HomeMy WebLinkAbout05 Headwaters Storm Drainage Report 2020_05_21Headwaters Academy
May 2020
Project: 19‐024
Bozeman Office . 32 Discovery Drive . Bozeman, Montana 59718 . Ph: (406) 582‐0221 . Fax: (406) 582‐5770 Page 1
Table of Contents
1 Project Overview and Background ......................................................................................... 2
2 Hydrology ............................................................................................................................... 2
2.1 Pre-Development .............................................................................................................. 2
2.2 Post Development ............................................................................................................ 2
3 Post Development Hydraulics ................................................................................................. 3
3.1 Inlet and Gutter Capacity ................................................................................................. 3
3.2 Storm Drain ...................................................................................................................... 4
3.3 Ponds ................................................................................................................................ 4
4 Maintenance Plan .................................................................................................................... 5
Table 1 - Pre-Development Hydrology ........................................................................................... 2
Table 2 - Post Development Drainage Basins ................................................................................ 3
Table 3 - Inlet and Gutter Summary (25-year event) ...................................................................... 3
Table 4 - Storm Drain Summary (25-year event) ........................................................................... 4
Table 5 - Outfall Summary ............................................................................................................. 4
Table 6 - Minimum Sizing .............................................................................................................. 4
Table 7 – Pond A Pond Stage-Storage-Discharge .......................................................................... 5
Table 8 - Pond B Pond Stage-Storage-Discharge ........................................................................... 5
Attachments:
Exhibit 1.1 – Vicinity Map - Topo
Exhibit 1.2 – Vicinity Map - Aerial
Exhibit 2.1 – Pre-Development Drainage
Exhibit 3.1 – Post Development Drainage
Exhibit 3.2 – Model Overview Plan
Appendix A – Supporting Calculations
Appendix B – Hydraulic Modeling Outputs
Appendix C – Storm Drainage Plans
Headwaters Academy
May 2020
Project: 19‐024
Bozeman Office . 32 Discovery Drive . Bozeman, Montana 59718 . Ph: (406) 582‐0221 . Fax: (406) 582‐5770 Page 2
1 Project Overview and Background
The proposed site improvements involve the construction of an additional structure and a
remodel of an existing structure. A new parking lot is included as part of the improvements. The
project site is located on the North side of North 10th Ave. and Durston Rd. Vicinity maps
showing the project location and extents are provided in Exhibits 1.1 and 1.2. An existing pond
is located at the Northwest corner of the lot. The origin of the pond is unknown but is anticipated
to be aesthetic. A new detention pond at the north end and a new retention pond along the west
side of the site will be provided to meet the water quality and peak runoff rate requirements. A
groundwater monitoring well was installed as part of the geotechnical test pits. Groundwater was
monitored on May 5, 2020; the monitor well was dry to a depth of 7.7-ft below existing ground.
2 Hydrology
The rational method was utilized to estimate peak flow rates for conveyance sizing as outlined
by the City of Bozeman Design Standards and Specifications. A weighted runoff coefficient “C”
was determined based on a combination of open space (C=0.2) and pavement (C=0.95). The time
to concentration was estimated using the overland flow method from the City of Bozeman
Design Standards and TR-55 for shallow concentrated flow. A more detailed breakout of the data
for each basin is provided in Appendix A.
2.1 Pre‐Development
An overview of the pre-development drainage is provided on Exhibit 2.1. Two basins were
assumed for the site matching the post development pond basins for the purpose of pond sizing.
A summary is provided in Table 1; more detailed information providing a time to concentration
breakout and intensity is provided in Appendix A. Basin B.1 was conservatively assumed to have
no impervious area prior to the proposed development.
Table 1 - Pre-Development Hydrology
Basin Total
Area (ac)
Impervious
(sf)
Open
Space (sf)
Weighted
C
Tc
(min)
10-yr Peak
Runoff
(cfs)
25-yr Peak
Runoff (cfs)
A.1 2.12 7,539 84,979 0.26 17 0.80 0.98
B.1 0.63 0 27,395 0.20 8 0.30 0.37
2.2 Post Development
The post development drainage basins are summarized in Table 2. An overview plan showing
the drainage areas and infrastructure is provided on Exhibit 3.1. Basins titled “A” are areas
routed through the proposed detention pond to the northeast of the proposed development; and
Basin B.1 consist of the area routed through the proposed pond to the west.
Headwaters Academy
May 2020
Project: 19‐024
Bozeman Office . 32 Discovery Drive . Bozeman, Montana 59718 . Ph: (406) 582‐0221 . Fax: (406) 582‐5770 Page 3
Table 2 - Post Development Drainage Basins
Basin Total Area
(acres)
Impervious
(sf)
Open
Space (sf)
Weighted
C
Tc
(min)
25-yr Peak
Runoff (cfs)
A.1 0.44 17,631 1,570 0.89 6 1.33
A.2 0.79 25,007 9,379 0.75 6 2.00
A.3 0.89 33,347 33,347 0.31 9 0.73
B.1 0.63 7,880 19,426 0.42 7 0.83
3 Post Development Hydraulics
The post development conveyance infrastructure considers the 25-year design event as outlined
in the City of Bozeman Design Standards. The proposed system was modeled using Autodesk
Storm and Sanitary Analysis (2017). An overview of the model is provided with Exhibit 3.2.
