HomeMy WebLinkAboutDrainage Reports - 05/06/1996Find cr vsd Reps
PROPERTY OF r VVVV a; 15
FORT CODUNs
FINAL
DRAINAGE REPORT
FOR
CARRABBA'S ITALIAN GRILL
in
2, OAKRIDGE BLOCK ONE, THIRD FILING
FORT COLLINS, COLORADO
Drexel Barrell
M
Engineers/Surveyors
Incorporated
Boulder,
Colorado Springs
4840 Pearl East Circle
Suite 114
Boulder, Colorado 80301
303 4424338
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FINAL
DRAINAGE REPORT
FOR
CARRABBA'S ITALIAN GRILL
in
LOT 2, OAKRIDGE BLOCK ONE, THIRD FILING
FORT COLLINS, COLORADO
Prepared For:
Carrabba's Italian Grill, Inc.
5100 W. Kennedy Blvd.
Suite 560
Tampa, Florida 33609
Prepared By:
Drexel Barrell
4840 Pearl East Circle, Suite 114
Boulder, Colorado 80301
Date Prepared:
January 19, 1996
Job No. E-4719
1
Drexel Barrell
�T\
1
tEngineers/Surveyors
March 6, 1996
Incorporated
'Boulder,
Matthew Fater
Colorado Springs
Stormwater Utilities Department
Pearl East Circle
P.O. Box 580
'4840
suite 114
Fort Collins, Colorado 80522
Boulder, Colorado 80301-2475.
Dear Mr. Fater,
'
303 4424338
We are pleased to submit the following Final Drainage and Erosion Control
Report for your review. The proposed site is the Carrabba's Italian Grill
located in Lot 2, Oakridge Block One, Filing No. Three. The following
report addresses the proposed development and resulting drainage and
erosion control measures.
All drainage concepts and calculations comply with the City of Fort Collins
Standard Criteria.
' Thank you for your time and consideration.
' Sincerely,
65� 0Q06
Debbie Klisis
vi wed,by, �.
I 1 � Vl I Ar
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PROJECT LOCATION
1
EXISTING SITE CONDITIONS
I
DRAINAGE CRITERIA
1
PROPOSED DEVELOPMENT AND DRAINAGE
I
EROSION CONTROL
2
CONCLUSION
3
REFERENCES
4
APPENDIX
5-11
Vicinity Map
5
Developed Runoff Calculations
6
Erosion Control Calculations ,
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FINAL
DRAINAGE REPORT
FOR
CARRABBA'S ITALIAN GRILL
in
LOT 2, OAKRIDGE BLOCK ONE, THIRD FILING
FORT COLLINS, COLORADO
' PROJECT LOCATION `
The proposed development is located west of Wheaton Drive between Harmony Road and Oakridge
Drive. Access to the site is through a joint entrance with the Harmony Medical Center,
' approximately 300 feet west of Wheaton Drive on Oakridge Drive. The parcel is located in the NW
1/4 of Section 6, T6N, R68W of the 6th P.M.
' EXISTING SITE CONDITIONS
' The existing site is grass covered land, which was previously graded, with a slope of 1 % to 2% to
the southeast. Offsite runoff from the north is cut off by Harmony Road. Runoff from the site
historically flows southeast to McClellands-Mail Creek Drainageway. Drainage then continues east,
eventually reaching the Cache Le Poudre River.
' No springs or irrigation ditches are located on the site. The proposed development lies within the
moderate rainfall erodibility zone and the moderate wind erodibility zone per the City of Fort Collins
Zone Maps. The site does not lie within the 100-year floodplain.
DRAINAGE CRITERIA
Runoff was calculated using the Rational Method for the 10- and 100-year storms. The plan and
report are designed in accordance with the City of Fort Collins "Storm Drainage Design Criteria and
Construction Standards".
1
PROPOSED DEVELOPMENT AND DRAINAGE
The proposed development consists of a sit-down restaurant and associated parking lot and landscape
improvements. The site is planned to fit on the lot without, disturbing existing conditions at the site
boundaries.
' The overall site drainage patterns were previously determined by drainage studies for Oakridge
Block One P.U.D., Filings 2 & 3. See references following the report. These drainage patterns are
closely maintained in the proposed development. The site uses existing detention ponding which
was constructed with the adjacent lot developments.
For purposes of this study, the site is divided into four drainage basins, "A" through "D". Basins "A"
and "B" constitute the primary developed portions of the site.. Runoff is designed to flow on the
surface, in swales and in curb and gutter, to offsite detention provided by the overall development..
