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Home My WebLink AboutWELLS FARGO PARKING LOT AND ATMS - MJA190003 - SUBMITTAL DOCUMENTS - ROUND 3 - DRAINAGE REPORTDRAINAGE REPORT FOR FINAL DRAINAGE REPORT PARKING AT 112 WEST MAGNOLIA STREET LOTS 1-2, BLOCK 113, FTC 112 WEST MAGNOLIA STREET FORT COLLINS, CO 80524 Prepared For: Wells Fargo Bank RO Box 2609 Carlsbad, CA 92018 Prepared By: Coffey Engineering & Surveying, LLC 4045 St. Cloud Drive, Suite 180 Loveland, CO 80538 970-622-2095 Project No. 2283.00 March 27, 2020 Parking at 112 West Magnolia Street FINAL DRAINAGE REPORT ENGINEER’S CERTIFICATION I hereby attest that this report for the Final Drainage Report drainage design for the Parking at 112 West Magnolia Street Project was prepared by me, or under my direct supervision, in accordance with the provisions of the City of Fort Collins Storm Drainage Design Criteria Manual. I understand that the City of Fort Collins does not and will not assume liability for drainage facilities designed by others. Ramsey J. Pickard, P.E. Registered Professional Engineer State of Colorado No. 56732 I. Table of Contents I. GENERAL LOCATION AND DESCRIPTION ......................................... 1 A. Location .................................................................................................................... 1 B. Description of Property ........................................................................................... 1 II. DRAINAGE BASINS AND SUB-BASINS .................................................. 2 A. Major Basin Description ......................................................................................... 2 B. Sub-Basin Description ............................................................................................. 2 III. DRAINAGE CRITERIA ............................................................................... 3 A. Regulations ............................................................................................................... 3 B. Implementation of the “Four Step Process” .......................................................... 3 C. Development Criteria Reference and Constraints ................................................ 4 D. Hydrological Criteria............................................................................................... 4 E. Hydraulic Criteria ................................................................................................... 5 F. Modifications of Criteria ......................................................................................... 5 IV. DRAINAGE FACILITY DESIGN ............................................................... 5 A. General Concept....................................................................................................... 5 B. Specific Details ......................................................................................................... 5 V. CONCLUSIONS ............................................................................................. 6 A. Compliance with Standards .................................................................................... 6 B. Drainage Concept..................................................................................................... 6 VI. REFERENCES ............................................................................................... 