HomeMy WebLinkAboutGROWTH LEASING COLORADO - BDR190008 - SUBMITTAL DOCUMENTS - ROUND 2 - DRAINAGE REPORTFINAL DRAINAGE AND
EROSION CONTROL REPORT
April 2, 2019
Growth Leasing Colorado
Fort Collins, Colorado
Prepared for:
Growth Leasing LLC
3019 Duportail Street, #177
Richland, WA 99352
(505) 570-7745
Prepared by:
301 N. Howes Street, Suite 100
Fort Collins, Colorado 80521
Phone: 970.221.4158
www.northernengineering.com
Project Number: 1585-001
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.
301 N. Howes Street, Suite 100, Fort Collins, CO 80521 970.221.4158 www.northernengineering.com
RE: Final Drainage and Erosion Control Report for
Growth Leasing Colorado
Dear Staff:
Northern Engineering is pleased to submit this Final Drainage and Erosion Control Report for your
review. This report accompanies Basic Development Review submittal for the proposed Growth
Leasing Colorado development.
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.
Mason Ruebel, EI Danny Weber, PE
Project Engineer Project Engineer
Growth Leasing Colorado
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 ................................................................................... 5
A. Regulations........................................................................................................................................ 5
B. Four Step Process .............................................................................................................................. 5
C. Development Criteria Reference and Constraints ............................................................................ 6
D. Hydrological Criteria ......................................................................................................................... 6
E. Hydraulic Criteria .............................................................................................................................. 6
F. Floodplain Regulations Compliance .................................................................................................. 7
G. Modifications of Criteria ................................................................................................................... 7
IV. DRAINAGE FACILITY DESIGN .................................................................................... 7
A. General Concept ............................................................................................................................... 7
B. Water Quality Treatment/Low Impact Development ....................................................................... 8
C. Specific Details .................................................................................................................................. 8
V. CONCLUSIONS ........................................................................................................ 9
A. Compliance with Standards .............................................................................................................. 9
B. Drainage Concept .............................................................................................................................. 9
References ....................................................................................................................... 10
APPENDICES:
APPENDIX A – Hydrologic Computations
APPENDIX B – Hydraulic Computations
B.1 – Detention Ponds
B.2 – Storm Sewers
B.3 – Inlets & Weirs
APPENDIX C – Erosion Control Report
APPENDIX D – LID Exhibit
APPENDIX E – References
Growth Leasing Colorado
Preliminary Drainage Report
LIST OF TABLES AND FIGURES:
Figure 1 – Aerial Photograph ................................................................................................ 2
Figure 2 – Proposed Site Plan ............................................................................................... 3
Figure 3 – Existing Floodplains ............................................................................................. 4
MAP POCKET:
DR1 - Drainage Exhibit
Growth Leasing Colorado
Final Drainage Report 1
I. GENERAL LOCATION AND DESCRIPTION
A. Location
1. Vicinity Map
2. Replat of Lot 17, Block 3, Replat (NO.1) of Evergreen Park. Located in the northwest
quarter of Section 1, Township 7 North, Range 69 West of the 6th Prime Meridian,
City of Fort Collins, County of Larimer, State of Colorado.
3. Bounded to the north by an undeveloped lot and transmission lines, to the west by an
existing alley, to the south by an industrial lot, and to the east by public right of way
for Red Cedar Circle.
4. No significant offsite flows are directed into the site. The majority of off-site flows are
prevented from entering the site by existing topography.
5. This lot was originally included in the Master Storm Drainage and Detention Plan for
Evergreen Park, prepared by Cornell Consulting Company. The Drainage Plan for the
area has been revised per the North East College Corridor Outfall (NECCO) project
commissioned by The City of Fort Collins and designed by Ayres Associates.
6. The NECCO project overrides the previous drainage plan for the Evergreen Park
Subdivision.
7. This site has also been included in the Final Strom Drainage Report for Evergreen Park
Lots17,18 and 19.
Growth Leasing Colorado
Final Drainage Report 2
B. Description of Property
1. The site is approximately 1.095 acres of Industrial zoning.
Figure 1 – Aerial Photograph
2. The existing site is comprised of undeveloped land with natural grasses and vegetation.
The northern boundary of the site contains overhead electric lines.
3. The site is generally very flat except along the eastern boundary. The site gently slopes
to the south with a high point through the middle of the site.
4. A Web Soil Survey from the Natural Resources Conservation Service lists the soils for the
area as Hydrologic Soil Group C, which has a low infiltration rate.
5. The proposed project site plan is composed of one commercial building, asphalt
parking/drives, and a concrete equipment area. This site will employ the use of a rain
garden as the main source of LID treatment.
Growth Leasing Colorado
Final Drainage Report 3
Figure 2– Proposed Site Plan
6. There is an abandoned concrete irrigation channel that will be removed with
construction.
7. The project site is within the Evergreen Park Subdivision Drainage Plan and the
NECCO drainage basin. The proposed project is not requesting a change in the land
use.
C. Floodplain
1. The subject property is not located in a FEMA or City regulatory floodplain.
Growth Leasing Colorado
Final Drainage Report 4
Figure 3 – Existing Floodplains
II. DRAINAGE BASINS AND SUB-BASINS
A. Major Basin Description
1. The Growth Leasing project is located within the Dry Creek Master Drainage Basin.
B. Sub-Basin Description
1. The existing site is very flat except near the east property line. Flows from the southern
half of the site gently slopes towards an existing concrete pan in the property to the
south. From there, flows are conveyed to the NECCO Regional Pond through the
existing storm infrastructure. Minor flows to the west generally drain to the adjacent
alley. These flows are conveyed along the alley to Conifer Street and to existing
downstream inlets. Minor Flows to the east generally drain to Red Cedar Circle. From
there, the flows are conveyed along the street curb and gutter to Conifer Street and to
existing downstream inlets.
2. The proposed plan will generally detain developed flows and release at a historical
flow rate to an existing storm drain stub on the southeast corner of the site. The
existing storm drain ultimately outfalls into the NECCO Regional Water Quality Pond.
Growth Leasing Colorado
Final Drainage Report 5
III. DRAINAGE DESIGN CRITERIA
A. Regulations
There are no additional provisions outside of the FCSCM proposed with the Growth
Leasing Colorado Project.
B. Four Step Process
The overall stormwater management strategy employed with the Growth Leasing Colorado
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
Specific 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:
Routing flows, to the extent feasible, through rain gardens to provide additional
infiltration.
Providing on-site detention to increase time of concentration, promote infiltration and
reduce loads on existing storm infrastructure.
Providing vegetated open areas along the south, east, and west portions of the site to
reduce the overall impervious area and to minimize directly connected impervious
areas (MDCIA).