The western 0.38 acres of the site, Basin "A", drains across the western boundary into Oakridge
Block One, Third Filing, which is the Marriot Hotel development, where detention ponding is
' provided for this basin. Basin "A" includes a minor change in the basin boundary from the previous
drainage study, which slightly increases the area of Basin "A" and decreases the area of Basin "B".
See the calculations in the appendix for further detail. Basin A includes two sub -basins, "Al" and
' A21f, which are created by a high point in Basin "A". Basin "Al" drains to the north around the
Marriot Hotel and Basin "AT' drains to the south around the hotel. Flows from both sub -basins
. combine at the existing detention pond.
The eastern 0.66 acres of the site, Basin "B", drains across the east boundary into Oakridge Block
One, Second Filing, which is the Harmony Medical Center development, where detention ponding
is also provided for this basin.
' Basin "C" consists of a small, 0.04 acre, landscaped area on the south end of the project along
Oakridge Drive. This basin will drain over the curb into Oakridge Drive and flow east along the
curb flowline to a curb inlet at Wheaton Drive.
' Basin "D" is a 0.33 acre landscaped buffer along Harmony Road on the north end of the project.
This area will drain in a broad grass lined swale east across the eastern property line to a detention
pond in Oakridge Block One, Second Filing.
To determine detention requirements, the runoff coefficients, or "C" values, for the site were
' calculated and compared to the values calculated in the adjacent site drainage studies. The values
for the proposed development are generally similar to the previously calculated values. The
difference in "C" values for Basin "A" is negligible. Basin "B" shows a difference in "C" value of
0.72 to 0.86. This results in a slight increase in detention ponding on the Harmony Medical Center
site due to the change in "C" values. The additional ponding amounts to 580 cubic feet, which is
' equivalent to a 1/2" rise in the 100-year water surface elevation of the pond.
The site lies within the moderate rainfall erodibility zone and the moderate wind erodibility zone.
Per the City of Fort Collins Erosion Control Reference Manual for Construction Sites, the erosion
control standards have been calculated. Based on existing slopes of 1.5%, the performance standard
was calculated to be 78.8%. With erosion control practices in place during construction, the net
effectiveness is 93.2%, which is more than existing conditions. Therefore, the erosion control plan
will meet the City of Fort Collins requirements.
' In order to adequately reduce the amount of erosion during construction, several measures are
proposed based on the erosion control calculations found in the appendix. A silt fence will be
constructed at the site perimeter, Basins "A", "B" and "C", to contain soil erosion and wind erosion.
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All disturbed areas to be paved, will be roughened after overlot grading. All landscape areas will
be planted with sod after final grading has occurred. These practices ensure control of both wind
and rainfall erosion to disturbed areas.'- With these erosion control practices, the proposed
construction area will not exceed historic erosion rates while the ground is disturbed. Once the grass
is established in the landscape areas and all paving is complete, the silt fence can be removed from
the site perimeter.
CONCLUSION
The design and all calculations conform to the City of Fort Collins Criteria. No downstream sites
will be adversely impacted by this development and historic drainage patterns will be maintained.
The development closely follows intended use and drainage pattterns as previously approved with
adjacent properties. Runoff from all disturbed areas will be controlled with adequate erosion control
practices during construction until the disturbed areas are either paved or have established vegetative
cover.
Written by: Reviewed by:
7>jok%� 4 4 06W
Debbie Klisis, E.I.T.
(4719fdr.wpd)
John Common. P.E.
1
1. City of Fort Collins Storm Drainage Design Criteria and Construction Standards.
2. "Final Drainage and Erosion Control Study for Oakridge Business Park, Block One, Filing 2,
Fort Collins, Colorado", dated September 2, 1994, prepared by RBD, Inc. Engineering
Consultants.
3. "Final Drainage and Erosion Control Study, Oakridge Block One P.U.D., Third Filing, City
of Fort Collins", dated December 9, 1994, prepared by RBD, Inc. Engineering Consultants.
APPENDIX
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c/i
HORSETOOTH RD.
PROPOSED
CARRABBA'S
ITALIAN GRILL
SITE -1,,,
HARMONY ROAD
t,_i
OAKRIDGE DR
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VICINITY MAP
N.T.S.
