HomeMy WebLinkAboutCAPSTONE COTTAGES - PDP - PDP140004 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTMay 7, 2014
PRELIMINARY DRAINAGE AND
EROSION CONTROL REPORT FOR
CAPSTONE COTTAGES
Fort Collins, Colorado
Prepared for:
Capstone Collegiate Communities
431 Office Park Drive
Birmingham, Alabama 35223
Prepared by:
200 South College Avenue, Suite 10
Fort Collins, Colorado 80524
Phone: 970.221.4158 Fax: 970.221.4159
www.northernengineering.com
Project Number: 939-001
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.
May 7, 2014
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, Colorado 80521
RE: Preliminary Drainage and Erosion Control Report for
CAPSTONE COTTAGES
Dear Staff:
Northern Engineering is pleased to submit this Preliminary Drainage and Erosion Control Report
for your review. This report accompanies the Project Development Plan submittal for the
proposed Capstone Cottages 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.
Aaron Cvar, PE
Project Engineer
Capstone Cottages
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
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
G. Modifications of Criteria ................................................................................................................... 6
IV. DRAINAGE FACILITY DESIGN .................................................................................... 6
A. General Concept ............................................................................................................................... 6
B. Specific Details .................................................................................................................................. 7
V. CONCLUSIONS ........................................................................................................ 8
A. Compliance with Standards .............................................................................................................. 8
B. Drainage Concept .............................................................................................................................. 8
References ....................................................................................................................... 10
APPENDICES:
APPENDIX A – Hydrologic Computations
APPENDIX B - Water Quality Design Computations
APPENDIX C – Stormwater Management Model (SWMM)
APPENDIX D – Erosion Control Report
Capstone Cottages
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:
Proposed Drainage Exhibit
Capstone Cottages
Preliminary Drainage Report 1
I. GENERAL LOCATION AND DESCRIPTION
A. Location
1. Vicinity Map
2. The project site is located in the west half of Section 7, Township 6 North, Range 68
West of the 6th Principal Meridian, City of Fort Collins, County of Larimer, State of
Colorado .
3. The project site is located just northeast of the intersection of Lemay Avenue and
Lincoln Avenue.
4. The project site lies within the Dry Creek Basin. Detention requirements are to detain
the difference between the 100-year developed inflow rate and the historic 2-year
release rate. The historic release rate for this basin is 0.20 cfs per acre.
5. The Mulberry Street Walmart and the Buffalo Run Apartment complex exist just to the
south of the site, on the south side of Lincoln Avenue. The San Criso residential
development exists to the north of the site. The Sunward Condos development exists
to the east of the site. The Lincoln Channel (Storm Drainage) runs along the southern
boundary of the project site, and will be utilized as the storm outfall for the majority of
Capstone Cottages
Preliminary Drainage Report 2
developed site runoff.
6. No offsite flows enter the site from the north, south, or east. The Lincoln Channel
conveys regional flows from the west; this channel conveys flows east along the
southern boundary of the project site.
B. Description of Property
1. The development area is roughly 28.33 net acres.
Figure 1 – Aerial Photograph
2. The subject property is an undeveloped parcel with native ground cover. Existing
ground slopes are mild to moderate (i.e., 1 - 6±%) through the interior of the
property. General topography slopes from northwest to southeast. The Lincoln
Channel, running along the southern boundary of the project site, collects the majority
of historic site runoff.
3. According to the United States Department of Agriculture (USDA) Natural Resources
Conservation Service (NRCS) Soil Survey website:
http://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx,
the site consists of Caruso Clay Loam, Loveland Clay Loam, and Nunn Clay Loam,
which all fall into Hydrologic Soil Group C.
4. The proposed project site plan is composed of residential and commercial
development. Associated roadways, water and sewer lines will be constructed with
Capstone Cottages
Preliminary Drainage Report 3
the development. Onsite detention is proposed within the subgrade of a permeable
paver system. The proposed paver system is to be located throughout the site,
predominantly within proposed parking areas. This paver system is anticipated to
meet or exceed the current City LID requirements.
