HomeMy WebLinkAboutLANDMARK APARTMENTS EXPANSION - PDP - PDP160013 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTPRELIMINARY DRAINAGE AND
EROSION CONTROL REPORT
April 5, 2016
Landmark Apartments Expansion
Fort Collins, Colorado
Prepared for:
Summit Management Services
730 W. Market Street
Akron, Ohio 44303
330-535-7027
Prepared by:
301 N. Howes Street, Suite 100
Fort Collins, Colorado 80521
Phone: 970.221.4158
www.northernengineering.com
Project Number: 1257-001
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
Landmark Apartments Expansion
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
Landmark Apartments Expansion 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
Landmark Apartments Expansion
Preliminary Drainage Report
TABLE OF CONTENTS
I. GENERAL LOCATION AND DESCRIPTION ................................................................... 1
A. Location ............................................................................................................................................. 1
B. Description of Property ..................................................................................................................... 1
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 ............................................................................ 5
D. Hydrological Criteria ......................................................................................................................... 6
E. Hydraulic Criteria .............................................................................................................................. 6
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 ....................................................................................................................... 10
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
Landmark Apartments Expansion
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
Landmark Apartments Expansion
Preliminary Drainage Report 1
I. GENERAL LOCATION AND DESCRIPTION
A. Location
1. Vicinity Map
2. Located in the northwest quarter of Section 23, Township 7 North, Range 69 West of
the 6th Prime Meridian, City of Fort Collins, County of Larimer, State of Colorado. The
site includes Lots 1, 2, 3, 4 and Tracts A, D, E, and F of Young’s Creek Subdivision.
3. Bounded to the north by Prospect Road, to the west by the existing Landmark
Apartments development, to the south by vacant land, and to the east by a single-
family development.
4. Offsite flows from the existing single-family development are expected, but should be
relatively small due to the low imperviousness. Off-site flows will be passed through
the site undetained.
5. This site was originally platted as Young’s Creek.
B. Description of Property
1. The site is approximately 3.67 acres.
Landmark Apartments Expansion
Preliminary Drainage Report 2
Figure 1 – Aerial Photograph
2. The existing site is comprised of vacant land with natural grasses and vegetation. The
Canal Importation Channel bisects the site from the western boundary to the south
boundary of the site.
3. The majority of the site slopes to the south, while a portion of the site, south of the
channel, slopes to the north.
4. A report by Soilogic, Inc. dated February 24, 2016 lists the soils for the area as
consisting of lean clay with varying amounts of silt and sand. These soils are classified
as Hydrologic Soil Group C and have a low infiltration rate.
5. The proposed project site plan is composed of 5 multi-family residential buildings. This
site will employ many water quality features and runoff reduction facilities including rain
gardens, landscape buffers, and water quality ponds.
Landmark Apartments Expansion
Preliminary Drainage Report 3
Figure 2– Proposed Site Plan
6. No existing irrigation facilities are known at this time.
7. The proposed project is not requesting a change in the land use.
C. Floodplain
1. The subject property is bisected by both a FEMA and City regulatory floodplain.
Development within the floodplain will be limited and subject to regulations set forth
by the City and FEMA.
Landmark Apartments Expansion
Preliminary Drainage Report 4
Figure 3 – Existing Floodplains
II. DRAINAGE BASINS AND SUB-BASINS
A. Major Basin Description
1. The Landmark Apartments Expansion project is located within the Canal Importation
Basin, which is located south of Laporte Avenue, north of Drake Road, west of Shields
Street, and East of the foothills.
B. Sub-Basin Description
1. The northern portion of the site drains south to the Canal Importation Channel. The
southern portion of the site drains north to the Canal Importation Channel.
2. Due to proximity to the Canal Importation Channel and location within the Canal
Importation Drainage Basin, no stormwater detention is proposed on this site. The
flow volumes and times of concentration for on-site basins are very small compared to
the regional flow through the Canal Importation Channel. The peak runoff from this
site will be conveyed through the channel prior to the peak flows from the major basin
upstream of the site.
Landmark Apartments Expansion
Preliminary Drainage Report 5
III. DRAINAGE DESIGN CRITERIA
A. Regulations
This project seeks provisions outside of the FCSCM to waive the detention requirement
within the Canal Importation Basin.
B. Four Step Process
The overall stormwater management strategy employed with Landmark Apartments
Expansion 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).
Utilizing large vegetated open areas throughout the site to reduce the overall
impervious area and to minimize directly connected impervious area (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 majority of stormwater runoff from the site will ultimately be
intercepted and treated in proposed water quality ponds.
Step 3 – Stabilize Drainageways
Buried riprap pads will be installed at the stormwater outfalls into the Canal Importation
Channel. These pads will fortify the outfall and reduce any erosion within the channel.
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 vegetated open areas 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. No previous studies were utilized with this project.
2. Low-Impact Development and water quality facilities make up the majority of this
drainage concept and report.
