20070295 Ver 6_4.01 Post-Hydrology Inputs_20191220

Holding Village - North Lake POST -DEVELOPMENT HYDROLOGY Maria Torres, E.I.
RAP-19000 Summary of Results Daniel Gunter
FYDROLOGY INPUT SUMMARY 12.16.2019
Sub -basin ID
Onsite Area [acres]
SCS CN Tc [min]
79 19.72
Impervious
Open
Wooded
Pond
Total
Sub 1 to Lake
50.88
39.45
11.76
12.89
114.98
Sub 1 Bypass
1.63
7.30
2.00
0.00
10.92
82
9.89
4 Bypass
1.24
1.84
1.90
0.00
4.98
69
8.78
4 to SCM A
10.31
5.84
2.13
0.41
18.69
82
5.00
5 Bypass
0.34
0.96
1.55
0.00
2.85
64
8.17
5 to SCM B
7.90
3.27
1.55
0.27
12.98
84
5.00
6
0.40
0.52
1.08
0.00
2.00
66
6.89
7 to SCM C
5.07
3.98
0.00
0.40
9.45
83
5.00
7 Bypass
0.00
1
1.70
0.87
0.00
2.57
1 61
11.19
Totals =
77.76 64.86 22.84 13.97
179.43

Holding Village - North Lake POST -DEVELOPMENT HYDROLOGY Maria Torres, E.I.
RAP-19000 Sub 1 to Lake Daniel Gunter
12.16.2019
I. SCS CURVE NUMBERS
Assume:
HSG
Impervious
Open
Wooded
1/8 ac lots
1/4 ac lots
Commercial
Industrial
A
98
39
30
77
61
89
81
B
98
61
55
85
75
92
88
C
98
74
70
90
83
94
91
D
98
80
77
92
87
95
93
HSG 'A' = 10.5%
HSG'B'= 66.4%
HSG 'C' = 0.0%
HSG'D'= 22.9%
Cover Condition
SCS CN
Comments
Impervious
98
Open
63
Assume good condition
Wooded
57
Assume good condition
Residential 1/8 ac)
86
Assume 1/8 acre lots
Residential 1/4 ac)
76
Assume 1/4 acre lots
Commercial
92
Industrial
88
North Lake
South Lake
;ontributing Area
# of Units
Area / Unit
e 'A' Total Imp.
39.5
3658
ype 'B'Total Imp.
34
3214
e'C'TotalImp.
6
3384
Type 'D'Total
5
3028
Type 'E'Total
10
1 2406
Contributing Area
# of Units
Area / Unit
Total Area
24-ft (TH) Lot Impervious
58
1,600
92,800
2.13
34-ft Lot Impervious
45.5
2,460
111,930
2.57
40-ft Lot Impervious
28
3,030
84,840
1.95
50-ft Lot Impervious
15
3,580
53,700
1.23
55-ft Lot Impervious
0
4,005
0
0.00
75-ft Lot Impervious
0
6,355
0
0.00
Right-of-way Impervious
-
-
314,287
7.22
Amenity (10%)
4,931
0.11
Apartments (80%)
-
144,305
3.31
Totals
146.5
806,793
18.52
II. POST -DEVELOPMENT
A. Watershed Breakdown
South Lake
Contributing Area
SCS CN
Area [sfj
Area acres
Comments
Impervious
98
466,557
10.71
Open
63
1,103,421
25.33
Assume good condition
Wooded
57
512,053
11.76
Assume good condition
Pond
100
561,526
12.89
-
Residential (1/8 ac)
86
0
0.00
Assume 1/8 acre lots
Residential (1/4 ac)
76
395,974
9.09
Assume 1/4 acre lots
Commercial
92
62,580
1.44
Industrial
88
484,466
11.12
North Lake
Contributing Area
SCS CN
Area [sf]
Area [acres]
Comments
Impervious
98
806,793
18.52
Open
63
615,096
14.12
Assume good condition
Wooded
57
0
0.00
Assume good condition
Pond
100
0
0.00
Commercial
92
0
0.00
Industrial
1 88
1 0
1 0.00
Total area =
Composite SCS CN =
114.98 acres
5,008,466 sq. ft
79

