HomeMy WebLinkAboutDrainage Reports - 07/10/2014MARTIN MARTIN
CONSULTING ENGINEERS
June 12, 2014
Revised July 2, 2014
Mr. Wes Lamarque
Stormwater Engineer
City of Fort Collins
281 North College Avenue
Fort Collins, CO 80524
City of Ft. Collins Approved Plans
Approved By
Date
Re: Avago Technologies — Building 4 West Annex Expansion and Site Development Drainage Report, June 12, 2014
Revision
Martin/Martin, Inc Project No.: 13.0688
Dear Mr. Lamarque,
This letter serves to inform you of the proposed changes to the approved "Avago Technologies — Building 4 West Annex
Expansion and Site Development Drainage Report" by Martin/Martin, Inc. dated May 21, 2013. Specifically, the revised
drainage report with a date of June 12, 2014 addresses the following revisions:
• The size of Basin Al has been increased to account for the increase in proposed roof area for the Building 4
West Annex Expansion Building.
• Basin Bl (previously landscaped area) has been eliminated.
• Basin B2 boundary and overall imperviousness has been updated.
• Basin Cl overall imperviousness has been decreased with the proposed removal of a portion of the existing
asphalt parking lot. The removal of the asphalt parking lot will offset the increased overall site imperviousness
due to the addition of roof area to Basin Al.
• The resulting overall site imperviousness and composite "C" factors remain unchanged from the approved
report dated May 21, 2013. The site imperviousness is 26% and the composite "C" factor is 0.43. The revised
"Hydrologic computations— composite c-factor compliance" page taken from the revised drainage report
dated June 12, 2014 is attached to this letter for reference. This condition has been accomplished by removing
existing parking lot areas for new building and paved areas.
• Hydraulic Calculations were revised to reflect updated flows per the revised rational method calculations.
• Maximum flooding heights were revised to reflect updated hydraulic calculations.
Please do not hesitate to call at 303.431.6100 or email at bsmith@martinmartin.com or pbuckley@martinmartin.com
should you have any questions or concerns.
Sincerely,
Bret M. Smith
EIT II
MARTIN/MARTIN, INC
12499 WEST COLFAX AVENUE
LAKEWOOD. COLORADO 80215
MAIN 303.431-6100
MART{NMARTIN.COM
Peter Buckley, PE
Senior Project Manager
HYDROLOGIC COMPUTATIONS -
COMPOSITE C-FACTOR COMPLIANCE
PROJECT INFORMATION
PROJECT NAME: BLDG 4 EXPANSION
PROJECT #: 1 MARTIN / M RTI N
6/17/2 aI DATE: 6/17/2014 CONy LTIN• [N04Nf906
BLDG 4 REPORT APPROVED BASINS WITHIN PROPOSED DEVELOPMENT
Basin Impervious Pervious A, Imp A, Pery A, total �, Imp %Pery Composite "C"
C. C. ac ac ae
4
0.95
0.251
0.19
1.441 1,67 11
86 0.32
5
0.95
0.25
0.12
0.65
0.77, 16
84
0.36
6
0.95
0.25
0.00
6.75
6.75 0
100
0.25
14
0.95
0.25
0.25
0.18
0.43
58
421
0.66
17
0.95
0.25
0.56
1.40
1.96
29
711
0.45
18
0.95
0.25
0.05
0.85
0.90
6
94
0.29
19
0.95
0.25
0.10
2.75
2.85
4
96
0.27
20
0.95
0.25
0.08
0.30
_
0.38
_
21
790.40
22
0.95
0.25
0.79
0.22
1.01
78
22 0.80
22A
0.95
0.25
0.72
0.15
0.87
83
17 0.83
23
0.95
0.25
0.49
0.25
0.74
67
34 0.72
24
0.96
0.25
0.56
0.07
0.63
89
11 0.87
24A
0.95
0.25
0.35
0.02
0.37
95
5 0.91
24B
0.95
025
0.25
0.06
0.31
81
19 0.81
25
0.95
0.25
0.48
0.17
0.65
74
26 0.77
_ 25A
0.95
0.25
0.42
0.12
0.54
78
22 0.79
26
0.95
0.25
0.27
0.03
0.30
90
10 0.88
27
0.95
0.25
0.04
0.001
0.04
100
0 0.95
36
0.95
0.25
0.16
0.17
0.33
48
52 0.59
37
0.95
0.25
0.29
0.04
0.33
88
12 0.87
_ 38
0.95
0.25
0.23
0.09
0.32
72
28 0.75
40
0.95
0.25
0.05
0.01
0.06
83
17 0.83
39
0.95
0.25
0.00
2.02
0.00
100
SRE
1
6.49
17.74
24.23
27
73'
BLDG 4 WEST ANNEX EXPANSION AND SITE DEVELOPMENT PROJECT
BASINS
Impervious Pervious A, Imp A, Pery A, total o
Basin (ac) ac ac / Imp / Pery Composite "C"
Al
0.95
0.251
0.83
0.00
0.83
1001
0
0.95
A2
0.95
015
0.05
020
015
19
81
6.38
A3
0.95
0.25
0.76
0.00
0.76
100
0
0.95
_
A4
0.95
0.25
0.07
2.18
2.26
3
97
0.27
AS
0.95
025
0.31
0.00
0.31
100
0
0.95
A6
0.95
0.25
0.09
1.70
1.79
5
95
0.29
A7
0.95
025
0.45
2.06
2.51
18
82
0.38
AS
0.95
0.25
0.19
0.03
0.22
88
12
0.86
A9
0.95
025
0.13
0.03
0.15
83
17
0.83
A10
0.95
0.25
0.16
0.03
0.19
86
14
0.95
All
0.95
025
0.22
2.18
2.40
9
911
0.31
B2
0.95
015
0.30
0.66
0.95
31
69
0.47
B3
0.95
025
0.46
1.35
1.81
25
75
0.43
B4
0.95
0.25
0.23
0.32
0.55
42
58
0,54
B5
0.95
025
0.07
0.19
025
27
73
0.44
B6
0.95
025
0.19
0.60
0.79
24
76
0.42
B7
0.95
0.25
0.19
0.471
0.66
28
72
0.45
Cl
0.95
025
0.75
0.27
1.02
741
26
0.77
C2
0.95
025
0.05
1.57
1.62
3
97
0.27
C3
0.95
025
0.29
1.68
1.97
15
Lo
0.35
C4
0.95
0.25
0.00
0.69
0.69
0
100
0.25
OS -A
0.95
025
0.57
1.68
225
26
74'
0.43
SITE
E
6.35
17.89
24.24
Ir 26
74 0.43
1
J
B. SMITH
12:48 PM6/17/2014 APPROVED BASIN COMPOSITE -MINOR AMENDMENT.xIs MARTIN/MARTIN INC.