Loading...
HomeMy WebLinkAboutARROWHEAD COTTAGES - MJA/FDP - FDP160004 - REPORTS - DRAINAGE REPORT301 N. Howes Street, Suite 100, Fort Collins, CO 80521 970.221.4158 www.northernengineering.com June 3, 2016 Wes Lamarque City of Fort Collins Stormwater Utility 700 Wood Street Fort Collins, CO 80521 RE: Drainage Addendum to the Final Drainage and Erosion Control Report for Centre Avenue Residences Mr. Lamarque: Northern Engineering is pleased to submit this Drainage Addendum for your review. This addendum serves to outline the drainage design for the Arrowhead Cottages project, and to show compliance with overall drainage concepts outlined in previous reports and studies. This addendum has been prepared in accordance with the Fort Collins Stormwater Criteria Manual (FCSCM) and serves to document the stormwater impacts associated with the proposed project. We understand that review by the City is to assure general compliance with standardized criteria. If you should have any questions as you review this addendum, please feel free to contact us. Sincerely, NORTHERN ENGINEERING SERVICES, INC. Danny Weber, PE Ryan Banning, PE Project Engineer Project Manager Arrowhead Cottages Page|2 The Arrowhead Cottages project is a Major Amendment to the Centre Avenue Residences site plan, previously submitted and approved by the City of Fort Collins. This addendum is intended to document the associated stormwater impacts of the revised site development plan on the existing and proposed storm drainage systems. The project area has been previously studied as part of the Amended Master Drainage Plan for the Centre for Advanced Technology (dated February 1987), the Final Drainage Report for the Seventh Filing of the Centre for Advanced Technology (dated August 1988), and the Final Drainage and Erosion Control Report for Centre Avenue Residences (dated October 2009). The drainage plan for this proposed project will conform to these previously approved reports. Historically, the majority of the site sheet flowed north to an existing detention pond located in the northern portion of the site. A small area of the site along Centre Avenue and Worthington Circle sheet flowed into the adjacent curb and gutter where it was routed to an existing inlet at the intersection between Centre Avenue and Worthington Circle. The proposed site will follow similar drainage patterns as historical. The majority of the site basins will be collected by existing and proposed storm sewer systems, where the flows will be routed to the existing detention facility. The basin which do not directly flow to the existing detention pond are described below: Basin OS1 is a small basin along the Worthington Circle Right-of-Way. Historically, flow from this basin sheet drained north directly to the existing detention pond. As proposed, the runoff will enter the Worthington Circle curb and gutter where it will be routed north to the existing detention pond. Runoff from this basin is considered negligible (0.19 cubic feet per second [cfs] for 100-yr event) and, therefore, the existing storm sewer system is not analyzed. This is similar to the previously approved Centre Avenue Residences development plan, labeled Basin D3 in that report. Basins OS2 and E are the southern-most basins along the Centre Avenue and Worthington Circle Right-of-Ways. Historically, flow from these basins sheet drained south or west into either Worthington Circle or Centre Avenue Right-of-Ways, where it was collected by an existing inlet on the north side of Centre Avenue. Stormwater runoff from Basin E will pass through an engineered bio-swale designed to provide water quality measures and attenuate the flows for minor events. This proposed bio-swale will treat a larger area of runoff then the previously approved rain garden. Additionally, the total off-site runoff has slightly