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Home My WebLink AboutFORT COLLINS MONTESSORI SCHOOL - SPA190003 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTPrepared For: Hauser Architects, P.C. 3780 East 15th Street, Suite 201 Loveland, CO 80538 970-669-8220 Prepared By: Coffey Engineering & Surveying, LLC 4045 St. Cloud Drive, Suite 180 Loveland, CO 80538 970-622-2095 Project No. 2259.03 October 18, 2019 FINAL DRAINAGE REPORT FORT COLLINS MONTESSORI SCHOOL 1109 W HARMONY FORT COLLINS, CO 80526 Fort Collins Montessori School FINAL DRAINAGE REPORT ENGINEER’S CERTIFICATION I hereby certify that this Final Drainage Report for the design of stormwater management facilities for the Fort Collins Montessori School site was prepared by me, or under my direct supervision, in accordance with the provisions of the City of Fort Collins Stormwater Criteria Manual for the owners thereof. Troy W. Campbell, P.E. Registered Professional Engineer State of Colorado No. 41159 I. Table of Contents I. GENERAL LOCATION AND DESCRIPTION ......................................... 1 A. Location .................................................................................................................... 1 B. Description of Property ........................................................................................... 1 II. DRAINAGE BASINS AND SUB-BASINS .................................................. 1 A. Major Basin Description ......................................................................................... 2 B. Sub-Basin Description ............................................................................................. 2 III. DRAINAGE CRITERIA ............................................................................... 3 A. Regulations ............................................................................................................... 3 B. Implementation of the “Four Step Process” .......................................................... 3 C. Development Criteria Reference and Constraints ................................................ 4 D. Hydrological Criteria............................................................................................... 5 E. Hydraulic Criteria ................................................................................................... 5 F. Modifications of Criteria ......................................................................................... 6 IV. DRAINAGE FACILITY DESIGN ............................................................... 6 A. General Concept....................................................................................................... 6 B. Specific Details ......................................................................................................... 6 V. CONCLUSIONS ............................................................................................. 6 A. Compliance with Standards .................................................................................... 6 B. Drainage Concept..................................................................................................... 7 VI. REFERENCES ............................................................................................... 7 VII. APPENDICES A. Hydrologic Computations Vicinity Map Fort Collins Flood Map FEMA FIRM Map Panel 08069C0979H USGS Soil Map Figure 3.4-1 Fort Collins Rainfall Intensity Curve Table 3.4-1Fort Collins Rainfall Intensity Table Table 3.2-2 Surface Type - Runoff Coefficients Rational Method Calculated Composite C Tables Rational Method Calculated Imperviousness Rational Method Calculated Flows B. Hydraulic Computations Fort Collins Modified FAA Method Ponds 1-4 Stage-Storage Sizing for Detention Ponds Water Quality Capture Volume Calculation Restrictor Plate Calculation Outlet Calculations Infiltration Calculation Spillway Calculation Linear Bioretention Cross-Section A-A Swale Cross-Section B-B 2' Curb Cut Calculation Rip Rap Calculation C. Map Pocket Drainage Plan Outlet Structure Detail PAGE | 1 I. GENERAL LOCATION AND DESCRIPTION A. Location The proposed site is located in the northeast quarter (NE ¼) of Section 3, Township 6 North, Range 69 West of the 6th P.M., City of Fort Collins, County of Larimer, State of Colorado. Specifically, the property is located southwest of the intersection of West Harmony Road and South Shields Street. The property address is 1109 West Harmony Road, Fort Collins, Colorado, 80526. (Please see the vicinity map located in the Appendix A). B. Description of Property The site is 4.29 acres currently zoned as low-density mixed-use neighborhood district (LMN). The existing site consists of a residence, detached garage, various outbuildings, gravel access drive and native vegetation. The site is bound by Harmony Road to the north, Shields Street to the east, and residential lots to the south and west. The existing site is comprised of two sub-basins. The northern portion of the site, approximately 2.17 acres, drains to the northeast corner of the site at a slope of approximately 3 percent to an existing 3’x3’ area inlet. The southern portion of the site, approximately 2.12 acres, sheet flows to the south onto the adjacent property. According to the NRCS soils map survey, the native soils consist of Altvan-Satanta Loams (a United States Department of Agriculture Type “B” hydrologic soil). These soils have a moderate rate of water transmission. There are no active irrigation facilities located within the proposed site area. The development of the site will occur in two phases. This drainage report will address the improvements for only phase I. The development of phase I consists of the construction of a 14,700-sf Montessori school, two temporary modular buildings, concrete sidewalks, playground area, right turn lane off Shields Street and landscaping improvements. Parking will be provided to the north of the