Holding Village - North Lake POST -DEVELOPMENT HYDROLOGY Maria Torres, E.I.
RAP-19000 Sub 1 to Lake Daniel Gunter
12.16.2019
B. Time of Concentration Information
Time of concentration is calculated using the SCS Segmental Approach (TR-55).
Segment 1: Overland Flow
Length =
Height =
Slope =
Manning's n =
P (2-year/24-hour) =
Segment Time =
Segment 3: Channel Flow
Length =
Height =
Slope =
Manning's n =
Flow Area =
Wetted Perimeter=
Channel Velocity=
Segment Time =
100
ft
3
ft
0.0300
ft/ft
0.24
dense grasses
3.45
inches (Wake Forest, NC)
11.69
minutes
1485
ft
54
ft
0.0364
ft/ft
0.045
Natural Channel
4.00
sf (Assume 2' x 2' Channel)
6.00
ft (Assume 2' x 2' Channel)
4.82
ft/sec
minutes
Segment 2: Concentrated Flow
Length =
680
ft
Height =
40
ft
Slope =
0.0588
ft/ft
Paved ? =
No
Velocity =
3.91
ft/sec
Segment Time =
2.90
minutes
Time of Concentration = 19.72 minutes
SCS Lag Time = 11.83 minutes (SCS Lag = 0.6* Tc)
Time Increment = 3.43 minutes (= 0.29*SCS Lag)

Holding Village - North Lake POST -DEVELOPMENT HYDROLOGY Maria Torres, E.I.
RAP-19000 Sub 1 Bypass Daniel Gunter
12.16.2019
Assume:
HSG
Impervious
Open
Wooded
1/8 ac lots
1/4 ac lots
Commercial
Industrial
A
98
39
30
77
61
89
81
B
98
61
55
85
75
92
88
C
98
74
70
90
83
94
91
D
98
80
77
92
87
95
93
HSG 'A' = 0.0%
HSG 'B' = 0.0%
HSG 'C' = 0.0%
HSG 'D' = 100.0%
Cover Condition
SCS CN
Comments
Impervious
98
Open
80
Assume good condition
Wooded
77
Assume good condition
Residential 1/8 ac)
92
Assume 1/8 acre lots
Residential 1/4 ac)
87
Assume 1/4 acre lots
Commercial
95
Industrial
93
II. POST -DEVELOPMENT _
A. Watershed Breakdown
;ontributing Area
# of Units
Area / Unit
ype'A'TotalImp.
5
3658
e'B'TotalImp.
3
3214
ype 'C'Total Imp.
0
3384
Type 'D'Total
0
3028
Type 'E'Total
0
2406
Contributing Area
SCS CN
Area sf
Area acres
Comments
Impervious
98
70,794
1.63
Open
80
317,776
7.30
Assume good condition
Wooded
77
87,295
2.00
Assume good condition
Pond
100
0
0.00
-
Residential (1/8 ac)
92
0
0.00
Assume 1/8 acre lots
Residential (1/4 ac)
87
0
0.00
Assume 1/4 acre lots
Commercial
95
0
0.00
Industrial
93
0
0.00
Total area =
Composite SCS CN =
10.92 acres
475,865 sq.ft
82

Holding Village - North Lake
POST -DEVELOPMENT HYDROLOGY
RAP-19000
Sub 1 Bypass
B. Time of Concentration Information
Time of concentration is calculated using the SCS Segmental Approach (TR-55).
Segment 1: Overland Flow
Segment 2: Concentrated
Flow
Length =
100
ft
Length =
251
ft
Height =
9
ft
Height =
25
ft
Slope =
0.0900
ft/ft
Slope =
0.0996
ft/ft
Manning's n =
0.24
dense grasses
Paved ? =
No
P (2-year/24-hour) =
3.45
inches (Wake Forest, NC) Velocity=
5.09
ft/sec
Segment Time =
7.53
minutes
Segment Time =
0.82
minutes
Segment 3: Channel Flow
Length =
Height =
Slope =
Manning's n =
Flow Area =
Wetted Perimeter=
Channel Velocity =
Segment Time =
512
ft
36
ft
0.0703
ft/ft
0.045
Natural Channel
2.00
sf (Assume 2' x 1' Channel)
4.00
ft (Assume 2' x 1' Channel)
5.53
ft/sec
1.54
minutes
Time of Concentration = 9.89 minutes
SCS Lag Time = 5.94 minutes (SCS Lag = 0.6* Tc)
Time Increment = 1.72 minutes (= 0.29*SCS Lag)
Maria Torres, E.I.
Daniel Gunter
12.16.2019

