20201340 Ver 2_Morphological Data_20231208

1100 Old English Court, Raleigh
Existing Conditions Morphological Data:
Cross sections of the channel were taken to quantify the morphological data. Two sections were taken
upstream of the repair area, three sections within the repair area and three sections downstream. The
cross sections obtained were comprised of both riffle and pool sections. The data was collected to
establish bankfull channel characteristics shown in Table B and quantify the stream slope, 0.010 ft/ft.
The eastern floodplain is wooded, and stream bank is generally stable within the repair area. The
western floodplain is inaccessible to flood flow due to fill and is also wooded south of the 90-degree
bend. The north western bank is wooded however the floodplain has less vegetation due to the
proximity of the house and the associated yard.
The watershed to the project site has a drainage area of approximately 0.56 square miles. The regional
curve data for a watershed of this size is listed in Table A.
Table A: Piedmont Regional Curve Data
Bankfull Urban Curves Rural Curves
Area (Sq Ft) ' 41.4 (30-80) 14.9 (7-28)
Width (Ft) 20.1 (16-36) 11.8 (5.8-22)
Depth (Ft) 2.0 (1.4-3.5) 1.4 (0.8-2)
Discharge (Cfs) 212.9 (160-380) 60.7 (20-180)
The project reach within the repair area classified as slightly entrenched E4/C4 stream. The following
morphological data included in Table B, was obtained from surveyed cross sections at riffle locations.
The morphological cross sections and longitudinal profile data are attached.
Table B: Site Morphological Data
Cross Slope
Section (ft/ft)
Wbkf Abkf
(ft) (sgft)
dbkf
(ft)
dmax bkf
(ft)
Qbkf
(cfs)
W/D
ER
1 (Riffle) 0.013 11.89
28.33
2.38
2.71
145.94
4.99
18.89
2 (Riffle) 0.019
13.11
28.72
2.19
2.70
216.38
5.99
16.37
3 (Run)
0.019
13.98
36.38
2.60
3.76
5.37
15.67
4 (Pool)
0.000
19.84
38.42
1.94
4.21
10.25
23.60
5 (Riffle) 0.023 15.52
28.67
1.85
2.39 274.12 8.40
9.09
1
Timmons Group 1100 Old English Court
Supplemental Information, PCN Applications

6 (Pool) 0.000
30.80
75.11
2.44
4.62
12.63
5.91
7 (Riffle) 0.020
12.92
30.22
2.34
2.78
240.55
5.53
16.75
The site morphological data falls within the data range for the urban curves as listed in Table A.
Timmons Group 1100 Old English Court
Supplemental Information, PCN Applications

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