Figure 2– Proposed Site Plan
5. There are no known irrigation laterals crossing the site.
6. The proposed land use is residential and commercial.
C. Floodplain
1. The project site is not encroached by any City or FEMA 100-year floodplain. The site
Capstone Cottages
Preliminary Drainage Report 4
is located within the 500-year floodplain of the Cache La Poudre Rive.
Figure 3 –Area Floodplain Mapping
II. DRAINAGE BASINS AND SUB-BASINS
A. Major Basin Description
2. The project site lies within the Dry Creek Basin. Detention requirements are to detain
the difference between the 100-year developed inflow rate and the historic 2-year
release rate. The historic release rate for this basin is 0.20 cfs per acre. The site
outfall is the existing Lincoln Channel, running along the southern boundary of the
site.
B. Sub-Basin Description
1. The subject property historically drains overland from northwest to southeast. Runoff
from the majority of the site has historically been collected in the Lincoln Channel,
running along the southern boundary of the site. The Lincoln Channel captures
regional flows from the west and conveys these flows east.
2. A more detailed description of the project drainage patterns follows in Section IV.A.4.,
below.
Capstone Cottages
Preliminary Drainage Report 5
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:
Conserving existing amenities in the site including the existing vegetated areas.
Providing vegetated open areas throughout the site to reduce the overall impervious
area and to minimize directly connected impervious areas (MDCIA).
Routing flows, to the extent feasible, through vegetated 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 (the Lincoln Channel is
located outside of the property boundary). 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.
Step 4 – Implement Site Specific and Other Source Control BMPs.
The proposed project will improve upon site specific source controls compared to historic
conditions:
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 development 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
Capstone Cottages
Preliminary Drainage Report 6
proposed drainage system including:
Existing elevations along the property lines will generally be maintained.
As previously mentioned, overall drainage patterns of the existing site will be
maintained.
Elevations of existing downstream facilities that the subject property will release to
will be maintained.
D. Hydrological Criteria
1. The City of Fort Collins Rainfall Intensity-Duration-Frequency Curves, as depicted in
Figure RA-16 of the FCSCM, serve as the source for all hydrologic computations
associated with the proposed development. Tabulated data contained in Table RA-7
has been utilized for Rational Method runoff calculations.
2. The Rational Method has been employed to compute stormwater runoff utilizing
coefficients contained in Tables RO-11 and RO-12 of the FCSCM.
3. 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 80th 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.
F. Modifications of Criteria
1. The proposed development is not requesting any modifications to criteria at this time.
IV. DRAINAGE FACILITY DESIGN
A. General Concept
1. The main objectives of the project drainage design are to maintain existing drainage
patterns, and to ensure no adverse impacts to any adjacent properties.
2. Onsite detention will be provided primarily within the subgrade of the proposed
permeable pavement systems. Water quality capture volume for the purpose of water
quality treatment conforming to extended detention criteria will also be provided
Capstone Cottages
Preliminary Drainage Report 7
within the subgrade of the proposed permeable pavement systems. Detention and
water quality release rates will be controlled through sub-surface control structures.
3. A list of tables and figures used within this report can be found in the Table of
Contents at the front of the document. The tables and figures are located within the
sections to which the content best applies.
4. The drainage patterns anticipated for proposed drainage basins are described below.
Basins 1-7
Basins 1 through 7 will generally drain via overland flow and curb and gutter flow into
inlets and storm line systems within the project site. A series of permeable paver
systems will be designed to both capture direct runoff and collect runoff from storm
line systems. The permeable paver sub-grade material will be utilized for both water
quality capture volume and detention volume. Please see further discussion of water
quality and detention requirements in Section IV.B, below.
