HomeMy WebLinkAboutAWEIDA - PDP - PDP180008 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTi
4101 South Taft Hill Road
FORT COLLINS
PRELIMINARY DRAINAGE REPORT
Prepared by:
North Star Design
700 Automation Drive, Unit I
Windsor, Colorado 80550
Prepared for:
Aweida Properties, Inc
June 12, 2018
Project Number 385-01
ii
June 12, 2018
Dan Mogen
City of Fort Collins Stormwater
700 Wood Street
Fort Collins, CO 80522-0580
RE: Preliminary Drainage Report for 4101 South Taft Hill Road
Dear Dan,
I am pleased to submit for your review and approval, this Preliminary Drainage Report for a
multi-use building at 4101 South Taft Hill Road in Fort Collins. I certify that this report for the
drainage design was prepared in accordance with the criteria in the City of Fort Collins Storm
Drainage Manual.
I appreciate your time and consideration in reviewing this submittal. Please call if you have any
questions.
Sincerely,
Patricia Kroetch, P.E.
700 Automation Drive, Unit I
Windsor, CO 80550
Phone: 970-686-6939
Fax: 970-686-1188
iii
TABLE OF CONTENTS
TABLE OF CONTENTS ............................................................................................................... iii
1. GENERAL LOCATION AND DESCRIPTION
1.1 Location ...................................................................................................................1
1.2 Description of Property ............................................................................................1
2. DRAINAGE BASINS AND SUB-BASINS
2.1 Major Basin Description ..........................................................................................1
2.2 Sub-Basin Description .............................................................................................2
3. DRAINAGE DESIGN CRITERIA
3.1 Regulations ..............................................................................................................2
3.2 Four Step Process to Minimize Adverse Impacts of Urbanization ..........................2
3.3 Development Criteria Reference and Constraints ...................................................3
3.4 Hydrologic Criteria ..................................................................................................4
3.5 Hydraulic Criteria ....................................................................................................4
4. DRAINAGE FACILITY DESIGN
4.1 General Concept ......................................................................................................4
4.2 Specific Flow Routing .............................................................................................4
4.3 Drainage Summary ..................................................................................................5
5. CONCLUSIONS
5.1 Compliance with Standards ....................................................................................6
5.2 Drainage Concept ....................................................................................................6
6. REFERENCES ....................................................................................................................7
APPENDICES
A Vicinity Map
B Hydrologic Computations
C Detention System Sizing Calculations
E BMP Schedule and Cost Estimate
F Erosion & Sediment Control Report
1
1. GENERAL LOCATION AND DESCRIPTION
1.1 Location
This site is located on the southwest corner of the intersection of West County Road 38E
and South Taft Hill Road in the Southeast Quarter of Section 33, Township 7 North,
Range 69 West of the Sixth Principal Meridian, in the City of Fort Collins, Larimer
County, Colorado. See the Vicinity Map in Appendix A of this report.
This project is bounded on the north and east by existing arterial rights of ways and on
the west and south by existing residences.
1.2 Description of Property
The entire project consists of approximately 0.35 acres. This site was previously
unplatted and was used for a single residence with a gravel driveway. There are some
older trees on site that will be removed and volunteer grasses and weeds cover the site.
All of the surrounding area is large lot residential county development and are not part of
a subdivision. There are no major drainageways, facilities or easements within or
adjacent to the site.
Proposed development on-site will include a single multi use building, a private drive
with access to both CR 38E and Taft Hill Road, a parking area and sidewalks. Existing
drainage patterns will be altered to route flow to a proposed rain garden and underground
detention system in the north and east portions of the site which will release into the
existing storm system near the northeast corner of the site. Irrigation of the site will be
through a drip system connected to the potable water system.
2. DRAINAGE BASINS AND SUB-BASINS
2.1 Major Basin Description
The proposed development lies within the Mail Creek Drainage Basin. The basin
generally drains from west to east to the confluence of Mail Creek and Fossil Creek, and
ultimately to Fossil Creek Reservoir. Three irrigation canals intercept stormwater to
transport it out of the basin, but runoff spills into the basin when their capacity is
exceeded. There are no irrigation facilities within this Basin which will influence or be
2
influenced by the local drainage design. This site is not within a FEMA defined
floodway or floodplain. No previous drainage studies have been completed for this site.
Stormwater detention and water quality enhancement are required for this site.
2.2 Sub-basin Description
Runoff from this site currently flows to the existing streets on the north and east.
Currently, there are small roadside ditches and driveway culverts that collect the water
from this site. Both adjacent properties direct their runoff to the adjacent street and no
runoff from those sites will impact this site.
With the proposed drainage concept for this site, the runoff from the site will flow to a
rain garden located on the north and east sides of the building and then into a proposed
on site underground detention area. This detention facility will release the runoff at a
composite historic rate into the existing storm system to the north of the site. Curb &
gutter will be added to the adjacent streets therefore street runoff will no longer impact
this site.
3. DRAINAGE DESIGN CRITERIA
3.1 Regulations
This report was prepared to meet or exceed the “City of Fort Collins Storm Drainage
Design Criteria Manual” specifications.
3.2 Four Step Process to Minimize Adverse Impacts of Urbanization
Because this site is small, the ability to disconnect impervious areas is difficult. The site
does not benefit from disconnecting the impervious areas therefore this has not been
accomplished on this site.
Step 1. Employ Runoff Reduction Practices – reduction of runoff peaks, volumes, and
pollutant loads as the site is developed by implementing Low-Impact Development (LID)
strategies including:
Increase time of concentration by routing flows along the drive aisles and
increasing the length of the flow path.
3
Routing runoff from the proposed site into rain gardens to promote infiltration
and biological uptake.