Model outputs are included with Appendix B.
3.1 Inlet and Gutter Capacity
Inlet hydraulic calculations are based on the orifice vs. weir method provided in HEC-22. The
maximum allowable water surface for the 25-year event is 0.15-ft below the top back of curb.
This corresponds to an average depth in the gutter pan of 0.27-ft and a spread width of 9.5-ft
assuming a 3% crown. Sag inlet capacity is weir controlled with a capacity of 2.4-cfs. The gutter
flow capacity is based on the HEC-22 gutter flow methodology for a uniform section. Street
capacity is 3.6-cfs for a typical cross slope of 3% and a minimum longitudinal grade of 0.5%.
There is one curb cut near the existing garage. The curb cut was modeled as a weir with a width
of 3-ft. All calculated peak flow rates are less than the typical street and inlet capacity. Sample
calculations are provided in Appendix A. A summary of inlet and gutter flow is provided in
Table 3. All inlets are located at a sag in the curb line.
Table 3 - Inlet and Gutter Summary (25-year event)
Inlet Cross Slope
(%)
Calc. Peak
Flow (cfs)
TBC
(ft)
TBC-0.15
(ft)
Calculated WSE
(ft)
Spread
(ft)
I-A.1 1.6 1.65 4785.14 4784.99 4781.84 9.84
I-A.2 2.3 1.68 4783.29 4783.14 4783.13 9.96
Curb
Cut B.1 2 0.84 4782.20 4782.05 4781.94 8.0
The concrete channels conveying drainage through the landscape islands were modeled based on
weir flow. The calculations were conservatively based on the entire area for basin A.1 and A.2.
The widths are 2.5-ft wide for the channel near the new structure (A.1), and 4.0-ft wide for the
channel near the existing structure (A.2). Flow depths are approximately 0.30-ft deep.
Supporting calculations are included in Appendix A.
Headwaters Academy
May 2020
Project: 19‐024
Bozeman Office . 32 Discovery Drive . Bozeman, Montana 59718 . Ph: (406) 582‐0221 . Fax: (406) 582‐5770 Page 4
3.2 Storm Drain
The storm drain analysis was completed using Autodesk Storm and Sanitary Analysis. Minimum
pipe grades for 12-in and 15-inch storm drains are 0.4% and 0.3% respectively. Minimum grades
are based on Table 7-7 in HEC-22 providing minimum pipe grades to ensure a pipe full velocity
of 3-fps. Headwater depths at the pipe entrances are all below top of pipe, no pipes are shown to
be surcharged. Table 4 provides a summary of storm pipe properties, flows, and flow depths.
Table 4 - Storm Drain Summary (25-year event)
Storm Drain Size/Material Grade (%) Length (ft) Peak
Flow (cfs)
Headwater
Depth (ft)
SD-1 12” PVC 2.02 80.01 1.32 0.35
SD-2 15” PVC 0.98 40.87 3.30 0.63
3.3 Ponds
The pre-development peak runoff rates were previously provided in Section 2. The post
development drainage is broken into multiple basins. Basins noted “A” drain to the proposed
detention pond northeast of the development. Basin B.1 drains to the proposed retention pond on
the west side of the property. A summary is provided below. Groundwater was monitored via a
monitor well on May 5, 2020. No groundwater was observed to a depth of 7.7-ft below existing
ground (depth of the monitor well was dry).
Table 5 - Outfall Summary
Desc. Basins Area
(ac)
Impervious
Area (sf)
Weighted
C
Tc
(min) Q (cfs) 10-yr
Pre-Dev. A Pre-A.1 2.12 7,539 0.26 17 0.80
Pre-Dev. B Pre-B.1 0.63 0 0.20 8 0.30
Post A A.1, A.2, A.3 2.12 48,225 0.59 9 2.72
Post B B.1 0.63 7,880 0.42 7 0.68
The allowable discharge for the COB method of pond sizing is based on subtracting the post
development basin peak runoff rate from the pre-development peak runoff rate. This
conservatively neglects routing and will produce a lower combined post development runoff rate
than the pre-development rate. The total increase of impervious area was used to determine the
required water quality volume.