7 VII. APPENDICES A. Hydrologic Computations Vicinity Map Fort Collins Flood Map FEMA FIRM Map Panel 08069C0979H USGS Soil Map Figure 3.4-1 Fort Collins Rainfall Intensity Curve Table 3.4-1Fort Collins Rainfall Intensity Table Table 3.2-2 Surface Type - Runoff Coefficients Rational Method Calculated Composite C Tables Rational Method Calculated Imperviousness Rational Method Calculated Flows B. Hydraulic Computations 6" Inlet Pipe Calculation 6" Outlet Pipe Calculation 1' U-Channel Calculation C. Map Pocket Drainage Plan PG. 1 I. GENERAL LOCATION AND DESCRIPTION A. Location The proposed site is located in the northeast quarter (NE ¼) of Section 11, Township 7 North, Range 69 West of the 6th P.M. in the City of Fort Collins, County of Larimer, State of Colorado. Specifically, the property is located at the northwest corner of West Magnolia Street and College Avenue. The property address is 112 West Magnolia Street, Fort Collins, Colorado, 80524. (Please see the vicinity map located in the Appendix A). B. Description of Property The property’s parcel number is 9711424001. The site is located on Lots 1 and 2, Block 113 Fort Collins Subdivision and is currently a 0.44-acre gravel parking lot surrounded by the clock tower building to the north, Wells Fargo to the south, and office buildings to the east and west. The site is bound by Magnolia Street to the south, College Avenue to the east, and an alley to the west. There is an existing access to the site on all three roadways. The existing accesses on College Avenue and Magnolia Street are to be abandoned and replaced with curb & gutter. The existing access on Magnolia Street and the adjacent alley will be replaced with a new access per current LCUASS standards. The existing property is a gravel parking lot that drains south to the flowline of Magnolia Street, which drains west to an existing storm inlet. Runoff that enters College Avenue drains north towards an existing storm inlet. All runoff from the site ultimately outfalls to the Poudre River. There are generally no offsite flows that drain toward the property. The entire site is located within the City-regulatory 100-year Old Town Basin Floodplain, prepared by Anderson Consulting Engineers, July 15, 2003. The northern half of the site is located in a moderate risk area, and the southern half of the site is located within the city flood fringe (see City Flood Risk Map in Appendix A). According to the NRCS soils map survey, the native soils consist of Fort Collins Loam (a United States Department of Agriculture Type “C” soil). These soils consist chiefly of soils having a layer that impedes the downward movement of water. These soils have a slow rate of water transmission. There are no existing irrigation facilities located within the proposed site area. The proposed development will consist of the construction of a 22-space parking lot that will act as employee parking and ATM drive-through for the Wells Fargo directly across Magnolia Street. The parking lot will be asphalt with permeable pavers in the parking stalls. The existing alley will be repaved with concrete adjacent to the site. PG. 2 II. DRAINAGE BASINS AND SUB-BASINS A. Major Basin Description The proposed site is located within the Old Town Drainage Basin, located in north-central Fort Collins. The basin has a drainage area of approximately 2,120 acres, including approximately 400 acres of the Colorado State University campus. The entire basin is urbanized, with some development dating back to the late 1800s. Generally, the basin drains from west to east. The Old Town Basin receives some runoff water from the Canal Importation Basin directly west of Old Town. Most of the water from Old Town Basin drains to the Poudre River, via the City of Fort Collins storm sewer system and the Udall Natural Area. B. Sub-Basin Description Historically, most of the site drains south to Magnolia Street. Developed flow will match historic drainage patterns. The developed site is delineated into one sub-basin, with permeable pavers