HomeMy WebLinkAboutWELLS FARGO PARKING LOT AND ATMS - FDP200016 - SUBMITTAL DOCUMENTS - ROUND 2 - 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
September 23, 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..................................................................................................... 7
VI. REFERENCES ............................................................................................... 7
VII. APPENDICES
A. Hydrologic Computations
Vicinity Map
Fort Collins Flood Map
FEMA FIRM Map Panel 08069C0979H
USGS Soil Map
Figure 3.4-1 Fort Collins Rainfall Intensity Curve
Table 3.4-1Fort Collins Rainfall Intensity Table
Table 3.2-2 Surface Type - Runoff Coefficients
Rational Method Calculated Composite C Tables
Rational Method Calculated Imperviousness
Rational Method Calculated Flows
B. Hydraulic Computations
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 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). The site is located within FEMA FIRM
panel #08069C0979H. A Floodplain Use permit will be obtained prior to starting any work
in the High Risk (100-yr) floodplain and a No-Rise Certification will accompany said
permit for any work in the floodway.
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.
PG. 2
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.
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 10” 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 2’ 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.
PG. 3
Currently, offsite flows do not enter the site property. This will not change after the site has
been developed.
III. DRAINAGE CRITERIA
A. Regulations
Drainage design criteria specified in the City of Fort Collins Storm Drainage Design Criteria
and Construction Standards manual (FCSDCM) 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. Low Impact Development (LID) requirements are
required on all new or redeveloping property which includes sites required to be brought into
compliance with the Land Use Code. These require a higher degree of water quality treatment
with one of the two following options: a) 50% of the newly added or modified impervious
area must be treated by LID techniques and 25% of new paved areas must be pervious or b)
75% of all newly added or modified impervious area must be treated by LID techniques.
For this site, we are following option b). The site improvements propose a 12,200 ft
2
asphalt
parking lot, of which 11,650 ft
2
drain to permeable pavers (95% treated with LID). Water
quality treatment for 50% of the site is provided for in the Udall Natural Area water treatment
facility.
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.
PG. 4
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.
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.
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)
PG. 5
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.
“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
PG. 6
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’.
After treatment within the permeable pavers, stormwater will infiltrate through the bottom of
the paver sections and dry well. The dry well was designed to be 8’ feet deep with 5.25’ of
clean open grade rock. A capped 8” perforated PVC conveys runoff to the alluvial soil layer,
17’ below finished grade.
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.
PG. 7
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.
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'
C/O UNDERDRAIN
INV: 93.63'
C/O UNDERDRAIN
INV: 94.49'
C/O UNDERDRAIN
INV: 93.19'
C/O UNDERDRAIN
INV: 94.66'
C/O UNDERDRAIN
INV: 93.40'
C/O UNDERDRAIN
C/O UNDERDRAIN INV: 93.89'
INV: 93.68'
C/O UNDERDRAIN
INV: 94.83'
C/O UNDERDRAIN
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