YADKI-035 Final Report

DAM HYDRAULIC CAPACITY
ASSESSMENT REPORT
(DRAFT)
DEEP CREEK W/S #30A (PL-566)
YADKI-035
YADKIN COUNTY, NC
PREPARED BY:
WOOD E&I Solutions
2020
EXECUTIVE SUMMARY
A hydraulic capacity analysis was completed for the Deep Creek W/S #30a Dam in Yadkin County,
North Carolina. The purpose of the study was to analyze the existing potential of the dam for
overtopping during predetermined specified rainfall events. The analyses were completed using
the United States Army Corps of Engineers developed software Hydrologic Engineering Center –
Hydrologic Modeling System (HEC-HMS) in combination with Arc-GIS to develop required input
parameters. The rainfall events included in the analyses consist of 24-hour durations with return
periods of 25 years, 50 years, 100 years, 200 years, 500 years, and 1000 years. Results of the
analyses indicate that the structure is hydraulically adequate for the 25 years, 50 years, and 100
years rainfall events. Results of the analyses indicate the structure is over-topped by the 200
years, 500 years, and 1000 years rainfall events. Data, input parameters, and final results can be
found on the attached summary sheets and in the appendices of this report as well as in the
associated electronic file in which all program files are stored.
Drainage Area (Sq. Mi.)=
Curve Number =
Lag Time (min.)=
Rainfall Distribution Methods =
7.5'x2.5' Riser w/30-inch Barrel
Grassed-Lined Trapezoidal Channel
SUMMARY OF INPUT PARAMETERS
2.52
SUMMARY SHEET OF HYDRAULIC CAPACITY RESULTS
DEEP CREEK W/S #30A, YADKI-035
ANALYSIS PERFORMED BY: SURBHI THAKUR, WOOD
TOP OF DAM ELEVATION = 865
24 HOUR - 100 YEAR EVENT, 7.8 INCHES, ELEVATION 864.6 (0.4 FT FREE-BOARD)
24 HOUR - 50 YEAR EVENT, 6.95 INCHES, ELEVATION 864 (1 FT FREE-BOARD)
24 HOUR - 25 YEAR EVENT, 6.14 INCHES, ELEVATION 863.3 (1.7 FT FREE-BOARD)
24 HOUR - 1000 YEAR EVENT, 10.9 INCHES, ELEVATION 865.8 (0.8 FT OVER-TOPPED)
24 HOUR - 500 YEAR EVENT, 9.9 INCHES, ELEVATION 865.6 (0.6 FT OVER-TOPPED)
24 HOUR - 200 YEAR EVENT, 8.68 INCHES, ELEVATION 865.2 (0.2 FT OVER-TOPPED)
860.2
862.3
ELEVATION
843.7
844.2
844.7
74.73
87
SCS Type 2
SPILLWAY
Principal
Auxiliary 1
TYPE ELEVATION
849.2
849.7
850.2
850.7
845.2
845.7
846.2
846.7
847.2
847.7
857.2
857.7
858.2
858.7
859.2
STORAGE (ACRE-FT)
0.0
0.9
2.0
3.2
854.2
854.7
855.2
855.7
856.2
856.7
851.2
851.7
852.2
852.7
853.2
853.7
848.2
848.7
25.7
29.6
33.7
38.1
4.6
6.3
8.3
10.6
13.1
15.8
126.7
136.8
147.5
158.8
ELEVATION
859.7
860.2
860.7
861.2
861.7
76.7
83.7
91.1
99.2
107.9
117.1
42.8
47.6
52.8
58.3
64.1
70.2
18.8
22.1
STORAGE (ACRE-FT)
170.6
183.0
196.0
209.6
223.8
238.6
871.2
871.7
868.2
868.7
869.2
869.7
870.2
870.7
865.2
865.7
866.2
866.7
867.2
867.7
862.2
862.7
863.2
253.9
269.8
286.3
303.5
321.2
339.7
874.2
874.7
875.0
872.2
872.7
873.2
873.7
863.7
864.2
864.7
809.2
828.5
NOT TO SCALE
634.7
661.8
689.6
718.2
747.6
777.9
485.9
509.2
533.1
557.6
582.6
608.3
358.8
378.5
398.8
419.6
441.1
463.2
DEEP CREEK W/S #30A YADKI-035 SEPTEMBER 18, 2020
APPENDIX A
Watershed Boundary
Sources: Esri, HERE, Garmin, USGS, Intermap, INCREMENT P,NRCan, Esri Japan, METI, Esri China (Hong Kong), Esri Korea,Esri (Thailand), NGCC, (c) OpenStreetMap contributors, and theGIS User Community
Deep Creek- YADKI-035 - Watershed Boundary
Legend
Longest Flowpath
Watershed
0 0.5 10.25 Miles
Date: 9/10/2020
/Drainage Area: 2.53 Square MilesFlowpath Length: 3.34 Miles

