HomeMy WebLinkAboutPOUDRE GARAGE - BASIC DEVELOPMENT REVIEW - BDR160007 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTMarch 2, 2016
PRELIMINARY DRAINAGE REPORT FOR
POUDRE GARAGE
Fort Collins, Colorado
Prepared for:
Poudre Garage, LLC
148 Remington Street
Fort Collins, Colorado 80524
Prepared by:
200 South College Avenue, Suite 10
Fort Collins, Colorado 80524
Phone: 970.221.4158 Fax: 970.221.4159
www.northernengineering.com
Project Number: 998-002
This Drainage Report is consciously provided as a PDF.
Please consider the environment before printing this document in its entirety.
When a hard copy is absolutely necessary, we recommend double-sided printing.
March 2, 2016
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, Colorado 80521
RE: Preliminary Drainage Report for
POUDRE GARAGE
Dear Staff:
Northern Engineering is pleased to submit this Preliminary Drainage Report for your review. This
report accompanies the Project Development Plan submittal for the proposed Poudre Garage.
This report has been prepared in accordance to Fort Collins Stormwater Criteria Manual (FCSCM),
and serves to document the stormwater impacts associated with the proposed project. We
understand that review by the City is to assure general compliance with standardized criteria
contained in the FCSCM.
If you should have any questions as you review this report, please feel free to contact us.
Sincerely,
NORTHERN ENGINEERING SERVICES, INC.
Frederick S. Wegert, PE
Project Engineer
Downtown Fort Collins Hotel Parking Garage Alternative
Preliminary Drainage Report
TABLE OF CONTENTS
I. GENERAL LOCATION AND DESCRIPTION ................................................................... 1
A. Location ............................................................................................................................................. 1
B. Description of Property ..................................................................................................................... 2
C. Floodplain.......................................................................................................................................... 3
II. DRAINAGE BASINS AND SUB-BASINS ....................................................................... 4
A. Major Basin Description .................................................................................................................... 4
B. Sub-Basin Description ....................................................................................................................... 4
III. DRAINAGE DESIGN CRITERIA ................................................................................... 4
A. Regulations........................................................................................................................................ 4
B. Four Step Process .............................................................................................................................. 5
C. Development Criteria Reference and Constraints ............................................................................ 5
D. Hydrological Criteria ......................................................................................................................... 6
E. Hydraulic Criteria .............................................................................................................................. 6
F. Modifications of Criteria ................................................................................................................... 6
IV. DRAINAGE FACILITY DESIGN .................................................................................... 6
A. General Concept ............................................................................................................................... 6
B. Specific Details .................................................................................................................................. 7
V. CONCLUSIONS ........................................................................................................ 8
A. Compliance with Standards .............................................................................................................. 8
B. Drainage Concept .............................................................................................................................. 8
APPENDICES:
APPENDIX A -- Developed Conditions Hydrologic Computations
APPENDIX B – LID Design Computations
LIST OF FIGURES:
Downtown Fort Collins Hotel Parking Garage Alternative
Preliminary Drainage Report
Figure 1 - Vicinity Map ........................................................................................................ 1
Figure 2 – Aerial Photograph ................................................................................................ 2
Figure 3 – Proposed Site Plan ............................................................................................... 3
Figure 4 – Area Floodplain Mapping ...................................................................................... 4
MAP POCKET:
Proposed Drainage Exhibit
Downtown Fort Collins Hotel Parking Garage Alternative
Preliminary Drainage Report 1
I. GENERAL LOCATION AND DESCRIPTION
A. Location
Figure 1 - Vicinity Map
1. The project site is located in the southwest quarter of Section 12, Township 7 North,
Range 69 West of the 6th Principal Meridian, City of Fort Collins, County of Larimer,
State of Colorado.
2. The project site is located at 148 Remington Street at northwest corner of the
intersection of Remington Street and Oak Street.
3. The project site lies within the Old Town Basin. The site drains to the storm sewer
system in Oak Street, which is conveyed east to the Udall Water Quality Treatment
Area, and ultimately discharging into the Cache La Poudre River. The proposed
impervious area for the site is 3,328 square feet, and detention is not required since
the proposed impervious area is less than the required 5,000 square feet. However,
the site still must provide current City Low Impact Design (LID) requirements. Water
quality treatment methods are described in further detail below.
