HomeMy WebLinkAboutNORTHBROOK PATIO HOMES @ FAIRBROOKE PUD - PRELIMINARY - 7-94 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTSTORM DRHIN::GE SYSTEM PRELIMINARY DESIGN DATA
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Street Capacity for 172 Street
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�^ yi^a� G1o�c'r/ �-.1.r,c u , r: •Icy l.� i ..
FAIR BROOKE S. 1. D.
LOCATED IN SECTION 21. TOWNSHIP T NORTH, RANGE
69 WEST OF THE GTK PM, To Tw[ on or rowT coLan,
coumn Or L1w1Y�Cm, CTATC Or COLOIAOO
wN�
4
N-
8
DRAINAGE MAP
4
BASIN F-2
BASIN F-S
i
4.85 AC,
15.28 AC..
:.
1
'
BAUDER ELEH. SCHOOL
TRACT
-BASIN F-Ga
_
I
HE
4A3 AG.
BASIN F-3a
BASIN F-I"^ 2.96AC.
11.78 AC
b
_
1
BASIN F-9
V
j �t
BASIN F-7a \
7.26 AC.Tom
/
A
0.47 AL
@TRACT
r
TRACT
p
45
BASIN F-3b
/
BASIN F-7b
` `
BA51N F-(oc
I
L25 AC.
'�
6.21 AG
BASIN F-4�___--
. 2.5G AC. �-/ '��— BASIN F-ld
TRACT C BASIN F-7c / 3.08 AC. \
TRACT I
BASIN F-B ,
13.46 AC.
-._ - FAIRBROOKE S.I. D.
N
" DRAINAGE MAP "
•wru■enoo¢ si.o. : in r•C>•vr
units per acre. Other tracts are proposed for apartments on which
the density will vary from 0 to 12 units per acre. The remaining
tracts will be rased for a day care center$ a church and a detention
pond.
HYDROLOGIC ANALYSIS
The Rational Method has been utili.:_ed to generate stormwater runoff
flows for the 2- and 100-year dvvelopr d return period storms for the
various tracts in Fairbrooke. Thin Drainage Map defines the basin
boundaries and the design points, ,:ind Table 1 summarizes the results
of the hydrologic analysi of tiu_se sub -basins. In addition,
offsite stormwater from the Drown Farm development contributing
runoff the the open channel along the south side of Fairbroolte west
of Hampshire Road and the runoff in Hampshire Road have been
estimated.
It should be noted at. this point -that the calculated flows in
Fairbro(-)ke are, approximate due to the fact -that the interior
drainage patterns (street layout and building locations) within the
individual tracts have not been established. The calculated runoff
quanti.ti.ess, however, aSst.une fully developed conditions rasing a
runorf ficient of (:).50 concurrent with the existing RL & RP
zoning. The pat.t.erns of flow and the basin.configurations as
containt=_-dherein should be maintained_ when actual development_occ_urs
Jo ass .not adversely affect the improvements proposed with the!
Fairbrooke Special Improvement pistrict.
DETENTION
The detention pond for Fairbrooke Special Improvement District will
be designed by the City of Fort Collins Storrs Drainage. Division, tend
is not included as part of this report.
FINAL STORM DRAINAGE REPORT
FAIRBROOKE S.I.D.
FORT COLLINS, COLORADO
GENERAL
This report, in combination with the Drainage Map accompanying this
report, the Fairbrooke S.I.D. Design Flans, the Brown Farm
Preliminary Master Drainage Flan (Sheet 18 of 18) prepared by
R. V* Lord and—aj.-q.soc.iates,,,__,L.n.c_,_, 6ygust,._1971, and Volume II
"' re� urinary. Design Fceport--Diversion of Storm Water Runoff ThroughIrri-gati_on-Canals"from' Mulberry Street to Spring CreeE:--Fort
Collins, Colorado", prepared by Resource Consultants, Inc., July,
19B0, is intended to describe the procedures and results of a .
drainage study.of stormwater runoff generated by this project and
adjacent properties. The proposed development along with the
required drainage improvements are analyzed in accordance with the
guidelines established by the City of Fort Collins' Storm Drainage
Criteria Manual.
