HomeMy WebLinkAboutHARMONY RIDGE PUD, PHASE ONE - PRELIMINARY - 49-95A - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTSC Al E I n^ /0,2
Harmony Ridge Detention Pond
THE MASS DIAGRAM FOR DETENTION REQUIREMENT
so
w
w
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U
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1-1
30
U�
O
20
En
0
0
O
10
0
iv.0 cu.0 W.0 wu.0 Ju.0 au.0 au.0 iw.0 MUM 1JU.0 iau.w
TIME IN MINUTES
MI Total Runoff Vol. M Allowable Discharge Vol.
REQUIRED DETENTION FOR THE 100 YR. STORM
Preliminary Harmony Ridge Detention Sizing
0.45 = Runoff (c) 6.08 = Area (acres) 2.37 = Release 0(21***
TIME
min
INTENSITY
in/hr
C*Cf*A
acre
RUNOFF
cu-ft
OUTFLOW
cu-ft
STORAGE
cu-ft
5.0
7.00
3.42
7182.0
711.0
6471.0
10.0
7.00
3.42
14364.0
1422.0
12942.0
15.0
6.10
3.42
18775.8
2133.0
16642.8
20.0
5.20
3.42
21340.8
2844.0
18496.8
25.0
4.68
3.42
24008.4
3555.0
20453.4
30.0
4.15
3.42
25547.4
4266.0
21281.4
35.0
3.83
3.42
27507.1
4977.0
22530.1
40.0
3.50
3.42
28728.0
5688.0
23040.0
45.0
3.25
3.42
30010.5
6399.0
23611.5
50.0
3.00
3.42
30780.0
7110.0
23670.0
55 0
2 80
3.42
: 31600 8
7821.0
23779,
60.0
2.60
3.42
32011.2
8532.0
23479.2
70.0
2.33
3.42
33468.1
9954.0
23514.1
80.0
2.05
3.42
33652.8
11376.0
22276.8
90.0
1.88
3.42
34719.8
12798.0
21921.8
100.0
1.70
3.42
34884.0
14220.0
20664.0
110.0
1.58
3.42
35663.8
15642.0
20021.8
120.0
1.45
3.42
35704.8
17064.0
18640.8
135.0
1.33
3.42
36843.7
19197.0
17646.7
150.0
1.20
3.42
36936.0
21330.0
15606.0
165.0
1.13
3.42
38259.5
23463.0
14796.5
180.00
1.05
3.42
38782.8
25596.0
13186.8
*** NOTE: -If C * Cf >= 1 , then C * Cf = 1 is used
Standard Form SF-9
HARMONY RIDGE
Calc'ed.By: AVE Storm Drainage System Design
Date: 9-95 (Rational Method Procedure)
Checked By: FDB
This area contributes to the newly developed storm drainage facilities for Harmony Ridge
Job No.
Project: Harmony Ridge
Design Storm:21100 Year
NOTE: TOC computations include overland, channel but not pipe times
F
G
H
r
7
K
r
G
H
►
K
a.ea
2.08
2.83
1.39
3.73
12 80
0.45
0.45
.45
0.45
1.913
0.936
1.274
0.626
6.179
5.760
14.4
15.5
17.6
16.0
20.8
15.9
2.17
2.10
1.97
2.07
1.81
2.07
4.15
1.97
2.51
1.29
11.18
11.92
N/A
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N/A
2-year
2-year
2-year
2-year
2-year
2- ear
�
F
G
H
F
G
I H
4.25
2.08
1 2.831
0.56
0.56
0.561
2.391
1.170
1.5921
123
14.3
1591
6.63
6.14
5921
15.85
7.18
9.7R
N/A
N/A
M/e
N/A
N/A
I MIA
N/A
N/A
N!A
N/A
N/A
N/A
N/A
N/A
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N/A
100-year
100- ear
37.08 = project drainage amain acres
r
NOTE -
s 0
September 1995
100 Year Time Of Concentration/ Intensity Calculations
For: Harmony Ridge
By: Stewart and Associates
T() = 1.87(1.1 —C*qD ^ 1.2 (S ^ 1/3)
T(c) = Length / (Velocity 60)
Yard slopes are assumed to be 2% unless otherwise indicated.
NOTES: Intensities are based
]
on information fromthe
.C!!y SDDCCM Fig 3-2
Intensity
...............