4. As this is an infill site, the area surrounding the site is fully developed.
5. No offsite flows enter the site from the north, south, east or west.
Downtown Fort Collins Hotel Parking Garage Alternative
Preliminary Drainage Report 2
B. Description of Property
1. The development area is roughly 0.16 net acres (6,995 square feet).
Figure 2 – Aerial Photograph
2. The subject property is currently composed of existing buildings and a hard-packed
dirt parking lot. Existing ground slopes are mild (i.e., 1 - 4±%) through the interior of
the property. General topography slopes from north to south.
3. According to the United States Department of Agriculture (USDA) Natural Resources
Conservation Service (NRCS) Soil Survey website:
http://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx,
the site consists of Satanta loam (Hydrologic Soil Group B).
4. The proposed project site plan is composed of expanding the existing building to
include a mixed use of commercial, residential, and covered parking for the residential
units. Associated site work, water, and sewer lines will be constructed with the
development. Current City Low Impact Design (LID) requirements will be
implemented with the project, and will consist of several LID features which are
discussed in Section IV, below.
Downtown Fort Collins Hotel Parking Garage Alternative
Preliminary Drainage Report 3
Figure 3 – Proposed Site Plan
5. There are no known irrigation laterals crossing the site.
6. The proposed land use is mixed use.
C. Floodplain
1. The project site is not encroached by any City or FEMA designated 100-year
floodplain.
Downtown Fort Collins Hotel Parking Garage Alternative
Preliminary Drainage Report 4
Figure 4 – Area Floodplain Mapping
II. DRAINAGE BASINS AND SUB-BASINS
A. Major Basin Description
1. The project site lies within the Old Town Basin. Generally, detention requirements for
this basin are to detain the difference between the 100-year developed inflow rate
and the historic 2-year release rate. However, the site drains to the storm sewer
system in Oak Street and conveyed to the Udall Water Quality Treatment Area. As
long as existing site runoff rates are not increased, detention is not required for the
site. However, the site must comply with current City Low Impact Design (LID)
requirements. Water quality treatment methods are described in further detail below.
B. Sub-Basin Description
1. The subject property historically drains overland from north to south. Runoff from the
majority of the site has historically been collected in existing inlets located within
Remington Street and Oak Street.
2. A more detailed description of the project drainage patterns is provided below.
III. DRAINAGE DESIGN CRITERIA
A. Regulations
There are no optional provisions outside of the FCSCM proposed with the proposed
project.
Downtown Fort Collins Hotel Parking Garage Alternative
Preliminary Drainage Report 5
B. Four Step Process
The overall stormwater management strategy employed with the proposed project utilizes
the “Four Step Process” to minimize adverse impacts of urbanization on receiving waters.
The following is a description of how the proposed development has incorporated each
step.
Step 1 – Employ Runoff Reduction Practices
Several techniques have been utilized with the proposed development to facilitate the
reduction of runoff peaks, volumes, and pollutant loads as the site is developed from the
current use by implementing multiple Low Impact Development (LID) strategies including:
Conserving existing amenities in the site including the existing vegetated areas.
Providing vegetated open areas throughout the site to reduce the overall impervious
area and to minimize directly connected impervious areas (MDCIA).
Routing flows, to the extent feasible, through vegetated areas to increase time of
concentration, promote infiltration and provide initial water quality.
Step 2 – Implement BMPs That Provide a Water Quality Capture Volume (WQCV) with
Slow Release
The efforts taken in Step 1 will facilitate the reduction of runoff; however, urban
development of this intensity will still generate stormwater runoff that will require
additional BMPs and water quality. The stormwater runoff from the site will be
intercepted and treated using rain gardens.
Step 3 – Stabilize Drainageways
There are no major drainageways within the subject property. While this step may not
seem applicable to proposed development, the project indirectly helps achieve stabilized
drainageways nonetheless. By providing water quality treatment, where none previously
existed, sediment with erosion potential is removed from downstream drainageway
systems. Furthermore, this project will pay one-time stormwater development fees, as
well as ongoing monthly stormwater utility fees, both of which help achieve City-wide
drainageway stability.
Step 4 – Implement Site Specific and Other Source Control BMPs.
The proposed project will improve upon site specific source controls compared to historic
conditions:
The proposed development will provide LID features which enhance water quality;
thus, eliminating sources of potential pollution previously left exposed to weathering
and runoff processes.