INTRODUCTION
The purpose of this !Study is to determine the quantity of stormwater
runoff generated from the development of the various tracts within
the Fairbrooke site, along with adjacent upstream property, the
manner by which this runoff. will be accommodated by the Fairbrooke
project, and how this relates to previous studies as outlined.above.
SITE DESC:F:1 F'1 101N1
The site is loceited in the not.ht.!r 1/22 of Section 21, Township 7
North. Range 69 West, oV the 6th F': incipal• Meridian, Stat(i! of
Colorado, County of l_ari.mer, Ci.t.y of Fort Collins. The Fairbrooke
project eonsists.of 99.42 acre!e> metre or less and in bounded by
Prospect Street on the north, Tivit Hill Poad on the east, The grown
Farm development and Aspen Heights P.U.D. on the south, and the
Foothillsv West development to the. west.
The site is presently undeveloped and is used primarily for
agricultural purposes. The. existing -drainage pattern is to the
north E:,nd east at slope=_ ranging from 0.8 to 1.0 percent. The
P1easa:it Val Ie.y and Lake Canal flows through the property from north
to south.
PROPOSED LAND USE
The project is planned to consist of tracts on which varying
proposed land usages will occur. Several of the tracts will have
townhomes and patio homes with densities ranging from 6 to 7 1/2
J •
FINAL DRAINAGE REPORT
ISO ��...•� � � 1 .. P , .,
FOR
FAf;bf:00h:: ; S..1 . 1).
�!n �� ;din 1, I� � :•i, .,.
CITY OF FLIRT COLLINS
COUP•1'TY OF LARIMER
STATE OF COLORADO
November,.198
Prepared by:
Persons €< Associates Consulting Engineers
432 Link Laney Plaza
Fort Collins, Colorado 80524
Project Number 83.•lEl WOR
SrK5-ST 5L-D9L-
clu'lFf3 1' �-',fi-17
DATA CONSTANTS
Type / Location .
NORTHBR OOK DR. / RES.
FLOWLINE
WIDTH (ft)
CROSS
SLOPE (ft)
STREET
SLOPE (ft)
YARD
SLOPE (ft)
WALK DEPTH @
WIDTH (ft) CURB F.L.
CURB
HEIGHT (ft)
CROWN
ELEV.
REDUCT'N
FACTOR
36.001
0.02001
0.0100
0.020
5.00 0.86
. 0.50
100.00
0.80
CALCULATED CONSTANTS
WETTED
PERIMETER
WEIGHT'D
MANNINGS
TOP
WIDTH
AREA
OF FLOW
97.017
0.0258
96.00
41.98
CALCULATED HYDRAULICS
THEO. I ALLOW
CAPACITY cfs CAPACITY
WATER
ELEV.
VELOCITY
s
138.371
110.701
100.50
1.14
FEBRUARY1994
Manning's Equation for the Theoretical Capacity
of Non - Symetrical Triangular Section
0.250 =Side Slope 1 1 0.060 = Manning's (n)
0.250 = Side Slope iiiiiiiiiiiiiiiiiiiillllllllllllllllll7 This Section
1
0.039
= Channel Slope
Flow Depth
Intercept
Area 1
Intercept
(ft/ft)
(ft from CL)
(sq/ft)
(ft from CL)
0.80
3.20
1.28
3.20
90.
360
1 62
3.60
1.00
4.00
2.00
4.00
1.20
4.80
2.881
4.80
52
1.40
5.601
3.92
5.60
1 50&
�61 00
� -
.4.50
...
.60
-6 4-01
5.12
TTO
1 a70
L6'80
S.78
>: 6:80,
0.200 =Side Slope 1 0.060 = Manning's (n)
0.200 =Side Slope 2 This Section
OUTFALL PAN 0.01 = Channel Slope
2
Total Discharge
Intercept
Areal
Intercept
t
This Section (cfs)
(ft from CL)
(sq/ft)
(ft from CO
1.28
6.66
4.00
1.60
4.00
.6 2 .
