HomeMy WebLinkAboutRevised Stormwater Design Report Reduced - Part 2 08-05-2020APPENDIX D
DESIGN CALCULATIONS
TD&H Engineering
Arrowleaf Park and Perennial Park
B19-006
7/23/2020
Rainfall Intensity:3.83 in/hr (25 year event)
Weighted Runoff Coefficient (C):0.8
Angle of Maximum Discharge:151.2 Degrees
0.013 RCP
(Rational Method)
PIPE Contributing
Area to
Catch Basin
Pipe (acre)
Culvert
inflow
(cfs)
Culvert
Diameter
(in)
Inlet Invert
Elevation
(ft)
Outlet
Invert
Elevation
(ft)
Culvert
Length
(ft)
Culvert
Slope
(ft/ft)
Depth at
Max
Discharge
Rate (in)
Area At
Max
Discharge
Rate (sf)
Hydraulic
Radius
(ft)
Storm
Pipe Max
Discharge
Rate (cfs)
Is Pipe
Capable
of Flow?
Velocity
(Q/A)
(ft/s)
1A 0.101 0.31 15 4730.17 4730.02 103.9 0.0014 14.07 1.20 0.36 2.64 yes 2.15
1B 0.463 1.73 15 4730.02 4729.66 180 0.0020 14.07 1.20 0.36 3.11 yes 2.53
1C 0.688 3.84 21 4729.26 4728.97 144.2 0.0020 19.70 2.34 0.51 7.64 yes 3.18
1D 0.553 5.53 24 4728.77 4728.7 60.3 0.0012 22.51 3.06 0.58 8.29 yes 2.64
1E 0.516 7.11 24 4728.7 4728.58 91.6 0.0013 22.51 3.06 0.58 8.81 yes 2.81
1F 0.000 7.11 30 4728.58 4728.5 50.9 0.0016 28.14 4.78 0.73 17.49 yes 3.57
Diameter Angle
Radiu
Depth
TD&H Engineering
Arrowleaf Park and Perennial Park
B19-006
7/23/2020
Rainfall Intensity:3.83 in/hr (25 year event)
Weighted Runoff Coefficient (C):0.8
Angle of Maximum Discharge:151.2 Degrees
0.013 RCP
(Rational Method)
PIPE Contributing
Area to
Catch Basin
Pipe (acre)
Culvert
inflow
(cfs)
Culvert
Diameter
(in)
Inlet Invert
Elevation
(ft)
Outlet
Invert
Elevation
(ft)
Culvert
Length
(ft)
Culvert
Slope
(ft/ft)
Depth at
Max
Discharge
Rate (in)
Area At
Max
Discharge
Rate (sf)
Hydraulic
Radius
(ft)
Storm Pipe
Max
Discharge
Rate (cfs)
Is Pipe
Capable
of Flow?
Velocity
(Q/A)
(ft/s)
2A 0.978 3.00 15 4730.59 4730.42 66.5 0.0026 14.07 1.20 0.36 3.51 yes 2.86
2B 0.406 4.24 18 4730.22 4729.79 155.1 0.0028 16.88 1.72 0.44 5.95 yes 3.37
2C 0.489 5.74 21 4729.59 4729.35 157 0.0015 19.70 2.34 0.51 6.66 yes 2.77
2D 0.862 8.38 24 4729.15 4728.97 90 0.0020 22.51 3.06 0.58 10.88 yes 3.47
2E 0.371 9.52 30 4728.77 4728.73 49.5 0.0008 28.14 4.78 0.73 12.54 yes 2.56
2E.1 0.000 9.52 30 4728.73 4728.57 162.5 0.0010 28.14 4.78 0.73 13.84 yes 2.82
2F 1.269 13.41 30 4728.57 4728.5 60 0.0012 28.14 4.78 0.73 15.07 yes 3.07
2G 0.498 1.53 15 4728.55 4728.5 35.1 0.0014 14.07 1.20 0.36 2.62 yes 2.14
Diameter Angle
Radiu
Depth
TD&H Engineering
Arrowleaf Park and Perennial Park
B19-006
7/23/2020
Rainfall Intensity:3.83 in/hr (25 year event)
Weighted Runoff Coefficient (C):0.8
Angle of Maximum Discharge:151.2 Degrees
0.013 RCP
(Rational Method)
PIPE Contributing
Area to
Catch Basin
Pipe (acre)
Culvert
inflow
(cfs)
Culvert
Diameter
(in)
Inlet Invert
Elevation
(ft)
Outlet
Invert
Elevation
(ft)
Culvert
Length
(ft)
Culvert
Slope
(ft/ft)
Depth at
Max
Discharge
Rate (in)
Area At
Max
Discharge
Rate (sf)
Hydraulic
Radius (ft)
Storm
Pipe Max
Discharge
Rate (cfs)
Is Pipe
Capable
of Flow?