proposed building on an asphalt parking lot with concrete curb and gutter allowing for site drainage. The site will utilize four on-site detention ponds connected by equalizer pipes. The detention ponds were designed to accommodate developed flows from both phases of development. PAGE | 2 II. DRAINAGE BASINS AND SUB-BASINS A. Major Basin Description The proposed site is located within the Mail Creek Basin, located in southwest Fort Collins. The basin has a drainage area of approximately 1676 acres and is primarily located between Taft Hill Road and Lemay Avenue between Horsetooth Road and County Road 36. The basin generally drains from west to east to the confluence of Mail Creek and Fossil Creek, and ultimately to Fossil Creek Reservoir. The site is located within the FEMA Firm Map Panel 08069C1000F but is outside of the FEMA floodplain and floodway (see FEMA Firm Map Panel in Appendix A). B. Sub-Basin Description Historically, the northern portion of the site drains to the northeast corner of the site to an existing storm sewer inlet and the southern portion of the site sheet flows to the adjacent property to the south. The developed site is delineated into seven sub-basins, that will generally follow historic drainage patterns. Sub-basin P1, (0.89 acres), consists of the northwest portion of the site, and is comprised of a portion of the proposed building, asphalt parking lot, concrete sidewalks and landscaped area. Runoff is directed north to the low point of the proposed parking lot. Runoff flows through a curb cut to the proposed linear bioretention swale then east to the northern portion of the proposed detention pond. This basin produces roughly 6.18 cfs of flow during a 100- year event. Sub-basin P2, (1.45 acres), consists of the southwestern portion of the site, and is comprised of a portion of the proposed building, existing greenhouse and concrete sidewalks, playground areas and detention pond. Runoff is directed southwest towards the proposed detention pond. Runoff is then directed through a storm pipe to the ultimate outlet point located in the sub-basin P3 detention pond. This basin produces roughly 3.30 cfs of flow during a 100-year event. Sub-basin P3, (0.53 acres), consists of the northeast portion of the site, and is comprised of a portion of the asphalt drive aisle, concrete sidewalks and detention pond. The asphalt drive aisle is shaped as an oval with the detention pond located in the center. Runoff drains towards the center of the drive aisle through curb cuts to the proposed detention pond. Runoff exits the proposed detention pond through an outlet structure designed to release runoff at the 2-year historic rate. This basin produces roughly 4.57 cfs of flow during a 100- year event. PAGE | 3 Sub-basin P4, (0.39 acres), consists of the southeast portion of the site, and is comprised of a portion of the asphalt drive aisle, landscaping and detention pond. Runoff drains east towards the flowline of the drive aisle then south to a proposed curb cut to the proposed detention pond. Runoff exits the proposed detention pond through a storm pipe to the proposed detention pond located in sub-basin P3. This basin produces roughly 2.28 cfs of flow during a 100-year event. Sub-basin P5, (0.07 acres), consists of the central portion of the site, and is comprised of a portion of the proposed building, concrete sidewalks and landscaping. Runoff is directed towards a 12” catch basin located at the center of the basin. Runoff is directed through a storm pipe to the proposed detention pond located in sub-basin P3. This basin produces roughly 0.72 cfs of flow during a 100-year event. Sub-basin P6, (1.55 acres), consists of the south-central portion of the site, and is comprised of landscaped area. Runoff sheet flows south to the adjacent property. This basin produces roughly 0.89 cfs of flow during a 100-year event, which is less than the historic rate of 1.50 cfs that currently drains onto the property to the south. Sub-basin P7, (0.13 acres), consists of the northeastern portion of the site, and is comprised of landscaped area. Runoff sheet flows east to the flowline of South Shields Street. This basin produces roughly 0.16 cfs of flow during a 100-year event. Currently, offsite flows do not enter the site property. This will not change after the site has been developed. III. DRAINAGE CRITERIA C. Regulations Drainage design criteria specified in the Fort Collins Stormwater Criteria Manual and the Urban Storm Drainage Criteria Manual, Volume 3 by the Urban Drainage and Flood Control District (UDFCD) have been referenced in the preparation of this study. D. Implementation of the “Four Step Process” Our stormwater management strategy utilizes the “Four Step Process” to minimize adverse impacts of urbanization on receiving waters, as follows: Step 1 – Employ Runoff Reduction Practices. To reduce runoff peaks, volumes and pollutant loads from urbanizing areas, implement LID strategies, including Minimizing Directly Connected Impervious Area (MDCIA). LID practices reduce unnecessary impervious areas and route runoff from impervious surfaces PAGE | 4 over permeable areas to slow runoff (increase time of concentration) and promote infiltration. A linear bioretention swale will be utilized to minimize the directly connected impervious areas. Runoff from the northern portion asphalt parking lot will be routed through a bioswale to slow flows and allow for infiltration. The site contains Type “B” soils, which will also help promote infiltration. Step 2 – Implement BMPs That Provide a Water Quality Capture Volume (WQCV) with Slow Release. After runoff has been minimized, the remaining runoff should be treated through capture and slow release of the WQCV. Extended detention basins will be utilized to ensure that runoff is released at the 2-year historic rate and provided water quality during minor storm events. Step 3 – Stabilize Drainageways. Mail Creek is the governing