Routing flows through filter material in the rain gardens to increase time of
concentration, promote infiltration and provide initial water quality.
Step 2. Implement BMPs That Provide a Water Quality Capture Volume with Slow
Release - The efforts outlined in Step 1 will facilitate the reduction of runoff. Runoff will
be routed through the rain gardens and then to an underground detention storage facility
that will provide attenuation prior to release into the public storm system to reduce the
amount of runoff generated from the site through infiltration, and also treat the runoff
prior to releasing it from the site.
Step 3. Stabilize Streams - There are no major drainageways in or near this site
therefore Step 3 it not directly applicable this project. However, this project will pay
stormwater development fees and monthly stormwater utility fees which contribute to the
City’s ongoing efforts to attain stream stability where and as needed.
Step 4. Implement Site Specific and Other Source Control BMPs - This step applies
to covering storage/handling areas and spill containment and control. Vehicle
maintenance and washing during construction will be completed off site to prevent
potential spills of vehicle fluids. Any handling of chemicals will be completed inside the
building and will be handled per the applicable MSDS (material safety data sheet). Spills
will be contained immediately and cleaned up using appropriate absorption materials.
3.3 Development Criteria Reference and Constraints
The runoff from this site has been routed to conform to the requirements of the Mail
Creek Drainage Basin and the City of Fort Collins Stormwater Department. There are no
previous drainage studies for this or the adjacent sites. This site is highly constrained due
to the small size of the site and the requirement for dedication of additional right of way
for the adjacent arterial streets.
Stormwater runoff detention is required for this site with on-site detention. The release
rate from the site will be at the calculated composite release rate of 0.60 cfs.
3.4 Hydrologic Criteria
4
Runoff computations were prepared for the 2-year minor and 100-year major storm
frequencies utilizing the rational method. All hydrologic calculations associated with the
basins are included in Appendix B of this report. Standard Form 8 (SF-8) provides time
of concentration calculations for all sub-basins.
Detention volume was calculated using the predetermined composite release rate of 0.60
cfs. The FAA method for detention sizing was utilized to determine the required volume.
Refer to the detention calculations included in Appendix C of this report.
3.5 Hydraulic Criteria
Hydraulic elements have been designed per City of Fort Collins standards to adequately
convey the 100-year storm runoff from this site to the proposed underground detention
area. A proposed 12” storm pipe will convey the detained runoff from the site to an
existing manhole located on the northwest corner of Taft Hill Road and CR 38E.
4. DRAINAGE FACILITY DESIGN
4.1 General Concept
The runoff from this site will surface flow to two on site low points on the entry drives.
The runoff will then enter the rain garden and infiltrate into the subdrain. From here, the
runoff will enter the underground detention area. The flow will be attenuated and the
detained runoff will discharge into the proposed inlet and storm pipe located in the
northeast corner of the site on CR 38E.
4.2 Specific Flow Routing
With this design, the site has been considered as a single basin which described in the
following paragraph.
Basin 1 contains the entire site including the building, parking lot, sidewalks, entrance
drives and rain garden. The runoff from this basin will flow north to one low point in the
entrance drive from CR 38E and will flow east to another low point in the access drive
from Taft Hill Road. Flow from both low points will flow to the rain garden located on
the north and east sides of the proposed building. From here, the flow will enter the
underdrains and be conveyed to a storm manhole in the northeast corner of the site. The
5
flow will backflow into the detention pipe array under along the north side of the
building and on the west side of the building under the parking lot. The flow will release
into the existing storm system at a rate of 0.60 cfs.
The underground detention chamber system will release the detained runoff from the site
at the rate of 0.60 cfs. This rate was calculated by determining the area of the site that is
historically impervious and using the 2 year historic runoff then determining the area of
the site that is historically pervious and using the 100 year historic runoff. The total of
these 2 historic values was used as the allowable release rate from the detention storage.
This totals an allowable release rate of 0.60 cfs.
A drainage easement will be dedicated on the plat to encompass the detention storage
pipes and the rain garden. Pipes are also shown on the plan to convey runoff from the
west and the south to the existing storm system at the northwest corner of the intersection
of Taft Hill Road and CR 38E. These pipes will fall within the right of ways and will not
require separate drainage easements.
4.3 Drainage Summary
This site has been designed to meet or exceed the “City of Fort Collins Storm Drainage
Design Criteria Manual” specifications. The proposed drainage design for this site has
been designed to convey on-site runoff to the detention pond while minimizing future
maintenance. The site incorporates LID (Low Impact Development) volume in the
chambers in addition to the detention volume. Refer to the end of Appendix E for a table
indicating the sizing of the required volume for LID treatment.
All drainage facilities proposed with this project, including the underground detention
chambers, drain basins, inlets and storm pipe are private and will be owned and
maintained by the property owner. The pipe and the storm manhole in the right of way
will be owned and maintained by the City of Fort Collins. The 12” pipe to be installed
from Lot 6 to Conifer Street will be maintained by the owner of Lot 6.
5. CONCLUSIONS
5.1 Compliance with Standards
6
All computations that have been completed within this report are in compliance with the
“City of Fort Collins Erosion Control Reference Manual for Construction Sites”, the
“City of Fort Collins Storm Drainage Design Criteria Manual”, and the “Urban Storm
Drainage Criteria Manual”.
5.2 Drainage Concept
The proposed drainage concepts presented in this report and on the construction plans
adequately provide for the collection and conveyance of on-site runoff to the
underground detention system. Conveyance elements exist in Conifer Street to
adequately convey detained runoff downstream.
If, at the time of construction, groundwater is encountered, a Colorado Department of
Health Construction Dewatering Permit would be required.
