HomeMy WebLinkAboutDrainage Reports - 06/27/20141 Cityaf Ft: Collins prov tans
Approved By
Date' — —
' AVAGO TECHNOLOGIES -BUILDING 4 WEST
' ANNEX EXPANSION AND SITE
DEVELOPMENT
DRAINAGE REPORT
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CITY OF FORT COLLINS, COLORADO
REV, JUNE 129 2014 (MINOR AMMENDMENT SUBMITTAL 1)
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REV, MAY21s, 2013 (APPROVED REPORT)
MARCH 25T' , 2013
MARTINIMARTINPROJECT NO. 13.0091
PREPARED FOR: AVAGO TECHNOLOGIES (APPLICANT)
4380 ZIEGLER ROAD
FORT COLLINS, CO 8025-9790
(970)288-0344
PAUL TANGUAY
PREPARED BY: MARTIN/MARTIN, INC.
12499 WEST COLFAX AVENUE
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LAKEWOOD, COLORADO 80215
PHONE: (303) 431-6100
PRINCIPAL IN CHARGE: MATTHEW B. SCHLAGETER, P.E.
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PROJECT MANAGER: PETER S. BUCKLEY, P.E.
PROJECT ENGINEER: BRET M. SMITH, E.I.T. II
TABLE OF CONTENTS
A. INTRODUCTION..................................................................................... 2
Al. LOCATION............................................................................................................. 2
AZPURPOSE................................................................................................................ 3
A3. EXISTING CONDITIONSAND PROPOSED DEVELOPMENT ...................... 3
B. DRAINAGE BASINS................................................................................ 4
BI. MAJOR DRAINAGE BASIN DESCRIPTION..................................................... 4
B2. SUB-BASINDESCRIPTIONS...............................................................................
S
B3. SWMM MODEL COMPLIANCE..........................................................................
S
C. DRAINAGE DESIGN CRITERIA........................................................... 8
Cl. REFERENCES.......................................................................................................
8
C2. HYDROLOGIC CRITERIA...................................................................................
8
C3. HYDRAULIC CRITERIA.......................................................................................
8
C4. VARIANCES FROM CRITERLA..........................................................................
9
D. DRAINAGE FACILITY DESIGN........................................................... 9
DI. GENERAL CONCEPT...........................................................................................
9
D2. SPECIFIC DETAILS...........................................................................................
10
E. STORMWA TER QUALITY....................................................................
14
F. CONCLUSIONS......................................................................................
18
Fl. COMPLIANCE WITH STANDARDS.................................................................
18
F2. SUMMARY OF CONCEPT..................................................................................18
LIST OF REFERENCES............................................................................19
G. APPENDIX.............................................................................................
20
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A. INTRODUCTION
A]. LOCATION
The Avago Technologies - Building 4 West Annex Expansion and Site Development
(hereafter referred to as "PROJECT") site is located on the Hewlett-Packard Campus
(hereafter referred to as "CAMPUS") in Lot 2 of the Preston -Kelley 2"d Subdivision,
found in the Southwest '/4 of Section 33, Township 7 North, Range 68 West of the 6d'
Principal Meridian, City of Fort Collins, County of Larimer, State of Colorado. The
PROJECT address is 4380 Ziegler Road. The overall site consists of 8.80 acres of
disturbed area. The overall area evaluated for the purposes of this drainage report consists
of 24.24 acres.
The overall CAMPUS is bound to the north by Hidden Pond Drive, to the east by the
Fossil Creek Drainage Ditch, to the south by East Harmony Road, and to the West by
Ziegler Road. The PROJECT site is bound to the north by an existing field and
Technology Parkway, to the east by the existing Hewlett Packard Building 4, to the south
by existing landscaped areas and an asphalt parking lot, and to the West by Technology
Parkway. Refer to the vicinity map below and in the Appendix.
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AZ PURPOSE
The following outlines the intent of this Compliance Drainage Report:
• Illustrate hydrologic compliance with the "Final Drainage and Erosion Control
Study for Hewlett-Packard Building 4" report produced by The Sear -Brown
iGroup dated March 22, 1999 (hereafter referred to as `BUILDING 4 REPORT").
Per an email dated 2/14/2013 from Wes Lamarque of the City of Fort Collins
Stormwater Utility Department, compliance with the BUILDING 4 REPORT
forms the basis of drainage design for the PROJECT. Refer to the Appendix for a
' copy of the email.
Hydrologic Compliance is illustrated in Section B3. SWMM COMPLIANCE of
this report
• Illustrate compliance with the Low Impact Design ("LID") policies for Water
Quality found in City of Fort Collins Municipal Code, Section 3.4.3 Water
Quality.
Compliance with the City's LID policies is illustrated in Section E.
STORMWA TER QUALITY of this report.
' • Quantitatively and qualitatively establish drainage design on the site.
A3. EXISTING CONDITIONSAND PROPOSED DEVELOPMENT
According to the "Geotechnical Engineering Report" produced by Terracon Consultants,
Inc., dated September 4, 2012, the existing soils consist of fill materials consisting of
sandy lean clay with various amounts of sand and gravel, and in -situ poorly graded sand
with gravel. Based on the results of borings, claystone bedrock is located at a maximum
depth of exploration of 39.7 feet. Groundwater was observed at a maximum elevation of
4982.6', and a minimum depth of 18' below existing grade. The soils on site are typically
SCS Type C Hydrologic Soils. A USDA web soil survey of the CAMPUS states that the
soils consist mostly of Nunn clay loam. A copy of the web soil survey is referenced in the
Appendix.
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The existing site topography generally slopes from west to east at approximately 0.7
percent. Native grasses or existing asphalt drives and parking cover a large majority of
the site.
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The proposed development will include the construction of an expansion to the existing
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Building 4, private asphalt and concrete drives, and utility infrastructure necessary to
service the proposed building. The footprint of the building expansion covers
approximately 82,000 SF. Additionally, drainage facilities designed to improve
Stormwater Quality are proposed for the site in accordance with Section 3.4.3 Water
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Quality of the City of Fort Collins Municipal Code.
B. DRAINAGE BASINS
Bl. MAJOR DRAINAGE BASIN DESCRIPTION
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The lies
CAMPUS entirely within the Fox Meadows Drainage Basin which is
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approximately bounded by Horsetooth Road on the north, Harmony Road on the south,
the Cache de La Poudre River I-25
and on the east, and Lemay Avenue on the west. A
Master Plan for the Fox Meadows Drainage Basin was prepared by Resource
Consultants, Inc., in 1981. In this the CAMPUS is located Basin H.
master report, within
This area was studied again by Nolte and Associates in 1990 when a master drainage plan
was prepared for the CAMPUS (this report hereafter referred to as "MASTER"). The
MASTER did not alter any of the assumptions or conclusions which were made in the
Fox Meadows Master Drainage Plan.
The majority of the proposed PROJECT site discharges north to a regional channel. This
regional channel located along County Road 9 and the north boundary of the CAMPUS
was recommended in the MASTER report and was designed and built with the Hewlett-
Packard Building 5 project. The channel was designed for the 100-year storm and
discharges to the North Pond on the CAMPUS. Stormwater detention and water quality
treatment for the CAMPUS is provided by four on -site ponds located in the SE corner of
the CAMPUS. These ponds are constructed as Extended Detention Basins (EDBs). The
North Pond is a dry bottom pond. The South Pond, Southwest Pond, and Dam Pond are
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wet ponds. Added water quality benefits are gained via the regional channel along the
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north side of the campus which is constructed as a Grass Swale. This channel provides
initial water quality treatment to the north -flowing basins in the PROJECT area prior to
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treatment in the CAMPUS ponds.
' B2. SUB -BASIN DESCRIPTIONS
The northern portion of the PROJECT site is located within Basin 32 of the MASTER
report. Basin 32 discharges to a regional channel located along County Road 9 and the
north boundary of the CAMPUS. The regional channel was recommended in the
MASTER report and was designed and built with the Hewlett-Packard Building 5
project. The channel was designed for the 100-year storm and discharges to the north
regional detention pond on the CAMPUS. It was modified during Building 4 construction
to ensure that uncontrolled spilling, into the Fossil Creek Ditch from the regional
' detention ponds does not occur during the 100-year storm.
A portion of the southern end of the PROJECT site is located within Basin 34 of the
MASTER. This Basin discharges south and travels east via storm sewer to a regional
detention pond located in the southeast portion of the CAMPUS.
1 B3. SU MM MODEL COMPLIANCE
1 The PROJECT site is designed in order to maintain the same amount of pervious area
specified in the BUILDING 4 REPORT. An analysis comparing proposed development
with the development specified in the BUILDING 4 REPORT confirms that there is no
net increase in impervious area for the PROJECT site. Additionally, the City requested
' that the calculated composite "C" factor remain in compliance with the BUILDING 4
REPORT. The allowable composite "C" factor within the proposed development is 0.44
per the BUILDING 4 REPORT. The proposed development will result in a net composite
"C" factor of 0.43 (indicating a slightly less percent imperviousness than the allowable
' imperviousness from the BUILDING 4 REPORT).
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IBLDG 4 REPORT APPROVED BASINS WITHIN PROPOSED
DEVELOPMENT
Imperviou Pervious A, Imp A, Pery A, total oo „
„ eC„ Composit
sC„ „C„ (ac) (ac) (ac) /o Basin Imp /o Pery
4
0.95
0.25
0.19
1.44
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
42
0.66
17
0.95
0.25
0.56
1.40
1.96
29
71
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
79
0.40
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
0.95
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
0.25
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
0.00
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
0
100
0.25
STI'E
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£,
6.49
17.74
24.23
27
73
0.44
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BLDG 4 WEST ANNEX EXPANSIONAND SITE
DEVELOPMENT PROJECT BASINS
Impervious Pervious A, Imp A, Pery A, total % % Composite
Basin ,. ..
C C (ac) (ac) (ac) Imp Pery .. C
A 1 0.95 0.25
0.831
0.00
0.83
100
0
0.95
A2 0.95 0.25
0.05
0.20
0.25
19
81
0.38
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
A5 0.95 0.25
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 0.25
0.45
2.06
2.51
18
82
0.38
A8 0.95 0.25
0.19
0.03
0.22
88
12
0.86
A9 0.95 0.25
0.13
0.03
0.15
83
17
0.83
A10 0.95 0.25
0.16'
0.03
0.19
86
14
0.85
-
A l l 0.95 0.25
---------
0.22
- --'--
2.18
- -
2.40
----
9
--
91
- -0. -
31
132 0.95 0.25
0.30
0.66
0.95
31
69
0.47
133 0.95 0.25
0.46
1.35
1.81
25
75
0.43
134 0.95. 0.25
0.23
0.32
0.55
42
58
0.54
B5 0.95 0.25
0.07
0.18'
0.25
27
73
0.44
B6 0.95 0.25
0.19
0.60'
0.79
24
76
0.42
B7 0.95 0.25
0.19
0.47'
0.66
28
72
0.45
C 1 f 0.95 0.25
0.751
1.02
74
261
0.77
C2 1 0.95 0.25
0.05
1.57
1.62
3
97
0.27
C3 1 0.95 0.25
0.29
1.68
1.97
15
85
0.35
C4 0.95 0.25
0.00
0.69
0.69
0
100
0.25
OS -A 0.95: 0.25
0.57
1.68
2.25.
26
74
0.43
S ITE E
6.35
17.891
24.24
` 26
74
0.43
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C. DRAINAGE DESIGN CRITERIA
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C1. REFERENCES
Cl.l Jurisdictional
This drainage report has been prepared in compliance with the following criteria:
i) Article VII, Stormwater Utility, City of Fort Collins Municipal Code, latest
revision ("hereafter referred to as the "CRITERIA"),
ii) Section 3.4.3, Water Quality, City of Fort Collins Municipal Code, latest
revision, and
iii) "Urban Storm Drainage Criteria Manual' latest revision (hereafter referred to
as the "MANUAL").
C1.2 Drainage Studies, Outfall Systems Plans, Site Constraints
The proposed design is in accordance with the MASTER report and BUILDING 4
REPORT.
1 The site is part of the Fox Meadows Master Drainage Plan (Basin H).
C2. HYDROLOGIC CRITERIA
Design runoff is calculated using the rational method as established in the MANUAL.
The 100-year, one -hour point rainfall data is 2.86 inches per the CRITERIA. Composite
runoff coefficients are based upon a value of 0.95 for imperviousness areas, and 0.25 for
Ipervious areas in accordance with the BUILDING 4 REPORT.
C3. HYDRA ULIC CRITERIA
Final pipe sizes and water surface profiles have been calculated using the Bentley
StormCAD program, latest edition. During major storm events and storm sewer failure,
stormwater in Basin A will pond to an elevation of 4917.95 before spilling south into
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Basin B. Basin B will pond to an elevation of 4917.65 before spilling south following
existing drainage patterns. The extent of ponding is shown on the drainage plan.
C4. VARIANCES FROM CRITERM
No variances from the CRITERIA are requested at this time.
A DRAINAGE FA CILITY DESIGN
Dl. GENERAL CONCEPT
Dl.l Major On -Site Basins
Proposed Basin A includes the Building 4 Expansion roof, portions of the north access
drive extension, and existing native areas. Basin A discharges via a grass swale to a 24"
FES located at design point A7. From A7, flow continues northeast via storm sewer to
the regional channel. From the regional channel, runoff enters the CAMPUS North Pond,
which then flows into the South Pond, which then flows into the Dam Pond before
flowing off -site.
Basin B discharges south to existing storm sewer via a series of swales, a trench drain, a
Type C inlet, DIP Basin B includes loading dock,
proposed and storm pipe. the proposed
proposed access drive, and landscaped areas. On -site storm sewer conveys flow into the
CAMPUS Southeast Pond, flows into South Pond, flows into
which then the which then
the Dam Pond before flowing off -site.
Basin C discharges north via existing inlets and storm sewer to the regional detention
channel. Basin C enters the regional detention channel farther west (upstream) than Basin
A, and then flows downstream in the same manner as runoff from Basin A.
D1.2 Major Off -Site Basins
Basin OS -A consists of approximately 2.25 acres of existing landscaped area and
portions of an existing parking lot located south of the proposed PROJECT site. Basin
OS -A discharges southwest via overland flow and curb and gutter, following existing
drainage patterns.
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DZ SPECIFIC DETAILS
DZ I Basin A
Sub -Basin A 1 consists of approximately 0.83 acres of the proposed Building 4 Expansion
roof. Runoff from Sub -Basin A 1 discharges through a roof drain Iambs tongue into a rock
box at Design Point A The rock box is designed to improve downstream water quality
by promoting sedimentation and filtration. From the rock box, discharge enters a 3' wide
concrete channel which flows west via a sidewalk chase. From the concrete channel,
discharge enters a level spreader. Once runoff has overtopped the level spreader, sheet
flow occurs to Design Point A2 where runoff from Sub -Basin A 1 meets runoff from Sub -
Basin A2 in the proposed grass swale.
