HomeMy WebLinkAboutPOUDRE SCHOOL DISTRICT, EAST PROSPECT ROAD SERVICE FACILITY - ODP - 44-08 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTDETENTION VOLUME CALCULATIONS
Rational Volumetric (FAA) Method
Pond C 100-Year Event
LOCATION: PSD
PROJECT NO: 1099-048-00
COMPUTATIONS BY: es
DATE: 12/23/2008
Equations: Area trib. to pond =
Developed flow = Qo = CIA C (100) =
Vol. In = Vi = T C I A = T Qp Developed C A =
Vol. Out = Vo =K QPo T Release rate, QPo =
storage = S = Vi - Vo K =
Rainfall intensity from City of Fort Collins OF Curve with (3.67") rainfall
3.6
acre
0.91
3.3
acre
0.70
cfs
1.0
(from fig 2.1)
Storm
Duration, T
(min)
Rainfall
Intensity, I
(in/hr)
Qp
(cfs)
Vol. In
Vi
(ft)
Vol. Out
Vo
(ft)
Storage
S
(ft)
Storage
S
(ac-ft)
5
9.95
32.6
9779
210
9569
0.22
10
7.72
25.3
15174
420
14754
0.34
20
5.60
18.3
22015
840
21175
0.49
30
4.52
14.8
26654
1260
25394
0.58
40
3.74
12.3
29405
1680
27725
0.64
50
3.23
10.6
31744
2100
29644
0.68
60
2.86
9.4
33730
2520
31210
0.72
70
2.60
8.5
35774
2940
32834
0.75
80
2.34
7.7
36796
3360
33436
0.77
90
2.17
7.1
38388
3780
34608
0.79
100
1.99
6.5
39115
4200
34915
0.80
110
1.87
6.1
40432
4620
35812
0.82
120
1.75
5.7
41278
5040
36238
0.83
130
1.66
5.4
42418
5460
36958
0.85
140
1.57
5.1
43204
5880
37324
0.86
150
1.48
4.8
43636
6300
37336
0.86
160
1.42
4.7
44658
6720
37938
0.87
170
1.36
4.5
45445
7140
38305
0.88
180
1.29
4.2
45641
7560
38081
0.87
Required Storage Volume: 38305 ft3
0.88 acre-ft
Detention Pond D.xls,FAA-100yr
Design -Procedure Form: Extended Detention Basin (EDB) Sedlmentatlon_Faclllty_4-'
Designer: ES
Company:
Interwest Consulting Group
Date:
December 23, 2008
Project:
PSD
Location:
Basin C
1. Basin Storage Volume
A) Tributary Area's Imperviousness Ratio (i = 1,/ 100 )
B) Contributing Watershed Area (Area)
C) Water Quality Capture Volume (WQCV)
(WQCV =1.0' (0.91 " 13 - 1.19 " Iz + 0.78' 1))
D) Design Volume: Vol = (WQCV / 12)' Area' 1.2
2. Outlet Works
A) Outlet Type (Check One)
B) Depth at Outlet Above Lowest Perforation (H)
C) Recommended Maximum Outlet Area per Row, (A,)
D) Perforation Dimensions:
i) Circular Perforation Diameter or
ii) Width of 2" High Rectangular Perforations
E) Number of Columns (nc, See Table 6a-1 For Maximum)
F) Actual Design Outlet Area per Row (N)
G) Number of Rows (nr)
H) Total Outlet Area (A,J
3. Trash Rack
A) Needed Open Area: A, = 0.5' (Figure 7 Value)' A,
B) Type of Outlet Opening (Check One)
C) For 2", or Smaller, Round Opening (Ref.: Figure 6a):
I) Width of Trash Rack and Concrete Opening (W..)
from Table 6a-1
ii) Height of Trash Rack Screen (HT)
la = 70.00 %
Area = 3.600 acres
WQCV = 0watershed inches
Vol '0 0990-?Wacre-feet e
X Orifice Plate
Perforated Riser Pipe
Other.
H = 0.00 feet
Ao F7F~ l 7V-'2,i square inches
D = Pa"e�`-^-;-i250 inches
W = Wz&?V�%W inches
nc =,r1F number
�)squareinches
nr i==0�1° 'r�) number
Age = Ef:00'- square inches
' f. ,�,Ta..'