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, this
development will still generate stormwater runoff that will require additional BMPs and
water quality. The LID strategies listed above will provide the on-site water quality
treatment required for this project. Additional water quality for this site is provided by the
NECCO drainage project within the downstream extended detention ponds.
Step 3 – Stabilize Drainageways
There are no major drainageways within the subject property. This property discharges to
existing storm sewers.
Step 4 – Implement Site Specific and Other Source Control BMPs.
The proposed project will improve upon site specific source controls compared to historic
conditions:
Localized trash enclosure within the development will allow for the disposal of solid
waste.
Water Quality measures to protect and prolong the design life of the BMPs delineated
in Step 1.
Standard Operating Procedures (SOPs) for BMP maintenance of Detention ponds and
associated drainage infrastructure to remove sediment accumulation regularly.
Growth Leasing Colorado
Final Drainage Report 6
C. Development Criteria Reference and Constraints
1. The proposed site is a part of the NECCO Drainage Basin. This project requires the
site to discharge runoff from the 100-yr storm event at the historic 2-year release rate,
which is 0.2-cfs per acre. Water quality capture volume is provided regionally by the
NECCO extended detention ponds downstream.
2. This site is subject to the LID requirements per the City of Fort Collins. Please see the
LID Exhibit located in the Appendix for calculations concerning LID treatment. The
site must either have the following:
75% of total new impervious areas must be treated through an LID (Low Impact
Development) treatment BMP, or
50% of total new impervious areas must be treated through an LID (Low Impact
Development) treatment BMP and 25% of new pavement shall be pervious.
3. Per the Final Strom Drainage Report for Evergreen Park lots 17,18 and 19, the
existing storm is capable of accepting 0.42-cfs as a release from this site. We are
discharging at 0.22-cfs.
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 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. The FAA Modified method was utilized for detention storage calculations and
maximum release from the site during a 100-yr event.
4. Three separate design storms have been utilized to address distinct drainage
scenarios. 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.
5. 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 site is generally very flat except along the eastern boundary.
The site gently slopes to the south with a high point through the middle of the site.
2. All drainage facilities proposed with the Growth Leasing Colorado project are designed
in accordance with criteria outlined in the FCSCM and/or the Urban Drainage and
Flood Control District’s (UDFCD) Urban Storm Drainage Criteria Manual.
3. As stated previously, the subject property is not located within a FEMA regulatory
floodplain.
4. The Growth Leasing Colorado project does not propose to modify any natural
drainageways.
Growth Leasing Colorado
Final Drainage Report 7
F. Floodplain Regulations Compliance
1. As previously mentioned, all structures are located outside of any FEMA 100-year
floodplain, and thus are not subject to any floodplain regulations.
G. Modifications of Criteria
1. This project is requesting a slight decrease in the required 75% total new impervious
area must be treated through LID. We are treating 73% of the total new impervious
area and 100% of the new parking areas.
IV. DRAINAGE FACILITY DESIGN
A. General Concept
1. The main objectives of the Growth Leasing Colorado drainage design are to minimize
the developed 100-yr event discharge from the site and meet LID treatment
requirements.
2. The site has been designed to store runoff above and release to the existing storm
infrastructure located on the southeast corner of the site.
3. A list of tables and figures used within this report can be found in the Table of
Contents at the front of the document. The tables and figures are located within the
sections to which the content best applies.
4. This project requires the site to discharge runoff from the 100-yr storm event at the
historic 2-year release rate. The historic 2-year release rate for the project was
calculated at 0.2-cfs per acre.
5. The Growth Leasing Colorado project is divided the site into five (4) major drainage
basins, designated as Basins 1A, 1B, 1C, and 1D.
Basin 1A
Basin A is a total of 0.46 acres. Basin 1A consists of proposed asphalt drive,
landscaped area, a concrete pad, and rain garden 1. Runoff from Basin A flows via
sheet flow to a concrete pan which outfalls into a proposed rain garden. Basin A is
treated entirely for LID within the proposed rain garden 1 and detained in detention
pond 1.
Basin 1B
Basin 1B is a total of 0.05 acres. Basin 1B consists of a section of the proposed
building. Runoff from Basin B is captured by downspouts and released into rain
garden 1. Basin 1B is also treated entirely for LID within the proposed rain garden 1
and detained in detention pond 1.
Basin 1C
Basin 1C is a total of 0.15 acres. Basin 1C consists of a section of the proposed
building. Runoff from Basin 1C is released from downspouts, directly into Basin 1D
and detention pond 1.
Basin 1D
Basin 1D is a total of 0.42 acres. Basin D consists of a concrete pad, landscape area,
and detention pond 1. Runoff from Basin D sheet flows and is detained in detention
pond 1.
Growth Leasing Colorado
Final Drainage Report 8
Table 2 – Proposed Rational Basin Summary
DESIGN
POINT
BASIN
ID
TOTAL
AREA
(acres)
C2 C10 C100
2-yr
Tc
(min)
10-yr
Tc
(min)
100-
yr Tc
(min)
Q2
(cfs)
Q10
(cfs)
Q100
(cfs)
1A 1A 0.46 0.67 0.67 0.84 8.6 8.6 6.7 0.73 1.25 3.51
1B 1B 0.05 0.95 0.95 1.00 5.0 5.0 5.0 0.14 0.23 0.50
1C 1C 0.15 0.95 0.95 1.00 5.0 5.0 5.0 0.41 0.71 1.52
1D 1D 0.42 0.25 0.25 0.31 17.1 17.1 16.1 0.18 0.32 0.83
6. One detention pond is proposed with the Growth Leasing Colorado project. Detention
Pond 1 is located within Basin 1D.
Detention Pond 1
Detention Pond 1 has a total of 0.22 ac-ft storage available. 0.21 ac-ft of storage is
required with this project. Water quality control volume for detention pond 1 is not
included in the pond volume since water quality is provided downstream in the
NECCO Regional Water Quality Ponds. Emergency Overflow from the pond is directed
over the adjacent sidewalk on the east property line and into Red Cedar Circle.
Release rate from detention pond 1 is proposed at 0.22 cfs.
Table 3 – Detention Pond Summary
Detention Pond Summary
Pond
100-yr
Volume 100-yr
WSEL
Max
Release
Pond
Spill
(ac-ft) (cfs) Elev
1 0.21 4973.4 0.22 4973.5
A full-size copy of the Drainage Exhibit can be found in the Map Pocket at the end of
this report.
B. Water Quality Treatment/Low Impact Development
1. Water Quality is provided for the site downstream with the NECCO Regional Water
Quality Pond. This site is only required to meet LID requirements for water quality
2. Basins 1A and 1B have water quality provided exclusively via Rain Garden 1.
Following UDFCD standards for a 12-hour drain time, a Water Quality Capture
Volume of 392 cu. ft. is required. Stormwater volume exceeding the volume provided
will overflow into detention pond 1.