Table 6 - Minimum Sizing
Outfall Detention
(cf)
Retention
(cf)
10-yr
allowable
discharge (cfs)
Minimum
Area (sf)
Actual
Bot. Area
(sf)
Water
Quality
Vol. (CF)
A/Pond 1,063 - 0.80 116 1,971 1,610
B/Pond - 777 0.28 40 391 312
Headwaters Academy
May 2020
Project: 19‐024
Bozeman Office . 32 Discovery Drive . Bozeman, Montana 59718 . Ph: (406) 582‐0221 . Fax: (406) 582‐5770 Page 5
A summary of the pond stage-storage-discharge relationship is outlined in Table 7. A more
detailed summary for each outflow component is provided in Appendix A. A small 0.2-ft
diameter orifice is provided at the pond bottom elevation to slowly drain the pond down over
time. A weir is set 0.75-ft off the pond bottom to provide the required water quality volume prior
to significant discharge from the pond. The incremental storage from a depth of 0.75-ft to a depth
of 1.25-ft is greater than the minimum pond detention volume based on the COB sizing method
outlined in the design standards. The table shows the pond provides adequate storage to control
post development runoff rates.
Table 7 – Pond A Pond Stage-Storage-Discharge
Stage (ft) Elevation (ft) Storage (cf) Discharge (cfs)
0.00 4779.00 0 0
0.25 4779.25 541 0.08
0.50 4779.50 1,185 0.11
0.75 4779.75 1,933 0.13
1.00 4780.00 2,786 0.36
1.25 4780.25 3,745 0.76
1.50 4780.50 4,812 1.27
Table 8 - Pond B Pond Stage-Storage-Discharge
Stage (ft) Elevation (ft) Storage (cf)
0.00 4780.50 0
0.25 4780.75 76
0.50 4781.00 183
0.75 4781.25 325
1.00 4781.50 502
1.25 4781.75 718
1.50 4782.00 976
Additional outputs from the model can be found in Appendix B. Geotechnical test pits were
completed for the site on December 19, 2019 by AESI. The test pits were generally excavated to
a depth of 8-ft. The pits generally became wet below a depth of 8-ft. The proposed ponds are
relatively shallow compared to existing ground; therefore, groundwater is not anticipated to be
an issue.
4 Maintenance Plan
All proposed storm drainage features will be privately owned and maintained. Storm
infrastructure generally consists of curb inlets, conveyance piping, a detention pond, and pond
outlet works. The curb inlets located in the parking lot will collect debris and should be inspected
in the spring and fall and cleaned if debris is present. Sumps are provided on each of the inlets
and should be inspected and cleaned out by hand or a vac truck once a year or as debris is
collected.
Headwaters Academy
May 2020
Project: 19‐024
Bozeman Office . 32 Discovery Drive . Bozeman, Montana 59718 . Ph: (406) 582‐0221 . Fax: (406) 582‐5770 Page 6
The proposed detention pond should be mowed, and any grass clippings or other organic matter
collected and removed from the pond bottom. The inlet and outlet pipes should be kept clear of
debris to allow for proper conveyance. A more detailed maintenance plan for the retention pond
is outlined below; many of the items will also apply to the detention pond and should be
considered where applicable.
The retention pond is relatively small and collects a limited drainage are; however, it will still be
critical to monitor and maintain the pond. The following recommendations are from the Montana
Post-Construction Storm Water BMP Design Guidance Manual. Refer to the manual for
additional information and detail.
As needed Maintenance
o Remove litter/debris from all components of the infiltration basin.
o Repair structural components including inlets, diversion structures, and outlet
structure (if applicable).
o Inspect the basin for signs of erosion and repair eroded areas accordingly.
Perform spot-reseeding if necessary.
o Observe drain time following rainfall events to determine if the facility is
clogged. If the observed drain time is longer than the local jurisdiction’s
allowable maximum drain time, corrective action must be taken to return the
infiltration basin to the design drain time.
o Regularly manage all vegetation associated with the infiltration basin and remove
all clippings.
Semiannual Maintenance
o Trim vegetation for aesthetics and to prevent the establishment of woody
vegetation that may drop leaf litter, fruits, and other vegetative material that may
clog the facility.
o Remove all green waste and dispose of properly to prevent clogging.
Annual Maintenance
o Inspect all components of the infiltration basin in accordance with an approved
inspection form. Refer to the Post-Construction BMP Design Manual for
additional information and example forms.
o Remove sediment from inlets, in-flow paths, and overflow paths.
