HomeMy WebLinkAboutKMART PLAZA - PDP/FDP - 38-97 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTNo Text
I
1 Appendix B — Hydraulic Calculations
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FLOW CALCULATIONS
10-year
EXISTING
DP
1
Sub -Basin
Area
C
tc
C"A
I
Q
A
0.83
0.76
5.0
0.63
5.6
3.5
2
B
1.87
0.84
8.5
1.57
4.6
7.2
3-a
C-1
1.10
0.80
11.4
0.88
4.2
3.7
3-b
C-2
0.37
0.70
9.3
0.26
4.5
1.2
4
D
1.53
0.88
5.3
1.35
5.5
7.4
5
E
1.22
0.83
9.2
1.01
4.5
4.6
'
6
F
1.80
0.89
5.0
1.60
5.6
9.0
7
G
0.71
0.87
5.5
0.62
5.5
3.4
8
H
0.43
0.86
5.2
0.37
5.6
2.1
TOTALS
9.86
42.02
100-year
EXISTING
DP
Sub -Basin
Area
C
tc
C'A
I
Q
1
A
0.83
0.82
5.0
0.68
7.0
4.8
2
B
1.87
0.88
8.5
1.65
7.0
11.5
3-a
C-1
1.10
0.85
11.4
0.94
6.8
6.4
'
3-b
C-2
0.37
0.78
9.3
0.29
7.0
2.0
4
D
1.53
0.91
5.3
1.39
7.0
9.7
5
E
1.22
0.88
9.2
1.07
7.0
7.5
'
6
F
1.80
0.91
5.0
1.64
7.0
11.5
7
G
0.71
0.91
5.5
0.65
7.0
4.5
8
H
0.43
0.89
5.2
0.38
7.0
2.7
TOTALS
9.86
60.59
10-year
PROPOSED
DP
Sub -Basin
Area
C
tc
C"A
I
Q
1
A
0.83
0.76
5.0
0.63
5.6
3.5
2
8
1.87
0.84
8.5
1.57
4.6
7.2
3-a
C-1
1.10
0.80
11.4
0.88
4.2
3.7
'
3-b
C-2
0.37
0.70
9.3
0.26
4.5
1.2
4
D
1.53
0.88
5.3
1.35
5.5
7.4
5
E
1.22
0.82
9.3
1.00
4.5
4.5
'
6
F
1.80
0.89
5.0
1.60
5.6
9.0
7
G
0.71
0.87
5.5
0.62
5.5
3.4
8
H
0.43
0.86
5.2
0.37
5.6
2.1
'
TOTALS
9.86
41.97
100-year
PROPOSED
DP
Sub -Basin
Area
C
tc
C"A
I
Q
1
A
0.83
0.82
5.0
0.68
7.0
4.8
2
B
1.87
0.88
8.5
1.65
7.0
11.5
3-a
C-1
1.10
0.85
11.4
0.94
6.8
6.4
3-b
C-2
0.37
0.78
9.3
0.29
7.0
2.0
4
D
1.53
0.91
5.3
1.39
7.0
9.7
5
E
1.22
0.86
9.3
1.05
7.0
7.3
6
F
1.80
0.91
5.0
1.64
7.0
11.5
7
G
0.71
0.91
5.5
0.65
7.0
4.5
8
H
0.43
0.89
5.2
0.38
7.0
2.7
TOTALS
9.86
60.42
DRAINAGE CRITERIA MANUAL
RUNOFF
50
30
t- 20
Z
to
U
a 10
Z
ILI
C-
C)
Cn
5
Lil
3
Q
U 2
C
IS.I
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C
1
fHy
I
0
4.0 Oy
Cl
I IQ.� I I LT ?mil U 4�
C
;r I T
aT
1
1ti
1
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I
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Figure 3-3
.2 .3 .5 I 1' I ,'5 2 3 5
VELOCITY IN FEET PER SECOND
ESTIMATE OF AVERAGE FLOW VELOCITY FOR
USE WITH THE RATIONAL FORMULA.