Basin OS-1
Basin OS-1 consists of a portion of the proposed Duff Drive (0.58 acres). This basin
will drain via street curb and gutter west into Lemay Avenue without detention or
water quality treatment.
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 is
proposed within the permeable paver sub-grade material. A series of sub-
grade detention release structures will be designed at Final in order to provide
the required water quality capture volume and to maintain the required site
release rate.
2. Quantity detention is a requirement for the site, and full quantity detention is
proposed to be provided within the permeable paver sub-grade material. A
series of sub-grade detention release structures will be designed at Final in
order to provide the required water quality capture volume and to maintain the
required site release rate. The current stipulation for release rate is 0.20 cfs
per acre per the Dry Creek. The project site encompasses 28.33 acres, thus a
release rate of 5.67 cfs for the overall site would be required by this criteria.
However, based on discussion with City Stormwater staff, the release rate may
be modified pending modeling currently under way comparing the current
effective Dry Creek Basin SWMM model with updated conditions reflecting the
current development. A total detention volume within the subgrade of the
paver systems of 5.04 acre-feet has been estimated for preliminary purposes
using the computer program EPA SWMM (please see Appendix C). A total
water quality capture volume of 0.79 acre-feet has been estimated for
preliminary purposes using standard extended (40-hour) detention design
methodology. Water quality capture volume will be provided within the
subgrade of the permeable paver systems.
3. LID features will be incorporated in the design of the overall site at Final
design. The site plan currently shows the majority of LID measures proposed
with the development plan as consisting of a very significant permeable paver
Capstone Cottages
Preliminary Drainage Report 8
system. Water quality and detention will be provided within the permeable
paver system. This system will greatly enhance filtration of storm runoff, and
will provide significant storm runoff infiltration.
4. Final design details, construction documentation, and Standard Operating
Procedures (SOP) Manual shall be provided to the City of Fort Collins for
review prior to Final Development Plan approval. A final copy of the approved
SOP manual shall be provided to City and must be maintained on-site by the
entity responsible for the facility maintenance. Annual reports must also be
prepared and submitted to the City discussing the results of the maintenance
program (i.e. inspection dates, inspection frequency, volume loss due to
sedimentation, corrective actions taken, etc.).
5. 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.
6. 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
Dry Creek Basin.
3. The drainage plan and stormwater management measures proposed with the
proposed development are compliant with all applicable State and Federal regulations
governing stormwater discharge.
B. Drainage Concept
1. The drainage design proposed with this project will effectively limit any potential
damage associated with its stormwater runoff by providing detention and water
quality mitigation features.
2. The drainage concept for the proposed development is consistent with requirements
for the Dry Creek Basin.
Capstone Cottages
Preliminary Drainage Report 9
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 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.
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
CHARACTER OF SURFACE:
Runoff
Coefficient
Percentage
Impervious Project: 939-001
Streets, Parking Lots, Roofs, Alleys, and Drives: Calculations By: ATC
Asphalt ……....……………...……….....…...……………….………………………………….. 0.95 100% Date:
Concrete …….......……………….….……….………………..….……………………………… 0.95 90%
Gravel ……….…………………….….…………………………..………………………………. 0.50 40%
Roofs …….…….………………..……………….…………………………………………….. 0.95 90%
Pavers…………………………...………………..…………………………………………….. 0.40 22%
Lawns and Landscaping
Sandy Soil ……..……………..……………….…………………………………………….. 0.15 0%
Clayey Soil ….….………….…….…………..………………………………………………. 0.25 0% 2-year Cf
= 1.00 100-year Cf = 1.25
Basin ID
Basin Area
(s.f.)
Basin Area
(ac)
Area of
Asphalt
(ac)
Area of
Concrete
(ac)
Area of
Roofs
(ac)
Area of
Gravel
(ac)
Area of
Lawns and
Landscaping
(ac)
2-year
Composite
Runoff
Coefficient
10-year
Composite
Runoff
Coefficient
100-year
Composite
Runoff
Coefficient
Composite
% Imperv.
