HomeMy WebLinkAboutKNICKERS FINAL PUD - 10 91A - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTFinal Drainage Report
for
KNICKERS P.U.D.'
(LOUDEN CREEK GOLF COURSE)
Fort Collins, Colorado
1t��
Prepared for
KNICKERS, INC.
Ft. Collins, Colorado 00
PREPARED BY:
SHEAR ENGINEERING CORPORATION
Project No: 120-1-91
Date: May 6, 1991
4836 S. College, Suite 12 Fort Collins, CO 80525 (303)226-5334
S 7 V? , .. :
. ....... ..
^-I .... Ov.F.- A ..... -
/.C",42 7 47
5L45,0171-01V 0 0- 052 _= _28.00.
....... ....
i
0
6�
36
TIME
(Ivl�1lJlSfFfa)
�IM�
CSFGO�.IDS)
10
!Do 0
30
I PJOO
�0
3000
Coo
3�vo
1Zo
?2oa
I So
�i000
Ivn
Io,8ot7
-r[M,✓ CN4,AQL rF-S)
GLF
L
A
0.33
"I.00
26.3
0.'3
4.2a
z6'.3
0.�3
3.so
26.3
0,33
3. o0
26.3
0.33
2.l00
26.3
0,33
1.43
G"6.3
0,33
0.33
VOL.-U z
91�IE4flloE
VoWuE
Cr-r3)
CFta)
cL73�
65, 6/3
//� 880
S3� 733
7Z, 904
/5, 840
57� 064
78,111
/9, 800
8/, 235
2,31 700
5-7, 475
873 C41
35, 640
54-Pj 00/
89t .359
447, 520
4It 839
92, 9s2
59� 4G0
33, 55�
98; 4.30
7/, 28G
27 /40
9
w
SUE ti-4 ��FEIG (�S oL.F '2S E
srv4 E -s c CU>V E ; CC4JDLna.15
3ovc 0 9oc oc� (ZO, 000 f�,000
STo0.6raE CC.v6tc. GE -FT)
COQTOUfL IAlC2EMElJTAL, IWCCEl./W'r&L GVM,VL4-mvE
STiA6aE
tiliovrz
b2Ea
'PP-PTLt
VOLUl-A.E
�oLvnaC
(FT)
Ccr)
CSF)
C>:T)
CGF)
CGF)
/.�
25rao
25�0
/
5012
33V0
2,Co
ro,�o
13,440
.3
5oiy.
�1520
2.o0
22,2do
5
Sores
�,?Zo
Z.oa
313)S20
lS,2oc�
7
S016+
Zd,Soo
Q,oc�
P�.Gno
ISS,Zoo
9
So2o
=�5, Zo U
APPENDIX 8
Figure 3-1; City of Fort Collins Rainfall -Intensity -Duration curves
Figure 3-2, Travel Time Velocity Curves, Urban Drainage and Flood Control
District
Figure 804-1D, Culvert capacity nomograph, Colorado Department of Highways
Table 3-3, Rational Method runoff coefficients for Composite Analysis.
No Text
DRAINAGE CR' 'RIA MANUAL
RUNOFF
50
m
1-- 20
z
W
U
Cr
W
a
10
z
W
a
OJ
5
U)
W
¢
3
U
2
0:
W
.5
.1 .2 .3 .5 1 2 3 5 10 20
VELOCITY IN FEET PER SECOND
FIGURE 3-2. ESTIMATE OF AVERAGE FLOW. VELOCITY FOR
USE WITH THE RATIONAL FORMULA.
�I�
►IW
FA■I,■■//I�M
M■■■■�
�eG��'mw■■FAME
I/II
�MMM■■■■�
�
MWI
NII
■V
It
I �1/I
iiwm■■ll�
■i�iMFAW
�■►i��rw�■ww��■■����
*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
AIRL
8-27
FIGURE 804-11)
ISO
10,000
168
8,000
EXAMPLE
(2)
(3)
156
6 000
D•42 Inches (3.5 feat)
6.
6.
144
5,000
Q-120 cis
5
4,000
jv" nw
6'
5.
132
3,000
D feet
5'
4
(1) 2.5 8.8
4.
120
(2) 2.1 7.4
2,000
'(3) 2.2 7.7
4•
3
108
00
3'
in feet
96
1,000
3.
800
84
600
500
72
400
3
2.
rn
_ .
