HomeMy WebLinkAbout13-1 - Sewer Report 2020-03-03 1
Sewer
This section is a response to the requirements of the City of Bozeman Unified Development
Ordinance Section 38.220.060 relative to Water and Sewer. The original Sanitary Sewer Design
Report provides analysis for the entire PUD including Phase 5. Flows from Phase 5 are designed
to flow east to the existing sewer main in Fowler Avenue (see updated sewer main exhibit).
Since the report was written, the City of Bozeman Design Standards and Specifications have
been revised to reflect a lower required flow rate for B-2 zoning, decreasing from 3495
gal/ac/day to 2000 gal/ac/day. Previous calculations combined with the reduction in B-2 flow
rates indicate that the existing system will meet the required sewer design criteria for Phase 4 of
the Bozeman Gateway.
The manhole located at the intersection of Fowler and Technology Blvd was dipped on
12/30/2019 and was found to have a sewage depth of 0.2’. Due to the timing of this measurement
during the holiday season, it is conservatively assumed that the average existing flow depth is
0.5’. The outlet pipe has a diameter of 21”. Assuming a minimum slope of 0.1% has a capacity
flowing full of 6.3cfs (2,827.6gpm). At a depth of 0.5’ the pipe is approximately 29% full and
flowing at a rate of 1.06cfs (475.8gpm). Based on the Sewer Facility Plan’s 2000 gal/ac/day for
6.9 acres, the wastewater produced by Phase 5 is 13,800gpd or 0.02cfs (8.98gpm). The
contribution of Phase 5 increases the flow to 1.08cfs (495gpm) which equates to a pipe depth of
0.51 or 29%. The 21” pipe has more than enough capacity to accommodate the development.
Channel Report
Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc.Tuesday, Dec 31 2019
Existing Pipe Flow
Circular
Diameter (ft) = 1.75
Invert Elev (ft) = 100.00
Slope (%) = 0.10
N-Value = 0.011
Calculations
Compute by: Known Depth
Known Depth (ft) = 0.50
Highlighted
Depth (ft) = 0.50
Q (cfs) = 1.061
Area (sqft) = 0.57
Velocity (ft/s) = 1.86
Wetted Perim (ft) = 1.98
Crit Depth, Yc (ft) = 0.37
Top Width (ft) = 1.58
EGL (ft) = 0.55
0 1 2 3
Elev (ft)Section
99.50
100.00
100.50
101.00
101.50
102.00
Reach (ft)
Channel Report
Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc.Sunday, Dec 29 2019
21in PVC Flowing Full
Circular
Diameter (ft) = 1.75
Invert Elev (ft) = 100.00
Slope (%) = 0.10
N-Value = 0.011
Calculations
Compute by: Q vs Depth
No. Increments = 10
Highlighted
Depth (ft) = 1.58
Q (cfs) = 6.312
Area (sqft) = 2.28
Velocity (ft/s) = 2.77
Wetted Perim (ft) = 4.38
Crit Depth, Yc (ft) = 0.93
Top Width (ft) = 1.05
EGL (ft) = 1.69
0 1 2 3
Elev (ft)Section
99.50
100.00
100.50
101.00
101.50
102.00
Reach (ft)
Channel Report
Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc.Monday, Jan 20 2020
Proposed Pipe Flow
Circular
Diameter (ft) = 1.75
Invert Elev (ft) = 100.00
Slope (%) = 0.10
N-Value = 0.011
Calculations
Compute by: Known Q
Known Q (cfs) = 1.08
Highlighted
Depth (ft) = 0.51
Q (cfs) = 1.080
Area (sqft) = 0.59
Velocity (ft/s) = 1.83
Wetted Perim (ft) = 2.00
Crit Depth, Yc (ft) = 0.37
Top Width (ft) = 1.59
EGL (ft) = 0.56
0 1 2 3
Elev (ft)Section
99.50
100.00
100.50
101.00
101.50
102.00
Reach (ft)
OPEN SPACE 2
OPEN SPACE 3
OPEN SPACE 4
COMMON AREA 1ALOT 1A1
LOT 3A
LOT 1A LOT 4 LOT 5
LOT 6
LOT 7
LOT 5
OPEN SPACE 5COMMON AREA 2A
OPEN SPACE 6
LOT 14A COMMON AREA 3A LOT 16A
COMMON AREA 4A
LOT 17A
LOT 25A
LOT 22B
LOT 46
LOT 45
COMMON AREA 12
LOT 48
COMMON AREA 7
COMMON AREA 6A
LOT 24A
LOT 23A
OPEN SPACE 10
LOT 1
LOT 2
LOT 3
LOT 4
LOT 1A
LOT 5
LOT 6
LOT 3 LOT 4
OPEN SPACE 1
LOT 1
LOT 6
LOT 7
COMMON AREA 5A LOT 19A
LOT 2A1
LOT 4A
LOT 35
LOT 36
COMMON AREA 11
LOT 37
LOT 38
COMMON AREA 10
LOT 40
LOT 41
LOT 42
COMMON AREA 14 COMMON AREA 13
LOT 44 LOT 43
OPEN SPACE 1B
COMMON AREA 8
OPEN SPACE 1A
LOT 2
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CONNECTION POINT
EXST. MH JO516
CONNECTION POINT
EXST. MH JO602
2W
1W
3W
5W
4W
1E
2E
3E
4E
1W ANALYZED SANITARY SEWER SEGMENT
SEE APPENDIX A & B
PROPOSED SANITARY
SEWER MAIN
PROPERTY BOUNDARY
LEGEND
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SSBOZEMAN GATEWAY
SEWER LAYOUT