HomeMy WebLinkAboutPECK APARTMENTS - PDP/FDP - FDP130031 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTA
%4
0
LOCATION:
PROJECT NO:
COMPUTATIONS BY
SUBMITTED BY:
DATE:
100yr ORIFICE PLATE SIZING
Detention Pond Outlet Sizing
(100 yr event)
218 Laurel Street
348-0 l
ppk
North Star Design, Inc
7/23/2013
Submerged Orifice Outlet:
release rate is described by the orifice equation,
Qo = COAO sqrt( 2g(h-E,))
where Qo =
orifice outflow (cfs)
Co
= orifice discharge coefficient
g
= gravitational acceleration = 32.2 ft/s
Ao
= effective area of the orifice (ft')
E.
= greater of geometric center elevation of the orifice or d/s HGL (ft)
h
= water surface elevation (ft)
Qa
= 0.08 cfs
outlet pipe dia = D
= 6.0 in
Invert elev.
= 4996.15 ft
Eo
= 4996.22 ft
h
= 4997.50 ft - 100 yr WSEL
Co
= 0.63
solve for effective area of orifice using the orifice equation
Ao = 0.014 ftz
2.0 in
orifice dia. = d = 1.60 in
Check orifice discharge coefficient using Figure 5-21 (Hydraulic Engineering)
d / D = 0.27
kinematic viscosity, u = 1.22E-05 ft2/s
Reynolds no. = Red = 4Q/(pdu) = 6.26E+04
Ca = (K in figure) = 0.63 check
Use d = 1.60 in
Aa = 0.014 ft2 = 2.01 in'
Q mar = 0.08 cfs
Detention pond.xls
N
u
Northstar Design, Inc
700 Automation Drive, Unit I
Windsor CO, 80550
(970)686-6939
LOCATION:
PROJECT NO:
COMPUTATIONS BY
SUBMITTED BY:
DATE:
Proposed Stage/Storage
218 Laurel Street
348-01
TDS
North Star Design
7/23/2013
V = 1/3 d ( A + B + sgrt(A'B))
where V = volume between contours, ft3
d = depth between contours, It
A = surface area of contour
REQ. 100 YR DETENTION VOL. = 550 Cu.Ft.
Stage
(ft)
Surface
Area
W)
Incremental
Storage
(cu-ft)
Total
Storage
(cu-ft)
96.15
0
97.00
537
152.150
152
97.50
1140
409.903
562
455
945
Detention pond.xls
Stage -Storage
t
Northstar Design, Inc
700 Automation Drive, Unit I
Windsor CO, 80550
(970) 686-6939
LOCATION:
ITEM:
COMPUTATIONS BY:
SUBMITTED BY:
DATE:
WATER QUALITY POND OUTLET SIZING
218 Laurel Street
Detention Pond
PPK
North Star Design, Inc
7/23/2013
From Urban Storm Drainage Criteria Manual, June 2001
(Referenced figures are attached in Appendix D)
Use 40-hour brim -full volume drain time for extended detention basin
Water Quality Capture Volume = WQCV = (required storage/12)'(tributary drainage area)
MAJOR
BASIN
Trib.
area
(ac)
% Imperv.