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Developed Runoff
Project: Lot 2 Oakridge Block One PUD, Third Filing
Job #: E4719
Date: 3/6/96
Basin: A Area (Ac. 0.38)
Basin: Al Area (Ac. 0.17)
Runoff Coefficient. Runoff C
Surface
Area (Ac.)
%Area
10yr.
100Yr.
10Yr.
100yr,
Roof
0
0
0
0
Pavement
0.11
64.7
0.95
1.00
0.61
0.65
Landscape
0.06
1 35.3
0.20
0.25
0.07
0.09
Basin: A2
Runoff Coefficient.
Composite C. 0.69 U.14
Area (Ac. 0.21
Runoff o/)' C I
Surface
Area (Ac.)
%Area
IOYr.
100yr.
I Joyr.
100Yr.
Roof
0
0
0
0
Pavement
0.27
128.6
0.95
1.00
1.22
1.29
Landscape
0.11
52.4
0.20
0.25
0.10
0.13
Time of Concentration:
Assume 5 min.
Intensity: From: FIGURE 3-1
I10Yr I100yr
5.65 8.00
Rainfall. Q=((CI *Al)+(C2*A2)) *I
Q1o= 2.23
Qloo= 3.38
Composite C. 1.33 1.42
Drexel Barrell and Company
4719RO.XLS
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Storm Water Detention
CITY OF FORT COLLINS
100 Year Storm
FAA Method'
Project: Lot 2 Oakridge Block One PUD, Third Filing
Job #: E4719
Date: 1 /12/96
AREA (AC.) 0.
100 YR C 0.72
Q OUT (CFS) 32
VOLUME
VOLUME
REQUIRED
TIME
INTENSITY
IN
OUT
STORAGE
(MIN)
(INIMR)
(CF)
(CF)
(CF)
5
9.00
1,283
396
887
10
7.20
2,053
792
1,261
15
6.00
2,566
1,188
1,378
20
5.20
2,965
1,584
1,381"
25
4.60
3,279
1,980
1,299
30
4.15
3,550
2,376
1,174
40
3.50
3,992
3,168
824
50
3.00
4,277
3,960
317
60
2.60
4,448
4,752
(304)
70
2.30
4,590
5,544
(954)
80
2.05
4,676
6,336
(1,660)
90
1.85
4,747
7,128
(2,381)
100
1.70
4,847
7,920
(3,073)
110
1.56
4,893
8,712
(3,819)
120
1.44
4,927
9,504
(4,577)
130
1.32
4,893
10,296
(5,403)
Drexel Barrell and Company 4719FAA.XLS 1 /12/96
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Developed Runoff
Project: Lot 2 Oakridge Block One PUD, Third Filing
Job #: E4719
Date: 3/6/96
Basin: C
Area (Ac.): 0.04
Runoff Coefficient:
Runoff C
Surface
Area (An)
%Area
10Yr.
100Yr.
10Yr.
100Yr.
Roof
0.00
0.0
0.00
0.00
Pavement
0.00
0.0
0.00
0.00
Landscape
0.04
100.0
0.20
0.25
0.20
0.25
Time of Concentration:
Assume 5 min.
Intensity: From: FIGURE 3-1
IIOYr I100Yr
5.65 8.00
Rainfall., Q=C*I*A WS)
Q10= 0.05
Q100= 0.08
Composite C. 0.20 0.25
Drexel Barrell and Company 4719RO.XLS
Developed Runoff
Project: Lot 2 Oakridge Block One PUD, Third Filing
Job #: E4719
Date: 3/6196
Basin: D
Area (Ac.): 0.33
Runoff Coefficient.
Runoff C
Surface
Area(Ac.)
%Area
Joyr.
100yr.
IOYr.
100Yr.
Roof
0
0
0
0
Pavement
0.03
9.1
0.95
1.00
0.09
0.09
Landscape
0.30
90.9
0.20
0.25
0.18
0.23
Composite C: U.Z 1 IU.3[
Time of Concentration:
Assume 5 min.
Intensity: From: FIGURE 3-1
I10Yr I100yr
5.65 8.00
Rainfall: Q--C*I*A (cfs)
Q1o= 0.50
Q1oo= 0.84
Drexel'Barrell and Company 4719RO.XLS
RUNOFF SUMMARY
Project. Lot 2 Oakridge Block One PUD, Third Filing
Job #: E4719
Date: 3/6/96
BASIN
AREA
C l0yr
C 100yr
Q 10yr
Q 100yr
A
0.38
0.73
0.78
1.57
2.38
B
0.66
0.81
0.86
3.03
4.56
C.