Velocity
(Q/A)
(ft/s)
3A 0.367 1.12 15 4735.8 4735.76 14.5 0.0028 14.07 1.20 0.36 3.65 yes 2.98
3B 0.000 1.12 15 4735.66 4735.25 171.25 0.0024 14.07 1.20 0.36 3.40 yes 2.77
3C 0.000 1.12 15 4735.25 4734.75 145.1 0.0034 14.07 1.20 0.36 4.08 yes 3.33
Diameter Angle
Radiu
Depth
Arrowleaf Park and Perennial Park 5/4/2020
C Value Determination
Basin 1
Sub-
Basin
Pavement
Area (sf)
Sidewalk
Area (sf)
Roof
Area (sf)
Lawn/
Landscaped
Area (sf)
Un-
improved
Areas (sf)
Total
Area (sf)
Paved/
Hard
Surfaces
C
Gravel
Surfaces
C
Lawn/
Landscaping
C
Un-
improved
Areas C
Weighted
Average C
C AVG
1A 2,648 766 0 979 0 4,393 0.9 0.8 0.1 0.2 0.72
1B 5,491 3,106 8,808 2,765 0 20,170 0.9 0.8 0.1 0.2 0.79
1C 10,540 3,574 9,809 6,043 0 29,966 0.9 0.8 0.1 0.2 0.74
1D 8,223 2,817 6,182 6,855 0 24,077 0.9 0.8 0.1 0.2 0.67
1E 7,876 1,816 5,187 7,588 0 22,467 0.9 0.8 0.1 0.2 0.63
Total 34,778 12,079 29,986 24,230 0 101,073 0.9 0.8 0.1 0.2 0.71
Total Impervious Area:76,843 sf
1st 1/2 Inch from Impervious Area:3,202 cf
Basin 2
Sub-
Basin
Pavement
Area (sf)
Sidewalk
Area (sf)
Roof
Area (sf)
Lawn/
Landscaped
Area (sf)
Un-
improved
Areas (sf)
Total
Area (sf)
Paved/
Hard
Surfaces
C
Gravel
Surfaces
C
Lawn/
Landscaping
C
Unimproved
Areas C
Weighted
Average C
C AVG
2A 17,128 4,144 10,377 10,957 0 42,606 0.9 0.8 0.1 0.2 0.69
2B 9,909 904 2,943 3,930 0 17,686 0.9 0.8 0.1 0.2 0.72
2C 9,466 1,157 4,120 6,566 0 21,309 0.9 0.8 0.1 0.2 0.65
2D 8,258 3,431 12,576 13,120 0 37,385 0.9 0.8 0.1 0.2 0.62
2E 5,207 1,975 1,931 7,045 0 16,158 0.9 0.8 0.1 0.2 0.55
2F 16,881 4,520 14,847 19,090 0 55,338 0.9 0.8 0.1 0.2 0.62
2G 8,949 1,504 5,187 6,051 0 21,691 0.9 0.8 0.1 0.2 0.68
Total 75,798 17,635 51,981 66,759 0 212,173 0.9 0.8 0.1 0.2 0.65
Total Impervious Area:145,414 sf
1st 1/2 Inch from Impervious Area:6,059 cf
Basin 3
Sub-
Basin
Pavement
Area (sf)
Sidewalk
Area (sf)
Roof
Area (sf)
Lawn/
Landscaped
Area (sf)
Un-
improved
Areas (sf)
Total
Area (sf)
Paved/
Hard
Surfaces
C
Gravel
Surfaces
C
Lawn/
Landscaping
C
Unimproved
Areas C
Weighted
Average C
C AVG
3A 28,735 7,495 11,587 23,924 0 71,741 0.9 0.8 0.1 0.2 0.63
3B 10,308 2,633 0 3,037 0 15,978 0.9 0.8 0.1 0.2 0.75
Total 39,043 10,128 11,587 26,961 0 87,719 0.9 0.8 0.1 0.2 0.65
Total Impervious Area:60,758 sf
1st 1/2 Inch from Impervious Area:2,532 cf
Basin 4
Sub-
Basin
Pavement
Area (sf)
Sidewalk
Area (sf)
Roof
Area (sf)
Lawn/
Landscaped
Area (sf)
Un-
improved
Areas (sf)
Total
Area (sf)
Paved/
Hard
Surfaces
C
Gravel
Surfaces
C
Lawn/
