HomeMy WebLinkAboutLEGACY SENIOR RESIDENCES - FDP - FDP120010 - SUBMITTAL DOCUMENTS - ROUND 2 - DRAINAGE REPORTAugust 29, 2012
FINAL DRAINAGE AND
EROSION CONTROL REPORT
LEGACY SENIOR RESIDENCES
Fort Collins, Colorado
Prepared for:
Cornerstone Associates, LLC
209 South 19th St, Suite 600
Omaha, NE 68102
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: 683-001
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.
August 29, 2012
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, Colorado 80521
RE: Final Drainage and Erosion Control Report for
LEGACY SENIOR RESIDENCES
Dear Staff:
Northern Engineering is pleased to submit this Final Drainage and Erosion Control Report for your
review. This report accompanies the Final Compliance Plans submittal for the proposed Legacy
Senior Residences 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 Kevin R. Brazleton, PE
Project Engineer Project Engineer
Legacy Senior Residences
Final 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
III. DRAINAGE DESIGN CRITERIA .................................................................................... 5
A. Regulations ........................................................................................................................................ 5
B. Four Step Process .............................................................................................................................. 5
C. Development Criteria Reference and Constraints ............................................................................ 6
D. Hydrological Criteria ......................................................................................................................... 6
E. Hydraulic Criteria .............................................................................................................................. 6
F. Floodplain Regulations Compliance .................................................................................................. 6
G. Modifications of Criteria ................................................................................................................... 7
IV. DRAINAGE FACILITY DESIGN ..................................................................................... 7
A. General Concept ............................................................................................................................... 7
B. Specific Details .................................................................................................................................. 8
V. CONCLUSIONS .......................................................................................................... 9
A. Compliance with Standards .............................................................................................................. 9
B. Drainage Concept ............................................................................................................................ 10
References ......................................................................................................................... 11
APPENDICES:
APPENDIX A – Hydrologic Computations
APPENDIX B – Hydraulic Computations
B.1 – Storm Sewers
B.2 – Inlets
APPENDIX C – Water Quality Design Computations
APPENDIX D – Offsite Basins Exhibit
APPENDIX E – Erosion Control Report (Storm Water Management Plan)
APPENDIX F – FEMA FIRMette
Legacy Senior Residences
Final Drainage Report
LIST OF TABLES AND FIGURES:
Figure 1 – Aerial Photograph .................................................................................................. 2
Figure 2– Proposed Site Plan .................................................................................................. 3
Figure 3 – Existing Floodplains ............................................................................................... 4
Table 1 – Water Quality Pond Summary .................................................................................. 9
MAP POCKET:
Drainage Exhibit
Legacy Senior Residences
Final Drainage Report 1
I. GENERAL LOCATION AND DESCRIPTION
A. Location
1. Vicinity Map
2. The project site is located in the northwest quarter of Section 12, Township 7 North,
Range 69 West of the 6th Principal Meridian, City of Fort Collins, County of Larimer,
State of Colorado.
3. The project site is located on the west side of Linden Street, the north side of Poudre
Street. The Cache La Poudre River runs just to the north of the project site.
4. The project site lies within the Downtown River District study area (Ayres, 2012), and
is located within Basin 114. This basin has a master planned outfall directly to the
Cache La Poudre river, which runs just north of the project site. Due to the project
site proximity to the river, no detention is required for onsite runoff.
5. Downtown development exists to the south and east of the site. The Aztlan
Community Center exists to the west of the project site.
B. Description of Property
1. The subject property is approximately 1.97 net acres.
Legacy Senior Residences
Final Drainage Report 2
Figure 1 – Aerial Photograph
2. The subject property currently consists of open area. The ground cover generally
consists of gravel and some native seeding. Existing ground slopes are rather gentle
throughout (i.e., 2±%). General topography slopes from southwest to the northeast
towards the Cache La Poudre River.
3. According to the United States Department of Agriculture (USDA) Natural Resources
Conservation Service (NRCS) Soil Survey, the site consists of Paoli fine sandy loam,
which falls into Hydrologic Soil Group B. More site-specific exploration found varying
materials including sandy clay with occasional sand layers and sandy gravel. See the
Geotechnical Engineering Report by Terracon Consultants, Inc. for additional
information.
4. The proposed project will develop the majority of the existing site, constructing a
senior housing center. Parking areas and associated utilities will be constructed. A
water quality pond will be constructed at the northeast corner of the site.
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Final Drainage Report 3
Figure 2– Proposed Site Plan
5. There are no irrigation ditches or related facilities in the vicinity of the project site.
6. The proposed land use is senior housing.
C. Floodplain
1. The subject property is not located in either a FEMA regulatory or City of Fort Collins
designated floodplain. The proposed outfall for the water quality pond is located
outside of the property boundary and lies within the Cache La Poudre 100-year
floodplain and floodway.
2. FEMA places the subject property within the unshaded Zone X Flood Hazard Area,
which constitutes an area determined to be outside the 0.2% annual chance
floodplain.
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Final Drainage Report 4
Figure 3 – Existing Floodplains
3. The Cache La Poudre 100-year and 500-year floodplain exist to the northeast of the
project site. FEMA FIRM Panel Number 979 for Larimer County, Dated June 17,
2008 (Revised May 2, 2012) are referenced in this study. A copy of the FIRMette is
provided in the appendix of this report.
4. The base (100-year) flood elevation in the vicinity of the proposed structure is
4954.8, which is referenced to the City of Fort Collins NGVD 29. The proposed
structure’s finished floor elevation will be set at elevation 4865.25 (FtCollins
NGVD29). The overtopping elevation of the Linden Street bridge is 4859.14
(FtCollins NGVD29).
5. The proposed structure is located outside of the 100-year and 500-year floodplain.
6. The Cache La Poudre half-foot floodway is located outside of the property boundary.
No fill is proposed within the half-foot floodway for construction of the offsite pond
outfall pipe.
7. It is noted that the vertical datum utilized for site survey work is the City of Fort
Collins Benchmark #4-00 (Elevation=4960.55, Ft. Collins NGVD 29).
8. A floodplain use permit and no-rise certification will be required for the offsite pond
outfall pipe within the floodplain.
II. DRAINAGE BASINS AND SUB-BASINS
A. Major Basin Description
1. The project site is located within the Downtown River District study area (Ayres,
2012), and is located within Basin 114Sub-Basin Description
2. The subject property historically drains overland towards the Cache La Poudre River,
Legacy Senior Residences
Final Drainage Report 5
which runs northeast of the site. A more detailed description of the project drainage
patterns follows in Section IV.A.4., below.
3. Developed areas to the southwest of the site historically drain through the project site.
These off-site drainage flows and patterns will be maintained and accounted for with
the proposed development.
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 as athletic facilities by implementing multiple Low Impact Development (LID)
strategies including:
Conserving existing amenities in the site including the existing vegetated areas and
large trees around the perimeter of the site.
Providing large 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. All stormwater runoff from the site will ultimately be
routed to the northeast corner of the site, where it is intercepted and treated in the main
water quality pond prior to exiting the site.
Step 3 – Stabilize Drainageways
There are no major drainageways in 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.
Legacy Senior Residences
Final Drainage Report 6
Step 4 – Implement Site Specific and Other Source Control BMPs.
The proposed project includes a senior housing center which will require the need for site
specific source controls including:
Several localized trash enclosures throughout the site for the disposal of household
waste.
C. Development Criteria Reference and Constraints
The subject property is essentially an "in-fill" development project as the property is
surrounded by currently developed properties. As such, constraints have been
identified during the course of this analysis that will impact the proposed drainage
system including:
Existing elevations along the perimeter of the site will be maintained.
As previously mentioned, overall drainage patterns of the existing site 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 either a FEMA regulatory or a
City of Fort Collins designated floodplain.
4. The proposed project does not propose to modify any natural drainageways.
F. Floodplain Regulations Compliance
1. As previously mentioned, this project is not subject to any floodplain regulations.
However, extra care has been taken to ensure that neither existing nor proposed
structures will suffer damage during the 100-year storm as a result of the proposed
development. The outfall pipe for the proposed water quality pond will involve a
riprap rundown which will convey flows into the Cache La Poudre River. This
Legacy Senior Residences
Final Drainage Report 7
rundown is being designed by Flywater Consulting. Permitting and construction
supervision will be coordinated by Flywater Consulting.
G. Modifications of Criteria
1. The proposed development is not requesting any modifications to criteria at this time.
IV. DRAINAGE FACILITY DESIGN
A. General Concept
1. The main objectives of the project drainage design are to maintain existing drainage
patterns, ensure no adverse impacts to any adjacent properties, and to maintain the
drainage concepts as outlined in the Downtown River District study (Ayres, 2012).
2. Developed areas to the southwest of the site historically drain through the project site.
These off-site drainage flows and patterns will be maintained and accounted for with
the proposed development.
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.
Basin 1
Basin 1 consists of landscaped area to the rear of the proposed building and a portion
of the rooftop. The basin drains west and north into a proposed swale running along
the west side of the proposed building. The proposed swale drains to an existing
swale located to the north of the building. The existing swale drains north to the
Cache La Poudre River.
Basin 2A and 2B
Basins 2A and 2B consist of the rooftop of the proposed building. The basins drain
into a roof drain system to the front and rear of the building. The roof drain system
drains into the water quality pond at the northeast corner of the site.
Basin 3
Basin 3 consists mainly of the proposed parking area and the proposed water quality
pond. The basin drains via surface flow into the proposed water quality pond at the
northeast corner of the site.
The area in the southeast corner of this basin will only be graded and seeded with the
current development. In the future, it is anticipated that this area may be developed.
All runoff and water quality calculations assume a 95% imperviousness for this area to
ensure future use of the area will not be encumbered.
Basin 4
Basin 4 consists mainly of the proposed parking area. The basin drains into a storm
drain system which drains into the proposed water quality pond at the northeast
corner of the site.
Legacy Senior Residences
Final Drainage Report 8
Basin 5
Basin 5 consists of a concrete drive and landscaped area to the south of the building.
The basin drains via surface flow into Poudre Street. A sidewalk chase will capture
the flows from this small basin and direct flows into the proposed swale running along
the west side of the proposed building. The proposed swale drains to an existing swale
located to the north of the proposed building. The existing swale drains north to the
Cache La Poudre River.
Basin 6
Basin 6 consists of landscaped area. The basin drains via surface sheet flow into the
Cache La Poudre River.
Basin 7
Basin 7 consists of landscaped area, and parking lot drive. The basin drains via
surface sheet flow into Linden Street.
Basin OS1
Basin OS1 consists of developed areas to the south of the project site. Runoff from
this basin will follow existing drainage patterns, as stormwater from this basin will be
directed via the proposed swale into the existing swale to the north of the proposed
building. This existing swale is the historic concentration point for flows from this
offsite basin.
Basin OS2
Basin OS2 consists of developed areas to the south of the project site. Runoff from
this basin will be directed via surface flow into the proposed water quality pond at the
northeast corner of the site. Offsite runoff will then be captured in the outlet pipe for
the proposed water quality pond, and be directed into the Cache La Poudre River.
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. Water quality treatment is being provided for the proposed development in the form of
extended detention as previously described.
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.).
Legacy Senior Residences
Final Drainage Report 9
2. Table 1, below, summarizes the water quality information for the proposed water
quality pond.
Table 1 – Water Quality Pond Summary
Water Quality Water Quality
Pond
Spillway Top of Pond
Capture Volume WSEL Elevation Elevation
(AC‐FT) (FT) (FT) (FT)
0.047 4958.55 4959.80 4959.80
3. 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 may be easily accessed by maintenance staff via the gentle
slope provided to the bottom of the pond from the south side.
4. The drainage features associated with the proposed project are all private facilities,
located on private property with the exception of the water quality pond outfall pipe.
The outfall pipe is located within Aztlan Community Center property. A drainage
easement will be dedicated for said outfall pipe to ensure that the stormwater
conveyance outfall line is protected.
5. The proposed outfall pipe requires a riprap rundown to the Cache La Poudre River,
which has been designed in conjunction with river bank stabilization done by others.
There are no other facilities or upgrades needed off-site in order to accommodate the
developed runoff from the proposed development. Placement of the outfall and riprap
will require a no-rise certification for the Cache La Poudre floodway. Pre- and post-
construction survey will be required in order to ensure no fill is placed within the
Cache La Poudre floodway. The tolerance for surveying is 0.01-feet. A floodplain use
permit will be required for construction of this outfall.
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 the Downtown River
District Final Design Report (Ayres, 2012).
3. There are no regulatory floodplains within the proposed development. The outfall pipe
for the proposed water quality pond will involve a riprap rundown which will convey
flows into the Cache La Poudre River. This rundown is being designed by Flywater
Consulting. Permitting and construction supervision will be coordinated by Flywater
Consulting. The rundown is in the Cache La Poudre River floodplain and floodway.
4. The drainage plan and stormwater management measures proposed with the
proposed development are compliant with all applicable State and Federal regulations
governing stormwater discharge.