3. This project will be subject to the design guidelines as set forth by the Fort Collins
Stormwater Criteria Manual (FCSCM) and the Urban Drainage and Flood Control
District Criteria Manual.
Landmark Apartments Expansion
Preliminary Drainage Report 6
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 Stormwater Management Model (SWMM) modeling was utilized to model peak
flow in the channel before and after development of this site.
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. The northern portion of the site drains south to the Canal Importation Channel. The
southern portion of the site drains north to the Canal Importation Channel.
2. All drainage facilities proposed with Landmark Apartments Expansion 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 bisected by both a FEMA and City
regulatory floodplain. Development within the floodplain will be limited and subject
to regulations set forth by the City and FEMA.
4. The Landmark Apartments Expansion project does not propose to modify the Canal
Importation Channel within the floodway limits. Limited grading within the flood
fringe is expected to accommodate the trail connection and grading to the buildings.
No grading is proposed in the floodway.
F. Floodplain Regulations Compliance
1. As stated previously, the subject property is bisected by both a FEMA and City
regulatory floodplain. Development within the floodplain will be limited and subject
to regulations set forth by the City and FEMA.
G. Modifications of Criteria
1. This project seeks provisions outside of the FCSCM to waive the detention
requirement within the Canal Importation Basin.
IV. DRAINAGE FACILITY DESIGN
A. General Concept
1. The main objectives of the Landmark Apartments Expansion drainage design are to
Landmark Apartments Expansion
Preliminary Drainage Report 7
provide water quality for stormwater runoff and safely convey stormwater runoff to the
Canal.
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. The Landmark Apartments Expansion project is divided into three (4) major drainage
basins, designated as Basins A, B, UD and OS. Basin A is on-site and located north
of the canal. Basin B is on-site and located south of the canal. Basins designated
UD are on-site basins that flow directly to the canal by-passing any water quality
ponds. Basins designated OS are off-site basins that flow onto the subject property.
Basin A
Basin A consists of proposed multi-family apartments, sidewalk, landscaped areas and
parking. Runoff from roofs will be conveyed through landscaped areas to sidewalk
chases and/or rain gardens. Sidewalk chases, curb cuts, and swales are the main
mode of water conveyance around the site. Basins A2, A3, A5, and A6 are conveyed
to a rain gardens sized for the respective basin. Basin A1 flows directly to the water
quality pond. Basin A4 is mostly landscaping and will not be subject to LID
treatment. Runoff from all basins, other than Basin A3, will be captured and treated
within the Water Quality Pond. The rain garden is Basin A3 is sized for water quality
utilizing the Urban Drainage BMP spreadsheets.
Runoff produced during a 2-year event will ultimately be captured in inlets and
conveyed to the canal via storm sewer.
Runoff produced during a 100-year event, up to the limits of inlet and storm sewer
capacities, will be captured by inlets and conveyed to the canal by storm sewer.
Additional flow above the inlet/sewer capacities will overtop sidewalks and berms at
rain garden locations and will flow directly into the canal.
Basin B
Basin B consists of proposed multi-family apartments, sidewalk, landscaped areas and
parking. Runoff is captured by a curb cut and conveyed to the rain garden. The rain
garden in Basin B is sized for water quality utilizing the Urban Drainage BMP
Spreadsheet.
Runoff produced during a 2-year event will ultimately be treated for water quality and
release via storm sewer to the canal.
Runoff produced during a 100-year event, up to the limits of inlet and storm sewer
capacities, will be captured by inlets and conveyed to the canal by storm sewer.
Additional flow above the inlet/sewer capacities will overtop sidewalks and berms at
the rain garden location and will flow directly into the canal.
Basin UD
Basin UD consists of proposed multi-family apartments, concrete trail, and landscaped
areas. Runoff during both 2-year and 100-year events will flow directly to the canal
over landscaped areas. These landscape buffers will provide some water quality
treatment, but these areas have not been included in the LID calculations. The
majority of the UD basins consist of landscaping; therefore, water quality from these
basins is not considered a concern.
Landmark Apartments Expansion
Preliminary Drainage Report 8
Basin OS
Basin OS consists of proposed parking, proposed sidewalks, existing single family lots
and existing multifamily development.
Runoff from Basins OS-1, OS-2 and OS-3 will be passed through Basin A safely to the
canal without detention or water quality treatment. Both rain gardens and the water
quality pond are not sized to treat these areas.
Runoff from Basin OS-4 will continue through the existing parking lot to the sidewalk
chase in Basin A3. This chase will be sized to convey the 2-yr flows from Basin OS-4
along with the 2-yr flows from Basin A3. The rain garden is not sized to
accommodate runoff from Basin OS-4; therefore, flows from Basin OS-4 will safely
bypass to the canal.
Runoff from Basin OS-5 and OS-6 will continue as historically to the drainage pan in
Hobbit Street, and be conveyed to the canal via existing swale. The existing swale will
provide a certain amount of LID and water quality treatment. This additional
treatment has not been included in the LID treatment calculations.