Landscaping
C
Unimproved
Areas C
Weighted
Average C
C AVG
4 0 4,765 36,012 9,902 0 50,679 0.9 0.8 0.1 0.2 0.74
Total 0 4,765 36,012 9,902 0 50,679 0.9 0.8 0.1 0.2 0.74
Total Impervious Area:40,777 sf
1st 1/2 Inch from Impervious Area:1,700 cf
Arrowleaf Park and Perennial Park 5/4/2020
C Value Determination
Basin (ALL)
Sub-
Basin
Pavement
Area (sf)
Sidewalk
Area (sf)
Roof
Area (sf)
Lawn/
Landscaped
Area (sf)
Un-
improved
Areas (sf)
Total
Area (sf)
Paved/
Hard
Surfaces
C
Gravel
Surfaces
C
Lawn/
Landscaping
C
Unimproved
Areas C
Weighted
Average C
C AVG
1 34,778 12,079 29,986 24,230 0 101,073 0.9 0.8 0.1 0.2 0.71
2 75,798 17,635 51,981 66,759 0 212,173 0.9 0.8 0.1 0.2 0.65
3 39,043 10,128 11,587 26,961 0 87,719 0.9 0.8 0.1 0.2 0.65
4 0 4,765 36,012 9,902 0 50,679 0.9 0.8 0.1 0.2 0.74
Total 149,619 39,842 93,554 117,950 0 400,965 0.9 0.8 0.1 0.2 0.66
Arrowleaf Park and Perennial Park 5/4/2020
10-year Flow Calcs
C
Area
(ac)
Tc*
Total
(min)
Tc*
Total
(hour)
10 yr
i
(in/hr)
Flow
Q
(cfs)
PostBASIN1 0.71 2.32 10.75 0.179 1.956 3.21
PostBASIN2 0.65 4.87 13.11 0.218 1.720 5.43
PostBASIN3 0.65 2.01 10.23 0.170 2.021 2.66
Slope
(%)
Distance
(ft)C
t1
(min)Slope (%)k
Velocity
(fps)
Distance
(ft)t2 (min)
Velocity
(fps)
Distance
(ft)
t3
(min)
Tc* Total
(min)
PostBASIN1 2.00 150 0.9 3.6356 2.00 0.619 2.87 635 3.6859 3.00 617.80 3.43 10.75
PostBASIN2 2.00 280 0.9 4.9672 2.00 0.619 2.87 636 3.6917 3.00 800.40 4.45 13.11
PostBASIN3 2.00 250 0.9 4.6935 2.00 0.619 2.87 637 3.6975 3.00 331.00 1.84 10.23
Overland Flow Shallow/Gutter Flow Pipe Flow
TIME OF CONCENTRATION
Arrowleaf Park and Perennial Park 5/4/2020
25-year Flow Calcs
C
Area
(ac)
Tc*
Total
(min)
Tc*
Total
(hour)
25 yr
i
(in/hr)
Flow
Q
(cfs)
PostBASIN1 0.71 2.32 9.12 0.152 2.605 4.28
PostBASIN2 0.65 4.87 10.87 0.181 2.328 7.35
PostBASIN3 0.65 2.01 8.12 0.135 2.806 3.70
Slope
(%)
Distance
(ft)C
t1
(min)Slope (%)k
Velocity
(fps)
Distance
(ft)t2 (min)
Velocity
(fps)
Distance
(ft)
t3
(min)
Tc* Total
(min)
PostBASIN1 2.00 150 0.9 1.9996 2.00 0.619 2.87 635 3.6859 3.00 617.80 3.43 9.12
PostBASIN2 2.00 280 0.9 2.7319 2.00 0.619 2.87 636 3.6917 3.00 800.40 4.45 10.87
PostBASIN3 2.00 250 0.9 2.5814 2.00 0.619 2.87 637 3.6975 3.00 331.00 1.84 8.12
TIME OF CONCENTRATION
Overland Flow Shallow/Gutter Flow Pipe Flow
Arrowleaf Park and Perennial Park 5/4/2020
100-year Flow Calcs
C
Area
(ac)
Tc*
Total
(min)
Tc*
Total
(hour)
100 yr
i
(in/hr)
Flow
Q
(cfs)
PostBASIN1 0.71 2.32 7.48 0.125 4.075 6.70
PostBASIN2 0.65 4.87 8.64 0.144 3.702 11.69