5. The proposed development is in compliance with Chapter 10 of City Code.
Legacy Senior Residences
Final Drainage Report 10
B. Drainage Concept
1. The drainage design proposed with this project will effectively limit any potential
damage associated with its stormwater runoff by providing an extended detention
water quality pond.
2. The drainage concept for the proposed development is consistent with the Downtown
River District Final Design Report (Ayres, 2012).
Legacy Senior Residences
Final Drainage Report 11
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.
6. Downtown River District Final Design Report, February 2012, Ayres Associates.
7. Geotechnical Engineering Report, Keifer Concrete Storage Yard, February 1, 2011, Terracon
Consultants, Inc.
APPENDIX A
HYDROLOGIC COMPUTATIONS
CHARACTER OF SURFACE:
Runoff
Coefficient
Percentage
Impervious Project: 683-001
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 12300 0.282 0.000 0.080 0.029 0.000 0.174 0.52 0.52 0.65 35%
2a 6711 0.154 0.000 0.000 0.154 0.000 0.000 0.95 0.95 1.00 90%
2b 13422 0.308 0.000 0.000 0.308 0.000 0.000 0.95 0.95 1.00 90%
3 27910 0.641 0.447 0.023 0.000 0.000 0.170 0.76 0.76 0.95 73%
4 23429 0.538 0.447 0.039 0.000 0.000 0.051 0.88 0.88 1.00 90%
5 1549 0.036 0.000 0.022 0.000 0.000 0.014 0.68 0.68 0.85 55%
6 658 0.015 0.000 0.000 0.000 0.000 0.015 0.25 0.25 0.31 0%
7 1104 0.025 0.015 0.000 0.000 0.000 0.015 0.71 0.71 0.89 59%
Overall Onsite to
Pond
Overland Flow, Time of Concentration:
Project: 683-001
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: 683-001
Calculations By:
Date:
From Section 3.2.1 of the CFCSDDC
Rainfall Intensity:
1 1 0.28 6 6 6 0.52 0.52 0.65 2.67 4.56 9.31 0.4 0.7 1.7
2a 2a 0.15 5 5 5 0.95 0.95 1.00 2.85 4.87 9.95 0.4 0.7 1.5
2b 2b 0.31 5 5 5 0.95 0.95 1.00 2.85 4.87 9.95 0.8 1.4 3.1
3 3 0.64 14 14 13 0.76 0.76 0.95 1.95 3.34 7.04 1.0 1.6 4.3
4 4 0.54 5 5 5 0.88 0.88 1.00 2.85 4.87 9.95 1.4 2.3 5.4
5 5 0.04 5 5 5 0.68 0.68 0.85 2.85 4.87 9.95 0.1 0.1 0.3
6 6 0.02 5 5 5 0.25 0.25 0.31 2.85 4.87 9.95 0.01 0.02 0.0
7 7 0.03 5 5 5 0.71 0.71 0.89 2.85 4.87 9.95 0.05 0.09 0.2
3
Overall Onsite to
Pond
(Basin 2-4) 1.64 14 14 13 0.86 0.86 1.00 1.95 3.34 7.04 2.7 4.7 11.6
OS1 OS1 012 12 12 10 040 040 050 209 357 772 01 02 05
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
July 1, 2012
Q C f C i A
OS1 OS1 0.12 12 12 10 0.40 0.40 0.50 2.09 3.57 7.72 0.1 0.2 0.5
OS2 OS2 1.31 16 16 15 0.54 0.54 0.67 1.81 3.08 6.52 1.3 2.2 5.7
APPENDIX B
HYDRAULIC COMPUTATIONS
B.1 – Storm Sewers
B.2 – Inlets
APPENDIX B.1
STORM SEWERS
Hydraflow Plan View
Project File: Storm A 2005.stm No. Lines: 1 07-10-2012
Hydraflow Storm Sewers 2005
Storm Sewer Summary Report Page 1
Line Line ID Flow Line Line Invert Invert Line HGL HGL Minor HGL Dns
No. rate size length EL Dn EL Up slope down up loss Junct line
(cfs) (in) (ft) (ft) (ft) (%) (ft) (ft) (ft) (ft) No.
1 Pipe - (30) (1) 15.90 24 c 89.8 4953.12 4953.57 0.501 4954.53 4955.14 0.56 4955.70 End
Project File: Storm A 2005.stm Number of lines: 1 Run Date: 07-10-2012
NOTES: c = cir; e = ellip; b = box; Return period = 100 Yrs.
Hydraflow Storm Sewers 2005
Hydraulic Grade Line Computations Page 1
Line Size Q Downstream Len Upstream Check JL Minor
coeff loss
Invert HGL Depth Area Vel Vel EGL Sf Invert HGL Depth Area Vel Vel EGL Sf Ave Enrgy
elev elev head elev elev elev head elev Sf loss
(in) (cfs) (ft) (ft) (ft) (sqft) (ft/s) (ft) (ft) (%) (ft) (ft) (ft) (ft) (sqft) (ft/s) (ft) (ft) (%) (%) (ft) (K) (ft)
1 24 15.90 4953.12 4954.53 1.41 2.37 6.71 0.70 4955.23 0.587 89.8 4953.57 4955.14 1.57 2.64 6.01 0.56 4955.70 0.459 0.523 0.470 1.00 0.56
Project File: Storm A 2005.stm Number of lines: 1 Run Date: 07-10-2012
Hydraflow Storm Sewers 2005
Hydraflow Plan View
Project File: Storm B 2005.stm No. Lines: 9 07-10-2012
Hydraflow Storm Sewers 2005
Storm Sewer Summary Report Page 1
Line Line ID Flow Line Line Invert Invert Line HGL HGL Minor HGL Dns
No. rate size length EL Dn EL Up slope down up loss Junct line
(cfs) (in) (ft) (ft) (ft) (%) (ft) (ft) (ft) (ft) No.
1 Pipe - (19) 15.40 18 c 30.6 4956.58 4956.66 0.262 4958.00* 4958.57* 0.59 4959.16 End
2 Pipe - (22) 6.20 18 c 28.3 4956.91 4957.19 0.988 4960.15* 4960.24* 0.14 4960.38 1
3 Pipe - (23) (1) 6.20 18 c 118.1 4957.18 4958.66 1.253 4960.38* 4960.73* 0.28 4961.01 2
4 Pipe - (24) 3.00 10 c 18.9 4958.91 4959.20 1.533 4961.01* 4961.31* 0.35 4961.66 3
5 Pipe - (25) 3.00 10 c 40.3 4959.20 4959.84 1.588 4961.66* 4962.31* 0.47 4962.78 4
6 Pipe - (26) 1.50 8 c 62.8 4959.84 4960.63 1.257 4962.96* 4963.79* 0.20 4963.99 5
7 Pipe - (27) 1.00 8 c 60.1 4960.63 4961.38 1.249 4964.15* 4964.50* 0.10 4964.60 6
8 Pipe - (28) 0.50 6 c 33.3 4961.38 4961.80 1.261 4964.62* 4964.85* 0.10 4964.95 7
9 Pipe - (29) 0.50 6 c 7.5 4961.80 4961.89 1.201 4964.95* 4965.00* 0.10 4965.10 8
Project File: Storm B 2005.stm Number of lines: 9 Run Date: 07-10-2012
NOTES: c = cir; e = ellip; b = box; Return period = 100 Yrs. ; *Surcharged (HGL above crown).
Hydraflow Storm Sewers 2005
Hydraulic Grade Line Computations Page 1
Line Size Q Downstream Len Upstream Check JL Minor
coeff loss
Invert HGL Depth Area Vel Vel EGL Sf Invert HGL Depth Area Vel Vel EGL Sf Ave Enrgy
elev elev head elev elev elev head elev Sf loss
(in) (cfs) (ft) (ft) (ft) (sqft) (ft/s) (ft) (ft) (%) (ft) (ft) (ft) (ft) (sqft) (ft/s) (ft) (ft) (%) (%) (ft) (K) (ft)
1 18 15.40 4956.58 4958.00 1.42 1.73 8.90 1.23 4959.23 1.585 30.6 4956.66 4958.57 1.50 1.77 8.71 1.18 4959.75 1.833 1.709 0.522 0.50 0.59
2 18 6.20 4956.91 4960.15 1.50 1.77 3.51 0.19 4960.34 0.297 28.3 4957.19 4960.24 1.50 1.77 3.51 0.19 4960.43 0.297 0.297 0.084 0.74 0.14
3 18 6.20 4957.18 4960.38 1.50 1.77 3.51 0.19 4960.57 0.297 118 4958.66 4960.73 1.50 1.77 3.51 0.19 4960.92 0.297 0.297 0.351 1.46 0.28
4 10 3.00 4958.91 4961.01 0.83 0.55 5.50 0.47 4961.48 1.600 18.9 4959.20 4961.31 0.83 0.55 5.50 0.47 4961.78 1.599 1.599 0.303 0.75 0.35
5 10 3.00 4959.20 4961.66 0.83 0.55 5.50 0.47 4962.13 1.600 40.3 4959.84 4962.31 0.83 0.55 5.50 0.47 4962.78 1.599 1.599 0.644 1.00 0.47
6 8 1.50 4959.84 4962.96 0.67 0.35 4.30 0.29 4963.25 1.315 62.8 4960.63 4963.79 0.67 0.35 4.30 0.29 4964.08 1.314 1.315 0.826 0.71 0.20
7 8 1.00 4960.63 4964.15 0.67 0.35 2.87 0.13 4964.28 0.584 60.1 4961.38 4964.50 0.67 0.35 2.86 0.13 4964.63 0.584 0.584 0.351 0.75 0.10
8 6 0.50 4961.38 4964.62 0.50 0.20 2.55 0.10 4964.73 0.678 33.3 4961.80 4964.85 0.50 0.20 2.55 0.10 4964.95 0.678 0.678 0.226 1.00 0.10
9 6 0.50 4961.80 4964.95 0.50 0.20 2.55 0.10 4965.05 0.678 7.5 4961.89 4965.00 0.50 0.20 2.55 0.10 4965.10 0.678 0.678 0.051 1.00 0.10
Project File: Storm B 2005.stm Number of lines: 9 Run Date: 07-10-2012
Hydraflow Storm Sewers 2005
Circular
D or Da,
Pipe
Diameter
(ft)
H or Ha,
Culvert
Height
(ft)
W,
Culvert
Width
(ft)
Yt/D Q/D
1.5
Q/D
2.5 Y
t/H Q/WH
0.5
Storm Line B 15.40 1.50 1.00 0.67 8.38 5.59 N/A N/A 4.00 5.59 3.08 6.32 Type L 8.00 6.00 1.5
Storm Line C 2.10 0.83 1.00 1.20 2.78 3.35 N/A N/A 6.70 3.35 0.42 -2.75 Type L 5.00 5.00 1.5
CALCULATIONS FOR RIPRAP PROTECTION AT PIPE OUTLETS
Circular
Pipe
(Figure MD-21)
Rectangular
Pipe
(Figure MD-22) Spec
Width
of
Riprap
(ft)
2*d50,
Depth
of
Riprap
(ft)
for L/2
Froude
Parameter
Q/D
2.5
Max 6.0
or
Q/WH
1.5
Max 8.0
Riprap
Type
(From
Figure
MD-21 or
MD-22)
Project: 683-001
Urban Drainage
pg MD-107
L=
1/(2tanq)*
[At/Yt)-W]
(ft)
APPENDIX B.2
INLETS
Project =
Inlet ID =
Design Information (Input) MINOR MAJOR
Type of Inlet Inlet Type =
Local Depression (additional to continuous gutter depression 'a' from 'Q-Allow') alocal
= 2.00 2.00 inches
Number of Unit Inlets (Grate or Curb Opening) No = 1 1
Water Depth at Flowline (outside of local depression) Flow Depth = 4.0 12.0 inches
Grate Information MINOR MAJOR
Length of a Unit Grate Lo
(G) = 3.00 3.00 feet
Width of a Unit Grate Wo
= 2.00 2.00 feet
Area Opening Ratio for a Grate (typical values 0.15-0.90) Aratio
= 0.31 0.31
Warning 3 Clogging Factor for a Single Grate (typical value 0.50 - 0.70) Cf
(G) = 0.50 0.50
Grate Weir Coefficient (typical value 2.15 - 3.60) Cw
(G) = 3.60 3.60
Grate Orifice Coefficient (typical value 0.60 - 0.80) Co
(G) = 0.60 0.60
Curb Opening Information MINOR MAJOR
Length of a Unit Curb Opening Lo
(C) = 3.00 3.00 feet
Height of Vertical Curb Opening in Inches Hvert
= 6.50 6.50 inches
Height of Curb Orifice Throat in Inches Hthroat
= 5.25 5.25 inches
Angle of Throat (see USDCM Figure ST-5) Theta = 0.00 0.00 degrees
Side Width for Depression Pan (typically the gutter width of 2 feet) Wp
= 2.00 2.00 feet
Clogging Factor for a Single Curb Opening (typical value 0.10) Cf
(C) = 0.10 0.10
Curb Opening Weir Coefficient (typical value 2.3-3.6) Cw
(C) = 3.70 3.70
Curb Opening Orifice Coefficient (typical value 0.60 - 0.70) Co
(C) = 0.66 0.66
MINOR MAJOR
Total Inlet Interception Capacity (assumes clogged condition) Qa
= 1.4 9.2 cfs
WARNING: Inlet Capacity less than Q Peak for Minor and Major Storms Q PEAK REQUIRED
= 2.0 16.0 cfs
Warning 1: Dimension entered is not a typical dimension for inlet type specified.