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Autodesk Storm and Sanitary Analysis Model Overview EX-3.2Autodesk Storm and Sanitary Analysis Model Overview EX-3.2
Appendix A
Supporting Calculations
Area Area
Open (sf)paved (sf)Overland flow (ft)grade (%)C Cf (25-yr)Tc (min) Length Grade time avg grade (ft/ft)length (ft)Tc (min)
PRE-DEVELOPMENT 10-yr i 25-yr I 10-yr Q 25-yr Q
A.1 1.45 1.77 0.80 0.98 92,518 2.12 84,979 7,539 0.26 17 0.28 100 1.86 0.2 1.1 13.4 442 1.86% 3.35
B.1 2.41 2.94 0.30 0.37 27,306 0.63 27,395 0 0.20 8 0.13 120 3.33 0.5 1.1 7.5
Area Area
POST DEVELOPMENT 10-yr i 25-yr i 10-yr Q 25-yr Q Open (sf) paved (sf)Overland flow (ft) grade (%) C Cf (25-yr) Tc (min) Length Grade time avg grade (ft/ft) length (ft) Tc (min)
A.1 2.79 3.40 1.09 1.33 19,201 0.44 1,570 17,631 0.89 6 0.10 150 2 0.9 1.1 2 0.007 30 1
A.2 2.79 3.40 1.64 2.00 34,383 0.79 9,376 25,007 0.75 6 0.10 80 1.875 0.9 1.1 1 0.007 150 3.6
A.3 2.17 2.64 0.60 0.73 38,934 0.89 33,347 5,587 0.31 9 0.15 75 1 0.5 1.1 9
B.1 2.61 3.19 0.68 0.83 27,306 0.63 19,426 7,880 0.42 7 0.11 33 1.42 0.5 1.1 5 192 2 1.4
A Combined 2.17 2.64 2.72 3.32 92,518 2.12 44,293 48,225 0.59 9 0.15
Intensity (in/hr) Peak Q (cfs)Area (sf) Area (acres)
Area (acres)Area (sf)
**Column Headers that are underlined and red are manual inputs
Manual - HEC-22 Gutter FlowC value Tc (min) Tc (hr)Overland Tc (COB Design Standards)Manual - Shallow Concentrated (TR-55)
Basin Overland Tc (COB Design Standards)Manual - HEC-22 Gutter FlowTc (hr)Tc (min)C value Manual - Shallow Concentrated (TR-55)Intensity (in/hr) Peak Q (cfs)
Basin Pre-Paved (sf)Post Paved (sf)Additional Pavement (sf)Water Quality Vol (cf)
A 7,539 48,225 40,686 1610
B 0 7,880 7,880 312
Water Quality Volume - Pre vs. Post Discharge Points
Calculation of Required Volume for Storm Detention Pond
Pond ID Proposed Pond
Accepts flow from basins A.1 A.2 A.3
(Reference: Bozeman Stormwater Master Plan - 1982)
Design Rainfall Freq. 10 year (see page III - 5 of master plan)
IDF coefficient a 0.64
IDF coefficient b
IDF coefficient n 0.65
Pre-development Calculations Post-development Calculations
C C
Areas (ft2):open space 0.20 Areas (ft2):open space 0.20
med. res.0.35 med. res.0.35
dense res.0.50 dense res.0.50
comm. neigh.0.60 comm. neigh.0.60
comm. down.0.80 comm. down.0.80
industrial 0.80 industrial 0.80
Total:Total:
total area: 2.12 acres total area: 2.12 acres
composite C: 0.26 composite C: 0.59
Overland tc Overland tc
average slope:percent average slope:percent
travel distance:feet travel distance:feet
tc:minutes tc:minutes
Channel tc Channel tc
channel tc:minutes channel tc:minutes
Total tc:17 minutes Total tc:9 minutes
intensity at tc (fig 23):1.45 in/hr intensity at tc (fig 23):2.20 in/hr
pre-devel peak runoff: 0.80 cfs post-devel peak runoff: 2.75 cfs
Storm Duration Intensity Future Runoff Runoff Release Required
(minutes)(in/hr)Rate (cfs)Volume (cf)Volume (cf)Storage (cf)
9 2.20 2.75 1484 432 1051
11 1.93 2.41 1591 528 1063
13 1.73 2.16 1687 625 1063
15 1.58 1.97 1774 721 1053
17 1.45 1.82 1853 817 1037
19 1.35 1.69 1927 913 1014
21 1.27 1.58 1996 1009 987
23 1.19 1.49 2060 1105 955
25 1.13 1.41 2121 1201 920
27 1.08 1.35 2179 1297 882
29 1.03 1.28 2234 1393 841
31 0.98 1.23 2287 1489 798
33 0.94 1.18 2338 1585 752
35 0.91 1.14 2386 1682 705
37 0.88 1.10 2433 1778 656
39 0.85 1.06 2479 1874 605
41 0.82 1.03 2522 1970 552
43 0.79 0.99 2565 2066 499
45 0.77 0.97 2606 2162 444
47 0.75 0.94 2646 2258 388
49 0.73 0.91 2685 2354 330
51 0.71 0.89 2722 2450 272
53 0.69 0.87 2759 2546 213
55 0.68 0.85 2795 2642 153
57 0.66 0.83 2831 2739 92
59 0.65 0.81 2865 2835 30
required detention storage (ft3) =1,063
detention pond COB
Calculation of Required Volume for Storm Detention Pond
Pond ID Proposed Pond Basin B