PostBASIN3 0.65 2.01 6.01 0.100 4.721 6.22
Slope
(%)
Distance
(ft)C
t1
(min)Slope (%)k
Velocity
(fps)
Distance
(ft)t2 (min)
Velocity
(fps)
Distance
(ft)
t3
(min)
Tc* Total
(min)
PostBASIN1 2.00 150 0.9 0.3636 2.00 0.619 2.87 635 3.6859 3.00 617.80 3.43 7.48
PostBASIN2 2.00 280 0.9 0.4967 2.00 0.619 2.87 636 3.6917 3.00 800.40 4.45 8.64
PostBASIN3 2.00 250 0.9 0.4694 2.00 0.619 2.87 637 3.6975 3.00 331.00 1.84 6.01
TIME OF CONCENTRATION
Overland Flow Shallow/Gutter Flow Pipe Flow
Arrowleaf Park and Perennial Park 5/4/2020
Gutter Flow and Inlet Capacity Equations
Sub
Basin
Flow from
Basin
Q
(cfs)
Transverse
Slope
ST
(ft/ft)
Longintudinal
Slope
SL
(ft/ft)
Water Top
Width
T
(ft)
Water
Depth
H
(ft)
Condition Capacity
per EJIW
(cfs)
Notes
1A 0.17 0.01 0.01 5.20 0.05 Sump 2.22
1B 0.80 0.01 0.02 8.09 0.08 Sump 2.77
1C 1.18 0.015 0.02 7.28 0.11 Sump 3.21
1D 0.95 0.015 0.02 6.71 0.10 Sump 3.09
1E 0.89 0.015 0.01 7.44 0.11 Sump 3.25
2A 1.43 0.015 0.02 7.83 0.12 Sump 3.33
2B 0.60 0.015 0.01 6.41 0.10 Tangent 3.02
2C 0.72 0.01 0.01 8.86 0.09 Sump 2.90
2D 1.26 0.015 0.01 8.50 0.13 Sump 3.47
2E 0.54 0.01 0.01 7.99 0.08 Sump 2.75
2F 1.86 0.015 0.02 8.63 0.13 Sump 3.50
2G 0.73 0.01 0.01 8.92 0.09 Sump 2.91
3A 3.00 0.02 0.02 8.63 0.17 Sump 4.04 Curb Cut
3B 0.67 0.01 0.01 8.63 0.09 Tangent 2.86
EXISTING DETENTION POND CALCS
POND SURFACE (BOTTOM) = LOWEST INVERT OUT = 4725.43
AREA OF POND SURFACE =37224 SF
AREA OF TOP OF POND =43543 SF
DEPTH AT OVERFLOW = 1.18
VOLUME OVER POND SURFACE 43,924
VOLUME ALONG BANK WHEN FULL 3,728
TOTAL POND VOLUME 47,653 CF
DESIGN VOLUME 44,860 CF
EXCESS ACTUAL VOLUME 2,793 CF
APPENDIX E
STORM WATER MANAGEMENT PLAN
JOB NO. B19-006
GREAT FALLS, BOZEMAN, KALISPELL & SHELBY, MT | SPOKANE, WA | LEWISTON, ID | WATFORD CITY, ND | MEDIA, PA
MAY 2020
406.586.0277
tdhengineering.com
234 East Babcock Street
Suite 3
Bozeman, MT 59715
CLIENT ENGINEER
CMD Development
520 Pike Street, Suite 1010
Seattle, WA 98101
TD&H Engineering
234 East Babcock Street, Suite 3
Bozeman, MT 59715
Engineer: Kyle Scarr, PE
ONSITE STORM WATER MAINTENANCE PLAN
ARROWLEAF PARK & PER ENNIAL PARK
BOZEMAN, MONTANA
ARROWLEAF PARK & PERENNIAL PARK Storm Sewer Maintenance Plan
B19-006 May 2020
ARROWLEAF PARK & PERENNIAL PARK
STORM WATER PLAN
PURPOSE AND INTRODUCTION
This maintenance plan identifies the recommended maintenance procedures necessary for the
proper function of the storm water management system at the new Arrowleaf Park & Perennial
Park.
