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April 11, 2014
City of Ft: Collin pprov d Plans
Approved By�
Date
FINAL DRAINAGE AND
EROSION CONTROL REPORT FOR
Global Village Academy
Fort Collins, Colorado
Prepared for:
Global Village International Schools
3398 Musson Road NW
Stanton, MI 48888
Prepared by:
■� I NORTHERN
ENGINEERING
200 South College Avenue, Suite 10
Fort Collins, Colorado 80524
Phone: 970.221.4158 Fax: 970.221.4159
v .northernengineering.com
Project Number: 924-003
NorthernEnatneerina.com It 970.221.4159
W (NORTHERN
ENGINEERING
April 11, 2014
ADDRESS: PHONE:970.221.4158 WEBSITE:
200 S. College Ave. Suite 10 www.northernengineering.com
Fort Collins, CO80524 FAX:970.221.4159
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, Colorado 80521
RE: Final Drainage and Erosion Control Report for
Global Village Academy._........ .. _... _ .....__.... ...
Dear Staff:
Northern Engineering is pleased to submit this Final Drainage and Erosion Control Report for your
review. This report accompanies the Project Development Plan submittal for the proposed Global
Village Academy 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.
�otx—
Aaron Cvar, PE
Project Engineer��,
.V NORTHERN
ENGINEERING
1
TABLE OF CONTENTS
"I.: GENERAL LOCATION AND DESCRIPTION.......::.........................................::::. 1
A. Location.............................................................................................................................................1
B. Description of Property.....................................................................................................................2
C. Floodplain...........................................................................................................................................4
II. DRAINAGE BASINS AND SUB-BASINS....................................................................... 4
A. Major Basin Description ..............:..............,...................... .,,..;:,.:.:.:.,...,.....,,..,.......... _._..,........... .4_.:,..,
III. DRAINAGE DESIGN CRITERIA .......... :...................................... ......... ....................... ...... 5.
A. Regulations................................................................................................:.......................................5
B. Four Step Process.............................................................................................................................. 5
C. Development Criteria Reference and Constraints............................................................................6
D. Hydrological Criteria.........................................................................................................................6
E. Hydraulic Criteria..............................................................................................................................6
G. Modifications of Criteria...................................................................................................................7
IV. DRAINAGE FACILITY DESIGN.................................................................................... 7
A. General Concept...............................................................................................................................7
B. Specific Details..................................................................................................................................7
V. CONCLUSIONS........................................................................................................8
A. Compliance with Standards..............................................................................................................8
B. Drainage Concept..............................................................................................................................8
References....................................................................................................................... 10
APPENDICES:
APPENDIX
A
— Hydrologic Computations
APPENDIX
B
— Inlet Calculations
APPENDIX
C
— Storm Line Calculations
APPENDIX
D
- Storm Line Outlet Protection Calculations
APPENDIX
E
- Water Quality Design Computations
APPENDIX
F
— Stormwater Management Model (SWMM), Detention Calculations
APPENDIX
G
— Erosion Control Report
Final Drainage Report
(NORTHERN
ENGINEERING
LIST OF FIGURES:
Figure 1- Aerial: Photograph ........:......... , :::..:::::::..............:. _...........::::....................::.:..:-.::. 2
.....
Figure 2— Proposed Site Plan................................................................................................ 3
Figure 3 -Existing Floodplains................................................................................. _:......._._..•..:• 4
MAP POCKET:
Proposed -Drainage Exhibit
Final Drainage Report
OBIKE�
■� _, I NORTHERN
I ENGINEERING
Global Village Academy
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6. No significant offsite flows are directed into the site. The adjacent Bronson Street,
South Taft Hill Road, and Horsetooth Road prevent offsite flows from entering the site
on the north, east, and southern boundaries of the property. Minimal offsite drainage
enters the site from the backs of lots to the west of the property.
B. Description of Property
1. The development area is roughly 5.0 net acres.
Figure 1 — Aerial Photograph
2. The property is currently open ground. The ground cover generally consists of native
grasses. Existing ground slopes are mild to moderate (i.e., 1 - 6±%) through the
interior of the property. General topography slopes from west to east.
3. According to the United States Department of Agriculture (USDA) Natural Resources
Conservation Service (NRCS) Soil Survey website:
hftp://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx,
the site consists of Paoli fine sandy loam and Table Mountain Loam, which fall into
Hydrologic Soil Group B.
