Loading...
HomeMy WebLinkAboutSW PROSPECT AND I 25 ROADWAY PROJECT - RP180001 - SUBMITTAL DOCUMENTS - ROUND 3 - DRAINAGE RELATED DOCUMENTJanuary 30, 2019 DRAINAGE LETTER SW Prospect & I-25 Fort Collins, Colorado Prepared for: Colorado State University Research Foundation (CSURF) Michael “Bo” Brown P.O. Box 483 Fort Collins, Colorado 80522 Prepared by: 301 North Mason Street, Suite 100 Fort Collins, Colorado 80524 Phone: 970.221.4158 www.northernengineering.com Project Number: 232-043 Drainage Letter – SW Prospect & I-25 Date: January 30, 2019 Project: SW Prospect & I-25 Project No. 232-043 Public Improvement Construction Plans (PICP) Fort Collins, Colorado Attn: City of Fort Collins Stormwater Utility 700 Wood Street Fort Collins, Colorado 80521 To whom it may concern: This letter serves to address the stormwater impacts of the proposed project known as “SW Prospect & I-25”. The site is located in northeast Fort Collins and is bounded to the north by East Prospect Road, to the east by the existing Interstate 25 access ramp and frontage road, to the south by a gravel road and to the west by Boxelder Creek (Figure 1). The proposed development consists of the removal of a portion of the existing Interstate 25 Frontage Road, and the construction of a new asphalt Frontage Road with a revised alignment. This project will also involve the construction of two culverts under the new road that will be utilized with the future site development. This letter shows that the proposed construction of the new road will reduce the imperviousness of the site and that the swales and culverts proposed with this project will convey existing stormwater runoff. This letter is documents that the proposed culverts and swales are sized to provide conveyance for the future development on the north side of the proposed roadway. Site Imperviousness Construction of the new Interstate 25 Frontage Road will begin with the removal of the existing road. Approximately 2,750 liner feet of 30-foot wide asphalt road will be removed accounting for 82,441 square feet. The new road will then be constructed along an updated alignment, consisting of approximately 2,295 linear feet of 28-foot wide asphalt pavement. The new roadway will have a total impervious area of 66,053 square feet -- a reduction in impervious area of 16,388 square feet. The resulting reduction in impervious area negates the need for stormwater quantity detention for the roadway project. Please see the Impervious exhibit provided in the attachments for additional information. Drainage Patterns With the construction of the new Frontage Road, existing drainage patterns will be maintained, generally traveling from northeast to southwest. The north side of the road will provide a drainage swale to channel sheet flow from the north side of the existing site to one of two culverts. These culverts are sized for the future development and are intended to remain in place and become part of a larger storm drain system when build out on the north side of the Frontage Road occurs. An assumed imperviousness of 90% was used to calculate the future flows to these culverts. The culverts will be sufficient in conveying the minor events (2-yr and 10-yr), as well as the major events (100-yr). Stormwater