designed to provide the required LID and water quality for the site. Sub-basin P1, (0.44 acres), consists of an asphalt parking lot, landscaped area, and permeable pavers. Rainfall travels via overland flow for short distances to curb & gutters of the proposed parking lot and to the permeable pavers in the parking stalls. The pavers in the parking stalls incorporate the City of Fort Collins LID and water quality features, which treats the water by filtering it through a 4” layer of #57 base, followed by a 12” layer of #2 rock base. The water is then collected in perforated PVC sub-drains and routed to a proposed dry well stormwater collection system. Stormwater will infiltrate into the soil through the bottom of the permeable pavers and dry well. Excess stormwater will drain through a 1’ U-channel to the flowline of Magnolia Street and into the existing storm sewer inlet. This site is located within a City recognized inadvertent stormwater storage area. The “College and Mulberry” storage pond extends several blocks each direction from this intersection (north, south and west of College and Mulberry). All site work within this storage area may not reduce the stormwater storage volume. As such, there shall be no net-fill for the proposed grading at this site. The proposed grading for the site has a net-cut condition of approximately 18 cubic yards. Currently, offsite flows do not enter the site property. This will not change after the site has been developed. PG. 3 III. DRAINAGE CRITERIA A. Regulations Drainage design criteria specified in the Fort Collins Stormwater Criteria Manual and the Urban Storm Drainage Criteria Manual, Volume 3 by the Urban Drainage and Flood Control District (UDFCD) have been referenced in the preparation of this study. B. Implementation of the “Four Step Process” Our stormwater management strategy utilizes the “Four Step Process” to minimize adverse impacts of urbanization on receiving waters, as follows: Step 1 – Employ Runoff Reduction Practices. The first consideration taken in trying to reduce the stormwater impacts of this development is the site selection itself. The land use for the site remains unchanged. The existing site is a gravel parking lot, but to provide a higher level of service to their employees, Wells Fargo is paving the parking lot. This will reduce the amount of dirt that is tracked on to the paved streets in the area by vehicles and during precipitation events. Step 2 – Implement BMPs That Provide a Water Quality Capture Volume (WQCV) with Slow Release. The primary water quality control will occur in the permeable paver sub-base, located under the parking spaces of the lot. Refer to the Major Amendment plan set for permeable paver details and cross-sections. The permeable pavers will increase water quality and promote infiltration. The standard water quality requirement is provided for in the Udall Natural Area water treatment facility. Step 3 – Stabilize Drainageways. The Poudre River is the governing drainageway for the proposed site. By improving the water quality and increasing infiltration, the likelihood of bed and bank erosion from this site is reduced. PG. 4 Step 4 – Implement Site Specific and Other Source Control BMPs. Permeable Pavement Systems: Flow from the parking lot will directly flow into the void area of the pavers sub-base, avoiding any extra pollutant-flow contact time and providing water quality. Landscaping: Personnel from Coffey Engineering and CS Design worked with the City of Fort Collins Forestry Department to preserve a large tree on the southwest side of the parking lot. Interception storage, the water caught by plants at the onset of a rainstorm, is significant when a large tree shades a