Req. Storage
(in. of runoff)
WQCV
(ac-ft)
DWQ
(ft)
req. vol
WQCV `1.2
(ac-ft)
req. area/row
(in 2/row)
Pond 1
0.12
61.00
0.240
0.002
0.50
0.003
0.22
Required Storage = 1 " ( 0.91 " 1A3 - 1.19 " IA2 + 0.78 " 1 )
WQ outlet sizing
From Figure 5,
for 1/2 in. hole diameter
Area of hole = 0.20 in
# of columns = 1
Area provided/row = 0.20 in
Area Required/row = 0.22 in
Use 1 column of 112" diam holes
Detention pond.xls WQCV-NOT USED
125 cf
Fr
10
v
-4
100 YEAR MINIMUM DETENTION VOLUME REQUIRED
FAA METHOD
LOCATION:
218 Laurel Street
PROJECT NO:
348-01
COMPUTATIONS BY:
ppk
SUBMITTED BY:
North Star Design, Inc
DATE:
7/23/2013
Equations:
Qo = CiA
V; = T*CiA =
T*Qo
Vp -In*QPo*(60*T)
S=V; -Vo
Rainfall intensity from Larimer County Area I IDF Curve
A trib. To pond =
0.12 acre
C100 =
0.61
Developed C*A =
0.07 acre
QPo =
0.08 cfs
tc =
5.1 min
Storm
Duration, T
(min)
Rainfall
Intensity, i
(in/hr)
QD
(cfs)
Vol. In
V;
(ft3)
Outflow
Adjustment
Factor, m
Vol. Out
Vo
(ft3)
Storage
S
(ft3)
Storage
S
(ac-ft)
5
9.95
0.7
197
1.00
25
171
0.004
10
7.72
0.6
305
0.76
38
267
0.006
20
5.60
0.4
443
0.63
63
379
0.009
30
4.52
0.3
536
0.59
88
448
0.010
40
3.74
0.3
591
0.56
1 114
478
0.011
50
3.23
0.2
638
0.55
139
500
0.011
60
2.86
0.2
678
0.54
164
514
0.012
70
2.62
0.2
725
0.54
189
536
0.012
80
2.38
0.2
753
0.53
214
538
0.012
90
2.22
0.2
790
0.53
240
550
0.013
100
2.05
0.2
810
0.53
265
545
0.013
110
1.93
0.1
839
0.52
1 290
549
0.013
120
1.80
0.1
854
0.52
315
539
0.012
130
1.60
0.1
822
0.52
340
482
0.011
140
1.40
0.1
775
0.52
366
409
0.009
150
1.20
0.1
712
0.52
391
321
0.007
160
1.15
0.1
727
0.52
416
311
0.007
170
1.10
0.1
739
0.52
441
298
0.007
180
1.05
0.1
747
0.51
466
281
0.006
Required Storage Volume: 550 ft 3
0.013 acre-ft
APPENDIX C
DETENTION POND CALCULATIONS
C
North Star Design, Inc.
700 Automation Drive, Unit I
Windsor, CO 80550
RATIONAL METHOD PEAK RUNOFF
(100-YEAR)
LOCATION: 218 Laurel
PROJECT NO: 348-01
COMPUTATIONS BY: PPK
DATE: 7/23/2013
DIRECT RUNOFF
TOTAL
Inlet Capacity
REMARKS
DESIGN
POINT
SUBBASIN
ID
A
(ac)
Cino
t,
(min)
i
(in/hr)
O100
(cfs)
Oiuo Total
(cfs)
(cfs)
EX 1
EX 1
0.15
0.58
5.9
9.55
0.85
0.9
DEV 1
DEV 1
0.12
0.61
5.1
9.91
0.76
0.8
DEV 2
DEV 2
0.03
0.73
5.0
9.95
0.23
0.2
Q=CiA
Q = peak discharge (cfs)
C = runoff coefficient
i = rainfall intensity (in/hr) from OF curve
A = drainage area (acres)
Flow site.xls 0100
s
North Star Design, Inc.
700 Automation Drive, Unit I
Windsor, CO 80550
RATIONAL METHOD PEAK RUNOFF
(10-YEAR)
LOCATION:
218 Laurel
PROJECT NO:
348-01
COMPUTATIONS BY:
PPK
DATE:
7/23/2013
DIRECT RUNOFF
TOTAL
Inlet Capacity
REMARKS
DESIGN
POINT
SUBBASIN
ID
A
(ac)
Coo
t�
(min)
i
(in/hr)
Qio
(cfs)
Quo Total
(cfs)
(cfs)
EX 1
EX 1
0.15
0.42
5.9
4.67
0.30
0.3
DEV 1
DEV 1
0.12
0.48
5.1
4.85
0.29
0.3
DEV 2
DEV 2
0.03
0.64
5.0
4.87
0.10
0.1
Q=CiA
Q = peak discharge (cfs)
C = runoff coefficient
i = rainfall intensity (in/hr) from OF curve
A = drainage area (acres)
Flow site.xls Q 10
North Star Design, Inc.