300
E
g��
6'I'p�
x
�-
1.5
1.5
Z
60
N
u
200
/ (�
�
1.5
Z
z
0
...
54
100 Gj
o
=
W
48
x
80/
J
o
/
=
0
6O
_
a
1.0
1.0
'A.
2
N
�0 HW ENTRANCE
W
O
.
1.0
�
40
p SCALE TYPE
W
9
F
36
30
111 Square edge with
-4
3
.9
' W
33
headwall
•9
Q
20
(2) Groove and with
la
-
G
30
headwall
x
.8
.8
(3) Groove and
8
2
projecting
10
7
T
24
8—
•
6
To use scale (2) or (3) project
2 1
5
horizontally to $cola (1), then
4
use straight Inclined line through
D and 0 scales, or reverse as
.6
3
illustrated.
g
'6
18
2
15
5
.5
5
I.O
12
HEADWATER
DEPTH
FOR
CONCRETE
PIPE CULVERTS
WITH
INLET
CONTROL
..N
R-M-P Medium Density Planned. Residential District — designation for medium density
areas planned as a unit (PUD) to provide a variation in use and building placements
with a minimum lot area of 6,000 square feet.
R-L-M Low Density Multiple Family District — areas containing low density multiple family
units or any other use in the R-L District with a minimum lot area of 6,000 square feet
for one -family or two-family dwellings and•9,000 square feet for multiple -family
dwellings.
M-L Low Density Mobile Home District — designation for areas for mobile home parks
containing independent mobile homes not exceeding 6 units per acre.
M-M Medium Density Mobile Home District — designation for areas of mobile home
parks containing independent mobile homes not exceeding 12 units per acre.
B-G General Business District — district designation for downtown business areas,
including a variety of permitted uses, with minimum lot areas equal to 1 /2 of the total
floor area of the building.
B-P Planned Business District — designates areas planned as unit developments to
provide business services while protecting the surrounding residential areas with
minumum lot areas the same as R-M.
H-B Highway Business District — designates an area of automobile -orientated busi-
nesses with a minimum lot area equal to 1 /2 of the total floor area of the building.
B-L Limited Business District — designates areas for neighborhood convenience
centers, including a variety of community uses with minimum lot areas equal to two
times the total floor area of the building.
C Commercial District —designates areas of commercial, service and storage areas.
I-L Limited Industrial District —designates areas of light industrial uses with a minimum
area of lot equal to two times the total floor area of the building not to be less than
20,000 square feet.
I-P Industrial Park District —designates light industrial park areas containing controlled
industrial uses with minimum lot areas equal to two times the total floor area of the
building not to be less than 20,000 square feet.
I-G General Industrial District — designates areas of major industrial development.
T Transition District — designates areas which are in a transitional stage with regard
to ultimate development.
For current and more explicit definitions of land uses and zoning classifications, refer to the
Code of the City of Fort Collins, Chapters 99 and 118.
Table 3-3
RATIONAL METHOD RUNOFF COEFFICIENTS FOR COMPOSITE ANALYSIS .. _
Character of Surface Runoff Coefficient
Streets, Parking Lots, Drives:
Asphalt................................................................................................ 0.95
95
Concrete 0.
Gravel................................................................................................ 0.50
Roofs 0.95
..........................................................................................................
Lawns, Sandy Soil:
Flat<2%............................................................................................. 0.15
..................................................................................
Average 2 to 7% 0.
Steep>7%.......................................................................................... 0.20
Lawns, Heavy Soil:
Flat<2%................................................................:............................ 0.20
Average 2 to 7% 0.25
Steep >7%..............................................................
0.35
MAY 1984
3-4
DESIGN CRITERIA
Te-
Knickers F.U.D. (Louden Creek Golf Course Drainage Flan); Stuffer
Envelope)
"yY
ac■000n000
�
,
' Y. O
Yl'S•S'�'v
A'
7.
�
a
a �► a r.i s• %e. �
�1 .._ _• _
`�--„—" r.
o
ww
Jess
Ms
-
—
gunnel
"' p�■o g
,�avl�YtiSITE
•
li
/
!
I
,
■
IM.,,see11
UPON
s
s
s_
Now
VICINITY MAP
PAGE 1
Knickers P.U.D. (Louden Creek Golf Course)
Final Drainage Report
I GENERAL LOCATE AND DESCRIPTION
A. Location
1. The Louden Creek Golf Course is located in South Fort
Collins in the Northeast one -quarter of Section 14, TEN,
R69W of the 6th P.M. It is located adjacent to, and west of,
Colorado State Highway 287.
