HomeMy WebLinkAboutTract 7140 SEWER STUDYSEWER STUDY
Tract No. 7140
Objective
The objective of this study is as follows:
1) The purpose of this study is to determine the sewer discharge from Tract 7140 and to
determine if any surrounding areas may be served by a main line extension.
Existing Facilities
The site is currently undeveloped and surrounded by undeveloped land to the south and west
with the school site to the east. Tract 7213 is planned for the land to the west and tract 7165
is planned for the land to the south. Berkshire Road exists to the north. One hundred six lots
of Tract 7140 will discharge to an existing 30-inch sewer line, part of the Ashe Road Trunk,
and ultimately to the Wastewater Treatment Plant #3.
Planned Land Uses
Tract 7140 is a residential development and will consist of 110 single family dwellings and a
temporary drainage basin. The drill island may be developed into 12 single family dwellings
at a future date.
Phasing
The project consists of three phases. Phase 1 contains 36 single family homes plus the
possible future development of the drill site. Phase 2 contains 24 single family homes and,
Phase 3 contains 50 single family homes.
Design
The proposed development will be serviced by an existing 30” sewer located on the east side
of Ashe Road, just south of Berkshire Road. The existing 30” sewer was constructed as part
of Ashe Road Trunk Line. Due to the terrain and cover restrictions, we are proposing to
construct 8” PVC sewer lines at a slope of 0.25%.
Our calculations, shown below and in the enclosed spreadsheet, show that the proposed 8”
line will work. Tract 7140 is expected to generate 0.186 cfs of sewer. All of Tract 7213,
which is to be developed at a future date, will generate a flow of 0.177 cfs, shown in Pipe 3.
The overall discharge produced for the developed condition is 0.363 cfs.
V = 1.486 R2/3S1/2 and Q = AV
n
Where “V” is the average velocity in feet per second
“n” is Manning’s coefficient
“A” is the area based on the pipe size
For plastic pipe: n = 0.011
1.486 = 135.091
n
“R” is the hydraulic radius in feet and “S” is the slope in feet per foot.
Sewer Main Allowable Flow Characteristics
8” @ 0.250% V = 135.091 x 0.304 x 0.050 = 2.053 fps
A = 0.349 sf
Q = 0.72 cfs
Calculations are attached in spreadsheet form.
Results
Tract 7140 has been divided into 3 phases and the sewer has been design to serve each phase
as it is constructed. It is calculated that the project, with future development of the drill
island, will generate 0.186 cfs of sewer. The system is designed to use 8” PVC pipe at 0.25%
throughout most of the site. The last 100 feet of all reaches are 6” PVC at 1%. The site
discharges to a proposed manhole on the east side of Ashe Road, an invert of 342.22 will be
used at this connection point. The new manhole will become part of the Ashe Road Trunk
line which discharges to the Wastewater Treatment Plan No 3.
The sewer system within the tract is very shallow. We are able to provide minimum cover by
using PVC pipe and minimizing the slope of the pipe to 0.25%. This system can service
Tract 7140 as well as Tract 7213.
C.E.Q.A. Compliance
Development of the proposed project will not result in significant impacts to the existing and
proposed sewer collection and treatment facilities. The development will be serviced by the
City of Bakersfield’s Wastewater Treatment Plant No. 3 which currently has a capacity of
32.0 million gallons per day.