will then travel through swales to the existing pond, maintaining existing drainage patterns. In the interim condition, the culverts are sufficient to convey the major events (100-yr). Culvert 1 will be replacing an existing culvert and provide drainage for a small area. Please see calculations in the attachments. Page | 3 FIGURE 1 Vicinity Map Water Quality/LID Conformance Although stormwater quantity detention is not required, stormwater quality will still need to be addressed. Since the project area will remain largely undeveloped, the project will utilize the long, flat swales to provide water quality for the project. areas adjacent to the roadway project will be required to provide their own water quality and Low-Impact Development (LID) facilities at the time of development. I-25 E. Prospect Rd. Frontage Rd. Page | 4 Floodplains The FEMA designated Boxelder Creek Flood Zone exists to the west of the project site, as shown in Figure 2, below. The proposed project will not involve the placement of any offsite project improvements within the Boxelder Creek Flood Zone. FIGURE 2 City Floodplain Map (Floodplain shown is a FEMA-Designated Flood Zone) Page | 5 Conclusions The proposed grading concept closely matches the original drainage patterns and decreases overall site imperviousness, proving additional detention unnecessary. The drainage system is sized to convey both existing stormwater runoff and to be utilized in the storm drain system when ultimate build-out occurs. Therefore, it is my professional opinion that SW Prospect & I-25 satisfies all applicable stormwater criteria and will effectively limit potential damage associated with its stormwater runoff. Please do not hesitate to contact me if you have questions or require additional information. Sincerely, Benjamin Ruch, P.E. Project Engineer ATTACHMENT 1 HYDROLOGIC CALCULATIONS / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / V AULT ELEC / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / CHARACTER OF SURFACE: Runoff Coefficient Percentage Impervious Project: CSURF- I25/Prospect Road Streets, Parking Lots, Roofs, Alleys, and Drives: Calculations By: B. Ruch Asphalt ……....……………...……….....…...……………….………………………………….0.95 . 100% Date: Concrete …….......……………….….……….………………..….………………………………… 0.95 90% Gravel ……….…………………….….…………………………..……………………………….0.50 . 40% Roofs …….…….………………..……………….…………………………………………….0.95 . 90% Pavers…………………………...………………..…………………………………………….0.40 . 40% 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 (ac) Area of Asphalt (ac) Area of Concrete (ac) Area of Roofs (ac) Area of Gravel (ac) Area of 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. A 19.74 0.48 0.00 0.00 0.00 0.00 19.27 0.27 0.27 0.33 2% B 19.37 0.52 0.00 0.00 0.00 0.00 18.85 0.27 0.27 0.34 3% Total Onsite 39.11 1.00 0.00 0.00 0.00 0.00 38.12 0.90 0.90 1.00 3% INTERIM 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 January 30, 2019 Overland Flow, Time of Concentration: Project: CSURF- I25/Prospect Road 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: CSURF- I25/Prospect Road Calculations By: Date: From Section 3.2.1 of the CFCSDDC Rainfall Intensity: Design Point Basin(s) Area, A (acres) 2-yr Tc (min) 10-yr Tc (min) 100-yr Tc (min) C2 C10 C100 