increased during the 100-yr event from the Centre Avenue Residences developed site to the Arrowhead Cottages developed site, from 1.9 cfs to 1.94 cfs, respectively. This is assuming no attenuation caused by the proposed bio-swale. Stormwater detention is provided by an existing detention facility constructed with the Seventh Filing of the Centre for Advanced Technology and certified with the Final Drainage and Erosion Control Report for Centre Avenue Residences. The total impervious area for the previously approved Centre Avenue Residences site plan was approximately 48,787 square feet (SF). Through the use of permeable pavers located along the driveway north of building 2, the Arrowhead Cottages site plan results in a total impervious area of Arrowhead Cottages Page|3 approximately 47,916 SF. For this reason, no modifications to the existing detention pond are proposed. In conclusion, this addendum has been prepared in accordance with the Fort Collins Stormwater Criteria Manual (FCSCM) and complies with assumptions from previous drainage reports. APPENDIX A HYDROLOGIC COMPUTATIONS CHARACTER OF SURFACE: Runoff Coefficient Percentage Impervious Project: Arrowhead Cottages Streets, Parking Lots, Roofs, Alleys, and Drives: Calculations By: D. Weber Asphalt ……....……………...……….....…...……………….………………………………….0.95 . 100 Date: Concrete …….......……………….….……….………………..….………………………………… 0.95 90 Gravel ……….…………………….….…………………………..……………………………….0.50 . 40 Roofs …….…….………………..……………….…………………………………………….0.. 95 90 Concrete Pavers…………………………...………………..…………………………………………….0.40 . 22 Lawns and Landscaping Sandy Soil ……..……………..……………….…………………………………………….. 0.15 0 Clayey Soil ….….………….…….…………..………………………………………………. 0.25 0 2-year Cf = 1.00 100-year Cf = 1.25 Basin ID Basin Area (s.f.) Basin Area (ac) Area of Asphalt (ac) Area of Concrete (ac) Area of Roofs (ac) Area of Gravel (ac) Area of Concrete Pavers (ac) Area of Lawns and Landscaping (ac) 2-year Composite Runoff Coefficient 10-year Composite Runoff Coefficient 100-year Composite Runoff Coefficient Composite % Imperv. A1 1,804 0.04 0.00 0.00 0.01 0.00 0.00 0.03 0.49 0.49 0.61 30.7 A2 1,244 0.03 0.00 0.01 0.00 0.00 0.00 0.02 0.47 0.47 0.59 28.4 A3 2,034 0.05 0.00 0.02 0.01 0.00 0.00 0.01 0.78 0.78 0.97 68.1 A4 1,780 0.04 0.00 0.01 0.02 0.00 0.00 0.01 0.72 0.72 0.90 60.7 A5 2,841 0.07 0.00 0.01 0.02 0.00 0.00 0.03 0.62 0.62 0.78 47.6 Overland Flow, Time of Concentration: Project: Arrowhead Cottages Calculations By: Date: Gutter/Swale Flow, Time of Concentration: Tt = L / 60V Tc = Ti + Tt (Equation RO-2) Velocity (Gutter Flow), V = 20·S ½ Velocity (Swale Flow), V = 15·S ½ NOTE: C-value for overland flows over grassy surfaces; C = 0.25 Is Length >500' ? C*Cf (2-yr Cf=1.00) C*Cf (10-yr Cf=1.00) C*Cf (100-yr Cf=1.25) Length, L (ft) Slope, S (%) Ti 2-yr (min) Ti 10-yr (min) Ti 100-yr (min) Length, L (ft) Slope, S (%) Velocity, V (ft/s) Tt (min) Length, L (ft) Slope, S (%) Velocity, Rational Method Equation: Project: Arrowhead Cottages Calculations By: Date: From Section 3.2.1 of the CFCSDDC Rainfall Intensity: A1 A1 0.04 5.0 5.0 5.0 0.49 0.49 0.61 2.85 4.87 9.95 0.06 0.10 0.25 A2 A2 0.03 5.5 5.5 5.0 0.47 0.47 0.59 2.85 4.87 9.95 0.04 0.07 0.17 A3 A3 0.05 5.0 5.0 5.0 0.78 0.78 0.97 2.85 4.87 9.95 0.10 0.18 0.45 A4 A4 0.04 5.0 5.0 5.0 0.72 0.72 0.90 2.85 4.87 9.95 0.08 0.14 0.37 A5 A5 0.07 5.0 5.0 5.0 0.62 0.62 0.78 2.85 4.87 9.95 0.12 0.20 0.50 A6 A6 0.17 5.0 5.0 5.0 0.85 0.85 1.00 2.85 4.87 9.95 0.41 0.70 1.68 A7 A7 0.08 5.0 5.0 5.0 0.81 0.81 1.00 2.85 4.87 9.95 0.17 0.30 0.75 A8 A8 0.03 5.0 5.0 5.0 0.70 0.70 0.87 2.85 4.87 9.95 0.06 0.10 0.26 B1 B1 0.04 5.3 5.3 5.0 0.25 0.25 0.31 2.85 4.87 9.95 0.03 0.05 0.12 B2 B2 0.03 5.0 5.0 5.0 0.47 0.47 0.59 2.85 4.87 9.95 0.04 0.06 0.16 B3 B3 0.15 5.0 5.0 5.0 0.87 0.87 1.00 2.85 4.87 9.95 0.38 0.64 1.51 B4 B4 0.04 5.0 5.0 5.0 0.25 0.25 0.31 2.85 