HomeMy WebLinkAboutTHE OVERLOOK - PDP - PDP160011 - REPORTS - DRAINAGE REPORTPRELIMINARY DRAINAGE AND
EROSION CONTROL REPORT
June 1, 2016
The Overlook
Fort Collins, Colorado
Prepared for:
Stockover Investments, LLC
1806 Westview Road
Fort Collins, CO 80524
970-556-8132
Prepared by:
301 N. Howes Street, Suite 100
Fort Collins, Colorado 80521
Phone: 970.221.4158
www.northernengineering.com
Project Number: 1174-001
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.
RE: Preliminary Drainage and Erosion Control Report for
The Overlook
Dear Staff:
Northern Engineering is pleased to submit this Preliminary Drainage and Erosion Control Report for
your review. This report accompanies Project Development Plan submittal for the proposed The
Overlook 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.
Stephanie Thomas, PE
Project Engineer
The Overlook
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 ........................................................................................................................ 4
C. Development Criteria Reference and Constraints ......................................................................... 5
D. Hydrological Criteria .................................................................................................................... 5
E. Hydraulic Criteria ......................................................................................................................... 5
F. Floodplain Regulations Compliance .............................................................................................. 6
G. Modifications of Criteria .............................................................................................................. 6
IV. DRAINAGE FACILITY DESIGN .................................................................................... 6
A. General Concept .......................................................................................................................... 6
B. Specific Details ............................................................................................................................. 8
V. CONCLUSIONS ........................................................................................................ 8
A. Compliance with Standards .......................................................................................................... 8
B. Drainage Concept ........................................................................................................................ 8
References ......................................................................................................................... 9
APPENDICES:
APPENDIX A – Hydrologic Computations
APPENDIX B – Hydraulic Computations (NOT INCLUDED WITH PDP)
B.1 – Detention Ponds and Water Quality
B.2 – Storm Sewers (NOT INCLUDED WITH PDP)
B.3 – Inlets (NOT INCLUDED WITH PDP)
APPENDIX C – SWMM Modeling
APPENDIX D – Erosion Control Report
APPENDIX E – LID Exhibit
APPENDIX F – References
The Overlook
Preliminary Drainage Report
LIST OF TABLES AND FIGURES:
Figure 1 – Aerial Photograph ................................................................................................ 2
Figure 2– Proposed Site Plan ................................................................................................ 3
Figure 3 – Existing Floodplains ............................................................................................. 3
MAP POCKET:
DR1 - Drainage Exhibit
The Overlook
Preliminary Drainage Report 1
I. GENERAL LOCATION AND DESCRIPTION
A. Location
1. Vicinity Map
2. Located in the western half of Section 36, Township 7 North, Range 69 West of the
6th Prime Meridian, City of Fort Collins, County of Larimer, State of Colorado. The site
is a part of Lots 3 and 4, Observatory Heights.
3. Bounded to the north by First National Bank 1st PUD, to the west by John F. Kennedy
Parkway, to the south by Larimer County Canal, and to the east by a Private Drive
and Wharf at the Landings PUD Phase 2 Replat.
4. No significant offsite flows are directed into the site. The majority of off-site flows are
are prevented from entering the site by curb and gutter.
5. The Overlook was originally included in the Revised Master Plan and Supplemental
Drainage Report for Fort Collins National Bank PUD, prepared by Cornell Consulting
Company, Revised April 4, 1980.
The Overlook
Preliminary Drainage Report 2
B. Description of Property
1. The site is approximately 3.29 acres. Approximately 0.23 acres of the 3.29 acres is a
parcel of land already developed by the First National Bank PUD; hence this area is
included in the original drainage report and accounted for in the existing detention
pond.
Figure 1 – Aerial Photograph
2. The existing site is comprised of vacant land with natural grasses and vegetation. In the
northeast corner of the site exists an existing parking lot. This existing parking lot will
be demolished with this project and reconfigured in another location.
3. The majority of the site slopes to the north, while an eastern portion slopes to the east.
4. A report by Earth Engineering Consultants dated December 14, 2015 lists the soils for
the area as consisting of lean clay with varying amounts of silt and sand, and
sandstone/siltstone bedrock ranging from 2 to 7 feet below the ground surface. These
soils are classified as Hydrologic Soil Group C and have a low infiltration rate.
5. The proposed project site plan is composed of 2 buildings connected by a walkway.
These buildings are classified as mixed-use with commercial on the first floor and
residential above. This site will employ water quality features and runoff reduction
facilities including rain gardens and extended detention basins.
The Overlook
Preliminary Drainage Report 3
Figure 2– Proposed Site Plan
6. No existing irrigation facilities are known at this time.
7. The project site is within the First National Bank 1st PUD Master Plan. 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.
Figure 3 – Existing Floodplains
The Overlook
Preliminary Drainage Report 4
II. DRAINAGE BASINS AND SUB-BASINS
A. Major Basin Description
1. The Overlook project is located within the Foothills Drainage Basin, which is located
between Prospect Road and Larimer #2 Canal from north to south and approximately
between Shields Street and Zeigler Road from west to east.
B. Sub-Basin Description
1. The western half of the property generally drains to the center of the property. From
there, flows are conveyed north in a swale to the access road bordering the north side
of the property. Flows within the access road are collected in an inlet at Horsetooth
Road. From there, flows are detained and released to Warren Reservoir.
2. The eastern half of the site generally sheet flows to the eastern boundary. From there,
flows sheet flow to backlot swales and drain pans routing flows around the existing
residential buildings. These flows are also collected in downstream inlets and
detained prior to be released to Warren Reservoir.
3. The proposed plan will generally detain developed flows and release to the detention
ponds north of the site, on the First National Bank property. These ponds have been
sized and included in the previous drainage report.
III. DRAINAGE DESIGN CRITERIA
A. Regulations
There are no optional provisions outside of the FCSCM proposed with The Overlook
project.
B. Four Step Process
The overall stormwater management strategy employed with The Overlook 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:
Providing rain gardens throughout the site to reduce the overall impervious area and to
minimize directly connected impervious areas (MDCIA).
Providing planter boxes with a rain garden filter section at downspout locations from
the building to reduce runoff from the rooftops.
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 majority of stormwater runoff from the site will ultimately be
intercepted and treated in proposed water quality ponds.
The Overlook
Preliminary Drainage Report 5
Step 3 – Stabilize Drainageways
There are no major drainageways within the subject property. This property discharges to
existing detention ponds that have been designed to accommodate runoff from this project
as a part of the First National Bank 1st PUD Master Plan.
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 enclosures within the development will allow for the disposal of solid
waste.
Rain gardens and planter boxes for water treatment prior to flows entering the
extended detention basins.
Water Quality measures to protect and prolong the design life of the BMPs delineated
in Step 1.
C. Development Criteria Reference and Constraints
1. The proposed site is a part of the Revised Master Plan and Supplemental Drainage
Report for Fort Collins National Bank PUD, prepared by Cornell Consulting Company,
Revised April 4, 1980. This report states a release rate of 75% of the 2-year release.
This is less than the typical 2-year release requirement.
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.
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. EPA SWMM modeling was utilized for detention storage calculations.
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 subject property historically drains to the north and east.
The north flows are collected in an existing inlet on the private access drive at
Horsetooth Road then conveyed to an existing detention pond that releases to Warren
The Overlook
Preliminary Drainage Report 6
Reservoir.
2. All drainage facilities proposed with The Overlook 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 Overlook project does not propose to modify any natural drainageways.
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. 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 Overlook drainage design are to maintain the allowable
storm runoffs as outlined within the Revised Master Plan and Supplemental Drainage
Report for Fort Collins National Bank PUD.
2. 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.
3. Historic runoff from The Overlook project site was evaluated. This evaluation provided
the historic 2-yr and 100-yr peak runoff rates for the existing site.
Basin H1
Basin H1 has an area of 0.23 acres. This basin contains a portion of the existing
private access road and an existing parking lot. The 2-yr and 100-yr peak runoff rates
from Basin H1 are 0.56 cfs and 2.27 cfs, respectively. Basin H1 has been accounted
for in previous subdivision drainage designs. Therefore, detention of this area is not
proposed.
Basin H2
Basin H2 has an area of 3.04 acres. This basin contains the majority of The Overlook
site. This existing basin contains vacant land. The 2-yr and 100-yr peak runoff rates
from Basin H2 are 1.05 cfs and 4.78 cfs, respectively.
4. The Overlook project divided the site into three (3) major drainage basins, designated
as Basins A, B, and UD. The project further subdivided Basin A in to seven (7) sub-
basins, Basin B into five (5) sub-basins, and Basin UD into five (5) sub-bains. The
drainage patterns anticipated for each basin and sub-basin are further described
below.