Intensity, i2 (in/hr) Intensity, i10 (in/hr) Intensity, i100 (in/hr) Flow, Q2 (cfs) Flow, Q10 (cfs) Flow, Q100 (cfs) Flow, WQ (cfs) A A 19.74 116 116 108 0.27 0.27 0.33 0.51 0.88 1.97 2.7 4.6 13.0 1.34 B B 19.37 71 71 66 0.27 0.27 0.34 0.72 1.24 2.71 3.8 6.4 17.6 1.88 INTERIM RUNOFF COMPUTATIONS B. Ruch January 30, 2019 Rainfall Intensity taken from the City of Fort Collins Storm Drainage Design Criteria (CFCSDDC), Figure 3.1 Q = C f ( C )( i )( A ) Basin ID Basin Area (s.f.) Basin Area (ac) Composite % Imperv. Flow, WQ (cfs) Flow, Q2 (cfs) Flow, Q100 (cfs) A 860051 19.74 2% 1.34 2.68 12.98 B 843750 19.37 3% 1.88 3.76 17.62 Interim Rational Summary CHARACTER OF SURFACE: Runoff Coefficient Percentage Impervious Project: CSURF- I25/Prospect Road Streets, Parking Lots, Roofs, Alleys, and Drives: Calculations By: B. Ruch Asphalt ……....……………...……….....…...……………….………………………………….0.95 . 100% Date: Concrete …….......……………….….……….………………..….………………………………… 0.95 90% Gravel ……….…………………….….…………………………..……………………………….0.50 . 40% Roofs …….…….………………..……………….…………………………………………….0.95 . 90% Pavers…………………………...………………..…………………………………………….0.40 . 40% 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 (ac) Area of Asphalt (ac) Area of Concrete (ac) Area of Roofs (ac) Area of Gravel (ac) Area of 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. A 14.39 0.00 0.00 0.00 0.00 0.00 0.00 0.90 0.90 1.00 90% B 22.57 0.00 0.00 0.00 0.00 0.00 0.00 0.90 0.90 1.00 90% Total Onsite 36.96 0.00 0.00 0.00 0.00 0.00 0.00 0.90 0.90 1.00 90% FUTURE 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 January 30, 2019 Overland Flow, Time of Concentration: Project: CSURF- I25/Prospect Road 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: CSURF- I25/Prospect Road Calculations By: Date: From Section 3.2.1 of the CFCSDDC Rainfall Intensity: Design Point Basin(s) Area, A (acres) 2-yr Tc (min) 10-yr Tc (min) 100-yr Tc (min) C2 C10 C100 Intensity, i2 (in/hr) Intensity, i10 (in/hr) Intensity, i100 (in/hr) Flow, Q2 (cfs) Flow, Q10 (cfs) Flow, Q100 (cfs) Flow, WQ (cfs) A A 14.39 39 39 38 0.90 0.90 1.00 1.09 1.86 3.90 14.1 24.1 56.1 7.06 B B 22.57 44 44 43 0.90 0.90 1.00 1.01 1.72 3.59 20.5 34.9 81.0 10.26 FUTURE RUNOFF COMPUTATIONS B. Ruch January 30, 2019 Rainfall Intensity taken from the City of Fort Collins Storm Drainage Design Criteria (CFCSDDC), Figure 3.1 Q = C f ( C )( i )( A ) Basin ID Basin Area (s.f.) Basin Area (ac) Composite % Imperv. Flow, WQ (cfs) Flow, Q2 (cfs) Flow, Q100 (cfs) A 627028 14.39 90% 7.06 14.12 56.14 B 983024 22.57 90% 10.26 20.51 81.02 Future Rational Summary ATTACHMENT 2 CULVERT AND SWALE SIZING Channel Report Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Monday, Jan 28 2019 West Swale - Culvert 2 - 2yr Trapezoidal Bottom Width (ft) = 1.00 Side Slopes (z:1) = 4.00, 4.00 Total Depth (ft) = 2.50 Invert Elev (ft) = 100.00 Slope (%) = 0.50 N-Value = 0.030 Calculations Compute by: Known Q Known Q (cfs) = 20.50 Highlighted Depth (ft) = 1.27 Q (cfs) = 20.50 Area (sqft) = 7.72 Velocity (ft/s) = 2.65 Wetted Perim (ft) = 11.47 Crit Depth, Yc (ft) = 0.99 Top Width (ft) = 11.16 EGL (ft) = 1.38 0 5 10 15 20 25 30 35 Elev (ft) Depth (ft) Section 99.50 -0.50 100.00 0.00 100.50 0.50 101.00 1.00 101.50 1.50 102.00 2.00 102.50 2.50 103.00 3.00 