2. The site is bounded partially on the north by the Hermitage
Annexation and partially by unplatted property, on the west
and south by unplatted property and on the east by Colorado
State Highway 287.
B. Description of property
1. Louden Creek Golf Course contains approximately 32.69 acres
(Triangle Farms Annexation).
2. The property is currently utilized as pasture/grassland and
is covered primarily with dryland wild grasses. Stables and
other equestrian related appurtenances exist on the site.
3. Development will consist of a 3 par, 9 hole golf course with
supplemental recreational facilities.
4. The site slopes moderately from west to east with slopes
reaching in the area of 6% to 7% nearing the east side of
the property.
5. The North Louden Ditch traverses the property. It will
remain unaffected and incorporated into the design of the
golf course. It will not be considered as a storm water
conveyance facility with this project.
II DRAINAGE BASINS AND SUB -BASINS
A. Major Basin description_
1. Louden Creek Golf Course is contained within the Fossil
Creek Drainage Basin.
2. The North Louden Ditch is located on the property and has
the potential to intercept storm runoff from the west. The
assumption that the ditch will be flowing at capacity will
be made for all rainfall events, though actual runoff to the
ditch will be analyzed.
B. Sub -basin description
1. The property is contained within a sub -basin consisting of
approximately 26.32 acres.
a. Runoff from a portion of the property, including
offsite contribution from the west (approximately 0.89
acres), concentrates at a point near the Southeast
corner of the property. An existing 24" RCP currently
conveys all storm runoff from the property, under
Highway 287, to Robert Benson Reservoir. Robert Benson
Reservoir is directly adjacent to Highway 287 on the
east side.
b. Since the existing 24" RCP restricts flow to a certain
rate, there is currently, an existing backwater
potential on the site for less frequent storms which
generate greater amounts of storm water. This will be
considered with detention volume requirements.
PAGE 2
Knickers P.U.D. (Louden Creek Golf Course)
Final Drainage Report
B. Sub -basin description (continued)
2. There will be absolutely no change to historic flow patterns
due to development of the Golf Course. Runoff will continue
to flow to the east, concentrate at the existing 24" RCP,
and be conveyed under Highway 287 to Robert Benson Reservoir
via the existing 24" RCP. Detention storage will be provided
so that the current overtopping potential of Highway 287
will be eliminated.
III DRAINAGE DESIGN CRITERIA
A. Regulations:
1. City of Fort Collins Storm Drainage Criteria was used.
B. Development criteria reference and constraints:
1. Although the North Louden Ditch is located on the property,
it will be assumed to be flowing full for peak runoff
calculations for the two storm frequency events under
consideration (2 year and 100 year storm frequencies).
2. Highway 287 and the existing 24" RCP under Highway 287
appear to be the main potential stormwater design
constraints. The 24" RCP was installed with the construction
of Highway 287. Highway Department Construction plans
indicate flow values and contributing area acreage to the
24" RCP (Contributing Area - 49 acres; (1100 = 34 cfs; G25 =
20 cfs). However, no backup drainage report for the values
indicated on the Highway Department plans was available from
the Highway Department.
C. Hydrological criteria
1. The Rational Method for determining peak flows was used for
the evaluation of the 2 and 100 year events.
2. The Cumulative Runoff method (Mass Curve) for determining
potential detention storage requirements will be utilized.
D. Hydraulic criteria
1. The 1990 Highway Department Roadway Design Manual culvert
nomographs were used to determine the Highway 287 24" RCP
culvert capacity with certain Headwater to Diameter (HW/D)
ratios.
IV DRAINAGE FACILITY DESIGN
A. General concept
1. Generally, there will be no change to historic flow
patterns. All storm runoff will continue to be conveyed to
the existing 24" RCP located at the southeast portion of the
property. Refer to the Drainage Plan included in the back
envelope of this report.
2. Detention will be provided for storage of the excess storm
water, over and above the historic 2-Year runoff rate.
3. In order to restrict the discharge to the 2 year historic
runoff rate, modifications to the 24" RCP outlet is
required.