7
6. REFERENCES
1. Urban Drainage and Flood Control District, “Urban Storm Drainage Criteria
Manual”, 2001 Edition Volume 1 updated June 2001, January 2004 and April
2008; Volume 2 updated June 2001 and April 2008; and Volume 3 updated
November and December 2010.
2. The Fort Collins Amendments to the Urban Drainage and Flood Control District
Criteria Manual, adopted by the City Council of the City of Fort Collins, as
referenced in Section 26-500 (c) of the Code of the City of Fort Collins.
3. ORDINANCE NO. 152, 2012 of the Council of the City of Fort Collins amending
Chapter 26 of the Code of the City of Fort Collins and the Fort Collins
Stormwater Criterial Manual to incorporate provisions implementing Low Impact
Development (LID) Principles.
APPENDIX A
VICINITY MAP
B
APPENDIX B
HYDROLOGIC COMPUTATIONS
North Star Design, Inc.
700 Automation Drive, Unit I
Windsor, CO 80550
LOCATION: 4101 South Taft Hill Road
PROJECT NO: 385-01
COMPUTATIONS BY: ppk
DATE: 6/12/2018
Recommended Runoff Coefficients from Table 3-3 of City of Fort Collins Design Criteria
Recommended % Impervious from Urban Storm Drainage Criteria Manual
% Runoff
Impervious coefficient
C
Streets, parking lots (asphalt): 100% 0.95
Sidewalks: 96% 0.95
Gravel: 40% 0.50
Roofs: 90% 0.95
Lawns (flat <2%, heavy soil): 0% 0.20
SUBBASIN TOTAL TOTAL ROOF PAVED SIDEWALK GRAVEL LANDSCAPE % RUNOFF
DESIGNATION AREA AREA AREA AREA AREA AREA AREA Impervious COEFF.
(ac.) (sq.ft) (sq.ft) (sq.ft) (sq.ft) (sq.ft) (sq.ft) (C)
1 0.34 14956 2660 5645 1787 0 4,864 65% 0.71
Total to pond 0.34 14,956 2,660 5,645 1,787 0 4,864 65% 0.71
Historic landscape 0.23 9,927 9,927 0% 0.20
Historic hardscape 0.12 5,029 1,370 1,572 690 1,397 0 80% 0.82
Historic Site 0.34 14,956 1,370 1,572 690 1,397 9,927 27% 0.41
Equations
- Calculated C coefficients & % Impervious are area weighted
C = (Ci Ai) / At
Ci = runoff coefficient for specific area, Ai
Ai = areas of surface with runoff coefficient of Ci
n = number of different surfaces to consider
At = total area over which C is applicable; the sum of all Ai's
Flow.xls Cval
North Star Design, Inc.
700 Automation Drive, Unit I
Windsor, CO 80550
LOCATION: 4101 South Taft Hill Road
PROJECT NO: 385-01
COMPUTATIONS BY: ppk
DATE: 6/12/2018
2-yr storm Cf = 1.00
FINAL REMARKS
tc
DESIGN SUBBASIN(s) Area C Length Slope ti Length Slope n Vel. tt tc = Total L tc=(l/180)+10
POINT (ac) (ft) (%) (min) (ft) (%) Manning (ft/s) (min) ti + tt (ft) (min) (min)
(1) (2) (3) (4) (5) (6) (7) (8) rough. (9) (10) (11) (12) (13) (14)
1 1 0.34 0.71 19 2.0 2.5 115 0.1 0.016 0.5 3.89 6.3 134 10.7 6.3
Historic landscape 0.23 0.20 158.5 2.2 15.7 0 1.0 0.020 1.6 0.00 15.7 158.5 10.9 10.9
Historic hardscape 0.12 0.82 158.5 2.2 4.8 0 1.0 0.020 1.6 0.00 4.8 158.5 10.9 5.0
Historic Site 0.34 0.41 158.5 2.2 12.0 0 1.0 0.020 1.6 0.00 12.0 158.5 10.9 10.9
EQUATIONS:
tc = ti + tt
ti = [1.87 (1.1 - CCf ) L0.5 ] / S 1/3
tt = L/Vel. Velocity from Manning's Equation with R=0.1 (corresponds to Figure 3-3 of City of Fort Collins Design Manual)
final tc = minimum of ti + tt and urbanized basin check
min. tc = 5 minutes
TIME (ti)
TRAVEL TIME / GUTTER OR CHANNEL FLOW
(tt)
tc CHECK
(URBANIZED BASIN)
STANDARD FORM SF-2
TIME OF CONCENTRATION - 2 YEAR
SUB-BASIN DATA INITIAL /OVERLAND
Flow.xls TOC-2
North Star Design, Inc.