Sub -Basin A2 consists of approximately 0.25 acres of mostly landscaped area. Runoff
from Sub -Basin A2 sheet flows to Design Point A2, where discharge enters the grass
swale and meets runoff from Sub -Basin A1.
Sub -Basin A3 consists of approximately 0.76 acres of the proposed Building 4 Expansion
roof. Runoff from Sub -Basin A3 discharges through a roof drain lambs tongue into a rock
box at Design Point A3. The rock box is designed to improve downstream water quality
by promoting sedimentation and filtration. From the rock box, discharge enters a 3' wide
concrete channel which flows west via a sidewalk chase. From the concrete channel,
discharge enters a level spreader. Once runoff has overtopped the level spreader, sheet
flow occurs to Design Point A4 where runoff from Sub -Basin Al meets runoff from
Design Point A2 and Sub -Basin A4 in the proposed grass swale.
ISub -Basin A4 consists of approximately 2.26 acres of landscaped area and existing native
area. Runoff from Sub -Basin A4 sheet flows to Design Point A4, where discharge enters
the grass swale and meets runoff from Sub -Basin A3 and Design Point A2.
Sub -Basin A5 consists of approximately 0.31 acres of the proposed Building 4 Expansion
roof. Runoff from Sub -Basin A5 discharges through a roof drain Iambs tongue into a rock
box at Design Point A5. The rock box is designed to improve downstream water quality
by promoting sedimentation and filtration. From the rock box, discharge enters a 3' wide
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concrete channel which flows west via a sidewalk chase. From the concrete channel,
discharge enters a level spreader. Once runoff has overtopped the level spreader, sheet
flow occurs to Design Point A6 where runoff from Sub -Basin A5 meets runoff from
Design Point A4 and Sub -Basin A6 in the proposed grass swale.
Sub -Basin A6 consists of approximately 1.79 acres of landscaped area and existing native
area. Runoff from Sub -Basin A6 sheet flows to Design Point A6, where discharge enters
f the grass Swale and meets runoff from Sub -Basin A5 and Design Point A4.
Sub -Basin A7 consists of approximately 2.51 acres of landscaped area, existing native
area, and proposed concrete pavement. Runoff from Sub -Basin A7 discharges to Design
Point A7 via storm sewer. Runoff enters the storm sewer via a 24" FES located at the
downstream end of the grass swale, or one of two Type C Inlets located in the concrete
pavement. At Design Point A7, runoff from Sub -Basin A7 combines with runoff from
Design Point A6.
Sub -Basin A8 consists of approximately 0.22 acres of mostly paved area. Runoff from
Sub -Basin A8 enters existing storm sewer via an existing inlet at Design Point A8.
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Sub -Basin A9 consists of approximately 0.15 acres of mostly paved area. Runoff from
Sub -Basin A9 enters existing storm sewer via an existing inlet at Design Point A9.
Sub -Basin A 10 consists of approximately 0.19 acres of mostly paved area. Runoff from
Sub -Basin A 10 enters existing storm sewer via an existing inlet at Design Point A 10.
Sub -Basin A 11 consists of approximately 2.40 acres of mostly pervious area. Runoff
from Sub -Basin A 11 enters existing storm sewer via a series of proposed swales and area
inlets.
Runoff from Sub -Basins A8, A9, A 10, and A 11 combines with runoff from Design Point
A7 at Design Point A. From Design Point A, runoff enters the regional channel and flows
to the existing regional detention pond.
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D2.1 Basin B
Sub -Basin B2 consists of approximately 0.95 acres of landscaped area, existing native
area, and proposed pavement. Runoff from Sub -Basin B2 enters the storm sewer system
at Design Point B2 via a proposed 18" trench drain and Type C Inlet.
Sub -Basin B3 consists of approximately 1.81 acres of existing and proposed landscaping,
paved parking, and paved drives. Runoff from Sub -Basin B3 travels via an existing
concrete swale to Design Point B3 and combines with discharge from Design Point B2.
Sub -Basin B4 consists of approximately 0.55 acres of mostly landscaped area. Runoff
from Sub -Basin B4 enters storm sewer at Design Point B4 via an existing area inlet.
Sub -Basin B5 consists of approximately 0.25 acres of mostly landscaped area. Runoff
from Sub -Basin B5 enters the storm sewer system via an area inlet at Design Point B5
and combines with discharge from Design Point B4.
Sub -Basin B6 consists of approximately 0.79 acres of mostly landscaped area. Runoff
from Sub -Basin B6 enters the storm sewer system via an area inlet and combines with
runoff from Design Point B5 at Design Point B6.
Sub -Basin B7 consists of approximately 0.66 acres of mostly landscaped area. Runoff
from Sub -Basin B7 enters the storm sewer system via an area inlet and combines with
runoff from Design Point B6 at Design Point B7.
Runoff from Sub -Basins B4, B5, B6, and B7 combines with runoff from Design Point B3
at Design Point B. From Design Point B, runoff continues south and east to a regional
detention pond.
D2.1 Basin C
Sub -Basin Cl consists of approximately 1.02 acres of existing asphalt parking lot and
proposed landscaped area. Portions of the existing asphalt parking lot are proposed for
demolition. Runoff from Sub -Basin C1 discharges southeasterly via sheet now and curb
and gutter to an existing inlet at Design Point Cl. At Design Point Cl, runoff enters the
storm sewer system and flows north.
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Sub -Basin C2 consists of approximately 1.62 acres of proposed landscaped area which is
to be built in place of an existing parking lot which is to be demolished. Runoff from
Sub -Basin combines with runoff from Sub -Basin Cl at Design Point C2, an existing
storm sewer inlet. From Design Point C2, runoff flows north via existing storm sewer.
The demolition of portions of the existing asphalt parking lot within Sub -Basins C1 and
C2 is the main strategy used to maintain compliance with the imperviousness values and
composite "C" factor found in the BUILDING 4 REPORT.
Sub -Basin C3 consists of approximately 1.97 acres of existing native area and a portion
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of the eastern half of Technology Way. Runoff travels via sheet flow and curb and gutter
to an existing inlet at Design Point C3.
Runoff from Sub -Basin C3 combines with runoff from Design Point C2 at Design Point
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C. From Design Point A, runoff enters the regional channel and flows to the existing
regional detention pond.
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E. STORMWATER QUALITY
Water Quality is provided by the regional detention ponds located on the CAMPUS;
however, in accordance with City of Fort Collins Municipal Code, Section 3.4.3 Water
Quality, this development has followed Low -Impact -Design ("LID") principles in order
to increase the water quality for stormwater discharge from the developed site. The
following specific LID features are incorporated into the drainage design for this project:
Grass Swale: The site has been designed with an approximately 450' long grass
swale which has been designed in accordance with the Grass Swale Best
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Management Practice Fact Sheet and Design Spreadsheet from the MANUAL.
The Grass Swale will except and treat runoff from Sub -Basins AI-A7. The Grass
Swale will be a densely vegetated trapezoidal channel with low-pitched side
slopes and a relatively broad cross section which will convey flow in a slow and
shallow manner, thereby facilitating sedimentation and filtering while limiting
erosion. An underdrain system has been provided for the Grass Swale in order to
encourage infiltration and limit ponding.
Rock Box: Runoff from roof drains will discharge via Iamb's tongues at the
building face into one of five proposed rock boxes. Rock boxes are constructed of
a single CDOT Type D Inlet approximately 48" in height. Rock Boxes are
designed to facilitate sedimentation, provide minimal detention, and provide
energy dissipation for roof drain runoff. The Rock Box utilizes a layer of rip -rap
or cobble at its top in order to first slow down and dissipate roof drain flows.
Next, these flows filter down through approximately 3' of 1-2" crushed rock in
order to encourage sedimentation and filtration. An orifice plate mounted to the
front of the rock box provides for the slow discharge rate out of the rock box.
From the rock box outlet, runoff enters a concrete lined chase which directs runoff
towards another LID feature, the level spreader.
Level Spreaders have been incorporated into the drainage design in order to
provide another feature which encourages infiltration, and limits erosion by
limiting flow velocities and concentration. The level spreader functions by
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providing a small sedimentation basin (approximately 3" depth) for flows
discharging from the proposed concrete channels. This sedimentation basin
discharges over the 40' long level spreader at a constant elevation, thereby
creating sheet flow as runoff discharges towards the grass swale. This has the
added benefit of increasing infiltration during sheet flow, and limiting the erosive
1 potential of the runoff by spreading the discharge.
Grass Buffer. Downstream from the level spreaders, sheet flow runs through a
grass buffer before entering the grass Swale. Grass Buffers play an important role
in LID by enabling infiltration and slowing runoff. The Grass Buffer provides the
benefits of filtering sediment and trash; and reducing directly connected
' impervious area.
Nyloplast Sedimentation Basin / Sediment Trap: At the request of the City, a
' Nyloplast Sedimentation Basin has been installed at the downstream end of the
proposed Grass Swale in order to provide an additional means for sedimentation
before entering the storm sewer system. The Nyloplast Sedimentation Basin will
consist of a 24" Nyloplast Drainage Basin in a concrete collar. The Basin will
have 2' of sump in order to allow for settlement before runoff enters the storm
sewer system via the proposed 24" FES.
Multiple Roof Drains and Disconnecting Impervious Area (DCIA): The roof
drainage from the Building 4 Expansion has been purposely broken up into
multiple discharge points along the perimeter of the building in order to
disconnect impervious areas which lengthens runoff times of concentration and
allows for multiple localized areas for water quality treatment.
Permanent site stabilization will be provided through the installation and maintenance of
asphalt or concrete paving and permanent landscaping at the time of final site
development. Final stabilization will be achieved once a uniform vegetative cover has
been established with a density of at least 70-percent of pre -disturbance levels.
' 15
I
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I
Detention and water quality for the entire CAMPUS will continue to be provided in the
' regional water quality and detention ponds. Additionally, the LID features mentioned
previously will enhance the water quality of discharge from the PROJECT site.
11
1
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1.
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No Text
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F. CONCLUSIONS
Fl. COMPLIANCE WITH STANDARDS
The Drainage Report for the Avago Building 4 Expansion and Site Development project
has been prepared in compliance with the BUILDING 4 REPORT, MASTER,
CRITERIA, MANUAL, and the City of Fort Collins Municipal Code, Section 3.4.3
Water Quality. The proposed drainage design is consistent with both existing and
developed conditions.
'! F2. SUMMARY OF CONCEPT
Developed runoff will be collected and conveyed by a system of overland flow, grass
swales, concrete channels, and proposed and existing storm sewer. Runoff will ultimately
be conveyed to existing regional detention and water quality ponds located on the
1- CAMPUS. LID principles will improve the water quality for stormwater runoff from the
developed site. Development of the site will not adversely impact downstream properties
or drainage facilities.
I
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1,
I
18
I
I
LIST OF REFERENCES
1. "Updated Hydrology for the Fox Meadows Basin". Resource Consultants. 1987.
2. "Master Drainage Report for Hewlett-Packard Site". Nolte and Associates. 1990.
1 3. "City of Fort Collins Municipal Code". Latest revision
4. "Hewlett-Packard Building 5 Drainage Report". Sear -Brown Group. 1996.
5. "Hewlett-Packard Building 4 Drainage Report". Sear -Brown Group. 1999.
6. "Symbios Logic Site Development". Sear -Brown Group. 1997
7. "Detailed Hydraulic Study, Regional Detention Facilities, Hewlett-Packard Company".
Sears Brown Group. 2000.
8. "Geotechnical Engineering Report, Avago Technologies B4 West Annex". Terracon
' Consultants, Inc. September 4, 2012
I
!-
19
I
G APPENDIX
20
I
1
1
1
1
1
1
n
1
1
1
1
MAPS AND DESIGN AIDS
VICINITY MAP
RAINFALL DATA
USDA SOIL SURVEY
FEMA FIRMMETTE
CITYOF FORT COLLINS WATER QUALITYMUNICIPAL CODE
GRASS BUFFER BMP
GRASS SWALE BMP
' MAPS AND DESIGN AIDS - VICINITY MAP
t
1
1
1
1
I
1
1
GOO,gle earth miles'
km 1
I
MAPS AND DESIGN AIDS -RAINFALL DATA
I
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1
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Table RA-8
City of Fort Collins Rainfall Intensity--Duration-Frequenev Table for
Use with the Rational 'Method
Duration
%>
2-Year Intensih
(in1kri
10-1Wear Intensih
(MAO
100-Year Intensih•
OnIhr)
31
1.27
2.16
4.42
32
1.24
2.12
4.33
33
1.22
2.08
4.24
34
1.19
2.04
4.16
35
1.17
2
4.08
36
1.15
1.96
4.01
37
1.16
1.93
3.93
38
1.11
1.89
3.87
39
1.09
1.86
3.8
40
1.07
1.83
3.74
41
1.05
1.8
3.68
42
1.04
1.77
3.62
43
1.02
1.74
3.56
44
1.01
1.72
3.51
45
0.099
1.69
3.46
46
0.98
1.67
3.41
47
0.96
1.64
3.36
48
0.95
1.62
3.31
49
0.94
1.6
3.27
50
0.92
1.58
3.23
51
0.91
1.56
3.18
52
0.9
1.54
3.14
53
0.89
1.52
3.1
54
0.88
1.5
3.07
55
0.87
1.48
3.03
56
0.86
1.47
2.99
51
0.85
1.45
2.96
58
0.84
1.43
2.96
59
0.83
1.42 1
2.89
60 1
0.82
1.4 1
2.86
1
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MAPS AND DESIGN AIDS - FEMA FIRM I MAP SCALE 1" = 500*
Soo 101
3135000 FT
JOINS PANEL 0992
GRAND TETON PL
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PANEL 0994F
FLOOD INSURANCE RATE MAP
LARIMER COUNTY,
COLORADO
AND INCORPORATED AREAS
EL 994 OF 1420
MAP INDEX FOR FIRM PANEL LAYOUT)
N NITY NUMBER PANEL SUFFIX
COLONS, CITY OF 080102 0994 F
ER COUNTY 080101 0994 F
Notice to User: The Map Number shown below
hould be used when placing map orders; the
ommunity Number shown above should be
used on insurance applications for the subject
mmunity.