Warning 3: Clogging factor is not in the recommended value for inlet type specified.
INLET IN A SUMP OR SAG LOCATION
683-001
Combo Inlet
Denver No. 16 Combination
H-Vert
H-Curb
W
Lo (C)
Lo (G)
Wo
WP
UD Inlet 3.1-comboinlet, Inlet In Sump 7/9/2012, 2:55 PM
Area Inlet Performance Curve:
Governing Equations:
At low flow depths, the inlet will act like a weir governed by the following equation:
* where P = 3.1416*Dia.of grate
* where H corresponds to the depth of water above the flowline
At higher flow depths, the inlet will act like an orifice governed by the following equation:
* where A equals the open area of the inlet grate
* where H corresponds to the depth of water above the centroid of the cross-sectional area (A)
The exact depth at which the inlet ceases to act like a weir, and begins to act like an orifice is unknown.
However, what is known, is that the stage-discharge curves of the weir equation and the orifice equation
will cross at a certain flow depth. The two curves can be found below:
If H > 1.792 (A/P), then the grate operates like an orifice; otherwise it operates like a weir.
Input Parameters:
Type of Grate: PERFORATED MANHOLE COVER
Diameter of Grate (ft): 1.5
Open Area of Grate (ft2): 1.32
Flowline Elevation (ft): 4962.18
Reduction Factor: 50%
Depth vs. Flow:
Depth Above Inlet (ft)
Elevation
(ft)
Shallow
Weir Flow
(cfs)
Orifice
Flow
(cfs)
Actual
Flow
(cfs)
0.00 4962.18 0.00 0.00 0.00
0.10 4962.28 0.22 1.12 0.22
0.20 4962.38 0.63 1.59 0.63
0.30 4962.48 1.16 1.94 1.16
0.40 4962.58 1.79 2.24 1.79
0.50 4962.68 2.50 2.51 2.50
0.60 4962.78 3.29 2.75 2.75
0.70 4962.88 4.14 2.97 2.97
0.80 4962.98 5.06 3.17 3.17
0.00
1.00
2.00
3.00
4.00
5.00
6.00
0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90
Discharge (cfs)
Stage (ft)
Stage - Discharge Curves
Weir Flow
Orifice Flow
Q 3 . 0 P H 1 . 5
Q 0 . 67 A ( 2 gH ) 0 . 5
APPENDIX C
WATER QUALITY DESIGN COMPUTATIONS
WATER QUALITY POND DESIGN CALCULATIONS
Water Quality Pond
Project: 683-001
By: ATC
Date: 8.15.12
REQUIRED STORAGE & OUTLET WORKS:
BASIN AREA = 1.640 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS PERCENT = 83.00 <-- INPUT from impervious calcs
BASIN IMPERVIOUSNESS RATIO = 0.8300 <-- CALCULATED
WQCV (watershed inches) = 0.348 <-- Determined from Figure 3-2, VOL 3, CH 3.0
WQCV (ac-ft) = 0.057 <-- CALCULATED from Equation EDB-1,
VOL 3, CH 4, T-5
WQ Depth (ft) = 2.400 <-- INPUT from stage-storage table
AREA REQUIRED PER ROW, a (in
2
) = 0.178 <-- CALCULATED from Equation EDB-3,
VOL 3, CH 4, T-5
CIRCULAR PERFORATION SIZING:
dia (in) = 0.500 <-- INPUT from Figure 5
n = 7.000 <-- INPUT from Figure 5
t (in) = 0.500 <-- INPUT from Figure 5
number of rows = 1.000 <-- CALCULATED from WQ Depth and row spacing
STAGE STORAGE TABLE
ELEV
AREA
(sq. ft.)
DEPT
H
(ft)
AVG END
INC. VOL.
(cu. ft.)
AVG END
TOTAL VOL.
(cu. ft.)
CONIC
INC. VOL.
(cu. ft.)
CONIC
TOTAL VOL.
(cu. ft.)
4,956.200 27.12 N/A N/A 0.00 N/A 0.00
4,956.400 94.03 0.200 12.12 12.12 11.44 11.44
4,956.600 231.63 0.200 32.57 44.68 31.55 42.99
4,956.800 433.73 0.200 66.54 111.22 65.49 108.48
4,957.000 602.32 0.200 103.60 214.82 103.14 211.62
4,957.200 750.71 0.200 135.30 350.12 135.03 346.66
4,957.400 940.40 0.200 169.11 519.23 168.76 515.41
4,957.600 1,193.50 0.200 213.39 732.62 212.89 728.30
4,957.800 1,502.81 0.200 269.63 1002.26 269.04 997.34
4,958.000 1,790.19 0.200 329.30 1331.56 328.88 1326.22
4,958.200 2,064.87 0.200 385.51 1717.06 385.18 1711.40
4,958.400 2,305.82 0.200 437.07 2154.13 436.85 2148.24
4,958.600 2,507.06 0.200 481.29 2635.42 481.15 2629.39
4,958.800 2,710.19 0.200 521.73 3157.14 521.59 3150.98
4,959.000 2,903.82 0.200 561.40 3718.54 561.29 3712.27
4,959.200 3,104.03 0.200 600.78 4319.33 600.67 4312.95
4,959.400 3,313.15 0.200 641.72 4961.05 641.60 4954.55
4,959.600 3,532.70 0.200 684.59 5645.63 684.47 5639.02
4,959.800 3,835.40 0.200 736.81 6382.44 736.60 6375.62
D:\Projects\683-001\Dwg\3D Data_683-001\Proposed\683-001_Proposed.dwg, 6/30/2012 10:07:26 AM, 1:33.0539
Pond Overflow Box Calculations
This spreadsheet uses the weir equation and the orifice equation to determine the amount
of flow entering the overflow box. The results of the weir equation are compared to the orifice
equation and the calculated lower flow of the two equations is selected.
Weir Equation: Q=CLH^3/2
Where: C=Weir Coefficient
L=Weir Length (only front and back walls of the box are used-sides are neglected)
H=Operating Head (note that front weir has more operating head due to slope in box)
Orifice Equation: Q=CoA(2gH)^1/2
Where: Co=Orifice Coefficient
A=Open Area of Orifice
H=Operating Head(note that average operating head taken from middle of box)
Weir Parameters: Orifice Parameters
Elev. Front Wall= 4958.55 Elev. of middle of box= 4959
Elev. Back Wall= 4959.43 Orifice Coefficient= 0.65
Weir Coefficient= 3.20 Area of Box= 6.7
Weir Length= 5.5 Open Area Ratio= 0.75
Blockage Factor= 0.80 Blockage Factor= 0.8
Weir Calculations: Orifice Calculations:
Water Operating Operating Calculated Calculated Total Operating Calculated Flow Selected
Surface Head on Head on Flow Flow Flow Head on Flow
Elevation Front Wall Back Wall Front Wall Back Wall Orifice
(FT) (FT) (FT) (CFS) (CFS) (CFS) (FT) (CFS) (CFS)
4958.55 0.00 0.00 0.00 0.00 0 0 0 0.00
4958.75 0.20 0.00 1.26 0.00 1.26 0 0 0.00
4959 0.45 0.00 4.25 0.00 4.25 0 0 0.00
4959.25 0.70 0.00 8.25 0.00 8.25 0.25 10.4846116 8.25
4959.5 0.95 0.07 13.04 0.26 13.30 0.5 14.82748 13.30
4959.8 1.25 0.37 19.68 3.17 22.85 0.8 18.7554434 18.76
APPENDIX D
OFFSITE BASINS EXHIBIT
APPENDIX E
EROSION CONTROL REPORT (STORM WATER MANAGEMENT PLAN)
Stormwater Management Plan
for
LEGACY SENIOR RESIDENCES
Fort Collins, Colorado
August 29, 2012
Prepared for:
Cornerstone Associates, LLC
209 South 19th St, Suite 600
Omaha, NE 68102
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: 683-001
ADDRESS:
200 S. College Ave. Suite 10
Fort Collins, CO 80524
PHONE: 970.221.4158
FAX: 970.221.4159
WEBSITE:
www.northernengineering.com
August 29, 2012
Cornerstone Associates, LLC
209 South 19th St, Suite 600
Omaha, NE 68102
RE: Stormwater Management Plan
Legacy Senior Residences
To whom it may concern:
Northern Engineering Services, Inc. is pleased to submit this Stormwater Management Plan for Legacy Senior
Residences. This report outlines Best Management Practices (BMPs) to be implemented with the proposed
construction in order to minimize potential pollutants in stormwater discharges.
We have prepared this report to accompany the Colorado Department of Public Health and Environment
General Permit for Stormwater Discharge Associated with Construction Activities (aka, Stormwater Discharge
Permit or SDP). The General Permit No. for this SDP is COR-0300000. A copy of the issuance cover letter
can be found in the Appendix D of this document.
Please note: this Stormwater Management plan (including the Site Maps) is not a static document. It is a
dynamic device that should be kept current and logged as construction takes place. As such, this version was
prepared to facilitate initial plan approvals and permitting, but does not necessarily reflect the final version, or
the transitions throughout the construction process. As the site develops and changes, the Contractor is
expected and encouraged to make changes to what is contained herein so that the SWMP works as effectively
and efficiently as possible. It shall be the responsibility of the SWMP Administrator and/or the permit holder
(or applicant thereof) to ensure the plan is properly maintained and followed.
If you should have any questions or comments as you review this report, please feel free to contact us at your
convenience.
Sincerely,
NORTHERN ENGINEERING SERVICES, INC.
Aaron Cvar, PE
Legacy Senior Residences
Stormwater Management Plan
TABLE OF CONTENTS
Vicinity Map
1.0 General Requirements ............................................................................................... 1
1.1 Objectives .................................................................................................................. 1
1.2 SMWP Availability ...................................................................................................... 1
1.3 Definitions.................................................................................................................. 1
1.4 Additional Permitting ................................................................................................... 1
2.0 Narrative Site Description .......................................................................................... 2
2.1 Existing Site Description .............................................................................................. 2
2.2 Nature of Construction Activity ..................................................................................... 2
2.3 Sequence of Major Activities ......................................................................................... 2
2.4 Site Disturbance ......................................................................................................... 3
2.5 Existing Data .............................................................................................................. 3
2.6 Existing Vegetation ...................................................................................................... 3
2.7 Potential Pollution Sources ........................................................................................... 3
2.8 Non-stormwater discharges .......................................................................................... 4
2.9 Receiving Waters ........................................................................................................ 4
3.0 Stormwater Management Controls .............................................................................. 5
3.1 SWMP Administrator ................................................................................................... 5
3.2 Best Management Practices (BMP’s) for Stormwater Pollution Prevention .......................... 5
3.3 Structural Practices for Erosion and Sediment Control ..................................................... 5
3.4 Non-Structural Practices for Erosion and Sediment Control .............................................. 8
3.5 Phased BMP Installation ............................................................................................ 10
3.6 Material Handling and Spill Prevention ........................................................................ 10
3.7 Dedicated Concrete or Asphalt Batch Plant .................................................................. 11
3.8 Vehicle Tracking Control ............................................................................................ 11
3.9 Waste Management and Disposal ............................................................................... 11
3.10 Groundwater and Stormwater Dewatering .................................................................... 12
4.0 Final Stabilization and Long-Term Stormwater Management ........................................ 13
4.1 Final Stabilization ..................................................................................................... 13
4.2 Long-Term Stormwater Management ........................................................................... 13
5.0 Inspection, Maintenance and Record Keeping ............................................................ 14
5.1 BMP Inspection ........................................................................................................ 14
5.2 BMP Maintenance .................................................................................................... 14
5.3 Record Keeping ........................................................................................................ 14
6.0 Additional SWMP and BMP Resources ...................................................................... 16
References …………………………………………………………………………………………………….17
Legacy Senior Residences
Stormwater Management Plan
LIST OF TABLES:
Table 1 – Native Grass Seed Mix ............................................................................................ 8
Table 2 – Preliminary Permit and Construction Schedule for The Grove at Fort Collins ................ 10
APPENDICES:
APPENDIX A – Site Maps
APPENDIX B – Erosion Control Details
APPENDIX C – Landscape Plan
APPENDIX D – Copies of Permits/Applications
APPENDIX E – Stormwater Management Plan Inspection Log
APPENDIX F – Contractor Inserts (as needed)
APPENDIX G – Contractor Inserts (as needed)
Legacy Senior Residences
Stormwater Management Plan 1
1.0 General Requirements
1.1 Objectives
The objective of a Stormwater Management Plan (SWMP) is to identify all potential sources of
pollution likely to occur as a result of construction activity associated with the site construction, and
to describe the practices that will be used to reduce the pollutants in stormwater discharges from
the site. The SWMP must be completed and implemented at the time the project breaks ground,
and revised as necessary as construction proceeds to accurately reflect the conditions and practices
at the site.
