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HomeMy WebLinkAboutBOARDWALK OFFICE BUILDING - FDP - FDP180001 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTFINAL DRAINAGE REPORT Boardwalk Office Building Prepared for: r4 Architects 226 Remington Street, Unit #3 Fort Collins, CO 80528 (970) 224-0630 Prepared by: Interwest Consulting Group 1218 West Ash, Suite A Windsor, Colorado 80550 (970) 674-3300 January 17, 2018 Job Number 1326-069-00 iii TABLE OF CONTENTS TABLE OF CONTENTS ............................................................................................................ iii 1. GENERAL LOCATION AND DESCRIPTION ................................................................ 1 1.1 Location ........................................................................................................................... 1 1.2 Description of Property ................................................................................................. 1 1.3 Floodplain Submittal Requirements ............................................................................. 1 2. DRAINAGE BASINS AND SUB-BASINS .......................................................................... 2 2.1 Major Basin Description ................................................................................................ 2 2.2 Sub-basin Description .................................................................................................... 2 3. DRAINAGE DESIGN CRITERIA ...................................................................................... 2 3.1 Regulations ...................................................................................................................... 2 3.2 Directly Connected Impervious Area (DCIA) Discussion .......................................... 2 3.3 Development Criteria Reference and Constraints ...................................................... 4 3.4 Hydrological Criteria ..................................................................................................... 4 3.5 Hydraulic Criteria .......................................................................................................... 4 3.6 Floodplain Regulations Compliance ............................................................................. 4 3.7 Modifications of Criteria ............................................................................................... 5 4. DRAINAGE FACILITY DESIGN ....................................................................................... 5 4.1 General Concept ............................................................................................................. 5 4.2 Specific Details ................................................................................................................ 6 5. CONCLUSIONS .................................................................................................................... 7 5.1 Compliance with Standards .......................................................................................... 7 5.2 Drainage Concept ........................................................................................................... 7 6. REFERENCES ...................................................................................................................... 8 APPENDIX VICINITY MAP AND DRAINAGE PLAN .............................................................................. A HYDROLOGIC COMPUTATIONS .......................................................................................... B HYDRAULIC COMPUTATIONS .............................................................................................. C WATER QUALITY AND LID INFORMATION .................................................................... D SOILS INFO, FEMA INFO, AND REFERENCE MATERIAL .............................................. E 1 1. GENERAL LOCATION AND DESCRIPTION 1.1 Location The Boardwalk Office Building development is located in Fort Collins. It is located in the Northwest Quarter of Section 36, Township 7 North, Range 69 West of the Sixth Principal Meridian, in the City of Fort Collins, Larimer County, Colorado. Please refer to the vicinity map in Appendix A. The project site is located at the northeast corner of JFK Parkway and Boardwalk Drive. JFK Parkway bounds the property on the west, Boardwalk Drive on the south, Tract 9, Block 1 of Landings Office Park PUD on the east and Landings Bay FDP on the north. The development consists of Tracts 8 and 10, Block 2 of Landings Office Park PUD. 1.2 Description of Property The property consists of 0.55 acres of land. The project will include construction of a new building, sidewalks and new parking with drive aisles. The proposed development is very similar to the original approved 1995 design of the property. The site generally slopes in a southerly direction at approximately 5% to 7%. The land is currently vacant. There is no offsite flow contributing to the site. Soils on site consist of Tassel sandy loam, 3 to 25 percent slopes classified as Type D hydrologic soil group. According to FEMA Panel 08069C0987G (effective 05/02/2012) there are no mapped FEMA Floodways on this property. Please refer to Appendix E for hydrologic soil and FEMA information. 