Growth Leasing Colorado
Final Drainage Report 9
2. An emergency overflow weir for Detention Pond 1 was provided to convey the 100-yr
storm flowrate from the pond safety to Red Cedar Circle in an emergency event.
Weirs were analyzed by Hydraflow Express.
3. Inlets were sized for the 100-yr event utilizing Area Inlet calculations spreadsheets.
V. CONCLUSIONS
A. Compliance with Standards
1. The drainage design proposed with the Growth Leasing Colorado project complies
with the City of Fort Collins’ Stormwater Criteria Manual.
2. The drainage design proposed with the Growth Leasing Colorado complies with the
City of Fort Collins’ Master Drainage Plan for the Dry Creek Drainage Basin.
3. There are no regulatory floodplains associated with the development.
4. The drainage plan and stormwater management measures proposed with the
development are compliant with all applicable State and Federal regulations governing
stormwater discharge.
5. The site is just under the requirements set forth by the City of Fort Collins for Low
Impact Development (LID) by providing 73% total impervious areas as being treated
through LID treatment. The area that is not being treated is basin 1D which is mainly
landscape area and basin 1C which is a section of the proposed building rooftop. This
area will have little impact on the water quality. Please see LID Exhibit located in the
Appendix.
B. Drainage Concept
1. The drainage design proposed with this project will effectively comply with previous
studies and will limit any potential damage or erosion associated with its stormwater
runoff. All existing downstream drainage facilities are expected to not be impacted
negatively by this development
2. The drainage design is anticipated to be very conservative. We have omitted any
runoff reduction that will manifest due to infiltration within the Rain Garden. This is
currently unable to be calculated with available soils data.
Growth Leasing Colorado
Final Drainage Report 10
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. Master Storm Drainage and Detention Plan for Evergreen Park, Cornell Consulting Company.
3. Larimer County Urban Area Street Standards, Adopted January 2, 2001, Repealed and
Reenacted, Effective October 1, 2002, Repealed and Reenacted, Effective April 1, 2007.
4. Soils Resource Report for Larimer County Area, Colorado, Natural Resources Conservation
Service, United States Department of Agriculture.
5. Urban Storm Drainage Criteria Manual, Volumes 1-3, Urban Drainage and Flood Control
District, Wright-McLaughlin Engineers, Denver, Colorado, Revised April 2008.
6. Final Storm Drainage Report for Evergreen Park Lots 17, 18 and 19, Stewart & Associates,
Fort Collins, Colorado, May 1995.
APPENDIX A
HYDROLOGIC COMPUTATIONS
Growth Leasing Colorado
CHARACTER OF SURFACE:
Runoff
Coefficient
Percentage
Impervious Project: Growth Leasing
Streets, Parking Lots, Roofs, Alleys, and Drives: Calculations By: D. Weber
Asphalt ……....……………...……….....…...……………….………………………………….0.95 . 100% Date:
Concrete …….......……………….….……….………………..….………………………………… 0.95 100%
Gravel ……….…………………….….…………………………..……………………………….0.50 . 40%
Roofs …….…….………………..……………….…………………………………………….0.. 95 90%
Concrete Pavers…………………………...………………..…………………………………………….0.50 . 40%
Lawns and Landscaping
Sandy Soil ……..……………..……………….…………………………………………….. 0.15 2%
Clayey Soil ….….………….…….…………..………………………………………………. 0.25 2% 2-year Cf
= 1.00 100-year Cf
= 1.25
Basin ID
Basin Area
(s.f.)
Basin Area
(ac)
Area of
Asphalt
(ac)
Area of
Concrete
(ac)
Area of
Roofs
(ac)
Area of
Gravel
(ac)
Area of
Concrete
Pavers
(ac)
Area of
Lawns and
Landscaping
(ac)
2-year
Composite
Runoff
Coefficient
10-year
Composite
Runoff
Coefficient
100-year
Composite
Runoff
Coefficient
Composite
% Imperv.
1A 20,023.51 0.46 0.21 0.07 0.00 0.00 0.00 0.18 0.67 0.67 0.84 61%
1B 2,184.00 0.05 0.00 0.00 0.05 0.00 0.00 0.00 0.95 0.95 1.00 90%
1C 6,637.84 0.15 0.00 0.00 0.15 0.00 0.00 0.00 0.95 0.95 1.00 90%
1D 18,369.49 0.42 0.00 0.00 0.00 0.00 0.00 0.42 0.25 0.25 0.31 2%
Growth Leasing Colorado
Overland Flow, Time of Concentration:
Project: Growth Leasing
Calculations By:
Date:
Gutter/Swale Flow, Time of Concentration:
Tt = L / 60V
Tc = Ti + Tt (Equation RO-2)
Velocity (Gutter Flow), V = 20·S½
Velocity (Swale Flow), V = 15·S½
NOTE: C-value for overland flows over grassy surfaces; C = 0.25
Is Length
>500' ?