Ai t"�, , <_0 . �s,., squareinches
2" Diameter Round
High Rectangular
Other:
W.., ,.`,<0 "(; ...s inches
Hra inches
Sheet 1 of 3
' UD-BMP_v2.06 Pond D.xls, EDB
12/23/2008, 11:41 AM
DETENTION VOLUME CALCULATIONS
Rational Volumetric (FAA) Method
Pond B 100-Year Event
LOCATION: PSD
PROJECT NO: 1099-048-00
COMPUTATIONS BY: es
DATE: 12/23/2008
Equations: Area trib. to pond =
Developed flow = Qo = CIA C (100) =
Vol. In = Vi = T C I A = T Qp Developed C A =
Vol. Out = Vo =K QPo T Release rate, QPo =
storage = S = Vi - Vo K =
Rainfall intensity from City of Fort Collins OF Curve with (3.67') rainfall
51
acre
0.91
46.4
acre
10.20
cfs
1.0
(from fig 2.1)
Storm
Duration, T
(min)
Rainfall
Intensity, I
(in/hr)
Qp
(cfs)
Vol. In
Vi
(ft)
Vol. Out
Vo
(ft)
Storage
S
(ft)
Storage
S
(ac-ft)
5
9.95
461.8
138534
3060
135474
3.11
10
7.72
358.3
214971
6120
208851
4.79
20
5.60
259.9
311875
12240
299635
1 6.88
30
4.52
209.8
377592
18360
359232
8.25
40
3.74
173.6
416576
24480
392096
9.00
50
3.23
149.9
449713
30600
419113
9.62
60
2.86
132.7
477837
36720
441117
10.13
70
2.60
120.7
506797
.42840
463957
10.65
80
2.34
108.6
521277
48960
472317
10.84
90
2.17
100.7
543832
55080
488752
11.22
100
1.99
92.4
554135
61200
492935
11.32
110
1.87
86.8
572792
67320
505472
11.60
120
1.75
81.2
584766
73440
511326
11.74
130
1.66
77.0
600917
79560
521357
11.97
140
1.57
72.9
612055
85680
526375
12.08
150
1.48
68.7
618181
91800
526381W12.08160
1.42
65.9
632661
97920
534741170
1.36
63.1
643800
104040
539760180
1.29
59.9
646584
110160
536424
r
equired Storage Volume: 539760 ft3
12.39 acre-ft
Detention Pond B-C.xls,FAA-100yr
'
Desi ri Procediire Form: Extended Detention Basln EDB
9 ( )
Sedimentation Facilit � h
Y
'
Designer:
ES
Sheet 1 of 3
Company:
Interwest Consulting Group
Date:
December 23, 2008
'
Project:
PSD
Location:
Basin B
[I
[1
1. Basin Storage Volume
la = 70.00 %
A) Tributary Area's Imperviousness Ratio (i = la / 100)
i 0. 70M
B) Contributing Watershed Area (Area)
Area = 51.000 acres
C) Water Quality Capture Volume (WOCV)
WOCVOt28.')17watershed inches
(W OCV = .19 12) 111
.ol
Volume: * Area
D) Design Volume: Vol = (W OCV / 12)' Area ' 1.2
(W CV
Vol e 1sA(2�7,1] acre-feet
2. Outlet Works
A) Outlet Type (Check One)
X Orifice Plate
'
Perforated Riser Pipe
Other.
B) Depth at Outlet Above Lowest Perforation (H)
H = 0.00 feet
C) Recommended Maximum Outlet Area per Row, (Aa)
A. = square inches
D) Perforation Dimensions: _
i) Circular Perforation Diameter or
D ''d inches
ii) Width of 2" High Rectangular Perforations
W='s'AT.89inches
E) Number of Columns (nc, See Table 6a-1 For Maximum)
nc a:;=,j 1^'!?' number
F) Actual Design Outlet Area per Row (Aa)
Aa = ��=15 8 square inches
G) Number of Rows (nr)
nr = EMT 700—! 77 number
H) Total Outlet Area (Aa)
Am0 0* r, square inches
3. Trash Rack
A) Needed Open Area: A, = 0.5' (Figure 7 Value)Aa,
A, 07e�"-_- square inches
B) Type of Outlet Opening (Check One)
' t`.-Y. _ S 2' Diameter Round
'
W a-,,X1: F„T; 2" High Rectangular
Other.