ZONE X vie"�—a.�F� MAP NUMBER
08069CO994F
EFFECTIVE DATE
�qND SE
DECEMBER 19, 2006
Federal Emergency Management Agency
This is an official copy of a portion of the above referenced flood map. It
was extracted using F-MIT On -tine. This map does not reflect changes
or amendments which may have been made subsequent to the date on the
title block. For the latest product information about National Flood Insurance
Program flood maps check the FEMA Flood Mao Store at www.msc.fema,ac
MAPS AND DESIGNAIDS - CITY OF FORT COLLINS WATER QUALITY
MUNICIPAL CODE
3.4.3 Water Quality
The development must comply with all applicable local, state and federal water quality standards, including, but not
limited to, those regulating erosion and sedimentation, storm drainage and runoff control, and the treatment of solid
wastes, and hazardous substances. Projects must be designed such that all runoff draining from development sites is
treated in accordance with the criteria set forth in the Stormwater Criteria Manual. Stormwater control and treatment
measures may include, but are not limited to:
' • grass buffers
• grass swales
• bioretention (rain garden or porous landscape detention)
• extended detention basins
• constructed wetland ponds
• sand filters
• retention ponds
• constructed wetland channels
• permeable pavements
(Ord No. 051, 2012 §11, 71,17112)
■ 1
11
1
MAPS AND DESIGN AIDS - URBAN DRAINAGE GRASS BUFFER
Grass Buffer
'
Description
Grass buffers are densely vegetated
'
strips of grass designed to accept sheet
flow from upgradient development.
Properly designed grass buffers play a
key role in LID, enabling infiltration and
slowing runoff. Grass buffers provide
filtration (straining) of sediment.
Buffers differ from swales in that they
are designed to accommodate overland
sheet flow rather than concentrated or
channelized flow.
Site Selection
I
I
Grass buffers can be incorporated into a
T-1
wide range of development settings. Photograph GB -I. A flush curb allows roadway runoff to sheet flow
Runoff can be directly accepted from a through the grass buffer. Flows are then further treated by the grass
parking lot, roadway, or the roof of a swale. Photo courtesy of Muller Engineering.
structure, provided the flow is distributed in a uniform manner over the width of the buffer. This can be
achieved through the use of flush curbs, slotted curbs, or level spreaders where needed. Grass buffers are
often used in conjunction with grass swales. They are well suited for use in riparian zones to assist in
stabilizing channel banks adjacent to major drainageways and receiving waters. These areas can also
sometimes serve multiple functions such as recreation.
Hydrologic Soil Groups A and B provide the best infiltration
' capacity for grass buffers. For Type C and D soils, buffers still
serve to provide filtration (straining) although infiltration rates are
lower.
Designing for Maintenance
Recommended ongoing maintenance practices for all BMPs are
provided in Chapter 6 of this manual. During design the
following should be considered to ensure ease of maintenance
over the long-term:
• Where appropriate (where vehicle safety would not be
impacted), install the top of the buffer 1 to 3 inches below the
adjacent pavement so that growth of vegetation and
accumulation of sediment at the edge of the strip does not
prevent runoff from entering the buffer. Alternatively, a
sloped edge can be used adjacent to vehicular traffic areas.
■ Amend soils to encourage deep roots and reduce irrigation
requirements, as well as promote infiltration.
Grass Buffer
Functions
LID/Volume Red.
Yes
W CV Capture
No
W CV+Flood Control
No
Fact Sheet Includes
EURV Guidance
No
Typical Effectiveness for Targeted
Pollutants3
Sediment/Solids
Good
Nutrients
Moderate
Total Metals
Good
Bacteria
Poor
Other Considerations
life -cycle Costs
Low
3 Based primarily on data from the
International Stormwater BMP Database
(www. bmndatabase. ore).
November 1-010 Urban Drainage and Flood Control District
Urban Storm Drainage Criteria Manual Volume 3
C
I MAPS AND DESIGN AIDS - URBAN DRAINAGE GRASS BUFFER
11
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T-1
■ Design and adjust the irrigation system (temporary or
permanent) to provide water in amounts appropriate for
the selected vegetation. Irrigation needs will change from
month to month and year to year.
Grass Buffer
Benefits
■ Filters (strains) sediment and
trash.
■ Protect the grass buffer from vehicular traffic when using Reduces directly connected
this BMP adjacent to roadways. This can be done with a impervious area. (See Chapter 3
slotted curb (or other type of barrier) or by constructing a for quantifying benefits.)
reinforced grass shoulder (see Fact Sheet T-10.5).
Design Procedure and Criteria
The following steps outline the grass buffer design procedure
and criteria. Figure GB-1 is a schematic of the facility and its
components:
1. Design Discharge: Use the hydrologic procedures
described in the Runoff chapter of Volume 1 to determine
the 2-year peak flow rate (Qz) of the area draining to the
grass buffer.
2. Minimum Width: The width (W), normal to flow of the
buffer, is typically the same as the contributing basin (see
Figure GB-1). An exception to this is where flows become
concentrated. Concentrated flows require a level spreader
to distribute flows evenly across the width of the buffer.
The minimum width should be:
_
IN Q20.05
Equation GB-1
■ Can easily be incorporated into a
treatment train approach.
■ Provides green space available
for multiple uses including
recreation and snow storage.
■ Straightforward maintenance
requirements when the buffer is
protected from vehicular traffic.
Limitations
■ Frequently damaged by vehicles
when adjacent to roadways and
unprotected.
■ A thick vegetative cover is
needed for grass buffers to be
effective.
■ Nutrient removal in grass buffers
Where: is typically low.
W = width of buffer (ft) ■ High loadings of coarse solids,
Q2 = 2-year peak runoff (cfs) trash, and debris require
pretreatment.
3. Length: The recommended length (L), the distance along ■ Space for grass buffers may not
the sheet flow direction, should be a minimum of 14 feet. be available in ultra urban areas
This value is based on the findings of Barrett et al. 2004 in (lot -line -to -lot -line).
Stormwater Pollutant Removal in Roadside vegetated
Strips and is appropriate for buffers with greater than 80%
vegetative cover and slopes up to 10%. The study found
that pollutant removal continues throughout a length of 14 feet. Beyond this length, a point of
diminishing returns in pollutant reduction was found. It is important to note that shorter lengths or
slightly steeper slopes will also provide some level of removal where site constraints dictate the
geometry of the buffer.
GB-2 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
I MAPS AND DESIGN AIDS - URBAN DRAINAGE GRASS B UFFER
1
Grass Buffer
4. Buffer Slope: The design slope of a grass buffer in the
direction of flow should not exceed 10%. Generally, a
minimum slope of 2% or more in turf is adequate to
facilitate positive drainage. For slopes less than 2%,
consider including an underdrain system to mitigate
nuisance drainage.
5. Flow Characteristics (sheet or concentrated):
Concentrated flows can occur when the width of the
watershed differs from that of the grass buffer.
Additionally, when the product of the watershed flow
length and the interface slope (the slope of the watershed
normal to flow at the grass buffer) exceeds approximately
one, flows may become concentrated. Use the following
equations to determine flow characteristics:
Sheet Flow: FL(SI) 5 1
Concentrated Flow: FL(SI) > 1
Where:
FL = watershed flow length (ft)
S1 = interface slope (normal to flow) (ft/ft)
T-1
Use of Grass Buffers
Sheet flow of stormwater through a
grassed area provides some benefit in
pollutant removal and volume
reduction even when the geometry of
the BMP does not meet the criteria
provided in this Fact Sheet. These
criteria provide a design procedure
that should be used when possible;
however, when site constraints are
limiting, this treatment concept is
still encouraged.
Equation G13-2
Equation G13-3
6. Flow Distribution: Flows delivered to a grass buffer must be sheet flows. Slotted or flush curbing,
permeable pavements, or other devices can be used to spread flows. The grass buffer should have
relatively consistent slopes to avoid concentrating flows within the buffer.
A level spreader should be used when flows are concentrated. A level spreader can be a slotted drain
designed to discharge flow through the slot as shown in Photo GB-2. It could be an exfiltration
trench filled with gravel, which allows water to infiltrate prior to discharging over a level concrete or
rock curb. There are many ways to design and construct a level spreader. They can also be used in
series when the length of the
buffer allows flows to re -
concentrate. See Figure G13-2 for
various level spreader sections.
Photograph GB-2. This level spreader carries concentrated flows into a
slotted pipe encased in concrete to distribute flows evenly to the grass buffer
shown left in the photo. Photo courtesy of Bill Wenk.
November 2010 Urban Drainage and Flood Control District
Urban Storm Drainage Criteria Manual Volume 3
GB-3
I MAPS AND DESIGN AIDS - URBAN DRAINAGE GRASS BUFFER
I
T-1
Photos GB-3 and GB-4 show a level
spreader that includes a basin for
sedimentation. Concentrated flows
enter the basin via stormsewer. The
basin is designed to drain slowly
while overflow is spread evenly to
the downstream vegetation. A small
notch, orifice, or pipe can be used to
drain the level spreader completely.
The opening should be small to
encourage frequent flows to overtop
the level spreader but not so small
that it is frequently clogged.
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7. Soil Preparation: In order to
encourage establishment and long-
term health of the selected vegetation,
it is essential that soil conditions be
properly prepared prior to
installation. Following site grading,
poor soil conditions often exist.
When possible, remove, strip,
stockpile, and reuse on -site topsoil.
If the site does not contain topsoil,
the soils should be amended prior to
vegetation. Typically 3 to 5 cubic
yards of soil amendment (compost)
per 1,000 square feet, tilled 6 inches
into the soil is required in order for
vegetation to thrive, as well as to
enable infiltration of runoff.
Additionally, inexpensive soil tests
can be conducted to determine
required soil amendments. (Some
local governments may also require
proof of soil amendment in
landscaped areas for water
conservation reasons.)
Grass Buffer
Photograph GB-3. This level spreader includes the added benefit of a
sedimentation basin prior to even distribution of concentrated flows
from the roadway into the grass buffer. Photo courtesy of Bill Wenk.
Photograph GB-4. Maintenance access is provided via the ramp
located at the end of the basin. Photo courtesy of Bill Wenk.
8. Vegetation: This is the most critical
component for treatment within a grass buffer. Select durable, dense, and drought tolerant grasses to
vegetate the buffer. Also consider the size of the watershed as larger watersheds will experience
more frequent flows. The goal is to provide a dense mat of vegetative cover. Grass buffer
performance falls off rapidly as the vegetation coverage declines below 80% (Barrett et a1.2004).
GB-4 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
MAPS AND DESIGN AIDS - URBAN DRAINAGE GRASS BUFFER
Grass Buffer T-1
Turf grasses such as Kentucky bluegrass are often selected due to these qualities'. Dense native turf
grasses may also be selected where a more natural look is desirable. Once established, these provide
the benefit of lower irrigation requirements. See the Revegetation chapter in Volume 2 of this manual
with regard to seed mix selection, planting and ground preparation. Depending on soils and
anticipated flows, consider erosion control measures until vegetation has been established.
9. Irrigation: Grass buffers should be equipped with irrigation systems to promote establishment and
survival in Colorado's semi -arid environment. Systems may be temporary or permanent, depending
on the type of vegetation selected. Irrigation application rates and schedules should be developed and
adjusted throughout the establishment and growing season to meet the needs of the selected plant
species. Initially, native grasses require the same irrigation requirements as bluegrass. After the
grass is established, irrigation requirements for native grasses can be reduced. Irrigation practices
have a significant effect on the function of the grass buffer. Overwatering decreases the permeability
of the soil, reducing the infiltration capacity and contributing to nuisance baseflows. Conversely,
under watering may result in delays in establishment of the vegetation in the short term and unhealthy
vegetation that provides less filtering and increased susceptibility to erosion and rilling over the long
term.
10. Outflow Collection: Provide a means for downstream conveyance. A grass swale can be used for
this purpose, providing additional LID benefits.
Construction Considerations
Success of grass buffers depends not only on a good design and long-term maintenance, but also on
installing the facility in a manner that enables the BMP to function as designed. Construction
considerations include:
• The final grade of the buffer is critical. Oftentimes, following soil amendment and placement of sod,
' the final grade is too high to accept sheet flow. The buffer should be inspected prior to placement of
seed or sod to ensure appropriate grading.
■ Perform soil amending, fine grading, and seeding only after tributary areas have been stabilized and
utility work crossing the buffer has been completed.
■ When using sod tiles stagger the ends of the tiles to prevent the formation of channels along the
joints. Use a roller on the sod to ensure there are no air pockets between the sod and soil.
• Avoid over compaction of soils in the buffer area during construction to preserve infiltration
capacities.
■ Erosion and sediment control measures on upgradient disturbed areas must be maintained to prevent
excessive sediment loading to grass buffer.
Although Kentucky bluegrass has relatively high irrigation requirements to maintain a lush, green aesthetic, it also withstands
drought conditions by going dormant. Over -irrigation of Kentucky bluegrass is a common problem along the Colorado Front
' Range, and it can be healthy, although less lush, with much less irrigation than is typically applied.
November 2010 Urban Drainage and Flood Control District G13-5
Urban Storm Drainage Criteria Manual Volume 3
MAPS AND DESIGNAIDS - URBAN DRAINAGE GRASS BUFFER
T-1 Grass Buffer
/l
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Q
ku 1
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t
i
t� r
WATER5NED rLJW LENCgTH R�
V 1 !
PLAN
I'TO3' LIP WWEWE
SUITABLE
(MIN)
AMENDED SOIL5?-,
LEVEL SPREADER
PROFILE
Figure GB-1. TN pical Grass Buffer Graphic by Adia Davis.
Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
MAPS AND DESIGN AIDS - URBAN DRAINA GE GRASS BUFFER
Grass Buffer T-1
CORRUGATED SLOTTED DRAIN PIPE
GRASS BUFFER
✓� AGGREGATE BASE COURSE
SECTION
LEVEL SPREADER FOR PIPE FLOWS
PIPE AND HEADWALL BEYOND
DRAIN PAN WITH CURBS
SECTION
LEVEL SPREADER FOR PIPE FLOWS
GRASS BUFFER
UNDERDRAIN, SEE SECTION 5
(OR PROVIDE SMALL OPENING IN WALL)
SECTION .g.
LEVEL SPREADER FOR SURFACE FLOWS
GRASS BUFFER
n-
UNOERDRAIN, SEE SECTION 5
(OPTIONAL)
SECTION
LEVEL SPREADER FOR SMALL SURFACE FLOWS
COOT CLASS C FILTER MATERIAL
OR OTHER COMPATIBLE MATERIAL
SUCH AS AASHTO f57 OR #67
COOT
CUSS C
FILTER
MATERIAL
PER TABLE
GS-2'
1. SEE BMP FACT SHEET T-2, GRASS SWALE
-5, MIN 8"
SLOTTED PIPE PER TABLE CS-3'
SECTION r1
UNDERDRAIN
Figure G13-2. Typical Level Spreader Details
November 2010 Urban Drainage and Flood Control District G13-7
Urban Storm Drainage Criteria Manual Volume 3
I MAPS AND DESIGN AIDS - URBAN DRAINAGE GRASS SWALE
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Grass Swale
Description
Grass swales are densely vegetated
trapezoidal or triangular channels with
low-pitched side slopes designed to
convey runoff slowly. Grass swales
have low longitudinal slopes and broad
cross -sections that convey flow in a slow
and shallow manner, thereby facilitating
sedimentation and filtering (straining)
while limiting erosion. Berms or check
dams may be incorporated into grass
swales to reduce velocities and
encourage settling and infiltration.