C*Cf
(2-yr
Cf=1.00)
C*Cf
(10-yr
Cf=1.00)
C*Cf
(100-yr
Cf=1.25)
Length,
L
(ft)
Slope,
S
(%)
Ti
2-yr
(min)
Ti
10-yr
(min)
Ti
100-yr
(min)
Length,
L
(ft)
Slope,
S
(%)
Velocity,
V
(ft/s)
Tt
(min)
Length,
L
(ft)
Slope,
S
(%)
Velocity,
V
(ft/s)
Tt
(min)
2-yr
Growth Leasing Colorado
Rational Method Equation: Project: Growth Leasing
Calculations By:
Date:
From Section 3.2.1 of the CFCSDDC
Rainfall Intensity:
1A 1A 0.46 8.6 8.6 6.7 0.67 0.67 0.84 2.35 4.02 9.06 0.73 1.25 3.51
1B 1B 0.05 5.0 5.0 5.0 0.95 0.95 1.00 2.85 4.87 9.95 0.14 0.23 0.50
1C 1C 0.15 5.0 5.0 5.0 0.95 0.95 1.00 2.85 4.87 9.95 0.41 0.71 1.52
1D 1D 0.42 17.1 17.1 16.1 0.25 0.25 0.31 1.75 2.99 6.30 0.18 0.32 0.83
Intensity,
i10
(in/hr)
Rainfall Intensity taken from the City of Fort Collins Storm Drainage Design Criteria (CFCSDDC), Figure 3.1
C10
Area, A
(acres)
Intensity,
i2
(in/hr)
100-yr
Tc
(min)
DEVELOPED RUNOFF COMPUTATIONS
C100
Design
Point
Flow,
Q100
(cfs)
Flow,
Q2
(cfs)
10-yr
Tc
(min)
2-yr
Tc
(min)
C2
Flow,
Q10
(cfs)
Intensity,
i100
(in/hr)
Basin(s)
D. Weber
March 13, 2019
Q = C f ( C )( i )( A )
\\BRONCOS\Engineers\Projects\1585-001\Drainage\Hydrology\1585-001_Rational.xlsx\Direct-Runoff
APPENDIX B
HYDRAULIC COMPUTATIONS
B.1 DETENTION PONDS
B.2 STORM SEWERS
B.3 INLET AND WEIR
APPENDIX B.1
DETENTION PONDS
Pond No : 1
1
100-yr
0.70
6.60 min 9195 ft3
1.08 acres 0.21 ac-ft
Max Release Rate = 0.22 cfs
Time (min)
Ft Collins
100-yr
Intensity
(in/hr)
Inflow
Volume
(ft3)
Outflow
Adjustment
Factor
Qav
(cfs)
Outflow Volume
(ft3)
Storage
Volume
(ft3)
5 9.950 2257 1.00 0.22 65 2192
10 7.720 3502 0.83 0.18 108 3394
15 6.520 4436 0.72 0.16 140 4296
20 5.600 5080 0.67 0.14 172 4908
25 4.980 5647 0.63 0.14 205 5443
30 4.520 6151 0.61 0.13 237 5914
35 4.080 6477 0.59 0.13 270 6208
40 3.740 6786 0.58 0.13 302 6484
45 3.460 7063 0.57 0.12 334 6728
50 3.230 7326 0.57 0.12 367 6959
55 3.030 7559 0.56 0.12 399 7160
60 2.860 7784 0.56 0.12 432 7352
65 2.720 8020 0.55 0.12 464 7556
70 2.590 8224 0.55 0.12 496 7727
75 2.480 8437 0.54 0.12 529 7908
80 2.380 8637 0.54 0.12 561 8075
85 2.290 8829 0.54 0.12 594 8236
90 2.210 9022 0.54 0.12 626 8396
95 2.130 9179 0.53 0.12 658 8520
100 2.060 9344 0.53 0.12 691 8653
105 2.000 9526 0.53 0.11 723 8802
110 1.940 9680 0.53 0.11 756 8924
115 1.890 9859 0.53 0.11 788 9071
120 1.840 10015 0.53 0.11 820 9195
*Note: Using the method described in Urban Storm Drainage Criteria Manual Volume 2.
DETENTION POND CALCULATION; MODIFIED FAA METHOD w/ Ft Collins IDF
Input Variables Results
Required Detention Volume
Fort Collins, CO
1585-001
Growth Leasing
Project Number :
Project Name :
A =
Tc =
Project:
Date:
4968.79 0.21 ac-ft
4970.5 0.00 ac-ft
4973.5 4973.44
N/A N/A
Maximum
Elevation
Minimum
Elevation
cu. ft. acre ft cu. ft. acre ft
4970.6 N/A 32.2 0 0.0 0.00 0.0 0.00
4970.8 4970.6 305.3 0.2 33.8 0.00 33.8 0.00
4971.0 4970.8 720.4 0.2 102.6 0.00 136.3 0.00
4971.2 4971.0 1,027.5 0.2 174.8 0.00 311.1 0.01
4971.4 4971.2 1,645.6 0.2 267.3 0.01 578.4 0.01
4971.6 4971.4 2,332.5 0.2 397.8 0.01 976.2 0.02
4971.8 4971.6 2,723.2 0.2 505.6 0.01 1,481.8 0.03
4972.0 4971.8 3,140.2 0.2 586.3 0.01 2,068.1 0.05
4972.2 4972.0 3,585.3 0.2 672.6 0.02 2,740.7 0.06
4972.4 4972.2 4,060.5 0.2 764.6 0.02 3,505.3 0.08
4972.6 4972.4 4,567.5 0.2 862.8 0.02 4,368.1 0.10
4972.8 4972.6 5,107.7 0.2 967.5 0.02 5,335.6 0.12
4973.0 4972.8 5,684.5 0.2 1,079.2 0.02 6,414.8 0.15
4973.2 4973.0 6,301.4 0.2 1,198.6 0.03 7,613.4 0.17
4973.4 4973.2 6,947.0 0.2 1,324.8 0.03 8,938.2 0.21
4973.5 4973.4 7,283.8 0.1 704.4 0.02 9,642.6 0.22
Detention Pond Stage Storage Curve
Water Quality Volume:
Outlet Elevation:
Grate Elevation:
Crest of Pond Elev.:
Water Quality Elev.:
Volume at Grate:
Contour Contour
Surface Area
(ft
2
)
Depth
Incremental Volume Cummalitive Volume
Pond Stage Storage Curve
1585-001
Fort Collins, Colorado
D. Weber
1
Elev at Design Volume:
Growth Leasing Colorado
3/14/2019
Pond Outlet and Volume Data
Design Volume:
Project Number:
Project Location:
Calculations By:
Pond No.:
3/27/2019 1:31 PM
\\BRONCOS\Engineers\Projects\1585-001\Drainage\Detention\
1585-001_Stage-Storage.xlsx\Pond
Project Title Date:
Project Number Calcs By:
Client
Pond Designation
Q = 0.22 cfs
C = 0.65
Q = Release Rate (cfs) Eh = 4973.44 ft
C = Discharge Coefficients (unitless) Ei = 4968.79 ft
Aa = Area Allowed of Opening (ft2) Ec = 4968.87 ft Circular
g = Gravity (32.2 ft/s
2
) Ec = 4969.02 ft Rectangular
Eh
= High Water Surface Elevation (ft)
Ei = Elevation of Outlet Invert (ft) 0.019566929 ft2
Ec = Elevation of Outlet Centroid (ft) 2.817638 in
2
Orifice Size (in.) 1.9 in
Area (in2) 2.82 sq-in
Q (cfs) 0.22 cfs
Orifice Height (in.) 5.64 in
Orifice Width (in.) 0.50 in Above Outlet Stage Dicharge (cfs)
Area (in2) 2.82 sq-in +2' 4970.80 0.14
Q 0.21 cfs +3' 4971.80 0.18
+4' 4972.80 0.20
+4.7' 4973.50 0.22
1
Growth Leasing Colorado March 14, 2019
1585-001 D. Weber
Growth Leasing
Aa =
Circular Orifice
100-Year Orifice
Rectangular Orifice
100-Year Orifice
Stormwater Facility Name:
Facility Location & Jurisdiction:
User (Input) Watershed Characteristics User Defined User Defined User Defined User Defined
Watershed Slope = 0.017 ft/ft Stage [ft] Area [ft^2] Stage [ft] Discharge [cfs]
Watershed Length-to-Width Ratio = 3.70 L:W 0.00 0 0.00 0.00
Watershed Area = 1.08 acres 2.00 305 2.00 0.14
Watershed Imperviousness = 44.0% percent 3.00 2,723 3.00 0.18
Percentage Hydrologic Soil Group A = 0.0% percent 4.00 5,108 4.00 0.20
Percentage Hydrologic Soil Group B = 0.0% percent 4.70 7,284 4.70 0.22
Percentage Hydrologic Soil Groups C/D = 100.0% percent
User Input: Detention Basin Characteristics
WQCV Design Drain Time = 40.00 hours
After completing and printing this worksheet to a pdf, go to:
https://maperture.digitaldataservices.com/gvh/?viewer=cswdif,
create a new stormwater facility, and
attach the pdf of this worksheet to that record.