C) For 2", or Smaller, Round Opening (Ref.: Figure 6a):
i) Width of Trash Rack and Concrete Opening (W..)
from Table 6a-1
Wiz ` x%t 4"?-2 inches
ii) Height of Trash Rack Screen (HTR)
HTR m= �4inches
' UD-BMP_v2.06 Pond B-C.xls, EDB 12/23/2008, 11:47 AM
DETENTION VOLUME CALCULATIONS
Rational Volumetric (FAA) Method
Pond A 100-Year Event
LOCATION: PSD
PROJECT NO: 1099-048-00
COMPUTATIONS BY: es
DATE: 12/23/2008
Equations: Area trib. to pond =
Developed flow = Qp = CIA C (100) =
Vol. In = Vi = T C I A = T Qp Developed C A =
Vol. Out = Vo =K QPo T Release rate, QPo =
storage=S=Vi -Vo K=
Rainfall intensity from City of Fort Collins IDF Curve with (3.67") rainfall
34
acre
0.63
21.4
acre
6.80
cfs
1.0
(from fig 2.1)
Storm
Duration, T
(min)
Rainfall
Intensity, I
(in/hr)
Qo
(cfs)
Vol. In
Vi
(ft)
Vol. Out
'Vo
(ft)
Storage
S
(ft)
Storage
S
(ac-ft)
5
9.95
213.1
63939
2040
61899
1.42
10
7.72
165.4
99217
4080
95137
2.18
20
5.60
120.0
143942
8160
135782
3.12
30
4.52
96.8
174273
12240
162033
3.72
40
3.74
80.1
192266
16320
175946
4.04
50
3.23
69.2
207560
20400
187160
4.30
60
2.86
61.3
220540
24480
196060
4.50
70
2.60
55.7
233906
28560
205346
4.71
80
2.34
50.1
240589
32640
207949
4.77
90
2.17
46.5
251000
36720
214280
4.92
100
1.99
42.6
255755
40800
214955
4.93
110
1.87
40.1
264366
44880
21.9486
5.04
120
1.75
37.5
269892
48960
220932
5.07
130
1.66
35.6
277346
53040
224306
5.15
140
1.57
33.6
282487
57120
225367
5.17
150
1.48
31.7
285314
61200
224114W*5.1160
1.42
30.4
291997
65280
226717170
1.36
29.1
297138
69360
227778180
1.29
27.6
298423
73440
224983
Required Storage Volume: 227778 ft3
5.23 acre-ft
Detention Pond A.xls,FAA-100yr
I
r
LL Deslg Y, _io dure Form _Extended DetenUonlBasm (EDB)_ Sedimentation Faculty _. r N
Sheet 1 of 3
Designer: ES
Company: Interwest Consulting Group
Date: December 23, 2008
Project: PSD
Location: Basin A
1. Basin Storage Volume
I, = 40.00 %
A) Tributary Area's Imperviousness Ratio (i = I,/ 100)
B) Contributing Watershed Area (Area)
Area = 34.000 acres
C) Water Quality Capture Volume (WQCV) .
WQCV=ERTTA8 F1watershed inches
(WQCV =1.0' (0.91h- 1.19' IZ+0.78' M
D) Design Volume: Vol 1.2
Vol =,ate 0:6115,;. acre-feet �-
= (WQCV / 12)' Area'
2. Outlet Works
A) Outlet Type (Check One)
X Orifice Plate
Perforated Riser Pipe
Other:
B) Depth at Outlet Above Lowest Perforation (H)
H = 0.00 feet
C) Recommended Maximum Outlet Area per Row, (AJ
A. = 7,6.9 51' square inches
D) Perforation Dimensions:
i) Circular Perforation Diameter or
D ,u inches
it) Width of 2" High Rectangular Perforations
Winches
E) Number of Columns (nc, See Table 6a-1 For Maximum)
nc number
F Actual Design Outlet Area per Row
r,m6:9`"w=A s uare inches
G) Number of Rows (nr)
nr =+i0 �t` number
H) Total Outlet Area (k,)
Fyi = ? >t:(0:0�?;:°,; ';- square inches
3. Trash Rack
A) Needed Open Area: At = 0.5' (Figure 7 Value)' A,,
Ar t .:. 0` s square inches
B) Type of Outlet Opening (Check One)
< 2 Diameter Round
>X^.; 2" High Rectangular
Other:
C) For 2", or Smaller, Round Opening (Ref.: Figure 6a):
i) Width of Trash Rack and Concrete Opening (W..)
from Table 6a-1
Wmm «ai� `;`y; inches
ii) Height of Trash Rack Screen (Hm)
HTa =2v=dinches
' UD-BMP v2.06 Pond A.xls, EDB
12/23/2008, 11:40 AM
Interwest Consulting Group
1218 West Ash, Suite C
Windsor, Colorado
RATIONAL METHOD PEAK RUNOFF
(100-YEAR)
LOCATION: PSD
PROJECT NO: 1099-048-00
COMPUTATIONS BY: ES
DATE: 12/23/2008
100-yr storm, Cf = 1.25
DIRECT RUNOFF
CARRY OVER
TOTAL
REMARKS
Des.