1 168878 3.88 Note: For preliminary calculations, Composite Runoff Coefficients are 0.55 0.55 0.69 45%
2 140314 3.22 based on Table RO-10. 0.55 0.55 0.69 45%
3 156373 3.59 Composite % Imperviousness has been estimated based 0.55 0.55 0.69 45%
4 98681 2.27 on UDFCD USDCM, Vol. I, Figures RO-3 and RO-4. 0.55 0.55 0.69 45%
5 179067 4.11 0.55 0.55 0.69 45%
6 225906 5.19 0.55 0.55 0.69 45%
7 110644 2.54 0.55 0.55 0.69 45%
8 38598 0.89 0.55 0.55 0.69 45%
OS1 25432 0.58 0.55 0.55 0.69 45%
DEVELOPED COMPOSITE % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS
Overland Flow, Time of Concentration:
Project: 939-001
Calculations By:
Date:
Gutter/Swale Flow, Time of Concentration:
Tt = L / 60V
Tc = Ti + Tt (Equation RO-2)
Velocity (Gutter Flow), V = 20·S½
Velocity (Swale Flow), V = 15·S½
NOTE: C-value for overland flows over grassy surfaces; C = 0.25
Is Length
>500' ?
C*Cf
(2-yr
Cf=1.00)
C*Cf
(10-yr
Cf=1.00)
C*Cf
(100-yr
Cf=1.25)
Length,
L
(ft)
Slope,
S
(%)
Ti
2-yr
(min)
Ti
10-yr
(min)
Ti
100-yr
(min)
Length,
L
(ft)
Slope,
S
(%)
Velocity,
V
(ft/s)
Tt
(min)
Length,
L
(ft)
Slope,
S
(%)
Velocity,
V
(ft/s)
Tt
(min)
2-yr
Tc
Rational Method Equation: Project: 939-001
Calculations By:
Date:
From Section 3.2.1 of the CFCSDDC
Rainfall Intensity:
1 1 3.88 12 12 10 0.55 0.55 0.69 2.09 3.57 7.88 4.5 7.6 21.0
2 2 3.22 13 13 11 0.55 0.55 0.69 2.02 3.45 7.57 3.6 6.1 16.8
3 3 3.59 15 15 14 0.55 0.55 0.69 1.90 3.24 6.82 3.7 6.4 16.8
4 4 2.27 11 11 10 0.55 0.55 0.69 2.13 3.63 7.88 2.7 4.5 12.3
5 5 4.11 12 12 10 0.55 0.55 0.69 2.09 3.57 7.88 4.7 8.1 22.3
6 6 5.19 12 12 10 0.55 0.55 0.69 2.05 3.50 7.72 5.8 10.0 27.5
7 7 2.54 9 9 7 0.55 0.55 0.69 2.30 3.93 8.80 3.2 5.5 15.4
8 8 0.89 8 8 7 0.55 0.55 0.69 2.40 4.10 9.06 1.2 2.0 5.5
OS1 OS1 0.58 7 7 6 0.55 0.55 0.69 2.52 4.31 9.63 0.8 1.4 3.9
Intensity,
i10
(in/hr)
Rainfall Intensity taken from the City of Fort Collins Storm Drainage Design Criteria (CFCSDDC), Figure 3.1
C10
Area, A
(acres)
Intensity,
i2
(in/hr)
100-yr
Tc
(min)
DEVELOPED RUNOFF COMPUTATIONS
C100
Design
Point
Flow,
Q100
(cfs)
Flow,
Q2
(cfs)
10-yr
Tc
(min)
2-yr
Tc
(min)
C2
Flow,
Q10
(cfs)
Intensity,
i100
(in/hr)
Basin(s)
ATC
April 1, 2014
Q C f C i A
APPENDIX B
WATER WAWAWATER QUALITY DESIGN COMPUTATIONS
WATER QUALITY DESIGN CALCULATIONS
Total Req'd Water Quality Capture Volume
Project: 939-001
By: ATC
Date: 4/1/14
REQUIRED STORAGE & OUTLET WORKS:
BASIN AREA = 25.680 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS PERCENT = 45.00 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS RATIO = 0.4500 <-- CALCULATED
WQCV (watershed inches) = 0.193 <-- CALCULATED from Figure EDB-2
WQCV (ac-ft) = 0.413 <-- CALCULATED from UDFCD DCM V.3 Section 6.5
WQ Depth (ft) = ** <-- INPUT from stage-storage table
AREA REQUIRED PER ROW, a (in
2
) = ** <-- CALCULATED from Figure EDB-3
CIRCULAR PERFORATION SIZING:
dia (in) = ** <-- INPUT from Figure 5
n = ** <-- INPUT from Figure 5
t (in) = ** <-- INPUT from Figure 5
number of rows = ** <-- CALCULATED from WQ Depth and row spacing