When using berms, an underdrain
system should be provided. Grass
swales are an integral part of the Low
Impact Development (LID) concept and
may be used as an alternative to a curb and
gutter system.
Site Selection
T-2
Photograph GS-1. This grass swale provides treatment of roadway
runoff in a residential area. Photo courtesy of Bill Ruzzo.
Grass swales are well suited for sites with low to moderate slopes.
Drop structures or other features designed to provide the same
function as a drop structures (e.g., a driveway with a stabilized
grade differential at the downstream end) can be integrated into
the design to enable use of this BMP at a broader range of site
conditions. Grass swales provide conveyance so they can also be
used to replace curb and gutter systems making them well suited
for roadway projects.
' Designing for Maintenance
Recommended ongoing maintenance practices for all BMPs are
provided in Chapter 6 of this manual. During design, the
following should be considered to ensure ease of maintenance
over the long-term:
■ Consider the use and function of other site features so that the
swale fits into the landscape in a natural way. This can
encourage upkeep of the area, which is particularly important
in residential areas where a loss of aesthetics and/or function
can lead to homeowners filling in and/or piping reaches of
this BMP.
' November 2010
Grass Swale
Functions
LID/Volume Red.
Yes
W CV Capture
No
WQCV+Flood Control
No
Fact Sheet Includes
EURV Guidance
No
Typical Effectiveness for Targeted
Pollutants'
Sediment/Solids
Good
Nutrients
Moderate
Total Metals
Good
Bacteria
Poor
Other Considerations
Life -cycle Costs
Low
' Based primarily on data from the
International Stormwater BMP Database
(www. bmpdatabase.org).
Urban Drainage and Flood Control District
Urban Storm Drainage Criteria Manual Volume 3
GS-1
I
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MAPS AND DESIGN AIDS - URBAN DRAINAGE GRASS SWALE
i
T-2
Grass Swale
■ Provide access to the swale for mowing equipment and
Benefits
design sideslopes flat enough for the safe operation of
Removal of sediment and
equipment.
■ Design and adjust the irrigation system (temporary or
associated constituents through
filtering (straining)
permanent) to provide appropriate water for the selected
Reduces length of storm sewer
vegetation.
systems in the upper portions of a
'
■ An underdrain system will reduce excessively wet areas,
watershed
which can cause rutting and damage to the vegetation
Provides a less expensive and
during mowing operations.
'
more attractive conveyance
■ When using an underdrain, do not put a filter sock on the
element
pipe. This is unnecessary and can cause the slots or
Reduces directly connected
perforations in the pipe to clog.
impervious area and can help
Design Procedure and Criteria
reduce runoff volumes.
The following steps outline the design procedure and criteria
Limitations
for stormwater treatment in a grass swale. Figure GS-1
shows trapezoidal and triangular swale configurations.
Requires more area than
traditional storm sewers.
1. Design Discharge: Determine the 2-year flow rate to be
conveyed in the grass swale under fully developed
conditions. Use the hydrologic procedures described in
• Underdrains are recommended for
slopes under 2%.
the Runoff Chapter in Volume 1.
■ Erosion problems may occur if not
2. Hydraulic Residence Time: Increased hydraulic
designed and constructed
residence time in a grass Swale improves water quality
properly.
treatment. Maximize the length of the swale when
possible. If the length of the Swale is limited due to site
constraints, the slope can also be decreased or the cross -sectional area increased to increase hydraulic
residence time.
'
3. Longitudinal Slope: Establish a longitudinal slope that will
meet Froude number, velocity, and
depth criteria while ensuring that the grass swale maintains
positive drainage. Positive drainage can
be achieved with a minimum 2% longitudinal slope or by including an underdrain system (see step 8).
Use drop structures as needed to accommodate site constraints.
Provide for energy dissipation
downstream of each drop when using drop structures.
4. Swale Geometry: Select geometry for the grass swale. The cross section should be either
trapezoidal or triangular with side slopes not exceeding 4:1 (horizontal: vertical), preferably flatter.
Increase the wetted area of the swale to reduce velocity. Lower velocities result in improved
pollutant removal efficiency and greater volume reduction. If one or both sides of the grass swale are
also to be used as a grass buffer, follow grass buffer criteria.
GS-2 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
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' MAPS AND DESIGN AIDS -URBAN DRAINAGE GRASS SWALE
1
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Grass Swale
T-2
Vegetation: Select durable, dense, and drought tolerant grasses. Turf grasses, such as Kentucky
bluegrass, are often selected due to these qualities'. Native turf gasses may also be selected where a
more natural look is desirable. This will also provide the benefit of lower irrigation requirements,
once established. Turf grass is a general term for any
grasses that will form a turf or mat as opposed to bunch
grass, which will grow in clumplike fashion. Grass
selection should consider both short-term (for
establishment) and long-term maintenance requirements,
given that some varieties have higher maintenance
requirements than others. Follow criteria in the
Revegetation Chapter of Volume 2, with regard to seed
mix selection, planting, and ground preparation.
6. Design Velocity: Maximum flow velocity in the swale
should not exceed one foot per second. Use the Soil
Conservation Service (now the NRCS) vegetal retardance
curves for the Manning coefficient (Chow 1959).
Determining the retardance coefficient is an iterative
process that the UD-BMP workbook automates. When
Native grasses provide
a more natural aesthetic
and require less water
once established.
starting the swale vegetation from sod, curve "D" (low retardance) should be used. When starting
vegetation from seed, use the "E" curve (very low vegetal retardance).
7. Design Flow Depth: Maximum flow depth should not exceed one foot at the 2-year peak flow rate.
Check the conditions for the 100-year flow to ensure that drainage is being handled without flooding
critical areas, structures, or adjacent streets.
Table GS-1. Grass Swale Design Summary for Water Quality
Design Flow
Maximum
Froude Number
Maximum
Velocity
Maximum
Flow Depth
2-year event
0.5
1 ft/s
1 ft
Use of Grass Swales
Vegetated conveyance elements provide some benefit in pollutant removal and volume reduction
even when the geometry of the BMP does not meet the criteria provided in this Fact Sheet. These
criteria provide a design procedure that should be used when possible; however, when site
constraints are limiting, vegetated conveyance elements designed for stability are still encouraged.
' Although Kentucky bluegrass has relatively high irrigation requirements to maintain a lush, green aesthetic, it also withstands
drought conditions by going dormant. Over -irrigation of Kentucky bluegrass is a common problem along the Colorado Front
Range. It can be healthy, although less lush, with much less irrigation than is typically applied.
November 2010 Urban Drainage and Flood Control District
Urban Storm Drainage Criteria Manual Volume 3
GS-3
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MAPS AND DESIGN AIDS - URBAN DRAINAGE GRASS SWALE
11
i
T-2
Grass Swale
8, Underdrain: An underdrain is necessary for swales with longitudinal slopes less than 2.0%. The
underdrain can drain directly into an inlet box at the downstream end of the swale, daylight through
the face of a grade control structure or continue below grade through several grade control structures
as shown in Figure GS-1.
The underdrain system should be placed within an aggregate layer. If no underdrain is required, this
layer is not required. The aggregate layer should consist of an 8-inch thick layer of CDOT Class C
filter material meeting the gradation in Table GS-2. Use of CDOT Class C Filter material with a
slotted pipe that meets the slot dimensions provided in Table GS-3 will eliminate the need for
geotextile fabrics. Previous versions of this manual detailed an underdrain system that consisted of a
3- to 4-inch perforated HDPE pipe in a one -foot trench section of AASHTO #67 coarse aggregate
' surrounded by geotextile fabric. If desired, this system continues to provide an acceptable alternative
for use in grass swales. Selection of the pipe size may be a function of capacity or of maintenance
equipment. Provide cleanouts at approximately 150 feet on center.
I
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I
GS-4
Table GS-2. Gradation Specifications for Class C Filter Material
(Source: CDOT Table 703-7)
Sieve Size
Mass Percent Passing Square Mesh Sieves
19.0 mm (3/4")
100
4.75 mm (No. 4)
60 — 100
300 m (No. 50)
10 — 30
150 gni (No. 100)
0 — 10
75 gm (No. 200)
0-3
Table GS-3. Dimensions for Slotted Pipe
Pipe Diameter
Slot
Length �
Maximum Slot
Width
Slot
Centers'
Open Area '
(per foot)
4"
1-1/16"
0.032"
0.413"
1.90 in
6"
1-3/8"
0.032"
0.516"
1.98 in
'Some variation in these values is acceptable and is expected from various pipe
manufacturers. Be aware that both increased slot length and decreased slot centers
will be beneficial to hydraulics but detrimental to the structure of the pipe.
Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
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MAPS AND DESIGN AIDS - URBAN DRAINAGE GRASS SWALE
Grass Swale T-2
9. Soil preparation: Poor soil conditions often exist following site grading. When the section includes
an underdrain, provide 4 inches of sandy loam at the invert of the swale extending up to the 2-year
water surface elevation. This will improve infiltration and reduce ponding. For all sections,
encourage establishment and long-term health of the bottom and side slope vegetation by properly
preparing the soil. If the existing site provides a good layer of topsoil, this should be striped,
stockpiled, and then replaced just prior to seeding or placing sod. If not available at the site, topsoil
can be imported or the existing soil may be amended. Inexpensive soil tests can be performed
following rough grading, to determine required soil amendments. Typically, 3 to 5 cubic yards of soil
amendment per 1,000 square feet, tilled 4 to 6 inches into the soil is required in order for vegetation to
thrive, as well as to enable infiltration of runoff.
10. Irrigation: Grass swales should be equipped with irrigation systems to promote establishment and
survival in Colorado's semi -arid environment. Systems may be temporary or permanent, depending
on the type of grass selected. Irrigation practices have a significant effect on the function of the grass
swale. Overwatering decreases the permeability of the soil, reducing the infiltration capacity of the
soil and contributing to.nuisance baseflows. Conversely, under watering may result in delays in
establishment of the vegetation in the short term and unhealthy vegetation that provides less filtering
(straining) and increased susceptibility to erosion and riling over the long term.
Construction Considerations
Success of grass swales depends not only on a good
design and maintenance, but also on construction
practices that enable the BMP to function as designed.
Construction considerations include:
■ Perform fine grading, soil amendment, and seeding
only after upgradient surfaces have been stabilized
and utility work crossing the swale has been
completed.
■ Avoid compaction of soils to preserve infiltration
capacities.
■ Provide irrigation appropriate to the grass type.
■ Weed the area during the establishment of vegetation
by hand or mowing. Mechanical weed control is
preferred over chemical weed killer.
■ Protect the swale from other construction activities.
Photograph GS-2. This community used
signage to mitigate compaction of soils post -
construction. Photo courtesy of Nancy Styles.
■ When using an underdrain, ensure no filter sock is placed on the pipe. This is unnecessary and can
cause the slots or perforations in the pipe to clog.
November 2010 Urban Drainage and Flood Control District
Urban Storm Drainage Criteria Manual Volume 3
GS-5
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PREVIOUS REPORTS
I
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I
' "Geotechnical Engineering Report, Avago Technologies B4 West Annex" Terracon
Consultants, Inc. September 4, 2012
1 Geotechnical Engineering Report
Avago Technologies B4 West Annex
1 4380 Ziegler Road
Fort Collins, Colorado
September 4, 2012
Terracon Project No. 20125028
I
0
'
Prepared for:
The CPI Group
Greenwood Village, Colorado
Prepared by:
1 Terracon Consultants, Inc.
Fort Collins, Colorado
11
11
' "Geotechnical Engineering Report, Avago Technologies B4 West Annex". Terracon
Consultants, Inc. September 4, 2012
I
1
I
I
September 4, 2012
The CPI Group
7400 East Orchard Road, Suite 270
Greenwood Village, Colorado 80111
Attn: Mr. Eric Wilson
President and CEO
P: (720) 475-8210
E: eric.wilson@thecpigroup.net
Re: Geotechnical Engineering Report
Avago Technologies B4 West Annex
4380 Ziegler Road
Fort Collins, Colorado
Terracon Project No. 20125028
Dear Mr. Wilson:
1k2r,recon
Terracon Consultants, Inc. (Terracon) has completed the geotechnical engineering services for
the project referenced above. These services were performed in general accordance with our
proposal number P20120131 dated July 16, 2012 and signed Agreement for Services dated
August 23, 2012. This geotechnical engineering report presents the results of the subsurface
exploration and provides geotechnical recommendations concerning earthwork and the design
and construction of foundations and floor slabs for the proposed project.
We appreciate the opportunity to be of service to you on this project. If you have any questions
concerning this report, or if we may be of further service, please contact us,
Sincerely,
Terracon Consultants, Inc.
Bryce C. Johnson, E.I.T.
Eric D.
Geotechnical Engineer
Geoted
Reviewed by: Douglas J. Jobe, P.E. Senior Vice President/Division Manager
Enclosures
' Copies to:
Addressee (1 via e-mail)
Terracon Consultants -,!Inc. 3o1,North Howes Street ' Fort Collins, Colorado. '565V
0. [970148450359 IF [Obl484E0454 www.terracon.com
11
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"Hewlett-Packard Building 5 Drainage Report': Sear -Brown Group. 1996.
FINAL DRAINAGE STUDY FOR
HEWLETT-PACKARD COMPANY
BUILDING 5
FORT COLLINS, COLORADO
October 4, 1996
Prepared for:
H + L Architecture
1621 18th Street, Suite 100
Denver, Colorado 80202
Prepared by:
RBD. Inc. Engineering Consultants
A Division of Sear Brown
209 South Meldrum
Fort Collins, Colorado 80521
(970) 482-5922
RBD Job No. 282-015
Phis unofficial copy was downloaded on Feb-06-2013 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
No Text
SEAR• BROWN
ARCHITECTURE
2095outh Meldmm
ENGINEERING
Fort Colllns,CO 80521-2603
PLANNING
970.482.5922 phone
CONSTRUCTION
970.482.6368 fax
i
www.searbrowmcom
"Detailed Hydraulic Study, Regional Detention Facilities, Hewlett-Packard Company':
Sears Brown Group. 2000.
July 3; 2000
Mr. Basil Harridan
City of Fort Collins
Stormwater Utility Services .
700 Wood Street
Fort Collins, Colorado 80522
RE: Detailed Hydraulic Analysis of HP Site Regional Detention Facilities
Dear Basil:
We are pleased to submit to you, for your review, this revised Detailed Hydraulic Analysis for the
Regional Detention Facilities at the Hewlett-Packard Site on Harmony Road in Fort Collins. All
computations within this report have been completed in compliance with the City of Fort Collins
Storm Drainage Design Criteria.