Point
Area
Design.
A
(ac)
C Cf
tc
(min)
i
(new)
(in/hr)
Q (100)
(cfs)
from
Design
Point
Q (100)
(cfs)
Q(100)tot
(cfs)
A
A
34.00
0.63
17.4
6.05
128.5
128.5
B
B
51.00
0.91
17.6
6.00
277.3
277.3
C
C
3.60
0.91
7.7
8.55
27.9
27.9
Q=CiA
Q = peak discharge (cfs)
C = runoff coefficient
I = rainfall intensity (in/hr) from IDF curve
A = drainage area (acres)
NOTE: Intensity based on Figure 3-1, 1999 (Regional Analysis)
Flow.xls Q100
Interwest Consulting Group
1218 West Ash, Suite C
Windsor, Colorado
RATIONAL METHOD PEAK RUNOFF
(10-YEAR)
LOCATION: PSD
PROJECT NO: 1099-048-00
COMPUTATIONS BY: ES
DATE: 12/23/2008
10-yr storm, Cf = 1.00
DIRECT RUNOFF
CARRY OVER
TOTAL
REMARKS
Design .
Point
Tributary
Sub -basin
A
(ac)
C Cf
tc
(min)
i
(new)
(in/hr)
Q (10)
(cfs)
from
Design
Point
Q (10)
(Cfs)
Q(10)tot
(cfs)
A
A
34.00
0.50
17.4
2.96
50.3
50.3
B
B
51.00
0.73
17.6
2.94
108.6
108.6
C
C
3.60
0.73
11.8
3.54
9.31
9.3
Q=CfCiA
Q = peak discharge (cfs)
C = runoff coefficient
Cf = frequency adjustment factor
I = rainfall intensity (in/hr) from IDF curve
A = drainage area (acres)
NOTE: Intensity based on Figure 3-1, 1999 (Regional Analysis)
Flow.xls Q10
Interwest Consulting Group
1218 West Ash, Suite C
Windsor, Colorado
STANDARD FORM SF-2
TIME OF CONCENTRATION -100 YR
LOCATION: PSD
PROJECT NO: 1099-048-00
COMPUTATIONS BY: ES
DATE: 12/23/2008
100-yr storm CIF = 1.25
SUB -BASIN
DATA
INITIAL /OVERLAND
TIME (t0
TRAVEL TIME / GUTTER OR CHANNEL FLOW
(tt)
tc CHECK
(URBANIZED BASIN)
FINAL
tc
REMARKS
DESIGN
POINT
SUBBASIN(s)
(1)
Area
(ac)
(2)
C
(3)
C'Cf
Length
(ft)
(4)
Slope
(%) -
(5)
ti
(min)
(6)
Length
(ft)
(7)
Slope
(%)
(8)
n
Manning
rough.
Val.
(Ills)
(9)
ft
(min)
(10)
tc =
5+it
(11)
Total
(ft)
(12)
tc=(p180)+10
(min)
(13)
(min)
(14)
A
A
34.00
0.50
0.63
300
0.5
18.7
1025
0.50
0.013
1.7
9.77
28.4
1325
17.4
17.4
B
B
51.00
0.73
0.91
300
0.5
7.6
1075
0.50
0.013
1.7
10.25
17.9
1375
17.6
17.6
D
C
3.60
0.73
0.91
100
0.5
4.4
350
0.50
0.013
1.7
3.34
7.7
450
12.5
7.7
EQUATIONS:
tc=ti+tt
ti = [1.87 (1.1 - CCt) L05 S It3
it = 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 min. due to limits of IDF curves
Flow.xls TOC-100
Internest Consulting Group
1218 West Ash, Suite C
Windsor, Colorado
STANDARD FORM SF-2
TIME OF CONCENTRATION -10 YEAR
LOCATION: PSD
PROJECT NO: 1099-048-00
COMPUTATIONS BY: ES
DATE: 12/23/2008
10-yr storm Cf = 1.00
SUB -BASIN
DATA
INITIAL /OVERLAND
TIME (ti)
TRAVEL TIME / GUTTER OR CHANNEL FLOW
(tt)
tc CHECK
(URBANIZED BASIN)
FINAL
tc
REMARKS
DESIGN
POINT
SUBBASIN(s)
(1)
Area
(ac)
(2)
C
(3)
Length
(11)
(4)
Slope
(%)
(5)
8
(min)
(6)
Length
(R)
(7)
Slope
(%)
(8)
n
Manning
rough.