Holding Village - North Lake POST -DEVELOPMENT HYDROLOGY Maria Torres, E.I.
RAP-19000 4 to SCM A Daniel Gunter
12.16.2019
I. SCS CURVE NUMBERS
HSG
Impervious
Open
Wooded
A
98
39
30
B
98
61
55
C
98
74
70
D
98
80
77
Assume:
II. POST -DEVELOPMENT
A. Impervious Breakdown
HSG 'A' = 38.6%
HSG'B'= 0.0%
HSG 'C' = 28.6%
HSG'D'= 32.8%
Cover Condition SCS CN Comments
Impervious 98
Open 62 Assume good condition
Wooded 57 Assume good condition
Contributing Area
# of Units
Area / Unit
Area [sf]
Area [ac]
24-ft (TH) Lot Impervious
0
1,946
0
0.00
W
34-ft Lot Impervious
16
2,850
45,600
1.05
Q
40-ft Lot Impervious
11
3,400
37,400
0.86
J
=
50-ft Lot Impervious
2
3,850
7,700
0.18
C55-ft
Lot Impervious
4
3,850
15,400
0.35
2
75-ft Lot Impervious
1.5
5,850
8,775
0.20
j
Right-of-way Impervious
-
-
103,474
2.38
=
Apartments 80%)
-
230,661
5.30
Totals
34.5
449,010
10.31
B. Watershed Breakdown
* Apartments assumed 80% impervious
Contributing Area
SCS CN
Area sf
Area acres
Comments
Impervious
98
449,010
10.31
Open
62
254,186
5.84
Assume good condition
Wooded
57
92,891
2.13
Assume good condition
Pond
100
18,040
0.41
C. Time of Concentration Information
Time of concentration is assumed to be 5 minutes.
Total area = 18.69 acres
814,127 sq. feet
Composite SCS CN = 82
Impervious = 55.2%
Time of Concentration = 5.00 minutes
SCS Lag Time = 3.00 minutes (SCS Lag = 0.6* Tc)
Time Increment = 0.87 minutes (= 0.29*SCS Lag)

Holding Village - North Lake POST -DEVELOPMENT HYDROLOGY Maria Torres, E.I.
RAP-19000 4 Bypass Daniel Gunter
12.16.2019
I. SCS CURVE NUMBERS
Assume:
HSG
Impervious
Open
Wooded
A
98
39
30
B
98
61
55
C
98
74
70
D
98
80
77
HSG 'A' = 38.6%
HSG 'B' = 0.0%
HSG 'C' = 28.6%
HSG 'D' = 32.8%
Cover Condition
SCS CN
Comments
Impervious
98
Open
62
Assume good condition
Wooded
57
Assume good condition
JJW-DEVELOPMEN
A. Impervious Breakdown
Contributing Area
# of Units
Area Unit
Area [sf]
Area ac
24-ft TH Lot Impervious
0
1,946
0
0.00
w
34-ft Lot Impervious
0
2,850
0
0.00
>z
g
40-ft Lot Impervious
0
3,400
0
0.00
=
50-ft Lot Impervious
7
3,850
26,950
0.62
55-ft Lot Impervious
2.5
3,850
9,625
0.22
Z
75-ft Lot Impervious
3
5,850
17,550
0.40
>
Ri ht-of-wayImpervious
-
-
0
0.00
=
Other
-
0
0.00
Totals
12.5
54,125
1.24
B. Watershed Breakdown
Contributing Area
SCS CN
Areas
Area acres
Comments
Impervious
98
54,125
1.24
Open
62
80,090
1.84
Assume good condition
Wooded
57
82,777
1.90
Assume good condition
Pond
100
0
0.00
Total area =
Composite SCS CN =
% Impervious =
4.98 acres
216,992 sq. feet
69
24.9%