Accepts flow from basins B.1
(Reference: Bozeman Stormwater Master Plan - 1982)
Design Rainfall Freq. 10 year (see page III - 5 of master plan)
IDF coefficient a 0.64
IDF coefficient b
IDF coefficient n 0.65
Pre-development Calculations Post-development Calculations
C C
Areas (ft2):open space 0.20 Areas (ft2):open space 0.20
med. res.0.35 med. res.0.35
dense res.0.50 dense res.0.50
comm. neigh.0.60 comm. neigh.0.60
comm. down.0.80 comm. down.0.80
industrial 0.80 industrial 0.80
Total:Total:
total area: 0.63 acres total area: 0.63 acres
composite C: 0.20 composite C: 0.42
Overland tc Overland tc
average slope:percent average slope:percent
travel distance:feet travel distance:feet
tc:minutes tc:minutes
Channel tc Channel tc
channel tc:minutes channel tc:minutes
Total tc:9 minutes Total tc:7 minutes
intensity at tc (fig 23):2.20 in/hr intensity at tc (fig 23):2.59 in/hr
pre-devel peak runoff: 0.28 cfs post-devel peak runoff: 0.68 cfs
Storm Duration Intensity Future Runoff Runoff Release Required
(minutes)(in/hr)Rate (cfs)Volume (cf)Volume (cf)Storage (cf)
7 2.59 0.68 287 116 171
9 2.20 0.58 314 149 164
11 1.93 0.51 337 183 154
13 1.73 0.46 357 216 141
15 1.58 0.42 375 249 126
17 1.45 0.38 392 282 110
19 1.35 0.36 408 315 92
21 1.27 0.34 422 349 73
23 1.19 0.32 436 382 54
25 1.13 0.30 449 415 34
27 1.08 0.28 461 448 13
29 1.03 0.27 473 482 -9
31 0.98 0.26 484 515 -31
33 0.94 0.25 495 548 -53
35 0.91 0.24 505 581 -76
37 0.88 0.23 515 614 -100
39 0.85 0.22 524 648 -123
41 0.82 0.22 534 681 -147
43 0.79 0.21 543 714 -171
45 0.77 0.20 551 747 -196
47 0.75 0.20 560 780 -221
49 0.73 0.19 568 814 -246
51 0.71 0.19 576 847 -271
53 0.69 0.18 584 880 -296
55 0.68 0.18 591 913 -322
57 0.66 0.18 599 946 -348
required detention storage (ft3) =171
detention pond COB
POND A SUMMARY
Pond Bottom 4779.00 DO NOT TOUCH
Orifice Elevation 4779.00
Orifice Size (ft)0.20
Orifice Area (sf)0.03 Pre-Development Target Rate (10-yr for COB)0.8
Weir 1 Elevation 4779.75 Bottom Area 1971
Weir 1 Width (ft)0.50 Water Quality Vol 1610
Weir 2 Elevation 4780.50
Weir 2 Width (ft)3.10
Stage Elev Storage (cf) Orifice Head Orifice Outflow Weir 1 Head Weir 1 Outflow Weir 2 Head Weir 2 Ouflow Total Outflow Stage Elev Storage (CY)
0.00 4779.00 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4779.00 0
0.25 4779.25 541 0.25 0.08 0.00 0.00 0.00 0.00 0.08 0.25 4779.25 20.04
0.50 4779.50 1185 0.50 0.11 0.00 0.00 0.00 0.00 0.11 0.50 4779.50 43.89
0.75 4779.75 1933 0.75 0.13 0.00 0.00 0.00 0.00 0.13 0.75 4779.75 71.58
1.00 4780.00 2786 1.00 0.15 0.25 0.21 0.00 0.00 0.36 1.00 4780.00 103.17
1.25 4780.25 3745 1.25 0.17 0.50 0.59 0.00 0.00 0.76 1.25 4780.25 138.71
1.50 4780.50 4812 1.50 0.19 0.75 1.08 0.00 0.00 1.27 1.50 4780.50 178.24
1.75 4780.75 5989 1.75 0.20 1.00 1.67 0.25 1.08 2.95 1.75 4780.75 221.83
2.00 4781.00 7277 2.00 0.21 1.25 2.33 0.50 3.06 5.60 2.00 4781.00 269.51
2.25 4781.25 8676 2.25 0.23 1.50 3.06 0.75 5.62 8.91 2.25 4781.25 321.33
2.50 4781.50 10188 2.50 0.24 1.75 3.85 1.00 8.66 12.75 2.50 4781.50 377.35
POND B SUMMARY
Pond Bottom 4780.50 DO NOT TOUCH
Orifice Elevation 4781.00
Orifice Size (ft)0.00
Orifice Area (sf)0.00 Pre-Development Target Rate (10-yr for COB)0.35 cfs
Weir 1 Elevation 0.00 Bottom Area 391 sf
Weir 1 Width (ft)0.00 Water Quality Vol 312 cf
Weir 2 Elevation 0.00 Retention Volume 777 cf
Weir 2 Width (ft)0.00
Stage Elev Storage (cf) Orifice Head Orifice Outflow Weir 1 Head Weir 1 Outflow Weir 2 Head Weir 2 Ouflow Total Outflow Stage Elev Storage (CY)
0.00 4780.50 0 0.00 0.00 4780.50 0.00 4780.50 0.00 0.00 0.00 4780.50 0
0.25 4780.75 76.41 0.00 0.00 4780.75 0.00 4780.75 0.00 0.00 0.25 4780.75 2.83
0.50 4781.00 183.33 0.00 0.00 4781.00 0.00 4781.00 0.00 0.00 0.50 4781.00 6.79