4.87 9.95 0.03 0.04 0.11 B5 B5 0.10 6.8 6.8 6.3 0.26 0.26 0.32 2.60 4.44 9.31 0.06 0.11 0.28 C C 0.08 5.0 5.0 5.0 0.84 0.84 1.00 2.85 4.87 9.95 0.20 0.34 0.84 D D 0.38 5.0 5.0 5.0 0.81 0.81 1.00 2.85 4.87 9.95 0.88 1.51 3.81 E E 0.19 5.0 5.0 5.0 0.62 0.62 0.77 2.85 4.87 9.95 0.34 0.57 1.47 F F 0.64 13.3 13.3 12.0 0.38 0.38 0.47 1.98 3.39 7.29 0.48 0.82 2.21 G G 0.19 9.5 9.5 9.3 0.25 0.25 0.31 2.30 3.93 8.03 0.11 0.19 0.49 OS1 OS1 0.03 5.0 5.0 5.0 0.44 0.44 0.55 2.85 4.87 9.95 0.04 0.07 0.19 OS2 OS2 0.11 6.6 6.6 5.8 0.35 0.35 0.44 2.60 4.44 9.63 0.10 0.17 0.47 DEVELOPED RUNOFF COMPUTATIONS C100 Design Point Flow, Q100 (cfs) Flow, Q2 (cfs) 10-yr Tc (min) 2-yr Tc (min) C2 Flow, Q10 (cfs) Intensity, i100 (in/hr) Basin(s) D. Weber June 1, 2016 Intensity, i10 (in/hr) Rainfall Intensity taken from the City of Fort Collins Storm Drainage Design Criteria (CFCSDDC), Figure 3.1 C10 Area, A (acres) Intensity, i2 APPENDIX B HYDRAULIC COMPUTATIONS APPENDIX B.1 STORM SEWERS Channel Report Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Tuesday, May 31 2016 Bio-swale Outfall Circular Diameter (ft) = 0.67 Invert Elev (ft) = 100.00 Slope (%) = 15.73 N-Value = 0.011 Calculations Compute by: Known Q Known Q (cfs) = 1.47 Highlighted Depth (ft) = 0.24 Q (cfs) = 1.470 Area (sqft) = 0.11 Velocity (ft/s) = 12.91 Wetted Perim (ft) = 0.86 Crit Depth, Yc (ft) = 0.57 Top Width (ft) = 0.64 EGL (ft) = 2.83 0 1 Elev (ft) Section 99.75 100.00 100.25 100.50 100.75 101.00 Reach (ft) APPENDIX B.2 INLETS Project: 374-018 By: D. Weber Date: 6/1/2016 Design Inlet Inlet Inlet Flow 2-Year 100-Year 2-Year 100-Year Comments Point ID Size Type Condition Flow Flow Inlet Capacity Inlet Capacity (IN) (CFS) (CFS) (CFS) (CFS) A1 EX INLET 3-1 15 Nyloplast SUMP 0.10 0.42 1.10 1.10 Recieves flow from Basin A2 A3 INLET 3-3-2 12 Nyloplast SUMP 0.10 0.45 0.54 0.54 A4 INLET 3-3-1 12 Nyloplast SUMP 0.08 0.37 0.63 0.63 A5 EX INLET 3-4 24 Nyloplast SUMP 0.12 0.50 4.30 4.30 A6 EX INLET 3-5 Single Combo SUMP 0.41 1.68 3.60 3.60 A8 INLET 3-4-1 12 Nyloplast SUMP 0.06 0.26 0.89 0.89 B1 INLET 1-1 12 Nyloplast SUMP 0.03 0.12 0.96 0.96 B2 INLET 1-2 12 Nyloplast SUMP 0.04 0.16 0.72 0.72 B3 INLET 1-3 Single Combo SUMP 0.38 1.51 3.60 3.60 B4 INLET 1-3-1 12 Nyloplast SUMP 0.03 0.11 1.18 1.18 B5 INLET 1-4 12 Nyloplast SUMP 0.06 0.28 0.94 0.94 C INLET 2-1 Single Combo SUMP 0.20 0.84 1.00 1.00 E INLET 4-1 15 Nyloplast SUMP 0.34 1.47 1.53 1.53 *EX INLET 3-2-1 (Design Point A7) was designed and installed under previous filing and flow to inlet is unchanged INLET CAPACITY SUMMARY 3130 Verona Avenue • Buford, GA 30518 (866) 888-8479 / (770) 932-2443 • Fax: (770) 932-2490 © Nyloplast Inlet Capacity Charts June 2012 0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05 1.10 Capacity (cfs) Head (ft) Nyloplast 15" Drop In Grate Inlet Capacity Chart 3130 Verona Avenue • Buford, GA 30518 (866) 888-8479 / (770) 932-2443 • Fax: (770) 932-2490 © Nyloplast Inlet Capacity Charts June 2012 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05 1.10 Capacity (cfs) Head (ft) Nyloplast 12" Drop In Grate Inlet Capacity Chart 3130 Verona Avenue • Buford, GA 30518 (866) 888-8479 / (770) 932-2443 • Fax: (770) 932-2490 © Nyloplast Inlet Capacity Charts June 2012 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05 1.10 Capacity (cfs) Head (ft) Nyloplast 12" Drop In Grate Inlet Capacity Chart 3130 Verona Avenue • Buford, GA 30518 (866) 888-8479 / (770) 932-2443 • Fax: (770) 932-2490 © Nyloplast Inlet Capacity Charts June 2012 0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05 1.10 Capacity (cfs) Head (ft) Nyloplast 24" Drop In Grate Inlet Capacity Chart Project = Inlet ID = Design Information (Input) MINOR MAJOR Type of Inlet Inlet Type = Local Depression (additional to continuous gutter depression 'a' from 'Q-Allow') alocal = 2.00 2.00 inches Number of Unit Inlets (Grate or