drainageway for the proposed site. By improving the water quality, limiting runoff to 2-year historic rates and increasing infiltration, the likelihood of bed and bank erosion caused by runoff from this site is reduced. The Mail Creek Master Plan update is currently underway. The development of this site will not impede the progress of the master plan. Step 4 – Implement Site Specific and Other Source Control BMPs. Linear Bioretention (Bioswale): Linear bioretention has low longitudinal slopes and broad cross-sections that convey flow in a slow and shallow manner, thereby facilitating sedimentation and filtering while limiting erosion. Berms or check dams may be incorporated into the facility to reduce velocities and encourage settling and infiltration. Linear bioretention is an integral part of the LID concept. Extended Detention Basin: An extended detention basin (EDB) is a sedimentation basin designed to detain stormwater for many hours after storm runoff ends. This BMP is similar to a detention basin used for flood control, however; the EBD uses a much smaller outlet that extends the emptying time of the more frequently occurring runoff events to facilitate pollutant removal. E. Development Criteria Reference and Constraints The criteria used as the basis for analysis and design of stormwater management improvements for this site are found in the references cited. PAGE | 5 To the knowledge of the author, there are no other capital drainage improvements planned for the site that would constrain or otherwise influence the design of the stormwater improvements for this site. F. Hydrological Criteria Stormwater runoff is analyzed for storms with 2-year and 100-year return frequencies. The Rational Method was chosen for this small site. The Rational Method provides that: Q = CIA, where: Q = Design flow in cubic feet per second (cfs) C = Coefficient of runoff for the area under consideration I = Rainfall intensity for the design storm duration (in/hr) A = Area of the drainage sub-basin under consideration (ac) Peak flows were calculated using the Rational Method for the 2-year and 100-year storm events. This software uses the local 1-hour rainfall depth and Fort Collins rainfall intensities, calculated as a function of the time of concentration. These values were obtained by the City of Fort Collins Rainfall Intensity-Duration-Frequency (IDF) curve/table; Figure 3.4-1 and Table 3.4-1, and can be found in Appendix A. Additionally, per the City of Fort Collins, the “C’ coefficients have been multiplied by the appropriate storm frequency factors. “C” values were taken from Table 3.2-2, Surface Types – Runoff Coefficients (See Appendix A). Soils of hydrologic soil type “B” dominate the site. Onsite runoff was calculated to determine the runoff differential between existing and developed conditions for use in sizing the WQCV as required by the FCSDM. The hydrologic basin parameters and runoff rates are included in the Appendices. The design worksheets included in the Appendices to this Final Drainage Report present documentation of the hydrologic calculations for the on-site storm drainage systems. We modified Urban Drainage spreadsheets to incorporate Fort Collins criteria as follows: • The Modified FAA spreadsheet incorporates the rainfall data from the Fort Collins Stormwater Criteria Manual, Table 3.4-1. G. Hydraulic Criteria Within this development, all runoff will be conveyed on the surface, initially as sheet flow and subsequently as concentrated flow in swales, bioswales, and curb & gutter. The assessment of required capacity and the sizing of the respective components of the drainage system are based on the anticipated runoff from the 100-year storm event. The surface runoff will culminate into an on-site detention pond. PAGE | 6 H. Modifications of Criteria There are no modifications or variances requested in connection with the design of the stormwater management for the Fort Collins Montessori School development. IV. DRAINAGE FACILITY DESIGN I. General Concept The storm drainage system is designed to safely convey developed storm flows by sheet flow, pipe flow, concentrated swale and gutter flow to the detention pond. The design worksheets included in the Appendices to this Final Drainage Report present details of the hydrologic and hydraulic calculations pertinent to the design of the on-site storm drainage system. A drainage plan, showing the proposed development of the site and developed drainage patterns is included in the map pocket following the Appendices. J. Specific Details The site will utilize on-site detention ponds located throughout. Runoff will enter the detention system through a proposed bioswale or through a series of storm sewer PVC pipes. The proposed detention ponds have a capacity of approximately 25,575 cubic feet. The required detention for the site is 25,150 cubic feet. The detention pond will drain through an outlet structure with a release rate of 1.20 cfs. The 100-year release rate was based off the 2-year historic flow rate. The proposed detention pond will have three controlled release rates. The detention pond has a water quality volume of 7,100 cubic feet and a release rate of 0.08 cfs through three ¾” orifices at 1’ intervals. Runoff exceeding the water quality elevation of 5087.0 will flow through a grated lid into the 18” outlet pipe. This pipe will be covered by a restrictor plate to control the release rate to 1.20 cfs. Runoff greater than a 100-year event will exit the detention pond through an emergency spillway at a rate no greater than the 100-year developed flow. The 100-year WSEL is 5088.60’ with 1’ of freeboard provided. V. CONCLUSIONS K. Compliance with Standards The drainage design for the Fort Collins Montessori School Site follows the requirements of the Fort Collins Stormwater Criteria Manual as well as the City’s floodplain regulations. The criteria and recommendations of the Urban Storm Drainage