...............
4
36
2:
V'v
V'v
.... ..... .
5.42
:100
in
September 1995
2 Year Time Of Concentration/ Intensity Calculations
For: Harmony Ridge
By: Stewart and Associates
T@ = 1.87(1.1 -C*qD - 1.2 (S - 1/3)
T(c) = Length / (Velocity 60)
Yard slopes are assumed to be 2% unless otherwise indicated.
0.45 = Runoff C for Basin
Sub -Basin Type Flow Length Slope Time (T) Channel Time (Tt) 'TotcMR
(feet) (percent) (min) Vel. (fps) (minTO.Clmin)j
F Overland 160.01 2.01 1221 1
Grass Channel
....... .. ......... 0.01 0.01 i o.n 1 n n is a
AC -
Overland 55-01
2.0
7.2
Grass Channel 0
0.0
0.0
0.0
15Z 1
Concrete Channe 0
1.0
2.0
8.3
..... .... ...
Overland 115.0T-2.01
1_0._3F_
Grass Channel 1 0.01
0.01
0_._0
Concrete Channel 875.01
1.01
1 2.0
7.3.......
40.01
2.01
UAD
6.1
= munon t�)
ror vasin
0.01
0.01
1185.01
1.01
0.45 = Runoff (C)
for Basin
190.01
2.01
13.31
1
0.01
0.01
1 0.01-
0.0
895.0
1.0
2.01
7.5
0.45 = Runoff (C)
for Basin
65.01
2.01
7.81
1
0.01
0.01
1 0.01
0.0
980.01
1.01
1 2.01
8.2
NOTES: Intensities are based
on information the
Cq SDDCCM Fig 3-21
fntensay
r
.9
Yr.
....344
......
.:AW___vFj
.:AW___vFj
&W:
1.04. rx
2 7�
10.7
At
max
STEWART-9,06ACIATES
Consulting Engineers and Surveyors
103 S. M ELDRL , FORT COLLINS, CO 80521
PH. 482-9331 FAX 482-9382
By: Date: Client: Sheet No. -7 of_
Project: I P-Z-m 0 Q "I Cpr P-Lk rvS I
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STEWART&ASACIATES
Consulting Engineers and Surveyors
103 S. MELDRU. izORT COLLINS, CO 80521
PH. 482-9331 FAX 482-9382
By: .42 A-1P , Date: 6/gy[q_ - Client: r A i t Rve 17. E-� Tut_ Sheet No. & of
Project: —1� A n� o v X n c
Subject: roe m [A I A T F R u .V e) F G ( 4 c.,- A
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STEWART9,05SJGATES 103 PH. S. 938 RFAX FORT gOLLINS, CO 80521
Consulting Engineers and Surveyors
By: 2, A ,P , Date: 9 / Client: F,e F � F' n) rF :�� z r. =roe. Sheet No. 5_ of
Project: o ,v v G c
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STEWART&LALSS,jCIATES
Consulting Engineers and Surveyors
103 S. MELDRUi. ORT COLLINS, CO 80521
PH. 482-9331 FAX 482-9382
By: /e A• 12, Date: ? • i Z Client: F �. �F F �, - ,� e z es-_ itae Sheet No. 4 of
Project:
Subject: STOP' AA 1:0 (iA .,/ r
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Preliminary Drainage Report
Harmony Ridge P.U.D.
Page 3
If you have any questions regarding this preliminary report, please call.
Sincerely,
Cailatlir' . al -� �
Richard A. Rutherford, P.E. & L. S.
President
1-t-N
•��13TEq'•;pp4
A g.
Preliminary Drainage Report
Harmony Ridge P.U.D.
Page 2
and "H" will continue to flow Southerly in the proposed street and in a proposed swale along the
East property line of the P.U.D.. The runoff will be piped under the Trilby Lateral and then flow
in a swale on the Cathy Fromme Prairie to the Bums Tributary. Runoff from developed Sub -
basin "I" will also drain South in the proposed street to the end of the cul-de-sac and then be
piped under the Trilby Lateral and then flow in a drainage swale through the Cathy Fromme
Prairie to the Bums Tributary.
Developed Sub -basin "J" has a natural swale flowing from the North end of the sub -basin
to the South end of the sub -basin that also will be piped under the Trilby Lateral. The existing
swale continues to the Bums Tributary. The swale is in a proposed landscaped tract that will also
have a walking path.
