HomeMy WebLinkAboutKNICKERS PUD (LOUDEN CREEK GOLF COURSE) - PRELIMINARY - 26-88D - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTt0
Final Drainage and Erosion Control Report
for
LOUDEN CREEK DRIVING RANGE AND GOLF CENTER
(Tinian F.U.D.
Fort Collins, Colorado
INITIAL SUN1lTfAL.
date: 1,140 J= Pp 1
Prepared for
KNICKERS, INC.
Fort Collins, Colorado
Project No: 120-02-91
Date: December 2, 1991
4836 S. College, Suite 12 Fort Collins, CO 80525 (303)226-5334
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APPENDIX A
Storm Drainage Calculations
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REFERENCES
1. City of Fort Collins Storm Drainage Criteria Manual
2. City of Fort Collins Storm Erosion Control Manual
3. City of Fort Collins topographic Aerial for the SE 1/4 of Section
11, TGN, R69W
4. Preliminary Master Drainage Report for the Timan P.U.D.
by ROD, Inc., dated April 4, 1988
3.1.6 Runoff Coefficients
The runoff coefficients to be used with the Rational Method referred to in Section 3.2
"Analysis Methodology" can be determined based on either zoning classifications or the
1 types of surfaces on the drainage area. Table 3-2 lists the runoff coefficients for the various
types of zoning along with the zoning definitions. Table 3-3 lists coefficients for the different
kinds of surfaces. Since the Land Development Guidance System for Fort Collins allows land
development to occur which may vary the zoning requirements and produce runoff coeffi-
cients different from those specified in Table 3,-2, the runoff coefficients should not be based
solely on the zoning classifications.
The Composite Runoff Coefficient shall be calculated using the following formula:
C = (ICiA;)/At
i-1
Where C = Composite Runoff Coefficient
C, = Runoff Coefficient for specific area Ai
Ai = Area of surface with runoff coefficient of Ci
n = Number of different surfaces to be considered
At = Total area over which C is applicable; the sum of all Ai's is equal to At
Table 3-2
RATIONAL METHOD RUNOFF COEFFICIENTS FOR ZONING CLASSIFICATIONS
Description of Area or Zoning
Coefficient
Business: BP, BL........................................................................................
0.85
Business: BG, HB, C..................................................................................
0.95
Industrial: IL, IP
0.85
..........................................................................................
Industrial: IG...............................................................................................
0.95
Residential: RE, RLP..................................................................................
0.45✓
0.50
Residential: RL, ML, RP.............................................................................
Residential: RLM, RMP
0.60
..............................................................................
Residential: RM, MM
0.65
..................................................................................
Residential: RH..........................................................................................
0.70
Parks, Cemeteries
0.25
......................................................................................
Playgrounds...............................................................................................
0.35
RailroadYard Areas
0.40
...................................................................................
UnimprovedAreas......................................................................................
0.20
N
Zoning Definitions
R-E Estate Residential District — a low density residential area primarily in outlying
areas with a minimum lot area of 9,000 square feet.
R-L Low Density Residential District — low density residential areas located throughout
the City with a minimum lot area of 6,000 square feet.
R-M Medium Density Residential District — both low and medium density residential
areas with a minimum lot area of 6,000 square feet for one -family or two-family
dwellings and 9,000 square feet for a multiple family dwelling.
R-H High Density Residential District— high density residential areas with a minimum lot
area of 6,000 square feet for one -family or two-family dwellings, 9,000 square feet
for a multiple family dwelling, and 12,000 square feet for other specified uses.
R-P Planned Residential District —designation of areas planned as a unit (PUD) to pro-
vide a variation in use and building placements with a minimum lot area of 6,000
square feet.
R-L-P Low Density Planned Residential District— areas planned as a unit (PUD) to permit
variations in use, density and building placements, with a minumum lot area of 6,000
square feet.
MAY 1984 3.3 DESIGN CRITERIA
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
Runoff Coefficient
Character of Surface
Streets, Parking Lots, Drives:
Asphalt................................................................................................ 0.95
Concrete..................................................................... .................................................. ........................................... 0.95
Gravel............................ 0.50
Roofs..........................................................................
Lawns, Sandy Soil:
Flat <2% ...........................,
..................
Average2 to 7%.................................................
Steep>7%.........................................................
Lawns, Heavy Soil:
Flat<2%............................................................
Average2 to 7%.................................................
Steep>7%......... :...............................................