C. Development Criteria Reference and Constraints
The subject property is surrounded by currently developed properties. Thus, several
constraints have been identified during the course of this analysis that will impact the
proposed drainage system including:
Existing elevations along the property lines will generally be maintained.
Downtown Fort Collins Hotel Parking Garage Alternative
Preliminary Drainage Report 6
As previously mentioned, overall drainage patterns of the existing site will be
maintained.
Elevations of existing downstream facilities that the subject property will release to
will be maintained.
D. Hydrological Criteria
1. The City of Fort Collins Rainfall Intensity-Duration-Frequency Curves, as depicted in
Figure RA-16 of the FCSCM, serve as the source for all hydrologic computations
associated with the proposed development. Tabulated data contained in Table RA-7
has been utilized for Rational Method runoff calculations.
2. The Rational Method has been employed to compute stormwater runoff utilizing
coefficients contained in Tables RO-11 and RO-12 of the FCSCM.
3. Two separate design storms have been utilized to address distinct drainage scenarios.
A third design storm has also been computed for comparison purposes. The first
event analyzed is the “Minor,” or “Initial” Storm, which has a 2-year recurrence
interval. The second event considered is the “Major Storm,” which has a 100-year
recurrence interval. The third storm computed, for comparison purposes only, is the
10-year event.
4. No other assumptions or calculation methods have been used with this development
that are not referenced by current City of Fort Collins criteria.
E. Hydraulic Criteria
1. As previously noted, the subject property maintains historic drainage patterns.
2. All drainage facilities proposed with the project are designed in accordance with
criteria outlined in the FCSCM and/or the Urban Drainage and Flood Control District
(UDFCD) Urban Storm Drainage Criteria Manual.
3. As stated above, the subject property is not located in a City or FEMA designated
floodplain. The proposed project does not propose to modify any natural
drainageways.
F. Modifications of Criteria
1. The proposed development is not requesting any modifications to criteria at this time.
IV. DRAINAGE FACILITY DESIGN
A. General Concept
1. The main objectives of the project drainage design are to maintain existing drainage
patterns, and to ensure no adverse impacts to any adjacent properties.
2. Drainage patterns anticipated for drainage basins shown in the Drainage Exhibit are
described below. Drainage basins have been defined for preliminary design purposes
and are subject to change at Final design; however, general drainage patterns and
concepts are not expected to be significantly altered.
Basin A
Basin A will generally follow historic drainage patterns. Basin A will drain via overland
flow, roof drains, and proposed storm sewer into the existing storm drain system
Downtown Fort Collins Hotel Parking Garage Alternative
Preliminary Drainage Report 7
within Oak Street. A proposed rain garden located within Basin A will discharge into
the proposed building’s storm drain system.
Basin OSA
Basin OSA will follow historic drainage patterns via overland flow into the existing
storm drain system within Oak Street.
Basins B & OSB
Minimal development will occur with Basins B and OSB. Basins B and OSB will
generally drain via overland flow into the existing storm drain system within
Remington Street. The emergency overflow for the rain garden will occur through
Basins B & OSB.
A full-size copy of the Drainage Exhibit can be found in the Map Pocket at the end of
this report. Runoff computations for these basins based on the Rational Method is
provided in Appendix A.
B. Specific Details
1. Low Impact Development (LID) measures will be incorporated into the site
design which will consist of a rain garden in the northeast corner of the site.
Rain gardens will be designed with drain systems that will outfall to the Oak
Street storm drain. The rain garden will be designed to treat 75% of the new
impervious area for the site. Details of this design will be provided at Final
design.
2. The following table summarizes proposed LID features and overall percentage
of the basin being treated by the proposed LID features
75% On-Site Treatment by LID Requirements
New Impervious Area 3,328 ft2 0.076 Ac.
Traditional Pavement Area 59 ft2 0.001 Ac.
Other Impervious Surfaces (Roofs, Concrete Walks, etc.) 3,269 ft2 0.075 Ac.
Required Minimum Impervious Area to be Treated 2,496 ft2 0.057 Ac.
Required Minimum Volume to be Treated 101 ft3 3.74 yd3
Design Volume of Rain Garden 101 ft3 3.74 yd3
Percent of Treatment of New Impervious Area 75%
3. Final design details, construction documentation, and Standard Operating
Procedures (SOP) Manual shall be provided to the City of Fort Collins for
review prior to Final Development Plan approval. A final copy of the approved
SOP manual shall be provided to City and must be maintained on-site by the
entity responsible for the facility maintenance. Annual reports must also be
prepared and submitted to the City discussing the results of the maintenance
program (i.e. inspection dates, inspection frequency, volume loss due to
sedimentation, corrective actions taken, etc.).