Basin A
Basin A is a total of 1.74 acres. Basin A consists of proposed building, parking lot,
sidewalk, landscape areas and rain gardens. Runoff from Basins A1, A2, A3 and A4
The Overlook
Preliminary Drainage Report 7
flow via overland flow and gutter to proposed rain gardens. Runoff from Basin A5 is
collected in trench drains and conveyed to Detention Pond A. Runoff from Basin A7 is
collected in a curb inlet and conveyed to Detention Pond A. Basin A7 contains
Detention Pond A. Total flow during a 100-yr storm from Basin A is calculated at a
routed 11.67 cfs.
Basin B
Basin B is a total of 1.04 acres. Basin B consists of proposed building, parking lot,
sidewalk, landscape areas and rain gardens. Runoff from Basins B1 and B2 are
collected in a storm pipe and curb inlet and are conveyed to a rain garden. Runoff
from Basins B3 and B4 are collected by curb inlets and are conveyed to Detention
Pond B. Basin B5 contains Detention Pond B. Total flow during a 100-yr storm from
Basin B is calculated at a routed 5.87 cfs.
Basin UD
Basin UD is a total of 0.50 acres. This basin is not detained and runoff will continue
to flow to historic capture points.
Basin UD1 and UD5 will continue, as historically, to overland flow to the adjacent The
Wharf Subdivision. Basins UD1 and UD5 have a percent impervious of 0%. Runoff
from these basins is considered negligible and similar to historic.
Basins UD2, UD3, and UD4 combine for a developed 49% impervious and total
combined area of 0.44 acres. These basins overland flow to either JFK Parkway or
the Private Access Road. Flows are conveyed along gutters to an inlet located at the
intersection of the Private Access Drive and Horsetooth Road. Total flows during a
100-yr storm from Basins UD2, UD3, and UD4 are a combined routed flow of 2.49
cfs.
5. Two (2) detention ponds are proposed with The Overlook development. Detention
Pond A is located within Basin A and Detention Pond B is located within Basin B.
Detention Pond B is routed through Detention Pond A. Release from Detention Pond
A is then conveyed to the existing detention pond on the Bank Property.
Detention Pond A
Detention Pond A has a total of 0.50 ac-ft storage available. 0.45 ac-ft of storage is
required with this project. Water quality control volume for Basin A is included in the
pond volume. Emergency Overflow from the pond is directed north to the existing
access road. Release rate from Pond A is proposed at 0.57 cfs.
Detention Pond B
Detention Pond B has a total of 0.32 ac-ft storage available. 0.25 ac-ft of storage is
required with this project. Water quality control volume for Basin B is included in the
pond volume. Emergency Overflow from the pond is directed east to The Wharf
development. 0.68 ft of freeboard is provided to prevent emergency overflow. The
existing The Wharf development should be able to accommodate any emergency
overflow from the site through a network of drainage pans. Release rate from Pond B
is proposed at 0.21 cfs.
The Overlook
Preliminary Drainage Report 8
Total Stormwater Release from Site
The total allowable 100-yr release from the site is a summation of the historic 100-yr
runoff from Basin H1 (2.27 cfs), plus 75% of the historic 2-yr runoff from Basin H2
(1.05*0.75=0.79 cfs). This totals 3.06 cfs total release allowable from The Overlook
site during a 100-yr event.
Total developed 100-yr release from the site is a combination of the undetained 100-
year flows from Basins UD2, UD3, and UD4 (2.49 cfs) plus the 0.57 cfs release from
Pond A for a total 3.06 cfs release.
A full-size copy of the Drainage Exhibit can be found in the Map Pocket at the end of
this report.
B. Specific Details
1. Additional details to be provided with the FDP submittal.
V. CONCLUSIONS
A. Compliance with Standards
1. The drainage design proposed with The Overlook project complies with the City of
Fort Collins’ Stormwater Criteria Manual.
2. The drainage design proposed with The Overlook project complies with the City of
Fort Collins’ Master Drainage Plan for the Foothills 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 achieves the requirements set forth by the City of Fort Collins for Low Impact
Development (LID) by providing 76% total impervious areas as being treated through
an LID treatment. 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 from rain gardens. This is
currently unable to be calculated with available soils data.
The Overlook
Preliminary Drainage Report 9
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. Supplemental Drainage Report for Fort Collins National Bank PUD, April 4, 1980, Cornell
Consulting Company.
3. Subsurface Exploration Report, JFK Luxury Apartments Fort Collins, Colorado, December 14,
2015, Earth Engineering Consultants, Inc.(EEC Project No. 1152119).
4. Larimer County Urban Area Street Standards, Adopted January 2, 2001, Repealed and
Reenacted, Effective October 1, 2002, Repealed and Reenacted, Effective April 1, 2007.
5. Soils Resource Report for Larimer County Area, Colorado, Natural Resources Conservation
Service, United States Department of Agriculture.
6. Urban Storm Drainage Criteria Manual, Volumes 1-3, Urban Drainage and Flood Control
District, Wright-McLaughlin Engineers, Denver, Colorado, Revised April 2008.
APPENDIX A
HYDROLOGIC COMPUTATIONS
The Overlook
CHARACTER OF SURFACE
1
:
Runoff
Coefficient
Percentage
Impervious Project: The Overlook
Streets, Parking Lots, Roofs, Alleys, and Drives: Calculations By: S. Thomas
Asphalt ……....……………...……….....…...……………….………………………………………………………….0.95 . 100% Date: March 29, 2016
Concrete …….......……………….….……….………………..….…………………………………………………….0.95 . 90%
Gravel (packed) ……….…………………….….…………………………..………………………………………….0.50 . 40%
Roofs …….…….………………..……………….……………………………………………………………………… 0.95 90%
Pavers…………………………...………………..……………………………………………………………………… 0.40 22%
Lawns and Landscaping
Sandy Soil
Flat <2% ……………………………………………………………………………………………………………… 0.10 0%
Average 2% to 7% ………………………………………………………………………………………………….0.15 . 0%
Steep >7% …………………………………………………………………………………………………………… 0.20 0%
Clayey Soil
Flat <2% ……………………………………………………………………………………………………………… 0.20 0%
Average 2% to 7% ………………………………………………………………………………………………….0.25 . 0%
Steep >7% …………………………………………………………………………………………………………… 0.35 0% 2-year Cf = 1.00 10-year Cf = 1.00 100-year Cf = 1.25
Runoff Coefficients are taken from the Fort Collins Stormwater Criteria Manual, Table RO-11
Sub-Basin ID
Sub-
BasinBasin
Area
(ac)
Area of
Asphalt
(ac)
Area of
Concrete
(ac)
Area of
Pavers
(ac)
Area of
Roofs
(ac)
Soil Type and Average
Slope
Area of
Lawns and
Landscaping
(ac)
2-year
Composite
Runoff
Coefficient
10-year
Composite Runoff
Coefficient
100-year
Composite Runoff
Coefficient
Composite
% Imperv.
H1 0.23 0.17 0.03 0.00 0.00 Clayey | Average 2% to 7% 0.029 0.86 0.86 1.00 86%
The Overlook
Overland Flow, Time of Concentration:
The Overlook
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)
2-yr
Tc
(min)
10-yr
Tc
(min)
100-yr
Tc
(min)
1 H1 No 0.86 0.86 1.00 104 2.40% 3.4 3.4 1.4 267 1.69% 2.60 1.7 5.1 5.1 5.0
2 H2 Yes 0.25 0.25 0.31 526 2.47% 27.0 27.0 25.0 0 N/A N/A N/A 27.0 27.0 25.0
* Time of Concentrations are calculated for the entire basin and used for both the Impervious and Pervious portions of the basins.