This report summarizes the Stormwater Management Plan for the construction activity that will
occur with proposed project as well. This plan has been prepared according to regulations of the
Colorado Department of Public Health and Environment (CDPHE), Water Quality Control Division.
1.2 SMWP Availability
This report is intended to remain on the aforementioned construction site to allow for maintenance
and inspection updates, and for review during inspection.
1.3 Definitions
BMP – Best Management Practice encompassing a wide range of erosion and sediment control
practices, both structural and non-structural in nature, which are intended to reduce or eliminate
any possible water quality impacts from stormwater leaving a construction site.
Erosion Control BMPs – Practices that PREVENT the erosion of soil, such as minimizing the amount
of disturbed area through phasing, temporary stabilization, and preserving existing vegetation
Sediment Control BMP’s – Practices to REMOVE sediment from runoff, such as sediment basins,
silt fence, or inlet protection.
Non-structural BMP’s – The implementation of methods, practices, and procedures to minimize
water quality impacts, such as the preservation of natural vegetation, preventive maintenance and
spill response procedures.
Structural BMP’s – Physical devices that prevent or minimize water quality impacts, such as
sediment basins, inlet protection, or silt fence.
1.4 Additional Permitting
As mentioned above, this Stormwater Management Plan is associated with the Colorado
Department of Public Health and Environment Stormwater Permit that is issued by the Water
Quality Control Division of the CDPHE. Additional Environmental permitting not described in this
report will likely be required as a part of this project. An example is the Construction Dewatering
Permit for groundwater, which will be discussed later. Another example is the Air Pollution
Emission Notice (APEN). The CDPHE website contains links to both of these permits, as well as
many other potential permits. The Contractor is responsible for ensuring the proper permits are
acquired.
Legacy Senior Residences
Stormwater Management Plan 2
2.0 Narrative Site Description
2.1 Existing Site Description
The project site is located in the northwest quarter of Section 12, Township 7 North, Range 69
West of the 6th Principal Meridian, City of Fort Collins, County of Larimer. The project site is
located on the west side of Linden Street, the north side of Poudre Street. The Cache La Poudre
River runs just to the north of the project site. The subject property is approximately 1.97 net
acres.
2.2 Nature of Construction Activity
The proposed project will develop the majority of the existing site, constructing a senior housing
center. Parking areas and associated utilities will be constructed. A water quality pond will be
constructed at the northeast corner of the site.
2.3 Sequence of Major Activities
To complete the project, many basic construction activities will take place. The project will begin
by stripping the site of topsoil, followed by overlot grading. The installation of utilities will occur
next, including water, sewer, storm sewer, and an underdrain system. Once overlot grading is
complete, and utilities have been installed, it is anticipated that construction of the building
foundations will begin. While building foundations are being constructed, curb and gutter will be
installed, followed by asphalt paving of the drives and parking areas. Vertical construction of the
buildings is expected to commence once the public infrastructure has been inspected by the city.
The final stages of construction will be fine grading of the areas around the buildings, and the
installation of landscaping throughout the project.
Legacy Senior Residences
Stormwater Management Plan 3
2.4 Site Disturbance
The entire project boundary, 1.97 acres. However, the total disturbance area affected by the
various construction activities associated with this project, particularly grading, is larger,
encompassing approximately 2.3 acres.
2.5 Existing Data
In order to complete the associated construction plans, a topographical survey of the site was
completed. This survey consisted of field measurements made by Northern Engineering. Field
surveys were completed the winter of 2012.
In addition to the field survey, the Natural Resources Conservation Service (NRCS) Soil Survey was
used to determine existing soil types found on-site. According to the NRCS Soil Survey, the site
consists of Paoli fine sandy loam, which falls into Hydrologic Soil Group B.
More site-specific exploration found varying materials including sandy clay with occasional sand
layers and sandy gravel Please see the Geotechnical Engineering Report by Terracon Consultants,
Inc. for additional information.
2.6 Existing Vegetation
The existing site vegetation consists primarily of native and non-native grasses. These grasses
naturally grow in clumps, which inevitably leads to some bare areas. In general, the site has
approximately 50% vegetative cover, which allows minimum ground erosion. It is highly
recommended that pre-construction photos be taken to clearly document vegetative conditions
prior any disturbance activities.
2.7 Potential Pollution Sources
As is typical with most construction sites, there are a number of potential pollution sources which
could affect water quality. It is not possible for this report to identify all materials that will be used
or stored on the construction site. It is the sole responsibility of the Contractor to identify and
properly handle all materials that are potential pollution sources. The following are some common
examples of potential pollution sources:
Exposed and stored soils
Management of contaminated soils
Off-site tracking of soils and sediment
Loading and unloading operations
Outdoor storage of building materials, fertilizers, chemicals, etc.
Vehicle and equipment maintenance and fueling
Significant dust or particulate generating processes
Routine maintenance activities involving fertilizers, pesticides, detergents, fuels, solvents, oils, etc.
On-site waste disposal practices (waste piles, dumpsters, etc.)
Concrete truck/equipment washing
Non-industrial waste sources that may be significant, such as worker trash and portable toilets
Uncovered trash bins
Other areas or procedures where potential spills can occur
Stockpiling of materials that can be transported to receiving waterway(s)
Legacy Senior Residences
Stormwater Management Plan 4
2.8 Non-stormwater discharges
The Stormwater Construction Permit only covers discharges composed entirely of stormwater.
Exceptions include emergency fire fighting activities, landscape irrigation return flow,
uncontaminated springs, construction dewatering (caused by storm events) and concrete washout
water. Proper treatment and use of BMPs is still required for these exceptions when available.
The discharge of pumped stormwater, ONLY, from excavations, ponds, depressions, etc. to surface
waters, or to a municipal storm sewer system is allowed by the Stormwater Construction Permit, as
long as the dewatering activity and associated BMPs are identified in the SWMP are implemented
in accordance with the SWMP.
Aside from the exceptions noted above, non-stormwater discharges must be addressed in a separate
permit issued for that discharge. If groundwater is encountered, and dewatering is required, a
Construction Dewatering Permit must be acquired from the Colorado Department of Public Health
and Environment. A copy of the dewatering permit application and instructions has been included
with Appendix D.
2.9 Receiving Waters
Stormwater runoff from the project area will generally sheet flow into a system storm drains and will
be captured by a water quality pond on the northeast corner of the site. The pond will release into
the Cache La Poudre River, which is just north of the project site. Proposed drainage patterns
follow the historic drainage course.
Legacy Senior Residences
Stormwater Management Plan 5
3.0 Stormwater Management Controls
3.1 SWMP Administrator
A SWMP Administrator must be designated in conjunction with the Stormwater Permit. This person
shall be responsible for developing, implementing, maintaining, and revising the SWMP. The
SWMP Administrator will also be the contact for all SWMP-related issues and will be the person
responsible for the accuracy, completeness, and implementation of the SWMP. The Administrator
should be a person with authority to adequately manage and direct day-to-day stormwater quality
management activities at the site.
The SWMP Administrator for this site is to be determined:
Name :
Company:
Phone:
E-mail
3.2 Best Management Practices (BMP’s) for Stormwater Pollution Prevention
Beginning from mobilization, and throughout the entire construction of the buildings, erosion control
devices shall be installed to ensure minimal pollutant migration. These erosion control devices may
be installed in phases, or not at all, depending on actual conditions encountered at the site. It is
the responsibility of the Contractor to make the ultimate determination as to what practices should
be employed and when.
Best Management Practices (BMPs) are loosely defined as a method, activity, maintenance
procedure, or other management practice for reducing the amount of pollution entering a water
body. The term originated from rules and regulations in Section 208 of the Clean Water Act.
Details for Structural and Non-Structural BMPs have been included in Appendix B. These details
should be used for additional information on installation and maintenance of BMPs specified in this
report. It is also intened to serve as a resource for additional BMPs that may be appropriate for the
site that have not specifically been mentioned in the report.
3.3 Structural Practices for Erosion and Sediment Control
Structural BMPs are physical devices that are implemented to prevent erosion from happening or to
limit erosion once it occurs. These devices can be temporary or permanent, and installation of
individual components will vary depending on the stage of construction.
A table depicting construction sequence and BMP application/removal has been placed on the
“Dynamic Site Plan” to help document the implementation of these BMPs. Refer to the Stormwater
Management Plan Static Site Plan in the Appendix for the assumed location of all BMPs.
Construction Details for Temporary BMPs are located in the Appendix for reference.
Again, the final determination for which BMP’s will be installed, where they will be located and
when they will be installed shall be made by the Contractor, along with all documentation
throughout the construction process.
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Stormwater Management Plan 6
Silt Fencing (Phase I)
Silt fencing shall be provided to prevent migration of sediment off-site or into adjacent
properties. All silt fencing shall be installed prior to any land disturbing activity (stockpiling,
stripping, grading, etc.). Silt fencing is to be installed prior to site excavation or earthwork
activities.
Inspections of the silt fence should identify tears or holes in the material, and should check
for slumping fence or undercut areas that allow flows to bypass the fencing. Damaged
sections of fencing should be repaired or replaced to ensure proper functioning. Sediment
accumulated behind the silt fence should be removed to maintain BMP effectiveness,
typically before it reaches a depth of 6 inches.
At a minimum, it is suggested that silt fencing shall be located along the northern boundary
of the disturbance area to prevent sediment from leaving the site and entering Cache La
Poudre.
Sediment Control Log – aka “Straw Wattles” (Phase I)
A Sediment Control Log is a linear roll made of natural materials, such as straw, coconut
fiber, or other fibrous material trenched into the ground and held with a wooden stake.
Sediment Control Logs can be used in many instances. Examples include perimeter control
for stockpiles, as part of inlet protection designs, as check dams in small drainage ways, or
on disturbed slopes to shorten flow lengths.
Sediment Control Logs should be inspected for excess sediment accumulation. Sediment
should be removed prior to reaching half the height of the log.
At a minimum, Sediment Control Logs should be used around soil stockpiles and for inlet
protection in unpaved areas of the site.
Vehicle Tracking Control Pads (Phase I)
Vehicle tracking control pads shall be provided to minimize tracking of mud and sediment
onto paved surfaces and neighboring roadways. All vehicle tracking control pads shall be
installed prior to any land disturbing activity (stockpiling, stripping, grading, etc.). Location
of vehicle tracking control pads will be located at any and all existing and future vehicle
accesses being used during any of the construction phases. These locations will primarily be
dictated by gates or openings in the temporary construction fencing that is expected to be
installed. Vehicle tracking control pads are to be installed prior to site excavation or
earthwork activities.
Vehicle tracking pads should be inspected for degradation and aggregate material should be
replaced as needed. If the area becomes clogged with water, excess sediment should be
removed. Aggregate material should remain rough, and at no point should aggregate be
allowed to compact in a manner that causes the tracking pad to stop working as intended.
Suggested locations for vehicle tracking pads are at the access to the site from the existing
Linden Street on the east.
Curb Inlet Protection (Phase I & II)
Curb inlet protection shall be provided for existing curb inlets to prevent sediment transport
from adjacent earthwork disturbance. Installation of these filters shall occur before adjacent
earthmoving activities (Phase I implementation). Wattle type filters are to be implemented
for new and existing inlets where asphalt is not yet installed. For these inlets, if pavement is
constructed adjacent to the structure or if the area adjacent to the inlet is changed such that
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Stormwater Management Plan 7
the wattle type filter is no longer effective, it shall be the responsibility of the Contractor to
ensure that an appropriate method is used instead. For example, the wattle filter could be
reused, or a gravel-block inlet filter may be installed. It will be left to the discretion of the
Contractor as to whether replacement of any inlet filter is necessary.
Inlet protection should be inspected regularly for tears that can result in sediment entering
an inlet. Inlet protection should also be inspected for sediment accumulation upstream of
the inlet, and sediment should be removed when the less than half of the capacity is
available, or per manufacturer specifications.
The Contractor shall also provide inlet protection for all newly constructed inlets as they are
built (Phase II implementation).
Concrete Washout Area (Phase II)
A concrete washout should be provided on the site. The washout can be lined or unlined
excavated pits in the ground, commercially manufactured prefabricated containers, or
aboveground holding areas. The concrete washout must be located a minimum of 400 feet
from any natural drainage way or body of water, and at least 1000 feet from any wells or
drinking water sources. Washout areas should not be located in an area where shallow
groundwater may be present. Contractor shall clearly show the desired location and access
to the Concrete Washout Area on the Stormwater Management Plan - Dynamic Site Plan.
Contractor shall place a Vehicle Tracking Pad if the selected location for the Concrete
Washout Area is detached from pavement. Clear signage identifying the concrete washout
should also be provided.
The Concrete Washout Area should be inspected regularly. Particular attention should be
paid to signage to ensure that the area is clearly marked. Confirmation that the washout is
being used should also be noted to ensure that other undesignated areas of the site are not
being used incorrectly as a concrete washout.