Vel.
(f/s)
(9)
tt
(min)
(10)
tc =
tl+tt
(11)
Total L
00
(12)
tc=(I/180)+10
(min)
(13)
(min)
(14)
A
A
34.00
0.50
300
0.5
23.6
1025
0.5
0.013
1.7
9.8
33.3
1325
17.4
17.4
B
B
51.00
0.73
300
0.5
14.7
1075
0.5
0.035
0.6
27.6
42.3
1375
17.6
17.6
C
C
3.601
0.73
100
0.5
8.5
350
0.5
0.013
1.7
3.3
11.8
450
12.51
11.8
EQUATIONS:
tc; =ti+tt
ti=[1.87(1.1-CCI)L05]/St1'
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 + It and urbanized basin check
min. tc = 5 min. due to limits of IDF curves
Flow.xls TOC-10
Inlerwesl Consulting Group
1218 West Ash, Suite C
Windsor, Colorado RUNOFF COEFFICIENTS & % IMPERVIOUS
LOCATION: PSD
PROJECT NO: 1099-048-00
COMPUTATIONS BY: ES
DATE: 12/23/2008
Recommended Runoff Coefficients from Table 3-3 of City of Fort Collins Design Criteria
Recommended % Impervious from Urban Storm Drainage Criteria Manual
Streets, parking lots (asphalt)
Concrete
Roofs
Gravel
Lawns (flat <2%, heavy soil)
Runoff
coefficient
C
%
Impervious
0.95
100
0.95
96
0.95
90
0.50
40
0.20
1 0
SUBBASIN
DESIGNATION
TOTAL
AREA
(ac.)
TOTAL
AREA
(sq.ft)
HARD SURFACE
AREA
(sq.ft)
CONCRETE
AREA
(sq.ft)
ROOF
AREA
(sq.ft)
GRAVEL
AREA
(sq.it)
LANDSCAPE
AREA
(sq.ft)
RUNOFF
COEFF.
(C)
%
Impervious
REMARKS
A
34
1,481,040
592,416
0
0
0
888,624
0.50
40
B
51
2,221,560
1.555,092
0
0
0
666,468
0.73
70
C
3.60
156,816
109,771
0
0
0
47,045
0.73
70
Total
88.60
3,859,416
2,257,279
0
0
0
1,602,137
1 0.64
58
Eauations
- Calculated C coefficients & % Impervious are area weighted
C=E(Ci Ai) /At
Ci = runoff coefficient for specific area, Ai
At = 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.>ds Cval
1
I
1
t
1]
1
I
.NOTES:
1. APPROXIMATE ACCESS. WATER AND SEWER CONNECTIONPOINTSARE SHOWN ON THIS PLAN. THE — — — _ — — — — — — — — — — _ —
ROU-nNGTHRWGti HESITEWILLBEDE RMINMD SPECIFICPROJECTSAREBRMGW FORWARD. ALL — — — , m�
ACCESS WILL BE THROUGH MWATE DRIVES OR"LOCAV CITY STREETS. UTILITY ROUTES WILL BE IN THESE -- _ _ IS M To M—K/rCH�L WAY—'/ — M