Curb Opening) No = 1 1 Water Depth at Flowline (outside of local depression) Flow Depth = 6.0 6.0 inches Grate Information MINOR MAJOR Length of a Unit Grate Lo (G) = 3.00 3.00 feet Width of a Unit Grate Wo = 1.73 1.73 feet Area Opening Ratio for a Grate (typical values 0.15-0.90) Aratio = 0.43 0.43 Clogging Factor for a Single Grate (typical value 0.50 - 0.70) Cf (G) = 0.50 0.50 Grate Weir Coefficient (typical value 2.15 - 3.60) Cw (G) = 3.30 3.30 Grate Orifice Coefficient (typical value 0.60 - 0.80) Co (G) = 0.60 0.60 Curb Opening Information MINOR MAJOR Length of a Unit Curb Opening Lo (C) = 3.00 3.00 feet Height of Vertical Curb Opening in Inches Hvert = 6.50 6.50 inches Height of Curb Orifice Throat in Inches Hthroat = 5.25 5.25 inches Angle of Throat (see USDCM Figure ST-5) Theta = 0.00 0.00 degrees Side Width for Depression Pan (typically the gutter width of 2 feet) Wp = 2.00 2.00 feet Clogging Factor for a Single Curb Opening (typical value 0.10) Cf (C) = 0.10 0.10 Curb Opening Weir Coefficient (typical value 2.3-3.6) Cw (C) = 3.70 3.70 Curb Opening Orifice Coefficient (typical value 0.60 - 0.70) Co (C) = 0.66 0.66 MINOR MAJOR Total Inlet Interception Capacity (assumes clogged condition) Q a = 3.6 3.6 cfs Inlet Capacity IS GOOD for Minor and Major Storms (>Q PEAK) Q PEAK REQUIRED = 0.4 1.7 cfs INLET IN A SUMP OR SAG LOCATION Arrowhead Cottages EX INLET 3-5 (Design Point A6) CDOT/Denver 13 Combination H-Vert H-Curb W Lo (C) Lo (G) Wo WP EX INLET 3-5 (Design Point A6).xlsm, Inlet In Sump 5/31/2016, 8:31 AM 3130 Verona Avenue • Buford, GA 30518 (866) 888-8479 / (770) 932-2443 • Fax: (770) 932-2490 © Nyloplast Inlet Capacity Charts June 2012 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05 1.10 Capacity (cfs) Head (ft) Nyloplast 12" Drop In Grate Inlet Capacity Chart 3130 Verona Avenue • Buford, GA 30518 (866) 888-8479 / (770) 932-2443 • Fax: (770) 932-2490 © Nyloplast Inlet Capacity Charts June 2012 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05 1.10 Capacity (cfs) Head (ft) Nyloplast 12" Drop In Grate Inlet Capacity Chart 3130 Verona Avenue • Buford, GA 30518 (866) 888-8479 / (770) 932-2443 • Fax: (770) 932-2490 © Nyloplast Inlet Capacity Charts June 2012 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05 1.10 Capacity (cfs) Head (ft) Nyloplast 12" Drop In Grate Inlet Capacity Chart Project = Inlet ID = Design Information (Input) MINOR MAJOR Type of Inlet Inlet Type = Local Depression (additional to continuous gutter depression 'a' from 'Q-Allow') alocal = 2.00 2.00 inches Number of Unit Inlets (Grate or Curb Opening) No = 1 1 Water Depth at Flowline (outside of local depression) Flow Depth = 6.0 6.0 inches Grate Information MINOR MAJOR Length of a Unit Grate Lo (G) = 3.00 3.00 feet Width of a Unit Grate Wo = 1.73 1.73 feet Area Opening Ratio for a Grate (typical values 0.15-0.90) Aratio = 0.43 0.43 Clogging Factor for a Single Grate (typical value 0.50 - 0.70) Cf (G) = 0.50 0.50 Grate Weir Coefficient (typical value 2.15 - 3.60) Cw (G) = 3.30 3.30 Grate Orifice Coefficient (typical value 0.60 - 0.80) Co (G) = 0.60 0.60 Curb Opening Information MINOR MAJOR Length of a Unit Curb Opening Lo (C) = 3.00 3.00 feet Height of Vertical Curb Opening in Inches Hvert = 6.50 6.50 inches Height of Curb Orifice Throat in Inches Hthroat = 5.25 5.25 inches Angle of Throat (see USDCM Figure ST-5) Theta = 0.00 0.00 degrees Side Width for Depression Pan (typically the gutter width of 2 feet) Wp = 2.00 2.00 feet Clogging Factor for a Single Curb Opening (typical value 0.10) Cf (C) = 0.10 0.10 Curb Opening Weir Coefficient (typical value 2.3-3.6) Cw (C) = 3.70 3.70 Curb Opening Orifice Coefficient (typical value 0.60 - 0.70) Co (C) = 0.66 0.66 MINOR MAJOR Total Inlet Interception Capacity (assumes clogged condition) Q a = 3.6 3.6 cfs Inlet Capacity IS GOOD for Minor and Major Storms (>Q