MAY 1984 3-4
0.95
0.10
0.15
0.20
0.20
0.25
0.35
DESIGN CRITERIA
No Text
1.2JO -40.17- Y/
RMIINC
Engineering Consultants
2900 South College Avenue
Fort Collins, Colorado 80525
303/226-4955
April 4, 1988
Susan Hayes
City of Fort Collins
Storm Drainage Department
P.O. Box 580
Fort Collins, Colorado 80522
RE: TIMAN P.U.D. MASTER DRAINAGE REPORT
Dear Susan:
Site Location
On behalf of Jeff Timan, RBD Inc. submits the following Prelimi-
nary Master Drainage Report for the Timan P.U.D.
The Timan P.U.D. site is located along the west side of State
Highway 287 (South College Avenue) north of Trilby Road. The 56
acre parcel is bounded on the north by Skyway Drive, on the east
by State Highway 287 on the south by Trilby Road and on the west
by the First Freewill Baptist Church, Skyway Acres Subdivision
and the Foothills Gateway facility. More'precisely this location
can be described as being situated in the east half of the
southeast quarter of Section 11, Township 6 North, Range 69 West
of the 6th P.M. in Larimer County, Colorado.
Existing Drainage
The site currently contains a commercial parcel in its southeast
corner and one residence. The vast majority of the site is used
for pasture. The site is traversed by a small irrigation lateral
which enters the site in the southwest corner, and exits the site
in the northwest corner. The lateral meanders along a ridgeline
through the site. The site slopes generally eastward at slopes
of 1.5% to 8% below the ridgeline and approximately 2.5% above
the ridgeline. Two RO^p ridges protrude eastward from the prin-
cipal ridge. These ridges have the effect of dividing the
lower area into three basins. Each of these basins have low
areas which are formed by the state highway embankment. These
areas are drained by culverts which run under State Highway 287
Other Offices: Vail, Colorado 303/476-6340 • Colorado Springs, Colorado 303/574-3504
and the commercial areas on the other side of the highway. The
two northern basins appear to have limited wetlands in their low
lying areas.
Offsite Drainage
Offsite drainage flows have a definite impact on this site. Of-
fsite flows will impact the site along the west property line.
No offsite flows are anticipated from any other region.
The first and most southern offsite area contributing flows along
the west property line is largely undeveloped area occupied by a
single church building with an unimproved parking area (see Of-
fsite Exhibit A in Appendix). Flows from this 7.6 acre area are
currently diverted into the forementioned irrigation lateral.
This lateral appears to have adequate capacity to handle 100 year
flows from this area, without substantially impacting the Timan
P.U.D.
The second offsite area is comprised of portions of the Skyway
Acres residential area and the Good Samaritan Center. Drainage
flows are collected in the street system in this area and flow
undetained into a concrete lined swale that runs northward just
west of the west property line of the Timan P.U.D. This swale
appears to be greatly undersized for 10 year as well as 100 year
flows. Therefore the majority of these flow will enter the site
undetained along the described swale.
The third offsite area is comprised principally of the Foothills
Gateway facility. Drainage from this area flows eastward until
it is intercepted by a grass swale which is a continuation of the
concrete swale mentioned in Offsite Area 2. This grass swale has
greater capacity due to a more substantial berm along its eastern
sideslope. This swale carries flows northward to the storage
pond which lies just west of the northwest corner of the Timan
P.U.D. At this point flows either enter the storage pond or fol-
low the Foothills Gateway entrance road and flow into Skyway
Drive. As a result of these conditions no offsite flows are an-
ticipated from this area.
Proposed Drainage
The attached Master Drainage and Utility Plan illustrates the ap-
proach taken in facilitating drainage onsite. Onsite drainage
will be handled rather simply utilizing the two. northern low
areas for the required site detention. This will be done in or-
der to reduce or eliminate grading in the wetland areas. An ad-
ditional improvement will be the piping of the irrigation lateral
from a point close to where the lateral crosses the west property
line to the north property line. This will simplify site grading
and access to the area above the lateral.
Basin A comprises roughly the northern third of the site.
Drainage flows in this area will be conveyed through a system of
curb and gutter, culverts, swales and storm drain piping to the
forementioned low area. This area provides the required deten-
tion with a minimal amount of grading. Most of this grading will
be above the wetlands thus reducing its impact. The culvert
opening will be redesigned to restrict outfall to the required
rate. No offsite flows will enter this basin.
Basin B comprising the remainder of the site will be handled in
much the same manner. Drainage flows will be conveyed in a
similar system to the low area at the midpoint of the highway
frontage. Again grading will be limited in the low area to areas
above the wetlands. The principal difference from Basin A, will
be that facilities carrying flows from the area adjacent to Of-
fsite Area 2 will be oversized to accommodate the undetained of-
fsite flows.
rnnrl iicinn
Calculations which substantiate the proposed approach appear in
the attached Appendix. All calculation reflect use of the City
of Fort Collins Storm Drainage Criteria. Detailed calculations
for the sizing of culverts and the design of outlet works will be
submitted with the Final Master Drainage Report. The approach
outlined in this report should provide for the efficient and safe
conveyance of drainage through the site.