Criteria Manual are also reflected in the design of the drainage systems. PAGE | 7 L. Drainage Concept The drainage design for the Fort Collins Montessori School site will safely convey onsite flows from the development into extended detention basin. Water quality treatment will be achieved by the extended detention basin system and linear bioretention. VI. REFERENCES “Fort Collins Stormwater Criteria Manual”, City of Fort Collins, Adopted December 2018. Natural Resources Conservation Service Web Soil Survey at websoilsurvey.nrcs.usda.gov/app Urban Storm Drainage Criteria Manual, Volumes 1, 2, and 3, Urban Drainage and Flood Control District, April 2008. VII. APPENDICES A. Hydrologic Computations Vicinity Map Fort Collins Flood Map FEMA FIRM Map Panel 08069C0979H USGS Soil Map Figure 3.4-1 Fort Collins Rainfall Intensity Curve Table 3.4-1Fort Collins Rainfall Intensity Table Table 3.2-2 Surface Type - Runoff Coefficients Rational Method Calculated Composite C Tables Rational Method Calculated Imperviousness Rational Method Calculated Flows Soil Map—Larimer County Area, Colorado Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 8/28/2019 Page 1 of 3 4485700 4485720 4485740 4485760 4485780 4485800 4485820 4485840 4485860 4485880 4485900 4485700 4485720 4485740 4485760 4485780 4485800 4485820 4485840 4485860 4485880 4485900 491690 491710 491730 491750 491770 491790 491810 491830 491850 491690 491710 491730 491750 491770 491790 491810 491830 491850 40° 31' 25'' N 105° 5' 53'' W 40° 31' 25'' N 105° 5' 46'' W 40° 31' 18'' N 105° 5' 53'' W 40° 31' 18'' N 105° 5' 46'' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 0 50 100 200 300 Feet 0 15 30 60 90 Meters Map Scale: 1:1,050 if printed on A portrait (8.5" x 11") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 3 Altvan-Satanta loams, 0 to 3 percent slopes 4.7 100.0% Totals for Area of Interest 4.7 100.0% Soil Map—Larimer County Area, Colorado Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 8/28/2019 Page 3 of 3 USGS The National Map: Orthoimagery. Data refreshed April, 2019. National Flood Hazard Layer FIRMette 0 250 500 1,000 1,500 2,000 Feet Ü 105°6'8.45"W 40°31'34.63"N 105°5'30.99"W 40°31'7.28"N SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT HAZARD SPECIAL FLOOD AREAS Without Zone A, V, Base A99 Flood Elevation (BFE) With BFE or Depth Zone AE, AO, AH, VE, AR Regulatory Floodway 0.of 2% 1% Annual annual Chance chance Flood flood with Hazard, average Areas depth areasdrainage of less less than than one one foot square or with mile Zone X Future ChanceAnnual Conditions Flood Hazard 1% Zone X Area Levee.to with See Reduced Notes. Flood Risk due Zone X Area with Flood Risk due to LeveeZone D NO SCREEN Area of Minimal Flood Hazard Zone X Area of Undetermined Flood Hazard Zone D Channel, Culvert, or Storm Sewer Levee, Dike, or Floodwall Cross Sections with 1% Annual Chance 17.5 Water Surface Elevation Coastal Transect Coastal Transect Baseline Profile Baseline Hydrographic Feature Base Flood Elevation Line (BFE) Effective LOMRs Limit of Study Jurisdiction Boundary Digital Data Available No Digital Data Available Unmapped This digital map flood complies maps if with it is FEMA's not void standards as described for the below. use of The accuracy basemap standards shown complies with FEMA's basemap The authoritative flood hazard NFHL information web services is derived provided directly by FEMA. from This the map was reflectnot exported changes on or 8/amendments 28/2019 at 2:subsequent 46:08 PM to and this does date and time. becomeor The superseded NFHL and effective by new data information over time. may change This elementsmap map image do not is appear: void if basemap the one or imagery, more of flood the following zone labels, legend, FIRM panel scale number, bar, map and creation FIRM effective date, community date. Map identifiers,images for unmapped regulatoryfor purposes. and unmodernized areas cannot be used Legend OTHER FLOOD AREAS HAZARD OF OTHER AREAS STRGUECNTUERREASL FEATURES OTHER MAP PANELS 8 1:6,000 B 20.2 The point pin selected displayed by the on the user map and is does an approximate not represent an authoritative property location. 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 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 Composite C Values Fort Collins Montessori School Total Area Minor (2-YR) Major (100-YR) (acres) Runoff Coefficent Runoff Coefficent - E1 0.00 0.05 0.24 0.10 1.78 2.17 0.20 0.25 - E2 0.00 0.00 0.00 0.01 2.11 2.12 0.10 0.13 - Site 0.00 0.05 0.24 0.11 3.89 4.29 0.15 0.19 1 P1 0.31 0.08 0.00 0.13 0.37 0.89 0.60 0.75 2 P2 0.00 0.09 0.07 0.20 1.09 1.45 0.29 0.36 3 P3 0.25 0.10 0.00 0.02 0.16 0.53 0.69 0.87 4 P4 0.16 0.01 0.00 0.00 0.22 0.39 0.47 0.59 5 P5 0.00 0.02 0.00 0.04 0.01 0.07 0.83 1.00 - P6 0.00 0.01 0.03 0.02 0.77 0.83 0.15 0.18 - P7 0.00 0.00 0.00 0.00 0.13 0.13 0.10 0.13 Phase I Site 0.72 0.31 0.10 0.41 2.75 4.29 0.39 0.49 Phase II Full Site 1.03 0.37 0.10 0.73 2.06 4.29 0.53 0.66 Notes: Values from Fort Collins Stormwater Criteria Manual Table 3.2-2 Developed Design Point Basin(s) Existing Asphalt Area (acres) Concrete Area (acres) Gravel (acres) Roofs (acres) Lawns (acres) RJP Rational Method Flow Calculations.xlsx 10/14/2019 Imperviousness Fort Collins Montessori School Asphalt Area (acres) Concrete Area (acres) Gravel (acres) Roofs (acres) Lawns (acres) Total Area Percent (I = 100) (I = 100) (I = 40) (I = 90) (I = 2) (acres) Imperviousness - E1 0.00 0.05 0.24 0.10 1.78 2.17 13% - E2 0.00 0.00 0.00 0.01 2.11 2.12 2% - Site 0.00 0.05 0.24 0.11 3.89 4.29 8% 1 P1 0.31 0.08 0.00 0.13 0.37 0.89 58% 2 P2 0.00 0.09 0.07 0.20 1.09 1.45 22% 3 P3 0.25 0.10 0.00 0.02 0.16 0.53 70% 4 P4 0.16 0.01 0.00 0.00 0.22 0.39 45% 5 P5 0.00 0.02 0.00 0.04 0.01 0.07 80% - P6 0.00 0.01 0.03 0.02 0.77 0.83 7% - P7 0.00 0.00 0.00 0.00 0.13 0.13 2% Phase I Site 0.72 0.31 0.10 0.41 2.75 4.29 35% Phase II Full Site 1.03 0.37 0.10 0.73 2.06 4.29 50% Notes: