A) Is an impermeable liner provided due to proximity of structures or groundwater contamination? PROVIDE A 30 MIL (MIN) PVC GEOMEMBRANE PER TABLE SF-4 WITH SEPARATOR FABRIC (PER TABLE SF-3) ABOVE IT. PROVIDE SEPARATOR FABRIC BELOW THE GEOMEMBRANE AS WELL IF SUBGRADE IS ANGULAR OR COULD OTHERWISE PUNCTURE THE GEOMEMBRANE. 6. Inlet / Outlet Works A) Describe the type of energy dissipation at inlet points and means of conveying flows in excess of the WQCV through the outlet Notes: Design Procedure Form: Sand Filter (SF) Frederick S. Wegert Northern Engineering December 15, 2020 Morningstar/Block 23 Sand Filter Vault - West Building/Parking Garage Choose One YES NO UD-BMP_v3.03_Sand Filter_West.xlsm, SF 12/15/2020, 8:34 AM Project: Date: 4976.64 1,066 ft 3 4978.65 1,125 ft 3 4978.75 1,184 ft 3 0.20 ft 4978.55 Maximum Elevation Minimum Elevation cu. ft. acre ft cu. ft. acre ft 4976.64 N/A 0.0 0 0.0 0.00 0.0 0.00 4976.75 4976.64 566.8 0.1 31.2 0.00 31.2 0.00 4977.00 4976.75 569.2 0.3 142.0 0.00 173.2 0.00 4977.25 4977.00 571.6 0.3 142.6 0.00 315.8 0.01 4977.50 4977.25 574.0 0.3 143.2 0.00 459.0 0.01 4977.75 4977.50 576.4 0.3 143.8 0.00 602.8 0.01 4978.00 4977.75 578.8 0.3 144.4 0.00 747.2 0.02 4978.25 4978.00 581.2 0.3 145.0 0.00 892.2 0.02 4978.50 4978.25 583.6 0.3 145.6 0.00 1,037.8 0.02 4978.75 4978.50 585.3 0.3 146.1 0.00 1,183.9 0.03 Freeboard: WQ Volume: Volume at Overflow: Project Number: Project Location: Calculations By: Pond No.: Top of Sand Elev.: Overflow Elevation: Volume at Crest: West Sand Filter Vault Stage Storage Curve Contour Contour Surface Area (ft2) Depth Incremental Volume Cummalitive Volume Pond Stage Storage Curve 1204-004 Fort Collins F. Wegert Sand Filter Vault Elev at WQ Volume: Morningstar/Block 23 12/15/2020 Pond Outlet and Volume Data Crest of Pond Elev.: 12/15/2020 8:52 AM P:\1204-004\Drainage\Detention\Stage Storage\ 1204-004_West Sand Filter_Stage-Storage.xlsx\Pond Project Number : Project Name : Project Location : Pond No :Calc. By: Q=3.3LH 1.5 Length (L)=21.00 FT Crest Elevation =4978.65 FT Depth Above Crest (ft) Elevation (ft) Flow (cfs) 0.00 4978.65 0.00 0.10 4978.75 2.19 0.20 4978.85 6.20 Q100 0.30 4978.95 11.39 0.40 4979.05 17.53 0.50 4979.15 24.50 0.60 4979.25 32.21 0.70 4979.35 40.59 0.80 4979.45 49.59 0.90 4979.55 59.17 1.00 4979.65 69.30 Q100 = 6.1 CFS Input Parameters: Depth vs. Flow: Sand Filter Vault SHARP-CRESTED WEIR This equation can be used to derive the stage-discharge relationship for a sharp crested weir where the depth of flow is small compared to the length of weir. Reference 1) Hydrologic Analysis and Design, Richard H McCuen, Prentice Hall, 1989. Pg.549. * where Q is flow rate in CFS * where L is the crest length of the weir (FT) * where H is the height of flow over the crest (FT) Governing Equations: 1204-004 Morningstar / Block 23 Fort Collins, Colorado F. Wegert Appendix D Erosion Control Report Final Drainage Report March 17, 2021 Morningstar/Block 23 Erosion Control Report Erosion Control Report A comprehensive Erosion and Sediment Control Plan (along with associated details) has been included with the final construction drawings. It should be noted, however, that any such Erosion and Sediment Control Plan serves only as a general guide to the Contractor. Staging and/or phasing of the BMPs depicted, and additional or different BMPs from those included may be necessary during construction, or as required by the authorities having jurisdiction. It shall be the responsibility of the Contractor to ensure erosion control measures are properly maintained and followed. The Erosion and Sediment Control Plan is intended to be a living document, constantly adapting to site conditions and needs. The Contractor shall update the location of BMPs as they are installed, removed or modified in conjunction with construction activities. It is imperative to appropriately reflect the current site conditions at all times. The Erosion and Sediment Control Plan shall address both temporary measures to be implemented during construction, as well as permanent erosion control protection. Best Management Practices from the Volume 3, Chapter 7 Construction BMPs will be utilized. Measures may include, but are not limited to, silt fencing and/or wattles along the disturbed perimeter, gutter protection in the adjacent roadways and inlet protection at existing and proposed storm inlets. Vehicle tracking control pads, spill containment and clean-up procedures, designated concrete washout areas, dumpsters, and job site restrooms shall also be provided by the Contractor. Grading and Erosion Control Notes can be found on Sheet CS2 of the Utility Plans. The Final Utility Plans will also contain a full-size Erosion Control Plan as well as a separate sheet dedicated to Erosion Control Details. In addition to this report and the referenced plan sheets, the Contractor shall be aware of, and adhere to, the applicable requirements outlined in any existing Development Agreement(s) of record, as well as the Development Agreement, to be recorded prior to issuance of the Development Construction Permit. Also, the Site Contractor for this project may be required to secure a Stormwater Construction General Permit from the Colorado Department of Public Health and Environment (CDPHE), Water Quality Control Division Stormwater Program, before commencing any earth disturbing activities. Prior to securing said permit, the Site Contractor shall develop a comprehensive Storm Water Management Plan (SWMP) pursuant to CDPHE requirements and guidelines. The SWMP will further describe and document the ongoing activities, inspections, and maintenance of construction BMPs. Appendix E USDA Soils Report Appendix F FEMA Firmette Map Pocket DR1 Drainage Exhibit