Routed Hydrograph Results
Design Storm Return Period = WQCV 2 Year 5 Year 10 Year 25 Year 50 Year 100 Year
Two-Hour Rainfall Depth = 0.53 0.98 1.36 1.71 2.31 2.91 3.67 in
Calculated Runoff Volume = 0.017 0.036 0.066 0.094 0.147 0.196 0.264 acre-ft
OPTIONAL Override Runoff Volume = acre-ft
Inflow Hydrograph Volume = 0.016 0.036 0.065 0.093 0.147 0.196 0.264 acre-ft
Time to Drain 97% of Inflow Volume = 2 3 5 7 10 13 16 hours
Time to Drain 99% of Inflow Volume = 2 4 5 7 10 13 17 hours
Maximum Ponding Depth = 1.91 2.57 3.04 3.37 3.88 4.25 4.67 ft
Maximum Ponded Area = 0.007 0.038 0.064 0.083 0.110 0.135 0.165 acres
Maximum Volume Stored = 0.006 0.020 0.044 0.068 0.117 0.162 0.226 acre-ft
Stormwater Detention and Infiltration Design Data Sheet
Growth Leasing Colorado
City of Fort Collins, Fort Collins, CO
Workbook Protected Worksheet Protected
1585-001_State Drain Time.xlsm, Design Data 3/28/2019, 2:14 PM
Doing_Clear_Formatting Yes =
CountA= 1
0 1 2 3
#N/A
#N/A
0 1 2 3
#N/A
#N/A
Check Data Set 1 Check Data Set 1
Stormwater Detention and Infiltration Design Data Sheet
Area
Discharge
0
1
2
3
4
5
6
0.1 1 10
FLOW [cfs]
TIME [hr]
100YR IN
100YR OUT
50YR IN
50YR OUT
25YR IN
25YR OUT
10YR IN
10YR OUT
5YR IN
5YR OUT
2YR IN
2YR OUT
WQCV IN
WQCV OUT
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
0.1 1 10 100
PONDING DEPTH [ft]
DRAIN TIME [hr]
100YR
50YR
25YR
10YR
5YR
2YR
WQCV
1585-001_State Drain Time.xlsm, Design Data 3/28/2019, 2:14 PM
APPENDIX B.2
STORM SEWERS
Culvert Report
Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Thursday, Mar 28 2019
Storm 2
Invert Elev Dn (ft) = 4971.50
Pipe Length (ft) = 26.00
Slope (%) = 1.00
Invert Elev Up (ft) = 4971.76
Rise (in) = 18.0
Shape = Circular
Span (in) = 18.0
No. Barrels = 1
n-Value = 0.012
Culvert Type = Circular Concrete
Culvert Entrance = Groove end projecting (C)
Coeff. K,M,c,Y,k = 0.0045, 2, 0.0317, 0.69, 0.2
Embankment
Top Elevation (ft) = 4973.50
Top Width (ft) = 5.00
Crest Width (ft) = 25.00
Calculations
Qmin (cfs) = 3.50
Qmax (cfs) = 3.50
Tailwater Elev (ft) = Crown
Highlighted
Qtotal (cfs) = 3.50
Qpipe (cfs) = 3.50
Qovertop (cfs) = 0.00
Veloc Dn (ft/s) = 1.98
Veloc Up (ft/s) = 4.23
HGL Dn (ft) = 4973.00
HGL Up (ft) = 4972.47
Hw Elev (ft) = 4972.76
Hw/D (ft) = 0.67
Flow Regime = Inlet Control
APPENDIX B.3
INLETS AND WEIRS
Area Inlet Performance Curve:
Growth Leasing Colorado - Inlet
Governing Equations:
At low flow depths, the inlet will act like a weir governed by the following equation:
* where P = 2(L + W)
* where H corresponds to the depth of water above the flowline
At higher flow depths, the inlet will act like an orifice governed by the following equation:
* where A equals the open area of the inlet grate
* where H corresponds to the depth of water above the centroid of the cross-sectional area (A)
The exact depth at which the inlet ceases to act like a weir, and begins to act like an orifice is unknown.
However, what is known, is that the stage-discharge curves of the weir equation and the orifice equation
will cross at a certain flow depth. The two curves can be found below:
If H > 1.792 (A/P), then the grate operates like an orifice; otherwise it operates like a weir.
Input Parameters:
Type of Grate: Dome
Grate Diameter (in) 24
Flowline Elevation (ft): 4972.50 Depth Needed
Q10 (cfs): 0.00
Q100 (cfs): 4.00 0.63
Depth Interval (ft) 0.1
Open Area of Grate (in
2
): 270.64
Allowable Capacity: 50%
Depth vs. Flow:
Depth Above Inlet (ft)
Elevation
(ft)
Shallow
Weir Flow
(cfs)
Orifice
Flow
(cfs)
Actual
Flow
(cfs)
0.00 4972.50 0.00 0.00 0.00
0.10 4972.60 0.30 1.60 0.30
0.20 4972.70 0.84 2.26 0.84
0.30 4972.80 1.55 2.77 1.55
0.40 4972.90 2.38 3.19 2.38
0.50 4973.00 3.33 3.57 3.33
0.60 4973.10 4.38 3.91 3.91
0.70 4973.20 5.52 4.23 4.23
0.80 4973.30 6.74 4.52 4.52
0.90 4973.40 8.05 4.79 4.79
1.00 4973.50 9.42 5.05 5.05
<-Q100
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00
Weir Report
Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Thursday, Mar 28 2019
Curb Cut
Rectangular Weir
Crest = Sharp
Bottom Length (ft) = 6.00
Total Depth (ft) = 0.50
Calculations
Weir Coeff. Cw = 3.33
Compute by: Known Q
Known Q (cfs) = 3.50
Highlighted
Depth (ft) = 0.31
Q (cfs) = 3.500
Area (sqft) = 1.88
Velocity (ft/s) = 1.86
Top Width (ft) = 6.00
0 1 2 3 4 5 6 7 8
Depth (ft) Curb Cut Depth (ft)
-0.50 -0.50
0.00 0.00
0.50 0.50
1.00 1.00
Length (ft)
Weir W.S.