. ...... ..........
0 3
4 50
2.00
12.08
5.00
2.50
5.00
57:
3 M
.50
2.88
19.64
..... ..
---
-TOO
3.60
ro�o
3.38..r..:�;:;...-:::.
... ............. . ... .
:r,,.,...
:;��24.311�
6.50::
4.22:
. ......... 6.50
3.92
-Z9-63
7.00
4.90
7.00
35.6y.
.-:7. 5G
5 63
7 50.
5.12
n
8.00
6.40
8.00
5.
49.72
8.501
-7.23
... 8.501-
)TE: - The manning's (n) Value is between the typical
- All 12'easements are 12'for draiange pans
1Z4. 1 C7(-S
I. -5-�5 -5Z -I eks
TYPICAL 2-in deep
S. BACKLOT PAN
2
Total Discharge
This Section (cfs)
1.60
4.1
2. 50
7.70
4.901 18.89
S63. ....... .. . ...........22.7,0
6.401 26.96
,75 - 8, 1 Cis
i1?
DRAINAGE CRITEF MANUAL
50
30
t-- 2 0
Z
w
U
a
°' 10
z
III
a
0 5
w
� 3
0
U 2
w
F—
a
kz
1
RUNOFF
All
PUFAI
.2 .3 .5 1 2 3 5 10 20
VELOCITY IN FEET PER SECOND
FIGURE 3-2.. ESTIMATE OF AVERAGE FLOW VELOCITY FOR
I USE WITH. THE RATIONAL FORMULA.
*MOST FREQUENTLY OCCURRING "UNDEVELOPED"
LAND SURFACES IN THE DENVER REGION.
REFERENCE: "Urban Hydrology For Small Watersheds" Technical
Release No. 55, USDA, SCS Jan. 1975.
5 -1-84
URBAN DRAINAGE & FLOOD CONTROL DISTRICT
STEWART&ASSOdATES 103 . MEL9331DRFUM, 48 J COLLINS, CO 80521
PH.Consulting Engineers and Surveyors 1 I
By: Date: 2' -�1 Client: �l'_f� A iZ� l�D C�-t• Sheet No. --L of
Project: 0,2�l� 32oa` �p�� 1 \aC
Subject: P�A'�1 IJfI 1�
i F3►iS� ti
� P\I2.�=1�
� Ou��c..ru� (C�-i
V e.�cc��
6
2,-56
go'(2-2)/ 4 1o(1T,�
i
2.03
ISS'(2%)/c}oo ( I'7n,
8�
(2%s(t���
/z.o
I
� I i
i �
I
DEVELOPED RUNOFF COMPUTATIONS FROM RATIONAL METHOD
Q =CxCfx[xA
SUBBASIN T.O.C. 4100 r ......
D. Pnt.
Slope
010
C Cf
Length
feet
Overt Tc
min.)
Vel.Chan
(ft/sec.)
Tc Chan.
(min.)
Tc Total
(min.)
COMMENTS
2.001
0.75
135.00
6.0
Tc (100)
1.001
400.00
2.001
3.3
LNGST. OVERL.+CHANNEL
-0.60 = Runoff C
1.00 = Cf 2,10
1.25 =Cf 100
1
D. Pnt.
Area
(acres)
C Cf
I (2yr.)
On/hr)
1 (1 Oyr.)
(in/hr)
I (100yr.)
in/hr
Basin 0
(cfs)
Comb. Q
WS)
COMMENTS
D
2.031-
0.601
2.601
3.17
3.2
2 yr. runoff
0.601
4.50
5.48
10 yr. runoff
0.75
7.00
10.66
10.7]
100 yr. runoff
0.60 = C 1.00 =Cf 2,10 1.25 =Cf(100)
SUBBASIN, .. . ... ....
D. Pnt.
Slope
N
C Cf
Length
(feet)
Overt Tc
(min.)