4. Proper maintenance of the drainage facilities designed with the proposed
development is a critical component of their ongoing performance and
effectiveness.
Downtown Fort Collins Hotel Parking Garage Alternative
Preliminary Drainage Report 8
V. CONCLUSIONS
A. Compliance with Standards
1. The drainage design proposed with the proposed project complies with the City of Fort
Collins’ Stormwater Criteria Manual.
2. The drainage design proposed with this project complies with requirements for the Old
Town Basin.
3. The drainage plan and stormwater management measures proposed with the
proposed development are compliant with all applicable State and Federal regulations
governing stormwater discharge.
B. Drainage Concept
1. The drainage design proposed with this project will effectively limit any potential
damage associated with its stormwater runoff by compliance with requirements set
forth in current City master plans.
2. The drainage concept for the proposed development is consistent with requirements
for the Old Town Basin and the Downtown River District Final Design Report.
References
1. Fort Collins Stormwater Criteria Manual, City of Fort Collins, Colorado, as adopted by Ordinance No.
174, 2011, and referenced in Section 26-500 (c) of the City of Fort Collins Municipal Code.
2. Larimer County Urban Area Street Standards, Adopted January 2, 2001, Repealed and
Reenacted, Effective October 1, 2002, Repealed and Reenacted, Effective April 1, 2007.
3. Soils Resource Report for Larimer County Area, Colorado, Natural Resources Conservation
Service, United States Department of Agriculture.
4. Old Town Master Drainage Plan, Baseline Hydraulics, Volume II, Anderson Consulting,
July 15, 2003.
5. Urban Storm Drainage Criteria Manual, Volumes 1-3, Urban Drainage and Flood Control
District, Wright-McLaughlin Engineers, Denver, Colorado, Revised August 2013.
Downtown Fort Collins Hotel Parking Garage Alternative
Preliminary Erosion Control Report
APPENDIX A
HYDROLOGIC COMPUTATIONS
Percent
Impervious
Developed
40%
0% Date:
2%
100%
Basin ID
Basin Area
(sq. ft.)
Basin Area
(ac)
Gravel Area
(ac.)
Area of
Lawns (ac.)
Pervious
Area (ac.)
Area of
Impervious
(ac.)
Composite
Percent
Impervious
2-year
Runoff
Coefficient
2
5-year
Runoff
Coefficient
2
10-year
Runoff
Coefficient
2
100-year
Runoff
Coefficient
2
A 6,995 0.16 0.09 0.00 0.00 0.07 67.94% 0.43 0.47 0.51 0.60
OS-A 5,491 0.13 0.00 0.00 0.00 0.12 99.07% 0.87 0.88 0.90 0.94
OS-B 8,929 0.20 0.00 0.00 0.00 0.20 98.54% 0.85 0.86 0.88 0.93
Notes:
2) Runoff Coefficients are taken from the Urban Drainage and Flood Control District, Chapter 5, Table RO-5.
Calculations By: F. Wegert
EXISTING % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS
Project: Poudre Garage
Gravel
Lawns
Pervious Area (Historical)
Impervious Area
1) Percent impervious are taken from the Urban Drainage and Flood Control District, Chapter 5, Table RO-3.
CHARACTER OF SURFACE
1
:
March 2, 2016
3/1/2016 8:56 AM D:\Projects\998-002\Drainage\Hydrology\998-002_Pre-Developed_UDFCD_RM.xlsx\Basin Runoff Coefficient
Overland Flow, Time of Concentration:
Project:
Calculations By:
Date:
Gutter/Swale Flow, Time of Concentration:
T
t
= L / 60V
T
c
= T
i
+ T
t
(Equation RO-2)
Velocity (Gutter Flow), V = 20·S
½
Velocity (Swale Flow), V = 15·S
½
Is Length
>500' ?