Weir Report
Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Thursday, Mar 28 2019
Emergency Spillway
Rectangular Weir
Crest = Broad
Bottom Length (ft) = 67.00
Total Depth (ft) = 0.50
Calculations
Weir Coeff. Cw = 2.60
Compute by: Known Q
Known Q (cfs) = 6.36
Highlighted
Depth (ft) = 0.11
Q (cfs) = 6.360
Area (sqft) = 7.37
Velocity (ft/s) = 0.86
Top Width (ft) = 67.00
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80
Depth (ft) Emergency Spillway Depth (ft)
-0.50 -0.50
0.00 0.00
0.50 0.50
1.00 1.00
Length (ft)
Weir W.S.
APPENDIX C
EROSION CONTROL REPORT
Growth Leasing Colorado
Preliminary Erosion Control Report
A comprehensive Erosion and Sediment Control Plan (along with associated details) is included with
the final construction drawings. It should be noted, however, that any such Erosion and Sediment
Control Plan serves only as a general guide to the Contractor. Staging and/or phasing of the BMPs
depicted, and additional or different BMPs from those included may be necessary during
construction, or as required by the authorities having jurisdiction.
It shall be the responsibility of the Contractor to ensure erosion control measures are properly
maintained and followed. The Erosion and Sediment Control Plan is intended to be a living
document, constantly adapting to site conditions and needs. The Contractor shall update the
location of BMPs as they are installed, removed or modified in conjunction with construction
activities. It is imperative to appropriately reflect the current site conditions at all times.
The Erosion and Sediment Control Plan shall address both temporary measures to be implemented
during construction, as well as permanent erosion control protection. Best Management Practices
from the Volume 3, Chapter 7 – Construction BMPs will be utilized. Measures may include, but are
not limited to, silt fencing along the disturbed perimeter, gutter protection in the adjacent roadways
and inlet protection at existing and proposed storm inlets. Vehicle tracking control pads, spill
containment and clean-up procedures, designated concrete washout areas, dumpsters, and job site
restrooms shall also be provided by the Contractor.
Grading and Erosion Control Notes can be found on Sheet CS2 of the Utility Plans. The Utility
Plans at final design will also contain a full-size Erosion Control Plan as well as a separate sheet
dedicated to Erosion Control Details. In addition to this report and the referenced plan sheets, the
Contractor shall be aware of, and adhere to, the applicable requirements outlined in any existing
Development Agreement(s) of record, as well as the Development Agreement, to be recorded prior
to issuance of the Development Construction Permit. Also, the Site Contractor for this project will
be required to secure a Stormwater Construction General Permit from the Colorado Department of
Public Health and Environment (CDPHE), Water Quality Control Division – Stormwater Program,
before commencing any earth disturbing activities. Prior to securing said permit, the Site Contractor
shall develop a comprehensive StormWater Management Plan (SWMP) pursuant to CDPHE
requirements and guidelines. The SWMP will further describe and document the ongoing activities,
inspections, and maintenance of construction BMPs.
APPENDIX D
LID EXHIBIT
UD
VAULT
ELEC
E
VAULT
F.O.
S
C
S
OHU
OHU
OHU OHU
OHU
OHU OHU
OHU
OHU OHU
OHU
OHU
OHU OHU
OHU
OHU
OHU OHU
OHU OHU
OHU OHU
OHU
OHU OHU OHU OHU
OHU
OHU OHU
OHU
OHU
OHU OHU
ST ST
D
S DS
LID BASIN 1
TOTAL AREA: 22,208 SF
TOTAL IMPERVIOUS AREA: 15,008 SF
LID TREATMENT: RAIN GARDEN
LID BASIN 2
TOTAL AREA: 25,007 SF
TOTAL IMPERVIOUS AREA: 5,607 SF
LID TREATMENT: NONE
RAIN GARDEN 1
FIGURE 1
LID TREATMENT CALCULATIONS
FORT COLLINS, CO
GROWTH LEASING COLORADO
ENGINEER ING
N O R T H E RN
03.14.19
\\BRONCOS\ENGINEERS\PROJECTS\1585-001\DWG\DRNG\1585-001_LID.DWG
NORTH
( IN FEET )
0
1 INCH = 30 FEET
30 30 60 90
LID TREATMENT SUMMARY
RAIN GARDEN 1
Total Volume Required (cf) 392
Total Volume Provided (cf) 533
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1. Basin Storage Volume
A) Effective Imperviousness of Tributary Area, Ia Ia = 68.0 %
(100% if all paved and roofed areas upstream of rain garden)
B) Tributary Area's Imperviousness Ratio (i = Ia/100) i = 0.680
C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.21 watershed inches
(WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i)
D) Contributing Watershed Area (including rain garden area) Area = 22,088 sq ft
E) Water Quality Capture Volume (WQCV) Design Volume VWQCV = 392 cu ft
Vol = (WQCV / 12) * Area
F) For Watersheds Outside of the Denver Region, Depth of d6 = in
Average Runoff Producing Storm
G) For Watersheds Outside of the Denver Region, VWQCV OTHER = cu ft
Water Quality Capture Volume (WQCV) Design Volume
H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER = cu ft
(Only if a different WQCV Design Volume is desired)
2. Basin Geometry
A) WQCV Depth (12-inch maximum) DWQCV = 12 in
B) Rain Garden Side Slopes (Z = 4 min., horiz. dist per unit vertical) Z = 4.00 ft / ft
(Use "0" if rain garden has vertical walls)
C) Mimimum Flat Surface Area AMin = 300 sq ft
D) Actual Flat Surface Area AActual = 402 sq ft
E) Area at Design Depth (Top Surface Area) ATop = 664 sq ft
F) Rain Garden Total Volume VT= 533 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 = ft
Volume to the Center of the Orifice
ii) Volume to Drain in 12 Hours Vol12 = N/A cu ft
iii) Orifice Diameter, 3/8" Minimum DO = N/A in
Design Procedure Form: Rain Garden (RG)
D. Weber
Northern Engineering
March 14, 2019
Growth Leasing Colorado
Rain Garden 1
Choose One
Choose One
18" Rain Garden Growing Media
Other (Explain):
YES
NO
1585-001_Rain Garden.xlsm, RG 3/27/2019, 2:40 PM
APPENDIX E
REFERENCES
Hydrologic Soil Group—Larimer County Area, Colorado
(Growth Leasing)
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
3/4/2019
Page 1 of 4
4494780 4494790 4494800 4494810 4494820 4494830 4494840
4494780 4494790 4494800 4494810 4494820 4494830 4494840
493590 493600 493610 493620 493630 493640 493650 493660 493670 493680 493690
493590 493600 493610 493620 493630 493640 493650 493660 493670 493680 493690
40° 36' 15'' N
105° 4' 33'' W
40° 36' 15'' N
105° 4' 28'' W
40° 36' 13'' N
105° 4' 33'' W
40° 36' 13'' N
105° 4' 28'' W
N
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 25 50 100 150
Feet
0 5 10 20 30
Meters
Map Scale: 1:517 if printed on A landscape (11" x 8.5") sheet.
