HomeMy WebLinkAboutSewer System AnalysisSEWER SYSTEM ANALYSIS
FOR
SONOMA SUBDIVISION
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COLLEGE STATION, TEXAS
JUNE2007
MBESI# 1053-0005
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McCLURE & BROWNE ENGINEERING/SURVEYING, INC.
1008 Woodcreek Drive, Suite 103 •College Station, Texas 77845
(979) 693-3838 • Fax: (979) 693-2554 •Email: McClureBrowne@Verizon.net
SEWER SYSTEM ANALYSIS
FOR
OFFSITE SEWER LINE
General Information
Approximate area to be served by this line: 761 acres
Anticipated land use: Single family residential
Commercial (C-3)
Future High School
Number of platted lots: 458 lots
Notes on surrounding development: This proposed sewer line is intended to serve the
upper portions of the spring creek sewer basin.
Currently a portion of this drainage basin is single
family residential housing in the Sonoma
Subdivision. The future land use for the basin
includes single family housing, small tracts of light
commercial (C-3), and a future high school for
College Station ISD.
Primary outfall line:
Software model:
Average daily flow:
Peaking factor:
Pipe Material:
Manning's N value:
Note about Future Extension:
Sewer System Analysis
An existing 21" sewer line located south of the existing Reatta
Meadows subdivision.
Microsoft EXCEL Spreadsheed based on Manning's Equation
267 gpd per existing or platted residential lots
1335 gpd per acre for undeveloped residential land use (5 lots/acre)
(this assumes a higher density than any of the existing
residential developments in the surrounding area)
1050 gpd per acre for school (35 per/acre)
750 gpd per acre for commercial (25 per/acre)
4.0
PVC (D3034) & DIP
0.013
The calculations shown in this report assume that the entire area
shown on the drainage area map (Exhibit A) will be sewered
through this line, however approximately 200 acres of this area
naturally drains back to the west towards FM 2154. The future
sewer line extension shown on Exhibit A is a possible route for the
future line. Assuming that the 15" line is extended along this route
with a 0.25% slope and manholes every 500' with a 0.1' drop in
each one, the line would be approximately 8' deep at its
termination adjacent to FM 2154. Since a large portion of the
proposed sewer drainage area lies on the west side of the
drainage divide, parts of the 15" line will require cuts in excess
of 35' in order to extend this line.
Sonoma Subdivision
Off-Site Sewer Line Report
MBESI #10530005
Spreadsheet Notes:
Conclusion:
Applicable Exhibits:
Exhibit A
Exhibit B
The spreadsheet in Exhibit A computes the anticipated flowrates
from each area and the minimum slopes of the lines that serve
those areas. It compares the computed slope with the required
minimum slope and the design slope from the plans (when
available). If the computed slope is less than the minimum or less
than the design slope, the spreadsheet indicates the line is "OK".
If not, it indicates the line is "Flat".
All of the lines in the spreadsheet on Exhibit A indicate they
are OK and thus meet the design guidelines of the City of
College Station. Therefore, we conclude that the lines are
adequately sized and will easily carry the sewage flows that are
expected to pass through them.
Schematic Sewer System Layout
Sewer Model Spreadsheet
Sonoma Subdivision
Off-Site Sewer Line Report
MBESI #10530005
Linc
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p,; e. f;: () ]
267 1335 35 25
OPDper OPDper OPDper OPD per
MH# MH# Lot Acre Per.son Per.son OPD
I 2 26 330 0 0 447,492
2 3 0 70 0 0 93,450 447,492
3 4 165 17 0 3.88 66,847 540,942
4 El 0 18 64 0 26,270 607,789
El E2 267 17 0 3.8 94,079 634,059
Exhibit B
Spring Creek Sanitary Sewer Extension
Sanitary Sewer Analysis
Flow Calculations
Manning Min.
Average Daily Flows Infiltration Peaking Peek Inside Friction Design Size Material (ADF) (IOo/oADF) Factor Flows Diameter Slope Slope
ADF ADF
OPD CFS CFS CFS (in.) Inches o/o o/o
447,492 0.6924 0.0692 4.00 2.84 15 D3034 14.124 0.0762 0.15
540,942 0.8369 0.0837 4.00 3.43 18 DIP 18.88 0.0237 0.20
607,789 0.9404 0.0940 4.00 3.86 18 DIP 18.88 0.0299 0.20
634,059 0.9810 0.0981 4.00 4.02 18 DIP 18.88 0.0325 0.20
728,138 1.1266 0.1127 4.00 4.62 21 D2241 20.25 0.0295 0.20
Pipe Calculations
Manning Min.
Ave. Daily Ave. Daily Friction Design
Flow Flow Slope Slope
Velocity Depth Peek Peek
Flows Flows
fps Inches o/o o/o
2.43 4.24 0.2645 0.26
2.62 3.78 0.0822 0.20
2.68 3.78 0.1038 0.20
2.74 4.72 0.1130 0.20
2.22 5.06 0.1025 0.20
Actual
Slope for
Existing Pipe Peek Peek
Slope Flow Flow or Check Velocity Depth Designed
Systems
o/o fps Inches
0.35 OK 3.37 9.89
0.40 OK 3.78 8.50
0.40 OK 3.89 9.44
0.40 OK 3.94 9.44
0.20 OK 3.12 12.15
I 0530005-0ff-site Sower Line.xls
6/1/2007
ExhibiLB