700 Automation Drive, Unit I
Windsor. CO 80550
RATIONAL METHOD PEAK RUNOFF
(2-YEAR)
LOCATION:
218 Laurel
PROJECT NO:
348-01
COMPUTATIONS BY:
PPK
DATE:
7/23/2013
DIRECT RUNOFF
TOTAL
Inlet Capacity
REMARKS
DESIGN
POINT
SUBBASIN
ID
A
(ac)
C2
tc
(min)
i
(in/hr)
Qz
(cfs)
Qz Total
(cfs)
(CIS)
EX 1
EX 1
0.15
0.28
5.9
2.73
0.12
0.1
to alley
DEV 1
DEV 1
0.12
0.37
5.1
2.84
0.13
0.1
to Linden
DEV 2
DEV 2
0.03
0.57
5.0
2.85
- 0.05
1 0.1
Ito alley
Q=CiA
Q = peak discharge (cfs)
C = runoff coefficient
i = rainfall intensity (in/hr) from IDF curve
A = drainage area (acres)
Flow site.xls Q2
North Star Design, Inc.
700 Automation Drive, Unit I
Windsor, CO 80550
TIME OF CONCENTRATION
LOCATION:
218 Laurel
PROJECT NO:
348-01
COMPUTATIONS BY:
PPK
DATE,
7/23/2013
SUB -BASIN DATA
INITIAL OVERLAND TIME
(t;)
TRAVEL TIME I GUTTER OR CHANNEL FLOW
(Q)
t, CHECK
(URBANIZED BASIN)
FINAL
I�
REMARKS
DESIGN
POINT
SUBBASIN
ID
(1)
Area
(ac)
(2)
Cs
(3)
Length
(ft)
(4)
Slope
(ft/ft)
(5)
t,
(min)
(6)
Length
(ft)
(7)
Slope
(ft/ft)
(8)
Chan.
Type
C,
Vel.
(fNs)
(9)
I,
(min)
(10)
t� =
ti+❑
(11)
Total L
(ft)
(12)
t�= (1/180)+10
(min)
(13)
(min)
(14)
EX 1
EX 1
0.15
0.35
23
0.020
5.2
68
0.007
F
20
1.7
0.7
5.9
91
10.5
5.9
DEV 1
DEV 1
0.12
0.42
10
0.040
2.5
164
0.005
E
15
1.1
2.6
5.1
174
11.0
5.1
DEV 2
DEV 2
0.03
0.60
18
0.050
2.3
84
0.007
F
20
1.7
0.8
3.1
102
1 10.6
5.0
EQUATIONS:
t�=ti+I,
I, = (0.395 (1.1 - CS ) Lo.S ] / S 1/3
tt = L/V V = C `So.s
final t, = minimum of D, + tt and urbanized basin check
minimum t, = 5 minutes
Channel Type
C„
A
Heavy Meadow
2.5
B
Tillage/Field
5.0
C
Short Pasture/ Lawn
7.0
D
Bare Ground
10.0
E
Grassed Waterway
15.0
F
Paved
20.0
Flow site.xls T005
North Star Design, Inc.
700 Automation Drive, Unit I
Windsor, CO 80550
RUNOFF COEFFICIENTS & % IMPERVIOUS
LOCATION:
218 Laurel
PROJECT NO:
348-01
COMPUTATIONS BY:
PPK
DATE:
7/23/2013
Recommended % Impervious from Urban Storm Drainage Criteria Manual
Impervious
Roofs:
90%
Streets and Parking (Asphalt)
100%
Concrete Drives and Walks
90%
Packed Gravel:
40%
Landscaped Areas (Clayey soil, 0-1 %
SUBBASIN
ID
TOTAL
AREA
(ac.)
TOTAL
AREA
(sq.ft)
ROOF
AREA
(sQ.ft)
ASPHALT
AREA
(s4.ft)
CONCRETE
AREA
(sg.ft)
GRAVEL
AREA
(sQ.ft)
LANDSCAPE
AREA
(sq.ft)
%
Impervious
RUNOFF
COEFF.
Ci
RUNOFF
COEFF.
Cs
RUNOFF
COEFF.
CID
RUNOFF
COEFF.