Vel.Chan
(ft/sec.)
Tc Chan.
(min.)
Tc Total
(min.)
COMMENTS
2.001
0.75
50.00
3.7
Tc (100)
1.001
530.00
2.90
3.0
is Z.7.
LNGST. OVERL.+CHANNEL
0.60 = Runoff C 1.00 = Cf 2,10 1.25 =Cf 100
D. Pnt.
Area
(acres)
C *Cf
I (2yr.)
(in/hr)
I (10yr.)
(in/hr
I (100yr.)
in/hr
Basin 0
cfs
Comb. Q
(cfs)
COMMENTS
0.881
0.60
2.85
1.50
2 yr. runoff
0.60
5.00
2.64
2;6
1 10 yr. runoff
1 0.75
7.00
M44.62
4.6
1 100 yr. runoff
�0.60 = C 1.00 =Cf 2,10 1.25 =Cf(100)
DEVELOPED RUNOFF COMPUTATIONS FROM RATIONAL METHOD
Q =CxCfx I xA
SUBBASIN::.T O.C,- 100
D. Pnt..
Slope
C Cf
Len gth
I Overt Tc
Vel.Chan
Tc Chan.
Tc Total
COMMENTS
el
I (min.)
(ft/sec.)
(min.)
(min.)
X, A 7
2.001
0.75
50.001
- 3.7
Tc (100)
1.001
340.001-
2.00
2.831:....
.. ....
-,, ......-x 6.51
LNGST. OVERL.+CHANNEL
,0.60 = Runoff C
1.00 = Cf 2,10
1.25 =Cf 100
D. Pnt.
Area
(acres)
C *Cf
I (2yr.)
(in/hr)
I (10yr.)
(in/hr)
I (100yr.)
(in/hr)
Basin Q
cfs
Comb. Q
(cfs)
COMMENTS
-0.71
0.60
2.901
1
1.24
F77777T41
2 yr. runoff
0.60
5.001
2.13
21
10 r. runoff
0.751
1
1 7.00
3.73
100 yr. runoff
0.60 = C 1.00 =Cf 2,10 1.25 =Cf(100)
SUBBASIN T.O.C:: (1 00yr)-,
D. Pnt.
Slope
C • Cf
Length
I OvierLTc
�Vel.Chan
Tc Chan.
Tc Total
COMMENTS
(0/0
(feet)
I (min.)
I (ft/sec.)
(min.)
(min.)
R
2.001
0.751
80.001-
4.61
Tc (100)
1.001
1 490.001-
1 2.00
4.1
-,87:
LNGST. OVERL.+CHANNEL
0.60 = Runoff C 1.00 = Cf 2,10 1.25 =Cf 100
D. Pnt.
Area
(acres)
C *Cf
I (2yr.)
On/hr)
I (10yr.)
(in/hr)
I (100yr.)
Basin Q
s
Comb. Q
cfs)
COMMENTS
B
2.56
0.601
2.601
3.99F77770
2 yr. runoff
0.60
4.50
6.91
10 yr. runoff
0.751
17.00
13.44
134
100 yr. runoff
0.60 = C 1.00 =Cf 2,10 1.25
D. Pnt.
Slope
c Cf
Length
(feet)
Overt Tc
(min.
Vel.Chan
(ft/sec.)
Tc Chan.
min.)
c TotalCOMMENTS
(min.)
C:
2.00
0.75
65.00
4.2
Tc (100)
0.50
565.00
1.501
6.3
-110v5.j
LNGST. OVERL. +CHANNEL
0.60 = Runoff C 1.00 = Cf 2,10 1.25 =Cf 100
D. Pnt. Area
(acres)
C *Cf
I (2yr.)
(in/hr)
I (10yr.)
On/hr)
I 100yr.)
(in/hr)
Basin Q
cfs
Comb. Q
(cfs)
COMMENTS
-1.17
0.60
2.48
1.74
1.1-1......., -.1:1.