TRANSPORT'ATIONCORRIOORSORINUi1L EASEMENTSTHATMEACCESSIBLEBYTHEUPIfTY _ _ + w
COMPANIES. --- _ y
2. ASTHESITEDEVELOPS.PROSPECTROADANDLCRS WILL ULTMATELYBEWIOENEDTO4 ANEARTERIAL
STREETS. AS PROSPECT IS WIDENED, THE DITCH WILL BE RELOCATED APPROXIMATELY W NORTH OF US !I I I I I I I y
PRESENTLOCATION. THEPH INGOFTHESEIMPROVEMENTSWI MOETERMINMD SPECIFIC I MAI001®�!]I I I I I I I LOTY
PROJECTS ARE BROUGHT FORWARD. l.E yLL uwi�RLY
3. ALL STORM DETENTION PONDS ARE PRESENTLY DESIGNED TO DISCHARGE TO THE CACHE LA FOUDRE \ I I Al1E
INLET DITCH AT 2-YEAR HISTORIC RATES THE ULTIMATE RATE WILL BE DETERMINED WITH THE DUCH I I I I I I
COMPANY). THE DUCH COMPANY HAS STATED THAT THEY WILL ACCEPT STORMWATER TO THE DUCH. MIS
LINELYTHAT"INTERIM" DETENTION MEASURES MAY BE BUILT IN THE INITIAL PHASES OF DEVELOPMENT. \ rI ICI I III I IiI I el
4. THERE ARE NO FLOODPLAINS ON THIS SITE. THERE IS NO EROSION BUFFER LIMIT ON THIS SITE.
S. NONE OF THE EXISTING AR G STRUCTURES E PROPOSED TO REMAIN AFTER THE DEVELOPMENT OF THIS
Ste' KrTCHE" —DIVISION
7bTCHELL SRrBO/Y/SrON
CWSuBrmu 1\
CWSUBrAUBT I
l\
d
5[yER rLL u/YA1D. I
OosA:T m A
I
III OR STE Atmis I i
II
II
III LOTS
I I
LOTS
LOT7
LOTS
Lor5
III
LOT4
LOT3
I I
11
I III
I
I
I
J
I\
�I m' umry Eair]!I/T
`
�
aTOERRY FESB
III
�
I
\ xlBvluY AVO
CWsusrT7EAvr
I
/
�Fwmnrr
I
\ �rwmnir
RJID T
MF1Nae( rLL B
4
/
\
m' uB/IY AYl GP4AR2lAY.f), i
�
I /y \
E LIXX STME1s
I_
`j
A1F
JI
— — —
/ A0.FR
\
—
mr
�/
\
IS
✓�
NE,.IfM w . OTHat
LOOPW
amADOUS
1\
\
II
�aa\ l
-
<SBI
,
NETAGAN A. 011401
LAGL Sl1EEl6 M
\ \ \ SIDES Tu aNNrsr \ \ _
\ \ \ E � SAN A ; ,SITER
\ _
ENSIN9 YAN�CT 1 / / \ `D •� m EnSiNa NIwI T fi r\
\\ AND
ZY QMr\ t Nsnm THMXIOI 9TE ' —, \ NMTm TNPIXIOI
\ e• wtER I \ ' \
\ \ \ pF.vrr rnMl�c �
PIE ISRft�TR) AvnRar
L sE LOr 5A1I�1R I \
NOR
TN As rnawEc
— \ a � � \ DETENnON
aiNOATIRW _ AREA A
S).S'
ON
AREA B 1. _ Tat aM — — —
i
\y \ s s S s , s s ��� Ir s s'w3r Ba6P S4rawrs s s DETENTION
7010XE2 6ABNEST I KO WA �PANOO --06 BEFE/ I I , i '
C217(
Lorl
TINIAN D r LOSTA]Es ^3
HOA�81FoK
HwcNOEA®MRO %RmI EoHaN3O 0.3EBTA77B ZOLO2 aS I AP
Lor3l
DRAINAGE SUMMARY TABLE
BASIN IT
DETENTION
AREA
AREA
(ACRES)
DEV.
C (10)
I
WV.
C (100)
I DU.
0 (10)
(CFS)
I OEV.
0 000)
(CFS)
I RELEASE
RATE
(CFS)
I WO
VOLUME
(AC -FT)
DETENTION
VOLUME
(AC -FT)
A
34
0.50
0.63
1 50
1 129
1 6.8
I0.6
5.2
B
51
1 0.75
1 0.91
1 109
1 277
1 10.2
11.4
12.4
C
3.6
1 0.75
1 0.91
1 9
1 28
1 0.7
1 0.1
1 0.9
HOAEE37£AO ESTAMS
LOT 79 i LOT)
ODP OVERALL UTILITY AND DRAINAGE PLAN
120 60 O 120 240
BDA`E -120' POUDRE SCHOOL DISTRICT WAREHOUSE
E. PROSPECT RD. AND COUNTY ROAD 5
FORT CC3LLlIVS, COLORA�O
Rl! W.M SURc BY.A DESIGN, INC. • I.OAK .I NONE 4w R. COLLNUS. CO 111 • TL I9MI 223.7571
N4K v.. SRUS
R. RI VR
fupGoI A1.Vf p x IlR�eeT CONSULTING GROUP S H E E T 3 of 3
DECEMBER 24, 2008
r-
c�
SITE
N
Cn
i
PROSPECT
FFIR-
VICINITY MAP
N.T.S.
l
I
I
I
I
l
I
I
I
I
1.