Values from Fort Collins Stormwater Criteria Manual Table 4.1-3 Developed Design Point Basin (s) Existing RJP Rational Method Flow Calculations.xlsx 10/14/2019 Individual Basin Flow Calculations Fort Collins Montessori School Area Minor Major (acres) Composite "C" Composite "C" Length (ft) Slope (%) Minor tov (min)a Major tov (min)a Length (ft) Slope (%) Channel Type Velocity (fps)c tt (min) Minor TC (min) Major TC (min) 2-yr 100-yr 2-yr 100-yr D1 E1 2.17 0.20 0.25 200 3.00 15.94 15.04 0 0.50 PA 1.41 0.00 15.94 15.04 1.87 6.52 0.82 3.59 D2 E2 2.12 0.10 0.13 200 3.00 17.70 17.24 0 0.50 PA 1.41 0.00 17.70 17.24 1.70 5.92 0.37 1.63 D3 Site 4.29 0.15 0.19 200 3.00 16.81 16.12 0 0.50 PA 1.41 0.00 16.81 16.12 1.81 6.30 1.20 5.21 1 P1 0.89 0.60 0.75 100 2.00 7.23 5.09 100 0.50 GW 1.06 1.5713 8.80 6.66 2.40 9.31 1.27 6.18 2 P2 1.45 0.29 0.36 210 2.00 16.87 15.37 0 0.50 GW 1.06 0.0000 16.87 15.37 1.75 6.30 0.73 3.30 3 P3 0.53 0.69 0.87 26 3.00 2.60 1.49 90 0.50 PA 1.41 1.0607 5.00 5.00 2.85 9.95 1.05 4.57 4 P4 0.39 0.47 0.59 35 2.00 5.35 4.35 130 0.50 PA 1.41 1.5321 6.88 5.88 2.67 9.95 0.49 2.28 5 P5 0.07 0.83 1.00 10 2.00 1.23 0.45 0 0.50 GW 1.06 0.0000 5.00 5.00 2.85 9.95 0.17 0.70 - P6 0.83 0.15 0.18 200 2.00 19.40 18.66 0 0.50 GW 1.06 0.0000 19.40 18.66 1.65 5.92 0.20 0.89 - P7 0.13 0.10 0.13 60 15.00 5.72 5.58 0 0.50 GW 1.06 0.0000 5.72 5.58 2.85 9.95 0.04 0.16 Phase I Site 4.29 0.39 0.49 100 2.00 10.13 8.71 100 0.50 GW 1.06 1.5713 11.70 10.29 2.13 7.72 3.61 16.34 Phase II Full Site 4.29 0.53 0.66 100 2.00 8.17 6.26 100 0.50 GW 1.06 1.5713 9.74 7.83 2.30 8.80 5.24 25.07 Notes: HM = Heavy Meadow, TF = Tillage/field, PL = Short pasture and lawns, BG = Nearly bare ground, GW = Grassed Waterway, PA = Paved Areas Design Point Developed Existing Initial/Overland Time Final TC Intensity (in/hr) Basin Flows (cfs) Basin (s) Travel Time RJP Rational Method Flow Calculations.xlsx 10/14/2019 B. Hydraulic Computations Fort Collins Modified FAA Method Ponds 1-4 Stage-Storage Sizing for Detention Ponds Water Quality Capture Volume Calculation Restrictor Plate Calculation Outlet Calculations Infiltration Calculation Spillway Calculation Linear Bioretention Cross-Section A-A Swale Cross-Section B-B 2' Curb Cut Calculation Rip Rap Calculation Project: Fort Collins Montessori School Basin ID: Design Information Input: Detemination of MINOR Detention Volume Using Modified FAA Method: Detemination of MAJOR Detention Volume Using Modified FAA Method: Catchment Drainage Area A= 4.29 acres Catchment Drainage Area A= 4.29 acres Catchment Drainage Imperviousness Ia = 50 percent Catchment Drainage Imperviousness I a= 50 percent Return Period for Detention Control T= 2 years (2 or 100) Return Period for Detention Control T= 100 years (2 or 100) Time of Concentration of Watershed Tc= 10 minutes Time of Concentration of Watershed Tc= 8 minutes NRCS Soil Group Type= B A, B, C, or D NRCS Soil Group Type= B A, B, C, or D Allowable Unit Release Rate q= 0.018 cfs/acre Allowable Unit Release Rate q= 0.28 cfs/acre Runoff Coefficient C= 0.49 Runoff Coefficient C= 0.66 Inflow Peak Runoff Qp-in= 5.21 cfs Inflow Peak Runoff Qp-in= 28.35 cfs Allowable Peak Outflow Rate Qp-out= 0.08 cfs Allowable Peak Outflow Rate Qp-out= 1.20 cfs Modified FAA Minor Storage Volume= 6,864 cubic feet Modified FAA Major Storage Volume= 25,142 cubic feet Rainfall Rainfall Inflow Outflow Storage Rainfall Rainfall Inflow Outflow Storage Duration Intensity Volume Volume Volume Duration Intensity Volume Volume Volume minutes inches / hr cubic feet cubic feet cubic feet minutes inches / hr cubic feet cubic feet cubic feet (input) (output) (output) (output) (output) (input) (output) (output) (output) (output) 0 0.00 0 0 0 0 0.00 0 0 0 5 2.85 1,797 23 1,774 5 9.95 7,607 359 7,247 10 2.21 2,787 46 2,741 10 7.72 11,804 718 11,085 15 1.87 3,538 69 3,468 15 6.52 14,953 1,077 13,876 20 1.61 4,061 93 3,969 20 5.60 17,124 1,436 15,688 25 1.43 4,509 116 4,393 25 4.98 19,036 1,795 17,240 30 1.30 4,919 139 4,780 30 4.52 20,733 2,154 18,578 35 1.17 5,165 162 5,003 35 4.08 21,833 2,514 19,320 40 1.07 5,398 185 5,213 40 3.74 22,873 2,873 20,001 45 0.99 5,619 208 5,410 45 3.46 23,806 3,232 20,574 50 0.92 5,802 232 5,570 50 3.23 24,693 3,591 21,102 55 0.87 6,035 255 5,780 55 3.03 25,480 3,950 21,530 60 0.82 6,205 278 5,927 60 2.86 26,237 4,309 21,928 65 0.78 6,395 301 6,093 65 2.71 26,933 4,668 22,265 70 0.73 6,445 324 6,121 70 2.59 27,720 5,027 22,693 75 0.70 6,622 347 6,274 75 2.48 28,439 5,386 23,052 80 0.66 6,659 371 6,289 80 2.38 29,111 5,745 23,366 85 0.64 6,861 394 6,467 85 2.29 29,761 6,104 23,657 90 0.61 6,924 417 6,507 90 2.21 30,411 6,463 23,948 95 0.58 6,950 440 6,509 95 2.13 30,938 6,822 24,116 100 0.56 7,063 463 6,600 100 2.06 31,496 7,181 24,315 105 0.54 7,151 486 6,665 105 2.00 32,108 7,541 24,568 110 0.52 7,214 510 6,705 110 1.94 32,628 7,900 24,728 115 0.51 7,397 533 6,864 115 1.88 33,056 8,259 24,797 120 0.49 7,416 556 6,860 120 1.84 33,759 8,618 25,142 City of Fort Collins Modified FAA Method Project: Basin ID: Design Information (Input): Width of Basin Bottom, W = ft Right Triangle OR… Length of Basin Bottom, L = ft Isosceles Triangle OR… Dam Side-slope (H:V), Zd = ft/ft Rectangle OR… Circle / Ellipse OR… Irregular (Use Overide values in cells G32:G52) MINOR MAJOR Storage Requirement from Sheet 'Modified FAA': 0.09 0.54 acre-ft. Stage-Storage Relationship: Storage Requirement from Sheet 'Hydrograph': acre-ft. Storage Requirement from Sheet 'Full-Spectrum': acre-ft. Labels Water Side Basin Basin Surface Surface Volume Surface Volume Target Volumes for WQCV, Minor, Surface Slope Width at Length at Area at Area at Below Area at Below for WQCV, Minor, & Major Storage Elevation (H:V) Stage Stage Stage Stage Stage Stage Stage & Major Storage Stages ft ft/ft ft ft ft2 ft2 User ft3 acres acre-ft Volumes (input) (input) Below El. (output) (output) (output) Overide (output) (output) (output) (for goal seek) 5083.60 (input) 0 0.000 0.000 