C
5
Length,
L
(ft)
Slope,
S
(%)
T
i
Length,
L
(ft)
Slope,
S
(%)
Velocity,
V
(ft/s)
T
t
(min)
Length,
L
(ft)
Slope,
S
(%)
Velocity,
V
(ft/s)
T
t
(min)
Urban Tc
Check
T
c
(min)
Rational Method Equation: Project: Poudre Garage
Calculations By: F. Wegert
Date: March 2, 2016
Rainfall Intensity:
A A 0.16 10.9 0.43 0.51 0.60 2.17 3.71 7.57 0.15 0.30 0.73
OS-A OS-A 0.13 5.0 0.87 0.90 0.94 2.85 4.87 9.95 0.31 0.55 1.18
OS-B OS-B 0.20
5.0 0.85 0.88 0.93 2.85 4.87 9.95 0.50 0.88 1.89
Notes
EXISTING RUNOFF COMPUTATIONS FOR INDIVIDUAL BASINS
Rainfall Intensity taken from the Larimer County Stormwater Design Standards, Adopted June 20, 2005, Figure RA-3.
Design
Point
Basin(s)
Area, A
(acres)
T
c
(min)
C
2
C
10
C
100
Intensity,
i
2
(in/hr)
Intensity,
i
10
(in/hr)
Intensity,
i
100
(in/hr)
Flow,
Q
2
(cfs)
Flow,
Q
10
(cfs)
Flow,
Q
100
(cfs)
Q C f C i A
3/1/2016 8:57 AM D:\Projects\998-002\Drainage\Hydrology\998-002_Pre-Developed_UDFCD_RM.xlsx\Runoff
Percent
Impervious
Developed
40%
0% Date:
2%
100%
Basin ID
Basin Area
(sq. ft.)
Basin Area
(ac)
Gravel Area
(ac.)
Area of
Lawns (ac.)
Pervious
Area (ac.)
Area of
Impervious
(ac.)
Composite
Percent
Impervious
2-year
Runoff
Coefficient
2
5-year
Runoff
Coefficient
2
10-year
Runoff
Coefficient
2
100-year
Runoff
Coefficient
2
A 6,618 0.15 0.00 0.01 0.00 0.14 95.42% 0.79 0.81 0.83 0.88
B 377 0.01 0.00 0.00 0.00 0.01 100.00% 0.89 0.90 0.92 0.96
OS-A 5,491 0.13 0.00 0.01 0.00 0.12 92.13% 0.74 0.76 0.78 0.84
OS-B 8,929 0.20 0.00 0.00 0.00 0.20 98.54% 0.85 0.86 0.88 0.93
Notes:
2) Runoff Coefficients are taken from the Urban Drainage and Flood Control District, Chapter 5, Table RO-5.
Calculations By: F. Wegert
DEVELOPED BASIN % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS
Project: Poudre Garage
Gravel
Lawns
Pervious Area (Historical)
Impervious Area
1) Percent impervious are taken from the Urban Drainage and Flood Control District, Chapter 5, Table RO-3.
CHARACTER OF SURFACE
1
:
March 2, 2016
3/1/2016 8:58 AM D:\Projects\998-002\Drainage\Hydrology\998-002_Post-Developed_UDFCD_RM.xlsx\Basin Runoff Coefficient
Overland Flow, Time of Concentration:
Project:
Calculations By:
Date:
Gutter/Swale Flow, Time of Concentration:
T
t
= L / 60V
T
c
= T
i
+ T
t
(Equation RO-2)
Velocity (Gutter Flow), V = 20·S
½
Velocity (Swale Flow), V = 15·S
½
Is Length
>500' ?
C
5
Length,
L
(ft)
Slope,
S
(%)
T
i
Length,
L
(ft)
Slope,
S
(%)
Velocity,
V
(ft/s)
T
t
(min)
Length,
L
(ft)
Slope,
S
(%)
Velocity,
V
(ft/s)
T
t
(min)
Urban Tc
Check
T
c
(min)
Rational Method Equation: Project: Poudre Garage
Calculations By: F. Wegert
Date: March 2, 2016
Rainfall Intensity:
A A 0.15 10.8 0.79 0.83 0.88 2.17 3.71 7.57 0.26 0.47 1.01
B B 0.01 5.0 0.89 0.92 0.96 2.85 4.87 9.95 0.02 0.04 0.08
OS-A OS-A 0.13 5.0 0.74 0.78 0.84 2.85 4.87 9.95 0.27 0.48 1.05
OS-B OS-B 0.20
5.0 0.85 0.88 0.93 2.85 4.87 9.95 0.50 0.88 1.89
Notes
DEVELOPED RUNOFF COMPUTATIONS FOR INDIVIDUAL BASINS
Rainfall Intensity taken from the Larimer County Stormwater Design Standards, Adopted June 20, 2005, Figure RA-3.