Reach (ft) Channel Report Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Monday, Jan 28 2019 West Swale - Culvert 2 - 100yr + 33% Trapezoidal Bottom Width (ft) = 1.00 Side Slopes (z:1) = 4.00, 4.00 Total Depth (ft) = 2.50 Invert Elev (ft) = 100.00 Slope (%) = 0.50 N-Value = 0.030 Calculations Compute by: Known Q Known Q (cfs) = 105.87 Highlighted Depth (ft) = 2.44 Q (cfs) = 105.87 Area (sqft) = 26.25 Velocity (ft/s) = 4.03 Wetted Perim (ft) = 21.12 Crit Depth, Yc (ft) = 2.01 Top Width (ft) = 20.52 EGL (ft) = 2.69 0 5 10 15 20 25 30 35 Elev (ft) Depth (ft) Section 99.50 -0.50 100.00 0.00 100.50 0.50 101.00 1.00 101.50 1.50 102.00 2.00 102.50 2.50 103.00 3.00 Reach (ft) Channel Report Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Monday, Jan 28 2019 East Swale - Culvert 3 - 2yr Trapezoidal Bottom Width (ft) = 2.00 Side Slopes (z:1) = 4.00, 4.00 Total Depth (ft) = 4.00 Invert Elev (ft) = 100.00 Slope (%) = 0.50 N-Value = 0.030 Calculations Compute by: Known Q Known Q (cfs) = 28.40 Highlighted Depth (ft) = 1.34 Q (cfs) = 28.40 Area (sqft) = 9.86 Velocity (ft/s) = 2.88 Wetted Perim (ft) = 13.05 Crit Depth, Yc (ft) = 1.04 Top Width (ft) = 12.72 EGL (ft) = 1.47 0 5 10 15 20 25 30 35 40 45 Elev (ft) Depth (ft) Section 99.00 -1.00 100.00 0.00 101.00 1.00 102.00 2.00 103.00 3.00 104.00 4.00 105.00 5.00 Reach (ft) Channel Report Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Monday, Jan 28 2019 East Swale - Culvert 3 - 100yr + 33% Trapezoidal Bottom Width (ft) = 2.00 Side Slopes (z:1) = 4.00, 4.00 Total Depth (ft) = 3.00 Invert Elev (ft) = 100.00 Slope (%) = 0.50 N-Value = 0.030 Calculations Compute by: Known Q Known Q (cfs) = 146.17 Highlighted Depth (ft) = 2.65 Q (cfs) = 146.17 Area (sqft) = 33.39 Velocity (ft/s) = 4.38 Wetted Perim (ft) = 23.85 Crit Depth, Yc (ft) = 2.19 Top Width (ft) = 23.20 EGL (ft) = 2.95 0 5 10 15 20 25 30 35 40 Elev (ft) Depth (ft) Section 99.00 -1.00 100.00 0.00 101.00 1.00 102.00 2.00 103.00 3.00 104.00 4.00 Reach (ft) HY-8 Culvert Analysis Report Crossing Discharge Data Culvert 2 – Interim 100- yr Flow Discharge Selection Method: Specify Minimum, Design, and Maximum Flow Minimum Flow: 0 cfs Design Flow: 12.98 cfs Maximum Flow: 12.98 cfs Table 1 - Summary of Culvert Flows at Crossing: Culvert 2 Headwater Elevation (ft) Total Discharge (cfs) 36 Discharge (cfs) Roadway Discharge (cfs) Iterations 4898.12 0.00 0.00 0.00 1 4898.62 1.30 1.30 0.00 1 4898.83 2.60 2.60 0.00 1 4898.99 3.89 3.89 0.00 1 4899.14 5.19 5.19 0.00 1 4899.26 6.49 6.49 0.00 1 4899.38 7.79 7.79 0.00 1 4899.49 9.09 9.09 0.00 1 4899.59 10.38 10.38 0.00 1 4899.69 11.68 11.68 0.00 1 4899.78 12.98 12.98 0.00 1 4905.27 72.52 72.52 0.00 Overtopping Rating Curve Plot for Crossing: Culvert 2 Water Surface Profile Plot for Culvert: 36 Site Data - 36 Site Data Option: Culvert Invert Data Inlet Station: 113.99 ft Inlet Elevation: 4898.12 ft Outlet Station: 0.00 ft Outlet Elevation: 4897.55 ft Number of Barrels: 1 Culvert Data Summary - 36 Barrel Shape: Circular Barrel Diameter: 3.00 ft Barrel Material: Concrete Embedment: 0.00 in Barrel Manning's n: 0.0120 Culvert Type: Straight Inlet Configuration: Mitered to Conform to Slope Inlet Depression: None Table 2 - Downstream Channel Rating Curve (Crossing: Culvert 2) Tailwater Channel