2 yr. runoff
0.60
4.30
3.02
3 0
10 Y . runoff
1
0.75
6.90
6.051
100 yr. runoff
0.60 = C 1.00 =Cf 2,10 1.25 =Cf 100
4.44 = Area(ac) this page
DATE: FEBRUARY 1994
DEVELOPED RUNOFF COMPUTATIONS FOR 2/10/100 YR. STORMS
NORTHBROOK PATIO HOMES P.U.D.
FOR: Nebarado Construction
BY: Stewart & Associates
GENERAL NOTES: Velocity in a Channel per FIGURE 3-2
If C x Cf > = 1 then C x Cf = 1 (constants listed below)
For design of the developed site runoff quantities Tc(l 00) was the basis for des ! ign
BANBROKRO.wk3
HISTORIC RUNOFF COMPUTATIONS FROM RATIONAL METHOD
Q = C x Cf x I x A
SUBBASIN T.O.G 100 r
D. Pnt.
slope
C Cf
I-
Length
feet
Overt Tc
(min.)
Vel.Chan
(ft/sec.)
Tc Chan.
(min.)
Tc Total
(min.)
COMMENTS
0.25
540.00
36.9
Tc (100)
1.00
0.00
0.501
0.0
.36.9.
LNGST. OVERL.+CHANNEL
0.20 = Runoff C
1.00 = Cf 2,10 1.25 =Cf 100
1
D. Pnt.
Area
(acres)
C *Cf
I (2yr.)
(in/hr)
I (10yr.)
(in/hr)
I (100yr.)
(in/hr)
Basin Q
(cfs)
Comb. Q
(Cfs)
COMMENTS
6.30
0.201
1.281
1.61
:1:6
2 yr. runoff
0.201
2.29
2.89
q, Q
10 yr. runoff
0.251
3.67
5.78
100 r. runoff
y
0.20 = C 1.00 =Cf 2,10 1.25 =Cf(100)
SUBBASIN::J.O.C.:....(100
D. Pnt.
Slope
N
C Cf
Length
(feet)
Overt Tc
(min.)
Vel.Chan
(ft/sec.)
Tc Chan.
(min.)
c TotalCOMMENTS
(min.)
I b
1.00
0.25
95.001
15.5
Tc (100)
1.000.00
0.00
> 95i5]
UNGST. OVERL. +CHANNEL
0.20 = Runoff C 1.00 = Cf 2,10 1.25 =Cf 100
D. Pnt.
Area
(acres)
C CF--F
I -(2yr.)
(in/hr)
I (10yr.)
(in/hr)
1 (1 00yr.)
Cin/hr)
Basin Q
(cfs)cfs
Comb. Q
COMMENTS
1.051
0.201
2.10
1
0.44
2 yr. runoff
0.20
3.70
0.76
-0811
10 r. runoff
0.25
5.95
1.56
100 yr. runoff
0.20 = C 1.00 =Cf 2,10 1.25 =Cf 100
2:
7.35 = Project Area (ac)
12-YEAR HISTORIC 2,05]
PRELIMINARY HYDROLOGIC SUMMARY
NORTHBROOK SUBDIVISION
...TOTAL DEVELOPEDRUNOFF'...
11.61
2 yr. runoff
20.21
10 yr. runoff
-38.51
100 yr. runoff
NORTHBROOK DRIVE PAN::.--,,--
5.6
F-2 yr. runoff
9.71
10 yr. runoff
18.81
100 yr. runoff
,7.35 = Total project area(ac) Basins 13, 0(1/2)
ADDITIONAL FLOWTO INLET...
1�2
2
2 1
:Fyr.rrunoff
0 y runoff
3.71
100 yr. runoff
OUTFALL PAN NORTHIBROOKDRIVE
2 yr. runoff
,.4E ,2
10 r. runoff
24.11
100 yr. runoff
Basins A (HAMPSHIRE ROAD) Basin A, U
NORTHBROOK: CO URT PAN. -I,-,
2
2 r. runoff
�251
Toy_
yr. runoff
6.7
100 . runoff
i3asinsB(1/2) l::AL;H zjiuL
W.:PROSPECT ROAD]
1.51
2 yr. runoff
2.61
10 yr. runoff
4.61
100 yr. runoff
Basin E
BACKLOT PAN
1.7
2 r, runoff
3.01
yr. runoff
6.11
100 yr. runoff
Basin L;
HISTORIC.. RUNOFF:::...........