Holding Village - North Lake POST -DEVELOPMENT HYDROLOGY Maria Torres, E.I.
RAP-19000 4 Bypass Daniel Gunter
12.16.2019
C. Time of Concentration Information
Time of concentration is assumed to be 5 minutes.
Segment 1: Overland Flow
Length =
Top Elev=
Bot Elev=
Height =
Slope =
Manning's n =
P (2-year/24-hour) =
Segment Time =
59
270.00
246.00
24
0.4068
0.40
3.45
4.06
ft
ft
ft
ft
ft/ft
wooded
Inches (Wake Forest, NC)
minutes
Segment 2: Channel Flow
Length =
589
Top Elev=
246.00
BotElev=
242.00
Height =
4
Slope =
0.0068
Manning's n =
0.045
Flow Area =
4.00
Wetted Perimeter =
6.00
Channel Velocity =
2.08
Segment Time =
4.71
Time of Concentration = 8.78 minutes
SCS Lag Time = 5.27 minutes (SCS Lag = 0.6* Tc)
Time Increment = 1.53 minutes (= 0.29*SCS Lag)
ft
ft/ft
natural channel
sf (assume 2'w x 2'h channel)
If (assume 2' x 2' channel)
ft/sec
minutes

Holding Village - North Lake POST -DEVELOPMENT HYDROLOGY Maria Torres, E.I.
RAP-19000 5 to SCM 8 Daniel Gunter
12.16.2019
I. SCS CURVE NUMBERS
HSG
Impervious
Open
Wooded
A
98
39
30
B
98
61
55
C
98
74
70
D
98
80
77
Assume:
II. POST -DEVELOPMENT
A. Impervious Breakdown
HSG 'A' = 38.6%
HSG'B'= 0.0%
HSG 'C' = 28.6%
HSG'D'= 32.8%
Cover Condition SCS CN Comments
Impervious 98
Open 62 Assume good condition
Wooded 57 Assume good condition
Contributing Area
# of Units
Area / Unit
Area [sf]
Area [ac]
24-ft (TH) Lot Impervious
10
1,846
18,460
0.42
W
34-ft Lot Impervious
19
2,750
52,250
1.20
Q
40-ft Lot Impervious
9
3,300
29,700
0.68
J
=
50-ft Lot Impervious
7
3,750
26,250
0.60
C55-ft
Lot Impervious
0
3,750
0
0.00
z
75-ft Lot Impervious
0
5,750
0
0.00
j
Right-of-way Impervious
-
-
119,960
2.75
=
Apartments (70%)
-
97,469
2.24
Totals
45
344,089
7.90
B. Watershed Breakdown
Contributing Area
SCS CN
Area sf
Area acres
Comments
Impervious
98
344,089
7.90
Open
62
142,341
3.27
Assume good condition
Wooded
57
67,375
1.55
Assume good condition
Pond
100
11,625
0.27
C. Time of Concentration Information
Time of concentration is assumed to be 5 minutes.
Total area = 12.98 acres
565,430 sq. feet
Composite SCS CN = 84
Impervious = 60.9%
Time of Concentration = 5.00 minutes
SCS Lag Time = 3.00 minutes (SCS Lag = 0.6* Tc)
Time Increment = 0.87 minutes (= 0.29*SCS Lag)