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. This project seeks provisions outside of the FCSCM to waive the detention
requirement within the Canal Importation Basin.
2. Other than the detention requirement, drainage design proposed with the Landmark
Apartments Expansion project complies with the City of Fort Collins’ Stormwater
Criteria Manual.
3. The subject property is bisected by both a FEMA and City regulatory floodplain.
Development within the floodplain will be limited and subject to regulations set forth
by the City and FEMA.
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 75% of total impervious areas as being treated
through an LID treatment.
B. Drainage Concept
1. All drainage facilities proposed with Landmark Apartments Expansion 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.
2. The drainage design proposed with this project will effectively limit any potential
Landmark Apartments Expansion
Preliminary Drainage Report 9
damage or erosion associated with its stormwater runoff. All existing downstream
drainage facilities are expected to not be impacted negatively by this development
3. The proposed development will not have any impact on the Master Drainage Plan
recommendations for the Canal Importation Basin.
4. The drainage design is anticipated to be very conservative. We have omitted any
runoff reduction that will manifest due to infiltration from rain gardens and landscape
buffers. This is currently unable to be calculated with available soils data.
Landmark Apartments Expansion
Preliminary 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. Geotechnical Subsurface Exploration Report Landmark Apartments Expansion Southeast of
West Prospect Road and South Shields Street, Fort Collins, Colorado, February 24, 2016,
Soilogic, Inc. (Soilogic Project No. 16-1024).
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.
APPENDIX A
HYDROLOGIC COMPUTATIONS
Landmark Apartments
CHARACTER OF SURFACE1:
Runoff
Coefficient
Percentage
Impervious Project: Landmark Apartments
Streets, Parking Lots, Roofs, Alleys, and Drives: Calculations By: S. Thomas
Asphalt ……....……………...……….....…...……………….………………………………………………………….0.95 . 100% Date: April 4, 2016
Concrete …….......……………….….……….………………..….…………………………………………………….0.95 . 90%
Gravel (packed) ……….…………………….….…………………………..………………………………………….0.50 . 40%
Roofs …….…….………………..……………….……………………………………………………………………… 0.95 90%
Pavers…………………………...………………..……………………………………………………………………… 0.40 40%
Land Use Calculations By: S. Thomas
Existing Multi-family ……....……………...……….....…...……………….…………………………………………… 0.55 50% Date: April 4, 2016
Existing Single Family …….......……………….….……….………………..….……………………………………… 0.30 30%
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% 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
Roofs
(ac)
Area of
Single Family
(ac)
Area of
Multi Family
(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
Landmark Apartments Expansion
Overland Flow, Time of Concentration:
Landmark Apartments
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
Tc
(min)
Landmark Apartments Expansion
Rational Method Equation: Project: Landmark Apartments
Calculations By:
Date:
Rainfall Intensity:
7 North Historic Basin 2.68 5 5 5 0.25 0.25 0.31 2.85 4.87 9.95 1.91 3.26 8.32
7 South Historic Basin 0.53 5 5 5 0.25 0.25 0.31 2.85 4.87 9.95 0.38 0.65 1.66
7 Total Existing Site 3.21 5 5 5 0.25 0.25 0.31 2.85 4.87 9.95 2.29 3.91 9.98
1 A1 0.68 8 8 6 0.58 0.58 0.72 2.46 4.21 9.63 0.97 1.65 4.72
2 A2 0.46 8 8 6 0.70 0.70 0.87 2.40 4.10 9.63 0.77 1.31 3.86
3 A3 0.47 5 5 5 0.83 0.83 1.00 2.85 4.87 9.95 1.12 1.91 4.70
4 A4 0.14 5 5 5 0.25 0.25 0.31 2.85 4.87 9.95 0.10 0.17 0.44
5 A5 0.18 5 5 5 0.85 0.85 1.00 2.85 4.87 9.95 0.44 0.75 1.81
6 A6 0.47 5 5 5 0.72 0.72 0.91 2.85 4.87 9.95 0.97 1.65 4.22
7 UD-3 0.27 5 5 5 0.44 0.44 0.54 2.85 4.87 9.95 0.34 0.57 1.47
7 North Proposed Basin 2.67 10 10 7 0.66 0.66 0.82 2.21 3.78 8.80 3.87 6.62 19.27
7 B1 0.05 11 11 9 0.35 0.35 0.44 2.17 3.71 8.03 0.04 0.06 0.17