11
I
LIU MIMM
City of Fort Collins OOP Drainage Report for Page 5
' Poudre School District Warehouse December 2008
' 4.0
[1
CONCLUSIONS
4.1 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 and Construction Standards" and the "Urban
Drainage Storm Drainage Criteria Manual".
4.2 Drainage Concept
' The proposed drainage concepts presented in this report and on the Overall Utility and
Drainage Plan adequately provide for an overall conveyance, detention and stormwater
' quality treatment of proposed impervious areas. Final drainage reports for this development
will provide further design and information to ensure that this overall development plan will
' be followed and that flows will be conveyed safely. Final drainage reports will address
erosion control and best management practices.
' 5.0 REFERENCES
1
1. "Storm Drainage Design Criteria and Construction Standards", City of Fort Collins,
Colorado, May 1984.
2. Urban Storm Drainage Criteria Manual, Volume 1, Urban Drainage and Flood
Control District, Denver, Colorado, June, 2001.
City of Fort Collins ODP Drainage Report for Page 4
Poudre School District Warehouse December 2008
I
1
1
developed area and increased flows will be detained in proposed detention Pond B.
These flows will also be released into the Ditch. Pond B will include water quality
capture volume.
Sub -basin C: This sub -basin consists of 3.6 acres, is located in the southwest corner
of the site and is triangular in shape. No use is firm on this parcel. The Ditch is
located to the northeast and Prospect Road is located to the south of this basin. CW
Subtrust property is located to the west. This basin was analyzed assuming 70%
impervious developed area and increased flows will be detained in proposed
detention Pond C. These flows will be released into the Ditch. Pond C will also
include water quality capture volume.
Please refer to the Appendix for the hydrologic calculations for these basins.
3.0 DRAINAGE FACILITY DESIGN
3.1 General Concept
The majority of the proposed development will be routed via sheet and gutter flow to the
proposed water quality and detention ponds. The ponds will release the detained 100-yr
flows into the Ditch.
' 3.2 Detention and Water Quality
The detention ponds have been preliminarily sized using the U.S. Federal Aviation
' Administration Equation (FAA Method). The ponds are required to store the 100-yr
developed flows and presently assumed to release at the 2-yr existing rate.
The Urban Drainage Storm Drainage Criteria Manual was used to determine the water
' quality capture volume. A 40-hour brim -full volume drain time for extended detention basin
was used.
'
The ponds will be refined during final designs. Please refer to the Appendix for the FAA
Method and WQCV calculations.
City of Fort Collins CDP Drainage Report for Page 3
Poudre School District warehouse December 2008
' 2.0
1
1
1
1
DRAINAGE BASINS AND SUB -BASINS
2.1 Major Basin Description
The site does not lie within a City of Fort Collins master drainage basin. The majority of the
site drains via overland flow to the Ditch were it is then conveyed east and discharges to the
Timnath Reservoir. The site is within Timnath's Master Drainage Plan. No specific
improvements are indentified for this site.
2.2 Developed Basin Description
The proposed development will increase the amount of runoff that currently exists on the site
because of an increase in impervious area due to development. Each developed basin is
currently planned to detain the 100-yr developed conditions to the 2-yr existing release rate.
For the purposes of this report, the 2-yr existing release rate was assumed to be 0.2 cfs/acre.
Based on conversations with the Ditch Company, it is acceptable to release detained flows
directly into the Ditch. Off -site detained flows from Kitchell Subdivision will pass through
the site as they do today.
For the purposes of the ODP, the site has been broken into three developed sub -basins: A, B
and C. All developed sub -basins are delineated on the ODP Overall Utility and Drainage
Plan included in the Appendix of this report. As the site develops, patterns and pond
locations may be changed. The ODP plan will be used as a guide for future development.