The onsite maintenance responsibility for the three new ponds and the storm water collection
system belongs to the new Arrowleaf Park & Perennial Park facility owner. Maintenance of the
existing subdivision detention pond is not covered in this document. The owner may hire a
qualified professional entity or individual to perform all monitoring and maintenance. A log shall
be kept for all required inspections and maintenance. These logs shall be made available to the
City of Bozeman Public Works Department for review as requested. A sample maintenance log
is included in the attached Appendix.
STORM WATER MANAGEMENT SYSTEM
The on-site storm water management system includes curb and gutter, curb inlets, sidewalk
drainage chases, storm water retention ponds, pond outlet structures, and storm drain culverts.
These various components of storm water management infrastructure are designed to collect,
convey, detain, clean, and/or infiltrate storm water runoff that is generated on the property
before it enters local waterways.
Storm water systems require proper maintenance to prevent sediment clogging, overgrown
vegetation, erosion of detention ponds, obstruction of inlets and outlet structures, and prolonged
standing water. Such issues may result in downstream pollution, unpleasant odors, unsightly
areas, nuisance insects, or algae blooms, and must be mitigated. Scheduled inspections, times
of inspections, locations inspected, maintenance completed, corrective actions taken, and any
modifications or reconstruction performed shall be documented in the maintenance logs to be
readily available upon request. Disposal of accumulated sediment must be in accordance with
all applicable local, state and federal regulations.
Wetlands may be present within the boundaries of retention ponds, drainage ditches and
surrounding areas, and should be considered when planning maintenance activities. Wetland
permitting is generally not required for maintenance of constructed storm water management
features. However, maintenance of locations where pond outlet pipes discharge to protected
water bodies within wetland areas may require wetland or stream bank permitting. If unsure of
the regulatory status of wetland features observed at the site, consult the local authorities prior
to undertaking any activities that may cause disturbance.
The following maintenance procedures are intended to prolong the life of these installed system
components and ensure their continued functionality:
General Storm Water System Maintenance –
1. Parking lot areas and curbs & gutters should be cleared of leaves and other debris once
a year at a minimum. This will minimize the potential for debris to enter the system
ARROWLEAF PARK & PERENNIAL PARK Storm Sewer Maintenance Plan
B19-006 May 2020
which could lead to premature clogging of structures, reduced storage capacity, and/or
blockage of inlets.
2. Inspect the storm drain inlets for sediment build-up or clogging and flush/clear as
needed. Inspect for snow/ice buildup at least once weekly during winter months and
clear the inlet as needed. Do not pile snow over the inlet.
3. Inspect culverts at the site for blockage or sediment buildup once a year at a minimum,
and flush/clear as needed.
4. Snow storage should be performed in designated areas during winter months and
should not be allowed to be piled in front of or over inlets. Piled snow around or over the
inlets could block early snowmelt run-off from entering the system, possibly causing
overflows and icy conditions.
5. Sanding of the parking lot should be done sparingly or avoided completely. Sand or
other sediment on the parking lot will likely be washed into stormwater system
components which can lead to buildup and reduced capacity or blockages over time.
Storm Water Pond Maintenance –
1. Routine Maintenance Activities (every 3 months):
a. Mow vegetation around each stormwater pond regularly throughout the
spring/summer months.
b. Designate a “no-mow” zone at the bottom of the ponds. This area will be trimmed
once a year and protected from regularly scheduled grass mowing. Excessive
mowing causes debris buildup and compaction of the soils in the bottom of the
pond, reducing the pond’s infiltration.
c. Remove trash, leaves, plant trimmings, grass clippings, pet waste and other
debris from the pond area.
d. Inspect the pond inlet and outlet for any obstructions that would prevent
stormwater from entering or leaving the pond and remove obstructions as
needed.