EXISTING TIME OF CONCENTRATION COMPUTATIONS
S. Thomas
The Overlook
Rational Method Equation: Project: The Overlook
Calculations By:
Date:
Rainfall Intensity:
1 H1 0.23 5 5 5 0.86 0.86 1.00 2.85 4.87 9.95 0.56 0.96 2.27
2 H2 3.04 27 27 25 0.25 0.25 0.31 1.39 2.37 5.04 1.05 1.80 4.78
EXISTING 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)
Sub-Basin(s)
S. Thomas
Rainfall Intensity taken from the Fort Collins Stormwater Criteria Manual (FCSCM), Tables RA-7 and RA-8
March 29, 2016
Intensity,
i10
(in/hr)
C10
Area, A
(acres)
Intensity,
i2
(in/hr)
100-yr
Tc
(min)
Q = C f ( C )( i )( A )
3/29/2016 12:08 PM D:\Projects\1174-001\Drainage\Hydrology\1174-001_Existing_Rational_Calcs.xlsx\Runoff
The Overlook
CHARACTER OF SURFACE
1
:
Runoff
Coefficient
Percentage
Impervious Project: The Overlook
Streets, Parking Lots, Roofs, Alleys, and Drives: Calculations By: S. Thomas
Asphalt ……....……………...……….....…...……………….………………………………………………………….0.95 . 100% Date: May 31, 2016
Concrete …….......……………….….……….………………..….…………………………………………………….0.95 . 90%
Gravel (packed) ……….…………………….….…………………………..………………………………………….0.50 . 40%
Roofs …….…….………………..……………….……………………………………………………………………… 0.95 90%
Pavers…………………………...………………..……………………………………………………………………… 0.40 22%
Lawns and Landscaping
Sandy Soil
Flat <2% ……………………………………………………………………………………………………………… 0.10 0%
Average 2% to 7% ………………………………………………………………………………………………….0.15 . 0%
Steep >7% …………………………………………………………………………………………………………… 0.20 0%
Clayey Soil
Flat <2% ……………………………………………………………………………………………………………… 0.20 0%
Average 2% to 7% ………………………………………………………………………………………………….0.25 . 0%
Steep >7% …………………………………………………………………………………………………………… 0.35 0% 2-year Cf = 1.00 10-year Cf = 1.00 100-year Cf = 1.25
Runoff Coefficients are taken from the Fort Collins Stormwater Criteria Manual, Table RO-11
Sub-Basin ID
Sub-
BasinBasin
Area
(ac)
Area of
Asphalt
(ac)
Area of
Concrete
(ac)
Area of
Pavers
(ac)
Area of
Roofs
(ac)
Soil Type and Average
Slope
Area of
Lawns and
Landscaping
(ac)
2-year
Composite
Runoff
Coefficient
10-year
Composite Runoff
Coefficient
100-year
Composite Runoff
Coefficient
Composite
% Imperv.
A1 0.55 0.00 0.01 0.00 0.54 Clayey | Average 2% to 7% 0.000 0.95 0.95 1.00 90%
The Overlook
Overland Flow, Time of Concentration:
The Overlook
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)
2-yr
Tc
(min)
10-yr
Tc
(min)
100-yr
Tc
(min)
1 A1 No 0.95 0.95 1.00 91 12.42% 1.2 1.2 0.8 N/A N/A N/A 5.0 5.0 5.0
1 A2 No 0.30 0.30 0.38 97 0.82% 15.6 15.6 14.1 N/A N/A N/A 15.6 15.6 14.1
2 A3 No 0.92 0.92 1.00 157 5.57% 2.4 2.4 1.3 161 0.78% 1.76 1.5 5.0 5.0 5.0
3 A4 No 0.87 0.87 1.00 58 4.14% 2.1 2.1 0.9 170 0.35% 1.19 2.4 5.0 5.0 5.0
4 A5 No 0.88 0.88 1.00 33 0.91% 2.4 2.4 1.1 N/A N/A N/A 5.0 5.0 5.0
The Overlook
Rational Method Equation: Project: The Overlook
Calculations By:
Date:
Rainfall Intensity:
1 A1 0.55 5 5 5 0.95 0.95 1.00 2.85 4.87 9.95 1.49 2.54 5.46
1 A2 0.10 16 16 14 0.30 0.30 0.38 1.84 3.14 6.71 0.06 0.10 0.25
2 A3 0.43 5 5 5 0.92 0.92 1.00 2.85 4.87 9.95 1.14 1.95 4.32
3 A4 0.22 5 5 5 0.87 0.87 1.00 2.85 4.87 9.95 0.54 0.92 2.18
4 A5 0.10 5 5 5 0.88 0.88 1.00 2.85 4.87 9.95 0.26 0.45 1.03
5 A6 0.18 5 5 5 0.86 0.86 1.00 2.85 4.87 9.95 0.44 0.75 1.78
6 A7 0.16 5 5 5 0.25 0.25 0.31 2.85 4.87 9.95 0.11 0.19 0.48
TOTAL BASIN A TOTAL BASIN A 1.74 16 16 14 0.82 0.82 1.00 1.84 3.14 6.71 2.62 4.47 11.67
7 B1 0.32 7 7 5 0.61 0.61 0.77 2.52 4.31 9.95 0.50 0.85 2.46
8 B2 0.27 5 5 5 0.95 0.95 1.00 2.85 4.87 9.95 0.73 1.24 2.67
9 B3 0.11 5 5 5 0.86 0.86 1.00 2.85 4.87 9.95 0.27 0.46 1.09
10 B4 0.11 5 5 5 0.85 0.85 1.00 2.85 4.87 9.95 0.27 0.46 1.10
11 B5 0.24 16 16 15 0.28 0.28 0.35 1.81 3.08 6.62 0.12 0.21 0.56
TOTAL BASIN B TOTAL BASIN B 1.05 16 16 15 0.67 0.67 0.84 1.81 3.08 6.62 1.28 2.19 5.87
13 UD2 0.04 12 12 11 0.33 0.33 0.41 2.09 3.57 7.42 0.03 0.05 0.13
13 UD3 0.10 11 11 10 0.35 0.35 0.44 2.17 3.71 7.72 0.07 0.13 0.33
13 UD4 0.30 5 5 5 0.73 0.73 0.91 2.85 4.87 9.95 0.63 1.08 2.76
TOTAL BASIN UD2-UD4
TOTAL BASIN
UD2-UD4 0.44
12 12 11 0.61 0.61 0.76 2.09 3.57 7.42 0.56 0.96 2.49
12 UD1 0.03 5 5 5 0.25 0.25 0.31 2.85 4.87 9.95 0.02 0.03 0.08
12 UD5 0.03 5 5 5 0.25 0.25 0.31 2.85 4.87 9.95 0.02 0.03 0.09
TOTAL SITE TOTAL SITE 3.29 16 16 15 0.74 0.74 0.92 1.81 3.08 6.62 4.38 7.45 20.00
May 31, 2016
Intensity,
i10
(in/hr)
C10
Area, A
(acres)
Intensity,
i2
(in/hr)
100-yr
Tc
(min)
PROPOSED RUNOFF COMPUTATIONS
C100
Design
Point
Flow,
Q100
(cfs)
Flow,
Q2
(cfs)
10-yr
Tc
(min)
2-yr
Tc
(min)
C2
Flow,
APPENDIX B
HYDRAULIC COMPUTATIONS
B.1 DETENTION POND SIZING
B.2 STORM SEWER (NOT INCLUDED)
B.3 INLET (NOT INCLUDED)
APPENDIX B.1
DETENTION PONDS AND WATER QUALITY
The Overlook
1174-001
Fort Collins, Colorado
S. Thomas Date: 5/31/2016
Pond No.: Detention Pond A
A
100-yr WQCV total 2084 ft3
1.00 Approx. Rain Garden Vol. 1467 ft3
Area (A)= 1.74 acres WQCV Required 617 ft3
Max Release Rate = 0.57 cfs Quantity Detention 18881 ft3 (per SWMM)
Total Volume 19498 ft3
Total Volume 0.45 ac-ft
Detention Pond Calculation | SWMM Method
Project Number:
Project Location:
Calculations By:
Input Variables Results
Design Point
Design Storm
Developed "C" =
Required Detention Volume
5/31/2016 2:06 PM D:\Projects\1174-001\Drainage\Detention\1174-001__Detention Pond A.xlsm\FAA_CoFC idf_Pond 1
1174-001
Fort Collins, CO
S. Thomas Date: 5/31/2016
Pond No.: A
A7
100-yr
0.45 acft 5019.97 ft.
Design Storm WQCV
Required Volume= 617 ft3 5014.02 ft.