10 20
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
No Text
TIME OF CONCENTRATION - EXISTING
SUB -BASIN DATA
Ti / To
Tt
Tc CHECK
LENGTH,
SLOPE,
Ti,
LENGTH,
SLOPE,
VEL,
Tt,
LENGTH,
Tc=(L/180)+10
Tc,
Desi nation
C5
Area
ft
%
min
ft
%
fps
min
FT
min
min
A
0.72
0.83
60
3.3
3.6
160
2.6
3.3
0.8
220
11.2
5.0
B
0.81
1.87
380
1.7
8.5
380
12.1
8.5
C-1
0.77
1.10
310
1.0
10.5
50
2.7
1.2
0.7
20
0.6
1.5
0.2
380
12.1
11.4
C-2
0.67
0.37
210
1.9
9.1
30
1.5
2.4
0.2
240
11.3
9.3
D
0.85
1.53
110
2.0
3.7
240
1.7
2.5
1.6
350
11.9
5.3
E
0.81
1.22
150
1.0
6.4
235
0.5
1.4
2.8
385
12.1
9.2
F
0.86
1.80
110
2.0
3.6
195
1.9
2.9
1.1
305
11.7
5.0
G
0.85
0.71
110
2.0
3.7
265
1.6
2.5
1.8
375
12.1
5.5
H
0.83
0.43
180
2.0
5.2
1
1
1
1 180
11.0
5.2
TIME OF CONCENTRATION - PROPOSED
SUB -BASIN DATA
Ti/To
Tt
Tc CHECK
LENGTH,
SLOPE,
Ti,
LENGTH,
SLOPE,
VEL,
Tt,
TOJAL
LENGTH,
Tc=(L/180)+10
Tc,
Designation
C5
Area
ft
%
min
ft
%
fps
min
FT
min
min
A
0.72
0.83
60
3.3
3.6
160
2.6
3.3
0.8
220
11.2
5.0
B
0.81
1.87
380
1.7
8.5
380
12.1
8.5
C-1
0.77
1.10
310
1.0
10.5
50
2.7
1.2
0.7
20
0.6
1.5
0.2
380
12.1
11.4
C-2
0.67
0.37
210
1.9
9.1
30
1.5
2.4
0.2
240
11.3
9.3
D
0.85
1.53
110
2.0
3.7
240
1.7
2.5
1.6
350
11.9
5.3
E
0.79
1.22
150
1.0
6.8
120
0.5
1.4
1.4
115
0.8
1.8
1.1
385
12.1
9.3
F
0.86
1.80
110
2.0
3.6
195
1.9
2.9
1.1
305
11.7
5.0
G
0.85
0.71
110
2.0
3.7
265
1.6
2.5
1.8
375
12.1
5.5
H
0.83
0.43
180
2.0
5.2
180
11.0
5.2
I 1
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1
SUB -BASIN "E" - PROPOSED
DESCRIPTION
AREA (SF)
AREA (AC)
C5
C10
C100
I
Building
6,500
0.15
0.85
0.90
0.90
90%
Asphalt
34,338
0.79
0.88
0.90
0.93
100%
Landscaping
6,381
0.15
0.18
0.25
0.45
7%
Concrete
6,124
0.14
0.87
0.88
0.89
96%
Totals / Average Values 53,343 1.22 0.79 0.82 0.86 87%
M:M=L'I►91i A
DESCRIPTION
AREA (SF)
AREA (AC)
C5
C10
C100
I
Building
30,800
0.71
0.85
0.90
0.90
90%
Asphalt
43,560
1.00
0.88
0.90
0.93
100%
Landscaping
800
0.02
0.18
0.25
0.45
7%
Concrete
3,360
0.08
0.87
0.88
0.89
96%
Totals / Average Values 78,520 1.80 0.86 0.89 0.91 95%
SUB -BASIN "G"
DESCRIPTION
AREA (SF)
AREA (AC)
C5
C10
C100
I
Building
3,400
0.08
0.85
0.90
0.90
90%
Asphalt
25,866
0.59
0.88
0.90
0.93
100%
Landscaping
1,300
0.03
0.18
0.25
0.45
7%
Concrete
480
0.01
0.87
0.88
0.89
96%
Totals / Average Values 31,046 0.71 0.85 0.87 0.91 95%
SUB -BASIN "H"
DESCRIPTION
AREA (SF)
AREA (AC)
C5
C10
C100
I
Building
3,839
0.09
0.85
0.90
0.90
90%
Asphalt
13,276
0.30
0.88
0.90
0.93
100%
Landscaping
1,100
0.03
0.18
0.25
0.45
7%
Concrete
700
0.02
0.87
0.88
0.89
96%
Totals / Average Values 18,915 0.43 0.83 0.86 0.89 92%
I
rSUB
"A"
-BASIN
DESCRIPTION
AREA (SF)
AREA (AC)
C5
C10
C100
I
Building