1.3 Floodplain Submittal Requirements Because the project is not within any FEMA or City of Fort Collins mapped floodway, a Floodplain Submittal is not required and a “City of Fort Collins Floodplain Review Checklist for 50% Submittals” has not been included with this report. 2 2. DRAINAGE BASINS AND SUB-BASINS 2.1 Major Basin Description The proposed development lies within the Mail Creek Master Drainage Plan. Outfall for this site is the Larimer County Canal No. 2. The site was previously studied in the “Final Drainage Report for Landings Office Park P.U.D.” by Northern Engineering Services, Inc., dated October 27, 1995 (Landings PUD). Please refer to Appendix E for reference material. 2.2 Sub-basin Description Today, the entire site sheet flows onto JFK Parkway and Boardwalk Drive where the curb and gutter conveys the flow to either the East Detention Pond of ShopKo or Detention Pond D1 of the Landings PUD located at the northwest corner of Boardwalk Drive and Landings Drive. 3. DRAINAGE DESIGN CRITERIA 3.1 Regulations This report was prepared to meet or exceed the “City of Fort Collins Storm Drainage Design Criteria Manual” specifications. Where applicable, the criteria established in the “Urban Storm Drainage Criteria Manual” (UDFCD), developed by the Denver Regional Council of Governments, has been used. 3.2 Directly Connected Impervious Area (DCIA) Discussion Urban Drainage and Flood Control District (UDFCD) recommends a Four Step Process for receiving water protection that focuses on reducing runoff volumes, treating the water quality capture volume (WQCV), stabilizing drainageways and implementing long-term source controls. The Four Step Process applies to the management of smaller, frequently occurring events. 3 Step 1: Employ Runoff Reduction Practices To reduce runoff peaks, volumes, and pollutant loads from urbanizing areas, implement Low Impact Development (LID) strategies, including Minimizing Directly Connected Impervious Areas (MDCIA). Runoff for the eastern portion of the site will be routed through vegetated areas through sheet flow thereby reducing runoff from impervious surfaces over permeable areas to slow runoff and increase the time of concentration and promote infiltration. Runoff from the parking lot and the eastern portion of the building shall drain directly into a porous pavement system thereby slowing runoff and also promoting infiltration. Runoff from the western portion of the building roof shall drain directly to a storm system that will release to a swale that will slow runoff and increase the time of concentration and promote infiltration. Step 2: Implement BMPs that Provide a Water Quality Capture Volume with Slow Release Once runoff has been minimized, the remaining runoff shall be treated through the porous pavement system that allows for settlement of sediments. Step 3: Stabilize Drainageways Natural Drainageways are subject to bed and bank erosion due to increases in frequency, duration, rate and volume of runoff during and following development. Because the site will drain to an existing detention pond, bank stabilization is unnecessary with this project. Step 4: Implement Site Specific and Other Source Control BMPs The proposed development will provide the porous pavement system feature which will eliminate pollution that had previously been exposed during weathering and runoff processes. The proposed project will proactively control pollutants at their source by preventing pollution rather than removing contaminants once they have entered the stormwater system as compared to historic conditions. 4 3.3 Development Criteria Reference and Constraints The runoff from this site has been routed to conform to the requirements of the City Stormwater Department. Because water quality capture volume from this site is not included in the development’s detention pond, water quality facilities are required for the new construction proposed on the site. The site’s water quality will be met through the use of a porous pavement system that includes 12” of storage in the voids below the pavers. Please note that a portion of the site (Basin D) drains directly to JFK and Boardwalk as shown on the previously approved Landings PUD. This design matches the previously approved condition. 3.4 Hydrologic Criteria Runoff computations were prepared for the 2-year and 10-year minor and 100-year major storm frequency utilizing the rational method. All hydrologic calculations associated with the basins are included in Appendix B of this report. Standard Form 8 (SF-8) provides time of concentration calculations for all sub- basins. Standard Form 9 (SF-9) provides a summary of the design flows for all Sub- basins and Design Points associated with this site. A variance to use the porous pavement system for the water quality capture volume is included in Appendix D. 3.5 Hydraulic Criteria All hydraulic calculations will be presented in the final drainage report and prepared in accordance with the City of Fort Collins Drainage Criteria. 