Holding Village - North Lake POST -DEVELOPMENT HYDROLOGY Maria Torres, E.I.
RAP-19000 5 Bypass Daniel Gunter
12.16.2019
I. SCS CURVE NUMBERS
HSG
Impervious
Open
Wooded
A
98
39
30
B
98
61
55
C
98
74
70
D
98
80
77
Assume:
II. POST -DEVELOPMENT
A. Impervious Breakdown
HSG 'A' = 38.6%
HSG'B'= 0.0%
HSG 'C' = 28.6%
HSG'D'= 32.8%
Cover Condition SCS CN Comments
Impervious 98
Open 62 Assume good condition
Wooded 57 Assume good condition
Contributing Area
# of Units
Area / Unit
Area [sf]
Area [ac]
24-ft (TH) Lot Impervious
0
1,946
0
0.00
W
34-ft Lot Impervious
0
2,850
0
0.00
Q
40-ft Lot Impervious
0
3,400
0
0.00
J
=
50-ft Lot Impervious
1.5
3,850
5,775
0.13
C55-ft
Lot Impervious
1.5
3,850
5,775
0.13
z
75-ft Lot Impervious
0
1 5,850
1 0
1 0.00
j
Right-of-way Impervious
-
-
3,354
0.08
=
Other
-
0
0.00
Totals
3
14,904
0.34
B. Watershed Breakdown
Contributing Area
SCS CN
Area sf
Area acres
Comments
Impervious
98
14,904
0.34
Open
62
41,881
0.96
Assume good condition
Wooded
57
67,375
1.55
Assume good condition
Pond
100
0
0.00
Total area =
Composite SCS CN =
Impervious =
2.85 acres
124,160 sq. feet
64
12.0

Holding Village - North Lake POST -DEVELOPMENT HYDROLOGY
RAP-19000 5 Bypass
C. Time of Concentration Information
Time of concentration is assumed to be 5 minutes.
Segment 1: Overland Flow
Segment 2: Concentrated Flow
Length =
100
ft
Length =
24
ft
Top Elev =
302.00
ft
Top Elev =
266.00
ft
Bot Elev =
266.00
ft
Bot Elev =
258.00
ft
Height =
36
ft
Height =
8
ft
Slope =
0.3604
ft/ft
Slope =
0.3333
ft/ft
Manning's n =
0.24
dense grasses
Paved ? =
No
P (2-year/24-hour) =
3.45
inches (Wake For
Velocity =
9.32
ft/sec
Segment Time=
4.32
minutes
Segment Time=
0.04
minutes
Segment 3: Channel Flow
Length =
906
ft
Top Elev =
258.00
Bot Elev =
245.00
Height =
13
ft
Slope =
0.0143
ft/ft
Manning's n =
0.045
natural channel
Flow Area =
8.00
sf (assume 4'w x 2'h channel)
Wetted Perimeter =
8.00
If (assume 4' x 2' channel)
Channel Velocity=
3.97
ft/sec
Segment Time=
3.81
minutes
Time of Concentration = 8.17 minutes
SCS Lag Time = 4.90 minutes (SCS Lag = 0.6* Tc)
Time Increment = 1.42 minutes (= 0.29*SCS Lag)
Maria Torres, E.I.
Daniel Gunter
12.16.2019

Holding Village - North Lake POST -DEVELOPMENT HYDROLOGY Maria Torres, E.I.
RAP-19000 Sub 6 Daniel Gunter
12.16.2019
Assume.,
HSG
Impervious
Open
Wooded
A
98
39
30
B
98
61
55
C
98
74
70
D
98
80
77
HSG 'A' = 38.6%
HSG 'B' = 0.0%
HSG 'C' = 28.6%
HSG 'D' = 32.8%
Cover Condition
SCS CN
Comments
Impervious
98
Open
62
Assume good condition
Wooded
57
Assume good condition
A. Impervious Breakdown
Contributing Area
# of Units
Area / Unit
Area [sf]
Area [ac]
24-ft (TH) Lot Impervious
0
1,946
0
0.00
w
34-ft Lot Impervious
0
2,850
0
0.00
>z
g
40-ft Lot Impervious
0
3,400
0
0.00
=
50-ft Lot Impervious
4.5
3,850
17,325
0.40
55-ft Lot Impervious
0
3,850
0
0.00
Z
75-ft Lot Impervious
0
5,850
0
0.00
>
Right-of-way Impervious
-
-
0
0.00
=
Other
0
0.00
Totals
4.5
17,325
0.40
B. Watershed Breakdown
Contributing Area
SCS CN
Areas
Area acres
Comments
Impervious
98
17,325
0.40
Open
62
22,822
0.52
Assume good condition
Wooded
57
47,146
1.08
Assume good condition
Pond
100
0
0.00
Total area =
Composite SCS CN =
% Impervious =
2.00 acres
87,293 sq. feet
66
19.8%