3,485
0.08
0.85
0.90
0.90
90%
Asphalt
20,473
0.47
0.88
0.90
0.93
100%
Landscaping
7,841
0.18
0.18
0.25
0.45
7%
Concrete
4,356
0.10
0.87
0.88
0.89
96%
Totals / Average Values
36,155
0.83
0.72
0.76
0.82
78%
'
SUB -BASIN "B"
DESCRIPTION
AREA (SF)
AREA (AC)
C5
C10
C100
I
Building
Asphalt
6,600
64,411
0.15
1.48
0.85
0.88
0.90
0.90
0.90
0.93
90%
100%
Landscaping
7,301
0.17
0.18
0.25
0.45
7%
Concrete
3,145
0.07
0.87
0.88
0.89
96%
Totals / Average Values
81,457
1.87
0.81
0.84
0.88
91%
SUB -BASIN "C-1"
DESCRIPTION
AREA (SF)
AREA (AC)
C5
C10
C100
I
Building
7,075
0.16
0.85
0.90
0.90
90%
Asphalt
32,527
0.75
0.88
0.90
0.93
100%
'
Landscaping
7,289
0.17
0.18
0.25
0.45
7%
Concrete
1,025
0.02
0.87
0.88
0.89
96%
'
Totals / Average Values
47,916
1.10
0.77
0.80
0.85
84%
SUB -BASIN "C-2"
DESCRIPTION
AREA (SF)
AREA (AC)
C5
C10
C100
I
Asphalt
8,337
0.19
0.88
0.90
0.93
100%
Landscaping
4,835
0.11
0.18
0.25
0.45
7%
Concrete
2,945
0.07
0.87
0.88
0.89
96%
Totals / Average Values
16,117
0.37
0.67
0.70
0.78
71 %
'
"D"
SUB -BASIN
DESCRIPTION
AREA (SF)
AREA (AC)
C5
C10
C100
I
Building
17,825
0.41
0.85
0.90
0.90
90%
'
Asphalt
44,922
1.03
0.88
0.90
0.93
100%
Landscaping
2,040
0.05
0.18
0.25
0.45
7%
'
Concrete
1,860
0.04
0.87
0.88
0.89
96%
Totals / Average Values
66,647
1.53
0.85
0.88
0.91
94%
'
SUB -BASIN "E" - EXISTING
DESCRIPTION
AREA (SF)
AREA (AC)
C5
C10
C100
I
Asphalt
45,393
1.04
0.88
0.90
0.93
100%
Landscaping
5,270
0.12
0.18
0.25
0.45
7%
Concrete
2,480
0.06
0.87
0.88
0.89
96%
'
Totals / Average Values
53,143
1.22
0.81
0.83
0.88
91%
I 1
DRAINAGE CRITERIA MANUAL RUNOFF
TABLE 3-1 (42)
RECOMMENDED -RUNOFF COEFFICIENTS AND PERCENT IMPERVIOUS
LAND USE OR
PERCENT
FREQUENCY
SURFACE CHARACTERISTICS
IMPERVIOUS
2
5
10
100
Business:
Commercial Areas
95
.87
.87
.88
.89
Neighborhood Areas
70
.60
.65
.70
.80
Residential:
Single -Family
*
.40
.45
.50
.60
Multi -Unit (detached)
50
.45
.50
.60
.70
Multi -Unit (attached)
70
.60
.65
.70
.80
1/2 Acre Lot or Larger
*
.30
.35
.40
.60
Apartments
70
.65
.70
.70
.80
Industrial:
Light Areas
80
.71
.72
.76
.82
Heavy Acres
90
.80
.80
.85
.90
Parks, Cemetaries:
7
.10
.18
.25
.45
Playgrounds:
13
.15
.20
.30
.50
Schools:
50
.45
.50
.60
.70
Railroad Yard Areas
20
.20
.25
.35
.45
Undeveloped Areas:
Historic Flow Analysis-
2
(See
"Lawns")
Greenbelts, Agricultural
Offsite Flow Analysis 45
(when land use not defined)
Streets:
Paved 100
Gravel (Packed) 40
nriva and Walkc- 96
Roofs:
Lawns, Sandy Soil
Lawns, Clayey Soil
90
0
0
.43 .47 .55 .65
.87
.88
.90
.93
.40
.45
.50
.60
.87
.87
.88
.89
.80
.85
.90
.90
.00
.01
.05
.20
.05
.15
.25
.50
NOTE: These Rational Formula coefficients may not be valid for large basins.