small lot. Some amount of the intercepted water evaporates, never reaching the ground. Additionally, water retained by the leaves and branches moves more slowly through the hydrograph. In the case of this tree, the canopy hangs directly over proposed impervious asphalt area. C. Development Criteria Reference and Constraints The criteria used as the basis for analysis and design of stormwater management improvements for this site are found in the references cited. There is a master planned “Magnolia Outfall Pipe” that is planned in Magnolia Street, directly south of this site. This capital improvement will consist of a future 108-inch diameter storm pipe in Magnolia Street. There is no set time frame when this outfall improvement will be constructed. This future pipe does not impact or change drainage requirements for the present project. D. Hydrological Criteria Stormwater runoff is analyzed for storms with 2-year and 100-year return frequencies. The Rational Method was chosen for this small site. The Rational Method provides that: Q = CIA, where: Q = Design flow in cubic feet per second (cfs) C = Coefficient of runoff for the area under consideration I = Rainfall intensity for the design storm duration (in/hr) A = Area of the drainage sub-basin under consideration (ac) Peak flows were calculated using the Rational Method for the 2-year and 100-year storm events. This software uses the local 1-hour rainfall depth and Fort Collins rainfall intensities, calculated as a function of the time of concentration. These values were obtained by the City of Fort Collins Rainfall Intensity-Duration-Frequency (IDF) curve/table; Figure 3.4-1 and Table 3.4-1 found in the Fort Collins Stormwater Criteria Manual, and can be found in Appendix A. Additionally, per the City of Fort Collins, the “C’ coefficients have been multiplied by the appropriate storm factors. PG. 5 “C” values were taken from Table 3.2-2, Surface Types – Runoff Coefficients (See Appendix A). Soils of hydrologic soil type “C” dominate the site. Onsite runoff was calculated to determine the runoff differential between existing and developed conditions for use in sizing the WQCV as required by the FCSDM. The hydrologic basin parameters and runoff rates are included in the Appendices. E. Hydraulic Criteria Within this development, all runoff will be conveyed on the surface, initially as sheet flow and subsequently as concentrated flow in gutters. The assessment of required capacity and the sizing of the respective components of the drainage system are based on the anticipated runoff from the 100-year storm event. The surface runoff will culminate into the permeable pavers. F. Modifications of Criteria There are no modifications or variances requested in connection with the design of the stormwater management for the parking at 112 West Magnolia site development. IV. DRAINAGE FACILITY DESIGN A. General Concept The storm drainage system is designed to safely convey developed storm flows by sheet flow, concentrated pan, underdrain, and gutter flow to the flowline of Magnolia Street. The design worksheets included in the Appendices to this Final Drainage Report present details of the hydrologic and hydraulic calculations pertinent to the design of the on-site storm drainage system. A drainage plan, showing the proposed development of the site and developed drainage patterns is included in the map pocket following the Appendices. B. Specific Details Sub-basin P1, (0.44 acres), consists of the concrete parking lot, landscaped area, and permeable pavers. Rainfall travels via overland flow to the gutter flowline of the parking area into the permeable pavers. Overland flow will infiltrate into the permeable pavers in the