Contour
Elevation (Y-
values)
Contour Area Depth
Column Not
Used
Incremental
Volume
Total Volume Total Volume
ft2 ft. ft3 ft3 ft3 acre-feet
5,013.20 7.7 0.00 0 0 0 0
5,013.40 244.02 0.20 20 20 0.00
5,013.60 803.69 0.20 99 119 0.00
5,013.80 1,333.72 0.20 211 330 0.01
5,014.00 1,511.37 0.20 284 614 0.01
5,014.20 1,628.45 0.20 314 928 0.02
5,014.40 1,749.36 0.20 337 1265 0.03
5,014.60 1,875.79 0.20 362 1627 0.04
5,014.80 2,009.54 0.20 388 2015 0.05
5,015.00 2,154.87 0.20 416 2431 0.06
5,015.20 2,237.34 0.20 439 2870 0.07
5,015.40 2,321.15 0.20 455 3325 0.08
5,015.60 2,423.05 0.20 474 3799 0.09
5,015.80 2,538.12 0.20 496 4295 0.10
5,016.00 2,662.90 0.20 520 4814 0.11
5,016.20 2,768.83 0.20 543 5357 0.12
5,016.40 2,883.13 0.20 565 5922 0.14
5,016.60 3,008.11 0.20 588 6510 0.15
5,016.80 3,136.88 0.20 614 7124 0.16
5,017.00 3,270.11 0.20 640 7764 0.18
5,017.20 3,388.00 0.20 665 8429 0.19
5,017.40 3,479.57 0.20 686 9115 0.21
5,017.60 3,564.42 0.20 704 9819 0.23
5,017.80 3,643.25 0.20 720 10539 0.24
5,018.00 3,719.24 0.20 735 11274 0.26
5,018.20 3,801.90 0.20 751 12026 0.28
5,018.40 3,885.54 0.20 768 12794 0.29
5,018.60 3,970.30 0.20 785 13578 0.31
5,018.80 4,059.01 0.20 802 14381 0.33
5,019.00 4,150.05 0.20 820 15201 0.35
5,019.20 4,261.66 0.20 840 16041 0.37
5,019.40 4,375.21 0.20 863 16904 0.39
5,019.60 4,495.27 0.20 886 17790 0.41
5,019.80 4,653.89 0.20 914 18704 0.43
5,020.00 4,838.55 0.20 948 19652 0.45
5,020.20 5,038.34 0.20 987 20639 0.47
5,020.40 5,254.04 0.20 1028 21667 0.50
Design Point
Design Storm
Require Volume=
Stage - Storage Calculation
The Overlook
1174-001
Fort Collins, Colorado
S. Thomas Date: 5/31/2016
Pond No.: Detention Pond B
B
100-yr WQCV total 915 ft3
0.84 Approx. Rain Garden Vol. 457 ft3
Area (A)= 1.05 acres WQCV Required 458 ft3
Max Release Rate = 0.21 cfs Quantity Detention 10392 ft3 (per SWMM)
Total Volume 10850 ft3
Total Volume 0.25 ac-ft
Detention Pond Calculation | SWMM Method
Project Number:
Project Location:
Calculations By:
Input Variables Results
Design Point
Design Storm
Developed "C" =
Required Detention Volume
5/31/2016 2:05 PM D:\Projects\1174-001\Drainage\Detention\1174-001__Detention Pond B.xlsm\SWMM_CoFC idf_Pond 1
1174-001
Fort Collins, CO
S. Thomas Date: 5/31/2016
Pond No.: B
B
100-yr
0.25 acft 5021.32 ft.
Design Storm WQCV
Required Volume= 458 ft
3 5017.91 ft.
Contour
Elevation (Y-
values)
Contour Area Depth
Column Not
Used
Incremental
Volume
Total Volume Total Volume
ft
2
ft. ft
3
ft
3
ft
3
acre-feet
5,016.60 0.47 0.00 0 0 0 0
5,016.80 38.37 0.20 3 3 0.00
5,017.00 138.99 0.20 17 20 0.00
5,017.20 283.65 0.20 41 61 0.00
5,017.40 438.86 0.20 72 133 0.00
5,017.60 604.53 0.20 104 236 0.01
5,017.80 781 0.20 138 374 0.01
5,018.00 968.53 0.20 174 549 0.01
5,018.20 1,167.28 0.20 213 762 0.02
5,018.40 1,377.14 0.20 254 1016 0.02
5,018.60 1,598.00 0.20 297 1313 0.03
5,018.80 1,829.44 0.20 342 1655 0.04
5,019.00 2,069.73 0.20 389 2044 0.05
5,019.20 2,318.44 0.20 438 2482 0.06
5,019.40 2,575.87 0.20 489 2971 0.07
5,019.60 2,843.14 0.20 541 3512 0.08
5,019.80 3,120.19 0.20 596 4108 0.09
5,020.00 3,406.96 0.20 652 4760 0.11
5,020.20 3,713.59 0.20 711 5471 0.13
5,020.40 4,074.84 0.20 778 6248 0.14
5,020.60 4,461.82 0.20 853 7101 0.16
5,020.80 4,853.28 0.20 930 8031 0.18
5,021.00 5,249.01 0.20 1009 9040 0.21
5,021.20 5,648.98 0.20 1088 10129 0.23
5,021.40 6,053.19 0.20 1169 11297 0.26
5,021.60 6,461.64 0.20 1250 12547 0.29
5,021.80 6,874.34 0.20 1332 13880 0.32
Design Point
Design Storm
Require Volume=
Stage - Storage Calculation
Project Number:
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1. Basin Storage Volume
A) Effective Imperviousness of Tributary Area, Ia Ia = 84.0 %
(100% if all paved and roofed areas upstream of rain garden)
B) Tributary Area's Imperviousness Ratio (i = Ia/100) i = 0.840
C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.28 watershed inches
(WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i)
D) Contributing Watershed Area (including rain garden area) Area = 14,044 sq ft
E) Water Quality Capture Volume (WQCV) Design Volume VWQCV = 332 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 = 14 in 12-INCH MAXIMUM
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 = 236 sq ft
D) Actual Flat Surface Area AActual = sq ft
E) Area at Design Depth (Top Surface Area) ATop = sq ft
F) Rain Garden Total Volume VT= 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)
Stephanie Thomas
Northern Engineering
May 31, 2016
The Overlook
Rain Garden L1
Choose One
Choose One
18" Rain Garden Growing Media
Other (Explain):
YES
NO
UD-BMP_v3.05-Rain Garden L1.xlsm, RG 5/31/2016, 2:33 PM
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1. Basin Storage Volume
A) Effective Imperviousness of Tributary Area, Ia I
a = 77.0 %
(100% if all paved and roofed areas upstream of rain garden)
B) Tributary Area's Imperviousness Ratio (i = Ia/100) i = 0.770
C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.25 watershed inches
(WQCV= 0.8 * (0.91* i
3
- 1.19 * i
2
+ 0.78 * i)
D) Contributing Watershed Area (including rain garden area) Area = 28,237 sq ft
E) Water Quality Capture Volume (WQCV) Design Volume VWQCV = 584 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 = 0.00 ft / ft
(Use "0" if rain garden has vertical walls)
C) Mimimum Flat Surface Area AMin = 435 sq ft
D) Actual Flat Surface Area AActual = sq ft
E) Area at Design Depth (Top Surface Area) ATop = sq ft
F) Rain Garden Total Volume VT= cu ft
(VT= ((A
Top + 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)
Stephanie Thomas
Northern Engineering
May 31, 2016
The Overlook
Rain Garden L2
Choose One
Choose One
18" Rain Garden Growing Media
Other (Explain):
YES
NO
UD-BMP_v3.05-Rain Garden L2.xlsm, RG 5/31/2016, 2:36 PM
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1. Basin Storage Volume
A) Effective Imperviousness of Tributary Area, Ia Ia = 94.0 %
(100% if all paved and roofed areas upstream of rain garden)
B) Tributary Area's Imperviousness Ratio (i = Ia/100) i = 0.940
C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.35 watershed inches
(WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i)
D) Contributing Watershed Area (including rain garden area) Area = 18,904 sq ft
E) Water Quality Capture Volume (WQCV) Design Volume VWQCV = 551 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 = 14 in 12-INCH MAXIMUM
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 = 355 sq ft
D) Actual Flat Surface Area AActual = sq ft
E) Area at Design Depth (Top Surface Area) ATop = sq ft