*See Figure 2-1 for percent impervious.
11-1-90
URBAN DRAINAGE AND FLOOD CONTROL DISTRICT
SECTION VI - APPENDICES
' Appendix A - Hydrologic Calculations
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' December 3, 1997
Kmart Plaza Retail Drainage Investigation
97-017
and additional landscaping. The present site drainage patterns of this sub -basin will not be affected by the
improvements, except to redirect 3.5 cfs (100-year runoff) behind the retail space into the existing inlet via
' a 1.8-foot-wide concrete trickle channel. In fact, the proposed shops would actually decrease the amount of
direct runoff from this sub -basin by 0.1 cfs and 0.2 cfs for the 10-year and 100-year storms, respectively.
SECTION IV - DRAINAGE FACILITY DESIGN
A. DRAINAGE STRUCTURES DESCRIPTION AND DESIGN
' As previously mentioned, the project site will require the construction of approximately 1101f of concrete
trickle channel located on the east side of the proposed retail shops. This channel will be constructed to
convey a portion of the sub -basin direct runoff to the existing inlet which presently accepts this runoff. The
' channel will be constructed in order to allow for the service ramp and screen wall to be constructed on the
southeast corner and along the east side of the building.
The channel has been designed to convey 100-year storm flows, and will have physical dimensions of 6"
deep and 1.8' wide, and will slope to the inlet at 0.5% grade.
'
SECTION V - CONCLUSIONS AND RECOMMENDATIONS
A. CONCLUSIONS
The proposed site improvements for the Kmart Plaza Retail Shops will not impact the project site nor
surrounding properties, but will in fact slightly decrease the amount of direct runoff received at the existing
inlet near the site access from South College Avenue (Design Point 5 on the map).
No facilities are proposed for detention purposes since the site is fully developed and again, will not be
negatively impacted by the proposed improvements. A small concrete trickle channel is however, proposed
and will be the only drainage structure improvement proposed for the site.
B. CONFORMANCE WITH DESIGN STANDARDS
This drainage investigation was prepared according to the criteria set forth in the Fort Collins Storm
Drainage Design Criteria and Construction Standards, as well as criteria established in Volume 1 of the
Urban Drainage and Flood Control District Drainage Criteria Manuals.
'
This project does not impact nor is impacted by any major drainageways nor modifies any major
drainageway study.
'
SECTION VI - REFERENCES
1. Storm Drainage Design Criteria and Construction Standards. City of Fort Collins, May 1984
(FCSDC)
2. Drainage Criteria Manual, Vol. 1, Urban Drainage and Flood Control District, March 1969
(UDTCM)
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December 3, 1997
Kmart Plaza Retail Drainage Investigation
97-017
SECTION I — INTRODUCTION
A. Purpose and Intent
The purpose of this drainage investigation is to determine the extent of drainage impacts upon the Kmart
Plaza Retail Center due to the addition of 6500 sf of retail space.
This investigation is intended to provide the best drainage management plan possible given the confining
developed conditions of the subject site and to assure the at minimum, no increase in the impacts of the site
drainage upon neighboring properties and public facilities.
