HomeMy WebLinkAboutSanitary Sewer ReportPreliminary Design Report
Proposed Sanitary Sewer Line Improvements
for
Dove Crossing Subdivision
Phases 1, 2, 3 & 4
College Station, Texas
September 2004
Prepared By:
TEXCON General Contractors
1707 Graham Road
College Station, Texas 77845
(979) 764 -7743
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1.0 INTRODUCTION & DESCRIPTION
The purpose of this report is to provide a description of the proposed sanitary sewer to be
constructed with the Dove Crossing Subdivision, and to provide the criteria used in the
design of this sanitary sewer system. The project will include the construction of
approximately 15,820 feet of sanitary sewer line. The sewer lines will service the
proposed development of the Dove Crossing Subdivision (Phases 1 -4), as well as the
future development of the adjacent parcels of land to the north and east of this
development.
The proposed sewer lines for Phase 1 will gravity drain to the existing 10" diameter sewer
line located in the right -of -way of Graham Road. The proposed sewer lines for Phases 2, 3
& 4 will drain to the existing 15" diameter line along the south boundary of the project.
The sewer lines to service Phase 2 of the subdivision will be constructed through Phases 3
and 4 of the subdivision in order to tie into the existing line.
2.0 SANITARY SEWER - Design Flow and Pipe Size Calculations
The proposed sewer lines are to be constructed of 6" and 8" diameter SDR -26, PVC pipe
which meets the requirements of ASTM- D3034. Until final design slopes are determined,
sewer line slopes have been evaluated at the minimum allowable slope (0.4% for 8" line
and 0.8% for 6" line) to determine the "worst case" scenario. The proposed manholes are
4' diameter manholes. The maximum distance between manholes is less than 500 feet, as
required by the Texas Commission on Environmental Quality (TCEQ). All construction
will meet the current City of College Station Standard Specifications for Sanitary Sewer
Construction. The sewer line information is summarized in the attached tables, and the
attached sketch shows manhole numbers and locations.
3.0 DETERMINATION OF PEAK FLOW VALUES
The peak flows were based on using a daily use of 300 gallons per day for each dwelling
unit. The design peak flow is determined by multiplying the average daily flow by 4.0,
which results in the peak hourly flow. For the adjacent tracts of land, a density of 5
dwelling units per acre was used. Also, it is assumed that half of the Lee and Tolson tracts
will be sewered to the north to the existing line along the North Fork of Lick Creek. The
velocities for the lines were calculated using Manning's Equation (n= 0.013). According to
the TCEQ, the minimum velocity for sewer systems flowing full is 2.0 feet per second. As
shown in the attached tables, the minimum anticipated flow velocities for the proposed
sewer lines at 50% full meet this requirement. The flow for 100% full will not be less than
the flow for 50% full; therefore, the TCEQ requirement is met. The TCEQ requires that
the maximum velocity for sewer systems flow full not exceed 10 feet per second. The
values in the attached tables are well below this maximum velocity.
4.0 CONCLUSIONS
It is our determination based on the criteria and data developed that the proposed sewer
lines will provide sufficient capacity for the anticipated wastewater Flows generated by this
development and the future development of the adjacent tracts to the north and east of this
project.
Dove Crossing Subdivision - Sewer Line Flow Data
Manhole
Number
Size
Length
Slope
No. of
Dwelling Unit
services
Units From
Merging
Lines
Cumulative
Dwelling
units
Average
Daily Flow
Peak Flow
Percent
Full
50% Full
Flow
(cfs)
Velocity
(fps)
From To
(in)
(ft)