3.6 Floodplain Regulations Compliance The project is not within any FEMA or City of Fort Collins mapped floodway; therefore, Floodplain Regulations Compliance is not required. 5 3.7 Modifications of Criteria The site has been designed to maximize water quality treatment but the handicap ramp area to Boardwalk and the west and south side of the site cannot drain to the porous pavement system. The entire site’s required water quality capture volume is 0.01 ac-ft and will be contained in the 12” of storage in the voids below the pavers. Please refer to Appendix D for supporting information regarding water quality. If the porous pavement system is completely saturated or overwhelmed, water will overtop into the Type R inlet then be conveyed east to the existing Detention Pond D1 of the Landings PUD. Runoff reduction practices (LID techniques) are also required. No less than fifty percent of any newly added impervious area must be treated using one or a combination of LID techniques. New impervious area is 16,449 sf. Basins A and B contain the porous paver system. Using this LID technique, 15,560 sf of new impervious area (95%) will be treated which exceeds the 50% requirement. No less than twenty five percent of any newly added pavement areas must be treated using a permeable pavement technology. The project adds 10,434 sf of new pavement area. This project will incorporate 3,790sf of porous pavers which is 36% of the newly added pavement which exceeds the required 25%. The porous pavement system is oversized and provides full water quality volume for the site. Please refer to Appendix D for LID calculations and information. 4. DRAINAGE FACILITY DESIGN 4.1 General Concept The majority of the proposed development will be collected and conveyed to the proposed storm drain system where it will be treated for water quality via a porous pavement system before being released into the proposed system that conveys water east to the existing Pond D1 of the Landings PUD. 6 4.2 Specific Details A summary of the drainage patterns within each basin is provided in the following paragraphs. Please refer to Appendix A for the drainage plan. Basin A is 0.09 acres and contains the north drive aisle and parking. This basin is calculated to have a 10-year discharge of 0.4 cfs and a 100-year discharge of 0.9 cfs. Flows from Basin A are captured by the porous paver system and will discharge to the 8- inch storm pipe around the north and east sides of the site. This system releases the treated water into the 5’ Type R inlet and 12-inch storm pipe located at design point B. Basin B is 0.26 acres, contains about 60 percent the roof (east portion) and the east drive aisle and parking. This basin is calculated to have a 10-year discharge of 1.0 cfs and a 100-year discharge of 2.5 cfs. Flows from Basin B are captured by the porous paver system. The treated water is released into the 5’ Type R inlet and 12-inch storm pipe located at design point B. Basin C is 0.04 acres and contains the remainder of the roof (about 40%). The basin is calculated to have a 10-year discharge of 0.2 cfs and a 100-year discharge of 0.4 cfs. Flows from this basin will be conveyed to the 6-inch perimeter drain that wraps around the west and south of the building. This drain will release flow to the sidewalk chase located on the southeast side of the building. This chase will direct the flow to Basin B’s porous paver system for treatment. The treated water is released into the same 5’ Type R inlet located at design point B and is then released to an outfall swale that conveys flow to the existing pond. 100 percent of the roof is treated in the porous paver system. Basin D is 0.13 acres and is calculated to have a 10-year discharge of 0.2 cfs and a 100- year discharge of 0.4 cfs. This basin consists of the west and south landscape area adjacent to the building. Flows from this basin will continue current conditions and sheet flow onto JFK Parkway and remains untreated and as was planned in the Landings PUD approved drainage plan. 7 Basin E is 0.03 acres and is calculated to have a 10-year discharge of 0.1 cfs and a 100- year discharge of 0.2 cfs. This basin consists of the handicap ramp adjacent to the north side of the building. Flows from this basin will drain to a sump inlet and the 8-inch storm pipe around the north and east sides of the site. This system releases the untreated water into the 5’ Type R inlet and 12-inch storm pipe located at design point B. The percent impervious weighted average of the entire site is 58% which is below the 70% imperviousness that was assumed in the approved Landings PUD; therefore, detention is not required. Please refer to Appendix E for excerpts from this drainage report. 5. CONCLUSIONS 5.1 Compliance with Standards All computations that have been completed within this report are in compliance with the City of Fort Collins Storm Drainage Design Criteria Manual. 