parking stalls, where it will be treated. The dry well and paver system will fill to an elevation of 4994.80’. Once runoff reaches this elevation, water is released, via a 6” PVC pipe and concrete U-channel to the flowline of Magnolia Street. The low point of the paver system is 4994.90’. PG. 6 After treatment within the permeable pavers, stormwater will infiltrate through the bottom of the paver sections and dry well. If the paver system overflows due to clogging, catch basins at the low point of the pavers will direct runoff into the underdrain system. When improvements are being added to an existing developed site, onsite detention is only required if there is an increase in impervious area greater than 5,000 square feet in the Old Town Basin. The effective impervious area for the existing site is 7,602 square feet and the effective impervious area for the proposed site is 12,205 square feet, a difference of 4,603 square feet. Since the effective impervious area added to the site is under 5,000 square feet, detention is not required. Effective Impervious Summary Condition Effective Impervious Area (SF) Existing Site 7,602 Proposed Site 12,205 Difference 4,603 Sub-basin P1 produces a 100-year flow of 3.48 cfs. The Modified FAA spreadsheet was created to incorporate rainfall data from the Fort Collins Stormwater Criteria Manual, Table 3.4-1. This spreadsheet was used to calculate the inflows and outflows from the site. With permeable pavers, the City of Fort Collins does not require a volume treatment based on WQCV. The treatment method is filtration and infiltration. The pavers criteria is a maximum run-on:pavers ratio of 3:1. The sub-base under the pavers is designed per Fort Collins Detail D-54, Interlocking Pavers Cross Section. The water quality volume is held in the 10” #2 rock layer. V. CONCLUSIONS A. Compliance with Standards The drainage design for the Parking at 112 West Magnolia Street follows the requirements of the Fort Collins Stormwater Criteria Manual as well as the City’s floodplain regulations. The criteria and recommendations of the Urban Storm Drainage Criteria Manual are also reflected in the design of the drainage systems. B. Drainage Concept The drainage design for the Parking at 112 West Magnolia Street will safely convey onsite flows from the parking lot into the existing storm inlet, via the permeable paver detention system. Permeable pavers and the preservation of an existing large tree help to minimize the impact of the development to the surrounding properties. Water quality and LID treatment will be achieved by the permeable paver system. PG. 7 VI. REFERENCES “Fort Collins Stormwater Criteria Manual”, City of Fort Collins, Adopted December 2018. “City of Fort Collins Municipal Code”, Chapter 10 – Flood Protection and Prevention City of Fort Collins, 1987. Urban Storm Drainage Criteria Manual, Volumes 1, 2, and 3, Urban Drainage and Flood Control District, April 2008. VII. APPENDICES A. Hydrologic Computations Vicinity Map Fort Collins Flood Map FEMA FIRM Map Panel 08069C0979H USGS Soil Map Figure 3.4-1 Fort Collins Rainfall Intensity Curve Table 3.4-1Fort Collins Rainfall Intensity Table Table 3.2-2 Surface Type - Runoff Coefficients Rational Method Calculated Composite C Tables Rational Method Calculated Imperviousness Rational Method Calculated Flows S COLLEGE AVE W MAGNOLIA ST . Printed: 03/25/2016 All floodplain boundaries are approximate. This information is based on the Federal Emergency Management Agency (FEMA) Flood Insurance Rate Map (FIRM) and the City of Fort Collins Master Drainageway Plans. This letter does not imply that the referenced property will or will not be free from flooding or damage. A property not in the