Data - Culvert 2 Tailwater Channel Option: Trapezoidal Channel Bottom Width: 1.00 ft Side Slope (H:V): 4.00 (_:1) Channel Slope: 0.0050 Channel Manning's n: 0.0300 Channel Invert Elevation: 4897.55 ft Roadway Data for Crossing: Culvert 2 Roadway Profile Shape: Constant Roadway Elevation Crest Length: 100.00 ft Crest Elevation: 4905.27 ft Roadway Surface: Paved Roadway Top Width: 32.00 ft Flow (cfs) Water Surface Elev (ft) Depth (ft) Velocity (ft/s) Shear (psf) Froude Number 0.00 4897.55 0.00 0.00 0.00 0.00 1.30 4897.93 0.38 1.33 0.12 0.48 2.60 4898.08 0.53 1.59 0.16 0.50 3.89 4898.18 0.63 1.76 0.20 0.51 5.19 4898.26 0.71 1.90 0.22 0.52 6.49 4898.33 0.78 2.01 0.24 0.53 7.79 4898.40 0.85 2.10 0.26 0.54 9.09 4898.45 0.90 2.19 0.28 0.54 10.38 4898.50 0.95 2.26 0.30 0.55 11.68 4898.55 1.00 2.33 0.31 0.55 12.98 4898.60 1.05 2.39 0.33 0.55 Culvert 3 – Interim 100- yr Flow Crossing Discharge Data Discharge Selection Method: Specify Minimum, Design, and Maximum Flow Minimum Flow: 0 cfs Design Flow: 17.62 cfs Maximum Flow: 17.62 cfs Table 3 - Summary of Culvert Flows at Crossing: Culvert 3 Headwater Elevation (ft) Total Discharge (cfs) 2 - 36 Discharge (cfs) Roadway Discharge (cfs) Iterations 4892.92 0.00 0.00 0.00 1 4893.33 1.76 1.76 0.00 1 4893.50 3.52 3.52 0.00 1 4893.64 5.29 5.29 0.00 1 4893.75 7.05 7.05 0.00 1 4893.85 8.81 8.81 0.00 1 4893.95 10.57 10.57 0.00 1 4894.03 12.33 12.33 0.00 1 4894.11 14.10 14.10 0.00 1 4894.19 15.86 15.86 0.00 1 4894.26 17.62 17.62 0.00 1 4900.02 144.33 144.33 0.00 Overtopping Rating Curve Plot for Crossing: Culvert 3 Water Surface Profile Plot for Culvert: 2 - 36 Site Data - 2 - 36 Site Data Option: Culvert Invert Data Inlet Station: 115.49 ft Inlet Elevation: 4892.92 ft Outlet Station: 0.00 ft Outlet Elevation: 4892.34 ft Number of Barrels: 2 Culvert Data Summary - 2 - 36 Barrel Shape: Circular Barrel Diameter: 3.00 ft Barrel Material: Concrete Embedment: 0.00 in Barrel Manning's n: 0.0120 Culvert Type: Straight Inlet Configuration: Mitered to Conform to Slope Inlet Depression: None Table 4 - Downstream Channel Rating Curve (Crossing: Culvert 3) Tailwater Channel Data - Culvert 3 Tailwater Channel Option: Trapezoidal Channel Bottom Width: 2.00 ft Side Slope (H:V): 4.00 (_:1) Channel Slope: 0.0050 Channel Manning's n: 0.0300 Channel Invert Elevation: 4892.92 ft Roadway Data for Crossing: Culvert 3 Roadway Profile Shape: Constant Roadway Elevation Crest Length: 100.00 ft Crest Elevation: 4900.02 ft Roadway Surface: Paved Roadway Top Width: 32.00 ft Flow (cfs) Water Surface Elev (ft) Depth (ft) Velocity (ft/s) Shear (psf) Froude Number 0.00 4892.92 0.00 0.00 0.00 0.00 1.76 4893.28 0.36 1.40 0.11 0.49 3.52 4893.43 0.51 1.69 0.16 0.51 5.29 4893.54 0.62 1.88 0.19 0.52 7.05 4893.64 0.72 2.03 0.22 0.53 8.81 4893.71 0.79 2.15 0.25 0.54 10.57 4893.78 0.86 2.25 0.27 0.55 12.33 4893.84 0.92 2.34 0.29 0.55 14.10 4893.90 0.98 2.42 0.31 0.56 15.86 4893.95 1.03 2.50 0.32 0.56 17.62 4894.00 1.08 2.57 0.34 0.56 HY-8 Culvert Analysis Report Crossing Discharge Data Culvert 2 – Future 100 – yr Flow Discharge Selection Method: Specify Minimum, Design, and Maximum Flow Minimum Flow: 0 cfs Design Flow: 56.14 cfs Maximum Flow: 56.14 cfs Table 1 - Summary of Culvert Flows at Crossing: Culvert 2 Headwater