700 Automation Drive, Unit I
Windsor, CO 80550
LOCATION: 4101 South Taft Hill Road
PROJECT NO: 385-01
COMPUTATIONS BY: ppk
DATE: 6/12/2018
100-yr storm Cf = 1.25
FINAL REMARKS
tc
DESIGN SUBBASIN(s) Area C C*Cf Length Slope ti Length Slope n Vel. tt tc = Total L tc=(l/180)+10
POINT (ac) (ft) (%) (min) (ft) (%) Manning (ft/s) (min) ti + tt (ft) (min) (min)
(1) (2) (3) (4) (5) (6) (7) (8) rough. (9) (10) (11) (12) (13) (14)
1 1 0.34 0.71 0.88 19 2.0 1.4 115 0.1 0.016 0.5 3.89 5.2 134 10.7 5.2
Historic landscape 0.23 0.20 0.25 158.5 2.2 14.8 0 1.0 0.020 1.6 0.00 14.8 158.5 10.9 10.9
Historic hardscape 0.12 0.82 1.00 158.5 2.2 1.7 0 1.0 0.020 1.6 0.00 1.7 158.5 10.9 5.0
Historic Site 0.34 0.41 0.51 158.5 2.2 10.2 0 1.0 0.020 1.6 0.00 10.2 158.5 10.9 10.2
EQUATIONS:
tc = ti + tt
ti = [1.87 (1.1 - CCf ) L
0.5
] / S
1/3
tt = L/Vel. Velocity from Manning's Equation with R=0.1 (corresponds to Figure 3-3 of City of Fort Collins Design Manual)
final tc = minimum of ti + tt and urbanized basin check
min. tc = 5 minutes
TIME OF CONCENTRATION - 100 YR
STANDARD FORM SF-2
SUB-BASIN DATA
TIME (ti)
INITIAL /OVERLAND TRAVEL TIME / GUTTER OR CHANNEL FLOW
(tt)
tc CHECK
(URBANIZED BASIN)
Flow.xls TOC-100
North Star Design, Inc.
700 Automation Drive, Unit I
Windsor, CO 80550
RATIONAL METHOD PEAK RUNOFF
(2-YEAR)
LOCATION: 4101 South Taft Hill Road
PROJECT NO: 385-01
COMPUTATIONS BY: ppk
DATE: 6/12/2018
2-yr storm, Cf = 1.00
TOTAL REMARKS
Design Tributary A C*Cf tc i Q (2) from Q (2) Q(2)tot
Sub-basin (new) Design
Point (ac) (min) (in/hr) (cfs) Point (cfs) (cfs)
1 1 0.34 0.71 6.3 2.64 0.6 0.6
Historic landscape 0.23 0.20 10.9 2.14 0.1 0.10
Historic hardscape 0.12 0.82 5.0 2.14 0.2 0.20 Allowable release rate
Historic Site 0.34 0.41 10.9 2.14 0.3 0.30
Q = Cf C iA
Q = peak discharge (cfs)
C = runoff coefficient
Cf = frequency adjustment factor
i = rainfall intensity (in/hr) from IDF curve
A = drainage area (acres)
DIRECT RUNOFF CARRY OVER
Flow.xls Q2
North Star Design, Inc.
700 Automation Drive, Unit I
Windsor, CO 80550 RATIONAL METHOD PEAK RUNOFF
(100-YEAR)
LOCATION: 4101 South Taft Hill Road
PROJECT NO: 385-01
COMPUTATIONS BY: ppk
DATE: 6/12/2018
100-yr storm, Cf = 1.25
TOTAL REMARKS
Des. Area A C*Cf tc i Q (100) from Q (100) Q(100)tot
(new) Design
Point Design. (ac) (min) (in/hr) (cfs) Point (cfs) (cfs)
1 1 0.34 0.88 5.2 9.81 3.0 3.0
Historic landscape 0.23 0.25 10.9 7.63 0.43 0.4 Allowable release rate
Historic hardscape 0.12 1.00 5.0 7.63 0.88 0.9
Historic Site 0.34 0.51 10.2 7.63 1.34 1.3
Q = C iA
Q = peak discharge (cfs)
C = runoff coefficient
I = rainfall intensity (in/hr) from IDF curve
A = drainage area (acres)
DIRECT RUNOFF CARRY OVER
Flow.xls Q100
C
APPENDIX C
DETENTION SIZING CALCULATIONS
MINIMUM DETENTION VOLUME REQUIRED
FAA METHOD
(100-YEAR)
LOCATION: 4101 South Taft Ave
PROJECT NO: 385-01
COMPUTATIONS BY: PPK
SUBMITTED BY: North Star Design, Inc.
DATE: 6/12/2018
Equations: A trib. To pond = 0.34 acre
QD = CiA C100 = 0.88
Vi = T*CiA = T*QD Developed C*A = 0.3 acre
Vo =K*QPO*T QPO = 0.60 cfs
S = Vi - Vo K = 1 (from fig 2.1)
Rainfall intensity from City of Fort Collins IDF Curve
Storm Rainfall QD Vol. In Vol. Out Storage Storage
Duration, T Intensity, i (cfs) Vi Vo SS
(min) (in/hr) (ft3) (ft3) (ft3) (ac-ft)
5 9.95 3.0 893 180 713 0.016
10 7.72 2.3 1386 360 1026 0.024
20 5.60 1.7 2011 720 1291 0.030
30 4.52 1.4 2434 1080 1354 0.031
40 3.74 1.1 2686 1440 1246 0.029
50 3.23 1.0 2899 1800 1099 0.025
60 2.86 0.9 3081 2160 921 0.021
70 2.62 0.8 3292 2520 772 0.018
80 2.38 0.7 3418 2880 538 0.012
90 2.22 0.7 3587 3240 347 0.008
100 2.05 0.6 3680 3600 80 0.002
110 1.93 0.6 3811 3960 -149 -0.003
120 1.80 0.5 3878 4320 -442 -0.010
130 1.60 0.5 3734 4680 -946 -0.022
140 1.40 0.4 3519 5040 -1521 -0.035
150 1.20 0.4 3231 5400 -2169 -0.050
160 1.15 0.3 3303 5760 -2457 -0.056
170 1.10 0.3 3357 6120 -2763 -0.063
180 1.05 0.3 3393 6480 -3087 -0.071
Required Storage Volume: 1354 ft3
0.031 acre-ft
STAGE - STORAGE TABLE
(100-YEAR)
LOCATION: 4101 South Taft Ave
PROJECT NO: 385-01
COMPUTATIONS BY: PPK
SUBMITTED BY: North Star Design, Inc.