**To be completed at final design
APPENDIX C
STORMWATER MANAGEMENT MODEL (SWMM)
EPA STORM WATER MANAGEMENT MODEL - VERSION 5.0 (Build 5.0.022)
--------------------------------------------------------------
*********************************************************
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
Ponding Allowed ........ NO
Water Quality .......... NO
Infiltration Method ...... HORTON
Flow Routing Method ...... KINWAVE
Starting Date ............ NOV-21-2012 00:00:00
Ending Date .............. NOV-21-2012 06:00:00
Antecedent Dry Days ...... 0.0
Report Time Step ......... 00:15:00
Wet Time Step ............ 00:05:00
Dry Time Step ............ 01:00:00
Routing Time Step ........ 30.00 sec
************************** Volume Depth
Runoff Quantity Continuity acre-feet inches
************************** --------- -------
Total Precipitation ...... 7.852 3.669
Evaporation Loss ......... 0.000 0.000
Infiltration Loss ........ 1.833 0.857
Surface Runoff ........... 5.965 2.787
Final Surface Storage .... 0.097 0.045
Continuity Error (%) ..... -0.544
************************** Volume Volume
Flow Routing Continuity acre-feet 10^6 gal
************************** --------- ---------
Dry Weather Inflow ....... 0.000 0.000
Wet Weather Inflow ....... 5.965 1.944
Groundwater Inflow ....... 0.000 0.000
RDII Inflow .............. 0.000 0.000
External Inflow .......... 0.000 0.000
External Outflow ......... 0.462 0.151
Internal Outflow ......... 0.000 0.000
Storage Losses ........... 0.000 0.000
Initial Stored Volume .... 0.000 0.000
Final Stored Volume ...... 5.497 1.791
Continuity Error (%) ..... 0.094
********************************
SWMM 5 Page 1
Highest Flow Instability Indexes
********************************
All links are stable.
*************************
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 : 1.08
***************************
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
--------------------------------------------------------------------------------------------------------
overall 3.67 0.00 0.00 0.86 2.79 1.94 160.55 0.760
******************
Node Depth Summary
******************
---------------------------------------------------------------------
Average Maximum Maximum Time of Max
Depth Depth HGL Occurrence
Node Type Feet Feet Feet days hr:min
---------------------------------------------------------------------
MH JUNCTION 0.21 1.25 98.75 0 00:40
outlet_overall OUTFALL 0.00 0.00 96.00 0 00:00
pond3 STORAGE 4.36 5.02 102.02 0 02:27
*******************
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
-------------------------------------------------------------------------------------
MH JUNCTION 160.55 160.55 0 00:40 1.944 1.944
outlet_overall OUTFALL 0.00 1.00 0 00:36 0.000 0.151
pond3 STORAGE 0.00 161.80 0 00:40 0.000 1.942
**********************
Node Surcharge Summary
**********************
No nodes were surcharged.
SWMM 5 Page 2
*********************
Node Flooding Summary
*********************
No nodes were flooded.