5.2 Drainage Concept The proposed drainage concepts presented in this report and on the construction plans adequately provides for stormwater quantity and quality treatment of proposed impervious areas. Conveyance elements have been designed to pass required flows and to minimize future maintenance. If, at the time of construction, groundwater is encountered, a Colorado Department of Health Construction Dewatering Permit will be required. 8 6. REFERENCES 1. City of Fort Collins, “Fort Collins Stormwater Criteria Manual Amendments to the Urban Drainage and Flood Control District Criteria Manual”, adopted December 2011. 2. Urban Drainage and Flood Control District, “Urban Storm Drainage Criteria Manual”, Volumes 1 and 2, dated June 2001, and Volume 3 dated November 2010. 3. Northern Engineering Services, Inc., “Final Drainage Report for Landings Office Park P.U.D.”, dated October 27, 1995. A APPENDIX A VICINITY MAP AND DRAINAGE PLAN B APPENDIX B HYDROLOGIC COMPUTATIONS SUMMARY DRAINAGE SUMMARY TABLE Design Tributary Area C (10) C (100) tc (10) tc (100) Q(2)tot Q(10)tot Q(100)tot Sub-basin REMARKS Point (ac) (min) (min) (cfs) (cfs) (cfs) A A 0.09 0.81 1.00 5.0 5.0 0.2 0.4 0.9 PERVIOUS PAVER SYSTEM B B 0.26 0.77 0.96 5.0 5.0 0.6 1.0 2.5 PERVIOUS PAVER SYSTEM C C 0.04 0.83 1.00 5.0 5.0 0.1 0.2 0.4 TO 6" ROOF DRAIN SYSTEM TO PERVIOUS PAVER SYSTEM D D 0.13 0.26 0.32 5.0 5.0 0.1 0.2 0.4 FLOWS TO JFK AND BOARDWALK - PART OF LANDINGS D3 E E 0.03 0.50 0.63 5.7 5.0 0.0 0.1 0.2 TO 24" ADS AREA INLET E A+E 0.12 0.74 0.93 5.0 5.0 0.3 0.4 1.1 TO 8" PERIMETER DRAIN B B+C 0.30 0.77 0.97 5.0 5.0 0.7 1.1 2.9 TO 18" PIPE AND TO POND Page 7 Interwest Consulting Group RUNOFF COEFFICIENTS & % IMPERVIOUS LOCATION: Boardwalk and JFK PROJECT NO: 1326-069-00 COMPUTATIONS BY: MO DATE: 10/17/2017 Recommended Runoff Coefficients from Table RO-11 of City of Fort Collins Stormwater Code, Volume I Recommended % Impervious from Table RO-3 Urban Storm Drainage Criteria Manual, Volume I Type B Soils Runoff % coefficient Impervious C Streets, parking lots (asphalt): 0.95 100 Sidewalks (concrete): 0.95 96 Roofs: 0.95 90 Gravel or Pavers: 0.50 40 Landscape Areas (Flat, heavy) : 0.20 0 Landscape Areas (Steep, heavy) : 0.35 0 SUBBASIN TOTAL TOTAL ROOF PAVED PAVERS SIDEWALK LANDSCAPE RUNOFF % DESIGNATION AREA AREA AREA AREA AREA AREA AREA COEFF. Impervious REMARKS (ac.) (sq.ft) (sq.ft) (sq.ft) (sq.ft) (sq.ft) (sq.ft) (C) LANDINGS D5 0.45 19,602 7,492 7,013 0 0 5,097 0.76 70 LANDINGS D7 0.19 8,059 0 5,706 0 0 2,352 0.73 71 A 0.09 4,071 0 2,642 989 297 143 0.81 82 PERVIOUS PAVER SYSTEM B 0.26 11,369 2,375 4,003 2,801 1,094 1,097 0.77 73 PERVIOUS PAVER SYSTEM C 0.04 1,625 1,360 0 0 0 265 0.83 75 TO 6" ROOF DRAIN SYSTEM TO PERVIOUS PAVER SYSTEM D 0.13 5,556 0 0 0 408 5,148 0.26 7 FLOWS TO JFK AND BOARDWALK - PART OF LANDINGS D3 E 0.03 1,198 0 0 0 481 717 0.50 39 TO 24" ADS AREA INLET A+E 0.12 5,269 0 2,642 989 778 861 0.74 72 TO 8" PERIMETER DRAIN B+C 0.30 12,994 3,734 4,003 2,801 1,094 1,363 0.77 73 UNDERDRAIN TO 18" PIPE AND TO POND D+E 0.16 6,754 0 0 0 889 5,865 0.30 13 FLOWS TO JFK AND BOARDWALK - PART OF LANDINGS D3 A+B+C+E 0.42 18,263 3,734 6,645 3,790 1,871 2,223 0.77 73 FLOWS TO STORM SYSTEM A+B+C+D+E 0.55 23,820 3,734 6,645 3,790 2,280 7,371 0.65 58 FOR ON SITE LID CALCULATIONS Equations - Calculated C coefficients & % Impervious are area weighted C = Σ (Ci Ai) / At Ci = runoff coefficient for specific area, Ai Ai = areas of surface with runoff coefficient of Ci n = number of different surfaces to consider At = total area over which C is applicable; the sum of all Ai's Worksheet in 1326-069-00 DR.dwg Interwest Consulting Group STANDARD FORM SF-2 TIME OF CONCENTRATION - 2 and 10 YR LOCATION: Boardwalk and JFK PROJECT NO: 1326-069-00 COMPUTATIONS BY: MO DATE: 10/17/2017 2 and 10-yr storm Cf = 1.00 from Table RO-12 of City of Fort Collins Stormwater Code, Volume I SUB-BASIN INITIAL /OVERLAND TRAVEL TIME / GUTTER OR CHANNEL FLOW tc CHECK FINAL REMARKS DATA TIME (ti) (tt) (URBANIZED BASIN) tc DESIGN SUBBASIN(s) Area C Length Slope ti Length Slope n Vel. tt tc = Total L tc=(l/180)+10 PONIT (ac) (ft) (%) (min) (ft) (%) Manning (ft/s) (min) ti + tt (ft) (min) (min) (1) (2) (3) (4) (5) (6) (7) (8) rough. (9) (10) (11) (12) (13) (14) A A 0.09 0.81 40 3.6 2.2 48 5.0 0.016 4.5 0.2 2.4 88 10.5 5.0 PERVIOUS PAVER SYSTEM B B 0.26 0.77 45 5.0 2.4 140 2.5 0.016 3.2 0.7 3.2 185 11.0 5.0 PERVIOUS PAVER SYSTEM C C 0.04 0.83 14 2.0 1.5 1 2.0 0.016 2.8 0.0 1.5 15 10.1 5.0 TO 6" ROOF DRAIN SYSTEM TO PERVIOUS PAVER SYSTEM D D 0.13 0.26 17 25.0 2.2 1 2.0 0.016 2.8 0.0 2.2 18 10.1 5.0 FLOWS TO JFK AND BOARDWALK - PART OF LANDINGS D3 E E 0.03 0.50 36 2.0 5.3 1 2.0 1.016 0.0 0.4 5.7 37 10.2 5.7 TO 24" ADS AREA INLET E A+E 0.12 0.74 40 3.6 2.8 48 5.0 0.016 4.5 0.2 2.9 88 10.5 5.0 TO 8" PERIMETER DRAIN B B+C 0.30 0.77 45 5.0 2.4 140 2.5 0.016 3.2 0.7 3.1 185 11.0 5.0 TO 18" PIPE AND TO POND B D+E 0.16 0.30 36 2.0 7.1 1 2.0 1.016 0.0 0.4 7.5 37 10.2 7.5 FLOWS TO JFK AND BOARDWALK - PART OF LANDINGS D3 B A+B+C+E 0.42 0.77 40 3.6 2.6 188 3.1 0.016 3.6 0.9 