We appreciate your time and consideration in reviewing this submittal. Please contact us if you have
any questions.
Respectfully,
Sear -Brown
Prepared By:
Jere*/V Franz, E.I.T.
Water Resource Engineer
File: 564-014 (B)
Reviewed By:
David K. Thaeme
Senior Engineer -
I unofficial copy was downloaded on Feb-06-2013 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 US
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1 his unofficial copy was downloaded on Feb-06r2013 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
or additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fart Collins, CO 80524 USA
' "Hewlett-Packard Building 4 Drainage Report': Sear -Brown Group. 1999.
' REVISION:
' FINAL DRAINAGE AND
' EROSION CONTROL STUDY FOR
HEWLETT-PACKARD BUILDING 4
' FORT COLLINS, COLORADO
March 22, 1999
Prepared for:
IDC
Portland Office
2020 S.W. Fourth Avenue, 3rd Floor
Portland, Oregon 97201
Prepared by:
The Sear -Brown Group
209 S. Meldrum
Fort Collins, Colorado 80521
(970)482-5922
RBD Job No. 799-001
is unofficial copy was downloaded on Feb-06-2013 from the City of Fort Collins Public Records Website: http://Citydocs.fcgov.com
''
or additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA
"He)vlett-Packard Building 4 Drainage Report . Sear -Brown Group. 1999. —
SEE NEAnwL
\ E pCFAA
SIR C'T5
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1± TYR.
R - - (,YVAP
to TYK
LEGEND
IF � • 2 n ` � I ' ''•' - EIKISTNG CONTOUR
—M� PROPOSED CONTOUR
5 .q. DIRECTION r
DESIGNESIGN l Ow
POINT
DRAINAGE BASIN BOUNDARY
TUMV BASIN NUWM
UTAC STORAGE BASIN AREA _ — — _ — _ _ ( jIL AVERAOE STREET SLOPE
• I _ _tA I —� SWALE/DITCH ./ FLOW ARROW
CON TRUC, I 7 _ O GRAVEL INLET FILTER
- I I
I ±� ± STRAW BALE CHECK DAM
JIFA
--jam-- Jz SILT FENCE
� � I
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A AREA IMi1 ®AI TS)MIFf f l T - -- -. ---
(1-27)
TSILAR-BROWN
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AREA MET w->a+a cool Ra+ma.as
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{ A _ A J Ni (121) ! iilr of Fort Cdfln•, Cdorodo I Iplca R aTF ea..T • .wow
't 17 TYPE 'R UTILITY PLAN APPROVAL • nao rw err roe* nn.
%EFT (1-3) — - . , AYPRDVLU. CAVED STRINGER 16 98 NO "Y OR 6M r DATE
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' ) j - -- '. CHECEDBY. +eT.tN/wslwewlRlET 46 // F-IEWLETT
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(MGxED BY- CAEN 0 SCHLUE TER �y6 CP� PAC KARD
a� I IRIIII I — 7 I / Aeu •oe. �" FORT Cowen
CHECKED By. -
CHECKED Br
CHECKED BY ICBD GENESIS IV
moon I I \ (H-1•) I -- - - - - - -- - -Im BUILDING
---
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w \ i® -4-6 DRAINAGE AND EROSION
CONTROL PLAN
_ cw.won 1wr
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TO DE901 PONE rYGSP--(:EE.DYG AR.Y 1 e 1
- ----- I I I '"..J'
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EXISTING BUILDINC> 1 w m C- 4.1
"Hewlett-Packard Building 4 Drainage Report". Sear -Brown Group. 1999.
RBD, Inc., Engineering Consunanb
Weighted Runoff Coefficients sheet 1 of 1
Project # 799-001 TLD
HP Building 4 - ADDENDUM 0727/98
This sheet calculates the composite "C" values for the Rational Method.
"'" Numbers 20 and 21a are not used
es'i"
Area
Impervious
'C"
Pervious
"C'
A,total
ac.
A,anp
ac.
A.perv.
ac.
/o Imp
hpery
omp.
C.
OFFSITE BASINS
OS1
0.95
0.25
0.87
0.58
0.29
67%
33%
0.72
OS2
0.95
0.25
1.52
0.94
0.58
62%
38%
0.68
OS3
0.95
0.25
0.79
0.41
0.38
52%
48%
0.51
OS4
0.95
0.25
0.67
0.57
0
100%
0%
0.95
OS5
0.95
0.25
0.29
0.29
0
100%
0%
0.95
OS6
0.95
0.25
2.31
1.62
0.69
70%
30%
0.74
OS7
0.95
0.25
0.34
0.18
0.16
53%
47%
0.62
otal:
6.69
4.59
2.10
69%
31%
0.73
ONSITE
BASINS
1
0.95
0.25
5.28
0.00
5.28
0%
100%
0.25
2
0.95
0.25
1.23
0.19
1.04
15%
85%
0.36
3
0.95
0.25
0.8
0.13
0.67
16%
84%
0.36
4
0.95
0.25
1.67
0.19
1.44
11 %
86%
0.32
5
0.95
0.25
0.77
0.12
0.65
16%
84%
0,36
6
0.95
0.25
6.75
0.00
6.75
0%
100%
0.25
7
0.95
0.25
0.75
0.23
0.52
31%
69%
0.46
8
0.95
0.25
0.41
0,24
0.17
59%
41%
0.66
9
0.95
0.25
0.99
0.99
0
100%
0%
0.95
10
0.95
0.25
0.46
0.46
0
100%
0%
0.95
11
0.95
0.25
0.38
0.38
0
100%
0%
0.95
12
0.95
0.25
0.7
0.7
0
100%
0%
0.95
13
0.95
0.25
0.5
0.5
0
100%
0%
0.95
14
0.95
0,25
0.43
0.25
0.18
58%
42%
0.66
15
0.95
0.25
0.39
0.39
0
100%
0%
0.95
16
0.95
0.25
0.18
0.18
0
100%
0%
0.95
17
0.95
0.25
1.96
0.56
1.4
29%
71%
0.45
18
0.95
0,25
0.9
0.05
0.85
6%
94%
0.29
19
0.95
0.25
2.85
- 0.10
2.75
4%
96%
0.27
20
0.95
0.25
0.38
0.08
0.3
21%
79%
0.40
21
0.95
0.25
0.74
0.46
0.28
62%
38%
0.69
22
D.95
0.25
1.01
0.79
0.22
78%
22%
0.80
22a
0.95
0.25
0.87
0.72
0.15
83%
17%
0.83
23
0.95
0.25
0.74
0.49
0.25
67%
34%
0.72
24
0.95
0.25
0.63
0.56
0.07
89%
11%
0.87
24a
0.95
0.25
0.37
0.35
0.02
95%
5%
0.91
24B
0.95
0.25
0.31
0.25
0.06
81%
19%
0.81
25
0.95
0.25
0.65
0.48
0.17
74%
26%
0.77
25A
0.95
0.25
0.54
0.421
0.12
78%
22%
0.79
26
0.95
0.25
0.3
0.27
0.03
90%
10%
0.88
27
0.95
0.25
0.04
0.04
0
100%
0%
0.95
28
0.95
0.25
0.25
0.25
0
100%
0%
0.95
29
0.95
0.25
0.15
0.15
0
100%
0%
0.95
30
0.95
0.25
0.16
0.16
0
100%
0%
0.95
31
0.95
0.25
0.07
0.07
0
100%
0%
0.95
32
0.95
0.25
0.52
0.31
0.21
60%
40%
0.67
33
0.95
0.25
0.03
0.03
0
100%
0%
0.95
34
0.95
0.25
0.42
0.23
0.19
55%
45%
0.63
35
0.95
0.25
0.391
0.39
0
10D%
0%
0.95
36
0.95
0.25
0.33
0.16
0,17
48%
52%
0.59
37
0.95
0.25
0.33
0.29
0.04
88%
12%
0.87
38
0.95
0.25
0.32
0.23
0.09
72%
28%
0.75
39
0.95
0.25
2.02
0.00
2.02
0%
100%
0.25
40
0.95
0.25
0.06
0.05
0.01
83%
17%
0.83
SITE
39.03
12.89
26.10
33.03%1
66.87%
0.48
Storm Drainage Design and Tedinival Crheria
Vhis unofficial copy was downloaded on Feb-06-2013 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com
or additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins. CO 80524 USA
I
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HYDROLOGIC COMPUTATIONS
RATIONAL METHOD
COMPOSITE C-FACTOR COMPLIANCE
1
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HYDROLOGIC COMPUTATIONS- RATIONAL METHOD
BAS I N A
RATIONAL METHOD ROUTING ' DIAGRAM
i
A3 A11 A8
A3 1 A8
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A9
- A9
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BASIN C
RATIONAL METHOD ROUTING DIAGRAM
cy
C1
C2
HYDROLOGIC COMPUTATIONS- RATIONAL METHOD
I
HYDROLOGIC COMPUTATIONS- RATIONAL METHOD
PROJECT INFORMATION
PROJECT NAME:
AVAGO
PROJECT NO:
13.0091
DESIGN BY:
BMS
REVIEWED BY:
PSB
JURISDICTION:
FORT COLLINS
REPORT TYPE:
FINAL, MINOR AMENDMENT
DATE:
06/17/14
�� MARTIN / MARTIN
/ CONAUI TINO ENOINEERS
JURISDICTIONAL STANDARD
C2
CS
C70
C100
% IMPERV
PERVIOUS _
IMPERVIOUS
0.25
0.95
0.00
0.00
0.00
0.25
0%
0.00
0.95
100%
TOTAL SITE COMPOSITE 1 24.24 1 0.43 0.00 1 0.00 0.43 26.2
SUB -BASIN SURFACE CHARACTERISTICS
AREA
COMPOSITE RUNOFF COEFFICIENTS PERCENT
C2 CS C10 C100 IMPERVIOUSNESS
(ACRES)
IMPERVIOUS
Al PERVIOUS
0.83
0.95
0.00
_
0,00 0.95
0.00 0,25
100%
0.00
0.25
0.00
0%
SUB -BASIN COMPOSITE
0.83
0.96
0.00
0.00 0.95 100.0%
SUB -BASIN SURFACE CHARACTERISTICS AREA
(ACRES)
IMPERVIOUS 0.05
A2 PERVIOUS 0.20
COMPOSITE
RUNOFF
COEFFICIENTS
PERCENT
IMPERVIOUSNESS
100%
0%
C2
C5
C10 C100
0.95
0.25
0.00
0.00 0.96:
0.00 0.25
0.00
SUB -BASIN COMPOSITE
0.25
0.38
0.00
0.00 0.38 15.7%
SUB -BASIN SURFACE CHARACTERISTICS
IMPERVIOUS
A3 PERVIOUS
AREA
COMPOSITE
RUNOFF
COEFFICIENTS PERCENT
C1'0 C100 IMPERVIOUSNESS
0.00 0.95 100%
(ACRES)
C2
C5
0.76
0.95
0.00
0.00
0.25
0.00
0.00 0.25 1 0%
SUB -BASIN COMPOSITE 0.76
0.96
0.00 0.00 0.95 100.0%
AREA
COMPOSITE RUNOFF COEFFICIENTS
PERCENT
SUB -BASIN SURFACE CHARACTERISTICS
(ACRES)
C2
C5
CIO
C100
IMPERVIOUSNESS
IMPERVIOUS
0.07
0.96
0.00
0.00
0.95
100%
A4 .PERVIOUS
2.18
0.25
0.00
0.00
0,25
0%
SUB -BASIN COMPOSITE
2.26
0.27
0.00 0.00
0.27
3.3°%
SUB -BASIN SURFACE CHARACTERISTICS
AREA
(ACRES)
COMPOSITE
C2
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SUB -BASIN COMPOSITE
1 0.31
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AREA
COMPOSITE RUNOFF COEFFICIENTS
PERCENT
IMPERVIOUSNESS
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C2
CS
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0.09
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1.70
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SUB -BASIN COMPOSITE
1.79
0.29
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1 6.1%
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G:%SCHLAGETER113.0091-Avago Bldg 4 Evansion and Site DevelomerhENGDRAINAGENRATIONAL METHODIRATIONAL METHOD -MINOR AMENDMENT SE
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HYDROLOGIC COMPUTATIONS- RATIONAL METHOD
SUB -BASIN SURFACE CHARACTERISTICS
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2.51
0.38
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AREA
COMPOSITE RUNOFF COEFFICIENTS
PERCENT
IMPERVIOUSNESS
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C2
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C10 C100
IMPERVIOUS
0.19
0.95
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100%
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0.03
0.25
0.00
0.00 0.25
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SUB -BASIN COMPOSITE
0.22
0.88
0.00
0.00 0.85
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0.03
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0.00 0.25
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SUB -BASIN COMPOSITE 0.15
0.83
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SUB -BASIN SURFACE CHARACTERISTICS AREA COMPOSITE RUNOFF COEFFICIENTS PERCENT
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SUB -BASIN SURFACE CHARACTERISTICS
AREA
COMPOSITE RUNOFF COEFFICIENTS
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IMPERVIOUSNESS
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C2
C6
C10 C100
IMPERVIOUS
0.22
0.95
0.00
0.00 0.95
100%
All PERVIOUS 2.18
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0.25
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0.00 0.25
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SUB -BASIN COMPOSITE 2.40
0.31
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IMPERVIOUS 0.30
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COEFFICIENTS _ PERCENT
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C2
CS
0.95
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0.25
0.00
0.00 0.25
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SUB -BASIN COMPOSITE
0.96
0.47
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SUB -BASIN SURFACE CHARACTERISTICS AREA
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IMPERVIOUS 1 0.46
B3 PERVIOUS 1.36
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C2
CS
C10 C100
0.95
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0.25
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0.00 0.25
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SUB -BASIN COMPOSITE
1.81
0.43
0.00
0.00 0.43 25.3%
COMPOSITE_C-VALUES
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6/17/2014 12:45 PM EXPANSION.xds
HYDROLOGIC COMPUTATIONS- RATIONAL METHOD
SUB -BASIN SURFACE CHARACTERISTICS
AREA
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COMPOSITE RUNOFF COEFFICIENTS
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IMPERVIOUSNESS
IMPERVIOUS
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0.95
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0.25
0.00
0.00
0.25
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SUB -BASIN COMPOSITE
1 0.56
0.64
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0.64
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SUB -BASIN SURFACE CHARACTERISTICS
AREA
COMPOSITE RUNOFF COEFFICIENTS
PERCENT
IMPERVIOUSNESS
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C2
C6
C1�0 C100
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0.07
0.95
0.00
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0.18
0.25
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SUB-BAStN COMPOSITE
0.25
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0.00
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27.0%
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AREA
COMPOSITE RUNOFF COEFFICIENTS
PERCENT
IMPERVIOUSNESS
(ACRES)
C2
C5
C10 C100
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0.19
0.96
0.00
0.00 0.95
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0.60
0.25
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0.00 0.25
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SUB -BASIN COMPOSITE
0.79
0.42
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AREA
COMPOSITE RUNOFF COEFFICIENTS
PERCENT
IMPERVIOUSNESS
(ACRES)
C2
C5
C10 C100
IMPERVIOUS
0.19
0.95
0.00
0.00 0.95
100%
PERVIOUS
0.47
0.25
0.00
0.00 0.25
0%
B7
SUB -BASIN COMPOSITE
0.66
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0.00
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AREA
COMPOSITE RUNOFF COEFFICIENTS
PERCENT
IMPERVIOUSNESS
(ACRES) C2
CS
C10 C100
IMPERVIOUS
0.75
0.95
0.00
0.00
0.96
100%
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0.27
0.25
0.00
0.00
0.25
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SUB -BASIN COMPOSITE
1.02
0.77
0.00
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COMPOSITE RUNOFF COEFFICIENTS
PERCENT
SUB -BASIN SURFACE CHARACTERISTICS
(ACRES)
C2
CS
C10
C100.