Riprap (Phase II)
Considered a permanent BMP, riprap pads will be provided to prevent long term erosion and
scour at the outlets of storm lines and other critical scour locations. Riprap pads will be
placed at specified storm sewer outfalls and other critical locations as soon as possible
following construction of the respective facility. The riprap pads will be inspected regularly
and any required maintenance will be performed as discussed in subsequent sections.
Permanent/Established Vegetation (Phase IV)
Permanent or established vegetation and landscaping is considered a permanent form of
sediment and erosion control for common open spaces, steep slopes and areas not exposed
to prolonged scour velocities, or acute incipient motion bed shear stresses that will create
soil erosion, rill formation and subsequent sediment transport. Areas where the previous
conditions apply will contain sufficient permanent BMPs, such as riprap and Erosion Control
Blankets. Permanent vegetation shall conform with the approved Landscape Plan. In
particular, native areas shall be revegetated with native grass and forb species. Seed,
Mulch, and tackifier shall be applied in phases throughout construction.
Permanent/Established vegetation defines Phase IV of development.
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Stormwater Management Plan 8
Table 1 – Native Grass Seed Mix
Preferred
Varieties
Seeded Rate
(lbs. per acre,
drilled)
PLS
Seeded/acre
Leymus Cinereus Great Basin Wilrye Mangar 3 285,000
Nassella Viridula Green Needlegrass Lodorm 2 362,000
Chnatherum Hymenoides Indian Ricegrass Paloma, Nezpar 1 188,000
Elymus Trachycaulus Slender Wheatgrass Primar, Revenue 2 320,000
Elymus Lanceolatus Thickspike Wheatgrass Critana 3 580,500
Pascopyrum Smithii Western Wheatgrass Arriba, Barton 4 504,000
Totals 15 2,239,500
Species
Extended Detention Basins – aka Water Quality Pond (Phase IV)
Extended Detention Basins serve to remove sediment and other pollutants from the
developed runoff, and are designed for a 40-hour dry extended detention basin. The 40-
hour release time is considered to be sufficient to allow for settlement of most suspended
solids and follows the design procedure specified by the Urban Storm Drainage Criteria
Manual, Volume 3. The Extended Detention Basins typically have a water quality outlet
structure and a water quality plate that restricts flow from the pond to allow enough time
(generally 40 hours) for particulates to precipitate out of the developed stormwater. Regular
maintenance and cleaning of the water quality plate and structure will be required to remove
trash and organic material.
3.4 Non-Structural Practices for Erosion and Sediment Control
Non-Structural BMPs are practices or activities that are implemented to prevent erosion from
happening or to limit erosion once it occurs. These BMPs can be a practice resulting in physical
change to the site, such as mulching or slope stabilization. They can also result in behavioral
changes on the site, such as changes to construction phasing to minimize exposure to weather
elements, or increased employee awareness gained through training.
Protection of Existing Vegetation (Phases I-IV)
Protection of existing vegetation on a construction site can be accomplished through
installation of a construction fence around the area requiring protection. In cases where
upgradient areas are disturbed, it may also be necessary to install perimeter controls to
minimize sediment loading to sensitive areas such as wetlands.
Trees that are to remain after construction is complete must be protected. Most tree roots
grow within the top 12”-18” of soil, and soil compaction is a significant threat to tree
health. As such, particular care should be taken to avoid activities within the drip-line of
the tree. Direct equipment damage should also be prevented. The most effective way to
ensure the health of trees is to establish a protection zone at the drip-line of the tree to
prevent unintended activity in the area directly surrounding the tree.
Fencing should be inspected and repaired when needed. If damage occurs to a tree, an
arborist should be consulted on how to care for the tree. If a tree is damage beyond repair,
the City Forester should be consulted on remediation measures.
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Stockpile Management (Phases I-III)
Stockpile management should be utilized to minimize erosion and sediment transport from
soil stockpiles. In general, soil stockpiles should be located a minimum of 100 feet from
any drainage way and 50 feet from any storm sewer inlets. Where practical, choose a
stockpile location that will remain undisturbed for the longest period of time as the phases
of construction progress. Sediment control BMPs should be placed around the perimeter of
the stockpile, and a designated access point on the upstream side of the stockpile should be
identified. BMPs such as surface roughening, temporary seeding, mulching, erosion control
blankets, or soil binders should be used to stabilize the stockpile surface.
As a part of stockpile management, regular inspections of the perimeter controls should be
completed. If BMPs have been utilized to stabilize the surface of the stockpile, they should
be inspected and repaired as needed.
Wind Erosion/Dust Control (Phase I-IV)
Wind Erosion and Dust Control BMP’s help to keep soil particles from entering the air as a
result of land disturbing construction activities. Examples include use of a water truck or
irrigation/sprinkler system to wet the top layer of disturbed soil, seeding and mulching, soil
binders, or wind fences.
If a water truck or irrigation/sprinkler system is utilized, monitoring to ensure that sufficient
water is applied is crucial to ensuring soil particles don’t become airborne. Equally
important is monitoring for overwatering, as too much water can lead to increased erosion.
Good Housekeeping Practices (All phases)
Good housekeeping practices that will prevent pollution associated with solid, liquid, and
hazardous construction-related materials and wastes should be implemented throughout the
project. Examples of good housekeeping include providing an appropriate location for waste
management containers, establishing proper building material staging areas, designating
paint and concrete washout areas, establishing proper equipment/vehicle fueling and
maintenance practices. Development of a spill prevention and response plan is another
example of Good Housekeeping practices that should be used on the project. The following
items are detailed examples of some of the good housekeeping practices that should be
utilized throughout the project. It should be noted that a complete list of practices and
detailed discussion regarding good housekeeping has been included with Appendix B, sheets
GH-1 – GH-6.
Street Sweeping and Vacuuming – Street sweeping and vacuuming should be used to
remove sediment that has been tracked onto adjacent roadways. Roadways should be
inspected at least once a day, and sediment should be removed as needed. A check of inlet
protection should be completed after sweeping to ensure nothing was displaced during
sweeping operations.
Waste Management – Designate trash and bulk waste collection areas on-site. When
possible, materials should be recycled. Hazardous material waste should be segregated
from other solid waste. Waste collection areas should be located away from streets, gutters,
watercourses, and storm drains. Dumpsters should be located near site entrances to
minimize traffic on disturbed soils, and they should be placed on a level soil surface.
Establish Proper Building Material Handling and Staging areas – Clearly designate site areas
for staging and storage of building materials. Provide appropriate BMPs to ensure that spills
or leaks are contained.
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Establish Proper Equipment/Vehicle Fueling and Maintenance Practices – If needed, create a
clearly designated on-site fueling and maintenance area that is clean and dry. Provide
appropriate BMPs to ensure that spills or leaks are contained.
3.5 Phased BMP Installation
It is important to recognize the four (4) major Development Phases as defined by the State of
Colorado’s Stormwater Discharge Permit (SDP). These four development phases (referred to as
Sequencing by the City of Fort Collins) have been distinguished to aid in the appropriate timing of
installation/implementation of BMPs at different stages of the construction process. These phases
are described as follows:
Phase I – Grading Stage; BMPs for initial installation of perimeter controls
Phase II – Infrastructure Stage; BMPs for utility, paving and curb installation
Phase III – Vertical Construction Stage; BMPs for individual building construction.
Phase IV – Permanent BMPs and final site stabilization.
The following is a rough estimate of the anticipated construction sequence for site improvements.
The schedule outlined below is subject to change as the project progresses and as determined by
the General Contractor.
Table 2 – Preliminary Permit and Construction Schedule
BEGINNING ENDING
BMP‐PHASE
OF
TASK DATE DATE DEVELOPMENT
Development Construction Permit
Issued by City of Fort Collins Aug. 2012 I
Overlot Grading Aug. 2012
Sept.
2012 I
Utility Installation Sept. 2012
Nov.
2013 II
Building Construction Nov.2012
May
2013 III
Final Stabilization May 2013
Sept.
2013 IV
Included in the back map pockets are five Site Plans: a “Static” Site Plan and four “Dynamic” Site
Plans (one for each phase of construction). The “Static” plan serves to display the overall
management plan all at once. However, proper implementation of BMPs does not occur at once,
and certain BMPs may move location in the construction process; therefore, the “Dynamic” Site
Plans are intended for the Contractor to write in the BMP symbols to document the location and
time the BMPs are installed and maintained throughout the entire construction process.
3.6 Material Handling and Spill Prevention
Potential pollution sources, as discussed in earlier sections, are to be to be identified by the
Contractor. Spill prevention procedures are to be determined and put in place prior to construction
by the Contractor. A spill and flooding response procedure must also be determined and put in
place prior to construction by the Contractor. Additionally, steps should be taken to reduce the
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potential for leaks and spills to come in contact with stormwater runoff, such as storing and
handling toxic materials in covered areas or by storing chemicals within berms or other secondary
containment devices.
A notification procedure must be put in place by the Contractor, by which workers would first notify
the site construction superintendent, who would then notify the SWMP Administrator. Depending
on the severity of the spill, the site construction superintendent and SWMP Administrator would
possibly notify the Colorado Department of Public Health and Environment - Water Quality Control
Division, downstream water users, or other appropriate agencies. The release of any chemical, oil,
petroleum product, sewage, etc., which enter waters of the State of Colorado (which include
surface water, ground water, and dry gullies or storm sewers leading to surface water) must be
reported immediately to the Division’s emergency spill reporting line at (877) 518-5608. All
spills that will require cleanup, even if the spill is minor and does not need to be reported to the
state, should still be reported to the City Utilities office at 970-221-6700.
While not expected with this project, it will be the responsibility of the Contractor to designate a
fueling area and take the necessary precautions to ensure that no stormwater pollution occurs in the
event that a fueling area is needed. Fueling areas shall be located a minimum 100 feet from all
drainage courses. A 12-inch high compacted earthen ridge capable of retaining potential spills
shall enclose fueling areas. Other secondary containment devices can be used instead of the
earthen ridge. The area shall be covered with a non-porous lining to prevent soil contamination.
Printed instructions for cleanup procedures shall be posted in the fueling area and appropriate fuel
absorbents shall be available along with containers for used absorbents within the fueling area.
3.7 Dedicated Concrete or Asphalt Batch Plant
There are not any dedicated concrete or asphalt batch plants anticipated with this project. In the
event that a plant is needed, the Contractor should be aware that additional permitting will be
required. In particular, an Air Pollutant Emission Notice (APEN) will need to be obtained from
CDPHE.
3.8 Vehicle Tracking Control
In addition to the vehicle tracking pads discussed previously, additional measures can be taken to
minimize and control sediment discharges from the site due to vehicle tracking. These measures
can include fencing around the site to control access points. Regular street sweeping can also be
used to minimize the transmission of sediment from the site due to vehicles leaving the site. The
use of gravel parking areas and wash racks can also be implemented to ensure minimal vehicle
tracking from the site.
3.9 Waste Management and Disposal
It will be the responsibility of the Contractor to designate a concrete truck chute washout area and
to clearly identify that area. Detailed information about the design and maintenance of the Concrete
Washout can be found under the Structural Practices section of this report. At no time should
untreated wash water be allowed to discharge from the site or to enter a storm drain system or
stream. Upon completion of construction activities the concrete washout material shall be removed
and properly disposed of prior to the area being restored.
Any waste material that currently exists on the site or that is generated by construction will be
disposed of in such a manner as to not cause pollutants in stormwater discharges. If waste is to be
stored on-site, it shall be in an area located a minimum of 100 feet from all drainage courses.
Whenever waste is not stored in a non-porous container, it shall be in an area enclosed by a 12-
inch high compacted earthen ridge or some other approved secondary containment device. The area
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shall be covered with a non-porous lining to prevent soil contamination. Whenever precipitation is
predicted, the waste shall be covered with a non-porous cover, anchored on all sides to prevent its
removal by wind, in order to prevent precipitation from leaching out potential pollutants from the
waste. On-site waste disposal practices, such as dumpsters, should be covered or otherwise
contained as to prevent dispersion of waste materials from wind. It shall also be the responsibility
of the Contractor to maintain a clean jobsite as to prevent dispersion of waste material and potential
pollutants into adjacent properties or waterways.
The location of, and protective measures for, temporary restroom facilities shall be the responsibility
of the SWMP Administrator.
3.10 Groundwater and Stormwater Dewatering
The BMPs selected for construction dewatering vary depending on the site-specific features, such as
soils, topography, discharge quantities, and discharge location. Typically, dewatering involves
pumping water from an inundated area to a BMP, prior to the water being released downstream
into a receiving waterway, sediment basin, or well-vegetated area. Acceptable BMPs included
discharging water into a sediment trap or basin, using a dewatering filter bag, or using a series of
sediment logs. A settlement tank or an active treatment system can also be utilized. Another
commonly used method to handle the pumped water is the “sprinkler method,” which involves
applying the water to vegetated areas through a perforated discharge hose. Dispersal from a water
truck for dust control can also be used to disperse the pumped water.
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4.0 Final Stabilization and Long-Term Stormwater Management
4.1 Final Stabilization
All disturbed areas will be seeded, crimped and mulched. As defined by the Colorado Department
of Public Health and Environment in the General Permit Application for Stormwater Discharges,
“Final stabilization is reached when all soil disturbing activities at the site have been completed,
and uniform vegetative cover has been established with a density of at least 70 percent of pre-
disturbance levels or equivalent permanent, physical erosion reduction methods have been
employed.”