F) Rain Garden Total Volume VT= 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)
Stephanie Thomas
Northern Engineering
May 31, 2016
The Overlook
Rain Garden L3
Choose One
Choose One
18" Rain Garden Growing Media
Other (Explain):
YES
NO
UD-BMP_v3.05-Rain Garden L3.xlsm, RG 5/31/2016, 2:37 PM
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 = 25,730 sq ft
E) Water Quality Capture Volume (WQCV) Design Volume VWQCV = 457 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 = 350 sq ft
D) Actual Flat Surface Area AActual = sq ft
E) Area at Design Depth (Top Surface Area) ATop = sq ft
F) Rain Garden Total Volume VT= 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)
Stephanie Thomas
Northern Engineering
May 31, 2016
The Overlook
Rain Garden L4
Choose One
Choose One
18" Rain Garden Growing Media
Other (Explain):
YES
NO
UD-BMP_v3.05-Rain Garden L4.xlsm, RG 5/31/2016, 2:37 PM
APPENDIX B.2
STORM SEWERS
APPENDIX B.3
INLETS
APPENDIX C
SWMM MODELING
SUBA1
SUBA2
SUBA3
SUBA4
SUBA5
SUBA6
SUBA7
SUBB1
SUBB2
SUBB3
SUBB4
SUBB5
2
3
4
5
6
7
8
9
10
OUTB
OUTA
J2
J1
J3
J4
J5
J6
J7
J8
J9
OUTFALL
PONDB
PONDA
FC-100YR
05/18/2016 00:15:00
SWMM 5 Page 1
[TITLE]
[OPTIONS]
FLOW_UNITS CFS
INFILTRATION HORTON
FLOW_ROUTING KINWAVE
START_DATE 05/18/2016
START_TIME 00:00:00
REPORT_START_DATE 05/18/2016
REPORT_START_TIME 00:00:00
END_DATE 05/18/2016
END_TIME 06:00:00
SWEEP_START 01/01
SWEEP_END 12/31
DRY_DAYS 0
REPORT_STEP 00:15:00
WET_STEP 00:15:00
DRY_STEP 01:00:00
ROUTING_STEP 0:00:30
ALLOW_PONDING NO
INERTIAL_DAMPING PARTIAL
VARIABLE_STEP 0.75
LENGTHENING_STEP 0
MIN_SURFAREA 0
NORMAL_FLOW_LIMITED BOTH
SKIP_STEADY_STATE NO
FORCE_MAIN_EQUATION H-W
LINK_OFFSETS DEPTH
MIN_SLOPE 0
[EVAPORATION]
;;Type Parameters
;;---------- ----------
CONSTANT 0.0
[RAINGAGES]
;; Rain Time Snow Data
;;Name Type Intrvl Catch Source
;;-------------- --------- ------ ------ ----------
FC-100YR INTENSITY 0:05 1.0 TIMESERIES FC-100YR
[SUBCATCHMENTS]
;; Total Pcnt. Pcnt. Curb Snow
;;Name Raingage Outlet Area Imperv Width Slope Length Pack
;;-------------- ---------------- ---------------- -------- -------- -------- -------- -------- --------
SUBA1 FC-100YR J8 .55 90 288 2 0
SUBA2 FC-100YR J8 .1 7 189 2 0
SUBA3 FC-100YR J1 .43 94 294 2 152
SUBA4 FC-100YR J6 .22 86 120 2 105
SUBA5 FC-100YR J6 .1 81 263 0.5 0
SWMM 5 Page 1
SUBA6 FC-100YR J7 .18 86 67 1 88
SUBA7 FC-100YR PONDA .16 0 74 10 0
SUBB1 FC-100YR J2 .32 50 82 2 0
SUBB2 FC-100YR J2 .27 90 180 2 0
SUBB3 FC-100YR J4 .11 83 25 5 0
SUBB4 FC-100YR J5 .11 84 33 5 131
SUBB5 FC-100YR J3 .24 4 50 2 0
[SUBAREAS]
;;Subcatchment N-Imperv N-Perv S-Imperv S-Perv PctZero RouteTo PctRouted
;;-------------- ---------- ---------- ---------- ---------- ---------- ---------- ----------
SUBA1 .016 .025 .1 .3 1 OUTLET
SUBA2 .016 .025 .1 .3 1 OUTLET
SUBA3 .016 .025 .1 .3 1 OUTLET
SUBA4 .016 .025 .1 .3 1 OUTLET
SUBA5 .016 .025 .1 .3 1 OUTLET
SUBA6 .016 .025 .1 .3 1 OUTLET
SUBA7 .016 .025 .1 .3 1 OUTLET
SUBB1 .016 .025 .1 .3 1 OUTLET
SUBB2 .016 .025 .1 .3 1 OUTLET
SUBB3 .016 .025 .1 .3 1 OUTLET
SUBB4 .016 .025 .1 .3 1 OUTLET
SUBB5 .016 .025 .1 .3 1 OUTLET
[INFILTRATION]
;;Subcatchment MaxRate MinRate Decay DryTime MaxInfil
;;-------------- ---------- ---------- ---------- ---------- ----------
SUBA1 .51 .5 .0018 7 0
SUBA2 .51 .5 .0018 7 0
SUBA3 .51 .5 .0018 7 0
SUBA4 .51 .5 .0018 7 0
SUBA5 .51 .5 .0018 7 0
SUBA6 .51 .5 .0018 7 0
SUBA7 .51 .5 .0018 7 0
SUBB1 .51 .5 .0018 7 0
SUBB2 .51 .5 .0018 7 0
SUBB3 .51 .5 .0018 7 0
SUBB4 .51 .5 .0018 7 0
SUBB5 .51 .5 .0018 7 0
[JUNCTIONS]
;; Invert Max. Init. Surcharge Ponded
;;Name Elev. Depth Depth Depth Area
;;-------------- ---------- ---------- ---------- ---------- ----------
J2 20.5 5 0 0 0
J1 16.5 5 0 0 0
J3 17 5 0 0 0
J4 23 5 0 0 0
J5 26 5 0 0 0
J6 21 5 0 0 0
SWMM 5 Page 2
J7 20 5 0 0 0
J8 23 5 0 0 0
J9 13 5 0 0 0
[OUTFALLS]
;; Invert Outfall Stage/Table Tide
;;Name Elev. Type Time Series Gate
;;-------------- ---------- ---------- ---------------- ----
OUTFALL 13 FREE NO
[STORAGE]
;; Invert Max. Init. Shape Shape Ponded Evap.
;;Name Elev. Depth Depth Curve Params Area Frac. Infiltration Parameters
;;-------------- -------- -------- -------- ---------- -------- -------- -------- -------- -------- -----------------------
PONDB 16.5 6 0 TABULAR PONDB 0 0
PONDA 13 7 0 TABULAR PONDA 0 0
[CONDUITS]
;; Inlet Outlet Manning Inlet Outlet Init. Max.
;;Name Node Node Length N Offset Offset Flow Flow
;;-------------- ---------------- ---------------- ---------- ---------- ---------- ---------- ---------- ----------
2 J2 J3 130 .025 0 0 0 0
3 J5 J4 63 .012 0 0 0 0
4 J4 J3 36 .012 0 0 0 0
5 J3 PONDB 75 .025 0 0 0 0
6 J1 PONDA 260 0.01 0 0 0 0
7 J7 PONDA 40 .012 0 0 0 0
8 J8 J1 67 .012 0 0 0 0
9 J6 PONDA 58 .012 0 0 0 0
10 J9 OUTFALL 100 0.01 0 0 0 0
[OUTLETS]
;; Inlet Outlet Outflow Outlet Qcoeff/ Flap
;;Name Node Node Height Type QTable Qexpon Gate
;;-------------- ---------------- ---------------- ---------- --------------- ---------------- ---------- ----
OUTB PONDB J1 0 TABULAR/DEPTH ORIFICEB NO
OUTA PONDA J9 0 TABULAR/DEPTH ORIFICEA NO
[XSECTIONS]
;;Link Shape Geom1 Geom2 Geom3 Geom4 Barrels
;;-------------- ------------ ---------------- ---------- ---------- ---------- ----------
2 TRAPEZOIDAL 1 2 4 4 1
3 CIRCULAR 1 0 0 0 1
4 CIRCULAR 1 0 0 0 1
5 TRIANGULAR 5 40 0 0 1
6 CIRCULAR 2 0 0 0 1
7 CIRCULAR 1 0 0 0 1
8 CIRCULAR 1 0 0 0 1
9 CIRCULAR 1 0 0 0 1
10 TRAPEZOIDAL 2 2 4 4 1
SWMM 5 Page 3
[TRANSECTS]
NC .012 .012 .012
X1 CURBLINE 5 0 0.0 0.0 0.0 0.0 0.0 0.0
GR .667 -25 .167 0 0 2 .5 2.1 .6 7
[LOSSES]
;;Link Inlet Outlet Average Flap Gate
;;-------------- ---------- ---------- ---------- ----------
[CURVES]
;;Name Type X-Value Y-Value
;;-------------- ---------- ---------- ----------
ORIFICEA Rating 0 0
ORIFICEA 7 .6
ORIFICEB Rating 0 0
ORIFICEB 5.5 .25
PONDA Storage 0 7.7
PONDA 0.2 244.02
PONDA 0.4 803.69
PONDA 0.6 1333.72
PONDA 0.8 1511.37
PONDA 1 1628.45
PONDA 1.2 1749.36
PONDA 1.4 1875.79
PONDA 1.6 2009.54
PONDA 1.8 2154.87
PONDA 2 2237.34
PONDA 2.2 2321.15
PONDA 2.4 2423.05
PONDA 2.6 2538.12
PONDA 2.8 2662.9
PONDA 3 2768.83
PONDA 3.2 2883.13
PONDA 3.4 3008.11
PONDA 3.6 3136.88
PONDA 3.8 3270.11
PONDA 4 3388
PONDA 4.2 3479.57
PONDA 4.4 3564.42
PONDA 4.6 3643.25
PONDA 4.8 3719.24
PONDA 5 3801.9
PONDA 5.2 3885.54
PONDA 5.4 3970.3
PONDA 5.6 4059.01
PONDA 5.8 4150.05
SWMM 5 Page 4
PONDA 6 4261.66
PONDA 6.2 4375.21
PONDA 6.4 4495.27
PONDA 6.6 4653.89
PONDA 6.8 4838.55
PONDA 7 5038.34
PONDA 7.2 5254.04
PONDB Storage 0 0.47