IMPERVIOUSNESS
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0.05
0.95
0.00
0.00
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C2 PERVIOUS
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0.00
0.00
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SUB -BASIN COMPOSITE
1.62
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0.27
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IMPERVIOUS 0.29
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IMPERVIOUSNESS
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SUB -BASIN COMPOSITE 1.97
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0.25
0.00 0.00 0.25
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COMPOSITE_C-VALUES
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HYDROLOGIC COMPUTATIONS- RATIONAL METHOD
PROJECT:
AVAGO
JOB NO:
01/13/00
DATE:
06/17/14
MARTIN/MARTIN
CONSULTING ENGINEERS
RUNOFF SUMMARY
BASIN
DESIGN
POINT
AREA
(ACRES)
%
IMP.
C z
C 00
O2
(CFS)
Q100
(CFS)
Al
Al 0.83 100.0% 0.95 0.95
A2 0.25 18.7% 1 0.38 0.38
2.18
7.61
A2
0.21
0.72
A3
A3
0.76
100.0%
0.95
0.95
2.01
6.99
A4
A4
2.26
3.3%
0.27
0.27
1.23
4.27
A5
A5
0.31
100.0%
0.95
0.95
0.82
2.84
A6
A6
1.79
5.1 %
0.29
0.29
1.04
3.62
A7
A7
2.51
18.1%
0.38
0.38
1.95
6.81
A8
A8
0.22
87.8%
0.86
0.86
0.41
1.41
A9
A9
0.15
82.8%
0.83
0.83
0.28
0.97
A10
A10
0.19
85.9%
0.85
0.85
0.35
1.21
All
All
2.40
9.1%
0.31
0.31
1.60
5.59
B2
B2
0.95
31.1 %
0.47
0.47
0.94
3.27
B3
83
1.81
25.3%
0.43
0.43
1.63
5.69
B4
B4
0.55
42.0%
0.54
0.54
0.69
2.42
B5
B5
0.25
27.0%
0.44
0.44
0.24
0.84
B6
B6
0.79
24.4%
0.42
0.42
0.71
2.49
B7
B7
0.66
28.4%
0.45
0.45
0.64
2.24
Cl
C1
1.02
73.6%
0.77
0.77
1.62
5.67
C2
C2
1.62
3.0%
0.27
0.27
0.91
3.17
C3
C3
1.97
14.6%
0.35
0.35
1.48
5.17
C4
C4
0.69
-0.3%
0.25
0.25
0.36
1.25
OS -A
OS -A
2.25
25.5%
0.43
0.43
2.02
7.04
SITE COMPOSITE
1
24.24 1
26.2% 1
0.43
0.43
Y3.31
81.31
RUNOFF SUMMARY
6/17/2014 12:45 PM
G:\SCHLAGETER\l3.0091-Avago Bldg 4 Expansion and Site Develoment\ENG\DRAINAGE\RATIONAL METHOMRATIONAL
METHOD -MINOR AMENDMENT SE EXPANSION.xls
HYDROLOGIC COMPUTATIONS -
COMPOSITE C-FACTOR COMPLIANCE
PROJECT INFORMATION
PROJECT NAME: BLDG 4 EXPANSION
PROJECT #: 1 MARTIN / M ARTI N
6/17/2
DATE: 6/17/2014 eorsu.nra rsu+rr+•
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) (ac
4
0.95 0.25 0.19 1,44 1.67 11 861
0.32
5
0.95
0.25 0.12 0.65, 0.77
161
84
_
0.36
6
0.95
0.25 0.00 6,751
0.25 0.25 0.18
6.75
0
100
0.25
14
0.95
0.43
58
42
0.66
17
0.95
0.25 0.56; 1.40
1.96
29.
71
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
0.251
0.08
0.30
0.38
21
79
0.40
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
0.7
24
0.95
0.25
0.56
0.07
0.63
89
11
0.8
24A
0.95
0.25
0.35
0.02
0,37
95
5
0.91
24B
1 0.95
0.25
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
0.96
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
0.00
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
0.09i
0.32
72
281
0.75
40 0.95 0.25 0.05
39 0.95 0.25 0.06
SITE E 6,49,
_
_ _ 0.01'i 0.06 83 171 0.83
ZOT 0.00 0 100
17.74 24.23 27 73 C 0.44
BLDG 4 WEST ANNEX EXPANSIONAND SITE DEVELOPMENT PROJECT
BASINS
Impervious Pervious A, Imp A, Pen A, total
Basin „C„ .,C1. ac (ac) ac. Imp %Pen Composite "C"'
Al
0.95
0.251
0831
0.001
0.83
100
19
01
095
039
A2
0.95
0.25
0.05
0.20
0.25
81
A3
0.95
0.25
0.76
0.00
0.76
100
0
095
A4
0.95
0.25
0.07
2.18i
2.26
3
97
0.2?
A5
0,95
0.25
0.31
0.001
0.31
100
0
095
A6
0.95
0.25
0.09
1.70
1.79
5
95
029
A7
0.95
0.25
0.45
2.06
2.51
18
82
0.38
A8
0.95
0.25
0.19
0.03
0.22
88
12
686
A9
0.95
0.25
0.13
0.03
0.15
83'
17
0.83
A10
0.95
0.25
0.16
0.03
0.19
86
14
0.85
All
0.95
0.25
0.22
2.18
2.40
9
91
0.31
B2
B3
0.95
0.95
0.25
0.25
0.30
0.66
L35
0.95
1.81
31
25
69
0.47
0.43
0.46
75
B4
0.95
0.25
0.23
0321
0.55
42
58
0.54
B5
0.95
0.25
0.07
0.18
0.25
27
73
0."
B6
0.95
0.25
0.19
0.60
0.79
24
76
0.42
B7
0,95
0.25
0.19
0.47
0.66
28
72
0.45
CI
0.95
0.25
0.75
0.27
1.02
74
26
0.77
C2
0.95
0.25
0.05
1.57
L62
3
97
0.27
C3
0.95
0.25
0.29
L68
1.97
15
85
0.35
C4
0,95
0.25
0.00
0,69
0,69
0
1201
0.25
OS -A
0.95
0.25
0.57
1.68
2,251
261
74
0.43
STTE L
6.35 17.99 24.24' 261
74 0.43
c
B. SMITH
12:48 PM6/17/2014 APPROVED BASIN COMPOSITE -MINOR AMENDMENT.xls MARTIN/MARTIN INC.
I.
'
HYDRA ULIC AND LOW IMPACT DEVELOPMENT
COMPUTATIONS
HGL AND EGL CALCULATIONS FOR PROPOSED SEWER
CONCRETE CHANNEL CAPACITY
ROCK BOX OUTLET RATING
LEVEL SPREADER WEIR CALCULATION
LID GRASS BUFFER
f
UD GRASS SWALE
L
I
HYDRAULIC AND LOW IMPACT DEVELOPMENT COMPUTATIONS:
EXCERPT FROM BUILDING 4 CONSTRUCTION PLANS USED TO DETERMINE PROPOSED STORM LINE A HGL AT TIE-IN
C
L
L
11'+ e' DUE AND 6' DATE wLLE is DE
°TA'�iwn ai•-eaopl4•.
�O ABAVDOxEO E IN PLACE IS INSTALLED
N IM05.0.1TN
1.11221-1111
I® 10' EW WAS ENDED .. ICS)SHS,
E 1031E.OI AND DUMP YJ CAP WAS
IBs'ALLEo.1(NC TEES HSTALLEo)
�� n
11 12'IN-LINE CAiE VALSE 3' WEST OF
- x..n.
13'. fi TEE O H 10505,00. E 1127439
EINIRAI NOTES
A. THE TYPE, SIM LOCATION. AND NUMBER DIE
ALL KNOWN UNDERGROUND UTILITIES ARE
APPROMMATE AS SIOW11 OR ME DRAWINGS.
IT SMALL BE ME RESPMSBIUTY OF THE
CONTRACTOR TO KRIh ME ETTENCE AND
LOCATON OF AL UNDERGROUND UTUTES
ALONG THE ROUIE 01 THE WORN BEUXE
COMMENONL NEW CONSTRUCTION.
B. REFER 70 SHEETS SPCE0741 FOR SIWM
ORAN DETAIL$.
C. AIL WATERWIES ARE TD HAVE A MR MUM
C.AR CG A5 FEET AND A MAXIMUM COWER
BE 5.5 FEET. UNLESS OTHERWISE NOTED.
D. THRUST BLOCKS REQUIRED AT ALL BENDS
TEES. M"J HYDRANTS PER DETAIL SHEET
SPCE76]R.
E. ALL UNES, VALKS. HYDRANTS AND nTDNOS
USED FOR EIRE USES SMALL BE FACTOPY
MUTUAL ADPROVEO.
F. VALIES ON 10" FIRE LINES SHALL HE
EQUIPPED WITH FACTORY MUTUAL AePROVEO
IxDILAIpt POST AT LOCATIONS BxOWN'.
MUELLER CO. A-2CR01. OR WATFROUS A240.
D. ALL WATER MAINS TO BE DUCTILE IRON PIPE
WITH POLYWRAP OR POLYETHYLENE TUBE
INSTALLED PER MANUFACTURER'6
RECWMEM.OACCR S.
N. ALL NEW UTLI71E5 SHOWN TERMINATE x5'
FROM BULDW+ ENYELCPE. REFER i0
MEMAHICAL PLAN (FUTURE BID DACNACE)
FOR CONTNUATION.
J. REFER TO SPCE7622 FOR TELECOM/LSS
TRENCH DETAIILLSS.
L A S" uN u'UM RADIUS SWEEP. UTILIZEIOUTILIZEY.
ALL TELEASS HANOHOLES M BE 22'.31 .1A.S'
FIBERpISS-REINFOACEo BCTTOREEM
ENCLOSURES (GEPt.T-INdAHAM PART
ND.9S50 OR APPROK ECUIVµFNT).
'J. ALL NE% FIRE HYDRANTS ME WAIERWS PACER
AQBEEN
MODEL W667F FIRE HYDRANTS. THESE HYDRANTS
CLOCKMY (RIGHT).
P SEE ALSO IXUWNO SP— 7DO0.
SITE, Now,
0 (4) 4- PYS CONDUITS AND (3) 1-1/2' RICK
STEEL CCNDIUITS,
z p) f EVC CONDUITS.
(1) 1-1/2' ROD STEEL CONDUITS,
A (3) 1-1/2' RIGHT STEEL CONEDITS
5 (E) 1-I/2' fiOID S1EE-
6 EXISTING (H) A' PE COM DK CONDUITS
7 (:) i Pvc CONDUIT.
B DEMOLEH EXISTND A' NO PIPE LINE BY
REMOVING PIPE FROM MENCN. BACKHWNG
AND COMPACTING TO 90% MAXIMUM DRY
DEPUTY. DEMOLHSHED PIPE SHALL BE REMOVED
QFROM
ME SITE.
5
UTILITIES NOT INSTALLED
'Am
2 AN IT"
r I/ee
W LA
A
n1"A
m mALA
mpry
u/ fne IT
m/w/w
NO REMVON ON ISSUE DATE dv
114HEWLETT
18:3 PACKARD
FORT COLLINS
WAXE
I, PAT H=H °ml'
ICED GENESIS IV
BUILDING 4
FORT COLLINS COLORADO
1
THIS !DE EASURE
]NE (HOP, THIS BRAIARD
IS NOT TO SCALE
GENESIS IV - CIVIL
OVERALL
"a22-1
SITE UTILITY PLAN
I-B0000-922-1987
N534-6700a`
DRAWNH' m--�-
�pL��•6�Cq^
ORAWNL NUMBER:
SP--CE-
HYDRAULIC AND LOW IMPACT DEVELOPMENT COMPUTATIONS.
EXCERPT FROM BUILDING 4 CONSTRUCTION PLANS USED TO DETERMINE PROPOSED STORM LINE A HGL AT TIE-IN
�P w�
.830
CLASS 12 RIPRAP 2 FT
OUR MON EXTEND 2 FT
ON
EACH EIDE OF CONCRE
APRON USE 1 FI THICK
TYPE --LTER .920
MAIN AL
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.910
GAIT/N 6/dP
.�RDD
1.00 2.CO 3.00 ..W 5.00 5.00 1.00 B.. 9.w 10+00 11.00 12.00 13.DO 14.00
b.
100-YR HGL =17.25 (SCALED)
a
s� � � s
�n7e
NOTE: PIPES SNALL HAYS A PRESSURE
SEAL RCP JONT SEALS SHALL COMPLY
80
8
Z�' 0
=a
_,
.Pi
.91
CLASS 11 RIPRAP 2
DEEP IMON EMEND
ON EACH SIDE CF CI
APRON USE I FT Tw
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NO NEYISION OP ISSUE DATE BY
114HEWLETT
,191 PACKARD
FORT COLLINS '
ICBD GENESIS IV
BUILDING 4
FORT COLLINS COLORADO
GENESIS IV - CIVIL
STORM DRAIN PROFILES (1)
THIS RECORD DRAMNDS HAS BEEN PREPANED.
IN PART ON THE BARS OF INFORMATION COMPILEDAND
'
IN"N" APW DRAFTED OR ENTERED INTO THE
DRAMNGS BY OTHERS MIS MCptD ORAMNG
MAY NOT REPRESENT IN DETAIL THE E%ACT LOCATION.
TYPE O- COMPONENT. MANNER ON EXTENT C£
CONSTRUCTION COMPLETED TO PUT NE PNOFCT
¢xi[e
1'-BOO-922-1987
ti wre uu- AS BN'.
M" uo SPCED]AI
ON ."III COLD SHELL+). IOC :S NOT RESPONSIBLE
DRAMNG ...BER'.