8 B2 0.26 5 5 5 0.89 0.89 1.00 2.85 4.87 9.95 0.64 1.10 2.54
7 UD-1 0.14 5 5 5 0.63 0.63 0.79 2.85 4.87 9.95 0.26 0.44 1.12
7 UD-2 0.09 7 7 6 0.29 0.29 0.37 2.60 4.44 9.31 0.07 0.12 0.31
7 South Proposed Basin 0.53 7 7 5 0.67 0.67 0.84 2.60 4.44 9.95 0.93 1.59 4.46
4 OS-1 0.77 14 14 12 0.30 0.30 0.38 1.95 3.34 7.16 0.45 0.77 2.06
2 OS-2 0.24 13 13 12 0.30 0.30 0.38 1.98 3.39 7.16 0.14 0.24 0.65
1 OS-3 1.05 12 12 11 0.30 0.30 0.38 2.05 3.50 7.42 0.64 1.10 2.92
3 OS-4 1.21 10 10 9 0.46 0.46 0.58 2.21 3.78 8.21 1.24 2.13 5.77
9 OS-5 0.16 5 5 5 0.83 0.83 1.00 2.85 4.87 9.95 0.39 0.67 1.64
10 OS-6 0.10 5 5 5 0.87 0.87 1.00 2.85 4.87 9.95 0.25 0.42 0.98
7 OS-7 0.51 5 5 5 0.29 0.29 0.37 2.85 4.87 9.95 0.43 0.74 1.88
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,
Q10
(cfs)
Intensity,
i100
(in/hr)
Sub-Basin(s)
APPENDIX B
HYDRAULIC COMPUTATIONS
B.1 WATER QUALITY POND SIZING
B.2 STORM SEWER (NOT INCLUDED)
B.3 INLET (NOT INCLUDED)
APPENDIX B.1
WATER QUALITY POND
Landmark Apartments Expansion
1257-001
Fort Collins, Colorado
S. Thomas Date: 4/4/2016
Pond No.: Water Quality Pond
A
WQCV
0.82 Approx. WQCV 1611 ft3
Area (A)= 1.93 acres Quantity Detention 0 ft3 (per SWMM)
Max Release Rate = n/a cfs Total Volume 1611 ft3
Total Volume 0.04 ac-ft
Detention Pond Calculation | SWMM Method
Project Number:
Project Location:
Calculations By:
Input Variables Results
Design Point
Design Storm Required Detention Volume
Developed "C" =
4/4/2016 2:19 PM D:\Projects\1257-001\Drainage\Detention\1257-001__Water Quality Pond.xlsm\FAA_CoFC idf_Pond 1
1257-001
Fort Collins, CO
S. Thomas Date: 4/4/2016
Pond No.: Water Quality
1
n/a
0.04 acft 5011.41 ft.
Design Storm WQCV
Required Volume= 1611 ft3 5011.43 ft.
Contour
Elevation (Y-
values)
Contour Area Depth
Column Not
Used
Incremental
Volume
Total Volume Total Volume
ft2 ft. ft3 ft3 ft3 acre-feet
5,010.40 108.43 0.00 0 0 0 0
5,010.60 629.03 0.20 67 67 0.00
5,010.80 1,338.23 0.20 192 259 0.01
5,011.00 2,092.49 0.20 340 599 0.01
5,011.20 2,489.44 0.20 457 1056 0.02
5,011.40 2,707.25 0.20 519 1575 0.04
5,011.60 2,899.67 0.20 560 2135 0.05
5,011.80 3,098.65 0.20 599 2734 0.06
Design Point
Design Storm
Require Volume=
Stage - Storage Calculation
Project Number:
Project Location:
Calculations By:
Required Volume Water Surface Elevation (WSE)
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1. Basin Storage Volume
A) Effective Imperviousness of Tributary Area, Ia Ia = 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* i3 - 1.19 * i2 + 0.78 * i)
D) Contributing Watershed Area (including rain garden area) Area = 20,570 sq ft
E) Water Quality Capture Volume (WQCV) Design Volume VWQCV = 426 cu ft
Vol = (WQCV / 12) * Area
F) For Watersheds Outside of the Denver Region, Depth of d6 = in
Average Runoff Producing Storm
G) For Watersheds Outside of the Denver Region, VWQCV OTHER = 0.0 cu ft
Water Quality Capture Volume (WQCV) Design Volume
H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER = cu ft
(Only if a different WQCV Design Volume is desired)
2. Basin Geometry
A) WQCV Depth (12-inch maximum) DWQCV = 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 = 284 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 = 18.0 ft
Volume to the Center of the Orifice
ii) Volume to Drain in 12 Hours Vol12 = 426 cu ft
iii) Orifice Diameter, 3/8" Minimum DO = 0.30 in MINIMUM DIAMETER = 3/8"
Design Procedure Form: Rain Garden (RG)
Stephanie Thomas
Northern Engineering
April 4, 2016
Landmark Apartments Expansion
Basin A3
Choose One
Choose One
18" Rain Garden Growing Media
Other (Explain):
YES
NO
UD-BMP_v3.03 Rain Gardens A.xlsm, RG 4/4/2016, 2:11 PM
Sheet 2 of 2
Designer:
Company:
Date:
Project:
Location:
5. Impermeable Geomembrane Liner and Geotextile Separator Fabric
A) Is an impermeable liner provided due to proximity
of structures or groundwater contamination?
6. Inlet / Outlet Control
A) Inlet Control
7. Vegetation
8. Irrigation
A) Will the rain garden be irrigated?