Soil Map may not be valid at this scale.
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Rating Polygons
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Soil Rating Lines
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Soil Rating Points
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Water Features
Streams and Canals
Transportation
Rails
Interstate Highways
US Routes
Major Roads
Local Roads
Background
Aerial Photography
The soil surveys that comprise your AOI were mapped at
1:24,000.
Warning: Soil Map may not be valid at this scale.
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil
line placement. The maps do not show the small areas of
contrasting soils that could have been shown at a more detailed
scale.
Please rely on the bar scale on each map sheet for map
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
Albers equal-area conic projection, should be used if more
accurate calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data as
Hydrologic Soil Group
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
73 Nunn clay loam, 0 to 1
percent slopes
C 1.1 100.0%
Totals for Area of Interest 1.1 100.0%
Description
Hydrologic soil groups are based on estimates of runoff potential. Soils are
assigned to one of four groups according to the rate of water infiltration when the
soils are not protected by vegetation, are thoroughly wet, and receive
precipitation from long-duration storms.
The soils in the United States are assigned to four groups (A, B, C, and D) and
three dual classes (A/D, B/D, and C/D). The groups are defined as follows:
Group A. Soils having a high infiltration rate (low runoff potential) when
thoroughly wet. These consist mainly of deep, well drained to excessively
drained sands or gravelly sands. These soils have a high rate of water
transmission.
Group B. Soils having a moderate infiltration rate when thoroughly wet. These
consist chiefly of moderately deep or deep, moderately well drained or well
drained soils that have moderately fine texture to moderately coarse texture.
These soils have a moderate rate of water transmission.
Group C. Soils having a slow infiltration rate when thoroughly wet. These consist
chiefly of soils having a layer that impedes the downward movement of water or
soils of moderately fine texture or fine texture. These soils have a slow rate of
water transmission.
Group D. Soils having a very slow infiltration rate (high runoff potential) when
thoroughly wet. These consist chiefly of clays that have a high shrink-swell
potential, soils that have a high water table, soils that have a claypan or clay
layer at or near the surface, and soils that are shallow over nearly impervious
material. These soils have a very slow rate of water transmission.
If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is
for drained areas and the second is for undrained areas. Only the soils that in
their natural condition are in group D are assigned to dual classes.
Rating Options
Aggregation Method: Dominant Condition
Component Percent Cutoff: None Specified
Hydrologic Soil Group—Larimer County Area, Colorado Growth Leasing
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
3/4/2019
Page 3 of 4
Tie-break Rule: Higher
Hydrologic Soil Group—Larimer County Area, Colorado Growth Leasing
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
3/4/2019
Page 4 of 4
#*
#*
#*
#*
#*
#*
S COLLEGE AVE
E MULBERRY ST
E VINE DR
MOUNTAIN VISTA DR
GIDDINGS RD
RICHARDS LAKE RD
TERRY LAKE RD
¦¨§25
LEMAY AVE
Terry
Lake
PLoonngd
LindLeankmeeier
Lari
m
er
a
nd Weld
C
anal
L
ake
Ca
n
a
l
Cac
h
e
L
a
Po
u
dre
R
e
s
.
I
n
l
e
t
Coy
D
itc
h
Ca
c
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e
La
P
o
MAP POCKET
DR1 – OVERALL DRAINAGE EXHIBIT
DS DS
VAULT
ELEC
E
VAULT
F.O.
S
C
S
OHU
OHU
OHU OHU
OHU
OHU OHU
OHU
OHU
OHU
OHU OHU
OHU
OHU OHU
OHU
OHU OHU
OHU OHU
OHU
OHU
OHU OHU
OHU
OHU OHU OHU
OHU
OHU OHU OHU
OHU
OHU OHU OHU
OHU
OHU
OHU
OHU OHU OHU
OHU
OHU OHU
OHU OHU
OHU
OHU OHU
OHU
OHU
OHU OHU OHU
X
ST ST
ST
ST
H
Y
D
0.46 ac
1A
0.05 ac
1B
0.15 ac
1C
0.42 ac
1D
UD
RED CEDAR CIRCLE
ALLEY
EVERGREEN PARK
REPLAT 1, LOT 6, BLOCK 4
OWNER: DENNIS SMILIE
EVERGREEN PARK
REPLAT 1, LOT 5, BLOCK 4
OWNER: JERALD RUSSELL
REPLAT (NO. 1) OF EVERGREEN PARK
TRACT C
EVERGREEN PARK REPLAT
LOT 18, BLOCK 3
OWNER: GILLETT REVOCABLE LIVING
EVERGREEN PARK 5TH FILING
LOT 2
OWNER: PWS PROPERTIES, LLC
RAIN
GARDEN 1
DETENTION
POND 1
PARCEL #9701200002
OWNER: GLOBOK LLC
EVERGREEN PARK
REPLAT 1, LOT 7, BLOCK 4
OWNER: DEBRA & RANDOLPH MILAN
Sheet
GROWTH LEASING COLORADO 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
E NGINEER ING
N O R T H E RN
FORT COLLINS: 301 North Howes Street, Suite 100, 80521
GREELEY: 820 8th Street, 80631
970.221.4158
northernengineering.com
of 16
CALL UTILITY NOTIFICATION CENTER OF
COLORADO
Know what'sbelow.
Call before you dig.
R
City Engineer Date
Date
Date
Date
Date
Stormwater Utility
Parks & Recreation
Traffic Engineer
Date
Water & Wastewater Utility
City of Fort Collins, Colorado
UTILITY PLAN APPROVAL
Environmental Planner
( IN FEET )
0
1 INCH = 20 FEET
20 20 40 60
DR1
DRAINAGE EXHIBIT
16
LEGEND:
5013
PROPOSED CONTOUR 93
EXISTING CONTOUR
PROPERTY BOUNDARY
EXISTING STORM SEWER
1. THE SIZE, TYPE AND LOCATION OF ALL KNOWN UNDERGROUND UTILITIES ARE
APPROXIMATE WHEN SHOWN ON THESE DRAWINGS. IT SHALL BE THE
RESPONSIBILITY OF THE CONTRACTOR TO VERIFY THE EXISTENCE OF ALL
UNDERGROUND UTILITIES IN THE AREA OF THE WORK. BEFORE COMMENCING
NEW CONSTRUCTION, THE CONTRACTOR SHALL BE RESPONSIBLE FOR LOCATING
ALL UNDERGROUND UTILITIES AND SHALL BE RESPONSIBLE FOR FOR ALL
UNKNOWN UNDERGROUND UTILITIES.