DATE: 8/1/2008
100 yr Detention Volume Required = 0.031 ac. ft. 1354 cf
Length of 24" PVC (L):
56' + 105' + 105' + 105' + 60' = 431 Linear feet
Cross sectional area of pipe (A):
Radius * Radius * pi = 3.14 Square feet
Total volume = L * A = 431 * 3.14 = 1354.0 cf
Detention Pond Outlet Sizing
(100 yr event)
LOCATION: 4101 South Taft Ave
PROJECT NO: 385-01
COMPUTATIONS BY: PPK
SUBMITTED BY: North Star Design, Inc.
DATE: 6/12/2018
Submerged Orifice Outlet:
release rate is described by the orifice equation,
Qo = CoAo sqrt( 2g(h-Eo))
where Qo = orifice outflow (cfs)
Co = orifice discharge coefficient
g = gravitational acceleration = 32.2 ft/s
Ao = effective area of the orifice (ft2)
Eo = greater of geometric center elevation of the orifice or d/s HGL (ft)
h = water surface elevation (ft)
Qo = 0.60 cfs
outlet pipe dia = D = 12.0 in
Invert elev. = 5152.20 ft
Eo = 5152.37 ft
h = 5154.2 ft - 100 yr WSEL
Co = 0.62
solve for effective area of orifice using the orifice equation
Ao = 0.089 ft2
= 12.8 in2
orifice dia. = d = 4.04 in
Check orifice discharge coefficient using Figure 5-21 (Hydraulic Engineering )
d / D = 0.34
kinematic viscosity, u = 1.22E-05 ft2/s
Reynolds no. = Red = 4Q/(pdu) = 1.86E+05
Co = (K in figure) = 0.62 check
Use d = 4.00 in
A o = 0.087 ft 2 = 12.57 in 2
Q max = 0.59 cfs
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1. Basin Storage Volume
A) Effective Imperviousness of Tributary Area, Ia Ia = 65.0 %
(100% if all paved and roofed areas upstream of rain garden)
B) Tributary Area's Imperviousness Ratio (i = Ia/100) i = 0.650
C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.20 watershed inches
(WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i)
D) Contributing Watershed Area (including rain garden area) Area = 14,956 sq ft
E) Water Quality Capture Volume (WQCV) Design Volume VWQCV = 253 cu ft
Vol = (WQCV / 12) * Area
F) For Watersheds Outside of the Denver Region, Depth of d6 = in
Average Runoff Producing Storm
G) For Watersheds Outside of the Denver Region, VWQCV OTHER = cu ft
Water Quality Capture Volume (WQCV) Design Volume
H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER = cu ft
(Only if a different WQCV Design Volume is desired)
2. Basin Geometry
A) WQCV Depth (12-inch maximum) DWQCV = 6in
B) Rain Garden Side Slopes (Z = 4 min., horiz. dist per unit vertical) Z = 4.00 ft / ft
(Use "0" if rain garden has vertical walls)
C) Mimimum Flat Surface Area AMin = 194 sq ft
D) Actual Flat Surface Area AActual = 614 sq ft
E) Area at Design Depth (Top Surface Area) ATop = 1127 sq ft
F) Rain Garden Total Volume VT= 435 cu ft
(VT= ((ATop + AActual) / 2) * Depth)
3. Growing Media
4. Underdrain System
A) Are underdrains provided? 1
B) Underdrain system orifice diameter for 12 hour drain time
i) Distance From Lowest Elevation of the Storage y = ft
Volume to the Center of the Orifice
ii) Volume to Drain in 12 Hours Vol12 = cu ft
iii) Orifice Diameter, 3/8" Minimum DO = in
Design Procedure Form: Rain Garden (RG)
Patricia Kroetch
North Star Design, Inc
June 12, 2018
4101 South Taft Ave
UD-BMP (Version 3.07, March 2018)
Choose One
Choose One
18" Rain Garden Growing Media
Other (Explain):
YES
NO
UD-BMP_v3.07.xlsm, RG 6/12/2018, 2:17 PM
Sheet 2 of 2
Designer:
Company:
Date:
Project:
Location:
5. Impermeable Geomembrane Liner and Geotextile Separator Fabric
A) Is an impermeable liner provided due to proximity
of structures or groundwater contamination?
PROVIDE A 30 MIL (MIN) PVC LINER WITH CDOT CLASS B
GEOTEXTILE ABOVE IT. USE THE SAME GEOTEXTILE BELOW
THE LINER IF THE SUBGRADE IS ANGULAR
6. Inlet / Outlet Control
A) Inlet Control
7. Vegetation
8. Irrigation
A) Will the rain garden be irrigated?