Sub -basin A: This sub -basin is located west of County Road 5 and is bounded by
the Ditch to the south and Kitchell Estates to the north. This site is presently
assumed to be a school site. It consists of 34 acres and was analyzed assuming 40%
impervious developed area. Increased flows will be detained in proposed detention
Pond A and will be released into the Ditch. Pond A will also include water quality
capture volume.
Sub -basin B: This sub -basin consists of 51 acres and contains the majority of the
site. This portion of the site is assumed to be a transportation facilities use. It is
bounded to the north by Kitchell Estates, to the east by sub -basin A and to the west
by CW Subtrust property (a future industrial development). The Ditch is located to
the south of this sub -basin. The basin was analyzed assuming 70% impervious
City of Fort Collins CDP Drainage Report for Page 2
Poudre School District Warehouse December 2008
' 1.0 GENERAL LOCATION AND DESCRIPTION
' 1.1 Location
The proposed site is a tract of land located in Section 15, Township 7 North, Range 68 West
of the Sixth Principal Meridian, City of Fort Collins, Larimer County, Colorado. In
particular, it is located on the north side of East Prospect Road between I-25 and County
' Road 5. The proposed site is approximately 98.5 acres. Please refer to the Appendix for the
vicinity map.
' 1.2 Description of the Property
' The proposed site is a rectangular shaped parcel that is currently covered by an irrigated farm
field and slopes south at an average slope of 0.5%. An existing irrigation ditch, Cache La
' Poudre Reservoir Inlet (Ditch), runs along the south of the site. The proposed improvements
to this site will generally consist of uses allowed in the UE, Urban Estate and I, Industrial
' Zoning Districts including but not limited to public facilities and schools. The property is
currently owned by the Poudre School District and their intent is to share a warehouse and
facility management project with Larimer County. There could be a future school on the
' easterly 34 acres of the property. Please refer to the Appendix for the Overall Utility and
Drainage Plan.
' The site is not located within a Federal Emergency Management Agency (FEMA) designated
' floodplain.
City of Fort Collins ODP Drainage Report for Page 1
' Poudre School District Warehouse December 2008
[1
1
TABLE OF CONTENTS
1
1.0 GENERAL LOCATION AND DESCRIPTION................................................................ 1
1
1.1 Location ....................... ...................................................................................................1
1.2 Description of the Property ............................................................................................. 1
1
2.0 DRAINAGE BASINS AND SUB-BASINS....................................................................... 2
2.1 Major Basin Description................................................................................................. 2
2.2 Developed Basin Description.......................................................................................... 2
1
3.0 DRAINAGE FACILITY DESIGN..................................................................................... 3
3.1 General Concept.............................................................................................................. 3
'
3.2 Detention and Water Quality .......................................................................................... 3
4.0 CONCLUSIONS...........:...............................................................................:.....................4
1
4.1 Compliance with Standards............................................................................................ 4
4.2 Drainage Concept............................................................................................................ 4
5.0 REFERENCES.................................................................................................................... 4
1
1
APPENDIX
VICINITY MAP
1
OVERALL UTILITY AND DRAINAGE PLAN
HYDROLOGIC CALCULATIONS
1
WQCV AND DETENTION VOLUME CALCULATIONS
1
1
1
1
1
1
INTE RWEST C O N S U L T I N G G R.O U P
December 23, 2008
Glen Schlueter .
City of Fort Collins Stormwater
700 Wood Street
Fort Collins, CO 80522-0580
RE: Overall Development Plan Drainage Report for Poudre School District Warehouse
Dear Glen,
I am pleased to submit for your review and approval, this Overall Development Plan (ODP)
Drainage Report for the Poudre School District Warehouse. This report is a general analysis of the
Poudre School District Warehouse site and gives a general drainage design for the entire area. It is to
be used as a guide for development of this area. 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,
p oho :R�Q�r
Michael Oberlander, P.E., L.S.I. A
1218 WEST ASH, SUITE C WINDSOR, COLORADO 80550
TEL. 970.674.3300 • FAX. 970.674.3303
CITY OF FORT COLLINS
OVERALL DEVELOPMENT PLAN
DRAINAGE REPORT FOR
POUDRE SCHOOL DISTRICT
WAREHOUSE
PREPARED BY:
INTERWEST C❑NSULTING GROUP
1 21 B WEST ASH, SUITE C
WINDSOR, COLORADO 80550
PHONE: 970.674.330❑
FAX: 970.674.3303
DECEMBER 23, 2008
INTERWEST = CONSULTING GROUP