4.2 Long-Term Stormwater Management
The primary method of long-term stormwater management will be the use of a concrete outlet
structure and a water quality pond. The outlet structure shall be designed in a manner that allows
smaller, more frequent rainfall events to be detained and released over an extended amount of time.
This extended detention allows suspended sediment and pollutants to settle from the water prior to
entering drainage facilities downstream of the site.
In addition to the water quality pond, riprap will be placed at the outlets of all storm sewer pipes,
curb cuts, drainage pans, and similar concentrated discharge points in order to prevent erosion. All
disturbed areas will receive permanent paving or will be vegetated per the Landscape Plan. All
stormwater runoff from paved surfaces and rooftops is released through a vegetated swale prior to
reaching the water quality pond. Therefore, the disconnection of impervious areas combined with
the detention pond design, offer significant water quality enhancement, and will serve the long-term
stormwater management goals for this project.
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5.0 Inspection, Maintenance and Record Keeping
5.1 BMP Inspection
All temporary erosion control facilities shall be inspected at a minimum of once every two (2) weeks
and after each significant storm event or snowmelt. Repairs or reconstruction of BMPs, as
necessary, shall occur as soon as possible in order to ensure the continued performance of their
intended function. It is the responsibility of the SWMP Administrator to conduct bi-weekly
inspections, maintain BMPs if needed, to keep records of site conditions and inspections, and to
update the SWMP as necessary.
The construction site perimeter, disturbed areas, all applicable/installed erosion and sediment
control measures, and areas used for material storage that are exposed to precipitation shall be
inspected for evidence of, or the potential for, pollutants entering the drainage system. Erosion and
sediment control measures identified in the SWMP shall be observed to ensure that they are
operating correctly. Particular attention should be paid to areas that have a significant potential for
stormwater pollution, such as demolition areas, concrete washout locations, and vehicle entries to
the site. The inspection must be documented to ensure compliance with the permit requirements.
5.2 BMP Maintenance
Any BMP’s not operating in accordance with the SWMP must be addressed as soon as possible,
immediately in most cases, to prevent the discharge of pollutants. If modifications are necessary,
such modifications shall be documented so that the SWMP accurately reflects on-site conditions.
The SWMP needs to accurately represent field conditions at all times.
Uncontrolled releases of mud, muddy water, or measurable amounts of sediment found off-site will
be recorded with a brief explanation of the measures taken to clean-up the sediment that has left
the site, as well as the measures taken to prevent future releases. This record shall be made
available to the appropriate public agencies (Colorado Department of Public Health and
Environment, Water Quality Control Division; Environmental Protection Agency; City of Fort Collins;
etc.) upon request.
Preventative maintenance of all temporary and permanent erosion control BMPs shall be provided
in order to ensure the continued performance of their intended function. Temporary erosion control
measures are to be removed after the site has been sufficiently stabilized as determined by the City
of Fort Collins. Maintenance activities and actions to correct problems shall be noted and recorded
during inspections.
Inspection and maintenance procedures specific to each BMP identified with this SWMP are
discussed in Section 3. Details have also been included with Appendix B.
5.3 Record Keeping
Documentation of site inspections must be maintained. The following items are to be recorded and
kept with the SWMP:
Date of Inspection
Name(s) and title(s) of personnel making the inspection
Location(s) of sediment discharges or other pollutants from the site
Location(s) of BMP’s that need to be maintained
Location(s) of BMP’s that failed to operate as designed or proved inadequate
Locations(s) where additional BMP’s are needed that were not in place at the time of inspection
Deviations from the minimum inspection schedule
Descriptions of corrective action taken to remedy deficiencies that have been identified
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The report shall contain a signed statement indicating the site is in compliance with the permit to the
best of the signer’s knowledge and belief after corrective actions have been taken.
Provided within Appendix E of this SWMP is an Example Inspection Log to aid in the record keeping
of BMP inspections and maintenance. Photographs, field notebooks, drawings and maps should be
included when appropriate.
In addition to the Inspection Log, records should be kept documenting:
BMP maintenance and operation
Stormwater contamination
Contacts with suppliers
Notes on the need for and performance of preventive maintenance and other repairs
Implementation of specific items in the SWMP
Training events (given or attened)
Events involving materials handling and storage
Contacts with regulatory agencies and personnel
Notes of employee activities, contact, notifications, etc.
Records of spills, leaks, or overflows that result in the discharge of pollutants must be documented
and maintained. A record of other spills that are responded to, even if they do not result in a
discharge of pollutants, should be made. Information that should be recorded for all occurrences
includes the time and date, weather conditions, reasons for the spill, etc. Some spills may need to
be reported to authorities immediately. Specifically, a release of any chemical, oil, petroleum
product, sewage, etc., which may enter waters of the State of Colorado (which include surface
water, ground water and dry gullies or storm sewers leading to surface water) must be reported to
the CDPHE.
Additionally, the “Dynamic Site Plan” is intended to be a “living” document where the SWMP
Administrator can hand write the location of BMPs as they are installed to appropriately reflect the
current site conditions. Also on the “Dynamic Site Plan” is a “Table of Construction Sequence and
BMP Application/Removal” that the SWMP Administrator can use to document when BMPs were
installed or removed in conjunction with construction activities. These items have been included as
an aid to the SWMP Administrator, and other methods of record keeping are at his or her discretion.
This Stormwater Management Plan (both the text and map) is not a static
document. It is a dynamic device intended to be kept current and logged as
construction takes place. It shall be the responsibility of the SWMP Administrator
and/or the permit holder (or applicant thereof) to ensure the plan is properly
maintained and followed. Diligent administration is critical, including processing
the Notice to Proceed and noting on the Stormwater Management Plan the dates
that various construction activities occur and respective BMPs are installed
and/or removed.
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6.0 Additional SWMP and BMP Resources
Urban Drainage and Flood Control District
Urban Storm Drainage Criteria Manual - Volume 3 “Best Management Practices”
Colorado Department of Transportation
Erosion Control and Stormwater Quality Guide
BMP Field Academy
EPA Menu of BMP’s
Construction Site Storm Water Runoff Control
International Stormwater Best Management (BMP) Database
Rocky Mountain Education Center
Rocky Mountain Education Center
Red Rocks Community College, Lakewood
Keep It Clean Partnership
Boulder
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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. Soil Resource Report for Larimer County Area, Colorado, Natural Resources
Conservation Service, United States Department of Agriculture.
3. Urban Storm Drainage Criteria Manual, Volumes 1-3, Urban Drainage and Flood
Control District, Water Resources Publications, LLC., Denver, Colorado, Updated
November 2010.
4. 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.
5. Downtown River District Final Design Report, February 2012, Ayres Associates.
6. Geotechnical Engineering Report, Keifer Concrete Storage Yard, February 1, 2011,
Terracon Consultants, Inc.
APPENDIX A
Site Maps
X X
X
X
X
X
X X
X
X
H
Y
D
M
F
E S
D
D
BLOCK 2
OWNER:
GODINEZ
JESSE
LOT 10
OWNER:
CIENFUEGOS
JOE C
LOT 12
OWNER:
JOHNSTON
JAMES R/
JANE A
OWNER:
SANNES
JILL MARIE
CACHE LA POUDRE RIVER
PINE STREET
(100' ROW)
POUDRE STREET
(20' ROW)
LINDEN STREET
(100' ROW)
G
LOT 2
NORTHSIDE AZTLAN
COMMUNITY CENTER
LOT 3
NORTHSIDE AZTLAN
COMMUNITY CENTER
LOT 8
LOT 6
LOT 4
LOT 2
LOT 16 LOT 14
PROPOSED
BUILDING
FFE=65.25
RD
RD
RD
RD
RD
RD
X X
X
X
X
X
X X
X
X
H
Y
D
M
F
E S
D
D
BLOCK 2
OWNER:
GODINEZ
JESSE
LOT 10
OWNER:
CIENFUEGOS
JOE C
LOT 12
OWNER:
JOHNSTON
JAMES R/
JANE A
OWNER:
SANNES
JILL MARIE
CACHE LA POUDRE RIVER
PINE STREET
(100' ROW)
POUDRE STREET
(20' ROW)
LINDEN STREET
(100' ROW)
G
LOT 2
NORTHSIDE AZTLAN
COMMUNITY CENTER
LOT 3
NORTHSIDE AZTLAN
COMMUNITY CENTER
LOT 8
LOT 6
LOT 4
LOT 2
LOT 16 LOT 14
PROPOSED
BUILDING
FFE=65.25
RD
RD
RD
RD
RD
RD
APPENDIX B
Erosion Control Details
SILT FENCE
SF
1
2 WATTLE INSTALLATION
WP
VEHICLE CONTROL TRACKING PAD
VTC
6
PLANTED RIPRAP INSTALLATION
RP
5
CURB INLET PROTECTION
IP
3
CONCRETE WASHOUT AREA
CWA
7
APPENDIX C
Landscape Plan
APPENDIX D
Copies of Permits/Applications
Page 2 of 22
Permit No. COR-030000
CDPS GENERAL PERMIT
STORMWATER DISCHARGES ASSOCIATED WITH
CONSTRUCTION ACTIVITY
AUTHORIZATION TO DISCHARGE UNDER THE
COLORADO DISCHARGE PERMIT SYSTEM
In compliance with the provisions of the Colorado Water Quality Control Act, (25-8-101 et seq., CRS, 1973
as amended) and the Federal Water Pollution Control Act, as amended (33 U.S.C. 1251 et seq.; the "Act"),
this permit authorizes the discharge of stormwater associated with construction activities (and specific
allowable non-stormwater discharges in accordance with Part I.D.3 of the permit) certified under this permit,
from those locations specified throughout the State of Colorado to specified waters of the State. Such
discharges shall be in accordance with the conditions of this permit.
This permit specifically authorizes the facility listed on the certification page (page 1) of this permit to
discharge, as of this date, in accordance with permit requirements and conditions set forth in Parts I and II
hereof. All discharges authorized herein shall be consistent with the terms and conditions of this permit.
This permit and the authorization to discharge shall expire at midnight, June 30, 2012.
Issued and Signed this 31
st
day of May, 2007
COLORADO DEPARTMENT OF PUBLIC HEALTH AND ENVIRONMENT
Janet S. Kieler
Permits Section Manager
Water Quality Control Division
SIGNED AND ISSUED MAY 31, 2007
EFFECTIVE JULY 1, 2007
APPENDIX E
Stormwater Management Plan Inspection Log
APPENDIX F
Contractor Inserts
APPENDIX G
Contractor Inserts
APPENDIX F
FEMA FIRMETTE
Preliminary Erosion Control Report
MAP POCKET
DRAINAGE EXHIBIT
X X
X
X
X
X
X X
X
X
H
Y
D
M
F
E S
D
D
BLOCK 2
OWNER:
GODINEZ
JESSE
LOT 10
OWNER:
CIENFUEGOS
JOE C
LOT 12
OWNER:
JOHNSTON
JAMES R/
JANE A
OWNER:
SANNES
JILL MARIE
CACHE LA POUDRE RIVER
PINE STREET
(100' ROW)
POUDRE STREET
(20' ROW)
LINDEN STREET
(100' ROW)
G
LOT 2
NORTHSIDE AZTLAN
COMMUNITY CENTER
LOT 3
NORTHSIDE AZTLAN
COMMUNITY CENTER
LOT 8
LOT 6
LOT 4
LOT 2
LOT 16 LOT 14
PROPOSED
BUILDING
FFE=65.25
RD
RD
RD
RD
RD
RD
RD
RD
RD
RD
RD
RD
RD
RD
RD
RD
RD
SF
SF
SF
SF
SF
SF
SF SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF SF
SF
SF
IP
SF SF
SF
SF SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF SF
SF
SF
SF
SF
SF
WP
CWA
2B
0.31
3
0.64
4
0.54
7
0.03
OS2
1.31
OS1
0.12
5
0.04
1
0.28
1
2B
3
5
4
6
OS1
OS2
VTC
WP
IP
IP
WP
WP
WP
WP
2A
0.15
2A
RP
RP
RP
RP
7
6
0.02
ST
LOT 1
BLOCK 1
TRACT A
N�. R��������:
B�: D���:
REVIEWED BY:
R. P��������
DESIGNED BY:
DRAWN BY:
SCALE:
DATE:
09/18/12
PROJECT:
683-001
S����
O� 15 S�����
LEGACY SENIOR RESIDENCES T���� �������� ���
����������� �� �������
�������� �� N�������
E���������� S�������, I��.
��� ��� ��� �� �� ���� ���
��� ���� �� ������������
������ ������ ��� ������ ��
� P����������� E������� ��
��� ������ �� N�������
E���������� S�������, I��.
NOT FOR CONSTRUCTION
REVIEW SET
200 S���� C������ A�����, S���� 010
F��� C������, C������� 80524
E N G I N E E R I N G
� � � � � � ��
PHONE: 970.221.4158 FAX: 970.221.4159
���.�������������������.��� 09/18/12
C600
CONTROL PLAN
DRAINAGE AND EROSION K. B��������
K. B��������
1"=20'
NORTH
( IN FEET )
1 ���� = ��.