Notes:
Design Procedure Form: Rain Garden (RG)
Patricia Kroetch
North Star Design, Inc
June 12, 2018
4101 South Taft Ave
Choose One
Choose One
Choose One
Sheet Flow- No Energy Dissipation Required
Concentrated Flow- Energy Dissipation Provided
Plantings
Seed (Plan for frequent weed control)
Sand Grown or Other High Infiltration Sod
Choose One
YES
NO
YES
NO
UD-BMP_v3.07.xlsm, RG 6/12/2018, 2:17 PM
E
APPENDIX E
BMP SCHEDULE & COST ESTIMATE
Project: Disturbed Acres: 0.35
EROSION CONTROL BMPs Units
Estimated
Quantity
Unit
Price
Total
Price
L.F. 426 $3.00 $1,278.00
each 5 $85.00 $425.00
each $180.00 $0.00
each 1 $255.00 $255.00
each 1 $1,500.00 $1,500.00
each 1 $1,200.00 $1,200.00
Sub-Total: $4,658.00
1.5 x Sub-Total: $6,987.00
Amount of security: $6,987.00
Total Acres x Price/acre: $420.00
$1,200.00 Sub-Total: $420.00
1.5 x Sub-Total: $630.00
Amount to Re-seed: $630.00
Minimum escrow amount: $3,000.00
Erosion Control Escrow: $6,987.00
Miniumum Escrow Amount
4101 South Taft Hill Road
Unit Price of Seeding per acre:
“The amount of the security must be based on one and one-half times the estimate of the cost to install the approved measures, or one and one-half times
the cost to re-vegetate the disturbed land to dry land grasses based upon unit cost determined by the City's Annual Revegetation and Stabilization Bid,
whichever is greater. In no instance, will the amount of security be less than one thousand five hundred dollars ($1,500) for residential development or three
thousand dollars ($3,000) for commercial development”
Rock Sock
Vehicle Tracking Control Pad
Final Escrow Amount
Erosion and Sediment Control Escrow/Security Calculation
for The City of Fort Collins
BMP Amount
Silt Fence
Concrete Washout
Reseeding Amount
Rock Berm
Inlet Protection
6/12/2018 2:22 PM N:\385-01 South Taft site\drainage\FC Escrow.xls
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APPENDIX F
EROSION & SEDIMENT CONTROL REPORT
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EROSION & SEDIMENT CONTROLS
1. Written Analysis
An Erosion and Sediment Control Plan is included herewith. It should be noted, however,
that any such Erosion and Sediment Control Plan serves only as a general guide to the
Contractor. Staging and/or phasing of the BMPs depicted, and additional or different
BMPs from those included may be necessary during construction, or as required by the
authorities having jurisdiction.
It shall be the responsibility of the Contractor to ensure erosion control measures are
properly maintained and followed. The Erosion and Sediment Control Plan is intended to
be a living document, constantly adapting to site conditions and needs. The Contractor
shall update the location of BMPs as they are installed, removed or modified in
conjunction with construction activities. It is imperative to appropriately reflect the
current site conditions at all times.
The Erosion and Sediment Control Plan shall address both temporary measures to be
implemented during construction, as well as permanent erosion control protection. Best
Management Practices from the Volume 3, Chapter 7 - Construction BMPs will be
utilized. Measures may include, but are not limited to, silt fencing along the disturbed
perimeter, gutter protection in the adjacent roadways and inlet protection at proposed
storm inlets. Vehicle tracking control pads, spill containment and clean-up procedures,
designated concrete washout areas, dumpsters, and job site restrooms shall also be
provided by the Contractor.
Grading and Erosion Control Notes can be found on Sheet 2 of the Utility Plans. In
addition to this report and the plan sheets, the Contractor shall be aware of and adhere to
the applicable requirements outlined all Development Agreements pertaining to this
property. Also, the Site Contractor for this project will be required to secure a
Stormwater Construction General Permit from the Colorado Department of Public Health
and Environment (CDPHE), Water Quality Control Division - Stormwater Program,
before commencing any earth disturbing activities. The Contractor shall also develop a
comprehensive Storm Water Management Plan (SWMP) conforming to applicable
requirements including descriptions of the ongoing activities, inspections and
maintenance of construction BMPs.
H
•
The site is approximately .35 acres all of which will undergo earthmoving operations.
The existing site has existing ground cover (volunteer grasses and weeds) on approximate
45% - 50% of the site as the site has been historically used for storage of materials and
vehicles for adjacent properties.
Runoff from this site currently discharges to Conifer Street on the south side of the site.
With the proposed development, this site will also be sloped to drain to the southeast.
The runoff will then enter the proposed detention pond and be released to the existing
storm system in Conifer Street as the historic flow path dictates.
The soils on this site are classified by the USGS Soil Survey as Caruso Clay Loam (3%)
which is classified in the hydrologic group D and Nunn Clay Loam (97%) which is
classified in the hydrologic group C. The D soils are described as having a very slow
infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of
clays that have a high shrink-swell potential, soils that have a high water table, soils that
have a claypan or clay layer at or near the surface, and soils that are shallow over nearly
impervious material. These soils have a very slow rate of water transmission. The rainfall
erodibility is deemed to be moderate and the wind erodibility is deemed to be moderate to
high. The C soils are described as having a slow infiltration rate when thoroughly wet.
These consist chiefly of soils having a layer that impedes the downward movement of
water or soils of moderately fine texture or fine texture. These soils have a slow rate of
water transmission. The rainfall erodibility is deemed to be moderate and the wind
erodibility is deemed to be moderate to high.
The site is surrounded by developed sites including streets, buildings and paved areas.
The construction shall utilize silt fence around the perimeter to control sediment transport
from rainfall and from wind. The silt fence that is located in the proposed pavement areas
will be removed prior to placing new pavement. Rock socks will be utilized in the
existing curb and proposed bio swales to capture sediments that are not fully contained
by the silt fence placement. The locations of the rock socks will be in the areas of
concentrated flow such as in the existing curb, at the concrete sidewalk chase and on the
concrete pans.
The site will also utilize a vehicle tracking control pad to minimize sediment from being
tracked onto adjacent pavements. Sediment that is tracked will be removed and placed
I
within the site or permanently disposed of offsite. A concrete washout will be used on
site during the concrete placement. All hardened concrete will be disposed of offsite.
These BMP’s have not been located on the site map due to the fact that the site is very
small and these BMP’s will need to be placed by the contractor in locations that are most
beneficial and will minimize disruption of adjacent traffic.