0.75 4781.25 324.54 0.25 0.00 4781.25 0.00 4781.25 0.00 0.00 0.75 4781.25 12.02
1.00 4781.50 502.2 0.50 0.00 4781.50 0.00 4781.50 0.00 0.00 1.00 4781.50 18.6
1.25 4781.75 718.2 0.75 0.00 4781.75 0.00 4781.75 0.00 0.00 1.25 4781.75 26.6
1.50 4782.00 976.32 1.00 0.00 4782.00 0.00 4782.00 0.00 0.00 1.50 4782.00 36.16
1.75 4782.25 0 1.25 0.00 4782.25 0.00 4782.25 0.00 0.00 1.75 4782.25
2.00 4782.50 0 1.50 0.00 4782.50 0.00 4782.50 0.00 0.00 2.00 4782.50
2.25 4782.75 0 1.75 0.00 4782.75 0.00 4782.75 0.00 0.00 2.25 4782.75
2.50 4783.00 0 2.00 0.00 4783.00 0.00 4783.00 0.00 0.00 2.50 4783.00
Appendix B
Model Outputs
10‐year
Post Development Model Outputs
Project Options
CFS
Elevation
Rational
User-Defined
Kinematic Wave
YESNO
Analysis Options
Sep 04, 2019 00:00:00
Sep 04, 2019 02:00:00
Sep 04, 2019 00:00:00
0 days
0 01:00:00 days hh:mm:ss0 00:05:00 days hh:mm:ss0 00:05:00 days hh:mm:ss30seconds
Rainfall Details
10 year(s)
Runoff (Wet Weather) Time Step ........................................Reporting Time Step ............................................................Routing Time Step ................................................................
Return Period........................................................................
Skip Steady State Analysis Time Periods ............................
Start Analysis On ..................................................................
End Analysis On ...................................................................
Start Reporting On ................................................................
Antecedent Dry Days ............................................................
Runoff (Dry Weather) Time Step ..........................................
Flow Units .............................................................................
Elevation Type ......................................................................
Hydrology Method .................................................................
Time of Concentration (TOC) Method ..................................
Link Routing Method .............................................................
Enable Overflow Ponding at Nodes ......................................
Subbasin Summary
SN Subbasin Area Weighted Total Total Total Peak Time ofIDRunoff Rainfall Runoff Runoff Runoff ConcentrationCoefficientVolume(ac)(in) (in) (ac-in) (cfs) (days hh:mm:ss)1 Sub-A.1 0.44 0.8900 0.29 0.25 0.11 1.12 0 00:06:002 Sub-A.2 0.79 0.7500 0.29 0.21 0.17 1.69 0 00:06:003 Sub-A.3 0.89 0.3100 0.33 0.10 0.09 0.61 0 00:09:00
Node Summary
SN Element Element Invert Ground/Rim Initial Surcharge Ponded Peak Max HGL Max Min Time of Total Total TimeID Type Elevation (Max) Water Elevation Area Inflow Elevation Surcharge Freeboard Peak Flooded FloodedElevation Elevation Attained Depth Attained Flooding VolumeAttainedOccurrence(ft) (ft) (ft) (ft) (ft²) (cfs) (ft) (ft) (ft) (days hh:mm) (ac-in) (min)1 Out-1 Outfall 4778.10 0.11 4778.102 Stor-01 Storage Node 4779.00 4780.50 0.00 0.00 3.19 4779.53 0.00 0.00
Inlet Summary
SN Element Inlet Manufacturer Inlet Number of Catchbasin Max (Rim) Initial Ponded Peak Peak Flow Peak Flow Inlet Allowable Max Gutter Max Gutter
ID Manufacturer Part Location Inlets Invert Elevation Water Area Flow Intercepted Bypassing Efficiency Spread Spread Water Elev.Number Elevation Elevation by Inlet during Peak during Peak during Peak
Inlet Flow Flow Flow
(ft) (ft) (ft) (ft²) (cfs) (cfs) (cfs) (%) (ft) (ft) (ft)1 Inlet-1 FHWA HEC-22 GENERIC N/A On Sag 1 4781.61 4784.72 4781.61 10.00 1.12 N/A N/A N/A 7.00 8.64 4784.93
2 Inlet-2 FHWA HEC-22 GENERIC N/A On Sag 1 4779.68 4782.84 4779.68 10.00 1.69 N/A N/A N/A 7.00 8.71 4783.10
Pipe Input