10yr.runoff
T:34
100 r. runoff
Northbrook Patio Homes P.U.D.
Page 2
The ground cover of the filled portion of the site varies from poor to
fair, and the ground cover of the unfilled portion is good grass. However,
all the unfilled portion will be stripped and filled. The resultant bare ground
will be reseeded if the units are not started on that part of the P.U.D. soon
after the fill is placed. Straw bale barriers and rock filters will be placed
at the discharge points into the pond. A silt fence will be placed along the
south and east property lines of the P.U.D.
The storm
drainage plan
any questions
Sincerely,
water runoff calculations and the preliminary grading and
are enclosed as a part of this preliminary report. If you have
regarding this report, please call.
62 Lam. 0
Richard A. Rutherford, P.E. & L.S.
President
jrr
enclosures
STEWART&ASSOCIATES
Consulting Engineers and Surveyors
February 7, 1994
Mr. Basil Harridan
Storm Water Utility
City of Fort Collins
P.O. Box 580
Fort Collins, Colorado 80522
Dear Basil:
The following is the preliminary.storm drainage report for Northbrook
Patio Homes P.U.D., Fort Collins, Colorado. The site contains 6.12 net acres
and 7.07 gross acres, including half of the Prospect Road and Hampshire Road
rights —of —way: It is located at the Southeast corner of West Prospect Road
and Hampshire Road in the Northeast ; of Section 21, Township 7 North, Range
69 West of the 6th P.M. It is Tract "G" and a part of Tract "H", Fairbrooke
S. I. D.
The site is in the Canal Importation Study Area. It is bounded on the
north by West Prospect Road, on the east by the Fairbrooke Detention Pond,
on the south by Fairbrooke Subdivision, Second Filing, and on the west by
Hampshire Road. The westerly 150 feet of the site has been filled. The site
slopes from west to east to the Fairbrooke Detention Pond at approximately
1.5%. There is an existing drainage channel approximately 400 feet south of
Prospect Road that flows easterly from the sump inlets on Hampshire Road to
the Fairbrooke Detention Pond.
The proposed P.U.D. will have 42 patio homes in 21 two —unit buildings.
It is proposed to fill the eastern part of the site to fit the western 150
feet. The existing 24—inch storm drain will be extended south along the east
side of Hampshire Road to a proposed 20—foot drainage easement along the south
line of the site. The 42—inch storm drain will then be extended easterly to
the detention pond. A 4.0 foot wide concrete pan will also be constructed
in the 20—foot easement to carry the major storm flows and the surface runoff
from the rear yards of the units on the south side of Northbrook Drive and
the rear yards of the lots in Fairbrooke Subdivision, Second Filing, to the
Detention Pond.
The site will be divided into five sub —basins. The runoff from Sub —Basins
"A" through "D" will flow directly into the Detention Pond in the 24—inch pipe
and two concrete pans. Sub —Basin "E" which is the south one—half of West
Prospect Road will enter the pond east of this P.U.D. Sub —Basins "A" through
"E" are Basin F-10 and part of Basin F-11 of the Fairbrooke S.I.D. Drainage
Report prepared by Parson and Associates and dated November 1983. Relevant
pages of that report are included in the appendix of this report.
James H. Stewart
and Associates, Inc.
103 S. Meldrum Street
P.O. Box 429
Ft. Collins, CO 80522
303/482-9331
Fax 303/482-9382
PRELIMINARY DRAINAGE REPORT
FOR
NORTHBROOK PATIO HOMES P.U.D.
FEBRUARY 7, 1994
STEWART & ASSOCIATES. INC.
103 SOUTH MELDRUM STREET
FORT COLLINS, COLORADO 80521
303/482-9331