Notes:
Design Procedure Form: Rain Garden (RG)
Stephanie Thomas
Northern Engineering
April 4, 2016
Landmark Apartments Expansion
Basin A3
Choose One
Choose One
Choose One
Sheet Flow- No Energy Dissipation Required
Concentrated Flow- Energy Dissipation Provided
Plantings
Seed (Plan for frequent weed control)
Sand Grown or Other High Infiltration Sod
Choose One
YES
NO
YES
NO
UD-BMP_v3.03 Rain Gardens A.xlsm, RG 4/4/2016, 2:11 PM
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1. Basin Storage Volume
A) Effective Imperviousness of Tributary Area, Ia Ia = 88.0 %
(100% if all paved and roofed areas upstream of rain garden)
B) Tributary Area's Imperviousness Ratio (i = Ia/100) i = 0.880
C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.31 watershed inches
(WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i)
D) Contributing Watershed Area (including rain garden area) Area = 11,110 sq ft
E) Water Quality Capture Volume (WQCV) Design Volume VWQCV = 285 cu ft
Vol = (WQCV / 12) * Area
F) For Watersheds Outside of the Denver Region, Depth of d6 = in
Average Runoff Producing Storm
G) For Watersheds Outside of the Denver Region, VWQCV OTHER = 0.0 cu ft
Water Quality Capture Volume (WQCV) Design Volume
H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER = cu ft
(Only if a different WQCV Design Volume is desired)
2. Basin Geometry
A) WQCV Depth (12-inch maximum) DWQCV = 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 = 190 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
April 4, 2016
Landmark Apartment Expansion
Basin B
Choose One
Choose One
18" Rain Garden Growing Media
Other (Explain):
YES
NO
UD-BMP_v3.03 Rain Gardens B.xlsm, RG 4/4/2016, 2:09 PM
Sheet 2 of 2
Designer:
Company:
Date:
Project:
Location:
5. Impermeable Geomembrane Liner and Geotextile Separator Fabric
A) Is an impermeable liner provided due to proximity
of structures or groundwater contamination?
6. Inlet / Outlet Control
A) Inlet Control
7. Vegetation
8. Irrigation
A) Will the rain garden be irrigated?
Notes:
Design Procedure Form: Rain Garden (RG)
Stephanie Thomas
Northern Engineering
April 4, 2016
Landmark Apartment Expansion
Basin B
Choose One
Choose One
Choose One
Sheet Flow- No Energy Dissipation Required
Concentrated Flow- Energy Dissipation Provided
Plantings
Seed (Plan for frequent weed control)
Sand Grown or Other High Infiltration Sod
Choose One
YES
NO
YES
NO
UD-BMP_v3.03 Rain Gardens B.xlsm, RG 4/4/2016, 2:09 PM
APPENDIX B.2
STORM SEWERS
APPENDIX B.3
INLETS
APPENDIX C
SWMM MODELING
01/01/2013 00:01:00
SWMM 5 Page 1
S U M M A R Y S T A T I S T I C S
===================================
Object .............. Link 43
Variable ............. Flow (CFS)
Event Period ......... Variable
Event Statistic ...... Peak (CFS)
Event Threshold ...... Flow > 0.0000 (CFS)
Event Threshold ...... Event Volume > 0.0000 (ft3)
Event Threshold ...... Separation Time >= 6.0 (hr)
Period of Record ..... 01/01/2013 to 01/01/2013
Number of Events ..... 1
Event Frequency*...... 0.993
Minimum Value ........ 518.730
Maximum Value ........ 518.730
Mean Value ........... 518.730
Std. Deviation ....... 0.000
Skewness Coeff. ...... 0.000
*Fraction of all reporting periods belonging to an event.
SWMM 5 Page 1
S U M M A R Y S T A T I S T I C S
===================================
Object .............. Link 43
Variable ............. Flow (CFS)
Event Period ......... Variable
Event Statistic ...... Peak (CFS)
Event Threshold ...... Flow > 0.0000 (CFS)
Event Threshold ...... Event Volume > 0.0000 (ft3)
Event Threshold ...... Separation Time >= 6.0 (hr)
Period of Record ..... 01/01/2013 to 01/01/2013
Number of Events ..... 1
Event Frequency*...... 0.993
Minimum Value ........ 518.810
Maximum Value ........ 518.810
Mean Value ........... 518.810
Std. Deviation ....... 0.000
Skewness Coeff. ...... 0.000
*Fraction of all reporting periods belonging to an event.