PEAK) Q PEAK REQUIRED = 0.4 1.5 cfs INLET IN A SUMP OR SAG LOCATION Arrowhead Cottages INLET 1-3 (Design Point B3) CDOT/Denver 13 Combination H-Vert H-Curb W Lo (C) Lo (G) Wo WP INLET 1-3 (Design Point B3).xlsm, Inlet In Sump 5/31/2016, 8:33 AM 3130 Verona Avenue • Buford, GA 30518 (866) 888-8479 / (770) 932-2443 • Fax: (770) 932-2490 © Nyloplast Inlet Capacity Charts June 2012 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05 1.10 Capacity (cfs) Head (ft) Nyloplast 12" Drop In Grate Inlet Capacity Chart 3130 Verona Avenue • Buford, GA 30518 (866) 888-8479 / (770) 932-2443 • Fax: (770) 932-2490 © Nyloplast Inlet Capacity Charts June 2012 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05 1.10 Capacity (cfs) Head (ft) Nyloplast 12" Drop In Grate Inlet Capacity Chart Project = Inlet ID = Design Information (Input) MINOR MAJOR Type of Inlet Inlet Type = Local Depression (additional to continuous gutter depression 'a' from 'Q-Allow') alocal = 2.00 2.00 inches Number of Unit Inlets (Grate or Curb Opening) No = 1 1 Water Depth at Flowline (outside of local depression) Flow Depth = 3.8 3.8 inches Grate Information MINOR MAJOR Length of a Unit Grate Lo (G) = 3.00 3.00 feet Width of a Unit Grate Wo = 1.73 1.73 feet Area Opening Ratio for a Grate (typical values 0.15-0.90) Aratio = 0.43 0.43 Clogging Factor for a Single Grate (typical value 0.50 - 0.70) Cf (G) = 0.50 0.50 Grate Weir Coefficient (typical value 2.15 - 3.60) Cw (G) = 3.30 3.30 Grate Orifice Coefficient (typical value 0.60 - 0.80) Co (G) = 0.60 0.60 Curb Opening Information MINOR MAJOR Length of a Unit Curb Opening Lo (C) = 3.00 3.00 feet Height of Vertical Curb Opening in Inches Hvert = 6.50 6.50 inches Height of Curb Orifice Throat in Inches Hthroat = 5.25 5.25 inches Angle of Throat (see USDCM Figure ST-5) Theta = 0.00 0.00 degrees Side Width for Depression Pan (typically the gutter width of 2 feet) Wp = 2.00 2.00 feet Clogging Factor for a Single Curb Opening (typical value 0.10) Cf (C) = 0.10 0.10 Curb Opening Weir Coefficient (typical value 2.3-3.6) Cw (C) = 3.70 3.70 Curb Opening Orifice Coefficient (typical value 0.60 - 0.70) Co (C) = 0.66 0.66 MINOR MAJOR Total Inlet Interception Capacity (assumes clogged condition) Q a = 1.0 1.0 cfs Inlet Capacity IS GOOD for Minor and Major Storms (>Q PEAK) Q PEAK REQUIRED = 0.2 0.8 cfs INLET IN A SUMP OR SAG LOCATION Arrowhead Cottages INLET 2-1 (Design Point C) CDOT/Denver 13 Combination H-Vert H-Curb W Lo (C) Lo (G) Wo WP INLET 2-1 (Design Point C).xlsm, Inlet In Sump 5/31/2016, 8:34 AM 3130 Verona Avenue • Buford, GA 30518 (866) 888-8479 / (770) 932-2443 • Fax: (770) 932-2490 © Nyloplast Inlet Capacity Charts June 2012 0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05 1.10 Capacity (cfs) Head (ft) Nyloplast 15" Drop In Grate Inlet Capacity Chart APPENDIX B.3 SWALES AND WEIRS Channel Report Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Tuesday, May 31 2016 2' Sidewalk Chase (Design Point A2) Rectangular Bottom Width (ft) = 2.00 Total Depth (ft) = 0.39 Invert Elev (ft) = 100.00 Slope (%) = 2.00 N-Value = 0.013 Calculations Compute by: Known Q Known Q (cfs) = 0.17 Highlighted Depth (ft) = 0.05 Q (cfs) = 0.170 Area (sqft) = 0.10 Velocity (ft/s) = 1.70 Wetted Perim (ft) = 2.10 Crit Depth, Yc (ft) = 0.07 Top Width (ft) = 2.00 EGL (ft) = 0.09 0 .5 1 1.5 2 2.5 3 Elev (ft) Depth (ft) Section 99.75 -0.25 100.00 0.00 100.25 0.25 100.50 0.50 100.75 0.75 101.00 1.00 Reach (ft) Channel Report Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Tuesday, May 31 2016 2' Sidewalk Chase (Design Point D) Rectangular Bottom Width (ft) = 2.00 Total Depth (ft) = 0.39 Invert Elev (ft) = 100.00 Slope (%) = 2.00 N-Value = 0.013 Calculations Compute by: Known Q Known Q (cfs) = 3.81 Highlighted Depth (ft) = 0.31 Q (cfs) = 3.810 Area (sqft) = 0.62 Velocity (ft/s) = 6.15 Wetted Perim (ft) = 2.62 Crit