Goo
EX 1
0.15
6,653
1,573
403
786
340
3,551
40%
0.28
0.35
0.42
0.58
DEV 1
0.12
5,425
3,240
0
35
0
2,150
54%
0.37
0.42
0.48
0.61
DEV 2
0.03
1,398
0
0
1,210
0
188
78°/
0.57
0.60
0.64
0.73
Flow site.xis Cval
APPENDIX B
HYDROLOGIC COMPUTATIONS
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Ell
lillli==■illl:!■�Il:iill� ��='illlllll@ ice=
Pup ;F-1 ff- FIT
I u -- �1 -
n9w'i
I�PROJECT-II
LOCTI AON -
i Ir? i
EAST ELIZABETH STREET
wriEAST PITKIN u
VICINITY MAP
APPENDIX A
VICINITY MAP
►r]
7. REFERENCES
City of Fort Collins, "Storm Drainage Criteria Manual", (SDCM), dated March,
1986.
2. Urban Drainage and Flood Control District, "Urban Storm Drainage Criteria
Manual", Volumes 1 and 2, dated March, 1969, and Volume 3 dated September,
1992.
13
IX
R I,
_ 9�4)
II
�I 10 s 0 10 20
SCALES 1' 10'
EOP
¢� 090
I I III ati
TDID
I
PROPOSED LANDSCAPE WALL
1 W-9).5
BW-9).0
-- - - - -- - "ail ���� T
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1
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TOP
OP BERM-499).Sdo
q��ryryEO�
TOP OF BERM-4997.5
---- - - --- -
h
- ,-------? ,
------ - -_ - -- - -
I
So1.ww
PROPOSED ,• WIDE
PROPOSED lANDSLAPE
METAL 9"" CULVERT.
; WAIL W/1.6" Dim ORENwG
_
sAWESAm T WALK As
FEESSARt M WSTALL
MEC
CUT T WOE OPENING IN
E10511NG "o HEAD
WEST LAUREL STREET
GRADING PLAN
SF
I
I
I
DETENTION POND
I
I
I
•, I
i
T
12 0.4
DETENTION POND
HWEL-41197.51
J�
WEST LAUREL STREET
CALL UTLl7Y NOTIFICATION
CENTER OF COLORADO
1-800-922.1987 (811)
C 2-BUSINESS DAYS IN ADVANCE
BEFORE YOU DIG. GRADE. OR EXCAVATE
FOR TIE MARKING OF UNDERGROUND
MEMBER UTILITIES.
THIS SECTION OF SILT FENCE To BE REYOMED
PRIOR TO GONCRETE INSTALLATION. ALL OTHER
SILT FENCE SHALL REMI FDA THE DURATION
OF THE CONSTRUCTION
I
LEGEND
I
iT FT ISNED ROOD
PROPERTY BOUNDARY
FC FINISHED CRADF
— RI.1-OF-WAY
iLO
ADJACENT PROPERTY LINE
1
NP NIGH ON,
O
- EASEMENT LINE
1
LP LOW POMi
'-m _.910- - - - - - EXISTING CONTOURS
1
EOA EDGE OF ASPHALT
491, PROPOSED CONTOURS
RE EDGE OF CONCRETE
PROPOSED ROWI
TOA TOP OF ASPHALT
PROPOSED 2 CONCRETE PAN
TCC TOP OF CONCRETE
_ _ _ _ _ _ _ _ _ _ = E JSTNG DRAINAGE PIPE
I •
TOW TOP OF WALK
gIPRAP
1
EN EXISTING
A.
J I
DESIGN PONT
J
-
Q .I
BASH CRITERIA
I _
0.26 0.9 5 m RUNOFF COFFFlCIENT
AREA IN ACRES
^ ROW DIRECTION
D 60L1
R 9TI IF a¢R 6¢ BASIN BWNDART
I
1
O—SF—SF—
SILT FENCE
-
I
1
®
_ VEHICLE mACKwc PAD
CW
CONCRETE WASNOUT AREA
II
I!
i
RS�
ROCK SOLI(
STRAW WATRE
r�
I
I!
I
I.
5' WE UD WALE
SEE DETAIL SNIEE-E 5
_ . .