Design
Point
Basin(s)
Area, A
(acres)
T
c
(min)
C
2
C
10
C
100
Intensity,
i
2
(in/hr)
Intensity,
i
10
(in/hr)
Intensity,
i
100
(in/hr)
Flow,
Q
2
(cfs)
Flow,
Q
10
(cfs)
Flow,
Q
100
(cfs)
Q C f C i A
3/1/2016 8:59 AM D:\Projects\998-002\Drainage\Hydrology\998-002_Post-Developed_UDFCD_RM.xlsx\Runoff
Project Number: Project:
Project Location:
Calculations By: Date:
Percent
Impervious
● roof & concrete 3,257 ft
2
100% 3,257 ft
2
● gravel
1
3,738 ft
2
40% 1,495 ft
2
4,752 ft
2
● new roof & concrete
1
3,328 ft
2
100% 3,328 ft
2
3,328 ft
2
Note:
1) Gravel parking lot to be replaced with proposed building, concrete, and rain garden.
Total New Impervious Area
Existing
Proposed
Impervious Area for the Site
998-002 Poudre Garage
Fort Collins, Colorado
F. Wegert 3/2/2016
Area Weighted Area
Total Existing Impervious Area
3/1/2016 8:57 AM D:\Projects\998-002\Drainage\Hydrology\998-002_Pre-Developed_UDFCD_RM.xlsx\New Impv Area
Downtown Fort Collins Hotel Parking Garage Alternative
Preliminary Erosion Control Report
APPENDIX B
WATER WAWALID DESIGN COMPUTATIONS
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1. Basin Storage Volume
A) Effective Imperviousness of Tributary Area, Ia Ia = 100.0 %
(100% if all paved and roofed areas upstream of rain garden)
B) Tributary Area's Imperviousness Ratio (i = Ia/100) i = 1.000
C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.40 watershed inches
(WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i)
D) Contributing Watershed Area (including rain garden area) Area = 2,496 sq ft
E) Water Quality Capture Volume (WQCV) Design Volume VWQCV = 83 cu ft
Vol = (WQCV / 12) * Area
F) For Watersheds Outside of the Denver Region, Depth of d6 = in
Average Runoff Producing Storm
G) For Watersheds Outside of the Denver Region, VWQCV OTHER = 0.0 cu ft
Water Quality Capture Volume (WQCV) Design Volume
H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER = cu ft
(Only if a different WQCV Design Volume is desired)
2. Basin Geometry
A) WQCV Depth (12-inch maximum) DWQCV = 4.0 in
B) Rain Garden Side Slopes (Z = 4 min., horiz. dist per unit vertical) Z = 0.00 ft / ft
(Use "0" if rain garden has vertical walls)
C) Mimimum Flat Surface Area AMin = 55 sq ft
D) Actual Flat Surface Area AActual = 303 sq ft
E) Area at Design Depth (Top Surface Area) ATop = 303 sq ft
F) Rain Garden Total Volume VT= 101 cu ft
(VT= ((ATop + AActual) / 2) * Depth)
3. Growing Media
4. Underdrain System
A) Are underdrains provided?
B) Underdrain system orifice diameter for 12 hour drain time
i) Distance From Lowest Elevation of the Storage y = 1.7 ft
Volume to the Center of the Orifice
ii) Volume to Drain in 12 Hours Vol12 = 83 cu ft
iii) Orifice Diameter, 3/8" Minimum DO = 0.22 in MINIMUM DIAMETER = 3/8"
Design Procedure Form: Rain Garden (RG)
Frederick Wegert
Northern Engineering
March 2, 2016
998-002
Rain Garden Onsite
Choose One
Choose One
18" Rain Garden Growing Media
Other (Explain):
YES
NO
UD-BMP_v3.02_Rngdn 75% Treatment.xls, RG 3/1/2016, 9:00 AM
Sheet 2 of 2
Designer:
Company:
Date:
Project:
Location:
5. Impermeable Geomembrane Liner and Geotextile Separator Fabric
A) Is an impermeable liner provided due to proximity
of structures or groundwater contamination?
6. Inlet / Outlet Control
A) Inlet Control
7. Vegetation
8. Irrigation
A) Will the rain garden be irrigated?