Special Flood Hazard Area or in a City Designated Floodplain may be damaged by a flood greater than that predicted on the map or from a local drainage problem not shown on the map. This map does not create liability on the part of the City, or any officer or employee thereof, for any damage that results from reliance on this information. City Flood Risk Map Moderate Risk May include: - Areas of FEMA 500-year floodplain (FEMA Zone X-shaded). - Areas of FEMA or City 100-year floodplain (sheet flow) with average depths of less than 1 foot. - Areas protected by levees from the 100-year flood. Low Risk Areas outside of FEMA and City mapped 100-year and 500-year floodplains. Local drainage problems may still exist. City Flood Fringe - May Include: - Areas of FEMA 100-year floodplain (FEMA Zones A, AE, AO, and AH) - Areas of City 100-year floodplain including ponding areas and sheet flow areas with average depths of 1-3 feet. There is a 1% annual chance that these areas will be flooded. High Risk City Floodway - Area of 100-year floodplain with greatest depths and fastest velocities. 0 15 30 60 90 120 Feet 35 C 0.5 0.5 112 W Magnolia Street 8/18/2016 FORT COLLINS STORMWATER CRITERIA MANUAL Hydrology Standards (Ch. 5) 3.0 Rational Method 3.4 Intensity-Duration-Frequency Curves for Rational Method Page 9 Figure 3.4-1. Rainfall IDF Curve – Fort Collins FORT COLLINS STORMWATER CRITERIA MANUAL Hydrology Standards (Ch. 5) 3.0 Rational Method 3.4 Intensity-Duration-Frequency Curves for Rational Method Page 8 Table 3.4-1. IDF Table for Rational Method Duration (min) Intensity 2-year (in/hr) Intensity 10-year (in/hr) Intensity 100-year (in/hr) Duration (min) Intensity 2-year (in/hr) Intensity 10-year (in/hr) Intensity 100-year (in/hr) 5 2.85 4.87 9.95 39 1.09 1.86 3.8 6 2.67 4.56 9.31 40 1.07 1.83 3.74 7 2.52 4.31 8.80 41 1.05 1.80 3.68 8 2.40 4.10 8.38 42 1.04 1.77 3.62 9 2.30 3.93 8.03 43 1.02 1.74 3.56 10 2.21 3.78 7.72 44 1.01 1.72 3.51 11 2.13 3.63 7.42 45 0.99 1.69 3.46 12 2.05 3.50 7.16 46 0.98 1.67 3.41 13 1.98 3.39 6.92 47 0.96 1.64 3.36 14 1.92 3.29 6.71 48 0.95 1.62 3.31 15 1.87 3.19 6.52 49 0.94 1.6 3.27 16 1.81 3.08 6.30 50 0.92 1.58 3.23 17 1.75 2.99 6.10 51 0.91 1.56 3.18 18 1.70 2.90 5.92 52 0.9 1.54 3.14 19 1.65 2.82 5.75 53 0.89 1.52 3.10 20 1.61 2.74 5.60 54 0.88 1.50 3.07 21 1.56 2.67 5.46 Composite C Values WELLS FARGO PARKING EXPANSION Asphalt Area (acres) Concrete Area (acres) Gravel (acres) Pavers (acres) Lawns (acres) Total Area Minor (2-YR) Major (100-YR) (C = 0.95) (C = 0.95) (C = 0.50) (C = 0.50) (C = 0.10) (acres) Composite "C" Composite "C" (Cf x C) E1 E1 0.00 0.00 0.44 0.00 0.00 0.44 0.47 0.59 Alley Alley 0.04 0.00 0.00 0.00 0.01 0.05 0.84 1.00 P1 P1 0.20 0.04 0.00 0.08 0.12 0.44 0.64 0.80 Alley Alley 0.00 0.047 0.00 0.00 0.00 0.05 0.95 1.00 Notes: Composite C values obtained from Table 3.2-2 Major Storm Runoff factored per Table 3.2-3 Developed Design Point Basin(s) Existing RJP Wells Fargo Rational Method.xlsx 1/23/2020 Impeviousness WELLS FARGO PARKING EXPANSION Asphalt Area (acres) Concrete Area (acres) Gravel (acres) Pavers (acres) Lawns (acres) Total Area Percent Effective Impervious Area (I = 100) (I = 100) (I = 40) (I = 40) (I = 0) (acres) Imperviousness (S.F) E1 E1 0.00 0.00 0.44 0.00 0.00 0.44 40% 7,602.40 Alley Alley 0.04 0.00 0.00 0.00 0.01 0.05 88% 1840.0 P1 P1 0.20 0.04 0.00 0.08 0.12 0.44 62% 11,856.95 Alley Alley 0.00 0.05 0.00 0.00 0.00 0.05 100% 2,090.90 Notes: Notes: Values from Fort Collins Stormwater Criteria Manual Table 4.1-3 Design Point Basin (s) Existing Developed RJP Wells Fargo Rational Method.xlsx 1/23/2020 Basin Flow Calculations WELLS FARGO PARKING EXPANSION Area Minor Major (acres) Composite "C" Composite "C" Length (ft) Slope (%) Minor tov (min)a Major tov (min)a Length (ft) Slope (%) Channel Type Velocity (fps)c tt (min) Minor TC (min) Major TC (min) 2-yr 10-yr 100-yr 2-yr 10-yr 100-yr E1 E1 0.44 0.47 0.59 100 1.50 10.29 8.37 0 0.60 PA 1.55 0.00 10.29 8.37 2.17 3.71 8.21 0.44 0.76 2.10 Alley Alley 0.05 0.84 1.00 20 1.50 1.87 0.73 88 1.00 PA 2.00 0.73 5.00 5.00 2.85 4.87 9.95 0.12 0.20 0.48 P1 P1 0.44 0.64 0.80 69 2.00 5.72 3.75 0 1.00 PA 2.00 0.0000 5.72 5.00 2.76 4.72 9.95 0.77 1.32 3.48 Alley Alley 0.05 0.95 1.00 20 1.50 1.10 0.73 88 1.00 PA 2.00 0.7333 5.00 5.00 2.85 4.87 9.95 0.13 0.22 0.47 Notes: b HM = Heavy Meadow, TF = Tillage/field, PL = Short pasture and lawns, BG = Nearly bare ground, GW = Grassed Waterway, PA = Paved Areas c Velocity alues from Figure 3-3/Table RO-2 Estimate of Average Flow Velocity for use with the Rational Method Design Point Developed Existing Initial/Overland Time Final TC Intensity (in/hr) Basin Flows (cfs) Basin (s) Travel Time RJP Wells Fargo Rational Method.xlsx 1/23/2020 B. Hydraulic Computations 6” Inlet Pipe Calculation 6" Outlet Pipe Calculation 1' U-Channel Calculation Channel Report Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Thursday, Jan 23 2020 6 Inch PVC Inlet Pipe Circular Diameter (ft) = 0.50 Invert Elev (ft) = 4994.78 Slope (%) = 1.00 N-Value = 0.012 Calculations Compute by: Known Q Known Q (cfs) = 0.44 Highlighted Depth (ft) = 0.32 Q (cfs) = 0.440 Area (sqft) = 0.13 Velocity (ft/s) = 3.31 Wetted Perim (ft) = 0.93 Crit Depth, Yc (ft) = 0.34 Top Width (ft) = 0.48 EGL (ft) = 0.49 0 1 2 Elev (ft) Section 4994.00 4994.50 4995.00 4995.50 4996.00 Reach (ft) Channel Report Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Thursday, Jan 23 2020 6 Inch PVC Outlet Pipe Circular Diameter (ft) = 0.50 Invert Elev (ft) = 4994.78 Slope (%) = 0.50 N-Value = 0.012 Calculations Compute by: Known Q Known Q (cfs) = 0.44 Highlighted Depth (ft) = 0.43 Q (cfs) = 0.440 Area (sqft) = 0.18 Velocity (ft/s) = 2.45 Wetted Perim (ft) = 1.19 Crit Depth, Yc (ft) = 0.34 Top Width (ft) = 0.35 EGL (ft) = 0.52 0 1 2 Elev (ft) Section 4994.00 4994.50 4995.00 4995.50 4996.00 Reach (ft) Channel Report Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Tuesday, Oct 22 2019 1 Foot U-Channel Rectangular Bottom Width (ft) = 1.00 Total Depth (ft) = 0.50 Invert Elev (ft) = 4994.78 Slope (%) = 0.50 N-Value = 0.013 Calculations Compute by: Known Q Known Q (cfs) = 0.45 Highlighted Depth (ft) = 0.21 Q (cfs) = 0.450 Area (sqft) = 0.21 Velocity (ft/s) = 2.14 Wetted Perim (ft) = 1.42 Crit Depth, Yc (ft) = 0.19 Top Width (ft) = 1.00 EGL (ft) = 0.28 0 .25 .5 .75 1 1.25 1.5 Elev (ft) Depth (ft) Section 4994.00 -0.78 4994.50 -0.28 4995.00 0.22 4995.50 0.72 4996.00 1.22 Reach (ft) C. Map Pocket Drainage Plan E E E E E E E FO VB S (OHP) (OHP) (OHP) (OHP) (OHP) (FO) (GAS) (FO) (GAS) (GAS) (GAS) (GAS) (GAS) (GAS) (GAS) (GAS) (GAS) (GAS) (GAS) (GAS) (GAS) (GAS) (GAS) (GAS) (GAS) (GAS) (GAS) (GAS) (GAS) (FO) (FO) (FO) (FO) (FO) (FO) (FO) (FO) (FO) (FO) (FO) (FO) (FO) (FO) (FO) (FO) (FO) (FO) (FO) (FO) (FO) (FO) (FO) (FO) (FO) (FO) (FO) (FO) (FO) (FO) (FO) (GAS) (GAS) (GAS) (GAS) (GAS) (GAS) (GAS) (GAS) (GAS) (GAS) (GAS) (GAS) (GAS) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) (UP) SS SS SS SS SS SS SS SS SS SS SS SS SS SS SS W W W W W W W W W W W W W W W W W W W W W W W W W W W W W W W W W EXISTING BUILDING MAGNOLIA STREET 20.0' ROW 18.81' PROPERTY LINE EXISTING STORM INLET LINCOLN CENTER FLOODPLAIN REVISION HEC-RAS MODEL CROSS-SECTION RIVER: MAGNOLIA7 REACH: MASON-COLLEGE RIVER STATION: 2068 BASE FLOOD ELEVATION: 4995.8' (NAVD88) FLOODWAY BOUNDARY INV: 94.78' PROPOSED SIDEWALK CHASE PROPOSED 1' U-CHANNEL PROPOSED 2' U-CHANNEL 20.0' ROW FORT COLLINS 100-YR FLOOD