- .. W615CA➢E WALL WTH T.o-
4 DIAM OPENING FOR DEIENTpN
RELEASE
,
DRAINAGE & EROSION CONTROL PLAN
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City of Fort Collins. Colorado N
UTILITY PLAN APPROVAL
APPROVED:
City Enpnm D.I. SHEET
CHECKED BY:
wotw h wmb.otw oUitr oete
CHECKED BY: s4
tm.�.Ob. uuny and
CHECKED BY:
Pw4. h flmw\im Date
4 OF 6
CHECKED BY:
huNc E.9—. G.t.
CHECKED BY: Job No. 348-0I
D.t.
of any pollutants to downstream waters.
7) 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 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.
6. CONCLUSIONS
6.1 Compliance with Standards
All computations that have been completed within this report are in compliance with the
City of Fort Collins Storm Drainage Design Criteria Manual and the Old Town Master
Drainage Plan.
6.2 Drainage Concept
The proposed drainage concepts presented in this report and on the construction plans
adequately provide for conveyance of runoff to the detention areas. Conveyance
elements have been designed to pass required flows and to minimize future maintenance.
If, at the time of construction, groundwater is encountered, a Colorado Department of
Health Construction Dewatering Permit would be required.
12
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 or by the State of Colorado.
5) 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
management company. Concrete waste will be allowed to harden and then will be
removed from site.
No washing activities will occur on site.
Location of the concrete washout will be determined by the contractor. 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.
6) Groundwater and Stormwater Dewatering:
No groundwater encountered during soils exploration
therefore 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
2 Materials Handling and S ill Prevention:
Materials Handling & Spill
Approximate location on site
Applicable to this
Prevention BMP
Project
Portable toilets, anchored &
Contractor to determine
X
located away from drainages
Fuel storage located in bulk tanks
with secondary containment &
spill kit
Mobile fueling performed at least
200 feet away from drainages &
Contractor to detennine
X
fully attended
Fertilizers, form oil, solvents,
cleaners, detergent stored in 55 gal
Contractor to determine
X
or smaller containers, kept in
storage units
Dumpsters containing used
chemicals containers & liquid
Contractor to determine
X
wastes kept covered
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
Location of spill
X
constructed to contain the spill &
prevent runoff to adjacent surface
waters
MSDS sheets for onsite chemicals
will be kept at the construction
Contractor to determine
X
trailer to facilitate spill response &
cleanup
3) Dedicated Asphalt or Concrete Batch Plant:
Not proposed with this development.
4) 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
E
SEDIMENT/EROSION CONTROL
BEST MANAGEMENT PRACTICES (BMPs)
COST OPINION SPREADSHEET
218 West Laurel Street
Item
No.
BMP
ID
Unit
Installation
Unit Cost
Maintenance
as % of
Installation
Installation &
Maintenance
Unit Cost
Quantity
Cost
1
Check Dam
CDR
LF
25%
$0.00
$0.00
2
Check Dam (Reinforced)
CDR
LF
25%
$0.00
$0.00
3
Concrete Washout Area
CWA
EA
$1,200.00
200%
$3,600.00
1
$3,600.00
4
Construction Fence
CF
LF
25%
$0.00
$0.00
5
Construction Markers
CM
LF
50%
$0.00
$0.00
6
Culvert Inlet Filter
CIF
LF
25%
$0.00
$0.00
7
Dewatering
DW
EA
50%
$0.00
$0.00
8
Diversion Ditch (Unlined)
DD
LF
25%
$0.00
$0.00
9
Diversion Ditch (ECM or plastic)
DD
LF
10%
$0.00
$0.00
10
Sediment/Erosion Control Matting
ECM
SY
25%
$0.00
$0.00
11
Inlet Protection
IP
LF
50%
$0.00
$0.00
12
Reinforced Rock Berm
RRB
LF
25%
$0.00
$0.00
13
Sediment Basin (1)
SB
LF
25%
$0.00
$0.00
14
Sediment Control Log (Wattle)
SCL
LF
$4.60
25%
$5.75
0
$0.00
15
Seeding and Mulching
SM
AC
50%
$0.00
$0.00
16
Silt Fence
SF
LF
$3.00
75%
$5.25
370
$1,942.50
17
Rock Sock
RS
LF
$10.00
10%
$11.00
30
$330.00
18
Stabilized Staging Area
SSA
SY
50%
$0.00
$0.00
19
Surface Roughening
SR
AC
25%
$0.00
$0.00
20
Temporary Stream Crossing
TSC
EA
25%
$0.00
$0.00
21
Topsoil (6-inch Lift)
TSL
AC
$2,500.00
25%
$3,125.00
0.06
$187.50
22
lVehicleTrackin Control(2)
VTC
EA
$1,500.00
100%
$3,000.00
1
$3,000.00
Contractor Added BMP(s) (3)
23
%
$0.00
24
%
$0.00
25
%
$0.00
26
%
$0.00
27
%
$0.00
P8
%
$0.00
SUBTOTAL COST $9,060.00
CONTINGENCY 15% $1,359.00
TOTAL COST lot $10,419.00
erosion control associated with each phase in order to comply with the SWM Plan and
Permit that is obtained by the contractor (or owner) for the site.