Holding Village - North Lake POST -DEVELOPMENT HYDROLOGY Maria Torres, E.I.
RAP-19000 Sub 6 Daniel Gunter
12.16.2019
C. Time of Concentration Information
Time of concentration is assumed to be 5 minutes.
Segment 1: Overland Flow
Length =
Top Elev =
Bot Elev =
Height =
Slope =
Manning's n =
P (2-year/24-hour) =
Segment Time =
63
ft
305.50
ft
298.00
ft
7.5
ft
0.1190
ft/ft
0.24
wooded
3.45
inches (Wake Forest, NC)
4.65
minutes
Segment 2: Channel Flow
Length =
801
Top Elev =
298.00
BotElev =
266.00
Height =
32
Slope =
0.0400
Manning's n =
0.045
Flow Area =
6.00
Wetted Perimeter =
7.00
Channel Velocity=
5.97
Segment Time =
2.24
Time of Concentration = 6.89 minutes
SCS Lag Time = 4.13 minutes (SCS Lag = 0.6* Tc)
Time Increment = 1.20 minutes (= 0.29*SCS Lag)
ft
ft
ft/ft
natural channel
sf (assume 3'w x 2'h channel)
If (assume Tx 2' channel)
ft/sec
minutes

Holding Village - North Lake POST -DEVELOPMENT HYDROLOGY Maria Torres, E.I.
RAP-19000 7 to SCM C Daniel Gunter
12.16.2019
I. SCS CURVE NUMBERS
HSG
Impervious
Open
Wooded
A
98
39
30
B
98
61
55
C
98
74
70
D
98
80
77
Assume:
II. POST -DEVELOPMENT
A. Impervious Breakdown
HSG 'A' = 38.6%
HSG'B'= 0.0%
HSG 'C' = 28.6%
HSG'D'= 32.8%
Cover Condition SCS CN Comments
Impervious 98
Open 62 Assume good condition
Wooded 57 Assume good condition
Contributing Area
# of Units
Area / Unit
Area [sf]
Area [ac]
24-ft (TH) Lot Impervious
0
1,946
0
0.00
W
34-ft Lot Impervious
17.5
2,850
49,875
1.14
Q
40-ft Lot Impervious
4
3,400
13,600
0.31
J
=
50-ft Lot Impervious
10
3,850
38,500
0.88
C55-ft
Lot Impervious
3
3,850
11,550
0.27
z
75-ft Lot Impervious
0
5,850
0
0.00
j
Right-of-way Impervious
-
-
105,212
2.42
=
Amenity (10%)
-
2,032
0.05
Totals
34.5
220,769
5.07
B. Watershed Breakdown
Contributing Area
SCS CN
Area sf
Area acres
Comments
Impervious
98
220,769
5.07
Open
62
173,522
3.98
Assume good condition
Wooded
57
0
0.00
Assume good condition
Pond
100
17,453
0.40
C. Time of Concentration Information
Time of concentration is assumed to be 5 minutes.
Total area = 9.45 acres
411,744 sq. feet
Composite SCS CN = 83
Impervious = 53.6%
Time of Concentration = 5.00 minutes
SCS Lag Time = 3.00 minutes (SCS Lag = 0.6* Tc)
Time Increment = 0.87 minutes (= 0.29*SCS Lag)