PAGE 3
Knickers P.U.D. (Louden Creek Golf Course)
Final Drainage Report
A. General concept (continued)
4. Temporary erosion protection is anticipated at the existing
24" RCP until golf course plantings take hold. Possible
erosion control upstream of the North Louden Ditch is also
anticipated. Immediate planting will occur to establish golf
course fairways as soon as possible.
A. Specific Details
1. The 24" RCP outlet will be modified with a drainage
structure with orifice plate to restrict flows to the 2-year
historic rate of 6.6 cfs.
2. Detention storage requirements will be satisfied with the
expansion of the existing pond located at the existing 24"
RCP.
PM11IN1U1111-I N11
A. Compliance with standards
1. All drainage calculations and facility design comply with
the requirements of the City of Fort Collins Storm Drainage
Criteria Manual and the current storm drainage system
intent.
B. Drainage concept
1. The drainage concept for the Louden Creek Golf Course
remains unchanged from the existing drainage situation
except for detention and outlet control modifications.
2. All grading of golf course fairways will include the
provision for adequate conveyance of storm water runoff
through the site and to the detention area and 24" RCP.
3. There will be absolutely no additional potential downstream
impact due to the development of this project.
4. The potential for storm water flow over the curb into
Highway 287 exists (for current conditions) for less
frequent storms which generate more runoff. Storm water
detention and modifications to the 24" RCP outlet will be
provided so that no curb overtopping occurs. Freeboard has
been provided with the final detention pond grading design.
S. The detention volume determination with the cumulative
runoff method, considering a release rate of 6.6 cfs (2-year
historic for the site), results in a total volume
requirement of 58,300 cubic feet. This has been acheived
with the detention pond. grading design (See stage -storage
curve in appendix).
C. Specific Details
1. The requirement to provide a 7' detached walk along Highway
287 results in a loss of storage volume for existing grade
conditions. All volumes have been determined based on final
grading which includes the provision for a 7' detached walk
located from 8' behind the existing curb to 15' behind the
existing curb.
2. Required detention volumes have been acheived. The storage
volume includes excess to handle the contributing area form
the south of the property.
PAGE 4
Knickers P.U.D. (Louden Creek Golf Course)
Final Drainage Report
V CDMCLUSIDMS (continued)
D. Erosion Control
1. The affected areas of the site during earthwork operations,
will be restricted to the fairways and will be minimal
relative to the total area of the project.
2. Temporary erosion control protection will be provided at the
existing 24" RCP outlet control structure until golf course
plantings take hold.
3. Temporary erosion control upstream of the North Louden Ditch
will be provided to only the extent of the affected area.
Immediate appropriate seeding and planting will occur to
establish golf course fairways as soon as possible.
VI REFERENCES
1. City of Fort Collins Storm Drainage Criteria Manual
2. "Roadway Design Manual", Colorado Department of Highways, 1990.
3. Colorado Department of Highways construction plans for Highway
297, 1978.
APPENDIX A
Runoff Calculations
Mass Curve for detention potential (Cumulative Runoff Method)
Stage -Storage Curve for existing conditions
Stage -Storage Curve for proposed conditions
-------- -70
- A7
A,V -r-'. "1200 0 e. . 76,
.eeAC
.......... --- ---- -------------------
C 71a,
9, 4. ea))/z 6., 9, e...
-77
. ....... .. ... . ..
---- -------- .. 50cw- 1282-04 .6 7 AIIAI.
.94 -2ac ..- ------ -- ----------
'a-42 0--.
..P�!/S/�lzF ss�LPi unTE 03�2 9/
f
2
4147
QP��j�J_dL0_E�e' .yw y �87
• 5
G
el06 LTi3C�ZffB.Ef_I�
7
0
.ter_ -;L89_ AC&e
to
— -r-ozzCL = S.../_o' .
tt
12
13
14
-A.['<vaAvs_:�s7_v�_r_Aso��o✓S�.�A.✓�x�a��—o.._2s_Ccr�.E_na�.zQ)
15
/
�J..�Qi�4/IG'%iDi.9v,"/L�i.✓f�J.SO,flf��i�7�O�C-X-�.�0����Q.�� �f�w.�
.16
490+ lidoo
17
10
/oo
•
19
"_S._01�/��/2�d�' = /88.2�sfso%I.¢�' _ �l.•_3?�ix�nl. .
20
45. n i/.c/ r5E
21
22
23
24
25
2G
27
cxeae�il�e� 20