SWMM 5 Page 1
APPENDIX D
EROSION CONTROL REPORT
Landmark Apartments Expansion
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
X
X
X
X
X X
X X
X X X X
X X X
X X X
X
X X
X X
X X X X X
X X
X X X
X X
X X
X X X X
X X
X X X
X X
X
X X
X X
X
X
X
HOBBIT STREET
54' RIGHT OFWAY
TRACT C
YOUNG'S CREEK
OWNER: CITY OF FORT COLLINS
TRACT B
YOUNG'S CREEK
OWNER: CITY OF FORT COLLINS
LOT 1 LANDMARK
SUBDIVISION PUD
OWNER: LANDMARK HOUSING LLC
EX. 10.00 SEWER EASEMENT
BOOK 1204, PAGE 344
EX. 15.00 UTILITY EASEMENT
REC. NO. 20040037611
LOT 6 SEAMAN
SUBDIVISION
OWNER: EWAN, JOHN L &
YVONNE S
EX. 90.00 STORM DRAINAGE EASEMENT
REC. NO. 86072551
LID BASIN D
TOTAL AREA: 0.46 AC
TOTAL IMPERVIOUS AREA: 0.29 AC
RAIN GARDEN AREA: 303 SF
RUN-ON RATIO: 42:1
LID
CALL UTILITY NOTIFICATION CENTER OF
COLORADO
Know what's
R
These drawings are
instruments of service
MAP POCKET
DR1 – OVERALL DRAINAGE EXHIBIT
X
X
X
X
X X
X X
X X X X
X X X
X X X
X
X X
X X
X X X X X
X X
X X X
X X
X X
X X X X
X X
X X X
X X
X
X X
X X
X
X
X
HOBBIT STREET
54' RIGHT OFWAY
TRACT C
YOUNG'S CREEK
OWNER: CITY OF FORT COLLINS
TRACT B
YOUNG'S CREEK
OWNER: CITY OF FORT COLLINS
LOT 1 LANDMARK
SUBDIVISION PUD
OWNER: LANDMARK HOUSING LLC
EX. 10.00' SEWER EASEMENT
BOOK 1204, PAGE 344
EX. 15.00' UTILITY EASEMENT
REC. NO. 20040037611
LOT 6 SEAMAN
SUBDIVISION
OWNER: EWAN, JOHN L &
YVONNE S
EX. 90.00' STORM DRAINAGE EASEMENT
REC. NO. 86072551
OS-4
A3
A2
OS-3
OS-1
B2
B1
UD-2
OS-5
10
9
8 1
2
5
6
3
4
RAIN GARDEN
RAIN GARDEN
RAIN GARDEN
RAIN GARDEN
RAIN GARDEN
RAIN GARDEN
CITY OF FORT COLLINS
100-YR FLOODWAY
CITY OF FORT COLLINS
100-YR FLOODPLAIN
CITY OF FORT COLLINS
100-YR FLOODPLAIN
INLET
INLET
INLET
INLET
DR1
CALL UTILITY NOTIFICATION CENTER OF
COLORADO
Know what's
R
CityDate Engineer
Date
Date
Date
Date
Stormwater Utility
Parks & Recreation
Traffic Engineer
Date
APPROVED:
CHECKED BY:
CHECKED BY:
CHECKED BY:
CHECKED BY:
CHECKED BY:
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
301 North Howes Street, Suite 100
Fort Collins, Colorado 80521
N O R T H E RN
PHONE: 970.221.4158
www.northernengineering.com
( IN FEET )
0
1 INCH = 30 FEET
30 30 60 90
KEYMAP
X
X
X
X
X
X
X
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 0.68 0.58 0.72 7.7 5.9 0.97 4.72
2 A2 0.46 0.70 0.87 8.3 5.6 0.77 3.86
3 A3 0.47 0.83 1.00 5.0 5.0 1.12 4.70
4 A4 0.14 0.25 0.31 5.0 5.0 0.10 0.44
5 A5 0.18 0.85 1.00 5.0 5.0 0.44 1.81
6 A6 0.47 0.72 0.91 5.0 5.0 0.97 4.22
7 UD-3 0.27 0.44 0.54 5.2 5.0 0.34 1.47
7 B1 0.05 0.35 0.44 10.7 9.5 0.04 0.17
8 B2 0.26 0.89 1.00 5.0 5.0 0.64 2.54
7 UD-1 0.14 0.63 0.79 5.0 5.0 0.26 1.12
7 UD-2 0.09 0.29 0.37 6.8 6.1 0.07 0.31
4 OS-1 0.77 0.30 0.38 13.6 12.3 0.45 2.06
2 OS-2 0.24 0.30 0.38 13.3 12.3 0.14 0.65
1 OS-3 1.05 0.30 0.38 12.1 11.1 0.64 2.92
3 OS-4 1.21 0.46 0.58 10.1 8.7 1.24 5.77
9 OS-5 0.16 0.83 1.00 5.0 5.0 0.39 1.64
10 OS-6 0.10 0.87 1.00 5.0 5.0 0.25 0.98
7 OS-7 0.51 0.29 0.37 5.0 5.0 0.43 1.88
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
LANDMARK APARTMENTS EXPANSION BY NORTHERN ENGINEERING, DATED April 5,
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
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
301 North Howes Street, Suite 100
Fort Collins, Colorado 80521
N O R T H E RN