4. The proposed project site plan is composed of a school grounds development.
Associated drives and parking, water and sewer lines will be constructed with the
development. Two water quality/detention ponds will be constructed with the
proposed development.
Final Drainage Report
2
NORTHERN
ENGINEERING
Global Village Academy
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44) NORTH
Figure 2— Proposed Site Plan
5. No existing irrigation facilities are located within the property.
6. The proposed land use is a school campus.
Final Drainage Report
3
NORTHERN
I ENGINEERING
Global Village Academy
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C. Floodplain
1. The project site is not encroached by any City or FEMA floodplain.
NORTH
Figure 3 —Area Floodplain Mapping
2. No offsite improvements are proposed with the project.
II. DRAINAGE BASINS AND SUB -BASINS
FEMA High Risk - Fbodway
0 FEMA Hgh Risk - 1 DO Year
0 FEMA Moderate Risk - 1001500
A. Major Basin Description
The project site lies within the Spring Creek Basin. Detention requirements are set by the
Silver Oaks Third Filing Drainage Plan, per City of Fort Collins Conceptual Review dated
November 1, 2013. This plan specified a 2- year historic release rate total release rate
(1.0 cfs for the overall site) into the Rossborough channel.
Final Drainage Report 4
u
■� NORTHERN
ENGINEERING
Global Village Academy
B. Sub -Basin Description
3. The subject property historically drains overland west to east. Runoff the site has
historically collected in the existing storm drain systems in Horsetooth Road and
South Taft Hill Road, which has directed all runoff into the existing Rossborough
channel which runs along. -the east side of South'Taft Hill Road and conveys drainage
north in the channel.. The.proposed site will generally maintain these historic . .
-drainage patterns. Xrriore detailed description of the project drainage patterns
follows in Section IV.A.4., below. i
III. DRAINAGE DESIGN CRITERIA
A. Regulations
There are no optional provisions outside of the FCSCM proposed with the proposed
project.
B. Four Step Process
The overall stormwater management strategy employed with the proposed project utilizes
the "Four Step Process" to minimize adverse impacts of urbanization on receiving waters.
The following is a description of how the proposed development has incorporated each
step.
Step 1 — Employ Runoff Reduction Practices
'
Several techniques have been utilized with the proposed development to facilitate the
reduction of runoff peaks, volumes, and pollutant loads as the site is developed from the
'
current use by implementing multiple Low Impact Development (LID) strategies including:
N7 Conserving existing amenities in the site including the existing vegetated areas.
Nil Providing .vegetated open areas throughout the site to reduce the overall impervious
area and to minimize directly connected imperious areas (MDCIA).
'
M Routing flows, to the extent feasible, through vegetated swales to increase time of
concentration, promote infiltration and provide initial water quality.
' Step 2 — Implement BMPs That Provide a Water Quality Capture Volume (WQCV) with
Slow Release
The efforts taken in Step 1 will facilitate the reduction of runoff; however, urban
development of this intensity will still generate stormwater runoff that will require
additional BMPs and water quality. The majority of stormwater runoff from the site will
ultimately be intercepted and treated using extended detention methods prior to exiting the
' site.
Step 3 — Stabilize Drainageways
' There are no. major drainageways within the subject property. While this step may not
seem applicable to proposed development, the project indirectly helps achieve stabilized
drainageways nonetheless. By providing water quality where none previously existed,
' sediment with erosion potential is removed from the downstream drainageway systems.
Furthermore, this project will pay one-time stormwater development fees, as well as
ongoing monthly stormwater utility fees, both of which help achieve City-wide drainageway
' stability.
Final Drainage Report 5
1 11C NORTHERN
ENGINEERING
Global Village Academy
' Step 4 —implement Site Specific and Other Source Control BMPs.
The proposed project will improve upon site specific source controls compared to historic
conditions:
NEI Trash, waste products, etc. that were previously left exposed with the historic trailer
park will no longer be allowed to exposure to runoff and transport to receiving
drainageways;- The proposed develgpmeht•will eliminate these sources of potential
' pollution.
C. Development Criteria Reference and Constraints
The subject property is surrounded by currently developed properties. Thus, several
-constraints have been identified -during the course of -this -analysis -that will impact the --
proposed drainage system including:
' W Existing elevations along the property lines will generally be maintained.