**********************
Storage Volume Summary
**********************
--------------------------------------------------------------------------------------------
Average Avg E&I Maximum Max Time of Max Maximum
Volume Pcnt Pcnt Volume Pcnt Occurrence Outflow
Storage Unit 1000 ft3 Full Loss 1000 ft3 Full days hr:min CFS
--------------------------------------------------------------------------------------------
pond3 208.039 21 0 251.609 25 0 02:26 1.00
***********************
Outfall Loading Summary
***********************
-----------------------------------------------------------
Flow Avg. Max. Total
Freq. Flow Flow Volume
Outfall Node Pcnt. CFS CFS 10^6 gal
-----------------------------------------------------------
outlet_overall 97.23 0.96 1.00 0.151
-----------------------------------------------------------
System 97.23 0.96 1.00 0.151
********************
Link Flow Summary
********************
-----------------------------------------------------------------------------
Maximum Time of Max Maximum Max/ Max/
|Flow| Occurrence |Veloc| Full Full
Link Type CFS days hr:min ft/sec Flow Depth
-----------------------------------------------------------------------------
9 CONDUIT 161.80 0 00:40 28.56 0.03 0.12
out3 DUMMY 1.00 0 00:36
*************************
Conduit Surcharge Summary
*************************
No conduits were surcharged.
Analysis begun on: Mon May 05 14:08:42 2014
Analysis ended on: Mon May 05 14:08:42 2014
Total elapsed time: < 1 sec
SWMM 5 Page 3
APPENDIX D
EROSION CONTROL REPORT
Capstone Cottages
Preliminary Erosion Control Report
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 the Utility Plans. The Final Plans will 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.
MAP POCKET
DRAINAGE EXHIBITS
(min)
10-yr
Tc
(min)
100-yr
Tc
(min)
11No0.55 0.55 0.69 110 2.00% 8.6 8.6 6.4 320 0.75% 1.73 3.1 0 0.00% N/A N/A 12 12 10
22No0.55 0.55 0.69 110 2.00% 8.6 8.6 6.4 430 0.75% 1.73 4.1 0 0.00% N/A N/A 13 13 11
33No0.55 0.55 0.69 45 2.00% 5.5 5.5 4.1 980 0.75% 1.73 9.4 0 0.00% N/A N/A 15 15 14
44No0.55 0.55 0.69 65 2.00% 6.6 6.6 4.9 510 0.75% 1.73 4.9 0 0.00% N/A N/A 11 11 10
55No0.55 0.55 0.69 85 2.00% 7.5 7.5 5.6 420 0.75% 1.73 4.0 0 0.00% N/A N/A 12 12 10
66No0.55 0.55 0.69 125 2.00% 9.1 9.1 6.8 340 0.75% 1.73 3.3 0 0.00% N/A N/A 12 12 10
77No0.55 0.55 0.69 75 2.00% 7.1 7.1 5.3 210 0.75% 1.73 2.0 0 0.00% N/A N/A 9 9 7
88No0.55 0.55 0.69 65 2.00% 6.6 6.6 4.9 190 0.75% 1.73 1.8 0 0.00% N/A N/A 8 8 7
OS1 OS1 No 0.55 0.55 0.69 45 2.00% 5.5 5.5 4.1 170 0.75% 1.73 1.6 0 0.00% N/A N/A 7 7 6
DEVELOPED TIME OF CONCENTRATION COMPUTATIONS
Gutter Flow Swale Flow
Design
Point
Basin
Overland Flow
ATC
April 1, 2014
Time of Concentration
(Equation RO-4)
3
1
1 . 87 1 . 1 *
S
Ti C Cf L
Runoff Coefficients are taken from the City of Fort Collins Storm Drainage Design Criteria and Construction Standards, Table 3-3. % Impervious taken from UDFCD USDCM, Volume I.
10-year Cf = 1.00
April 1, 2014