FOR ERRORS OR WISSOiS MNCH MAY HAVE BEEN
INADKRTENTLY INCORPORATED INTO NIS RECORD
' w534-6700•.w
rya
yw—y
SPCE0741
[TRAINING.
1
1
1
1
1
i
1
1
24" X 38" HERCP
STORMLINE A 100-YEAR STORMCAD
ST MH #A.1-2 PIPE 2 EXISTING 33" RCP - 2
ST MH #A.1-3 EXISTING
ST MH #1
v_
v �
rn
ST MH #A.1-1
w
PIPE 5
ST INLET #2
ST INLET #A.3-1
EXISTING MANHOLE'ST MH2'
n
RCP-1
STORMLINE B 100-YEAR STORMCAD
ST INLET #3
-o
rn
EXISTING 12" DIP TIE-IN
I
100-YEAR STORMCAD RESULTS
Conduit FlexTable: Combined Pipe/Node Report (AVAGO STORMCAD_MINOR AMENDMENT.stc) ,
Label Total Flow Length (User Velocity Invert Invert Slope Elevation Elevation Hydraulic Grade Hydraulic Grade Energy Grade Energy Grade
(ft3)S) Defined) (Average) (Upstream) (Downstream) (ft/ft) Ground (Start) Ground (Stop) Line (In) Line (Out) Line (In Link) Line (Out Link)
(ft) (ft/s) (ft) (ft) (ft) (ft) (ft) (ft) (ft) (ft)
EXISTING 33" RCP - 1
24.37
140.0
4.10
4,914.91
4,914.30
0.004
4,920.66
4,922.70
4,917.80
4,917.50
4,918.06
{ 4,917.76
EXISTING 33" RCP - 2
23.37
88.8
3.93
4,915.30
4,914.91
0.004
4,920.38
4,920.66
4,918.13
4,917.95
4,918.37
4,918.19
PIPE 1
1.00
66.3
1.27
4,915.24
4,914.91
0.005
4,919.50
4,920.66
4,918.01
4,917.95
4,918.03
4,917.98
PIPE 2
23.37
30.4
4.76
4,915.70
4,915.59
0.004
4,920.75
4,920.38
4,918.35
4,918.25
4,918.70
4,918.60
PIPE 3
23.37
67.3
4.34
4,915.94
4,915.70
O.OD4
4,920.16
4,920.75
4,918.85
4,918.63
4,919.19
4,918.97
PIPE 4
22.37
68.2
4.16
4,916.18
4,915.94
0.004
4,916.18
4,920.16
4,919.37
4,919.16
4,919.68
4,919.47
PIPE 5
1.00
30.0
0.81
4,916.23
4,915.94
0.010
4,919.50
4,920.16
4,919.17
4,919.16
4,919.18
4,919.17
PIPE 6
3.27
39.8
4.16
4,912.63
4,912.43
0.005
4,914.10
4,914.72
4,917.94
4,917.65
4,918.21
4,917.92
Bentley StormCAD VBi (SELECTseries 2)
AVAGO STORMCAD_MINOR AMENDMENT.stc Bentley Systems, Inc. Haestad Methods Solution Center [08.11.02.35]
6/17/2014 27 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 Page 1 of 1
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I
STORMLINE A.2 -100-YEAR STORMCAD RESULTS
4,925.00
4,920.00
4,915.00
4,910.00
-0+50
ST MH #1
Rim: 4,920.66 ft
Invert 4.914.91 ft
ST INLET #
Rim: 4,919.
Invert 4,91
PIPE 1: 66.3 ft @ 0-�?
Gimular Pipe -12.0 in Ckmaete
ft/R
0+00
Station (ft)
0+50
r
r0 ft
.24 ft
1+00
w.
W
STORMLINE A.3 -100-YEAR STORMCAD RESULTS
4,925.00
4,920.00
42915.00
ST INLET #X3-1
Rim_ 4,919.50It
Invert 4,91623 It
ST
Rim:
Inv
PIPE 5130.0
Ocular
Tuft
ft C& 0.010
l
H #Al-1
1,920.16 It
4,915.94 It
tae
-0+50 0+00 0+50
Station (ft)
STORMLINE B -100-YEAR STORMCAD RESULTS
W
4,920.00
4,915.00
4.910.00
ST INLET #3
Rim: 4,914.10 It
Invert 4,912.63 ft
PIPE
6: 39.8 ft @ 0.005 ft/ft
Circular
ipe - 12.0 in Ductile Iron
-0+50 0+00
Station (ft)
*BASINB WILL OVERFLOWSOUTHA TAN ELEVATION OF 17.65
EXISTING 12" DIP TIE-IN
-Rim: 4,914.72 ft
Invert 4,912.43 ft
0+50
'
HYDRAULIC CALCULATIONS- CONCRETE CHANNEL CAPACITY
CONCRETE CHANNEL CAPACITY
Project Description
Friction Method Manning Formula
'
Solve For Discharge
Input Data
Roughness Coefficient 0.013
Channel Slope 0.00500 ft/ft
Normal Depth 0.50 It
Bottom VVidth 3.00 ft
Rating Curve Plot
W orksheet: Rectangular Channel -1
Discharge (fNls)vsChannel Slope(fbl)
.......
26 .. ......... ......... ......... ........ ......... ......... ........ .........
24....... ............. ........................... ............ ............ ........ ........
'
_ 22....... t........................ ............................. ........ ......... ........ .........
620 .. ......... ......... ......... ..... ........ ......... ......... ........ ......... �
18 .........
s16 .................................. ...... ........ ......... ........................... ........ ........
0 oi i ........ ......... ......... ......... ........ .........
14 .... ..:................... ................. ....
12 ... ......... ......... ........ ........ ........................... ...........................
max100 yr
1g .... .. ......... ......... ........ ......... ......... ....... ........ i� ... .:. . .. ..:.. ..;..
discharge =
6
7.61 cfs
am _W o_aa 0.04 0.05 0.0s 0.07 0.08 0.09 0.1
'
Channel Slope(ftM)
Ti
min slope =1.5%
' THE PROPOSED CONCRETE CHANNELS HAVE ADEQUATE CAPACITY TO CONVEY THE
100-YR DEVELOPED FLOW
Bentley Systems, Inc. Haested Methods Sol916atldpf4aMaster V8i (SELECTseries 1) (08.11.01.031
3122/2013 4:39:06 PM 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 Page 1 of 1
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HYDRAULIC AND LOW IMPACT DEVELOPMENT COMPUTATIONS -ROCK BOX
A
3.50'(H) X 3.0T
1/4'(T) GAL%
STEEL PLATE TO DIRECT
DOWNWARD TOWARI
BOLT TO OUTSIDE OF BO
i' ANCHOR BOLTS O 1
(NOT SHOWN ON SECIOI
3' CONCRETE PAN WITH 6'
50
{—
I
I ..Fp.r�
X
1/4-() X GALVAN3.00 IZED
1/4'(1) GALVANIZED
STEEL PLATE WITH WATER
i..: •
OIW.fTY ORIFICES AS SHOWN
6'0 RIVER COBBLE
%.
i
-.
BOLT TO INSIDE OF BOX WITH
9- THICK (IYP.)
; "a
50'
1.10'
,SO'
i `
Jr ANCHOR BOLTS O 6' O.C.
•
�e
. •-,
CDOT TYPE O BOX
G�1`
l
0.25' .32'
-fit^ 1'-'1 (?�"
0 0 0 0 o
I
2' CRUSHED ROCK
'.•'
i'>'�
_
0 0 0 0 0 0 0
0 0 0 0 0 0 0
-
GRADE FLUSH WITH TOP OF CURB
1
I
-
0 0 0 0 0 o O
0 0 0 0 %2I'q
r2.90'I
0.25
t
0 0 0 0 0 0 0
1
0 0 0 0 0 0 0
--t__-I I__I_r----.
iith---
--
--1� �I �I
__ IIi---r _
L._I
O O O O O O O
y11-1
___ _
-
iIiI-iI_-1 -1-1 I1 II -I_- _
III _1I1_11I
-
'� i i -I _1 .1L11
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IITiI)-11TTTI1IT•
I --I t 1-- .• �
0 0 0 0 0 0 0
G.DB'
ol
I 1 1
IIIITiI-L!
Ili11411i11.LT
lL1.Tl111iT-ITiI Ii_
114__I
1 III -1 111.__I
I IC__--
I I
-i _-_-_' :•••
0 0 0 0 0
.I
iI1I-
"1
1
4: • • M•"
i __
-1 I -1 11---4
I I___I I I--.1!
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HYDRAULIC AND LOW IMPACT DEVELOPMENT COMPUTATIONS -ROCK BOX OUTLET RATING
ROCK BOX - RATING CURVE FOR 100-YR WEIR
Project Description
Solve For Discharge
Input Data
Headwater Elevation
4.00
ft
Crest Elevation
2.90
ft
Tailwater Elevation
0.00
ft
WeirCoefrcient
3.00
US
Crest Length
2.00
ft
Number Of Contractions 0
Rating Curve Plot
6.5
6
5.5
_ 5
` 4
�.5
U 3
®Jt.S
Q
2
t.5
0.5
0
2.9
Worksheet: RectangularWeir-i
Discharge (ftl,s ) vs Headwater Elevation M
3 3.1 32 3.3 3.4 15 7 3.8 3.9
Headwater Elevation (fti
Bentley Systems, Inc. Haestad Methods Sol9badd;eFbwMaster V8i (SELECTseries 1) [08.11.01.03]
312212013 1:19:17 PM 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 Page 1 of 1
HYDRAULIC AND LOW IMPACT DEVELOPMENT COMPUTATIONS -ROCK BOX OUTLET RATING
ROCK BOX - RATING CURVE FOR WATER QUALITY PLATE
Project Description
Solve For Discharge
Input Data
Headwater Elevation
4.00
ft
Centroid Elevation
0.08
ft
Tailwater Elevation
0.00
ft
Discharge Coefficient
0.60
Opening Area
2.75
in'
Rating Curve Plot
0.18
0.16
0.14
D.12
LM 0.1
to
0.08
a
0.06
0.D4
D.D2
Aarksheet Gen encOrifice- t
Discharge (ft1,1s.1 vs Headwater Elevation iftj varying Centro id Elerdon (ft)
r "
u•�•is I
• iro
Yi
a^
• • i
i
a a
r
t5 2.6 3 3.5
Headwater Elevation (ft)
ORIFICE DIAMETER:
1 00 814
AREA:
0 79 IIN"2
HOLESIROW:
700
EFFECTIVE AREA:
5 50 IW2
CLOGGING
50%
EFFECTIVE OPEN AREA:
2 75 N 2
USE 11 ROWS I " DIAMETER HOLES WITH 7 HOLES PER ROW
4
♦ 0.36 ft
wo R1
• 0 33 ft
Wry 92
• C 5a ft
WO 83
•
WE) 94
0
wo 95
♦ .``
Wr?f6
♦ 1 53 ft
INQ 97
u
•206ft
Wps9
• 2.33ft
IM7910
•I
WOr11
Bentley Systems, Inc. Haestad Methods So19Bodd;4 lawMaster V8i (SELECTseries 1) [08.11.01.03]
3/2212013 1:20:30 PM 27 Siemens Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 Page 1 of 1
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HYDRAULIC AND LOW IMPACT DEVELOPMENT COMPUTATIONS -ROCK BOX OUTLET RATING
ROCK BOX COMBINED OUTLET RATING DATA
WSEL
WO/
W02 .W03
W04 Was
was
W07
WOO
Was
W010
WO 11
WEp
00MP0617E
1.40_
S.45
0.00 _ _
0.00
_
_
1.10
0.013
0.01
8.16
0.021319
0.02
02a
0.03194'
0.03
11.25
0.037806
0.04
Sao
o.a3+1z
0.SS
Sac
0_S4n01 40129
OA9
OAS
0.051995: 0.0243+
a.OE
Los
0.05591� D.o318/
a.m
LOS
0378
0.059568� 0J0.047781
-
-
a.Is
am
0.083014112
0.11
too
0.08028118i 0.012999
- -
0.13
Las
0.0593959 0.02431
-
-
0.15
0.70
0.0tt37/591 0.0]1B4
0.16
0.75
0.0752 58E 0.037
0.17
too
0.077993014 0.04311
6.15
OAS
0.90
0. 281 0.04n01 0.012909
0.00323 395 0.051995 OA24319
0.21
023
0.9E
O.OS573 374 0.05591 0.03164
8.25
too
SA88+6 236 0.059508 0.03789E
6.26
1.05
0.090526993 0A83014 0.043M
- -
8.27
1.10
0.092830.086281 0.0477610.012099
0.30
1.15
0195072 0.063233 0.069395 405105' 0.024319
Eat
1.24
0,097274 OA85733 0.072374 0.05511 0.03184
0.34
125
0.090422 0.068152 0.075236 0.059568 0.037898
0.36
1.30
0,10IS24 0.=526 O.On993 0.083014 O.0/3112
0.2E
1.35
0.103584 0.092a3 0,080656 0.066281 O.O47761
0.012029
0.40
1.40
OAOS603 0.09SO75 0.093233 OMO395 0.051905
0.024319
OAS
1.46
O.ID7 4097274 0.085733 0,072374. 0.05591
0.03134
OAS
1.69
OADOS3 0.099422 0,088182 0.075236 0.059558
0.037898
8.47
1.55
0,111"2 0101524 0.090520 0.077993' 0.083014
0.043112
OAS
1.so
0,113321 0.1035" 0DOM 0.080656 0.055281
0.047761
0012009
OA2
1.45
0.11617 0.105503 0.09507a 0.083233 0.069395
0.05t995
0.024312
9.64
t.io - -
0.116949 D.taT584 0.097274 o.oesf33: D.ott374
0.1118781 - 0.1095 o1090422 0.06816 D.075236
0.05591 0.03154
6A7
1.75
0.059568 0.037898
os9
1AO
SAMS4 0.111442 0.101524 0.090526 O.On993
0.0a3M 0.043112
0.61
LOS
0.127286 0.113321 0.103584 0.092a3 0-080658
0.086281 0.047761 0.012099
a."
1.90
0.124001 DAIM7 0.105603 0.005078 0.083233
0.089395 0.051995 0.024319
0.67
1.115
OA258 0.116989. OAO7564 0.097274 0.055733
0.072374 0.06591 0.031
0.69
Loa
0.12736 0.118791 0.10953 0.099422 00.088192
0A75238 0.059569 0.037698
0.72
Los
0,12901 0.120546 0.111442 0.101524 0.090526
0.07799 0.06M14 0.043112
0.74
L10
0.13083 0.122288 0.113321 0.103581 O:U9283
0.080858 O.OB8281 0.04n61
0.012999
O.n
L16
0.13224 0.124001 0.11517 0.105603 0.095078
0,083233 0.069305 O.DSMS
0.024319
0.10
220
0.133931 0.125693 0.116980 0.107584 0.097274
0.1354 0.127362 0.118781 0.16953 06-N422
0.065733 0.072374 D.05591
0.03154
OA3
L25
0.08318 0.075235 OA59568
0.090526 0.077993 0.063014
OA37898
0.043112
OAS
9.87
2a0
0.136951 0.12901 0.120546 0.111442 0,101524
2.36
0.13M8 0.170837 0.122296 0.11 332i 0.1035a!