20 0 20 F���
20
40 60
CALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOU DIG, GRADE, OR EXCAVATE FOR THE MARKING OF UNDERGROUND MEMBER UTILITIES.
CALL UTILITY NOTIFICATION CENTER OF
COLORADO
K��� ����'� �����.
C��� ������ ��� ���.
R
LEGEND:
NOTES:
D���
D���
D���
D���
D���
D���
APPROVED:
CHECKED BY:
CHECKED BY:
CHECKED BY:
CHECKED BY:
CHECKED BY:
C��� E�������
W���� & W��������� U������
S��������� U������
P���� & R���������
T������ E�������
E������������ P������
C��� �� F��� C������, C�������
UTILITY PLAN APPROVAL
1.REFER TO THE "FINAL DRAINAGE REPORT FOR LEGACY SENIOR HOUSING' BY NORTHERN
ENGINEERING, DATED AUGUST 29, 2012 FOR ADDITIONAL INFORMATION.
2.THE FINISHED FLOOR ELEVATIONS SHOWN ARE THE MINIMUM ELEVATIONS REQUIRED
FOR PROTECTION FROM THE 100-YEAR STORM.
3.SEE SECTION 3.4.1 OF THE LAND USE CODE FOR ALLOWABLE USES WITHIN THE NATURAL
HABITAT BUFFER ZONE.
�4.A FLOODPLAIN USE PERMIT WILL BE REQUIRED FOR THE POND OUTLET PIPE RIPRAP
RUNDOWN. NOTE THAT ANY CONSTRUCTION WITHIN THE FEMA 0.5-FOOT FLOODWAY (I.E.
IMPROVEMENTS TO THE EXISTING RUNDOWN) WILL REQUIRE A CITY NO-RISE
CERTIFICATION. CONTRACTOR SHALL CONTACT THE CITY OF FORT COLLINS FLOODPLAIN
ADMINISTRATOR PRIOR TO CONSTRUCTION TO OBTAIN ALL REQUIREMENTS FOR
DEMOLITION AND/OR CONSTRUCTION WITHIN THE FEMA 0.5-FOOT FLOODWAY, INCLUDING
THE REQUIRED PRE-CONSTRUCTION SURVEY. ONCE CONSTRUCTION WITHIN THE
FLOODWAY IS COMPLETE A POST-CONSTRUCTION SURVEY SHALL BE COMPLETED TO
ENSURE THAT THE ELEVATIONS WITHIN THE FLOODWAY HAVE NOT INCREASED BY MORE
THAN 0.00-FEET.
5.THE FOLLOWING FLOODWAY REGULATIONS MUST BE MET:
-NO FILL IS ALLOWED IN THE FLOODWAY UNLESS A HYDRAULIC ANALYSIS SHOWS "NO
RISE".
-LANDSCAPING MEETS REQUIREMENTS FOR NO ENCROACHMENT IN THE FLOODWAY
WITHOUT A HYDRAULIC ANALYSIS TO SHOW "NO RISE".
-NO STORAGE OF MATERIALS OR EQUIPMENT IN THE FLOODWAY.
-NO RISE CERTIFICATION REQUIRED BOTH FOR PRE-CONSTRUCTION AND
POST-CONSTRUCTION FOR THE POND OUTLET PIPE RIPRAP RUNDOWN.�
WATER QUALITY POND SUMMARY
WQ VOLUME REQ'D (��-��) WQ VOLUME PROVIDED (��-��) POND INVERT WQ WATER SURFACE POND SPILL ELEV.
0.06 0.06 4956.11 4958.55 4959.80
PROPOSED STORM SEWER
PROPOSED STORM DRAINAGE INLET
PROPOSED CONTOURS
80
79
EXISTING STORM SEWER
PROPERTY BOUNDARY
EXISTING MAJOR CONTOUR
EXISTING MINOR CONTOUR
5015
5013
EXISTING TREES
A
DESIGN POINT
FLOW ARROW
DRAINAGE BASIN LABEL
BASIN
DESIGNATION
BASIN
AREA (AC)
DRAINAGE BASIN BOUNDARY
B2
1.45 ��
EXISTING RIGHT-OF-WAY
EXISTING FLOODWAY
WATTLE PROTECTION WP
INLET PROTECTION IP
VEHICLE TRACKING CONTROL PAD
VTC
SILT FENCE SF
CONCRETE WASHOUT AREA - FINAL LOCATION TO BE DETERMINED BY CONTRACTOR
CWA
SF
RIPRAP PAD
RP
DRAINAGE SUMMARY TABLE
DESIGN
POINT
BASIN
ID
TOTAL
AREA
(�����)
C10 C100
10-��
T�
(���)
100-�
�
T�
(���)
Q10
(���)
Q100
(���)
1 1 0.28 0.52 0.65 6.4 6.0 0.7 1.7
2� 2� 0.15 0.95 1.00 5.0 5.0 0.7 1.5
2� 2� 0.31 0.95 1.00 5.0 5.0 1.4 3.1
3 3 0.64 0.76 0.95 13.7 12.8 1.6 4.3
4 4 0.54 0.88 1.00 5.0 5.0 2.3 5.4
5 5 0.04 0.68 0.85 5.0 5.0 0.1 0.3
6 6 0.02 0.25 0.31 5.0 5.0 0.0 0.0
7 7 0.03 0.71 0.89 5.0 5.0 0.1 0.2
3
O������ ��
P���
(B���� 1-5) 1.64 0.86 1.00 13.7 12.8 4.7 11.6
OS1 OS1 0.12 0.40 0.50 11.9 10.4 0.2 0.5
OS2 OS2 1.31 0.54 0.67 16.1 15.1 2.2 5.7
SEDIMENT TRAP ST
RD
RD
RD
RD
RD
RD
RD
RD
RD
RD
RD
2
SWMP - DYNAMIC PLAN
A. C���
A. C���
1"=20'
NORTH
( IN FEET )
1 ���� = ��.
20 0 20 F���
20
40 60
CALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOU DIG, GRADE, OR EXCAVATE FOR THE MARKING OF UNDERGROUND MEMBER UTILITIES.
CALL UTILITY NOTIFICATION CENTER OF
COLORADO
K��� ����'� �����.
C��� ������ ��� ���.
R
LEGEND:
PROPOSED STORM SEWER
PROPOSED STORM DRAINAGE INLET
PROPOSED CONTOURS
80
79
EXISTING STORM SEWER
PROPERTY BOUNDARY
EXISTING MAJOR CONTOUR
EXISTING MINOR CONTOUR
5015
5013
EXISTING TREES
EXISTING RIGHT-OF-WAY
EXISTING FLOODWAY
WATTLE PROTECTION WP
INLET PROTECTION IP
VEHICLE TRACKING CONTROL PAD
VTC
SILT FENCE SF
CONCRETE WASHOUT AREA - FINAL LOCATION TO BE DETERMINED BY CONTRACTOR
CWA
SF
RIPRAP PAD
RP
PERMANENT BMP'S
TEMPORARY BMP'S
�1.CONTRACTOR SHALL IMMEDIATELY STABILIZE ALL DISTURBED SLOPES BY CRIMP
MULCHING OR SIMILAR METHODS.
2.TOTAL DISTURBED AREA = 2.3 ACRES
3.SWMP ADMINISTRATOR:
TO BE DETERMINED
4.CONTRACTOR TO PROVIDE VEHICLE TRACKING CONTROL FOR CONCRETE WASHOUT
AREA IF ACCESS IS OFF PAVEMENT.
5.SEE "GRADING & EROSION CONTROL NOTES" ON SHEET C001 OF THE UTILITY PLAN
SET FOR LEGACY SENIOR RESIDENCES PREPARED BY NORTHERN ENGINEERING DATED
SEPTEMBER 18, 2012 FOR ADDITIONAL INFORMATION.�
GENERAL NOTES:
NOTE:
ALL BMP'S SHOWN ON THIS PLAN ARE GRAPHIC
REPRESENTATIONS ONLY. FINAL
DETERMINATION OF SIZE AND LOCATION SHALL
BE DETERMINED BY THE CONTRACTOR AND
DOCUMENTED ON THE DYNAMIC SITE PLAN.
A.IT SHOULD BE NOTED THAT ANY EROSION CONTROL PLAN SERVES ONLY AS A GUIDELINE TO THE
CONTRACTOR. STAGING AND/OR PHASING OF BEST MANAGEMENT PRACTICES (BMP�) IS EXPECTED.
ADDITIONAL AND/OR DIFFERENT BMP� FROM THOSE ORIGINALLY DEPICTED MAY BE NECESSARY DURING
CONSTRUCTION DUE TO CHANGING SITE CONDITIONS OR AS REQUIRED BY LOCAL AUTHORITIES.
B.THE CONTRACTOR SHALL BE RESPONSIBLE FOR ALL PERMITTING (CITY, STATE DISCHARGE PERMIT, ETC.)
AND COMPLIANCE WITH GOVERNING AUTHORITIES. IT SHALL BE THE RESPONSIBILITY OF THE CONTRACTOR
(OR PERMIT HOLDER) TO ENSURE EROSION CONTROL MEASURES ARE PROPERLY MAINTAINED AND FOLLOWED.
C.CONTRACTOR SHALL IMPLEMENT THE APPROPRIATE EROSION CONTROL MEASURES ACCORDING THE THE
CONSTRUCTION SEQUENCING AND LEVEL OF SITE STABILIZATION.
D.CONTRACTOR SHALL IMPLEMENT APPROPRIATE INLET PROTECTION FOR ALL STORM DRAINS, SWALES,
PONDS AND RAIN GARDENS UNTIL SITE IS FULLY STABILIZED.
E.INLET PROTECTION SHALL BE ADAPTED, AS NECESSARY, TO THE SURROUNDING SURFACE TYPE AND
CONDITION (�.�., STAKE-DRIVEN WATTLES FOR BARE SOIL, SAND BAGS OR GRAVEL SOCKS FOR PAVEMENT,
ETC.)
F.CONTRACTOR IS RESPONSIBLE FOR STABILIZING ALL SLOPES, PARTICULARLY THOSE STEEPER THAN 6:1.
CRIMP MULCHING, HYDRO MULCHING, EROSION MATS, TEMPORARY IRRIGATION, AND ADDITIONAL WATTLES OR
SILT FENCING MAY BE NECESSARY TO ESTABLISH VEGETATIVE COVER AND STABILIZE THE SLOPE.
G.ADDITIONAL WATTLES, SILT FENCE, OR OTHER MEASURES, MAY BE NECESSARY TO INSURE THAT EACH
BUILDING PAD IS STABILIZED THROUGHOUT CONSTRUCTION. AT NO TIME SHALL SEDIMENT BE ALLOWED TO
CROSS THE PUBLIC SIDEWALKS.
H.FUELING FACILITIES SHALL BE LOCATED AT LEAST ONE HUNDRED (100) FEET FROM NATURAL BODY OF
WATER, WETLAND, NATURAL DRAINAGE WAY OR MANMADE DRAINAGE WAY. THE FUEL TANKS AND FUELING
AREA MUST BE SET IN A CONTAINMENT AREA THAT WILL NOT ALLOW A FUEL SPILL TO DIRECTLY FLOW, SEEP,
RUN OFF, OR BE WASHED INTO A BODY OF WATER, WETLAND OR DRAINAGE WAY.
I.CONSTRUCTION WASTE STORAGE (DUMPSTERS) AND PORTABLE SANITATION UNITS (CONSTRUCTION
TOILETS) SHALL BE LOCATED AT LEAST FIFTY (50) FEET FROM ANY STORMWATER INLET, WETLAND, OR
DRAINAGE WAY. SAID FACILITIES MUST BE SET IN A CONTAINMENT AREA THAT WILL NOT ALLOW POLLUTANTS
TO DIRECTLY FLOW, SEEP, RUN OFF, OR BE WASHED INTO A BODY OF WATER, WETLAND OR DRAINAGE WAY.
DUMPSTERS SHALL BE LOCATED ON FLAT, STABLE GROUND, AND CONSTRUCTION TOILETS SHALL BE STAKED
DOWN.
J.CONSTRUCTION STAGING IS GENERALLY EXPECTED TO OCCUR ON TRACT A. THIS INCLUDES TEMPORARY
SOIL STOCKPILES, MATERIAL STORAGE, CONSTRUCTION TRAILERS, DUMPSTERS, PORTABLE TOILETS, ETC.
PROPER BMP� SHALL BE IMPLEMENTED AND MAINTAINED ACCORDINGLY FOR SAID COMPONENTS, AND
ADAPTED AS NECESSARY AS CONSTRUCTION PROGRESSES AND/OR OCCURS IN OTHER LOCATIONS.