Permanent erosion control consists of covering the soils with a building, concrete walks,
concrete pavement, recycled asphalt pavement and sod. No soil will be left exposed to
erosion after the construction is complete. Refer to the landscape plan for areas of and
instructions for placement of sod and soil amendments required prior to placement of
sod.
Refer to Appendix for the timing of the construction phases and the sequential
installation of all BMP phasing for this site.
Refer to the Appendix for the Erosion Control Surety calculations.
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2. SWMP contact information
Permit holder:
Name:
Address:
Phone Number:
Email Address:
Appointed agent:
Name:
Address:
Phone Number:
Email Address:
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3. Identification and location of all potential pollution sources
Potential Pollutant Source Activity Potential Pollutant
Generated
Applicable to
this project
Control Measure
Disturbed Areas Sediment X Silt Fence, Rock Socks
Soil stockpiles Sediment X Silt Fence, Rock Socks
Travel to adjacent public streets Tracked sediment X Tracking Pad, street sweeping
Contaminated soils Sediment, chemicals Possible Remove contaminated soils
from site **
Loading and unloading chemicals Chemicals
Unloading of building materials Trash, debris, track out X Trash dumpsters, Waste
Management Firm **
Outdoor storage of chemicals Chemicals
On site equipment maintenance Oil, grease
On site equipment fueling Diesel, gasoline X Containment berm **
Dust generating activities Particulates, sediment X Water truck
Use of fertilizer, pesticides, herbicides Fertilizer, pesticides
Use of detergents, solvents, oils Detergents, solvents, oil X
If spilled, remove
contaminated soils from site
**
Waste Chemicals, trash, debris X Waste Management Firm
Concrete wash Concrete, sediment, wash
water X
Remove hardened concrete,
dispose of offsite **
On site equipment washing Detergents, oil
On site asphalt batch plant Asphaltic cement, sediment
On site concrete batch plant Cement, sediment
Portable toilets Domestic sewage X Waste Management Firm
** Refer to Section 5 for additional Materials Handling & Spill Prevention BMP
4. Best Management Practices (BMP’s) for Stormwater Pollution Prevention
Structural Practices for Erosion and Sediment Control
Structural practices for the site will consist mainly of silt fence and rock sock filters and
are described in detail in the following paragraphs. These BMP's are expected to change
as the construction progresses and it is the responsibility of the contractor to ensure
appropriate BMP's are in place and/or removed at the appropriate time in the construction
sequence. All temporary and permanent erosion and sediment control practices must be
maintained and repaired as needed to assure continued performance of their intended
function.
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Silt fence and rock sock filters shall be in place prior to commencement of construction
activities. During clearing and grubbing necessary for silt fence installation, all cleared
material shall be placed on the uphill side so that if erosion occurs from the cleared
material, the sediment will be trapped and not transported downstream. Rock socks shall
be implemented in the existing curb line as shown on the Drainage & Erosion Control
Plan.
A vehicle tracking pad will be installed at a location most beneficial to the site
construction as determined by the contractor. Vehicles will not be permitted in the
excavated area if soil is muddy. Gravel sub base will be placed and compacted in the
areas indicated for pavement following excavation.
All BMP's shall be installed per the details shown on the construction plan set.
Temporary & Permanent Structural BMP’s:
Refer to table in Section 3 for purpose of Structural BMP noted below
Structural BMP Approximate location on site Applicable to this
Project
Silt Fence Site perimeter, refer to site map X
Rock Socks At existing sidewalk culverts, in existing
gutters, refer to site map X
Earthen diversion dams
Vegetated swales
Sediment trap/pond
Pipe slope drains
Geogrid
Inlet/outlet protection
Culverts Refer to site map X
Riprap
Erosion control mats
Inlet protection
Vehicle Tracking Control Pad At site entrance, refer to site map X
Concrete Washout To be located by Contractor X
Non-Structural Practices for Erosion and Sediment Control:
Soils exposed during the earthwork phase and landscape prep phase shall be kept in a
roughened condition by ripping or disking along land contours until mulch, vegetation, or
other permanent erosion control is installed. No large amount of soils (in excess of 15
yards) will be allowed to be stock piled on site. Overburden from the utility pipe
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trenching will be piled adjacent to trenches upstream of sediment controls and will be
replaced in the trenches within 72 hours.
Excess excavated materials from the demolition and grading phases of the project that
cannot be reused on site will be exported as it is excavated. This includes any asphalt
pavement from the existing site that is to be removed.
In the current pre construction state the site enables tracking of silt onto the adjacent
streets during wet conditions. During construction activities the street will be monitored
for foreign debris tracked out of the site and mechanical sweeping and clean up will be
performed as needed.
No area shall remain exposed by land disturbing activity for more than thirty (30) days
before required temporary or permanent erosion control (e.g. seed/mulch, landscaping,
etc.) is installed.