Elevation (ft) Total Discharge (cfs) 36 Discharge (cfs) Roadway Discharge (cfs) Iterations 4898.12 0.00 0.00 0.00 1 4899.18 5.61 5.61 0.00 1 4899.65 11.23 11.23 0.00 1 4900.05 16.84 16.84 0.00 1 4900.39 22.46 22.46 0.00 1 4900.73 28.07 28.07 0.00 1 4901.09 33.68 33.68 0.00 1 4901.51 39.30 39.30 0.00 1 4901.99 44.91 44.91 0.00 1 4902.54 50.53 50.53 0.00 1 4903.15 56.14 56.14 0.00 1 4905.27 72.52 72.52 0.00 Overtopping Rating Curve Plot for Crossing: Culvert 2 Water Surface Profile Plot for Culvert: 36 Site Data - 36 Site Data Option: Culvert Invert Data Inlet Station: 113.99 ft Inlet Elevation: 4898.12 ft Outlet Station: 0.00 ft Outlet Elevation: 4897.55 ft Number of Barrels: 1 Culvert Data Summary - 36 Barrel Shape: Circular Barrel Diameter: 3.00 ft Barrel Material: Concrete Embedment: 0.00 in Barrel Manning's n: 0.0120 Culvert Type: Straight Inlet Configuration: Mitered to Conform to Slope Inlet Depression: None Table 2 - Downstream Channel Rating Curve (Crossing: Culvert 2) Tailwater Channel Data - Culvert 2 Tailwater Channel Option: Trapezoidal Channel Bottom Width: 1.00 ft Side Slope (H:V): 4.00 (_:1) Channel Slope: 0.0050 Channel Manning's n: 0.0300 Channel Invert Elevation: 4897.55 ft Roadway Data for Crossing: Culvert 2 Roadway Profile Shape: Constant Roadway Elevation Crest Length: 100.00 ft Crest Elevation: 4905.27 ft Roadway Surface: Paved Roadway Top Width: 32.00 ft Flow (cfs) Water Surface Elev (ft) Depth (ft) Velocity (ft/s) Shear (psf) Froude Number 0.00 4897.55 0.00 0.00 0.00 0.00 5.61 4898.29 0.74 1.93 0.23 0.53 11.23 4898.54 0.99 2.30 0.31 0.55 16.84 4898.72 1.17 2.55 0.36 0.56 22.46 4898.86 1.31 2.74 0.41 0.57 28.07 4898.99 1.44 2.90 0.45 0.58 33.68 4899.10 1.55 3.04 0.48 0.59 39.30 4899.19 1.64 3.16 0.51 0.59 44.91 4899.28 1.73 3.26 0.54 0.60 50.53 4899.37 1.82 3.36 0.57 0.60 56.14 4899.45 1.90 3.45 0.59 0.61 Culvert 3 – Future 100 – yr Flow Crossing Discharge Data Discharge Selection Method: Specify Minimum, Design, and Maximum Flow Minimum Flow: 0 cfs Design Flow: 81.02 cfs Maximum Flow: 81.02 cfs Table 3 - Summary of Culvert Flows at Crossing: Culvert 3 Headwater Elevation (ft) Total Discharge (cfs) 2 - 36 Discharge (cfs) Roadway Discharge (cfs) Iterations 4892.92 0.00 0.00 0.00 1 4893.81 8.10 8.10 0.00 1 4894.21 16.20 16.20 0.00 1 4894.52 24.31 24.31 0.00 1 4894.81 32.41 32.41 0.00 1 4895.06 40.51 40.51 0.00 1 4895.30 48.61 48.61 0.00 1 4895.55 56.71 56.71 0.00 1 4895.81 64.82 64.82 0.00 1 4896.09 72.92 72.92 0.00 1 4896.41 81.02 81.02 0.00 1 4900.02 144.33 144.33 0.00 Overtopping Rating Curve Plot for Crossing: Culvert 3 Water Surface Profile Plot for Culvert: 2 - 36 Site Data - 2 - 36 Site Data Option: Culvert Invert Data Inlet Station: 115.49 ft Inlet Elevation: 4892.92 ft Outlet Station: 0.00 ft Outlet Elevation: 4892.34 ft Number of Barrels: 2 Culvert Data Summary - 2 - 36 Barrel Shape: Circular Barrel Diameter: 3.00 ft Barrel Material: Concrete Embedment: 0.00 in Barrel Manning's n: 0.0120 Culvert Type: Straight Inlet Configuration: Mitered to Conform to Slope Inlet Depression: None Table 4 - Downstream Channel Rating Curve (Crossing: Culvert 3) Tailwater Channel Data - Culvert 3 Tailwater Channel Option: Trapezoidal Channel Bottom Width: 2.00 ft Side Slope (H:V): 4.00 (_:1) Channel