NH As previously mentioned, overall drainage patterns of the existing site will be
maintained.
N7 Elevations of existing downstream facilities that the subject property will release to
will be maintained.
D. Hydrological Criteria
1. The City of Fort Collins Rainfall Intensity -Duration -Frequency Curves, as depicted in
Figure RA-16 of the FCSCM, serve as the source for all hydrologic computations
'
associated with the proposed development. Tabulated data contained in Table RA-7
has been utilized for Rational Method runoff calculations.
'
2. The Rational Method has been employed to compute stormwater runoff utilizing
coefficients contained in Tables RO-11 and RO-12 of the FCSCM.
3. Three separate design storms have been utilized to address distinct drainage
scenarios. A fourth design storm has also been computed for comparison purposes.
'
The first design storm considered is the 801h percentile rain event, which has been
employed to design the project's water quality features. The second event analyzed is
the "Minor," or "Initial" Storm, which has a 2-year recurrence interval. The third
'
event considered is the "Major Storm," which has a 100-year recurrence interval.
The fourth storm computed, for comparison purposes only, is the 10-year event.
4. No other assumptions or calculation methods have been used with this development
that are not referenced by current City of Fort Collins criteria.
'
E. Hydraulic Criteria
1. As previously noted, the subject property maintains historic drainage patterns.
2. All drainage facilities proposed with the project are designed in accordance with
'
criteria outlined in the FCSCM and/or the Urban Drainage and Flood Control District
(UDFCD) Urban Storm Drainage Criteria Manual.
'
3. As stated above, the subject property is not located in a City or FEMA regulatory
floodplain.
'
4. The proposed project does not propose to modify any natural drainageways.
J
Final Drainage Report
6
' (NORTHERN
ENGINEERING
Global Village Academy
' F. Modifications of Criteria
1. The proposed development is not requesting any modifications to criteria at this time.
IV.- DRAINAGE FACILITY DESIGN
A. General Concept
i 1. The main objectives of the project drainage design are to maintain existing drainage
patterns, and to ensure no adverse impacts to any adjacent properties.
2. 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 -with in. the
sections to which the content best applies.
3. The drainage patterns anticipated for proposed drainage basins are described below.
Basin A
Basin A consists of future potential building area, drive, and the parking area for the
current phase building. The basin will drain via sheet flow and gutter flow into Pond
1.
' Basins B and C
Basins B and C consist of future (phase 2) building area, and a future (phase 2)
parking area, as well as a drive connecting to Bronson Street along the property north
boundary. These basins will drain via sheet flow and gutter flow into Pond 2.
' Basins D. E. and F
Basins D, E, and F, consist of paved and landscaped areas that drain offsite to
adjacent Right of Way. These basins are relatively small, and will create insignificant
drainage additions to adjacent Right of Way.
Basin OS
Basin OS consists of landscaped area that drain onsite. This basin is 0.02 acres in
size and will have insignificant impact to the site. The basin "drains directly into Pond
1.
' 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. Standard water quality treatment in the form of Extended Detention is being
' provided for the proposed development in Ponds 1 and 2.
2. LID features have been incorporated in the overall drainage design for the site
and include the design of soft bottom swales running along the lengths of
' Ponds 1 and 2. Additionally, the future parking area to be constructed with
phase 2 of the development will include the required 25% of paved area as
permeable pavers. This parking area will incorporate permeable pavers for
' 25% of the overall site, including both the paved area for the current phase
and the future phase 2.
Final Drainage Report 7
.V (NORTHERN
ENGINEERING
LVIII
3. Table 1, below, summarizes detention and water quality volumes for Ponds 1 and 2.
Please refer to Appendix F for detention computations and SWMM modeling output.
Table 1 — Pond Summary Table
100-YR ....._
' DET. VOL. WQ VOL. TOTAL VOL. RELEASE
—POND ..(AC -FT) ...: (AC -FT) (AGFT) (CFS).
1 (SE CORNER) 0.42 0.05 0.47 0.55
2 (NE CORNER) 0.74 0.07 0.81 0.37
4. Proper maintenance of the drainage -facilities -designed with the -proposed -
development is a critical component of their ongoing performance and effectiveness.
The water quality pond will be designed at Final to be easily accessed by
maintenance staff via gentle slopes provided to the bottom of the pond.
5. The drainage features associated with the proposed project are all private facilities,
located on private property.