APPENDIX B
Lag Time Calculation

Dam No:Yadki-035 Date:9/3/2020
Dam Name:Deep Creek W/S #30a Engineer:S. Thakur
Maximum Potential Retention (inches):S =(1000/cn')-10
Time of Concentration (hours):Tc =l0.8*(S+1)0.7
1140*Y0.5
Basin Data:Input Values in yellow
Curve Number CN =74.73 from NRCS CN
S =3.38151 in.
Mean Basin Slope Y =6.45134 %
Longest Flowpath:3.34183 mi.
Flow Length l =17644.9 ft.
Time of Concentration Tc =2.42 Hours Tc =145 mins
Lag Time TL =1.45 Hours TL =87 mins

APPENDIX C
NRCS Curve Number Summary Sheet

Change CN according to TR-55 (see tables below)
NLCD (2016) Landuse TR-55 Landuse HSG A (sq. ft.)CN HSG B (sq. ft.)CN HSG C (sq. ft.)CN HSG D (sq. ft.)CN
Open Water Not Available 0 100 0 48946 100 4894591 21729 100 2172919 45572 100 4557189
Developed, Open Space Open space - Fair condition (grass cover 50% to 75%)0 49 0 4086030 69 281936074 5633650 79 445058365 168269 84 14134616
Developed, Low Intensity Residential districts by average lot size: 1/3 acre 0 57 0 2007559 72 144544283 2106552 81 170630681 80408 86 6915077
Developed, Medium Intensity Residential districts by average lot size: 1/8 acre 0 77 0 338868 85 28803783 240938 90 21684463 5290 92 486634
Developed, High Intensity Urban districts - Commercial and business 0 89 0 159510 92 14674890 31829 94 2991941 5331 95 506477
Barren Land Newly graded areas 0 77 0 0 86 31 7520 91 684357 2166 94 203646
Deciduous Forest Woods - Fair 0 36 0 9270490 60 556229416 4260575 73 311021966 1690509 79 133550216
Evergreen Forest Woods - Fair 0 36 0 86303 60 5178175 78381 73 5721804 0 79 0
Mixed Forest Woods - Fair 0 36 0 1400729 60 84043756 1282554 73 93626472 279951 79 22116166
Shrub/Scrub Brush - Fair 0 35 0 62581 56 3504516 5 70 361 8773 77 675485
Herbaceuous Herbaceuous - Fair 0 60 0 616614 71 43779574 235300 81 19059319 66970 89 5960325
Hay/Pasture Pasture - Fair 0 49 0 9687116 69 668411031 10984857 79 867803717 1020512 84 85723037
Cultivated Crops Row crops (SR + CR) - Poor 0 71 0 6085808 80 486864642 8013946 87 697213266 165991 90 14939175
Woody Wetlands Not Available 0 80 0 4869 85 413861 7184 90 646532 113881 95 10818742
Emergent Herbaceuous Wetlands Not Available 0 80 0 0 85 0 0 90 0 0 95 0 Weighted CN=74.73196
NOTE: Curve Numbers are from SCS TR-55 with the exception of assumed HSG A (CN=60) for Herbaceous,Open Water, Woody Wetlands, and Emergent Herbaceous Wetlands.
NOTE: double-check all the land types are being calculated and texts are accurate
NOTE: double-check the exported attribute table has the same table format as the "Export_Output" table

APPENDIX D

Hyetograph Results Used for Analyses
0.0
2.0
4.0
6.0
8.0
10.0
12.0
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24Cumulative Depth (in)Time (hrs)
Hyetographs for 24-Hour SCS Type II Rainfall Distributions
25YR
50YR
100YR
200YR
500YR
1000YR