3.5 228 11.3 5.0 FLOWS TO STORM SYSTEM EQUATIONS: tc = ti + tt ti = [1.87 (1.1 - CCf ) L0.5 ] / S 1/3 tt = L/Vel. Velocity from Manning's Equation with R=0.1 (corresponds to Figure 3-3 of City of Fort Collins Design Manual) final tc = minimum of ti + tt and urbanized basin check min. tc = 5 min. due to limits of IDF curves Worksheet in 1326-069-00 DR.dwg Interwest Consulting Group STANDARD FORM SF-2 TIME OF CONCENTRATION - 100 YR LOCATION: Boardwalk and JFK PROJECT NO: 1326-069-00 COMPUTATIONS BY: MO DATE: 10/17/2017 100-yr storm Cf = 1.25 from Table RO-12 of City of Fort Collins Stormwater Code, Volume I SUB-BASIN INITIAL /OVERLAND TRAVEL TIME / GUTTER OR CHANNEL FLOW tc CHECK FINAL REMARKS DATA TIME (ti) (tt) (URBANIZED BASIN) tc DESIGN SUBBASIN(s) Area C C*Cf Length Slope ti Length Slope n Vel. tt tc = Total L tc=(l/180)+10 PONIT (ac) (ft) (%) (min) (ft) (%) Manning (ft/s) (min) ti + tt (ft) (min) (min) (1) (2) (3) (4) (5) (6) (7) (8) rough. (9) (10) (11) (12) (13) (14) A A 0.09 0.81 1.00 40 3.6 0.8 48 5.0 0.016 4.5 0.2 1.0 88 10.5 5.0 PERVIOUS PAVER SYSTEM B B 0.26 0.77 0.96 45 5.0 1.0 140 2.5 0.016 3.2 0.7 1.8 185 11.0 5.0 PERVIOUS PAVER SYSTEM C C 0.04 0.83 1.00 14 2.0 0.6 1 2.0 0.016 2.8 0.0 0.6 15 10.1 5.0 TO 6" ROOF DRAIN SYSTEM TO PERVIOUS PAVER SYSTEM D D 0.13 0.26 0.32 17 25.0 2.1 1 2.0 0.016 2.8 0.0 2.1 18 10.1 5.0 FLOWS TO JFK AND BOARDWALK - PART OF LANDINGS D3 E E 0.03 0.50 0.63 36 2.0 4.2 1 2.0 1.016 0.0 0.4 4.6 37 10.2 5.0 TO 24" ADS AREA INLET E A+E 0.12 0.74 0.93 40 3.6 1.3 48 5.0 0.016 4.5 0.2 1.5 88 10.5 5.0 TO 8" PERIMETER DRAIN B B+C 0.30 0.77 0.97 45 5.0 1.0 140 2.5 0.016 3.2 0.7 1.7 185 11.0 5.0 TO 18" PIPE AND TO POND B D+E 0.16 0.30 0.37 36 2.0 6.5 1 2.0 1.016 0.0 0.4 6.8 37 10.2 6.8 FLOWS TO JFK AND BOARDWALK - PART OF LANDINGS D3 B A+B+C+E 0.42 0.77 0.96 40 3.6 1.1 188 3.1 0.016 3.6 0.9 2.0 228 11.3 5.0 FLOWS TO STORM SYSTEM EQUATIONS: tc = ti + tt ti = [1.87 (1.1 - CCf ) L 0.5 ] / S 1/3 tt = L/Vel. Velocity from Manning's Equation with R=0.1 (corresponds to Figure 3-3 of City of Fort Collins Design Manual) final tc = minimum of ti + tt and urbanized basin check min. tc = 5 min. due to limits of IDF curves Worksheet in 1326-069-00 DR.dwg Interwest Consulting Group RATIONAL METHOD PEAK RUNOFF (City of Fort Collins, 2-Yr Storm) LOCATION: Boardwalk and JFK PROJECT NO: 1326-069-00 COMPUTATIONS BY: MO DATE: 10/17/2017 2 yr storm, Cf = 1.00 DIRECT RUNOFF CARRY OVER TOTAL REMARKS Design Tributary A C Cf tc i Q (2) from Q (2) Q(2)tot Sub-basin Design Point (ac) (min) (in/hr) (cfs) Point (cfs) (cfs) A A 0.09 0.81 5.0 2.85 0.2 0.2 PERVIOUS PAVER SYSTEM B B 0.26 0.77 5.0 2.85 0.6 0.6 PERVIOUS PAVER SYSTEM C C 0.04 0.83 5.0 2.85 0.1 0.1 TO 6" ROOF DRAIN SYSTEM TO PERVIOUS PAVER SYSTEM D D 0.13 0.26 5.0 2.85 0.1 0.1 FLOWS TO JFK AND BOARDWALK - PART OF LANDINGS D3 E E 0.03 0.50 5.7 2.70 0.0 0.0 TO 24" ADS AREA INLET E A+E 0.12 0.74 5.0 2.85 0.3 0.3 TO 8" PERIMETER DRAIN B B+C 0.30 0.77 5.0 2.85 0.7 0.7 TO 18" PIPE AND TO POND B D+E 0.16 0.30 7.5 2.47 0.1 0.1 FLOWS TO JFK AND BOARDWALK - PART OF LANDINGS D3 B A+B+C+E 0.42 0.77 5.0 2.85 0.9 0.9 FLOWS TO STORM SYSTEM Q = Cf C iA Q = peak discharge (cfs) C = runoff coefficient Cf = frequency adjustment factor i = rainfall intensity (in/hr) from City of Fort Collins IDF curve (4/16/99) A = drainage area (acres) i = 24.221 / (10+ tc)0.7968 Worksheet in 1326-069-00 DR.dwg Interwest Consulting Group RATIONAL METHOD PEAK RUNOFF (City of Fort Collins, 10-Yr Storm) LOCATION: Boardwalk and JFK PROJECT NO: 1326-069-00 COMPUTATIONS BY: MO DATE: 10/17/2017 10 yr storm, Cf = 1.00 DIRECT RUNOFF CARRY OVER TOTAL REMARKS Design Tributary A C Cf tc i Q (10) from Q (10) Q(10)tot Sub-basin Design Point (ac) (min) (in/hr) (cfs) Point (cfs) (cfs) A A 0.09 0.81 5.0 4.87 0.4 0.4 PERVIOUS PAVER SYSTEM B B 0.26 0.77 5.0 4.87 1.0 1.0 PERVIOUS PAVER SYSTEM C C 0.04 0.83 5.0 4.87 0.2 0.2 TO 6" ROOF DRAIN SYSTEM TO PERVIOUS PAVER SYSTEM D D 0.13 0.26 5.0 4.87 0.2 0.2 FLOWS TO JFK AND BOARDWALK - PART OF LANDINGS D3 E E 0.03 0.50 5.7 4.61 0.1 0.1 TO 24" ADS AREA INLET E A+E 0.12 0.74 5.0 4.87 0.4 0.4 TO 8" PERIMETER DRAIN B B+C 0.30 0.77 5.0 4.87 1.1 1.1 TO 18" PIPE AND TO POND B D+E 0.16 0.30 7.5 4.23 0.2 0.2 FLOWS TO JFK AND BOARDWALK - PART OF LANDINGS D3 B A+B+C+E 0.42 0.77 5.0 4.87 1.6 1.6 FLOWS TO STORM SYSTEM Q = Cf C iA Q = peak discharge (cfs) C = runoff coefficient Cf = frequency adjustment factor i = rainfall intensity (in/hr) from City of Fort Collins IDF curve (4/16/99) A = drainage area (acres) i = 41.44 / (10+ tc)0.7974 Worksheet in 1326-069-00 DR.dwg Interwest Consulting Group RATIONAL METHOD PEAK RUNOFF (City of Fort Collins, 100-Yr Storm) LOCATION: Boardwalk and JFK PROJECT NO: 1326-069-00 COMPUTATIONS BY: MO DATE: 10/17/2017 100 yr storm, Cf = 1.25 DIRECT RUNOFF CARRY OVER TOTAL REMARKS Des. Area A C Cf tc i Q (100) from Q (100) Q(100)tot Design Point Design. (ac) (min) (in/hr) (cfs) Point (cfs) (cfs) A A 0.09 1.00 5.0 9.95 0.9 0.9 PERVIOUS PAVER SYSTEM B B 0.26 0.96 5.0 9.95 2.5 2.5 PERVIOUS PAVER SYSTEM C C 0.04 1.00 5.0 9.95 0.4 0.4 TO 