Holding Village - North Lake POST -DEVELOPMENT HYDROLOGY Maria Torres, E.I.
RAP-19000 7 Byposs Daniel Gunter
12.16.2019
W*41Nltl,tl401111JA104 11
HSG
Impervious
Open
Wooded
A
98
39
30
B
98
61
55
C
98
74
70
D
98
80
77
Assume:
TM201.1 dr];ktl4[i11JAl4'1Y i
A. Impervious Breakdown
HSG 'A' = 38.6%
HSG'B'= 0.0%
HSG 'C' = 28.6%
HSG'D'= 32.8%
Cover Condition SCS CN Comments
Impervious 98
Open 62 Assume good condition
Wooded 57 Assume good condition
Contributing Area
# of Units
Area / Unit
Area [sf]
Area [ac]
24-ft (TH) Lot Impervious
0
1,946
0
0.00
W
34-ft Lot Impervious
0
2,850
0
0.00
Q
40-ft Lot Impervious
0
3,400
0
0.00
J
=
50-ft Lot Impervious
0
3,850
0
0.00
C55-ft
Lot Impervious
0
3,850
0
0.00
z
75-ft Lot Impervious
0
1 5,850
1 0
1 0.00
j
Right-of-way Impervious
-
-
0
0.00
=
Other
-
0
0.00
Totals
0
0
0.00
B. Watershed Breakdown
Contributing Area
SCS CN
Area sf
Area acres
Comments
Impervious
98
0
0.00
Open
62
74,031
1.70
Assume good condition
Wooded
57
37,863
0.87
Assume good condition
Pond
100
0
0.00
Total area =
Composite SCS CN =
Impervious =
2.57 acres
111,894 sq. feet
61
0.0

Holding Village - North Lake POST -DEVELOPMENT HYDROLOGY
RAP-19000 7 Bypass
III. TIME OF CONCENTRATION INFORMATION
Time of concentration is calculated using the SCS Segmental Approach (TR-55).
Segment 1: Overland Flow
Length =
100
Top Elev =
328.00
Bot Elev =
310.00
Height =
18
Slope =
0.1800
Manning's n =
0.40
Z-year/24-hour) =
3.45
Segment Time =
8.59
Time of Concentration =
SCS Lag Time =
ft
ft
ft
ft
ft/ft
wooded
inches (Wake Forest, NC)
minutes
Segment 2: Channel Flow
Length =
656
Top Elev =
310.00
Bot Elev =
297.00
Height =
13
Slope =
0.0198
Manning's n =
0.045
Flow Area =
6.00
Wetted Perimeter=
7.00
Channel Velocity =
4.21
Segment Time =
2.60
11.19 minutes
6.71 minutes (SCS Lag = 0.6* Tc)
Maria Torres, E.I.
Daniel Gunter
12.16.2019
ft
ft/ft
natural channel
sf (assume 3'w x 2'h channel)
If (assume 3' x 2' channel)
ft/sec
minutes

Holding Village - North Lake POST -DEVELOPMENT HYDROLOGY Maria Torres, E.I.
RAP-19000 Reach Daniel Gunter
12.16.2019
Reach 1: Channel Flow
Length =
587
ft
Top Elev =
245.00
Bot Elev =
241.00
Height =
4
ft
Slope =
0.0068
ft/ft
Manning's n =
0.045
natural channel
Flow Area =
12.00
sf (assume 4'w x 3'h channel)
Wetted Perimeter =
12.00
If (assume 4' x 3' channel)
Channel Velocity=
2.73
ft/sec
Segment Time =
3.68
minutes
Reach 2: Channel Flow
Length =
1002
ft
Top Elev =
266.00
Bot Elev =
245.00
Height =
21
ft
Slope =
0.0210
ft/ft
Manning's n =
0.045
natural channel
Flow Area =
8.00
sf (assume 4'w x 2'h channel)
Wetted Perimeter =
8.00
If (assume 4' x 2' channel)
Channel Velocity=
4.79
ft/sec
Segment Time =
3.48
minutes
Reach 3: Channel Flow
Length =
985
ft
Top Elev =
297.00
Bot Elev =
266.00
Height =
31
ft
Slope =
0.0315
ft/ft
Manning's n =
0.045
natural channel
Flow Area =
6.00
sf (assume 3'w x 2'h channel)
Wetted Perimeter =
7.00
If (assume Tx 2' channel)
Channel Velocity=
5.30
ft/sec
Segment Time =
3.10
minutes