V. CONCLUSIONS
A. Compliance with Standards
1. The drainage design proposed with the proposed project complies with the City of Fort
Collins' Stormwater Criteria Manual.
2. The drainage design proposed with this project complies with requirements for the
Spring Creek Basin and the Silver Oaks Third Filing Drainage Plan.
3. The drainage plan and stormwater management measures proposed with the
proposed development are compliant with all applicable State and Federal regulations
governing stormwater discharge.
B. Drainage Concept
1. The drainage design proposed with this project will effectively limit any potential
damage associated with its stormwater runoff by providing detention and water
quality mitigation features.
2. The drainage concept for the proposed development is consistent with requirements
for the Spring Creek Basin.
H
Final Drainage Report
8
(NORTHERN
ENGINEERING
Global Villa
References
1. City of Fort Collins Landscape Design Guidelines for Stormwater and Detention Facilities,
November 5, 2009, BHA Design, Inc. with City of Fort Collins Utility Services.
2. Fort Collins Stoiiriwater 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.
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 Draina>e Criteria Manual, Volumes 1-3, Urban Drainage and Flood Control
District, Wright -McLaughlin Engineers, Denver, Colorado, Revised April 2008.
Final Drainage Report
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APPENDIX A
Hydrologic Computations
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APPENDIX B
' Inlet Calculations
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APPENDIX C
Storm Line Calculations
APPENDIX D
' Storm Line Outlet Protection Calculations
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APPENDIX E
Water Quality Design Computations
' APPENDIX F
' Stormwater Management Model (SWMM), Detention Calculations
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APPENDIX G
Erosion Control Report
MAP POCKET '
Drainage Exhibits
0
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NORTHERN
■v
ENGINEERING Global Village Academy
'
EROSION CONTROL REPORT
A comprehensive Erosion and Sediment Control Plan (along with associated details) has been
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, constant) ada tin to site
y adapting conditions and needs. The Contractor shall update the
_...
_
location of..BMPs_as they are installed „removed or mod ified,.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 the Utility Plans. The Final Plans contain a
full-size Erosion Control sheet 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 the Development Agreement for the development. 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, prior to any earth disturbance 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.
1
Final Drainage Report
APPENDIX A
' Hydrologic Computations
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1 APPENDIX B
1 Inlet Calculations
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INLET CAPACITY SUMMARY
Project:
924-003
By:
ATC
Date:
3/1/2014
Inlet
Inlet
Inlet
Design
Design
ID
Type
Condition
Storm
Flow
Inlet Capacity
(CFS)
(CFS)
2-2
Single Combination Inlet
Sump
100-yr
4.50
6.20
3-2
Single Combination Inlet
Sump
10-yr
5.40
8.90
1
INLET IN A SUMP OR SAG LOCATION
Project >< 926-003
k" IDS Combo Inlet Calculation -DP B
Lo (C) X
H-Curb H-Vert
Wo
Wp
w
Lo (G)
Wammg
Warning
in Information (Input)
of inlet
Inlet Type
Depression (additional to cominuous gutter depression'a'from'O-AiloW)
aur.'
oar of Unit Inlets (Grate or Curb Opening)
No
r Depth at Flowltne (outside of local depression)
Flow Depth
r Information
in of a Unit Grate
L. (G)''
n of a Unit Grate
W.
Openng Raao for a Grate (typical values 0.15-0.90)
A..'
ling Factof for a Single Grate (typical value 0.50- 0.70)
C, (G)
I Wen Coaffivam (typical value 2.15 - 3.60)
C.. (G)'.
i Orifice Coefficient (typical value 0,60 - 0.60)
Co (G) "
OpeMrg Infix WA n
U of a Unit Curb OpaNng
4 (C)'
tt of Vertical Curb Opening in Inches
H,
tt of Curb Orlflm Throat In Inches
rtwo
r of Throat (see USDCM Figure ST-5)
Theta
Width for Depression Pan (typicaty the gutter vndth of 2 feet)
Wc'
ling Factor for a Sella Curt, Opening (typical value 0 10)
CG (C)
Opening Weir Coef6uem Itypical value 2.3-3 6)
C. (C) "
Opening Onhce CoeHiuem (typical value 0 60 - 0 70)
C„ (C)'
al Inlet Interception Capacity (assumes clogged condition)
Q. °
NING: Inlet Capacity, less Man 0 Peak for I OR Storm
Qe . ne.uri
laming 1: Dimension entered is not a typical dlmonstnn for inlet type specified.