PONDB 0.2 38.37
PONDB 0.4 138.99
PONDB 0.6 283.65
PONDB 0.8 438.86
PONDB 1 604.53
PONDB 1.2 781
PONDB 1.4 968.53
PONDB 1.6 1167.28
PONDB 1.8 1377.14
PONDB 2 1598
PONDB 2.2 1829.44
PONDB 2.4 2069.73
PONDB 2.6 2318.44
PONDB 2.8 2575.87
PONDB 3 2843.14
PONDB 3.2 3120.19
PONDB 3.4 3406.96
PONDB 3.6 3713.59
PONDB 3.8 4074.84
PONDB 4 4461.82
PONDB 4.2 4853.28
PONDB 4.4 5249.01
PONDB 4.6 5648.98
PONDB 4.8 6053.19
PONDB 5 6461.64
PONDB 5.2 6874.34
[TIMESERIES]
;;Name Date Time Value
;;-------------- ---------- ---------- ----------
FC-100YR 0:05 1
FC-100YR 0:10 1.14
FC-100YR 0:15 1.33
FC-100YR 0:20 2.23
FC-100YR 0:25 2.84
FC-100YR 0:30 5.49
FC-100YR 0:35 9.95
FC-100YR 0:40 4.12
FC-100YR 0:45 2.48
FC-100YR 0:50 1.46
FC-100YR 0:55 1.22
SWMM 5 Page 5
FC-100YR 1:00 1.06
FC-100YR 1:05 1
FC-100YR 1:10 .95
FC-100YR 1:15 .91
FC-100YR 1:20 .87
FC-100YR 1:25 .84
FC-100YR 1:30 .81
FC-100YR 1:35 .78
FC-100YR 1:40 .75
FC-100YR 1:45 .73
FC-100YR 1:50 .71
FC-100YR 1:55 .69
FC-100YR 2:00 .67
[REPORT]
INPUT NO
CONTROLS NO
SUBCATCHMENTS ALL
NODES ALL
LINKS ALL
SWMM 5 Page 6
EPA STORM WATER MANAGEMENT MODEL - VERSION 5.0 (Build 5.0.015)
--------------------------------------------------------------
*********************************************************
NOTE: The summary statistics displayed in this report are
based on results found at every computational time step,
not just on results from each reporting time step.
*********************************************************
****************
Analysis Options
****************
Flow Units ............... CFS
Process Models:
Rainfall/Runoff ........ YES
Snowmelt ............... NO
Groundwater ............ NO
Flow Routing ........... YES
Water Quality .......... NO
Infiltration Method ...... HORTON
Flow Routing Method ...... KINWAVE
Starting Date ............ MAY-18-2016 00:00:00
Ending Date .............. MAY-18-2016 06:00:00
Antecedent Dry Days ...... 0.0
Report Time Step ......... 00:15:00
Wet Time Step ............ 00:15:00
Dry Time Step ............ 01:00:00
Routing Time Step ........ 30.00 sec
WARNING 04: minimum elevation drop used for Conduit 10
WARNING 01: wet weather time step reduced to recording interval for Rain Gage FC-100YR
************************** Volume Depth
Runoff Quantity Continuity acre-feet inches
************************** --------- -------
Total Precipitation ...... 0.853 3.669
Evaporation Loss ......... 0.000 0.000
Infiltration Loss ........ 0.097 0.415
Surface Runoff ........... 0.745 3.204
Final Surface Storage .... 0.016 0.069
Continuity Error (%) ..... -0.500
************************** Volume Volume
Flow Routing Continuity acre-feet 10^6 gal
************************** --------- ---------
Dry Weather Inflow ....... 0.000 0.000
Wet Weather Inflow ....... 0.746 0.243
SWMM 5 Page 1
Groundwater Inflow ....... 0.000 0.000
RDII Inflow .............. 0.000 0.000
External Inflow .......... 0.000 0.000
External Outflow ......... 0.231 0.075
Internal Outflow ......... 0.000 0.000
Evaporation Loss ......... 0.000 0.000
Initial Stored Volume .... 0.000 0.000
Final Stored Volume ...... 0.514 0.168
Continuity Error (%) ..... 0.080
********************************
Highest Flow Instability Indexes
********************************
Link 9 (3)
Link 6 (1)
*************************
Routing Time Step Summary
*************************
Minimum Time Step : 30.00 sec
Average Time Step : 30.00 sec
Maximum Time Step : 30.00 sec
Percent in Steady State : 0.00
Average Iterations per Step : 1.25
***************************
Subcatchment Runoff Summary
***************************
----------------------------------------------------------------------------------------------
Total Total Total Total Total Total Peak Runoff
Precip Runon Evap Infil Runoff Runoff Runoff Coeff
Subcatchment in in in in in 10^6 gal CFS
----------------------------------------------------------------------------------------------
SUBA1 3.669 0.000 0.000 0.133 3.462 0.052 5.484 0.944
SUBA2 3.669 0.000 0.000 1.238 2.436 0.007 0.955 0.664
SUBA3 3.669 0.000 0.000 0.079 3.511 0.041 4.299 0.957
SUBA4 3.669 0.000 0.000 0.186 3.412 0.020 2.190 0.930
SUBA5 3.669 0.000 0.000 0.252 3.349 0.009 0.994 0.913
SUBA6 3.669 0.000 0.000 0.187 3.416 0.017 1.780 0.931
SUBA7 3.669 0.000 0.000 1.338 2.355 0.010 1.522 0.642
SUBB1 3.669 0.000 0.000 0.674 2.971 0.026 3.112 0.810
SUBB2 3.669 0.000 0.000 0.133 3.461 0.025 2.694 0.943
SUBB3 3.669 0.000 0.000 0.226 3.377 0.010 1.091 0.920
SUBB4 3.669 0.000 0.000 0.213 3.388 0.010 1.093 0.923
SUBB5 3.669 0.000 0.000 1.309 2.393 0.016 2.168 0.652
--------------------------------------------------------------------------------------------
SWMM 5 Page 2
System 3.669 0.000 0.000 0.415 3.204 0.243 27.382 0.873
******************
Node Depth Summary
******************
---------------------------------------------------------------------
Average Maximum Maximum Time of Max
Depth Depth HGL Occurrence
Node Type Feet Feet Feet days hr:min
---------------------------------------------------------------------
J2 JUNCTION 0.05 0.40 20.90 0 00:40
J1 JUNCTION 0.17 0.78 17.28 0 00:40
J3 JUNCTION 0.15 0.93 17.93 0 00:40
J4 JUNCTION 0.03 0.25 23.25 0 00:40
J5 JUNCTION 0.03 0.24 26.24 0 00:40
J6 JUNCTION 0.04 0.32 21.32 0 00:40
J7 JUNCTION 0.03 0.22 20.22 0 00:40
J8 JUNCTION 0.06 0.52 23.52 0 00:40
J9 JUNCTION 0.50 0.56 13.56 0 02:09
OUTFALL OUTFALL 0.49 0.56 13.56 0 02:15
PONDB STORAGE 4.02 4.64 21.14 0 02:10
PONDA STORAGE 5.55 6.63 19.63 0 02:09
*******************
Node InFlow Summary
*******************
-------------------------------------------------------------------------------------
Maximum Maximum Lateral Total
Lateral Total Time of Max Inflow Inflow
Inflow Inflow Occurrence Volume Volume
Node Type CFS CFS days hr:min 10^6 gal 10^6 gal
-------------------------------------------------------------------------------------
J2 JUNCTION 5.81 5.81 0 00:40 0.051 0.051
J1 JUNCTION 4.30 10.85 0 00:40 0.041 0.129
J3 JUNCTION 2.17 9.93 0 00:40 0.016 0.087
J4 JUNCTION 1.09 2.17 0 00:40 0.010 0.020
J5 JUNCTION 1.09 1.09 0 00:40 0.010 0.010
J6 JUNCTION 3.18 3.18 0 00:40 0.030 0.030
J7 JUNCTION 1.78 1.78 0 00:40 0.017 0.017
J8 JUNCTION 6.44 6.44 0 00:40 0.058 0.058
J9 JUNCTION 0.00 0.57 0 02:09 0.000 0.077
OUTFALL OUTFALL 0.00 0.57 0 02:15 0.000 0.075
PONDB STORAGE 0.00 9.90 0 00:40 0.000 0.087
PONDA STORAGE 1.52 16.99 0 00:40 0.010 0.185
SWMM 5 Page 3
**********************
Node Surcharge Summary
**********************
Surcharging occurs when water rises above the top of the highest conduit.