PHONE: 970.221.4158
www.northernengineering.com
( IN FEET )
0
1 INCH = 30 FEET
30 30 60 90
KEYMAP
X
X
X
X
X
X
X
TOTAL SITE IMPERVIOUS AREA: 81,429 SF (1.87 AC)
TOTAL RAIN GARDEN AREA: 1,719 SF
TOTAL RAIN GARDEN RUN-ON AREA (IMPERVIOUS ONLY): 60,833 SF (1.39 AC)
OVERALL RAIN GARDEN TO RUN-ON RATIO: 35:1
TOTAL IMPERVIOUS AREA TREATED: 60,833 SF (1.39 AC)
PERCENT OF TOTAL IMPERVIOUS AREA TREATED: 75%
S. Thomas
Rainfall Intensity taken from the Fort Collins Stormwater Criteria Manual (FCSCM), Tables RA-7 and RA-8
April 4, 2016
Intensity,
i10
(in/hr)
C10
Q = C f ( C )( i )( A )
4/4/2016 2:04 PM D:\Projects\1257-001\Drainage\Hydrology\1257-001_Conceptual Hydrologic Calculations.xlsx\Runoff
10-yr
Tc
(min)
100-yr
Tc
(min)
7 North Historic Basin No 0.25 0.25 0.31 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A 5.0 5.0 5.0
7 South Historic Basin No 0.25 0.25 0.31 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A 5.0 5.0 5.0
7 Total Existing Site No 0.25 0.25 0.31 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A 5.0 5.0 5.0
1 A1 No 0.58 0.58 0.72 42 0.95% 6.4 6.4 4.7 N/A N/A N/A 189 2.65% 2.44 1.3 7.7 7.7 5.9
2 A2 No 0.70 0.70 0.87 159 3.40% 6.3 6.3 3.6 116 1.12% 2.12 0.9 141 2.06% 2.15 1.1 8.3 8.3 5.6
3 A3 No 0.83 0.83 1.00 34 7.06% 1.5 1.5 0.6 78 0.77% 1.75 0.7 132 2.88% 2.55 0.9 5.0 5.0 5.0
4 A4 No 0.25 0.25 0.31 N/A N/A N/A N/A N/A N/A N/A 257 5.56% 3.54 1.2 5.0 5.0 5.0
5 A5 No 0.85 0.85 1.00 134 4.33% 3.3 3.3 1.3 144 5.00% 4.47 0.5 N/A N/A N/A 5.0 5.0 5.0
6 A6 No 0.72 0.72 0.91 16 4.38% 1.7 1.7 0.9 86 1.51% 2.46 0.6 147 6.46% 3.81 0.6 5.0 5.0 5.0
7 UD-3 No 0.44 0.44 0.54 68 7.85% 5.2 5.2 4.3 N/A N/A N/A N/A N/A N/A 5.2 5.2 5.0
7 North Proposed Basin No 0.66 0.66 0.82 130 1.23% 8.8 8.8 5.6 55 1.27% 2.26 0.4 257 5.56% 3.54 1.2 10.5 10.5 7.2
7 B1 No 0.35 0.35 0.44 38 0.53% 10.7 10.7 9.5 N/A N/A N/A N/A N/A N/A 10.7 10.7 9.5
8 B2 No 0.89 0.89 1.00 67 0.75% 3.6 3.6 1.7 86 1.98% 2.81 0.5 N/A N/A N/A 5.0 5.0 5.0
7 UD-1 No 0.63 0.63 0.79 69 6.38% 3.9 3.9 2.6 N/A N/A N/A N/A N/A N/A 5.0 5.0 5.0
7 UD-2 No 0.29 0.29 0.37 55 4.55% 6.8 6.8 6.1 N/A N/A N/A N/A N/A N/A 6.8 6.8 6.1
7 South Proposed Basin No 0.67 0.67 0.84 95 2.00% 6.2 6.2 3.8 86 1.98% 2.81 0.5 N/A N/A N/A 6.7 6.7 5.0
4 OS-1 No 0.30 0.30 0.38 278 6.15% 13.6 13.6 12.3 N/A N/A N/A N/A N/A N/A 13.6 13.6 12.3
2 OS-2 No 0.30 0.30 0.38 205 6.73% 11.3 11.3 10.3 116 1.12% 2.12 0.9 141 2.06% 2.15 1.1 13.3 13.3 12.3
1 OS-3 No 0.30 0.30 0.38 188 6.97% 10.7 10.7 9.7 170 2.12% 2.91 1.0 64 3.75% 2.90 0.4 12.1 12.1 11.1
3 OS-4 No 0.46 0.46 0.58 180 9.78% 7.5 7.5 6.1 78 0.77% 1.75 0.7 222 1.71% 1.96 1.9 10.1 10.1 8.7
9 OS-5 No 0.83 0.83 1.00 90 2.89% 3.4 3.4 1.2 37 1.08% 2.08 0.3 N/A N/A N/A 5.0 5.0 5.0
10 OS-6 No 0.87 0.87 1.00 72 2.36% 2.7 2.7 1.2 61 1.64% 2.56 0.4 N/A N/A N/A 5.0 5.0 5.0
7 OS-7 No 0.29 0.29 0.37 N/A N/A N/A N/A N/A N/A N/A 350 1.20% 1.64 3.6 5.0 5.0 5.0
PROPOSED TIME OF CONCENTRATION COMPUTATIONS
S. Thomas
April 4, 2016
Design
Point
Sub-Basin
Overland Flow Gutter/ConcentrationPipe Flow Swale Flow Time of
(Equation RO-4)
( )
3
1
1 . 87 1 . 1 *
S
Ti C Cf L
-
=
4/4/2016 2:04 PM D:\Projects\1257-001\Drainage\Hydrology\1257-001_Conceptual Hydrologic Calculations.xlsx\Tc
Composite
% Imperv.