6" ROOF DRAIN SYSTEM TO PERVIOUS PAVER SYSTEM D D 0.13 0.32 5.0 9.95 0.4 0.4 FLOWS TO JFK AND BOARDWALK - PART OF LANDINGS D3 E E 0.03 0.63 5.0 9.95 0.2 0.2 TO 24" ADS AREA INLET E A+E 0.12 0.93 5.0 9.95 1.1 1.1 TO 8" PERIMETER DRAIN B B+C 0.30 0.97 5.0 9.95 2.9 2.9 TO 18" PIPE AND TO POND B D+E 0.16 0.37 6.8 8.91 0.5 0.5 FLOWS TO JFK AND BOARDWALK - PART OF LANDINGS D3 B A+B+C+E 0.42 0.96 5.0 9.95 4.0 4.0 FLOWS TO STORM SYSTEM Q = C iA Q = peak discharge (cfs) C = runoff coefficient i = rainfall intensity (in/hr) from City of Fort Collins IDF curve (4/16/99) A = drainage area (acres) i = 84.682 / (10+ tc) 0.7975 Worksheet in 1326-069-00 DR.dwg C APPENDIX C HYDRAULIC CALCULATIONS Purpose: This workbook can be used to size a variety of inlets based on allowable spread and depth in a street or swale. Content: The workbook consists of the following worksheets: Q-Peak Inlet Management Inlet [#] Inlet Pictures Acknowledgements: Spreadsheet Development Team: Dr. James C.Y. Guo, P.E. Professor, Department of Civil Engineering, University of Colorado at Denver Ken A. MacKenzie, P.E., Chris Carandang Urban Drainage and Flood Control District Derek N. Rapp, P.E. Peak Stormwater Engineering, LLC Comments? Direct all comments regarding this spreadsheet workbook to: UDFCD email Revisions? Check for revised versions of this or any other workbook at: Downloads The Inlet Management sheet imports information from the Q-Peak sheet and Inlet [#] sheets and can be used to connect inlets in series so that bypass flow from an upstream inlet is added to flow calculated for the next downstream inlet. This sheet can also be used to modify design information from the Q-peak sheet. Inlet [#] sheets are created each time the user exports information from the Q-Peak sheet to the Inlet Management sheet. The Inlet [#] sheets calculate allowable half-street capacity based on allowable depth and allowable spread for the minor and major storm events. This is also where the user selects an inlet type and calculates the capacity of that inlet. The Inlet Pictures sheet contains a library of photographs of the various types of inlets contained in UD-Inlet and referenced in the USDCM. Version 4.05 Released March 2017 STREET AND INLET HYDRAULICS Urban Drainage and Flood Control District Denver, Colorado The Q-Peak sheet calculates the peak discharge for the inlet tributary area based on the Rational Method for the minor and major storm events. Alternatively, the user can enter a known flow. Information from this sheet is then exported to the Inlet Management sheet. 12-12-17 UD-Inlet_v4.05.xlsm, INTRO 11/29/2017, 8:47 AM Worksheet Protected Project: Design Flow: ONLY if already determined through other methods: Minor Storm Major Storm (local peak flow for 1/2 of street OR grass-lined channel): *QKnown = 1.6 4.0 cfs * If you enter flows in Row 14, select "Street Inlet" or "Area Inlet" button and then skip the rest of this sheet and click "Add New Inlet" at bottom of sheet. Geographic Information: (Enter data in the blue cells): Subcatchment Area = Acres Percent Imperviousness = % NRCS Soil Type = A, B, C, or D Slope (ft/ft) Length (ft) Overland Flow = Gutter Flow = Rainfall Information: Intensity I (inch/hr) = C1 * P1 / ( C2 + Tc ) ^ C3 Minor Storm Major Storm Design Storm Return Period, Tr = years Return Period One-Hour Precipitation, P1 = inches C1 = C2 = C3 = User-Defined Storm Runoff Coefficient (leave this blank to accept a calculated value), C = User-Defined 5-yr. Runoff Coefficient (leave this blank to accept a calculated value), C5 = Bypass (Carry-Over) Flow from upstream Subcatchments, Qb = 0.0 0.0 cfs Total Design Peak Flow, Q = 1.6 4.0 cfs Version 4.05 Released March 2017 <--- FILL IN THIS SECTION OR… FILL IN THE SECTIONS BELOW. <--- DESIGN PEAK FLOW FOR SWALE OR ONE-HALF OF STREET BY THE RATIONAL METHOD Boardwalk Office Park Site is Urban Site is Rural Show Details Site Type: Street Inlet Area Inlet in a Swale Flows Developed For: 12-12-17 UD-Inlet_v4.05.xlsm, Q-Peak 11/29/2017, 8:47 AM Project: Inlet ID: Gutter Geometry (Enter data in the blue cells) Maximum Allowable Width for Spread Behind Curb TBACK = 3.0 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 = 0.016 Height of Curb at Gutter Flow Line HCURB = 6.00 inches Distance from Curb Face to Street Crown TCROWN = 17.0 ft Gutter Width W = 2.00 ft Street Transverse Slope SX = 0.030 ft/ft Gutter Cross Slope (typically 2 inches over 24 inches or 0.083 ft/ft) SW = 0.083 ft/ft Street Longitudinal Slope - Enter 0 for sump condition SO = 0.000 ft/ft Manning's Roughness for Street Section (typically between 0.012 and 0.020) nSTREET = 0.016 Minor Storm Major Storm Max. Allowable Spread for Minor & Major Storm TMAX = 12.0 17.0 ft Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX = 6.0 6.0 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) Boardwalk Office Park Inlet B 12-12-17 UD-Inlet_v4.05.xlsm, Inlet B 11/29/2017, 8:53 AM Design Information (Input) MINOR MAJOR Type of Inlet Type = Local Depression (additional to continuous gutter depression 'a' from above) alocal = 