Sincerely,
RBD, Inc.
C�__ - W -'I—
Stan A. Myers, P.E.
cc: 272-001
A P P END IX
OFFSITE DRAINAC
EXHIBIT A
GOB®. _
,m A ITA4 "
t �T R l�
o `
lAy
_ 1 e� •Y 'i I DIVISION
y am. i L - I 1 l-J f
QFFSIT
l�RF-A- t - - '�J fl lo.. _ r
C CRET DRAIN P N , -zQ
i i �•}'r.o �- �� - I:1'-1� I -� GRASS
i, ,/ - • ;;J .. Q = 36.85 cfs
10
100
aE
SCALE: 1*=200'
LU
>
>
cl)
/-,i:bOTHILLS
�"G AT E,�"
SWALE
•
T1
6�84 CfS"
10
2 2.3,,c f S,-
0..
61SOINC
g:r%rj;nc3prinri rnnclllfA.nte,
DATE: .=/23/88
PROJECT: TIMAN
JOB NUMBER: 272-001
DESIGN ENGINEER: SAM
BASIN DESIGNATION = Al
DETERMINE EXISTING 0 FOR 2 YEAR STORM
HISTORIC RUNOFF COEFFICIENT .25
BASIN SLOPE: 4.2 PERCENT
BASIN LENGTH 120o FEET
AREA: 20.09 ACRES
HIST TC = 1.87*(1.1-( 1 .25
))*SORROOT 1200 ))/ 4.2
1/3 = 34.14359 MINUTES
HISTORIC RAINFALL INTENSITY: 1.404752 INCHES/HOUR
HISTORIC OUTFALL: 7.055366 CUBIC FEET PER SECOND
DETERMINATION OF DETENTION POND VOLUME FOR DEVELOPED CONDITIONS
DEVELOPED STORM: 100
DEVELOPED RUNOFF COEFFICIENT
CCFAC =
20.09
.85
DURATION
I1IN
5
10
15
30
45
60
90
120
180
36o
21 .3ti4563
GROSS VOL.
CU. FT.
54966.24
84619.08
107762.8
148987.4
179001.9
188765.6
203953.7
203293.1
225650.9
251697.5
YEAR STORM
. 85
1.25
OUTFLOW VOL.
CU. FT.
2116.61
4233. 221
6349.631
12699.66
19049.49
25399.Z2
38093.99
50793.65
76197.97
152395.9
DETENTION VOL.
CU. FT
52849.64
80385. 86
101412.9
136287.3
159952.4
163366.3
165854.7
157494.5
149452.9
99291.58
REQUIRED DETENTION VOLUME IS 165854.7 CU. FT. OR
3.8075 ACRE FEET
CLIENT
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DATE: 3/28/88
PROJECT: TIMAN
JOB NUMBER: 272.001
DESIGN ENGINEER: SAM
BASIN DESIGNATION = 10 13
DETERMINE EXISTING 0 FOR 2 YEAR STORM
HISTORIC RUNOFF COEFFICIENT
.25
BASIN SLOPE: 2.4
PERCENT
BASIN LENGTH 1850
FEET
AREA: 39.3 ACRES
HIST TC = 1.87*(1.1-( 1
*
.25
))*SQRROOT 1850
))/
2.4
= 51.07826
MINUTES
HISTORIC RAINFALL INTENSITY:
1.126278
INCHES/HOUR
HISTORIC OUTFALL: 11.06569
CUBIC FEET
PER SECOND
DETERMINATION OF DETENTION POND VOLUME FOR DEVELOPED CONDITIONS
DEVELOPED
STORM:
100
YEAR STORM
DEVELOPED
RUNOFF COEFFICIENT
.85
CCFAC =
.85
*
1.25
=
41.75625
DURATION
GROSS VOL.
OUTFLOW VOL.
MIN
CU. FT.
CU. FT.
5
107524.8
3319.706
10
165531.6
6639.411
15
210805.2
9959.116
30
291448.8
19918.23
45
350163
29877.35
60
369262.8
39836.47
90
398973.6
59754.7
120
407462.4
79672.93
180
441417.6
119509.4
360
492350.4
Z39018.8
REQUIRED
DETENTION
VOLUME IS
339218.9
7.787395
ACRE FEET
^ 1/3
* 39.3
DETENTION VOL.
CU. FT
104205.1
158892.2
200846.1
271530.6
320285.7
329426.3
339218.9
327789.5
321908.2
Z53331.6
CU. FT. OR
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