Temporary & Permanent non-structural BMP’s:
Refer to table in Section 3 for purpose of Non Structural BMP noted below
Non-Structural BMP Approximate location on site Applicable to this
Project
Surface roughening Entire site X
Soil stockpile height limit (less than
10’)
Perimeter vegetative buffer east boundary of site X
Minimization of site disturbance
Mulch
Seed & mulch stockpiles after 30 days
Preservation & protection of existing
vegetation & trees east boundary of site X
Good site housekeeping (routine
cleanup of trash & constr debris) Entire Site X
Sweeping & scraping of hardscape
areas On and off site pavements X
Heavy equip staged on site, properly
maintained & inspected daily (no
onsite maintenance)
Staging area X
N
5. Material Handling & Spill Prevention
Refer to table in Section 3
Materials Handling & Spill Prevention BMP Approximate location on site Applicable to
this Project
Portable toilets, anchored & located away from
drainages Contractor to determine X
Fuel storage located in bulk tanks with secondary
containment & spill kit
Mobile fueling performed at least 200 feet away from
drainages & fully attended Contractor to determine X
Fertilizers, form oil, solvents, cleaners, detergent
stored in 55 gal or smaller containers, kept in storage
units
Contractor to determine X
Dumpsters containing used chemicals containers &
liquid wastes kept covered Contractor to determine X
Equipment cleaning (on site) uses no detergents &
flows to onsite retention basin
In case of a release of fuel or other chemicals,
absorbent booms or earthen berms will be immediately
constructed to contain the spill & prevent runoff to
adjacent surface waters
Location of spill X
MSDS sheets for onsite chemicals will be kept at the
construction trailer to facilitate spill response &
cleanup
Contractor to determine X
B) Dedicated Asphalt or Concrete Batch Plant:
Not proposed with this development
C) Vehicle Tracking Pad:
Vehicle tracking control pad shall be installed wherever construction vehicle access
routes intersect paved public roads. Vehicle tracking control pads shall be installed to
minimize the transport of sediment (mud) by runoff or vehicles tracking onto the paved
surface. Any mud tracked to public roads shall be removed on a daily basis and after any
significant storm that causes sediment to be transported. It is unlawful to track
sediment/mud onto public streets and may be enforced by the City of Fort Collins, by the
State of Colorado or by the EPA.
D) Waste Management and Disposal:
Portable toilets will be anchored & periodically maintained by waste management
company. Dumpsters on site will be covered & periodically emptied by waste
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management company. Concrete waste will be allowed to harden and then will be
removed from site.
No vehicle or equipment washing activities will occur on site.
Location of the concrete washout is shown on the site map. The washout will be
sufficiently deep to accommodate all anticipated concrete truck wash water. Waste
concrete will be allowed to harden and be removed from site periodically as the washout
reaches 50% of its capacity. Truck wash water will not be allowed to reach the curb &
gutter or any other water course.
E) Groundwater and Stormwater Dewatering:
No groundwater was encountered during soils exploration therefore ground water is not
anticipated to be an issue. If groundwater is encountered a groundwater discharge permit
shall be obtained and a detailed report shall be completed describing the location and the
route of where pumped groundwater will be conveyed and the measures taken to prevent
the transport of any pollutants to downstream waters.
6. BMP Implementation
A) Phased BMP Implementation
BMP’s are expected to change as the construction progresses and it is the responsibility
of the contractor to ensure appropriate BMP’s are in place and/or removed at the
appropriate time in the construction sequence. A construction sequence schedule has
been included on the Drainage & Erosion Control Plan and included in the construction
plans for this site.
All BMP’s shall be inspected and repaired or replaced as required to satisfy the
conditions of the Stormwater Discharge Permit. All BMP’s must be maintained and
repaired as needed to assure continued performance of their intended function. Refer to
Appendix E for the BMP schedule and estimated costs.
B) Inspection & Maintenance:
It is required that routine site inspections are performed to effectively address
maintenance and repair of Best Management Practices (BMP's). The site inspections are
to performed by the contractor or an inspector designated by the administrator at a
minimum of once every fourteen (14) calendar days on active construction sites and after
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any significant storm event (an event causing runoff). As part of the site inspections the
inspector is required to keep documentation of all inspections and BMP maintenance,
including an updated Site Map indicating new BMP's or the removal of BMP's since the
previous inspection.
Any maintenance, repair, or necessary installation of BMP's that are noted during the
inspection must be completed within seven (7) calendar days from the date of the
inspection.
7. Soil Amendments, Permanent Seeding & Mulching
A) Soil Amendments
Soil in the Rain Gardens shall be amended per the City of Fort Collins Bioretention Sand
Media Specifications found at:
http://www.fcgov.com/utilities/img/site_specific/uploads/Bioretention_Sand_Media_Specs.pdf
Soil treatment in the detention area will be to spread imported or stockpiled topsoil to a
minimum depth of four inches over areas to be planted.
B) Permanent Seeding
The following seed mix shall be applied at the rates indicated in the bioswale and in the
water quality pond. Other landscaped areas on site shall be treated per the landscape plan.
Mulch shall be applied after seeding as the notes indicate below.
Drill seed specified mix in two passes, each at right angles to each other. Drill half of the
seed in each pass. If areas are too wet or steep to drill seed, broadcast seed in two
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opposite directions. Restore fine grade after seeding, and cover seed to depth of 1/4 inch
by raking or dragging. Firm seeded areas with a roller weighing maximum of 100 lbs. per
foot of width. Ground cover shall be considered established when 70% of the seed has
been germinated. At the point that the seed is considered established, the temporary
erosion control measures may be removed.
C) Mulching
All planted areas should be mulched preferably immediately following planting, but in no
case later than 14 days from planting. Mulch conserves water and reduces erosion. The
most common type of mulch used is hay or grass that is crimped into the soil to hold it.
However, crimping may not be practical on slopes steeper than 3:1. The following
guidelines should be followed with mulching:
• Only weed-free and seed-free straw mulch should be used (grass hay often
contains weedy exotic species). Mulch should be applied at 2 tons/acre and
adequately secured by crimping, tackifier, netting, or blankets.
• Crimping is appropriate on slopes of 3:1 or flatter and must be done so as to
tuck mulch fibers into the soil 3 to 4 inches deep.
• Tackifier or netting and blankets anchored with staples should be used on slopes
steeper than 3:1.
• Hydraulic mulching may also be used on steep slopes or where access is limited.
Wood cellulose fibers mixed with water at 2,000 to 2,500 pounds/acre and
organic tackifier at 100 pounds per acre should be applied with a hydraulic
mulcher.