APPENDIX E
NOAA Atlas 14 Rainfall Table

Point precipitation frequency estimates (inches)
NOAA Atlas 14 Volume 2 Version 3
Data type: Precipitation depth
Time series type: Partial duration
Project area: Ohio River Basin
Location name (ESRI Maps): Yadkinville, North Carolina USA
Station Name: -
Latitude: 36.1245°
Longitude: -80.6907°
Elevation (USGS): None None
PRECIPITATION FREQUENCY ESTIMATES
by
duration
for ARI
(years):1 2 5 10 25 50 100 200 500 1000
5-min:0.356 0.422 0.499 0.554 0.62 0.666 0.71 0.751 0.799 0.834
10-min:0.569 0.675 0.799 0.885 0.988 1.06 1.13 1.19 1.26 1.31
15-min:0.711 0.849 1.01 1.12 1.25 1.34 1.43 1.5 1.59 1.65
30-min:0.975 1.17 1.44 1.62 1.86 2.02 2.18 2.34 2.53 2.67
60-min:1.22 1.47 1.84 2.11 2.47 2.74 3.01 3.28 3.63 3.9
2-hr:1.44 1.74 2.2 2.54 3.01 3.37 3.74 4.11 4.62 5.02
3-hr:1.55 1.88 2.37 2.75 3.27 3.69 4.11 4.54 5.14 5.62
6-hr:1.92 2.32 2.92 3.4 4.04 4.56 5.09 5.65 6.41 7.01
12-hr:2.35 2.84 3.58 4.16 4.96 5.6 6.26 6.95 7.92 8.68
24-hr:2.85 3.46 4.39 5.12 6.14 6.95 7.8 8.68 9.9 10.9
2-day:3.38 4.08 5.12 5.93 7.04 7.91 8.81 9.73 11 12
3-day:3.6 4.33 5.41 6.25 7.39 8.3 9.23 10.2 11.5 12.5
4-day:3.81 4.59 5.7 6.57 7.75 8.69 9.64 10.6 12 13
7-day:4.36 5.22 6.37 7.26 8.45 9.39 10.3 11.3 12.6 13.6
10-day:4.99 5.96 7.17 8.1 9.33 10.3 11.2 12.2 13.5 14.5
20-day:6.7 7.93 9.38 10.5 12 13.1 14.3 15.5 17 18.2
30-day:8.32 9.79 11.3 12.4 13.9 14.9 16 17 18.3 19.3
45-day:10.5 12.3 13.9 15.2 16.7 17.9 19 20 21.4 22.4
60-day:12.5 14.6 16.4 17.7 19.5 20.7 21.9 23.1 24.6 25.7
Date/time (GMT): Tue Jun 23 11:44:25 2020
pyRunTime: 0.0178411006927

APPENDIX F
Outlet Works Rating Curves

Total outlet discharge from the spillway system
Client: NCEM Date: 9/18/2020
Project: Overtopping Study Engineer: S. Thakur
Dam: Deep Creek W/S #30a Dam No. YADKI-035
Reservior Water
Level (RWS)
Elevation (ft)
Primary spillway
discharge (cfs)
(from HydroCAD)
Emergency spillway
discharge (cfs)
(from HydroCAD)
Total discharge from the
spillway system (cfs)
843.7 0.0 0.0 0.0
844.4 3.5 0.0 3.5
845.1 7.8 0.0 7.8
845.8 10.3 0.0 10.3
846.5 12.4 0.0 12.4
847.2 14.1 0.0 14.1
847.9 15.6 0.0 15.6
848.6 17.1 0.0 17.1
849.3 18.3 0.0 18.3
850.0 19.6 0.0 19.6
850.7 20.7 0.0 20.7
851.4 21.8 0.0 21.8
852.1 22.8 0.0 22.8
852.8 23.8 0.0 23.8
853.5 24.7 0.0 24.7
854.2 25.6 0.0 25.6
854.9 26.5 0.0 26.5
855.6 27.4 0.0 27.4
856.3 28.2 0.0 28.2
857.0 29.0 0.0 29.0
857.7 29.8 0.0 29.8
858.4 30.5 0.0 30.5
859.1 31.3 0.0 31.3
859.8 32.0 0.0 32.0
860.5 40.9 0.0 40.9
861.2 85.6 0.0 85.6
861.9 123.5 0.0 123.5
862.6 124.9 70.2 195.1
863.3 126.3 290.0 416.3
864.0 127.6 609.5 737.1
864.7 129.0 1000.1 1129.0
865.4 130.3 1448.9 1579.2
866.1 131.6 1948.0 2079.6
866.8 133.0 2491.6 2624.5
867.5 134.3 3075.2 3209.5
868.2 135.5 3695.4 3831.0
868.9 136.8 4349.3 4486.1
869.6 138.1 5034.3 5172.4
870.3 139.3 5748.3 5887.6
871.0 140.6 6489.4 6630.0
871.7 141.8 7255.9 7397.8
872.4 143.0 8046.4 8189.4
873.1 144.2 8859.4 9003.7
873.8 145.4 9693.8 9839.2
874.5 146.6 10548.2 10694.9
0.0
2000.0
4000.0
6000.0
8000.0
10000.0
12000.0
840.0 845.0 850.0 855.0 860.0 865.0 870.0 875.0 880.0Total discharge from the spillway system (cfs)Reservior Water Level (RWS) Elevation (ft)
The Whole Spillway System Rating Curve (cfs)