Notes:
Design Procedure Form: Rain Garden (RG)
Frederick Wegert
Northern Engineering
March 2, 2016
998-002
Rain Garden Onsite
Choose One
Choose One
Choose One
Sheet Flow- No Energy Dissipation Required
Concentrated Flow- Energy Dissipation Provided
Plantings
Seed (Plan for frequent weed control)
Sand Grown or Other High Infiltration Sod
Choose One
YES
NO
YES
NO
UD-BMP_v3.02_Rngdn 75% Treatment.xls, RG 3/1/2016, 9:00 AM
Downtown Fort Collins Hotel Parking Garage Alternative
Preliminary Erosion Control Report
MAP POCKET
DRAINAGE EXHIBITS
S
C
S
H
Y
D
D
D
W
D
C
S
G
ELEC
VAULT
RD RD
UD UD UD UD UD
EXISTING DOOR
THRESHOLD
ELEV. = 4982.52
EXISTING DOOR
THRESHOLD
ELEV. = 4982.44
EXISTING DOOR
THRESHOLD
ELEV. = 4983.99
EXISTING DOOR
THRESHOLD
ELEV. = 4984.04
EXISTING DOOR
THRESHOLD
ELEV. = 4982.56
EXISTING DOOR
THRESHOLD
ELEV. = 4982.46
EXISTING DOOR
THRESHOLD
ELEV. = 4982.42
EXISTING TREE WELL (TYP.)
PRESERVE & PROTECT
EXISTING TREE
PRESERVE & PROTECT
EX. RAMP WITH HANDRAIL
REMMINGTON STREET
(100' ROW)
20' WIDE ALLEY
PRESERVE & PROTECT
EXISTING TREE
PRESERVE & PROTECT
EXISTING TREE
EXISTING 1-STORY
BRICK BUILDING
EXISTING 1-STORY
BRICK BUILDING
EXISTING 2-STORY
BRICK BUILDING
PRESERVE & PROTECT EXISTING
UNDERGROUND ELECTRIC VAULT
PRESERVE & PROTECT
EXISTING TREE
OS-A
0.13 AC.
A
0.15 AC.
OS-B
0.20 AC.
PRESERVE & PROTECT
EXISTING TREES
OAK STREET
(100' ROW)
B
0.01 AC.
PROPOSED BUILDING
FF = 4982.50
OSA
OSB
A
(M) N00°18'49"E 99.99'
(R) NORTH 100'
(M) S00°20'34"W 99.97'
(R) SOUTH 100'
(M) N89°42'10"W 69.94'
(R) WEST 70'
(M) S89°41'11"E 69.99'
(R) EAST 70'
No. Revisions:
By: Date:
REVIEWED BY:
R. Provencio
DESIGNED BY:
DRAWN BY:
SCALE:
DATE:
3/2/16
PROJECT:
998-002
Sheet
Of 9 Sheets
POUDRE GARAGE
These drawings are
instruments of service
provided by Northern
Engineering Services, Inc.
and are not to be used for
any type of construction
unless signed and sealed by
a Professional Engineer in
the employ of Northern
Engineering Services, Inc.
NOT FOR CONSTRUCTION
REVIEW SET
3/2/16
200 South College Avenue, Suite 010
Fort Collins, Colorado 80524
E N G I N E E R I N G
N O R T H E RN
PHONE: 970.221.4158 FAX: 970.221.4159
www.northernengineering.com
C500
DRAINAGE PLAN F. Wegert
F. Wegert
1" = 10'
City UTILITY of Fort PLAN Collins, APPROVAL Colorado
Date
Date
Date
Date
Date
Date
APPROVED:
City Engineer
Traffic Engineer
Parks & Recreation
Stormwater Utility
Water & Wastewater Utility
CHECKED BY:
CHECKED BY:
CHECKED BY:
CHECKED BY:
CHECKED BY:
CALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOU
DIG, GRADE, OR EXCAVATE FOR THE MARKING OF
UNDERGROUND MEMBER UTILITIES.
CALL UTILITY NOTIFICATION CENTER OF
COLORADO
Know what'sbelow.
Call before you dig.