Phase 1 — Mobilization
Install silt fence, Install rock socks, set dumpster.
Phase 2 — Clear site, Overlot Grading
Clear existing house, concrete and treess. Cut and fill on site to achieve subgrade
elevations
Phase 3 - Utilities
Excavate and install for water service, fire line and sewer service modification, excavate
and install dry utilities
Phase 4 — Install Concrete Foundation
Establish temporary concrete washout area, cut for building foundation, place
concrete foundation.
Phase 5 — Concrete Site Paving
Remove silt fence in pavement area, Install sub base, install Concrete pavement. Remove
concrete wash out.
Phase 6 — Building construction
Complete vertical building construction
Phase 7 — Landscape installation
Final shaping of detention pond, install LID Swale, final shape planting areas, Install
irrigation system, Install soil amendments, Landscape plant installation, Install mulch
ground cover
Phase 8 — Final Stabilization
Final stabilization is complete when constructed improvements are in place, Inspect
completed construction for possible sources of erosion and amend the plan as required to
trap sediments.
E
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:
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
West boundary of site
X
Minimization of site disturbance
Mulch
Seed & mulch stockpiles after 30
days
Stockpile toe protection (silt fence,
wattles or ditch)
Preservation & protection of
West boundary of site
X
existing vegetation & trees
Good site housekeeping (routine
Entire Site
X
cleanup of trash & constr debris)
Heavy equip staged on site,
properly maintained & inspected
Staging area
X
daily (no onsite maintenance)
5.5 BMP Implementation
1) 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. 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.
The following phase depictions and erosion controls are suggestions to the contractor only
and are in no way intended to dictate construction phasing or control of the work on site.
The contractor shall be responsible to control construction phasing and provide adequate
N
All BMP's shall be installed per the details shown on the construction plan set.
Temporary & Permanent Structural BMP's:
Structural BMP
Approximate location on site
Applicable t this
Project
Silt Fence
Site perimeter, refer to site map
X
Straw bale dams
Rock Socks
At proposed sidewalk culverts, refer to site
map
X
Earthen diversion darns
Vegetated swales
Sediment trap/pond
Pipe slope drains
Geogrid
Inlet/outlet protection
Culverts
Riprap
Erosion control unats
Inlet protection
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 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.
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. 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.
7
m
5.3 Identification and location of all potential pollution sources
Potential Pollutant Source Activity
Potential Pollutant'Generated
Applicable to
this project
Disturbed Areas
Sediment
X
Soil stockpiles
Sediment
X
Travel to adjacent public streets
Tracked sediment
X
Contaminated soils
Sediment, chemicals
Loading and unloading chemicals
Chemicals
Outdoor storage of chemicals
Chemicals
On site equipment maintenance
Oil, grease
On site equipment fueling
Diesel, gasoline
X
Dust generating activities
Particulates, sediment
X
Use of fertilizer, pesticides, herbicides
Fertilizer, pesticides
Use of detergents, solvents, oils
Detergents, solvents, oil
X
Waste dumpsters, waste piles
Chemicals
X
Concrete washout
Concrete, sediment
X
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
5.4 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.
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.
6
The locations of the rock socks will be in the areas of concentrated flow such as the
existing curb and the proposed sidewalk culverts.
The site may 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
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 drives 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 section 5.5 for the timing of the construction phases and the sequential
installation of all BMP phasing for this site.