0.04
0.20
0.25
0.05
0.08
D
0.33
0.27
0.32
0.50
0.84
Time of Concentration:
Drexel Barrell and Company
.. 4719RO.XLS
Composite C:
Storm Water Detention
CITY OF FORT COLLINS
100 Year Storm
FAA Method
Project: Lot 2 Oakridge Block One PUD, Third Filing
Job #: E4719
Date: 1 /12/96
AREA (AC.)
100 YR C 086
Q OUT (CFS)
VOL UME ,
TIME INTENSITY IN
(MIN) (INIHR) (CF)
5 9.00 1,533
10 7.20 2,452
15 6.00 3 065
'
20
5.20
3,542
25
4.60
3,916
'
30
40
4.15
3.50
4,240
4,768
50
3.00
5,108
60
2.60
5,313
70
2.30
5,483
80
2.05
5,585
90
1.85
5,670
'
100
1.70
5,790
110
1.56
5,844
120
1.44
5,885
130
1.32
5,844
Drexel Barrell and Company
4719FAA.XLS
VOLUME
REQUIRED
OUT
STORAGE
(CF)
(CF)
396
1,137
792
1,660
1,188
1,877
1,584
1,958-
1,980
1,936
2,376
1,864
3,168
1,600
3,960
1,148
4,752
561
5,544
(61)
6,336
(751)
7,128
(1,458)
7,920
(2,130)
8,712
(2,868)
9,504
(3,619)
10,296
(4,452)
1 /12/96
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Developed Runoff
Project., Lot 2 Oakridge Block One PUD, Third Filing
Job #: E4719
Date: 3/6/96
Basin: B
Area (Ac.): 0.66
Runoff Coefficient:
Runoff C
Surface
Area (Ac.)
%Area
Joyr.
100Yr.
IOYr.
100yr.
Roof
0.14
21.2
0.95
1.00
0.20
0.21
Pavement
0.40
60.6
0.95
1.00
0.58
0.61
Landscape
0.12
18.2
0.20
0.25
0.04
0.05
Time of Concentration:
Assume 5 min.
Intensity: From: FIGURE 3-1
Iloyr I100Yr
5.65 8.00
Rainfall. Q=C*I*A (cfs)
Q10= 3.03
Q1oo= 4.56
Composite C. 0.81 0.86
Drexel Barrell and Company
4719RO.XLS
Historic Runoff
Project., Lot 2 Oakridge Block One PUD, Third Filing
Job #: E4719
Date: 1/11/96
Basin: B
Area (Ac.): 0.66
Runoff Coefficient:
Surface
Area (Ae)
%Area
10Yr.
100Yr.
10yr.
100Yr.
Roof
0.00
0.0
0.95
1.00
0.00
0.00
Pavement
0.00
0.0
0.95
1.00
0.00
0.00
Landscape
0.66
100.0
0.20
0.25
0.20
0.25
Time of Consentration:
Assume 5 min.
Intensity: From:
IIOYr 1100Yr
5.65 8.00
Rainfall. Q=C*I*A (cfs)
Q10= 0.75
Q1oo= 1.32
Composit C. 0.20 0.25
Drexel Barrell and Company
4719HRO.XLS
1/12/96
RAINFALL PERFORMANCE STANDARD EVALUATION
I
MARCH1991 B-14 DESIGN CRITERIA
EFFECTIVENESS CALCULATIONS
PROJECT: 6loca• G-4-1)g STANDARD FORM B
COMPLETED BY: DATE: I�11�`1(c
Erosion Control C-Factor P-Factor
Method Value Value Comment
Gr�,�,12ed.s�'a N1vlcL (;,D10 1, oO !°% Fv5`/, snafu.