---------------------------------------------------------------------
Max. Height Min. Depth
Hours Above Crown Below Rim
Node Type Surcharged Feet Feet
---------------------------------------------------------------------
PONDA STORAGE 5.48 4.631 0.369
*********************
Node Flooding Summary
*********************
No nodes were flooded.
**********************
Storage Volume Summary
**********************
--------------------------------------------------------------------------------------
Average Avg Maximum Max Time of Max Maximum
Volume Pcnt Volume Pcnt Occurrence Outflow
Storage Unit 1000 ft3 Full 1000 ft3 Full days hr:min CFS
--------------------------------------------------------------------------------------
PONDB 8.124 40 10.392 52 0 02:10 0.21
PONDA 14.900 72 18.881 91 0 02:09 0.57
***********************
Outfall Loading Summary
***********************
-----------------------------------------------------------
Flow Avg. Max. Total
Freq. Flow Flow Volume
Outfall Node Pcnt. CFS CFS 10^6 gal
-----------------------------------------------------------
OUTFALL 95.28 0.49 0.57 0.075
-----------------------------------------------------------
System 95.28 0.49 0.57 0.075
********************
Link Flow Summary
********************
SWMM 5 Page 4
-----------------------------------------------------------------------------
Maximum Time of Max Maximum Max/ Max/
|Flow| Occurrence Velocity Full Full
Link Type CFS days hr:min ft/sec Flow Depth
-----------------------------------------------------------------------------
2 CONDUIT 5.70 0 00:40 4.12 0.14 0.39
3 CONDUIT 1.08 0 00:40 7.38 0.13 0.24
4 CONDUIT 2.16 0 00:40 14.13 0.14 0.25
5 CONDUIT 9.90 0 00:40 2.88 0.01 0.19
6 CONDUIT 10.65 0 00:40 9.70 0.31 0.38
7 CONDUIT 1.77 0 00:40 13.55 0.11 0.22
8 CONDUIT 6.41 0 00:40 15.54 0.53 0.52
9 CONDUIT 3.17 0 00:40 14.69 0.22 0.32
10 CONDUIT 0.57 0 02:15 0.24 0.06 0.28
OUTB DUMMY 0.21 0 02:10
OUTA DUMMY 0.57 0 02:09
*************************
Conduit Surcharge Summary
*************************
No conduits were surcharged.
Analysis begun on: Wed May 18 12:10:52 2016
Analysis ended on: Wed May 18 12:10:52 2016
Total elapsed time: < 1 sec
SWMM 5 Page 5
APPENDIX D
EROSION CONTROL REPORT
The Overlook
Preliminary Erosion Control Report
A comprehensive Erosion and Sediment Control Plan (along with associated details) will be 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 E
LID EXHIBIT
Project: The Overlook
Calculations By:
Date:
L1 A4 9,533 86% 8,182
A5 4,511 81% 3,676
Total L1 14,044 84% 11,857 332 355
L2 A1 23,900 90% 21,510
A2 4,337 7% 303
Total L2 28,237 77% 21,813 584 584
L3 A3 18,904 94% 17,772
Total L3 18,904 94% 17,772 551 578
L4 B1 14,054 50% 7,070
B2 11,676 90% 10,508
Total L4 25,730 68% 17,578 457 555
Total Treated 86,915 79% 69,020 1,924 2,072
A6 7,798 86% 6,697
A7 6,773 0% 0
B3 4,763 83% 3,957
B4 4,834 84% 4,041
B5 10,551 4% 431
UD2 1,788 10% 183
UD3 4,216 13% 537
UD4 13,275 66% 8,753
UD1 1,133 0% 0
UD5 1,241 0% 0
Total Proposed
Untreated
56,372 44% 24,599
H1 9,932 86% 8,542
Total Existing
Untreated
9,932 86% 8,542
143,287
8,542
93,620
85,078
63,808
1,924
2,072
69,020
69,020
81%
PROPOSED LID COMPUTATIONS
S. Thomas
May 31, 2016
LID BASIN NODE Sub-Basin(s)
Area, A
(sf)
Percent
Impervious
Impervious Area,
A
(sf)
UD Rain Garden
Flat WQCV
Required (Cf)
LID TREATMENT SUMMARY
PROPOSED LID UNTREATED AREA
Total Site Area (sf)
PROPOSED LID TREATED AREA
APPENDIX F
REFERENCES
MAP POCKET
DR1 – OVERALL DRAINAGE EXHIBIT
HDR1
CALL UTILITY NOTIFICATION CENTER OF
COLORADO
Know what's
R
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
200 South College Avenue, Suite 010
Fort Collins, Colorado 80524
N O R T H E RN
PHONE: 970.221.4158 FAX: 970.221.4159
www.northernengineering.com
( IN FEET )
0
1 INCH = 30 FEET
30 30 60 90
KEYMAP
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 "PRELIMINARY DRAINAGE AND EROSION CONTROL REPORT FOR
THE OVERLOOK BY NORTHERN ENGINEERING, DATED MARCH 30, 2016 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
DRAINAGE SUMMARY TABLE
DESIGN
POINT
BASIN
ID
TOTAL
AREA
(acres)
C2 C100 2-yr
DR1
CALL UTILITY NOTIFICATION CENTER OF
COLORADO
Know what's
R
CityDate Engineer
Date
Date
Date
Date
Stormwater Utility
Parks & Recreation
Traffic Engineer
Date
Water & Wastewater Utility
City of Fort Collins, Colorado
UTILITY PLAN APPROVAL
Environmental Planner
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
200 South College Avenue, Suite 010
Fort Collins, Colorado 80524
N O R T H E RN
PHONE: 970.221.4158 FAX: 970.221.4159
www.northernengineering.com
( IN FEET )
0
1 INCH = 30 FEET
30 30 60 90
KEYMAP
DRAINAGE SUMMARY TABLE
DESIGN
POINT
BASIN
ID
TOTAL
AREA
(acres)
C2 C100 2-yr
Tc
(min)
100-yr
Tc
(min)
Q2
(cfs)
Q100
(cfs)
1 A1 0.55 0.95 1.00 5.0 5.0 1.49 5.46
1 A2 0.10 0.30 0.38 15.6 14.1 0.06 0.25
2 A3 0.43 0.92 1.00 5.0 5.0 1.14 4.32
3 A4 0.22 0.87 1.00 5.0 5.0 0.54 2.18
4 A5 0.10 0.88 1.00 5.0 5.0 0.26 1.03
5 A6 0.18 0.86 1.00 5.0 5.0 0.44 1.78
6 A7 0.16 0.25 0.31 5.0 5.0 0.11 0.48
7 B1 0.32 0.61 0.77 7.2 5.0 0.50 2.46
8 B2 0.27 0.95 1.00 5.0 5.0 0.73 2.67
9 B3 0.11 0.86 1.00 5.0 5.0 0.27 1.09
10 B4 0.11 0.85 1.00 5.0 5.0 0.27 1.10
11 B5 0.24 0.28 0.35 16.1 14.7 0.12 0.56
13 UD2 0.04 0.33 0.41 11.7 11.0 0.03 0.13
13 UD3 0.10 0.35 0.44 10.8 10.1 0.07 0.33
13 UD4 0.30 0.73 0.91 5.0 5.0 0.63 2.76
12 UD1 0.03 0.25 0.31 5.0 5.0 0.02 0.08
12 UD5 0.03 0.25 0.31 5.0 5.0 0.02 0.09
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 "PRELIMINARY DRAINAGE AND EROSION CONTROL REPORT FOR