SN Element Length Inlet Inlet Outlet Outlet Total Average Pipe Pipe Pipe Manning's Entrance Exit/Bend Additional Initial Flap No. ofIDInvert Invert Invert Invert Drop Slope Shape Diameter or Width Roughness Losses Losses Losses Flow Gate BarrelsElevation Offset Elevation Offset Height(ft) (ft) (ft) (ft) (ft) (ft) (%)(in) (in)(cfs)1 SD-1 80.01 4781.61 0.00 4779.93 0.25 1.68 2.1000 CIRCULAR 12.000 12.000 0.0130 0.5000 0.5000 0.0000 0.00 No 12 SD-2 40.87 4779.68 0.00 4779.26 0.26 0.42 1.0300 CIRCULAR 15.000 15.000 0.0130 0.5000 0.5000 0.0000 0.00 No 1
Pipe Results
SN Element Peak Time of Design Flow Peak Flow/ Peak Flow Travel Peak Flow Peak Flow Total Time Froude ReportedID Flow Peak Flow Capacity Design Flow Velocity Time Depth Depth/ Surcharged Number ConditionOccurrenceRatioTotal DepthRatio(cfs) (days hh:mm) (cfs)(ft/sec) (min) (ft)(min)1 SD-1 1.11 0 00:06 5.16 0.21 6.45 0.21 0.31 0.31 0.00 Calculated2 SD-2 2.78 0 00:06 6.55 0.42 5.13 0.13 0.57 0.45 0.00 Calculated
Inlet Input
SN Element Inlet Manufacturer Inlet Number of Catchbasin Max (Rim) Inlet Initial Initial Ponded GrateID Manufacturer Part Location Inlets Invert Elevation Depth Water Water Area CloggingNumberElevationElevation Depth Factor(ft) (ft) (ft) (ft) (ft) (ft²) (%)1 Inlet-1 FHWA HEC-22 GENERIC N/A On Sag 1 4781.61 4784.72 3.11 4781.61 0.00 10.00 0.002 Inlet-2 FHWA HEC-22 GENERIC N/A On Sag 1 4779.68 4782.84 3.16 4779.68 0.00 10.00 0.00
Roadway & Gutter Input
SN Element Roadway Roadway Roadway Gutter Gutter Gutter AllowableID Longitudinal Cross Manning's Cross Width Depression SpreadSlope Slope Roughness Slope(ft/ft) (ft/ft)(ft/ft) (ft) (in) (ft)1 Inlet-1 N/A 0.0160 0.0130 0.0620 1.50 0.0000 7.002 Inlet-2 N/A 0.0230 0.0130 0.0620 1.50 0.0000 7.00
Inlet Results
SN Element Peak Peak Peak Flow Peak Flow Inlet Max Gutter Max Gutter Max Gutter Time of Total Total TimeID Flow Lateral Intercepted Bypassing Efficiency Spread Water Elev. Water Depth Max Depth Flooded FloodedInflow by Inlet during Peak during Peak during Peak during Peak Occurrence VolumeInletFlow Flow Flow Flow(cfs) (cfs) (cfs) (cfs) (%) (ft) (ft)(ft) (days hh:mm) (ac-in) (min)1 Inlet-1 1.12 1.12 N/A N/A N/A 8.64 4784.93 0.21 0 00:06 0.00 0.002 Inlet-2 1.69 1.69 N/A N/A N/A 8.71 4783.10 0.26 0 00:06 0.00 0.00
25‐year
Post Development Model Outputs
Project Options
CFS
Elevation
Rational
User-Defined
Kinematic Wave
YESNO
Analysis Options
Sep 04, 2019 00:00:00
Sep 04, 2019 02:00:00
Sep 04, 2019 00:00:00
0 days
0 01:00:00 days hh:mm:ss0 00:05:00 days hh:mm:ss0 00:05:00 days hh:mm:ss30seconds
Rainfall Details
25 year(s)
Runoff (Wet Weather) Time Step ........................................Reporting Time Step ............................................................Routing Time Step ................................................................
Return Period........................................................................
Skip Steady State Analysis Time Periods ............................
Start Analysis On ..................................................................
End Analysis On ...................................................................
Start Reporting On ................................................................
Antecedent Dry Days ............................................................
Runoff (Dry Weather) Time Step ..........................................
Flow Units .............................................................................
Elevation Type ......................................................................
Hydrology Method .................................................................
Time of Concentration (TOC) Method ..................................
Link Routing Method .............................................................
Enable Overflow Ponding at Nodes ......................................