Depth, Yc (ft) = 0.39 Top Width (ft) = 2.00 EGL (ft) = 0.90 0 .5 1 1.5 2 2.5 3 Elev (ft) Depth (ft) Section 99.75 -0.25 100.00 0.00 100.25 0.25 100.50 0.50 100.75 0.75 101.00 1.00 Reach (ft) APPENDIX C LOW IMPACT DEVELOPMENT Sheet 1 of 2 Designer: Company: Date: Project: Location: 1. Basin Storage Volume A) Effective Imperviousness of Tributary Area, Ia Ia = 100.0 % (100% if all paved and roofed areas upstream of rain garden) B) Tributary Area's Imperviousness Ratio (i = Ia/100) i = 1.000 C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.40 watershed inches (WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i) D) Contributing Watershed Area (including rain garden area) Area = 3,259 sq ft E) Water Quality Capture Volume (WQCV) Design Volume VWQCV = 109 cu ft Vol = (WQCV / 12) * Area F) For Watersheds Outside of the Denver Region, Depth of d6 = in Average Runoff Producing Storm G) For Watersheds Outside of the Denver Region, VWQCV OTHER = cu ft Water Quality Capture Volume (WQCV) Design Volume H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER = cu ft (Only if a different WQCV Design Volume is desired) 2. Basin Geometry A) WQCV Depth (12-inch maximum) DWQCV = 9 in B) Rain Garden Side Slopes (Z = 4 min., horiz. dist per unit vertical) Z = 4.00 ft / ft (Use "0" if rain garden has vertical walls) C) Mimimum Flat Surface Area AMin = 65 sq ft D) Actual Flat Surface Area AActual = 71 sq ft E) Area at Design Depth (Top Surface Area) ATop = 289 sq ft F) Rain Garden Total Volume VT= 135 cu ft (VT= ((ATop + AActual) / 2) * Depth) 3. Growing Media 4. Underdrain System A) Are underdrains provided? B) Underdrain system orifice diameter for 12 hour drain time i) Distance From Lowest Elevation of the Storage y = 1.0 ft Volume to the Center of the Orifice ii) Volume to Drain in 12 Hours Vol12 = 109 cu ft iii) Orifice Diameter, 3/8" Minimum DO = 2/7 in LESS THAN MINIMUM. USE DIAMETER OF 3/8" Design Procedure Form: Rain Garden (RG) D. Weber Northern Engineering June 3, 2016 Arrowhead Cottages North Choose One Choose One 18" Rain Garden Growing Media Other (Explain): YES NO 374-018_RainGarden.xlsm, RG 5/31/2016, 2:51 PM APPENDIX D EROSION CONTROL REPORT Arrowhead Cottages EROSION CONTROL REPORT A comprehensive Erosion and Sediment Control Plan (along with associated details) is in included with the final construction drawings. It should be noted, however, that any such Erosion and Sediment Control Plan serves only as a general guide to the Contractor. Staging and/or phasing of the BMPs depicted, and additional or different BMPs from those included may be necessary during construction, or as required by the authorities having jurisdiction. It shall be the responsibility of the Contractor to ensure erosion control measures are properly maintained and followed. The Erosion and Sediment Control Plan is intended to be a living document, constantly adapting to site conditions and needs. The Contractor shall update the location of BMPs as they are installed, removed or modified in conjunction with construction activities. It is imperative to appropriately reflect the current site conditions at all times. The Erosion and Sediment Control Plan shall address both temporary measures to be implemented during construction, as well as permanent erosion control protection. Best Management Practices from the Volume 3, Chapter 7 – Construction BMPs will be utilized. Measures may include, but are not limited to, silt fencing and/or wattles along the disturbed perimeter, gutter protection in the adjacent roadways and inlet protection at existing and proposed storm inlets. Vehicle tracking control pads, spill containment and clean-up procedures, designated concrete washout areas, dumpsters, and job site restrooms shall also be provided by the Contractor. To ensure stormwater quality is achieved long after the construction