K.THE CONTRACTOR AND ALL SUBCONTRACTORS WILL COOPERATE WITH THE CITY'S CONSTRUCTION
EROSION CONTROL NOTES:
N�. R��������:
B�: D���:
REVIEWED BY:
R. P��������
DESIGNED BY:
DRAWN BY:
SCALE:
DATE:
09/18/12
PROJECT:
683-001
S����
O� 2 S�����
LEGACY SENIOR RESIDENCES T���� �������� ���
����������� �� �������
�������� �� N�������
E���������� S�������, I��.
��� ��� ��� �� �� ���� ���
��� ���� �� ������������
������ ������ ��� ������ ��
� P����������� E������� ��
��� ������ �� N�������
E���������� S�������, I��.
NOT FOR CONSTRUCTION
REVIEW SET
200 S���� C������ A�����, S���� 010 09/18/12
F��� C������, C������� 80524
E N G I N E E R I N G
� � � � � � ��
PHONE: 970.221.4158 FAX: 970.221.4159
���.�������������������.���
RD
RD
RD
RD
RD
RD
RD
RD
RD
RD
RD
SF
SF
SF
SF
SF
SF
SF SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF SF
SF
SF
SF SF
SF
SF SF
SF
SF
SF
SF
SF
SF
SF
SF
SF SF
SF
SF
SF
SF
IP
SF
SF
SF
SF
SF
SF
SF
WP
CWA
VTC
WP
IP
IP
WP
WP
WP
WP
RP
RP
RP
RP
N�. R��������:
B�: D���:
REVIEWED BY:
R. P��������
DESIGNED BY:
DRAWN BY:
SCALE:
DATE:
09/18/12
PROJECT:
683-001
S����
O� 2 S�����
LEGACY SENIOR RESIDENCES T���� �������� ���
����������� �� �������
�������� �� N�������
E���������� S�������, I��.
��� ��� ��� �� �� ���� ���
��� ���� �� ������������
������ ������ ��� ������ ��
� P����������� E������� ��
��� ������ �� N�������
E���������� S�������, I��.
NOT FOR CONSTRUCTION
REVIEW SET
200 S���� C������ A�����, S���� 010 09/18/12
F��� C������, C������� 80524
E N G I N E E R I N G
� � � � � � ��
PHONE: 970.221.4158 FAX: 970.221.4159
���.�������������������.���
1
SWMP - STATIC PLAN
A. C���
A. C���
1"=20'
NORTH
( IN FEET )
1 ���� = ��.
20 0 20 F���
20
40 60
CALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOU DIG, GRADE, OR EXCAVATE FOR THE MARKING OF UNDERGROUND MEMBER UTILITIES.
CALL UTILITY NOTIFICATION CENTER OF
COLORADO
K��� ����'� �����.
C��� ������ ��� ���.
R
LEGEND:
PROPOSED STORM SEWER
PROPOSED STORM DRAINAGE INLET
PROPOSED CONTOURS
80
79
EXISTING STORM SEWER
PROPERTY BOUNDARY
EXISTING MAJOR CONTOUR
EXISTING MINOR CONTOUR
5015
5013
EXISTING TREES
EXISTING RIGHT-OF-WAY
EXISTING FLOODWAY
WATTLE PROTECTION WP
INLET PROTECTION IP
VEHICLE TRACKING CONTROL PAD
VTC
SILT FENCE SF
CONCRETE WASHOUT AREA - FINAL LOCATION TO BE DETERMINED BY CONTRACTOR
CWA
SF
RIPRAP PAD
RP
PERMANENT BMP'S
TEMPORARY BMP'S
�1.CONTRACTOR SHALL IMMEDIATELY STABILIZE ALL DISTURBED SLOPES BY CRIMP
MULCHING OR SIMILAR METHODS.
2.TOTAL DISTURBED AREA = 2.3 ACRES
3.SWMP ADMINISTRATOR:
TO BE DETERMINED
4.CONTRACTOR TO PROVIDE VEHICLE TRACKING CONTROL FOR CONCRETE WASHOUT
AREA IF ACCESS IS OFF PAVEMENT.
5.SEE "GRADING & EROSION CONTROL NOTES" ON SHEET C001 OF THE UTILITY PLAN
SET FOR LEGACY SENIOR RESIDENCES PREPARED BY NORTHERN ENGINEERING DATED
SEPTEMBER 18, 2012 FOR ADDITIONAL INFORMATION.�
GENERAL NOTES:
NOTE:
ALL BMP'S SHOWN ON THIS PLAN ARE GRAPHIC
REPRESENTATIONS ONLY. FINAL
DETERMINATION OF SIZE AND LOCATION SHALL
BE DETERMINED BY THE CONTRACTOR AND
DOCUMENTED ON THE DYNAMIC SITE PLAN.
A.IT SHOULD BE NOTED THAT ANY EROSION CONTROL PLAN SERVES ONLY AS A GUIDELINE TO THE
CONTRACTOR. STAGING AND/OR PHASING OF BEST MANAGEMENT PRACTICES (BMP�) IS EXPECTED.
ADDITIONAL AND/OR DIFFERENT BMP� FROM THOSE ORIGINALLY DEPICTED MAY BE NECESSARY DURING
CONSTRUCTION DUE TO CHANGING SITE CONDITIONS OR AS REQUIRED BY LOCAL AUTHORITIES.
B.THE CONTRACTOR SHALL BE RESPONSIBLE FOR ALL PERMITTING (CITY, STATE DISCHARGE PERMIT, ETC.)
AND COMPLIANCE WITH GOVERNING AUTHORITIES. IT SHALL BE THE RESPONSIBILITY OF THE CONTRACTOR
(OR PERMIT HOLDER) TO ENSURE EROSION CONTROL MEASURES ARE PROPERLY MAINTAINED AND FOLLOWED.
C.CONTRACTOR SHALL IMPLEMENT THE APPROPRIATE EROSION CONTROL MEASURES ACCORDING THE THE
CONSTRUCTION SEQUENCING AND LEVEL OF SITE STABILIZATION.
D.CONTRACTOR SHALL IMPLEMENT APPROPRIATE INLET PROTECTION FOR ALL STORM DRAINS, SWALES,
PONDS AND RAIN GARDENS UNTIL SITE IS FULLY STABILIZED.
E.INLET PROTECTION SHALL BE ADAPTED, AS NECESSARY, TO THE SURROUNDING SURFACE TYPE AND
CONDITION (�.�., STAKE-DRIVEN WATTLES FOR BARE SOIL, SAND BAGS OR GRAVEL SOCKS FOR PAVEMENT,
ETC.)
F.CONTRACTOR IS RESPONSIBLE FOR STABILIZING ALL SLOPES, PARTICULARLY THOSE STEEPER THAN 6:1.
CRIMP MULCHING, HYDRO MULCHING, EROSION MATS, TEMPORARY IRRIGATION, AND ADDITIONAL WATTLES OR
SILT FENCING MAY BE NECESSARY TO ESTABLISH VEGETATIVE COVER AND STABILIZE THE SLOPE.
G.ADDITIONAL WATTLES, SILT FENCE, OR OTHER MEASURES, MAY BE NECESSARY TO INSURE THAT EACH
BUILDING PAD IS STABILIZED THROUGHOUT CONSTRUCTION. AT NO TIME SHALL SEDIMENT BE ALLOWED TO
CROSS THE PUBLIC SIDEWALKS.
H.FUELING FACILITIES SHALL BE LOCATED AT LEAST ONE HUNDRED (100) FEET FROM NATURAL BODY OF
WATER, WETLAND, NATURAL DRAINAGE WAY OR MANMADE DRAINAGE WAY. THE FUEL TANKS AND FUELING
AREA MUST BE SET IN A CONTAINMENT AREA THAT WILL NOT ALLOW A FUEL SPILL TO DIRECTLY FLOW, SEEP,
RUN OFF, OR BE WASHED INTO A BODY OF WATER, WETLAND OR DRAINAGE WAY.
I.CONSTRUCTION WASTE STORAGE (DUMPSTERS) AND PORTABLE SANITATION UNITS (CONSTRUCTION
TOILETS) SHALL BE LOCATED AT LEAST FIFTY (50) FEET FROM ANY STORMWATER INLET, WETLAND, OR
DRAINAGE WAY. SAID FACILITIES MUST BE SET IN A CONTAINMENT AREA THAT WILL NOT ALLOW POLLUTANTS
TO DIRECTLY FLOW, SEEP, RUN OFF, OR BE WASHED INTO A BODY OF WATER, WETLAND OR DRAINAGE WAY.
DUMPSTERS SHALL BE LOCATED ON FLAT, STABLE GROUND, AND CONSTRUCTION TOILETS SHALL BE STAKED
DOWN.
J.CONSTRUCTION STAGING IS GENERALLY EXPECTED TO OCCUR ON TRACT A. THIS INCLUDES TEMPORARY
SOIL STOCKPILES, MATERIAL STORAGE, CONSTRUCTION TRAILERS, DUMPSTERS, PORTABLE TOILETS, ETC.
PROPER BMP� SHALL BE IMPLEMENTED AND MAINTAINED ACCORDINGLY FOR SAID COMPONENTS, AND
ADAPTED AS NECESSARY AS CONSTRUCTION PROGRESSES AND/OR OCCURS IN OTHER LOCATIONS.
K.THE CONTRACTOR AND ALL SUBCONTRACTORS WILL COOPERATE WITH THE CITY'S CONSTRUCTION
EROSION CONTROL NOTES:
INPUT CALCULATE
Date: 7/1/12
Expansion
Factor
1/(2tan
From
Figure
MD-23 or
MD-24)
Storm
Line/Culvert
Label
Design
Discharge
(cfs)
By: ATC
OUTPUT
Spec
Length
of
Riprap
(ft)
Box Culvert
Yt,
Tailwater
Depth
(ft)
Culvert Parameters
At=Q/V
(ft)
3
Overall Onsite +
Offsite to Pond
(Basin 2-4,
OS2) 2.95 19 19 18 0.71 0.71 0.89 1.68 2.86 6.01 3.53 6.02 15.8
(min)
10-yr
Tc
(min)
100-yr
Tc
(min)
11No0.25 0.25 0.31 41 12.00% 4.4 4.4 4.1 0 0.00% N/A N/A 198 1.30% 1.71 1.9 6 6 6
2a 2a No 0.95 0.95 1.00 15 0.50% 1.4 1.4 0.9 200 0.50% 1.41 2.4 0 N/A N/A N/A 5 5 5
2b 2b No 0.95 0.95 1.00 40 0.50% 2.2 2.2 1.5 200 0.50% 1.41 2.4 0 N/A N/A N/A 5 5 5
33No0.25 0.25 0.31 141 3.20% 12.8 12.8 11.9 76 0.50% 1.41 0.9 0 N/A N/A N/A 14 14 13
44No0.95 0.95 1.00 62 2.50% 1.6 1.6 1.1 67 0.50% 1.41 0.8 0 N/A N/A N/A 5 5 5
55No0.95 0.95 1.00 33 4.50% 1.0 1.0 0.7 0 0.00% N/A N/A 0 N/A N/A N/A 5 5 5
6 6 No 0.25 0.25 0.31 20 8.00% 3.6 3.6 3.3 0 0.00% N/A N/A 0 N/A N/A N/A 5 5 5
7 7 No 0.95 0.95 1.00 20 2.00% 1.0 1.0 0.7 0 0.00% N/A N/A 0 N/A N/A N/A 5 5 5
Overall to
Pond
DEVELOPED TIME OF CONCENTRATION COMPUTATIONS
Gutter Flow Swale Flow
Design
Point
Basin
Overland Flow
ATC
July 1, 2012
Time of Concentration
(Equation RO-4)
3
1
1 . 87 1 . 1 *
S
Ti C Cf L
3
(Basin 2-
4) No 0.25 0.25 0.31 141 3.20% 12.8 12.8 11.9 76 0.50% 1.41 0.9 0 N/A N/A N/A 14 14 13
OS1 OS1 No 0.40 0.40 0.50 94 1.60% 10.9 10.9 9.3 78 0.40% 1.26 1.0 0 N/A N/A N/A 12 12 10
OS2 OS2 No 0.25 0.25 0.31 85 1.30% 13.4 13.4 12.5 202 0.40% 1.26 2.7 0 N/A N/A N/A 16 16 15
3
Overall to
Pond
(Basin 2-
4, OS2) No 0.25 0.25 0.31 76 1.10% 13.4 13.4 12.5 416 0.45% 1.34 5.2 0 N/A N/A N/A 19 19 17.6
(Basin 2-4) 71472 1.641 0.895 0.062 0.462 0.000 0.222 0.86 0.86 1.00 83%
OS1 5408 0.124 0.000 0.000 0.026 0.000 0.098 0.40 0.40 0.50 19%
OS2 56991 1.308 0.229 0.000 0.282 0.073 0.725 0.54 0.54 0.67 39%
Overall Onsite +
Offsite to Pond
(Basin 2-4, OS2) 128463 2.949 1.123 0.062 0.744 0.073 0.947 0.71 0.71 0.89 64%
DEVELOPED COMPOSITE % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS
Runoff Coefficients are taken from the City of Fort Collins Storm Drainage Design Criteria and Construction Standards, Table 3-3. % Impervious taken from UDFCD USDCM, Volume I.
10-year Cf = 1.00
July 1, 2012