Slope: 0.0050 Channel Manning's n: 0.0300 Channel Invert Elevation: 4892.92 ft Roadway Data for Crossing: Culvert 3 Roadway Profile Shape: Constant Roadway Elevation Crest Length: 100.00 ft Crest Elevation: 4900.02 ft Roadway Surface: Paved Roadway Top Width: 32.00 ft Flow (cfs) Water Surface Elev (ft) Depth (ft) Velocity (ft/s) Shear (psf) Froude Number 0.00 4892.92 0.00 0.00 0.00 0.00 8.10 4893.68 0.76 2.10 0.24 0.54 16.20 4893.96 1.04 2.51 0.33 0.56 24.31 4894.17 1.25 2.79 0.39 0.58 32.41 4894.33 1.41 3.00 0.44 0.59 40.51 4894.47 1.55 3.17 0.48 0.59 48.61 4894.60 1.68 3.32 0.52 0.60 56.71 4894.71 1.79 3.45 0.56 0.61 64.82 4894.81 1.89 3.57 0.59 0.61 72.92 4894.91 1.99 3.68 0.62 0.62 81.02 4895.00 2.08 3.78 0.65 0.62 ATTACHMENT 3 DRAINAGE EXHIBIT ST / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / X X X X X X X X X X X X X X X X X X ST / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / F E S LID LID LID M SS SS SS SS SS SS SS S S VAULT ELEC / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / PROPOSED CULVERT PROPOSED 36" RCP CULVERT A 14.40 AC B 22.57 AC A B E PROSPECT RD INTERSTATE 25 REST AREA ACCESS RD SW FRONTAGE ROAD SW FRONTAGE ROAD SW FRONTAGE ROAD INTERSTATE 25 PROPOSED 2 - 36" RCP CULVERTS CULVERT 2 CULVERT 3 EAST SWALE WEST SWALE CULVERT 1 NORTH KEYMAP F E S M VAULT ELEC INTERSTATE 25 PROSPECT ROAD MCLAUGHLIN LN ( IN FEET ) 1 inch = ft. 100 0 100 Feet 100 200 300 LEGEND: PROPOSED CONTOUR PROPOSED STORM SEWER EXISTING CONTOUR PROPOSED CURB & GUTTER PROPERTY BOUNDARY PROPOSED INLET A DESIGN POINT FLOW ARROW DRAINAGE BASIN LABEL DRAINAGE BASIN BOUNDARY BENCHMARK FOR DRAINAGE REVIEW ONLY NOT FOR CONSTRUCTION C PROJECT DATUM: NAVD88 CITY OF FORT COLLINS BENCHMARK 2-01 LOCATED ON THE NORTH SIDE OF HORSETOOTH ROAD ON THE CONCRETE BASE OF THE WEST GATE POST TO THE LARGE GRAVEL PIT APPROX. 1/2 MILE EAST OF ZIEGLER ROAD. ELEVATION=4861.39 CITY OF FORT COLLINS BENCHMARK 29-01 LOCATED ON THE SOUTH SIDE OF PROSPECT ROAD, EAST OF THE INTERSECTION OF THE WEST FRONTAGE ROAD OF I-25 AND PROSPECT ROAD, EAST OF THE COLORADO WELCOME CENTER, ON A CONCRETE HEADWALL TO AN IRRIGATION PIPE. ELEVATION=4904.41 BASIS OF BEARINGS ASSUMING THE NORTH LINE OF THE NORTHEAST QUARTER OF SECTION 21, T.7N., R.69W., AS BEARING NORTH 88°38'29" WEST BEING A GRID BEARING OF THE COLORADO STATE PLANE COORDINATE SYSTEM, NORTH ZONE, NORTH AMERICAN DATUM 1983/92, A DISTANCE OF 2642.40 FEET WITH ALL OTHER BEARINGS CONTAINED HEREIN RELATIVE THERETO. FUTURE DEVELOPED DRAINAGE EXHIBIT FUTURE SITE FORT COLLINS, CO CSURF PROPERTY E NGINEER ING N O R T H E RN JANUARY 30, 2019 D:\PROJECTS\232-043\DWG\DRNG\232-043_DEV DRNG.DWG CONCEPTUAL DEVELOPED SITE PLAN Future Rational Summary Basin ID Basin Area (s.f.) Basin Area (ac) Composite % Imperv. Flow, WQ (cfs) Flow, Q2 (cfs) Flow, Q100 (cfs) A 627028 14.39 90% 7.06 14.12 56.14 B 983024 22.57 90% 10.26 20.51 81.02 X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / F E S LID LID LID M SS SS SS SS SS SS SS S S VAULT ELEC / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / PROPOSED CULVERT PROPOSED 36" RCP CULVERT A B PROPOSED 2 - 36" RCP CULVERTS CULVERT 2 CULVERT 3 EAST SWALE WEST SWALE B 19.49 AC A 19.74 AC E PROSPECT RD INTERSTATE 25 REST AREA ACCESS RD SW FRONTAGE ROAD SW FRONTAGE