of the project, one permanent Stormwater Quality BMP is included within the design. Located at the northern portion of the project site, an Extended Detention Basin (EDB) is being proposed. This measure will treat all of the runoff draining through the property prior to reaching the historic outfall. The Final Public Improvement Construction Plan contains a full-size Erosion Control Plan as well as a separate sheet dedicated to Erosion Control Details. In addition to this report and the referenced plan sheets, the Contractor shall be aware of, and adhere to, the applicable requirements outlined in any existing Development Agreement(s) of record, as well as the Development Agreement, to be recorded prior to issuance of the Development Construction Permit. Also, the Site Contractor for this project may be required to secure a Stormwater Construction General Permit from the Colorado Department of Public Health and Environment (CDPHE), Water Quality Control Division – Stormwater Program, before commencing any earth disturbing activities. Prior to securing said permit, the Site Contractor shall develop a comprehensive StormWater Management Plan (SWMP) pursuant to CDPHE requirements and guidelines. The SWMP will further describe and document the ongoing activities, inspections, and maintenance of construction BMPs. MAP POCKET DR1 – OVERALL DRAINAGE EXHIBIT ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST H Y D ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST C ONTROL IRR CONTROL IRR ST F E S ST ST ST ST ST ST ST D D D D D D UD UD UD UD UD UD UD UD CENTRE AVENUE WORTHINGTON CIRCLE EXISTING STUCCO BUILDING FFE=~5048.1 NEW MERCER DITCH BLDG 2 BLDG 1 GARAGE EXISTING APARTMENT BUILDING FFE=~5049.0 A1 A1 A2 A3 A4 A5 A8 A6 A7 A2 A3 A4 A5 A8 A6 A7 B1 B1 B2 B2 B3 B4 B4 B5 B5 C C D D F F G G E E OS1 OS1 OS2 OS2 B3 Sheet Of 16 Sheets ARROWHEAD COTTAGES These drawings are instruments of service provided by Northern Engineering Services, Inc. and are not to be used for any type of construction unless signed and sealed by a Professional Engineer in the employ of Northern Engineering Services, Inc. NOT FOR CONSTRUCTION REVIEW SET 200 South College Avenue, Suite 010 Fort Collins, Colorado 80524 ENGINEER ING N O R T H E RN PHONE: 970.221.4158 FAX: 970.221.4159 www.northernengineering.com DR1 DRAINAGE PLAN CALL UTILITY NOTIFICATION CENTER OF COLORADO Know what's below. Call before you dig. R City Engineer Date Date Date Date Date Stormwater Utility Parks & Recreation Traffic Engineer Date Water & Wastewater Utility City of Fort Collins, Colorado UTILITY PLAN APPROVAL Environmental Planner NORTH ( IN FEET ) 1 inch = ft. 30 0 30 Feet 30 60 90 LEGEND: PROPOSED CONTOUR PROPOSED STORM SEWER PROPOSED SWALE EXISTING CONTOUR PROPOSED CURB & GUTTER PROPERTY BOUNDARY PROPOSED INLET A DESIGN POINT FLOW ARROW DRAINAGE BASIN LABEL BASIN DESIGNATION BASIN AREA (AC) DRAINAGE BASIN BOUNDARY PROPOSED SWALE SECTION 1 1 B2 1.45 ac RUNOFF SUMMARY TABLE DESIGN POINT BASIN ID TOTAL AREA (acres) C2 C10 C100 2-yr Tc (min) 10-yr Tc (min) 100-yr Tc (min) Q2 (cfs) Q10 (cfs) Q100 (cfs) A1 A1 0.04 0.49 0.49 0.61 5.0 5.0 5.0 0.06 0.10 0.25 A2 A2 0.03 0.47 0.47 0.59 5.5 5.5 5.0 0.04 0.07 0.17 A3 A3 0.05 0.78 0.78 0.97 5.0 5.0 5.0 0.10 0.18 0.45 A4 A4 0.04 0.72 0.72 0.90 5.0 5.0 5.0 0.08 0.14 0.37 A5 A5 0.07 0.62 0.62 0.78 5.0 5.0 5.0 0.12 0.20 0.50 A6 A6 0.17 0.85 0.85 1.00 5.0 5.0 5.0 0.41 0.70 1.68 A7 A7 0.08 0.81 0.81 1.00 5.0 5.0 5.0 0.17 0.30 0.75 A8 A8 0.03 0.70 0.70 0.87 5.0 5.0 5.0 0.06 0.10 0.26 B1 B1 0.04 0.25 0.25 0.31 5.3 5.3 5.0 0.03 0.05 0.12 B2 B2 0.03 0.47 0.47 0.59 5.0 5.0 5.0 0.04 0.06 0.16 B3 B3 0.15 0.87 0.87 1.00 5.0 5.0 5.0 0.38 0.64 1.51 B4 B4 0.04 0.25 0.25 0.31 5.0 5.0 5.0 0.03 0.04 0.11 B5 B5 0.10 0.26 0.26 0.32 6.8 6.8 6.3 0.06 0.11 0.28 C C 0.08 0.84 0.84 1.00 5.0 5.0 5.0 0.20 0.34 0.84 D D 0.38 0.81 