R
( IN FEET )
10 0 10 20 30
1 INCH = 10 FEET
A
DRAINAGE BASIN LABEL
BASIN
DESIGNATION
BASIN
AREA (AC)
DRAINAGE BASIN BOUNDARY
B2
1.45 ac
80
79
5015
5013
EXISTING MAJOR CONTOUR
EXISTING MINOR CONTOUR
PROPOSED CONTOURS
DESIGN POINT
FLOW ARROWS
1.EXISTING UNDERGROUND AND OVERHEAD PUBLIC AND PRIVATE UTILITIES AS SHOWN ARE
INDICATED ACCORDING TO THE BEST INFORMATION AVAILABLE TO THE ENGINEER. THE
ENGINEER DOES NOT GUARANTEE THE ACCURACY OF SUCH INFORMATION. EXISTING UTILITY
MAINS AND SERVICES MAY NOT BE STRAIGHT LINES OR AS INDICATED ON THESE DRAWINGS.
THE CONTRACTOR SHALL BE RESPONSIBLE TO CALL ALL UTILITY COMPANIES (PUBLIC AND
PRIVATE) PRIOR TO ANY CONSTRUCTION TO VERIFY EXACT UTILITY LOCATIONS.
2.REFER TO THE "PRELIMINARY DRAINAGE REPORT FOR POUDRE GARAGE" BY NORTHERN
ENGINEERING, DATED MARCH 2, 2016 FOR ADDITIONAL INFORMATION.
NOTES:
LEGEND:
EXISTING RIGHT-OF-WAY/PROPERTY LINE
VAULT
ELEC
EXISTING CONCRETE
EXISTING CURB & GUTTER
PROPOSED CONCRETE PAVEMENT
PROPOSED ASPHALT PAVEMENT
PROPOSED VERTICAL CURB & GUTTER
RD
PROPOSED RAIN GARDEN/LID TREATMENT
EXISTING BUILDING
SAWCUT LINE
EXISTING ELECTRIC VAULT
EXISTING FIRE HYDRANT
EXISTING TREES
PROPOSED ROOF DRAIN
PROPOSED BUILDING EXPANSION
CALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOU
DIG, GRADE, OR EXCAVATE FOR THE MARKING OF
UNDERGROUND MEMBER UTILITIES.
CALL UTILITY NOTIFICATION CENTER OF
COLORADO
Know what'sbelow.
Call before you dig.
R
FIELD SURVEY BY:
ORIGINAL FIELD SURVEY
NORTHERN ENGINEERING SERVICES, INC.
PROJECT NUMBER: 998-002
DATE: DECEMBER 2015
PROPOSED STORM SEWER
PROPOSED UNDERDRAIN
UD
A A No 0.81 137 0.18% 11.0 0 0.00% N/A N/A 0 0.00% N/A N/A 10.8 10.8
B B No 0.90 8 6.25% 0.6 60 0.83% 1.82 0.5 0 0.00% N/A N/A 10.4 5.0
OS-A OS-A No 0.76 23 1.65% 2.5 93 0.87% 1.87 0.8 0 0.00% N/A N/A 10.6 5.0
OS-B OS-B No 0.86 23 1.65% 1.8 159 0.78% 1.77 1.5 0 0.00% N/A N/A 11.0 5.0
DEVELOPED DIRECT TIME OF CONCENTRATION FOR INDIVIDUAL BASINS
Gutter Flow 1 Swale Flow
Design
Point
Basin
Overland Flow Time of Concentration
Poudre Garage
F. Wegert
March 2, 2016
(Equation RO-4)
3
1
0 . 395 1 . 1 5
S
C L
Ti
3/1/2016 8:58 AM D:\Projects\998-002\Drainage\Hydrology\998-002_Post-Developed_UDFCD_RM.xlsx\Tc
A A No 0.47 170 0.32% 22.2 0 0.00% N/A N/A 0 0.00% N/A N/A 10.9 10.9
OS-A OS-A No 0.88 23 1.65% 1.6 93 0.87% 1.87 0.8 0 0.00% N/A N/A 10.6 5.0
OS-B OS-B No 0.86 23 1.65% 1.8 159 0.78% 1.77 1.5 0 0.00% N/A N/A 11.0 5.0
EXISTING DIRECT TIME OF CONCENTRATION FOR INDIVIDUAL BASINS
Gutter Flow 1 Swale Flow
Design
Point
Basin
Overland Flow Time of Concentration
Poudre Garage
F. Wegert
March 2, 2016
(Equation RO-4)
3
1
0 . 395 1 . 1 5
S
C L
Ti
3/1/2016 8:57 AM D:\Projects\998-002\Drainage\Hydrology\998-002_Pre-Developed_UDFCD_RM.xlsx\Tc