THE OVERLOOK BY NORTHERN ENGINEERING, DATED June 1, 2016 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
Detention Pond Summary | Proposed Condition
Pond 100-yr Volume
(ac-ft)
100-yr WSEL WQCV
(ft3)
WQCV WSEL Max Release
(cfs)
A 0.45 5019.97 617 5014.02 0.57
B 0.25 5021.32 458 5017.91 0.21
Tc
(min)
100-yr
Tc
(min)
Q2
(cfs)
Q100
(cfs)
1 H1 0.23 0.86 1.00 5.1 5.0 0.56 2.27
2 H2 3.04 0.25 0.31 27.0 25.0 1.05 4.78
LID BASIN NODE Sub-Basin(s)
Area, A
(sf)
Percent
Impervious
Impervious Area,
A
(sf)
Rain Garden
WQCV Provided
(cf)
Total Existing Impervious Area (sf)
Total Proposed Impervious Area (sf)
Total Net Proposed Impervious Area (sf)
Total Treated Impervious Area (sf)
Percent Impervious Treated by LID
measures
75% Required Minimum Area to be
Treated by LID measures (sf)
Rain Garden Treatment
Total Volume Required (cf)
Total Volume Provided (cf)
Area treated by Rain Gardens (sf)
Project Location:
Calculations By:
Required Volume Water Surface Elevation (WSE)
Project Number:
Project Location:
Calculations By:
Required Volume Water Surface Elevation (WSE)
Q10
(cfs)
Intensity,
i100
(in/hr)
Sub-Basin(s)
S. Thomas
Rainfall Intensity taken from the Fort Collins Stormwater Criteria Manual (FCSCM), Tables RA-7 and RA-8
Q = C f ( C )( i )( A )
5/31/2016 2:22 PM D:\Projects\1174-001\Drainage\Hydrology\1174-001_Proposed_Rational_Calcs.xlsx\Runoff
5 A6 No 0.86 0.86 1.00 95 4.21% 2.7 2.7 1.1 110 1.73% 2.63 0.7 5.0 5.0 5.0
6 A7 No 0.25 0.25 0.31 N/A N/A N/A N/A N/A N/A N/A 5.0 5.0 5.0
TOTAL BASIN A TOTAL BASIN A 15.6 15.6 14.1
7 B1 No 0.61 0.61 0.77 202 5.94% 7.2 7.2 4.9 N/A N/A N/A 7.2 7.2 5.0
8 B2 No 0.95 0.95 1.00 70 17.14% 0.9 0.9 0.6 N/A N/A N/A 5.0 5.0 5.0
9 B3 No 0.86 0.86 1.00 174 5.40% 3.3 3.3 1.4 16 3.13% 3.54 0.1 5.0 5.0 5.0
10 B4 No 0.85 0.85 1.00 138 5.22% 3.1 3.1 1.3 N/A N/A N/A 5.0 5.0 5.0
11 B5 No 0.28 0.28 0.35 179 2.07% 16.1 16.1 14.7 N/A N/A N/A 16.1 16.1 14.7
TOTAL BASIN B TOTAL BASIN B 16.1 16.1 14.7
13 UD2 No 0.33 0.33 0.41 47 4.26% 6.1 6.1 5.4 965 2.07% 2.88 5.6 11.7 11.7 11.0
13 UD3 No 0.35 0.35 0.44 47 4.26% 5.9 5.9 5.2 882 2.27% 3.01 4.9 10.8 10.8 10.1
13 UD4 No 0.73 0.73 0.91 17 4.71% 1.7 1.7 0.9 440 1.93% 2.78 2.6 5.0 5.0 5.0
TOTAL BASIN UD2-UD4 TOTAL BASIN UD2-UD4
11.7 11.7 11.0
12 UD1 No 0.25 0.25 0.31 21 7.62% 3.7 3.7 3.4 N/A N/A N/A 5.0 5.0 5.0
12 UD5 No 0.25 0.25 0.31 16 15.00% 2.6 2.6 2.4 N/A N/A N/A 5.0 5.0 5.0
TOTAL SITE TOTAL SITE 16.1 16.1 14.7
* Time of Concentrations are calculated for the entire basin and used for both the Impervious and Pervious portions of the basins.
PROPOSED TIME OF CONCENTRATION COMPUTATIONS
S. Thomas
May 31, 2016
Design
Point
Sub-Basin
Overland Flow Gutter/Pipe Flow Time of Concentration
(Equation RO-4)
( )
3
1
1 . 87 1 . 1 *
S
Ti C Cf L
-
=
5/31/2016 2:21 PM D:\Projects\1174-001\Drainage\Hydrology\1174-001_Proposed_Rational_Calcs.xlsx\Tc
A2 0.10 0.00 0.01 0.00 0.00 Clayey | Average 2% to 7% 0.092 0.30 0.30 0.38 7%
A3 0.43 0.33 0.08 0.00 0.00 Clayey | Average 2% to 7% 0.018 0.92 0.92 1.00 94%
A4 0.22 0.14 0.05 0.00 0.00 Clayey | Average 2% to 7% 0.026 0.87 0.87 1.00 86%
A5 0.10 0.00 0.09 0.00 0.00 Clayey | Average 2% to 7% 0.010 0.88 0.88 1.00 81%
A6 0.18 0.13 0.03 0.00 0.00 Clayey | Average 2% to 7% 0.023 0.86 0.86 1.00 86%
A7 0.16 0.00 0.00 0.00 0.00 Clayey | Average 2% to 7% 0.155 0.25 0.25 0.31 0%
TOTAL BASIN A 1.74 0.61 0.27 0.00 0.54 Clayey | Average 2% to 7% 0.324 0.82 0.82 1.00 77%
B1 0.32 0.12 0.05 0.00 0.00 Clayey | Average 2% to 7% 0.156 0.61 0.61 0.77 50%
B2 0.27 0.00 0.00 0.00 0.27 Clayey | Average 2% to 7% 0.000 0.95 0.95 1.00 90%
B3 0.11 0.04 0.05 0.00 0.00 Clayey | Average 2% to 7% 0.013 0.86 0.86 1.00 83%
B4 0.11 0.07 0.03 0.00 0.00 Clayey | Average 2% to 7% 0.015 0.85 0.85 1.00 84%
B5 0.24 0.00 0.01 0.00 0.00 Clayey | Average 2% to 7% 0.231 0.28 0.28 0.35 4%
TOTAL BASIN B 1.05 0.23 0.14 0.00 0.27 Clayey | Average 2% to 7% 0.415 0.67 0.67 0.84 57%
UD2 0.04 0.00 0.00 0.00 0.00 Clayey | Average 2% to 7% 0.036 0.33 0.33 0.41 10%
UD3 0.10 0.00 0.01 0.00 0.00 Clayey | Average 2% to 7% 0.083 0.35 0.35 0.44 13%
UD4 0.30 0.14 0.07 0.00 0.00 Clayey | Average 2% to 7% 0.097 0.73 0.73 0.91 66%
TOTAL BASIN UD2-UD4 0.44 0.14 0.09 0.00 0.00 Clayey | Average 2% to 7% 0.216 0.61 0.61 0.76 49%
UD1 0.03 0.00 0.00 0.00 0.00 Clayey | Average 2% to 7% 0.026 0.25 0.25 0.31 0%
UD5 0.03 0.00 0.00 0.00 0.00 Clayey | Average 2% to 7% 0.028 0.25 0.25 0.31 0%
TOTAL SITE 3.29 0.97 0.49 0.00 0.81 Clayey | Average 2% to 7% 1.010 0.74 0.74 0.92 65%
Composite Runoff Coefficient with Adjustment
PROPOSED COMPOSITE % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS
5/31/2016 2:20 PM D:\Projects\1174-001\Drainage\Hydrology\1174-001_Proposed_Rational_Calcs.xlsx\Composite C
March 29, 2016
Design
Point
Sub-Basin
Overland Flow Gutter/Pipe Flow Time of Concentration
(Equation RO-4)
( )
3
1
1 . 87 1 . 1 *
S
Ti C Cf L
-
=
3/29/2016 12:08 PM D:\Projects\1174-001\Drainage\Hydrology\1174-001_Existing_Rational_Calcs.xlsx\Tc
H2 3.04 0.00 0.00 0.00 0.00 Clayey | Average 2% to 7% 3.038 0.25 0.25 0.31 0%
TOTAL SITE 3.27 0.17 0.03 0.00 0.00 Clayey | Average 2% to 7% 3.067 0.29 0.29 0.37 6%
1. Table RO-11 | Rational Method Runoff Coefficients for Composite Analysis
Composite Runoff Coefficient with Adjustment
EXISTING COMPOSITE % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS
3/29/2016 12:08 PM D:\Projects\1174-001\Drainage\Hydrology\1174-001_Existing_Rational_Calcs.xlsx\Composite C