Denver No. 15 Combination
200 inches
1
6.0 115 inches
MINOR MAJOR
3.00 feet
2.00 eel
031
0-50 0 50
3.60
060
300
650
5.25
0,00
2,00
0A0
010
3.70
0.66
ail
Iches
Iclres
agrees
Sat
UO Inlet 3.1-combomlet-dpa. Inlet In Sump 3111/2014, 2:07 PM
INLET IN A SUMP OR SAG LOCATION
Project = 924-003 _
Inlet ID = Combo Inlet Calculation -DP B
,�-Lo (C)-,f
M-Curt H-Vert
Wo
Wp
W
Lo (G)
Naming
in Information (input)
of Inlet
Inlet Type'
Depression (additional to continuous gutter depression' a' Imm'Q-AIbW)
4m+'
wo of Unit Inlets (Grate or Curb Opening)
No
r Depth at Fbwllna (outside of local depression)
Few Depth
r Wormetlen
In of a Unit Grate
Ile (G)'
1 of a Unit Grate
WD'
Opening Ratio fora Grate (typical values 0.15-0.90)
rlaa'
prig Factor for a Single Grate (typical value 0.50 - 0 70)
4 (G)'
i Weir COemCi.nt (typical value 2.15 - 3.60)
C. (G) "
i Orifice Coefficient (typical yaee 0.60 - 0.60)
C. (G)'
Opening information
M of a Unit Curb Opening
b (C)'
n of Verucal Curb Opening in boles
Hwn "
V of Curb Orifice Throat in Inches
H.
i of Throat (sea USDCM Figure ST-5)
Theta'
Width for Depression Pan (typically Into guner viol of 2 feet)
Wo'
prig Factor for a Single Cue Opening (typical value 0.10)
Cr (C) "
Opening Weir Coefficient (typical value 2.3-3.6)
co (C)'
Opening Orifice Coefficient (typical value 0.60 - 0.70)
C. (C)''
III Inlet Interception Capacity (assumes clogged condition)
Q. r
Capacity IS GOOD for Minor and Major Storms (>Q PEAK)
Ore asaauneo''
taming 1: Dimension entered is not a typical dimension for Inlet type sya:itu at
Denver No. 16 Combirle0on
2.00 - Inches
i
6.0 6.0 Inches
MINOR MAJOR
3.00 foal
2.00 feet
0.31
0.50 0.50
3.60
0.60
3.00
6.50
5.25
0.00
2.00
0.10
010
3.70
0.66
MINOR MAJOR
eat
nches
nches
legreas
eat
UD Inlet 3.1comboinlel-dpe, Inlet In Sump
311112014, 2:04 PM
APPENDIX . C
Storm Line Calculations
1
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' APPENDIX D
' Storm Line Outlet Protection Calculations
1
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I
' APPENDIX E
Water Quality Design Computations
TY POND DESIGN CALCULATIONS
ATC
:QUIRED STORAGE & OUTLET WORKS:
BASIN AREA =
1.750
<-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS PERCENT =
85.00
<-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS RATIO =
0.8500
<--CALCULATED
WQCV (watershed inches) =
0.362
<-- CALCULATED from Figure EDB-2
WQCV (ac-ft) =
0.053
<-- CALCULATED from UDFCD DCM V.3 Section 6.5
WQ Depth (ft) =
1.000
<-- INPUT from stage -storage table
AREA REQUIRED PER ROW, a (in2) =
0.217
<-- CALCULATED from Figure EDB-3
CIRCULAR PERFORATION SIZING:
dia (in) = 112
<-- INPUT from Figure 5
n = 3
<-- INPUT from Figure 5
t (in) = 1/4
<-- INPUT from Figure 5
number of rows = 1
<-- CALCULATED from WQ Depth and row spacing
WATER QUALITY POND DESIGN CALCULATIONS
POND 2
Project: 924-003
By: ATC
Date: 3/10/14 -
=IRED STORAGE & OUTLET WORKS:
BASIN AREA =
3.050
<-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS PERCENT =
65.00
<--INPUT from impervious calcs
BASIN IMPERVIOUSNESS RATIO =
0.6500
<-- CALCULATED
WQCV (watershed inches) =
0.254
<-- CALCULATED from Figure EDB-2
WQCV (ac-ft) =
0.065.