2. Annual Maintenance Activities (annually):
a. At the end of each fall, cut plants in the “no-mow” zone to a height of six inches
and rake and remove all clippings and leaves.
b. Re-establish vegetation on eroded or barren areas of the pond.
3. Long-Term Maintenance Activities (as observed/required):
a. Survey the pond elevations to determine the amount of sediment buildup, if any,
in the pond.
ARROWLEAF PARK & PERENNIAL PARK Storm Sewer Maintenance Plan
B19-006 May 2020
b. Excavate sediment and re-establish the pond to its initial design volume per the
construction plans if sediment build-up is found to be greater than six inches or if
the pond volume has decreased by more than ten percent.
c. Flush sediment from outlet structures/piping and from the outfall location if build-
up is observed. Remove sediment build-up from outlet structure or dry well
sumps if needed.
APPENDIX
City of Bozeman Stormwater Basin Maintenance Guide
Sample Maintenance & Inspection Log
FIGURE 5
Storm Water Facilities Inspection and Maintenance Log
Facility Name
Begin Date End Date
Date Location Facility Description Inspected
by:
Cause for
Inspection
Exceptions Noted Comments and
Actions Taken
Instructions: Record all inspections and maintenance for all storm water facilities on this form. Use additional log sheets and/or
attach extended comments or documentation as necessary. Save all completed logs in one place and have them readily available for
the City of Bozeman’s review upon request.
Location — Specify the exact location of the facility either by its name, facility ID or physical location.
Inspected by — Note all inspections and maintenance on this form, including the required independent annual inspection.
Cause for inspection — Note if the inspection is routine, pre-rainy-season, post-storm, annual, or in response to a noted
problem or complaint.
Exceptions noted — Note any condition that requires correction or indicates a need for maintenance.
Comments and actions taken — Describe any maintenance performed and need for follow-up.
FIGURE 6
APPENDIX F
FLOOD ANALYSIS
FF=4736.00
FF=4735.00
FF=4734.75
FF=4734.50
FF=4735.25
FF=4735.75
FF=4735.25
FF=4734.75
FF=4734.50
FF=4736.00
FAMILY PROMISEFF=4739.00
COMMUNITY HEALTHPARTNERSFF=4740.00
FLOOD AREA
ELEV.=4727.41
PROPOSED
SITE
QUALITY CHECK:
DESIGNED BY:
DRAWN BY:
CAD NO.
JOB NO.
DATE:
B19-006-FLOODPLAIN EXHIBIT-20200501
Engineering
tdhengineering.com
1
EXHIBIT
B19-006
5/01/20
HMH
KJM
KJM
FLOODPLAIN ANALYSIS
BOZEMAN, MONTANA
ARROWLEAF PARK & PERENNIAL PARK
APPROXIMATE
ALIGNMENT OF
PROPOSED
15TH AVE.
FLOOD
AREA
ELEV.=4727.41
PROPOSED
SITE
QUALITY CHECK:
DESIGNED BY:
DRAWN BY:
CAD NO.
JOB NO.
DATE:
B19-006-FLOODPLAIN EXHIBIT-20200501
2
EXHIBIT
B19-006
5/01/20
HMH
KJM
KJM
FLOODPLAIN ANALYSIS
BOZEMAN, MONTANA
ARROWLEAF PARK & PERENNIAL PARK
Engineering
tdhengineering.com
BLDG A
BLDG B
BLDG D
FINISH FLOOR
ELEVATIONS
BLDG A=4735.25
BLDG B=4734.75
BLDG C=4736.00
BLDG D=4734.75
BLDG E=4735.00
BLDG F=4736.00
BLDG G=4734.50
BLDG H=4734.50
BLDG I =4735.25
BLDG J=4735.75
BLDG K=4740.00
BLDG L=4739.00
BLDG E
BLDG F
BLDG G
BLDG H
BLDG I
BLDG J
BLDG K BLDG L
BLDG C
FLOOD ELEV.=4728.67
FLOOD ELEV.=4731.27
FLOOD ELEV.=4733.56
FLOOD ELEV.=4735.10