5084.00 0.00 0.00 263 53 0.006 0.001 5084.50 0.00 0.00 856 332 0.020 0.008 5085.00 0.00 0.00 1,353 885 0.031 0.020 5085.50 0.00 0.00 1,837 1,682 0.042 0.039 5086.00 0.00 0.00 2,348 2,728 0.054 0.063 5086.50 0.00 0.00 2,883 4,036 0.066 0.093 5087.00 0.00 0.00 3,444 5,618 0.079 0.129 5087.50 0.00 0.00 4,029 7,486 0.092 0.172 5088.00 0.00 0.00 4,640 9,653 0.107 0.222 5088.50 0.00 0.00 5,275 12,132 0.121 0.279 5088.60 0.00 0.00 5,405 12,666 0.124 0.291 100-YR 5089.10 0.00 0.00 5,070 15,285 0.116 0.351 5089.60 0.00 0.00 6,770 18,245 0.155 0.419 STAGE-STORAGE SIZING FOR DETENTION BASINS Fort Collins Montessori School Check Basin Shape Detention Pond 1 Detention Pond 1_v2.35.xls, Basin 10/14/2019, 4:57 PM Project: Basin ID: Design Information (Input): Width of Basin Bottom, W = ft Right Triangle OR… Length of Basin Bottom, L = ft Isosceles Triangle OR… Dam Side-slope (H:V), Zd = ft/ft Rectangle OR… Circle / Ellipse OR… Irregular (Use Overide values in cells G32:G52) MINOR MAJOR Storage Requirement from Sheet 'Modified FAA': 0.09 0.54 acre-ft. Stage-Storage Relationship: Storage Requirement from Sheet 'Hydrograph': acre-ft. Storage Requirement from Sheet 'Full-Spectrum': acre-ft. Labels Water Side Basin Basin Surface Surface Volume Surface Volume Target Volumes for WQCV, Minor, Surface Slope Width at Length at Area at Area at Below Area at Below for WQCV, Minor, & Major Storage Elevation (H:V) Stage Stage Stage Stage Stage Stage Stage & Major Storage Stages ft ft/ft ft ft ft2 ft2 User ft3 acres acre-ft Volumes (input) (input) Below El. (output) (output) (output) Overide (output) (output) (output) (for goal seek) 5086.10 (input) 0 0.000 0.000 5086.50 0.00 0.00 95 19 0.002 0.000 5087.00 0.00 0.00 190 90 0.004 0.002 5087.50 0.00 0.00 560 278 0.013 0.006 5088.00 0.00 0.00 924 649 0.021 0.015 5088.50 0.00 0.00 1,321 1,210 0.030 0.028 5088.60 0.00 0.00 1,404 1,346 0.032 0.031 100-YR 5089.10 0.00 0.00 1,837 2,157 0.042 0.050 5089.60 0.00 0.00 2,300 3,191 0.053 0.073 STAGE-STORAGE SIZING FOR DETENTION BASINS Fort Collins Montessori School Check Basin Shape Detention Pond 2 Detention Pond 2_v2.35.xls, Basin 10/14/2019, 4:01 PM Project: Basin ID: Design Information (Input): Width of Basin Bottom, W = ft Right Triangle OR… Length of Basin Bottom, L = ft Isosceles Triangle OR… Dam Side-slope (H:V), Zd = ft/ft Rectangle OR… Circle / Ellipse OR… Irregular (Use Overide values in cells G32:G52) MINOR MAJOR Storage Requirement from Sheet 'Modified FAA': 0.09 0.54 acre-ft. Stage-Storage Relationship: Storage Requirement from Sheet 'Hydrograph': acre-ft. Storage Requirement from Sheet 'Full-Spectrum': acre-ft. Labels Water Side Basin Basin Surface Surface Volume Surface Volume Target Volumes for WQCV, Minor, Surface Slope Width at Length at Area at Area at Below Area at Below for WQCV, Minor, & Major Storage Elevation (H:V) Stage Stage Stage Stage Stage Stage Stage & Major Storage Stages ft ft/ft ft ft ft2 ft2 User ft3 acres acre-ft Volumes (input) (input) Below El. (output) (output) (output) Overide (output) (output) (output) (for goal seek) 5084.95 (input) 0 0.000 0.000 5085.00 0.00 0.00 31 1 0.001 0.000 5085.50 0.00 0.00 374 102 0.009 0.002 5086.00 0.00 0.00 815 399 0.019 0.009 5086.50 0.00 0.00 1,249 915 0.029 0.021 5087.00 0.00 0.00 1,718 1,657 0.039 0.038 5087.50 0.00 0.00 2,220 2,642 0.051 0.061 5088.00 0.00 0.00 2,755 3,885 0.063 0.089 5088.60 0.00 0.00 3,442 5,744 0.079 0.132 100-YR 5089.60 0.00 0.00 4,676 9,803 0.107 0.225 STAGE-STORAGE SIZING FOR DETENTION BASINS Fort Collins Montessori School Check Basin Shape Detention Pond 3 Detention Pond 3_v2.35.xls, Basin 10/14/2019, 4:02 PM Project: Basin ID: Design Information (Input): Width of Basin Bottom, W = ft Right Triangle OR… Length of Basin Bottom, L = ft Isosceles Triangle OR… Dam Side-slope (H:V), Zd = ft/ft Rectangle OR… Circle / Ellipse OR… Irregular (Use Overide values in cells G32:G52) MINOR MAJOR Storage Requirement from Sheet 'Modified FAA': 0.09 0.54 acre-ft. Stage-Storage Relationship: Storage Requirement from Sheet 'Hydrograph': acre-ft. Storage Requirement from Sheet 'Full-Spectrum': acre-ft. Labels Water Side Basin Basin Surface Surface Volume Surface Volume Target Volumes for WQCV, Minor, Surface Slope Width at Length at Area at Area at Below Area at Below for WQCV, Minor, & Major Storage Elevation (H:V) Stage Stage Stage Stage Stage Stage Stage & Major Storage Stages ft ft/ft ft ft ft2 ft2 User ft3 acres acre-ft Volumes (input) (input) Below El. (output) (output) (output) Overide (output) (output) (output) (for goal seek) 5086.70 (input) 0 0.000 0.000 5087.00 0.00 0.00 130 20 0.003 0.000 5087.50 0.00 0.00 1,437 411 0.033 0.009 5088.00 0.00 0.00 5,188 2,068 0.119 0.047 5088.60 0.00 0.00 7,309 5,817 0.168 0.134 100-YR 5089.60 0.00 0.00 9,152 14,047 0.210 0.322 STAGE-STORAGE SIZING FOR DETENTION BASINS Fort Collins Montessori School Check Basin Shape Detention Pond 4 Detention Pond 4_v2.35.xls, Basin 10/14/2019, 4:04 PM Project: Basin ID: Design Information (Input): Width of Basin Bottom, W = ft Right Triangle OR… Length of Basin Bottom, L = ft Isosceles Triangle OR… Dam Side-slope (H:V), Zd = ft/ft Rectangle OR… Circle / Ellipse OR… Irregular (Use Overide values in cells G32:G52) MINOR MAJOR Storage Requirement from Sheet 'Modified FAA': 0.10 0.54 acre-ft. Stage-Storage Relationship: Storage Requirement from Sheet 'Hydrograph': acre-ft. Storage Requirement from Sheet 'Full-Spectrum': acre-ft. Labels Water Side Basin Basin Surface Surface Volume Surface Volume Target Volumes for WQCV, Minor, Surface Slope Width at Length at Area at Area at Below Area at Below for WQCV, Minor, & Major Storage Elevation (H:V) Stage Stage Stage Stage Stage Stage Stage & Major Storage Stages ft ft/ft ft ft ft2 ft2 User ft3 acres acre-ft Volumes (input) (input) Below El. (output) (output) (output) Overide (output) (output) (output) (for goal seek) 5083.60 (input) 0 0.000 0.000 5084.00 0.00 0.00 263 53 0.006 0.001 5084.50 0.00 0.00 