<-- CALCULATED from UDFCD DCM V.3 Section 6.5
WO Depth (ft) =
1.000
<-- INPUT from stage -storage table
AREA REQUIRED PER ROW, a (in2) =
0.263
<-- CALCULATED from Figure EDB-3
CIRCULAR PERFORATION SIZING:
dia (in) = 1/2
<-- INPUT from Figure 5
n = 3
<-- INPUT from Figure 5
t (in) = 1/4
<-- INPUT from Figure 5
number of rows = 1
<-- CALCULATED from WQ Depth and row spacing
0
Calculating the WQCV and Volume Reduction Chapter 3
1
Once the WQCV in watershed inches is found from Figure 3-2 or using Equation 3-1 and/or 3-2, the
required BMP storage volume in acre-feet can be calculated as follows:
r WQCVI
..' :.. V -.\ 12 / A � .: .: , . _ .... Equation 3=3 .
' Where:
V = required storage volume (acre-ft)
' A = tributary catchment area upstream (acres)
WQCV = Water Quality Capture Volume (watershed inches)
'
0.500
0.450
'
r
0.400
c
0.350
'
0.300
t
y
0.250
'
0.200
c
0.150
C
0.100
t
0.050
0 Mn
"I mil
--------
2 4 drain I
--'W
'-
' 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0:8 0.9 1
Total Imperviousness Ratio (i = la/100)
' Figure 3-2. Water Quality Capture Volume (WQCV) Based on BMP Drain Time
'
3-6
Urban Drainage and Flood Control District
Urban Storm Drainage Criteria Manual Volume 3
August 2011
' APPENDIX F
' Stormwater Management Model (SWMM), Detention Calculations
SWMM RATING CURVE
POND 1
Project: 924-003
Date: 3/10/14
By: ATC
STAGE
FT
DEPTH
FT
SURFACE AREA
OF CONTOUR
SF
STORAGE
CF
STORAGE
AC FT
RELEASE
CFS
5123.6
0
10
0
0.000
0.00
5124
0.40
3,339.73
641.27
0.015
0.00
5125
1.00
7,382.79
6578.05
0.151
0.39
5126
1.00
9,827.20
15166.47
0.348
0.52
5127
1.00
12,465.23
26295.97
0.604
0.63
OUTLET RATING CURVE
POND 1
100-YR ORIFICE RATING
Orifice Dia (in) 3.50
Orifice Area (so 0.0668
Orifice invert (ft) 5123.6
Orifice Coefficient 0.65
Orifice Area
SF
Stage
FT
Outlet
release
CFS
0.0668
5,123.60
0.00
0.0668
5,124.00
0.00
0.0668
5,125.00
0.39
0.0668
5,126.00
0.52
0.0668
5,127.00
0.63
1
1
1
1
1
1
1
SWMM RATING CURVE
POND 2
Project: 924-003
Date: 3/10/14
By: ATC
STAGE
FT
DEPTH
FT
SURFACE AREA
OF CONTOUR
SF
STORAGE
CF
STORAGE
AC -FT
RELEASE
CFS
5121.2
0
1489
0
0.000
0.00
5122
0.80
15239
8004
0.184
0.18
5123
1.00
17562
24396.9
0.560
0.28
5123.8
0.80
119492
39214.5
0.900
0.34
OUTLET RATING CURVE
POND 2
100-YR ORIFICE RATING
Orifice Dia (in) 2.75
Orifice Area (sf) 0.0412
Orifice invert (ft) 5121.2
Orifice Coefficient 0.65
Orifice Area
SF
Stage
FT
Outlet
release
CFS
0.0412
5,121.20
0.00
0.0412
5,122.00
0.18
0.0412
5,123.00
0.28
0.0412
5,123.80
0.34
0
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APPENDIX G
Erosion Control Report
'
INORTHERN
ENGINEERING Global Village AcademN
'
EROSION CONTROL REPORT
'
A comprehensive Erosion and Sediment Control Plan (along with associated details) has been
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..i.nstalled, 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 the Utility Plans. The Final Plans contain a
full-size Erosion Control sheet 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 the Development Agreement for the development. 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, prior to any earth disturbance 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.
Final Drainage Report
MAP POCKET
Drainage Exhibits
No Text