ROAD SW FRONTAGE ROAD INTERSTATE 25 CULVERT 1 NORTH KEYMAP F E S M VAULT ELEC INTERSTATE 25 PROSPECT ROAD MCLAUGHLIN LN ( IN FEET ) 1 inch = ft. 100 0 100 Feet 100 200 300 LEGEND: PROPOSED CONTOUR PROPOSED STORM SEWER EXISTING CONTOUR PROPOSED CURB & GUTTER PROPERTY BOUNDARY PROPOSED INLET A DESIGN POINT FLOW ARROW DRAINAGE BASIN LABEL DRAINAGE BASIN BOUNDARY BENCHMARK FOR DRAINAGE REVIEW ONLY NOT FOR CONSTRUCTION C PROJECT DATUM: NAVD88 CITY OF FORT COLLINS BENCHMARK 2-01 LOCATED ON THE NORTH SIDE OF HORSETOOTH ROAD ON THE CONCRETE BASE OF THE WEST GATE POST TO THE LARGE GRAVEL PIT APPROX. 1/2 MILE EAST OF ZIEGLER ROAD. ELEVATION=4861.39 CITY OF FORT COLLINS BENCHMARK 29-01 LOCATED ON THE SOUTH SIDE OF PROSPECT ROAD, EAST OF THE INTERSECTION OF THE WEST FRONTAGE ROAD OF I-25 AND PROSPECT ROAD, EAST OF THE COLORADO WELCOME CENTER, ON A CONCRETE HEADWALL TO AN IRRIGATION PIPE. ELEVATION=4904.41 BASIS OF BEARINGS ASSUMING THE NORTH LINE OF THE NORTHEAST QUARTER OF SECTION 21, T.7N., R.69W., AS BEARING NORTH 88°38'29" WEST BEING A GRID BEARING OF THE COLORADO STATE PLANE COORDINATE SYSTEM, NORTH ZONE, NORTH AMERICAN DATUM 1983/92, A DISTANCE OF 2642.40 FEET WITH ALL OTHER BEARINGS CONTAINED HEREIN RELATIVE THERETO. INTERIM DRAINAGE EXHIBIT INTERIM SITE FORT COLLINS, CO CSURF PROPERTY E NGINEER ING N O R T H E RN JANUARY 30, 2019 D:\PROJECTS\232-043\DWG\DRNG\232-043_INTERIM DRNG.DWG Interim Rational Summary Basin ID Basin Area (s.f.) Basin Area (ac) Composite % Imperv. Flow, WQ (cfs) Flow, Q2 (cfs) Flow, Q100 (cfs) A 860051 19.74 2% 1.34 2.68 12.98 B 843750 19.37 3% 1.88 3.76 17.62 V (ft/s) Tt (min) 2-yr Tc (min) 10-yr Tc (min) 100-yr Tc (min) A A NO 0.25 0.25 0.31 210 2.00% 18.3 18.3 16.9 1775 0.50% 1.41 20.9 0 NA N/A N/A 39 39 38 B B No 0.25 0.25 0.31 200 2.00% 17.8 17.8 16.5 2225 0.50% 1.41 26.2 0 NA N/A N/A 44 44 43 FUTURE TIME OF CONCENTRATION COMPUTATIONS Gutter Flow Swale Flow Design Point Basin Overland Flow B. Ruch January 30, 2019 Time of Concentration (Equation RO-4) ( ) 3 1 1 . 87 1 . 1 * S C Cf L Ti = − V (ft/s) Tt (min) 2-yr Tc (min) 10-yr Tc (min) 100-yr Tc (min) A A Yes 0.25 0.25 0.31 1170 0.11% 112.0 112.0 103.7 0 N/A N/A N/A 375 1.19% 1.63 3.8 116 116 108 B B Yes 0.25 0.25 0.31 1310 0.53% 71.2 71.2 65.9 0 N/A N/A N/A 0 NA N/A N/A 71 71 66 INTERIM TIME OF CONCENTRATION COMPUTATIONS Gutter Flow Swale Flow Design Point Basin Overland Flow B. Ruch January 30, 2019 Time of Concentration (Equation RO-4) ( ) 3 1 1 . 87 1 . 1 * S C Cf L Ti = − INTERSTATE 25 CSURF EXISTING ASPHALT ROAD TO BE REMOVED / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / VAULT ELEC / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / INTERSTATE 25 CSURF PROPOSED ASPHALT ROAD ASPHALT SURFACE AREA (SF) % IMPERV. IMPERV. AREA (SF) 82,441 100% ASPHALT SURFACE AREA (SF) % IMPERV. IMPERV. AREA (SF) 66,053 100% EXISTING PROPOSED 82,441 66,053 D:\PROJECTS\232-043\DWG\DRNG\232-043_IMPERVIOUS.DWG CSURF PROPERTY INTERSTATE 25 / PROSPECT ROAD FORT COLLINS 301 N. Howes Street, Suite 100 COLORADO Fort Collins, Colorado 80521 E NGINEER ING N O R T H E RN PHONE: 970.221.4158 www.northernengineering.com DESCRIPTION EXISTING VS. PROPOSED IMPERVIOUS AREA DRAWN BY B. RUCH DATE JANUARY 30, 2019 PROJECT 232-043 SK-C1 SCALE DRAWING 1"=300'