Refer to the end of Section 5.4 for the Erosion Control Surety calculations.
5.2 SWMP contact information
Permit holder:
Name:
Address:
Phone Number:
Email Address:
Appointed agent:
Name:
Address:
Phone Number:
Email Address:
f;
I
We are requesting a variance from the criteria that requires that 25% of the site
pavements be impervious. This site has approximately 1200 square feet of concrete
proposed on site which is entirely within Basin 1, a majority of which is in the driveways
with a small portion being the sidewalk and the trash enclosure. Of the 1200 square feet,
approximately 900 square feet can be driven on and 25% of this area would equate to 225
square feet of pervious pavement. We believe this amount of pervious pavement would
have little to no impact on the quality of the runoff from this site.
4.3 Drainage Summary
All runoff from this site and the adjacent sites will be safely conveyed via surface flow to
the detention pond. The site will generally conform to the Old Town Master Drainage
plan which this site is included in.
The City of Fort Collins will be responsible for maintenance of the existing storm
drainage facilities located within the right-of-way. The drainage facilities located outside
of the right of way (including the detention pond) will be maintained by the property
owner.
5. STORMWATER MANAGEMENT CONTROLS
5.1 Written Analysis
The soils on this site are classified by the USGS Soil Survey as Fort Collins Loam and
are classified in the hydrologic group B. The rainfall and wind erodibility is deemed to be
moderate. The Group B soils are Soils having a moderate infiltration rate when
thoroughly wet. These consist chiefly of moderately deep or deep, moderately well
drained or well drained soils that have moderately fine texture to moderately coarse
texture. These soils have a moderate rate of water transmission.
The site is surrounded by developed sites including streets 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 to capture sediments that are not fully contained by the silt fence placement.
4
4. DRAINAGE FACILITY DESIGN
4.1 General Concept
The runoff from this site will be collected in a grassed swale along the west property line
and be conveyed to the detention pond on the south portion of the site. A small amount of
runoff will be allowed to discharge directly to the existing alley on the east property line.
A small amount of flow from the property on the west is anticipated to enter the site and
will be conveyed to the detention area. The offsite flows will not be detained and will
flow over the detention pond berm.
4.2 Specific Flow Routing
A summary of the drainage patterns within each basin is provided in the following
paragraphs.
Basin 1 encompasses the majority of the proposed development including the building,
front porch, front walk and the landscaping on the north, west and south sides of the site.
A majority of the runoff flows to the grassed swale on the west property line which will
convey the flows south to the proposed detention pond. This detention pond will have a
very small release rate (0.08 cfs) which allows for a 1.6" diameter orifice on the outlet.
The water quality extended detention is incorporated into the detention volume. In the
east most portion of the pond, an LID swale is being incorporated into the detention pond
also. The pond will have 0.5' of freeboard to the building finished grade and 1.25' of
freeboard to the building finished floor. The pond will have a spillway all along the
existing sidewalk on the north side of West Laurel Street.
Basins 2 includes the proposed driveways on the east side of the site. The runoff from
this basin will flow east directly into the alley and be conveyed to the south and into
West Laurel Street or north eventually reaching West Myrtle Street. This flow path is the
historic flow path for the runoff from this site. Because the runoff from this Basin
exceeds the 2 year historic runoff from the site, the detention release allowed from Basin
I has been reduced.
3
V.
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. Where applicable, the criteria established in the
"Urban Storm Drainage Criteria Manual" (UDFCD), developed by the Denver Regional
Council of Governments, has been used.
3.2 Development Criteria Reference and Constraints
The runoff from this site has been routed to conform to the Old Town Master Drainage
plan and the existing conditions on site. The Old Town Basin is restricted to a 2 year
historic release rate with redevelopment. Because of the existing development on all four
sides to this site, the east portion of the development (the driveways) will release directly
onto the alley without detention. The runoff from the remainder of the site, including the
entire proposed building, will be directed to a swale on the west property line that
conveys the runoff to the proposed detention pond. The release rate for the detention
pond has been reduced from the 2 year historic release rate in order to partially
compensate for the free release runoff from the driveways.
The detention pond will release directly into West Laurel via a sidewalk culvert and a
curb opening.