( %)
(gpm) (Cfs)
(cfs)
( %)
CO -2 3 8 59.9 0.40 2 2 0.42 0.0009 0.0037 5.0 0.3821 2.2
CO -3
3
8
209.5
0.40
5
5
1.04
0.0023
0.0093
7.7
0.3821
2.2
3
2
8
332.6
0.40
10
2
17
+
0.0079
0.0316
13.9
0.3821
2.2
2
1
8
224.9
0.40
8
-
25
5.21
0.0116
0.0464
16.7
0.3821
2.2
r
5 4 8 455.1 0.40 18 18 3.75 0.0084 0.0334 14.2 0.3821 2.2
m
N
L
7
6
8
278.2
0.40
12
12
2.50
0.0056
0.0223
11.7
0.3821
2.2
a
6
4
8
258.0
0.40
9
-
21
4.37
0.0097
0.0390
15.4
0.3821
2.2
4
1
8
317.0
0.40
0
18
39
8.12
0.0181
0.0724
20.8
0.3821
2.2
CO -1
11
8
290.5
0.40
10
-
10
2.08
0.0046
0.0186
10.8
0.3821
2.2
11
10
8
235.7
0.40
8
-
18
3.75
0.0084
0.0334
14.2
0.3821
2.2
10
9
8
316.4
0.40
10
-
28
5.83
0.0130
0.0520
17.7
0.3821
2.2
9
8
8
474.5
0.40
11
-
39
8.12
0.0181
0.0724
20.8
0.3821
2.2
8
1
8
479.8
0.40
16
-
55
11.46
0.0255
0.1021
24.7
0.3821
2.2
1
Existing
8
120.9
0.40
0
64
119
24.79
TO.0552
0.2209
36.8
0.3821
2.2
Existing Stub 10 - 0.25 0 119 24.79 1 0.0552 0.2209 30.5 0.5477 2.0
Dove Crossing Subdivision - Sewer Line Flow Data
Manhole
Number
Size
Length
Slope
No. of
Dwelling Unit
services
Units From
Merging
Lines
cumulative
Dwelling
units
Average
Daily Flow
Peak Flow
Percent
Full
50%
Flow
(cfs)
(in)
(ft)
N
(gpm(cfs)
N
18 16 6 293.5 0.80 10 10 2.08 0.0046 0.0186 13.2 0.2509 2.6
19 15 6 293.5 0.80 10 10 2.08 0.0046 0.0186 13.2 0.2509 2.6
20 14 6 293.6 0.80 10 10 2.08 0.0046 0.0186 13.2 0.2509 2.6
21 13 6 301.6 0.80 10 - 10 2.08 0.0046 0.0186 13.2 0.2509 2.6
17
16
6
137.5
0.80
5
5
1.04
0.0023
0.0093
9.4
0.2509
2.6
16
15
8
303.0
0.40
4
10
19
3.96
0.0088
0.0353
14.6
0.3821
2.2
15
14
8
274.0
0.40
5
10
34
7.08
0.0158
0.0631
19.4
0.3821
2.2
14
13
8
276.0
0.40
5
10
49
10.21
0.0227
0.0909
23.2
0.3821
2.2
13 1
12
8
169.1
1 0.40
1 2
1 10
61
12.71
0.0283
0.1132
26.0
0.3821
2.2
31
30
6
217.1
0.80
10
-
10
2.08
0.0046
0.0186
13.2
0.2509
2.6
30
29
6
381.7
0.80
14
-
24
5.00
0.0111
0.0445
20.1
0.2509
2.6
29
27
6
436.4
0.80
14
24
38
7.92
0.0176
0.0705
25.3
0.2509
2.6
33
32
6
325.7
0.80
14
14
2.92
0.0065
0.0260
15.5
0.2509
2.6
32
25
6
383.4
0.80
12
26
5.42
0.0121
0.0483
21.0
0.2509
2.6
Future
35
-
-
-
25
25
5.21
0.0116
0.0464
-
-
-
35
34
8
191.8
0.40
3
28
5.83
0.0130
0.0520
17.7
0.3821
2.2
Rt
34
26
8
455.1
0.40
14
42
8.75
0.0195
0.0780
21.6
0.3821
2.2
06
N
37
36
=
324.7
0.80
14
14
2.92
0.0065
0.0260
15.5
0.2509
2.6
CAI
m
36
24
6
383.4
0.80
12
-
26
5.42
0.0121
0.0483
21.0
0.2509
2.6
N
M
a
39
38
6
388.3
0.80
16
16
3.33
0.0074
0.0297
16.5
0.2509
2.6
38
24
6
343.8
0.80
12
28
5.83
0.0130
0.0520
21.7
0.2509
2.6
41
40
6
323.5
0.80
14
14
2.92
0.0065
0.0260
15.5
0.2509
2.6
40
23
6
383.4
0.80
12
26
5.42
0.0121
0.0483
21.0
0.2509
2.6
43
42
6
331.5
0.80
15
15
3.12
0.0070
0.0278
16.0
0.2509
2.6
42
23
6
343.1
0.80
12
27
5.62
0.0125
0.0501
21.3
0.2509
2.6
45
44
6
326.0
0.80
14
-
14
2.92
0.0065
0.0260
15.5
0.2509
2.6
44
22
6
383.5
0.80
12
26
5.42
0.0121
0.0483
21.0
0.2509
2.6
Future
51
135
-
135
28.12
0.0626
0.2506
-
-
51
48
8
108.5
0.40
0
135
28.12
0.0626
0.2506
39.4
0.3821
2.2
50
49
6
293.7
0.80
6
6
1.25
0.0028
0.0111
10.3
0.2509
2.6
49
48
6
404.2
0.80
8
14
2.92
0.0065
0.0260
15.5
0.2509
2.6
48
47
8
85.1
0.40
3
135
152
31.66
0.0705
0.2821
42.1
0.3821
2.2
47
46
8
381.4
0.40
14
-
166
34.58
0.0770
0.3081
44.2
0.3821
2.2
46
22
8
393.4
0.40
14
180
37.49
0.0835
0.3341
46.3
0.3821
2.2
28
27
6
208.1
0.80
5
-
5
1.04
0.0023
0.0093
9.4
0.2509
2.6
27
26
8
278.0
0.40
4
38
47
9.79
0.0218
0.0872
22.8
0.3821
2.2
26
25
8
327.8
0.40
12
42
101
21.04
0.0469
0.1875
33.7
0.3821
2.2
25
24
8
301.0
0.40
0
26
127
26.45
0.0589
0.2357
38.1
0.3821
2 2
24
23
8
276.0
0.40
0
54
181
37.70
0.0840
0.3359
46.4
0.3821
2.2
23
22
8
276.0
0.40
0
53
234
48.74
01086
0.4343
54.0
0.3821
2.2
22
Exist ng
8
169.2
0.40
0
206
440
91.65
0.2042
0.8166
90.6
0.3821
2. 2
Graham Road
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