Developed Sub -basin W' also has an existing drainage swale flowing from North to
South. The Easterly half of Sub -basin "K" is in Phase I of the development and the Westerly half
will be in Phase 11. The runoff from Sub -basin "K" will be piped under the Trilby Lateral and flow
to the Bums Tributary in a swale across the Cathy Fromme Prairie.
The historic sub -basins and the historic runoff table are shown on Sheet 1 of 2 for the total
project. The developed sub -basins and the developed runoff table for Phase I are shown on Sheet
2 of 2.
The site is in the moderate wind erodibility zone and in the high rainfall erodibility zone.
Silt fences, straw bale dikes and gravel filters will be used as mechanical means to control erosion.
Areas that are disturbed and will not be hard surfaced or built on for a period of time, will be
reseeded. Most of the steeper areas will not be disturbed until the walk out foundations are
constructed.
The storm water facilities such as the detention pond in the historic Sub -basin "A" and all
of the swales in the landscaped green areas will be maintained by the Harmony Ridge Home
Owners Association. It is proposed to have the City of Fort Collins maintain storm drain pipes
that are in public rights -of -way and easements.
The preliminary storm drainage design and drainage plan and report are in substantial
compliance with the City of Fort Collins Storm Drainage specifications and criteria except for the
proposed contours that are required. In the steep areas, the existing ground contours will be
maintained as much as possible. The units being built on the steep areas will have walk out
basements. As soon as the streets are designed, the final contours will be drawn on the final
grading and drainage plan.
STEWART&LA SSOCIATES
Consulting Engineers and Surveyors
September 18, 1995
Mr. Basil Harridan
Stormwater Utility
City of Fort Collins
P.O. Box 580
Fort Collins, CO 80522
Dear Basil:
The following is the preliminary drainage report for Harmony Ridge P.U.D. that is situate
in the Northwest 1/4 of Section 3; Township 6 North, Range 69 West of the 6th P.M., Fort
Collins, Colorado. The project contains 45.469 acres and is zoned R.L.P.. The project is
bounded on the North by West Harmony Road, on the East by the Light House Church and The
Ridge P.U.D., and on the South and West by the proposed Cathy Fromme Prairie. The Southerly
boundary is also the Trilby Lateral.
There are two proposed phases in the P.U.D.. Phase One will have 132 residential units
on 27.4 acres which has a resultant density of 4.82 units per acre. Phase Two will have 138 units
on 18.1 acres which has a resultant density of 7.62 units per acre.
The Harmony Ridge P.U.D. has 6.08 acres in the McClellands/Mail Creek Drainage Basin
and 40.3 acres in the Fossil Creek Drainage Basin.
Historic Sub -basin "A" is in the McClellands/Mail Creek Drainage Basin. The historic
storm water runoff from Sub -basin "A" sheet flows Northeasterly from the ridge that separates
the two major drainage basins to the Northeast comer of the proposed Harmony Ridge P.U.D..
The storm water runoff then flows Easterly in the existing borrow ditch on the South side of West
Harmony Road across the Light House Church property and across the Ridge P.U.D. to the
Ridge P.U.D. existing detention pond and then into the Pleasant Valley and Lake Canal. The
outlet into the Canal is being re -designed at this time to flow through the Westbury P.U.D. and
onto Mail Creek. It is proposed to detain the difference between the historic runoff in a two year
storm and the developed runoff in a 100 year storm onsite in the Northeast comer of Harmony
Ridge P.U.D.. The allowable historic outlet rate is 2.37 cubic feet per second from Sub -basin
"A". The runoff will continue to flow in the South borrow ditch until there is curb and gutter
along the frontage of the Light House Church. At that time the detention pond will discharge into
the Harmony Road curb and gutter.
Historic Sub-basins'B", licit, "D" and "E" are in the Fossil Creek Drainage Basin. It is
proposed to release the runoff from these four sub -basins undetained. Developed Sub -basins "G"
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
HARMONY RIDGE P.U.D.
PREPARED
FOR
FREE ENTERPRISES, INC.
SEPTEMBER 18, 1995
STEWART & ASSOCIATES, INC.
103 SOUTH MELDRUM STREET
FORT COLLINS, COLORADO 80521
970/482-9331