3.00 3.00 inches Number of Unit Inlets (Grate or Curb Opening) No = 1 1 Water Depth at Flowline (outside of local depression) Ponding Depth = 5.6 6.0 inches Grate Information MINOR MAJOR Length of a Unit Grate Lo (G) = N/A N/A feet Width of a Unit Grate Wo = N/A N/A feet Area Opening Ratio for a Grate (typical values 0.15-0.90) Aratio = N/A N/A Clogging Factor for a Single Grate (typical value 0.50 - 0.70) Cf (G) = N/A N/A Grate Weir Coefficient (typical value 2.15 - 3.60) Cw (G) = N/A N/A Grate Orifice Coefficient (typical value 0.60 - 0.80) Co (G) = N/A N/A Curb Opening Information MINOR MAJOR Length of a Unit Curb Opening Lo (C) = 5.00 5.00 feet Height of Vertical Curb Opening in Inches Hvert = 6.00 6.00 inches Height of Curb Orifice Throat in Inches Hthroat = 6.00 6.00 inches Angle of Throat (see USDCM Figure ST-5) Theta = 63.40 63.40 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) = 3.60 3.60 Curb Opening Orifice Coefficient (typical value 0.60 - 0.70) Co (C) = 0.67 0.67 Low Head Performance Reduction (Calculated) MINOR MAJOR Depth for Grate Midwidth dGrate = N/A N/A ft Depth for Curb Opening Weir Equation dCurb = 0.30 0.33 ft Combination Inlet Performance Reduction Factor for Long Inlets RFCombination = 0.72 0.77 Curb Opening Performance Reduction Factor for Long Inlets RFCurb = 1.00 1.00 Grated Inlet Performance Reduction Factor for Long Inlets RFGrate = N/A N/A MINOR MAJOR Total Inlet Interception Capacity (assumes clogged condition) Qa = 4.6 5.4 cfs Inlet Capacity IS GOOD for Minor and Major Storms(>Q PEAK) Q PEAK REQUIRED = 1.6 4.0 cfs CDOT Type R Curb Opening INLET IN A SUMP OR SAG LOCATION Version 4.05 Released March 2017 H-Vert H-Curb W Lo (C) Lo (G) Wo WP CDOT Type R Curb Ope Override 12-12-17 UD-Inlet_v4.05.xlsm, Inlet B 11/29/2017, 8:53 AM Interwest Consulting Group 1218 W. Ash, Suite C Windsor, CO 80550 Inlet Flow Calculation for Area Inlet (24" ADS Inlet) Project: Boardwalk Office Building Job Number : 1326-069-00 Calculations by : es Date : 12/12/2017 Objective: to find the number of grates required for area inlets in grassy areas Geometry at inlet : Square Feet Open (A): 1.145 sf Reduction Factor (F): 50% Grate Flow: Use the orifice equation Qi = C*A*SQRT(2*g*H) to find the ideal inlet capacity.* *See Hydraulic Design Handbook by McGraw-Hill for verificaiton of equation use and C value C = Orifice discharge coefficient= 0.67 A = Orifice area (ft2) - open area of grate g = gravitational constant = 32.2 ft/s2 H = head on grate centroid, ponding depth (feet) Then multiply by the reduction factor for the allowable capacity. QG = Qi * (1-F) DP E Q = 0.2 cfs Q100 H = 0.1 ft A= 1.15 ft2 Qi = C*A*SQRT(2*g*H) = 1.95 cfs QG = Qi * F = 0.97 cfs OK Grate Open Area and information: WSEL Page1 Scenario: 100-yr Title: Boardwalk Office Building x:\...\drainage\design\stormcad\11-28-17 storm.stm 11/29/17 09:37:14 AM Interwest Consulting Group © Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 USA +1-203-755-1666 Project Engineer: Interwest Consulting Group StormCAD v5.5 [5.5005] Page 1 of 1 P-4 P-3 P-2 P-1 12" SOLID LID-2 12" SOLID LID-1 5' TYPE R OUTLET 24" INLET Calculation Results Summary Title: Boardwalk Office Building x:\...\drainage\design\stormcad\11-28-17 storm.stm 11/29/17 09:35:05 AM Interwest Consulting Group © Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 USA +1-203-755-1666 Project Engineer: Interwest Consulting Group StormCAD v5.5 [5.5005] Page 1 of 2 ================================================================= Scenario: Base >>>> Info: Subsurface Network Rooted by: OUTLET >>>> Info: Subsurface Analysis iterations: 1 >>>> Info: Convergence was achieved. CALCULATION SUMMARY FOR SURFACE NETWORKS ____________________________________________________________________________________________________________ | Label | Inlet | Inlet | Total | Total | Capture | Gutter | Gutter | | | Type | | Intercepted | Bypassed | Efficiency | Spread | Depth | | | | | Flow | Flow | (%) | (ft) | (ft) | | | | | (cfs) | (cfs) | | | | |-----------|---------------|----------------------|-------------|----------|------------|--------|--------| | 24" INLET | Generic Inlet | Generic Default 100% | 0.00 | 0.00 | 100.0 | 0.00 | 0.00 | | 5' TYPE R | Generic Inlet | Generic Default 100% | 0.00 | 0.00 | 100.0 | 0.00 | 0.00 | ------------------------------------------------------------------------------------------------------------ CALCULATION SUMMARY FOR SUBSURFACE NETWORK WITH ROOT: OUTLET _______________________________________________________________________________________________ | Label | Number | Section | Section | Length | Total | Average | Hydraulic | Hydraulic | | | of | Size | Shape | (ft) | System | Velocity | Grade | Grade | | | Sections | | | | Flow | (ft/s) | Upstream | Downstream | | | | | | | (cfs) | | (ft) | (ft) | |-------|----------|---------|----------|--------|--------|----------|-----------|------------| | P-1 | 1 | 12 inch | Circular | 13.70 | 4.00 | 5.09 | 49.52 | 49.27 | | P-2 | 1 | 8 inch | Circular | 21.50 | 1.10 | 3.15 | 49.95 | 49.84 | | P-3 | 1 | 8 inch | Circular | 143.80 | 1.10 | 3.15 | 50.77 | 50.07 | | P-4 | 1 | 8 inch | Circular | 35.10 | 1.10 | 3.15 | 51.07 | 50.90 | ----------------------------------------------------------------------------------------------- ________________________________________________________________ | Label | Total | Ground | Hydraulic | Hydraulic | | | System | Elevation | Grade | Grade | | | Flow | (ft) | Line In | Line Out | | | (cfs) | | (ft) | (ft) | |-----------------|--------|-----------|-----------|-----------| | OUTLET | 4.00 | 51.00 | 48.42 | 48.42 | | 5' TYPE R | 4.00 | 51.82 | 49.84 | 49.52 | | 12" SOLID LID-1 | 1.10 | 52.92 | 50.07 | 49.95 | | 12" SOLID LID-2 | 1.10 | 56.13 | 50.90 | 50.77 | | 24" INLET | 1.10 | 52.50 | 51.07 | 51.07 | ---------------------------------------------------------------- ================================================================= Calculation Results Summary Title: Boardwalk Office Building x:\...\drainage\design\stormcad\11-28-17 storm.stm 11/29/17 09:35:05 AM Interwest Consulting Group © Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 USA +1-203-755-1666 Project Engineer: Interwest Consulting Group StormCAD v5.5 [5.5005] Page 2 of 2 Completed: 11/29/2017 09:34:28 AM Profile Scenario: Base Title: Boardwalk Office Building x:\...\drainage\design\stormcad\11-28-17 storm.stm 11/29/17 09:36:32 AM Interwest Consulting Group © Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 USA +1-203-755-1666 Project Engineer: Interwest Consulting Group StormCAD v5.5 [5.5005] Page 1 of 1 Elevation (ft) Station (ft) Profile: Profile - 1 Scenario: Base -3+00 -2+00 -1+00 0+00 45.00 50.00 55.00 60.00 Sump: 49.83 ft Rim: 52.50 ft Label: 24" INLET Sump: 49.66 ft Rim: 56.13 ft Label: 12" SOLID LID-2 Sump: 48.94 ft Rim: 52.92 ft Label: 12" SOLID LID-1 Sump: 48.49 ft Rim: 52.32 ft Label: 5' TYPE R Sump: 48.42 ft Rim: 51.00 ft Label: OUTLET S: 0.004843 ft/ft Size: 8 inch L: 35.10 ft Dn. Invert: 49.66 ft Up. Invert: 49.83 ft Label: P-4 S: 0.005007 ft/ft Size: 8 inch L: 143.80 ft Dn. Invert: 48.94 ft Up. Invert: 49.66 ft Label: P-3 S: 0.005581 ft/ft Size: 8 inch L: 21.50 ft Dn. Invert: 48.82 ft Up. Invert: 48.94 ft Label: P-2 S: 0.005109 ft/ft Size: 12 inch L: 13.70 ft Dn. Invert: 48.42 ft Up. Invert: 48.49 ft Label: P-1 Project Description Flow Element: Rectangular Channel Friction Method: Manning Formula Solve For: Discharge Input Data Roughness Coefficient: 0.013 Channel Slope: 0.02000 ft/ft Normal Depth: 0.50 ft Bottom Width: 1.00 ft Results Discharge: 3.21 ft³/s Flow Area: 0.50 ft² Wetted Perimeter: 2.00 ft Top Width: 1.00 ft Critical Depth: 0.68 ft Critical Slope: 0.00882 ft/ft Velocity: 6.41 ft/s Velocity Head: 0.64 ft Specific Energy: 1.14 ft Froude Number: 1.60 Flow Type: Supercritical GVF Input Data Downstream Depth: 0.00 ft Length: 0.00 ft Number Of Steps: 0 GVF Output Data Upstream Depth: 0.00 ft Profile Description: N/A Profile Headloss: 0.00 ft Downstream Velocity: 0.00 ft/s Upstream Velocity: 0.00 ft/s Normal Depth: 0.50 ft Critical Depth: 0.68 ft Channel Slope: 0.02000 ft/ft Critical Slope: 0.00882 ft/ft Worksheet for 1' SW Chase Project Description Flow Element: Rectangular Channel Friction Method: Manning Formula Solve For: Discharge Section Data Roughness Coefficient: 0.013 Channel Slope: 0.02000 ft/ft Normal Depth: 0.50 ft Bottom Width: 1.00 ft Discharge: 3.21 ft³/s Cross Section for 1' SW Chase D APPENDIX D WATER QUALITY AND LID INFORMATION Design Procedure Form: Extended Detention Basin (EDB) - Sedimentation Facility Project Name: Boardwalk Office Building Project Number: 1326-069-00 Company: INTERWEST CONSULTING GROUP Designer: ES Date: 10/17/2017 1. Basin Storage Volume A) Tributary Area's Imperviousness Ratio (i=Ia/100) Ia = 58 % i = 0.58 B) Contributing Watershed Area (Area) A = 0.55 acres C) Water Quality Capture Volume (WQCV) WQCV = 0.229636 watershed inches (WQCV = 1.0 * (0.91 * i3 - 1.19 * i2 + 0.78i) ) D) Design Volume: Vol = WQCV/12 * Area * 1.2 Vol. = 0.013 ac-ft New Impervious Area 16,449 sf Required Minimum Impervious Area to be Treated 8,225 sf Treatment #1 - Pervious Pavers (Basin A) 989 sf Treatment #1 - Impervious Area Treated (Basin A) 3,928 sf Treatment #1 - Run-on Ratio (3:1 Max) 3.0 Treatment #2 - Pervious Pavers (Basin B) 2,801 sf Treatment #2 - Impervious Area Treated (Basin B & C) 11,632 sf Treatment #2 - Run-on Ratio (3:1 Max) 3.2 Total Area Treated 15,560 sf Actual % of Impervious Area On-Site Treated by LID 95 % New Pavement Area 10,434 sf Required Minimum Area of Pervious Pavement 2,609 sf Area of Pervious Pavers Provided 3,790 sf Actual % of Pervious Pavement Provided 36 % 50% On-Site Treatment by LID Requirement LID Table 25% Porous Pavement Requirement E APPENDIX E EXCERPTS FROM REFERENCE REPORTS Page 1 of 1 https://utility.arcgisonline.com/arcgis/rest/directories/arcgisoutput/Utilities/PrintingTools_... 8/17/2017 This unofficial copy was downloaded on Jul-18-2017 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com For additional information or an official copy, please contact Engineering Office 281 North College Fort Collins, CO 80521 USA