North Historic Basin 2.68 0.00 0.00 0.00 0.00 0.00 Clayey | Average 2% to 7% 2.675 0.25 0.25 0.31 0%
South Historic Basin 0.53 0.00 0.00 0.00 0.00 0.00 Clayey | Average 2% to 7% 0.535 0.25 0.25 0.31 0%
Total Existing Site 3.21 0.00 0.00 0.00 0.00 0.00 Clayey | Average 2% to 7% 3.210 0.25 0.25 0.31 0%
A1 0.68 0.22 0.04 0.05 0.00 0.00 Clayey | Average 2% to 7% 0.361 0.58 0.58 0.72 45%
A2 0.46 0.18 0.06 0.05 0.00 0.00 Clayey | Average 2% to 7% 0.167 0.70 0.70 0.87 61%
A3 0.47 0.12 0.09 0.18 0.00 0.00 Clayey | Average 2% to 7% 0.082 0.83 0.83 1.00 77%
A4 0.14 0.00 0.00 0.00 0.00 0.00 Clayey | Average 2% to 7% 0.141 0.25 0.25 0.31 0%
A5 0.18 0.13 0.03 0.00 0.00 0.00 Clayey | Average 2% to 7% 0.025 0.85 0.85 1.00 85%
A6 0.47 0.09 0.07 0.15 0.00 0.00 Clayey | Average 2% to 7% 0.151 0.72 0.72 0.91 63%
UD-3 0.27 0.00 0.02 0.05 0.00 0.00 Clayey | Average 2% to 7% 0.198 0.44 0.44 0.54 24%
North Proposed Basin 2.67 0.75 0.31 0.49 0.00 0.00 Clayey | Average 2% to 7% 1.126 0.66 0.66 0.82 55%
B1 0.05 0.00 0.01 0.00 0.00 0.00 Clayey | Average 2% to 7% 0.040 0.35 0.35 0.44 13%
B2 0.26 0.15 0.03 0.06 0.00 0.00 Clayey | Average 2% to 7% 0.023 0.89 0.89 1.00 88%
UD-1 0.14 0.00 0.03 0.05 0.00 0.00 Clayey | Average 2% to 7% 0.065 0.63 0.63 0.79 49%
UD-2 0.09 0.00 0.01 0.00 0.00 0.00 Clayey | Average 2% to 7% 0.085 0.29 0.29 0.37 6%
South Proposed Basin 0.53 0.15 0.06 0.11 0.00 0.00 Clayey | Average 2% to 7% 0.213 0.67 0.67 0.84 57%
Total Proposed Site 3.21 0.90 0.37 0.59 0.00 0.00 Clayey | Average 2% to 7% 1.339 0.66 0.66 0.82 55%
OS-1 0.77 0.00 0.00 0.00 0.77 0.00 Clayey | Average 2% to 7% 0.000 0.30 0.30 0.38 30%
OS-2 0.24 0.00 0.00 0.00 0.24 0.00 Clayey | Average 2% to 7% 0.000 0.30 0.30 0.38 30%
OS-3 1.05 0.00 0.00 0.00 1.05 0.00 Clayey | Average 2% to 7% 0.000 0.30 0.30 0.38 30%
OS-4 1.21 0.00 0.00 0.00 0.42 0.79 Clayey | Average 2% to 7% 0.000 0.46 0.46 0.58 43%
OS-5 0.16 0.11 0.03 0.00 0.00 0.00 Clayey | Average 2% to 7% 0.028 0.83 0.83 1.00 81%
OS-6 0.10 0.06 0.01 0.02 0.00 0.00 Clayey | Average 2% to 7% 0.011 0.87 0.87 1.00 86%
OS-7 0.51 0.00 0.03 0.00 0.00 0.00 Clayey | Average 2% to 7% 0.481 0.29 0.29 0.37 6%
1. Table RO-11 | Rational Method Runoff Coefficients for Composite Analysis
PROPOSED COMPOSITE % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS
4/4/2016 2:04 PM D:\Projects\1257-001\Drainage\Hydrology\1257-001_Conceptual Hydrologic Calculations.xlsx\Composite C