Blaine Neptune
R.C.E. 55102
SEWER STUDY 2/27/15
Tract 7140
Minimum Velocity Full:2
Maninings "n":0.011
Cumulat.PeakTotal Req'd.DesignCapacity
SERVICELandDEN.AREAE.D.U.AverageAverageAve. Res.PeakFlowDesignU.S.U.S.ReachSizeSlopeSlopeD.S.D.S.at Design
AREAUseDU/ACacrescfs/acFlow,cfsFlow,cfsFactorcfsFlow,cfsM.H.INV.lengthInchesINV.M.H.Slope, cfs
Initial Development
Pipe 28SF 4 0.001245.1760.006 --1006 0.003507 0.010000 --0.663
Pipe 26 (A) & (B)SF8 0.002474.8300.018 --2328 0.002390 0.002500 348.40 140.714
Pipe 25SF4 0.001245.1760.006 CO4 350.25 1006 0.003507 0.010000 349.25 150.663
Pipe 24SF8 0.002474.8300.018 15 349.12 2898 0.002390 0.002500 348.40 140.714
Point of Confluence @ MH 14 0.007420.037 14 348.30 2808 0.002390 0.002500 347.60 130.714
Pipe 9SF 0 0.000000.0000.037 14 348.30 2808 0.002390 0.002500 347.60 130.714
Pipe 27SF4 0.001245.1760.006 CO8 349.61 1006 0.003507 0.010000 348.61 190.663
Pipe 23SF8 0.002474.8300.018 19 348.65 2718 0.002390 0.003500 347.70 130.845
Pipe 22SF4 0.001245.1760.006 CO7 349.55 1006 0.003507 0.010000 348.55 180.663
Pipe 21SF8 0.002474.8300.018 18 348.42 2898 0.002390 0.002500 347.70 130.714
Point of Confluence @ MH 13 0.014840.073 13 347.30 2808 0.002390 0.002500 346.60 120.714
Pipe 8SF 0 0.000000.0000.073 13 347.60 2808 0.002390 0.002500 346.90 120.714
Pipe 20SF 4 0.001245.1760.006 CO6 349.00 1006 0.003507 0.010000 348.00 170.663
Pipe 19SF8 0.002474.8300.018 17 347.87 2498 0.002390 0.003500 347.00 120.845
Pipe 18SF4 0.001245.1760.006 CO5 349.13 1006 0.003507 0.010000 348.13 160.663
Pipe 17SF8 0.002474.8300.018 16 348.00 2878 0.002390 0.003500 347.00 120.845
Point of Confluence @ MH 12 0.022260.110 12 346.90 2908 0.002390 0.002500 346.18 70.714
Pipe 7SF 0 0.000000.0000.110 12 346.90 2908 0.002390 0.002500 346.18 70.714
Pipe 16SF4 0.001245.1760.006 CO1 348.83 1276 0.003507 0.010000 347.56 80.663
Pipe 15SF12 0.003714.6380.024 8 347.43 3858 0.002390 0.003500 346.08 70.845
Point of Confluence @ MH 7 0.027210.134 7 335.90 1908 0.002390 0.00250060.714
Pipe 14SF 4 0.001245.1760.006 CO3 346.87 1508 0.002390 0.002500 346.50 90.714
Pipe 13SF 4 0.001245.1760.006 CO2 349.06 1006 0.003507 0.010000 348.06 110.663
Pipe 12SF 8 0.002474.8300.018 11 347.93 2728 0.002390 0.002500 347.25 100.714
Pipe 11SF 8 0.002474.8300.030 10 347.25 3008 0.002390 0.002500 346.50 90.714
Point of Confluence @ MH 9 0.007420.037 9 346.40 2808 0.002390 0.002500 345.70 60.714
Pipe 10SF 0 0.000000.0000.037 9 346.40 2808 0.002390 0.002500 345.70 60.714
Pipe 6SF 5 0.001555.0620.142 7 346.08 1908 0.002390 0.002500 345.60 60.714
Point of Confluence @ MH 6 0.036180.178 6 345.86 4088 0.002390 0.002500 344.84 50.714
Pipe 5SF 5 0.001555.0620.186 6 345.60 3048 0.002390 0.002500 344.84 50.714
Pipe 4SF 0 0.000000.0000.186 5 344.84 3008 0.002390 0.002500 344.09 40.714
Pipe 3SF 160 0.049483.5790.363 4 344.07 2808 0.002390 0.003500 343.09 30.845
Pipe 2SF 0 0.000000.0000.363 3 343.09 3288 0.002390 0.003500 341.94 20.845
Point of Confluence @ MH 2 0.08720 0.363 <<< Direct Flow into Exist. 30" from Tract 7140 & Tract 7213
P:\PROJECTS\13086.00-TR7140\Studies\Sewer\REPORT\13086SS01.xls
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