0.11 0.132243 0.124001 0.11517 0,105603
0.141602 D.133831 0.125693, 0.116989 0.107584
0.09283 0.0E0858 0.08020f
O.OQ701
0.012999
_..
8.81
2AO
0_025078 0.083233 0.062305
0.051995
0.024319
0.94
2AS
0.007274 0.086733 0.072374
0.099423 0.088182 0.075296
0.05591
0.058588
0.03184
0.037898
9.97
0.09
t.b9
0.1420117 O.I35/ 0.127702 0.115791 0.10951
2.00
0.14445 0.136951 0.12907 0.120545 0.111442
0.115911 0.13640.5 0.130637 0.12n86_0.113321
0.101524 0.0905 0.0n993
0.163584 0.09293 0.080556
0.063014
0.043112
1.02
LOS
0ASU81
0.04n61 0.012M
1.06
2.66
0.14735 0.14DO02 0.132243 0.124001 0.11517
0.105601 0.095078 OA83233
0_069395
0.051995 0.02431
1."
L70
0.14877 0.141602 0.133531 0.125693 0.116989
OAO7584 0.097274 0.085733
0.072314
0.D5591 0.03184
1.12
LIS
0.150107 0.1429a7 0.1354 0.127382' 0.11878+
0.10953 0.0a9/22 0.088162
0.075236
0.0595a O.w7ass
1.14
LIS
0.15150 0.144457 0.138951 0.12901 0.120540
0.111442 0.101524 OmO526
0.07790
0.063014 0.043112
1.17
LO6
0.15297 0.145911 0.138455 0.130637
0.122288
0,113321 0.103584 0,09283
0.080656
0.066251 0.047761
1.19
LB
0.15435 0.147352 0.140002 0.132243!
0.124001
0.11517 0.105603 0.095078
0.083233
0.059395 0.057
122
an
0.15571 MUMS 0.141502 0.1335311
0.125093
0.116989 0.107584 0.097274
0.0857n
0.072374 0055Ot 4W7082
1.31
3
0.15705 0.150191 DA42687 0.13641
0.127362
0.118761 0.1090 0.099422
0.088162
0.075236 0.059568 0IM737
1.45
3.06
0.10./51591 0.144457 0.136951
0.12907
0.120518 0.111143 0.107534
0.080526
0.077993 0.063011 Oa18569
1.87
3.1
0.1597 0.15297 0.145971 0.19M85
0 .130837
0.122288 0.113321 0.10.3514
0.09283
0.080856 0.065281 0.536658
1.04
Lac
0.161" 0.154352 OA47352 0.140002'
0.132243
0.124001 0.11517 0.105603
0.095078
0.063233 0.059395 0.T5
Los
]2
OAS235 0.155715 0.716778 0.141602
0.133831
0.125893 0.116989 Od07584
0.097274
0.085733 0,072374 O.9a5901
2.33
LIS
0.163651 0.157 DA50191 0.142987 0.1354
OA27362 DA18781 0.10953
0,099422
0.00182 0.075230 12423n
Lai
32
O.78499 0.158404 0.151581 0.14N5] 0.13895/
0.12901 0.120 0.111/42
0.101524
0.080536 O.On893 1.517093
L01
]AO
0.18621 0.1597 0.162978 0.145911 0.135455
0.130637 0.122286 0.113321
0.103554
Oman 0.080556 1.81121
3.22
0A
SAO34
0.16747 0.15t01 0.1543 0.147352 0.140002
0.1807 O.1fi2 0.15571 0,150191 0.142087
0.132243 0.124001 0.11517
0.1
O-OM78 A.053233 L12132
3Ac
0.137331 0.118781
O.tW584
0.097274 0.0a57 2.147
7A
0.1 0.18WSJ 4157065 0.150181 0.1/2987
OA25853
0.1351 0.127382 0.118781
0.1
0.089/22 0.0861 L7
4.25
12b
]a6
0.17121 0.18403 OAS44W 0.151591 0.144457
0.138951 0.129OL 0.1MS46
0.111442
0.101524 0.090526 3.144281
4.62
3A
0.172" 0.16921 OAS9732 0.152978 0.115911
O.t 36485 0.13063T 0.122286
0.113321
0.103584 OAS= 3.5139
SAt
LOS
0.1 0,16747 0.18104 OAS4352 0.1473521
0. 140002 0. 132243 0.124DOI
0.11517
0.10560 0.095078 3.897114
SA1
3.7
0.174651 OASS7 D. 62M 0.155715 0.14ane
0. 141502 0. 133831 0.125693
0. 142937 0.1354 0-127382
0.116989
OJD7 Om7274 4.29325t
6A3
3.75
0.1 0.1899E 0.10651 0.157005 0.150191
0.118781
0.10953 0.099422 4.701958
Lis
3.5
0.tn2 0.171 0.164937 0AS"64 0.1515910.144457 0. 136951 0.12901
0.120546
0.11144 OA01524 5.12289�
L69
OAS
0.1784 0.172N 0.166212 0.159732 0.152978, 0.145911 0.138485 0.190637
0.122286
O.1t3321 0.103584 5.555673
7.14
L!
O.i7B81 O.i7]88 0.167478 0.181D19 0.151352� 0.147352 0.1a0002 0.1322/3�
0.124001
0.71517 0.105803 8
7A0
Lac
0.15061 0.174501 MOST 0.162355 0.+5571 0.145na� 0.161502 0.13383h,
0.125693
0.115909 0.107584 aA55579
L07
4
0.1519 0.17605 0ASS14Z 0.183651 0.15700 0.150191; 0, 142987 0.1354.
0.127367
41187 11 0.10o53 5.gM1361
OAo
I
0
� M
0
a
O
0
W
O
U N
C9 G LO
Z N
H
H H
W LL
J o
jO
O N Q
W_
H
IL �Z o
U O�
� W
O
00
V o
O
O
uO
0
0
0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 O o 0
of ao r� co vi v ri �i o
(s-AO) 398VHOsia
HYDRAULIC AND LOW IMPACT DEVELOPMENT COMPUTATIONS - LEVEL SPREADER WEIR
LEVEL SPREADER WEIR
Projed Description
Solve For
Headwater Elevation
Input Data
Discharge
7.61
ft'/s
= max discharge over level spreader
Headwater Elevation
0.45
ft
= depth of flow over level spreader
Crest Elevation
0.25
ft
= 3" curb
Tailwater Elevation
0.00
ft
= bottom of curb
Crest Surface Type
Gravel
Crest Breadth
0.50
ft
= top of curb width
Crest Length
27.00
ft
Cross Section Image
+t 00' +1.00'
+0.45' (depth of flow over weir = 0.20')
650ft 27.00ft 6.50ft�
Headv,later HeOtAbDve Crest
02p
ft
ail'water Height.Abarre Crest
-02
ft
IN& Coefficient:
g 09
U5
SubrnLrgence Factor:
100
Adjusted 'a veir Ccefficie'nt
3.09
us
Flaw area:
5.47
ft1
H I
Velocity-
1.39
ft's
Vvented Perimeter
27.41
ft
TcF 'lu'iryth:
27.00
ft
Bentley Systems, Inc. Haestad Methods SoIBBoderyd'ibwMaster V8i (SELECTseries 1) [08.11.01.031
611712014 2:40:23 PM 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 Page 1 of 1
HYDRAULIC AND LOW IMPACT DEVELOPMENT COMPUTATIONS -GRASS BUFFER
I
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II Design Procedure Form: Grass Buffer (GB)
Sheet 1 of 1
Designer: BMS
Company: MARTIN/MARTIN, INC.
Date: March 22, 2013
Project: AVAGO BLDG 4 EXPANSION
Location: FORT COLLINS, CO
1. Design Discharge
A) 2-Year Peak Flow Rate of the Area Draining to the Grass Buffer
Oi = 2.0 `/- cfs
2. Minimum Width of Grass Buffer
Wo= 40 ft
3. Length of Grass Buffer (14' or greater recommended)
Ls= 15 ry DISTANCE FROM LEVEL
SPREADER TO GRASS SW'ALE
4. Buffer Slope (in the direction of flownot to exceed 0.1 It / ft)
So = 0.100 ft / ft 6ARIES
J = SL4 rIVV.v
5. Flow Characteristics (sheet or concentrated)
A) Does runoff now into the grass buffer across the
entire width of the buffer?
Choose One
Oyes No
CONCENTRATED FLOW
6. Flow Distribution for Concentrated Flows
Choose One
O None (sheet flow)
O Slotted Curbing
0 Level Spreader
O Other (Explain):
40' LEVEL SPREADER TO BE USED TO DISTRIBUTE FLOW
ACROSS GRASS BUFFER
7 Soil Preparation
(Describe soil amendment)
PER LANDSCAPE
8 Vegetation (Check the type used or describe "Other")
Choose One
O Existing xenc Turf Grass
* Irrigated Turf Grass
O Other (Explain):
9. Imgmion
('Select None it existing butter area has 80% vegetation
AND will not be disturbed during construction.)
Choose One
O Temporary
0 Permanent
Nn- eoe'
O N
10. Outflow Collecbon (Check the type used or describe "Other')
Choose One
OQ Grass Swale
O Street Guth
O Storm Sewer Inlet
O Other (Explain):
Notes:
I
JD-13MP_v3.02.xIs, GB
3/22/2013, 512 PM
Design Procedure Form: Grass Swale (GS)
Sheet 1 of 1
Designer: BMS
Company: MARTINIMARTIN, INC.
Date: June 17, 2014
Project: AVAGO BLDG 4 EXPANSION
Location: FORT COLLINS, CO
1. Design Discharge for 2-Year Return Period
Q2 =
6.41
; AR/ES, 6.4/ Af f.Y AT DP A7
2. Hydraulic Residence Time
A) : Length of Grass Swale
LS =
462.0
ft
B) Calculated Residence Time (based on design velocity below)
THR=
8.8
minutes
3. Longitudinal Slope (vertical distance per unit honzordal)
A) Available Slope (based on site constraints)
S,,,w =
0.003
ft / ft
B) Design Slope
Sc =
0.003
ft / ft
4. Swale Geometry
A) Channel Side Slopes (Z = 4 min., hodz. distance per unit vertical)
Z =
10A0
ft / ft VARIES, 10: I MAX
B) Bottom Width of Swale (enter 0 for triangular section)
We =
5.00
ft
S. Vegetation
A) Type of Planting (seed vs. sod, affects vegetal retardance factor)
Q Grass From Seed
O Grass From Sod
6. Design Velocity (1 ft / is maximum)
V, =
0.88
ft / s
7. Design Flow Depth (1 foot maximum)
D, =
0.64
ft
A) Flow Area
A, =
7.3
sq ft
B) Top Width of Swale
WT =
17.8
ft
C) Froude Number (0.50 maximum)
F =
0.24
D) Hydraulic Radius
Rh =
0.41
E) Veloaty-Hydraulic Radius Product for Vegetal Reerdance
VR =
0.36
F) Manning's n (based on SCS vegetal retardance curve E for seeded grass)
n =
0.052
G) Cumulative Height of Grade Control Structures Required
He =
0.10
ft
AN UNDERDRAIN IS
8. Underdrain
(Is an underdrain necessary?)
*YES
O NO
REQUIRED IF THE
DESIGN SLOPE < 2-0%
9. Soil Preparation
PER LANDSCAPE
(Describe soil amendment)
10. Irrigation
r
I 0 Temporary
QQ Permanent
' UD-BMP_v3.02.xls, GS 6/17/2014, 2:53 PM
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CORRESPONDENCE
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1 Bret Smith
1 From: Wes Lamarque [WLAMARQUE@fcgov.com]
Sent: Thursday, February 14, 2013 10:50 AM
To: Glen Schlueter
Cc: Peter S. Buckley
Subject: RE: Avago building addition
The report and plans are the right ones to compare the c-factors.
Wes
From: Glen Schlueter
Sent: Wednesday, February 13, 2013 3:47 PM
To: Wes Lamarque
Cc: 'PBuckley@martinmartin.com'
Subject: FW: Avago building addition
Wes,
Can you follow up on this and see if they are using the correct report and plans? The date seems close but
building 4 was under construction in the fall of 1998 when I hired Jay. He was working on building 4 so there
may be an older report. The plans are dated April of 98 so that seems right but the March 99 date must have
been a revision to a 98 report. If you find the one they show it may explain which report should rule. The plans
aren't signed but my name is printed on the signature block which is strange.
Glen
From: Peter S. Buckleyfmailto:PBucklevftmartinmartin.com]
Sent: Tuesday, February 12, 2013 5:17 PM
To: Glen Schlueter
Subject: RE: Avago building addition
Glen,
We are planning on comparing back to the approved "HP Building 4 — revision' drainage report — see attached for
the plans from what I understand to be the approved report. We will compare what is actually going to be out
there after the Building 4 addition with what this report was showing. I think we are on the same page. Can you
confirm that the attached report cover and plans is the approved report we should compare to? Thanks.
Peter S. Buckley, PE
Senior Project Engineer
'
PE (CO)
Martin/Martin, Inc.
12419 W. Colfax Ave., Lakewood, CO 80215
'
P) 303-431-6100 Ext. 246
www.martinmartin.com
From: Glen Schlueter [mailto:GSCHLUETER@fcgov.coml
Sent: Tuesday, February 12, 2013 5:01 PM
To: Peter S. Buckley
ISubject: Avago building addition
1 3/25/2013
[1
Page 2 of 2
iPeter,
Basil Harridan said you had questions about the drainage as well as the water quality requirements that you
asked him about. Specifically he mentioned the impervious area. As I mentioned at the conceptual review
meeting your drainage design engineer needs to compare the new impervious area to the approved plan and
see if additional detention is needed. I don't think you can go by what it onsite because as you mentioned the
ring road and parking lots were not what was approved. The large asphalt staging area and ring road that
moved are probably more than the approved impervious area, but I can't tell for sure.
Give me a call if you or your engineer have questions about this.
Glen
Stormwater Development Manager
224-6065
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I
11
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'' 3/25/2013
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PngIECT NUMBER. tYs.Nt
V/N PROER FIZDNI
No. Description
1 MINOR AMENDMENT
2
3
4
Date
05.12.14
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06.14.13
Drawn By
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Checked By
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SHEET NO.
D100
Scale AS SHOWN