FRINGE FORT COLLINS 100-YEAR FLOODWAY FORT COLLINS 100-YEAR FLOOD FRINGE FORT COLLINS 100-YEAR FLOODWAY FORT COLLINS 100-YEAR FLOOD FRINGE DRAINS TO PAVER SECTION #2 AREA = 632 SQ FT DRAINS TO STREET AREA = 278 SQ FT FORT COLLINS MODERATE RISK FLOODPLAIN LANDSCAPING AREA FORT COLLINS 100-YEAR FLOOD FRINGE FORT COLLINS 100-YEAR FLOODWAY FORT COLLINS 100-YEAR FLOOD FRINGE PAVER SECTION #1 PAVER SECTION #2 PAVER SECTION #4 DRAINS TO PAVER SECTION #1 AREA = 1,262 SQ FT DRAINS TO PAVER SECTION #4 AREA = 3,235 SQ FT FORT COLLINS MODERATE RISK FLOODPLAIN DRAINS TO PAVER SECTION #5 AREA = 2,144 SQ FT PAVER SECTION #3 PAVER SECTION #5 DRAINS TO PAVER SECTION #3 AREA = 1,529 SQ FT DRAINS TO STREET AREA = 418 SQ FT 10.7 LF OF 4" PVC @12.1% 6.0 LF OF 6" PVC @1.0% 6.0 LF OF 6" PVC @0.5% PROPOSED 1' CURB CUT ELEVATION: 94.31' 4996 4996 4996 4996 4996 4997 4996 4995 4995 4995 4997 4996 4996 4996 4996 PROPOSED 36" DRY WELL INV. IN =93.13' INV. OUT 94.81' C/O UNDERDRAIN INV: 93.89' C/O UNDERDRAIN INV: 93.96' 8" CATCH BASIN INV: 93.63' C/O UNDERDRAIN INV: 94.49' 8" CATCH BASIN INV: 93.19' 8" CATCH BASIN INV: 94.66' C/O UNDERDRAIN INV: 93.40' 8" CATCH BASIN 8" CATCH BASIN INV: 93.89' INV: 93.68' C/O UNDERDRAIN INV: 94.83' 8" CATCH BASIN INV: 93.82 C/O UNDERDRAIN INV: 93.82' 30.8 LF OF 4" PERFORATED PVC PIPE 55.9 LF OF 4" PERFORATED PVC PIPE 12.6 LF OF 4" PERFORATED PVC PIPE @ 1.3% 38.6 LF OF 4" PERFORATED PVC PIPE 42.4 LF OF 4" PVC @ 0.5% 45.9 LF OF 4" PVC @ 0.5% 24.5 LF OF 4" PVC @ 0.8% 9.9 LF OF 4" PVC @ 0.5% 27.0 LF OF 4" PVC @ 4.6% 13.6 LF OF 4" PVC @ 0.5% 29.9 LF OF 4" PERFORATED PVC PIPE @ 0.9% POTENTIAL OVERFLOW PATH PONDING DEPTH: 0.5' POTENTIAL OVERFLOW PATH PONDING DEPTH: 0.47' POTENTIAL OVERFLOW PATH PONDING DEPTH: 0.5' POTENTIAL OVERFLOW PATH PONDING DEPTH: 0.24' DRAINAGE PLAN C5.0 10' SCALE: 1" = 10' 0 20' DRAINAGE LEGEND D1 112 W. MAGNOLIA ST. PARKING 112 WEST MAGNOLIA STREET FORT COLLINS CO, 80525 FOR BURIED UTILITY INFORMATION THREE (3) BUSINESS DAYS BEFORE YOU DIG CALL 811 (OR 1-800-922-1987) UTILITY NOTIFICATION CENTER OF COLORADO (UNCC) WWW.UNCC.ORG R P1 L.I.D. LEGEND BASIN ID MINOR "C" COEFFICIENT MAJOR "C" COEFFICIENT DRAINAGE AREA CITY OF FORT COLLINS, COLORADO UTILITY PLAN APPROVAL E1 N SYMBOL LEGEND SANITARY LINE MAJOR CONTOUR MINOR CONTOUR CENTER LINE EASEMENT CONCRETE SIDEWALK FENCE UNDERGROUND TELEPHONE WATER MAIN UNDERGROUND POWER GAS LINE RIGHT-OF-WAY PROPERTY BOUNDARY FLOW LINE G G (UP) (UT) SS X WS WS WS WS WS SS FIRE HYDRANT WATER VALVE R/W WS WATER SERVICE LINE W R/W (OHP) OVERHEAD UTILITY EDGE OF ASPHALT DEMOLISH EXISTING STRUCTURE 10.00 2.05% W W FS E E E 11 FLOODPLAIN NOTES ENGINEERING & SURVEYING 4045 St. Cloud Drive, Suite 180 Loveland, CO 80538 [P] 970-622-2095 [F] 970-461-4469 DIRECTION OF FLOW WITH SLOPE AMOUNT SPOT ELEVATION MAJOR CONTOUR MINOR CONTOUR CONCRETE/ASPHALT DRIVE CONCRETE SIDEWALK EMERGENCY ACCESS BOUNDS FLOW LINE UNDERGROUND ELECTRIC LINE RIGHT-OF-WAY SANITARY LINE STORM SEWER PIPE FIRE LINE WATER LINE WATER SERVICE LINE PARKING COUNT WATER METER/ CURB STOP SANITARY SEWER MANHOLE SANITARY SEWER MANHOLE 55 0.87 1.48 3.03 22 1.53 2.61 5.32 56 0.86 1.47 2.99 23 1.49 2.55 5.20 57 0.85 1.45 2.96 24 1.46 2.49 5.09 58 0.84 1.43 2.92 25 1.43 2.44 4.98 59 0.83 1.42 2.89 26 1.4 2.39 4.87 60 0.82 1.4 2.86 27 1.37 2.34 4.78 65 0.78 1.32 2.71 28 1.34 2.29 4.69 70 0.73 1.25 2.59 29 1.32 2.25 4.60 75 0.70 1.19 2.48 30 1.30 2.21 4.52 80 0.66 1.14 2.38 31 1.27 2.16 4.42 85 0.64 1.09 2.29 32 1.24 2.12 4.33 90 0.61 1.05 2.21 33 1.22 2.08 4.24 95 0.58 1.01 2.13 34 1.19 2.04 4.16 100 0.56 0.97 2.06 35 1.17 2.00 4.08 105 0.54 0.94 2.00 36 1.15 1.96 4.01 110 0.52 0.91 1.94 37 1.16 1.93 3.93 115 0.51 0.88 1.88 38 1.11 1.89 3.87 120 0.49 0.86 1.84