856 332 0.020 0.008 5085.00 0.00 0.00 1,384 892 0.032 0.020 5085.50 0.00 0.00 2,211 1,791 0.051 0.041 5086.00 0.00 0.00 3,163 3,135 0.073 0.072 5086.50 0.00 0.00 4,227 4,982 0.097 0.114 5087.00 0.00 0.00 5,482 7,409 0.126 0.170 WQCV 5087.50 0.00 0.00 8,246 10,841 0.189 0.249 5088.00 0.00 0.00 13,507 16,280 0.310 0.374 5088.60 0.00 0.00 17,560 25,600 0.403 0.588 100-YR 5089.60 0.00 0.00 22,898 45,829 0.526 1.052 STAGE-STORAGE SIZING FOR DETENTION BASINS Fort Collins Montessori School Check Basin Shape Detention Pond System Detention Pond Outlet Design File_v2.35.xls, Basin 10/14/2019, 4:07 PM Project: Basin ID: WQCV Design Volume (Input): Catchment Imperviousness, Ia = 50.0 percent Catchment Area, A = 4.29 acres Diameter of holes, D = 0.820 inches Depth at WQCV outlet above lowest perforation, H = 3 feet Number of holes per row, N = 1 Vertical distance between rows, h = 12.00 inches OR Number of rows, NL = 3.00 Orifice discharge coefficient, Co = 0.60 Height of slot, H = inches Slope of Basin Trickle Channel, S = 0.010 ft / ft Width of slot, W = inches Time to Drain the Pond = 40 hours Watershed Design Information (Input): 3.4 Percent Soil Type A = 0 % Percent Soil Type B = 100 % Percent Soil Type C/D = 0 % Outlet Design Information (Output): Water Quality Capture Volume, WQCV = 0.229 watershed inches Water Quality Capture Volume (WQCV) = 0.082 acre-feet 0.00 Design Volume (WQCV / 12 * Area * 1.2) Vol = 0.098 acre-feet Outlet area per row, Ao = 0.53 square inches Total opening area at each row based on user-input above, Ao = 0.53 square inches Total opening area at each row based on user-input above, Ao = 0.004 square feet 3 Row 1 Row 2 Row 3 Row 4 Row 5 Row 6 Row 7 Row 8 Row 9 Row 10 Row 11 Row 12 Row 13 Row 14 Row 15 Row 16 Row 17 Row 18 Row 19 Row 20 Row 21 Row 22 Row 23 Row 23 ΣΣΣΣ 5083.60 5084.60 5085.60 Flow 5083.60 0.0000 0.0000 0.0000 0.00 5084.00 0.0112 0.0000 0.0000 0.01 5084.50 0.0168 0.0000 0.0000 0.02 5085.00 0.0244 0.0168 0.0000 0.04 5085.50 0.0274 0.0209 0.0112 0.06 5086.00 0.0274 0.0209 0.0112 0.06 5086.50 0.0301 0.0244 0.0168 0.07 5087.00 0.0326 0.0274 0.0209 0.08 5087.50 0.0349 0.0301 0.0244 0.09 5088.00 0.0371 0.0326 0.0274 0.10 5088.60 0.0395 0.0353 0.0306 0.11 5089.60 0.0433 0.0395 0.0353 0.12 Central Elevations of Rows of Holes in feet Collection Capacity for Each Row of Holes in cfs STAGE-DISCHARGE SIZING OF THE WATER QUALITY CAPTURE VOLUME (WQCV) OUTLET Fort Collins Montessori School Detention Pond System Detention Pond Outlet Design File_v2.35.xls, WQCV 10/14/2019, 4:13 PM Project: Basin ID: X 1 #1 Vertical #2 Vertical Sizing the Restrictor Plate for Circular Vertical Orifices or Pipes (Input) Orifice Orifice Water Surface Elevation at Design Depth Elev: WS = 5,088.60 feet Pipe/Vertical Orifice Entrance Invert Elevation Elev: Invert = 5,083.60 feet Required Peak Flow through Orifice at Design Depth Q = 1.20 cfs Pipe/Vertical Orifice Diameter (inches) Dia = 18.0 inches Orifice Coefficient Co = 0.60 Full-flow Capacity (Calculated) Full-flow area Af = 1.77 sq ft Half Central Angle in Radians Theta = 3.14 rad Full-flow capacity Qf = 17.5 cfs Percent of Design Flow = 1462% Calculation of Orifice Flow Condition Half Central Angle (0<Theta<3.1416) Theta = 0.69 rad Flow area Ao = 0.11 sq ft Top width of Orifice (inches) To = 11.49 inches Height from Invert of Orifice to Bottom of Plate (feet) Yo = 0.17 feet Elevation of Bottom of Plate Elev Plate Bottom Edge = 5,083.77 feet Resultant Peak Flow Through Orifice at Design Depth Qo = 1.2 cfs Width of Equivalent Rectangular Vertical Orifice Equivalent Width = 0.65 feet Centroid Elevation of Equivalent Rectangular Vertical Orifice Equiv. Centroid El. = 5,083.69 feet Fort Collins Montessori School Detention Pond System RESTRICTOR PLATE SIZING FOR CIRCULAR VERTICAL ORIFICES Detention Pond Outlet Design File_v2.35.xls, Restrictor Plate 10/14/2019, 4:14 PM Project: Basin ID: Design Information (Input): #1 Horiz. #2 Horiz. #1 Vert. #2 Vert. Circular Opening: Diameter in Inches Dia. = inches OR Rectangular Opening: Width in Feet W = 3.00 0.65 ft. Length (Height for Vertical) L or H = 3.00 0.17 ft. Percentage of Open Area After Trash Rack Reduction % open = 50 100 % Orifice Coefficient Co = 0.67 0.60 Weir Coefficient Cw = 3.00 Orifice Elevation (Bottom for Vertical) Eo = 5087.00 5,083.60 ft. Calculation of Collection Capacity: Net Opening Area (after Trash Rack Reduction) Ao = 4.50 0.11 sq. ft. OPTIONAL: User-Overide Net Opening Area Ao = sq. ft. Perimeter as Weir Length Lw = 9.00 ft. OPTIONAL: User-Overide Weir Length Lw = ft. Top Elevation of Vertical Orifice Opening, Top = 5083.77 ft. Center Elevation of Vertical Orifice Opening, Cen = 5083.69 ft. Horizontal Orifices Vertical Orifices Labels Water WQCV #1 Horiz. #1 Horiz. #2 Horiz. #2 Horiz. #1 Vert. #2 Vert. Total Target Volumes for WQCV, Minor, Surface Plate/Riser Weir Orifice Weir Orifice Collection Collection Collection for WQCV, Minor, & Major Storage Elevation Flow Flow Flow Flow Flow Capacity Capacity Capacity & Major Storage W.S. Elevations ft cfs cfs cfs cfs cfs cfs cfs cfs Volumes (input) (linked) (User-linked) (output) (output) (output) (output) (output) (output) (output) (link for goal seek) 5083.60 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 5084.00 0.01 0.00 0.00 0.00 0.00 0.30 0.00 0.01 5084.50 0.02 0.00 0.00 0.00 0.00 0.48 0.00 0.02 5085.00 0.04 0.00 0.00 0.00 0.00 0.61 0.00 0.04 5085.50 0.06 0.00 0.00 0.00 0.00 0.71 0.00 0.06 5086.00 0.06 0.00 0.00 0.00 0.00 0.81 0.00 0.06 5086.50 0.07 0.00 0.00 0.00 0.00 0.89 0.00 0.07 5087.00 0.08 0.00 0.00 0.00 0.00 0.96 0.00 0.08 WQCV 5087.50 0.09 9.55 17.11 0.00 0.00 1.03 0.00 1.03 5088.00 0.10 27.00 24.20 0.00 0.00 1.10 0.00 1.10 5088.60 0.11 54.64 30.60 0.00 0.00 1.17 0.00 1.17 100-Year 5089.60 0.12 113.19 39.01 0.00 0.00 1.29 0.00 1.29 Routing 3: Single Stage - Water flows through WQCV plate and #1 horizontal opening into #1 vertical opening. This flow will be applied to culvert sheet (#2 vertical & horizontal openings is not used). STAGE-DISCHARGE SIZING OF THE WEIRS AND ORIFICES (INLET CONTROL) Fort Collins Montessori School Detention Pond System Current Routing Order is #3 W.S. EL. WQ W.S. EL. Minor W.S. EL. Major WQ H1 H2 V1 V2 Routing Order #1 (Standard) V1 W.S. EL. WQ W.S. EL. Design Storm Project: Basin ID: Design Information (input): Bottom Length of Weir L = 8.00 feet Angle of Side Slope Weir Angle = 45.00 degrees Elev. for Weir Crest EL. Crest = 5,088.60 feet Coef. for Rectangular Weir Cw = 2.50 Coef. for Trapezoidal Weir Ct = 2.20 Calculation of Spillway Capacity (output): Water Rect. Triangle Total Total Surface Weir Weir Spillway Pond Elevation Flowrate Flowrate Release Release ft. cfs cfs cfs cfs (linked) (output) (output) (output) (output) 5083.60 0.00 0.00 0.00 0.00 5084.00 0.00 0.00 0.00 0.00 5084.50 0.00 0.00 0.00 0.00 5085.00 0.00 0.00 0.00 0.00 5085.50 0.00 0.00 0.00 0.00 5086.00 0.00 0.00 0.00 0.00 5086.50 0.00 0.00 0.00 0.00 5087.00 0.00 0.00 0.00 0.00 5087.50 0.00 0.00 0.00 0.00 5088.00 0.00 0.00 0.00 0.00 5088.60 0.00 0.00 0.00 0.00 5089.60 20.00 2.20 22.20 22.20 STAGE-DISCHARGE SIZING OF THE SPILLWAY Fort Collins Montessori School Detention Pond System Detention Pond Outlet Design File_v2.35.xls, Spillway 10/14/2019, 4:15 PM Channel Report Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Tuesday, Oct 1 2019 Linear Bioretention Trapezoidal Bottom Width (ft) = 2.00 Side Slopes (z:1) = 8.00, 8.00 Total Depth (ft) = 0.50 Invert Elev (ft) = 5089.65 Slope (%) = 0.50 N-Value = 0.035 Calculations Compute by: Known Q Known Q (cfs) = 1.39 Highlighted Depth (ft) = 0.31 Q (cfs) = 1.390 Area (sqft) = 1.39 Velocity (ft/s) = 1.00 Wetted Perim (ft) = 7.00 Crit Depth, Yc (ft) = 0.20 Top Width (ft) = 6.96 EGL (ft) = 0.33 0 1 2 3 4 5 6 7 8 9 10 11 12 Elev (ft) Depth (ft) Section 5089.00 -0.65 5089.50 -0.15 5090.00 0.35 5090.50 0.85 5091.00 1.35 Reach (ft) Channel Report Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Friday, Oct 4 2019 Swale Cross Section Triangular Side Slopes (z:1) = 12.00, 6.00 Total Depth (ft) = 1.50 Invert Elev (ft) = 5090.72 Slope (%) = 1.00 N-Value = 0.030 Calculations Compute by: Known Q Known Q (cfs) = 3.30 Highlighted Depth (ft) = 0.45 Q (cfs) = 3.300 Area (sqft) = 1.82 Velocity (ft/s) = 1.81 Wetted Perim (ft) = 8.16 Crit Depth, Yc (ft) = 0.39 Top Width (ft) = 8.10 EGL (ft) = 0.50 0 5 10 15 20 25 30 35 40 Elev (ft) Depth (ft) Section 5090.00 -0.72 5090.50 -0.22 5091.00 0.28 5091.50 0.78 5092.00 1.28 5092.50 1.78 5093.00 2.28 Reach (ft) Channel Report Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Monday, Oct 14 2019 2 Foot Curb Cut Rectangular Bottom Width (ft) = 2.00 Total Depth (ft) = 0.50 Invert Elev (ft) = 5090.38 Slope (%) = 3.00 N-Value = 0.013 Calculations Compute by: Known Q Known Q (cfs) = 6.18 Highlighted Depth (ft) = 0.38 Q (cfs) = 6.180 Area (sqft) = 0.76 Velocity (ft/s) = 8.13 Wetted Perim (ft) = 2.76 Crit Depth, Yc (ft) = 0.50 Top Width (ft) = 2.00 EGL (ft) = 1.41 0 .5 1 1.5 2 2.5 3 Elev (ft) Depth (ft) Section 5090.00 -0.38 5090.25 -0.13 5090.50 0.12 5090.75 0.37 5091.00 0.62 Reach (ft) Q = Flow from Basin Basin Q= 6.18 cfs A= 0.760 ft2 S = Channel Slope: ft/ft S= 0.03 ft/ft V = Velocity of Flow: ft/s V = 8.13 ft/s Gs = Specific Gravity (2.5 default if not known) Gs = 2.5 Type D50 (in) VL < 3.3 6 L ≥ 3.3 - < 4.0 9 = 3.43 M ≥ 4.0 - < 4.6 12 H ≥ 4.6 - < 5.6 18 VH ≥ 5.6 - 6.4 24 Type = VL D50 = 6 in Grouted YES Rip Rap Protection Fort Collins Montessori School The minimum mean particle size (intermediate dimension) by weigth for riprap, commonly known as the D50, is six (6) inches. Riprap Size Riprap Type Input Design Parameters 4.4.4.3. Riprap Specifications and Applicability = (�� .�� )/ �� − 1 �.�� (�� .�� )/ �� − 1 �.�� C. Map Pocket Drainage Plan Outlet Structure Detail ONLY N UTILITY PLANS FOR FORT COLLINS MONTESSORI SCHOOL ENGINEERING & SURVEYING 4045 St. Cloud Drive, Suite 180 Loveland, CO 80538 [P] 970-622-2095 [F] 970-461-4469 1109 W HARMONY ROAD NE1 4 OF SECTION 3, T6N, R69W, 6TH P.M., CITY OF FORT COLLINS, COUNTY OF LARIMER, STATE OF COLORADO DWG. NAME 15 NO. REVISION DATE SHEET NO. OF PROJECT: DATE: DESIGNER: DRAFTER: CHECKED BY: APPROVED BY: 2259.03 09/07/18 TWC TWC NOT FOR CONSTRUCTION PRELIMINARY Know what's below. Call before you dig. R BENCHMARK STATEMENT LEGEND: DRAINAGE & EROSION CONTROL PLAN C-11 11 ___ ___ CITY OF FORT COLLINS, COLORADO UTILITY PLAN APPROVAL PROPOSED BASIN FLOWS STANDARD EROSION AND SEDIMENT CONSTRUCTION PLAN NOTES EROSION BMP LEGEND DETENTION SUMMARY UTILITY PLANS FOR FORT COLLINS MONTESSORI SCHOOL ENGINEERING & SURVEYING 4045 St. Cloud Drive, Suite 180 Loveland, CO 80538 [P] 970-622-2095 [F] 970-461-4469 1109 W HARMONY ROAD NE1 4 OF SECTION 3, T6N, R69W, 6TH P.M., CITY OF FORT COLLINS, COUNTY OF LARIMER, STATE OF COLORADO DWG. NAME 15 NO. REVISION DATE SHEET NO. OF PROJECT: DATE: DESIGNER: DRAFTER: CHECKED BY: APPROVED BY: 2259.03 09/07/18 TWC TWC NOT FOR CONSTRUCTION PRELIMINARY Know what's below. Call before you dig. R DETAIL SHEET 4 C-15 15 RJP RJP DETAIL NOT TO SCALE SECTION C SECTION B SECTION A WATER QUALITY OUTLET STRUCTURE - PLAN VIEW EARTHEN SPILLWAY ELEVATION DR-1A WATER QUALITY OUTLET STRUCTURE DETAIL WQ H1 Routing Order #3 (Single Stage) Routing Order #4 V2 V1 H1 WQ W.S. EL. Major W.S. EL. Minor W.S. EL. WQ W.S. EL. Emergency Spillway Emergency Overflow into Pipe- H2 V2 H1 WQ W.S. EL. Major W.S. EL. Minor W.S. EL. WQ V1 Routing Order #2 Detention Pond Outlet Design File_v2.35.xls, Outlet 10/14/2019, 4:14 PM 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 accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Larimer County Area, Colorado Survey Area Data: Version 13, Sep 10, 2018 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Aug 11, 2018—Aug 12, 2018 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Soil Map—Larimer County Area, Colorado Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 8/28/2019 Page 2 of 3