B. Location and Description
The site is located on the northwest corner of the intersection of South College Avenue and Drake Road in
Fort Collins, Colorado in the Kmart Plaza shopping center.
The site and surrounding properties are presently developed, and therefore present little flexibility in
structure and facility modification and/or adaptation. Alternately, however, since there is little
modification proposed to the site, drainage impacts upon the project site and surrounding properties will be
negligible. On -site there is presently a Kmart discount store, a Jiffy Lube auto service center, and 4500 sf
of independent retail. Adjacent to the site is a bank to the north across the site access, and South College
Avenue to the east. A Denny's restaurant is also located north of the bank near the project location.
SECTION II - DRAINAGE DESIGN AND CRITERIA
A. GENERAL CONCEPT
Site flows will continue to flow according to the current drainage patterns. The only alteration in drainage
pattern will be the slight redirection of runoff generated in Sub -basin "E" as shown on the drainage plan,
behind the proposed retail shops; this redirection will not, however, result in concentration of these flows
to any other design point.
B. DESIGN CRITERIA
Drainage calculations and design for this project were based upon criteria set forth in the City of Fort
Collins Storm Drainage Design and Construction Standards (FCSDC), and Vol. 1 of the Urban Drainage
and Flood Control District Drainage Criteria Manuals (UDTCM).
SECTION III - DRAINAGE BASINS
A. SUB -BASIN DESCRIPTIONS
Although the Kmart Plaza site contains more sub -basins than those evaluated in this report, some were
eliminated due to their proximity to the project and because those sub -basins would have no impact upon
nor be impacted by the proposed improvements to the Plaza. Specifically, only those sub -basins which
drain toward the project site or into inlets proximal to the project site were evaluated.
' In all, eight sub -basins were delineated to describe the drainage situation at the Plaza. They range in size
from 0.37 acres to 1.87 acres in size, and slope gently, from 3.3% to 1.1 %. All of the basins are presently
developed and contain differing combinations of buildings, concrete walks and landscape areas in addition
to the predominant asphalt pavement throughout the site.
' The sub -basin "E" which contains the proposed retail shop improvements is approximately 1.22 acres in
size, slopes to the northeast at 1.0%, and currently contains only asphalt parking with minimal landscaping.
tThe proposed improvements would include the addition of 6500 sf of retail space, concrete patio and walk,
TABLE OF CONTENTS
Item Description Page
SECTION I - INTRODUCTION 1
A. Purpose and Intent
B. Location and Description
SECTION II - DRAINAGE DESIGN AND CRITERIA 1
A. General Concept
B. Design Criteria
SECTION III - DRAINAGE BASINS I
B. Sub -Basin Descriptions
SECTION IV - DRAINAGE FACILITY DESIGN 2
A. Drainage Structures Description and Design
SECTION V - CONCLUSIONS AND RECOMMENDATIONS 2
A. Conclusions
B. Conformance with Design Standards
SECTION VI - REFERENCES 2
SECTION VI - APPENDICES
Appendix A - Hydrologic Calculations
Appendix B - Hydraulic Calculations
II
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ENGINEER'S CERTIFICATION
I hereby certify that this report (plan) for the Drainage Investigation for the Kmart Plaza Retail Shopsnts
was prepared by me (or under my direct supervision) in accordance with the provisions of the City of Ft.
Collins Storm Drainage Design and Technical Criteria for the owners thereof. I understand that the City of
FT. Collins does not and will not assume liability for drainage facilities designed by others.
1
(Affix Seal)
1
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DIRANVAGE ]AIVESTIGATION
FOR
WART PLAZA RETAIL SHOPS
FT. COLLINS, COLORADO
FHP Job No.: 97-017
PREPARED FOR:
Southwestern Production Corporation
1675 Larimer Street
Suite 720
Denver, CO 80202
Attn: Thomas Oldenburg
PREPARED BY:
CONSULTING ( ENGINEERING
'LC
x7ut Yates Drives Sune 220 Phone: 303- 87-0696
W cstininster_ CO 801)30 FAX 30 3-387-0685
Attn: Aaron Thompson
December 3, 1997