QovS l-.a rigid ,Sur . c2. 1.00 D , 90
,so-2 Crass 0.01 1 • 00
Sfra.V-) kjar(i1.00 —._D, S0 C4Ccrs'v�c'Z�. �ni�-avCe LC4s,J r1r
1,00 O•SO
P 5 Y Pa Je w�c v�r p. O 1 1.00
_"-
a I; 4v G+ass �, c I ol° a"l a .;n (c7,'n 8A
MAJOR PS SUB AREA
BASIN ($) BASIN (Ac) CALCULATIONS
s1� �g• v �•3 V �^6lSCa C :?rfc 0.11
U So
L0.0lti`..If 4 D.01a
Pf'QLTCr = ( I,00 (0.2-7 } 1.0 0.39 KO.SD
EFF 059)Yloo= 97.511-
g d•io� (� ASCc �cre4= O.IZ>� �CaJCv Ev.T= G 40°�
FG(�p�=-t.0,01 [ 0, )7- .0 0.4 -4 1,0 D,14� "�• Ic(o
= 0 , 25
P.Fa� r=(1,DO"040 1.0,�0.1Z.)'D•5Z 0.So
o.SO) 11;co = g-1.5/°
C, 0.04 (.'� ci5[� �r��s O.CL F�.c;So{
(c oq 1 p.o1 )7D.o4
o of
g0 0
D 0. S .3 c r.-ems - O.3o EX. Po `1�w: = 0.c3
(y.Y ct .
p r Fid. ?r+Fa = o. CCo « Sod Ce=o.o1 a=I.
c'✓4 C. c=l e�-r e.55 - D, Z�ar. �-7:j'l4 of ba
(1• 03 0. 24 + P. 0 I K C. G + O •o lx o.03�= 0. 3
P Face i l .O x 0, LQ, 4 1.O 1 0 CV - 6.z0 � 0. _O
0.
' MARCH 1991 B•15 DESIGN CRITERIA
EFFECTIVENESS CALCULATIONS
PROJECT: '� STANDARD FORM B
,, r aLiaba S F+ Co (( , v: g - E 41(9
COMPLETED BYO DATE: 1 11'7 / 9 (.,
Erosion -Control C-Factor P-Factor
Method Value Value Comment
r�
MAJOR
PS
SUB
AREA
BASIN
($)
BASIN
(Ac)
CALCULATIONS
°Vo
9 9. r 0. 04
��o
Q r7?.f ��r..-.s �. ✓O r
7 6. U
J
MARCH 1991 8.15 DESIGN CRITERIA
CONSTRUCTION SEQUENCE
1
PROJECT: rfA 17�
r
S - t--{ I,.�S
E' g, I I
STANDARD FORM C
SEQUENCE FOR 19 9 ONLY COMPLETED BY:
D
DATE: IIn
Indicate by use of a bar line or symbols when
erosion control measures will be installed.
Major modifications to an approved schedule
approval by the City Engineer.
may require submitting a
new schedule for
YEAR
r
MONTH
OVERLOT GRADING
WIND EROSION CONTROL
Soil Roughening
Perimeter Barrier
Additional Barriers
Vegetative Methods
Soil Sealant
Other
,RAINFALL EROSION CONTROL
STRUCTURAL;
Sediment Trap/Basin
Inlet Filters
Straw Barriers
Silt Fence Barriers
Sand Bags
Bare Soil Preparation
' Contour Furrows
Terracing
Asphalt/Concrete Paving
' Other
VEGETATIVE:
Permanent Seed Planting
Mulching/Sealant .
Temporary Seed Planting
Sod Installation
Nettings/Hats/Blankets
Other
RUCTURES: INSTALLED BY
GETATION/MULCHING CONTRACTOR
�TE SUBMITTED
1
MAINTAINED BY
APPROVED BY CITY OF FORT COLLINS ON
IMARCH1991
8.16
DESIGN CRfTERIA
1
Erosion Control Cost Estimate
'
for
Carrabba's Italian Grill
'
Ft. Collins, Colorado
March 5, 1996
Unit
'
Description Unit Quantity
cost
Amoun
'
Method 1: revegetate site
Native Grasses Acre 1.07
$
650.00
$
695.50
'
+ Contingency (50%)
$347.75
'
TOTAL
$12043.25
'
Method 2: Temporary Erosion Control
Overlot Grading CY 870
$
2.50
$
2,175.00
'
Soil Roughening SY 1245
$
0.25
$
311.25
- Proposed Landscape Areas
'
Crimped Straw Mulch SY 3153
$
0.10
$
315.30
- Proposed Paved Areas
Silt Fence LF 945
$
2.00
$
1,890.00
'
Vehicle Tracking Control EA 1
$1,000.00
$
1,000.00
Sediment Trap EA 2
$
400.00
$
800.00
'
Subtotal
$
6,491.55
+ Contingency (50%)
$3,245.78
'
TOTAL
$ 9,7 3 T3-3-1 USE
'
(I:IPROJIENGIE4719ICOSTS14719COST.XLS)
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