3.3 Hydrologic Criteria
Runoff coefficients calculations were prepared for the 2 and 10-year minor and 100-year
major storm frequency utilizing the rational method. Detention is proposed on site (with
incorporated water quality volume) with a release rate below the 2 year historic runoff
rate.
3.4 Hydraulic Criteria
No subsurface drainage conveyances are proposed with this development; therefore no
hydraulic calculations were completed with this design.
2
V
4�
1. GENERAL LOCATION AND DESCRIPTION
1.1 Location
The site is located on the East '/z of the East % of Lots 12 and 13, Block 106 Harrison
Addition in Section 5, Township 6 North, Range 68 West of the Sixth Principal Meridian,
in the City of Fort Collins, Larimer County, Colorado. The address of the existing site is
218 West Laurel Street. See the location map in Appendix A.
The project is located on the north side of West Laurel Street between South Mason
Street and South Howes Street. The project is bounded on the north and west by existing
(�S on the east by Rainbow Cafe and the alley and on the south by Laurel Street
l J and CSU campus. V ut Gt 1 E-
1.2 Description of Property
The entire site consists of approximately 0.15 acres of land. The land is currently
developed with an existing house and concrete walks and drives. The site currently drains
to the alley on the east and then to the north and south. Slopes on site range from
approximately 0.5% to 1%.
This project will include the development of a six-plex residential building, driveways
and landscape area. The site will be reconfigured so that a majority of the runoff will be
directed to the west propert line ine and south into the proposed detention and water quality
2. DRAINAGE BASINS AND SUB -BASINS
2.1 Major Basin Description
The proposed development lies within the Old Town Drainage Basin.
2.2 Sub -basin Description
This site has not been included in any known previous drainage study.
TABLE OF CONTENTS
TABLEOF CONTENTS............................................................................................................... iii
GENERAL LOCATION AND DESCRIPTION
1.1 Location...................................................................................................................1
1.2 Description of Property............................................................................................I
2. DRAINAGE BASINS AND SUB -BASINS
2.1 Major Basin Description..........................................................................................1
2.2 Sub -Basin Description.............................................................................................I
3. DRAINAGE DESIGN CRITERIA
3.1 Regulations..............................................................................................................2
3.2 Development Criteria Reference and Constraints...................................................2
3.3 Hydrologic Criteria..................................................................................................2
3.4 Hydraulic Criteria....................................................................................................2
4. DRAINAGE FACILITY DESIGN
4.1 General Concept......................................................................................................3
4.2 Specific Flow Routing.............................................................................................3
4.3 Drainage Summary ..................................................................................................4
5. STORMWATER MANAGEMENT CONTROLS
5.1 Written Analysis.....................................................................................................4
5.2 SWMP Contact Information...................................................................................5
5.3 Identification and location of all potential pollution sources..................................6
5.4 Best Management Practices (BMP's) for Stormwater Pollution Prevention ........... 6
5.5 BMP Implementation..............................................................................................8
6. CONCLUSIONS
6.1 Compliance with Standards..................................................................................12
6.2 Drainage Concept..................................................................................................12
7. REFERENCES..................................................................................................................13
APPENDICES
A Vicinity Map
B Hydrologic Computations
C Detention Pond Calculations
Y
4-
North Star
design
700 Automation Drive, Unit I
Windsor, CO 80550
Phone:970-686-6939
Fax:970-686-1188
July 23, 2013
Glen Schlueter
City of Fort Collins Stormwater
700 Wood Street
Fort Collins, CO 80522-0580
RE: Final Drainage and Erosion Control Study for
218 West Laurel Street
Dear Glen,
I am pleased to submit for your review and approval, this Final Drainage and Erosion Control
Study for 2118 West Laurel Street. I certify that this report for the drainage design was prepared
in accordance with the Old Town Master Plan and 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.
ii
9
4.-
FINAL DRAINAGE AND EROSION
CONTROLSTUDY
218 WEST LAUREL STREET
Prepared for:
Dana Lockwood
Lockwood Architects
415 East Pitkin
Fort Collins, CO 80524
Prepared by:
North Star Design, Inc.
700 Automation Drive, Unit I
Windsor, Colorado 80550.
(970)686-6939
July 23, 2013
Job Number 348-01