Subbasin Summary
SN Subbasin Area Weighted Total Total Total Peak Time ofIDRunoff Rainfall Runoff Runoff Runoff ConcentrationCoefficientVolume(ac)(in) (in) (ac-in) (cfs) (days hh:mm:ss)1 Sub-A.1 0.44 0.8900 0.34 0.30 0.13 1.33 0 00:06:002 Sub-A.2 0.79 0.7500 0.34 0.26 0.20 2.02 0 00:06:003 Sub-A.3 0.89 0.3100 0.39 0.12 0.11 0.73 0 00:09:00
Node Summary
SN Element Element Invert Ground/Rim Initial Surcharge Ponded Peak Max HGL Max Min Time of Total Total TimeID Type Elevation (Max) Water Elevation Area Inflow Elevation Surcharge Freeboard Peak Flooded FloodedElevation Elevation Attained Depth Attained Flooding VolumeAttainedOccurrence(ft) (ft) (ft) (ft) (ft²) (cfs) (ft) (ft) (ft) (days hh:mm) (ac-in) (min)1 Out-1 Outfall 4778.10 0.12 4778.102 Stor-01 Storage Node 4779.00 4780.50 0.00 0.00 3.80 4779.61 0.00 0.00
Inlet Summary
SN Element Inlet Manufacturer Inlet Number of Catchbasin Max (Rim) Initial Ponded Peak Peak Flow Peak Flow Inlet Allowable Max Gutter Max Gutter
ID Manufacturer Part Location Inlets Invert Elevation Water Area Flow Intercepted Bypassing Efficiency Spread Spread Water Elev.Number Elevation Elevation by Inlet during Peak during Peak during Peak
Inlet Flow Flow Flow
(ft) (ft) (ft) (ft²) (cfs) (cfs) (cfs) (%) (ft) (ft) (ft)1 Inlet-1 FHWA HEC-22 GENERIC N/A On Sag 1 4781.61 4784.72 4781.61 10.00 1.33 N/A N/A N/A 7.00 9.84 4784.95
2 Inlet-2 FHWA HEC-22 GENERIC N/A On Sag 1 4779.68 4782.84 4779.68 10.00 2.02 N/A N/A N/A 7.00 9.96 4783.13
Pipe Input
SN Element Length Inlet Inlet Outlet Outlet Total Average Pipe Pipe Pipe Manning's Entrance Exit/Bend Additional Initial Flap No. ofIDInvert Invert Invert Invert Drop Slope Shape Diameter or Width Roughness Losses Losses Losses Flow Gate BarrelsElevation Offset Elevation Offset Height(ft) (ft) (ft) (ft) (ft) (ft) (%)(in) (in)(cfs)1 SD-1 80.01 4781.61 0.00 4779.93 0.25 1.68 2.1000 CIRCULAR 12.000 12.000 0.0130 0.5000 0.5000 0.0000 0.00 No 12 SD-2 40.87 4779.68 0.00 4779.26 0.26 0.42 1.0300 CIRCULAR 15.000 15.000 0.0130 0.5000 0.5000 0.0000 0.00 No 1
Pipe Results
SN Element Peak Time of Design Flow Peak Flow/ Peak Flow Travel Peak Flow Peak Flow Total Time Froude ReportedID Flow Peak Flow Capacity Design Flow Velocity Time Depth Depth/ Surcharged Number ConditionOccurrenceRatioTotal DepthRatio(cfs) (days hh:mm) (cfs)(ft/sec) (min) (ft)(min)1 SD-1 1.32 0 00:06 5.16 0.26 6.62 0.20 0.34 0.34 0.00 Calculated2 SD-2 3.30 0 00:06 6.55 0.50 5.36 0.13 0.63 0.50 0.00 Calculated
Inlet Input
SN Element Inlet Manufacturer Inlet Number of Catchbasin Max (Rim) Inlet Initial Initial Ponded GrateID Manufacturer Part Location Inlets Invert Elevation Depth Water Water Area CloggingNumberElevationElevation Depth Factor(ft) (ft) (ft) (ft) (ft) (ft²) (%)1 Inlet-1 FHWA HEC-22 GENERIC N/A On Sag 1 4781.61 4784.72 3.11 4781.61 0.00 10.00 0.002 Inlet-2 FHWA HEC-22 GENERIC N/A On Sag 1 4779.68 4782.84 3.16 4779.68 0.00 10.00 0.00
Roadway & Gutter Input
SN Element Roadway Roadway Roadway Gutter Gutter Gutter AllowableID Longitudinal Cross Manning's Cross Width Depression SpreadSlope Slope Roughness Slope(ft/ft) (ft/ft)(ft/ft) (ft) (in) (ft)1 Inlet-1 N/A 0.0160 0.0130 0.0620 1.50 0.0000 7.002 Inlet-2 N/A 0.0230 0.0130 0.0620 1.50 0.0000 7.00
Inlet Results
SN Element Peak Peak Peak Flow Peak Flow Inlet Max Gutter Max Gutter Max Gutter Time of Total Total TimeID Flow Lateral Intercepted Bypassing Efficiency Spread Water Elev. Water Depth Max Depth Flooded FloodedInflow by Inlet during Peak during Peak during Peak during Peak Occurrence VolumeInletFlow Flow Flow Flow(cfs) (cfs) (cfs) (cfs) (%) (ft) (ft)(ft) (days hh:mm) (ac-in) (min)1 Inlet-1 1.33 1.33 N/A N/A N/A 9.84 4784.95 0.23 0 00:06 0.00 0.002 Inlet-2 2.02 2.02 N/A N/A N/A 9.96 4783.13 0.29 0 00:06 0.00 0.00
Appendix C
Storm Drainage Plans
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DETAIL1C5.1CURB AND GUTTER
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DETAIL4C5.1TYPICAL PAVEMENT SECTIONDET
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DETAIL1C5.2ACCESSIBLE PARKINGDETAIL4C5.2LANDSCAPE ISLAND DRAI
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