2. REFER TO THE "FINAL DRAINAGE AND EROSION CONTROL REPORT FOR GROWTH
LEASING COLORADO" DATED APRIL 2, 2019 FOR ADDITIONAL INFORMATION.
NOTES:
FLOW PATH
DRAINAGE BASIN BUBBLE
A
DESIGN POINT A
BASIN BOUNDARY
PROPOSED STORM SEWER
FOR DRAINAGE REVIEW ONLY
NOT FOR CONSTRUCTION
FLOW ARROW
BASIN
DESIGNATION
BASIN
AREA (AC)
RUNOFF SUMMARY TABLE
DESIGN
POINT
BASIN
ID
TOTAL
AREA
(acres)
C2 C10 C100
2-yr Tc
(min)
10-yr Tc
(min)
100-yr
Tc
(min)
Q2
(cfs)
Q10
(cfs)
Q100
(cfs)
1A 1A 0.46 0.67 0.67 0.84 8.6 8.6 6.7 0.73 1.25 3.51
1B 1B 0.05 0.95 0.95 1.00 5.0 5.0 5.0 0.14 0.23 0.50
1C 1C 0.15 0.95 0.95 1.00 5.0 5.0 5.0 0.41 0.71 1.52
1D 1D 0.42 0.25 0.25 0.31 17.1 17.1 16.1 0.18 0.32 0.83
u
d
r
e
R
i
ve
r
Richard's
Lake
D
r
y
C
r
e
e
k
C
o
o
p
e
r
S
l
o
u
gh
Arth
u
r C
a
nal
JAX
No. 8 Outlet
SoKoinpgers
Greenbriar
RBarubsbhit
Eastridge
Trailhead
HIororsne
Airport
CLaankael
MHaipllle
RiLcahkaerds
CNoomrtmheuansitty
Water Quality Dry Master Conceptual Creek Plan Alternatives
DC3 Improvements Channel
Proposed ● Buyout Property Adriel Hills and Pond place
Water Quality Pond
Lindenmeier ●Lake Water Quality Treatment
provided Lindenmeier in Existing Lake
Pheasant ●Pond Retrofit Existing Ridge Pond to
accommodate Volume Water Quality
Terry ● Retrofit Lake Existing Road Pond Pond to
accommodate Volume Water Quality
Spalding ●Pond Retrofit Lane Existing Pond to
accommodate Volume Water Quality
NCDID Quality Regional Pond Water
NECCO Quality Pond Regional Water
0 500 1,000 2,000 [
Feet
NAIP Image - 2009
Proposed BMP Basin Type
Dry Creek Basin Boundary
Flood Control Only
Water Quality Only
Flood Control and Water Quality
Proposed Improvements
None
Proposed Proposed WaterConceptual Quality Alternatives
Undeveloped Area
Water
Stream - Canal
#* Proposed Water Quality Pond
Natural Area
Parks
Existing
Proposed
of the version date(s) listed below.
Soil Survey Area: Larimer County Area, Colorado
Survey Area Data: Version 13, Sep 10, 2018
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Sep 20, 2015—Oct
21, 2017
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
Hydrologic Soil Group—Larimer County Area, Colorado
(Growth Leasing)
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
3/4/2019
Page 2 of 4
Total Impervious Area Treated (sf) 15,008
Proposed On-site Impervious Area (sf) 20,615
75% Required Minimum Area to be Treated by LID Measures (sf) 15,461
Proposed On-site Treated Area (sf) 15,008
Percent Treated by LID Measures 73%
Discharge (cfs)
Stage (ft)
Stage - Discharge Curves
Weir Flow
Orifice Flow
Q = 3 . 0 P H 1 . 5
Q = 0 . 67 A ( 2 gH ) 0 . 5
Project Location :
Design Point
C =
Design Storm
3/27/2019
1:33 PM
1585-001_FAA Detention.xls
POND-1_ModFAAVol
Northern Engineering Services
Tc
(min)
10-yr
Tc
(min)
100-yr
Tc
(min)
1A 1A No 0.67 0.67 0.84 60 2.2 4.7 4.7 2.9 290 0.5 1.41 3.4 36 1.0 1.50 0.4 8.6 8.6 6.7
1B 1B No 0.95 0.95 1.00 52 15.0 0.8 0.8 0.5 0 0.0 0.00 N/A 0 0.0 0.00 N/A 5.0 5.0 5.0
1C 1C No 0.95 0.95 1.00 52 5.0 1.2 1.2 0.8 0 0.0 0.00 N/A 0 0.0 0.00 N/A 5.0 5.0 5.0
1D 1D No 0.25 0.25 0.31 125 2.0 14.1 14.1 13.1 0 0.0 0.00 N/A 190 0.5 1.06 3.0 17.1 17.1 16.1
DEVELOPED TIME OF CONCENTRATION COMPUTATIONS
Gutter Flow Swale Flow
Design
Point
Basin
Overland Flow
D. Weber
March 13, 2019
Time of Concentration
(Equation RO-4)
( )
3
1
1 . 87 1 . 1 *
S
C Cf L
Ti
= −
\\BRONCOS\Engineers\Projects\1585-001\Drainage\Hydrology\1585-001_Rational.xlsx\Tc-2-yr_&_100-yr
Total 47,214.83 1.08 0.21 0.07 0.20 0.00 0.00 0.60 0.56 0.56 0.70 44%
Rain Garden 22,207.50 0.51 0.21 0.07 0.05 0.00 0.00 1.02 1.12 1.12 1.00 68%
DEVELOPED COMPOSITE % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS
Runoff Coefficients are taken from the City of Fort Collins Storm Drainage Design Criteria and Construction Standards, Table 3-3. % Impervious taken from UDFCD USDCM, Volume I.
10-year Cf
= 1.00
March 13, 2019
\\BRONCOS\Engineers\Projects\1585-001\Drainage\Hydrology\1585-001_Rational.xlsx\C-Values
3. Rain Garden 1 is used as the Low Impact Development (LID) measure for basins 1A
and 1B. This accounts for 73% of the on-site impervious area. Please see the
Appendix for detailed calculations.
C. Specific Details
1. Storm Sewer were sized for the 100-yr storm utilized the program Hydraflow for
AutoCAD extension.