0.81 1.00 5.0 5.0 5.0 0.88 1.51 3.81 E E 0.19 0.62 0.62 0.77 5.0 5.0 5.0 0.34 0.57 1.47 F F 0.64 0.38 0.38 0.47 13.3 13.3 12.0 0.48 0.82 2.21 G G 0.19 0.25 0.25 0.31 9.5 9.5 9.3 0.11 0.19 0.49 OS1 OS1 0.03 0.44 0.44 0.55 5.0 5.0 5.0 0.04 0.07 0.19 OS2 OS2 0.11 0.35 0.35 0.44 6.6 6.6 5.8 0.10 0.17 0.47 (in/hr) 100-yr Tc (min) Q = C f ( C )( i )( A ) D:\Projects\374-018\Drainage\Hydrology\374-018_Rational.xlsx\Direct-Runoff V (ft/s) Tt (min) 2-yr Tc (min) 10-yr Tc (min) 100-yr Tc (min) A1 A1 No 0.49 0.49 0.61 27 25.0 2.0 2.0 1.6 0 0.0 0.00 N/A 42 3.2 2.68 0.3 5.0 5.0 5.0 A2 A2 No 0.47 0.47 0.59 34 2.2 5.3 5.3 4.3 0 0.0 0.00 N/A 22 1.5 1.84 0.2 5.5 5.5 5.0 A3 A3 No 0.78 0.78 0.97 34 33.3 1.1 1.1 0.4 0 0.0 0.00 N/A 10 5.0 3.35 0.0 5.0 5.0 5.0 A4 A4 No 0.72 0.72 0.90 49 5.3 2.8 2.8 1.5 0 0.0 0.00 N/A 0 0.0 0.00 N/A 5.0 5.0 5.0 A5 A5 No 0.62 0.62 0.78 44 7.0 3.1 3.1 2.1 0 0.0 0.00 N/A 0 0.0 0.00 N/A 5.0 5.0 5.0 A6 A6 No 0.85 0.85 1.00 48 2.3 2.4 2.4 1.0 76 0.6 1.55 0.8 0 0.0 0.00 N/A 5.0 5.0 5.0 A7 A7 No 0.81 0.81 1.00 32 33.3 1.0 1.0 0.3 0 0.0 0.00 N/A 22 2.6 2.42 0.2 5.0 5.0 5.0 A8 A8 No 0.70 0.70 0.87 48 2.3 3.9 3.9 2.2 76 0.6 1.55 0.8 0 0.0 0.00 N/A 5.0 5.0 5.0 B1 B1 No 0.25 0.25 0.31 35 5.6 5.3 5.3 4.9 0 0.0 0.00 N/A 0 0.0 0.00 N/A 5.3 5.3 5.0 B2 B2 No 0.47 0.47 0.59 29 6.0 3.5 3.5 2.8 0 0.0 0.00 N/A 0 0.0 0.00 N/A 5.0 5.0 5.0 B3 B3 No 0.87 0.87 1.00 26 2.0 1.7 1.7 0.8 99 0.5 1.41 1.2 0 0.0 0.00 N/A 5.0 5.0 5.0 B4 B4 No 0.25 0.25 0.31 5 5.0 2.1 2.1 1.9 0 0.0 0.00 N/A 32 5.0 3.35 0.2 5.0 5.0 5.0 B5 B5 No 0.26 0.26 0.32 48 4.7 6.5 6.5 6.0 0 0.0 0.00 N/A 28 1.5 1.84 0.3 6.8 6.8 6.3 C C No 0.84 0.84 1.00 26 2.0 2.0 2.0 0.8 58 0.5 1.41 0.7 0 0.0 0.00 N/A 5.0 5.0 5.0 D D No 0.81 0.81 1.00 25 2.0 2.2 2.2 0.7 179 1.1 2.10 1.4 0 0.0 0.00 N/A 5.0 5.0 5.0 E E No 0.62 0.62 0.77 26 33.3 1.4 1.4 1.0 0 0.0 0.00 N/A 106 1.0 1.50 1.2 5.0 5.0 5.0 F F No 0.38 0.38 0.47 95 2.0 10.5 10.5 9.1 244 0.5 1.41 2.9 0 0.0 0.00 N/A 13.3 13.3 12.0 G G No 0.25 0.25 0.31 17 20.0 2.4 2.4 2.2 0 0.0 0.00 N/A 285 0.2 0.67 7.1 9.5 9.5 9.3 OS1 OS1 No 0.44 0.44 0.55 10 2.0 3.1 3.1 2.6 0 0.0 0.00 N/A 0 0.0 0.00 N/A 5.0 5.0 5.0 OS2 OS2 No 0.35 0.35 0.44 35 2.0 6.6 6.6 5.8 0 0.0 0.00 N/A 0 0.0 0.00 N/A 6.6 6.6 5.8 DEVELOPED TIME OF CONCENTRATION COMPUTATIONS Gutter Flow Swale Flow Design Point Basin Overland Flow D. Weber June 1, 2016 Time of Concentration (Equation RO-4) ( ) 3 1 1 . 87 1 . 1 * S C Cf L Ti − = D:\Projects\374-018\Drainage\Hydrology\374-018_Rational.xlsx\Tc-2-yr_&_100-yr A6 7,364 0.17 0.00 0.15 0.00 0.00 0.00 0.02 0.85 0.85 1.00 77.5 A7 3,293 0.08 0.00 0.01 0.05 0.00 0.00 0.02 0.81 0.81 1.00 71.4 A8 1,323 0.03 0.00 0.00 0.02 0.00 0.00 0.01 0.70 0.70 0.87 57.6 B1 1,623 0.04 0.00 0.00 0.00 0.00 0.00 0.04 0.25 0.25 0.31 0.0 B2 1,163 0.03 0.00 0.01 0.00 0.00 0.00 0.02 0.47 0.47 0.59 28.7 B3 6,615 0.15 0.00 0.09 0.04 0.00 0.02 0.00 0.87 0.87 1.00 80.0 B4 1,546 0.04 0.00 0.00 0.00 0.00 0.00 0.04 0.25 0.25 0.31 0.0 B5 4,157 0.10 0.00 0.00 0.00 0.00 0.00 0.09 0.26 0.26 0.32 0.7 C 3,666 0.08 0.00 0.02 0.05 0.00 0.02 0.00 0.84 0.84 1.00 76.1 D 16,696 0.38 0.00 0.18 0.12 0.00 0.00 0.08 0.81 0.81 1.00 71.8 E 8,350 0.19 0.00 0.01 0.09 0.00 0.00 0.09 0.62 0.62 0.77 47.0 F 27,979 0.64 0.00 0.02 0.10 0.00 0.00 0.53 0.38 0.38 0.47 16.4 G 8,448 0.19 0.00 0.00 0.00 0.00 0.00 0.19 0.25 0.25 0.31 0.0 OS1 1,510 0.03 0.00 0.01 0.00 0.00 0.00 0.03 0.44 0.44 0.55 24.4 OS2 4,913 0.11 0.00 0.02 0.00 0.00 0.00 0.10 0.35 0.35 0.44 12.6 TOTAL 108,349 2.49 0.00 0.56 0.54 0.00 0.04 1.35 0.56 0.56 0.70 40.1 DEVELOPED COMPOSITE % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS Runoff Coefficients are taken from the City of Fort Collins Storm Drainage Design Criteria and Construction Standards, Table 3-3. % Impervious taken from UDFCD USDCM, Volume I. 10-year Cf = 1.00 June 1, 2016 D:\Projects\374-018\Drainage\Hydrology\374-018_Rational.xlsx\C-Values